WorldWideScience

Sample records for strength model hypotheses

  1. Sleep regulation: physiological models and hypotheses.

    Science.gov (United States)

    Borbély, A A

    1995-06-01

    The elucidation of sleep regulation is not an easy task. On one side, there is a multitude of solid yet disparate data, on the other side, the topic is tempting for engaging in wild speculation, particularly with respect to the functions of sleep. Models may exert a moderating influence by mediating between the two extremes. However, also they navigate between the risk of banality in reformulating the obvious, and the peril of fancy in losing touch with empirical reality.

  2. Political market orientation and strategic party postures: Some hypotheses regarding profiles and relationship strengths

    DEFF Research Database (Denmark)

    Ormrod, Robert P.; Henneberg, Stephan C. M.

    2007-01-01

    an integrated construct of political marketing strategy which is exemplified by the derivation of hypotheses of the relationships between organizational stances on the one hand, and attitudinal and behavioural aspects of political market orientation on the other. We propose two levels of hypotheses: Firstly......Recently, the areas of strategic political marketing as well as political market orientation have been the subject of several conceptual articles (e.g., Henneberg 2006a; O'Cass 1996; Ormrod 2005, 2007). These have laid the theoretical foundations for further empirical work (e.g., Henneberg 2006b; O......'Cass 1996, 2001a, 2001b; Ormrod et al. 2007; Ormrod and Henneberg 2008 forthcoming). However, despite the close conceptual relatedness between some of these concepts they have yet to be integrated to provide a more nuanced picture which researchers but also political marketing practitioners can utilise...

  3. Testing hypotheses involving Cronbach's alpha using marginal models

    NARCIS (Netherlands)

    Kuijpers, R.E.; van der Ark, L.A.; Croon, M.A.

    2013-01-01

    We discuss the statistical testing of three relevant hypotheses involving Cronbach's alpha: one where alpha equals a particular criterion; a second testing the equality of two alpha coefficients for independent samples; and a third testing the equality of two alpha coefficients for dependent

  4. Pursuing the method of multiple working hypotheses for hydrological modeling

    NARCIS (Netherlands)

    Clark, M.P.; Kavetski, D.; Fenicia, F.

    2011-01-01

    Ambiguities in the representation of environmental processes have manifested themselves in a plethora of hydrological models, differing in almost every aspect of their conceptualization and implementation. The current overabundance of models is symptomatic of an insufficient scientific understanding

  5. Ontological Analysis of Integrated Process Models: testing hypotheses

    Directory of Open Access Journals (Sweden)

    Michael Rosemann

    2001-11-01

    Full Text Available Integrated process modeling is achieving prominence in helping to document and manage business administration and IT processes in organizations. The ARIS framework is a popular example for a framework of integrated process modeling not least because it underlies the 800 or more reference models embedded in the world's most popular ERP package, SAP R/3. This paper demonstrates the usefulness of the Bunge-Wand-Weber (BWW representation model for evaluating modeling grammars such as those constituting ARIS. It reports some initial insights gained from pilot testing Green and Rosemann's (2000 evaluative propositions. Even when considering all five views of ARIS, modelers have problems representing business rules, the scope and boundary of systems, and decomposing models. However, even though it is completely ontologically redundant, users still find the function view useful in modeling.

  6. Improving data analysis in herpetology: Using Akaike's information criterion (AIC) to assess the strength of biological hypotheses

    Science.gov (United States)

    Mazerolle, M.J.

    2006-01-01

    In ecology, researchers frequently use observational studies to explain a given pattern, such as the number of individuals in a habitat patch, with a large number of explanatory (i.e., independent) variables. To elucidate such relationships, ecologists have long relied on hypothesis testing to include or exclude variables in regression models, although the conclusions often depend on the approach used (e.g., forward, backward, stepwise selection). Though better tools have surfaced in the mid 1970's, they are still underutilized in certain fields, particularly in herpetology. This is the case of the Akaike information criterion (AIC) which is remarkably superior in model selection (i.e., variable selection) than hypothesis-based approaches. It is simple to compute and easy to understand, but more importantly, for a given data set, it provides a measure of the strength of evidence for each model that represents a plausible biological hypothesis relative to the entire set of models considered. Using this approach, one can then compute a weighted average of the estimate and standard error for any given variable of interest across all the models considered. This procedure, termed model-averaging or multimodel inference, yields precise and robust estimates. In this paper, I illustrate the use of the AIC in model selection and inference, as well as the interpretation of results analysed in this framework with two real herpetological data sets. The AIC and measures derived from it is should be routinely adopted by herpetologists. ?? Koninklijke Brill NV 2006.

  7. Skin Stem Cell Hypotheses and Long Term Clone Survival - Explored Using Agent-based Modelling

    OpenAIRE

    Li, X.; Upadhyay, A.K.; Bullock, A.J.; Dicolandrea, T.; Xu, J.; Binder, R.L.; Robinson, M.K.; Finlay, D.R.; Mills, K.J.; Bascom, C.C.; Kelling, C.K.; Isfort, R.J.; Haycock, J.W.; MacNeil, S.; Smallwood, R.H.

    2013-01-01

    Epithelial renewal in skin is achieved by the constant turnover and differentiation of keratinocytes. Three popular hypotheses have been proposed to explain basal keratinocyte regeneration and epidermal homeostasis: 1) asymmetric division (stem-transit amplifying cell); 2) populational asymmetry (progenitor cell with stochastic fate); and 3) populational asymmetry with stem cells. In this study, we investigated lineage dynamics using these hypotheses with a 3D agent-based model of the epiderm...

  8. Modeling of Sylgard Adhesive Strength

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Ralph Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-03

    Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.

  9. Statistical analysis of hypotheses on the cointegrating relations in the I(2) model

    DEFF Research Database (Denmark)

    Johansen, Søren

    2006-01-01

    The cointegrated vector autoregressive model for I(2) variables is a non-linear parametric restriction on the linear I(2) regression model for variables of order I(0), I(1) and I(2). In this paper we discuss non-linear submodels given by smooth parametrizations. We give conditions on the parametr......) and the reformulation is applied to show that some hypotheses on the cointegrating coefficients in the cointegrated I(2) model give asymptotic ¿² inference....

  10. Mechanistic Mathematical Modeling Tests Hypotheses of the Neurovascular Coupling in fMRI.

    Directory of Open Access Journals (Sweden)

    Karin Lundengård

    2016-06-01

    Full Text Available Functional magnetic resonance imaging (fMRI measures brain activity by detecting the blood-oxygen-level dependent (BOLD response to neural activity. The BOLD response depends on the neurovascular coupling, which connects cerebral blood flow, cerebral blood volume, and deoxyhemoglobin level to neuronal activity. The exact mechanisms behind this neurovascular coupling are not yet fully investigated. There are at least three different ways in which these mechanisms are being discussed. Firstly, mathematical models involving the so-called Balloon model describes the relation between oxygen metabolism, cerebral blood volume, and cerebral blood flow. However, the Balloon model does not describe cellular and biochemical mechanisms. Secondly, the metabolic feedback hypothesis, which is based on experimental findings on metabolism associated with brain activation, and thirdly, the neurotransmitter feed-forward hypothesis which describes intracellular pathways leading to vasoactive substance release. Both the metabolic feedback and the neurotransmitter feed-forward hypotheses have been extensively studied, but only experimentally. These two hypotheses have never been implemented as mathematical models. Here we investigate these two hypotheses by mechanistic mathematical modeling using a systems biology approach; these methods have been used in biological research for many years but never been applied to the BOLD response in fMRI. In the current work, model structures describing the metabolic feedback and the neurotransmitter feed-forward hypotheses were applied to measured BOLD responses in the visual cortex of 12 healthy volunteers. Evaluating each hypothesis separately shows that neither hypothesis alone can describe the data in a biologically plausible way. However, by adding metabolism to the neurotransmitter feed-forward model structure, we obtained a new model structure which is able to fit the estimation data and successfully predict new

  11. "On Clocks and Clouds:" Confirming and Interpreting Climate Models as Scientific Hypotheses (Invited)

    Science.gov (United States)

    Donner, L.

    2009-12-01

    The certainty of climate change projected under various scenarios of emissions using general circulation models is an issue of vast societal importance. Unlike numerical weather prediction, a problem to which general circulation models are also applied, projected climate changes usually lie outside of the range of external forcings for which the models generating these changes have been directly evaluated. This presentation views climate models as complex scientific hypotheses and thereby frames these models within a well-defined process of both advancing scientific knowledge and recognizing its limitations. Karl Popper's Logik der Forschung (The Logic of Scientific Discovery, 1934) and 1965 essay “On Clocks and Clouds” capture well the methodologies and challenges associated with constructing climate models. Indeed, the process of a problem situation generating tentative theories, refined by error elimination, characterizes aptly the routine of general circulation model development. Limitations on certainty arise from the distinction Popper perceived in types of natural processes, which he exemplified by clocks, capable of exact measurement, and clouds, subject only to statistical approximation. Remarkably, the representation of clouds in general circulation models remains the key uncertainty in understanding atmospheric aspects of climate change. The asymmetry of hypothesis falsification by negation and much vaguer development of confidence in hypotheses consistent with some of their implications is an important practical challenge to confirming climate models. The presentation will discuss the ways in which predictions made by climate models for observable aspects of the present and past climate can be regarded as falsifiable hypotheses. The presentation will also include reasons why “passing” these tests does not provide complete confidence in predictions about the future by climate models. Finally, I will suggest that a “reductionist” view, in

  12. Skin Stem Cell Hypotheses and Long Term Clone Survival – Explored Using Agent-based Modelling

    Science.gov (United States)

    Li, X.; Upadhyay, A. K.; Bullock, A. J.; Dicolandrea, T.; Xu, J.; Binder, R. L.; Robinson, M. K.; Finlay, D. R.; Mills, K. J.; Bascom, C. C.; Kelling, C. K.; Isfort, R. J.; Haycock, J. W.; MacNeil, S.; Smallwood, R. H.

    2013-01-01

    Epithelial renewal in skin is achieved by the constant turnover and differentiation of keratinocytes. Three popular hypotheses have been proposed to explain basal keratinocyte regeneration and epidermal homeostasis: 1) asymmetric division (stem-transit amplifying cell); 2) populational asymmetry (progenitor cell with stochastic fate); and 3) populational asymmetry with stem cells. In this study, we investigated lineage dynamics using these hypotheses with a 3D agent-based model of the epidermis. The model simulated the growth and maintenance of the epidermis over three years. The offspring of each proliferative cell was traced. While all lineages were preserved in asymmetric division, the vast majority were lost when assuming populational asymmetry. The third hypothesis provided the most reliable mechanism for self-renewal by preserving genetic heterogeneity in quiescent stem cells, and also inherent mechanisms for skin ageing and the accumulation of genetic mutation. PMID:23712735

  13. Skin stem cell hypotheses and long term clone survival--explored using agent-based modelling.

    Science.gov (United States)

    Li, X; Upadhyay, A K; Bullock, A J; Dicolandrea, T; Xu, J; Binder, R L; Robinson, M K; Finlay, D R; Mills, K J; Bascom, C C; Kelling, C K; Isfort, R J; Haycock, J W; MacNeil, S; Smallwood, R H

    2013-01-01

    Epithelial renewal in skin is achieved by the constant turnover and differentiation of keratinocytes. Three popular hypotheses have been proposed to explain basal keratinocyte regeneration and epidermal homeostasis: 1) asymmetric division (stem-transit amplifying cell); 2) populational asymmetry (progenitor cell with stochastic fate); and 3) populational asymmetry with stem cells. In this study, we investigated lineage dynamics using these hypotheses with a 3D agent-based model of the epidermis. The model simulated the growth and maintenance of the epidermis over three years. The offspring of each proliferative cell was traced. While all lineages were preserved in asymmetric division, the vast majority were lost when assuming populational asymmetry. The third hypothesis provided the most reliable mechanism for self-renewal by preserving genetic heterogeneity in quiescent stem cells, and also inherent mechanisms for skin ageing and the accumulation of genetic mutation.

  14. Amazon rainforest responses to elevated CO2: Deriving model-based hypotheses for the AmazonFACE experiment

    Science.gov (United States)

    Rammig, A.; Fleischer, K.; Lapola, D.; Holm, J.; Hoosbeek, M.

    2017-12-01

    Increasing atmospheric CO2 concentration is assumed to have a stimulating effect ("CO2 fertilization effect") on forest growth and resilience. Empirical evidence, however, for the existence and strength of such a tropical CO2 fertilization effect is scarce and thus a major impediment for constraining the uncertainties in Earth System Model projections. The implications of the tropical CO2 effect are far-reaching, as it strongly influences the global carbon and water cycle, and hence future global climate. In the scope of the Amazon Free Air CO2 Enrichment (FACE) experiment, we addressed these uncertainties by assessing the CO2 fertilization effect at ecosystem scale. AmazonFACE is the first FACE experiment in an old-growth, highly diverse tropical rainforest. Here, we present a priori model-based hypotheses for the experiment derived from a set of 12 ecosystem models. Model simulations identified key uncertainties in our understanding of limiting processes and derived model-based hypotheses of expected ecosystem responses to elevated CO2 that can directly be tested during the experiment. Ambient model simulations compared satisfactorily with in-situ measurements of ecosystem carbon fluxes, as well as carbon, nitrogen, and phosphorus stocks. Models consistently predicted an increase in photosynthesis with elevated CO2, which declined over time due to developing limitations. The conversion of enhanced photosynthesis into biomass, and hence ecosystem carbon sequestration, varied strongly among the models due to different assumptions on nutrient limitation. Models with flexible allocation schemes consistently predicted an increased investment in belowground structures to alleviate nutrient limitation, in turn accelerating turnover rates of soil organic matter. The models diverged on the prediction for carbon accumulation after 10 years of elevated CO2, mainly due to contrasting assumptions in their phosphorus cycle representation. These differences define the expected

  15. On the use of uncertainty analyses to test hypotheses regarding deterministic model predictions of environmental processes

    International Nuclear Information System (INIS)

    Gilbert, R.O.; Bittner, E.A.; Essington, E.H.

    1995-01-01

    This paper illustrates the use of Monte Carlo parameter uncertainty and sensitivity analyses to test hypotheses regarding predictions of deterministic models of environmental transport, dose, risk and other phenomena. The methodology is illustrated by testing whether 238 Pu is transferred more readily than 239+240 Pu from the gastrointestinal (GI) tract of cattle to their tissues (muscle, liver and blood). This illustration is based on a study wherein beef-cattle grazed for up to 1064 days on a fenced plutonium (Pu)-contaminated arid site in Area 13 near the Nevada Test Site in the United States. Periodically, cattle were sacrificed and their tissues analyzed for Pu and other radionuclides. Conditional sensitivity analyses of the model predictions were also conducted. These analyses indicated that Pu cattle tissue concentrations had the largest impact of any model parameter on the pdf of predicted Pu fractional transfers. Issues that arise in conducting uncertainty and sensitivity analyses of deterministic models are discussed. (author)

  16. Why Victory in the War on Cancer Remains Elusive: Biomedical Hypotheses and Mathematical Models

    Directory of Open Access Journals (Sweden)

    Leonid Hanin

    2011-01-01

    Full Text Available We discuss philosophical, methodological, and biomedical grounds for the traditional paradigm of cancer and some of its critical flaws. We also review some potentially fruitful approaches to understanding cancer and its treatment. This includes the new paradigm of cancer that was developed over the last 15 years by Michael Retsky, Michael Baum, Romano Demicheli, Isaac Gukas, William Hrushesky and their colleagues on the basis of earlier pioneering work of Bernard Fisher and Judah Folkman. Next, we highlight the unique and pivotal role of mathematical modeling in testing biomedical hypotheses about the natural history of cancer and the effects of its treatment, elaborate on model selection criteria, and mention some methodological pitfalls. Finally, we describe a specific mathematical model of cancer progression that supports all the main postulates of the new paradigm of cancer when applied to the natural history of a particular breast cancer patient and fit to the observables.

  17. ITSSOIN Hypotheses

    NARCIS (Netherlands)

    Anheier, H.K.; Krlev, G.; Preuss, S.; Mildenberger, G.; Bekkers, R.H.F.P.; Brink Lund, A.

    2014-01-01

    This report brings together findings from the first ITSSOIN project working steps to formulate empirically testable hypotheses on the impact of the third sector and social innovation – in particular regarding the role of the third sector in generating social innovation but also with reference to

  18. Use of Computational Modeling to Evaluate Hypotheses About the Molecular and Cellular Mechanisms of Bystander Effects

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuchao; Conolly, Rory B; Andersen, Melvin E.

    2006-11-21

    This report describes the development of a computational systems biology approach to evaluate the hypotheses of molecular and cellular mechanisms of adaptive response to low dose ionizing radiation. Our concept is that computational models of signaling pathways can be developed and linked to biologically based dose response models to evaluate the underlying molecular mechanisms which lead to adaptive response. For development of quantitatively accurate, predictive models, it will be necessary to describe tissues consisting of multiple cell types where the different types each contribute in their own way to the overall function of the tissue. Such a model will probably need to incorporate not only cell type-specific data but also spatial information on the architecture of the tissue and on intercellular signaling. The scope of the current model was more limited. Data obtained in a number of different biological systems were synthesized to describe a chimeric, “average” population cell. Biochemical signaling pathways involved in sensing of DNA damage and in the activation of cell cycle checkpoint controls and the apoptotic path were also included. As with any computational modeling effort, it was necessary to develop these simplified initial descriptions (models) that can be iteratively refined. This preliminary model is a starting point which, with time, can evolve to a level of refinement where large amounts of detailed biological information are synthesized and a capability for robust predictions of dose- and time-response behaviors is obtained.

  19. Modelling desiccation cracking in a homogenous soil clay layer: comparison between different hypotheses on constitutive behaviour

    Directory of Open Access Journals (Sweden)

    Jommi Cristina

    2016-01-01

    Full Text Available Desiccation cracks are usually thought to start from the surface of an evaporating soil layer, and the available simplified models for crack initiation and propagation are based on this hypothesis. On the contrary, experimental results on a Dutch river clay showed that cracks in an evaporating soil layer may start and propagate below the surface, confirming earlier findings by other researchers. A simple one-dimensional model was set up to analyse the consequences of different hypotheses about the material behaviour on the crack onset in a homogenous soil layer undergoing surface drying. The results of the model show that dependence of the material behaviour on the rate of water content change is a necessary requirement for cracks to initiate below the surface. The conclusion suggests that, to properly understand cracking in an evaporating soil layer, an intrinsic time scale for the mechanical response must be accounted for, among all the other factors which were previously highlighted by other researchers. The key factor to predict crack onset below the surface is the dependence of the drying branch of the water retention curve of the compressible soil on the rate of drying, which would be justified by a rate dependent fabric evolution.

  20. Emergence of nutrient limitation in tropical dry forests: hypotheses from simulation models

    Science.gov (United States)

    Medvigy, D.; Waring, B. G.; Xu, X.; Trierweiler, A.; Werden, L. K.; Wang, G.; Zhu, Q.; Powers, J. S.

    2017-12-01

    It is unclear to what extent tropical dry forest productivity may be limited by nutrients. Direct assessment of nutrient limitation through fertilization experiments has been rare, and paradigms pertaining to other ecosystems may not extend to tropical dry forests. For example, because dry tropical forests have a lower water supply than moist tropical forests, dry forests can have lower decomposition rates, higher soil carbon and nitrogen concentrations, and a more open nitrogen cycle than moist forests. We used a mechanistic, numerical model to generate hypotheses about nutrient limitation in tropical dry forests. The model dynamically couples ED2 (vegetation dynamics), MEND (biogeochemistry), and N-COM (plant-microbe competition for nutrients). Here, the MEND-component of the model has been extended to include nitrogen (N) and phosphorus (P) cycles. We focus on simulation of sixteen 25m x 25m plots in Costa Rica where a fertilization experiment has been underway since 2015. Baseline simulations are characterized by both nitrogen and phosphorus limitation of vegetation. Fertilization with N and P increased vegetation biomass, with N fertilization having a somewhat stronger effect. Nutrient limitation was also sensitive to climate and was more pronounced during drought periods. Overflow respiration was identified as a key process that mitigated nutrient limitation. These results suggest that, despite often having richer soils than tropical moist forests, tropical dry forests can also become nutrient-limited. If the climate becomes drier in the next century, as is expected for Central America, drier soils may decrease microbial activity and exacerbate nutrient limitation. The importance of overflow respiration underscores the need for appropriate treatment of microbial dynamics in ecosystem models. Ongoing and new nutrient fertilization experiments will present opportunities for testing whether, and how, nutrient limitation may indeed be emerging in tropical dry

  1. What drove reversions to quadrupedality in ornithischian dinosaurs? Testing hypotheses using centre of mass modelling.

    Science.gov (United States)

    Maidment, Susannah C R; Henderson, Donald M; Barrett, Paul M

    2014-11-01

    The exceptionally rare transition to quadrupedalism from bipedal ancestors occurred on three independent occasions in ornithischian dinosaurs. The possible driving forces behind these transitions remain elusive, but several hypotheses-including the development of dermal armour and the expansion of head size and cranial ornamentation-have been proposed to account for this major shift in stance. We modelled the position of the centre of mass (CoM) in several exemplar ornithischian taxa and demonstrate that the anterior shifts in CoM position associated with the development of an enlarged skull ornamented with horns and frills for display/defence may have been one of the drivers promoting ceratopsian quadrupedality. A posterior shift in CoM position coincident with the development of extensive dermal armour in thyreophorans demonstrates this cannot have been a primary causative mechanism for quadrupedality in this clade. Quadrupedalism developed in response to different selective pressures in each ornithischian lineage, indicating different evolutionary pathways to convergent quadrupedal morphology.

  2. Coopersmith Self-Esteem: Two Different Hypothesized Factor Models--Both Acceptable for the Same Data Structure.

    Science.gov (United States)

    Hofmann, Rich; Sherman, Larry

    Using data from 135 sixth-, seventh-, and eighth-graders between 11 and 15 years old attending a middle school in a suburban Southwest Ohio school district, two hypothesized models of the factor structures for the Coopersmith Self-Esteem Inventory were tested. One model represents the original Coopersmith factor structure, and the other model is…

  3. Use of hypotheses for analysis of variance Models: Challenging the current practice

    NARCIS (Netherlands)

    van Wesel, F.; Boeije, H.R.; Hoijtink, H

    2013-01-01

    In social science research, hypotheses about group means are commonly tested using analysis of variance. While deemed to be formulated as specifically as possible to test social science theory, they are often defined in general terms. In this article we use two studies to explore the current

  4. Numerical Model of High Strength Concrete

    Science.gov (United States)

    Wang, R. Z.; Wang, C. Y.; Lin, Y. L.

    2018-03-01

    The purpose of this paper is to present a three-dimensional constitutive model based on the concept of equivalent uniaxial strain. closed Menetrey-Willam (CMW) failure surfaces which combined with Menetrey-Willam meridian and the cap model are introduced in this paper. Saenz stress-strain model is applied and adjusted by the ultimate strength parameters from CMW failure surface to reflect the latest stress or strain condition. The high strength concrete (HSC) under tri-axial non-proportional loading is considered and the model in this paper performed a good prediction.

  5. A Decentralized Approach to the Formulation of Hypotheses: A Hierarchical Structural Model for a Prion Self-Assembled System

    Science.gov (United States)

    Wang, Mingyang; Zhang, Feifei; Song, Chao; Shi, Pengfei; Zhu, Jin

    2016-07-01

    Innovation in hypotheses is a key transformative driver for scientific development. The conventional centralized hypothesis formulation approach, where a dominant hypothesis is typically derived from a primary phenomenon, can, inevitably, impose restriction on the range of conceivable experiments and legitimate hypotheses, and ultimately impede understanding of the system of interest. We report herein the proposal of a decentralized approach for the formulation of hypotheses, through initial preconception-free phenomenon accumulation and subsequent reticular logical reasoning processes. The two-step approach can provide an unbiased, panoramic view of the system and as such should enable the generation of a set of more coherent and therefore plausible hypotheses. As a proof-of-concept demonstration of the utility of this open-ended approach, a hierarchical model has been developed for a prion self-assembled system, allowing insight into hitherto elusive static and dynamic features associated with this intriguing structure.

  6. [A Structural Equation Model on Family Strength of Married Working Women].

    Science.gov (United States)

    Hong, Yeong Seon; Han, Kuem Sun

    2015-12-01

    The purpose of this study was to identify the effect of predictive factors related to family strength and develop a structural equation model that explains family strength among married working women. A hypothesized model was developed based on literature reviews and predictors of family strength by Yoo. This constructed model was built of an eight pathway form. Two exogenous variables included in this model were ego-resilience and family support. Three endogenous variables included in this model were functional couple communication, family stress and family strength. Data were collected using a self-report questionnaire from 319 married working women who were 30~40 of age and lived in cities of Chungnam province in Korea. Data were analyzed with PASW/WIN 18.0 and AMOS 18.0 programs. Family support had a positive direct, indirect and total effect on family strength. Family stress had a negative direct, indirect and total effect on family strength. Functional couple communication had a positive direct and total effect on family strength. These predictive variables of family strength explained 61.8% of model. The results of the study show a structural equation model for family strength of married working women and that predicting factors for family strength are family support, family stress, and functional couple communication. To improve family strength of married working women, the results of this study suggest nursing access and mediative programs to improve family support and functional couple communication, and reduce family stress.

  7. Speech Motor Development in Childhood Apraxia of Speech : Generating Testable Hypotheses by Neurocomputational Modeling

    NARCIS (Netherlands)

    Terband, H.; Maassen, B.

    2010-01-01

    Childhood apraxia of speech (CAS) is a highly controversial clinical entity, with respect to both clinical signs and underlying neuromotor deficit. In the current paper, we advocate a modeling approach in which a computational neural model of speech acquisition and production is utilized in order to

  8. Speech motor development in childhood apraxia of speech: generating testable hypotheses by neurocomputational modeling.

    NARCIS (Netherlands)

    Terband, H.R.; Maassen, B.A.M.

    2010-01-01

    Childhood apraxia of speech (CAS) is a highly controversial clinical entity, with respect to both clinical signs and underlying neuromotor deficit. In the current paper, we advocate a modeling approach in which a computational neural model of speech acquisition and production is utilized in order to

  9. From single molecule fluctuations to muscle contraction: a Brownian model of A.F. Huxley's hypotheses.

    Directory of Open Access Journals (Sweden)

    Lorenzo Marcucci

    Full Text Available Muscular force generation in response to external stimuli is the result of thermally fluctuating, cyclical interactions between myosin and actin, which together form the actomyosin complex. Normally, these fluctuations are modelled using transition rate functions that are based on muscle fiber behaviour, in a phenomenological fashion. However, such a basis reduces the predictive power of these models. As an alternative, we propose a model which uses direct single molecule observations of actomyosin fluctuations reported in the literature. We precisely estimate the actomyosin potential bias and use diffusion theory to obtain a brownian ratchet model that reproduces the complete cross-bridge cycle. The model is validated by simulating several macroscopic experimental conditions, while its interpretation is compatible with two different force-generating scenarios.

  10. Rényi statistics for testing composite hypotheses in general exponential models

    Czech Academy of Sciences Publication Activity Database

    Morales, D.; Pardo, L.; Pardo, M. C.; Vajda, Igor

    2004-01-01

    Roč. 38, č. 2 (2004), s. 133-147 ISSN 0233-1888 R&D Projects: GA ČR GA201/02/1391 Grant - others:BMF(ES) 2003-00892; BMF(ES) 2003-04820 Institutional research plan: CEZ:AV0Z1075907 Keywords : natural exponential models * Levy processes * generalized Wald statistics Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.323, year: 2004

  11. Postglacial recolonization at a snail's pace (Trochulus villosus): confronting competing refugia hypotheses using model selection.

    Science.gov (United States)

    Dépraz, A; Cordellier, M; Hausser, J; Pfenninger, M

    2008-05-01

    The localization of Last Glacial Maximum (LGM) refugia is crucial information to understand a species' history and predict its reaction to future climate changes. However, many phylogeographical studies often lack sampling designs intensive enough to precisely localize these refugia. The hairy land snail Trochulus villosus has a small range centred on Switzerland, which could be intensively covered by sampling 455 individuals from 52 populations. Based on mitochondrial DNA sequences (COI and 16S), we identified two divergent lineages with distinct geographical distributions. Bayesian skyline plots suggested that both lineages expanded at the end of the LGM. To find where the origin populations were located, we applied the principles of ancestral character reconstruction and identified a candidate refugium for each mtDNA lineage: the French Jura and Central Switzerland, both ice-free during the LGM. Additional refugia, however, could not be excluded, as suggested by the microsatellite analysis of a population subset. Modelling the LGM niche of T. villosus, we showed that suitable climatic conditions were expected in the inferred refugia, but potentially also in the nunataks of the alpine ice shield. In a model selection approach, we compared several alternative recolonization scenarios by estimating the Akaike information criterion for their respective maximum-likelihood migration rates. The 'two refugia' scenario received by far the best support given the distribution of genetic diversity in T. villosus populations. Provided that fine-scale sampling designs and various analytical approaches are combined, it is possible to refine our necessary understanding of species responses to environmental changes.

  12. Genomic outlier profile analysis: mixture models, null hypotheses, and nonparametric estimation.

    Science.gov (United States)

    Ghosh, Debashis; Chinnaiyan, Arul M

    2009-01-01

    In most analyses of large-scale genomic data sets, differential expression analysis is typically assessed by testing for differences in the mean of the distributions between 2 groups. A recent finding by Tomlins and others (2005) is of a different type of pattern of differential expression in which a fraction of samples in one group have overexpression relative to samples in the other group. In this work, we describe a general mixture model framework for the assessment of this type of expression, called outlier profile analysis. We start by considering the single-gene situation and establishing results on identifiability. We propose 2 nonparametric estimation procedures that have natural links to familiar multiple testing procedures. We then develop multivariate extensions of this methodology to handle genome-wide measurements. The proposed methodologies are compared using simulation studies as well as data from a prostate cancer gene expression study.

  13. 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.

  14. Stigma models: Testing hypotheses of how images of Nevada are acquired and values are attached to them

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins-Smith, H.C. [New Mexico Univ., Albuquerque, NM (United States)

    1994-12-01

    This report analyzes data from surveys on the effects that images associated with nuclear power and waste (i.e., nuclear images) have on people`s preference to vacation in Nevada. The analysis was stimulated by a model of imagery and stigma which assumes that information about a potentially hazardous facility generates signals that elicit negative images about the place in which it is located. Individuals give these images negative values (valences) that lessen their desire to vacation, relocate, or retire in that place. The model has been used to argue that the proposed Yucca Mountain high-level nuclear waste repository could elicit images of nuclear waste that would stigmatize Nevada and thus impose substantial economic losses there. This report proposes a revised model that assumes that the acquisition and valuation of images depend on individuals` ideological and cultural predispositions and that the ways in which new images will affect their preferences and behavior partly depend on these predispositions. The report tests these hypotheses: (1) individuals with distinct cultural and ideological predispositions have different propensities for acquiring nuclear images, (2) these people attach different valences to these images, (3) the variations in these valences are important, and (4) the valences of the different categories of images within an individual`s image sets for a place correlate very well. The analysis largely confirms these hypotheses, indicating that the stigma model should be revised to (1) consider the relevant ideological and cultural predispositions of the people who will potentially acquire and attach value to the image, (2) specify the kinds of images that previously attracted people to the host state, and (3) consider interactions between the old and potential new images of the place. 37 refs., 18 figs., 17 tabs.

  15. Stigma models: Testing hypotheses of how images of Nevada are acquired and values are attached to them

    International Nuclear Information System (INIS)

    Jenkins-Smith, H.C.

    1994-12-01

    This report analyzes data from surveys on the effects that images associated with nuclear power and waste (i.e., nuclear images) have on people's preference to vacation in Nevada. The analysis was stimulated by a model of imagery and stigma which assumes that information about a potentially hazardous facility generates signals that elicit negative images about the place in which it is located. Individuals give these images negative values (valences) that lessen their desire to vacation, relocate, or retire in that place. The model has been used to argue that the proposed Yucca Mountain high-level nuclear waste repository could elicit images of nuclear waste that would stigmatize Nevada and thus impose substantial economic losses there. This report proposes a revised model that assumes that the acquisition and valuation of images depend on individuals' ideological and cultural predispositions and that the ways in which new images will affect their preferences and behavior partly depend on these predispositions. The report tests these hypotheses: (1) individuals with distinct cultural and ideological predispositions have different propensities for acquiring nuclear images, (2) these people attach different valences to these images, (3) the variations in these valences are important, and (4) the valences of the different categories of images within an individual's image sets for a place correlate very well. The analysis largely confirms these hypotheses, indicating that the stigma model should be revised to (1) consider the relevant ideological and cultural predispositions of the people who will potentially acquire and attach value to the image, (2) specify the kinds of images that previously attracted people to the host state, and (3) consider interactions between the old and potential new images of the place. 37 refs., 18 figs., 17 tabs

  16. Why Be a Shrub? A Basic Model and Hypotheses for the Adaptive Values of a Common Growth Form

    Science.gov (United States)

    Götmark, Frank; Götmark, Elin; Jensen, Anna M.

    2016-01-01

    Shrubs are multi-stemmed short woody plants, more widespread than trees, important in many ecosystems, neglected in ecology compared to herbs and trees, but currently in focus due to their global expansion. We present a novel model based on scaling relationships and four hypotheses to explain the adaptive significance of shrubs, including a review of the literature with a test of one hypothesis. Our model describes advantages for a small shrub compared to a small tree with the same above-ground woody volume, based on larger cross-sectional stem area, larger area of photosynthetic tissue in bark and stem, larger vascular cambium area, larger epidermis (bark) area, and larger area for sprouting, and faster production of twigs and canopy. These components form our Hypothesis 1 that predicts higher growth rate for a small shrub than a small tree. This prediction was supported by available relevant empirical studies (14 publications). Further, a shrub will produce seeds faster than a tree (Hypothesis 2), multiple stems in shrubs insure future survival and growth if one or more stems die (Hypothesis 3), and three structural traits of short shrub stems improve survival compared to tall tree stems (Hypothesis 4)—all hypotheses have some empirical support. Multi-stemmed trees may be distinguished from shrubs by more upright stems, reducing bending moment. Improved understanding of shrubs can clarify their recent expansion on savannas, grasslands, and alpine heaths. More experiments and other empirical studies, followed by more elaborate models, are needed to understand why the shrub growth form is successful in many habitats. PMID:27507981

  17. Dynamic multistate site occupancy models to evaluate hypotheses relevant to conservation of Golden Eagles in Denali National Park, Alaska

    Science.gov (United States)

    Martin, Julien; McIntyre, Carol L.; Hines, James E.; Nichols, James D.; Schmutz, Joel A.; MacCluskie, Margaret C.

    2009-01-01

    The recent development of multistate site occupancy models offers great opportunities to frame and solve decision problems for conservation that can be viewed in terms of site occupancy. These models have several characteristics (e.g., they account for detectability) that make them particularly well suited for addressing management and conservation problems. We applied multistate site occupancy models to evaluate hypotheses related to the conservation and management of Golden Eagles (Aquila chrysaetos) in Denali National Park, Alaska, and provided estimates of transition probabilities among three occupancy states for nesting areas (occupied with successful reproduction, occupied with unsuccessful reproduction, and unoccupied). Our estimation models included the effect of potential recreational activities (hikers) and environmental covariates such as a snowshoe hare (Lepus americanus) index on transition probabilities among the three occupancy states. Based on the most parsimonious model, support for the hypothesis of an effect of potential human disturbance on site occupancy dynamics was equivocal. There was some evidence that potential human disturbance negatively affected local colonization of territories, but there was no evidence of an effect on reproductive performance parameters. In addition, models that assume a positive relationship between the hare index and successful reproduction were well supported by the data. The statistical approach that we used is particularly useful to parameterize management models that can then be used to make optimal decisions related to the management of Golden Eagles in Denali. Although in our case we were particularly interested in managing recreational activities, we believe that such models should be useful to for a broad class of management and conservation problems.

  18. Short-term Periodization Models: Effects on Strength and Speed-strength Performance.

    Science.gov (United States)

    Hartmann, Hagen; Wirth, Klaus; Keiner, Michael; Mickel, Christoph; Sander, Andre; Szilvas, Elena

    2015-10-01

    Dividing training objectives into consecutive phases to gain morphological adaptations (hypertrophy phase) and neural adaptations (strength and power phases) is called strength-power periodization (SPP). These phases differ in program variables (volume, intensity, and exercise choice or type) and use stepwise intensity progression and concomitant decreasing volume, converging to peak intensity (peaking phase). Undulating periodization strategies rotate these program variables in a bi-weekly, weekly, or daily fashion. The following review addresses the effects of different short-term periodization models on strength and speed-strength both with subjects of different performance levels and with competitive athletes from different sports who use a particular periodization model during off-season, pre-season, and in-season conditioning. In most periodization studies, it is obvious that the strength endurance sessions are characterized by repetition zones (12-15 repetitions) that induce muscle hypertrophy in persons with a low performance level. Strictly speaking, when examining subjects with a low training level, many periodization studies include mainly hypertrophy sessions interspersed with heavy strength/power sessions. Studies have demonstrated equal or statistically significant higher gains in maximal strength for daily undulating periodization compared with SPP in subjects with a low to moderate performance level. The relatively short intervention period and the lack of concomitant sports conditioning call into question the practical value of these findings for competitive athletes. Possibly owing to differences in mesocycle length, conditioning programs, and program variables, competitive athletes either maintained or improved strength and/or speed-strength performance by integrating daily undulating periodization and SPP during off-season, pre-season and in-season conditioning. In high-performance sports, high-repetition strength training (>15) should be

  19. Global model for the lithospheric strength and effective elastic thickness

    OpenAIRE

    Magdala Tesauro; Mikhail Kaban; S. A. P. L. Cloetingh

    2013-01-01

    Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young modulus (E) within the lithosphere. In view of the large uncertainties affecting strength estimates, we evaluate global strength and Te distributions for possible end-member ‘hard’ (HRM) and a ‘soft’ (SR...

  20. College Chemistry Students' Mental Models of Acids and Acid Strength

    Science.gov (United States)

    McClary, LaKeisha; Talanquer, Vicente

    2011-01-01

    The central goal of this study was to characterize the mental models of acids and acid strength expressed by advanced college chemistry students when engaged in prediction, explanation, and justification tasks that asked them to rank chemical compounds based on their relative acid strength. For that purpose we completed a qualitative research…

  1. STOCHASTIC MODELING OF COMPRESSIVE STRENGTH OF PHOSPHORUS SLAG CONTENT CEMENT

    Directory of Open Access Journals (Sweden)

    Ali Allahverdi

    2016-07-01

    Full Text Available One of the common methods for quick determination of compressive strength as one of the most important properties for assessment of cement quality is to apply various modeling approaches. This study is aimed at finding a model for estimating the compressive strength of phosphorus slag content cements. For this purpose, the compressive strengths of chemically activated high phosphorus slag content cement prepared from phosphorus slag (80 wt.%, Portland cement (14 wt.% and a compound chemical activator containing sodium sulfate and anhydrite (6 wt.% were measured at various Blaine finenesses and curing times. Based on the obtained results, a primary stochastic model in terms of curing time and Blaine fineness has been developed. Then, another different dataset was used to incorporate composition variable including weight fractions of phosphorus slag, cement, and activator in the model. This model can be effectively used to predict the compressive strength of phosphorus slag content cements at various Blaine finenesses, curing times, and compositions.

  2. Properties of hypothesis testing techniques and (Bayesian) model selection for exploration-based and theory-based (order-restricted) hypotheses

    NARCIS (Netherlands)

    Kuiper, Rebecca M.; Nederhoff, Tim; Klugkist, Irene

    2015-01-01

    In this paper, the performance of six types of techniques for comparisons of means is examined. These six emerge from the distinction between the method employed (hypothesis testing, model selection using information criteria, or Bayesian model selection) and the set of hypotheses that is

  3. A Strength Model and Service Envelope for PBX 9501

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-02-05

    An analytical method is proposed for making an assessment of the severity of the response of PBX 9501 in structural response simulations. The approach is based on the coherent use of a strength model and a failure criterion. The strength model is based on a creep rupture function and an associated cumulative damage model. The material's residual strength at any time during a simulation of structural response is determined by taking into account both the actual stress history up to that time, and a hypothetical continuation of the applied stresses that are assumed to grow until material failure results. The residual strength is used by the failure criterion to define the region of safe (non-failed) material response. The Mohr-Coulomb failure criterion is chosen for its general applicability to materials with both cohesive and frictional strength. The combined use of the residual strength model and the failure criterion provides a quantitative method of assessing the severity of the response of PBX 9501 material in structural simulations: the proximity of any evolving, general state of stress to the failure surface (which shrinks due to the cumulative damage caused by the past stress history) can be calculated and used as a measure of margin to failure. The strength model has been calibrated to a broad range of uniaxial tension and compression tests, and a small set of creep tests, and is applicable to a broad range of loading conditions.

  4. Review of probabilistic models of the strength of composite materials

    International Nuclear Information System (INIS)

    Sutherland, L.S.; Guedes Soares, C.

    1997-01-01

    The available literature concerning probabilistic models describing the strength of composite materials has been reviewed to highlight the important aspects of this behaviour which will be of interest to the modelling and analysis of a complex system. The success with which these theories have been used to predict experimental results has been discussed. Since the brittle reinforcement phase largely controls the strength of composites, the probabilistic theories used to describe the strength of brittle materials, fibres and bundles of fibres have been detailed. The use of these theories to predict the strength of composite materials has been considered, along with further developments incorporating the damage accumulation observed in the failure of such materials. Probabilistic theories of the strength of short-fibre composites have been outlined. Emphasis has been placed throughout on straightforward engineering explanations of these theories and how they may be used, rather than providing comprehensive statistical descriptions

  5. Properties of hypothesis testing techniques and (Bayesian) model selection for exploration-based and theory-based (order-restricted) hypotheses.

    Science.gov (United States)

    Kuiper, Rebecca M; Nederhoff, Tim; Klugkist, Irene

    2015-05-01

    In this paper, the performance of six types of techniques for comparisons of means is examined. These six emerge from the distinction between the method employed (hypothesis testing, model selection using information criteria, or Bayesian model selection) and the set of hypotheses that is investigated (a classical, exploration-based set of hypotheses containing equality constraints on the means, or a theory-based limited set of hypotheses with equality and/or order restrictions). A simulation study is conducted to examine the performance of these techniques. We demonstrate that, if one has specific, a priori specified hypotheses, confirmation (i.e., investigating theory-based hypotheses) has advantages over exploration (i.e., examining all possible equality-constrained hypotheses). Furthermore, examining reasonable order-restricted hypotheses has more power to detect the true effect/non-null hypothesis than evaluating only equality restrictions. Additionally, when investigating more than one theory-based hypothesis, model selection is preferred over hypothesis testing. Because of the first two results, we further examine the techniques that are able to evaluate order restrictions in a confirmatory fashion by examining their performance when the homogeneity of variance assumption is violated. Results show that the techniques are robust to heterogeneity when the sample sizes are equal. When the sample sizes are unequal, the performance is affected by heterogeneity. The size and direction of the deviations from the baseline, where there is no heterogeneity, depend on the effect size (of the means) and on the trend in the group variances with respect to the ordering of the group sizes. Importantly, the deviations are less pronounced when the group variances and sizes exhibit the same trend (e.g., are both increasing with group number). © 2014 The British Psychological Society.

  6. Assessing the accuracy of subject-specific, muscle-model parameters determined by optimizing to match isometric strength.

    Science.gov (United States)

    DeSmitt, Holly J; Domire, Zachary J

    2016-12-01

    Biomechanical models are sensitive to the choice of model parameters. Therefore, determination of accurate subject specific model parameters is important. One approach to generate these parameters is to optimize the values such that the model output will match experimentally measured strength curves. This approach is attractive as it is inexpensive and should provide an excellent match to experimentally measured strength. However, given the problem of muscle redundancy, it is not clear that this approach generates accurate individual muscle forces. The purpose of this investigation is to evaluate this approach using simulated data to enable a direct comparison. It is hypothesized that the optimization approach will be able to recreate accurate muscle model parameters when information from measurable parameters is given. A model of isometric knee extension was developed to simulate a strength curve across a range of knee angles. In order to realistically recreate experimentally measured strength, random noise was added to the modeled strength. Parameters were solved for using a genetic search algorithm. When noise was added to the measurements the strength curve was reasonably recreated. However, the individual muscle model parameters and force curves were far less accurate. Based upon this examination, it is clear that very different sets of model parameters can recreate similar strength curves. Therefore, experimental variation in strength measurements has a significant influence on the results. Given the difficulty in accurately recreating individual muscle parameters, it may be more appropriate to perform simulations with lumped actuators representing similar muscles.

  7. Investigation of stress–strain models for confined high strength ...

    Indian Academy of Sciences (India)

    High strength concrete; confined concrete; stress–strain models; ... One of its advantages is the lessening column cross-sectional areas. It was ..... Ahmad S H, Shah S P 1982 Stress–strain curves of concrete confined by spiral reinforcement.

  8. models for predicting compressive strength and water absorption

    African Journals Online (AJOL)

    user

    presents a mathematical model for predicting the compressive strength and water absorption of laterite-quarry dust cement block using ... building and construction of new infrastructure and .... In (6), R is a vector containing the real ratios of the.

  9. Testing hypotheses in order

    OpenAIRE

    Paul R. Rosenbaum

    2008-01-01

    In certain circumstances, one wishes to test one hypothesis only if certain other hypotheses have been rejected. This ordering of hypotheses simplifies the task of controlling the probability of rejecting any true hypothesis. In an example from an observational study, a treated group is shown to be further from both of two control groups than the two control groups are from each other. Copyright 2008, Oxford University Press.

  10. Models for predicting compressive strength and water absorption of ...

    African Journals Online (AJOL)

    This work presents a mathematical model for predicting the compressive strength and water absorption of laterite-quarry dust cement block using augmented Scheffe's simplex lattice design. The statistical models developed can predict the mix proportion that will yield the desired property. The models were tested for lack of ...

  11. Micromechanical modelling of mechanical behaviour and strength of wood

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Qing, Hai

    2008-01-01

    An overview of the micromechanical theoretical and numerical models of wood is presented. Different methods of analysis of the effects of wood microstructures at different scale levels on the mechanical behaviour, deformation and strength of wood are discussed and compared. Micromechanical models...

  12. A Review of Consequences of Poverty on Economic Decision-Making: A Hypothesized Model of a Cognitive Mechanism

    OpenAIRE

    Adamkovič, Matúš; Martončik, Marcel

    2017-01-01

    This review focuses on the issue of poverty affecting economic decision-making. By critically evaluating existing studies, the authors propose a structural model detailing the cognitive mechanism involved in how poverty negatively impacts economic decision-making, and explores evidence supporting the basis for the formation of this model. The suggested mechanism consists of a relationship between poverty and four other factors: (1) cognitive load (e.g., experiencing negative affect and stress...

  13. Social deprivation and burden of influenza: Testing hypotheses and gaining insights from a simulation model for the spread of influenza

    Directory of Open Access Journals (Sweden)

    Ayaz Hyder

    2015-06-01

    Full Text Available Factors associated with the burden of influenza among vulnerable populations have mainly been identified using statistical methodologies. Complex simulation models provide mechanistic explanations, in terms of spatial heterogeneity and contact rates, while controlling other factors and may be used to better understand statistical patterns and, ultimately, design optimal population-level interventions. We extended a sophisticated simulation model, which was applied to forecast epidemics and validated for predictive ability, to identify mechanisms for the empirical relationship between social deprivation and the burden of influenza. Our modeled scenarios and associated epidemic metrics systematically assessed whether neighborhood composition and/or spatial arrangement could qualitatively replicate this empirical relationship. We further used the model to determine consequences of local-scale heterogeneities on larger scale disease spread. Our findings indicated that both neighborhood composition and spatial arrangement were critical to qualitatively match the empirical relationship of interest. Also, when social deprivation was fully included in the model, we observed lower age-based attack rates and greater delay in epidemic peak week in the most socially deprived neighborhoods. Insights from simulation models complement current understandings from statistical-based association studies. Additional insights from our study are: (1 heterogeneous spatial arrangement of neighborhoods is a necessary condition for simulating observed disparities in the burden of influenza and (2 unmeasured factors may lead to a better quantitative match between simulated and observed rate ratio in the burden of influenza between the most and least socially deprived populations.

  14. Hypothesized diprotomeric enzyme complex supported by stochastic modelling of palytoxin-induced Na/K pump channels.

    Science.gov (United States)

    Vilallonga, Gabriel D; de Almeida, Antônio-Carlos G; Ribeiro, Kelison T; Campos, Sergio V A; Rodrigues, Antônio M

    2018-03-01

    The sodium-potassium pump (Na + /K + pump) is crucial for cell physiology. Despite great advances in the understanding of this ionic pumping system, its mechanism is not completely understood. We propose the use of a statistical model checker to investigate palytoxin (PTX)-induced Na + /K + pump channels. We modelled a system of reactions representing transitions between the conformational substates of the channel with parameters, concentrations of the substates and reaction rates extracted from simulations reported in the literature, based on electrophysiological recordings in a whole-cell configuration. The model was implemented using the UPPAAL-SMC platform. Comparing simulations and probabilistic queries from stochastic system semantics with experimental data, it was possible to propose additional reactions to reproduce the single-channel dynamic. The probabilistic analyses and simulations suggest that the PTX-induced Na + /K + pump channel functions as a diprotomeric complex in which protein-protein interactions increase the affinity of the Na + /K + pump for PTX.

  15. A Review of Consequences of Poverty on Economic Decision-Making: A Hypothesized Model of a Cognitive Mechanism

    Directory of Open Access Journals (Sweden)

    Matúš Adamkovič

    2017-10-01

    Full Text Available This review focuses on the issue of poverty affecting economic decision-making. By critically evaluating existing studies, the authors propose a structural model detailing the cognitive mechanism involved in how poverty negatively impacts economic decision-making, and explores evidence supporting the basis for the formation of this model. The suggested mechanism consists of a relationship between poverty and four other factors: (1 cognitive load (e.g., experiencing negative affect and stress; (2 executive functions (e.g., attention, working memory, and self-control; (3 intuition/deliberation in decision-making; and (4 economic decision-making (e.g., time-discounting and risk preference, with a final addition of financial literacy as a covariate. This paper focuses on shortfalls in published research, and delves further into the proposed model.

  16. A Review of Consequences of Poverty on Economic Decision-Making: A Hypothesized Model of a Cognitive Mechanism.

    Science.gov (United States)

    Adamkovič, Matúš; Martončik, Marcel

    2017-01-01

    This review focuses on the issue of poverty affecting economic decision-making. By critically evaluating existing studies, the authors propose a structural model detailing the cognitive mechanism involved in how poverty negatively impacts economic decision-making, and explores evidence supporting the basis for the formation of this model. The suggested mechanism consists of a relationship between poverty and four other factors: (1) cognitive load (e.g., experiencing negative affect and stress); (2) executive functions (e.g., attention, working memory, and self-control); (3) intuition/deliberation in decision-making; and (4) economic decision-making (e.g., time-discounting and risk preference), with a final addition of financial literacy as a covariate. This paper focuses on shortfalls in published research, and delves further into the proposed model.

  17. Testing hypotheses in an I(2) model with applications to the persistent long swings in the Dmk/$ rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings...... components in the I(2) model is discussed at some length. Model specification and tests are illustrated with an empirical analysis of long and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two...... in nominal exchange rates, typical in periods of floating exchange rates....

  18. Global model for the lithospheric strength and effective elastic thickness

    Science.gov (United States)

    Tesauro, Magdala; Kaban, Mikhail K.; Cloetingh, Sierd A. P. L.

    2013-08-01

    Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young modulus (E) within the lithosphere. In view of the large uncertainties affecting strength estimates, we evaluate global strength and Te distributions for possible end-member 'hard' (HRM) and a 'soft' (SRM) rheology models of the continental crust. Temperature within the lithosphere has been estimated using a recent tomography model of Ritsema et al. (2011), which has much higher horizontal resolution than previous global models. Most of the strength is localized in the crust for the HRM and in the mantle for the SRM. These results contribute to the long debates on applicability of the "crème brulée" or "jelly-sandwich" model for the lithosphere structure. Changing from the SRM to HRM turns most of the continental areas from the totally decoupled mode to the fully coupled mode of the lithospheric layers. However, in the areas characterized by a high thermal regime and thick crust, the layers remain decoupled even for the HRM. At the same time, for the inner part of the cratons the lithospheric layers are coupled in both models. Therefore, rheological variations lead to large changes in the integrated strength and Te distribution in the regions characterized by intermediate thermal conditions. In these areas temperature uncertainties have a greater effect, since this parameter principally determines rheological behavior. Comparison of the Te estimates for both models with those determined from the flexural loading and spectral analysis shows that the 'hard' rheology is likely applicable for cratonic areas, whereas the 'soft' rheology is more representative for young orogens.

  19. Modelling of tension stiffening for normal and high strength concrete

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1998-01-01

    form the model is extended to apply to biaxial stress fields as well. To determine the biaxial stress field, the theorem of minimum complementary elastic energy is used. The theory has been compared with tests on rods, disks, and beams of both normal and high strength concrete, and very good results...

  20. Global model for the lithospheric strength and effective elastic thickness

    NARCIS (Netherlands)

    Tesauro, M.; Kaban, M.K.; Cloetingh, S.A.P.L.

    2013-01-01

    Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young

  1. Identifying the connective strength between model parameters and performance criteria

    Directory of Open Access Journals (Sweden)

    B. Guse

    2017-11-01

    Full Text Available In hydrological models, parameters are used to represent the time-invariant characteristics of catchments and to capture different aspects of hydrological response. Hence, model parameters need to be identified based on their role in controlling the hydrological behaviour. For the identification of meaningful parameter values, multiple and complementary performance criteria are used that compare modelled and measured discharge time series. The reliability of the identification of hydrologically meaningful model parameter values depends on how distinctly a model parameter can be assigned to one of the performance criteria. To investigate this, we introduce the new concept of connective strength between model parameters and performance criteria. The connective strength assesses the intensity in the interrelationship between model parameters and performance criteria in a bijective way. In our analysis of connective strength, model simulations are carried out based on a latin hypercube sampling. Ten performance criteria including Nash–Sutcliffe efficiency (NSE, Kling–Gupta efficiency (KGE and its three components (alpha, beta and r as well as RSR (the ratio of the root mean square error to the standard deviation for different segments of the flow duration curve (FDC are calculated. With a joint analysis of two regression tree (RT approaches, we derive how a model parameter is connected to different performance criteria. At first, RTs are constructed using each performance criterion as the target variable to detect the most relevant model parameters for each performance criterion. Secondly, RTs are constructed using each parameter as the target variable to detect which performance criteria are impacted by changes in the values of one distinct model parameter. Based on this, appropriate performance criteria are identified for each model parameter. In this study, a high bijective connective strength between model parameters and performance criteria

  2. Testing Hypotheses in an I(2) Model with Applications to the Persistent Long Swings in the Dmk/$ Rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate...... that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates...

  3. Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters.

    Science.gov (United States)

    Chowdhury, S; Maniar, A; Suganya, O M

    2015-11-01

    In this study, Wood Ash (WA) prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength) of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45) and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20%) including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM), strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

  4. Strength development in concrete with wood ash blended cement and use of soft computing models to predict strength parameters

    Directory of Open Access Journals (Sweden)

    S. Chowdhury

    2015-11-01

    Full Text Available In this study, Wood Ash (WA prepared from the uncontrolled burning of the saw dust is evaluated for its suitability as partial cement replacement in conventional concrete. The saw dust has been acquired from a wood polishing unit. The physical, chemical and mineralogical characteristics of WA is presented and analyzed. The strength parameters (compressive strength, split tensile strength and flexural strength of concrete with blended WA cement are evaluated and studied. Two different water-to-binder ratio (0.4 and 0.45 and five different replacement percentages of WA (5%, 10%, 15%, 18% and 20% including control specimens for both water-to-cement ratio is considered. Results of compressive strength, split tensile strength and flexural strength showed that the strength properties of concrete mixture decreased marginally with increase in wood ash contents, but strength increased with later age. The XRD test results and chemical analysis of WA showed that it contains amorphous silica and thus can be used as cement replacing material. Through the analysis of results obtained in this study, it was concluded that WA could be blended with cement without adversely affecting the strength properties of concrete. Also using a new statistical theory of the Support Vector Machine (SVM, strength parameters were predicted by developing a suitable model and as a result, the application of soft computing in structural engineering has been successfully presented in this research paper.

  5. Testing statistical hypotheses

    CERN Document Server

    Lehmann, E L

    2005-01-01

    The third edition of Testing Statistical Hypotheses updates and expands upon the classic graduate text, emphasizing optimality theory for hypothesis testing and confidence sets. The principal additions include a rigorous treatment of large sample optimality, together with the requisite tools. In addition, an introduction to the theory of resampling methods such as the bootstrap is developed. The sections on multiple testing and goodness of fit testing are expanded. The text is suitable for Ph.D. students in statistics and includes over 300 new problems out of a total of more than 760. E.L. Lehmann is Professor of Statistics Emeritus at the University of California, Berkeley. He is a member of the National Academy of Sciences and the American Academy of Arts and Sciences, and the recipient of honorary degrees from the University of Leiden, The Netherlands and the University of Chicago. He is the author of Elements of Large-Sample Theory and (with George Casella) he is also the author of Theory of Point Estimat...

  6. Johnson - Cook Strength Models for Mild and DP 590 Steels

    International Nuclear Information System (INIS)

    Vedantam, K.; Brar, N. S.; Bajaj, D.; Hill, S.

    2006-01-01

    Automotive steels, Mild and Dual Phase590 (DP590) are characterized in tension at room temperature, using the quasi-static and split Hopkinson bar techniques at various strain rates ranging from ∼10-3/s to ∼1800/s. Tension stress-strain data for both the steels are analyzed to determine the Johnson-Cook Strength model constants, J-C strength model constants for mild steel are A=217 MPa, B = 234 MPa, n = 0.643 and C = 0.076 and for DP590 steel are A = 430 MPa, B = 824 MPa, n = 0.510 and C = 0.017. Higher value of strain rate sensitivity constant C for mild steel (0.076) compared to DP 590 (0.017) is also reflected in the stress- strain data at various strain rates

  7. The emergence of cooperation in tie strength models

    International Nuclear Information System (INIS)

    Xu, Bo; Yue, Yunpeng

    2016-01-01

    In this paper, we propose a tie strength model to explain the emergence of cooperation in spatial prisoner's dilemma games, assuming that cooperators preferentially allocate their investments to friends with strong ties. Two types of prisoner's dilemma models are examined in this study: the traditional two-strategy model considering only cooperators and defectors; the expanded three-strategy model consisting cooperators, defectors and extortioners. The results show that tie strength model contributes to the promotion of cooperation in both types of prisoner's dilemma games. However, we point out that the influence of the investment preference is quite different in the two prisoner's dilemma game settings. In the two-strategy prisoner's dilemma game, only small preference contributes to the promotion of cooperation. Once this preference exceeds a critical value, cooperation will be prohibited. We explain this phenomenon by arguing that extremely strong investment preference undermines the ability of cooperative clusters to resist defectors. Moreover, we extend the analysis into the three-strategy case and discover that the catalytic effect of extortioners can eliminate this first up and then down trend in the two-strategy model. The equilibrium fraction of cooperators is always positively correlated to the level of investment preference in three-strategy models.

  8. A Variable Flow Modelling Approach To Military End Strength Planning

    Science.gov (United States)

    2016-12-01

    function. The MLRPS is more complex than the variable flow model as it has to cater for a force structure that is much larger than just the MT branch...essential positions in a Ship’s complement, or by the biggest current deficit in forecast end strength. The model can be adjusted to cater for any of these...is unlikely that the RAN will be able to cater for such an increase in hires, so this scenario is not likely to solve their problem. Each transition

  9. A structural bond strength model for glass durability

    International Nuclear Information System (INIS)

    Feng, Xiangdong; Metzger, T.B.

    1996-01-01

    A glass durability model, structural bond strength (SBS) model was developed to correlate glass durability with its composition. This model assumes that the strengths of the bonds between cations and oxygens and the structural roles of the individual elements in the glass arc the predominant factors controlling the composition dependence of the chemical durability of glasses. The structural roles of oxides in glass are classified as network formers, network breakers, and intermediates. The structural roles of the oxides depend upon glass composition and the redox state of oxides. Al 2 O 3 , ZrO 2 , Fe 2 O 3 , and B 2 O 3 are assigned as network formers only when there are sufficient alkalis to bind with these oxides. CaO can also improve durability by sharing non-bridging oxygen with alkalis, relieving SiO 2 from alkalis. The percolation phenomenon in glass is also taken into account. The SBS model is applied to correlate the 7-day product consistency test durability of 42 low-level waste glasses with their composition with an R 2 of 0.87, which is better than 0.81 obtained with an eight-coefficient empirical first-order mixture model on the same data set

  10. Discrete Model for the Structure and Strength of Cementitious Materials

    Science.gov (United States)

    Balopoulos, Victor D.; Archontas, Nikolaos; Pantazopoulou, Stavroula J.

    2017-12-01

    Cementitious materials are characterized by brittle behavior in direct tension and by transverse dilatation (due to microcracking) under compression. Microcracking causes increasingly larger transverse strains and a phenomenological Poisson's ratio that gradually increases to about ν =0.5 and beyond, at the limit point in compression. This behavior is due to the underlying structure of cementitious pastes which is simulated here with a discrete physical model. The computational model is generic, assembled from a statistically generated, continuous network of flaky dendrites consisting of cement hydrates that emanate from partially hydrated cement grains. In the actual amorphous material, the dendrites constitute the solid phase of the cement gel and interconnect to provide the strength and stiffness against load. The idealized dendrite solid is loaded in compression and tension to compute values for strength and Poisson's effects. Parametric studies are conducted, to calibrate the statistical parameters of the discrete model with the physical and mechanical characteristics of the material, so that the familiar experimental trends may be reproduced. The model provides a framework for the study of the mechanical behavior of the material under various states of stress and strain and can be used to model the effects of additives (e.g., fibers) that may be explicitly simulated in the discrete structure.

  11. Tantalum strength model incorporating temperature, strain rate and pressure

    Science.gov (United States)

    Lim, Hojun; Battaile, Corbett; Brown, Justin; Lane, Matt

    Tantalum is a body-centered-cubic (BCC) refractory metal that is widely used in many applications in high temperature, strain rate and pressure environments. In this work, we propose a physically-based strength model for tantalum that incorporates effects of temperature, strain rate and pressure. A constitutive model for single crystal tantalum is developed based on dislocation kink-pair theory, and calibrated to measurements on single crystal specimens. The model is then used to predict deformations of single- and polycrystalline tantalum. In addition, the proposed strength model is implemented into Sandia's ALEGRA solid dynamics code to predict plastic deformations of tantalum in engineering-scale applications at extreme conditions, e.g. Taylor impact tests and Z machine's high pressure ramp compression tests, and the results are compared with available experimental data. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Stochastic models for strength of wind turbine blades using tests

    DEFF Research Database (Denmark)

    Toft, H.S.; Sørensen, John Dalsgaard

    2008-01-01

    The structural cost of wind turbine blades is dependent on the values of the partial safety factors which reflect the uncertainties in the design values, including statistical uncertainty from a limited number of tests. This paper presents a probabilistic model for ultimate and fatigue strength...... of wind turbine blades especially considering the influence of prior knowledge and test results and how partial safety factors can be updated when additional full-scale tests are performed. This updating is performed by adopting a probabilistic design basis based on Bayesian statistical methods....

  13. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    Energy Technology Data Exchange (ETDEWEB)

    Henry de Frahan, M. T., E-mail: marchdf@umich.edu; Johnsen, E. [Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Belof, J. L.; Cavallo, R. M.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; LeBlanc, M. M. [Lawrence Livermore National Laboratory Livermore, California 94551-0808 (United States); Raevsky, V. A.; Ignatova, O. N.; Lebedev, A. [Russian Federal Nuclear Center-VNIIEF, Sarov 607188 (Russian Federation)

    2015-06-14

    We present a set of high explosive driven Rayleigh-Taylor strength experiments for beryllium to produce data to distinguish predictions by various strength models. Design simulations using existing strength model parameterizations from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, suggests growth consistent with little material strength. We focus mostly on efforts to simulate the data using published strength models as well as the more recent RING relaxation model developed at VNIIEF. The results of the strength experiments indicate weak influence of strength in mitigating the growth with the RING model coming closest to predicting the material behavior. Finally, we present shock and ramp-loading recovery experiments.

  14. Elementary and advanced modelling of the splitting strength of timber connections

    NARCIS (Netherlands)

    Schoenmakers, J.C.M.D.

    2008-01-01

    The load-bearing capacity of a timber member loaded perpendicular-to-grain by a connection is governed by either the embedment strength, the bending yield strength of the steel fasteners, or the splitting strength of the timber. Only coarse models for predicting the splitting strength are

  15. Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta.

    Science.gov (United States)

    Oestreich, Arin K; Kamp, William M; McCray, Marcus G; Carleton, Stephanie M; Karasseva, Natalia; Lenz, Kristin L; Jeong, Youngjae; Daghlas, Salah A; Yao, Xiaomei; Wang, Yong; Pfeiffer, Ferris M; Ellersieck, Mark R; Schulz, Laura C; Phillips, Charlotte L

    2016-11-22

    During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstn tm1Sjl/+ ) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstn tm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2 oim ), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2 oim/+ offspring from natural mating of Mstn tm1Sjl/+ dams to Col1a2 oim/+ sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2 oim/+ dams to Col1a2 oim/+ sires. Finally, increased bone biomechanical strength of Col1a2 oim/+ offspring that had been transferred into Mstn tm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta.

  16. Confined compressive strength model of rock for drilling optimization

    Directory of Open Access Journals (Sweden)

    Xiangchao Shi

    2015-03-01

    Full Text Available The confined compressive strength (CCS plays a vital role in drilling optimization. On the basis of Jizba's experimental results, a new CCS model considering the effects of the porosity and nonlinear characteristics with increasing confining pressure has been developed. Because the confining pressure plays a fundamental role in determining the CCS of bottom-hole rock and because the theory of Terzaghi's effective stress principle is founded upon soil mechanics, which is not suitable for calculating the confining pressure in rock mechanics, the double effective stress theory, which treats the porosity as a weighting factor of the formation pore pressure, is adopted in this study. The new CCS model combined with the mechanical specific energy equation is employed to optimize the drilling parameters in two practical wells located in Sichuan basin, China, and the calculated results show that they can be used to identify the inefficient drilling situations of underbalanced drilling (UBD and overbalanced drilling (OBD.

  17. mathematical model for the optimization of compressive strength

    African Journals Online (AJOL)

    ES Obe

    cement and sand either wholly or partially without adverse effect on the strength properties of the ... sandcrete block, compressive strength, laterite, scheffe's theory. 1. Introduction ... that for the properties of a q-component mix- ture which ...

  18. Comparison of ANN and RKS approaches to model SCC strength

    Science.gov (United States)

    Prakash, Aravind J.; Sathyan, Dhanya; Anand, K. B.; Aravind, N. R.

    2018-02-01

    Self compacting concrete (SCC) is a high performance concrete that has high flowability and can be used in heavily reinforced concrete members with minimal compaction segregation and bleeding. The mix proportioning of SCC is highly complex and large number of trials are required to get the mix with the desired properties resulting in the wastage of materials and time. The research on SCC has been highly empirical and no theoretical relationships have been developed between the mixture proportioning and engineering properties of SCC. In this work effectiveness of artificial neural network (ANN) and random kitchen sink algorithm(RKS) with regularized least square algorithm(RLS) in predicting the split tensile strength of the SCC is analysed. Random kitchen sink algorithm is used for mapping data to higher dimension and classification of this data is done using Regularized least square algorithm. The training and testing data for the algorithm was obtained experimentally using standard test procedures and materials available. Total of 40 trials were done which were used as the training and testing data. Trials were performed by varying the amount of fine aggregate, coarse aggregate, dosage and type of super plasticizer and water. Prediction accuracy of the ANN and RKS model is checked by comparing the RMSE value of both ANN and RKS. Analysis shows that eventhough the RKS model is good for large data set, its prediction accuracy is as good as conventional prediction method like ANN so the split tensile strength model developed by RKS can be used in industries for the proportioning of SCC with tailor made property.

  19. Gluon field strength correlation functions within a constrained instanton model

    International Nuclear Information System (INIS)

    Dorokhov, A.E.; Esaibegyan, S.V.; Maximov, A.E.; Mikhailov, S.V.

    2000-01-01

    We suggest a constrained instanton (CI) solution in the physical QCD vacuum which is described by large-scale vacuum field fluctuations. This solution decays exponentially at large distances. It is stable only if the interaction of the instanton with the background vacuum field is small and additional constraints are introduced. The CI solution is explicitly constructed in the ansatz form, and the two-point vacuum correlator of the gluon field strengths is calculated in the framework of the effective instanton vacuum model. At small distances the results are qualitatively similar to the single instanton case; in particular, the D 1 invariant structure is small, which is in agreement with the lattice calculations. (orig.)

  20. Physical models for the hypothesized F(nu) varies as the inverse of nu infrared to X-ray continuum of quasi-stellar objects

    International Nuclear Information System (INIS)

    Stein, W.A.

    1991-01-01

    Models for producing the large ultraviolet bump, low-energy X-rays and the hypothesized F(nu) varies as the inverse of nu IR to X-ray continua of QSOs are investigated. Thermal Comptonization in a hot corona of an accretion disk appears to offer the best potential. However, under the energy input conditions in QSOs a corona will reach T above 100 million K. It must be optically thin, so as to not Comptonize the accretion disk ultraviolet emission to an unacceptable extent. However, it then cannot Comptonize a low-frequency source to an F(nu) varies as the inverse of nu continuum extending from the infrared to X-rays. An inner corona, possibly optically thick because of n varies as the sq rt of r density increase, is required for the F(nu) varies as the inverse of nu continuum, but it cannot therefore cover the UV-emitting accretion disk. However, then a Wien peak associated with this inner volume may be implied at 10 keV, contrary to observations. 42 refs

  1. A dependent stress-strength interference model based on mixed copula function

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jian Xiong; An, Zong Wen; Liu, Bo [School of Mechatronics Engineering, Lanzhou University of Technology, Lanzhou (China)

    2016-10-15

    In the traditional Stress-strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.

  2. Analytical model for shear strength of end slabs of prestressed concrete nuclear reactor vessels

    International Nuclear Information System (INIS)

    Abdulrahman, H.O.; Sozen, M.A.; Schnobrich, W.C.

    1979-04-01

    The results are presented of an investigation of the behavior and strength of flat end slabs of cylindrical prestressed concrete nuclear reactor vessels. The investigation included tests of ten small-scale pressure vessels and development of a nonlinear finite-element model to simulate the deformation response and strength of the end slabs. Because earlier experimental studies had shown that the flexural strength of the end slab could be calculated using intelligible procedures, the emphasis of this investigation was on shear strength

  3. Neutron strength functions: the link between resolved resonances and the optical model

    International Nuclear Information System (INIS)

    Moldauer, P.A.

    1980-01-01

    Neutron strength functions and scattering radii are useful as energy and channel radius independent parameters that characterize neutron scattering resonances and provide a connection between R-matrix resonance analysis and the optical model. The choice of R-matrix channel radii is discussed, as are limitations on the accuracies of strength functions. New definitions of the p-wave strength function and scattering radius are proposed. For light nuclei, where strength functions display optical model energy variations over the resolved resonances, a doubly reduced partial neutron width is introduced for more meaningful statistical analyses of widths. The systematic behavior of strength functions and scattering radii is discussed

  4. Constraint effects of model coal pillar geometry on its strength

    Energy Technology Data Exchange (ETDEWEB)

    Wahab Khair, A.; Danqing Xu (West Virgina University, Morgantown, WV (United States))

    1994-06-01

    Coal and rock specimens with various diameter/height ratios (D/H) were subjected to compressive test in the laboratory. The deformation and failure characteristics of specimens were studied. The study showed that the D/H ratio of specimens significantly affects the deformation, failure characteristics, and the strength of material. The results provide a better understanding of the mechanism of D/H ratio effect on the strength of materials. The magnitude and mechanism of D/H ratio effect was compared with the effect of confining pressure, and contrasted to size effect. The application of the study to pillar design is discussed. 3 refs., 10 figs.

  5. Some difficulties and inconsistencies when using habit strength and reasoned action variables in models of metered household water conservation.

    Science.gov (United States)

    Jorgensen, Bradley S; Martin, John F; Pearce, Meryl; Willis, Eileen

    2013-01-30

    Research employing household water consumption data has sought to test models of water demand and conservation using variables from attitude theory. A significant, albeit unrecognised, challenge has been that attitude models describe individual-level motivations while consumption data is recorded at the household level thereby creating inconsistency between units of theory and measurement. This study employs structural equation modelling and moderated regression techniques to addresses the level of analysis problem, and tests hypotheses by isolating effects on water conservation in single-person households. Furthermore, the results question the explanatory utility of habit strength, perceived behavioural control, and intentions for understanding metered water conservation in single-person households. For example, evidence that intentions predict water conservation or that they interact with habit strength in single-person households was contrary to theoretical expectations. On the other hand, habit strength, self-reports of past water conservation, and perceived behavioural control were good predictors of intentions to conserve water. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. A discrete stress-strength interference model based on universal generating function

    International Nuclear Information System (INIS)

    An Zongwen; Huang Hongzhong; Liu Yu

    2008-01-01

    Continuous stress-strength interference (SSI) model regards stress and strength as continuous random variables with known probability density function. This, to some extent, results in a limitation of its application. In this paper, stress and strength are treated as discrete random variables, and a discrete SSI model is presented by using the universal generating function (UGF) method. Finally, case studies demonstrate the validity of the discrete model in a variety of circumstances, in which stress and strength can be represented by continuous random variables, discrete random variables, or two groups of experimental data

  7. Oxidation Phenomena in Advanced High Strength Steels : Modelling and Experiment

    NARCIS (Netherlands)

    Mao, W.

    2018-01-01

    Galvanized advanced high strength steels (AHSS) will be the most competitive structural material for automotive applications in the next decade. Oxidation of AHSS during the recrystalization annealing process in a continuous galvanizing line to a large extent influences the quality of zinc coating

  8. Scientific 'Laws', 'Hypotheses' and 'Theories'

    Indian Academy of Sciences (India)

    theories, defines a hypothesis as "any supposition which we may ... about the origin of the solar system are also hypotheses of this type. They are about the birth of the planets, an event, which has happened, in the past history of our Universe.

  9. Scientific 'Laws', 'Hypotheses' and 'Theories'

    Indian Academy of Sciences (India)

    verified, the hypothesis changes from the status of a 'mere' hypothesis, and ... a pre-existing law and the body of facts upon which that law is based. Hypotheses .... implicit belief that order objectively exists in nature, and that scientific laws ...

  10. A New Form of Nondestructive Strength-Estimating Statistical Models Accounting for Uncertainty of Model and Aging Effect of Concrete

    International Nuclear Information System (INIS)

    Hong, Kee Jeung; Kim, Jee Sang

    2009-01-01

    As concrete ages, the surrounding environment is expected to have growing influences on the concrete. As all the impacts of the environment cannot be considered in the strength-estimating model of a nondestructive concrete test, the increase in concrete age leads to growing uncertainty in the strength-estimating model. Therefore, the variation of the model error increases. It is necessary to include those impacts in the probability model of concrete strength attained from the nondestructive tests so as to build a more accurate reliability model for structural performance evaluation. This paper reviews and categorizes the existing strength-estimating statistical models of nondestructive concrete test, and suggests a new form of the strength-estimating statistical models to properly reflect the model uncertainty due to aging of the concrete. This new form of the statistical models will lay foundation for more accurate structural performance evaluation.

  11. Using hardness to model yield and tensile strength

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.; Dogan, Omer N.; Schrems, Karol K.

    2005-02-01

    The current direction in hardness research is towards smaller and smaller loads as nano-scale materials are developed. There remains, however, a need to investigate the mechanical behavior of complex alloys for severe environment service. In many instances this entails casting large ingots and making numerous tensile samples as the bounds of the operating environment are explored. It is possible to gain an understanding of the tensile strength of these alloys using room and elevated temperature hardness in conjunction with selected tensile tests. The approach outlined here has its roots in the work done by Tabor for metals and low alloy and carbon steels. This research seeks to extend the work to elevated temperatures for multi-phase, complex alloys. A review of the approach will be given after which the experimental data will be examined. In particular, the yield stress and tensile strength will be compared to their corresponding hardness based values.

  12. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    Energy Technology Data Exchange (ETDEWEB)

    Henry de Frahan, M. T. [Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA; Belof, J. L. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; Cavallo, R. M. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; Raevsky, V. A. [Russian Federal Nuclear Center-VNIIEF, Sarov 607188, Russia; Ignatova, O. N. [Russian Federal Nuclear Center-VNIIEF, Sarov 607188, Russia; Lebedev, A. [Russian Federal Nuclear Center-VNIIEF, Sarov 607188, Russia; Ancheta, D. S. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; El-dasher, B. S. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; Florando, J. N. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; Gallegos, G. F. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA; Johnsen, E. [Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA; LeBlanc, M. M. [Lawrence Livermore National Laboratory Livermore, California 94551-0808, USA

    2015-06-14

    A recent collaboration between LLNL and VNIIEF has produced a set of high explosive driven Rayleigh-Taylor strength data for beryllium. Design simulations using legacy strength models from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, shows close to classical growth. We characterize the material properties of the beryllium tested in the experiments. We also discuss recent efforts to simulate the data using the legacy strength models as well as the more recent RING relaxation model developed at VNIIEF. Finally, we present shock and ramp-loading recovery experiments conducted as part of the collaboration.

  13. A Multi-Phase Equation of State and Strength Model for Tin

    International Nuclear Information System (INIS)

    Cox, G. A.

    2006-01-01

    This paper considers a multi-phase equation of state and a multi-phase strength model for tin in the β, γ and liquid phases. At a phase transition there are changes in volume, energy, and properties of a material that should be included in an accurate model. The strength model will also be affected by a solid-solid phase transition. For many materials there is a lack of experimental data for strength at high pressures making the derivation of strength parameters for some phases difficult. In the case of tin there are longitudinal sound speed data on the Hugoniot available that have been used here in conjunction with a multi-phase equation of state to derive strength parameters for the γ phase, a phase which does not exist at room temperature and pressure

  14. Testing statistical hypotheses of equivalence

    CERN Document Server

    Wellek, Stefan

    2010-01-01

    Equivalence testing has grown significantly in importance over the last two decades, especially as its relevance to a variety of applications has become understood. Yet published work on the general methodology remains scattered in specialists' journals, and for the most part, it focuses on the relatively narrow topic of bioequivalence assessment.With a far broader perspective, Testing Statistical Hypotheses of Equivalence provides the first comprehensive treatment of statistical equivalence testing. The author addresses a spectrum of specific, two-sided equivalence testing problems, from the

  15. Implementation of the Strengths Model at an area mental health service.

    Science.gov (United States)

    Chopra, Prem; Hamilton, Bridget; Castle, David; Smith, Jenny; Mileshkin, Cris; Deans, Michael; Wynne, Brad; Prigg, Glenn; Toomey, Nigel; Wilson, Michael

    2009-06-01

    The objectives of this paper are to provide an overview of recovery-focused models of care and discuss the implementation of the Strengths Model at St. Vincent's Mental Health Melbourne (SVMH), Victoria, Australia. The implementation of the Strengths Model at SVMH is discussed with particular emphasis on the process of implementation, service implications, practical challenges and dilemmas that have arisen, and proposed evaluation. Recovery-focused care is feasible and can enhance current practice of mental health services.

  16. Modeling strength loss in wood by chemical composition. Part I, An individual component model for southern pine

    Science.gov (United States)

    J. E. Winandy; P. K. Lebow

    2001-01-01

    In this study, we develop models for predicting loss in bending strength of clear, straight-grained pine from changes in chemical composition. Although significant work needs to be done before truly universal predictive models are developed, a quantitative fundamental relationship between changes in chemical composition and strength loss for pine was demonstrated. In...

  17. Micromechanical modeling of strength and damage of fiber reinforced composites

    Energy Technology Data Exchange (ETDEWEB)

    Mishnaevsky, L. Jr.; Broendsted, P.

    2007-03-15

    The report for the first year of the EU UpWind project includes three parts: overview of concepts and methods of modelling of mechanical behavior, deformation and damage of unidirectional fiber reinforced composites, development of computational tools for the automatic generation of 3D micromechanical models of fiber reinforced composites, and micromechanical modelling of damage in FRC, and phenomenological analysis of the effect of frequency of cyclic loading on the lifetime and damage evolution in materials. (au)

  18. Mathematical Model for Prediction of Flexural Strength of Mound ...

    African Journals Online (AJOL)

    The mound soil-cement blended proportions were mathematically optimized by using scheffe's approach and the optimization model developed. A computer program predicting the mix proportion for the model was written. The optimal proportion by the program was used prepare beam samples measuring 150mm x 150mm ...

  19. Novel Predictive Model of the Debonding Strength for Masonry Members Retrofitted with FRP

    Directory of Open Access Journals (Sweden)

    Iman Mansouri

    2016-11-01

    Full Text Available Strengthening of masonry members using externally bonded (EB fiber-reinforced polymer (FRP composites has become a famous structural strengthening method over the past decade due to the popular advantages of FRP composites, including their high strength-to-weight ratio and excellent corrosion resistance. In this study, gene expression programming (GEP, as a novel tool, has been used to predict the debonding strength of retrofitted masonry members. The predictions of the new debonding resistance model, as well as several other models, are evaluated by comparing their estimates with experimental results of a large test database. The results indicate that the new model has the best efficiency among the models examined and represents an improvement to other models. The root mean square errors (RMSE of the best empirical Kashyap model in training and test data were, respectively, reduced by 51.7% and 41.3% using the GEP model in estimating debonding strength.

  20. In Situ Strength Model for Continuous Fibers and Multi-Scale Modeling the Fracture of C/SiC Composites

    Science.gov (United States)

    Zhang, Sheng; Gao, Xiguang; Song, Yingdong

    2018-04-01

    A new in situ strength model of carbon fibers was developed based on the distribution of defects to predict the stress-strain response and the strength of C/SiC composites. Different levels of defects in the fibers were considered in this model. The defects in the fibers were classified by their effects on the strength of the fiber. The strength of each defect and the probability that the defect appears were obtained from the tensile test of single fibers. The strength model of carbon fibers was combined with the shear-lag model to predict the stress-strain responses and the strengths of fiber bundles and C/SiC minicomposites. To verify the strength model, tensile tests were performed on fiber bundles and C/SiC minicomposites. The predicted and experimental results were in good agreement. Effects of the fiber length, the fiber number and the heat treatment on the final strengths of fiber bundles and C/SiC minicomposites were also discussed.

  1. A Thermodamage Strength Theoretical Model of Ceramic Materials Taking into Account the Effect of Residual Stress

    Directory of Open Access Journals (Sweden)

    Weiguo Li

    2012-01-01

    Full Text Available A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.

  2. The Heteroscedastic Graded Response Model with a Skewed Latent Trait: Testing Statistical and Substantive Hypotheses Related to Skewed Item Category Functions

    Science.gov (United States)

    Molenaar, Dylan; Dolan, Conor V.; de Boeck, Paul

    2012-01-01

    The Graded Response Model (GRM; Samejima, "Estimation of ability using a response pattern of graded scores," Psychometric Monograph No. 17, Richmond, VA: The Psychometric Society, 1969) can be derived by assuming a linear regression of a continuous variable, Z, on the trait, [theta], to underlie the ordinal item scores (Takane & de Leeuw in…

  3. An efficient numerical target strength prediction model: Validation against analysis solutions

    NARCIS (Netherlands)

    Fillinger, L.; Nijhof, M.J.J.; Jong, C.A.F. de

    2014-01-01

    A decade ago, TNO developed RASP (Rapid Acoustic Signature Prediction), a numerical model for the prediction of the target strength of immersed underwater objects. The model is based on Kirchhoff diffraction theory. It is currently being improved to model refraction, angle dependent reflection and

  4. Comparing Three Patterns of Strengths and Weaknesses Models for the Identification of Specific Learning Disabilities

    Science.gov (United States)

    Miller, Daniel C.; Maricle, Denise E.; Jones, Alicia M.

    2016-01-01

    Processing Strengths and Weaknesses (PSW) models have been proposed as a method for identifying specific learning disabilities. Three PSW models were examined for their ability to predict expert identified specific learning disabilities cases. The Dual Discrepancy/Consistency Model (DD/C; Flanagan, Ortiz, & Alfonso, 2013) as operationalized by…

  5. Strength of the trilinear Higgs boson coupling in technicolor models

    International Nuclear Information System (INIS)

    Doff, A.; Natale, A.A.

    2006-01-01

    In the standard model of elementary particles the fermion and gauge boson masses are generated due to the interaction of these particles with elementary Higgs scalar bosons. Despite its success there are some points in the model as, for instance, the enormous range of masses between the lightest and heaviest fermions and other peculiarities that could be better explained at a deeper level. The nature of the Higgs boson is one of the most important problems in particle physics, and there are many questions that may be answered in the near future by LHC experiments, such as: Is the Higgs boson, if it exists at all, elementary or composite? What are the symmetries behind the Higgs mechanism? There are many variants for the Higgs mechanism. Our interest in this work will be focused in the models of electroweak symmetry breaking via strongly interacting theories of technicolor (TC) type. In these theories the Higgs boson is a composite of the so called technifermions, and at some extent any model where the Higgs boson is not an elementary field follows more or less the same ideas of the technicolor models. In extensions of the standard model the scalar self-couplings can be enhanced, like in the supersymmetric version. If the same happens in models of dynamical symmetry breaking, as far as we know, has not been investigated up to now, and this study is the motivation of our work. Although technicolor is a non-Abelian gauge theory it is not necessarily similar to QCD, and most of the work in this area try to find the TC dynamics dealing with the particle content of the theory in order to obtain a technifermion self-energy that does not lead to phenomenological problems as in the scheme known as walking technicolor. In this work we will consider a very general Ansatz for the technifermion self-energy, which is an essential ingredient to compute the scalar self-couplings. This Ansatz interpolates between all known forms of technifermionic self-energy. As we vary some

  6. Enriching the ECSI model using brand strength in the retail setting

    Directory of Open Access Journals (Sweden)

    Paraskevi Sarantidou

    2017-10-01

    Full Text Available Purpose - The purpose of this paper is to investigate the role of the retailer’s brand strength as a potential predictor of loyalty. It also examines the role of customer satisfaction (CS to the retailer’s loyalty as well as its impact on the retailer’s brand strength. Design/methodology/approach - The study was conducted in the grocery context and in a market under recession using the European Customer Satisfaction Index (ECSI model. Data were collected through a telephone survey from 2,000 participants responsible for the household grocery shopping with a quota of 250 respondents from each of the leading grocery retailers in Greece. A formative measurement model was developed and the collected data were analyzed using partial least square path modeling. Findings - The findings revealed that the strength of the retailer’s brand and CS influence retail loyalty and that brand strength mediate the strength of CS to loyalty. Results also suggested that the expectations and the perceptions toward the retailer’s product offering are the most important drivers of CS and loyalty. Thus, the study has proved the importance of the functional store attributes to CS and loyalty in the grocery store setting. Originality/value - Research examining the suitability of the ECSI model in the grocery setting and in a market under economic crisis is scarce. This paper addresses these shortcomings by examining a customer loyalty model which incorporates the brand strength construct and investigates the role of brand strength as a potential predictor of loyalty as well as the role of CS in the brand strength and loyalty.

  7. Modelling the strength of an aluminium-steel nailed joint

    Science.gov (United States)

    Goldspiegel, Fabien; Mocellin, Katia; Michel, Philippe

    2018-05-01

    For multi-material applications in automotive industry, a cast aluminium (upper layer) and dual-phase steel (lower layer) superposition joined with High-Speed Nailing process is investigated through an experimental vs numerical framework. Using FORGE® finite-element software, results from joining simulations have been inserted into models in charge of nailed-joint mechanical testings. Numerical Shear and Cross-tensile tests are compared to experimental ones to discuss discrepancy and possible improvements.

  8. Conformity and dietary disinhibition: a test of the ego-strength model of self-regulation.

    Science.gov (United States)

    Kahan, Dana; Polivy, Janet; Herman, C Peter

    2003-03-01

    Ego-strength depletion was examined as an explanation for dietary disinhibition in restrained eaters. We predicted that the depletion of ego strength resulting from having to choose whether to conform would undermine dietary restraint. Participants completed an Asch-type conformity task, after which they completed a taste-rating task in which food intake was measured. As predicted, restrained eaters who repeatedly exercised choice ate significantly more than did restrained eaters who did not exercise choice. An ego-strength model of dietary restraint is discussed. Copyright 2003 by Wiley Periodicals, Inc.

  9. Testing hypotheses in an I(2) model with piecewise linear trends. An analysis of the persistent long swings in the Dmk/$ rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    2010-01-01

    This paper discusses the I(2) model with breaks in the deterministic component and illustrates with an analysis of German and US prices, exchange rates, and interest rates in 1975--1999. It provides new results on the likelihood ratio test of overidentifying restrictions on the cointegrating...... relations when they contain piecewise linear trends. One important aim of the paper is to demonstrate that a structured I(2) analysis is useful for a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates....

  10. Analysing the strength of friction stir welded dissimilar aluminium alloys using Sugeno Fuzzy model

    Science.gov (United States)

    Barath, V. R.; Vaira Vignesh, R.; Padmanaban, R.

    2018-02-01

    Friction stir welding (FSW) is a promising solid state joining technique for aluminium alloys. In this study, FSW trials were conducted on two dissimilar plates of aluminium alloy AA2024 and AA7075 by varying the tool rotation speed (TRS) and welding speed (WS). Tensile strength (TS) of the joints were measured and a Sugeno - Fuzzy model was developed to interconnect the FSW process parameters with the tensile strength. From the developed model, it was observed that the optimum heat generation at WS of 15 mm.min-1 and TRS of 1050 rpm resulted in dynamic recovery and dynamic recrystallization of the material. This refined the grains in the FSW zone and resulted in peak tensile strength among the tested specimens. Crest parabolic trend was observed in tensile strength with variation of TRS from 900 rpm to 1200 rpm and TTS from 10 mm.min-1 to 20 mm.min-1.

  11. Unit-Sphere Multiaxial Stochastic-Strength Model Applied to Anisotropic and Composite Materials

    Science.gov (United States)

    Nemeth, Noel, N.

    2013-01-01

    Models that predict the failure probability of brittle materials under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This methodology has been extended to predict the multiaxial strength response of transversely isotropic brittle materials, including polymer matrix composites (PMCs), by considering (1) flaw-orientation anisotropy, whereby a preexisting microcrack has a higher likelihood of being oriented in one direction over another direction, and (2) critical strength, or K (sub Ic) orientation anisotropy, whereby the level of critical strength or fracture toughness for mode I crack propagation, K (sub Ic), changes with regard to the orientation of the microstructure. In this report, results from finite element analysis of a fiber-reinforced-matrix unit cell were used with the unit-sphere model to predict the biaxial strength response of a unidirectional PMC previously reported from the World-Wide Failure Exercise. Results for nuclear-grade graphite materials under biaxial loading are also shown for comparison. This effort was successful in predicting the multiaxial strength response for the chosen problems. Findings regarding stress-state interactions and failure modes also are provided.

  12. Corrosion-induced bond strength degradation in reinforced concrete-Analytical and empirical models

    International Nuclear Information System (INIS)

    Bhargava, Kapilesh; Ghosh, A.K.; Mori, Yasuhiro; Ramanujam, S.

    2007-01-01

    The present paper aims to investigate the relationship between the bond strength and the reinforcement corrosion in reinforced concrete (RC). Analytical and empirical models are proposed for the bond strength of corroded reinforcing bars. Analytical model proposed by Cairns.and Abdullah [Cairns, J., Abdullah, R.B., 1996. Bond strength of black and epoxy-coated reinforcement-a theoretical approach. ACI Mater. J. 93 (4), 362-369] for splitting bond failure and later modified by Coronelli [Coronelli, D. 2002. Corrosion cracking and bond strength modeling for corroded bars in reinforced concrete. ACI Struct. J. 99 (3), 267-276] to consider the corroded bars, has been adopted. Estimation of the various parameters in the earlier analytical model has been proposed by the present authors. These parameters include corrosion pressure due to expansive action of corrosion products, modeling of tensile behaviour of cracked concrete and adhesion and friction coefficient between the corroded bar and cracked concrete. Simple empirical models are also proposed to evaluate the reduction in bond strength as a function of reinforcement corrosion in RC specimens. These empirical models are proposed by considering a wide range of published experimental investigations related to the bond degradation in RC specimens due to reinforcement corrosion. It has been found that the proposed analytical and empirical bond models are capable of providing the estimates of predicted bond strength of corroded reinforcement that are in reasonably good agreement with the experimentally observed values and with those of the other reported published data on analytical and empirical predictions. An attempt has also been made to evaluate the flexural strength of RC beams with corroded reinforcement failing in bond. It has also been found that the analytical predictions for the flexural strength of RC beams based on the proposed bond degradation models are in agreement with those of the experimentally

  13. Petrology and geochemistry of the orbicular granitoid of Caldera, northern Chile. Models and hypotheses on the formation of radial orbicular textures

    Science.gov (United States)

    Díaz-Alvarado, Juan; Rodríguez, Natalia; Rodríguez, Carmen; Fernández, Carlos; Constanzo, Ítalo

    2017-07-01

    The orbicular granitoid of Caldera, located at the northern part of the Chilean Coastal Range, is a spectacular example of radial textures in orbicular structures. The orbicular body crops out as a 375 m2 tabular to lensoidal intrusive sheet emplaced in the Lower Jurassic Relincho pluton. The orbicular structures are 3-7 cm in diameter ellipsoids hosted in a porphyritic matrix. The orbicules are comprised by a Qtz-dioritic core (3-5 cm in diameter) composed by Pl + Hbl + Qtz + Bt ± Kfs with equiaxial textures and a gabbroic shell (2-3 cm in diameter) characterized by feathery and radiate textures with a plagioclase + hornblende paragenesis. The radial shell crystals are rooted and orthogonally disposed in the irregular contact with the core. The radial shell, called here inner shell, is in contact with the granodioritic equiaxial interorbicular matrix through a 2-3 mm wide poikilitic band around the orbicule (outer shell). The outer shell and the matrix surrounding the orbicules are characterized by the presence of large hornblende and biotite oikocrystals that include fine-grained rounded plagioclase and magnetite. The oikocrystals of both the outer shell and the matrix have a circumferential arrangement around the orbicule, i.e. orthogonal to the radial inner shell. The coarse-grained granodioritic interorbicular matrix present pegmatitic domains with large acicular hornblende and K-feldspar megacrysts. This work presents a review of the textural characteristics of the orbicules and a complete new mineral and whole-rock geochemical study of the different parts of the orbicular granitoid, together with thermobarometric and crystallographic data, and theoretical modeling of the crystallization and element partitioning processes. We propose a model for the formation of the orbicular radial textures consisting of several processes that are suggested to occur fast and consecutively: superheating, volatile exsolution, undercooling, geochemical fractionation and

  14. Models of bending strength for Gilsocarbon graphites irradiated in inert and oxidising environments

    International Nuclear Information System (INIS)

    Eason, Ernest D.; Hall, Graham N.; Marsden, Barry J.; Heys, Graham B.

    2013-01-01

    This paper presents the development and validation of an empirical model of fast neutron damage and radiolytic oxidation effects on bending strength for the moulded Gilsocarbon graphites used in Advanced Gas-cooled Reactors (AGRs). The inert environment model is based on evidence of essentially constant strength as fast neutron dose increases in inert environment. The model of combined irradiation and oxidation calibrates that constant along with an exponential function representing the degree of radiolytic oxidation as measured by weight loss. The change in strength with exposure was found to vary from one AGR station to another. The model was calibrated to data on material trepanned from AGR moderator bricks after varying operating times

  15. The Strength-Based Counseling Model: A Paradigm Shift in Psychology

    Science.gov (United States)

    Smith, Elsie J.

    2006-01-01

    Sometimes, it is difficult for a profession to move forward because its members interpret emerging conceptual models from the perspective of old frameworks. Each of the five reactants in this issue of "The Counseling Psychologist" interpreted the strength-based counseling model within their own self-adopted framework--Adlerian psychology, role…

  16. A 3D multilevel model of damage and strength of wood: Analysis of microstructural effects

    DEFF Research Database (Denmark)

    Qing, Hai; Mishnaevsky, Leon

    2011-01-01

    A 3D hierarchical computational model of damage and strength of wood is developed. The model takes into account the four scale microstructures of wood, including the microfibril reinforced structure at nanoscale, multilayered cell walls at microscale, hexagon-shape-tube cellular structure...

  17. A Model for Investigation of the Intensity of Trust Relationships' Strength among Users in Social Media

    Directory of Open Access Journals (Sweden)

    rojiar pir mohammadiani

    2017-06-01

    Full Text Available Although trust relations among users in social media are the evidence of social influence, but the level of this impact depends on strength of trust among users. Therefore, in this paper we study the effect of trust relationships’ strength among users through the development of matrix factorization method. Matrix factorization is a method to predict the rate that user assign to the products. For this purpose, based on similarity factors the strength of trust relationship is measured, then this feature as an effective parameter was added to matrix factorization. The proposed model is applied on Epinions data set. The weight of trust relationships’ strength parameter is determined through the proposed model. Based on the results, by adding the strength of trust relationship the error rate is reduced. Furthermore, if the strength of trust between users is larger than 0.8, the error reduction will be more significant. Improving the results through more accurate estimation shows that this effect is set correctly.

  18. Fragmentation of single-particle strength and the validity of the shell model

    International Nuclear Information System (INIS)

    Brand, M.G.E.; Rijsdijk, G.A.; Muller, F.A.; Allaart, K.; Dickhoff, W.H.

    1991-01-01

    The problem of missing spectroscopic strength in proton knock-out reactions is addressed by calculating this strength with a realistic interaction up to about a hundred MeV missing energy. An interaction suitably modified for short-range correlations (G-matrix) is employed in the calculation of the self-energy including all orbitals up to and including three major shells above the Fermi level for protons. The spectroscopic strength is obtained by solving the Dyson equation for the Green function with a self-energy up to second order in the interaction. Results for 48 Ca and 90 Zr are compared with recent (e,e'p) data. The calculated strength overestimates the data by about 10-15% of the independent particle shell-model (IPSM) sum rule. This is in accordance with what is expected from depletions calculated in infinite nuclear matter. Inclusion of higher order terms into the self-energy, especially the correlated motion of particles and holes, is found to be necessary to reproduce the observed fragmentation of strength in the low-energy region. The widths of the strength distributions compare well with empirical formulas which have been deduced from optical potentials. The validity of the conventional shell-model picture is connected with the relevance of Landau's quasiparticle picture for strongly interacting Fermi systems. (orig.)

  19. The importance of spatial models for estimating the strength of density dependence

    DEFF Research Database (Denmark)

    Thorson, James T.; Skaug, Hans J.; Kristensen, Kasper

    2014-01-01

    the California Coast. In this case, the nonspatial model estimates implausible oscillatory dynamics on an annual time scale, while the spatial model estimates strong autocorrelation and is supported by model selection tools. We conclude by discussing the importance of improved data archiving techniques, so...... that spatial models can be used to re-examine classic questions regarding the presence and strength of density dependence in wild populations Read More: http://www.esajournals.org/doi/abs/10.1890/14-0739.1...

  20. Integrating the strengths of cognitive emotion models with traditional HCI analysis tools

    OpenAIRE

    Springett, Mark; Law, Effie Lai-Chong; Coulson, Mark

    2015-01-01

    This paper reports an attempt to integrate key concepts from cognitive models of emotion to cognitive models of interaction established in HCI literature. The aim is to transfer the strengths of interaction models to analysis of affect-critical systems in games, e-commerce and education, thereby increasing their usefulness in these systems where affect is increasingly recognised as a key success factor. Concepts from Scherer’s appraisal model and stimulation evaluation checks, along with a fr...

  1. Damage Analysis and Evaluation of High Strength Concrete Frame Based on Deformation-Energy Damage Model

    Directory of Open Access Journals (Sweden)

    Huang-bin Lin

    2015-01-01

    Full Text Available A new method of characterizing the damage of high strength concrete structures is presented, which is based on the deformation energy double parameters damage model and incorporates both of the main forms of damage by earthquakes: first time damage beyond destruction and energy consumption. Firstly, test data of high strength reinforced concrete (RC columns were evaluated. Then, the relationship between stiffness degradation, strength degradation, and ductility performance was obtained. And an expression for damage in terms of model parameters was determined, as well as the critical input data for the restoring force model to be used in analytical damage evaluation. Experimentally, the unloading stiffness was found to be related to the cycle number. Then, a correction for this changing was applied to better describe the unloading phenomenon and compensate for the shortcomings of structure elastic-plastic time history analysis. The above algorithm was embedded into an IDARC program. Finally, a case study of high strength RC multistory frames was presented. Under various seismic wave inputs, the structural damages were predicted. The damage model and correction algorithm of stiffness unloading were proved to be suitable and applicable in engineering design and damage evaluation of a high strength concrete structure.

  2. Effects of ionic strength and ion pairing on (plant-wide) modelling of anaerobic digestion

    DEFF Research Database (Denmark)

    Solon, Kimberly; Flores Alsina, Xavier; Mbamba, Christian Kazadi

    2015-01-01

    Plant-wide models of wastewater treatment (such as the Benchmark Simulation Model No. 2 or BSM2) are gaining popularity for use in holistic virtual studies of treatment plant control and operations. The objective of this study is to show the influence of ionic strength (as activity corrections....... The paper describes: 1) how the anaerobic digester performance is affected by physico-chemical corrections; 2) the effect on pH and the anaerobic digestion products (CO2, CH4 and H2); and, 3) how these variations are propagated from the sludge treatment to the water line. Results at high ionic strength...

  3. Functional and muscular adaptations in an experimental model for isometric strength training in mice.

    Directory of Open Access Journals (Sweden)

    Karsten Krüger

    Full Text Available Exercise training induces muscular adaptations that are highly specific to the type of exercise. For a systematic study of the differentiated exercise adaptations on a molecular level mouse models have been used successfully. The aim of the current study was to develop a suitable mouse model of isometric strength exercise training characterized by specific adaptations known from strength training. C57BL/6 mice performed an isometric strength training (ST for 10 weeks 5 days/week. Additionally, either a sedentary control group (CT or a regular endurance training group (ET groups were used as controls. Performance capacity was determined by maximum holding time (MHT and treadmill spirometry, respectively. Furthermore, muscle fiber types and diameter, muscular concentration of phosphofructokinase 1 (PFK, succinate dehydrogenase (SDHa, and glucose transporter type 4 (GLUT4 were determined. In a further approach, the effect of ST on glucose intolerance was tested in diabetic mice. In mice of the ST group we observed an increase of MHT in isometric strength tests, a type II fiber hypertrophy, and an increased GLUT4 protein content in the membrane fraction. In contrast, in mice of the ET group an increase of VO(2max, a shift to oxidative muscle fiber type and an increase of oxidative enzyme content was measured. Furthermore strength training was effective in reducing glucose intolerance in mice fed a high fat diet. An effective murine strength training model was developed and evaluated, which revealed marked differences in adaptations known from endurance training. This approach seems also suitable to test for therapeutical effects of strength training.

  4. Constitutive modelling of the undrained shear strength of fine grained soils containing gas

    Energy Technology Data Exchange (ETDEWEB)

    Grozic, J.L.H. [Calgary Univ., AB (Canada); Nadim, F.; Kvalstad, T.J. [Norwegian Geotechnical Inst., Oslo (Norway)

    2002-07-01

    The behaviour of fine grained gassy soils was studied in order to develop a technique to quantitatively evaluate geohazards. Gas can occur in seabeds either in solution in pore water, undissolved in the form of gas filled voids, or as gas hydrates. In offshore soils, the degree of saturation is generally greater than 90 per cent, resulting in a soil structure with a continuous water phase and a discontinuous gas phase. The presence of methane gas will impact the strength of the soil, which alters its resistance to submarine sliding. This paper presents a constitutive model for determining the undrained shear strength of fine-grained gassy soils to assess the stability of deep water marine slopes for offshore developments. Methane gas is shown to have a beneficial effect on the soil strength in compressive loading, but the peak strength is achieved at larger deformations. The increased strength is a result of compression and solution gas which cause partial drainage and reduced pore pressures. The undrained shear strength of gassy soils was shown to increase with increasing initial consolidation stress, increasing volumetric coefficient of solubility, and increasing initial void ratio. 9 refs., 3 tabs., 6 figs.

  5. Pearce element ratios: A paradigm for testing hypotheses

    Science.gov (United States)

    Russell, J. K.; Nicholls, Jim; Stanley, Clifford R.; Pearce, T. H.

    Science moves forward with the development of new ideas that are encapsulated by hypotheses whose aim is to explain the structure of data sets or to expand existing theory. These hypotheses remain conjecture until they have been tested. In fact, Karl Popper advocated that a scientist's job does not finish with the creation of an idea but, rather, begins with the testing of the related hypotheses. In Popper's [1959] advocation it is implicit that there be tools with which we can test our hypotheses. Consequently, the development of rigorous tests for conceptual models plays a major role in maintaining the integrity of scientific endeavor [e.g., Greenwood, 1989].

  6. Strength analysis and modeling of cellular lattice structures manufactured using selective laser melting for tooling applications

    DEFF Research Database (Denmark)

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus

    2016-01-01

    Additive manufacturing is rapidly developing and gaining popularity for direct metal fabrication systems like selective laser melting (SLM). The technology has shown significant improvement for high-quality fabrication of lightweight design-efficient structures such as conformal cooling channels...... in injection molding tools and lattice structures. This research examines the effect of cellular lattice structures on the strength of workpieces additively manufactured from ultra high-strength steel powder. Two commercial SLM machines are used to fabricate cellular samples based on four architectures— solid......, hollow, lattice structure and rotated lattice structure. Compression test is applied to the specimens while they are deformed. The analytical approach includes finite element (FE), geometrical and mathematical models for prediction of collapse strength. The results from the the models are verified...

  7. EXPERIMENTAL TESTS OF VANADIUM STRENGTH MODELS AT HIGH PRESSURES AND STRAIN RATES

    Energy Technology Data Exchange (ETDEWEB)

    Park, H; Barton, N R; Becker, R C; Bernier, J V; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Rudd, R E

    2010-03-02

    Experimental results showing significant reductions from classical in the Rayleigh-Taylor (RT) instability growth rate due to high pressure material strength or effective lattice viscosity in metal foils are presented. On the Omega Laser in the Laboratory for Laser Energetics, University of Rochester, target samples of polycrystalline vanadium are compressed and accelerated quasi-isentropically at {approx}1 Mbar pressures, while maintaining the samples in the solid-state. Comparison of the results with constitutive models for solid state strength under these conditions show that the measured RT growth is substantially lower than predictions using existing models that work well at low pressures and long time scales. High pressure, high strain rate data can be explained by the enhanced strength due to a phonon drag mechanism, creating a high effective lattice viscosity.

  8. Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC Concrete

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

  9. THE MODERATING EFFECT OF STRENGTH OF MANUFACTURER’S BRANDS ON THE RELATIONSHIP BETWEEN RETAILER’S RELATIONSHIP SATISFACTION AND COMMITMENT: A THEORETICAL MODEL

    Directory of Open Access Journals (Sweden)

    Majid Mapkhot Goaill

    2013-01-01

    Full Text Available Many recent studies emphasized the importance of retailer's satisfaction and commitment to manufacturer/supplier. These studies investigated the relationship between them as an overall relationship. However, there is a dearth of studies that investigated the dimensions of retailer's satisfaction on commitment, and analyzed the mysterious relationship via strength of manufacturer's brands as a moderating effect. Therefore, this study is an attempt to provide a value conceptual model that explains the theoretical linkages existing between dimensions of retailer's satisfaction and commitment, and tries to explain the in-depth meaning of this relationship through the moderating effect of manufacturer's brand strength in the context of social exchange theory. Additionally, hypotheses on the association between the constructs are presented as a basis for further study.

  10. Testing hypotheses for differences between linear regression lines

    Science.gov (United States)

    Stanley J. Zarnoch

    2009-01-01

    Five hypotheses are identified for testing differences between simple linear regression lines. The distinctions between these hypotheses are based on a priori assumptions and illustrated with full and reduced models. The contrast approach is presented as an easy and complete method for testing for overall differences between the regressions and for making pairwise...

  11. Global Models of Ridge-Push Force, Geoid, and Lithospheric Strength of Oceanic plates

    Science.gov (United States)

    Mahatsente, Rezene

    2017-12-01

    An understanding of the transmission of ridge-push related stresses in the interior of oceanic plates is important because ridge-push force is one of the principal forces driving plate motion. Here, I assess the transmission of ridge-push related stresses in oceanic plates by comparing the magnitude of the ridge-push force to the integrated strength of oceanic plates. The strength is determined based on plate cooling and rheological models. The strength analysis includes low-temperature plasticity (LTP) in the upper mantle and assumes a range of possible tectonic conditions and rheology in the plates. The ridge-push force has been derived from the thermal state of oceanic lithosphere, seafloor depth and crustal age data. The results of modeling show that the transmission of ridge-push related stresses in oceanic plates mainly depends on rheology and predominant tectonic conditions. If a lithosphere has dry rheology, the estimated strength is higher than the ridge-push force at all ages for compressional tectonics and at old ages (>75 Ma) for extension. Therefore, under such conditions, oceanic plates may not respond to ridge-push force by intraplate deformation. Instead, the plates may transmit the ridge-push related stress in their interior. For a wet rheology, however, the strength of young lithosphere (stress may dissipate in the interior of oceanic plates and diffuses by intraplate deformation. The state of stress within a plate depends on the balance of far-field and intraplate forces.

  12. Ego Depletion and the Strength Model of Self-Control: A Meta-Analysis

    Science.gov (United States)

    Hagger, Martin S.; Wood, Chantelle; Stiff, Chris; Chatzisarantis, Nikos L. D.

    2010-01-01

    According to the strength model, self-control is a finite resource that determines capacity for effortful control over dominant responses and, once expended, leads to impaired self-control task performance, known as "ego depletion". A meta-analysis of 83 studies tested the effect of ego depletion on task performance and related outcomes,…

  13. Implications of a visco-elastic model of the lithosphere for calculating yield strength envelopes

    NARCIS (Netherlands)

    Ershov, A.V.; Stephenson, R.A.

    2006-01-01

    The dominant deformation mechanism in the ductile part of the lithosphere is creep. From a mechanical point of view, creep can be modelled as a viscous phenomenon. On the other hand, yield-strength envelopes (YSEs), commonly used to describe lithosphere rheology, are constructed supposing creep to

  14. Hydrate failure in ITZ governs concrete strength: A micro-to-macro validated engineering mechanics model

    Czech Academy of Sciences Publication Activity Database

    Königsberger, M.; Hlobil, Michal; Delsaute, B.; Staquet, S.; Hellmich, C.; Pichler, B.

    2018-01-01

    Roč. 103, č. 1 (2018), s. 77-94 ISSN 0008-8846 Institutional support: RVO:68378297 Keywords : compressive strength * micromechanics * cement paste * concrete * modeling Subject RIV: JM - Building Engineering OBOR OECD: Construction engineering, Municipal and structural engineering Impact factor: 4.762, year: 2016 http://www.sciencedirect.com/science/article/pii/S0008884617302934?via%3Dihub

  15. Analytical Solution of Interface Effect on the Strength of Combined Model Composed of Different Geologic Bodies

    Directory of Open Access Journals (Sweden)

    Zeng-hui Zhao

    2014-01-01

    Full Text Available According to the special combined structure of surrounding rock in western mining area of China, a micromechanical model with variable parameters containing contact interface was proposed firstly. Then, the derived stresses in coal and rock near the interface were analyzed on the basis of the harmonized strain relation, and the analytical solutions with respect to stress states near the interface were drawn up. The triaxial compressive strength of coal and rock was further determined in case the contact interface was in the horizontal position. Moreover, effects of stiffness ratio, interface angle, and stress level on the strength of two bodies near the contact area were expounded in detail. Results indicate that additional stresses which have significant effect on the strength of combined model are derived due to the adhesive effect of contact interface and lithological differences between geologic bodies located on both sides. The interface effect on the strength of combined body is most associated with the stiffness, interface angle, and the stress level. These conclusions are also basically valid for three-body model and even for the multibody model and lay important theory foundation to guide the stability study of soft strata composed of different geologic bodies.

  16. Starck Ta PTW strength model recommendation for use with SESAME 93524 EoS

    Energy Technology Data Exchange (ETDEWEB)

    Sjue, Sky K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Prime, Michael Bruce [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-27

    The purpose of this document is to provide a calibration of the Preston-Tonks- Wallace (PTW) strength model for use with the new SESAME equation of state (EoS) 93524. The calibration data included in this t spans temperatures from 198 K to 673 K and strain rates from 0.001/s to 3200/s.

  17. Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model

    International Nuclear Information System (INIS)

    Elangovan, K.; Balasubramanian, V.; Babu, S.

    2009-01-01

    AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop a mathematical model to predict tensile strength of the friction stir welded AA6061 aluminium alloy by incorporating FSW process parameters. Four factors, five levels central composite design has been used to minimize number of experimental conditions. Response surface method (RSM) has been used to develop the model. Statistical tools such as analysis of variance (ANOVA), student's t-test, correlation co-efficient etc. have been used to validate the developed model. The developed mathematical model can be effectively used to predict the tensile strength of FSW joints at 95% confidence level

  18. Assessing hypotheses about nesting site occupancy dynamics

    Science.gov (United States)

    Bled, Florent; Royle, J. Andrew; Cam, Emmanuelle

    2011-01-01

    Hypotheses about habitat selection developed in the evolutionary ecology framework assume that individuals, under some conditions, select breeding habitat based on expected fitness in different habitat. The relationship between habitat quality and fitness may be reflected by breeding success of individuals, which may in turn be used to assess habitat quality. Habitat quality may also be assessed via local density: if high-quality sites are preferentially used, high density may reflect high-quality habitat. Here we assessed whether site occupancy dynamics vary with site surrogates for habitat quality. We modeled nest site use probability in a seabird subcolony (the Black-legged Kittiwake, Rissa tridactyla) over a 20-year period. We estimated site persistence (an occupied site remains occupied from time t to t + 1) and colonization through two subprocesses: first colonization (site creation at the timescale of the study) and recolonization (a site is colonized again after being deserted). Our model explicitly incorporated site-specific and neighboring breeding success and conspecific density in the neighborhood. Our results provided evidence that reproductively "successful'' sites have a higher persistence probability than "unsuccessful'' ones. Analyses of site fidelity in marked birds and of survival probability showed that high site persistence predominantly reflects site fidelity, not immediate colonization by new owners after emigration or death of previous owners. There is a negative quadratic relationship between local density and persistence probability. First colonization probability decreases with density, whereas recolonization probability is constant. This highlights the importance of distinguishing initial colonization and recolonization to understand site occupancy. All dynamics varied positively with neighboring breeding success. We found evidence of a positive interaction between site-specific and neighboring breeding success. We addressed local

  19. Medium strength self-compacting concrete containing fly ash: Modelling using factorial experimental plans

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed Sonebi [University of Paisley, Paisley (United Kingdom). Advanced Concrete and Masonry Centre

    2004-07-01

    This investigation aims to develop medium strength self-compacting concrete (MS-SCC). The cost of materials will be decreased by reducing the cement content and by using pulverised fuel ash (PFA) with a minimum amount of superplasticizer (SP). A factorial design was carried out to mathematically model the influence of five key parameters on filling and passing abilities, segregation and compressive strength, which are important for the successful development of medium strength self-compacting concrete incorporating PFA. The parameters considered in the study were the contents of cement and PFA, water-to-powder (cement+PFA) ratio (W/P) and dosage of SP. The responses of the derived statistical models are slump flow, fluidity loss, Orimet time, V-funnel time, L-box, JRing combined to the Orimet, JRing combined to cone, rheological parameters, segregation and compressive strength at 7, 28 and 90 days. Twenty-one mixes were prepared to derive the statistical models, and five were used for the verification and the accuracy of the developed models. The models are valid for mixes made with 0.38 to 0.72 W/P, 60 to 216 kg/m{sup 3} of cement content, 183 to 317 kg/m{sup 3} of PFA and 0% to 1% of SP, by mass of powder. The influences of W/P, cement and PFA contents, and the dosage of SP were characterised and analysed using polynomial regression, which can identify the primary factors and their interactions on the measured properties. The results show tha MS-SCC can be achieved with a 28-day compressive strength of 30 to 35 MPa by using up to 210 kg/m{sup 3} of PFA.

  20. Effects of ion strength and ion pairing on (plant-wide) modelling of anaerobic digestion processes

    DEFF Research Database (Denmark)

    Flores-Alsina, Xavier; Mbamba, Christian Kazadi; Solon, Kimberly

    2014-01-01

    the effects that an improved physico-chemical description will have on the predicted effluent quality (EQI) and operational cost (OCI) indices. The acid-base equilibria implemented in the Anaerobic Digestion Model No.1 (ADM1) are modified to account for non-ideal aqueous-phase chemistry. The model corrects......The objective of this study is to show the influence of ionic strength (as activity corrections) andion pairing on (plant-wide) modelling of anaerobic digestion processes in wastewater treatment plants(WWTPs). Using the Benchmark Simulation Model No. 2 (BSM2) as a case study, this paper presents...... for ionic strength via the Davies approach to consider chemical activities instead of molar concentrations. Also, a speciation sub-routine based on a multi-dimensional Newton-Raphson iteration method accounts for the formation of some of the ion pairs playing an important role in wastewater treatment...

  1. A Theoretical Model for Estimation of Yield Strength of Fiber Metal Laminate

    Science.gov (United States)

    Bhat, Sunil; Nagesh, Suresh; Umesh, C. K.; Narayanan, S.

    2017-08-01

    The paper presents a theoretical model for estimation of yield strength of fiber metal laminate. Principles of elasticity and formulation of residual stress are employed to determine the stress state in metal layer of the laminate that is found to be higher than the stress applied over the laminate resulting in reduced yield strength of the laminate in comparison with that of the metal layer. The model is tested over 4A-3/2 Glare laminate comprising three thin aerospace 2014-T6 aluminum alloy layers alternately bonded adhesively with two prepregs, each prepreg built up of three uni-directional glass fiber layers laid in longitudinal and transverse directions. Laminates with prepregs of E-Glass and S-Glass fibers are investigated separately under uni-axial tension. Yield strengths of both the Glare variants are found to be less than that of aluminum alloy with use of S-Glass fiber resulting in higher laminate yield strength than with the use of E-Glass fiber. Results from finite element analysis and tensile tests conducted over the laminates substantiate the theoretical model.

  2. A molecular-mechanics based finite element model for strength prediction of single wall carbon nanotubes

    International Nuclear Information System (INIS)

    Meo, M.; Rossi, M.

    2007-01-01

    The aim of this work was to develop a finite element model based on molecular mechanics to predict the ultimate strength and strain of single wallet carbon nanotubes (SWCNT). The interactions between atoms was modelled by combining the use of non-linear elastic and torsional elastic spring. In particular, with this approach, it was tried to combine the molecular mechanics approach with finite element method without providing any not-physical data on the interactions between the carbon atoms, i.e. the CC-bond inertia moment or Young's modulus definition. Mechanical properties as Young's modulus, ultimate strength and strain for several CNTs were calculated. Further, a stress-strain curve for large deformation (up to 70%) is reported for a nanotube Zig-Zag (9,0). The results showed that good agreement with the experimental and numerical results of several authors was obtained. A comparison of the mechanical properties of nanotubes with same diameter and different chirality was carried out. Finally, the influence of the presence of defects on the strength and strain of a SWNT was also evaluated. In particular, the stress-strain curve a nanotube with one-vacancy defect was evaluated and compared with the curve of a pristine one, showing a reduction of the ultimate strength and strain for the defected nanotube. The FE model proposed demonstrate to be a reliable tool to simulate mechanical behaviour of carbon nanotubes both in the linear elastic field and the non-linear elastic field

  3. Enacting Firm, Fair and Friendly Practice: A Model for Strengths-Based Child Protection Relationships?

    Science.gov (United States)

    Oliver, Carolyn; Charles, Grant

    2016-06-01

    Strengths-based solution-focused approaches are gaining ground in statutory child protection work, but few studies have asked front line practitioners how they navigate the complex worker-client relationships such approaches require. This paper describes one component of a mixed-methods study in a large Canadian statutory child protection agency in which 225 workers described how they applied the ideas of strengths-based practice in their daily work. Interviews with twenty-four practitioners were analysed using an interpretive description approach. Only four interviewees appeared to successfully enact a version of strengths-based practice that closely mirrored those described by key strengths-based child protection theorists and was fully congruent with their mandated role. They described navigating a shifting balance of collaboration and authority in worker-client relationships based on transparency, impartial judgement, attentiveness to the worker-client interaction and the value that clients were fellow human beings. Their accounts extend current conceptualisations of the worker-client relationship in strengths-based child protection work and are congruent with current understandings of effective mandated relationships. They provide what may be a useful model to help workers understand and navigate relationships in which they must reconcile their own authority and expertise with genuine support for the authority and expertise of their clients.

  4. Anchorage strength models for end-debonding predictions in RC beams strengthened with FRP composites

    Science.gov (United States)

    Nardini, V.; Guadagnini, M.; Valluzzi, M. R.

    2008-05-01

    The increase in the flexural capacity of RC beams obtained by externally bonding FRP composites to their tension side is often limited by the premature and brittle debonding of the external reinforcement. An in-depth understanding of this complex failure mechanism, however, has not yet been achieved. With specific regard to end-debonding failure modes, extensive experimental observations reported in the literature highlight the important distinction, often neglected in strength models proposed by researchers, between the peel-off and rip-off end-debonding types of failure. The peel-off failure is generally characterized by a failure plane located within the first few millimetres of the concrete cover, whilst the rip-off failure penetrates deeper into the concrete cover and propagates along the tensile steel reinforcement. A new rip-off strength model is described in this paper. The model proposed is based on the Chen and Teng peel-off model and relies upon additional theoretical considerations. The influence of the amount of the internal tensile steel reinforcement and the effective anchorage length of FRP are considered and discussed. The validity of the new model is analyzed further through comparisons with test results, findings of a numerical investigation, and a parametric study. The new rip-off strength model is assessed against a database comprising results from 62 beams tested by various researchers and is shown to yield less conservative results.

  5. Seemingly irrational driving behavior model: The effect of habit strength and anticipated affective reactions.

    Science.gov (United States)

    Chung, Yi-Shih

    2015-09-01

    An increasing amount of evidence suggests that aberrant driving behaviors are not entirely rational. On the basis of the dual-process theory, this study postulates that drivers may learn to perform irrational aberrant driving behaviors, and these behaviors could be derived either from a deliberate or an intuitive decision-making approach. Accordingly, a seemingly irrational driving behavior model is proposed; in this model, the theory of planned behavior (TPB) was adopted to represent the deliberate decision-making mechanism, and habit strength was incorporated to reflect the intuitive decision process. A multiple trivariate mediation structure was designed to reflect the process through which driving behaviors are learned. Anticipated affective reactions (AARs) were further included to examine the effect of affect on aberrant driving behaviors. Considering the example of speeding behaviors, this study developed scales and conducted a two-wave survey of students in two departments at a university in Northern Taiwan. The analysis results show that habit strength consists of multiple aspects, and frequency of past behavior cannot be a complete repository for accumulating habit strength. Habit strength appeared to be a crucial mediator between intention antecedents (e.g., attitude) and the intention itself. Including habit strength in the TPB model enhanced the explained variance of speeding intention by 26.7%. In addition, AARs were different from attitudes; particularly, young drivers tended to perform speeding behaviors to reduce negative feelings such as regret. The proposed model provides an effective alternative approach for investigating aberrant driving behaviors; corresponding countermeasures are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. The Inclusion of Arbitrary Load Histories in the Strength Decay Model for Stress Rupture

    Science.gov (United States)

    Reeder, James R.

    2014-01-01

    Stress rupture is a failure mechanism where failures can occur after a period of time, even though the material has seen no increase in load. Carbon/epoxy composite materials have demonstrated the stress rupture failure mechanism. In a previous work, a model was proposed for stress rupture of composite overwrap pressure vessels (COPVs) and similar composite structures based on strength degradation. However, the original model was limited to constant load periods (holds) at constant load. The model was expanded in this paper to address arbitrary loading histories and specifically the inclusions of ramp loadings up to holds and back down. The broadening of the model allows for failures on loading to be treated as any other failure that may occur during testing instead of having to be treated as a special case. The inclusion of ramps can also influence the length of the "safe period" following proof loading that was previously predicted by the model. No stress rupture failures are predicted in a safe period because time is required for strength to decay from above the proof level to the lower level of loading. Although the model can predict failures during the ramp periods, no closed-form solution for the failure times could be derived. Therefore, two suggested solution techniques were proposed. Finally, the model was used to design an experiment that could detect the difference between the strength decay model and a commonly used model for stress rupture. Although these types of models are necessary to help guide experiments for stress rupture, only experimental evidence will determine how well the model may predict actual material response. If the model can be shown to be accurate, current proof loading requirements may result in predicted safe periods as long as 10(13) years. COPVs design requirements for stress rupture may then be relaxed, allowing more efficient designs, while still maintaining an acceptable level of safety.

  7. Models for Strength Prediction of High-Porosity Cast-In-Situ Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Wenhui Zhao

    2018-01-01

    Full Text Available A study was undertaken to develop a prediction model of compressive strength for three types of high-porosity cast-in-situ foamed concrete (cement mix, cement-fly ash mix, and cement-sand mix with dry densities of less than 700 kg/m3. The model is an extension of Balshin’s model and takes into account the hydration ratio of the raw materials, in which the water/cement ratio was a constant for the entire construction period for a certain casting density. The results show that the measured porosity is slightly lower than the theoretical porosity due to few inaccessible pores. The compressive strength increases exponentially with the increase in the ratio of the dry density to the solid density and increases with the curing time following the composite function A2ln⁡tB2 for all three types of foamed concrete. Based on the results that the compressive strength changes with the porosity and the curing time, a prediction model taking into account the mix constitution, curing time, and porosity is developed. A simple prediction model is put forward when no experimental data are available.

  8. An Elasto-Plastic Damage Model for Rocks Based on a New Nonlinear Strength Criterion

    Science.gov (United States)

    Huang, Jingqi; Zhao, Mi; Du, Xiuli; Dai, Feng; Ma, Chao; Liu, Jingbo

    2018-05-01

    The strength and deformation characteristics of rocks are the most important mechanical properties for rock engineering constructions. A new nonlinear strength criterion is developed for rocks by combining the Hoek-Brown (HB) criterion and the nonlinear unified strength criterion (NUSC). The proposed criterion takes account of the intermediate principal stress effect against HB criterion, as well as being nonlinear in the meridian plane against NUSC. Only three parameters are required to be determined by experiments, including the two HB parameters σ c and m i . The failure surface of the proposed criterion is continuous, smooth and convex. The proposed criterion fits the true triaxial test data well and performs better than the other three existing criteria. Then, by introducing the Geological Strength Index, the proposed criterion is extended to rock masses and predicts the test data well. Finally, based on the proposed criterion, a triaxial elasto-plastic damage model for intact rock is developed. The plastic part is based on the effective stress, whose yield function is developed by the proposed criterion. For the damage part, the evolution function is assumed to have an exponential form. The performance of the constitutive model shows good agreement with the results of experimental tests.

  9. Embedded 3D electromechanical impedance model for strength monitoring of concrete using a PZT transducer

    International Nuclear Information System (INIS)

    Wang, Dansheng; Song, Hongyuan; Zhu, Hongping

    2014-01-01

    The electromechanical (EM) impedance approach in which piezoelectric ceramics (PZT) simultaneously act as both a sensor and an actuator due to their direct and inverse piezoelectric effects has emerged as a powerful tool for structural health monitoring in recent years. This paper formulates a new 3D electromechanical impedance model that characterizes the interaction between an embedded square PZT transducer and the host structure based on the effective impedance. The proposed formulations can be conveniently used to extract the mechanical impedance of the host structure from the electromechanical admittance measurements of an embedded PZT patch. The proposed model is verified by experimental and numerical results from a smart concrete cube in which a square PZT transducer is embedded. Subsequently, this paper also presents a new methodology to monitor the compressive strength of concrete based on the effective mechanical impedance. By extracting the effective mechanical impedances from the electromechanical admittance signatures, measuring the compressive strength of the concrete cubes at different ages and combining these measurements with the index of the correlation coefficient (CC), a linear correlation between the concrete strength gain and the CC of the real mechanical admittances was found. The proposed approach is found to be feasible to monitor the compressive strength of concrete by age. (paper)

  10. Origin of honeycombs: Testing the hydraulic and case hardening hypotheses

    Science.gov (United States)

    Bruthans, Jiří; Filippi, Michal; Slavík, Martin; Svobodová, Eliška

    2018-02-01

    Cavernous weathering (cavernous rock decay) is a global phenomenon, which occurs in porous rocks around the world. Although honeycombs and tafoni are considered to be the most common products of this complex process, their origin and evolution are as yet not fully understood. The two commonly assumed formation hypotheses - hydraulic and case hardening - were tested to elucidate the origin of honeycombs on sandstone outcrops in a humid climate. Mechanical and hydraulic properties of the lips (walls between adjacent pits) and backwalls (bottoms of pits) of the honeycombs were determined via a set of established and novel approaches. While the case hardening hypothesis was not supported by the determinations of either tensile strength, drilling resistance or porosity, the hydraulic hypothesis was clearly supported by field measurements and laboratory tests. Fluorescein dye visualization of capillary zone, vapor zone, and evaporation front upon their contact, demonstrated that the evaporation front reaches the honeycomb backwalls under low water flow rate, while the honeycomb lips remain dry. During occasional excessive water flow events, however, the evaporation front may shift to the lips, while the backwalls become moist as a part of the capillary zone. As the zone of evaporation corresponds to the zone of potential salt weathering, it is the spatial distribution of the capillary and vapor zones which dictates whether honeycombs are created or the rock surface is smoothed. A hierarchical model of factors related to the hydraulic field was introduced to obtain better insights into the process of cavernous weathering.

  11. Modeling of high-strength concrete-filled FRP tube columns under cyclic load

    Science.gov (United States)

    Ong, Kee-Yen; Ma, Chau-Khun; Apandi, Nazirah Mohd; Awang, Abdullah Zawawi; Omar, Wahid

    2018-05-01

    The behavior of high-strength concrete (HSC) - filled fiber-reinforced-polymer (FRP) tubes (HSCFFTs) column subjected to cyclic lateral loading is presented in this paper. As the experimental study is costly and time consuming, a finite element analysis (FEA) is chosen for the study. Most of the previous studies have focused on examining the axial load behavior of HSCFFT column instead of seismic behavior. The seismic behavior of HSCFFT columns has been the main interest in the industry. The key objective of this research is to develop a reliable numerical non-linear FEA model to represent the seismic behavior of such column. A FEA model was developed using the Concrete Damaged Plasticity Model (CDPM) available in the finite element software package (ABAQUS). Comparisons between experimental results from previous research and the predicted results were made based on load versus displacement relationships and ultimate strength of the column. The results showed that the column increased in ductility and able to deform to a greater extent with the increase of the FRP confinement ratio. With the increase of confinement ratio, HSCFFT column achieved a higher moment resistance, thus indicated a higher failure strength in the column under cyclic lateral load. It was found that the proposed FEA model can regenerate the experimental results with adequate accuracy.

  12. Statistical modeling of static strengths of nuclear graphites with relevance to structural design

    International Nuclear Information System (INIS)

    Arai, Taketoshi

    1992-02-01

    Use of graphite materials for structural members poses a problem as to how to take into account of statistical properties of static strength, especially tensile fracture stresses, in component structural design. The present study concerns comprehensive examinations on statistical data base and modelings on nuclear graphites. First, the report provides individual samples and their analyses on strengths of IG-110 and PGX graphites for HTTR components. Those statistical characteristics on other HTGR graphites are also exemplified from the literature. Most of statistical distributions of individual samples are found to be approximately normal. The goodness of fit to normal distributions is more satisfactory with larger sample sizes. Molded and extruded graphites, however, possess a variety of statistical properties depending of samples from different with-in-log locations and/or different orientations. Second, the previous statistical models including the Weibull theory are assessed from the viewpoint of applicability to design procedures. This leads to a conclusion that the Weibull theory and its modified ones are satisfactory only for limited parts of tensile fracture behavior. They are not consistent for whole observations. Only normal statistics are justifiable as practical approaches to discuss specified minimum ultimate strengths as statistical confidence limits for individual samples. Third, the assessment of various statistical models emphasizes the need to develop advanced analytical ones which should involve modeling of microstructural features of actual graphite materials. Improvements of other structural design methodologies are also presented. (author)

  13. Strengths and Weaknesses of McNamara's Evolutionary Psychological Model of Dreaming

    Directory of Open Access Journals (Sweden)

    Sandra Olliges

    2010-10-01

    Full Text Available This article includes a brief overview of McNamara's (2004 evolutionary model of dreaming. The strengths and weaknesses of this model are then evaluated in terms of its consonance with measurable neurological and biological properties of dreaming, its fit within the tenets of evolutionary theories of dreams, and its alignment with evolutionary concepts of cooperation and spirituality. McNamara's model focuses primarily on dreaming that occurs during rapid eye movement (REM sleep; therefore this article also focuses on REM dreaming.

  14. Dataset on predictive compressive strength model for self-compacting concrete.

    Science.gov (United States)

    Ofuyatan, O M; Edeki, S O

    2018-04-01

    The determination of compressive strength is affected by many variables such as the water cement (WC) ratio, the superplasticizer (SP), the aggregate combination, and the binder combination. In this dataset article, 7, 28, and 90-day compressive strength models are derived using statistical analysis. The response surface methodology is used toinvestigate the effect of the parameters: Varying percentages of ash, cement, WC, and SP on hardened properties-compressive strengthat 7,28 and 90 days. Thelevels of independent parameters are determinedbased on preliminary experiments. The experimental values for compressive strengthat 7, 28 and 90 days and modulus of elasticity underdifferent treatment conditions are also discussed and presented.These dataset can effectively be used for modelling and prediction in concrete production settings.

  15. Johnson-Cook Strength Model Constants for VascoMax 300 and 1080 Steels

    International Nuclear Information System (INIS)

    Cinnamon, J. D.; Palazotto, A. N.; Kennan, Z.; Brar, N. S.; Bajaj, D.

    2006-01-01

    High strength steels, VascoMax 300 and 1080, are characterized under tension at strain rates of ∼1/s, ∼500/s, ∼1000/s, and ∼1500/s and at high temperatures using the quasi-static and split Hopkinson bar techniques. The data on 1080 steel exhibited a typical strain hardening response, whereas Vasco-Max 300 steel showed diminishing flow stress beyond yielding because of localized necking in gauge section of the tested specimens. The tension data are analyzed to determine the Johnson-Cook (J-C) strength model constants for the two steels. The flow stress values for VascoMax are adjusted to account for necking, and the corrected J-C model is developed

  16. Ductile failure analysis of high strength steel in hot forming based on micromechanical damage model

    OpenAIRE

    Ying Liang; Liu Wenquan; Wang Dantong; Hu Ping

    2016-01-01

    The damage evolution of high strength steel at elevated temperature is investigated by using the Gurson-Tvergaard-Needleman (GTN) model. A hybrid method integrated thermal tensile test and numerical technique is employed to identify the damage parameters. The analysis results show that the damage parameters are different at different temperature as the variation of tested material microstructure. Furthermore, the calibrated damage parameters are implemented to simulate a bugling forming at el...

  17. In silico generation of alternative hypotheses using causal mapping (CMAP.

    Directory of Open Access Journals (Sweden)

    Gabriel E Weinreb

    Full Text Available Previously, we introduced causal mapping (CMAP as an easy to use systems biology tool for studying the behavior of biological processes that occur at the cellular and molecular level. CMAP is a coarse-grained graphical modeling approach in which the system of interest is modeled as an interaction map between functional elements of the system, in a manner similar to portrayals of signaling pathways commonly used by molecular cell biologists. CMAP describes details of the interactions while maintaining the simplicity of other qualitative methods (e.g., Boolean networks.In this paper, we use the CMAP methodology as a tool for generating hypotheses about the mechanisms that regulate molecular and cellular systems. Furthermore, our approach allows competing hypotheses to be ranked according to a fitness index and suggests experimental tests to distinguish competing high fitness hypotheses. To motivate the CMAP as a hypotheses generating tool and demonstrate the methodology, we first apply this protocol to a simple test-case of a three-element signaling module. Our methods are next applied to the more complex phenomenon of cortical oscillations observed in spreading cells. This analysis produces two high fitness hypotheses for the mechanism that underlies this dynamic behavior and suggests experiments to distinguish the hypotheses. The method can be widely applied to other cellular systems to generate and compare alternative hypotheses based on experimentally observed data and using computer simulations.

  18. Model of fracture of metal melts and the strength of melts under dynamic conditions

    International Nuclear Information System (INIS)

    Mayer, P. N.; Mayer, A. E.

    2015-01-01

    The development of a continuum model of deformation and fracture of melts is needed for the description of the behavior of metals in extreme states, in particular, under high-current electron and ultrashort laser irradiation. The model proposed includes the equations of mechanics of a two-phase continuum and the equations of the kinetics of phase transitions. The change (exchange) of the volumes of dispersed and carrier phases and of the number of dispersed particles is described, and the energy and mass exchange between the phases due to phase transitions is taken into account. Molecular dynamic (MD) calculations are carried out with the use of the LAMMPS program. The continuum model is verified by MD, computational, and experimental data. The strength of aluminum, copper, and nickel is determined at various temperatures and strain rates. It is shown that an increase in the strain rate leads to an increase in the strength of a liquid metal, while an increase in temperature leads to a decrease in its strength

  19. Modeling and Optimization of Compressive Strength of Hollow Sandcrete Block with Rice Husk Ash Admixture

    Directory of Open Access Journals (Sweden)

    2016-11-01

    Full Text Available The paper presents the report of an investigation into the model development and optimization of the compressive strength of 55/45 to 70/30 cement/Rice Husk Ash (RHA in hollow sandcrete block. The low cost and local availability potential of RHA, a pozzolanic material gasps for exploitation. The study applies the Scheffe\\'s optimization approach to obtain a mathematical model of the form f(xi1 ,xi2 ,xi3 xi4 , where x are proportions of the concrete components, viz: cement, RHA, sand and water. Scheffe\\'s i experimental design techniques are followed to mould various hollow block samples measuring 450mm x 225mm x 150mm and tested for 28 days strength. The task involved experimentation and design, applying the second order polynomial characterization process of the simplex lattice method. The model adequacy is checked using the control factors. Finally, a software is prepared to handle the design computation process to take the desired property of the mix, and generate the optimal mix ratios. Reversibly, any mix ratios can be desired and the attainable strength obtained.

  20. Model of fracture of metal melts and the strength of melts under dynamic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, P. N., E-mail: polina.nik@mail.ru; Mayer, A. E., E-mail: mayer@csu.ru [Chelyabinsk State University (Russian Federation)

    2015-07-15

    The development of a continuum model of deformation and fracture of melts is needed for the description of the behavior of metals in extreme states, in particular, under high-current electron and ultrashort laser irradiation. The model proposed includes the equations of mechanics of a two-phase continuum and the equations of the kinetics of phase transitions. The change (exchange) of the volumes of dispersed and carrier phases and of the number of dispersed particles is described, and the energy and mass exchange between the phases due to phase transitions is taken into account. Molecular dynamic (MD) calculations are carried out with the use of the LAMMPS program. The continuum model is verified by MD, computational, and experimental data. The strength of aluminum, copper, and nickel is determined at various temperatures and strain rates. It is shown that an increase in the strain rate leads to an increase in the strength of a liquid metal, while an increase in temperature leads to a decrease in its strength.

  1. Neptunium (V) Adsorption to a Halophilic Bacterium Under High Ionic Strength Conditions: A Surface Complexation Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory

    2012-06-11

    Rationale for experimental design: Np(V) -- important as analog for Pu(V) and for HLW scenarios; High ionic strength -- relevant to salt-based repositories such as the WIPP; Halophilic microorganisms -- representative of high ionic strength environments. For the first time showed: Significant adsorbant to halophilic microorganisms over entire pH range under high ionic strength conditions; Strong influence of ionic strength with increasing adsorption with increasing ionic strength (in contrast to trends of previous low ionic strength studies); Effect of aqueous Np(V) and bacterial surface site speciation on adsorption; and Developed thermodynamic models that can be incorporated into geochemical speciation models to aid in the prediction of the fate and transport of Np(V) in more complex systems.

  2. Oscillator strength of partially ionized high-Z atom on Hartree-Fock Slater model

    International Nuclear Information System (INIS)

    Nakamura, S.; Nishikawa, T.; Takabe, H.; Mima, K.

    1991-01-01

    The Hartree-Fock Slater (HFS) model has been solved for the partially ionized gold ions generated when an intense laser light is irradiated on a gold foil target. The resultant energy levels are compared with those obtained by a simple screened hydrogenic model with l-splitting effect (SHML). It is shown that the energy levels are poorly model by SHML as the ionization level becomes higher. The resultant wave functions are used to evaluate oscillator strength of important line radiations and compared with those obtained by a simple model using hydrogenic wave functions. Its demonstrated that oscillator strength of the 4p-4d and 4d-4f lines are well modeled by the simple method, while the 4-5 transitions such as 4f-5g, 4d-5f, 4p-5d, and 4f-5p forming the so-called N-band emission are poorly modeled and HFS results less strong line emissions. (author)

  3. Industrial point source CO2 emission strength estimation with aircraft measurements and dispersion modelling.

    Science.gov (United States)

    Carotenuto, Federico; Gualtieri, Giovanni; Miglietta, Franco; Riccio, Angelo; Toscano, Piero; Wohlfahrt, Georg; Gioli, Beniamino

    2018-02-22

    CO 2 remains the greenhouse gas that contributes most to anthropogenic global warming, and the evaluation of its emissions is of major interest to both research and regulatory purposes. Emission inventories generally provide quite reliable estimates of CO 2 emissions. However, because of intrinsic uncertainties associated with these estimates, it is of great importance to validate emission inventories against independent estimates. This paper describes an integrated approach combining aircraft measurements and a puff dispersion modelling framework by considering a CO 2 industrial point source, located in Biganos, France. CO 2 density measurements were obtained by applying the mass balance method, while CO 2 emission estimates were derived by implementing the CALMET/CALPUFF model chain. For the latter, three meteorological initializations were used: (i) WRF-modelled outputs initialized by ECMWF reanalyses; (ii) WRF-modelled outputs initialized by CFSR reanalyses and (iii) local in situ observations. Governmental inventorial data were used as reference for all applications. The strengths and weaknesses of the different approaches and how they affect emission estimation uncertainty were investigated. The mass balance based on aircraft measurements was quite succesful in capturing the point source emission strength (at worst with a 16% bias), while the accuracy of the dispersion modelling, markedly when using ECMWF initialization through the WRF model, was only slightly lower (estimation with an 18% bias). The analysis will help in highlighting some methodological best practices that can be used as guidelines for future experiments.

  4. Ductile failure analysis of high strength steel in hot forming based on micromechanical damage model

    Directory of Open Access Journals (Sweden)

    Ying Liang

    2016-01-01

    Full Text Available The damage evolution of high strength steel at elevated temperature is investigated by using the Gurson-Tvergaard-Needleman (GTN model. A hybrid method integrated thermal tensile test and numerical technique is employed to identify the damage parameters. The analysis results show that the damage parameters are different at different temperature as the variation of tested material microstructure. Furthermore, the calibrated damage parameters are implemented to simulate a bugling forming at elevated temperature. The experimental results show the availability of GTN damage model in analyzing sheet formability in hot forming.

  5. Estimation of genetic parameters related to eggshell strength using random regression models.

    Science.gov (United States)

    Guo, J; Ma, M; Qu, L; Shen, M; Dou, T; Wang, K

    2015-01-01

    This study examined the changes in eggshell strength and the genetic parameters related to this trait throughout a hen's laying life using random regression. The data were collected from a crossbred population between 2011 and 2014, where the eggshell strength was determined repeatedly for 2260 hens. Using random regression models (RRMs), several Legendre polynomials were employed to estimate the fixed, direct genetic and permanent environment effects. The residual effects were treated as independently distributed with heterogeneous variance for each test week. The direct genetic variance was included with second-order Legendre polynomials and the permanent environment with third-order Legendre polynomials. The heritability of eggshell strength ranged from 0.26 to 0.43, the repeatability ranged between 0.47 and 0.69, and the estimated genetic correlations between test weeks was high at > 0.67. The first eigenvalue of the genetic covariance matrix accounted for about 97% of the sum of all the eigenvalues. The flexibility and statistical power of RRM suggest that this model could be an effective method to improve eggshell quality and to reduce losses due to cracked eggs in a breeding plan.

  6. MODELS TO ESTIMATE BRAZILIAN INDIRECT TENSILE STRENGTH OF LIMESTONE IN SATURATED STATE

    Directory of Open Access Journals (Sweden)

    Zlatko Briševac

    2016-06-01

    Full Text Available There are a number of methods of estimating physical and mechanical characteristics. Principally, the most widely used is the regression, but recently the more sophisticated methods such as neural networks has frequently been applied, as well. This paper presents the models of a simple and a multiple regression and the neural networks – types Radial Basis Function and Multiple Layer Perceptron, which can be used for the estimate of the Brazilian indirect tensile strength in saturated conditions. The paper includes the issues of collecting the data for the analysis and modelling and the overview of the performed analysis of the efficacy assessment of the estimate of each model. After the assessment, the model which provides the best estimate was selected, including the model which could have the most wide-spread application in the engineering practice.

  7. Lateral strength force of URM structures based on a constitutive model for interface element

    Directory of Open Access Journals (Sweden)

    A.H. Akhaveissy

    Full Text Available This paper presents the numerical implementation of a new proposed interface model for modeling the behavior of mortar joints in masonry walls. Its theoretical framework is fully based on the plasticity theory. The Von Mises criterion is used to simulate the behavior of brick and stone units. The interface laws for contact elements are formulated to simulate the softening behavior of mortar joints under tensile stress; a normal linear cap model is also used to limit compressive stress. The numerical predictions based on the proposed model for the behavior of interface elements correlate very highly with test data. A new explicit formula based on results of proposed interface model is also presented to estimate the strength of unreinforced masonry structures. The closed form solution predicts the ultimate lateral load of unreinforced masonry walls less error percentage than ATC and FEMA-307. Consequently, the proposed closed form solution can be used satisfactorily to analyze unreinforced masonry structures.

  8. Modeling Cable and Guide Channel Interaction in a High-Strength Cable-Driven Continuum Manipulator.

    Science.gov (United States)

    Moses, Matthew S; Murphy, Ryan J; Kutzer, Michael D M; Armand, Mehran

    2015-12-01

    This paper presents several mechanical models of a high-strength cable-driven dexterous manipulator designed for surgical procedures. A stiffness model is presented that distinguishes between contributions from the cables and the backbone. A physics-based model incorporating cable friction is developed and its predictions are compared with experimental data. The data show that under high tension and high curvature, the shape of the manipulator deviates significantly from a circular arc. However, simple parametric models can fit the shape with good accuracy. The motivating application for this study is to develop a model so that shape can be predicted using easily measured quantities such as tension, so that real-time navigation may be performed, especially in minimally-invasive surgical procedures, while reducing the need for hazardous imaging methods such as fluoroscopy.

  9. Strain rate dependent tensile behavior of advanced high strength steels: Experiment and constitutive modeling

    International Nuclear Information System (INIS)

    Kim, Ji-Hoon; Kim, Daeyong; Han, Heung Nam; Barlat, F.; Lee, Myoung-Gyu

    2013-01-01

    High strain rate tensile tests were conducted for three advanced high strength steels: DP780, DP980 and TRIP780. A high strain rate tensile test machine was used for applying the strain rate ranging from 0.1/s to 500/s. Details of the measured stress–strain responses were comparatively analyzed for the DP780 and TRIP780 steels which show similar microstructural feature and ultimate tensile strength, but different strengthening mechanisms. The experimental observations included: usual strain rate dependent plastic flow stress behavior in terms of the yield stress (YS), the ultimate tensile strength (UTS), the uniform elongation (UE) and the total elongation (TE) which were observed for the three materials. But, higher strain hardening rate at early plastic strain under quasi-static condition than that of some increased strain rates was featured for TRIP780 steel, which might result from more active transformation during deformation with lower velocity. The uniform elongation that explains the onset of instability and the total elongation were larger in case of TRIP steel than the DP steel for the whole strain rate range, but interestingly the fracture strain measured by the reduction of area (RA) method showed that the TRIP steel has lower values than DP steel. The fractographs using scanning electron microscopy (SEM) at the fractured surfaces were analyzed to relate measured fracture strain and the microstructural difference of the two materials during the process of fracture under various strain rates. Finally, constitutive modeling for the plastic flow stresses under various strain rates was provided in this study. The proposed constitutive law could represent both Hollomon-like and Voce-like hardening laws and the ratio between the two hardening types was efficiently controlled as a function of strain rate. The new strength model was validated successfully under various strain rates for several grades of steels such as mild steels, DP780, TRIP780, DP980 steels.

  10. Case studies of extended model-based flood forecasting: prediction of dike strength and flood impacts

    Science.gov (United States)

    Stuparu, Dana; Bachmann, Daniel; Bogaard, Tom; Twigt, Daniel; Verkade, Jan; de Bruijn, Karin; de Leeuw, Annemargreet

    2017-04-01

    Flood forecasts, warning and emergency response are important components in flood risk management. Most flood forecasting systems use models to translate weather predictions to forecasted discharges or water levels. However, this information is often not sufficient for real time decisions. A sound understanding of the reliability of embankments and flood dynamics is needed to react timely and reduce the negative effects of the flood. Where are the weak points in the dike system? When, how much and where the water will flow? When and where is the greatest impact expected? Model-based flood impact forecasting tries to answer these questions by adding new dimensions to the existing forecasting systems by providing forecasted information about: (a) the dike strength during the event (reliability), (b) the flood extent in case of an overflow or a dike failure (flood spread) and (c) the assets at risk (impacts). This work presents three study-cases in which such a set-up is applied. Special features are highlighted. Forecasting of dike strength. The first study-case focusses on the forecast of dike strength in the Netherlands for the river Rhine branches Waal, Nederrijn and IJssel. A so-called reliability transformation is used to translate the predicted water levels at selected dike sections into failure probabilities during a flood event. The reliability of a dike section is defined by fragility curves - a summary of the dike strength conditional to the water level. The reliability information enhances the emergency management and inspections of embankments. Ensemble forecasting. The second study-case shows the setup of a flood impact forecasting system in Dumfries, Scotland. The existing forecasting system is extended with a 2D flood spreading model in combination with the Delft-FIAT impact model. Ensemble forecasts are used to make use of the uncertainty in the precipitation forecasts, which is useful to quantify the certainty of a forecasted flood event. From global

  11. Limits on hypothesizing new quantum numbers

    International Nuclear Information System (INIS)

    Goldstein, G.R.; Moravcsik, M.J.

    1986-01-01

    According to a recent theorem, for a general quantum-mechanical system undergoing a process, one can tell from measurements on this system whether or not it is characterized by a quantum number, the existence of which is unknown to the observer, even though the detecting equipment used by the observer is unable to distinguish among the various possible values of the ''secret'' quantum number and hence always averages over them. The present paper deals with situations in which this averaging is avoided and hence the ''secret'' quantum number remains ''secret.'' This occurs when a new quantum number is hypothesized in such a way that all the past measurements pertain to the system with one and the same value of the ''secret'' quantum number, or when the new quantum number is related to the old ones by a specific dynamical model providing a one-to-one correspondence. In the first of these cases, however, the one and the same state of the ''secret'' quantum number needs to be a nondegenerate one. If it is degenerate, the theorem can again be applied. This last feature provides a tool for experimentally testing symmetry breaking and the reestablishment of symmetries in asymptotic regions. The situation is illustrated on historical examples like isospin and strangeness, as well as on some contemporary schemes involving spaces of higher dimensionality

  12. A Constitutive Model for Strain-Controlled Strength Degradation of Rockmasses (SDR)

    Science.gov (United States)

    Kalos, A.; Kavvadas, M.

    2017-11-01

    The paper describes a continuum, rate-independent, incremental plasticity constitutive model applicable in weak rocks and heavily fractured rockmasses, where mechanical behaviour is controlled by rockmass strength rather than structural features (discontinuities). The model describes rockmass structure by a generalised Hoek-Brown Structure Envelope (SE) in the stress space. Stress paths inside the SE are nonlinear and irreversible to better simulate behaviour at strains up to peak strength and under stress reversals. Stress paths on the SE have user-controlled volume dilatancy (gradually reducing to zero at large shear strains) and can model post-peak strain softening of brittle rockmasses via a structure degradation (damage) mechanism triggered by accumulated plastic shear strains. As the SE may strain harden with plastic strains, ductile behaviour can also be modelled. The model was implemented in the Finite Element Code Simulia ABAQUS and was applied in plane strain (2D) excavation of a cylindrical cavity (tunnel) to predict convergence-confinement curves. It is shown that small-strain nonlinearity, variable volume dilatancy and post-peak hardening/softening strongly affect the predicted curves, resulting in corresponding differences of lining pressures in real tunnel excavations.

  13. Application of ANFIS for analytical modeling of tensile strength of functionally graded steels

    Directory of Open Access Journals (Sweden)

    Ali Nazari

    2012-06-01

    Full Text Available In the present study, the tensile strength of ferritic and austenitic functionally graded steels produced by electroslag remelting has been modeled. To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrode. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. Vickers microhardness profile of the specimen has been obtained experimentally and modeled with adaptive network-based fuzzy inference systems (ANFIS. To build the model for graded ferritic and austenitic steels, training, testing and validation using respectively 174 and 120 experimental data were conducted. According to the input parameters, in the ANFIS model, the Vickers microhardness of each layer was predicted. A good fit equation which correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterwards; the Vickers microhardness of each layer in functionally graded steels was related to the yield stress of the corresponding layer and by assuming Holloman relation for stress-strain curve of each layer, they were acquired. Finally, by applying the rule of mixtures, tensile strength of functionally graded steels configuration was found through a numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments.

  14. HYBRID CONTINUUM-DISCONTINUUM MODELLING OF ROCK FRACUTRE PROCESS IN BRAZILIAN TENSILE STRENGTH TEST

    Directory of Open Access Journals (Sweden)

    Huaming An

    2017-10-01

    Full Text Available A hybrid continuum-discontinuum method is introduced to model the rock failure process in Brazilian tensile strength (BTS test. The key component of the hybrid continuum-discontinuum method, i.e. transition from continuum to discontinuum through fracture and fragmentation, is introduced in detail. A laboratory test is conducted first to capture the rock fracture pattern in the BTS test while the tensile strength is calculated according to the peak value of the loading forces. Then the proposed method is used to model the rock behaviour during BTS test. The stress propagation is modelled and compared with those modelled by finite element method in literatures. In addition, the crack initiation and propagation are captured and compared with the facture patter in laboratory test. Moreover, the force-loading displacement curve is obtained which represents a typical brittle material failure process. Furthermore, the stress distributions along the vertical direction are compared with the theoretical solution. It is concluded that the hybrid continuum-discontinuum method can model the stress propagation process and the entire rock failure process in BTS test. The proposed method is a valuable numerical tool for studying the rock behaviour involving the fracture and fragmentation processes.

  15. Surface magnetic field strengths: New tests of magnetoconvective models of M dwarfs

    International Nuclear Information System (INIS)

    MacDonald, James; Mullan, D. J.

    2014-01-01

    Precision modeling of M dwarfs has become worthwhile in recent years due to the increasingly precise values of masses and radii which can be obtained from eclipsing binary studies. In a recent paper, Torres has identified four prime M dwarf pairs with the most precise empirical determinations of masses and radii. The measured radii are consistently larger than standard stellar models predict by several percent. These four systems potentially provide the most challenging tests of precision evolutionary models of cool dwarfs at the present time. We have previously modeled M dwarfs in the context of a criterion due to Gough and Tayler in which magnetic fields inhibit the onset of convection according to a physics-based prescription. In the present paper, we apply our magnetoconvective approach to the four prime systems in the Torres list. Going a step beyond what we have already modeled in CM Dra (one of the four Torres systems), we note that new constraints on magnetoconvective models of M dwarfs are now available from empirical estimates of magnetic field strengths on the surfaces of these stars. In the present paper, we consider how well our magnetoconvective models succeed when confronted with this new test of surface magnetic field strengths. Among the systems listed by Torres, we find that plausible magnetic models work well for CM Dra, YY Gem, and CU Cnc. (The fourth system in Torres's list does not yet have enough information to warrant magnetic modeling.) Our magnetoconvection models of CM Dra, YY Gem, and CU Cnc yield predictions of the magnetic fluxes on the stellar surface which are consistent with the observed correlation between magnetic flux and X-ray luminosity.

  16. Surface Magnetic Field Strengths: New Tests of Magnetoconvective Models of M Dwarfs

    Science.gov (United States)

    MacDonald, James; Mullan, D. J.

    2014-05-01

    Precision modeling of M dwarfs has become worthwhile in recent years due to the increasingly precise values of masses and radii which can be obtained from eclipsing binary studies. In a recent paper, Torres has identified four prime M dwarf pairs with the most precise empirical determinations of masses and radii. The measured radii are consistently larger than standard stellar models predict by several percent. These four systems potentially provide the most challenging tests of precision evolutionary models of cool dwarfs at the present time. We have previously modeled M dwarfs in the context of a criterion due to Gough & Tayler in which magnetic fields inhibit the onset of convection according to a physics-based prescription. In the present paper, we apply our magnetoconvective approach to the four prime systems in the Torres list. Going a step beyond what we have already modeled in CM Dra (one of the four Torres systems), we note that new constraints on magnetoconvective models of M dwarfs are now available from empirical estimates of magnetic field strengths on the surfaces of these stars. In the present paper, we consider how well our magnetoconvective models succeed when confronted with this new test of surface magnetic field strengths. Among the systems listed by Torres, we find that plausible magnetic models work well for CM Dra, YY Gem, and CU Cnc. (The fourth system in Torres's list does not yet have enough information to warrant magnetic modeling.) Our magnetoconvection models of CM Dra, YY Gem, and CU Cnc yield predictions of the magnetic fluxes on the stellar surface which are consistent with the observed correlation between magnetic flux and X-ray luminosity.

  17. Quantitative linking hypotheses for infant eye movements.

    Directory of Open Access Journals (Sweden)

    Daniel Yurovsky

    Full Text Available The study of cognitive development hinges, largely, on the analysis of infant looking. But analyses of eye gaze data require the adoption of linking hypotheses: assumptions about the relationship between observed eye movements and underlying cognitive processes. We develop a general framework for constructing, testing, and comparing these hypotheses, and thus for producing new insights into early cognitive development. We first introduce the general framework--applicable to any infant gaze experiment--and then demonstrate its utility by analyzing data from a set of experiments investigating the role of attentional cues in infant learning. The new analysis uncovers significantly more structure in these data, finding evidence of learning that was not found in standard analyses and showing an unexpected relationship between cue use and learning rate. Finally, we discuss general implications for the construction and testing of quantitative linking hypotheses. MATLAB code for sample linking hypotheses can be found on the first author's website.

  18. A COMPARISON OF THE TENSILE STRENGTH OF PLASTIC PARTS PRODUCED BY A FUSED DEPOSITION MODELING DEVICE

    Directory of Open Access Journals (Sweden)

    Juraj Beniak

    2015-12-01

    Full Text Available Rapid Prototyping systems are nowadays increasingly used in many areas of industry, not only for producing design models but also for producing parts for final use. We need to know the properties of these parts. When we talk about the Fused Deposition Modeling (FDM technique and FDM devices, there are many possible settings for devices and models which could influence the properties of a final part. In addition, devices based on the same principle may use different operational software for calculating the tool path, and this may have a major impact. The aim of this paper is to show the tensile strength value for parts produced from different materials on the Fused Deposition Modeling device when the horizontal orientation of the specimens is changed.

  19. Optimized biological nitrogen removal of high-strength ammonium wastewater by activated sludge modeling

    Directory of Open Access Journals (Sweden)

    Abdelsalam Elawwad

    2018-09-01

    Full Text Available Wastewater containing high ammonium concentrations is produced from various industrial activities. In this study, the author used a complex activated sludge model, improved by utilizing BioWin© (EnviroSim, Hamilton, Canada simulation software, to gain understanding of the problem of instability in biological nitrogen removal (BNR. Specifically, the study focused on BNR in an industrial wastewater treatment plant that receives high-strength ammonium wastewater. Using the data obtained from a nine-day sampling campaign and routinely measured data, the model was successfully calibrated and validated, with modifications to the sensitive stoichiometric and kinetic parameters. Subsequently, the calibrated model was employed to study various operating conditions in order to optimize the BNR. These operating conditions include alkalinity addition, sludge retention time, and the COD/N ratio. The addition of a stripping step and modifications to the configuration of the aerators are suggested by the author to increase the COD/N ratio and therefore enhance denitrification. It was found that the calibrated model could successfully represent and optimize the treatment of the high-strength ammonium wastewater.

  20. Modeling and Simulation to Muscle Strength Training of Lower Limbs Rehabilitation Robots

    Directory of Open Access Journals (Sweden)

    Ke-Yi Wang

    2015-01-01

    Full Text Available Considering the issues of lower limb rehabilitation robots with single control strategies and poor training types, a training method for improving muscle strength was put forward in this paper. Patients’ muscle strength could be achieved by targeted exercises at the end of rehabilitation. This approach could be realized through programming wires’ force. On the one hand, each wires force was measured by tension sensor and force closed loop control was established to control the value of wires’ force which was acted on trainees. On the other hand, the direction of output force was changed by detecting the trainees’ state of motion and the way of putting load to patient was achieved. Finally, the target of enhancing patients’ muscle strength was realized. Dynamic model was built by means of mechanism and training types of robots. Force closed loop control strategy was established based on training pattern. In view of the characteristics of the redundance and economy of wire control, the process for simple wire's load changes was discussed. In order to confirm the characteristics of robot control system, the controller was simulated in Matlab/Simulink. It was verified that command signal could be traced by control system availably and the load during muscle training would be provided effectively.

  1. Determination of strength behaviour of slope supported by vegetated crib walls using centrifuge model testing

    Science.gov (United States)

    Sudan Acharya, Madhu

    2010-05-01

    The crib retaining structures made of wooden/bamboo logs with live plants inside are called vegetative crib walls which are now becoming popular due to their advantages over conventional civil engineering walls. Conventionally, wooden crib walls were dimensioned based on past experiences. At present, there are several guidelines and design standards for machine finished wooden crib walls, but only few guidelines for the design and construction of vegetative log crib walls are available which are generally not sufficient for an economic engineering design of such walls. Analytical methods are generally used to determine the strength of vegetated crib retaining walls. The crib construction is analysed statically by satisfying the condition of static equilibrium with acceptable level of safety. The crib wall system is checked for internal and external stability using conventional monolithic and silo theories. Due to limitations of available theories, the exact calculation of the strength of vegetated wooden/bamboo crib wall cannot be made in static calculation. Therefore, experimental measurements are generally done to verify the static analysis. In this work, a model crib construction (1:20) made of bamboo elements is tested in the centrifuge machine to determine the strength behaviour of the slope supported by vegetated crib retaining wall. A geotechnical centrifuge is used to conduct model tests to study geotechnical problems such as the strength, stiffness and bearing capacity of different structures, settlement of embankments, stability of slopes, earth retaining structures etc. Centrifuge model testing is particularly well suited to modelling geotechnical events because the increase in gravitational force creates stresses in the model that are equivalent to the much larger prototype and hence ensures that the mechanisms of ground movements observed in the tests are realistic. Centrifuge model testing provides data to improve our understanding of basic mechanisms

  2. Bayesian and Classical Estimation of Stress-Strength Reliability for Inverse Weibull Lifetime Models

    Directory of Open Access Journals (Sweden)

    Qixuan Bi

    2017-06-01

    Full Text Available In this paper, we consider the problem of estimating stress-strength reliability for inverse Weibull lifetime models having the same shape parameters but different scale parameters. We obtain the maximum likelihood estimator and its asymptotic distribution. Since the classical estimator doesn’t hold explicit forms, we propose an approximate maximum likelihood estimator. The asymptotic confidence interval and two bootstrap intervals are obtained. Using the Gibbs sampling technique, Bayesian estimator and the corresponding credible interval are obtained. The Metropolis-Hastings algorithm is used to generate random variates. Monte Carlo simulations are conducted to compare the proposed methods. Analysis of a real dataset is performed.

  3. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling.

    Science.gov (United States)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-28

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10 3 to 10 4  s -1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

  4. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    Science.gov (United States)

    Erzar, Benjamin

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s−1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual–Forquin–Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956504

  5. Towards Subject-Specific Strength Training Design through Predictive Use of Musculoskeletal Models

    Directory of Open Access Journals (Sweden)

    Michael Plüss

    2018-01-01

    Full Text Available Lower extremity dysfunction is often associated with hip muscle strength deficiencies. Detailed knowledge of the muscle forces generated in the hip under specific external loading conditions enables specific structures to be trained. The aim of this study was to find the most effective movement type and loading direction to enable the training of specific parts of the hip muscles using a standing posture and a pulley system. In a novel approach to release the predictive power of musculoskeletal modelling techniques based on inverse dynamics, flexion/extension and ab-/adduction movements were virtually created. To demonstrate the effectiveness of this approach, three hip orientations and an external loading force that was systematically rotated around the body were simulated using a state-of-the art OpenSim model in order to establish ideal designs for training of the anterior and posterior parts of the M. gluteus medius (GM. The external force direction as well as the hip orientation greatly influenced the muscle forces in the different parts of the GM. No setting was found for simultaneous training of the anterior and posterior parts with a muscle force higher than 50% of the maximum. Importantly, this study has demonstrated the use of musculoskeletal models as an approach to predict muscle force variations for different strength and rehabilitation exercise variations.

  6. Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling

    Science.gov (United States)

    Zinszner, Jean-Luc; Erzar, Benjamin; Forquin, Pascal

    2017-01-01

    Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 103 to 104 s-1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual-Forquin-Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  7. Algorithmic modeling of the irrelevant sound effect (ISE) by the hearing sensation fluctuation strength.

    Science.gov (United States)

    Schlittmeier, Sabine J; Weissgerber, Tobias; Kerber, Stefan; Fastl, Hugo; Hellbrück, Jürgen

    2012-01-01

    Background sounds, such as narration, music with prominent staccato passages, and office noise impair verbal short-term memory even when these sounds are irrelevant. This irrelevant sound effect (ISE) is evoked by so-called changing-state sounds that are characterized by a distinct temporal structure with varying successive auditory-perceptive tokens. However, because of the absence of an appropriate psychoacoustically based instrumental measure, the disturbing impact of a given speech or nonspeech sound could not be predicted until now, but necessitated behavioral testing. Our database for parametric modeling of the ISE included approximately 40 background sounds (e.g., speech, music, tone sequences, office noise, traffic noise) and corresponding performance data that was collected from 70 behavioral measurements of verbal short-term memory. The hearing sensation fluctuation strength was chosen to model the ISE and describes the percept of fluctuations when listening to slowly modulated sounds (f(mod) background sounds, the algorithm estimated behavioral performance data in 63 of 70 cases within the interquartile ranges. In particular, all real-world sounds were modeled adequately, whereas the algorithm overestimated the (non-)disturbance impact of synthetic steady-state sounds that were constituted by a repeated vowel or tone. Implications of the algorithm's strengths and prediction errors are discussed.

  8. An alternative approach for modeling strength differential effect in sheet metals with symmetric yield functions

    Science.gov (United States)

    Kurukuri, Srihari; Worswick, Michael J.

    2013-12-01

    An alternative approach is proposed to utilize symmetric yield functions for modeling the tension-compression asymmetry commonly observed in hcp materials. In this work, the strength differential (SD) effect is modeled by choosing separate symmetric plane stress yield functions (for example, Barlat Yld 2000-2d) for the tension i.e., in the first quadrant of principal stress space, and compression i.e., third quadrant of principal stress space. In the second and fourth quadrants, the yield locus is constructed by adopting interpolating functions between uniaxial tensile and compressive stress states. In this work, different interpolating functions are chosen and the predictive capability of each approach is discussed. The main advantage of this proposed approach is that the yield locus parameters are deterministic and relatively easy to identify when compared to the Cazacu family of yield functions commonly used for modeling SD effect observed in hcp materials.

  9. Development of an Atlas of Strengths and Establishment of an Appropriate Model Structure

    Science.gov (United States)

    1981-11-01

    the strength comparisons. Everyone uses their hand constantly and unless there were a debilitating illness, such as arthritis , hand strength would...30. Edwards, R. H. T. and Hyde, S. Methods of measuring muscle strength and fatigue. Physiotherapy ; 1977, 63(2), 51-55. 31. Falkel, J. Planter flexor...and Hyde, S. Methods of measuring muscle strength and fatigue. Physiotherapy ; 1977, 63(2), 51-55. KEYWORDS: Muscle strength tests, male and female

  10. The revelation effect: A meta-analytic test of hypotheses.

    Science.gov (United States)

    Aßfalg, André; Bernstein, Daniel M; Hockley, William

    2017-12-01

    Judgments can depend on the activity directly preceding them. An example is the revelation effect whereby participants are more likely to claim that a stimulus is familiar after a preceding task, such as solving an anagram, than without a preceding task. We test conflicting predictions of four revelation-effect hypotheses in a meta-analysis of 26 years of revelation-effect research. The hypotheses' predictions refer to three subject areas: (1) the basis of judgments that are subject to the revelation effect (recollection vs. familiarity vs. fluency), (2) the degree of similarity between the task and test item, and (3) the difficulty of the preceding task. We use a hierarchical multivariate meta-analysis to account for dependent effect sizes and variance in experimental procedures. We test the revelation-effect hypotheses with a model selection procedure, where each model corresponds to a prediction of a revelation-effect hypothesis. We further quantify the amount of evidence for one model compared to another with Bayes factors. The results of this analysis suggest that none of the extant revelation-effect hypotheses can fully account for the data. The general vagueness of revelation-effect hypotheses and the scarcity of data were the major limiting factors in our analyses, emphasizing the need for formalized theories and further research into the puzzling revelation effect.

  11. Finite element modelling of chain-die forming for ultra-high strength steel

    Science.gov (United States)

    Majji, Raju; Xiang, Yang; Ding, Scott; Yang, Chunhui

    2017-10-01

    There has been a high demand for weight reduction in automotive vehicles while maintaining passenger safety. A potential steel material to achieve this is Ultra High Strength Steel (UHSS). As a high strength material, it is difficult to be formed with desired profiles using traditional sheet metal forming processes such as Cold Roll Forming. To overcome this problem, a potentially alternative solution is Chain-die Forming (CDF), recently developed. The basic principal of the CDF is to fully combine roll forming and bending processes. The main advantage of this process is the elongated deformation length that significantly increases effective roll radius. This study focuses on identifying issues with the CDF by using CAD modelling, Motion Analysis and Finite Element Analysis (FEA) to devise solutions and construct a more reliable process in an optimal design sense. Some attempts on finite element modelling and simulation of the CDF were conducted using relatively simple models in literature and the research was still not sufficient enough for optimal design of a typical CDF for UHSS. Therefore two numerical models of Chain-die Forming process are developed in this study, including a) one having a set of rolls similar to roll forming but with a large radius, i.e., 20 meters; and b) the other one with dies and punch segments similar to a typical CDF machine. As a case study, to form a 60° channel with single pass was conducted using these two devised models for a comparison. The obtained numerical results clearly show the CDF could generate less residual stress, low strain and small springback of a single pass for the 60° UHSS channel. The design analysis procedure proposed in this study could greatly help the mechanical designers to devise a cost-effective and reliable CDF process for forming UHSS.

  12. Mechanical strength of 17,134 model proteins and cysteine slipknots.

    Directory of Open Access Journals (Sweden)

    Mateusz Sikora

    2009-10-01

    Full Text Available A new theoretical survey of proteins' resistance to constant speed stretching is performed for a set of 17,134 proteins as described by a structure-based model. The proteins selected have no gaps in their structure determination and consist of no more than 250 amino acids. Our previous studies have dealt with 7510 proteins of no more than 150 amino acids. The proteins are ranked according to the strength of the resistance. Most of the predicted top-strength proteins have not yet been studied experimentally. Architectures and folds which are likely to yield large forces are identified. New types of potent force clamps are discovered. They involve disulphide bridges and, in particular, cysteine slipknots. An effective energy parameter of the model is estimated by comparing the theoretical data on characteristic forces to the corresponding experimental values combined with an extrapolation of the theoretical data to the experimental pulling speeds. These studies provide guidance for future experiments on single molecule manipulation and should lead to selection of proteins for applications. A new class of proteins, involving cysteine slipknots, is identified as one that is expected to lead to the strongest force clamps known. This class is characterized through molecular dynamics simulations.

  13. A New Metric for Land-Atmosphere Coupling Strength: Applications on Observations and Modeling

    Science.gov (United States)

    Tang, Q.; Xie, S.; Zhang, Y.; Phillips, T. J.; Santanello, J. A., Jr.; Cook, D. R.; Riihimaki, L.; Gaustad, K.

    2017-12-01

    A new metric is proposed to quantify the land-atmosphere (LA) coupling strength and is elaborated by correlating the surface evaporative fraction and impacting land and atmosphere variables (e.g., soil moisture, vegetation, and radiation). Based upon multiple linear regression, this approach simultaneously considers multiple factors and thus represents complex LA coupling mechanisms better than existing single variable metrics. The standardized regression coefficients quantify the relative contributions from individual drivers in a consistent manner, avoiding the potential inconsistency in relative influence of conventional metrics. Moreover, the unique expendable feature of the new method allows us to verify and explore potentially important coupling mechanisms. Our observation-based application of the new metric shows moderate coupling with large spatial variations at the U.S. Southern Great Plains. The relative importance of soil moisture vs. vegetation varies by location. We also show that LA coupling strength is generally underestimated by single variable methods due to their incompleteness. We also apply this new metric to evaluate the representation of LA coupling in the Accelerated Climate Modeling for Energy (ACME) V1 Contiguous United States (CONUS) regionally refined model (RRM). This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-734201

  14. Influence of heterogeneity on rock strength and stiffness using discrete element method and parallel bond model

    Directory of Open Access Journals (Sweden)

    Spyridon Liakas

    2017-08-01

    Full Text Available The particulate discrete element method (DEM can be employed to capture the response of rock, provided that appropriate bonding models are used to cement the particles to each other. Simulations of laboratory tests are important to establish the extent to which those models can capture realistic rock behaviors. Hitherto the focus in such comparison studies has either been on homogeneous specimens or use of two-dimensional (2D models. In situ rock formations are often heterogeneous, thus exploring the ability of this type of models to capture heterogeneous material behavior is important to facilitate their use in design analysis. In situ stress states are basically three-dimensional (3D, and therefore it is important to develop 3D models for this purpose. This paper revisits an earlier experimental study on heterogeneous specimens, of which the relative proportions of weaker material (siltstone and stronger, harder material (sandstone were varied in a controlled manner. Using a 3D DEM model with the parallel bond model, virtual heterogeneous specimens were created. The overall responses in terms of variations in strength and stiffness with different percentages of weaker material (siltstone were shown to agree with the experimental observations. There was also a good qualitative agreement in the failure patterns observed in the experiments and the simulations, suggesting that the DEM data enabled analysis of the initiation of localizations and micro fractures in the specimens.

  15. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  16. Implementation of a Stress-dependent Strength Material Model in PLAXIS 3D

    DEFF Research Database (Denmark)

    Knudsen, Bjørn S.; Østergaard, Martin Underlin; Clausen, Johan

    To perform tests on bucket foundations, full-scale testing is rarely used since it is rather expensive. Instead small-scale testing is done to examine the static and dynamic behaviour of such structures. In the laboratory at Aalborg University, small-scale testing of offshore support structures can...... be performed in a pressure tank, where a pressure can be applied in order to simulate deep water situations. Since the test set-up is downscaled 15 to 30 times compared to real-life structures, stresses and strains will be downscaled too. For soils, normally a Mohr-Coulomb failure criterion is used......, and in the region of small stresses, a non-linear behaviour is observed - unlike the linear behaviour normally assumed in Mohr-Coulomb. To better model this non-linearity, a stress-dependent model for the strength of the soil material is sought to be implemented in PLAXIS 3D through FORTRAN to improve...

  17. Adaptive hatching hypotheses do not explain asynchronous ...

    African Journals Online (AJOL)

    At the core of the suite of adaptive hatching hypotheses advanced to explain asynchronous hatching in birds is the assumption that if food is not limited then all the hatchlings will develop normally to adulthood. In this study Brown-headed Parrot Poicephalus cryptoxanthus chicks were hand fed and weighed on a daily basis.

  18. Scientific'Laws','Hypotheses' and'Theories'

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 12. Scientific 'Laws', 'Hypotheses' and 'Theories' - How are They Related? J R Lakshmana Rao. General Article Volume 3 Issue 12 December 1998 pp 55-61. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Modeling and experiments on the drive characteristics of high-strength water hydraulic artificial muscles

    Science.gov (United States)

    Zhang, Zengmeng; Hou, Jiaoyi; Ning, Dayong; Gong, Xiaofeng; Gong, Yongjun

    2017-05-01

    Fluidic artificial muscles are popular in robotics and function as biomimetic actuators. Their pneumatic version has been widely investigated. A novel water hydraulic artificial muscle (WHAM) with high strength is developed in this study. WHAMs can be applied to underwater manipulators widely used in ocean development because of their environment-friendly characteristics, high force-to-weight ratio, and good bio-imitability. Therefore, the strength of WHAMs has been improved to fit the requirements of underwater environments and the work pressure of water hydraulic components. However, understanding the mechanical behaviors of WHAMs is necessary because WHAMs use work media and pressure control that are different from those used by pneumatic artificial muscles. This paper presents the static and dynamic characteristics of the WHAM system, including the water hydraulic pressure control circuit. A test system is designed and built to analyze the drive characteristics of the developed WHAM. The theoretical relationships among the amount of contraction, pressure, and output drawing force of the WHAM are tested and verified. A linearized transfer function is proposed, and the dynamic characteristics of the WHAM are investigated through simulation and inertia load experiments. Simulation results agree with the experimental results and show that the proposed model can be applied to the control of WHAM actuators.

  20. Computer Modeling of the Dynamic Strength of Metal-Plastic Cylindrical Shells Under Explosive Loading

    Science.gov (United States)

    Abrosimov, N. A.; Novosel'tseva, N. A.

    2017-05-01

    A technique for numerically analyzing the dynamic strength of two-layer metal-plastic cylindrical shells under an axisymmetric internal explosive loading is developed. The kinematic deformation model of the layered package is based on a nonclassical theory of shells. The geometric relations are constructed using relations of the simplest quadratic version of the nonlinear elasticity theory. The stress and strain tensors in the composite macrolayer are related by Hooke's law for an orthotropic body with account of degradation of the stiffness characteristics of the multilayer package due to local failure of some its elementary layers. The physical relations in the metal layer are formulated in terms of a differential theory of plasticity. An energy-correlated resolving system of dynamic equations for the metal-plastic cylindrical shells is derived by minimizing the functional of total energy of the shells as three-dimensional bodies. The numerical method for solving the initial boundary-value problem formulated is based on an explicit variational-difference scheme. The reliability of the technique considered is verified by comparing numerical results with experimental data. An analysis of the ultimate strains and strength of one-layer basalt-and glass-fiber-reinforced plastic and two-layer metalplastic cylindrical shells is carried out.

  1. HyQue: evaluating hypotheses using Semantic Web technologies

    Science.gov (United States)

    2011-01-01

    Background Key to the success of e-Science is the ability to computationally evaluate expert-composed hypotheses for validity against experimental data. Researchers face the challenge of collecting, evaluating and integrating large amounts of diverse information to compose and evaluate a hypothesis. Confronted with rapidly accumulating data, researchers currently do not have the software tools to undertake the required information integration tasks. Results We present HyQue, a Semantic Web tool for querying scientific knowledge bases with the purpose of evaluating user submitted hypotheses. HyQue features a knowledge model to accommodate diverse hypotheses structured as events and represented using Semantic Web languages (RDF/OWL). Hypothesis validity is evaluated against experimental and literature-sourced evidence through a combination of SPARQL queries and evaluation rules. Inference over OWL ontologies (for type specifications, subclass assertions and parthood relations) and retrieval of facts stored as Bio2RDF linked data provide support for a given hypothesis. We evaluate hypotheses of varying levels of detail about the genetic network controlling galactose metabolism in Saccharomyces cerevisiae to demonstrate the feasibility of deploying such semantic computing tools over a growing body of structured knowledge in Bio2RDF. Conclusions HyQue is a query-based hypothesis evaluation system that can currently evaluate hypotheses about the galactose metabolism in S. cerevisiae. Hypotheses as well as the supporting or refuting data are represented in RDF and directly linked to one another allowing scientists to browse from data to hypothesis and vice versa. HyQue hypotheses and data are available at http://semanticscience.org/projects/hyque. PMID:21624158

  2. HyQue: evaluating hypotheses using Semantic Web technologies.

    Science.gov (United States)

    Callahan, Alison; Dumontier, Michel; Shah, Nigam H

    2011-05-17

    Key to the success of e-Science is the ability to computationally evaluate expert-composed hypotheses for validity against experimental data. Researchers face the challenge of collecting, evaluating and integrating large amounts of diverse information to compose and evaluate a hypothesis. Confronted with rapidly accumulating data, researchers currently do not have the software tools to undertake the required information integration tasks. We present HyQue, a Semantic Web tool for querying scientific knowledge bases with the purpose of evaluating user submitted hypotheses. HyQue features a knowledge model to accommodate diverse hypotheses structured as events and represented using Semantic Web languages (RDF/OWL). Hypothesis validity is evaluated against experimental and literature-sourced evidence through a combination of SPARQL queries and evaluation rules. Inference over OWL ontologies (for type specifications, subclass assertions and parthood relations) and retrieval of facts stored as Bio2RDF linked data provide support for a given hypothesis. We evaluate hypotheses of varying levels of detail about the genetic network controlling galactose metabolism in Saccharomyces cerevisiae to demonstrate the feasibility of deploying such semantic computing tools over a growing body of structured knowledge in Bio2RDF. HyQue is a query-based hypothesis evaluation system that can currently evaluate hypotheses about the galactose metabolism in S. cerevisiae. Hypotheses as well as the supporting or refuting data are represented in RDF and directly linked to one another allowing scientists to browse from data to hypothesis and vice versa. HyQue hypotheses and data are available at http://semanticscience.org/projects/hyque.

  3. HyQue: evaluating hypotheses using Semantic Web technologies

    Directory of Open Access Journals (Sweden)

    Callahan Alison

    2011-05-01

    Full Text Available Abstract Background Key to the success of e-Science is the ability to computationally evaluate expert-composed hypotheses for validity against experimental data. Researchers face the challenge of collecting, evaluating and integrating large amounts of diverse information to compose and evaluate a hypothesis. Confronted with rapidly accumulating data, researchers currently do not have the software tools to undertake the required information integration tasks. Results We present HyQue, a Semantic Web tool for querying scientific knowledge bases with the purpose of evaluating user submitted hypotheses. HyQue features a knowledge model to accommodate diverse hypotheses structured as events and represented using Semantic Web languages (RDF/OWL. Hypothesis validity is evaluated against experimental and literature-sourced evidence through a combination of SPARQL queries and evaluation rules. Inference over OWL ontologies (for type specifications, subclass assertions and parthood relations and retrieval of facts stored as Bio2RDF linked data provide support for a given hypothesis. We evaluate hypotheses of varying levels of detail about the genetic network controlling galactose metabolism in Saccharomyces cerevisiae to demonstrate the feasibility of deploying such semantic computing tools over a growing body of structured knowledge in Bio2RDF. Conclusions HyQue is a query-based hypothesis evaluation system that can currently evaluate hypotheses about the galactose metabolism in S. cerevisiae. Hypotheses as well as the supporting or refuting data are represented in RDF and directly linked to one another allowing scientists to browse from data to hypothesis and vice versa. HyQue hypotheses and data are available at http://semanticscience.org/projects/hyque.

  4. Testing Hypotheses About Glacial Cycles Against the Observational Record

    DEFF Research Database (Denmark)

    Kaufmann, Robert; Juselius, Katarina

    2013-01-01

    We estimate an identified cointegrated vector autoregression (CVAR) model of the climate system to test hypotheses about the physical mechanisms that may drive glacial cycles during the late Pleistocene. Results indicate that a permanent doubling of CO2 generates a 11.1oC rise in Antarctic...

  5. Data-driven efficient score tests for deconvolution hypotheses

    NARCIS (Netherlands)

    Langovoy, M.

    2008-01-01

    We consider testing statistical hypotheses about densities of signals in deconvolution models. A new approach to this problem is proposed. We constructed score tests for the deconvolution density testing with the known noise density and efficient score tests for the case of unknown density. The

  6. Cannabis social clubs in Belgium: organizational strengths and weaknesses, and threats to the model.

    Science.gov (United States)

    Decorte, Tom

    2015-02-01

    Cannabis Social Clubs (CSCs) are private organizations or clubs of users that produce cannabis for non-profit distribution to adult members to meet their personal needs without having to turn to the black market. CSCs can be found in many countries, but the term often covers very different empirical realities. Inspired by the Spanish CSCs and similarly taking advantage of a grey area in the Belgian cannabis legislation, Belgian cannabis activists set up the first Belgian CSC in 2006, and there are now at least 5 Belgian CSCs. The paper's main objective is to analyse the (internal) strengths and weaknesses and the (external) opportunities and threats of the model, as it exists today. The paper draws on a review of international literature and qualitative data on the Belgian cannabis social clubs. Field visits and interviews were conducted with each club. We analysed membership application forms, cultivation protocols and contracts with growers, cannabis ownership certificates of members, information leaflets, the clubs' websites, and all media articles and documentaries on the clubs in the Belgian media. The paper describes the membership criteria and house rules, the members' profile, the organization and protocols for cannabis production, the distribution of cannabis through 'exchange fairs', the administrative features of the clubs and their contacts with other CSCs and with local authorities, the drug sector and the media. Belgian CSCs seem not profit-driven, and operate as a system in which cannabis is not too easily available. The clubs have fairly direct control over the quality and the potency of the cannabis they distribute. The model offers important potential opportunities, in terms of economic advantages and monitoring consumption patterns. The main threats to Belgian CSCs consist of attempts to criminalize the model, the emergence of profit-driven clubs and systemic violence from criminal entrepreneurs. Weaknesses of the model relate to the unstable or

  7. Yield strengths of flows on the earth, Mars, and moon. [application of Bingham plastic model to lava flows

    Science.gov (United States)

    Moore, H. J.; Arthur, D. W. G.; Schaber, G. G.

    1978-01-01

    Dimensions of flows on the earth, Mars, and moon and their topographic gradients obtained from remote measurements are used to calculate yield strengths with a view to explore the validity of the Bingham plastic model and determine whether there is a relation between yield strengths and silica contents. Other factors are considered such as the vagaries of natural phenomena that might contribute to erroneous interpretations and measurements. Comparison of yield strengths of Martian and lunar flows with terrestrial flows suggests that the Martian and lunar flows are more akin to terrestrial basalts than they are to terrestrial andesites, trachytes, and rhyolites.

  8. Singularity hypotheses a scientific and philosophical assessment

    CERN Document Server

    Moor, James; Søraker, Johnny; Steinhart, Eric

    2012-01-01

    Singularity Hypotheses: A Scientific and Philosophical Assessment offers authoritative, jargon-free essays and critical commentaries on accelerating technological progress and the notion of technological singularity. It focuses on conjectures about the intelligence explosion, transhumanism, and whole brain emulation. Recent years have seen a plethora of forecasts about the profound, disruptive impact that is likely to result from further progress in these areas. Many commentators however doubt the scientific rigor of these forecasts, rejecting them as speculative and unfounded. We therefore invited prominent computer scientists, physicists, philosophers, biologists, economists and other thinkers to assess the singularity hypotheses. Their contributions go beyond speculation, providing deep insights into the main issues and a balanced picture of the debate.

  9. A review of shear strength models for rock joints subjected to constant normal stiffness

    Directory of Open Access Journals (Sweden)

    Sivanathan Thirukumaran

    2016-06-01

    Full Text Available The typical shear behaviour of rough joints has been studied under constant normal load/stress (CNL boundary conditions, but recent studies have shown that this boundary condition may not replicate true practical situations. Constant normal stiffness (CNS is more appropriate to describe the stress–strain response of field joints since the CNS boundary condition is more realistic than CNL. The practical implications of CNS are movements of unstable blocks in the roof or walls of an underground excavation, reinforced rock wedges sliding in a rock slope or foundation, and the vertical movement of rock-socketed concrete piles. In this paper, the highlights and limitations of the existing models used to predict the shear strength/behaviour of joints under CNS conditions are discussed in depth.

  10. Analytic EoS and PTW strength model recommendation for Starck Ta

    Energy Technology Data Exchange (ETDEWEB)

    Sjue, Sky K. [Los Alamos National Laboratory; Prime, Michael Bruce [Los Alamos National Laboratory

    2016-09-01

    The purpose of this document is to provide an analytic EoS and PTW strength model for Starck Ta that can be consistently used between different platforms and simulations at three labs. This should provide a consistent basis for comparison of the results of calculations, but not the best implementation for matching a wide variety of experimental data. Another version using SESAME tables should follow, which will provide a better physical representation over a broader range of conditions. The data sets available at the time only include one Hopkinson bar at a strain rate of 1800/s; a broader range of high-rate calibration data would be preferred. The resulting fit gives the PTW parameter p = 0. To avoid numerical issues, p = 0:001 has been used in FLAG. The PTW parameters that apply above the maximum strain rate in the data use the values from the original publication.

  11. New hypotheses regarding the Danish health puzzle.

    Science.gov (United States)

    Bakah, May; Raphael, Dennis

    2017-12-01

    Nordic welfare states have achieved admirable population health profiles as a result of public policies that provide economic and social security across the life course. Denmark has been an exception to this rule, as its life expectancies and infant mortality rates since the mid-1970s have lagged behind the other Nordic nations and, in the case of life expectancy, behind most Organisation for Economic Co-operation and Development nations. In this review paper, we identify a number of new hypotheses for why this may be the case. These hypotheses concern the health effects of neo-liberal restructuring of the economy and its institutions, the institution of flexi-security in Denmark's labour market and the influence of Denmark's tobacco and alcohol industries. Also of note is that Denmark experienced higher unemployment rates during its initial period of health stagnation, as well as its treatment of non-Western immigrants and high wealth inequality and, until recently, the fact that Denmark did not systematically address the issue of health inequalities. These hypotheses may serve as covering explanations for the usually provided accounts of elevated behavioural risks and psychosocial stress as being responsible for Denmark's health profile.

  12. Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys

    Science.gov (United States)

    Mao, Jian

    Precipitation-hardened nickel-based superalloys have been widely used as high temperature structural materials in gas turbine engine applications for more than 50 years. Powder metallurgy (P/M) technology was introduced as an innovative manufacturing process to overcome severe segregation and poor workability of alloys with high alloying contents. The excellent mechanical properties of P/M superalloys also depend upon the characteristic microstructures, including grain size and size distribution of gamma' precipitates. Heat treatment is the most critical processing step that has ultimate influences on the microstructure, and hence, on the mechanical properties of the materials. The main objective of this research was to study the gamma ' precipitation kinetics in various cooling circumstances and also study the strength response to the cooling history in two model alloys, Rne88DT and U720LI. The research is summarized below: (1) An experimental method was developed to allow accurate simulation and control of any desired cooling profile. Two novel cooling methods were introduced: continuous cooling and interrupt cooling. Isothermal aging was also carried out. (2) The growth and coarsening kinetics of the cooling gamma' precipitates were experimentally studied under different cooling and aging conditions, and the empirical equations were established. It was found that the cooling gamma' precipitate versus the cooling rate follows a power law. The gamma' precipitate size versus aging time obeys the LSW cube law for coarsening. (3) The strengthening of the material responses to the cooling rate and the decreasing temperature during cooling was investigated in both alloys. The tensile strength increases with the cooling rate. In addition, the non-monotonic response of strength versus interrupt temperature is of great interest. (4) An energy-driven model integrated with the classic growth and coarsen theories was successfully embedded in a computer program developed to

  13. A cohesive zone model to simulate the hydrogen embrittlement effect on a high-strength steel

    Directory of Open Access Journals (Sweden)

    G. Gobbi

    2016-01-01

    Full Text Available The present work aims to model the fracture mechanical behavior of a high-strength low carbon steel, AISI 4130 operating in hydrogen contaminated environment. The study deals with the development of 2D finite element cohesive zone model (CZM reproducing a toughness test. Along the symmetry plane over the crack path of a C(T specimen a zero thickness layer of cohesive elements are implemented in order to simulate the crack propagation. The main feature of this kind of model is the definition of a traction-separation law (TSL that reproduces the constitutive response of the material inside to the cohesive elements. Starting from a TSL calibrated on hydrogen non-contaminated material, the embrittlement effect is simulated by reducing the cohesive energy according to the total hydrogen content including the lattice sites (NILS and the trapped amount. In this perspective, the proposed model consists of three steps of simulations. First step evaluates the hydrostatic pressure. It drives the initial hydrogen concentration assigned in the second step, a mass diffusion analysis, defining in this way the contribution of hydrogen moving across the interstitial lattice sites. The final stress analysis, allows getting the total hydrogen content, including the trapped amount, and evaluating the new crack initiation and propagation due to the hydrogen presence. The model is implemented in both plane strain and plane stress configurations; results are compared in the discussion. From the analyses, it resulted that hydrogen is located only into lattice sites and not in traps, and that the considered steel experiences a high hydrogen susceptibility. By the proposed procedure, the developed numerical model seems a reliable and quick tool able to estimate the mechanical behavior of steels in presence of hydrogen.

  14. Dynamic rock tensile strengths of Laurentian granite: Experimental observation and micromechanical model

    Directory of Open Access Journals (Sweden)

    Kaiwen Xia

    2017-02-01

    Full Text Available Tensile strength is an important material property for rocks. In applications where rocks are subjected to dynamic loads, the dynamic tensile strength is the controlling parameter. Similar to the study of static tensile strength, there are various methods proposed to measure the dynamic tensile strength of rocks. Here we examine dynamic tensile strength values of Laurentian granite (LG measured from three methods: dynamic direct tension, dynamic Brazilian disc (BD test, and dynamic semi-circular bending (SCB. We found that the dynamic tensile strength from direct tension has the lowest value, and the dynamic SCB gives the highest strength at a given loading rate. Because the dynamic direct tension measures the intrinsic rock tensile strength, it is thus necessary to reconcile the differences in strength values between the direct tension and the other two methods. We attribute the difference between the dynamic BD results and the direct tension results to the overload and internal friction in BD tests. The difference between the dynamic SCB results and the direct tension results can be understood by invoking the non-local failure theory. It is shown that, after appropriate corrections, the dynamic tensile strengths from the two other tests can be reduced to those from direct tension.

  15. Evaluating Internal Model Strength and Performance of Myoelectric Prosthesis Control Strategies.

    Science.gov (United States)

    Shehata, Ahmed W; Scheme, Erik J; Sensinger, Jonathon W

    2018-05-01

    On-going developments in myoelectric prosthesis control have provided prosthesis users with an assortment of control strategies that vary in reliability and performance. Many studies have focused on improving performance by providing feedback to the user but have overlooked the effect of this feedback on internal model development, which is key to improve long-term performance. In this paper, the strength of internal models developed for two commonly used myoelectric control strategies: raw control with raw feedback (using a regression-based approach) and filtered control with filtered feedback (using a classifier-based approach), were evaluated using two psychometric measures: trial-by-trial adaptation and just-noticeable difference. The performance of both strategies was also evaluated using Schmidt's style target acquisition task. Results obtained from 24 able-bodied subjects showed that although filtered control with filtered feedback had better short-term performance in path efficiency ( ), raw control with raw feedback resulted in stronger internal model development ( ), which may lead to better long-term performance. Despite inherent noise in the control signals of the regression controller, these findings suggest that rich feedback associated with regression control may be used to improve human understanding of the myoelectric control system.

  16. Research and application of fuzzy subtractive clustering model on tensile strength of radiation vulcanization for nitrile-butadiene rubber

    International Nuclear Information System (INIS)

    Zuo Duwen; Wang Hong; Zhu Nankang

    2010-01-01

    By use of fuzzy subtractive clustering model, the relationship between tensile strength of radiation vulcanization of NBRL (Nitrile-butadiene rubber latex) and irradiation parameters have been investigated. The correlation coefficient was calculated to be 0.8222 in the comparison of experimental data to the predicted data. It was obvious that fuzzy model identification method is not only high precision with small computation, but also easy to be used. It can directly supply the evolution of tensile strength of NBR by fuzzy modeling method in radiation vulcanization process for nitrile-butadiene rubber. (authors)

  17. Statistical modeling of tear strength for one step fixation process of reactive printing and easy care finishing

    International Nuclear Information System (INIS)

    Asim, F.; Mahmood, M.

    2017-01-01

    Statistical modeling imparts significant role in predicting the impact of potential factors affecting the one step fixation process of reactive printing and easy care finishing. Investigation of significant factors on tear strength of cotton fabric for single step fixation of reactive printing and easy care finishing has been carried out in this research work using experimental design technique. The potential design factors were; concentration of reactive dye, concentration of crease resistant, fixation method and fixation temperature. The experiments were designed using DoE (Design of Experiment) and analyzed through software Design Expert. The detailed analysis of significant factors and interactions including ANOVA (Analysis of Variance), residuals, model accuracy and statistical model for tear strength has been presented. The interaction and contour plots of vital factors has been examined. It has been found from the statistical analysis that each factor has an interaction with other factor. Most of the investigated factors showed curvature effect on other factor. After critical examination of significant plots, quadratic model of tear strength with significant terms and their interaction at alpha = 0.05 has been developed. The calculated correlation coefficient, R2 of the developed model is 0.9056. The high values of correlation coefficient inferred that developed equation of tear strength will precisely predict the tear strength over the range of values. (author)

  18. Accumulative job demands and support for strength use: Fine-tuning the job demands-resources model using conservation of resources theory.

    Science.gov (United States)

    van Woerkom, Marianne; Bakker, Arnold B; Nishii, Lisa H

    2016-01-01

    Absenteeism associated with accumulated job demands is a ubiquitous problem. We build on prior research on the benefits of counteracting job demands with resources by focusing on a still untapped resource for buffering job demands-that of strengths use. We test the idea that employees who are actively encouraged to utilize their personal strengths on the job are better positioned to cope with job demands. Based on conservation of resources (COR) theory, we hypothesized that job demands can accumulate and together have an exacerbating effect on company registered absenteeism. In addition, using job demands-resources theory, we hypothesized that perceived organizational support for strengths use can buffer the impact of separate and combined job demands (workload and emotional demands) on absenteeism. Our sample consisted of 832 employees from 96 departments (response rate = 40.3%) of a Dutch mental health care organization. Results of multilevel analyses indicated that high levels of workload strengthen the positive relationship between emotional demands and absenteeism and that support for strength use interacted with workload and emotional job demands in the predicted way. Moreover, workload, emotional job demands, and strengths use interacted to predict absenteeism. Strengths use support reduced the level of absenteeism of employees who experienced both high workload and high emotional demands. We conclude that providing strengths use support to employees offers organizations a tool to reduce absenteeism, even when it is difficult to redesign job demands. (c) 2016 APA, all rights reserved).

  19. Composition design of superhigh strength maraging stainless steels using a cluster model

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2014-02-01

    Full Text Available The composition characteristics of maraging stainless steels were studied in the present work investigation using a cluster-plus-glue-atom model. The least solubility limit of high-temperature austenite to form martensite in basic Fe–Ni–Cr corresponds to the cluster formula [NiFe12]Cr3, where NiFe12 is a cuboctahedron centered by Ni and surrounded by 12 Fe atoms in FCC structure and Cr serves as glue atoms. A cluster formula [NiFe12](Cr2Ni with surplus Ni was then determined to ensure the second phase (Ni3M precipitation, based on which new multi-component alloys [(Ni,Cu16Fe192](Cr32(Ni,Mo,Ti,Nb,Al,V16 were designed. These alloys were prepared by copper mould suction casting method, then solid-solution treated at 1273 K for 1 h followed by water-quenching, and finally aged at 783 K for 3 h. The experimental results showed that the multi-element alloying results in Ni3M precipitation on the martensite, which enhances the strengths of alloys sharply after ageing treatment. Among them, the aged [(Cu4Ni12Fe192](Cr32(Ni8.5Mo2Ti2Nb0.5Al1V1 alloy (Fe74.91Ni8.82Cr11.62Mo1.34Ti0.67Nb0.32Al0.19V0.36Cu1.78 wt% has higher tensile strengths with YS=1456 MPa and UTS=1494 MPa. It also exhibits good corrosion-resistance in 3.5 wt% NaCl solution.

  20. Intrinsic rewards, fruit and vegetable consumption, and habit strength: a three-wave study testing the associative-cybernetic model.

    Science.gov (United States)

    Wiedemann, Amelie U; Gardner, Benjamin; Knoll, Nina; Burkert, Silke

    2014-03-01

    Habit formation is thought to lead to long-term maintenance of fruit and vegetable consumption. Habits develop through context-dependent repetition, but additional variables such as intrinsic reward of behaviour may influence habit strength. Drawing upon the Associative-Cybernetic Model, this exploratory study tested different pathways by which intrinsic reward may influence fruit and vegetable consumption habit strength. In a three-wave study of fruit and vegetable intake in adults (N = 127) from the general population, intrinsic reward, intention, and self-efficacy were assessed at baseline, fruit and vegetable consumption and intrinsic reward two weeks later, and habit strength another two weeks later. Direct, indirect, and moderation effects of intrinsic reward on habit strength were tested simultaneously in a moderated mediation model. Intrinsic reward had a positive indirect effect on habit strength through its influence on the frequency of fruit and vegetable consumption. Further, the relationship between fruit and vegetable consumption and habit was stronger where consumption was considered more intrinsically rewarding. Findings highlight the potential relevance of intrinsic reward to habit. We suggest that intrinsic rewards from behaviour may not only facilitate habit via behaviour frequency, but also reinforce the relationship between behavioural repetition and habit strength. © 2013 The International Association of Applied Psychology.

  1. Strength analysis and modeling of cellular lattice structures manufactured using selective laser melting for tooling applications

    DEFF Research Database (Denmark)

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus

    2016-01-01

    in injection molding tools and lattice structures. This research examines the effect of cellular lattice structures on the strength of workpieces additively manufactured from ultra high-strength steel powder. Two commercial SLM machines are used to fabricate cellular samples based on four architectures— solid...... with experimental data and it is shown that they agree well. The results from this research show that using lattice structures significantly reduces the strength of material with respect to solid samples while indicating no serious increase of strength compared to hollow structures. In combination with an analysis...

  2. A Simplified Model for the Effect of Weld-Induced Residual Stresses on the Axial Ultimate Strength of Stiffened Plates

    Science.gov (United States)

    Chen, Bai-Qiao; Guedes Soares, C.

    2018-03-01

    The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.

  3. Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

    Science.gov (United States)

    Bradshaw, James F.; Sandefur, Paul G., Jr.; Young, Clarence P., Jr.

    1991-01-01

    A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

  4. Of Mental Models, Assumptions and Heuristics: The Case of Acids and Acid Strength

    Science.gov (United States)

    McClary, LaKeisha Michelle

    2010-01-01

    This study explored what cognitive resources (i.e., units of knowledge necessary to learn) first-semester organic chemistry students used to make decisions about acid strength and how those resources guided the prediction, explanation and justification of trends in acid strength. We were specifically interested in the identifying and…

  5. Constant conditional entropy and related hypotheses

    International Nuclear Information System (INIS)

    Ferrer-i-Cancho, Ramon; Dębowski, Łukasz; Moscoso del Prado Martín, Fermín

    2013-01-01

    Constant entropy rate (conditional entropies must remain constant as the sequence length increases) and uniform information density (conditional probabilities must remain constant as the sequence length increases) are two information theoretic principles that are argued to underlie a wide range of linguistic phenomena. Here we revise the predictions of these principles in the light of Hilberg’s law on the scaling of conditional entropy in language and related laws. We show that constant entropy rate (CER) and two interpretations for uniform information density (UID), full UID and strong UID, are inconsistent with these laws. Strong UID implies CER but the reverse is not true. Full UID, a particular case of UID, leads to costly uncorrelated sequences that are totally unrealistic. We conclude that CER and its particular cases are incomplete hypotheses about the scaling of conditional entropies. (letter)

  6. Dental Hypotheses: Seeks to Publish Hypotheses from All Areas of Dentistry

    Directory of Open Access Journals (Sweden)

    Edward F. Rossomando

    2010-07-01

    Full Text Available Starting a new open access journal in a rapid growing scientific panorama is a severe challenge. However, the first issue of dental hypotheses is now history and the even skeptics can appreciate that dental hypotheses is a success - it is a journal of high quality that provides an outlet for publication of articles that encourage readers to question dental paradigms. But dental hypotheses readers might have noticed that the majority of the articles published in the first issue of dental hypotheses concern clinical dentistry. However, dental hypotheses editors recognize that there are many other areas in dentistry that present challenges and that our readers may offer suggestions for their solution. Some of these challenges relate to: dental education; digital dental technology; teledentistry and access to dental care; dental practice issues, such as, dental office design, dental office management, the slow rate of acceptance of innovative technology in the dental office; and issues related to innovation and dental entrepreneurship including intellectual property protection. Nevertheless, the dental profession faces many challenges - in many areas - and with the publication of dental hypotheses our profession has a venue for presentation of possible solutions. If you have developed a hypothesis that might help, please share it with your colleagues. As many have noted, the intellectual power of the global village in which we now live is formidable. The internet has provided the technology to bring us together and dental hypotheses has provided the venue. Please use it. New radical, speculative and non-mainstream scientific ideas are always welcome.

  7. Modeling of Cyclic Strength for the Asphalt Concrete Considering Damage Accumulation

    Directory of Open Access Journals (Sweden)

    Alibai Iskakbayev

    2017-12-01

    Full Text Available The expression is obtained for determination of cyclic tensile strength for asphalt concrete, which considers damage accumulation and history of loading, using the long-term strength curve for asphalt concrete obtained according to the test results of more than 110 samples to failure at stresses from 0.05 to 0.31 MPa and by introduction of damage kernel in this paper. Cyclic strength depends on the stress, parameters of long-term strength, frequency of loading, durations of loading and relax periods, and ratio of loading period to the long-term strength. Evaluation of accuracy for the obtained expression for the cyclic strength has been performed by comparison with the results of a series for experimental tests of asphalt concrete samples at a temperature of 22 °С and cyclic loading conditions. The stress is 0.31 MPa, and the durations of loading and relax periods are 5 and 60 s, respectively. Calculations performed with the obtained expressions at real road conditions (the stress is 0.31 MPa, and the durations of loading and relax periods are 0.1 and 9.9 s respectively showed the possibility of its use for the prediction of fatigue (multicyclic strength of an asphalt concrete pavement for a highway.

  8. A model of mitochondrial creatine kinase binding to membranes: adsorption constants, essential amino acids and the effect of ionic strength

    DEFF Research Database (Denmark)

    Fedosov, Sergey; Belousova, Lubov; Plesner, Igor

    1993-01-01

    The quantitative aspects of mitochondrial creatinekinase (mitCK) binding to mitochondrial membranes were investigated. A simple adsorption and binding model was used for data fitting, taking into account the influence of protein concentration, pH, ionic strength and substrate concentration on the...

  9. artificial neural network model for low strength rc beam shear capacity

    African Journals Online (AJOL)

    User

    RESEARCH PAPER. Keywords: Shear strength, reinforced concrete, Artificial Neural Network, design equations ... searchers using artificial intelligence to im- prove on theoretical ...... benefit to humanity or a waste of time?” The. Structural ...

  10. Dike Strength Analysis on a Regional Scale Based On a Stochastic Subsoil Model

    Science.gov (United States)

    Koelewijn, A. R.; Vastenburg, E. W.

    2013-12-01

    [Knoeff et al. 2011] J.G. Knoeff, E.W. Vastenburg, G.A. van den Ham & J. Lopez de la Cruz, Automated levee flood risk management, 5th Int. Conf. on Flood Management, Tokyo, 2011 [Koelewijn et al. 2011] A.R. Koelewijn, G.A.M. Kruse & J. Pruiksma, Stochastic subsoil modelling - first set-up of the model and reliability analyses, report 12042000-002-HYE-0001, Deltares, Delft, 2011 [In Dutch] [Lam et al. 2013] K.S. Lam, P.W. Gill & L.W.A. Zwang, Implementation of new levee strength modules for continuous safety assessments, Comprehensive Flood Risk Managment, Taylor & Francis, London, 2013, 317-326. Dike sections with stochastic subsoil profiles.

  11. Research on NDT Technology in Inference of Steel Member Strength Based on Macro/Micro Model

    Directory of Open Access Journals (Sweden)

    Beidou Ding

    2017-01-01

    Full Text Available In consideration of correlations among hardness, chemical composition, grain size, and strength of carbon steel, a new nondestructive testing technology (NDT of inferring the carbon steel strength was explored. First, the hardness test, chemical composition analysis, and metallographic analysis of 162 low-carbon steel samples were conducted. Second, the following works were carried out: (1 quantitative relationship between steel Leeb hardness and carbon steel strength was studied on the basis of regression analysis of experimental data; (2 influences of chemical composition and grain size on tension properties of carbon steel were analyzed on the basis of stepwise regression analysis, and quantitative relationship between conventional compositions and grain size with steel strength was obtained; (3 according to the macro and/or micro factors such as hardness, chemical compositions, and grain size of carbon steel, the fitting formula of steel strength was established based on MLR (multiple linear regressions method. The above relationships and fitting formula based on MLR method could be used to estimate the steel strength with no damage to the structure in engineering practice.

  12. Electroconvulsive therapy's mechanism of action: neuroendocrine hypotheses.

    Science.gov (United States)

    Haskett, Roger F

    2014-06-01

    Despite a range of etiological theories since the introduction of electroconvulsive therapy (ECT) more than 75 years ago, its mechanism of action remains poorly understood. The neuroendocrine hypothesis is based on the seizure-related release of hypothalamic hormones into the blood and cerebrospinal fluid and evidence of endocrine dysfunction in many patients with severe mood disorder. The specific effect of ECT was hypothesized to result from the transverse passage of current through the brain with direct stimulation of axial structures including the diencephalon. The prompt release of adrenocorticotropic hormone, cortisol, and prolactin into blood followed ECT with a return to pretreatment baseline levels in several hours. The elevated levels of hormones were absorbed by the cerebrospinal fluid, providing contact with brain cells and central nervous system structures. An apparently specific pattern of ECT-induced hormone changes, limited to prolactin and cortisol, suggested that ECT released a substance with dopaminergic antagonist and antipsychotic properties. As hypothalamic dysfunction is a key finding in endogenomorphic depression and the abnormal endocrine and physiological functions usually normalize with recovery, this led to a search for biological markers that would supplement clinical assessment of diagnosis and treatment response. One of these, the overnight dexamethasone suppression test found that 40% to 50% of melancholic depressed patients had abnormal results, whereas 90% of control patients suppressed normally. This was followed by a period of uncritical overenthusiasm followed by wholesale rejection of the clinical neuroendocrine strategies. Several key methodological issues received inadequate attention, and there have been calls to revisit this topic.

  13. Strength and deformational characteristics of three-way reinforced concrete containment models subjected to lateral forces

    International Nuclear Information System (INIS)

    Aoyagi, Y.; Yamada, K.; Takahashi, T.

    1981-01-01

    With a view to investigating the earthquake resistance characteristics of reinforced concrete containments two cylindrical models with three-way system of bars were made and loaded laterally up to failure combined with or without internal pressures, simulating the conditions in which containments were subjected to earthquake forces at a simultaneous LOCA or at normal operation. The main conclusions obtained withing the limit of the experiments are as follows. (1) Stresses in reinforcements in three-way reinforced concrete plate elements can reasonably be estimated by the equations proposed by Baumann. It is, however, necessary to take into consideration the contributions of concrete between cracks to the deformation in order to accurately estimate the average strains in the plate elements, applying such a formula as CEB as reformed by the authors. (2) The strength capacity of three-way reinforced concrete containments against lateral forces combined with internal pressure is somewhat inferior to that of orthogonally reinforced one if compared on the condition that the volumetric reinforcement ratios are the same for the two cases of reinforcement arrangements. However, three-way reinforcement improves initial shear rigidity as well as ultimate horizontal deformability for lateral forces. (3) The ability for three-way reinforced concrete containment to absorb strain energy in the range of large deformations is superior to that of orthogonally reinforced one. The equivalent viscous damping coefficient for the former is markedly larger than that for the latter, especially at the increased deformational stages. These experimental evidences suggent that three-way system of reinforcement may constitute one of the prospective measures to improve the earthquake resistance of reinforced concrete containments. (orig./HP)

  14. Modeling of hot tensile and short-term creep strength for LWR piping materials under severe accident conditions

    International Nuclear Information System (INIS)

    Harada, Y.; Maruyama, Y.; Chino, E.; Shibazaki, H.; Kudo, T.; Hidaka, A.; Hashimoto, K.; Sugimoto, J.

    2000-01-01

    The analytical study on severe accident shows the possibility of the reactor coolant system (RCS) piping failure before reactor pressure vessel failure under the high primary pressure sequence at pressurized water reactors. The establishment of the high-temperature strength model of the realistic RCS piping materials is important in order to predict precisely the accident progression and to evaluate the piping behavior with small uncertainties. Based on material testing, the 0.2% proof stress and the ultimate tensile strength above 800degC were given by the equations of second degree as a function of the reciprocal absolute temperature considering the strength increase due to fine precipitates for the piping materials. The piping materials include type 316 stainless steel, type 316 stainless steel of nuclear grade, CF8M cast duplex stainless steel and STS410 carbon steel. Also the short-term creep rupture time and the minimum creep rate at high-temperature were given by the modified Norton's Law as a function of stress and temperature considering the effect of the precipitation formation and resolution on the creep strength. The present modified Norton's Law gives better results than the conventional Larson-Miller method. Correlating the creep data (the applied stress versus the minimum creep rate) with the tensile data (the 0.2% proof stress or the ultimate tensile strength versus the strain rate), it was found that the dynamic recrystallization significantly occurred at high-temperature. (author)

  15. Modelling and assessment of the electric field strength caused by mobile phone to the human head

    Directory of Open Access Journals (Sweden)

    Buckus Raimondas

    2016-01-01

    Full Text Available Background/Aim. Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. Methods. In this paper the software “COMSOL Multiphysics” was used to establish the electric field strength created by mobile phones around the head. Results. The second generation (2G Global System for Mobile (GSM phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G UMTS smart phones that effectively use high (2,100 MHz radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear, and constitutes 1-12% of the artificial head’s surface. Conclusion. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user ear.

  16. Modelling and assessment of the electric field strength caused by mobile phone to the human head.

    Science.gov (United States)

    Buckus, Raimondas; Strukcinskiene, Birute; Raistenskis, Juozas; Stukas, Rimantas

    2016-06-01

    Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. In this paper the software "COMSOL Multiphysics" was used to establish the electric field strength created by mobile phones around the head. The second generation (2G) Global System for Mobile (GSM) phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G) GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G) UMTS smart phones that effectively use high (2,100 MHz) radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear), and constitutes 1-12% of the artificial head's surface. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR) and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user's ear.

  17. Mathematical model to compare the relative tensile strength of the cornea after PRK, LASIK, and small incision lenticule extraction.

    Science.gov (United States)

    Reinstein, Dan Z; Archer, Timothy J; Randleman, J Bradley

    2013-07-01

    To develop a mathematical model to estimate the relative differences in postoperative stromal tensile strength following photorefractive keratectomy (PRK), LASIK, and small incision lenticule extraction (SMILE). Using previously published data where in vitro corneal stromal tensile strength was determined as a function of depth, a mathematical model was built to calculate the relative remaining tensile strength by fitting the data with a fourth order polynomial function yielding a high correlation coefficient (R(2) = 0.930). Calculating the area under this function provided a measure of total stromal tensile strength (TTS), based only on the residual stromal layer for PRK or LASIK and the residual stromal layers above and below the lenticule interface for SMILE. Postoperative TTS was greatest after SMILE, followed by PRK, then LASIK; for example, in a 550-μm cornea after 100-μm tissue removal, postoperative TTS was 75% for SMILE (130-μm cap), 68% for PRK, and 54% for LASIK (110-μm flap). The postoperative TTS decreased for thinner corneal pachymetry for all treatment types. In LASIK, the postoperative TTS decreased with increasing flap thickness by 0.22%/μm, but increased by 0.08%/μm for greater cap thickness in SMILE. The model predicted that SMILE lenticule thickness could be approximately 100 μm greater than the LASIK ablation depth and still have equivalent corneal strength (equivalent to approximately 7.75 diopters). This mathematical model predicts that the postoperative TTS is considerably higher after SMILE than both PRK and LASIK, as expected given that the strongest anterior lamellae remain intact. Consequently, SMILE should be able to correct higher levels of myopia. Copyright 2013, SLACK Incorporated.

  18. Infliximab's influence on anastomotic strength and degree of inflammation in intestinal surgery in a rabbit model

    DEFF Research Database (Denmark)

    Frostberg, Erik; Ström, Petter; Gerke, Oke

    2014-01-01

    and conclusions. The purpose of this study was to investigate whether a single dose infliximab has an adverse effect on the anastomotic healing process, observed as reduced anastomotic breaking strength and histopathologically verified lower grade of inflammatory response, in the small intestine of a rabbit....... METHODS: Thirty New Zealand rabbits (median weight 2.5 kg) were allocated to treatment with an intravenous bolus of either 10 mg/kg infliximab (n = 15) or placebo (n = 15). One week later all rabbits underwent two separate end-to-end anastomoses in the jejunum under general anesthesia. At postoperative...... day three, the anastomotic breaking strength was determined and histopathological changes were examined. RESULTS: The mean value of anastomotic breaking strength in the placebo group was 1.89 +/- 0.36 N and the corresponding value was 1.81 +/- 0.33 N in the infliximab treated rabbits...

  19. A structural equation model of the relationship between muscle strength, balance performance, walking endurance and community integration in stroke survivors.

    Directory of Open Access Journals (Sweden)

    P W H Kwong

    Full Text Available To use structural equation modelling (SEM to determine (1 the direct and indirect associations of strength of paretic lower limb muscles with the level of community integration, and (2 the direct association of walking endurance and balance performance with the level of community integration in community-dwelling stroke survivors.In this cross-sectional study of 105 stroke survivors, the Subjective Index of Physical and Social Outcome (SIPSO was used to measure the level of community integration. Lower-limb strength measures included isometric paretic ankle strength and isokinetic paretic knee peak torque. The Berg Balance Scale (BBS and the 6-minute walk test (6MWT were used to evaluate balance performance and walking endurance, respectively.SEM revealed that the distance walked on the 6MWT had the strongest direct association with the SIPSO score (β = 0.41, p <0.001. An increase of one standard deviation in the 6MWT distance resulted in an increase of 0.41 standard deviations in the SIPSO score. Moreover, dorsiflexion strength (β = 0.18, p = 0.044 and the BBS score (β = 0.21, p = 0.021 had direct associations with the SIPSO score.The results of the proposed model suggest that rehabilitation training of community-dwelling stroke survivors could focus on walking endurance, balance performance and dorsiflexor muscle strengthening if the aim is to augment the level of community integration.

  20. The effects of honey (Apis dorsata) supplements on increased bone strength in ovariectomized rat as animal model of osteoporosis

    Science.gov (United States)

    Yudaniayanti, Ira Sari; Primarizky, Hardany; Nangoi, Lianny

    2018-04-01

    Osteoporosis is a chronic skeletal disease characterized by low bone mass and microarchitectural deterioration with a consequent increase in bone fragility and fracture risk. The aim of the study was to evaluate the effects of honey (Apis dorsata) supplements on increased bone strength in ovariectomized rat as animal models of osteoporosis. Twenty female rats at 3 months of age, weighing 150-200 g were used in the study. The rats were divided into five groups (n=4) : Sham operation group (SH); ovariectomy group no treatment(OVX); ovariectomy with treatment Apis dorsata 1g/Kg BW (AD-1); ovariectomy with treatment Apis dorsata 2g/Kg BW (AD-2); ovariectomy with treatment Apis dorsata 4g/Kg BW (AD-3). The treatment started to be given the next day after ovariectomy operation for 12 weeks. The Rats were sacrified within 12 weeks, and then the right femur were taken bone strength test. Based on the statistical analysis of the bone strength test, the greatest score belongs to the Sham operation group (SH) that have significant difference (p0,05). In conclusion, honey (Apis dorsata) supplements has the effect of increasing bone strength in ovariectomized rat as animal models of osteoporosis, so that honey (Apis dorsata) supplements has the potential to be used as an alternative treatment for osteoporosis.

  1. Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out.

    Science.gov (United States)

    Pujari-Palmer, Michael; Robo, Celine; Persson, Cecilia; Procter, Philip; Engqvist, Håkan

    2018-01-01

    Disease and injuries that affect the skeletal system may require surgical intervention and internal fixation, i.e. orthopedic plate and screw insertion, to stabilize the injury and facilitate tissue repair. If the surrounding bone quality is poor the screws may migrate, or the bone may fail, resulting in fixation failure. While numerous studies have shown that cement augmentation of the interface between bone and implant can increase screw pull-out force, the physical properties of cement that influence pull-out force have not been investigated. The present study sought to determine how the physical properties of high strength calcium phosphate cements (hsCPCs, specifically dicalcium phosphate) affected the corresponding orthopedic screw pull-out force in urethane foam models of "healthy" and "osteoporotic" synthetic bone (Sawbones). In the simplest model, where only the bond strength between screw thread and cement (without Sawbone) was tested, the correlation between pull-out force and cement compressive strength (R 2 = 0.79) was weaker than correlation with total cement porosity (R 2 = 0.89). In open pore Sawbone that mimics "healthy" cancellous bone density the stronger cements produced higher pull-out force (50-60% increase). High strength, low porosity cements also produced higher pull-out forces (50-190% increase) in "healthy" Sawbones with cortical fixation if the failure strength of the cortical material was similar to, or greater than (a metal shell), actual cortical bone. This result is of particular clinical relevance where fixation with a metal plate implant is indicated, as the nearby metal can simulate a thicker cortical shell, thereby increasing the pull-out force of screws augmented with stronger cements. The improvement in pull-out force was apparent even at low augmentation volumes of 0.5mL (50% increase), which suggest that in clinical situations where augmentation volume is limited the stronger, lower porosity calcium phosphate cement (CPC) may

  2. Prediction Model of Cutting Parameters for Turning High Strength Steel Grade-H: Comparative Study of Regression Model versus ANFIS

    Directory of Open Access Journals (Sweden)

    Adel T. Abbas

    2017-01-01

    Full Text Available The Grade-H high strength steel is used in the manufacturing of many civilian and military products. The procedures of manufacturing these parts have several turning operations. The key factors for the manufacturing of these parts are the accuracy, surface roughness (Ra, and material removal rate (MRR. The production line of these parts contains many CNC turning machines to get good accuracy and repeatability. The manufacturing engineer should fulfill the required surface roughness value according to the design drawing from first trail (otherwise these parts will be rejected as well as keeping his eye on maximum metal removal rate. The rejection of these parts at any processing stage will represent huge problems to any factory because the processing and raw material of these parts are very expensive. In this paper the artificial neural network was used for predicting the surface roughness for different cutting parameters in CNC turning operations. These parameters were investigated to get the minimum surface roughness. In addition, a mathematical model for surface roughness was obtained from the experimental data using a regression analysis method. The experimental data are then compared with both the regression analysis results and ANFIS (Adaptive Network-based Fuzzy Inference System estimations.

  3. Modeling the Effect of Nail Corrosion on the Lateral Strength of Joints

    Science.gov (United States)

    Samuel L. Zelinka; Douglas R. Rammer

    2012-01-01

    This article describes a theoretical method of linking fastener corrosion in wood connections to potential reduction in lateral shear strength. It builds upon published quantitative data of corrosion rates of metals in contact with treated wood for several different wood preservatives. These corrosion rates are then combined with yield theory equations to calculate a...

  4. Size effect model for the edge strength of glass with cut and ground edge finishing

    NARCIS (Netherlands)

    Vandebroek, M.; Louter, C.; Caspeele, R.; Ensslen, F.; Belis, J.L.I.F.

    2014-01-01

    The edge strength of glass is influenced by the size of the surface (near the edge) which is subjected to tensile stresses. To quantify this size effect, 8 series of single layer annealed glass beam specimens (as-received glass) were subjected to in-plane four-point bending with linearly increased

  5. Development and Validation of a Rule-Based Strength Scaling Method for Musculoskeletal Modelling

    DEFF Research Database (Denmark)

    Oomen, Pieter; Annegarn, Janneke; Rasmussen, John

    2015-01-01

    performed maximal isometric knee extensions. A multiple linear regression analysis (MLR) resulted in an empirical strength scaling equation, accounting for age, mass, height, gender, segment masses and segment lengths. For validation purpose, 20 newly included healthy subjects performed a maximal isometric...

  6. Self-control, self-regulation, and doping in sport: a test of the strength-energy model.

    Science.gov (United States)

    Chan, Derwin K; Lentillon-Kaestner, Vanessa; Dimmock, James A; Donovan, Robert J; Keatley, David A; Hardcastle, Sarah J; Hagger, Martin S

    2015-04-01

    We applied the strength-energy model of self-control to understand the relationship between self-control and young athletes' behavioral responses to taking illegal performance-enhancing substances, or "doping." Measures of trait self-control, attitude and intention toward doping, intention toward, and adherence to, doping-avoidant behaviors, and the prevention of unintended doping behaviors were administered to 410 young Australian athletes. Participants also completed a "lollipop" decision-making protocol that simulated avoidance of unintended doping. Hierarchical linear multiple regression analyses revealed that self-control was negatively associated with doping attitude and intention, and positively associated with the intention and adherence to doping-avoidant behaviors, and refusal to take or eat the unfamiliar candy offered in the "lollipop" protocol. Consistent with the strength-energy model, athletes with low self-control were more likely to have heightened attitude and intention toward doping, and reduced intention, behavioral adherence, and awareness of doping avoidance.

  7. Strength and water-tightness of the closure head and valves of a model cask under high external pressure

    International Nuclear Information System (INIS)

    Terada, O.; Kumada, M.; Hayakawa, T.; Mochizuki, S.; Ohrui, K.

    1978-01-01

    This paper describes experimental research on the strength and water-tightness of the closure head and attached valves of a model cask under high external pressure, in simulation of its having been accidentally lost in the deep sea. Both the external pressure tests and the corrosion tests were carried out using scale models of the closure head of an 80-ton spent-fuel shipping cask, and the full size pressure relief valves and drain valves which were to be attached to the actual cask. Based on the results of the above tests, evaluations were made, and new information was obtained on the pressure-proof strength and water-tightness of the closure head of the cask and the valves. Lastly, research which is being carried on in Japan on the pressure equalizer is also introduced

  8. Analysis of the physical properties of trehalose-water-lithium iodide based on the bond strength coordination number fluctuation model

    International Nuclear Information System (INIS)

    Sahara; Jean L Ndeugueu; Masaru Aniya

    2010-01-01

    The temperature dependence of the viscosity of trehalose-water-lithium iodide system has been investigated by the mean of the Bond Strength Coordination Number Fluctuation (BSCNF) model. The result indicates that by increasing the trehalose content, maintaining the content of LiI constant, the fragility decreases due to the increase of the connectivity between the structural units. Our analysis suggests also that the fragility of the system is controlled by the amount of water in the composition. By increasing the water content, the total bond strength decreases and its fluctuation increases, resulting in the increase of the fragility. Based on the analysis of the obtained parameters of the BSCNF model, a physical interpretation of the VFT parameters reported in a previous study has been given. (author)

  9. Impact of the solution ionic strength on strontium diffusion through the Callovo-Oxfordian clayrocks: An experimental and modeling study

    International Nuclear Information System (INIS)

    Savoye, S.; Beaucaire, C.; Grenut, B.; Fayette, A.

    2015-01-01

    Highlights: • HTO and 85 Sr diffusion is studied in clayrocks under increasing ionic strengths. • Sr diffusive flux is 5 times higher than HTO under standard porewater ionic strength. • Sr diffusive flux is reduced when the porewater ionic strength increases. • The Sr diffusive evolution is qualitatively reproduced by a surface diffusion model. - Abstract: Diffusion of cations in clayrocks is widely investigated, because deep clay-rich formations are currently considered as one of the potential host rocks for radioactive waste repositories. However, several authors have already reported that sorbing cations seem to diffuse at rates larger than those predicted by a simple pore diffusion model from their sorption coefficients and from the diffusive flux of non-sorbing water tracers. This process has been attributed to the migration of cations within the electrical double layer, next to the mineral surfaces, called the surface diffusion phenomenon. The aim of this work was to verify whether this “enhanced” cation diffusion compared to neutral species was observed for strontium and, if so, to what extent this effect might vary with the salinity of the synthetic solutions. These questions were addressed by performing batch sorption, through-diffusion and out-diffusion experiments on rock samples from the Callovo-Oxfordian claystone formation (France). The results showed that there was a good agreement of the distribution ratios (R D ) determined on crushed and intact rocks by batch and through-diffusion methods with a R D decrease related to the increase of the sodium concentration, a sorption competitor. Such a trend was also well reproduced by means of a geochemical modeling based on the multi-site ion exchange (MSIE) theory. Moreover, the “enhanced” diffusion for strontium was clearly observed in this study: the Sr diffusive flux was almost five times higher than that for HTO in the cell with the lowest ionic strength, and diminished to less than 1

  10. Bonding Strength Effects in Hydro-Mechanical Coupling Transport in Granular Porous Media by Pore-Scale Modeling

    Directory of Open Access Journals (Sweden)

    Zhiqiang Chen

    2016-03-01

    Full Text Available The hydro-mechanical coupling transport process of sand production is numerically investigated with special attention paid to the bonding effect between sand grains. By coupling the lattice Boltzmann method (LBM and the discrete element method (DEM, we are able to capture particles movements and fluid flows simultaneously. In order to account for the bonding effects on sand production, a contact bond model is introduced into the LBM-DEM framework. Our simulations first examine the experimental observation of “initial sand production is evoked by localized failure” and then show that the bonding or cement plays an important role in sand production. Lower bonding strength will lead to more sand production than higher bonding strength. It is also found that the influence of flow rate on sand production depends on the bonding strength in cemented granular media, and for low bonding strength sample, the higher the flow rate is, the more severe the erosion found in localized failure zone becomes.

  11. Infliximab's influence on anastomotic strength and degree of inflammation in intestinal surgery in a rabbit model

    DEFF Research Database (Denmark)

    Frostberg, Erik; Ström, Petter; Gerke, Oke

    2014-01-01

    and conclusions. The purpose of this study was to investigate whether a single dose infliximab has an adverse effect on the anastomotic healing process, observed as reduced anastomotic breaking strength and histopathologically verified lower grade of inflammatory response, in the small intestine of a rabbit......BACKGROUND: Infliximab, a TNF-alpha inhibitor, is a potent anti-inflammatory drug in the treatment of inflammatory bowel diseases. Recent studies have investigated the effect of infliximab treatment on postoperative complications such as anastomotic leakage, however, with conflicting results...... of infliximab, given one week prior to surgery, does not have an impact on the anastomotic breaking strength on the third postoperative day in the small intestine of rabbits....

  12. Examining the model structure of the strengths and difficulties questionnaire (SDQ)

    OpenAIRE

    Azzopardi, Lara Marie; Camilleri, Liberato; Sammut, Fiona; Cefai, Carmel

    2016-01-01

    The Strengths and Difficulties questionnaire (SDQ), proposed by Goodman 1997, has been used by researchers to measure social, emotional and behaviour difficulties in children. The SDQ includes four difficulty subscales, measuring emotional, conduct, hyperactivity and peer problems. It also includes a fifth subscale, measuring prosocial behaviour. Dickey 2004 suggested that the SDQ factor structure can be reduced to three dimensions comprising the prosocial, externalisation and internalisation...

  13. A unified bond theory, probabilistic meso-scale modeling, and experimental validation of deformed steel rebar in normal strength concrete

    Science.gov (United States)

    Wu, Chenglin

    Bond between deformed rebar and concrete is affected by rebar deformation pattern, concrete properties, concrete confinement, and rebar-concrete interfacial properties. Two distinct groups of bond models were traditionally developed based on the dominant effects of concrete splitting and near-interface shear-off failures. Their accuracy highly depended upon the test data sets selected in analysis and calibration. In this study, a unified bond model is proposed and developed based on an analogy to the indentation problem around the rib front of deformed rebar. This mechanics-based model can take into account the combined effect of concrete splitting and interface shear-off failures, resulting in average bond strengths for all practical scenarios. To understand the fracture process associated with bond failure, a probabilistic meso-scale model of concrete is proposed and its sensitivity to interface and confinement strengths are investigated. Both the mechanical and finite element models are validated with the available test data sets and are superior to existing models in prediction of average bond strength (rib spacing-to-height ratio of deformed rebar. It can accurately predict the transition of failure modes from concrete splitting to rebar pullout and predict the effect of rebar surface characteristics as the rib spacing-to-height ratio increases. Based on the unified theory, a global bond model is proposed and developed by introducing bond-slip laws, and validated with testing of concrete beams with spliced reinforcement, achieving a load capacity prediction error of less than 26%. The optimal rebar parameters and concrete cover in structural designs can be derived from this study.

  14. [Pain in humans: experimental facts and hypotheses].

    Science.gov (United States)

    Cesaro, P

    1994-09-15

    The description of painful phenomena in humans has to take into account its different components: sensory component (relevant to nociception), affective and emotional components. Nociceptor's (physiology is best understood with electrophysiological and neurochemical methods allowing a clear description of hyperalgesia, with its peripheral and spinal mechanisms. A functional model is partly available to explain allodynia, spontaneous burning pain and lightning pain, the three main consequences following deafferentation. At the thalamo-cortical level, one can describe nociceptive pathways and other pathways or neuronal networks involved in the affective and emotional components of pain.

  15. Examination and modeling of void growth kinetics in modern high strength dual phase steels during uniaxial tensile deformation

    Energy Technology Data Exchange (ETDEWEB)

    Saeidi, N., E-mail: navidsae@gmail.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ashrafizadeh, F.; Niroumand, B. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Forouzan, M.R.; Mohseni mofidi, S. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Barlat, F. [Materials Mechanics Laboratory (MML), Graduate Institute of Ferrous Technology (GIFT), Pohang University of Science and Technology - POSTECH, San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

    2016-04-01

    Ductile fracture mechanisms during uniaxial tensile testing of two different modern high strength dual phase steels, i.e. DP780 and DP980, were studied. Detailed microstructural characterization of the strained and sectioned samples was performed by scanning electron microscopy as well as EBSD examination. The results revealed that interface decohesion, especially at martensite particles located at ferrite grain boundaries, was the most probable mechanism for void nucleation. It was also revealed that the creation of cellular substructure can reduce stored strain energy and thereby, higher true fracture strain was obtained in DP980 than DP780 steel. Prediction of void growth behavior based on some previously proposed models showed unreliable results. Therefore, a modified model based on Rice-Tracey family models was proposed which showed a very lower prediction error compared with other models. - Highlights: • Damage mechanism in two modern high strength dual phase steels was studied. • Creation of cellular substructures can reduce the stored strain energy within the ferrite grains. • The experimental values were examined by Agrawal as well as RT family models. • A modified model was proposed for prediction of void growth behavior of DP steels.

  16. Test of E1-radiative strength function and level density models by 155 Gd (n,2γ) 156 Gd reaction

    International Nuclear Information System (INIS)

    Voinov, A.V.

    1996-01-01

    The information about the level density of 156 Gd nucleus and strength functions of γ transitions extracted from two γ-cascade spectra of the 155 Gd (n,2γ) 156 Gd reaction is analyzed. The method of statistical simulation of γ-cascade intensity is applied for calculation of the main parameters of experimental spectra. The method is used to extract the information on the E1-radiative strength function of γ transitions and level density in the 156 Gd nucleus. It is shown that at an excitation energy above 3 MeV the level density of 156 Gd nucleus must decrease in comparison with that calculated within the Fermi gas model. Its is concluded that possible explanation of the observed effect is connected with the influence of pairing correlations on the level density in nuclei

  17. Parameter estimation and testing of hypotheses

    International Nuclear Information System (INIS)

    Fruhwirth, R.

    1996-01-01

    This lecture presents the basic mathematical ideas underlying the concept of random variable and the construction and analysis of estimators and test statistics. The material presented is based mainly on four books given in the references: the general exposition of estimators and test statistics follows Kendall and Stuart which is a comprehensive review of the field; the book by Eadie et al. contains selecting topics of particular interest to experimental physicist and a host of illuminating examples from experimental high-energy physics; for the presentation of numerical procedures, the Press et al. and the Thisted books have been used. The last section deals with estimation in dynamic systems. In most books the Kalman filter is presented in a Bayesian framework, often obscured by cumbrous notation. In this lecture, the link to classical least-squares estimators and regression models is stressed with the aim of facilitating the access to this less familiar topic. References are given for specific applications to track and vertex fitting and for extended exposition of these topics. In the appendix, the link between Bayesian decision rules and feed-forward neural networks is presented. (J.S.). 10 refs., 5 figs., 1 appendix

  18. Nonlinear modeling, strength-based design, and testing of flexible piezoelectric energy harvesters under large dynamic loads for rotorcraft applications

    Science.gov (United States)

    Leadenham, Stephen; Erturk, Alper

    2014-04-01

    There has been growing interest in enabling wireless health and usage monitoring for rotorcraft applications, such as helicopter rotor systems. Large dynamic loads and acceleration fluctuations available in these environments make the implementation of vibration-based piezoelectric energy harvesters a very promising choice. However, such extreme loads transmitted to the harvester can also be detrimental to piezoelectric laminates and overall system reliability. Particularly flexible resonant cantilever configurations tuned to match the dominant excitation frequency can be subject to very large deformations and failure of brittle piezoelectric laminates due to excessive bending stresses at the root of the harvester. Design of resonant piezoelectric energy harvesters for use in these environments require nonlinear electroelastic dynamic modeling and strength-based analysis to maximize the power output while ensuring that the harvester is still functional. This paper presents a mathematical framework to design and analyze the dynamics of nonlinear flexible piezoelectric energy harvesters under large base acceleration levels. A strength-based limit is imposed to design the piezoelectric energy harvester with a proof mass while accounting for material, geometric, and dissipative nonlinearities, with a focus on two demonstrative case studies having the same linear fundamental resonance frequency but different overhang length and proof mass values. Experiments are conducted at different excitation levels for validation of the nonlinear design approach proposed in this work. The case studies in this work reveal that harvesters exhibiting similar behavior and power generation performance at low excitation levels (e.g. less than 0.1g) can have totally different strength-imposed performance limitations under high excitations (e.g. above 1g). Nonlinear modeling and strength-based design is necessary for such excitation levels especially when using resonant cantilevers with no

  19. Evaluation of bond strength of silorane and methacrylate based restorative systems to dentin using different cavity models

    Directory of Open Access Journals (Sweden)

    Stephano Zerlottini Isaac

    2013-09-01

    Full Text Available OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS to dentin of two different restorative systems: silorane-based (P90, and methacrylate-based (P60, using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5 were prepared in 20 teeth, which were divided into two groups (n=10 restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2 and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10. The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. RESULTS: For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p0.05, or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05. Regarding fracture pattern, there was no statistical difference among groups (p=0.0713 and 56.3% of the fractures were adhesive. CONCLUSION: It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor.

  20. An ongoing investigation on modeling the strength properties of water-entrained cement-based materials

    DEFF Research Database (Denmark)

    Esteves, L.P.

    2012-01-01

    Water-entrained cement based materials by superabsorbent polymers is a concept that was introduced in the research agenda about a decade ago. However, a recent application in the production of high performance concrete revealed potential weaknesses when the proportioning of this intelligent......-based materials. Beyond the discussion of whether or not the introduction of superabsorbent polymers leads to a strength reduction, this paper uses both experimental and theoretical background to separate the effect of SAP in both pore structure and internal relative humidity and the effect from the active...

  1. Nonlinear Fatigue Damage Model Based on the Residual Strength Degradation Law

    Science.gov (United States)

    Yongyi, Gao; Zhixiao, Su

    In this paper, a logarithmic expression to describe the residual strength degradation process is developed in order to fatigue test results for normalized carbon steel. The definition and expression of fatigue damage due to symmetrical stress with a constant amplitude are also given. The expression of fatigue damage can also explain the nonlinear properties of fatigue damage. Furthermore, the fatigue damage of structures under random stress is analyzed, and an iterative formula to describe the fatigue damage process is deduced. Finally, an approximate method for evaluating the fatigue life of structures under repeated random stress blocking is presented through various calculation examples.

  2. Fireballs Masses and Densities: Hypotheses and Reality

    Science.gov (United States)

    Gritsevich, Maria

    Techniques of determining the masses of meteor bodies have long been discussed in the literature dedicated to meteor studies. Unfortunately the development of methods for evaluating meteors and fireballs parameters from observational data requires much attention since the available literature, including handbooks (e.g., C. W. Allen, Astrophysical Quantities, Athlone, London, 1973), contains discrepancies that are of a basic character rather than due to experimental uncertainties. A comprehensive survey and analysis deserve a separate publication. Thus, we will cite here some literary sources. The mass of a fireball is conventionally determined using a photometric formula, by integrating the brightness along the entire luminous segment of the trajectory. The mass can also be estimated using the altitude and rate of fireball deceleration in the atmosphere. The discrepancy of the estimates obtained using these two techniques is usually diminished by selecting "appropriate" values of the fireball density. However, this leads to obviously underestimated values of 0.25 g/cm3 for this density. In order to eliminate these discrepancies, it was proposed to consider a swarm of similar-size fragments instead of a single meteoroid. In this case, it is the photometric-to-dynamic mass ratio that determines the number of such fragments. In the present report, the mass is calculated using the data of actual observations, by selecting the parameters describing deceleration and ablation of fireballs along the luminous segment of the trajectory. New model is based on the best fitting of the observational data by an analytical solution of the equations of meteor physics. In doing so, the author tried to take into account all of the peculiarities of the events noted in the literature, as well as the newest results of numerical experiments on the 3D aerodynamics of bodies of complicated shapes. The proximity of results obtained using different dynamic methods implies that observational

  3. On the calibration strategies of the Johnson–Cook strength model: Discussion and applications to experimental data

    International Nuclear Information System (INIS)

    Gambirasio, Luca; Rizzi, Egidio

    2014-01-01

    The present paper aims at assessing the various procedures adoptable for calibrating the parameters of the so-called Johnson–Cook strength model, expressing the deviatoric behavior of elastoplastic materials, with particular reference to the description of High Strain Rate (HSR) phenomena. The procedures rely on input experimental data corresponding to a set of hardening functions recorded at different equivalent plastic strain rates and temperatures. After a brief review of the main characteristics of the Johnson–Cook strength model, five different calibration strategies are framed and widely described. The assessment is implemented through a systematic application of each calibration strategy to three different real material cases, i.e. a DH-36 structural steel, a commercially pure niobium and an AL-6XN stainless steel. Experimental data available in the literature are considered. Results are presented in terms of plots showing the predicted Johnson–Cook hardening functions against the experimental trends, together with tables describing the fitting problematics which arise in each case, by assessing both lower yield stress and overall plastic flow introduced errors. The consequences determined by each calibration approach are then carefully compared and evaluated. A discussion on the positive and negative aspects of each strategy is presented and some suggestions on how to choose the best calibration approach are outlined, by considering the available experimental data and the objectives of the following modeling process. The proposed considerations should provide a useful guideline in the process of determining the best Johnson–Cook parameters in each specific situation in which the model is going to be adopted. A last section introduces some considerations about the calibration of the Johnson–Cook strength model through experimental data different from those consisting in a set of hardening functions relative to different equivalent plastic strain

  4. Study protocol for a controlled trial of Strengths Model Case Management in mental health services in Hong Kong.

    Science.gov (United States)

    Tsoi, Wing-See Emily; Tse, Samson; Fukui, Sadaaki; Jones, Steven

    2015-10-06

    Although strengths-based models are popular within recovery-oriented approaches, there is still a lack of conclusive research to guide how they should be implemented. A recent meta-analysis confirmed the lack of clarity in how this perspective is operationalised and that fidelity monitoring during the implementation process is lacking. Hence, there is a clear need to evaluate the feasibility of delivering and evaluating a clearly operationalised strengths-based intervention that incorporates fidelity checks to inform more definitive research. This protocol therefore describes a controlled trial of Strengths Model Case Management (SMCM), a complex intervention, for people with severe mental illnesses in Hong Kong. This trial follows the guidelines of the Medical Research Council as a phase 2 trial. Hence, it is a pilot study that tests the feasibility and effectiveness of the model. This is a 9-month controlled trial that uses the Kansas Model. Participants and a matched control group are recruited on a voluntary basis, after screening for eligibility. Effectiveness of the SMCM will be measured through outcome measures taken at baseline, the mid-point and at the end of the trial. Outcomes for service users include personal recovery, hope, subjective well-being, psychiatric symptoms, perceived level of recovery features within the organisation, therapeutic alliance and achievement of recovery goals. Outcomes for care workers will include job burnout, organisational features of recovery and perceived supervisory support. With a 2×3 analysis of variance design and a moderate intervention effect (Cohen's d=0.50), a total of 86 participants will be needed for a statistical power of 0.80. Ethical approval has been obtained from the Human Research Ethics Committee for Non-Clinical Faculties at The University of Hong Kong (HRECNCF: EA140913). Australian New Zealand Clinical Trial Registry (ACTRN)12613001120763. Published by the BMJ Publishing Group Limited. For permission

  5. Single nuclear transfer strengths and sum rules in the interacting boson-fermion model and in the spectral averaging theory

    International Nuclear Information System (INIS)

    Kota, V.K.B.

    1991-01-01

    In the interacting boson-fermion model of collective nuclei, in the symmetry limits of the model appropriate for vibrational, rotational and γ-unstable nuclei, for one-particle transfer, the selection rules, model predictions for the allowed strengths and comparison of theory with experiment are briefly reviewed. In the spectral-averaging theory, with the specific example of orbit occupancies, the smoothed forms (linear or better ratio of Gaussians) as determined by central limit theorems, how they provide a good criterion for selecting effective interactions and the convolution structure of occupancy densities in huge spaces are described. Complementary information provided by nuclear models and statistical laws is broughtout. (author). 63 refs., 5 figs

  6. A Connection Model between the Positioning Mechanism and Ultrasonic Measurement System via a Web Browser to Assess Acoustic Target Strength

    Science.gov (United States)

    Ishii, Ken; Imaizumi, Tomohito; Abe, Koki; Takao, Yoshimi; Tamura, Shuko

    This paper details a network-controlled measurement system for use in fisheries engineering. The target strength (TS) of fish is important in order to convert acoustic integration values obtained during acoustic surveys into estimates of fish abundance. The target strength pattern is measured with the combination of the rotation system for the aspect of the sample and the echo data acquisition system using the underwater supersonic wave. The user interface of the network architecture is designed for collaborative use with researchers in other organizations. The flexible network architecture is based on the web direct-access model for the rotation mechanism. The user interface is available for monitoring and controlling via a web browser that is installed in any terminal PC (personal computer). Previously the combination of two applications was performed not by a web browser but by the exclusive interface program. So a connection model is proposed between two applications by indirect communication via the DCOM (Distributed Component Object Model) server and added in the web direct-access model. A prompt report system in the TS measurement system and a positioning and measurement system using an electric flatcar via a web browser are developed. By a secure network architecture, DCOM communications via both Intranet and LAN are successfully certificated.

  7. An Exploratory Analysis of Economic Factors in the Navy Total Force Strength Model (NTFSM)

    Science.gov (United States)

    2015-12-01

    the model incorporates (in the personnel calculations) econometric effects to Losses by Expiration of Active Obligated Service, Attrition, and Length...Incorporate econometric effects of losses by LOS and paygrade using parameters generated by the Navy Econometric Modeling System (NEMS) to the greatest...community- level models . (CAP9) • Model architecture will support hosting of model , scenarios, (inputs, user comments, etc.) and outputs in a secure

  8. BEM-DDM modelling of rock damage and its implications on rock laboratory strength and in-situ stresses

    International Nuclear Information System (INIS)

    Matsui, Hiroya

    2008-03-01

    Within the framework of JAEA's Research and Development on deep geological environments for assessing the safety and reliability of the disposal technology for nuclear waste, this study was conducted to determine the effects of sample damage on the strength obtained from laboratory results (uniaxial compression and Brazilian test). Results of testing on samples of Toki granite taken at Shobasama and at the construction site for the Mizunami Underground Research Laboratory (MIU) at Mizunami, Gifu Pref., Japan, were analysed. Some spatial variation of the results along the boreholes suggested the presence of a correlation between the laboratory strength and the in-situ stresses measured by means of the hydro-fracturing method. To confirm this, numerical analyses of the drilling process in brittle rock by means of a BEM-DDM program (FRACOD 2D ) were carried out to study the induced fracture patterns. These fracture patterns were compared with similar results reported by other published studies and were found to be realistic. The correlation between strength and in-situ stresses could then be exploited to estimate the stresses and the location of core discing observed in boreholes where stress measurements were not available. A correction of the laboratory strength results was also proposed to take into account sample damage during drilling. Modelling of Brazilian tests shows that the calculated fracture patterns determine the strength of the models. This is different from the common assumption that failure occurs when the uniform tensile stress in the sample reaches the tensile strength of the rock material. Based on the modelling results, new Brazilian tests were carried out on samples from borehole MIZ-1 that confirmed the failure mechanism numerically observed. A numerical study of the fracture patterns induced by removal of the overburden on a large scale produces fracture patterns and stress distributions corresponding to observations in crystalline hard rock in

  9. Application of MMC model on simulation of shearing process of thick hot-rolled high strength steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Shuhui [Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Bing; Gao, Yongsheng [Automotive Steel Research Institute, R and D Center, BaoShan Iron and Steel Co.,Ltd, Shanghai 201900 (China)

    2013-12-16

    Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterion (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully.

  10. Multi-Scale Modeling for Predicting the Stiffness and Strength of Hollow-Structured Metal Foams with Structural Hierarchy

    Directory of Open Access Journals (Sweden)

    Yong Yi

    2018-03-01

    Full Text Available This work was inspired by previous experiments which managed to establish an optimal template-dealloying route to prepare ultralow density metal foams. In this study, we propose a new analytical–numerical model of hollow-structured metal foams with structural hierarchy to predict its stiffness and strength. The two-level model comprises a main backbone and a secondary nanoporous structure. The main backbone is composed of hollow sphere-packing architecture, while the secondary one is constructed of a bicontinuous nanoporous network proposed to describe the nanoscale interactions in the shell. Firstly, two nanoporous models with different geometries are generated by Voronoi tessellation, then the scaling laws of the mechanical properties are determined as a function of relative density by finite volume simulation. Furthermore, the scaling laws are applied to identify the uniaxial compression behavior of metal foams. It is shown that the thickness and relative density highly influence the Young’s modulus and yield strength, and vacancy defect determines the foams being self-supported. The present study provides not only new insights into the mechanical behaviors of both nanoporous metals and metal foams, but also a practical guide for their fabrication and application.

  11. Application of MMC model on simulation of shearing process of thick hot-rolled high strength steel plate

    International Nuclear Information System (INIS)

    Dong, Liang; Li, Shuhui; Yang, Bing; Gao, Yongsheng

    2013-01-01

    Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterion (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully

  12. From themes to hypotheses: following up with quantitative methods.

    Science.gov (United States)

    Morgan, David L

    2015-06-01

    One important category of mixed-methods research designs consists of quantitative studies that follow up on qualitative research. In this case, the themes that serve as the results from the qualitative methods generate hypotheses for testing through the quantitative methods. That process requires operationalization to translate the concepts from the qualitative themes into quantitative variables. This article illustrates these procedures with examples that range from simple operationalization to the evaluation of complex models. It concludes with an argument for not only following up qualitative work with quantitative studies but also the reverse, and doing so by going beyond integrating methods within single projects to include broader mutual attention from qualitative and quantitative researchers who work in the same field. © The Author(s) 2015.

  13. Recruitment processes in Baltic sprat - A re-evaluation of GLOBEC Germany hypotheses

    Science.gov (United States)

    Voss, Rüdiger; Peck, Myron A.; Hinrichsen, Hans-Harald; Clemmesen, Catriona; Baumann, Hannes; Stepputtis, Daniel; Bernreuther, Matthias; Schmidt, Jörn O.; Temming, Axel; Köster, Fritz W.

    2012-12-01

    The GLOBEC Germany program (2002-2007) had the ambitious goal to resolve the processes impacting the recruitment dynamics of Baltic sprat (Sprattus sprattus L.) by examining various factors affecting early life history stages. At the start of the research program, a number of general recruitment hypotheses were formulated, i.e. focusing on (1) predation, (2) food availability, (3) physical parameters, (4) the impact of current systems, and finally (5) the importance of top-down vs bottom-up effects. The present study synthesizes the results of field sampling (2002 and 2003), laboratory experiments, and modeling studies to re-evaluate these hypotheses for the Baltic sprat stock. Recruitment success was quite different in the 2 years investigated. Despite a lower spawning stock biomass in 2003, the total number of recruits was almost 2-fold higher that year compared to 2002. The higher recruitment success in 2003 could be attributed to enhanced survival success during the post-larval/juvenile stage, a life phase that appears to be critical for recruitment dynamics. In the state of the Baltic ecosystem during the period of investigation, we consider bottom-up control (e.g. temperature, prey abundance) to be more important than top-down control (predation mortality). This ranking in importance does not vary seasonally. Prevailing water circulation patterns and the transport dynamics of larval cohorts have a strong influence on sprat recruitment success. Pronounced transport to coastal areas is detrimental for year-class strength particularly at high sprat stock sizes. A suggested mechanism is density-dependant regulation of survival via intra- and inter-specific competition for prey in coastal areas. A documented change in larval vertical migration behavior between the early 1990s and early 2000s increased the transport potential to the coast, strengthening the coupling between inter-annual differences in the magnitude and direction of wind-driven surface currents and

  14. The Kenya rift revisited: insights into lithospheric strength through data-driven 3-D gravity and thermal modelling

    Science.gov (United States)

    Sippel, Judith; Meeßen, Christian; Cacace, Mauro; Mechie, James; Fishwick, Stewart; Heine, Christian; Scheck-Wenderoth, Magdalena; Strecker, Manfred R.

    2017-01-01

    We present three-dimensional (3-D) models that describe the present-day thermal and rheological state of the lithosphere of the greater Kenya rift region aiming at a better understanding of the rift evolution, with a particular focus on plume-lithosphere interactions. The key methodology applied is the 3-D integration of diverse geological and geophysical observations using gravity modelling. Accordingly, the resulting lithospheric-scale 3-D density model is consistent with (i) reviewed descriptions of lithological variations in the sedimentary and volcanic cover, (ii) known trends in crust and mantle seismic velocities as revealed by seismic and seismological data and (iii) the observed gravity field. This data-based model is the first to image a 3-D density configuration of the crystalline crust for the entire region of Kenya and northern Tanzania. An upper and a basal crustal layer are differentiated, each composed of several domains of different average densities. We interpret these domains to trace back to the Precambrian terrane amalgamation associated with the East African Orogeny and to magmatic processes during Mesozoic and Cenozoic rifting phases. In combination with seismic velocities, the densities of these crustal domains indicate compositional differences. The derived lithological trends have been used to parameterise steady-state thermal and rheological models. These models indicate that crustal and mantle temperatures decrease from the Kenya rift in the west to eastern Kenya, while the integrated strength of the lithosphere increases. Thereby, the detailed strength configuration appears strongly controlled by the complex inherited crustal structure, which may have been decisive for the onset, localisation and propagation of rifting.

  15. Increased consumer density reduces the strength of neighborhood effects in a model system.

    Science.gov (United States)

    Merwin, Andrew C; Underwood, Nora; Inouye, Brian D

    2017-11-01

    An individual's susceptibility to attack can be influenced by conspecific and heterospecifics neighbors. Predicting how these neighborhood effects contribute to population-level processes such as competition and evolution requires an understanding of how the strength of neighborhood effects is modified by changes in the abundances of both consumers and neighboring resource species. We show for the first time that consumer density can interact with the density and frequency of neighboring organisms to determine the magnitude of neighborhood effects. We used the bean beetle, Callosobruchus maculatus, and two of its host beans, Vigna unguiculata and V. radiata, to perform a response-surface experiment with a range of resource densities and three consumer densities. At low beetle density, damage to beans was reduced with increasing conspecific density (i.e., resource dilution) and damage to the less preferred host, V. unguiculata, was reduced with increasing V. radiata frequency (i.e., frequency-dependent associational resistance). As beetle density increased, however, neighborhood effects were reduced; at the highest beetle densities neither focal nor neighboring resource density nor frequency influenced damage. These findings illustrate the importance of consumer density in mediating indirect effects among resources, and suggest that accounting for consumer density may improve our ability to predict population-level outcomes of neighborhood effects and our use of them in applications such as mixed-crop pest management. © 2017 by the Ecological Society of America.

  16. The Schoolwide Enrichment Model: A Focus on Student Strengths and Interests

    Science.gov (United States)

    Renzulli, Joseph S.; Renzulli, Sally Reis

    2010-01-01

    This article includes an introduction to the Schoolwide Enrichment Model (SEM), with its three components: a total talent portfolio for each child, curriculum differentiation and modification, and enrichment opportunities from the Enrichment Triad Model. Also included is a brief history of the SEM and a summary of 30 years of research underlying…

  17. A meso-scale model to study the compressive strength of woven carbon fiber reinforced plastics

    NARCIS (Netherlands)

    Schormans, J.M.J.; Remmers, J.J.C.; Wilson, W.; Deshpande, V.S.

    2016-01-01

    Modeling kink-band formation in woven composites using a detailed micro-model is numerically expensive. In order to reduce the computational resources, a method to homogenize fiber-tows is proposed which uses a rules of mixture approach. The method is tested by comparing the stiffness and

  18. Analysis of isometric cervical strength with a nonlinear musculoskeletal model with 48 degrees of freedom

    NARCIS (Netherlands)

    De Bruijn, E.; Van der Helm, F.C.T.; Happee, R.

    2015-01-01

    Background: Musculoskeletal models served to analyze head–neck motion and injury during automotive impact. Although muscle activation is known to affect the kinematic response, a model with properly validated muscle contributions does not exist to date. The goal of this study was to enhance a

  19. Using the ADDIE Model to Create an Online Strength Training Program: An Exploration

    Science.gov (United States)

    Brook, Rebekah L.

    2014-01-01

    The purpose of this design and development research was to investigate whether the ADDIE model can be used to design online modules that teach psychomotor skills. The overarching research question was: How can the ADDIE Model of Instructional Design be used to create an online module that teaches safe and effective movement for psychomotor skills?…

  20. Predictive hypotheses are ineffectual in resolving complex biochemical systems.

    Science.gov (United States)

    Fry, Michael

    2018-03-20

    Scientific hypotheses may either predict particular unknown facts or accommodate previously-known data. Although affirmed predictions are intuitively more rewarding than accommodations of established facts, opinions divide whether predictive hypotheses are also epistemically superior to accommodation hypotheses. This paper examines the contribution of predictive hypotheses to discoveries of several bio-molecular systems. Having all the necessary elements of the system known beforehand, an abstract predictive hypothesis of semiconservative mode of DNA replication was successfully affirmed. However, in defining the genetic code whose biochemical basis was unclear, hypotheses were only partially effective and supplementary experimentation was required for its conclusive definition. Markedly, hypotheses were entirely inept in predicting workings of complex systems that included unknown elements. Thus, hypotheses did not predict the existence and function of mRNA, the multiple unidentified components of the protein biosynthesis machinery, or the manifold unknown constituents of the ubiquitin-proteasome system of protein breakdown. Consequently, because of their inability to envision unknown entities, predictive hypotheses did not contribute to the elucidation of cation theories remained the sole instrument to explain complex bio-molecular systems, the philosophical question of alleged advantage of predictive over accommodative hypotheses became inconsequential.

  1. Mechanical strength model for plastic bonded granular materials at high strain rates and large strains

    International Nuclear Information System (INIS)

    Browning, R.V.; Scammon, R.J.

    1998-01-01

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-9501. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate that the observed characteristic behavior is captured by this viscoelastic based model. copyright 1998 American Institute of Physics

  2. Grain fracture model and its application to strength evaluation in engineering ceramics

    Science.gov (United States)

    Hoshide, Toshihiko

    1993-02-01

    A new model of cracking process in ceramics is developed assuming the fracture of the grain just ahead of a flaw, such as a crack or a notch, during the loading process, prior to the final unstable fracture. Based on the grain fracture model, a simulation was carried out to explain the anomalous behavior of small flaws and the notch width effect, which were reported by Evans and Langdon (1976) and Hoshide et al. (1984) and by Bertolotti (1973) and Pabst et al. (1982), respectively. It is shown that the analytical relations of the new model can explain the experimental results for both situations.

  3. A proposal of parameter determination method in the residual strength degradation model for the prediction of fatigue life (I)

    International Nuclear Information System (INIS)

    Kim, Sang Tae; Jang, Seong Soo

    2001-01-01

    The static and fatigue tests have been carried out to verify the validity of a generalized residual strength degradation model. And a new method of parameter determination in the model is verified experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron. It is shown that the correlation between the experimental results and the theoretical prediction on the statistical distribution of fatigue life by using the proposed method is very reasonable. Furthermore, it is found that the correlation between the theoretical prediction and the experimental results of fatigue life in case of tension-tension fatigue data in composite material appears to be reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than maximum likelihood method and minimization technique

  4. A compressibility based model for predicting the tensile strength of directly compressed pharmaceutical powder mixtures.

    Science.gov (United States)

    Reynolds, Gavin K; Campbell, Jacqueline I; Roberts, Ron J

    2017-10-05

    A new model to predict the compressibility and compactability of mixtures of pharmaceutical powders has been developed. The key aspect of the model is consideration of the volumetric occupancy of each powder under an applied compaction pressure and the respective contribution it then makes to the mixture properties. The compressibility and compactability of three pharmaceutical powders: microcrystalline cellulose, mannitol and anhydrous dicalcium phosphate have been characterised. Binary and ternary mixtures of these excipients have been tested and used to demonstrate the predictive capability of the model. Furthermore, the model is shown to be uniquely able to capture a broad range of mixture behaviours, including neutral, negative and positive deviations, illustrating its utility for formulation design. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Accounting for uncertainty in ecological analysis: the strengths and limitations of hierarchical statistical modeling.

    Science.gov (United States)

    Cressie, Noel; Calder, Catherine A; Clark, James S; Ver Hoef, Jay M; Wikle, Christopher K

    2009-04-01

    Analyses of ecological data should account for the uncertainty in the process(es) that generated the data. However, accounting for these uncertainties is a difficult task, since ecology is known for its complexity. Measurement and/or process errors are often the only sources of uncertainty modeled when addressing complex ecological problems, yet analyses should also account for uncertainty in sampling design, in model specification, in parameters governing the specified model, and in initial and boundary conditions. Only then can we be confident in the scientific inferences and forecasts made from an analysis. Probability and statistics provide a framework that accounts for multiple sources of uncertainty. Given the complexities of ecological studies, the hierarchical statistical model is an invaluable tool. This approach is not new in ecology, and there are many examples (both Bayesian and non-Bayesian) in the literature illustrating the benefits of this approach. In this article, we provide a baseline for concepts, notation, and methods, from which discussion on hierarchical statistical modeling in ecology can proceed. We have also planted some seeds for discussion and tried to show where the practical difficulties lie. Our thesis is that hierarchical statistical modeling is a powerful way of approaching ecological analysis in the presence of inevitable but quantifiable uncertainties, even if practical issues sometimes require pragmatic compromises.

  6. Modeling of quantitative relationships between physicochemical properties of active pharmaceutical ingredients and tensile strength of tablets using a boosted tree.

    Science.gov (United States)

    Hayashi, Yoshihiro; Oishi, Takuya; Shirotori, Kaede; Marumo, Yuki; Kosugi, Atsushi; Kumada, Shungo; Hirai, Daijiro; Takayama, Kozo; Onuki, Yoshinori

    2018-07-01

    The aim of this study was to explore the potential of boosted tree (BT) to develop a correlation model between active pharmaceutical ingredient (API) characteristics and a tensile strength (TS) of tablets as critical quality attributes. First, we evaluated 81 kinds of API characteristics, such as particle size distribution, bulk density, tapped density, Hausner ratio, moisture content, elastic recovery, molecular weight, and partition coefficient. Next, we prepared tablets containing 50% API, 49% microcrystalline cellulose, and 1% magnesium stearate using direct compression at 6, 8, and 10 kN, and measured TS. Then, we applied BT to our dataset to develop a correlation model. Finally, the constructed BT model was validated using k-fold cross-validation. Results showed that the BT model achieved high-performance statistics, whereas multiple regression analysis resulted in poor estimations. Sensitivity analysis of the BT model revealed that diameter of powder particles at the 10th percentile of the cumulative percentage size distribution was the most crucial factor for TS. In addition, the influences of moisture content, partition coefficients, and modal diameter were appreciably meaningful factors. This study demonstrates that BT model could provide comprehensive understanding of the latent structure underlying APIs and TS of tablets.

  7. A state-of-the-art anisotropic rock deformation model incorporating the development of mobilised shear strength

    Science.gov (United States)

    Noor, M. J. Md; Jobli, A. F.

    2018-04-01

    Currently rock deformation is estimated using the relationship between the deformation modulus Em and the stress-strain curve. There have been many studies conducted to estimate the value of Em. This Em is basically derived from conducting unconfined compression test, UCS. However, the actual stress condition of the rock in the ground is anisotropic stress condition where the rock mass is subjected to different confining and vertical pressures. In addition, there is still no empirical or semi-empirical framework that has been developed for the prediction of rock stress-strain response under anisotropic stress condition. Arock triaxial machine GCTS Triaxial RTX-3000 has been deployed to obtain the anisotropic stress-strain relationship for weathered granite grade II from Rawang, Selangor sampled at depth of 20 m and subjected to confining pressure of 2 MPa, 7.5 MPa and 14 MPa. The developed mobilised shear strength envelope within the specimen of 50 mm diameter and 100 mm height during the application of the deviator stress is interpreted from the stress-strain curves. These mobilised shear strength envelopes at various axial strains are the intrinsic property and unique for the rock. Once this property has been established then it is being used to predict the stress-strain relationship at any confining pressure. The predicted stress-strain curves are compared against the curves obtained from the tests. A very close prediction is achieved to substantiate the applicability of this rock deformation model. This is a state-of-the art rock deformation theory which characterise the deformation base on the applied load and the developed mobilised shear strength within the rock body.

  8. Modelling of ultrasonic impact treatment (UIT of welded joints and its effect on fatigue strength

    Directory of Open Access Journals (Sweden)

    K.L. Yuan

    2015-10-01

    Full Text Available Ultrasonic impact treatment (UIT is a remarkable post-weld technique applying mechanical impacts in combination with ultrasound into the welded joints. In the present work, a 3D simulation method including welding simulation, numerical modelling of UIT-process and an evaluation of fatigue crack growth has been developed. In the FE model, the actual treatment conditions and local mechanical characteristics due to acoustic softening are set as input parameters. The plastic deformation and compressive stress layer are found to be more pronounced when acoustic softening takes place. The predicted internal residual stress distributions of welded joint before and after UIT are compared with experimental results, showing a fairly good agreement with each other. Finally, simulated results of fatigue crack growth in various residual stress fields are well compared with test results, so that the proposed model may provide an effective tool to simulate UIT-process in engineering structures.

  9. Testing competing hypotheses about single trial fMRI

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Purushotham, Archana; Kim, Seong-Ge

    2002-01-01

    We use a Bayesian framework to compute probabilities of competing hypotheses about functional activation based on single trial fMRI measurements. Within the framework we obtain a complete probabilistic picture of competing hypotheses, hence control of both type I and type II errors....

  10. Applying Strengths Model principles to build a rural community-based mental health support service and achieve recovery outcomes.

    Science.gov (United States)

    Dunstan, Debra; Anderson, Donnah

    2018-02-01

    The Personal Helpers and Mentors (PHaMs) service is a non-clinical, community-based Australian Government initiative aimed at increasing opportunities for recovery for people whose lives are severely affected by mental illness. Using a strengths-based recovery model, PHaMs caseworkers support and mentor people 'at risk of falling through the gaps' between state funded clinical treatment services and federally funded social services (such as supported housing, education and employment). While there is evidence that PHaMs realises its aim in metropolitan areas, little is known about how services are developed and function in low resource rural settings and what outcomes are achieved. These questions were addressed in a case study of a PHaMs service in a rural town in the state of New South Wales, Australia. Data were collected from two sources: local service documents prepared for staff orientation and operational purposes, and records and reports of service participants\\' performance and achievements. Participants\\' gains in wellbeing, recovery goals, and the target outcome areas of increased access to services, increased personal capacity and self-reliance, and increased community participation, were gathered from self-reports. The Role Functioning Scale was used as a measure of caseworker ratings of participants\\' adaptive functioning. The qualitative data were examined for semantic content and underlying themes. The quantitative analyses involved repeated measures and between-groups comparisons of uncontrolled pre-test–post-test and retrospective pre-test data. From commencement of the service in October 2009 to June 2014, an estimated 31% of the people living with severe mental illness in the local government area had accessed the PHaMs service (N=126; mean age 31.9 years; 42% male, 27% Aboriginal). The document analysis revealed that despite a lack of detail on how a PHaMs service should be developed or delivered, by focusing on the goal of client recovery

  11. A Test of the Need Hierarchy Concept by a Markov Model of Change in Need Strength.

    Science.gov (United States)

    Rauschenberger, John; And Others

    1980-01-01

    In this study of 547 high school graduates, Alderfer's and Maslow's need hierarchy theories were expressed in Markov chain form and were subjected to empirical test. Both models were disconfirmed. Corroborative multiwave correlational analysis also failed to support the need hierarchy concept. (Author/IRT)

  12. Representation of the radiative strength functions in the practical model of cascade gamma decay

    International Nuclear Information System (INIS)

    Vu, D.C.; Sukhovoj, A.M.; Mitsyna, L.V.; Zeinalov, Sh.; Jovancevic, N.; Knezevic, D.; Krmar, M.; Dragic, A.

    2016-01-01

    The developed in Dubna practical model of the cascade gamma decay of neutron resonance allows one, from the fitted intensities of the two-step cascades, to obtain parameters both of level density and of partial widths of emission of nuclear reaction products. In the presented variant of the model a part of phenomenological representations is minimized. Analysis of new results confirms the previous finding that dynamics of interaction between Fermi- and Bose-nuclear states depends on the form of the nucleus. It also follows from the ratios of densities of vibrational and quasi-particle levels that this interaction exists at least up to the binding neutron energy and probably differs for nuclei with varied parities of nucleons. [ru

  13. European column buckling curves and finite element modelling including high strength steels

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Stan, Tudor-Cristian

    2017-01-01

    Eurocode allows for finite element modelling of plated steel structures, however the information in the code on how to perform the analysis or what assumptions to make is quite sparse. The present paper investigates the deterministic modelling of flexural column buckling using plane shell elements...... imperfections may be very conservative if considered by finite element analysis as described in the current Eurocode code. A suggestion is given for a slightly modified imperfection formula within the Ayrton-Perry formulation leading to adequate inclusion of modern high grade steels within the original four...... bucking curves. It is also suggested that finite element or frame analysis may be performed with equivalent column bow imperfections extracted directly from the Ayrton-Perry formulation....

  14. Hybrid RPA-cluster model for the dipole strength function of sup(11)Li

    International Nuclear Information System (INIS)

    Teruya, N.; Bertulani, C.A.; Krewald, S.

    1990-09-01

    A hybrid RPA-cluster model is developed and applied to the calculation of the dipole response of sup(11)L1. A strong collective state at 1.81 MeV is found. Its width is predicted to be 4.0 MeV. The electromagnetic excitation cross section was found to be 700 mb for sup(11)L1 + sup(208)Pb (E = 800 MeV/n), close to the experimental result. (author)

  15. Application of a global plasticity model to determine the ultimate strength of a reinforced concrete slab

    International Nuclear Information System (INIS)

    Hoffmann, A.; Millard, A.; Nahas, G.

    1983-08-01

    In order to predict the behaviour of composite beams and shells loaded up to failure, a global method has been developped. This method is based on a generalized stress approach, formulated in terms of moment-curvature relations. The case of a reinforced concrete slab subjected to uniform pressure has been considered. It is shown that numerical results compare fairly well with experimental data. Some improvements to the model are also suggested

  16. Numerical model of glulam beam delamination in dependence on cohesive strength

    Science.gov (United States)

    Kawecki, Bartosz; Podgórski, Jerzy

    2018-01-01

    This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit.

  17. The Public Health Innovation Model: Merging Private Sector Processes with Public Health Strengths.

    Science.gov (United States)

    Lister, Cameron; Payne, Hannah; Hanson, Carl L; Barnes, Michael D; Davis, Siena F; Manwaring, Todd

    2017-01-01

    Public health enjoyed a number of successes over the twentieth century. However, public health agencies have arguably been ill equipped to sustain these successes and address the complex threats we face today, including morbidity and mortality associated with persistent chronic diseases and emerging infectious diseases, in the context of flat funding and new and changing health care legislation. Transformational leaders, who are not afraid of taking risks to develop innovative approaches to combat present-day threats, are needed within public health agencies. We propose the Public Health Innovation Model (PHIM) as a tool for public health leaders who wish to integrate innovation into public health practice. This model merges traditional public health program planning models with innovation principles adapted from the private sector, including design thinking, seeking funding from private sector entities, and more strongly emphasizing program outcomes. We also discuss principles that leaders should consider adopting when transitioning to the PHIM, including cross-collaboration, community buy-in, human-centered assessment, autonomy and creativity, rapid experimentation and prototyping, and accountability to outcomes.

  18. The Public Health Innovation Model: Merging Private Sector Processes with Public Health Strengths

    Directory of Open Access Journals (Sweden)

    Cameron Lister

    2017-08-01

    Full Text Available Public health enjoyed a number of successes over the twentieth century. However, public health agencies have arguably been ill equipped to sustain these successes and address the complex threats we face today, including morbidity and mortality associated with persistent chronic diseases and emerging infectious diseases, in the context of flat funding and new and changing health care legislation. Transformational leaders, who are not afraid of taking risks to develop innovative approaches to combat present-day threats, are needed within public health agencies. We propose the Public Health Innovation Model (PHIM as a tool for public health leaders who wish to integrate innovation into public health practice. This model merges traditional public health program planning models with innovation principles adapted from the private sector, including design thinking, seeking funding from private sector entities, and more strongly emphasizing program outcomes. We also discuss principles that leaders should consider adopting when transitioning to the PHIM, including cross-collaboration, community buy-in, human-centered assessment, autonomy and creativity, rapid experimentation and prototyping, and accountability to outcomes.

  19. Factors Affecting the Longevity and Strength in an In Vitro Model of the Bone–Ligament Interface

    Science.gov (United States)

    Paxton, Jennifer Z.; Donnelly, Kenneth; Keatch, Robert P.; Grover, Liam M.

    2010-01-01

    The interfaces between musculoskeletal tissues with contrasting moduli are morphologically and biochemically adapted to allow the transmission of force with minimal injury. Current methods of tissue engineering ligaments and tendons do not include the interface and this may limit the future clinical success of engineered musculoskeletal tissues. This study aimed to use solid brushite cement anchors to engineer intact ligaments from bone-to-bone, creating a functional musculoskeletal interface in vitro. We show here that modifying anchor shape and cement composition can alter both the longevity and the strength of an in vitro model of the bone–ligament interface: with values reaching 23 days and 21.6 kPa, respectively. These results validate the use of brushite bone cement to engineer the bone–ligament interface in vitro and raise the potential for future use in ligament replacement surgery. PMID:20431953

  20. Computer-aided model analysis for ionic strength-dependent effective charge of protein in ion-exchange chromatography

    DEFF Research Database (Denmark)

    Lim, Young-il; Jørgensen, Sten Bay; Kim, In-Ho

    2005-01-01

    differential algebraic equation (PDAE) system, a fast and accurate numerical method (i.e., conservation element/solution element (CE/SE) method), is proposed. Sensitivity and elasticity of the model parameters (e.g., steric/shape factors, adsorption heat coefficient, effective protein charge, equilibrium...... constant, mass transfer coefficient, axial dispersion coefficient and bed voidage) are analyzed for a BSA-salt system in a low protein concentration range. Within a low concentration range of bovine serum albumin (BSA) where linear adsorption isotherms are shown, the adsorption heat coefficient, shape...... salt concentrations, it is proposed that the effective protein charge could depend upon the salt concentration (or ionic strength). The reason for this dependence may be a steric hindrance of protein binding sites combined with a salt shielding effect neutralizing the surface charges of the protein. (c...

  1. Accuracy of the models for the evaluation of strength under non-standard lightning impulse (overvoltages transmitted from overhead lines)

    Energy Technology Data Exchange (ETDEWEB)

    Pigini, A.; Rizzi, G.; Garbagnati, E.; Porrino, A.; Baldo, G.; Pesavento, G.

    1987-10-01

    Approaches to evaluate the strength of external insulation exposed to lightning overvoltages can be grouped into: physical approaches, which, in their general form, evaluate the time to breakdown for a given applied voltage as the sum of the times necessary for the development of the various phenomena involved in the discharge; integration methods, which consider the time integral of the difference between the applied and fixed voltages. From an analysis of the results of systematic tests conducted on rod plane, rod rod and conductor structure configurations, with clearances from 2 to 4 meters, it was concluded that the integration methods are generally less accurate than the use of physical models, the only approach which takes into account the interaction between test circuit and test object.

  2. Modelling and simulation of the influence of forming processes on the structural behavior of high strength steels

    International Nuclear Information System (INIS)

    Gelin, J.C.; Thibaud, S.; Boudeau, N.

    2005-01-01

    The paper first describes experiments and modeling concerning the identification of material behavior for high strength steels with phase transformations associated to plastic deformation. The experiments consist of tensile and bulging tests carried out on 316L stainless steels and TRIP 700 steels used in automotive industry. These experiments have permitted to determine the hardening curves of such materials vs. the martensite volume fraction associated to plastic deformation. It has been demonstrated that the stress triaxiality has a major role in the martenstic transformation and a model is proposed to define the flow stress vs. effective strain accounting planar anisotropy and variation of martenstic volume fraction. Then a plasticity model has been proposed in an anisotropic form and the related flow rules have been defined. The resulting model has been implemented in different finite elements software, and applied in numerical simulations of stamping and hydroforming of typical components to prove the effects of forming processes on the resulting properties of the components. Finally, the structural behavior of the resulting components is investigated and the effects of forming processes on the resulting structural behaviour are analyzed. Two cases are presented, one concerns the deep drawing of a cylindrical cup and the other concerns the stamping of a closed U channel used as a structural part for crash frames. Is has been clearly proved that the variation of martensite volume fraction arising during processing has a strong influence on the resulting behaviour of the parts considering springback and crash resistance

  3. Strengths and Limitations of Model Systems for the Study of Urinary Tract Infections and Related Pathologies

    Science.gov (United States)

    Barber, Amelia E.; Norton, J. Paul; Wiles, Travis J.

    2016-01-01

    SUMMARY Urinary tract infections (UTIs) are some of the most common bacterial infections worldwide and are a source of substantial morbidity among otherwise healthy women. UTIs can be caused by a variety of microbes, but the predominant etiologic agent of these infections is uropathogenic Escherichia coli (UPEC). An especially troubling feature of UPEC-associated UTIs is their high rate of recurrence. This problem is compounded by the drastic increase in the global incidence of antibiotic-resistant UPEC strains over the past 15 years. The need for more-effective treatments for UTIs is driving research aimed at bettering our understanding of the virulence mechanisms and host-pathogen interactions that occur during the course of these infections. Surrogate models of human infection, including cell culture systems and the use of murine, porcine, avian, teleost (zebrafish), and nematode hosts, are being employed to define host and bacterial factors that modulate the pathogenesis of UTIs. These model systems are revealing how UPEC strains can avoid or overcome host defenses and acquire scarce nutrients while also providing insight into the virulence mechanisms used by UPEC within compromised individuals, such as catheterized patients. Here, we summarize our current understanding of UTI pathogenesis while also giving an overview of the model systems used to study the initiation, persistence, and recurrence of UTIs and life-threatening sequelae like urosepsis. Although we focus on UPEC, the experimental systems described here can also provide valuable insight into the disease processes associated with other bacterial pathogens both within the urinary tract and elsewhere within the host. PMID:26935136

  4. A survey of etiologic hypotheses among testicular cancer researchers.

    Science.gov (United States)

    Stang, A; Trabert, B; Rusner, C; Poole, C; Almstrup, K; Rajpert-De Meyts, E; McGlynn, K A

    2015-01-01

    Basic research results can provide new ideas and hypotheses to be examined in epidemiological studies. We conducted a survey among testicular cancer researchers on hypotheses concerning the etiology of this malignancy. All researchers on the mailing list of Copenhagen Testis Cancer Workshops and corresponding authors of PubMed-indexed articles identified by the search term 'testicular cancer' and published within 10 years (in total 2750 recipients) were invited to respond to an e-mail-based survey. Participants of the 8th Copenhagen Testis Cancer Workshop in May 2014 were subsequently asked to rate the plausibility of the suggested etiologic hypotheses on a scale of 1 (very implausible) to 10 (very plausible). This report describes the methodology of the survey, the score distributions by individual hypotheses, hypothesis group, and the participants' major research fields, and discuss the hypotheses that scored as most plausible. We also present plans for improving the survey that may be repeated at a next international meeting of experts in testicular cancer. Overall 52 of 99 (53%) registered participants of the 8th Copenhagen Testis Cancer Workshop submitted the plausibility rating form. Fourteen of 27 hypotheses were related to exposures during pregnancy. Hypotheses with the highest mean plausibility ratings were either related to pre-natal exposures or exposures that might have an effect during pregnancy and in post-natal life. The results of the survey may be helpful for triggering more specific etiologic hypotheses that include factors related to endocrine disruption, DNA damage, inflammation, and nutrition during pregnancy. The survey results may stimulate a multidisciplinary discussion about new etiologic hypotheses of testicular cancer. Published 2014. This article is a U. S. Government work and is in the public domain in the USA.

  5. Representation of radiative strength functions within a practical model of cascade gamma decay

    Energy Technology Data Exchange (ETDEWEB)

    Vu, D. C., E-mail: vuconghnue@gmail.com; Sukhovoj, A. M., E-mail: suchovoj@nf.jinr.ru; Mitsyna, L. V., E-mail: mitsyna@nf.jinr.ru; Zeinalov, Sh., E-mail: zeinal@nf.jinr.ru [Joint Institute for Nuclear Research (Russian Federation); Jovancevic, N., E-mail: nikola.jovancevic@df.uns.ac.rs; Knezevic, D., E-mail: david.knezevic@df.uns.ac.rs; Krmar, M., E-mail: krmar@df.uns.ac.rs [University of Novi Sad, Department of Physics, Faculty of Sciences (Serbia); Dragic, A., E-mail: dragic@ipb.ac.rs [Institute of Physics Belgrade (Serbia)

    2017-03-15

    A practical model developed at the Joint Institute for Nuclear Research (JINR, Dubna) in order to describe the cascade gamma decay of neutron resonances makes it possible to determine simultaneously, from an approximation of the intensities of two-step cascades, parameters of nuclear level densities and partial widths with respect to the emission of nuclear-reaction products. The number of the phenomenological ideas used isminimized in themodel version considered in the present study. An analysis of new results confirms what was obtained earlier for the dependence of dynamics of the interaction of fermion and boson nuclear states on the nuclear shape. From the ratio of the level densities for excitations of the vibrational and quasiparticle types, it also follows that this interaction manifests itself in the region around the neutron binding energy and is probably different in nuclei that have different parities of nucleons.

  6. Industrial-Strength Model-Based Testing - State of the Art and Current Challenges

    Directory of Open Access Journals (Sweden)

    Jan Peleska

    2013-03-01

    Full Text Available As of today, model-based testing (MBT is considered as leading-edge technology in industry. We sketch the different MBT variants that - according to our experience - are currently applied in practice, with special emphasis on the avionic, railway and automotive domains. The key factors for successful industrial-scale application of MBT are described, both from a scientific and a managerial point of view. With respect to the former view, we describe the techniques for automated test case, test data and test procedure generation for concurrent reactive real-time systems which are considered as the most important enablers for MBT in practice. With respect to the latter view, our experience with introducing MBT approaches in testing teams are sketched. Finally, the most challenging open scientific problems whose solutions are bound to improve the acceptance and effectiveness of MBT in industry are discussed.

  7. FEM Modeling of In-Plane Stress Distribution in Thick Brittle Coatings/Films on Ductile Substrates Subjected to Tensile Stress to Determine Interfacial Strength

    Directory of Open Access Journals (Sweden)

    Kaishi Wang

    2018-03-01

    Full Text Available The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young’s modulus, on the in-plane stress distribution have also been investigated. ‘Thickness-averaged In-plane Stress’ (TIS, a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.

  8. FEM Modeling of In-Plane Stress Distribution in Thick Brittle Coatings/Films on Ductile Substrates Subjected to Tensile Stress to Determine Interfacial Strength.

    Science.gov (United States)

    Wang, Kaishi; Zhang, Fangzhou; Bordia, Rajendra K

    2018-03-27

    The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm) on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young's modulus, on the in-plane stress distribution have also been investigated. 'Thickness-averaged In-plane Stress' (TIS), a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.

  9. Fear of knowledge: Clinical hypotheses in diagnostic and prognostic reasoning.

    Science.gov (United States)

    Chiffi, Daniele; Zanotti, Renzo

    2017-10-01

    Patients are interested in receiving accurate diagnostic and prognostic information. Models and reasoning about diagnoses have been extensively investigated from a foundational perspective; however, for all its importance, prognosis has yet to receive a comparable degree of philosophical and methodological attention, and this may be due to the difficulties inherent in accurate prognostics. In the light of these considerations, we discuss a considerable body of critical thinking on the topic of prognostication and its strict relations with diagnostic reasoning, pointing out the distinction between nosographic and pathophysiological types of diagnosis and prognosis, underlying the importance of the explication and explanation processes. We then distinguish between various forms of hypothetical reasoning applied to reach diagnostic and prognostic judgments, comparing them with specific forms of abductive reasoning. The main thesis is that creative abduction regarding clinical hypotheses in diagnostic process is very unlikely to occur, whereas this seems to be often the case for prognostic judgments. The reasons behind this distinction are due to the different types of uncertainty involved in diagnostic and prognostic judgments. © 2016 John Wiley & Sons, Ltd.

  10. Host Lipid Mediators in Leprosy: The Hypothesized Contributions to Pathogenesis

    Directory of Open Access Journals (Sweden)

    Carlos A. M. Silva

    2018-02-01

    Full Text Available The spectrum of clinical forms observed in leprosy and its pathogenesis are dictated by the host’s immune response against Mycobacterium leprae, the etiological agent of leprosy. Previous results, based on metabolomics studies, demonstrated a strong relationship between clinical manifestations of leprosy and alterations in the metabolism of ω3 and ω6 polyunsaturated fatty acids (PUFAs, and the diverse set of lipid mediators derived from PUFAs. PUFA-derived lipid mediators provide multiple functions during acute inflammation, and some lipid mediators are able to induce both pro- and anti-inflammatory responses as determined by the cell surface receptors being expressed, as well as the cell type expressing the receptors. However, little is known about how these compounds influence cellular immune activities during chronic granulomatous infectious diseases, such as leprosy. Current evidence suggests that specialized pro-resolving lipid mediators (SPMs are involved in the down-modulation of the innate and adaptive immune response against M. leprae and that alteration in the homeostasis of pro-inflammatory lipid mediators versus SPMs is associated with dramatic shifts in the pathogenesis of leprosy. In this review, we discuss the possible consequences and present new hypotheses for the involvement of ω3 and ω6 PUFA metabolism in the pathogenesis of leprosy. A specific emphasis is placed on developing models of lipid mediator interactions with the innate and adaptive immune responses and the influence of these interactions on the outcome of leprosy.

  11. [The evolution of plant life span: facts and hypotheses].

    Science.gov (United States)

    2006-01-01

    There are two different views on the evolution of life forms in Cormophyta: from woody plants to herbaceous ones or in opposite direction - from herbs to trees. In accordance with these views it is supposed that life span in plants changed in the course of evolution from many years (perennials) to few years (annuals, biennials), or went in reverse - from few years to many years. The author discusses the problems of senescence and longevity in Cormophyta in the context of various hypotheses of ageing (programmed death theory, mutation accumulation, antagonistic pleiotropy, disposable soma, genes of ageing, genes of longevity). Special attention is given to bio-morphological aspects of longevity and cases of non-ageing plants ("negative senescence", "potential immortality"). It is proposed to distinguish seven models of simple ontogenesis in Cormophyta that can exemplify the diversity of mechanisms of ageing and longevity. The evolution of life span in plants is considered as an indirect result of natural selection of other characteristics of organisms or as a consequence of fixation of modifications (episelectional evolution). It seems that short life span could emerge several times during evolution of one group of plants, thus favoring its adaptive radiation.

  12. An automated framework for hypotheses generation using literature

    Directory of Open Access Journals (Sweden)

    Abedi Vida

    2012-08-01

    Full Text Available Abstract Background In bio-medicine, exploratory studies and hypothesis generation often begin with researching existing literature to identify a set of factors and their association with diseases, phenotypes, or biological processes. Many scientists are overwhelmed by the sheer volume of literature on a disease when they plan to generate a new hypothesis or study a biological phenomenon. The situation is even worse for junior investigators who often find it difficult to formulate new hypotheses or, more importantly, corroborate if their hypothesis is consistent with existing literature. It is a daunting task to be abreast with so much being published and also remember all combinations of direct and indirect associations. Fortunately there is a growing trend of using literature mining and knowledge discovery tools in biomedical research. However, there is still a large gap between the huge amount of effort and resources invested in disease research and the little effort in harvesting the published knowledge. The proposed hypothesis generation framework (HGF finds “crisp semantic associations” among entities of interest - that is a step towards bridging such gaps. Methodology The proposed HGF shares similar end goals like the SWAN but are more holistic in nature and was designed and implemented using scalable and efficient computational models of disease-disease interaction. The integration of mapping ontologies with latent semantic analysis is critical in capturing domain specific direct and indirect “crisp” associations, and making assertions about entities (such as disease X is associated with a set of factors Z. Results Pilot studies were performed using two diseases. A comparative analysis of the computed “associations” and “assertions” with curated expert knowledge was performed to validate the results. It was observed that the HGF is able to capture “crisp” direct and indirect associations, and provide knowledge

  13. An automated framework for hypotheses generation using literature.

    Science.gov (United States)

    Abedi, Vida; Zand, Ramin; Yeasin, Mohammed; Faisal, Fazle Elahi

    2012-08-29

    In bio-medicine, exploratory studies and hypothesis generation often begin with researching existing literature to identify a set of factors and their association with diseases, phenotypes, or biological processes. Many scientists are overwhelmed by the sheer volume of literature on a disease when they plan to generate a new hypothesis or study a biological phenomenon. The situation is even worse for junior investigators who often find it difficult to formulate new hypotheses or, more importantly, corroborate if their hypothesis is consistent with existing literature. It is a daunting task to be abreast with so much being published and also remember all combinations of direct and indirect associations. Fortunately there is a growing trend of using literature mining and knowledge discovery tools in biomedical research. However, there is still a large gap between the huge amount of effort and resources invested in disease research and the little effort in harvesting the published knowledge. The proposed hypothesis generation framework (HGF) finds "crisp semantic associations" among entities of interest - that is a step towards bridging such gaps. The proposed HGF shares similar end goals like the SWAN but are more holistic in nature and was designed and implemented using scalable and efficient computational models of disease-disease interaction. The integration of mapping ontologies with latent semantic analysis is critical in capturing domain specific direct and indirect "crisp" associations, and making assertions about entities (such as disease X is associated with a set of factors Z). Pilot studies were performed using two diseases. A comparative analysis of the computed "associations" and "assertions" with curated expert knowledge was performed to validate the results. It was observed that the HGF is able to capture "crisp" direct and indirect associations, and provide knowledge discovery on demand. The proposed framework is fast, efficient, and robust in

  14. Experimental investigation and empirical modelling of FDM process for compressive strength improvement

    Directory of Open Access Journals (Sweden)

    Anoop K. Sood

    2012-01-01

    Full Text Available Fused deposition modelling (FDM is gaining distinct advantage in manufacturing industries because of its ability to manufacture parts with complex shapes without any tooling requirement and human interface. The properties of FDM built parts exhibit high dependence on process parameters and can be improved by setting parameters at suitable levels. Anisotropic and brittle nature of build part makes it important to study the effect of process parameters to the resistance to compressive loading for enhancing service life of functional parts. Hence, the present work focuses on extensive study to understand the effect of five important parameters such as layer thickness, part build orientation, raster angle, raster width and air gap on the compressive stress of test specimen. The study not only provides insight into complex dependency of compressive stress on process parameters but also develops a statistically validated predictive equation. The equation is used to find optimal parameter setting through quantum-behaved particle swarm optimization (QPSO. As FDM process is a highly complex one and process parameters influence the responses in a non linear manner, compressive stress is predicted using artificial neural network (ANN and is compared with predictive equation.

  15. Three-dimensional in vitro cancer spheroid models for Photodynamic Therapy: Strengths and Opportunities

    Science.gov (United States)

    Evans, Conor

    2015-03-01

    Three dimensional, in vitro spheroid cultures offer considerable utility for the development and testing of anticancer photodynamic therapy regimens. More complex than monolayer cultures, three-dimensional spheroid systems replicate many of the important cell-cell and cell-matrix interactions that modulate treatment response in vivo. Simple enough to be grown by the thousands and small enough to be optically interrogated, spheroid cultures lend themselves to high-content and high-throughput imaging approaches. These advantages have enabled studies investigating photosensitizer uptake, spatiotemporal patterns of therapeutic response, alterations in oxygen diffusion and consumption during therapy, and the exploration of mechanisms that underlie therapeutic synergy. The use of quantitative imaging methods, in particular, has accelerated the pace of three-dimensional in vitro photodynamic therapy studies, enabling the rapid compilation of multiple treatment response parameters in a single experiment. Improvements in model cultures, the creation of new molecular probes of cell state and function, and innovations in imaging toolkits will be important for the advancement of spheroid culture systems for future photodynamic therapy studies.

  16. Sleep deprivation, low self-control, and delinquency: a test of the strength model of self-control.

    Science.gov (United States)

    Meldrum, Ryan C; Barnes, J C; Hay, Carter

    2015-02-01

    Recent work provides evidence that sleep deprivation is positively related to delinquency. In this study, we draw on Baumeister and colleagues' strength model of self-control to propose an explanation for this association. Specifically, we argue that low self-control is the construct that bridges the relationship between sleep deprivation and delinquency. To test the proposed model, we examine survey data drawn from a longitudinal multi-city cohort study of adolescents who were followed from birth through age 15 (N = 825; 50% female; 82% non-Hispanic white, 59% two-parent nuclear family). The results from regression models using latent factors indicate: sleep deprivation is positively related to low self-control; low self-control is positively related to delinquency; and the relationship between sleep deprivation and delinquency is indirect and operates through low self-control. Impressively, these relationships emerged when accounting for potential background sources of spuriousness, including neighborhood context, depressive symptoms, parenting practices, unstructured socializing with peers, and prior delinquency. Implications and directions for future research are discussed.

  17. Delayed administration of recombinant human parathyroid hormone improves early biomechanical strength in a rat rotator cuff repair model.

    Science.gov (United States)

    Duchman, Kyle R; Goetz, Jessica E; Uribe, Bastian U; Amendola, Andrew M; Barber, Joshua A; Malandra, Allison E; Fredericks, Douglas C; Hettrich, Carolyn M

    2016-08-01

    Despite advances in intraoperative techniques, rotator cuff repairs frequently do not heal. Recombinant human parathyroid hormone (rhPTH) has been shown to improve healing at the tendon-to-bone interface in an established acute rat rotator cuff repair model. We hypothesized that administration of rhPTH beginning on postoperative day 7 would result in improved early load to failure after acute rotator cuff repair in an established rat model. Acute rotator cuff repairs were performed in 108 male Sprague-Dawley rats. Fifty-four rats received daily injections of rhPTH beginning on postoperative day 7 until euthanasia or a maximum of 12 weeks postoperatively. The remaining 54 rats received no injections and served as the control group. Animals were euthanized at 2 and 16 weeks postoperatively and evaluated by gross inspection, biomechanical testing, and histologic analysis. At 2 weeks postoperatively, rats treated with rhPTH demonstrated significantly higher load to failure than controls (10.9 vs. 5.2 N; P = .003). No difference in load to failure was found between the 2 groups at 16 weeks postoperatively, although control repairs more frequently failed at the tendon-to-bone interface (45.5% vs. 22.7%; P = .111). Blood vessel density appeared equivalent between the 2 groups at both time points, but increased intracellular and extracellular vascular endothelial growth factor expression was noted in the rhPTH-treated group at 2 weeks. Delayed daily administration of rhPTH resulted in increased early load to failure and equivalent blood vessel density in an acute rotator cuff repair model. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  18. Mirror bootstrap method for testing hypotheses of one mean

    OpenAIRE

    Varvak, Anna

    2012-01-01

    The general philosophy for bootstrap or permutation methods for testing hypotheses is to simulate the variation of the test statistic by generating the sampling distribution which assumes both that the null hypothesis is true, and that the data in the sample is somehow representative of the population. This philosophy is inapplicable for testing hypotheses for a single parameter like the population mean, since the two assumptions are contradictory (e.g., how can we assume both that the mean o...

  19. Comparison of the Pullout Strength of Different Pedicle Screw Designs and Augmentation Techniques in an Osteoporotic Bone Model.

    Science.gov (United States)

    Kiyak, Gorkem; Balikci, Tevfik; Heydar, Ahmed Majid; Bezer, Murat

    2018-02-01

    Mechanical study. To compare the pullout strength of different screw designs and augmentation techniques in an osteoporotic bone model. Adequate bone screw pullout strength is a common problem among osteoporotic patients. Various screw designs and augmentation techniques have been developed to improve the biomechanical characteristics of the bone-screw interface. Polyurethane blocks were used to mimic human osteoporotic cancellous bone, and six different screw designs were tested. Five standard and expandable screws without augmentation, eight expandable screws with polymethylmethacrylate (PMMA) or calcium phosphate augmentation, and distal cannulated screws with PMMA and calcium phosphate augmentation were tested. Mechanical tests were performed on 10 unused new screws of each group. Screws with or without augmentation were inserted in a block that was held in a fixture frame, and a longitudinal extraction force was applied to the screw head at a loading rate of 5 mm/min. Maximum load was recorded in a load displacement curve. The peak pullout force of all tested screws with or without augmentation was significantly greater than that of the standard pedicle screw. The greatest pullout force was observed with 40-mm expandable pedicle screws with four fins and PMMA augmentation. Augmented distal cannulated screws did not have a greater peak pullout force than nonaugmented expandable screws. PMMA augmentation provided a greater peak pullout force than calcium phosphate augmentation. Expandable pedicle screws had greater peak pullout forces than standard pedicle screws and had the advantage of augmentation with either PMMA or calcium phosphate cement. Although calcium phosphate cement is biodegradable, osteoconductive, and nonexothermic, PMMA provided a significantly greater peak pullout force. PMMA-augmented expandable 40-mm four-fin pedicle screws had the greatest peak pullout force.

  20. A Bayesian decision procedure for testing multiple hypotheses in DNA microarray experiments.

    Science.gov (United States)

    Gómez-Villegas, Miguel A; Salazar, Isabel; Sanz, Luis

    2014-02-01

    DNA microarray experiments require the use of multiple hypothesis testing procedures because thousands of hypotheses are simultaneously tested. We deal with this problem from a Bayesian decision theory perspective. We propose a decision criterion based on an estimation of the number of false null hypotheses (FNH), taking as an error measure the proportion of the posterior expected number of false positives with respect to the estimated number of true null hypotheses. The methodology is applied to a Gaussian model when testing bilateral hypotheses. The procedure is illustrated with both simulated and real data examples and the results are compared to those obtained by the Bayes rule when an additive loss function is considered for each joint action and the generalized loss 0-1 function for each individual action. Our procedure significantly reduced the percentage of false negatives whereas the percentage of false positives remains at an acceptable level.

  1. Dynamic Strength and Accumulated Plastic Strain Development Laws and Models of the Remolded Red Clay under Long-Term Cyclic Loads: Laboratory Test Results

    Directory of Open Access Journals (Sweden)

    Li Jian

    2015-09-01

    Full Text Available The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.

  2. Dynamic locking screw improves fixation strength in osteoporotic bone: an in vitro study on an artificial bone model.

    Science.gov (United States)

    Pohlemann, Tim; Gueorguiev, Boyko; Agarwal, Yash; Wahl, Dieter; Sprecher, Christoph; Schwieger, Karsten; Lenz, Mark

    2015-04-01

    The novel dynamic locking screw (DLS) was developed to improve bone healing with locked-plate osteosynthesis by equalising construct stiffness at both cortices. Due to a theoretical damping effect, this modulated stiffness could be beneficial for fracture fixation in osteoporotic bone. Therefore, the mechanical behaviour of the DLS at the screw-bone interface was investigated in an artificial osteoporotic bone model and compared with conventional locking screws (LHS). Osteoporotic surrogate bones were plated with either a DLS or a LHS construct consisting of two screws and cyclically axially loaded (8,500 cycles, amplitude 420 N, increase 2 mN/cycle). Construct stiffness, relative movement, axial screw migration, proximal (P) and distal (D) screw pullout force and loosening at the bone interface were determined and statistically evaluated. DLS constructs exhibited a higher screw pullout force of P 85 N [standard deviation (SD) 21] and D 93 N (SD 12) compared with LHS (P 62 N, SD 28, p = 0.1; D 57 N, SD 25, p LHS (p = 0.01). DLS constructs showed significantly lower axial construct stiffness (403 N/mm, SD 21, p LHS (529 N/mm, SD 27; 0.8 mm, SD 0.04). Based on the model data, the DLS principle might also improve in vivo plate fixation in osteoporotic bone, providing enhanced residual holding strength and reducing screw cutout. The influence of pin-sleeve abutment still needs to be investigated.

  3. Instrumented anvil-on-rod impact experiments for validating constitutive strength model for simulating transient dynamic deformation response of metals

    International Nuclear Information System (INIS)

    Martin, M.; Shen, T.; Thadhani, N.N.

    2008-01-01

    Instrumented anvil-on-rod impact experiments were performed to access the applicability of this approach for validating a constitutive strength model for dynamic, transient-state deformation and elastic-plastic wave interactions in vanadium, 21-6-9 stainless steel, titanium, and Ti-6Al-4V. In addition to soft-catching the impacted rod-shaped samples, their transient deformation states were captured by high-speed imaging, and velocity interferometry was used to record the sample back (free) surface velocity and monitor elastic-plastic wave interactions. Simulations utilizing AUTODYN-2D hydrocode with Steinberg-Guinan constitutive equation were used to generate simulated free surface velocity traces and final/transient deformation profiles for comparisons with experiments. The simulations were observed to under-predict the radial strain for bcc vanadium and fcc steel, but over-predict the radial strain for hcp titanium and Ti-6Al-4V. The correlations illustrate the applicability of the instrumented anvil-on-rod impact test as a method for providing robust model validation based on the entire deformation event, and not just the final deformed state

  4. Ion Exchange Distribution Coefficient Tests and Computer Modeling at High Ionic Strength Supporting Technetium Removal Resin Maturation

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Charles A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, Frank G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, Daniel J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-12-19

    The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant (WTP) that is currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and poured into canisters for disposition. The LAW glass will be disposed onsite in the Integrated Disposal Facility (IDF). There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the water solubility properties of pertechnetate and long half-life of 99Tc, effective management of 99Tc is important to the overall success of the Hanford River Protection Project mission. To achieve the full target WTP throughput, additional LAW immobilization capacity is needed, and options are being explored to immobilize the supplemental LAW portion of the tank waste. Removal of 99Tc, followed by off-site disposal, would eliminate a key risk contributor for the IDF Performance Assessment (PA) for supplemental waste forms, and has potential to reduce treatment and disposal costs. Washington River Protection Solutions (WRPS) is developing some conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal. One of these flowsheets will specifically examine removing 99Tc from the LAW feed stream to supplemental immobilization. To enable an informed decision regarding the viability of technetium removal, further maturation of available technologies is being performed. This report contains results of experimental ion exchange distribution coefficient testing and computer modeling using the resin SuperLig® 639a to selectively remove perrhenate from high ionic strength simulated LAW. It is advantageous to operate at higher concentration in order to treat the waste

  5. Application of the Multi-Doorway Continuum Shell Model to the Magnetic Dipole Strength Distribution in 58Ni

    Science.gov (United States)

    Spangenberger, H.; Beck, F.; Richter, A.

    The usual continuum shell model is extended so as to include a statistical treatment of multi-doorway processes. The total configuration space of the nuclear reaction problem is subdivided into the primary doorway states which are coupled by the initial excitation to the nuclear ground state and the secondary doorway states which represent the complicated nature of multi-step reactions. The latter are evaluated within the exciton model which gives the coupling widths between the various finestructure subspaces. This coupling is determined by a statistical factor related to the exciton model and a dynamical factor given by the interaction matrix elements of the interacting excitons. The whole structure defines the multi-doorway continuum shell model. In this work it is applied to the highly fragmented magnetic dipole strength in 58Ni observed in high resolution electron scattering.Translated AbstractAnwendung des Multi-Doorway-Kontinuum-Schalenmodells auf die Verteilung der magnetischen Dipolstärke von 58NiDas Kontinuum-Schalenmodell wurde so erweitert, daß auch statistische Multi-Doorway-Prozesse berücksichtigt werden können. Hierzu wird der Konfigurationsraum unterteilt in den Raum der primären Doorway-Zustände, die direkt aus dem Grundzustand angeregt werden, und den der sekundären Doorway-Zustände, die die komplizierte Struktur der Multi-Step-Reaktionen repräsentieren. Während die primären Doorway-Zustände inclusive ihrer Anregungen mittels üblicher Schalenmodellmethoden beschrieben werden können, werden die sekundären Doorway-Zustände sowie ihre verschiedenen Kopplungen im Rahmen des Exciton-Modells behandelt. Diese Kopplungen sind durch einen aus dem Exciton-Modell resultierenden Faktor sowie durch einen dynamischen Faktor bestimmt, der sich aus dem Matrixelement der wechselwirkenden Excitonen berechnet. Die Struktur der Kopplungen definiert das Multi-Doorway-Kontinuum-Schalenmodell, das hier auf die Beschreibung der stark fragmentierten

  6. Preliminary testing of flow-ecology hypotheses developed for the GCP LCC region

    Science.gov (United States)

    Brewer, Shannon K.; Davis, Mary

    2014-01-01

    some of the data concerns and improve hypothesis interpretation. If the regional hydrologic model currently under development by the U.S. Geological Survey for the South-Central Climate Science Center is improved to produce daily hydrographs, it will enable use of fish data at ungaged locations. In future efforts, exhaustive analyses using these data, in addition to the development of more complex multivariate hypotheses, would be beneficial to understanding data gaps, particularly as relevant to species of conservation concern.

  7. Instrumented Taylor anvil-on-rod impact tests for validating applicability of standard strength models to transient deformation states

    Science.gov (United States)

    Eakins, D. E.; Thadhani, N. N.

    2006-10-01

    Instrumented Taylor anvil-on-rod impact tests have been conducted on oxygen-free electronic copper to validate the accuracy of current strength models for predicting transient states during dynamic deformation events. The experiments coupled the use of high-speed digital photography to record the transient deformation states and laser interferometry to monitor the sample back (free surface) velocity as a measure of the elastic/plastic wave propagation through the sample length. Numerical continuum dynamics simulations of the impact and plastic wave propagation employing the Johnson-Cook [Proceedings of the Seventh International Symposium on Ballistics, 1983, The Netherlands (Am. Def. Prep. Assoc. (ADPA)), pp. 541-547], Zerilli-Armstrong [J. Appl. Phys. C1, 1816 (1987)], and Steinberg-Guinan [J. Appl. Phys. 51, 1498 (1980)] constitutive equations were used to generate transient deformation profiles and the free surface velocity traces. While these simulations showed good correlation with the measured free surface velocity traces and the final deformed sample shape, varying degrees of deviations were observed between the photographed and calculated specimen profiles at intermediate deformation states. The results illustrate the usefulness of the instrumented Taylor anvil-on-rod impact technique for validating constitutive equations that can describe the path-dependent deformation response and can therefore predict the transient and final deformation states.

  8. STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

    Directory of Open Access Journals (Sweden)

    NOZEMTСEV Alexandr Sergeevich

    2013-02-01

    Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

  9. Work Environment Dialogue in a Swedish Municipality — Strengths and Limits of the Nordic Work Environment Model

    Directory of Open Access Journals (Sweden)

    Kaj Frick

    2013-01-01

    were as demonstrated by other research on municipalities’ limited development capacity. Hälsosam’s narrow focus was also supported by the limited priorities of the national municipal employers. This gave a narrow perspective in the central social partners’ consultants to Leksand and other municipalities. Hälsosam thereby demonstrates both the strengths and the weaknesses of the Nordic work environment model. On the one hand, the local dialogue was even further improved. On the other, local and central trade union cooperation with the employers did not enable them to much raise the organizational problems of work overload and poor work environment management. Leksand’s municipal employees remained squeezed between limited taxes and unlimited service demands and had to “solve” this by too hard work.

  10. Adult Brtl/+ mouse model of osteogenesis imperfecta demonstrates anabolic response to sclerostin antibody treatment with increased bone mass and strength.

    Science.gov (United States)

    Sinder, B P; White, L E; Salemi, J D; Ominsky, M S; Caird, M S; Marini, J C; Kozloff, K M

    2014-08-01

    Treatments to reduce fracture rates in adults with osteogenesis imperfecta are limited. Sclerostin antibody, developed for treating osteoporosis, has not been explored in adults with OI. This study demonstrates that treatment of adult OI mice respond favorably to sclerostin antibody therapy despite retention of the OI-causing defect. Osteogenesis imperfecta (OI) is a heritable collagen-related bone dysplasia, characterized by brittle bones with increased fracture risk. Although OI fracture risk is greatest before puberty, adults with OI remain at risk of fracture. Antiresorptive bisphosphonates are commonly used to treat adult OI, but have shown mixed efficacy. New treatments which consistently improve bone mass throughout the skeleton may improve patient outcomes. Neutralizing antibodies to sclerostin (Scl-Ab) are a novel anabolic therapy that have shown efficacy in preclinical studies by stimulating bone formation via the canonical wnt signaling pathway. The purpose of this study was to evaluate Scl-Ab in an adult 6 month old Brtl/+ model of OI that harbors a typical heterozygous OI-causing Gly > Cys substitution on Col1a1. Six-month-old WT and Brtl/+ mice were treated with Scl-Ab (25 mg/kg, 2×/week) or Veh for 5 weeks. OCN and TRACP5b serum assays, dynamic histomorphometry, microCT and mechanical testing were performed. Adult Brtl/+ mice demonstrated a strong anabolic response to Scl-Ab with increased serum osteocalcin and bone formation rate. This anabolic response led to improved trabecular and cortical bone mass in the femur. Mechanical testing revealed Scl-Ab increased Brtl/+ femoral stiffness and strength. Scl-Ab was successfully anabolic in an adult Brtl/+ model of OI.

  11. Modeling of the hot flow behavior of advanced ultra-high strength steels (A-UHSS) microalloyed with boron

    Energy Technology Data Exchange (ETDEWEB)

    Mejía, I., E-mail: imejia@umich.mx [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Altamirano, G.; Bedolla-Jacuinde, A. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Cabrera, J.M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB – Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnològic, Av. de las Bases de Manresa, 1, 08240 Manresa (Spain)

    2014-07-29

    In this research work, modeling of the hot flow behavior was carried out in a low carbon advanced ultra-high strength steels (A-UHSS) microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm). For this purpose, experimental stress–strain data of uniaxial hot-compression tests over a wide range of temperatures (1223, 1273, 1323 and 1373 K (950, 1000, 1050 and 1100 °C)) and strain rates (10{sup −3}, 10{sup −2} and 10{sup −1} s{sup −1}) were used. The stress–strain relationships as a function of temperature and strain rate were successfully described on the basis of the approach proposed by Estrin, Mecking, and Bergström, together with the classical Avrami equation and the conventional hyperbolic sine function. The analysis of the modeling parameters of the hot flow curves shows that boron additions to A-UHSS play a major role in softening mechanisms rather than on hardening. The peak stress (σ{sub p}) and steady-state stress (σ{sub ss}) values show a decreasing trend with increasing boron content, which indicates that boron additions promote a solid solution softening effect additional to that produced by DRX. The time for 50% recrystallization (t{sub 50%}) tends to increase with boron additions, revealing that boron additions cause a delay of the DRX kinetics during hot deformation. Similarly, the presence of boron in the steel decreases the apparent activation energy for recrystallization (Q{sub t}), indicating that boron additions accelerate the onset of DRX. The constitutive equations developed in this way provided an excellent description of the experimental hot flow curves.

  12. Modeling of the hot flow behavior of advanced ultra-high strength steels (A-UHSS) microalloyed with boron

    International Nuclear Information System (INIS)

    Mejía, I.; Altamirano, G.; Bedolla-Jacuinde, A.; Cabrera, J.M.

    2014-01-01

    In this research work, modeling of the hot flow behavior was carried out in a low carbon advanced ultra-high strength steels (A-UHSS) microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm). For this purpose, experimental stress–strain data of uniaxial hot-compression tests over a wide range of temperatures (1223, 1273, 1323 and 1373 K (950, 1000, 1050 and 1100 °C)) and strain rates (10 −3 , 10 −2 and 10 −1 s −1 ) were used. The stress–strain relationships as a function of temperature and strain rate were successfully described on the basis of the approach proposed by Estrin, Mecking, and Bergström, together with the classical Avrami equation and the conventional hyperbolic sine function. The analysis of the modeling parameters of the hot flow curves shows that boron additions to A-UHSS play a major role in softening mechanisms rather than on hardening. The peak stress (σ p ) and steady-state stress (σ ss ) values show a decreasing trend with increasing boron content, which indicates that boron additions promote a solid solution softening effect additional to that produced by DRX. The time for 50% recrystallization (t 50% ) tends to increase with boron additions, revealing that boron additions cause a delay of the DRX kinetics during hot deformation. Similarly, the presence of boron in the steel decreases the apparent activation energy for recrystallization (Q t ), indicating that boron additions accelerate the onset of DRX. The constitutive equations developed in this way provided an excellent description of the experimental hot flow curves

  13. Landscape moderation of biodiversity patterns and processes - eight hypotheses

    NARCIS (Netherlands)

    Tscharntke, T.; Tylianakis, J.M.; Rand, T.A.; Didham, R.K.; Fahrig, L.; Batary, P.; Bengtsson, J.; Clough, Y.; Crist, T.O.; Dormann, C.; Ewers, R.M.; Frund, J.; Holt, R.D.; Holzschuh, A.; Klein, A.M.; Kleijn, D.; Kremen, C.; Landis, D.A.; Laurance, W.F.; Lindenmayer, D.B.; Scherber, C.; Sodhi, N.; Steffan-Dewenter, I.; Thies, C.; Putten, van der W.H.; Westphal, C.

    2012-01-01

    Understanding how landscape characteristics affect biodiversity patterns and ecological processes at local and landscape scales is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest eight hypotheses, which

  14. Twelve testable hypotheses on the geobiology of weathering

    Science.gov (United States)

    S.L. Brantley; J.P. Megonigal; F.N. Scatena; Z. Balogh-Brunstad; R.T. Barnes; M.A. Bruns; P. van Cappelen; K. Dontsova; H.E. Hartnett; A.S. Hartshorn; A. Heimsath; E. Herndon; L. Jin; C.K. Keller; J.R. Leake; W.H. McDowell; F.C. Meinzer; T.J. Mozdzer; S. Petsch; J. Pett-Ridge; K.S. Pretziger; P.A. Raymond; C.S. Riebe; K. Shumaker; A. Sutton-Grier; R. Walter; K. Yoo

    2011-01-01

    Critical Zone (CZ) research investigates the chemical, physical, and biological processes that modulate the Earth's surface. Here, we advance 12 hypotheses that must be tested to improve our understanding of the CZ: (1) Solar-to-chemical conversion of energy by plants regulates flows of carbon, water, and nutrients through plant-microbe soil networks, thereby...

  15. What Is the Problem of Ad Hoc Hypotheses?

    Science.gov (United States)

    Bamford, Greg

    1999-01-01

    Philosophers' attempts to convincingly explicate the received view of an ad hoc hypothesis--that it accounts for only the observations it was designed to account for--have been unsuccessful. Familiar and firmer criteria for evaluating the hypotheses or modified theories so classified are characteristically available. Contains 41 references.…

  16. Editorial: hypotheses about protein folding - the proteomic code and wonderfolds

    Directory of Open Access Journals (Sweden)

    Agutter Paul S

    2009-12-01

    Full Text Available Abstract Theoretical biology journals can contribute in many ways to the progress of knowledge. They are particularly well-placed to encourage dialogue and debate about hypotheses addressing problematical areas of research. An online journal provides an especially useful forum for such debate because of the option of posting comments within days of the publication of a contentious article.

  17. Toward Valid Measurement of Stephen Pepper's World Hypotheses.

    Science.gov (United States)

    Johnson, John A.

    Two measures of the "world hypotheses" of Stephen Pepper were mailed to 100 sociobiologists, 87 behaviorists, 79 personality psychologists, and 45 human developmentalists. The World Hypothesis Scale (WHS) was designed to measure Pepper's four world views: (1) formism; (2) mechanism; (3) organicism; and (4) contextualism. The…

  18. Cancer stem cell hypotheses: Impact on modern molecular

    Indian Academy of Sciences (India)

    basis for the so-called cancer stem cell (CSC) hypotheses. The first exact proof of CSC ... or less equal ability for tumour regeneration and repopulation. (Nowell 1976 .... Also, there are reports that the 'stemness' (stem-like properties) of brain.

  19. Data Collection and Analysis of Moisture and Soil Strength Information for Validation of New State-of-the-Ground Models

    National Research Council Canada - National Science Library

    Mason, George

    2003-01-01

    .... Data collection teams were sent to the site intermittently to collect soil moisture, soil strength, and other related soils data for calibration with the weather station probes and support of input...

  20. Causes of bat fatalities at wind turbines: Hypotheses and predictions

    Science.gov (United States)

    Cryan, P.M.; Barclay, R.M.R.

    2009-01-01

    Thousands of industrial-scale wind turbines are being built across the world each year to meet the growing demand for sustainable energy. Bats of certain species are dying at wind turbines in unprecedented numbers. Species of bats consistently affected by turbines tend to be those that rely on trees as roosts and most migrate long distances. Although considerable progress has been made in recent years toward better understanding the problem, the causes of bat fatalities at turbines remain unclear. In this synthesis, we review hypothesized causes of bat fatalities at turbines. Hypotheses of cause fall into 2 general categoriesproximate and ultimate. Proximate causes explain the direct means by which bats die at turbines and include collision with towers and rotating blades, and barotrauma. Ultimate causes explain why bats come close to turbines and include 3 general types: random collisions, coincidental collisions, and collisions that result from attraction of bats to turbines. The random collision hypothesis posits that interactions between bats and turbines are random events and that fatalities are representative of the bats present at a site. Coincidental hypotheses posit that certain aspects of bat distribution or behavior put them at risk of collision and include aggregation during migration and seasonal increases in flight activity associated with feeding or mating. A surprising number of attraction hypotheses suggest that bats might be attracted to turbines out of curiosity, misperception, or as potential feeding, roosting, flocking, and mating opportunities. Identifying, prioritizing, and testing hypothesized causes of bat collisions with wind turbines are vital steps toward developing practical solutions to the problem. ?? 2009 American Society of Mammalogists.

  1. Attitude Strength.

    Science.gov (United States)

    Howe, Lauren C; Krosnick, Jon A

    2017-01-03

    Attitude strength has been the focus of a huge volume of research in psychology and related sciences for decades. The insights offered by this literature have tremendous value for understanding attitude functioning and structure and for the effective application of the attitude concept in applied settings. This is the first Annual Review of Psychology article on the topic, and it offers a review of theory and evidence regarding one of the most researched strength-related attitude features: attitude importance. Personal importance is attached to an attitude when the attitude is perceived to be relevant to self-interest, social identification with reference groups or reference individuals, and values. Attaching personal importance to an attitude causes crystallizing of attitudes (via enhanced resistance to change), effortful gathering and processing of relevant information, accumulation of a large store of well-organized relevant information in long-term memory, enhanced attitude extremity and accessibility, enhanced attitude impact on the regulation of interpersonal attraction, energizing of emotional reactions, and enhanced impact of attitudes on behavioral intentions and action. Thus, important attitudes are real and consequential psychological forces, and their study offers opportunities for addressing behavioral change.

  2. Source strength and dispersion of CO2 releases from high-pressure pipelines: CFD model using real gas equation of state

    International Nuclear Information System (INIS)

    Liu, Xiong; Godbole, Ajit; Lu, Cheng; Michal, Guillaume; Venton, Philip

    2014-01-01

    Highlights: • Validated CFD models for decompression and dispersion of CO 2 releases from pipelines. • Incorporation of real gas EOS into CFD code for source strength estimation. • Demonstration of better performance of SST k–ω turbulence model for jet flow. • Demonstration of better performance of real gas EOS compared to ideal gas EOS. • Demonstration of superiority of CFD models over a commercial risk assessment package. - Abstract: Transportation of CO 2 in high-pressure pipelines forms a crucial link in the ever-increasing application of Carbon Capture and Storage (CCS) technologies. An unplanned release of CO 2 from a pipeline presents a risk to human and animal populations and the environment. Therefore it is very important to develop a deeper understanding of the atmospheric dispersion of CO 2 before the deployment of CO 2 pipelines, to allow the appropriate safety precautions to be taken. This paper presents a two-stage Computational Fluid Dynamics (CFD) study developed (1) to estimate the source strength, and (2) to simulate the subsequent dispersion of CO 2 in the atmosphere, using the source strength estimated in stage (1). The Peng–Robinson (PR) EOS was incorporated into the CFD code. This enabled accurate modelling of the CO 2 jet to achieve more precise source strength estimates. The two-stage simulation approach also resulted in a reduction in the overall computing time. The CFD models were validated against experimental results from the British Petroleum (BP) CO 2 dispersion trials, and also against results produced by the risk management package Phast. Compared with the measurements, the CFD simulation results showed good agreement in both source strength and dispersion profile predictions. Furthermore, the effect of release direction on the dispersion was studied. The presented research provides a viable method for the assessment of risks associated with CCS

  3. Accounting for the Strengths of MNC Subsidiaries

    DEFF Research Database (Denmark)

    Forsgren, Mats; Pedersen, Torben; Foss, Nicolai Juul

    1999-01-01

    that organizational strength can to some extent be proxied by strength in the market place. Based on analysis of data on foreign-owned production firms in Denmark, we test three hypotheses: 1) that internal factors (capabilities, patents....) are positively related to the organizational strengths of MNC subsidiaries......This paper links up with recent work on the role of subsidiaries in multinational corporations as well as with recent work in the strategy and business network literature. We discuss the sources of organizational strengths of subsidiaries in the larger multinational corporation, and argue...

  4. Earth system model simulations show different feedback strengths of the terrestrial carbon cycle under glacial and interglacial conditions

    Directory of Open Access Journals (Sweden)

    M. Adloff

    2018-04-01

    Full Text Available In simulations with the MPI Earth System Model, we study the feedback between the terrestrial carbon cycle and atmospheric CO2 concentrations under ice age and interglacial conditions. We find different sensitivities of terrestrial carbon storage to rising CO2 concentrations in the two settings. This result is obtained by comparing the transient response of the terrestrial carbon cycle to a fast and strong atmospheric CO2 concentration increase (roughly 900 ppm in Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP-type simulations starting from climates representing the Last Glacial Maximum (LGM and pre-industrial times (PI. In this set-up we disentangle terrestrial contributions to the feedback from the carbon-concentration effect, acting biogeochemically via enhanced photosynthetic productivity when CO2 concentrations increase, and the carbon–climate effect, which affects the carbon cycle via greenhouse warming. We find that the carbon-concentration effect is larger under LGM than PI conditions because photosynthetic productivity is more sensitive when starting from the lower, glacial CO2 concentration and CO2 fertilization saturates later. This leads to a larger productivity increase in the LGM experiment. Concerning the carbon–climate effect, it is the PI experiment in which land carbon responds more sensitively to the warming under rising CO2 because at the already initially higher temperatures, tropical plant productivity deteriorates more strongly and extratropical carbon is respired more effectively. Consequently, land carbon losses increase faster in the PI than in the LGM case. Separating the carbon–climate and carbon-concentration effects, we find that they are almost additive for our model set-up; i.e. their synergy is small in the global sum of carbon changes. Together, the two effects result in an overall strength of the terrestrial carbon cycle feedback that is almost twice as large in the LGM experiment

  5. Earth system model simulations show different feedback strengths of the terrestrial carbon cycle under glacial and interglacial conditions

    Science.gov (United States)

    Adloff, Markus; Reick, Christian H.; Claussen, Martin

    2018-04-01

    In simulations with the MPI Earth System Model, we study the feedback between the terrestrial carbon cycle and atmospheric CO2 concentrations under ice age and interglacial conditions. We find different sensitivities of terrestrial carbon storage to rising CO2 concentrations in the two settings. This result is obtained by comparing the transient response of the terrestrial carbon cycle to a fast and strong atmospheric CO2 concentration increase (roughly 900 ppm) in Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP)-type simulations starting from climates representing the Last Glacial Maximum (LGM) and pre-industrial times (PI). In this set-up we disentangle terrestrial contributions to the feedback from the carbon-concentration effect, acting biogeochemically via enhanced photosynthetic productivity when CO2 concentrations increase, and the carbon-climate effect, which affects the carbon cycle via greenhouse warming. We find that the carbon-concentration effect is larger under LGM than PI conditions because photosynthetic productivity is more sensitive when starting from the lower, glacial CO2 concentration and CO2 fertilization saturates later. This leads to a larger productivity increase in the LGM experiment. Concerning the carbon-climate effect, it is the PI experiment in which land carbon responds more sensitively to the warming under rising CO2 because at the already initially higher temperatures, tropical plant productivity deteriorates more strongly and extratropical carbon is respired more effectively. Consequently, land carbon losses increase faster in the PI than in the LGM case. Separating the carbon-climate and carbon-concentration effects, we find that they are almost additive for our model set-up; i.e. their synergy is small in the global sum of carbon changes. Together, the two effects result in an overall strength of the terrestrial carbon cycle feedback that is almost twice as large in the LGM experiment as in the PI experiment

  6. Study and modeling of lanthanide(3)-L and americium(3)-L (With L = NTA, EDTA and DTPA) in high ionic strength aqueous solutions

    International Nuclear Information System (INIS)

    Rocchiccioli, F.

    2000-01-01

    The dissociation constants of NTA, EDTA, DTPA in NaCl, NaClO 4 , LiCl and LiClO 4 aqueous solutions of various ionic strengths have been gathered from the literature and from the Critical Surveys of Stability Constants. These values have been completed by a series of pKa values obtained in the same salted solution at higher ionic strengths by potentiometry involving a combined glass electrode at 25 deg C. The dependencies of the pKas versus the ionic strength have been investigated by using the Specific Interaction Theory (SIT), the parabolic model and the Pitzer model. The stability constants of complexes involving lanthanides (III), such as Nd 3+ , Eu 3+ and Lu 3+ , and americium (III), with the ligands previously mentioned in NaCl, NaClO 4 , LiCl and LiClO 4 aqueous solutions of high ionic strengths have been determined. The methods used for the determination of the stability constants for the lanthanide complexes are various: direct measurements by potentiometry when possible, UV-visible absorption spectroscopy involving Arsenazo (III) as a competitor ligand. For the actinide complexes, solvent extraction experiments have been performed. The different systems, along with the dissociation constants of several complexes in the same aqueous media, have been successfully modeled by the SIT, the parabolic method and the Pitzer method. (author)

  7. The Ras antagonist, farnesylthiosalicylic acid (FTS, decreases fibrosis and improves muscle strength in dy/dy mouse model of muscular dystrophy.

    Directory of Open Access Journals (Sweden)

    Yoram Nevo

    Full Text Available The Ras superfamily of guanosine-triphosphate (GTP-binding proteins regulates a diverse spectrum of intracellular processes involved in inflammation and fibrosis. Farnesythiosalicylic acid (FTS is a unique and potent Ras inhibitor which decreased inflammation and fibrosis in experimentally induced liver cirrhosis and ameliorated inflammatory processes in systemic lupus erythematosus, neuritis and nephritis animal models. FTS effect on Ras expression and activity, muscle strength and fibrosis was evaluated in the dy(2J/dy(2J mouse model of merosin deficient congenital muscular dystrophy. The dy(2J/dy(2J mice had significantly increased RAS expression and activity compared with the wild type mice. FTS treatment significantly decreased RAS expression and activity. In addition, phosphorylation of ERK, a Ras downstream protein, was significantly decreased following FTS treatment in the dy(2J/dy(2J mice. Clinically, FTS treated mice showed significant improvement in hind limb muscle strength measured by electronic grip strength meter. Significant reduction of fibrosis was demonstrated in the treated group by quantitative Sirius Red staining and lower muscle collagen content. FTS effect was associated with significantly inhibition of both MMP-2 and MMP-9 activities. We conclude that active RAS inhibition by FTS was associated with attenuated fibrosis and improved muscle strength in the dy(2J/dy(2J mouse model of congenital muscular dystrophy.

  8. Hydrogen adsorption strength and sites in the metal organic framework MOF5: Comparing experiment and model calculations

    Science.gov (United States)

    Mulder, F. M.; Dingemans, T. J.; Schimmel, H. G.; Ramirez-Cuesta, A. J.; Kearley, G. J.

    2008-07-01

    Hydrogen adsorption in porous, high surface area, and stable metal organic frameworks (MOF's) appears a novel route towards hydrogen storage materials [N.L. Rosi, J. Eckert, M. Eddaoudi, D.T. Vodak, J. Kim, M. O'Keeffe, O.M. Yaghi, Science 300 (2003) 1127; J.L.C. Rowsell, A.R. Millward, K. Sung Park, O.M. Yaghi, J. Am. Chem. Soc. 126 (2004) 5666; G. Ferey, M. Latroche, C. Serre, F. Millange, T. Loiseau, A. Percheron-Guegan, Chem. Commun. (2003) 2976; T. Loiseau, C. Serre, C. Huguenard, G. Fink, F. Taulelle, M. Henry, T. Bataille, G. Férey, Chem. Eur. J. 10 (2004) 1373]. A prerequisite for such materials is sufficient adsorption interaction strength for hydrogen adsorbed on the adsorption sites of the material because this facilitates successful operation under moderate temperature and pressure conditions. Here we report detailed information on the geometry of the hydrogen adsorption sites, based on the analysis of inelastic neutron spectroscopy (INS). The adsorption energies for the metal organic framework MOF5 equal about 800 K for part of the different sites, which is significantly higher than for nanoporous carbon materials (˜550 K) [H.G. Schimmel, G.J. Kearley, M.G. Nijkamp, C.T. Visser, K.P. de Jong, F.M. Mulder, Chem. Eur. J. 9 (2003) 4764], and is in agreement with what is found in first principles calculations [T. Sagara, J. Klassen, E. Ganz, J. Chem. Phys. 121 (2004) 12543; F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113]. Assignments of the INS spectra is realized using comparison with independently published model calculations [F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113] and structural data [T. Yildirim, M.R. Hartman, Phys. Rev. Lett. 95 (2005) 215504].

  9. Kolmogorov's refined similarity hypotheses for turbulence and general stochastic processes

    International Nuclear Information System (INIS)

    Stolovitzky, G.; Sreenivasan, K.R.

    1994-01-01

    Kolmogorov's refined similarity hypotheses are shown to hold true for a variety of stochastic processes besides high-Reynolds-number turbulent flows, for which they were originally proposed. In particular, just as hypothesized for turbulence, there exists a variable V whose probability density function attains a universal form. Analytical expressions for the probability density function of V are obtained for Brownian motion as well as for the general case of fractional Brownian motion---the latter under some mild assumptions justified a posteriori. The properties of V for the case of antipersistent fractional Brownian motion with the Hurst exponent of 1/3 are similar in many details to those of high-Reynolds-number turbulence in atmospheric boundary layers a few meters above the ground. The one conspicuous difference between turbulence and the antipersistent fractional Brownian motion is that the latter does not possess the required skewness. Broad implications of these results are discussed

  10. A survey of etiologic hypotheses among testicular cancer researchers

    DEFF Research Database (Denmark)

    Stang, A; Trabert, B; Rusner, C

    2015-01-01

    Basic research results can provide new ideas and hypotheses to be examined in epidemiological studies. We conducted a survey among testicular cancer researchers on hypotheses concerning the etiology of this malignancy. All researchers on the mailing list of Copenhagen Testis Cancer Workshops...... and corresponding authors of PubMed-indexed articles identified by the search term 'testicular cancer' and published within 10 years (in total 2750 recipients) were invited to respond to an e-mail-based survey. Participants of the 8th Copenhagen Testis Cancer Workshop in May 2014 were subsequently asked to rate...... that scored as most plausible. We also present plans for improving the survey that may be repeated at a next international meeting of experts in testicular cancer. Overall 52 of 99 (53%) registered participants of the 8th Copenhagen Testis Cancer Workshop submitted the plausibility rating form. Fourteen of 27...

  11. Explanatory hypotheses formation and the anomalous β spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Gauderis, Tjerk [Centre for Logic and Philosophy of Science, Ghent University (Belgium)

    2013-07-01

    Between 1928 and 1934, a persevering anomaly mystified the physics community: while alpha decay behaved perfectly according to the new quantum mechanics, the energy of electrons emitted in beta decay displayed a broad continuous spectrum. This puzzle invoked a lively debate among the most established physicists at the time. But the curious thing was that they all suggested hypotheses of very different formal types: Rutherford and Chadwick thought of varying internal energies, Bohr suggested to restrict the energy conservation principle, Heisenberg tinkered with a new quantization of space, and Pauli suggested the existence of a new elementary particle - all these hypotheses being radical and highly controversial. In physics, an anomalous experimental result can trigger the formation of formally very different hypotheses. A scientist confronted with such a result has no strict guidelines to help her decide whether she should explain this result by withdrawing or adapting a constraint (e.g. a law) of the current theory, or by presupposing the existence of a hitherto unobserved entity (e.g. a particle) that makes the anomaly fit within that theory. In this talk I aim to gain some insights how scientists make this choice, by examining in the above case study how the choice of the various mentioned physicists depended on their previous experiences and their specific perception of the problem.

  12. How the mainstream limits the spreading of alternative hypotheses

    Science.gov (United States)

    Kalenda, Pavel

    2014-05-01

    that prof. Djuric had tried for more than 10 years to publish this article in various peer-reviewed journals. So, prof. Djuric got into the official book (list) of "scientific dissidents" among hundreds of other professors and doctors of science (De Climont 2012). These "scientific dissidents" do not have access to established journals and may possibly publish privately or at best on the web in marginal journals whose list was published by De Climont (2012). Such a marginal journal in the field of geophysics and geology is New Concepts in Global Tectonics. This journal has been established because the current hypothesis about the movement of the continents due to convection currents in the mantle becomes under the weight of new observation quite untenable. 4) Scientific consensus History has known many hypotheses that were accepted as proven truth but later, in the light of new knowledge, they completely failed. - No one has the right to decide which scientific hypotheses will be accepted and which will not get into print. Perhaps the worst situation is in climatology (due to global effects and impacts), when the plenary session of IPCC consensually stated that the current global warming was mainly due to the human activity. References De Climont, J. (2012): The worldwide list of dissident scientists. http://astrojan.hostei.com/droa.htm. Djurič, J. (2006): Unification Of Gravitation And Electromagnetism. http://jovandjuric.tripod.com/ David H. Douglass, John R. Christy, Benjamin D. Pearson and S. Fred Singer (2007): A comparison of tropical temperature trends with model predictions. International Journal of Climatology, Volume 28, Issue 13, 15 November 2008, Pages: 1693-1701. http://onlinelibrary.wiley.com/doi/10.1002/joc.1651/pdf. Einstein, A. : List of scientific publications by Albert Einstein. /wiki/List_of_scientific_publications_by_Albert_Einstein. Kolínský, P., Valenta, J. and Gaždová, R. (2012): Seismicity, groundwater level variations and earth tides in

  13. Development of working hypotheses linking management of the Missouri River to population dynamics of Scaphirhynchus albus (pallid sturgeon)

    Science.gov (United States)

    Jacobson, Robert B.; Parsley, Michael J.; Annis, Mandy L.; Colvin, Michael E.; Welker, Timothy L.; James, Daniel A.

    2016-01-20

    This report documents a process of filtering of hypotheses that relate Missouri River Scaphirhynchus albus (pallid sturgeon) population dynamics to management actions including flow alterations, channel reconfigurations, and pallid sturgeon population augmentation. The filtering process was a partnership among U.S. Geological Survey, U.S. Army Corps of Engineers, and U.S. Fish and Wildlife Service to contribute to the Missouri River Recovery Management Plan process. The objective of the filtering process was to produce a set of hypotheses with high relevance to pallid sturgeon population dynamics and decision making on the Missouri River. The Missouri River Pallid Sturgeon Effects Analysis team filtered hundreds of potential hypotheses implicit in conceptual ecological models to develop a set of 40 candidate dominant hypotheses that were identified by experts as being important in pallid sturgeon population dynamics. Using a modified Delphi process and additional expert opinion, the team reduced this set of hypotheses to 23 working dominant hypotheses. We then matched the 23 hypotheses with management actions that could influence the biotic outcomes, resulting in as many as 176 potential effects between management actions and pallid sturgeon in the Missouri River. This number was consolidated to a candidate set of 53 working management hypotheses because some management actions applied to multiple life stages of the pallid sturgeon. We used an additional round of expert surveys to identify a set of 30 working management hypotheses. Finally, the set of working management hypotheses was filtered by the U.S. Army Corps of Engineers, Missouri River Recovery Program for actions that were within the agency’s authority and jurisdiction. This round resulted in a set of 21 hypotheses for initial modeling of linkages from management to pallid sturgeon population responses.

  14. Analysis of responsive characteristics of ionic-strength-sensitive hydrogel with consideration of effect of equilibrium constant by a chemo-electro-mechanical model.

    Science.gov (United States)

    Li, Hua; Lai, Fukun; Luo, Rongmo

    2009-11-17

    A multiphysics model is presented in this paper for analysis of the influence of various equilibrium constants on the smart hydrogel responsive to the ionic strength of environmental solution, and termed the multieffect-coupling ionic-strength stimulus (MECis) model. The model is characterized by a set of partial differential governing equations by consideration of the mass and momentum conservations of the system and coupled chemical, electrical, and mechanical multienergy domains. The Nernst-Planck equations are derived by the mass conservation of the ionic species in both the interstitial fluid of the hydrogel and the surrounding solution. The binding reaction between the fixed charge groups of the hydrogel and the mobile ions in the solution is described by the fixed charge equation, which is based on the Langmuir monolayer theory. As an important effect for the binding reaction, the equilibrium constant is incorporated into the fixed charge equation. The kinetics of the hydrogel swelling/deswelling is illustrated by the mechanical equation, based on the law of momentum conservation for the solid polymeric networks matrix within the hydrogel. The MECis model is examined by comparison of the numerical simulations and experiments from open literature. The analysis of the influence of different equilibrium constants on the responsive characteristics of the ionic-strength-sensitive hydrogel is carried out with detailed discussion.

  15. Modelling and Predicting the Breaking Strength and Mass Irregularity of Cotton Rotor-Spun Yarns Containing Cotton Fiber Recovered from Ginning Process by Using Artificial Neural Network Algorithm

    Directory of Open Access Journals (Sweden)

    Mohsen Shanbeh

    2011-01-01

    Full Text Available One of the main methods to reduce the production costs is waste recycling which is the most important challenge for the future. Cotton wastes collected from ginning process have desirable properties which could be used during spinning process. The purpose of this study was to develop predictive models of breaking strength and mass irregularity (CV% of cotton waste rotor-spun yarns containing cotton waste collected from ginning process by using the artificial neural network trained with backpropagation algorithm. Artificial neural network models have been developed based on rotor diameter, rotor speed, navel type, opener roller speed, ginning waste proportion and yarn linear density as input parameters. The parameters of artificial neural network model, namely, learning, and momentum rate, number of hidden layers and number of hidden processing elements (neurons were optimized to get the best predictive models. The findings showed that the breaking strength and mass irregularity of rotor spun yarns could be predicted satisfactorily by artificial neural network. The maximum error in predicting the breaking strength and mass irregularity of testing data was 8.34% and 6.65%, respectively.

  16. Application of Meta-Heuristic Hybrid Artificial Intelligence Techniques for Modeling of Bonding Strength of Plywood Panels

    Directory of Open Access Journals (Sweden)

    Cenk Demirkır

    2014-04-01

    Full Text Available Plywood, which is one of the most important wood based panels, has many usage areas changing from traffic signs to building constructions in many countries. It is known that the high quality plywood panel manufacturing has been achieved with a good bonding under the optimum pressure conditions depending on adhesive type. This is a study of determining the using possibilities of modern meta-heuristic hybrid artificial intelligence techniques such as IKE and AANN methods for prediction of bonding strength of plywood panels. This study has composed of two main parts as experimental and analytical. Scots pine, maritime pine and European black pine logs were used as wood species. The pine veneers peeled at 32°C and 50°C were dried at 110°C, 140°C and 160°C temperatures. Phenol formaldehyde and melamine urea formaldehyde resins were used as adhesive types. EN 314-1 standard was used to determine the bonding shear strength values of plywood panels in experimental part of this study. Then the intuitive k-nearest neighbor estimator (IKE and adaptive artificial neural network (AANN were used to estimate bonding strength of plywood panels. The best estimation performance was obtained from MA metric for k-value=10. The most effective factor on bonding strength was determined as adhesive type. Error rates were determined less than 5% for both of the IKE and AANN. It may be recommended that proposed methods could be used in applying to estimation of bonding strength values of plywood panels.

  17. Comparison of different models for ground-level atmospheric turbulence strength (C(n)(2)) prediction with a new model according to local weather data for FSO applications.

    Science.gov (United States)

    Arockia Bazil Raj, A; Arputha Vijaya Selvi, J; Durairaj, S

    2015-02-01

    Atmospheric parameters strongly affect the performance of free-space optical communication (FSOC) systems when the optical wave is propagating through the inhomogeneous turbulence transmission medium. Developing a model to get an accurate prediction of the atmospheric turbulence strength (C(n)(2)) according to meteorological parameters (weather data) becomes significant to understand the behavior of the FSOC channel during different seasons. The construction of a dedicated free-space optical link for the range of 0.5 km at an altitude of 15.25 m built at Thanjavur (Tamil Nadu) is described in this paper. The power level and beam centroid information of the received signal are measured continuously with weather data at the same time using an optoelectronic assembly and the developed weather station, respectively, and are recorded in a data-logging computer. Existing models that exhibit relatively fewer prediction errors are briefed and are selected for comparative analysis. Measured weather data (as input factors) and C(n)(2) (as a response factor) of size [177,147×4] are used for linear regression analysis and to design mathematical models more suitable in the test field. Along with the model formulation methodologies, we have presented the contributions of the input factors' individual and combined effects on the response surface and the coefficient of determination (R(2)) estimated using analysis of variance tools. An R(2) value of 98.93% is obtained using the new model, model equation V, from a confirmatory test conducted with a testing data set of size [2000×4]. In addition, the prediction accuracies of the selected and the new models are investigated during different seasons in a one-year period using the statistics of day, week-averaged, month-averaged, and seasonal-averaged diurnal Cn2 profiles, and are verified in terms of the sum of absolute error (SAE). A Cn2 prediction maximum average SAE of 2.3×10(-13)  m(-2/3) is achieved using the new model in

  18. Hypothesized eye movements of neurolinguistic programming: a statistical artifact.

    Science.gov (United States)

    Farmer, A; Rooney, R; Cunningham, J R

    1985-12-01

    Neurolinguistic programming's hypothesized eye-movements were measured independently from videotapes of 30 subjects, aged 15 to 76 yr., who were asked to recall visual pictures, recorded audio sounds, and textural objects. chi 2 indicated that subjects' responses were significantly different from those predicted. When chi 2 comparisons were weighted by number of eye positions assigned to each modality (3 visual, 3 auditory, 1 kinesthetic), subjects' responses did not differ significantly from the expected pattern. These data indicate that the eye-movement hypothesis may represent randomly occurring rather than sensory-modality-related positions.

  19. Evaluation of the interfacial shear strength and residual stress of TiAlN coating on ZIRLO™ fuel cladding using a modified shear-lag model approach

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y., E-mail: troy.liu@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Bhamji, I., E-mail: imran.bhamji@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Withers, P.J., E-mail: p.j.withers@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Wolfe, D.E., E-mail: dew125@arl.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Motta, A.T., E-mail: atmnuc@engr.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Preuss, M., E-mail: michael.preuss@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom)

    2015-11-15

    This paper investigates the residual stresses and interfacial shear strength of a TiAlN coating on Zr–Nb–Sn–Fe alloy (ZIRLO™) substrate designed to improve corrosion resistance of fuel cladding used in water-cooled nuclear reactors, both during normal and exceptional conditions, e.g. a loss of coolant event (LOCA). The distribution and maximum value of the interfacial shear strength has been estimated using a modified shear-lag model. The parameters critical to this analysis were determined experimentally. From these input parameters the interfacial shear strength between the TiAlN coating and ZIRLO™ substrate was inferred to be around 120 MPa. It is worth noting that the apparent strength of the coating is high (∼3.4 GPa). However, this is predominantly due to the large compressive residuals stress (3 GPa in compression), which must be overcome for the coating to fail in tension, which happens at a load just 150 MPa in excess of this.

  20. The relationship between compressive strength and flexural strength of pavement geopolymer grouting material

    Science.gov (United States)

    Zhang, L.; Han, X. X.; Ge, J.; Wang, C. H.

    2018-01-01

    To determine the relationship between compressive strength and flexural strength of pavement geopolymer grouting material, 20 groups of geopolymer grouting materials were prepared, the compressive strength and flexural strength were determined by mechanical properties test. On the basis of excluding the abnormal values through boxplot, the results show that, the compressive strength test results were normal, but there were two mild outliers in 7days flexural strength test. The compressive strength and flexural strength were linearly fitted by SPSS, six regression models were obtained by linear fitting of compressive strength and flexural strength. The linear relationship between compressive strength and flexural strength can be better expressed by the cubic curve model, and the correlation coefficient was 0.842.

  1. Political Participation Online: The Replacement and the Mobilisation Hypotheses Revisited

    DEFF Research Database (Denmark)

    Jensen, Jakob Linaa

    2013-01-01

    This article discusses the state of political participation online more than ten years after the Internet’s great popular breakthrough as an everyday medium. Denmark is used as a case study to critically re-examine the frequently discussed replacement and mobilisation hypotheses on behalf of the ...... participation, efficacy and social capital seem to have less impact on online political participation. In the end, these findings are related to more overall discussions on the democratising potential of the Internet.......This article discusses the state of political participation online more than ten years after the Internet’s great popular breakthrough as an everyday medium. Denmark is used as a case study to critically re-examine the frequently discussed replacement and mobilisation hypotheses on behalf...... of the Internet. The pure replacement hypothesis is rejected. Instead, it is found that the Internet still supplements rather than replaces other media, even among heavy Internet users. The Internet is one among several media used by ‘media omnivores’, and political participation online supplements rather than...

  2. Seed dormancy and germination - Emerging mechanisms and new hypotheses

    Directory of Open Access Journals (Sweden)

    Hiroyuki eNonogaki

    2014-05-01

    Full Text Available Seed dormancy has played a significant role in adaptation and evolution of seed plants. While its biological significance is clear, molecular mechanisms underlying seed dormancy induction, maintenance and alleviation still remain elusive. Intensive efforts have been made to investigate gibberellin and abscisic acid metabolism in seeds, which greatly contributed to the current understanding of seed dormancy mechanisms. Other mechanisms, which might be independent of hormones, or specific to the seed dormancy pathway, are also emerging from genetic analysis of seed dormancy mutants. These studies suggest that chromatin remodeling through histone ubiquitination, methylation and acetylation, which could lead to transcription elongation or gene silencing, may play a significant role in seed dormancy regulation. Small interfering RNA and/or long non-coding RNA might be a trigger of epigenetic changes at the seed dormancy or germination loci, such as DELAY OF GERMINATION1. While new mechanisms are emerging from genetic studies of seed dormancy, novel hypotheses are also generated from seed germination study with high throughput gene expression analysis. Recent studies on tissue-specific gene expression in tomato and Arabidopsis seeds, which suggested possible mechanosensing in the regulatory mechanisms, advanced our understanding of embryo-endosperm interaction and have potential to re-draw the traditional hypotheses or integrate them into a comprehensive scheme. The progress in basic seed science will enable knowledge translation, another frontier of research to be expanded for food and fuel production.

  3. Transfer factor - hypotheses for its structure and function.

    Science.gov (United States)

    Shifrine, M; Scibienski, R

    1975-01-01

    Transfer factor (TF) is a dialyzable extract from primed lymphocytes that is able to transfer specific delayed hypersensitivity from one animal to another. On the basis of available data we suggest that TF is a polypeptide with a molecular weight below 15,000 daltons. We hypothesize that TF is the variable light or heavy chain domain of immunoglobulin: such a molecule conforms with the accepted properties of TF and also has the necessary specificity requirements. We also hypothesize that TF is part of a receptor site. beta-2-microglobulin, a molecule that is an integral part of cell surfaces, could be the anchor for TF. beta-2-microglobulin has homologies with the constant portion of immunoglobulin light or heavy chain and thus would combine with the variable domain (TF) to form a complete receptor site for a specific antigen. The properties of TF suggest its mode of action, which is discussed in detail in the text. The biologic advantages of TF is its ability to confer immediate (immunologie specific) protection while the 'normal' immune response develops.

  4. Experienced physicians benefit from analyzing initial diagnostic hypotheses

    Science.gov (United States)

    Bass, Adam; Geddes, Colin; Wright, Bruce; Coderre, Sylvain; Rikers, Remy; McLaughlin, Kevin

    2013-01-01

    Background Most incorrect diagnoses involve at least one cognitive error, of which premature closure is the most prevalent. While metacognitive strategies can mitigate premature closure in inexperienced learners, these are rarely studied in experienced physicians. Our objective here was to evaluate the effect of analytic information processing on diagnostic performance of nephrologists and nephrology residents. Methods We asked nine nephrologists and six nephrology residents at the University of Calgary and Glasgow University to diagnose ten nephrology cases. We provided presenting features along with contextual information, after which we asked for an initial diagnosis. We then primed participants to use either hypothetico-deductive reasoning or scheme-inductive reasoning to analyze the remaining case data and generate a final diagnosis. Results After analyzing initial hypotheses, both nephrologists and residents improved the accuracy of final diagnoses (31.1% vs. 65.6%, p inductive reasoning (odds ratio [95% confidence interval] 5.69 [1.59, 20.33], p = 0.07), whereas the performance of experienced nephrologists did not differ between strategies (odds ratio 0.57 [0.23, 1.39], p = 0.20). Discussion Experienced nephrologists and nephrology residents can improve their performance by analyzing initial diagnostic hypotheses. The explanation of the interaction between experience and the effect of different reasoning strategies is unclear, but may relate to preferences in reasoning strategy, or the changes in knowledge structure with experience. PMID:26451203

  5. Reinterpretation of searches for supersymmetry in models with variable $R$-parity-violating coupling strength and long-lived $R$-hadrons

    CERN Document Server

    The ATLAS collaboration

    2018-01-01

    A selection of ATLAS searches for supersymmetry (SUSY), optimized for $R$-parity-conserving and $R$-parity-violating (RPV) models, are reinterpreted in SUSY models with variable RPV-coupling strength. Depending on the coupling strength the lightest supersymmetric particle is stable at collider scales, is long-lived and decays away from the interaction point, or decays promptly. Limits are placed on simplified models of pair-produced gluinos decaying to final states enhanced or depleted with top quarks, and models of pair-produced top squarks. In a model of pair-produced gluinos decaying to final states enhanced with top quarks, a lower limit of 1.8 TeV on the gluino mass is set at 95% confidence level regardless of the RPV coupling value. Limits are set on models of gluino pair production decaying to light-flavor quarks, and models of top squark production. Limits are also placed on meta-stable gluinos decaying within the detector volume.

  6. On the importance of body posture and skin modelling with respect to in situ electric field strengths in magnetic field exposure scenarios

    Science.gov (United States)

    Schmid, Gernot; Hirtl, Rene

    2016-06-01

    The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the

  7. Bond strength of masonry

    NARCIS (Netherlands)

    Pluijm, van der R.; Vermeltfoort, A.Th.

    1992-01-01

    Bond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished: - tensile bond strength, - shear (and torsional) bond strength, - flexural bond strength. In this contribution the behaviour and strength of masonry in deformation controlled uniaxial

  8. UO2 leaching and radionuclide release modelling under high and low ionic strength solution and oxidation conditions

    International Nuclear Information System (INIS)

    1995-01-01

    In this work, the UO 2 dissolution under oxidizing conditions has been studied in order to compare these results to those obtained with spent fuel. Two different leaching solutions have been used, one with a high ionic strength trying to simulate the conditions expected in a saline repository and the other at low ionic strength much appropriate to granitic environments. In both cases, the dissolution has been studied studied as a function of pH, redox potential, oxidants, complexing agents, particle size as well as the experimental methodology. Results can be summarized as follows: a) The UO 2 dissolution is rather independent on ionic strength. b) Dissolution rates can be explained in general independent on the oxidant as: Log R=3DK [oxidant] Surface solid evolution is very important to understand the dissolution/oxidation mechanism of UO 2 . d) Under oxidizing conditions, the dissolution is H+ and HCO 3 promoted. e) In carbonate medium, both UO 2 and spent fuel dissolution rates are very similar, while in a non-complexing medium, spent fuel dissolution rate is much higher than the UO 2 one. This fact seems to indicate that radiolysis is much important non-complexing media. (Author)

  9. Assessing the skill of hydrology models at simulating the water cycle in the HJ Andrews LTER: Assumptions, strengths and weaknesses

    Science.gov (United States)

    Simulated impacts of climate on hydrology can vary greatly as a function of the scale of the input data, model assumptions, and model structure. Four models are commonly used to simulate streamflow in model assumptions, and model structure. Four models are commonly used to simu...

  10. FINITE-ELEMENT MODELING OF HOT FORMING OF BUSHES MADE FROM HIGH-STRENGTH CAST IRON WITH A GRADIENT DISTRIBUTION OF GRAPHITE INCLUSIONS OVER CROSS-SECTION

    Directory of Open Access Journals (Sweden)

    A. I. Pokrovsky

    2016-01-01

    Full Text Available Imitation modeling of direct hot extrusion of bushes made from high-strength cast iron is performed using finite-element method. The evolution of stress and strain fields during processing and the probability of crack formation are evaluated. The specific feature of the work is that during hot forming a special technique was used which permitted obtaining a gradient distribution of graphite inclusions over the cross-section of bushes. The results of modeling are used in certain technologies which are implemented in industrial practice.

  11. About hypotheses and paradigms: exploring the Discreetness-Chance Paradigm.

    Science.gov (United States)

    Kaellis, Eugene

    2006-01-01

    Hypotheses generally conform to paradigms which, over time, change, usually tardily, after they have become increasingly difficult to sustain under the impact of non-conforming evidence and alternative hypotheses, but more important, when they no longer are comfortably ensconced in the surrounding social-economic-political-cultural milieu. It is asserted that this milieu is the most important factor in shaping scientific theorizing. Some examples are cited: the rejection of the evidence that the world orbits around the sun (suspected by Pythagoras) in favor of centuries-long firm adherence to the Ptolemaic geocentric system; the early acceptance of Natural Selection in spite of its tautological essence and only conjectural supporting evidence, because it justified contemporaneous social-political ideologies as typified by, e.g., Spencer and Malthus. Economic, social, and cultural factors are cited as providing the ground, i.e., ideational substrate, for what is cited as the Discreetness-Chance Paradigm (DCP), that has increasingly dominated physics, biology, and medicine for over a century and which invokes small, discrete packets of energy/matter (quanta, genes, microorganisms, aberrant cells) functioning within an environment of statistical, not determined, causality. There is speculation on a possible paradigmatic shift from the DCP, which has fostered the proliferation, parallel with ("splitting") taxonomy, of alleged individual disease entities, their diagnoses, and, when available, their specific remedies, something particularly prominent in, e.g., psychiatry's Diagnostic and Statistical Manual, a codified compendium of alleged mental and behavioral disorders, but evident in any textbook of diagnosis and treatment of physical ailments. This presumed paradigm shift may be reflected in Western medicine, presently increasingly empirical and atomized, towards a growing acceptance of a more generalized, subject-oriented, approach to health and disease, a non

  12. Testing evolutionary hypotheses for phenotypic divergence using landscape genetics.

    Science.gov (United States)

    Funk, W Chris; Murphy, Melanie A

    2010-02-01

    Understanding the evolutionary causes of phenotypic variation among populations has long been a central theme in evolutionary biology. Several factors can influence phenotypic divergence, including geographic isolation, genetic drift, divergent natural or sexual selection, and phenotypic plasticity. But the relative importance of these factors in generating phenotypic divergence in nature is still a tantalizing and unresolved problem in evolutionary biology. The origin and maintenance of phenotypic divergence is also at the root of many ongoing debates in evolutionary biology, such as the extent to which gene flow constrains adaptive divergence (Garant et al. 2007) and the relative importance of genetic drift, natural selection, and sexual selection in initiating reproductive isolation and speciation (Coyne & Orr 2004). In this issue, Wang & Summers (2010) test the causes of one of the most fantastic examples of phenotypic divergence in nature: colour pattern divergence among populations of the strawberry poison frog (Dendrobates pumilio) in Panama and Costa Rica (Fig. 1). This study provides a beautiful example of the use of the emerging field of landscape genetics to differentiate among hypotheses for phenotypic divergence. Using landscape genetic analyses, Wang & Summers were able to reject the hypotheses that colour pattern divergence is due to isolation-by-distance (IBD) or landscape resistance. Instead, the hypothesis left standing is that colour divergence is due to divergent selection, in turn driving reproductive isolation among populations with different colour morphs. More generally, this study provides a wonderful example of how the emerging field of landscape genetics, which has primarily been applied to questions in conservation and ecology, now plays an essential role in evolutionary research.

  13. Hypotheses about geoglyphs at Nasca, Peru: new discoveries

    Directory of Open Access Journals (Sweden)

    Jaroslav Klokočník

    2016-07-01

    Full Text Available The known hypotheses about the reasons why the geoglyphs in the Nasca and Palpa region of Peru were created are many: roads/paths, rituals/ceremonials, use of hallucinogens, astronomical meaning, influence of extraterrestrials, underground water… and so on. We present a new hypothesis, formulated by J. Sonnek (first published in 2011 in the context of all previous hypotheses.1 Sonnek explains the geoglyphs as tidied work areas for the production of rope and nets, although he goes much further than Stierlin. This eccentric hypothesis now has not only experimental but also archaeological and ethnographical support, which is presented here. Geoglyphs of a special shape were discovered in the pampas; they may represent technical objects – different types of ‘rope twisters’. Following this idea, Sonnek made technical devices (using today’s materials and tested them in practice; they work perfectly, see his YouTube videos.2 In November 2012, wooden pieces, which may be the remnants of ropemaking, were collected from the pampa near the towns of Nasca and Palpa, in vicinity of these hypothetic ropemaking places. Radiocarbon testing by 14C standardized radio-carbon age according to Stuiver-Polach convention and Accelerator Mass Spectroscopy (AMS of these wood pieces shows the age to be in a wide range from Early Nasca to the 17th century (and to our epoch with a fake geoglyph, too, thus supporting (but surely not proving the new hypothesis. Moreover, in the Quechua language, the word huasca, waskha (read: uasca means a rope or cord or place where these are produced. This word is very similar to ‘nasca’.

  14. Experienced physicians benefit from analyzing initial diagnostic hypotheses

    Directory of Open Access Journals (Sweden)

    Adam Bass

    2013-03-01

    Full Text Available Background: Most incorrect diagnoses involve at least one cognitive error, of which premature closure is the most prevalent. While metacognitive strategies can mitigate premature closure in inexperienced learners, these are rarely studied in experienced physicians. Our objective here was to evaluate the effect of analytic information processing on diagnostic performance of nephrologists and nephrology residents. Methods: We asked nine nephrologists and six nephrology residents at the University of Calgary and Glasgow University to diagnose ten nephrology cases. We provided presenting features along with contextual information, after which we asked for an initial diagnosis. We then primed participants to use either hypothetico-deductive reasoning or scheme-inductive reasoning to analyze the remaining case data and generate a final diagnosis. Results: After analyzing initial hypotheses, both nephrologists and residents improved the accuracy of final diagnoses (31.1% vs. 65.6%, p < 0.001, and 40.0% vs. 70.0%, p < 0.001, respectively. We found a significant interaction between experience and analytic processing strategy (p = 0.002: nephrology residents had significantly increased odds of diagnostic success when using scheme-inductive reasoning (odds ratio [95% confidence interval] 5.69 [1.59, 20.33], p = 0.007, whereas the performance of experienced nephrologists did not differ between strategies (odds ratio 0.57 [0.23, 1.39], p = 0.2. Discussion: Experienced nephrologists and nephrology residents can improve their performance by analyzing initial diagnostic hypotheses. The explanation of the interaction between experience and the effect of different reasoning strategies is unclear, but may relate to preferences in reasoning strategy, or the changes in knowledge structure with experience.

  15. Screen-based sedentary behavior and associations with functional strength in 6-15 year-old children in the United States.

    Science.gov (United States)

    Edelson, Lisa R; Mathias, Kevin C; Fulgoni, Victor L; Karagounis, Leonidas G

    2016-02-04

    Physical strength is associated with improved health outcomes in children. Heavier children tend to have lower functional strength and mobility. Physical activity can increase children's strength, but it is unknown how different types of electronic media use impact physical strength. Data from the NHANES National Youth Fitness Survey (NNYFS) from children ages 6-15 were analyzed in this study. Regression models were conducted to determine if screen-based sedentary behaviors (television viewing time, computer/video game time) were associated with strength measures (grip, leg extensions, modified pull-ups, plank) while controlling for potential confounders including child age, sex, BMI z-score, and days per week with 60+ minutes of physical activity. Grip strength and leg extensions divided by body weight were analyzed to provide measures of relative strength together with pull-ups and plank, which require lifting the body. The results from the regression models showed the hypothesized inverse association between TV time and all strength measures. Computer time was only significantly inversely associated with the ability to do one or more pull-ups. This study shows that television viewing, but not computer/videogames, is inversely associated with measures of child strength while controlling for child characteristics and physical activity. These findings suggest that "screen time" may not be a unified construct with respect to strength outcomes and that further exploration of the potential benefits of reducing television time on children's strength and related mobility is needed.

  16. An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain.

    Science.gov (United States)

    Wahab, Siti Waznah; Bister, Dirk; Sherriff, Martyn

    2014-02-01

    This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces force delivery and tensile strength of exposed chains.

  17. Electroweak precision observables and Higgs-boson signal strengths in the Standard Model and beyond: present and future

    Energy Technology Data Exchange (ETDEWEB)

    Blas, J. de [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy); Ciuchini, M. [INFN, Sezione di Roma Tre,Via della Vasca Navale 84, I-00146 Roma (Italy); Franco, E. [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy); Mishima, S. [Theory Center, Institute of Particle and Nuclear Studies (IPNS),High Energy Accelerator Research Organization (KEK),1-1 Oho, Tsukuba, 305-0801 (Japan); Pierini, M. [CERN,Geneva (Switzerland); Reina, L. [Physics Department, Florida State University,77 Chieftan Way, Tallahassee, FL 32306-4350 (United States); Kavli Institute for Theoretical Physics, University of California,Kohn Hall, Santa Barbara, CA 93106-4030 (United States); Silvestrini, L. [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Rome (Italy)

    2016-12-27

    We present results from a state-of-the-art fit of electroweak precision observables and Higgs-boson signal-strength measurements performed using 7 and 8 TeV data from the Large Hadron Collider. Based on the HEPfit package, our study updates the traditional fit of electroweak precision observables and extends it to include Higgs-boson measurements. As a result we obtain constraints on new physics corrections to both electroweak observables and Higgs-boson couplings. We present the projected accuracy of the fit taking into account the expected sensitivities at future colliders.

  18. Optimizing gradient conditions in online comprehensive two-dimensional reversed-phase liquid chromatography by use of the linear solvent strength model

    DEFF Research Database (Denmark)

    Græsbøll, Rune; Janssen, Hans-Gerd; Christensen, Jan H.

    2017-01-01

    The linear solvent strength model was used to predict coverage in online comprehensive two-dimensional reversed-phase liquid chromatography. The prediction model uses a parallelogram to describe the separation space covered with peaks in a system with limited orthogonality. The corners of the par......The linear solvent strength model was used to predict coverage in online comprehensive two-dimensional reversed-phase liquid chromatography. The prediction model uses a parallelogram to describe the separation space covered with peaks in a system with limited orthogonality. The corners...... of the parallelogram are assumed to behave like chromatographic peaks and the position of these pseudo-compounds was predicted. A mix of 25 polycyclic aromatic compounds were used as a test. The precision of the prediction, span 0-25, was tested by varying input parameters, and was found to be acceptable with root...... factors were low, or when gradient conditions affected parameters not included in the model, e.g. second dimension gradient time affects the second dimension equilibration time. The concept shows promise as a tool for gradient optimization in online comprehensive two-dimensional liquid chromatography...

  19. Large low-energy M1 strength for ^{56,57}Fe within the nuclear shell model.

    Science.gov (United States)

    Brown, B Alex; Larsen, A C

    2014-12-19

    A strong enhancement at low γ-ray energies has recently been discovered in the γ-ray strength function of ^{56,57}Fe. In this work, we have for the first time obtained theoretical γ decay spectra for states up to ≈8  MeV in excitation for ^{56,57}Fe. We find large B(M1) values for low γ-ray energies that provide an explanation for the experimental observations. The role of mixed E2 transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high-ℓ(=f) diagonal terms are most important for the strong low-energy M1 transitions. As such types of 0ℏω transitions are expected for all nuclei, our results indicate that a low-energy M1 enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the M1 strength function at high excitation energies, with profound implications for astrophysical reaction rates.

  20. Masticatory-stress hypotheses and the supraorbital region of primates.

    Science.gov (United States)

    Hylander, W L; Picq, P G; Johnson, K R

    1991-09-01

    The purpose of this study is to test various masticatory-stress hypotheses about the evolution and function of well-developed browridges of higher primates. This was done by measuring and analyzing patterns of in vivo bone strain recorded from three-element rosette strain gages bonded to the supraorbital region and to other portions of the bony face of Macaca fascicularis and Papio anubis during mastication and incision. The magnitude and direction of the principal strains recorded support Endo's hypothesis that the supraorbital region during mastication and incision is bent in the frontal plane (Endo, 1966). Our data do not, however, support his hypothesis that the supraorbital region is bent more during incision than during mastication. The data also demonstrate that overall levels of supraorbital strain are not larger in more prognathic subjects. Most importantly, the data indicate that the supraorbital region of nonhuman catarrhines is strained very little during mastication and incision. This indicates that there is much more supraorbital bone than is necessary both to counter masticatory loads and to provide an adequate safety factor to failure for these loads. This in turn suggests that the macaque and baboon browridges can be considerably reduced in size and still maintain these required structural characteristics. Thus, our experiments provide no support whatsoever for those hypotheses that directly link browridge morphology to masticatory stress (cf. Endo, 1966; Russell, 1983, 1985). A recent review of Endo's original work indicates that this latter statement is also true for humans (Picq and Hylander, 1989). We conclude, therefore, that there is no good reason to believe that enlarged browridges in living and/or fossil primates are structural adaptations to counter intense masticatory forces. The evolution of browridge morphology in primates is best explained on the basis of factors related to the position of the brain relative to the orbits (Moss and

  1. Using Transcranial tDCS to test cognitive hypotheses

    Directory of Open Access Journals (Sweden)

    Nazbanou Nozari

    2014-04-01

    Full Text Available Transcranial Direct Current Stimulation (tDCS is used increasingly often for testing cognitive hypotheses. It is, however, often ignored that many assumptions regarding how the neural tissue reacts to stimulation have only been verified in the motor domain. Extrapolating these assumptions to the cognitive domain has a set of unique issues which, if ignored, can lead to incorrect interpretations. In this talk I will review a number of common pitfalls in using tDCS for testing a cognitive hypothesis, and discuss some solutions for better-controlled designs. I will address the following issues: 1- Making an incorrect assumption about the nature of the effect: It is often assumed that anodal stimulation has “excitatory” and cathodal stimulation has “inhibitory” effects. Results are then interpreted in light of this assumption. Obviously, if the assumption is incorrect, the interpretation of the results too will be incorrect. I will discuss how the effects of polarity can change as a function of a number of design parameters, and the dangers of making a priori assumptions about the direction of stimulation effects, especially when employing a new design. 2- Choosing an inappropriate montage: By definition, tDCS requires two electrodes, although we are often only interested in stimulating one brain region. Where the second (reference electrode is placed may not be of theoretical interest to us, but it can have serious consequences for our effects of interest. For one thing the path of the direct current changes as a function of where the reference electrode is placed. This affects the density of the current, as well as the regions that undergo stimulation. Moreover, the region directly under the reference electrode is very likely to be affected by stimulation. Therefore, sometimes the changes in behavior may be due to the unanticipated effects at the reference electrode site, as opposed to the hypothesized effects at the target electrode site

  2. Landscape moderation of biodiversity patterns and processes - eight hypotheses.

    Science.gov (United States)

    Tscharntke, Teja; Tylianakis, Jason M; Rand, Tatyana A; Didham, Raphael K; Fahrig, Lenore; Batáry, Péter; Bengtsson, Janne; Clough, Yann; Crist, Thomas O; Dormann, Carsten F; Ewers, Robert M; Fründ, Jochen; Holt, Robert D; Holzschuh, Andrea; Klein, Alexandra M; Kleijn, David; Kremen, Claire; Landis, Doug A; Laurance, William; Lindenmayer, David; Scherber, Christoph; Sodhi, Navjot; Steffan-Dewenter, Ingolf; Thies, Carsten; van der Putten, Wim H; Westphal, Catrin

    2012-08-01

    Understanding how landscape characteristics affect biodiversity patterns and ecological processes at local and landscape scales is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest eight hypotheses, which we hope will encourage more systematic research on the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. We organize the eight hypotheses under four overarching themes. Section A: 'landscape moderation of biodiversity patterns' includes (1) the landscape species pool hypothesis-the size of the landscape-wide species pool moderates local (alpha) biodiversity, and (2) the dominance of beta diversity hypothesis-landscape-moderated dissimilarity of local communities determines landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. Section B: 'landscape moderation of population dynamics' includes (3) the cross-habitat spillover hypothesis-landscape-moderated spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes and (4) the landscape-moderated concentration and dilution hypothesis-spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations with functional consequences. Section C: 'landscape moderation of functional trait selection' includes (5) the landscape-moderated functional trait selection hypothesis-landscape moderation of species trait selection shapes the functional role and trajectory of community assembly, and (6) the landscape-moderated insurance hypothesis-landscape complexity provides spatial and temporal insurance, i.e. high resilience and stability of ecological processes in changing environments. Section D: 'landscape constraints on

  3. Evaluation of Extremal Hypotheses as a Criterion to Resolve Channel Indeterminacy

    Science.gov (United States)

    Tranmer, A.

    2012-12-01

    Design criteria for river restoration and sustainable development have significantly advanced in recent decades, yet complete deterministic formulations to address channel form and sinuosity still prove elusive. Many hypotheses have been presented to ascertain the dynamic-equilibrium of a stream at both the cross sectional and reach level. These efforts to better understand the functioning of alluvial systems include regime theory, stability theory, perturbation analysis, threshold theory, reference reach comparison, downstream hydraulic geometry, and extremal hypotheses. The latter of these theories, the extremal hypothesis, is based on optimizing one variable or criterion in the alluvial system in order to find closure to the channel design problem. Currently, there is no method to directly compare the various hypotheses at the system scale, understanding of their sensitivity to the various formulae employed or consensus regarding which hypothesis is most appropriate. This study analyzed the various extremal hypotheses in as close to a pristine environment as exists (a remote part of Patagonia, Chile), in order to assess which hypothesis (or collective hypotheses) is most appropriate for channel design. Extremal hypotheses were applied in the longitudinal direction, under the assumption of a space-for-time substitution, to evaluate the geomorphic trends of a river evolving during deglaciation. The space-for-time model assumes the watershed reaches stable, dynamic-equilibrium in its lower meandering reaches and the point of equilibrium extends upstream through its braiding reaches as the watershed adapts to new climatic and environmental conditions. Extremal hypotheses applied in a downstream fashion are then expected to predict chaotic and oversized channel characteristics in the upstream reaches and trend towards a point of equilibrium (minimum/maximum of tested hypothesis). Initial findings indicate that many hypotheses predict similar geometry and sinuosity

  4. Assessment regarding the use of the computer aided analytical models in the calculus of the general strength of a ship hull

    Science.gov (United States)

    Hreniuc, V.; Hreniuc, A.; Pescaru, A.

    2017-08-01

    Solving a general strength problem of a ship hull may be done using analytical approaches which are useful to deduce the buoyancy forces distribution, the weighting forces distribution along the hull and the geometrical characteristics of the sections. These data are used to draw the free body diagrams and to compute the stresses. The general strength problems require a large amount of calculi, therefore it is interesting how a computer may be used to solve such problems. Using computer programming an engineer may conceive software instruments based on analytical approaches. However, before developing the computer code the research topic must be thoroughly analysed, in this way being reached a meta-level of understanding of the problem. The following stage is to conceive an appropriate development strategy of the original software instruments useful for the rapid development of computer aided analytical models. The geometrical characteristics of the sections may be computed using a bool algebra that operates with ‘simple’ geometrical shapes. By ‘simple’ we mean that for the according shapes we have direct calculus relations. In the set of ‘simple’ shapes we also have geometrical entities bounded by curves approximated as spline functions or as polygons. To conclude, computer programming offers the necessary support to solve general strength ship hull problems using analytical methods.

  5. Exploration of miRNA families for hypotheses generation.

    KAUST Repository

    Kamanu, T.K.

    2013-10-15

    Technological improvements have resulted in increased discovery of new microRNAs (miRNAs) and refinement and enrichment of existing miRNA families. miRNA families are important because they suggest a common sequence or structure configuration in sets of genes that hint to a shared function. Exploratory tools to enhance investigation of characteristics of miRNA families and the functions of family-specific miRNA genes are lacking. We have developed, miRNAVISA, a user-friendly web-based tool that allows customized interrogation and comparisons of miRNA families for hypotheses generation, and comparison of per-species chromosomal distribution of miRNA genes in different families. This study illustrates hypothesis generation using miRNAVISA in seven species. Our results unveil a subclass of miRNAs that may be regulated by genomic imprinting, and also suggest that some miRNA families may be species-specific, as well as chromosome- and/or strand-specific.

  6. Drug-Resistant Epilepsy: Multiple Hypotheses, Few Answers

    Directory of Open Access Journals (Sweden)

    Fei Tang

    2017-07-01

    Full Text Available Epilepsy is a common neurological disorder that affects over 70 million people worldwide. Despite the recent introduction of new antiseizure drugs (ASDs, about one-third of patients with epilepsy have seizures refractory to pharmacotherapy. Early identification of patients who will become refractory to ASDs could help direct such patients to appropriate non-pharmacological treatment, but the complexity in the temporal patterns of epilepsy could make such identification difficult. The target hypothesis and transporter hypothesis are the most cited theories trying to explain refractory epilepsy, but neither theory alone fully explains the neurobiological basis of pharmacoresistance. This review summarizes evidence for and against several major theories, including the pharmacokinetic hypothesis, neural network hypothesis, intrinsic severity hypothesis, gene variant hypothesis, target hypothesis, and transporter hypothesis. The discussion is mainly focused on the transporter hypothesis, where clinical and experimental data are discussed on multidrug transporter overexpression, substrate profiles of ASDs, mechanism of transporter upregulation, polymorphisms of transporters, and the use of transporter inhibitors. Finally, future perspectives are presented for the improvement of current hypotheses and the development of treatment strategies as guided by the current understanding of refractory epilepsy.

  7. Estimating the Proportion of True Null Hypotheses in Multiple Testing Problems

    Directory of Open Access Journals (Sweden)

    Oluyemi Oyeniran

    2016-01-01

    Full Text Available The problem of estimating the proportion, π0, of the true null hypotheses in a multiple testing problem is important in cases where large scale parallel hypotheses tests are performed independently. While the problem is a quantity of interest in its own right in applications, the estimate of π0 can be used for assessing or controlling an overall false discovery rate. In this article, we develop an innovative nonparametric maximum likelihood approach to estimate π0. The nonparametric likelihood is proposed to be restricted to multinomial models and an EM algorithm is also developed to approximate the estimate of π0. Simulation studies show that the proposed method outperforms other existing methods. Using experimental microarray datasets, we demonstrate that the new method provides satisfactory estimate in practice.

  8. NegaWatt 2011-2050 scenario - Hypotheses and method. Technical report, May 2014

    International Nuclear Information System (INIS)

    2014-05-01

    This report proposes an analysis of the negaWatt 2011 scenario. It describes in detail the methodology adopted to elaborate this prospective scenario, and presents the major part of the hypotheses which structure this scenario. A first part presents the approach and methodology (constraints, scenario, model). The second part addresses the issue of energy saving and energy efficiency through a sector-based analysis (housing and office building, transports, industrial and agricultural production). The third part studies the substitution by renewable energies through a supply analysis: energy production based on biomass, renewable energies, and fissile and fossil energies. It outlines the major role of grids in the supply-demand balance. The results of the negaWatt 2011 scenario are presented in terms of final energy, primary energies, and impact on greenhouse gas emissions. Hypotheses and results related to the different sectors (building, transports, industry and agriculture, energy production) are given in appendix

  9. Lycopene treatment against loss of bone mass, microarchitecture and strength in relation to regulatory mechanisms in a postmenopausal osteoporosis model.

    Science.gov (United States)

    Ardawi, Mohammed-Salleh M; Badawoud, Mohammed H; Hassan, Sherif M; Rouzi, Abdulrahim A; Ardawi, Jumanah M S; AlNosani, Nouf M; Qari, Mohammed H; Mousa, Shaker A

    2016-02-01

    Lycopene supplementation decreases oxidative stress and exhibits beneficial effects on bone health, but the mechanisms through which it alters bone metabolism in vivo remain unclear. The present study aims to evaluate the effects of lycopene treatment on postmenopausal osteoporosis. Six-month-old female Wistar rats (n=264) were sham-operated (SHAM) or ovariectomized (OVX). The SHAM group received oral vehicle only and the OVX rats were randomized into five groups receiving oral daily lycopene treatment (mg/kg body weight per day): 0 OVX (control), 15 OVX, 30 OVX, and 45 OVX, and one group receiving alendronate (ALN) (2μg/kg body weight per day), for 12weeks. Bone densitometry measurements, bone turnover markers, biomechanical testing, and histomorphometric analysis were conducted. Micro computed tomography was also used to evaluate changes in microarchitecture. Lycopene treatment suppressed the OVX-induced increase in bone turnover, as indicated by changes in biomarkers of bone metabolism: serum osteocalcin (s-OC), serum N-terminal propeptide of type 1 collagen (s-PINP), serum crosslinked carboxyterminal telopeptides (s-CTX-1), and urinary deoxypyridinoline (u-DPD). Significant improvement in OVX-induced loss of bone mass, bone strength, and microarchitectural deterioration was observed in lycopene-treated OVX animals. These effects were observed mainly at sites rich in trabecular bone, with less effect in cortical bone. Lycopene treatment down-regulated osteoclast differentiation concurrent with up-regulating osteoblast together with glutathione peroxidase (GPx) catalase (CAT) and superoxide dismutase (SOD) activities. These findings demonstrate that lycopene treatment in OVX rats primarily suppressed bone turnover to restore bone strength and microarchitecture. Copyright © 2015. Published by Elsevier Inc.

  10. Extraversion, Neuroticism and Strength of the Nervous System

    Science.gov (United States)

    Frigon, Jean-Yves

    1976-01-01

    The hypothesized identity of the dimensions of extraversion-introversion and strength of the nervous system was tested on four groups of nine subjects (neurotic extraverts, stable extraverts, neurotic introverts, stable introverts). Strength of the subjects' nervous system was estimated using the electroencephalographic (EEG) variant of extinction…

  11. Application of Geostatistical Modelling to Study the Exploration Adequacy of Uniaxial Compressive Strength of Intact Rock alongthe Behesht-Abad Tunnel Route

    Directory of Open Access Journals (Sweden)

    Mohammad Doustmohammadi

    2014-12-01

    Full Text Available Uniaxial compressive strength (UCS is one of the most significant factors on the stability of underground excavation projects. Most of the time, this factor can be obtained by exploratory boreholes evaluation. Due to the large distance between exploratory boreholes in the majority of geotechnical projects, the application of geostatistical methods has increased as an estimator of rock mass properties. The present paper ties the estimation of UCS values of intact rock to the distance between boreholes of the Behesht-Abad tunnel in central Iran, using SGEMS geostatistical program. Variography showed that UCS estimation of intact rock using geostatistical methods is reasonable. The model establishment and validation was done after assessment that the model was trustworthy. Cross validation proved the high accuracy (98% and reliability of the model to estimate uniaxial compressive strength. The UCS values were then estimated along the tunnel axis. Moreover, using geostatistical estimation led to better identification of the pros and cons of geotechnical explorations in each location of tunnel route.

  12. Improving the prediction of the final part geometry in high strength steels U drawing by means of advanced material and friction models

    Science.gov (United States)

    de Argandoña, Eneko Saenz; Mendiguren, Joseba; Otero, Irune; Mugarra, Endika; Otegi, Nagore; Galdos, Lander

    2018-05-01

    Steel has been used in vehicles from the automotive industry's inception. Different steel grades are continually being developed in order to satisfy new fuel economy requirements. For example, advanced high strength steel grades (AHSS) are widely used due to their good strength/weight ratio. Because each steel grade has a different microstructure composition and hardness, they show different behaviors when they are subjected to different strain paths. Similarly, the friction behavior when using different contact pressures is considerably altered. In the present paper, four different steel grades, ZSt380, DP600, DP780 and Fortiform 1050 materials are deeply characterized using uniaxial and cyclic tension-compression tests. Coefficient of friction (COF) is also obtained using strip drawing tests. These results have been used to calibrate mixed kinematic-hardening material models as well as pressure dependent friction models. Finally, the geometrical accuracy of the different material and friction models has been evaluated by comparing the numerical predictions with experimental demonstrators obtained using a U-Drawing tester.

  13. Endocardial tip cells in the human embryo - facts and hypotheses.

    Directory of Open Access Journals (Sweden)

    Mugurel C Rusu

    Full Text Available Experimental studies regarding coronary embryogenesis suggest that the endocardium is a source of endothelial cells for the myocardial networks. As this was not previously documented in human embryos, we aimed to study whether or not endothelial tip cells could be correlated with endocardial-dependent mechanisms of sprouting angiogenesis. Six human embryos (43-56 days were obtained and processed in accordance with ethical regulations; immunohistochemistry was performed for CD105 (endoglin, CD31, CD34, α-smooth muscle actin, desmin and vimentin antibodies. Primitive main vessels were found deriving from both the sinus venosus and aorta, and were sought to be the primordia of the venous and arterial ends of cardiac microcirculation. Subepicardial vessels were found branching into the outer ventricular myocardium, with a pattern of recruiting α-SMA+/desmin+ vascular smooth muscle cells and pericytes. Endothelial sprouts were guided by CD31+/CD34+/CD105+/vimentin+ endothelial tip cells. Within the inner myocardium, we found endothelial networks rooted from endocardium, guided by filopodia-projecting CD31+/CD34+/CD105+/ vimentin+ endocardial tip cells. The myocardial microcirculatory bed in the atria was mostly originated from endocardium, as well. Nevertheless, endocardial tip cells were also found in cardiac cushions, but they were not related to cushion endothelial networks. A general anatomical pattern of cardiac microvascular embryogenesis was thus hypothesized; the arterial and venous ends being linked, respectively, to the aorta and sinus venosus. Further elongation of the vessels may be related to the epicardium and subepicardial stroma and the intramyocardial network, depending on either endothelial and endocardial filopodia-guided tip cells in ventricles, or mostly on endocardium, in atria.

  14. Relationship between Length and Surface-Enhanced Raman Spectroscopy Signal Strength in Metal Nanoparticle Chains: Ideal Models versus Nanofabrication

    Directory of Open Access Journals (Sweden)

    Kristen D. Alexander

    2012-01-01

    Full Text Available We have employed capillary force deposition on ion beam patterned substrates to fabricate chains of 60 nm gold nanospheres ranging in length from 1 to 9 nanoparticles. Measurements of the surface-averaged SERS enhancement factor strength for these chains were then compared to the numerical predictions. The SERS enhancement conformed to theoretical predictions in the case of only a few chains, with the vast majority of chains tested not matching such behavior. Although all of the nanoparticle chains appear identical under electron microscope observation, the extreme sensitivity of the SERS enhancement to nanoscale morphology renders current nanofabrication methods insufficient for consistent production of coupled nanoparticle chains. Notwithstanding this fact, the aggregate data also confirmed that nanoparticle dimers offer a large improvement over the monomer enhancement while conclusively showing that, within the limitations imposed by current state-of-the-art nanofabrication techniques, chains comprising more than two nanoparticles provide only a marginal signal boost over the already considerable dimer enhancement.

  15. The Strength Compass

    DEFF Research Database (Denmark)

    Ledertoug, Mette Marie

    In the Ph.D-project ͚Strengths-based Learning - Children͛s character strengths as a means to their learning potential͛ 750 Danish children have assessed ͚The Strength Compass͛ in order to identify their strengths and to create awareness of strengths. This was followed by a strengths......-based intervention program in order to explore the strengths. Finally different methods to apply the strength in everyday life at school were applied. The paper presentation will show the results for strengths display for children aged 6-16 in different categories: Different age groups: Are the same strengths...... present in both small children and youths? Gender: Do the results show differences between the two genders? Danish as a mother- tongue language: Do the results show any differences in the strengths display when considering different language and cultural backgrounds? Children with Special Needs: Do...

  16. Curie's hypotheses concerning radioactivity and the origin of the elements

    International Nuclear Information System (INIS)

    Kuroda, P.K.

    1999-01-01

    Pierre Curie gave two hypotheses at first; (1) It can be supposed that the radioactive substances borrow the energy, which they release, from an external radiation, and their radiation would then be a secondary radiation, (2) It can be supposed that the radioactive substances draw from themselves the energy which they release. The second hypothesis has shown the more fertile in explaining the properties of the radioactive substances. Consequently, the first hypothesis became more or less forgotten. It appears, however, the first hypothesis should play an important role in explaining the phenomena concerning the origin of the elements. The Oklo Phenomenon has demonstrated that a nuclear fire had once existed on our planet earth and formation of heavy elements was occurring in nature. The author pointed out that the difference in the isotopic compositions of xenon found in meteorites, lunar samples and in the earth's atmosphere can only be explained as due to the alterations of the isotropic compositions of xenon by combined effect of (a) mass-fractionation, (b) spallation, and (c) stellar temperature neutron-capture reactions. The strange xenon components are not isotopically pure substance. Instead, xenon-HL is a mixture of the 244 Pu fission xenon and the xenon whose isotopic compositions is severely altered by a combined effect of the processes (a), (b) and (c) mentioned above. These results also indicate that C1 carbonaceous chondrites, which is generally as the most primitive sample of the solar system material, began to retain its xenon 5.1 billion years ago, when the plutonium to uranium ratio in the solar system was as high as almost 0.6 (atom/atom), while the C2 carbonaceous chondrite began to retain their xenon about 150 million years later and the ordinary chondrites and achondrite about 500 to 600 million years later. This means that the birth of the solar system began soon after the last supernova exploded about 5.1 billion years ago, and the generally

  17. Evaluating Hypotheses of Plant Species Invasions on Mediterranean Islands: Inverse Patterns between Alien and Endemic Species

    Directory of Open Access Journals (Sweden)

    Alexander Bjarnason

    2017-08-01

    Full Text Available Invasive alien species cause major changes to ecosystem functioning and patterns of biodiversity, and the main factors involved in invasion success remain contested. Using the Mediterranean island of Crete, Greece as a case study, we suggest a framework for analyzing spatial data of alien species distributions, based on environmental predictors, aiming to gain an understanding of their spatial patterns and spread. Mediterranean islands are under strong ecological pressure from invading species due to their restricted size and increased human impact. Four hypotheses of invasibility, the “propagule pressure hypothesis” (H1, “biotic resistance hypothesis vs. acceptance hypothesis” (H2, “disturbance-mediated hypothesis” (H3, and “environmental heterogeneity hypothesis” (H4 were tested. Using data from alien, native, and endemic vascular plant species, the propagule pressure, biotic resistance vs. acceptance, disturbance-mediated, and environmental heterogeneity hypotheses were tested with Generalized Additive Modeling (GAM of 39 models. Based on model selection, the optimal model includes the positive covariates of native species richness, the negative covariates of endemic species richness, and land area. Variance partitioning between the four hypotheses indicated that the biotic resistance vs. acceptance hypothesis explained the vast majority of the total variance. These results show that areas of high species richness have greater invasibility and support the acceptance hypothesis and “rich-get-richer” distribution of alien species. The negative correlation between alien and endemic species appears to be predominantly driven by altitude, with fewer alien and more endemic species at greater altitudes, and habitat richness. The negative relationship between alien and endemic species richness provides potential for understanding patterns of endemic and alien species on islands, contributing to more effective conservation

  18. Relationship between the edgewise compression strength of ...

    African Journals Online (AJOL)

    The results of this study were used to determine the linear regression constants in the Maltenfort model by correlating the measured board edgewise compression strength (ECT) with the predicted strength, using the paper components' compression strengths, measured with the short-span compression test (SCT) and the ...

  19. Evaluation of Multiple Mechanistic Hypotheses of Leaf Photosynthesis and Stomatal Conductance against Diurnal and Seasonal Data from Two Contrasting Panamanian Tropical Forests

    Science.gov (United States)

    Serbin, S.; Walker, A. P.; Wu, J.; Ely, K.; Rogers, A.; Wolfe, B.

    2017-12-01

    Tropical forests play a key role in regulating the global carbon (C), water, and energy cycles and stores, as well as influence climate through the exchanges of mass and energy with the atmosphere. However, projected changes in temperature and precipitation patterns are expected to impact the tropics and the strength of the tropical C sink, likely resulting in significant climate feedbacks. Moreover, the impact of stronger, longer, and more extensive droughts not well understood. Critical for the accurate modeling of the tropical C and water cycle in Earth System Models (ESMs) is the representation of the coupled photosynthetic and stomatal conductance processes and how these processes are impacted by environmental and other drivers. Moreover, the parameterization and representation of these processes is an important consideration for ESM projections. We use a novel model framework, the Multi-Assumption Architecture and Testbed (MAAT), together with the open-source bioinformatics toolbox, the Predictive Ecosystem Analyzer (PEcAn), to explore the impact of the multiple mechanistic hypotheses of coupled photosynthesis and stomatal conductance as well as the additional uncertainty related to model parameterization. Our goal was to better understand how model choice and parameterization influences diurnal and seasonal modeling of leaf-level photosynthesis and stomatal conductance. We focused on the 2016 ENSO period and starting in February, monthly measurements of diurnal photosynthesis and conductance were made on 7-9 dominant species at the two Smithsonian canopy crane sites. This benchmark dataset was used to test different representations of stomatal conductance and photosynthetic parameterizations with the MAAT model, running within PEcAn. The MAAT model allows for the easy selection of competing hypotheses to test different photosynthetic modeling approaches while PEcAn provides the ability to explore the uncertainties introduced through parameterization. We

  20. How doctors generate diagnostic hypotheses: a study of radiological diagnosis with functional magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Marcio Melo

    Full Text Available In medical practice, diagnostic hypotheses are often made by physicians in the first moments of contact with patients; sometimes even before they report their symptoms. We propose that generation of diagnostic hypotheses in this context is the result of cognitive processes subserved by brain mechanisms that are similar to those involved in naming objects or concepts in everyday life.To test this proposal we developed an experimental paradigm with functional magnetic resonance imaging (fMRI using radiological diagnosis as a model. Twenty-five radiologists diagnosed lesions in chest X-ray images and named non-medical targets (animals embedded in chest X-ray images while being scanned in a fMRI session. Images were presented for 1.5 seconds; response times (RTs and the ensuing cortical activations were assessed. The mean response time for diagnosing lesions was 1.33 (SD ±0.14 seconds and 1.23 (SD ±0.13 seconds for naming animals. 72% of the radiologists reported cogitating differential diagnoses during trials (3.5 seconds. The overall pattern of cortical activations was remarkably similar for both types of targets. However, within the neural systems shared by both stimuli, activation was significantly greater in left inferior frontal sulcus and posterior cingulate cortex for lesions relative to animals.Generation of diagnostic hypotheses and differential diagnoses made through the immediate visual recognition of clinical signs can be a fast and automatic process. The co-localization of significant brain activation for lesions and animals suggests that generating diagnostic hypotheses for lesions and naming animals are served by the same neuronal systems. Nevertheless, diagnosing lesions was cognitively more demanding and associated with more activation in higher order cortical areas. These results support the hypothesis that medical diagnoses based on prompt visual recognition of clinical signs and naming in everyday life are supported by similar

  1. A soluble activin type IIA receptor mitigates the loss of femoral neck bone strength and cancellous bone mass in a mouse model of disuse osteopenia.

    Science.gov (United States)

    Lodberg, Andreas; Eijken, Marco; van der Eerden, Bram C J; Okkels, Mette Wendelboe; Thomsen, Jesper Skovhus; Brüel, Annemarie

    2018-05-01

    Disuse causes a rapid and substantial bone loss distinct in its pathophysiology from the bone loss associated with cancers, age, and menopause. While inhibitors of the activin-receptor signaling pathway (IASPs) have been shown to prevent ovariectomy- and cancer-induced bone loss, their application in a model of disuse osteopenia remains to be tested. Here, we show that a soluble activin type IIA receptor (ActRIIA-mFc) increases diaphyseal bone strength and cancellous bone mass, and mitigates the loss of femoral neck bone strength in the Botulinum Toxin A (BTX)-model of disuse osteopenia in female C57BL/6J mice. We show that ActRIIA-mFc treatment preferentially stimulates a dual-effect (anabolic-antiresorptive) on the periosteal envelope of diaphyseal bone, demonstrating in detail the effects of ActRIIA-mFc on cortical bone. These observations constitute a previously undescribed feature of IASPs that mediates at least part of their ability to mitigate detrimental effects of unloading on bone tissue. The study findings support the application of IASPs as a strategy to combat bone loss during disuse. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. A two-parameter model to predict fatigue life of high-strength steels in a very high cycle fatigue regime

    Science.gov (United States)

    Sun, Chengqi; Liu, Xiaolong; Hong, Youshi

    2015-06-01

    In this paper, ultrasonic (20 kHz) fatigue tests were performed on specimens of a high-strength steel in very high cycle fatigue (VHCF) regime. Experimental results showed that for most tested specimens failed in a VHCF regime, a fatigue crack originated from the interior of specimen with a fish-eye pattern, which contained a fine granular area (FGA) centered by an inclusion as the crack origin. Then, a two-parameter model is proposed to predict the fatigue life of high-strength steels with fish-eye mode failure in a VHCF regime, which takes into account the inclusion size and the FGA size. The model was verified by the data of present experiments and those in the literature. Furthermore, an analytic formula was obtained for estimating the equivalent crack growth rate within the FGA. The results also indicated that the stress intensity factor range at the front of the FGA varies within a small range, which is irrespective of stress amplitude and fatigue life.

  3. Adsorption of Sr(II) and Eu(III) on Na-rectorite. Effect of pH, ionic strength, concentration and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Hu, J.; Wang, X.K. [School of Nuclear Science and Engineering, North China Electric Power Univ., BJ (China); Key Lab. of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chen, C.L.; Sheng, G.D.; Li, J.X. [Key Lab. of Novel Thin Film Solar Cells, Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chen, Y.X. [School of Nuclear Science and Engineering, North China Electric Power Univ., BJ (China)

    2010-07-01

    The surface charge characteristics of Na-rectorite (NaAl{sub 4}[Si,Al]{sub 8}O{sub 20}(OH){sub 4}.nH{sub 2}O;) were studied by potentiometric acid-base titrations. Sr(II) and Eu(III) adsorptions on Na-rectorite as a function of pH, ionic strength, and Sr(II)/Eu(III) concentrations were carried out to investigate the surface interactions between Sr(II)/Eu(III) with Na-rectorite. The results indicated that the adsorptions of Sr(II) and Eu(III) on Na-rectorite increased with increasing pH and decreased with increasing ionic strength and initial Sr(II)/Eu(III) concentrations, and that the affinity of Na-rectorite for Eu(III) was much higher than for Sr(II). The experimental data of Sr(II)/Eu(III) adsorption were simulated by the diffuse-layer model (DLM) well with the aid of FITEQL 3.2. Simultaneous adsorptions of Sr(II) and Eu(III) on Na-rectorite were also modeled using the DLM. The adsorption mechanisms of Sr(II) and Eu(III) on Na-rectorite may be dominated by ion exchange interaction at low pH or moderate pH, and by surface complexation interaction at high pH. (orig.)

  4. A Modified Constitutive Model for Tensile Flow Behaviors of BR1500HS Ultra-High-Strength Steel at Medium and Low Temperature Regions

    Science.gov (United States)

    Zhao, Jun; Quan, Guo-Zheng; Pan, Jia; Wang, Xuan; Wu, Dong-Sen; Xia, Yu-Feng

    2018-01-01

    Constitutive model of materials is one of the most requisite mathematical model in the finite element analysis, which describes the relationships of flow behaviors with strain, strain rate and temperature. In order to construct such constitutive relationships of ultra-high-strength BR1500HS steel at medium and low temperature regions, the true stress-strain data over a wide temperature range of 293-873 K and strain rate range of 0.01-10 s-1 were collected from a series of isothermal uniaxial tensile tests. The experimental results show that stress-strain relationships are highly non-linear and susceptible to three parameters involving temperature, strain and strain rate. By considering the impacts of strain rate and temperature on strain hardening, a modified constitutive model based on Johnson-Cook model was proposed to characterize flow behaviors in medium and low temperature ranges. The predictability of the improved model was also evaluated by the relative error (W(%)), correlation coefficient (R) and average absolute relative error (AARE). The R-value and AARE-value for modified constitutive model at medium and low temperature regions are 0.9915 & 1.56 % and 0.9570 & 5.39 %, respectively, which indicates that the modified constitutive model can precisely estimate the flow behaviors for BR1500HS steel in the medium and low temperature regions.

  5. Evaluation of size dependent design shear strength of reinforced ...

    Indian Academy of Sciences (India)

    to the development of the size dependent models on the shear strength in ... predict the diagonal cracking strength and the ultimate shear strength of RC ... ing strength of normal beams was by Zsutty (1968) based on the data base available without .... The comparison of the calculated shear strength of the beams is shown.

  6. Constraints on the Lithospheric Strength at Volcanic Rifted Margins from the Geometry of Seaward Dipping Reflectors Using Analytic and Numerical Models

    Science.gov (United States)

    Tian, X.; Buck, W. R.

    2017-12-01

    Seaward dipping reflectors (SDRs) are found at many rifted margins. Drilling indicates SDRs are interbedded layers of basalts and sediments. Multi-channel seismic reflection data show SDRs with various width (2 100 km), thickness (1 15 km) and dip angles (0 30). Recent studies use analytic thin plate models (AtPM) to describe plate deflections under volcanic loads. They reproduce a wide range of SDRs structures without detachment faulting. These models assume that the solidified dikes provide downward loads at the rifting center. Meanwhile, erupted lava flows and sediments fill in the flexural depression and further load the lithosphere. Because the strength of the lithosphere controls the amount and wavelength of bending, the geometries of SDRs provide a window into the strength of the lithosphere during continental rifting. We attempt to provide a quantitative mapping between the SDR geometry and the lithospheric strength and thickness during rifting. To do this, we first derive analytic solutions to two observables that are functions of effective elastic thickness (Te). One observable (Xf) is the horizontal distance for SDRs to evolve from flat layers to the maximum bent layers. Another observable is the ratio between the thickness and the tangent of the maximum slope of SDRs at Xf. We then extend the AtPM to numerical thin plate models (NtPM) with spatially restricted lava flows. AtPM and NtPM show a stable and small relative difference in terms of the two observables with different values of Te. This provides a mapping of Te between NtPM and AtPM models. We also employ a fully two-dimensional thermal-mechanical treatment with elasto-visco-plastic rheology to simulate SDRs formation. These models show that brittle yielding due to bending can reduce the Te of the lithosphere by as much as 50% of the actual brittle lithospheric thickness. Quantification of effects of plastic deformation on bending allow us to use Te to link SDRs geometries to brittle lithospheric

  7. Testing biological hypotheses with embodied robots: adaptations, accidents, and by-products in the evolution of vertebrates

    Directory of Open Access Journals (Sweden)

    Sonia F Roberts

    2014-11-01

    Full Text Available Evolutionary robotics allows biologists to test hypotheses about extinct animals. We modeled some of the first vertebrates, jawless fishes, in order to study the evolution of the trait after which vertebrates are named: vertebrae. We tested the hypothesis that vertebrae are an adaptation for enhanced feeding and fleeing performance. We created a population of autonomous embodied robots, Preyro, in which the number of vertebrae, N, were free to evolve. In addition, two other traits, the span of the caudal fin, b, and the predator detection threshold, ζ, a proxy for the lateral line sensory system, were also allowed to evolve. These three traits were chosen because they evolved early in vertebrates, are all potentially important in feeding and fleeing, and vary in form among species. Preyro took on individual identities in a given generation as defined by the population’s six diploid genotypes, Gi. Each Gi was a 3-tuple, with each element an integer specifying N, b, and, ζ. The small size of the population allowed for genetic drift to operate in concert with random mutation and mating; the presence of these mechanisms of chance provided an opportunity for N to evolve by accident. The presence of three evolvable traits provided an opportunity for direct selection on b and/or ζ to evolve N as a by-product linked trait correlation. In selection trials, different Gi embodied in Preyro attempted to feed at a light source and then flee to avoid a predator robot in pursuit. The fitness of each Gi was calculated from five different types of performance: speed, acceleration, distance to the light, distance to the predator, and the number of predator escapes initiated. In each generation, we measured the selection differential, the selection gradient, the strength of chance, and the indirect correlation selection gradient. These metrics allowed us to understand the relative contributions of the three mechanisms: direct selection, chance, and indirect

  8. Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

    National Research Council Canada - National Science Library

    Underwood, John

    2000-01-01

    ...; overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid...

  9. Relativistic model-potential oscillator strengths and transition probabilities for 4fsup(n)6s-4fsup(n)6p transitions in Eu(II), Tb(II), and Ho(II) in J1j coupling

    International Nuclear Information System (INIS)

    Migdalek, J.

    1984-01-01

    The lowest 4fsup(n)6s-4fsup(n)6p transitions are studied for the Eu(II) (n=7), Tb(II) (n=9), and Ho(II) (n=11) spectra, where the J 1 J coupling is an acceptable approximation. The relativistic radial integrals, required to evaluate the oscillator strengths and transition probabilities, are calculated with the model-potential method, which includes also core-polarization effects. The similarities observed in oscillator strengths for transitions with given ΔJ but different J values are discussed and explained. The computed oscillator strengths are compared with those obtained with the Coulomb approximation and it is found that the latter are only 11-12% lower. The core polarization influence on oscillator strengths is also investigated and the 19-21% decrease in oscillator strengths due to this effect is predicted. This result may, however, be overestimated because of some deficiencies in our procedure. (author)

  10. Strength and failure modes of ceramic multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Toftegaard, Helmuth Langmaack; Linderoth, Søren

    2012-01-01

    A model was developed for the prediction of the tensile strength of thin, symmetric 3-layer sandwich specimens. The model predictions rationalize the effect of heat-treatment temperature on the strength of sandwich specimens consisting of an YSZ (Yttria-Stabilized Zirconia) substrate coated with ...... and propagating into the substrate. These predictions are consistent with microstructural observations of the fracture surfaces. A good agreement was found between the measured strength values and model predictions. © 2012 Elsevier Ltd. All rights reserved....

  11. Review and analysis of strengths and weaknesses of agro-ecosystem models for simulating C and N fluxes.

    Science.gov (United States)

    Brilli, Lorenzo; Bechini, Luca; Bindi, Marco; Carozzi, Marco; Cavalli, Daniele; Conant, Richard; Dorich, Cristopher D; Doro, Luca; Ehrhardt, Fiona; Farina, Roberta; Ferrise, Roberto; Fitton, Nuala; Francaviglia, Rosa; Grace, Peter; Iocola, Ileana; Klumpp, Katja; Léonard, Joël; Martin, Raphaël; Massad, Raia Silvia; Recous, Sylvie; Seddaiu, Giovanna; Sharp, Joanna; Smith, Pete; Smith, Ward N; Soussana, Jean-Francois; Bellocchi, Gianni

    2017-11-15

    Biogeochemical simulation models are important tools for describing and quantifying the contribution of agricultural systems to C sequestration and GHG source/sink status. The abundance of simulation tools developed over recent decades, however, creates a difficulty because predictions from different models show large variability. Discrepancies between the conclusions of different modelling studies are often ascribed to differences in the physical and biogeochemical processes incorporated in equations of C and N cycles and their interactions. Here we review the literature to determine the state-of-the-art in modelling agricultural (crop and grassland) systems. In order to carry out this study, we selected the range of biogeochemical models used by the CN-MIP consortium of FACCE-JPI (http://www.faccejpi.com): APSIM, CERES-EGC, DayCent, DNDC, DSSAT, EPIC, PaSim, RothC and STICS. In our analysis, these models were assessed for the quality and comprehensiveness of underlying processes related to pedo-climatic conditions and management practices, but also with respect to time and space of application, and for their accuracy in multiple contexts. Overall, it emerged that there is a possible impact of ill-defined pedo-climatic conditions in the unsatisfactory performance of the models (46.2%), followed by limitations in the algorithms simulating the effects of management practices (33.1%). The multiplicity of scales in both time and space is a fundamental feature, which explains the remaining weaknesses (i.e. 20.7%). Innovative aspects have been identified for future development of C and N models. They include the explicit representation of soil microbial biomass to drive soil organic matter turnover, the effect of N shortage on SOM decomposition, the improvements related to the production and consumption of gases and an adequate simulations of gas transport in soil. On these bases, the assessment of trends and gaps in the modelling approaches currently employed to

  12. Mutation-selection models of codon substitution and their use to estimate selective strengths on codon usage

    DEFF Research Database (Denmark)

    Yang, Ziheng; Nielsen, Rasmus

    2008-01-01

    Current models of codon substitution are formulated at the levels of nucleotide substitution and do not explicitly consider the separate effects of mutation and selection. They are thus incapable of inferring whether mutation or selection is responsible for evolution at silent sites. Here we impl...... codon usage in mammals. Estimates of selection coefficients nevertheless suggest that selection on codon usage is weak and most mutations are nearly neutral. The sensitivity of the analysis on the assumed mutation model is discussed.......Current models of codon substitution are formulated at the levels of nucleotide substitution and do not explicitly consider the separate effects of mutation and selection. They are thus incapable of inferring whether mutation or selection is responsible for evolution at silent sites. Here we...... implement a few population genetics models of codon substitution that explicitly consider mutation bias and natural selection at the DNA level. Selection on codon usage is modeled by introducing codon-fitness parameters, which together with mutation-bias parameters, predict optimal codon frequencies...

  13. Cognitive diagnostic assessment via Bayesian evaluation of informative diagnostic hypotheses.

    NARCIS (Netherlands)

    Hoijtink, Herbert; Béland, Sébastien; Vermeulen, Jorine A.

    2014-01-01

    There exist diverse approaches that can be used for cognitive diagnostic assessment, such as mastery testing, constrained latent class analysis, rule space methodology, diagnostic cognitive modeling, and person-fit analysis. Each of these approaches can be used within 1 of the 4 psychometric

  14. Cognitive Diagnostic Assessment via Bayesian Evaluation of Informative Diagnostic Hypotheses

    NARCIS (Netherlands)

    Hoitink, Herbert; Beland, Sebastien; Vermeulen, Jorine

    2014-01-01

    There exist diverse approaches that can be used for cognitive diagnostic assessment, such as mastery testing, constrained latent class analysis, rule space methodology, diagnostic cognitive modeling, and person-fit analysis. Each of these approaches can be used within 1 of the 4 psychometric

  15. Comparative analysis between two models of active aging and its influence on body composition, strength levels and quality of life: long-distance runners versus bodybuilders practitioners.

    Science.gov (United States)

    Latorre-Román, Pedro Ángel; Izquierdo-Sánchez, Jose Manuel; Salas-Sánchez, Jesús; García-Pinillos, Felipe

    2015-04-01

    To analyze the body composition, strength level, and the quality of life related to the health (QoL) in veteran sportsmen (>35 years old) in relation to sedentary ones (S), and to compare the result in the mentioned variables between two models of sports practice, long-distance runners (LDR) and bodybuilding practitioners (BBP). One hundred forty-eight male participants took part and were distributed into three groups: 47 LDR (age=42.01±6.96 years), 49 BBP (age=45.14±7.04 years), and 47 S (age=43.71±8.75 years). Body composition, upper- and lower-limb strength level, and QoL were assessed. The LDR and BBP obtained better performance in countermovement jump (CMJ) than the S ones (+0.06 m, paging on body composition, the muscle mass is reduced in all groups controlled (LDR, BBP, and S). Additionally, the %fat mass is increased only in S group (pactive aging showed healthier values in BMI and %fat mass as well as greater results in QoL than BBP and S groups. Nevertheless, the LDR group showed similar values to S ones in muscle mass. The regression analysis performed showed that the sedentary habit predicts the %fat mass and CMJ performance. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  16. Enhanced Wnt signaling improves bone mass and strength, but not brittleness, in the Col1a1(+/mov13) mouse model of type I Osteogenesis Imperfecta.

    Science.gov (United States)

    Jacobsen, Christina M; Schwartz, Marissa A; Roberts, Heather J; Lim, Kyung-Eun; Spevak, Lyudmila; Boskey, Adele L; Zurakowski, David; Robling, Alexander G; Warman, Matthew L

    2016-09-01

    Osteogenesis Imperfecta (OI) comprises a group of genetic skeletal fragility disorders. The mildest form of OI, Osteogenesis Imperfecta type I, is frequently caused by haploinsufficiency mutations in COL1A1, the gene encoding the α1(I) chain of type 1 collagen. Children with OI type I have a 95-fold higher fracture rate compared to unaffected children. Therapies for OI type I in the pediatric population are limited to anti-catabolic agents. In adults with osteoporosis, anabolic therapies that enhance Wnt signaling in bone improve bone mass, and ongoing clinical trials are determining if these therapies also reduce fracture risk. We performed a proof-of-principle experiment in mice to determine whether enhancing Wnt signaling in bone could benefit children with OI type I. We crossed a mouse model of OI type I (Col1a1(+/Mov13)) with a high bone mass (HBM) mouse (Lrp5(+/p.A214V)) that has increased bone strength from enhanced Wnt signaling. Offspring that inherited the OI and HBM alleles had higher bone mass and strength than mice that inherited the OI allele alone. However, OI+HBM and OI mice still had bones with lower ductility compared to wild-type mice. We conclude that enhancing Wnt signaling does not make OI bone normal, but does improve bone properties that could reduce fracture risk. Therefore, agents that enhance Wnt signaling are likely to benefit children and adults with OI type 1. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Treatment with soluble activin type IIB-receptor improves bone mass and strength in a mouse model of Duchenne muscular dystrophy.

    Science.gov (United States)

    Puolakkainen, Tero; Ma, Hongqian; Kainulainen, Heikki; Pasternack, Arja; Rantalainen, Timo; Ritvos, Olli; Heikinheimo, Kristiina; Hulmi, Juha J; Kiviranta, Riku

    2017-01-19

    Inhibition of activin/myostatin pathway has emerged as a novel approach to increase muscle mass and bone strength. Duchenne muscular dystrophy (DMD) is a neuromuscular disorder that leads to progressive muscle degeneration and also high incidence of fractures. The aim of our study was to test whether inhibition of activin receptor IIB ligands with or without exercise could improve bone strength in the mdx mouse model for DMD. Thirty-two mdx mice were divided to running and non-running groups and to receive either PBS control or soluble activin type IIB-receptor (ActRIIB-Fc) once weekly for 7 weeks. Treatment of mdx mice with ActRIIB-Fc resulted in significantly increased body and muscle weights in both sedentary and exercising mice. Femoral μCT analysis showed increased bone volume and trabecular number (BV/TV +80%, Tb.N +70%, P treatment of mdx mice with the soluble ActRIIB-Fc results in a robust increase in bone mass, without any additive effect by voluntary running. Thus ActRIIB-Fc could be an attractive option in the treatment of musculoskeletal disorders.

  18. Association Between Maximal Bench Press Strength and Isometric Handgrip Strength Among Breast Cancer Survivors.

    Science.gov (United States)

    Rogers, Benjamin H; Brown, Justin C; Gater, David R; Schmitz, Kathryn H

    2017-02-01

    To characterize the relationship between 1-repetition maximum (1-RM) bench press strength and isometric handgrip strength among breast cancer survivors. Cross-sectional study. Laboratory. Community-dwelling breast cancer survivors (N=295). Not applicable. 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer, with 3 maximal contractions of the left and right hands. All measures were conducted by staff with training in clinical exercise testing. Among 295 breast cancer survivors, 1-RM bench press strength was 18.2±6.1kg (range, 2.2-43.0kg), and isometric handgrip strength was 23.5±5.8kg (range, 9.0-43.0kg). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7kg (95% limits of agreement, -8.2 to 17.6kg). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=.31; Pstrength (R 2 =.23). Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among breast cancer survivors. 1-RM bench press strength and isometric handgrip strength quantify distinct components of muscular strength. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  19. Modeling and sensitivity analysis on the transport of aluminum oxide nanoparticles in saturated sand: effects of ionic strength, flow rate, and nanoparticle concentration.

    Science.gov (United States)

    Rahman, Tanzina; Millwater, Harry; Shipley, Heather J

    2014-11-15

    Aluminum oxide nanoparticles have been widely used in various consumer products and there are growing concerns regarding their exposure in the environment. This study deals with the modeling, sensitivity analysis and uncertainty quantification of one-dimensional transport of nano-sized (~82 nm) aluminum oxide particles in saturated sand. The transport of aluminum oxide nanoparticles was modeled using a two-kinetic-site model with a blocking function. The modeling was done at different ionic strengths, flow rates, and nanoparticle concentrations. The two sites representing fast and slow attachments along with a blocking term yielded good agreement with the experimental results from the column studies of aluminum oxide nanoparticles. The same model was used to simulate breakthrough curves under different conditions using experimental data and calculated 95% confidence bounds of the generated breakthroughs. The sensitivity analysis results showed that slow attachment was the most sensitive parameter for high influent concentrations (e.g. 150 mg/L Al2O3) and the maximum solid phase retention capacity (related to blocking function) was the most sensitive parameter for low concentrations (e.g. 50 mg/L Al2O3). Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A novel use of 3D printing model demonstrates the effects of deteriorated trabecular bone structure on bone stiffness and strength.

    Science.gov (United States)

    Barak, Meir Max; Black, Margaret Arielle

    2018-02-01

    Trabecular bone structure is crucial to normal mechanical behavior of bones. Studies have shown that osteoporosis negatively affects trabecular bone structure, mainly by reducing bone volume fraction (BV/TV) and thus increasing fracture risk. One major limitation in assessing and quantifying the effect of this structural deterioration is that no two trabecular structures are identical. Thus, when we compare a group of healthy bones against a different group of bones that experienced resorption (i.e. decreased BV/TV) we only discover an "average" mechanical effect. It is impossible to quantify the mechanical effect of individual structural deterioration for each sample, simply because we never have the same sample in both states (intact and deteriorated structure). 3D printing is a new technology that can assist in overcoming this issue. Here we report a preliminary study that compares a healthy 3D printed trabecular bone model with the same model after bone resorption was simulated. Since the deteriorated structural bone model is derived from the healthy one, it is possible to directly estimate (percentage wise) the decrease of tissue stiffness and strength as a result of bone resorption for this specific structure. Our results demonstrate that a relatively small decrease in BV/TV (about 8%) leads to a dramatic decrease in structural strength (24%) and structural stiffness (17%), (P printing is a novel and valuable tool for quantifying the effect of structural deterioration on the mechanical properties of trabecular bone. In the future, this approach may help us attain better personal fracture risk assessments by CT scanning, 3D printing and mechanically testing individual bone replicas from patients suffering excessive bone resorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Finite element modeling of shell shape in the freshwater turtle Pseudemys concinna reveals a trade-off between mechanical strength and hydrodynamic efficiency.

    Science.gov (United States)

    Rivera, Gabriel; Stayton, C Tristan

    2011-10-01

    Aquatic species can experience different selective pressures on morphology in different flow regimes. Species inhabiting lotic regimes often adapt to these conditions by evolving low-drag (i.e., streamlined) morphologies that reduce the likelihood of dislodgment or displacement. However, hydrodynamic factors are not the only selective pressures influencing organismal morphology and shapes well suited to flow conditions may compromise performance in other roles. We investigated the possibility of morphological trade-offs in the turtle Pseudemys concinna. Individuals living in lotic environments have flatter, more streamlined shells than those living in lentic environments; however, this flatter shape may also make the shells less capable of resisting predator-induced loads. We tested the idea that "lotic" shell shapes are weaker than "lentic" shell shapes, concomitantly examining effects of sex. Geometric morphometric data were used to transform an existing finite element shell model into a series of models corresponding to the shapes of individual turtles. Models were assigned identical material properties and loaded under identical conditions, and the stresses produced by a series of eight loads were extracted to describe the strength of the shells. "Lotic" shell shapes produced significantly higher stresses than "lentic" shell shapes, indicating that the former is weaker than the latter. Females had significantly stronger shell shapes than males, although these differences were less consistent than differences between flow regimes. We conclude that, despite the potential for many-to-one mapping of shell shape onto strength, P. concinna experiences a trade-off in shell shape between hydrodynamic and mechanical performance. This trade-off may be evident in many other turtle species or any other aquatic species that also depend on a shell for defense. However, evolution of body size may provide an avenue of escape from this trade-off in some cases, as changes in

  2. Beyond ROC Curvature: Strength Effects and Response Time Data Support Continuous-Evidence Models of Recognition Memory

    Science.gov (United States)

    Dube, Chad; Starns, Jeffrey J.; Rotello, Caren M.; Ratcliff, Roger

    2012-01-01

    A classic question in the recognition memory literature is whether retrieval is best described as a continuous-evidence process consistent with signal detection theory (SDT), or a threshold process consistent with many multinomial processing tree (MPT) models. Because receiver operating characteristics (ROCs) based on confidence ratings are…

  3. Rock strength under explosive loading

    International Nuclear Information System (INIS)

    Rimer, N.; Proffer, W.

    1993-01-01

    This presentation emphasizes the importance of a detailed description of the nonlinear deviatoric (strength) response of the surrounding rock in the numerical simulation of underground nuclear explosion phenomenology to the late times needed for test ban monitoring applications. We will show how numerical simulations which match ground motion measurements in volcanic tuffs and in granite use the strength values obtained from laboratory measurements on small core samples of these rocks but also require much lower strength values after the ground motion has interacted with the rock. The underlying physical mechanisms for the implied strength reduction are not yet well understood, and in fact may depend on the particular rock type. However, constitutive models for shock damage and/or effective stress have been used successfully at S-Cubed in both the Geophysics Program (primarily for DARPA) and the Containment Support Program (for DNA) to simulate late time ground motions measured at NTS in many different rock types

  4. The strength compass

    DEFF Research Database (Denmark)

    Ledertoug, Mette Marie

    of agreement/disagreement. Also the child/teacher is asked whether the actual strength is important and if he or she has the possibilities to apply the strength in the school. In a PhDproject ‘Strengths-based Learning - Children’s Character Strengths as Means to their Learning Potential’ 750 Danish children......Individual paper presentation: The ‘Strength Compass’. The results of a PhDresearch project among schoolchildren (age 6-16) identifying VIAstrengths concerning age, gender, mother-tongue-langue and possible child psychiatric diagnosis. Strengths-based interventions in schools have a theoretical...... Psychological Publishing Company. ‘The Strength Compass’ is a computer/Ipad based qualitative tool to identify the strengths of a child by a self-survey or a teacher’s survey. It is designed as a visual analogue scale with a statement of the strength in which the child/teacher may declare the degree...

  5. Retrieval of Methane Source Strengths in Europe Using a Simple Modeling Approach to Assess the Potential of Spaceborne Lidar Observations

    Science.gov (United States)

    Weaver, C.; Kiemle, C.; Kawa, S. R.; Aalto, T.; Necki, J.; Steinbacher, M.; Arduini, J.; Apadula, F.; Berkhout, H.; Hatakka, J.

    2014-01-01

    We investigate the sensitivity of future spaceborne lidar measurements to changes in surface methane emissions. We use surface methane observations from nine European ground stations and a Lagrangian transport model to infer surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands, the coal mines in Upper Silesia, Poland, and wetlands in southern Finland. The simulated methane surface concentrations capture at least half of the daily variability in the observations, suggesting that the transport model is correctly simulating the regional transport pathways over Europe. With this tool we can test whether proposed methane lidar instruments will be sensitive to changes in surface emissions. We show that future lidar instruments should be able to detect a 50% reduction in methane emissions from the Netherlands and Germany, at least during summer.

  6. Inequality and mortality: demographic hypotheses regarding advanced and peripheral capitalism.

    Science.gov (United States)

    Gregory, J W; Piché, V

    1983-01-01

    This paper analyzes mortality differences between social classes and between advanced and peripheral regions of the world economy. The demographic analysis of mortality is integrated with the study of political economy, which emphasizes the entire process of social reproduction. As part of this dialectic model, both the struggle of the working class to improve health and the interest of capital in maximizing profits are examined. Data from Québec and Upper Volta are used to illustrate the hypothesis that substantially higher mortality rates exist for the working class compared with the bourgeoisie and in the less developed peripheral regions compared with the more developed regions.

  7. Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer.

    Science.gov (United States)

    Lens, Frederic; Sperry, John S; Christman, Mairgareth A; Choat, Brendan; Rabaey, David; Jansen, Steven

    2011-05-01

    • Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic 'noise' and maximize detection of functionally relevant variation. • This integrative study combined in-depth anatomical observations using light, scanning and transmission electron microscopy of seven Acer taxa, and compared these observations with empirical measures of xylem hydraulics. • Our results reveal a 2 MPa range in species' mean cavitation pressure (MCP). MCP was strongly correlated with intervessel pit structure (membrane thickness and porosity, chamber depth), weakly correlated with pit number per vessel, and not related to pit area per vessel. At the tissue level, there was a strong correlation between MCP and mechanical strength parameters, and some of the first evidence is provided for the functional significance of vessel grouping and thickenings on inner vessel walls. In addition, a strong trade-off was observed between xylem-specific conductivity and MCP. Vessel length and intervessel wall characteristics were implicated in this safety-efficiency trade-off. • Cavitation resistance and hydraulic conductivity in Acer appear to be controlled by a very complex interaction between tissue, vessel network and pit characteristics. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

  8. Emergent spatial patterns of excitatory and inhibitory synaptic strengths drive somatotopic representational discontinuities and their plasticity in a computational model of primary sensory cortical area 3b

    Directory of Open Access Journals (Sweden)

    Kamil A. Grajski

    2016-07-01

    Full Text Available Mechanisms underlying the emergence and plasticity of representational discontinuities in the mammalian primary somatosensory cortical representation of the hand are investigated in a computational model. The model consists of an input lattice organized as a three-digit hand forward-connected to a lattice of cortical columns each of which contains a paired excitatory and inhibitory cell. Excitatory and inhibitory synaptic plasticity of feedforward and lateral connection weights is implemented as a simple covariance rule and competitive normalization. Receptive field properties are computed independently for excitatory and inhibitory cells and compared within and across columns. Within digit representational zones intracolumnar excitatory and inhibitory receptive field extents are concentric, single-digit, small, and unimodal. Exclusively in representational boundary-adjacent zones, intracolumnar excitatory and inhibitory receptive field properties diverge: excitatory cell receptive fields are single-digit, small, and unimodal; and the paired inhibitory cell receptive fields are bimodal, double-digit, and large. In simulated syndactyly (webbed fingers, boundary-adjacent intracolumnar receptive field properties reorganize to within-representation type; divergent properties are reacquired following syndactyly release. This study generates testable hypotheses for assessment of cortical laminar-dependent receptive field properties and plasticity within and between cortical representational zones. For computational studies, present results suggest that concurrent excitatory and inhibitory plasticity may underlie novel emergent properties.

  9. Defining the role of sensation, strength, and prehension for upper limb function in cervical spinal cord injury.

    Science.gov (United States)

    Kalsi-Ryan, Sukhvinder; Beaton, Dorcas; Curt, Armin; Duff, Susan; Jiang, Depeng; Popovic, Milos R; Rudhe, Claudia; Fehlings, Michael G; Verrier, Mary C

    2014-01-01

    Upper limb function plays a significant role in enhancing independence for individuals with tetraplegia. However, there is limited knowledge about the specific input of sensorimotor deficits on upper limb function. Thus the theoretical framework designed to develop the Graded Redefined Assessment of Strength Sensibility and Prehension (GRASSP) was used as a hypothetical model to analyze the impact of impairment on function. To define the association of impairment (sensation, strength, and prehension measured by the GRASSP) to upper limb function as defined by functional measures (Capabilities of Upper Extremity Questionnaire, Spinal Cord Independence Measure). A hypothetical model representing relationships by applying structural equation modeling was used to estimate the effect of the impairment domains in GRASSP on upper limb function. Data collected on 72 chronic individuals with tetraplegia was used to test the hypothetical model. Structural equation modeling confirmed strong associations between sensation, strength, and prehension with upper limb function, and determined 72% of the variance in "sensorimotor upper limb function" was explained by the model. Statistics of fit showed the data did fit the hypothesized model. Sensation and strength influence upper limb function directly and indirectly with prehension as the mediator. The GRASSP is a sensitive diagnostic tool in distinguishing the relative contribution of strength, sensation and prehension to function. Thus, the impact of interventions on specific domains of impairment and related contribution on clinical recovery of the upper limb can be detailed to optimize rehabilitation programs.

  10. Modelling Analysis of Echo Signature and Target Strength of a Realistically Modelled Ship Wake for a Generic Forward Looking Active Sonar

    NARCIS (Netherlands)

    Schippers, P.

    2009-01-01

    The acoustic modelling in TNO’s ALMOST (=Acoustic Loss Model for Operational Studies and Tasks) uses a bubble migration model as realistic input for wake modelling. The modelled bubble cloud represents the actual ship wake. Ship hull, propeller and bow wave are the main generators of bubbles in the

  11. Sexual Orientation as a Peripheral Cue in Advertising: Effects of Models' Sexual Orientation, Argument Strength, and Involvement on Responses to Magazine Ads.

    Science.gov (United States)

    Ivory, Adrienne Holz

    2017-10-12

    This study examines how sexual orientation of couples featured in magazine advertisements affects heterosexual viewers' responses using the elaboration likelihood model as a framework. A 3 × 2 × 2 × 3 experiment tested effects of sexual orientation, argument strength, involvement, and attitudes toward homosexuality on heterosexuals' attitudes toward the couple, advertisement, brand, and product, purchase intentions, and recall. Results indicate that consumers were accepting of ads with lesbian portrayals. Participants showed more negative attitudes toward gay male portrayals, but attitudes toward heterosexual and lesbian ads were similar. This effect was moderated by participants' attitudes toward homosexuals. Low-involvement consumers showed more negative attitudes toward homosexual portrayals than toward heterosexual portrayals, indicating that sexual orientation may have served as a peripheral cue negatively impacting attitudes toward the couple and ad under low elaboration. These effects were not observed for attitudes toward the brand and product, purchase intentions, or recall.

  12. The Combined Strength of Thermodynamics and Comparative Planetology: Application of Activity Models to Core Formation in Terrestrial Bodies

    Science.gov (United States)

    Righter, K.; Pando, K. M.; Danielson, L. R.

    2015-01-01

    Recent models for accretion of terrestrial bodies involve metal-silicate equilibrium as the metallic core formed during growth. Most elements considered are either refractory or well studied elements for which effects of pressure, temperature, oxygen fugacity, and metallic liquid composition are well known. There are a large number of elements that are both siderophile and volatile, whose fate in such models is unknown, largely due to a lack of data at comparable conditions and com-positions (FeNi core with light elements such as S, C, Si, and O). We have focused on Ge, In, As, Sb and determined the effect of Si and C on metal-silicate partitioning, and developed a thermo-dynamic model that allows application of these new data to a wide range of planetary bodies. New experiments: We have previously carried out experiments with FeSi metallic liquid at C-saturated conditions at 1600 and 1800 C [4]. In a new series of experiments we investigate the effect of Si in carbon-free systems at 1600 C for comparison. Experiments were carried out at 1 GPa in MgO capsules using the same basaltic starting composition as in previous studies. The MgO capsule reacts with the silicate melt to form more MgO-rich liquids that have 22-26 wt% MgO. Experimental met-als and silicates were analyzed using a combination of electron microprobe analysis and laser ablation ICP-MS. Results: The new results can be interpreted by considering Ge as an example, in the simple exchange equilibrium Fe + GeO = FeO + Ge, where the equilibrium constant Kd can be examined as a function of Si content of the metal. The slope of lnKd vs. (1-XSi) for this new series allows derivation of the epsilon interaction parameter for each of these four elements and Si (both C-saturated and C-free).All four elements have positive epsilon values, indicating that Si causes a decrease in the partition coefficients; values are 6.6, 6.5, 27.8 and 25.2 for In, Ge, As, and Sb, respectively, at 1 GPa and 1600 C. As an example of

  13. Mathematical Modelling of a Friction Stir Welding Process to Predict the Joint Strength of Two Dissimilar Aluminium Alloys Using Experimental Data and Genetic Programming

    Directory of Open Access Journals (Sweden)

    Mohammed Yunus

    2018-01-01

    Full Text Available Friction stir welding (FSW is the most popular and efficient method of solid-state joining for similar as well as dissimilar metals and alloys. It is mostly used in applications for aerospace, rail, automotive, and marine industries. Many researchers are currently working with different perspectives on this FSW process for various combinations of materials. The general input process parameters are the thickness of the plate, axial load, rotational speed, welding speed, and tilt angle. The output parameters are joint hardness, % of elongation, and impact and yield strengths. Genetic programming (GP is a relatively new method of evolutionary computing with the principal advantage of this approach being to evaluate efficacious predictive mathematical models or equations without any prior assumption regarding the possible form of the functional relationship. This paper both defines and illustrates how GP can be applied to the FSW process to derive precise relationships between the output and input parameters in order to obtain a generalized prediction model. A GP model will assist engineers in quantifying the performance of FSW, and the results from this study can then be utilized to estimate future requirements based on the historical data to provide a robust solution. The obtained results from the GP models showed good agreement with experimental and target data at an average prediction error of 0.72%.

  14. Topological strength of magnetic skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Ramos, J.G.G.S.; Rodrigues, E.I.B.

    2017-02-01

    This work deals with magnetic structures that attain integer and half-integer skyrmion numbers. We model and solve the problem analytically, and show how the solutions appear in materials that engender distinct, very specific physical properties, and use them to describe their topological features. In particular, we found a way to model skyrmion with a large transition region correlated with the presence of a two-peak skyrmion number density. Moreover, we run into the issue concerning the topological strength of a vortex-like structure and suggest an experimental realization, important to decide how to modify and measure the topological strength of the magnetic structure.

  15. The micromechanics model analysis of the viscosity regulation of ultra-high strength concrete with low viscosity

    Science.gov (United States)

    Zhu, M.; Wang, F. G.; Wang, F. Z.; Liu, Y. P.

    2017-02-01

    The plastic viscosity of mortar and concrete with different binder content, sand ratio, water-binder ratio, microbead dosage and different class and dosage of fly ash were tested and calculated according tomicromechanics model proposed by A. Ghanbari and B.L. Karihaloo, The correlations between these parameters and fresh concrete workability were also investigated, which showed i. high consistence with the objective reality. When binder content, microbead dosage, fly ash dosage or the water-binder ratio was increased or sand ratio was reduced, the fresh concrete viscosity would decrease correspondingly. However their effects were not that same. The relationships between T50 a, V-funnel and inverted slump time with fresh concrete viscosity were established, respectively.

  16. Increased carbon sequestration in a Danish beech forest during 1996-2016: Observations and hypotheses.

    Science.gov (United States)

    Pilegaard, Kim; Ibrom, Andreas

    2017-04-01

    A study of the net exchange of CO2 (NEE) between the atmosphere and a beech forest near Sorø, Denmark, during 14 years (1996-2009) showed that the beech forest acted as an increasing sink of CO2 [1]. A significant increase in gross primary production (GPP) and a smaller and not significant increase in ecosystem respiration (RE) were also found. Thus, the increased NEE was mainly attributed to an increase in GPP. The length of the carbon uptake period (CUP) significantly increased, whereas there was a no increase in the leafed period (LP). This means that the leaves stayed active longer. The increase in the carbon uptake period explained about half of the increasing NEE. The remaining increase was believed to be due to an observed increased uptake capacity of the canopy and increased annual radiation efficiency[2]. The causes for this were hypothesized to be a combination of increase in atmospheric CO2 concentration, higher summer precipitation, and increased availability of N. A higher nitrogen content in the leaves was observed towards the end of the observation period. An updated analysis of the flux data, now including the years 1996-2016, confirms the increasing trend in carbon sequestration of the forest, an increasingly longer growing season, and a significant correlation of NEE and CUP, however, similarly to the first study, the increase in CUP only explains about half of the total increase. Here we investigate three hypotheses for the remaining reasons for the increase: H1: increased canopy nitrogen content H2: carbon dioxide fertilisation H3: increased water availability due to changing precipitation patterns. We describe the multiannual development of canopy photosynthesis capacity with regression analysis and perform sensitivity studies with the canopy model MAESTRA [3] to investigate the above hypotheses. The results will be presented, critically discussed and interpreted with respect to general effects of global climate change and site specific, local

  17. Pickles and ice cream! Food cravings in pregnancy: hypotheses, preliminary evidence, and directions for future research

    Science.gov (United States)

    Orloff, Natalia C.; Hormes, Julia M.

    2014-01-01

    Women in the United States experience an increase in food cravings at two specific times during their life, (1) perimenstrually and (2) prenatally. The prevalence of excess gestational weight gain (GWG) is a growing concern due to its association with adverse health outcomes in both mothers and children. To the extent that prenatal food cravings may be a determinant of energy intake in pregnancy, a better understanding of craving etiology could be crucial in addressing the issue of excessive GWG. This paper reviews the available literature to corroborate and/or dispute some of the most commonly accepted hypotheses regarding the causes of food cravings during pregnancy, including a role of (1) hormonal changes, (2) nutritional deficits, (3) pharmacologically active ingredients in the desired foods, and (4) cultural and psychosocial factors. An existing model of perimenstrual chocolate craving etiology serves to structure the discussion of these hypotheses. The main hypotheses discussed receive little support, with the notable exception of a postulated role of cultural and psychosocial factors. The presence of cravings during pregnancy is a common phenomenon across different cultures, but the types of foods desired and the adverse impact of cravings on health may be culture-specific. Various psychosocial factors appear to correlate with excess GWG, including the presence of restrained eating. Findings strongly suggest that more research be conducted in this area. We propose that future investigations fall into one of the four following categories: (1) validation of food craving and eating-related measures specifically in pregnant populations, (2) use of ecological momentary assessment to obtain real time data on cravings during pregnancy, (3) implementation of longitudinal studies to address causality between eating disorder symptoms, food cravings, and GWG, and (4) development of interventions to ensure proper prenatal nutrition and prevent excess GWG. PMID:25295023

  18. Pickles and Ice Cream! Food Cravings in Pregnancy: Hypotheses, Preliminary Evidence, and Directions for Future Research

    Directory of Open Access Journals (Sweden)

    Natalia C. Orloff

    2014-09-01

    Full Text Available Women in the United States experience an increase in food cravings at two specific times during their life, 1 perimenstrually and 2 prenatally. The prevalence of excess gestational weight gain (GWG is a growing concern due to its association with adverse health outcomes in both mothers and children. To the extent that prenatal food cravings may be a determinant of energy intake in pregnancy, a better understanding of craving etiology could be crucial in addressing the issue of excessive GWG. This paper reviews the available literature to corroborate and/or dispute some of the most commonly accepted hypotheses regarding the causes of food cravings during pregnancy, including a role of 1 hormonal changes, 2 nutritional deficits, 3 pharmacologically active ingredients in the desired foods, and 4 cultural and psychosocial factors. An existing model of perimenstrual chocolate craving etiology serves to structure the discussion of these hypotheses. The main hypotheses discussed receive little support, with the notable exception of a postulated role of cultural and psychosocial factors. The presence of cravings during pregnancy is a common phenomenon across different cultures, but the types of foods desired and the adverse impact of cravings on health may be culture-specific. Various psychosocial factors appear to correlate with excess GWG, including the presence of restrained eating. Findings strongly suggest that more research be conducted in this area. We propose that future investigations fall into one of the four following categories: 1 validation of food craving and eating-related measures specifically in pregnant populations, 2 use of ecological momentary assessment to obtain real time data on cravings during pregnancy, 3 implementation of longitudinal studies to address causality between eating disorder symptoms, food cravings, and gestational weight gain, and 4 development of interventions to ensure proper prenatal nutrition and prevent excess

  19. Access pricing for transmission networks: Hypotheses and empirical evidence

    Energy Technology Data Exchange (ETDEWEB)

    Martoccia, Maria [Decision Technology Centre, London (United Kingdom)

    1999-08-01

    The sectors characterised by the use of transmission or transport networks as inputs of production (electricity, gas, telecommunications) have long been considered as natural monopolies. Thanks to the technological innovations which have modified the economics of production (as in electricity generation) or that have driven the development of high value added services (as in telecommunications), the boundaries of the old natural monopolies have been eroded by the presence of operators potentially able to compete in national and international markets. The objective is to delineate, by analysing the more significant theoretical contributions and some of the restructuring experiences of the sector in question, the possible regulatory solutions which, in the perspective of a `European market` for electricity, makes the management and the expansion of the transmission networks adequate for the `open access` of national electricity sectors. The analysis of some mature experiences, such as in Chile, Argentina, the UK and Norway, in the second section, will offer a useful support to this evaluation. The regulatory solution here adopted will be analysed, in particular, with reference to the two main problems outlined above: on the one hand, the problem of providing through prices the necessary information about the opportunities of using the transmission assets; and on the other hand, the problem of defining an efficient incentive mechanism for the behaviour of the monopolist (the owner of the transmission assets). Finally, by considering the limits found in the solutions explored in these models, we will try, in the third section, to delineate the evolution that the regulation of the analysed sectors could follow, in an attempt to make the optimal solution defined in the first section consistent with the imperfections of the real scenarios. (EHS)

  20. A Review of Hypothesized Determinants Associated with Bighorn Sheep (Ovis canadensis Die-Offs

    Directory of Open Access Journals (Sweden)

    David S. Miller

    2012-01-01

    Full Text Available Multiple determinants have been hypothesized to cause or favor disease outbreaks among free-ranging bighorn sheep (Ovis canadensis populations. This paper considered direct and indirect causes of mortality, as well as potential interactions among proposed environmental, host, and agent determinants of disease. A clear, invariant relationship between a single agent and field outbreaks has not yet been documented, in part due to methodological limitations and practical challenges associated with developing rigorous study designs. Therefore, although there is a need to develop predictive models for outbreaks and validated mitigation strategies, uncertainty remains as to whether outbreaks are due to endemic or recently introduced agents. Consequently, absence of established and universal explanations for outbreaks contributes to conflict among wildlife and livestock stakeholders over land use and management practices. This example illustrates the challenge of developing comprehensive models for understanding and managing wildlife diseases in complex biological and sociological environments.

  1. The evolution of parental care in insects: A test of current hypotheses.

    Science.gov (United States)

    Gilbert, James D J; Manica, Andrea

    2015-05-01

    Which sex should care for offspring is a fundamental question in evolution. Invertebrates, and insects in particular, show some of the most diverse kinds of parental care of all animals, but to date there has been no broad comparative study of the evolution of parental care in this group. Here, we test existing hypotheses of insect parental care evolution using a literature-compiled phylogeny of over 2000 species. To address substantial uncertainty in the insect phylogeny, we use a brute force approach based on multiple random resolutions of uncertain nodes. The main transitions were between no care (the probable ancestral state) and female care. Male care evolved exclusively from no care, supporting models where mating opportunity costs for caring males are reduced-for example, by caring for multiple broods-but rejecting the "enhanced fecundity" hypothesis that male care is favored because it allows females to avoid care costs. Biparental care largely arose by males joining caring females, and was more labile in Holometabola than in Hemimetabola. Insect care evolution most closely resembled amphibian care in general trajectory. Integrating these findings with the wealth of life history and ecological data in insects will allow testing of a rich vein of existing hypotheses. © 2015 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  2. The evolution of parental care in insects: A test of current hypotheses

    Science.gov (United States)

    Gilbert, James D J; Manica, Andrea

    2015-01-01

    Which sex should care for offspring is a fundamental question in evolution. Invertebrates, and insects in particular, show some of the most diverse kinds of parental care of all animals, but to date there has been no broad comparative study of the evolution of parental care in this group. Here, we test existing hypotheses of insect parental care evolution using a literature-compiled phylogeny of over 2000 species. To address substantial uncertainty in the insect phylogeny, we use a brute force approach based on multiple random resolutions of uncertain nodes. The main transitions were between no care (the probable ancestral state) and female care. Male care evolved exclusively from no care, supporting models where mating opportunity costs for caring males are reduced—for example, by caring for multiple broods—but rejecting the “enhanced fecundity” hypothesis that male care is favored because it allows females to avoid care costs. Biparental care largely arose by males joining caring females, and was more labile in Holometabola than in Hemimetabola. Insect care evolution most closely resembled amphibian care in general trajectory. Integrating these findings with the wealth of life history and ecological data in insects will allow testing of a rich vein of existing hypotheses. PMID:25825047

  3. The Association between Maximal Bench Press Strength and Isometric Handgrip Strength among Breast Cancer Survivors

    Science.gov (United States)

    Rogers, Benjamin H.; Brown, Justin C.; Gater, David R.; Schmitz, Kathryn H.

    2016-01-01

    Objective One-repetition maximum (1-RM) bench press strength is considered the gold standard to quantify upper-body muscular strength. Isometric handgrip strength is frequently used as a surrogate for 1-RM bench press strength among breast cancer (BrCa) survivors. The relationship between 1-RM bench press strength and isometric handgrip strength, however, has not been characterized among BrCa survivors. Design Cross-sectional study. Setting Laboratory. Participants Community-dwelling BrCa survivors. Interventions Not applicable. Main Outcome Measure 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer with three maximal contractions of left and right hands. All measures were conducted by staff with training in clinical exercise testing. Results Among 295 BrCa survivors, 1-RM bench press strength was 18.2±6.1 kg (range: 2.2-43.0) and isometric handgrip strength was 23.5±5.8 kg (range: 9.0-43.0). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=0.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7 kg (95% limits of agreement: −8.2 to 17.6). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=0.31; Pstrength (R2=0.23). Conclusions Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among BrCa survivors. 1-RM bench press and isometric handgrip strength quantify distinct components of muscular strength. PMID:27543047

  4. Strengths-based Learning

    DEFF Research Database (Denmark)

    Ledertoug, Mette Marie

    -being. The Ph.D.-project in Strength-based learning took place in a Danish school with 750 pupils age 6-16 and a similar school was functioning as a control group. The presentation will focus on both the aware-explore-apply processes and the practical implications for the schools involved, and on measurable......Strength-based learning - Children͛s Character Strengths as Means to their Learning Potential͛ is a Ph.D.-project aiming to create a strength-based mindset in school settings and at the same time introducing strength-based interventions as specific tools to improve both learning and well...

  5. Exhaustive sampling of docking poses reveals binding hypotheses for propafenone type inhibitors of P-glycoprotein.

    Directory of Open Access Journals (Sweden)

    Freya Klepsch

    2011-05-01

    Full Text Available Overexpression of the xenotoxin transporter P-glycoprotein (P-gp represents one major reason for the development of multidrug resistance (MDR, leading to the failure of antibiotic and cancer therapies. Inhibitors of P-gp have thus been advocated as promising candidates for overcoming the problem of MDR. However, due to lack of a high-resolution structure the concrete mode of interaction of both substrates and inhibitors is still not known. Therefore, structure-based design studies have to rely on protein homology models. In order to identify binding hypotheses for propafenone-type P-gp inhibitors, five different propafenone derivatives with known structure-activity relationship (SAR pattern were docked into homology models of the apo and the nucleotide-bound conformation of the transporter. To circumvent the uncertainty of scoring functions, we exhaustively sampled the pose space and analyzed the poses by combining information retrieved from SAR studies with common scaffold clustering. The results suggest propafenone binding at the transmembrane helices 5, 6, 7 and 8 in both models, with the amino acid residue Y307 playing a crucial role. The identified binding site in the non-energized state is overlapping with, but not identical to, known binding areas of cyclic P-gp inhibitors and verapamil. These findings support the idea of several small binding sites forming one large binding cavity. Furthermore, the binding hypotheses for both catalytic states were analyzed and showed only small differences in their protein-ligand interaction fingerprints, which indicates only small movements of the ligand during the catalytic cycle.

  6. The Importance of Muscular Strength: Training Considerations.

    Science.gov (United States)

    Suchomel, Timothy J; Nimphius, Sophia; Bellon, Christopher R; Stone, Michael H

    2018-04-01

    This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules. Bilateral training, eccentric training and accentuated eccentric loading, and variable resistance training may produce the greatest comprehensive strength adaptations. Bodyweight exercise, isolation exercises, plyometric exercise, unilateral exercise, and kettlebell training may be limited in their potential to improve maximal strength but are still relevant to strength development by challenging time-limited force expression and differentially challenging motor demands. Training to failure may not be necessary to improve maximum muscular strength and is likely not necessary for maximum gains in strength. Indeed, programming that combines heavy and light loads may improve strength and underpin other strength-power characteristics. Multiple sets appear to produce superior training benefits compared to single sets; however, an athlete's training status and the dose-response relationship must be considered. While 2- to 5-min interset rest intervals may produce the greatest strength-power benefits, rest interval length may vary based an athlete's training age, fiber type, and genetics. Weaker athletes should focus on developing strength before emphasizing power-type training. Stronger athletes may begin to emphasize power-type training while maintaining/improving their strength. Future research should

  7. Insulin resistance and bone strength: findings from the study of midlife in the United States.

    Science.gov (United States)

    Srikanthan, Preethi; Crandall, Carolyn J; Miller-Martinez, Dana; Seeman, Teresa E; Greendale, Gail A; Binkley, Neil; Karlamangla, Arun S

    2014-04-01

    Although several studies have noted increased fracture risk in individuals with type 2 diabetes mellitus (T2DM), the pathophysiologic mechanisms underlying this association are not known. We hypothesize that insulin resistance (the key pathology in T2DM) negatively influences bone remodeling and leads to reduced bone strength. Data for this study came from 717 participants in the Biomarker Project of the Midlife in the United States Study (MIDUS II). The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from fasting morning blood glucose and insulin levels. Projected 2D (areal) bone mineral density (BMD) was measured in the lumbar spine and left hip using dual-energy X-ray absorptiometry (DXA). Femoral neck axis length and width were measured from the hip DXA scans, and combined with BMD and body weight and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. We used multiple linear regressions to examine the relationship between HOMA-IR and bone strength, adjusted for age, gender, race/ethnicity, menopausal transition stage (in women), and study site. Greater HOMA-IR was associated with lower values of all three composite indices of femoral neck strength relative to load, but was not associated with BMD in the femoral neck. Every doubling of HOMA-IR was associated with a 0.34 to 0.40 SD decrement in the strength indices (p<0.001). On their own, higher levels of fasting insulin (but not of glucose) were independently associated with lower bone strength. Our study confirms that greater insulin resistance is related to lower femoral neck strength relative to load. Further, we note that hyperinsulinemia, rather than hyperglycemia, underlies this relationship. Although cross-sectional associations do not prove causality, our findings do suggest that insulin resistance and in particular, hyperinsulinemia, may negatively affect bone strength relative to

  8. Studies of brain and cognitive maturation through childhood and adolescence: a strategy for testing neurodevelopmental hypotheses.

    Science.gov (United States)

    Luna, B; Sweeney, J A

    2001-01-01

    Although neurodevelopmental models of schizophrenia are now widely accepted, there is minimal direct human evidence of dysmaturation in schizophrenia to support this theory. This is especially the case regarding maturational changes during late childhood and adolescence, which immediately precede the typical age of onset of the disorder. By integrating new noninvasive methods of functional magnetic resonance imaging with techniques of developmental cognitive neuroscience, it is now possible to begin systematic research programs to directly test hypotheses of neurodevelopmental abnormalities in schizophrenia. In this article, we describe strategies for characterizing developmental changes taking place during the critical period of adolescence that can elucidate dysmaturation processes in schizophrenia. We emphasize the need for studies characterizing normal development before examining at-risk or clinical populations, and the potential value of using neurobehavioral and neuroimaging approaches to directly characterize the dysmaturation associated with schizophrenia.

  9. Science from evaluation: testing hypotheses about differential effects of three youth-focused suicide prevention trainings.

    Science.gov (United States)

    Coleman, Daniel; Del Quest, Aisling

    2015-01-01

    As part of an evaluation component of a youth suicide prevention, a quasi-experimental repeated measures design tested hypotheses about two brief suicide prevention gatekeeper trainings (Question, Persuade, Refer [QPR] and RESPONSE) and one longer suicide intervention skills training (Applied Suicide Intervention Skills Training [ASIST]). All three trainings showed large changes in prevention attitudes and self-efficacy, largely maintained at follow-up. ASIST trainees had large increases in asking at-risk youth about suicide at follow-up. Convergent with other research, modeling and role-play in training are crucial to increased prevention behaviors. Practice and research implications are discussed, including social work roles in suicide prevention and research.

  10. Comments and hypotheses on the mechanism of methane against ischemia/reperfusion injury

    Directory of Open Access Journals (Sweden)

    He Li

    2017-01-01

    Full Text Available As we all know, methane is a kind of fuel. Previous studies have shown that methanogens in the colon can react with carbon dioxide and hydrogen to produce methane. In a recent study, the anti-inflammatory effects of methane were shown in a dog model of small intestinal ischemia/reperfusion. The mechanism of this anti-inflammatory effect needs further investigation. Recently, studies have shown anti-inflammatory, anti-apoptotic and anti-oxidative effects of methane on different organic injuries. According to the results of these studies, we hypothesize that the initial effects of methane are to react with free radicals and enhance expression of antioxidase through forkhead box transcription factor class O pathway. The anti-inflammatory effect is following the anti-oxidative effect, and the anti-apoptotic effect relies on anti-inflammatory and anti-oxidative effects.

  11. Revisiting the environmental Kuznets curve and pollution haven hypotheses: MIKTA sample.

    Science.gov (United States)

    Bakirtas, Ibrahim; Cetin, Mumin Atalay

    2017-08-01

    This study aims to examine the validity of the environmental Kuznets curve (EKC) and pollution haven hypotheses in Mexico, Indonesia, South Korea, Turkey, and Australia (MIKTA) countries from 1982 to 2011 by using a panel vector auto regressive (PVAR) model. Empirical findings imply that the EKC hypothesis is rejected by the MIKTA sample. However, PVAR estimations reveal Granger causality from income level, foreign direct investment (FDI) inward, and energy consumption to CO 2 emissions. Orthogonalized impulse-response functions are derived from PVAR estimations. According to the analysis results, the response of CO 2 emissions to a shock on FDI is positive. These results assert that FDI has a detrimental effect on environmental quality in MIKTA countries which means the pollution haven hypothesis is confirmed by the MIKTA sample. Therefore, MIKTA countries should revise their current economic growth plans to provide sustainable development and also re-organize their legal infrastructure to induce usage of renewable energy sources.

  12. Strength and life under creeping

    International Nuclear Information System (INIS)

    Pospishil, B.

    1982-01-01

    Certain examples of the application of the Lepin modified creep model, which are of interest from technical viewpoint, are presented. Mathematical solution of the dependence of strength limit at elevated temperatures on creep characteristics is obtained. Tensile test at elevated temperatures is a particular case of creep or relaxation and both strength limit and conventional yield strength at elevated temperatures are completely determined by parameters of state equations during creep. The equation of fracture summing during creep is confirmed not only by the experiment data when stresses change sporadically, but also by good reflection of durability curve using the system of equations. The system presented on the basis of parameters of the equations obtained on any part of durability curve, permits to forecast the following parameters of creep: strain, strain rate, life time, strain in the process of fracture. Tensile test at elevated temperature is advisable as an addition when determining creep curves (time-strain curves) [ru

  13. Give Me Strength.

    Institute of Scientific and Technical Information of China (English)

    维拉

    1996-01-01

    Mort had an absolutely terrible day at the office.Everythingthat could go wrong did go wrong.As he walked home he could beheard muttering strange words to himself:“Oh,give me strength,give me strength.”Mort isn’t asking for the kind of strength thatbuilds strong muscles:he’s asking for the courage or ability to

  14. Accelerated Strength Testing of Thermoplastic Composites

    Science.gov (United States)

    Reeder, J. R.; Allen, D. H.; Bradley, W. L.

    1998-01-01

    Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.

  15. Institutional Strength in Depth

    International Nuclear Information System (INIS)

    Weightman, M.

    2016-01-01

    Much work has been undertaken in order to identify, learn and implement the lessons from the TEPCO Fukushima Daiichi nuclear accident. These have mainly targeted on engineering or operational lessons. Less attention has been paid to the institutional lessons, although there have been some measures to improve individual peer reviews, particularly by the World Association of Nuclear Operators, and the authoritative IAEA report published in 2015 brought forward several important lessons for regulators and advocated a system approach. The report noted that one of the contributing factors the accident was the tendency of stakeholders not to challenge. Additionally, it reported deficiencies in the regulatory authority and system. Earlier, the root cause of the accident was identified by a Japanese independent parliamentary report as being cultural and institutional. The sum total of the institutions, the safety system, was ineffective. While it is important to address the many technical and operational lessons these may not necessary address this more fundamental lesson, and may not serve to provide robust defences against human or institutional failings over a wide variety of possible events and combinations. The overall lesson is that we can have rigorous and comprehensive safety standards and other tools in place to deliver high levels of safety, but ultimately what is important is the ability of the nuclear safety system to ensure that the relevant institutions diligently and effectively apply those standards and tools — to be robust and resilient. This has led to the consideration of applying the principles of the strength in depth philosophy to a nuclear safety system as a way of providing a framework for developing, assessing, reviewing and improving the system. At an IAEA conference in October 2013, a model was presented for a robust national nuclear safety system based on strength in depth philosophy. The model highlighted three main layers: industry, the

  16. Effect of tocotrienol from Bixa orellana (annatto on bone microstructure, calcium content, and biomechanical strength in a model of male osteoporosis induced by buserelin

    Directory of Open Access Journals (Sweden)

    Mohamad NV

    2018-03-01

    Full Text Available Nur-Vaizura Mohamad, Soelaiman Ima-Nirwana, Kok-Yong Chin Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia Background: Patients receiving androgen deprivation therapy experience secondary hypogonadism, associated bone loss, and increased fracture risk. It has been shown that tocotrienol from Bixa orellana (annatto prevents skeletal microstructural changes in rats experiencing primary hypogonadism. However, its potential in preventing bone loss due to androgen deprivation therapy has not been tested. This study aimed to evaluate the skeletal protective effects of annatto tocotrienol using a buserelin-induced osteoporotic rat model. Methods: Forty-six male Sprague Dawley rats aged 3 months were randomized into six groups. The baseline control (n=6 was sacrificed at the onset of the study. The normal control (n=8 received corn oil (the vehicle of tocotrienol orally daily and normal saline (the vehicle of buserelin subcutaneously daily. The buserelin control (n=8 received corn oil orally daily and subcutaneous buserelin injection (75 µg/kg daily. The calcium control (n=8 was supplemented with 1% calcium in drinking water and daily subcutaneous buserelin injection (75 µg/kg. The remaining rats were given daily oral annatto tocotrienol at 60 mg/kg (n=8 or 100 mg/kg (n=8 plus daily subcutaneous buserelin injection (75 µg/kg (n=8. At the end of the experiment, the rats were euthanized and their blood, tibia, and femur were harvested. Structural changes of the tibial trabecular and cortical bone were examined using X-ray micro-computed tomography. Femoral bone calcium content and biomechanical strength were also evaluated. Results: Annatto tocotrienol at 60 and 100 mg/kg significantly prevented the deterioration of trabecular bone and cortical thickness in buserelin-treated rats (P<0.05. Both doses of annatto tocotrienol also improved femoral biomechanical strength and bone calcium content

  17. Contrast visibility for indirect MR arthrography with different protein contents and agent relaxivities at different field strengths: An in vitro model

    International Nuclear Information System (INIS)

    Nouh, M.R.; Schweitzer, M.E.; Ragatte, Ravinder R.

    2011-01-01

    Objectives: Protein binding and relaxivity are major determinants of the relative effectiveness of an MR arthrographic contrast agent. We sought to evaluate the optimal concentrations of high and usual relaxivity agents in two different proteinous environments at variable field strength for two MR contrast agents of different relaxivities. Materials and methods: At 1.5, 3.0 and 7.0 T, gadobenate dimeglumine (Multihance) with high-relaxivity in proteinous environment and gadoteridol (Prohance) with more typical behavior were studied at 1.25, 2.5, 5, and 10 mmol in 1.7 g/dL and 3 g/dL albumin (mimicking protein content of normal and inflammatory synovial fluids, respectively) vs. pure normal saline, as a control. Analysis of image signal intensity (SI) and relaxivity values was done. Results: In our study a change in concentration had no significant effect on T1 SI. In contrast, nearly every change in concentration led to a significant change in T2 SI. In 1.25 mmol concentration, there was no effect on T1 SI of either protein concentrations while higher concentrations showed significant decreased SI in either protein carrier compared to saline. The SI of Gadoteridol was significantly higher (p < 0.0001) than that of gadobenate at each of 3 T and 7 T, but was significantly lower (p < 0.001) at 1.5 T in saline solution while this was not significant for either protein carrier. Both protein carriers had significant effect on T1 (p = 0.0124) and T2 (p = 0.0118) relaxivities. Also solution concentration significantly (p < 0.01) affected both T1 and T2 relaxivities. Field strength did not affect T1 relaxivity (p = 0.02511) while it significantly affected T2 relaxivity (p < 0.001). This was significant (p = 0.035) in case of gadoteridol at 3 T. Conclusion: 1.25 mmol concentration of both gadoteridol and gadobenate solutions yields the best diagnostic T1 SI specially in higher fields (3 T and 7 T) and avoid the deleterious effect of increasing concentration on T2 SI

  18. Polynomial expansions and transition strengths

    International Nuclear Information System (INIS)

    Draayer, J.P.

    1980-01-01

    The subject is statistical spectroscopy applied to determining strengths and strength sums of excitation processes in nuclei. The focus will be on a ds-shell isoscalar E2 study with detailed shell-model results providing the standard for comparison; similar results are available for isovector E2 and M1 and E4 transitions as well as for single-particle transfer and ν +- decay. The present study is intended to serve as a tutorial for applications where shell-model calculations are not feasible. The problem is posed and a schematic theory for strengths and sums is presented. The theory is extended to include the effect of correlations between H, the system Hamiltonian, and theta, the excitation operator. Associated with correlation measures is a geometry that can be used to anticipate the goodness of a symmetry. This is illustrated for pseudo SU(3) in the fp-shell. Some conclusions about fluctuations and collectivity that one can deduce from the statistical results for strengths are presented

  19. Comparison and Analysis of Steel Frame Based on High Strength Column and Normal Strength Column

    Science.gov (United States)

    Liu, Taiyu; An, Yuwei

    2018-01-01

    The anti-seismic performance of high strength steel has restricted its industrialization in civil buildings. In order to study the influence of high strength steel column on frame structure, three models are designed through MIDAS/GEN finite element software. By comparing the seismic performance and economic performance of the three models, the three different structures are comprehensively evaluated to provide some references for the development of high strength steel in steel structure.

  20. Updating impairments and the failure to explore new hypotheses following right brain damage.

    Science.gov (United States)

    Stöttinger, Elisabeth; Guay, Carolyn Louise; Danckert, James; Anderson, Britt

    2018-06-01

    We have shown recently that damage to the right hemisphere impairs the ability to update mental models when evidence suggests an old model is no longer appropriate. We argue that this deficit is generic in the sense that it crosses multiple cognitive and perceptual domains. Here, we examined the nature of this updating impairment to determine more precisely the underlying mechanisms. We had right (RBD, N = 12) and left brain damaged (LBD, N = 10) patients perform versions of our picture-morphing task in which pictures gradually morph from one object (e.g., shark) to another (e.g., plane). Performance was contrasted against two groups of healthy older controls, one matched on age (HCO-age-matched, N = 9) and another matched on general level of cognitive ability (HCO-cognitively-matched, N = 9). We replicated our earlier findings showing that RBD patients took longer than LBD patients and HCOs to report seeing the second object in a sequence of morphing images. The groups did not differ when exposed to a morphing sequence a second time, or when responding to ambiguous images outside the morphing context. This indicates that RBD patients have little difficulty alternating between known representations or labeling ambiguous images. Instead, the difficulty lies in generating alternate hypotheses for ambiguous information. Lesion overlay analyses, although speculative given the sample size, are consistent with our fMRI work in healthy individuals in implicating the anterior insular cortex as critical for updating mental models.

  1. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  2. High strength ferritic alloy

    International Nuclear Information System (INIS)

    1977-01-01

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  3. Photon strength functions

    International Nuclear Information System (INIS)

    Bergqvist, I.

    1976-01-01

    Methods for extracting photon strength functions are briefly discussed. We follow the Brink-Axel approach to relate the strength functions to the giant resonances observed in photonuclear work and summarize the available data on the E1, E2 and M1 resonances. Some experimental and theoretical problems are outlined. (author)

  4. Interviewing to Understand Strengths

    Science.gov (United States)

    Hass, Michael R.

    2018-01-01

    Interviewing clients about their strengths is an important part of developing a complete understanding of their lives and has several advantages over simply focusing on problems and pathology. Prerequisites for skillfully interviewing for strengths include the communication skills that emerge from a stance of not knowing, developing a vocabulary…

  5. pH-cycling models for in vitro evaluation of the efficacy of fluoridated dentifrices for caries control: strengths and limitations

    Directory of Open Access Journals (Sweden)

    Marília Afonso Rabelo Buzalaf

    2010-08-01

    Full Text Available Despite a plethora of in situ studies and clinical trials evaluating the efficacy of fluoridated dentifrices on caries control, in vitro pH cycling models are still broadly used because they mimic the dynamics of mineral loss and gain involved in caries formation. This paper critically reviews the current literature on existing pH-cycling models for the in vitro evaluation of the efficacy of fluoridated dentifrices for caries control, focusing on their strengths and limitations. A search was undertaken in the MEDLINE electronic journal database using the keywords "pH-cycling", "demineralization", "remineralization", "in vitro", "fluoride", "dentifrice". The primary outcome was the decrease of demineralization or the increase of remineralization as measured by different methods (e.g.: transverse microradiography or tooth fluoride uptake. Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. One hundred and sixteen studies were included, of which 42 addressed specifically the comparison of dentifrices using different pH-cycling models. The other studies included meta-analysis or reviews, data about the effect of different fluoride sources on de-remineralization, different methods for analysis de-remineralization and chemical variables and characteristics of dental hard tissues that might have influence on de-remineralization processes. Generally, the studies presented ability to detect known results established by clinical trials, to demonstrate dose-related responses in the fluoride content of the dentifrices, and to provide repeatability and reproducibility between tests. In order to accomplish these features satisfactorily, it is mandatory to take into account the type of substrate and baseline artificial lesion, as well as the adequate response variables and statistical approaches

  6. The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices.

    Science.gov (United States)

    Asare-Addo, Kofi; Conway, Barbara R; Larhrib, Hassan; Levina, Marina; Rajabi-Siahboomi, Ali R; Tetteh, John; Boateng, Joshua; Nokhodchi, Ali

    2013-11-01

    The evaluation of the effects of different media ionic strengths and pH on the release of hydrochlorothiazide, a poorly soluble drug, and diltiazem hydrochloride, a cationic and soluble drug, from a gel forming hydrophilic polymeric matrix was the objective of this study. The drug to polymer ratio of formulated tablets was 4:1. Hydrochlorothiazide or diltiazem HCl extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The ionic strength of the media was varied over a range of 0-0.4M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. Sodium chloride was used for ionic regulation due to its ability to salt out polymers in the midrange of the lyotropic series. The results showed that the ionic strength had a profound effect on the drug release from the diltiazem HCl K100LV matrices. The K4M, K15M and K100M tablets however withstood the effects of media ionic strength and showed a decrease in drug release to occur with an increase in ionic strength. For example, drug release after the 1h mark for the K100M matrices in water was 36%. Drug release in pH 1.2 after 1h was 30%. An increase of the pH 1.2 ionic strength to 0.4M saw a reduction of drug release to 26%. This was the general trend for the K4M and K15M matrices as well. The similarity factor f2 was calculated using drug release in water as a reference. Despite similarity occurring for all the diltiazem HCl matrices in the pH 1.2 media (f2=64-72), increases of ionic strength at 0.2M and 0.4M brought about dissimilarity. The hydrochlorothiazide tablet matrices showed similarity at all the ionic strength tested for all polymers (f2=56-81). The values of f2 however reduced with increasing ionic strengths. DSC hydration results explained the hydrochlorothiazide release from their HPMC matrices. There was an increase in

  7. The RNA-world and co-evolution hypotheses and the origin of life: Implications, research strategies and perspectives

    Science.gov (United States)

    Lahav, Noam

    1993-12-01

    The applicability of the RNA-world and co-evolution hypotheses to the study of the very first stages of the origin of life is discussed. The discussion focuses on the basic differences between the two hypotheses and their implications, with regard to the reconstruction methodology, ribosome emergence, balance between ribozymes and protein enzymes, and their major difficulties. Additional complexities of the two hypotheses, such as membranes and the energy source of the first reactions, are not treated in the present work. A central element in the proposed experimental strategies is the study of the catalytic activities of very small peptides and RNA-like oligomers, according to existing, as well as to yet-to-be-invented scenarios of the two hypotheses under consideration. It is suggested that the noveldirected molecular evolution technology, andmolecular computational modeling, can be applied to this research. This strategy is assumed to be essential for the suggested goal of future studies of the origin of life, namely, the establishment of a ‘Primordial Darwinian entity’.

  8. Relationship Between Neck Strength, Anthropometric Parameters, and Gender with Head Motion under Impact Acceleration

    National Research Council Canada - National Science Library

    Morris, Charles

    1996-01-01

    .... Since women tend to have less upper-body strength than men, it was hypothesized that they may not be able to brace their heads as effectively against the loads which occur during impact and escape...

  9. Black/White Differences in Adolescent Drug Use: A Test of Six Hypotheses

    Science.gov (United States)

    Rote, Sunshine M.; Taylor, John

    2014-01-01

    Six specific hypotheses have been developed to account for why Caucasians have higher rates of drug use compared to African-Americans. This article utilizes data from a South Florida-based community study of 893 young adults (1998-2002) to test these hypotheses. Specifically, Caucasians (1) initiate drug use at younger ages than African-Americans…

  10. Evaluating hypotheses in geolocation on a very large sample of Twitter

    DEFF Research Database (Denmark)

    Salehi, Bahar; Søgaard, Anders

    2017-01-01

    Recent work in geolocation has madeseveral hypotheses about what linguisticmarkers are relevant to detect where peoplewrite from. In this paper, we examinesix hypotheses against a corpus consistingof all geo-tagged tweets from theUS, or whose geo-tags could be inferred,in a 19% sample of Twitter...

  11. Reactor Core Coolability Analysis during Hypothesized Severe Accidents of OPR1000

    International Nuclear Information System (INIS)

    Lee, Yongjae; Seo, Seungwon; Kim, Sung Joong; Ha, Kwang Soon; Kim, Hwan-Yeol

    2014-01-01

    Assessment of the safety features over the hypothesized severe accidents may be performed experimentally or numerically. Due to the considerable time and expenditures, experimental assessment is implemented only to the limited cases. Therefore numerical assessment has played a major role in revisiting severe accident analysis of the existing or newly designed power plants. Computer codes for the numerical analysis of severe accidents are categorized as the fast running integral code and detailed code. Fast running integral codes are characterized by a well-balanced combination of detailed and simplified models for the simulation of the relevant phenomena within an NPP in the case of a severe accident. MAAP, MELCOR and ASTEC belong to the examples of fast running integral codes. Detailed code is to model as far as possible all relevant phenomena in detail by mechanistic models. The examples of detailed code is SCDAP/RELAP5. Using the MELCOR, Carbajo. investigated sensitivity studies of Station Black Out (SBO) using the MELCOR for Peach Bottom BWR. Park et al. conduct regulatory research of the PWR severe accident. Ahn et al. research sensitivity analysis of the severe accident for APR1400 with MELCOR 1.8.4. Lee et al. investigated RCS depressurization strategy and developed a core coolability map for independent scenarios of Small Break Loss-of-Coolant Accident (SBLOCA), SBO, and Total Loss of Feed Water (TLOFW). In this study, three initiating cases were selected, which are SBLOCA without SI, SBO, and TLOFW. The initiating cases exhibit the highest probability of transitioning into core damage according to PSA 1 of OPR 1000. The objective of this study is to investigate the reactor core coolability during hypothesized severe accidents of OPR1000. As a representative indicator, we have employed Jakob number and developed JaCET and JaMCT using the MELCOR simulation. Although the RCS pressures for the respective accident scenarios were different, the JaMCT and Ja

  12. Testing Biological Hypotheses with Embodied Robots: Adaptations, Accidents, and By-Products in the Evolution of Vertebrates

    OpenAIRE

    Roberts, Sonia F.; Hirokawa, Jonathan; Rosenblum, Hannah G.; Sakhtah, Hassan; Gutierrez, Andres A.; Porter, Marianne E.; Long, John H.

    2014-01-01

    Evolutionary robotics allows biologists to test hypotheses about extinct animals. In our case, we modeled some of the first vertebrates, jawless fishes, in order to study the evolution of the trait after which vertebrates are named: vertebrae. We tested the hypothesis that vertebrae are an adaptation for enhanced feeding and fleeing performance. We created a population of autonomous embodied robots, Preyro, in which the number of vertebrae, N, were free to evolve. In addition, two other trait...

  13. Opposite phenotypes of muscle strength and locomotor function in mouse models of partial trisomy and monosomy 21 for the proximal Hspa13-App region.

    Directory of Open Access Journals (Sweden)

    Véronique Brault

    2015-03-01

    Full Text Available The trisomy of human chromosome 21 (Hsa21, which causes Down syndrome (DS, is the most common viable human aneuploidy. In contrast to trisomy, the complete monosomy (M21 of Hsa21 is lethal, and only partial monosomy or mosaic monosomy of Hsa21 is seen. Both conditions lead to variable physiological abnormalities with constant intellectual disability, locomotor deficits, and altered muscle tone. To search for dosage-sensitive genes involved in DS and M21 phenotypes, we created two new mouse models: the Ts3Yah carrying a tandem duplication and the Ms3Yah carrying a deletion of the Hspa13-App interval syntenic with 21q11.2-q21.3. Here we report that the trisomy and the monosomy of this region alter locomotion, muscle strength, mass, and energetic balance. The expression profiling of skeletal muscles revealed global changes in the regulation of genes implicated in energetic metabolism, mitochondrial activity, and biogenesis. These genes are downregulated in Ts3Yah mice and upregulated in Ms3Yah mice. The shift in skeletal muscle metabolism correlates with a change in mitochondrial proliferation without an alteration in the respiratory function. However, the reactive oxygen species (ROS production from mitochondrial complex I decreased in Ms3Yah mice, while the membrane permeability of Ts3Yah mitochondria slightly increased. Thus, we demonstrated how the Hspa13-App interval controls metabolic and mitochondrial phenotypes in muscles certainly as a consequence of change in dose of Gabpa, Nrip1, and Atp5j. Our results indicate that the copy number variation in the Hspa13-App region has a peripheral impact on locomotor activity by altering muscle function.

  14. Opposite phenotypes of muscle strength and locomotor function in mouse models of partial trisomy and monosomy 21 for the proximal Hspa13-App region.

    Science.gov (United States)

    Brault, Véronique; Duchon, Arnaud; Romestaing, Caroline; Sahun, Ignasi; Pothion, Stéphanie; Karout, Mona; Borel, Christelle; Dembele, Doulaye; Bizot, Jean-Charles; Messaddeq, Nadia; Sharp, Andrew J; Roussel, Damien; Antonarakis, Stylianos E; Dierssen, Mara; Hérault, Yann

    2015-03-01

    The trisomy of human chromosome 21 (Hsa21), which causes Down syndrome (DS), is the most common viable human aneuploidy. In contrast to trisomy, the complete monosomy (M21) of Hsa21 is lethal, and only partial monosomy or mosaic monosomy of Hsa21 is seen. Both conditions lead to variable physiological abnormalities with constant intellectual disability, locomotor deficits, and altered muscle tone. To search for dosage-sensitive genes involved in DS and M21 phenotypes, we created two new mouse models: the Ts3Yah carrying a tandem duplication and the Ms3Yah carrying a deletion of the Hspa13-App interval syntenic with 21q11.2-q21.3. Here we report that the trisomy and the monosomy of this region alter locomotion, muscle strength, mass, and energetic balance. The expression profiling of skeletal muscles revealed global changes in the regulation of genes implicated in energetic metabolism, mitochondrial activity, and biogenesis. These genes are downregulated in Ts3Yah mice and upregulated in Ms3Yah mice. The shift in skeletal muscle metabolism correlates with a change in mitochondrial proliferation without an alteration in the respiratory function. However, the reactive oxygen species (ROS) production from mitochondrial complex I decreased in Ms3Yah mice, while the membrane permeability of Ts3Yah mitochondria slightly increased. Thus, we demonstrated how the Hspa13-App interval controls metabolic and mitochondrial phenotypes in muscles certainly as a consequence of change in dose of Gabpa, Nrip1, and Atp5j. Our results indicate that the copy number variation in the Hspa13-App region has a peripheral impact on locomotor activity by altering muscle function.

  15. Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength

    DEFF Research Database (Denmark)

    Jæger, Pia Therese; Nielsen, Zbigniew Jerzy Koscielniak; Henningsen, Lene Marianne

    2013-01-01

    : The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5-6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints were...

  16. Strength training for the warfighter.

    Science.gov (United States)

    Kraemer, William J; Szivak, Tunde K

    2012-07-01

    Optimizing strength training for the warfighter is challenged by past training philosophies that no longer serve the modern warfighter facing the "anaerobic battlefield." Training approaches for integration of strength with other needed physical capabilities have been shown to require a periodization model that has the flexibility for changes and is able to adapt to ever-changing circumstances affecting the quality of workouts. Additionally, sequencing of workouts to limit over-reaching and development of overtraining syndromes that end in loss of duty time and injury are paramount to long-term success. Allowing adequate time for rest and recovery and recognizing the negative influences of extreme exercise programs and excessive endurance training will be vital in moving physical training programs into a more modern perspective as used by elite strength-power anaerobic athletes in sports today. Because the warfighter is an elite athlete, it is time that training approaches that are scientifically based are updated within the military to match the functional demands of modern warfare and are given greater credence and value at the command levels. A needs analysis, development of periodized training modules, and individualization of programs are needed to optimize the strength of the modern warfighter. We now have the knowledge, professional coaches and nonprofit organization certifications with continuing education units, and modern training technology to allow this to happen. Ultimately, it only takes command decisions and implementation to make this possible.

  17. Prediction of bone strength by μCT and MDCT-based finite-element-models: How much spatial resolution is needed?

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Jan S., E-mail: jsb@tum.de [Department of Radiology, Technische Universität München, Munich (Germany); Department of Radiology, University of California, San Francisco, CA (United States); Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Sidorenko, Irina [Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Mueller, Dirk [Department of Radiology, Universität Köln (Germany); Baum, Thomas [Department of Radiology, Technische Universität München, Munich (Germany); Department of Radiology, University of California, San Francisco, CA (United States); Max Planck Institute for Extraterrestrial Physics, Garching (Germany); Issever, Ahi Sema [Department of Radiology, University of California, San Francisco, CA (United States); Department of Radiology, Charite, Berlin (Germany); Eckstein, Felix [Institute of Anatomy and Musculoskeletal Research, Paracelsus Medical University, Salzburg (Austria); Rummeny, Ernst J. [Department of Radiology, Technische Universität München, Munich (Germany); Link, Thomas M. [Department of Radiology, University of California, San Francisco, CA (United States); Raeth, Christoph W. [Max Planck Institute for Extraterrestrial Physics, Garching (Germany)

    2014-01-15

    Objectives: Finite-element-models (FEM) are a promising technology to predict bone strength and fracture risk. Usually, the highest spatial resolution technically available is used, but this requires excessive computation time and memory in numerical simulations of large volumes. Thus, FEM were compared at decreasing resolutions with respect to local strain distribution and prediction of failure load to (1) validate MDCT-based FEM and to (2) optimize spatial resolution to save computation time. Materials and methods: 20 cylindrical trabecular bone specimens (diameter 12 mm, length 15–20 mm) were harvested from elderly formalin-fixed human thoracic spines. All specimens were examined by micro-CT (isotropic resolution 30 μm) and whole-body multi-row-detector computed tomography (MDCT, 250 μm × 250 μm × 500 μm). The resolution of all datasets was lowered in eight steps to ∼2000 μm × 2000 μm × 500 μm and FEM were calculated at all resolutions. Failure load was determined by biomechanical testing. Probability density functions of local micro-strains were compared in all datasets and correlations between FEM-based and biomechanically measured failure loads were determined. Results: The distribution of local micro-strains was similar for micro-CT and MDCT at comparable resolutions and showed a shift toward higher average values with decreasing resolution, corresponding to the increasing apparent trabecular thickness. Small micro-strains (ε{sub eff} < 0.005) could be calculated down to 250 μm × 250 μm × 500 μm. Biomechanically determined failure load showed significant correlations with all FEM, up to r = 0.85 and did not significantly change with lower resolution but decreased with high thresholds, due to loss of trabecular connectivity. Conclusion: When choosing connectivity-preserving thresholds, both micro-CT- and MDCT-based finite-element-models well predicted failure load and still accurately revealed the distribution of local micro-strains in

  18. Prediction of bone strength by μCT and MDCT-based finite-element-models: How much spatial resolution is needed?

    International Nuclear Information System (INIS)

    Bauer, Jan S.; Sidorenko, Irina; Mueller, Dirk; Baum, Thomas; Issever, Ahi Sema; Eckstein, Felix; Rummeny, Ernst J.; Link, Thomas M.; Raeth, Christoph W.

    2014-01-01

    Objectives: Finite-element-models (FEM) are a promising technology to predict bone strength and fracture risk. Usually, the highest spatial resolution technically available is used, but this requires excessive computation time and memory in numerical simulations of large volumes. Thus, FEM were compared at decreasing resolutions with respect to local strain distribution and prediction of failure load to (1) validate MDCT-based FEM and to (2) optimize spatial resolution to save computation time. Materials and methods: 20 cylindrical trabecular bone specimens (diameter 12 mm, length 15–20 mm) were harvested from elderly formalin-fixed human thoracic spines. All specimens were examined by micro-CT (isotropic resolution 30 μm) and whole-body multi-row-detector computed tomography (MDCT, 250 μm × 250 μm × 500 μm). The resolution of all datasets was lowered in eight steps to ∼2000 μm × 2000 μm × 500 μm and FEM were calculated at all resolutions. Failure load was determined by biomechanical testing. Probability density functions of local micro-strains were compared in all datasets and correlations between FEM-based and biomechanically measured failure loads were determined. Results: The distribution of local micro-strains was similar for micro-CT and MDCT at comparable resolutions and showed a shift toward higher average values with decreasing resolution, corresponding to the increasing apparent trabecular thickness. Small micro-strains (ε eff < 0.005) could be calculated down to 250 μm × 250 μm × 500 μm. Biomechanically determined failure load showed significant correlations with all FEM, up to r = 0.85 and did not significantly change with lower resolution but decreased with high thresholds, due to loss of trabecular connectivity. Conclusion: When choosing connectivity-preserving thresholds, both micro-CT- and MDCT-based finite-element-models well predicted failure load and still accurately revealed the distribution of local micro-strains in spatial

  19. Annotation of selection strengths in viral genomes

    DEFF Research Database (Denmark)

    McCauley, Stephen; de Groot, Saskia; Mailund, Thomas

    2007-01-01

    Motivation: Viral genomes tend to code in overlapping reading frames to maximize information content. This may result in atypical codon bias and particular evolutionary constraints. Due to the fast mutation rate of viruses, there is additional strong evidence for varying selection between intra......- and intergenomic regions. The presence of multiple coding regions complicates the concept of Ka/Ks ratio, and thus begs for an alternative approach when investigating selection strengths. Building on the paper by McCauley & Hein (2006), we develop a method for annotating a viral genome coding in overlapping...... may thus achieve an annotation both of coding regions as well as selection strengths, allowing us to investigate different selection patterns and hypotheses. Results: We illustrate our method by applying it to a multiple alignment of four HIV2 sequences, as well as four Hepatitis B sequences. We...

  20. Analysis of Lithospheric Stresses Using Satellite Gravimetry: Hypotheses and Applications to North Atlantic

    Science.gov (United States)

    Minakov, A.; Medvedev, S.

    2017-12-01

    Analysis of lithospheric stresses is necessary to gain understanding of the forces that drive plate tectonics and intraplate deformations and the structure and strength of the lithosphere. A major source of lithospheric stresses is believed to be in variations of surface topography and lithospheric density. The traditional approach to stress estimation is based on direct calculations of the Gravitational Potential Energy (GPE), the depth integrated density moment of the lithosphere column. GPE is highly sensitive to density structure which, however, is often poorly constrained. Density structure of the lithosphere may be refined using methods of gravity modeling. However, the resulted density models suffer from non-uniqueness of the inverse problem. An alternative approach is to directly estimate lithospheric stresses (depth integrated) from satellite gravimetry data. Satellite gravity gradient measurements by the ESA GOCE mission ensures a wealth of data for mapping lithospheric stresses if a link between data and stresses or GPE can be established theoretically. The non-uniqueness of interpretation of sources of the gravity signal holds in this case as well. Therefore, the data analysis was tested for the North Atlantic region where reliable additional constraints are supplied by both controlled-source and earthquake seismology. The study involves comparison of three methods of stress modeling: (1) the traditional modeling approach using a thin sheet approximation; (2) the filtered geoid approach; and (3) the direct utilization of the gravity gradient tensor. Whereas the first two approaches (1)-(2) calculate GPE and utilize a computationally expensive finite element mechanical modeling to calculate stresses, the approach (3) uses a much simpler numerical treatment but requires simplifying assumptions that yet to be tested. The modeled orientation of principal stresses and stress magnitudes by each of the three methods are compared with the World Stress Map.

  1. Do Job Demands of Chinese Manufacturing Employees Predict Positive or Negative Outcomes? A Test of Competing Hypotheses.

    Science.gov (United States)

    Cheung, Janelle H; Sinclair, Robert R; Shi, Junqi; Wang, Mo

    2015-12-01

    Karasek's job demands-control (JDC) model posits that job control can buffer against the harmful effects of demands experienced by employees. A large volume of JDC research has obtained support for the main effects of demands and control, but not the interactive effects. Recent research on the challenge-hindrance stressors framework, however, found that work stressors may not always be deleterious, suggesting alternative hypotheses about the effects of demands and control. The present study therefore examined competing hypotheses concerning the effects of job demands on occupational health outcomes. Using a sample of 316 employees in a Chinese manufacturing company, we found that, consistent with the challenge-hindrance framework, production demands were challenge stressors associated with favourable outcomes (i.e. job satisfaction and psychological well-being). In addition, results showed that the interactive role of job control depended on the nature of outcome variables. Future recommendations and implications of findings are discussed. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Family Stress and Parental Responses to Children’s Negative Emotions: Tests of the Spillover, Crossover, and Compensatory Hypotheses

    Science.gov (United States)

    Nelson, Jackie A.; O’Brien, Marion; Blankson, A. Nayena; Calkins, Susan D.; Keane, Susan P.

    2010-01-01

    The relations between 4 sources of family stress (marital dissatisfaction, home chaos, parental depressive symptoms, and job role dissatisfaction) and the emotion socialization practice of mothers’ and fathers’ responses to children’s negative emotions were examined. Participants included 101 couples with 7-year-old children. Dyadic analyses were conducted using the Actor–Partner Interdependence Model and relations were tested in terms of the spillover, crossover, and compensatory hypotheses. Results suggest that measures of family stress relate to supportive and nonsupportive parental responses, though many of these relations differ by parent gender. The results are discussed in terms of the 3 theoretical hypotheses, all of which are supported to some degree depending on the family stressor examined. PMID:19803603

  3. Family stress and parental responses to children's negative emotions: tests of the spillover, crossover, and compensatory hypotheses.

    Science.gov (United States)

    Nelson, Jackie A; O'Brien, Marion; Blankson, A Nayena; Calkins, Susan D; Keane, Susan P

    2009-10-01

    The relations between 4 sources of family stress (marital dissatisfaction, home chaos, parental depressive symptoms, and job role dissatisfaction) and the emotion socialization practice of mothers' and fathers' responses to children's negative emotions were examined. Participants included 101 couples with 7-year-old children. Dyadic analyses were conducted using the Actor-Partner Interdependence Model and relations were tested in terms of the spillover, crossover, and compensatory hypotheses. Results suggest that measures of family stress relate to supportive and nonsupportive parental responses, though many of these relations differ by parent gender. The results are discussed in terms of the 3 theoretical hypotheses, all of which are supported to some degree depending on the family stressor examined.

  4. Behaviour and strength assessment of masonry prisms

    Directory of Open Access Journals (Sweden)

    Nassif Nazeer Thaickavil

    2018-06-01

    Full Text Available This is a case study presenting the cracking behavior and assessment of the compressive strength of masonry prisms. The compressive strength of masonry was determined by performing laboratory tests on 192 masonry prism specimens corresponding to 3 specimens each in 64 groups. The variables considered in the experimental program are type of brick, strength of masonry and height-to-thickness (h/t ratio of the prism specimen. Pressed earth bricks and burnt clay bricks were used for the preparation of masonry prisms. A mathematical model is also proposed for the estimation of compressive strength of masonry prisms by performing a statistical multiple regression analysis on 232 data sets, which includes 64 test data from the present study and 168 test data published in the literature. The model was developed based on the regression analysis of test data of prisms made of a variety of masonry units namely clay bricks, pressed earth bricks, concrete blocks, calcium silicate bricks, stone blocks, perforated bricks and soft mud bricks. The proposed model not only accounts for the wide ranges of compressive strengths of masonry unit and mortar, but also accounts for the influence of volume fractions of masonry unit and mortar in addition to the height-to-thickness ratio. The predicted compressive strength of prisms using the proposed model is compared with 14 models available in published literature. The predicted strength was found to be in good agreement with the corresponding experimental data. Keywords: Prism strength, Stack bonded masonry, Running bonded masonry, Masonry unit strength, Cracking

  5. Detection of rock strength at Branisko massif

    Directory of Open Access Journals (Sweden)

    Lazarová Edita

    2000-09-01

    Full Text Available When monitoring and optimizing the driving proces of the exploratory gallery by a computer system, conditions for verification of the interaction between desintegrating head of driving machine and rock massif were created. One of the output values of this mathematical model is the model strength at a simple pressure ótlH, which is defined as a pressure at the discus and the massif contact during the desintigration (a near limit of massif strength. By geological and geological engineering exploration, the section of length 2340 m was divided into fourty-two geological sections and five quasi-homogeneous massif enviroments. In the article, results of scleroscopic strength óCI , the strength in a simple pressure determined from the point load test and the strength at simple pressure ótlH are confronted . The main advance of the electronic geomechanical monitoring is the density of gained information. The two-seconds sample period of input and output data during the driving process makes it possible to describe driving circumstances in an almost continual way for each millimeter of the built tunnel. Then the information about changes of disintegrated rock properties, have the same density (frequency. By comparing a quantity of data gained by examining the index of point strength, scleroscopic strength and the model strength in a simple pressure from the monitoring process of driving process it is obvious that during the driving of exploratory gallery of motorway tunnel Branisko, a proportion of data number from the three “type examinations” of strength was reached and it was approximately 1:7:5000. Approximately in the same proportion, there were determined values for the 42 geologic sections (I. – XLII., which were defined in detail by the geologic, engineering geologic, hydrogeologic and geotechnic research.. The presented quantity values of presented rock mass strength for each geologic section are presented by their arithmetic average

  6. Situational Strength Cues from Social Sources at Work: Relative Importance and Mediated Effects.

    Science.gov (United States)

    Alaybek, Balca; Dalal, Reeshad S; Sheng, Zitong; Morris, Alexander G; Tomassetti, Alan J; Holland, Samantha J

    2017-01-01

    Situational strength is considered one of the most important situational forces at work because it can attenuate the personality-performance relationship. Although organizational scholars have studied the consequences of situational strength, they have paid little attention to its antecedents. To address this gap, the current study focused on situational strength cues from different social sources as antecedents of overall situational strength at work. Specifically, we examined how employees combine situational strength cues emanating from three social sources (i.e., coworkers, the immediate supervisor, and top management). Based on field theory, we hypothesized that the effect of situational strength from coworkers and immediate supervisors (i.e., proximal sources of situational strength) on employees' perceptions of overall situational strength on the job would be greater than the effect of situational strength from the top management (i.e., the distal source of situational strength). We also hypothesized that the effect of situational strength from the distal source would be mediated by the effects of situational strength from the proximal sources. Data from 363 full-time employees were collected at two time points with a cross-lagged panel design. The former hypothesis was supported for one of the two situational strength facets studied. The latter hypothesis was fully supported.

  7. Situational Strength Cues from Social Sources at Work: Relative Importance and Mediated Effects

    Directory of Open Access Journals (Sweden)

    Balca Alaybek

    2017-09-01

    Full Text Available Situational strength is considered one of the most important situational forces at work because it can attenuate the personality–performance relationship. Although organizational scholars have studied the consequences of situational strength, they have paid little attention to its antecedents. To address this gap, the current study focused on situational strength cues from different social sources as antecedents of overall situational strength at work. Specifically, we examined how employees combine situational strength cues emanating from three social sources (i.e., coworkers, the immediate supervisor, and top management. Based on field theory, we hypothesized that the effect of situational strength from coworkers and immediate supervisors (i.e., proximal sources of situational strength on employees' perceptions of overall situational strength on the job would be greater than the effect of situational strength from the top management (i.e., the distal source of situational strength. We also hypothesized that the effect of situational strength from the distal source would be mediated by the effects of situational strength from the proximal sources. Data from 363 full-time employees were collected at two time points with a cross-lagged panel design. The former hypothesis was supported for one of the two situational strength facets studied. The latter hypothesis was fully supported.

  8. Evaluation of hypotheses for the cause of the 1886 Charleston earthquake

    Energy Technology Data Exchange (ETDEWEB)

    White, R.M.; Long, L.T. (Law Environmental, Inc., Kennesaw, GA (USA); Georgia Inst. of Tech., Atlanta, GA (USA))

    1989-10-01

    This report describes a geophysical/geological investigation of the earth's crust at seismogenic depths in the Charleston, South Carolina area. This investigation was made for the purpose of narrowing the range of theories that have been used to explain the historic 1886 Charleston earthquake. Since a number of these theories are based on only a portion of the available data, we have established a comprehensive data set in order to allow these hypotheses to be subjected to the entire data set. Specifically, we combined existing and new gravity, magnetic and topographic data in grids of 128 km, 256 km and 1028 km on a side centered on Charleston. Seismic, geologic and drilling data were collected and summarized. A magnetotelluric survey consisting of 12 soundings interpreted to depths of over 40 kilometers defined the bottom of the rigid crust with assistance from seismic reflection and other data. A geologic model of the crust in the area of Charleston was constructed and it defined the locations of Triassic/Jurassic basins Paleozoic plutons in greater detail than has previously been achieved. 102 refs., 75 figs.

  9. Recruitment processes in Baltic sprat - A re-evaluation of GLOBEC Germany hypotheses

    DEFF Research Database (Denmark)

    Voss, Rudiger; Peck, M.A.; Hinrichsen, H.-H.

    2012-01-01

    The GLOBEC Germany program (2002–2007) had the ambitious goal to resolve the processes impacting the recruitment dynamics ofBalticsprat (Sprattus sprattus L.) by examining various factors affecting early life history stages. At the start of the research program, a number of general recruitmenthyp......The GLOBEC Germany program (2002–2007) had the ambitious goal to resolve the processes impacting the recruitment dynamics ofBalticsprat (Sprattus sprattus L.) by examining various factors affecting early life history stages. At the start of the research program, a number of general......, and modeling studies to re-evaluate these hypotheses for the Balticsprat stock. Recruitment success was quite different in the 2 years investigated. Despite a lower spawning stock biomass in 2003, the total number of recruits was almost 2-fold higher that year compared to 2002. The higher recruitment success...... in 2003 could be attributed to enhanced survival success during the post-larval/juvenile stage, a life phase that appears to be critical for recruitment dynamics. In the state of the Baltic ecosystem during the period of investigation, we consider bottom-up control (e.g. temperature, prey abundance...

  10. Evaluation of hypotheses for the cause of the 1886 Charleston earthquake

    International Nuclear Information System (INIS)

    White, R.M.; Long, L.T.

    1989-10-01

    This report describes a geophysical/geological investigation of the earth's crust at seismogenic depths in the Charleston, South Carolina area. This investigation was made for the purpose of narrowing the range of theories that have been used to explain the historic 1886 Charleston earthquake. Since a number of these theories are based on only a portion of the available data, we have established a comprehensive data set in order to allow these hypotheses to be subjected to the entire data set. Specifically, we combined existing and new gravity, magnetic and topographic data in grids of 128 km, 256 km and 1028 km on a side centered on Charleston. Seismic, geologic and drilling data were collected and summarized. A magnetotelluric survey consisting of 12 soundings interpreted to depths of over 40 kilometers defined the bottom of the rigid crust with assistance from seismic reflection and other data. A geologic model of the crust in the area of Charleston was constructed and it defined the locations of Triassic/Jurassic basins Paleozoic plutons in greater detail than has previously been achieved. 102 refs., 75 figs

  11. Basal tissue structure in the earliest euconodonts: Testing hypotheses of developmental plasticity in euconodont phylogeny

    Science.gov (United States)

    Dong, X.-P.; Donoghue, P.C.J.; Repetski, J.E.

    2005-01-01

    The hypothesis that conodonts are vertebrates rests solely on evidence of soft tissue anatomy. This has been corroborated by microstructural, topological and developmental evidence of homology between conodont and vertebrate hard tissues. However, these conclusions have been reached on the basis of evidence from highly derived euconodont taxa and the degree to which they are representative of plesiomorphic euconodonts remains an open question. Furthermore, the range of variation in tissue types comprising the euconodont basal body has been used to establish a hypothesis of developmental plasticity early in the phylogeny of the clade, and a model of diminishing potentiality in the evolution of development systems. The microstructural fabrics of the basal tissues of the earliest euconodonts (presumed to be the most plesiomorphic) are examined to test these two hypotheses. It is found that the range of microstructural variation observed hitherto was already apparent among plesiomorphic euconodonts. Thus, established histological data are representative of the most plesiomorphic euconodonts. However, although there is evidence of a range in microstructural fabrics, these are compatible with the dentine tissue system alone, and the degree of variation is compatible with that seen in clades of comparable diversity. ?? The Palaeontological Association.

  12. 3D tooth microwear texture analysis in fishes as a test of dietary hypotheses of durophagy

    Science.gov (United States)

    Purnell, Mark A.; Darras, Laurent P. G.

    2016-03-01

    An understanding of how extinct animals functioned underpins our understanding of past evolutionary events, including adaptive radiations, and the role of functional innovation and adaptation as drivers of both micro- and macroevolution. Yet analysis of function in extinct animals is fraught with difficulty. Hypotheses that interpret molariform teeth in fishes as evidence of durophagous (shell-crushing) diets provide a good example of the particular problems inherent in the methods of functional morphology. This is because the assumed close coupling of form and function upon which the approach is based is weakened by, among other things, behavioural flexibility and the absence of a clear one to one relationship between structures and functions. Here we show that ISO 25178-2 standard parameters for surface texture, derived from analysis of worn surfaces of molariform teeth of fishes, vary significantly between species that differ in the amount of hard-shelled prey they consume. Two populations of the Sheepshead Seabream (Archosargus probatocephalus) were studied. This fish is not a dietary specialist, and one of the populations is known to consume more vegetation and less hard-shelled prey than the other; this is reflected in significant differences in their microwear textures. The Archosargus populations differ significantly in their microwear from the specialist shell-crusher Anarhichas lupus (the Atlantic Wolffish). Multivariate analysis of these three groups of fishes lends further support to the relationship between diet and tooth microwear, and provides robust validation of the approach. Application of the multivariate models derived from microwear texture in Archosargus and Anarhichas to a third fish species—the cichlid Astatoreochromis alluaudi—successfully separates wild caught fish that ate hard-shelled prey from lab-raised fish that did not. This cross-taxon validation demonstrates that quantitative analysis of tooth microwear texture can

  13. Evolution of microgastropods (Ellobioidea, Carychiidae): integrating taxonomic, phylogenetic and evolutionary hypotheses

    Science.gov (United States)

    2013-01-01

    Background Current biodiversity patterns are considered largely the result of past climatic and tectonic changes. In an integrative approach, we combine taxonomic and phylogenetic hypotheses to analyze temporal and geographic diversification of epigean (Carychium) and subterranean (Zospeum) evolutionary lineages in Carychiidae (Eupulmonata, Ellobioidea). We explicitly test three hypotheses: 1) morphospecies encompass unrecognized evolutionary lineages, 2) limited dispersal results in a close genetic relationship of geographical proximally distributed taxa and 3) major climatic and tectonic events had an impact on lineage diversification within Carychiidae. Results Initial morphospecies assignments were investigated by different molecular delimitation approaches (threshold, ABGD, GMYC and SP). Despite a conservative delimitation strategy, carychiid morphospecies comprise a great number of unrecognized evolutionary lineages. We attribute this phenomenon to historic underestimation of morphological stasis and phenotypic variability amongst lineages. The first molecular phylogenetic hypothesis for the Carychiidae (based on COI, 16S and H3) reveals Carychium and Zospeum to be reciprocally monophyletic. Geographical proximally distributed lineages are often closely related. The temporal diversification of Carychiidae is best described by a constant rate model of diversification. The evolution of Carychiidae is characterized by relatively few (long distance) colonization events. We find support for an Asian origin of Carychium. Zospeum may have arrived in Europe before extant members of Carychium. Distantly related Carychium clades inhabit a wide spectrum of the available bioclimatic niche and demonstrate considerable niche overlap. Conclusions Carychiid taxonomy is in dire need of revision. An inferred wide distribution and variable phenotype suggest underestimated diversity in Zospeum. Several Carychium morphospecies are results of past taxonomic lumping. By collecting

  14. 3D tooth microwear texture analysis in fishes as a test of dietary hypotheses of durophagy

    International Nuclear Information System (INIS)

    Purnell, Mark A; Darras, Laurent P G

    2016-01-01

    An understanding of how extinct animals functioned underpins our understanding of past evolutionary events, including adaptive radiations, and the role of functional innovation and adaptation as drivers of both micro- and macroevolution. Yet analysis of function in extinct animals is fraught with difficulty. Hypotheses that interpret molariform teeth in fishes as evidence of durophagous (shell-crushing) diets provide a good example of the particular problems inherent in the methods of functional morphology. This is because the assumed close coupling of form and function upon which the approach is based is weakened by, among other things, behavioural flexibility and the absence of a clear one to one relationship between structures and functions. Here we show that ISO 25178-2 standard parameters for surface texture, derived from analysis of worn surfaces of molariform teeth of fishes, vary significantly between species that differ in the amount of hard-shelled prey they consume. Two populations of the Sheepshead Seabream (Archosargus probatocephalus) were studied. This fish is not a dietary specialist, and one of the populations is known to consume more vegetation and less hard-shelled prey than the other; this is reflected in significant differences in their microwear textures. The Archosargus populations differ significantly in their microwear from the specialist shell-crusher Anarhichas lupus (the Atlantic Wolffish). Multivariate analysis of these three groups of fishes lends further support to the relationship between diet and tooth microwear, and provides robust validation of the approach. Application of the multivariate models derived from microwear texture in Archosargus and Anarhichas to a third fish species—the cichlid Astatoreochromis alluaudi—successfully separates wild caught fish that ate hard-shelled prey from lab-raised fish that did not. This cross-taxon validation demonstrates that quantitative analysis of tooth microwear texture can

  15. Accumulative job demands and support for strength use : Fine-tuning the job demands-resources model using conservation of resources theory

    NARCIS (Netherlands)

    van Woerkom, M.; Bakker, A.B.; Nishii, L.H.

    2016-01-01

    Absenteeism associated with accumulated job demands is a ubiquitous problem. We build on prior research on the benefits of counteracting job demands with resources by focusing on a still untapped resource for buffering job demands—that of strengths use. We test the idea that employees who are

  16. TGF-β1 Improves Biomechanical Strength by Extracellular Matrix Accumulation Without Increasing the Number of Tenogenic Lineage Cells in a Rat Rotator Cuff Repair Model.

    Science.gov (United States)

    Arimura, Hitoshi; Shukunami, Chisa; Tokunaga, Takuya; Karasugi, Tatsuki; Okamoto, Nobukazu; Taniwaki, Takuya; Sakamoto, Hidetoshi; Mizuta, Hiroshi; Hiraki, Yuji

    2017-08-01

    Transforming growth factor β1 (TGF-β1) positively regulates the tenogenic marker genes scleraxis ( Scx) and tenomodulin ( Tnmd) in mesenchymal progenitors in vitro. However, little is known about the effect of TGF-β1 on the expression of tenogenic markers during rotator cuff (RC) healing in rats. TGF-β1 improves the biomechanical properties and histological maturity of reparative tissue in a rat RC repair model by stimulating the growth of tenogenic cells. Controlled laboratory study. Adult male Sprague-Dawley rats (N = 180) underwent unilateral supraspinatus tendon-to-bone surgical repair and were randomly treated with a gelatin hydrogel presoaked in TGF-β1 (100 ng) or phosphate-buffered saline. The effects of TGF-β1 on RC healing were investigated at 2, 4, 6, 8, and 12 weeks postoperatively by immunostaining for proliferating cell nuclear antigen, by real-time reverse transcription polymerase chain reaction and in situ hybridization or immunostaining for enthesis-related markers (SRY-box containing gene 9 [ Sox9], Scx, and Tnmd), and by real-time reverse transcription polymerase chain reaction and immunostaining for type I and III collagen. At 6 and 12 weeks postoperatively, biomechanical testing, micro-computed tomography, and biochemical analysis were also performed. At 2 and 4 weeks postoperatively, mesenchymal stem cell-related markers, phospho-Smad2, and matrix metalloproteinase 9 (MMP-9) and MMP-13 were assessed by immunostaining. The TGF-β1-treated group had significantly higher ultimate load to failure and tissue volume at 6 and 12 weeks postoperatively and a higher collagen content at 12 weeks compared with the saline group. Tendon-related gene expression, histological maturity, cell proliferation, and mesenchymal stem cell-related marker immunoreactivity were not affected by exogenously administrated TGF-β1 at all time points. In the TGF-β1-treated group, the percentage of phospho-Smad2-positive cells within the healing tissue increased

  17. Serial Learning Process: Test of Chaining, Position, and Dual-Process Hypotheses

    Science.gov (United States)

    Giurintano, S. L.

    1973-01-01

    The chaining, position, and dual-process hypotheses of serial learning (SL) as well as serial recall, reordering, and relearning of paired-associate learning were examined to establish learning patterns. Results provide evidence for dual-process hypothesis. (DS)

  18. A criterion for testing hypotheses about the covariance function of a stationary Gaussian stochastic process

    OpenAIRE

    Kozachenko, Yuriy; Troshki, Viktor

    2015-01-01

    We consider a measurable stationary Gaussian stochastic process. A criterion for testing hypotheses about the covariance function of such a process using estimates for its norm in the space $L_p(\\mathbb {T}),\\,p\\geq1$, is constructed.

  19. Testing contingency hypotheses in budgetary research: An evaluation of the use of moderated regression analysis

    NARCIS (Netherlands)

    Hartmann, Frank G.H.; Moers, Frank

    1999-01-01

    In the contingency literature on the behavioral and organizational effects of budgeting, use of the Moderated Regression Analysis (MRA) technique is prevalent. This technique is used to test contingency hypotheses that predict interaction effects between budgetary and contextual variables. This

  20. A novel approach to generating CER hypotheses based on mining clinical data.

    Science.gov (United States)

    Zhang, Shuo; Li, Lin; Yu, Yiqin; Sun, Xingzhi; Xu, Linhao; Zhao, Wei; Teng, Xiaofei; Pan, Yue

    2013-01-01

    Comparative effectiveness research (CER) is a scientific method of investigating the effectiveness of alternative intervention methods. In a CER study, clinical researchers typically start with a CER hypothesis, and aim to evaluate it by applying a series of medical statistical methods. Traditionally, the CER hypotheses are defined manually by clinical researchers. This makes the task of hypothesis generation very time-consuming and the quality of hypothesis heavily dependent on the researchers' skills. Recently, with more electronic medical data being collected, it is highly promising to apply the computerized method for discovering CER hypotheses from clinical data sets. In this poster, we proposes a novel approach to automatically generating CER hypotheses based on mining clinical data, and presents a case study showing that the approach can facilitate clinical researchers to identify potentially valuable hypotheses and eventually define high quality CER studies.