WorldWideScience

Sample records for modelling context dependency

  1. Context dependent DNA evolutionary models

    DEFF Research Database (Denmark)

    Jensen, Jens Ledet

    This paper is about stochastic models for the evolution of DNA. For a set of aligned DNA sequences, connected in a phylogenetic tree, the models should be able to explain - in probabilistic terms - the differences seen in the sequences. From the estimates of the parameters in the model one can...

  2. A Context-dependent Service Model

    Directory of Open Access Journals (Sweden)

    Naseem Ibrahim

    2014-12-01

    Full Text Available In service-oriented systems a service invariably is bound to a contract. This contract includes the functionalities and quality of services guarantees that the provider can make. But such guarantees are not absolute. A service cannot guarantee its contract in all situations. It can only guarantee its contract in a predefined set of conditions. These conditions are usually related to the context of the service provider and requester. Yet, most of service-oriented applications use only service functionality as the basis of providing services and building system compositions. To remedy this situation, in this article both functionality and contract of a service are integrated into a single concept, called ConfiguredService, and formalized as a higher-order data type. The service part that includes the functionality, nonfunctional properties, service parameters, and data of the service requester, is loosely coupled to the contract part that includes trustworthiness claims, legal and business rules governing the service provision, and the context information pertaining to the provider and receiver. This loose coupling allows the creation of many ConfiguredServices, which share the same functionality but possess different contract parts. To facilitate dynamic service adaptation, we introduce a syntax and semantics for extending or modifying a ConfiguredService.

  3. Context-Dependent Competition in a Model Gut Bacterial Community

    OpenAIRE

    de Muinck, Eric J.; Stenseth, Nils Chr.; Sachse, Daniel; vander Roost, Jan; R?nningen, Kjersti S.; Rudi, Knut; Trosvik, P?l

    2013-01-01

    Understanding the ecological processes that generate complex community structures may provide insight into the establishment and maintenance of a normal microbial community in the human gastrointestinal tract, yet very little is known about how biotic interactions influence community dynamics in this system. Here, we use natural strains of Escherichia coli and a simplified model microbiota to demonstrate that the colonization process on the strain level can be context dependent, in the sense ...

  4. Verification of Context-Dependent Channel-Based Service Models

    NARCIS (Netherlands)

    N. Kokash (Natallia); , C. (born Köhler, , C.) Krause (Christian); E.P. de Vink (Erik Peter)

    2010-01-01

    htmlabstractThe paradigms of service-oriented computing and model-driven development are becoming of increasing importance in the eld of software engineering. According to these paradigms, new systems are composed with added value from existing stand-alone services to support business processes

  5. Modelling of Context: Designing Mobile Systems from Domain-Dependent Models

    DEFF Research Database (Denmark)

    Nielsen, Peter Axel; Stage, Jan

    2009-01-01

    Modelling of domain-dependent aspects is a key prerequisite for the design of software for mobile systems. Most mobile systems include a more or less advanced model of selected aspects of the domain in which they are used. This paper discusses the creation of such a model and its relevance...... for technical design of a mobile software system. Conventional approaches to modelling of context focus either on the application domain or the problem domain. These approaches are presented and their relevance for technical design of software for mobile systems is discussed. The paper also reports from...... an empirical study where a methodology that combines both of these approaches was introduced and employed for modelling of the domain-dependent aspects that were relevant for the design of a software component in a mobile telephone. The empirical study was conducted in two companies that produce software...

  6. Context-Dependent Help for the DynaLearn Modelling and Simulation Workbench

    NARCIS (Netherlands)

    Beek, W.; Bredeweg, B.; Latour, S.; Biswas, G.; Bull, S.; Kay, J.; Mitrovic, A.

    2011-01-01

    We implemented three kinds of context-dependent help for a qualitative modelling and simulation workbench called DynaLearn. We show that it is possible to generate and select assistance knowledge based on the current model, simulation results and workbench state.

  7. Comparative Analysis of Context-Dependent Mutagenesis Using Human and Mouse Models

    Directory of Open Access Journals (Sweden)

    Sofya A. Medvedeva

    2013-01-01

    Full Text Available Substitution rates strongly depend on their nucleotide context. One of the most studied examples is the excess of C > T mutations in the CG context in various groups of organisms, including vertebrates. Studies on the molecular mechanisms underlying this mutation regularity have provided insights into evolution, mutagenesis, and cancer development. Recently several other hypermutable motifs were identified in the human genome. There is an increased frequency of T > C mutations in the second position of the words ATTG and ATAG and an increased frequency of A > C mutations in the first position of the word ACAA. For a better understanding of evolution, it is of interest whether these mutation regularities are human specific or present in other vertebrates, as their presence might affect the validity of currently used substitution models and molecular clocks. A comprehensive analysis of mutagenesis in 4 bp mutation contexts requires a vast amount of mutation data. Such data may be derived from the comparisons of individual genomes or from single nucleotide polymorphism (SNP databases. Using this approach, we performed a systematical comparison of mutation regularities within 2–4 bp contexts in Mus musculus and Homo sapiens and uncovered that even closely related organisms may have notable differences in context-dependent mutation regularities.

  8. Variable length and context-dependent HMM letter form models for Arabic handwritten word recognition

    Science.gov (United States)

    Bianne-Bernard, Anne-Laure; Menasri, Fares; Likforman-Sulem, Laurence; Mokbel, Chafic; Kermorvant, Christopher

    2012-01-01

    We present in this paper an HMM-based recognizer for the recognition of unconstrained Arabic handwritten words. The recognizer is a context-dependent HMM which considers variable topology and contextual information for a better modeling of writing units. We propose an algorithm to adapt the topology of each HMM to the character to be modeled. For modeling the contextual units, a state-tying process based on decision tree clustering is introduced which significantly reduces the number of parameters. Decision trees are built according to a set of expert-based questions on how characters are written. Questions are divided into global questions yielding larger clusters and precise questions yielding smaller ones. We apply this modeling to the recognition of Arabic handwritten words. Experiments conducted on the OpenHaRT2010 database show that variable length topology and contextual information significantly improves the recognition rate.

  9. Pitfalls of the most commonly used models of context dependent substitution

    Directory of Open Access Journals (Sweden)

    Huttley Gavin A

    2008-12-01

    Full Text Available Abstract Background Neighboring nucleotides exert a striking influence on mutation, with the hypermutability of CpG dinucleotides in many genomes being an exemplar. Among the approaches employed to measure the relative importance of sequence neighbors on molecular evolution have been continuous-time Markov process models for substitutions that treat sequences as a series of independent tuples. The most widely used examples are the codon substitution models. We evaluated the suitability of derivatives of the nucleotide frequency weighted (hereafter NF and tuple frequency weighted (hereafter TF models for measuring sequence context dependent substitution. Critical properties we address are their relationships to an independent nucleotide process and the robustness of parameter estimation to changes in sequence composition. We then consider the impact on inference concerning dinucleotide substitution processes from application of these two forms to intron sequence alignments from primates. Results We prove that the NF form always nests the independent nucleotide process and that this is not true for the TF form. As a consequence, using TF to study context effects can be misleading, which is shown by both theoretical calculations and simulations. We describe a simple example where a context parameter estimated under TF is confounded with composition terms unless all sequence states are equi-frequent. We illustrate this for the dinucleotide case by simulation under a nucleotide model, showing that the TF form identifies a CpG effect when none exists. Our analysis of primate introns revealed that the effect of nucleotide neighbors is over-estimated under TF compared with NF. Parameter estimates for a number of contexts are also strikingly discordant between the two model forms. Conclusion Our results establish that the NF form should be used for analysis of independent-tuple context dependent processes. Although neighboring effects in general are

  10. Pitfalls of the most commonly used models of context dependent substitution.

    Science.gov (United States)

    Lindsay, Helen; Yap, Von Bing; Ying, Hua; Huttley, Gavin A

    2008-12-16

    Neighboring nucleotides exert a striking influence on mutation, with the hypermutability of CpG dinucleotides in many genomes being an exemplar. Among the approaches employed to measure the relative importance of sequence neighbors on molecular evolution have been continuous-time Markov process models for substitutions that treat sequences as a series of independent tuples. The most widely used examples are the codon substitution models. We evaluated the suitability of derivatives of the nucleotide frequency weighted (hereafter NF) and tuple frequency weighted (hereafter TF) models for measuring sequence context dependent substitution. Critical properties we address are their relationships to an independent nucleotide process and the robustness of parameter estimation to changes in sequence composition. We then consider the impact on inference concerning dinucleotide substitution processes from application of these two forms to intron sequence alignments from primates. We prove that the NF form always nests the independent nucleotide process and that this is not true for the TF form. As a consequence, using TF to study context effects can be misleading, which is shown by both theoretical calculations and simulations. We describe a simple example where a context parameter estimated under TF is confounded with composition terms unless all sequence states are equi-frequent. We illustrate this for the dinucleotide case by simulation under a nucleotide model, showing that the TF form identifies a CpG effect when none exists. Our analysis of primate introns revealed that the effect of nucleotide neighbors is over-estimated under TF compared with NF. Parameter estimates for a number of contexts are also strikingly discordant between the two model forms. Our results establish that the NF form should be used for analysis of independent-tuple context dependent processes. Although neighboring effects in general are still important, prominent influences such as the elevated Cp

  11. A reliable facility location design model with site-dependent disruption in the imperfect information context

    Science.gov (United States)

    Yun, Lifen; Wang, Xifu; Fan, Hongqiang; Li, Xiaopeng

    2017-01-01

    This paper proposes a reliable facility location design model under imperfect information with site-dependent disruptions; i.e., each facility is subject to a unique disruption probability that varies across the space. In the imperfect information contexts, customers adopt a realistic “trial-and-error” strategy to visit facilities; i.e., they visit a number of pre-assigned facilities sequentially until they arrive at the first operational facility or give up looking for the service. This proposed model aims to balance initial facility investment and expected long-term operational cost by finding the optimal facility locations. A nonlinear integer programming model is proposed to describe this problem. We apply a linearization technique to reduce the difficulty of solving the proposed model. A number of problem instances are studied to illustrate the performance of the proposed model. The results indicate that our proposed model can reveal a number of interesting insights into the facility location design with site-dependent disruptions, including the benefit of backup facilities and system robustness against variation of the loss-of-service penalty. PMID:28486564

  12. Long-lasting context dependence constrains neural encoding models in rodent auditory cortex.

    Science.gov (United States)

    Asari, Hiroki; Zador, Anthony M

    2009-11-01

    Acoustic processing requires integration over time. We have used in vivo intracellular recording to measure neuronal integration times in anesthetized rats. Using natural sounds and other stimuli, we found that synaptic inputs to auditory cortical neurons showed a rather long context dependence, up to > or =4 s (tau approximately 1 s), even though sound-evoked excitatory and inhibitory conductances per se rarely lasted greater, similar 100 ms. Thalamic neurons showed only a much faster form of adaptation with a decay constant tau history to only a few hundred milliseconds reduced the predictable response component to about half that of the optimal infinite-history model. Our results demonstrate the importance of long-range temporal effects in auditory cortex and suggest a potential neural substrate for auditory processing that requires integration over timescales of seconds or longer, such as stream segregation.

  13. Context-dependent modelling of English vowels in Sepedi code-switched speech

    CSIR Research Space (South Africa)

    Modipa, TI

    2012-11-01

    Full Text Available phone to a matrix language counterpart. We use acoustic log likelihoods to assist us in identifying the optimal mapping strategy at a context-dependent level (that is, at triphone, rather than monophone level) and obtain new insights in the way English...

  14. Dynamic temperature dependence patterns in future energy demand models in the context of climate change

    International Nuclear Information System (INIS)

    Hekkenberg, M.; Moll, H.C.; Uiterkamp, A.J.M. Schoot

    2009-01-01

    Energy demand depends on outdoor temperature in a 'u' shaped fashion. Various studies have used this temperature dependence to investigate the effects of climate change on energy demand. Such studies contain implicit or explicit assumptions to describe expected socio-economic changes that may affect future energy demand. This paper critically analyzes these implicit or explicit assumptions and their possible effect on the studies' outcomes. First we analyze the interaction between the socio-economic structure and the temperature dependence pattern (TDP) of energy demand. We find that socio-economic changes may alter the TDP in various ways. Next we investigate how current studies manage these dynamics in socio-economic structure. We find that many studies systematically misrepresent the possible effect of socio-economic changes on the TDP of energy demand. Finally, we assess the consequences of these misrepresentations in an energy demand model based on temperature dependence and climate scenarios. Our model results indicate that expected socio-economic dynamics generally lead to an underestimation of future energy demand in models that misrepresent such dynamics. We conclude that future energy demand models should improve the incorporation of socio-economic dynamics. We propose dynamically modeling several key parameters and using direct meteorological data instead of degree days. (author)

  15. The Context-Dependency of the Experience of Auditory Succession and Prospects for Embodying Philosophical Models of Temporal Experience

    Directory of Open Access Journals (Sweden)

    Maria Kon

    2015-05-01

    Full Text Available Recent philosophical work on temporal experience offers generic models that are often assumed to apply to all sensory modalities. I show that the models serve as broad frameworks in which different aspects of cognitive science can be slotted and, thus, are beneficial to furthering research programs in embodied music cognition. Here I discuss a particular feature of temporal experience that plays a key role in such philosophical work: a distinction between the experience of succession and the mere succession of experiences. I question the presupposition that there is such an evident, clear distinction and suggest that, instead, how the distinction is drawn is context-dependent. After suggesting a way to modify the philosophical models of temporal experience to accommodate this context-dependency, I illustrate that these models can fruitfully incorporate features of research projects in embodied musical cognition. To do so I supplement a modified retentionalist model with aspects of recent work that links bodily movement with musical perception (Godøy, 2006; 2010a; Jensenius, Wanderley, Godøy, and Leman, 2010. The resulting model is shown to facilitate novel hypotheses, refine the notion of context-dependency and point towards means of extending the philosophical model and an existent research program.

  16. Audio visual speech source separation via improved context dependent association model

    Science.gov (United States)

    Kazemi, Alireza; Boostani, Reza; Sobhanmanesh, Fariborz

    2014-12-01

    In this paper, we exploit the non-linear relation between a speech source and its associated lip video as a source of extra information to propose an improved audio-visual speech source separation (AVSS) algorithm. The audio-visual association is modeled using a neural associator which estimates the visual lip parameters from a temporal context of acoustic observation frames. We define an objective function based on mean square error (MSE) measure between estimated and target visual parameters. This function is minimized for estimation of the de-mixing vector/filters to separate the relevant source from linear instantaneous or time-domain convolutive mixtures. We have also proposed a hybrid criterion which uses AV coherency together with kurtosis as a non-Gaussianity measure. Experimental results are presented and compared in terms of visually relevant speech detection accuracy and output signal-to-interference ratio (SIR) of source separation. The suggested audio-visual model significantly improves relevant speech classification accuracy compared to existing GMM-based model and the proposed AVSS algorithm improves the speech separation quality compared to reference ICA- and AVSS-based methods.

  17. Deep Belief Networks Learn Context Dependent Behavior

    OpenAIRE

    Raudies, Florian; Zilli, Eric A.; Hasselmo, Michael E.

    2014-01-01

    With the goal of understanding behavioral mechanisms of generalization, we analyzed the ability of neural networks to generalize across context. We modeled a behavioral task where the correct responses to a set of specific sensory stimuli varied systematically across different contexts. The correct response depended on the stimulus (A,B,C,D) and context quadrant (1,2,3,4). The possible 16 stimulus-context combinations were associated with one of two responses (X,Y), one of which was correct f...

  18. Dynamic temperature dependence patterns in future energy demand models in the context of climate change

    NARCIS (Netherlands)

    Hekkenberg, M.; Moll, H.C.; Schoot Uiterkamp, A.J.M.

    2009-01-01

    Energy demand depends on outdoor temperature in a 'u' shaped fashion. Various studies have used this temperature dependence to investigate the effects of climate change on energy demand. Such studies contain implicit or explicit assumptions to describe expected socio-economic changes that may affect

  19. Modeling spatial-temporal operations with context-dependent associative memories.

    Science.gov (United States)

    Mizraji, Eduardo; Lin, Juan

    2015-10-01

    We organize our behavior and store structured information with many procedures that require the coding of spatial and temporal order in specific neural modules. In the simplest cases, spatial and temporal relations are condensed in prepositions like "below" and "above", "behind" and "in front of", or "before" and "after", etc. Neural operators lie beneath these words, sharing some similarities with logical gates that compute spatial and temporal asymmetric relations. We show how these operators can be modeled by means of neural matrix memories acting on Kronecker tensor products of vectors. The complexity of these memories is further enhanced by their ability to store episodes unfolding in space and time. How does the brain scale up from the raw plasticity of contingent episodic memories to the apparent stable connectivity of large neural networks? We clarify this transition by analyzing a model that flexibly codes episodic spatial and temporal structures into contextual markers capable of linking different memory modules.

  20. Deep belief networks learn context dependent behavior.

    Directory of Open Access Journals (Sweden)

    Florian Raudies

    Full Text Available With the goal of understanding behavioral mechanisms of generalization, we analyzed the ability of neural networks to generalize across context. We modeled a behavioral task where the correct responses to a set of specific sensory stimuli varied systematically across different contexts. The correct response depended on the stimulus (A,B,C,D and context quadrant (1,2,3,4. The possible 16 stimulus-context combinations were associated with one of two responses (X,Y, one of which was correct for half of the combinations. The correct responses varied symmetrically across contexts. This allowed responses to previously unseen stimuli (probe stimuli to be generalized from stimuli that had been presented previously. By testing the simulation on two or more stimuli that the network had never seen in a particular context, we could test whether the correct response on the novel stimuli could be generated based on knowledge of the correct responses in other contexts. We tested this generalization capability with a Deep Belief Network (DBN, Multi-Layer Perceptron (MLP network, and the combination of a DBN with a linear perceptron (LP. Overall, the combination of the DBN and LP had the highest success rate for generalization.

  1. Deep belief networks learn context dependent behavior.

    Science.gov (United States)

    Raudies, Florian; Zilli, Eric A; Hasselmo, Michael E

    2014-01-01

    With the goal of understanding behavioral mechanisms of generalization, we analyzed the ability of neural networks to generalize across context. We modeled a behavioral task where the correct responses to a set of specific sensory stimuli varied systematically across different contexts. The correct response depended on the stimulus (A,B,C,D) and context quadrant (1,2,3,4). The possible 16 stimulus-context combinations were associated with one of two responses (X,Y), one of which was correct for half of the combinations. The correct responses varied symmetrically across contexts. This allowed responses to previously unseen stimuli (probe stimuli) to be generalized from stimuli that had been presented previously. By testing the simulation on two or more stimuli that the network had never seen in a particular context, we could test whether the correct response on the novel stimuli could be generated based on knowledge of the correct responses in other contexts. We tested this generalization capability with a Deep Belief Network (DBN), Multi-Layer Perceptron (MLP) network, and the combination of a DBN with a linear perceptron (LP). Overall, the combination of the DBN and LP had the highest success rate for generalization.

  2. Context-dependent encoding of fear and extinction memories in a large-scale network model of the basal amygdala.

    Directory of Open Access Journals (Sweden)

    Ioannis Vlachos

    2011-03-01

    Full Text Available The basal nucleus of the amygdala (BA is involved in the formation of context-dependent conditioned fear and extinction memories. To understand the underlying neural mechanisms we developed a large-scale neuron network model of the BA, composed of excitatory and inhibitory leaky-integrate-and-fire neurons. Excitatory BA neurons received conditioned stimulus (CS-related input from the adjacent lateral nucleus (LA and contextual input from the hippocampus or medial prefrontal cortex (mPFC. We implemented a plasticity mechanism according to which CS and contextual synapses were potentiated if CS and contextual inputs temporally coincided on the afferents of the excitatory neurons. Our simulations revealed a differential recruitment of two distinct subpopulations of BA neurons during conditioning and extinction, mimicking the activation of experimentally observed cell populations. We propose that these two subgroups encode contextual specificity of fear and extinction memories, respectively. Mutual competition between them, mediated by feedback inhibition and driven by contextual inputs, regulates the activity in the central amygdala (CEA thereby controlling amygdala output and fear behavior. The model makes multiple testable predictions that may advance our understanding of fear and extinction memories.

  3. Stress Disrupts Context-Dependent Memory

    Science.gov (United States)

    Schwabe, Lars; Bohringer, Andreas; Wolf, Oliver T.

    2009-01-01

    Memory is facilitated when the retrieval context resembles the learning context. The brain structures underlying contextual influences on memory are susceptible to stress. Whether stress interferes with context-dependent memory is still unknown. We exposed healthy adults to stress or a control procedure before they learned an object-location task…

  4. Time dependent photon and neutrino emission from Mkr 421 in the context of the one-zone leptohadronic model

    Directory of Open Access Journals (Sweden)

    Mastichiadis Apostolos

    2013-12-01

    Full Text Available We apply a recently developed time-dependent one-zone leptohadronic model to study the emission of the blazar Mrk 421. Both processes involving proton-photon interactions, i.e. photopair (Bethe-Heitler and photopion, have been modeled in great detail using the results of Monte Carlo simulations, like the SOPHIA event generator, in a self-consistent scheme that couples energy losses and secondary injection. We find that TeV gamma-rays can be attributed to synchrotron radiation either from relativistic protons or, alternatively, from secondary leptons produced via photohadronic processes. We also study the variability patterns that each scenario predicts and we find that while the former is more energetically favored, it is the latter that produces, in a more natural way, the usual quadratic behavior between X-rays and TeV gamma-rays. We also use the obtained SEDs to calculate in detail the expected neutron and neutrino fluxes that each model predicts.

  5. Perceived luminance depends on temporal context.

    Science.gov (United States)

    Eagleman, David M; Jacobson, John E; Sejnowski, Terrence J

    2004-04-22

    Brightness--the perception of an object's luminance--arises from complex and poorly understood interactions at several levels of processing. It is well known that the brightness of an object depends on its spatial context, which can include perceptual organization, scene interpretation, three-dimensional interpretation, shadows, and other high-level percepts. Here we present a new class of illusion in which temporal relations with spatially neighbouring objects can modulate a target object's brightness. When compared with a nearby patch of constant luminance, a brief flash appears brighter with increasing onset asynchrony. Simultaneous contrast, retinal effects, masking, apparent motion and attentional effects cannot account for this illusory enhancement of brightness. This temporal context effect indicates that two parallel streams--one adapting and one non-adapting--encode brightness in the visual cortex.

  6. The Context-Dependency of the Experience of Auditory Succession and Prospects for Embodying Philosophical Models of Temporal Experience

    OpenAIRE

    Maria Kon

    2015-01-01

    Recent philosophical work on temporal experience offers generic models that are often assumed to apply to all sensory modalities. I show that the models serve as broad frameworks in which different aspects of cognitive science can be slotted and, thus, are beneficial to furthering research programs in embodied music cognition. Here I discuss a particular feature of temporal experience that plays a key role in such philosophical work: a distinction between the experience of succession and the ...

  7. Context dependent prediction and category encoding for DPCM image compression

    Science.gov (United States)

    Beaudet, Paul R.

    1989-01-01

    Efficient compression of image data requires the understanding of the noise characteristics of sensors as well as the redundancy expected in imagery. Herein, the techniques of Differential Pulse Code Modulation (DPCM) are reviewed and modified for information-preserving data compression. The modifications include: mapping from intensity to an equal variance space; context dependent one and two dimensional predictors; rationale for nonlinear DPCM encoding based upon an image quality model; context dependent variable length encoding of 2x2 data blocks; and feedback control for constant output rate systems. Examples are presented at compression rates between 1.3 and 2.8 bits per pixel. The need for larger block sizes, 2D context dependent predictors, and the hope for sub-bits-per-pixel compression which maintains spacial resolution (information preserving) are discussed.

  8. Context-dependent discrimination and the evolution of mimicry.

    Science.gov (United States)

    Holen, Øistein Haugsten; Johnstone, Rufus A

    2006-03-01

    Many mimetic organisms have evolved a close resemblance to their models, making it difficult to discriminate between them on the basis of appearance alone. However, if mimics and models differ slightly in their activity patterns, behavior, or use of microhabitats, the exact circumstances under which a signaler is encountered may provide additional clues to its identity. We employ an optimality model of mimetic discrimination in which signal receivers obtain information about the relative risk of encountering mimics and models by observing an external background cue and flexibly adjust their response thresholds. Although such flexibility on the part of signal receivers has been predicted by theory and is supported by empirical evidence in a range of biological settings, little is known about the effects it has on signalers. We show that the presence of external cues that partly reveal signaler identity may benefit models and harm mimics, harm both, or even benefit both, depending on ecological circumstances. Moreover, if mimetic traits are costly to express, or mimics are related to their neighbors, context-dependent discrimination can dramatically alter the outcome of mimetic evolution. We discuss context-dependent discrimination among signal receivers in relation to small-scale synchrony in model and mimic activity patterns.

  9. Specification and Verification of Context-dependent Services

    Directory of Open Access Journals (Sweden)

    Naseem Ibrahim

    2011-08-01

    Full Text Available Current approaches for the discovery, specification, and provision of services ignore the relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. We remedy this situation in this paper. We present a formal definition of services with context-dependent contracts. We define a composition theory of services with context-dependent contracts taking into consideration functional, nonfunctional, legal and contextual information. Finally, we present a formal verification approach that transforms the formal specification of service composition into extended timed automata that can be verified using the model checking tool UPPAAL.

  10. Context-dependent ATC complexity metric

    NARCIS (Netherlands)

    Mercado Velasco, G.A.; Borst, C.

    2015-01-01

    Several studies have investigated Air Traffic Control (ATC) complexity metrics in a search for a metric that could best capture workload. These studies have shown how daunting the search for a universal workload metric (one that could be applied in different contexts: sectors, traffic patterns,

  11. Context-dependent hierarchies in pigeons.

    Science.gov (United States)

    Nagy, Máté; Vásárhelyi, Gábor; Pettit, Benjamin; Roberts-Mariani, Isabella; Vicsek, Tamás; Biro, Dora

    2013-08-06

    Hierarchical organization is widespread in the societies of humans and other animals, both in social structure and in decision-making contexts. In the case of collective motion, the majority of case studies report that dominant individuals lead group movements, in agreement with the common conflation of the terms "dominance" and "leadership." From a theoretical perspective, if social relationships influence interactions during collective motion, then social structure could also affect leadership in large, swarm-like groups, such as fish shoals and bird flocks. Here we use computer-vision-based methods and miniature GPS tracking to study, respectively, social dominance and in-flight leader-follower relations in pigeons. In both types of behavior we find hierarchically structured networks of directed interactions. However, instead of being conflated, dominance and leadership hierarchies are completely independent of each other. Although dominance is an important aspect of variation among pigeons, correlated with aggression and access to food, our results imply that the stable leadership hierarchies in the air must be based on a different set of individual competences. In addition to confirming the existence of independent and context-specific hierarchies in pigeons, we succeed in setting out a robust, scalable method for the automated analysis of dominance relationships, and thus of social structure, applicable to many species. Our results, as well as our methods, will help to incorporate the broader context of animal social organization into the study of collective behavior.

  12. Effects of extended context discrimination training and context extinction on transfer of context dependency of conditioned flavor aversion.

    Science.gov (United States)

    Iguchi, Yoshio; Fukumoto, Kazuya; Sawa, Kosuke; Ishii, Kiyoshi

    2014-03-01

    We trained rats in a context discrimination paradigm by pairing a sucrose solution with lithium chloride in one context (conditioning context) and simple exposure to the same fluid in a second (neutral) context to establish a context-dependent aversion to the conditioned fluid. We then investigated whether transfer of the context dependency to a test fluid (a sodium chloride solution) was affected by two post-discrimination training treatments, an extended context discrimination training, and non-reinforced exposure to the conditioning context (context extinction). We found that the context-dependent flavor aversion that had been specific to sucrose transferred to the test fluid after the extensive training (Experiment 1). Context extinction eliminated the transfer effect that had been observed immediately after the context discrimination training (Experiment 2). In addition, an aversion acquired by sucrose through a simple conditioning of sucrose-LiCl pairings did not generalize to the test fluid (Experiment 3). These results emphasize the importance of a Pavlovian excitatory association between the conditioning context and nausea as a primary source of transfer of the context dependency, rather than a generalization of aversion acquired by the conditioned fluid to the test fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Context Dependent Analysis of BioAmbients

    DEFF Research Database (Denmark)

    Pilegaard, Henrik; Nielson, Flemming; Nielson, Hanne Riis

    2006-01-01

    BioAmbients is a derivative of mobile ambients that has shown promise of describing interesting features of the behaviour of biological systems. The technical contribution of this paper is to extend the Flow Logic approach to static analysis with a couple of new techniques in order to give precise...... information about the behaviour of systems written in BioAmbients. Applying the development to a simple model of a cell releasing nutrients from food compunds we illustrate how the proposed analysis does indeed improve on previous efforts....

  14. Exploring the Context Dependency of the PSM-Performance Relationship

    DEFF Research Database (Denmark)

    Lynggard, Mikkel; Pedersen, Mogens Jin; Andersen, Lotte Bøgh

    2016-01-01

    The public service motivation (PSM) of public employees matters to their performance at work. Yet research on how context factors moderate the PSM–performance relationship is sparse. This article shows how the PSM–performance relationship may depend on two context factors: (a) the extent of work ...

  15. Hybrid methodological approach to context-dependent speech recognition

    Directory of Open Access Journals (Sweden)

    Dragiša Mišković

    2017-01-01

    Full Text Available Although the importance of contextual information in speech recognition has been acknowledged for a long time now, it has remained clearly underutilized even in state-of-the-art speech recognition systems. This article introduces a novel, methodologically hybrid approach to the research question of context-dependent speech recognition in human–machine interaction. To the extent that it is hybrid, the approach integrates aspects of both statistical and representational paradigms. We extend the standard statistical pattern-matching approach with a cognitively inspired and analytically tractable model with explanatory power. This methodological extension allows for accounting for contextual information which is otherwise unavailable in speech recognition systems, and using it to improve post-processing of recognition hypotheses. The article introduces an algorithm for evaluation of recognition hypotheses, illustrates it for concrete interaction domains, and discusses its implementation within two prototype conversational agents.

  16. Modeling Uncertain Context Information via Event Probabilities

    NARCIS (Netherlands)

    van Bunningen, A.H.; Feng, L.; Apers, Peter M.G.; de Keijzer, Ander; de Keijzer, A.; van Keulen, M.; van Keulen, Maurice

    2006-01-01

    To be able to support context-awareness in an Ambient Intelligent (AmI) environment, one needs a way to model context. Previous research shows that a good way to model context is using Description Logics (DL). Since context data is often coming from sensors and therefore exhibits uncertain

  17. Brain structural connectivity and context-dependent extinction memory.

    Science.gov (United States)

    Hermann, Andrea; Stark, Rudolf; Blecker, Carlo R; Milad, Mohammed R; Merz, Christian J

    2017-08-01

    Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity. Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later. Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum. Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders. © 2017 Wiley Periodicals, Inc.

  18. Ketamine-induced deficits in auditory and visual context-dependent processing in healthy volunteers: implications for models of cognitive deficits in schizophrenia.

    Science.gov (United States)

    Umbricht, D; Schmid, L; Koller, R; Vollenweider, F X; Hell, D; Javitt, D C

    2000-12-01

    In patients with schizophrenia, deficient generation of mismatch negativity (MMN)-an event-related potential (ERP) indexing auditory sensory ("echoic") memory-and a selective increase of "context dependent" ("BX") errors in the "A-X" version of the Continuous Performance Test (AX-CPT) indicate an impaired ability to form and use transient memory traces. Animal and human studies implicate deficient N-methyl-D-aspartate receptor (NMDAR) functioning in such abnormalities. In this study, effects of the NMDAR antagonists ketamine on MMN generation and AX-CPT performance were investigated in healthy volunteers to test the hypothesis that NMDARs are critically involved in human MMN generation, and to assess the nature of ketamine-induced deficits in AX-CPT performance. In a single-blind placebo-controlled study, 20 healthy volunteers underwent an infusion with subanesthetic doses of ketamine. The MMN-to-pitch and MMN-to-duration deviants were obtained while subjects performed an AX-CPT. Ketamine significantly decreased the peak amplitudes of the MMN-to-pitch and MMN-to-duration deviants by 27% and 21%, respectively. It induced performance deficits in the AX-CPT characterized by decreased hit rates and specific increases of errors (BX errors), reflecting a failure to form and use transient memory traces of task relevant information. The NMDARs are critically involved in human MMN generation. Deficient MMN in schizophrenia thus suggests deficits in NMDAR-related neurotransmission. N-methyl-D-aspartate receptor dysfunction may also contribute to the impairment of patients with schizophrenia in forming and using transient memory traces in more complex tasks, such as the AX-CPT. Thus, NMDAR-related dysfunction may underlie deficits in transient memory at different levels of information processing in schizophrenia. Arch Gen Psychiatry. 2000;57:1139-1147.

  19. Modeling trust context in networks

    CERN Document Server

    Adali, Sibel

    2013-01-01

    We make complex decisions every day, requiring trust in many different entities for different reasons. These decisions are not made by combining many isolated trust evaluations. Many interlocking factors play a role, each dynamically impacting the others.? In this brief, 'trust context' is defined as the system level description of how the trust evaluation process unfolds.Networks today are part of almost all human activity, supporting and shaping it. Applications increasingly incorporate new interdependencies and new trust contexts. Social networks connect people and organizations throughout

  20. Behavioural plasticity of social trematodes depends upon social context

    OpenAIRE

    Kamiya, T.; Poulin, R.

    2013-01-01

    Members of some social insects adjust their behaviours depending upon social context. Such plasticity allows colonies to sustain efficiency of the whole without the cost of additional production of individuals or delayed responses to perturbations. Using the recently discovered social clonal stage of trematode parasites, we investigated whether members of the reproductive caste adjust their defensive behaviour according to the local availability of non-reproductive defensive specialists, and ...

  1. A Formal Model for Context-Awareness

    DEFF Research Database (Denmark)

    Kjærgaard, Mikkel Baun; Bunde-Pedersen, Jonathan

    here is a definite lack of formal support for modeling real- istic context-awareness in pervasive computing applications. The Conawa calculus presented in this paper provides mechanisms for modeling complex and interwoven sets of context-information by extending ambient calculus with new construc...

  2. Context-dependent incremental timing cells in the primate hippocampus.

    Science.gov (United States)

    Sakon, John J; Naya, Yuji; Wirth, Sylvia; Suzuki, Wendy A

    2014-12-23

    We examined timing-related signals in primate hippocampal cells as animals performed an object-place (OP) associative learning task. We found hippocampal cells with firing rates that incrementally increased or decreased across the memory delay interval of the task, which we refer to as incremental timing cells (ITCs). Three distinct categories of ITCs were identified. Agnostic ITCs did not distinguish between different trial types. The remaining two categories of cells signaled time and trial context together: One category of cells tracked time depending on the behavioral action required for a correct response (i.e., early vs. late release), whereas the other category of cells tracked time only for those trials cued with a specific OP combination. The context-sensitive ITCs were observed more often during sessions where behavioral learning was observed and exhibited reduced incremental firing on incorrect trials. Thus, single primate hippocampal cells signal information about trial timing, which can be linked with trial type/context in a learning-dependent manner.

  3. Context-dependent Reasoning for the Semantic Web

    Directory of Open Access Journals (Sweden)

    Neli P. Zlatareva

    2011-08-01

    Full Text Available Ontologies are the backbone of the emerging Semantic Web, which is envisioned to dramatically improve current web services by extending them with intelligent capabilities such as reasoning and context-awareness. They define a shared vocabulary of common domains accessible to both, humans and computers, and support various types of information management including storage and processing of data. Current ontology languages, which are designed to be decidable to allow for automatic data processing, target simple typed ontologies that are completely and consistently specified. As the size of ontologies and the complexity of web applications grow, the need for more flexible representation and reasoning schemes emerges. This article presents a logical framework utilizing context-dependent rules which are intended to support not fully and/or precisely specified ontologies. A hypothetical application scenario is described to illustrate the type of ontologies targeted, and the type of queries that the presented logical framework is intended to address.

  4. Representing Context in Hypermedia Data Models

    DEFF Research Database (Denmark)

    Hansen, Frank Allan

    2005-01-01

    As computers and software systems move beyond the desktopand into the physical environments we live and workin, the systems are required to adapt to these environmentsand the activities taking place within them. Making applicationscontext-aware and representing context informationalong side...... application data can be a challenging task. Thispaper describes how digital context traditionally has beenrepresented in hypermedia data models and how this representationcan scale to also represent physical context. TheHyCon framework and data model, designed for the developmentof mobile context...

  5. Curation of complex, context-dependent immunological data

    Directory of Open Access Journals (Sweden)

    Sidney John

    2006-07-01

    Full Text Available Abstract Background The Immune Epitope Database and Analysis Resource (IEDB is dedicated to capturing, housing and analyzing complex immune epitope related data http://www.immuneepitope.org. Description To identify and extract relevant data from the scientific literature in an efficient and accurate manner, novel processes were developed for manual and semi-automated annotation. Conclusion Formalized curation strategies enable the processing of a large volume of context-dependent data, which are now available to the scientific community in an accessible and transparent format. The experiences described herein are applicable to other databases housing complex biological data and requiring a high level of curation expertise.

  6. History-dependent sorption in humic acids and a lignite in the context of a polymer model for natural organic matter.

    Science.gov (United States)

    Lu, Yuefeng; Pignatello, Joseph J

    2004-11-15

    We examined sorption of two apolar compounds in three samples of macromolecular natural organic matter (NOM) in order to test whether history-dependent ("irreversible") behaviors, including sorption hysteresis and the conditioning effect, agree with a pore deformation/creation hypothesis applicable to the glassy organic solid state as proposed in the polymer literature. The compounds are 1,2,4-trichlorobenzene (TCB) and naphthalene (Naph). The NOM samples are a soil humic acid (H-HA), an Al3+-exchanged form of the same humic acid (Al-HA), and a low-rank coal (Beulah-Zap lignite, BZL). The HAs, at least, are believed free of environmental black carbon. The degree of nonlinearity in the isotherm and the ratio of hole-filling to solid-phase dissolution increased in the order of hardness (stiffness) of the solid: H-HA hole "sites" as compared to dissolution "sites", which we attribute to the free energy needed in the dissolution domain to create a cavity to accommodate the solute. All solids exhibited hysteresis and the conditioning effect, which refers to enhanced re-sorption after pretreatment with a conditioning agent (in this case, chlorobenzene). Conditioning the sample results in increased sorption and increased contribution of hole-filling relative to dissolution. The effects of original hole population, matrix stiffness, and solute concentration on the hysteresis index and on the magnitude of the conditioning effect are consistent with a pore-deformation mechanism as the underlying cause of sorption irreversibility. This mechanism involves concurrent processes of irreversible hole expansion and the creation of new holes by the incoming sorbate (or conditioning agent). The results show that nonlinear and irreversible behavior may be expected for macromolecular forms of NOM that are in a glassy state and emphasize the case that NOM is not a passive sorbent but may be physically altered by the sorbate.

  7. Characterization of the SIRT family of NAD+-dependent protein deacetylases in the context of a mammalian model of hibernation, the thirteen-lined ground squirrel.

    Science.gov (United States)

    Rouble, Andrew N; Storey, Kenneth B

    2015-10-01

    Hibernating mammals employ strong metabolic rate depression to survive the winter, thereby avoiding the high energy costs of maintaining a euthermic lifestyle in the face of low seasonal temperatures and limited food resources. Characteristics of this natural torpor include a significant reduction in body temperature, a shift to a lipid-based metabolism, global suppression of ATP-expensive activities, and the upregulation of selected genes that mediate biochemical reorganization and cytoprotection. Sirtuin (SIRT) proteins, an evolutionarily conserved family of NAD(+)-dependent protein deacetylases, have been shown to play important roles in the post-translational regulation of many metabolic and cytoprotective processes, suggesting a potential function for these enzymes in the control of hibernation. To assess this possibility, protein levels of the seven mammalian SIRTs (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7), total SIRT activity, and the acetylation status of two downstream SIRT targets (SOD2K68 and NF-κB p65K310) were measured in skeletal muscle, liver, brown adipose and white adipose tissues of the hibernating thirteen-lined ground squirrel (Ictidomys tridecemlineatus) over the course of the torpor-arousal cycle. The analysis revealed tissue-specific responses of different SIRTs at various points throughout hibernation, including a potentially interesting correlation between increased levels of SIRT3 protein, heightened total SIRT activity, and decreased acetylation of SIRT3 downstream target SOD2K68 in skeletal muscle during late torpor. These results provide evidence to suggest a possible role for the SIRT family of protein deacetylases in the regulation of the metabolic and cellular protective pathways that mediate the process of mammalian hibernation. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Towards a Formal Model of Context Awareness

    DEFF Research Database (Denmark)

    Kjærgaard, Mikkel Baun; Bunde-Pedersen, Jonathan

    2006-01-01

    There is a definite lack of formal support for modeling realistic context-awareness in pervasive computing applications. The CONAWA calculus presented in this paper provides mechanisms for modeling complex and interwoven sets of context-information by extending ambient calculus with new constructs...... and capabilities. The calculus is a step in the direction of making formal methods applicable in the area of pervasive computing....

  9. Feature context-dependency and complexity-reduction in probability landscapes for integrative genomics

    Directory of Open Access Journals (Sweden)

    Benecke Arndt

    2008-09-01

    Full Text Available Abstract Background The question of how to integrate heterogeneous sources of biological information into a coherent framework that allows the gene regulatory code in eukaryotes to be systematically investigated is one of the major challenges faced by systems biology. Probability landscapes, which include as reference set the probabilistic representation of the genomic sequence, have been proposed as a possible approach to the systematic discovery and analysis of correlations amongst initially heterogeneous and un-relatable descriptions and genome-wide measurements. Much of the available experimental sequence and genome activity information is de facto, but not necessarily obviously, context dependent. Furthermore, the context dependency of the relevant information is itself dependent on the biological question addressed. It is hence necessary to develop a systematic way of discovering the context-dependency of functional genomics information in a flexible, question-dependent manner. Results We demonstrate here how feature context-dependency can be systematically investigated using probability landscapes. Furthermore, we show how different feature probability profiles can be conditionally collapsed to reduce the computational and formal, mathematical complexity of probability landscapes. Interestingly, the possibility of complexity reduction can be linked directly to the analysis of context-dependency. Conclusion These two advances in our understanding of the properties of probability landscapes not only simplify subsequent cross-correlation analysis in hypothesis-driven model building and testing, but also provide additional insights into the biological gene regulatory problems studied. Furthermore, insights into the nature of individual features and a classification of features according to their minimal context-dependency are achieved. The formal structure proposed contributes to a concrete and tangible basis for attempting to formulate novel

  10. Visual memory performance for color depends on spatiotemporal context.

    Science.gov (United States)

    Olivers, Christian N L; Schreij, Daniel

    2014-10-01

    Performance on visual short-term memory for features has been known to depend on stimulus complexity, spatial layout, and feature context. However, with few exceptions, memory capacity has been measured for abruptly appearing, single-instance displays. In everyday life, objects often have a spatiotemporal history as they or the observer move around. In three experiments, we investigated the effect of spatiotemporal history on explicit memory for color. Observers saw a memory display emerge from behind a wall, after which it disappeared again. The test display then emerged from either the same side as the memory display or the opposite side. In the first two experiments, memory improved for intermediate set sizes when the test display emerged in the same way as the memory display. A third experiment then showed that the benefit was tied to the original motion trajectory and not to the display object per se. The results indicate that memory for color is embedded in a richer episodic context that includes the spatiotemporal history of the display.

  11. Support for context effects on segmentation and segments depends on the context.

    Science.gov (United States)

    Heffner, Christopher C; Newman, Rochelle S; Idsardi, William J

    2017-04-01

    Listeners must adapt to differences in speech rate across talkers and situations. Speech rate adaptation effects are strong for adjacent syllables (i.e., proximal syllables). For studies that have assessed adaptation effects on speech rate information more than one syllable removed from a point of ambiguity in speech (i.e., distal syllables), the difference in strength between different types of ambiguity is stark. Studies of word segmentation have shown large shifts in perception as a result of distal rate manipulations, while studies of segmental perception have shown only weak, or even nonexistent, effects. However, no study has standardized methods and materials to study context effects for both types of ambiguity simultaneously. Here, a set of sentences was created that differed as minimally as possible except for whether the sentences were ambiguous to the voicing of a consonant or ambiguous to the location of a word boundary. The sentences were then rate-modified to slow down the distal context speech rate to various extents, dependent on three different definitions of distal context that were adapted from previous experiments, along with a manipulation of proximal context to assess whether proximal effects were comparable across ambiguity types. The results indicate that the definition of distal influenced the extent of distal rate effects strongly for both segments and segmentation. They also establish the presence of distal rate effects on word-final segments for the first time. These results were replicated, with some caveats regarding the perception of individual segments, in an Internet-based sample recruited from Mechanical Turk.

  12. Process and Context in Choice Models

    DEFF Research Database (Denmark)

    Ben-Akiva, Moshe; Palma, André de; McFadden, Daniel

    2012-01-01

    We develop a general framework that extends choice models by including an explicit representation of the process and context of decision making. Process refers to the steps involved in decision making. Context refers to factors affecting the process, focusing in this paper on social networks....... The extended choice framework includes more behavioral richness through the explicit representation of the planning process preceding an action and its dynamics and the effects of context (family, friends, and market) on the process leading to a choice, as well as the inclusion of new types of subjective data...

  13. Modeling Musical Context With Word2Vec

    Science.gov (United States)

    Herremans, Dorien; Chuan, Ching-Hua

    2017-05-01

    We present a semantic vector space model for capturing complex polyphonic musical context. A word2vec model based on a skip-gram representation with negative sampling was used to model slices of music from a dataset of Beethoven's piano sonatas. A visualization of the reduced vector space using t-distributed stochastic neighbor embedding shows that the resulting embedded vector space captures tonal relationships, even without any explicit information about the musical contents of the slices. Secondly, an excerpt of the Moonlight Sonata from Beethoven was altered by replacing slices based on context similarity. The resulting music shows that the selected slice based on similar word2vec context also has a relatively short tonal distance from the original slice.

  14. Context dependency and generality of fever in insects

    Science.gov (United States)

    Stahlschmidt, Z. R.; Adamo, S. A.

    2013-07-01

    Fever can reduce mortality in infected animals. Yet, despite its fitness-enhancing qualities, fever often varies among animals. We used several approaches to examine this variation in insects. Texas field crickets ( Gryllus texensis) exhibited a modest fever (1 °C increase in preferred body temperature, T pref) after injection of prostaglandin, which putatively mediates fever in both vertebrates and invertebrates, but they did not exhibit fever during chronic exposure to heat-killed bacteria. Further, chronic food limitation and mating status did not affect T pref or the expression of behavioural fever, suggesting limited context dependency of fever in G. texensis. Our meta-analysis of behavioural fever studies indicated that behavioural fever occurs in many insects, but it is not ubiquitous. Thus, both empirical and meta-analytical results suggest that the fever response in insects `is widespread, although certainly not inevitable' (Moore 2002). We highlight the need for future work focusing on standardizing an experimental protocol to measure behavioural fever, understanding the specific mechanism(s) underlying fever in insects, and examining whether ecological or physiological costs often outweigh the benefits of fever and can explain the sporadic nature of fever in insects.

  15. Neighbor Preferences of Amino Acids and Context-Dependent Effects of Amino Acid Substitutions in Human, Mouse, and Dog

    Directory of Open Access Journals (Sweden)

    Mingchuan Fu

    2014-09-01

    Full Text Available Amino acids show apparent propensities toward their neighbors. In addition to preferences of amino acids for their neighborhood context, amino acid substitutions are also considered to be context-dependent. However, context-dependence patterns of amino acid substitutions still remain poorly understood. Using relative entropy, we investigated the neighbor preferences of 20 amino acids and the context-dependent effects of amino acid substitutions with protein sequences in human, mouse, and dog. For 20 amino acids, the highest relative entropy was mostly observed at the nearest adjacent site of either N- or C-terminus except C and G. C showed the highest relative entropy at the third flanking site and periodic pattern was detected at G flanking sites. Furthermore, neighbor preference patterns of amino acids varied greatly in different secondary structures. We then comprehensively investigated the context-dependent effects of amino acid substitutions. Our results showed that nearly half of 380 substitution types were evidently context dependent, and the context-dependent patterns relied on protein secondary structures. Among 20 amino acids, P elicited the greatest effect on amino acid substitutions. The underlying mechanisms of context-dependent effects of amino acid substitutions were possibly mutation bias at a DNA level and natural selection. Our findings may improve secondary structure prediction algorithms and protein design; moreover, this study provided useful information to develop empirical models of protein evolution that consider dependence between residues.

  16. Analysis and modeling of "focus" in context

    DEFF Research Database (Denmark)

    Hovy, Dirk; Anumanchipalli, Gopala; Parlikar, Alok

    2013-01-01

    or speech stimuli. We then build models to show how well we predict that focus word from lexical (and higher) level features. Also, using spectral and prosodic information, we show the differences in these focus words when spoken with and without context. Finally, we show how we can improve speech synthesis...... of these utterances given focus information....

  17. Context and strain-dependent behavioral response to stress

    Directory of Open Access Journals (Sweden)

    Baum Amber E

    2008-06-01

    Full Text Available Abstract Background This study posed the question whether strain differences in stress-reactivity lead to differential behavioral responses in two different tests of anxiety. Strain differences in anxiety-measures are known, but strain differences in the behavioral responses to acute prior stress are not well characterized. Methods We studied male Fisher 344 (F344 and Wistar Kyoto (WKY rats basally and immediately after one hour restraint stress. To distinguish between the effects of novelty and prior stress, we also investigated behavior after repeated exposure to the test chamber. Two behavioral tests were explored; the elevated plus maze (EPM and the open field (OFT, both of which are thought to measure activity, exploration and anxiety-like behaviors. Additionally, rearing, a voluntary behavior, and grooming, a relatively automatic, stress-responsive stereotyped behavior were measured in both tests. Results Prior exposure to the test environment increased anxiety-related measures regardless of prior stress, reflecting context-dependent learning process in both tests and strains. Activity decreased in response to repeated testing in both tests and both strains, but prior stress decreased activity only in the OFT which was reversed by repeated testing. Prior stress decreased anxiety-related measures in the EPM, only in F344s, while in the OFT, stress led to increased freezing mainly in WKYs. Conclusion Data suggest that differences in stressfulness of these tests predict the behavior of the two strains of animals according to their stress-reactivity and coping style, but that repeated testing can overcome some of these differences.

  18. Context and strain-dependent behavioral response to stress

    Science.gov (United States)

    Nosek, Katarzyna; Dennis, Kristen; Andrus, Brian M; Ahmadiyeh, Nasim; Baum, Amber E; Woods, Leah C Solberg; Redei, Eva E

    2008-01-01

    Background This study posed the question whether strain differences in stress-reactivity lead to differential behavioral responses in two different tests of anxiety. Strain differences in anxiety-measures are known, but strain differences in the behavioral responses to acute prior stress are not well characterized. Methods We studied male Fisher 344 (F344) and Wistar Kyoto (WKY) rats basally and immediately after one hour restraint stress. To distinguish between the effects of novelty and prior stress, we also investigated behavior after repeated exposure to the test chamber. Two behavioral tests were explored; the elevated plus maze (EPM) and the open field (OFT), both of which are thought to measure activity, exploration and anxiety-like behaviors. Additionally, rearing, a voluntary behavior, and grooming, a relatively automatic, stress-responsive stereotyped behavior were measured in both tests. Results Prior exposure to the test environment increased anxiety-related measures regardless of prior stress, reflecting context-dependent learning process in both tests and strains. Activity decreased in response to repeated testing in both tests and both strains, but prior stress decreased activity only in the OFT which was reversed by repeated testing. Prior stress decreased anxiety-related measures in the EPM, only in F344s, while in the OFT, stress led to increased freezing mainly in WKYs. Conclusion Data suggest that differences in stressfulness of these tests predict the behavior of the two strains of animals according to their stress-reactivity and coping style, but that repeated testing can overcome some of these differences. PMID:18518967

  19. The Effect of Practice Schedule on Context-Dependent Learning.

    Science.gov (United States)

    Lee, Ya-Yun; Fisher, Beth E

    2018-03-02

    It is well established that random practice compared to blocked practice enhances motor learning. Additionally, while information in the environment may be incidental, learning is also enhanced when an individual performs a task within the same environmental context in which the task was originally practiced. This study aimed to disentangle the effects of practice schedule and incidental/environmental context on motor learning. Participants practiced three finger sequences under either a random or blocked practice schedule. Each sequence was associated with specific incidental context (i.e., color and location on the computer screen) during practice. The participants were tested under the conditions when the sequence-context associations remained the same or were changed from that of practice. When the sequence-context association was changed, the participants who practiced under blocked schedule demonstrated greater performance decrement than those who practiced under random schedule. The findings suggested that those participants who practiced under random schedule were more resistant to the change of environmental context.

  20. Models for dependent time series

    CERN Document Server

    Tunnicliffe Wilson, Granville; Haywood, John

    2015-01-01

    Models for Dependent Time Series addresses the issues that arise and the methodology that can be applied when the dependence between time series is described and modeled. Whether you work in the economic, physical, or life sciences, the book shows you how to draw meaningful, applicable, and statistically valid conclusions from multivariate (or vector) time series data.The first four chapters discuss the two main pillars of the subject that have been developed over the last 60 years: vector autoregressive modeling and multivariate spectral analysis. These chapters provide the foundational mater

  1. Context-aware modeling of neuronal morphologies

    Directory of Open Access Journals (Sweden)

    Benjamin eTorben-Nielsen

    2014-09-01

    Full Text Available Neuronal morphologies are pivotal for brain functioning: physical overlap between dendrites and axons constrain the circuit topology, and the precise shape and composition of dendrites determine the integration of inputs to produce an output signal. At the same time, morphologies are highly diverse and variant. The variance, presumably, originates from neurons developing in a densely packed brain substrate where they interact (e.g., repulsion or attraction with other actors in this substrate. However, when studying neurons their context is never part of the analysis and they are treated as if they existed in isolation.Here we argue that to fully understand neuronal morphology and its variance it is important to consider neurons in relation to each other and to other actors in the surrounding brain substrate, i.e., their context. We propose a context-aware computational framework, NeuroMaC, in which large numbers of neurons can be grown simultaneously according to growth rules expressed in terms of interactions between the developing neuron and the surrounding brain substrate.As a proof of principle, we demonstrate that by using NeuroMaC we can generate accurate virtual morphologies of distinct classes both in isolation and as part of neuronal forests. Accuracy is validated against population statistics of experimentally reconstructed morphologies. We show that context-aware generation of neurons can explain characteristics of variation. Indeed, plausible variation is an inherent property of the morphologies generated by context-aware rules. We speculate about the applicability of this framework to investigate morphologies and circuits, to classify healthy and pathological morphologies, and to generate large quantities of morphologies for large-scale modeling.

  2. Significance of chemical recognition cues is context dependent in ants

    DEFF Research Database (Denmark)

    Bos, N.; Guerrieri, F.J.; d'Ettorre, P.

    2010-01-01

    used as training odour in our experiments. This suggests that ants, like some, but not all other insects, show interactions between different modalities (i.e. olfactory and visual), and can treat complex chemical cues differently, according to the context in which they are perceived. This plasticity...

  3. Dependency in Caregiving Contexts : The Role of Personality

    OpenAIRE

    Burmedi, David

    2002-01-01

    This paper examines the personality correlates of behavioral dependency and morale among 114 elderly care recipients. The research draws on a trait personality and person-environment perspective in order to understand factors which influence dependency in home and institutional environments. Subjects completed standardized scales of trait dependency, affiliation, and respect for authority. Measures of stoicism, caregiver affiliation, and respect for medical authority, which were specially des...

  4. Context-dependent preferences in starlings: linking ecology, foraging and choice.

    Directory of Open Access Journals (Sweden)

    Marco Vasconcelos

    Full Text Available Foraging animals typically encounter opportunities that they either pursue or skip, but occasionally meet several alternatives simultaneously. Behavioural ecologists predict preferences using absolute properties of each option, while decision theorists focus on relative evaluations at the time of choice. We use European starlings (Sturnus vulgaris to integrate ecological reasoning with decision models, linking and testing hypotheses for value acquisition and choice mechanism. We hypothesise that options' values depend jointly on absolute attributes, learning context, and subject's state. In simultaneous choices, preference could result either from comparing subjective values using deliberation time, or from processing each alternative independently, without relative comparisons. The combination of the value acquisition hypothesis and independent processing at choice time has been called the Sequential Choice Model. We test this model with options equated in absolute properties to exclude the possibility of preference being built at the time of choice. Starlings learned to obtain food by responding to four stimuli in two contexts. In context [AB], they encountered options A5 or B10 in random alternation; in context [CD], they met C10 or D20. Delay to food is denoted, in seconds, by the suffixes. Observed latency to respond (Li to each option alone (our measure of value ranked thus: LA≈LCcontext. We then introduced simultaneous presentations of A5 vs. C10 and B10 vs. C10, using latencies in no-choice tests to predict sign and strength of preference in pairings. Starlings preferred A5 over C10 and C10 over B10. There was no detectable evaluation time, and preference magnitude was predictable from latency differentials. This implies that value reflects learning rather than choice context, that preferences are not constructed by relative judgements at the time of choice

  5. Knowledge-Based Environmental Context Modeling

    Science.gov (United States)

    Pukite, P. R.; Challou, D. J.

    2017-12-01

    As we move from the oil-age to an energy infrastructure based on renewables, the need arises for new educational tools to support the analysis of geophysical phenomena and their behavior and properties. Our objective is to present models of these phenomena to make them amenable for incorporation into more comprehensive analysis contexts. Starting at the level of a college-level computer science course, the intent is to keep the models tractable and therefore practical for student use. Based on research performed via an open-source investigation managed by DARPA and funded by the Department of Interior [1], we have adapted a variety of physics-based environmental models for a computer-science curriculum. The original research described a semantic web architecture based on patterns and logical archetypal building-blocks (see figure) well suited for a comprehensive environmental modeling framework. The patterns span a range of features that cover specific land, atmospheric and aquatic domains intended for engineering modeling within a virtual environment. The modeling engine contained within the server relied on knowledge-based inferencing capable of supporting formal terminology (through NASA JPL's Semantic Web for Earth and Environmental Technology (SWEET) ontology and a domain-specific language) and levels of abstraction via integrated reasoning modules. One of the key goals of the research was to simplify models that were ordinarily computationally intensive to keep them lightweight enough for interactive or virtual environment contexts. The breadth of the elements incorporated is well-suited for learning as the trend toward ontologies and applying semantic information is vital for advancing an open knowledge infrastructure. As examples of modeling, we have covered such geophysics topics as fossil-fuel depletion, wind statistics, tidal analysis, and terrain modeling, among others. Techniques from the world of computer science will be necessary to promote efficient

  6. The Contextual Map - A Context Model for Detecting Affinity between Contexts

    Science.gov (United States)

    Schmohl, Robert; Baumgarten, Uwe

    Context-awareness represents an important research domain in mobile computing by utilizing information about persons, places and objects anytime and anywhere. The highly dynamic contexts created by this paradigm raise questions how to efficiently determine alikeness and affinity between such contexts. Inspired by mechanisms from location-aware computing, we tackle the issue of contextual proximity by constructing an n-dimensional map-model, which serves as a context model for regular context repositories. This Contextual Map enables us to store non-location contexts in a map-based way. Further, this model enables us to conduct location-based n-dimensional proximity detection on the non-location contexts, hence giving us the possibility to determine contextual proximity. This paper introduces the contextual map model, describing how principles from the location-based service domain can be leveraged on general context-aware computing and how they can be employed to detect affinities between different contexts.

  7. Context-dependent Trust Decisions with Subjective Logic

    OpenAIRE

    Cerutti, Federico; Toniolo, Alice; Oren, Nir; Norman, Timothy J.

    2013-01-01

    A decision procedure implemented over a computational trust mechanism aims to allow for decisions to be made regarding whether some entity or information should be trusted. As recognised in the literature, trust is contextual, and we describe how such a context often translates into a confidence level which should be used to modify an underlying trust value. J{\\o}sang's Subjective Logic has long been used in the trust domain, and we show that its operators are insufficient to address this pro...

  8. Business model innovation in SME context

    DEFF Research Database (Denmark)

    Madsen, Svend Ole; Brink, Tove

    2014-01-01

    The purpose of this article is to reveal how small and medium sized enterprises (SMEs) can enable sustainable business model innovation (BMI) in the offshore wind turbine industry. A longitudinal empirical research on 10 SMEs within the wind turbine industry provides data for the findings....... The findings reveal interesting opportunities for BMI both within the SMEs, the SME network and in wider industrial context to increase awareness on business opportunities to act and hereby increase sustainable value. However, also boundaries occur for BMI, which can be difficult to crisscross. It is revealed...... for sustainable value is present, however also considerable risk to fail....

  9. The climate impacts of bioenergy systems depend on market and regulatory policy contexts.

    Science.gov (United States)

    Lemoine, Derek M; Plevin, Richard J; Cohn, Avery S; Jones, Andrew D; Brandt, Adam R; Vergara, Sintana E; Kammen, Daniel M

    2010-10-01

    Biomass can help reduce greenhouse gas (GHG) emissions by displacing petroleum in the transportation sector, by displacing fossil-based electricity, and by sequestering atmospheric carbon. Which use mitigates the most emissions depends on market and regulatory contexts outside the scope of attributional life cycle assessments. We show that bioelectricity's advantage over liquid biofuels depends on the GHG intensity of the electricity displaced. Bioelectricity that displaces coal-fired electricity could reduce GHG emissions, but bioelectricity that displaces wind electricity could increase GHG emissions. The electricity displaced depends upon existing infrastructure and policies affecting the electric grid. These findings demonstrate how model assumptions about whether the vehicle fleet and bioenergy use are fixed or free parameters constrain the policy questions an analysis can inform. Our bioenergy life cycle assessment can inform questions about a bioenergy mandate's optimal allocation between liquid fuels and electricity generation, but questions about the optimal level of bioenergy use require analyses with different assumptions about fixed and free parameters.

  10. Neurobiological Correlates of State-Dependent Context Fear

    Science.gov (United States)

    Meyer, Mariah A. A.; Corcoran, Kevin A.; Chen, Helen J.; Gallego, Sonia; Li, Guanguan; Tiruveedhula, Veda V.; Cook, James M.; Radulovic, Jelena

    2017-01-01

    Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic ?-aminobutyric acid type A receptors (GABAAR) with the broad a-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits…

  11. Context-Dependent Modulation of GABAAR-Mediated Tonic Currents

    DEFF Research Database (Denmark)

    Patel, Bijal; Bright, Damian P; Mortensen, Martin

    2016-01-01

    of neurological disorders. Consequently, developing compounds to selectively modulate the activity of extrasynaptic GABAA receptors underlying tonic inhibition is likely to prove therapeutically useful. Here, we examine the GABAA receptor subtype selectivity of the weak partial agonist, 5-(4-piperidyl)isoxazol-3......-ol (4-PIOL), as a potential mechanism for modulating extrasynaptic GABAA receptor-mediated tonic currents. By using recombinant GABAA receptors expressed in HEK293 cells, and native GABAA receptors of cerebellar granule cells, hippocampal neurons, and thalamic relay neurons, 4-PIOL evidently...... displayed differential agonist and antagonist-type profiles, depending on the extrasynaptic GABAA receptor isoforms targeted. For neurons, this resulted in differential modulation of GABA tonic currents, depending on the cell type studied, their respective GABAA receptor subunit compositions, and critically...

  12. Robust Visual Tracking via Exclusive Context Modeling

    KAUST Repository

    Zhang, Tianzhu

    2015-02-09

    In this paper, we formulate particle filter-based object tracking as an exclusive sparse learning problem that exploits contextual information. To achieve this goal, we propose the context-aware exclusive sparse tracker (CEST) to model particle appearances as linear combinations of dictionary templates that are updated dynamically. Learning the representation of each particle is formulated as an exclusive sparse representation problem, where the overall dictionary is composed of multiple {group} dictionaries that can contain contextual information. With context, CEST is less prone to tracker drift. Interestingly, we show that the popular L₁ tracker [1] is a special case of our CEST formulation. The proposed learning problem is efficiently solved using an accelerated proximal gradient method that yields a sequence of closed form updates. To make the tracker much faster, we reduce the number of learning problems to be solved by using the dual problem to quickly and systematically rank and prune particles in each frame. We test our CEST tracker on challenging benchmark sequences that involve heavy occlusion, drastic illumination changes, and large pose variations. Experimental results show that CEST consistently outperforms state-of-the-art trackers.

  13. The sound of arousal in music is context-dependent.

    Science.gov (United States)

    Blumstein, Daniel T; Bryant, Gregory A; Kaye, Peter

    2012-10-23

    Humans, and many non-human animals, produce and respond to harsh, unpredictable, nonlinear sounds when alarmed, possibly because these are produced when acoustic production systems (vocal cords and syrinxes) are overblown in stressful, dangerous situations. Humans can simulate nonlinearities in music and soundtracks through the use of technological manipulations. Recent work found that film soundtracks from different genres differentially contain such sounds. We designed two experiments to determine specifically how simulated nonlinearities in soundtracks influence perceptions of arousal and valence. Subjects were presented with emotionally neutral musical exemplars that had neither noise nor abrupt frequency transitions, or versions of these musical exemplars that had noise or abrupt frequency upshifts or downshifts experimentally added. In a second experiment, these acoustic exemplars were paired with benign videos. Judgements of both arousal and valence were altered by the addition of these simulated nonlinearities in the first, music-only, experiment. In the second, multi-modal, experiment, valence (but not arousal) decreased with the addition of noise or frequency downshifts. Thus, the presence of a video image suppressed the ability of simulated nonlinearities to modify arousal. This is the first study examining how nonlinear simulations in music affect emotional judgements. These results demonstrate that the perception of potentially fearful or arousing sounds is influenced by the perceptual context and that the addition of a visual modality can antagonistically suppress the response to an acoustic stimulus.

  14. Context-dependent concurrent adaptation to static and moving targets.

    Directory of Open Access Journals (Sweden)

    Maria N Ayala

    Full Text Available Is the neural control of movements towards moving targets independent to that of static targets? In the following experiments, we used a visuomotor rotation adaptation paradigm to examine the extent to which adapting arm movements to static targets generalize to that of moving targets (i.e. pursuit or tracking. In the first and second experiments, we showed that adaptation to perturbed tracking movements generalizes to reaching movements; reach aftereffects following perturbed tracking were about half the size (≈9° of those produced following reach training (≈ 19°. Given these findings, in the final experiment we associated opposing perturbations (-30° and +30° with either reaching or tracking movements and presented them within the same experimental block to determine whether these contexts allow for dual adaptation. We found that the group that experienced opposing perturbations was able to reduce both reaching and tracking errors, as well as produce reach aftereffects following dual training of ≈7°, which were substantially smaller than those produced when reach training was not concurrent with tracking training. This reduction in reach aftereffects is consistent with the extent of the interference from tracking training as measured by the reach aftereffects produced when only that condition was performed. These results suggest partial, but not complete, overlap in the learning processes involved in the acquisition of tracking and reaching movements.

  15. Context-dependence of Aimed Arm Movements: A Transitory or A Stable Phenomenon?

    Directory of Open Access Journals (Sweden)

    Benjamin Baak

    2014-10-01

    Full Text Available Previous work documented that grasping movements in a typical laboratory context differ widely from those in a more natural context. We evaluate whether this context-dependence changes with experience. Data from 48 subjects (24 female; 24.9 ± 2.7 years of age were (reanalyzed. They had participated in experimental blocks with externally triggered, purposeless and repetitive movements (context L, laboratory-like, and a block with self-initiated, ecologically valid movements embedded in a complex task (context E, everyday-like. Mechanical constraints on grasping were identical in both blocks. A global metric, representing context-dependence across multiple kinematic parameters, did not change appreciably across the 20 trials of a block. Furthermore, the metric was not affected by prior participation in the other block. We conclude that context-dependence of grasping is robust, i.e., it shows little influence of prior experience. This opens the avenue for within-subject designs on context-dependence, e.g., for clinical investigations. Keywords: Motor control, Prehension, Context-dependence, Serial order, Attunement

  16. Context-Dependent Conflation, Text Filtering and Clustering

    Science.gov (United States)

    2004-09-01

    2003). Document clustering into an unknown number of clusters using a genetic algorithm. Text, Speech and Dialogue, Proceedings, 2807. Lecture... Chameleon : A hierarchical clustering algorithm using dynamic modeling. IEEE Computer: Special Issue on Data Analysis and Mining 32(8). 68-75

  17. U.S. oil dependence in a global context

    International Nuclear Information System (INIS)

    Mitchell, J.V.

    2002-05-01

    The plan of this paper is to review the role of the US in the evolution of international energy security in the past; to examine the present situation and outlook for international energy trade and investment on which the US, and most major consuming countries depend, and, finally, to speculate about the possible effect on energy security of the war against terrorism. It seems that, the slogans of past energy security are not a good guide to the present problems. All industrial countries depend to some extent on imported energy supplies, but have the capacity to pay for imports over a wide range of price scenarios. Price stability is not to be expected: there will be short term shocks to both buyers and sellers, medium term cycles with leads and lags in adjusting supply capacity to demand, and long term uncertainty about the effects of policies aimed at sustainability and protecting the climate. The diversity and flexibility of international trade and investment offers the best long and medium term security and is most likely to achieve adjustments at lowest cost. Competition between oil and other fuels, and between major oil exporters to secure markets for their oil reserves, will limit the possibilities for cartel behaviour. Short-term disruptions do, however, create problems. These have been managed during the last twenty years by a combination of actual or potential use of strategic stocks by importers and reserve capacity by OPEC exporters, particularly Saudi Arabia. The role of Saudi Arabia cannot be separated from its political relationships within the Middle East and with the US. The immense flexibility of policy which the US now enjoys as a superpower could be eroded by a weakening of the acceptance the US receives from governments in the Middle East. In the last resort, if the international system fails, the US and Europe could survive the termination of oil imports from the Middle East; Asia could not, and the consequences for the world economy including

  18. U.S. oil dependence in a global context

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J.V. [Royal Institute of Interantional Relations, Londres (United Kingdom)

    2002-05-15

    The plan of this paper is to review the role of the US in the evolution of international energy security in the past; to examine the present situation and outlook for international energy trade and investment on which the US, and most major consuming countries depend, and, finally, to speculate about the possible effect on energy security of the war against terrorism. It seems that, the slogans of past energy security are not a good guide to the present problems. All industrial countries depend to some extent on imported energy supplies, but have the capacity to pay for imports over a wide range of price scenarios. Price stability is not to be expected: there will be short term shocks to both buyers and sellers, medium term cycles with leads and lags in adjusting supply capacity to demand, and long term uncertainty about the effects of policies aimed at sustainability and protecting the climate. The diversity and flexibility of international trade and investment offers the best long and medium term security and is most likely to achieve adjustments at lowest cost. Competition between oil and other fuels, and between major oil exporters to secure markets for their oil reserves, will limit the possibilities for cartel behaviour. Short-term disruptions do, however, create problems. These have been managed during the last twenty years by a combination of actual or potential use of strategic stocks by importers and reserve capacity by OPEC exporters, particularly Saudi Arabia. The role of Saudi Arabia cannot be separated from its political relationships within the Middle East and with the US. The immense flexibility of policy which the US now enjoys as a superpower could be eroded by a weakening of the acceptance the US receives from governments in the Middle East. In the last resort, if the international system fails, the US and Europe could survive the termination of oil imports from the Middle East; Asia could not, and the consequences for the world economy including

  19. Context dependent memory in two learning environments: the tutorial room and the operating theatre.

    Science.gov (United States)

    Coveney, Andrew P; Switzer, Timothy; Corrigan, Mark A; Redmond, Henry P

    2013-09-01

    Psychologists have previously demonstrated that information recall is context dependent. However, how this influences the way we deliver medical education is unclear. This study aimed to determine if changing the recall context from the learning context affects the ability of medical students to recall information. Using a free recall experimental model, fourteen medical student participants were administered audio lists of 30 words in two separate learning environments, a tutorial room and an operating theatre. They were then asked to recall the words in both environments. While in the operating theatre participants wore appropriate surgical clothing and assembled around an operating table. While in the tutorial room, participants dressed casually and were seated around a table. Students experienced the same duration (15 minutes) and disruption in both environments. The mean recall score from the 28 tests performed in the same environment was 12.96 +/- 3.93 (mean, SD). The mean recall score from the 28 tests performed in an alternative environment to the learning episode was 13.5 +/- 5.31(mean, SD), indicating that changing the recall environment from the learning environment does not cause any statistical difference (p=0.58). The average recall score of participants who learned and recalled in the tutorial room was 13.0 +/- 3.84 (mean, SD). The average recall score of participants who learnt and recalled in the operating theatre was 12.92 +/- 4.18 (mean, SD), representing no significant difference between the two environments for learning (p=0.4792). The results support the continued use of tutorial rooms and operating theatres as appropriate environments in which to teach medical students, with no significant difference in information recall seen either due to a same context effect or specific context effect.

  20. Characterizing QALYs under a General Rank Dependent Utility Model

    NARCIS (Netherlands)

    H. Bleichrodt (Han); J. Quiggin (John)

    1997-01-01

    textabstractThis paper provides a characterization of QALYs, the most important outcome measure in medical decision making, in the context of a general rank dependent utility model. We show that both for chronic and for nonchronic health states the characterization of QALYs depends on intuitive

  1. Context-dependent antagonism between Akt inhibitors and topoisomerase poisons.

    Science.gov (United States)

    Gálvez-Peralta, Marina; Flatten, Karen S; Loegering, David A; Peterson, Kevin L; Schneider, Paula A; Erlichman, Charles; Kaufmann, Scott H

    2014-05-01

    Signaling through the phosphatidylinositol-3 kinase (PI3K)/Akt pathway, which is aberrantly activated in >50% of carcinomas, inhibits apoptosis and contributes to drug resistance. Accordingly, several Akt inhibitors are currently undergoing preclinical or early clinical testing. To examine the effect of Akt inhibition on the activity of multiple widely used classes of antineoplastic agents, human cancer cell lines were treated with the Akt inhibitor A-443654 [(2S)-1-(1H-indol-3-yl)-3-[5-(3-methyl-2H-indazol-5-yl)pyridin-3-yl]oxypropan-2-amine; ATP-competitive] or MK-2206 (8-[4-(1-aminocyclobutyl)phenyl]-9-phenyl-2H-[1,2,4]triazolo[3,4-f][1,6]naphthyridin-3-one;dihydrochloride; allosteric inhibitor) or with small interfering RNA (siRNA) targeting phosphoinositide-dependent kinase 1 (PDK1) along with cisplatin, melphalan, camptothecin, or etoposide and assayed for colony formation. Surprisingly different results were observed when Akt inhibitors were combined with different drugs. Synergistic effects were observed in multiple cell lines independent of PI3K pathway status when A-443654 or MK-2206 was combined with the DNA cross-linking agents cisplatin or melphalan. In contrast, effects of the Akt inhibitors in combination with camptothecin or etoposide were more complicated. In HCT116 and DLD1 cells, which harbor activating PI3KCA mutations, A-443654 over a broad concentration range enhanced the effects of camptothecin or etoposide. In contrast, in cell lines lacking activating PI3KCA mutations, partial inhibition of Akt signaling synergized with camptothecin or etoposide, but higher A-443654 or MK-2206 concentrations (>80% inhibition of Akt signaling) or PDK1 siRNA antagonized the topoisomerase poisons by diminishing DNA synthesis, a process that contributes to effective DNA damage and killing by these agents. These results indicate that the effects of combining inhibitors of the PI3K/Akt pathway with certain classes of chemotherapeutic agents might be more

  2. Context-dependent medicinal effects of anabasine and infection-dependent toxicity in bumble bees.

    Science.gov (United States)

    Palmer-Young, Evan C; Hogeboom, Alison; Kaye, Alexander J; Donnelly, Dash; Andicoechea, Jonathan; Connon, Sara June; Weston, Ian; Skyrm, Kimberly; Irwin, Rebecca E; Adler, Lynn S

    2017-01-01

    tritrophic interactions by both host genotype and environmental variables. Overall, our results demonstrate that Bombus impatiens prefer diets without nicotine and anabasine, and suggest that the medicinal effects and toxicity of anabasine may be context dependent. Future research should identify the specific environmental and genotypic factors that determine whether nectar phytochemicals have medicinal or deleterious effects on pollinators.

  3. Context-dependent medicinal effects of anabasine and infection-dependent toxicity in bumble bees.

    Directory of Open Access Journals (Sweden)

    Evan C Palmer-Young

    modulation of tritrophic interactions by both host genotype and environmental variables. Overall, our results demonstrate that Bombus impatiens prefer diets without nicotine and anabasine, and suggest that the medicinal effects and toxicity of anabasine may be context dependent. Future research should identify the specific environmental and genotypic factors that determine whether nectar phytochemicals have medicinal or deleterious effects on pollinators.

  4. How Recommender Systems in Technology-Enhanced Learning depend on Context

    NARCIS (Netherlands)

    Drachsler, Hendrik; Manouselis, Nikos

    2009-01-01

    Drachsler, H., & Manouselis, N. (2009). How Recommender Systems in Technology-Enhanced Learning depend on Context. Presentation given at the 1st workshop on Context-aware Recommender Systems for Learning at the Alpine Rendez-Vous 2009. November, 30 - December, 3, 2009, Garmisch-Patenkirchen,

  5. Modelling dynamics with context-free grammars

    Science.gov (United States)

    García-Huerta, Juan-M.; Jiménez-Hernández, Hugo; Herrera-Navarro, Ana-M.; Hernández-Díaz, Teresa; Terol-Villalobos, Ivan

    2014-03-01

    This article presents a strategy to model the dynamics performed by vehicles in a freeway. The proposal consists on encode the movement as a set of finite states. A watershed-based segmentation is used to localize regions with high-probability of motion. Each state represents a proportion of a camera projection in a two-dimensional space, where each state is associated to a symbol, such that any combination of symbols is expressed as a language. Starting from a sequence of symbols through a linear algorithm a free-context grammar is inferred. This grammar represents a hierarchical view of common sequences observed into the scene. Most probable grammar rules express common rules associated to normal movement behavior. Less probable rules express themselves a way to quantify non-common behaviors and they might need more attention. Finally, all sequences of symbols that does not match with the grammar rules, may express itself uncommon behaviors (abnormal). The grammar inference is built with several sequences of images taken from a freeway. Testing process uses the sequence of symbols emitted by the scenario, matching the grammar rules with common freeway behaviors. The process of detect abnormal/normal behaviors is managed as the task of verify if any word generated by the scenario is recognized by the grammar.

  6. Context Dependent Effect of Landscape on the Occurrence of an Apex Predator across Different Climate Regions.

    Science.gov (United States)

    Fujita, Go; Azuma, Atsuki; Nonaka, Jun; Sakai, Yoshiaki; Sakai, Hatsumi; Iseki, Fumitaka; Itaya, Hiroo; Fukasawa, Keita; Miyashita, Tadashi

    2016-01-01

    In studies of habitat suitability at landscape scales, transferability of species-landscape associations among sites are likely to be critical because it is often impractical to collect datasets across various regions. However, limiting factors, such as prey availability, are not likely to be constant across scales because of the differences in species pools. This is particularly true for top predators that are often the target for conservation concern. Here we focus on gray-faced buzzards, apex predators of farmland-dominated landscapes in East Asia. We investigated context dependency of "buzzard-landscape relationship", using nest location datasets from five sites, each differing in landscape composition. Based on the similarities of prey items and landscape compositions across the sites, we determined several alternative ways of grouping the sites, and then examined whether buzzard-landscape relationship change among groups, which was conducted separately for each way of grouping. As a result, the model of study-sites grouping based on similarities in prey items showed the smallest ΔAICc. Because the terms of interaction between group IDs and areas of broad-leaved forests and grasslands were selected, buzzard-landscape relationship showed a context dependency, i.e., these two landscape elements strengthen the relationship in southern region. The difference in prey fauna, which is associated with the difference in climate, might generate regional differences in the buzzard-landscape associations.

  7. Nitric oxide regulates input specificity of long-term depression and context dependence of cerebellar learning.

    Directory of Open Access Journals (Sweden)

    Hideaki Ogasawara

    2007-01-01

    Full Text Available Recent studies have shown that multiple internal models are acquired in the cerebellum and that these can be switched under a given context of behavior. It has been proposed that long-term depression (LTD of parallel fiber (PF-Purkinje cell (PC synapses forms the cellular basis of cerebellar learning, and that the presynaptically synthesized messenger nitric oxide (NO is a crucial "gatekeeper" for LTD. Because NO diffuses freely to neighboring synapses, this volume learning is not input-specific and brings into question the biological significance of LTD as the basic mechanism for efficient supervised learning. To better characterize the role of NO in cerebellar learning, we simulated the sequence of electrophysiological and biochemical events in PF-PC LTD by combining established simulation models of the electrophysiology, calcium dynamics, and signaling pathways of the PC. The results demonstrate that the local NO concentration is critical for induction of LTD and for its input specificity. Pre- and postsynaptic coincident firing is not sufficient for a PF-PC synapse to undergo LTD, and LTD is induced only when a sufficient amount of NO is provided by activation of the surrounding PFs. On the other hand, above-adequate levels of activity in nearby PFs cause accumulation of NO, which also allows LTD in neighboring synapses that were not directly stimulated, ruining input specificity. These findings lead us to propose the hypothesis that NO represents the relevance of a given context and enables context-dependent selection of internal models to be updated. We also predict sparse PF activity in vivo because, otherwise, input specificity would be lost.

  8. Cell Context Dependent p53 Genome-Wide Binding Patterns and Enrichment at Repeats

    Science.gov (United States)

    Botcheva, Krassimira; McCorkle, Sean R.

    2014-01-01

    The p53 ability to elicit stress specific and cell type specific responses is well recognized, but how that specificity is established remains to be defined. Whether upon activation p53 binds to its genomic targets in a cell type and stress type dependent manner is still an open question. Here we show that the p53 binding to the human genome is selective and cell context-dependent. We mapped the genomic binding sites for the endogenous wild type p53 protein in the human cancer cell line HCT116 and compared them to those we previously determined in the normal cell line IMR90. We report distinct p53 genome-wide binding landscapes in two different cell lines, analyzed under the same treatment and experimental conditions, using the same ChIP-seq approach. This is evidence for cell context dependent p53 genomic binding. The observed differences affect the p53 binding sites distribution with respect to major genomic and epigenomic elements (promoter regions, CpG islands and repeats). We correlated the high-confidence p53 ChIP-seq peaks positions with the annotated human repeats (UCSC Human Genome Browser) and observed both common and cell line specific trends. In HCT116, the p53 binding was specifically enriched at LINE repeats, compared to IMR90 cells. The p53 genome-wide binding patterns in HCT116 and IMR90 likely reflect the different epigenetic landscapes in these two cell lines, resulting from cancer-associated changes (accumulated in HCT116) superimposed on tissue specific differences (HCT116 has epithelial, while IMR90 has mesenchymal origin). Our data support the model for p53 binding to the human genome in a highly selective manner, mobilizing distinct sets of genes, contributing to distinct pathways. PMID:25415302

  9. Context-dependent effects of background colour in free recall with spatially grouped words.

    Science.gov (United States)

    Sakai, Tetsuya; Isarida, Toshiko K; Isarida, Takeo

    2010-10-01

    Three experiments investigated context-dependent effects of background colour in free recall with groups of items. Undergraduates (N=113) intentionally studied 24 words presented in blocks of 6 on a computer screen with two different background colours. The two background colours were changed screen-by-screen randomly (random condition) or alternately (alternation condition) during the study period. A 30-second filled retention interval was imposed before an oral free-recall test. A signal for free recall was presented throughout the test on one of the colour background screens presented at study. Recalled words were classified as same- or different-context words according to whether the background colours at study and test were the same or different. The random condition produced significant context-dependent effects, whereas the alternation condition showed no context-dependent effects, regardless of whether the words were presented once or twice. Furthermore, the words presented on the same screen were clustered in recall, whereas the words presented against the same background colour but on different screens were not clustered. The present results imply: (1) background colours can cue spatially massed words; (2) background colours act as temporally local context; and (3) predictability of the next background colour modulates the context-dependent effect.

  10. Ensemble coding of context-dependent fear memory in the amygdala

    Directory of Open Access Journals (Sweden)

    Caitlin A Orsini

    2013-12-01

    Full Text Available After fear conditioning, presenting the conditioned stimulus (CS alone yields a context-specific extinction memory; fear is suppressed in the extinction context, but renews in any other context. The context-dependence of extinction is mediated by a brain circuit consisting of the hippocampus, prefrontal cortex and amygdala. In the present work, we sought to determine at what level of this circuit context-dependent representations of the CS emerge. To explore this question, we used cellular compartment analysis of temporal activity by fluorescent in situ hybridization (catFISH. This method exploits the intracellular expression profile of the immediate early gene, Arc, to visualize neuronal activation patterns to two different behavioral experiences. Rats were fear conditioned in one context and extinguished in another; twenty-four hours later, they were sequentially exposed to the CS in the extinction context and another context. Control rats were also tested in each context, but were never extinguished. We assessed Arc mRNA expression within the basal amygdala (BA, lateral amygdala (LA, ventral hippocampus (VH, prelimbic cortex (PL and infralimbic cortex (IL. We observed that the sequential retention tests induced context-dependent patterns of Arc expression in the BA, LA, and IL of extinguished rats; this was not observed in non-extinguished controls. In general, non-extinguished animals had proportionately greater numbers of non-selective (double-labeled neurons than extinguished animals. Collectively, these findings suggest that extinction learning results in pattern separation, particularly within the BA, in which unique neuronal ensembles represent fear memories after extinction.

  11. Context-dependent autoprocessing of human immunodeficiency virus type 1 protease precursors.

    Directory of Open Access Journals (Sweden)

    ChihFeng Tien

    Full Text Available HIV-1 protease autoprocessing is responsible for liberation of free mature protease (PR from the Gag-Pol polyprotein precursor. A cell-based model system was previously developed to examine the autoprocessing mechanism of fusion precursors carrying the p6*-PR miniprecursor sandwiched between various proteins or epitopes. We here report that precursor autoprocessing is context-dependent as its activity and outcomes can be modulated by sequences upstream of p6*-PR. This was exemplified by the 26aa maltose binding protein (MBP signal peptide (SigP when placed at the N-terminus of a fusion precursor. The mature PRs released from SigP-carrying precursors are resistant to self-degradation whereas those released from SigP-lacking fusion precursors are prone to self-degradation. A H69D mutation in PR abolished autoprocessing of SigP-containing fusion precursors whereas it only partially suppressed autoprocessing of fusion precursors lacking SigP. An autoprocessing deficient GFP fusion precursor with SigP exhibited a subcellular distribution pattern distinct from the one without it in transfected HeLa cells. Furthermore, a SigP fusion precursor carrying a substitution at the P1 position released the mature PR and PR-containing fragments that were different from those released from the precursor carrying the same mutation but lacking SigP. We also examined autoprocessing outcomes in viral particles produced by a NL4-3 derived proviral construct and demonstrated the existence of several PR-containing fragments along with the mature PR. Some of these resembled the SigP precursor autoprocessing outcomes. This finding of context-dependent modulation reveals the complexity of precursor autoprocessing regulation that most likely accompanies sequence variation imposed by the evolution of the upstream Gag moiety.

  12. Compositional dependability modeling using arcade

    NARCIS (Netherlands)

    Stoelinga, Mariëlle Ida Antoinette; Huisman, Marieke

    Dependability is a key concern for today's complex computer and communication systems. To make sure that such an application meets all its dependability requirements, a rigorous and systematic analysis is required. This talk introduces ARCADE, a formally well-rooted and extensible framework for

  13. Towards a Model of Context-Aware Infrastructure in Mobile ...

    African Journals Online (AJOL)

    The aim of this paper is to propose the main components of a system that provide a model for context aware architecture in mobile ubiquitous computing as a layered architecture. The modeled system provide services should be adapted according to context for end user application, that can be executed in a mobile device ...

  14. Modeling Domain Variability in Requirements Engineering with Contexts

    Science.gov (United States)

    Lapouchnian, Alexei; Mylopoulos, John

    Various characteristics of the problem domain define the context in which the system is to operate and thus impact heavily on its requirements. However, most requirements specifications do not consider contextual properties and few modeling notations explicitly specify how domain variability affects the requirements. In this paper, we propose an approach for using contexts to model domain variability in goal models. We discuss the modeling of contexts, the specification of their effects on system goals, and the analysis of goal models with contextual variability. The approach is illustrated with a case study.

  15. Context-dependent enhancer selection confers alternate modes of notch regulation on argos.

    Science.gov (United States)

    Housden, Benjamin E; Terriente-Felix, Ana; Bray, Sarah J

    2014-02-01

    Wiring between signaling pathways differs according to context, as exemplified by interactions between Notch and epidermal growth factor receptor (EGFR) pathways, which are cooperative in some contexts but antagonistic in others. To investigate mechanisms that underlie different modes of cross talk, we have focused on argos, an EGFR pathway regulator in Drosophila melanogaster which is upregulated by Notch in adult muscle progenitors but is repressed in the wing. Results show that the alternate modes of cross talk depend on the engagement of enhancers with opposite regulatory logic, which are selected by context-determining factors. This is likely to be a general mechanism for enabling the wiring between these pathways to switch according to context.

  16. Context-dependent motor skill: perceptual processing in memory-based sequence production

    NARCIS (Netherlands)

    Ruitenberg, M.F.L.; Abrahamse, E.L.; de Kleine, Elian; Verwey, Willem B.

    2012-01-01

    Previous studies have shown that motor sequencing skill can benefit from the reinstatement of the learning context—even with respect to features that are formally not required for appropriate task performance. The present study explored whether such context-dependence develops when sequence

  17. Context-dependent memory in two natural environments: on land and underwater

    Science.gov (United States)

    Godden, D. R.; Baddeley, A. D.

    1975-01-01

    In a free recall experiment, divers learn lists of words in two natural environments: on dry land and underwater, and recalled the words in either the environment of original learning, or in the alternative environment. A subsequent experiment related these actions to context-dependent memory. (Editor/RK)

  18. Emotion recognition specialization and context-dependent risk of anxiety and depression in adolescents

    NARCIS (Netherlands)

    Oldehinkel, Albertine J.; Hartman, Catharina A.; Van Oort, Floor V. A.; Nederhof, Esther

    Background Some adolescents function poorly in apparently benign environments, while others thrive despite hassles and difficulties. The aim of this study was to examine if adolescents with specialized skills in the recognition of either positive or negative emotions have a context-dependent risk of

  19. Olfactory Context-Dependent Memory and the Effects of Affective Congruency.

    Science.gov (United States)

    Hackländer, Ryan P M; Bermeitinger, Christina

    2017-10-31

    Odors have been claimed to be particularly effective mnemonic cues, possibly because of the strong links between olfaction and emotion processing. Indeed, past research has shown that odors can bias processing towards affectively congruent material. In order to determine whether this processing bias translates to memory, we conducted 2 olfactory-enhanced-context memory experiments where we manipulated affective congruency between the olfactory context and to-be-remembered material. Given the presumed importance of valence to olfactory perception, we hypothesized that memory would be best for affectively congruent material in the olfactory enhanced context groups. Across the 2 experiments, groups which encoded and retrieved material in the presence of an odorant exhibited better memory performance than groups that did not have the added olfactory context during encoding and retrieval. While context-enhanced memory was exhibited in the presence of both pleasant and unpleasant odors, there was no indication that memory was dependent on affective congruency between the olfactory context and the to-be-remembered material. While the results provide further support for the notion that odors can act as powerful contextual mnemonic cues, they call into question the notion that affective congruency between context and focal material is important for later memory performance. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Modeling Guidelines for Code Generation in the Railway Signaling Context

    Science.gov (United States)

    Ferrari, Alessio; Bacherini, Stefano; Fantechi, Alessandro; Zingoni, Niccolo

    2009-01-01

    Modeling guidelines constitute one of the fundamental cornerstones for Model Based Development. Their relevance is essential when dealing with code generation in the safety-critical domain. This article presents the experience of a railway signaling systems manufacturer on this issue. Introduction of Model-Based Development (MBD) and code generation in the industrial safety-critical sector created a crucial paradigm shift in the development process of dependable systems. While traditional software development focuses on the code, with MBD practices the focus shifts to model abstractions. The change has fundamental implications for safety-critical systems, which still need to guarantee a high degree of confidence also at code level. Usage of the Simulink/Stateflow platform for modeling, which is a de facto standard in control software development, does not ensure by itself production of high-quality dependable code. This issue has been addressed by companies through the definition of modeling rules imposing restrictions on the usage of design tools components, in order to enable production of qualified code. The MAAB Control Algorithm Modeling Guidelines (MathWorks Automotive Advisory Board)[3] is a well established set of publicly available rules for modeling with Simulink/Stateflow. This set of recommendations has been developed by a group of OEMs and suppliers of the automotive sector with the objective of enforcing and easing the usage of the MathWorks tools within the automotive industry. The guidelines have been published in 2001 and afterwords revisited in 2007 in order to integrate some additional rules developed by the Japanese division of MAAB [5]. The scope of the current edition of the guidelines ranges from model maintainability and readability to code generation issues. The rules are conceived as a reference baseline and therefore they need to be tailored to comply with the characteristics of each industrial context. Customization of these

  1. TOWARDS A MODEL OF CONTEXT-AWARE INFRASTRUCTURE ...

    African Journals Online (AJOL)

    model for context aware architecture in mobile ubiquitous computing as a layered architecture. ... context for end user application, that can be executed in a mobile device as mobile web or mobile application ..... guides, and proximity marketing are only few examples of location-aware applications. To support such ...

  2. Context-dependent flight speed: evidence for energetically optimal flight speed in the bat Pipistrellus kuhlii?

    Science.gov (United States)

    Grodzinski, Uri; Spiegel, Orr; Korine, Carmi; Holderied, Marc W

    2009-05-01

    at a context-dependent, energetically optimal flight speed.

  3. Conceptual modeling in social and physical contexts

    NARCIS (Netherlands)

    Wieringa, Roelf J.

    The history of the computing sciences shows a shift in attention from the syntactic properties of computation to the semantics of computing in the real world. A large part of this shift has been brought about by the introduction of conceptual modeling languages. In this paper I review this history

  4. Context Sensitive Modeling of Cancer Drug Sensitivity.

    Directory of Open Access Journals (Sweden)

    Bo-Juen Chen

    Full Text Available Recent screening of drug sensitivity in large panels of cancer cell lines provides a valuable resource towards developing algorithms that predict drug response. Since more samples provide increased statistical power, most approaches to prediction of drug sensitivity pool multiple cancer types together without distinction. However, pan-cancer results can be misleading due to the confounding effects of tissues or cancer subtypes. On the other hand, independent analysis for each cancer-type is hampered by small sample size. To balance this trade-off, we present CHER (Contextual Heterogeneity Enabled Regression, an algorithm that builds predictive models for drug sensitivity by selecting predictive genomic features and deciding which ones should-and should not-be shared across different cancers, tissues and drugs. CHER provides significantly more accurate models of drug sensitivity than comparable elastic-net-based models. Moreover, CHER provides better insight into the underlying biological processes by finding a sparse set of shared and type-specific genomic features.

  5. Relationships between bacterial community composition, functional trait composition and functioning are context dependent--but what is the context?

    Directory of Open Access Journals (Sweden)

    Ina Severin

    Full Text Available Bacterial communities are immensely diverse and drive many fundamental ecosystem processes. However, the role of bacterial community composition (BCC for functioning is still unclear. Here we evaluate the relative importance of BCC (from 454-sequencing, functional traits (from Biolog Ecoplates and environmental conditions for per cell biomass production (BPC; 3H-leucine incorporation in six data sets of natural freshwater bacterial communities. BCC explained significant variation of BPC in all six data sets and most variation in four. BCC measures based on 16S rRNA (active bacteria did not consistently explain more variation in BPC than measures based on the 16S rRNA-gene (total community, and adding phylogenetic information did not, in general, increase the explanatory power of BCC. In contrast to our hypothesis, the importance of BCC for BPC was not related to the anticipated dispersal rates in and out of communities. Functional traits, most notably the ability to use cyclic and aromatic compounds, as well as local environmental conditions, i.e. stoichiometric relationships of nutrients, explained some variation in all six data sets. In general there were weak associations between variation in BCC and variation in the functional traits contributing to productivity. This indicates that additional traits may be important for productivity as well. By comparing several data sets obtained in a similar way we conclude that no single measure of BCC was obviously better than another in explaining BPC. We identified some key functional traits for productivity, but although there was a coupling between BCC, functional traits and productivity, the strength of the coupling seems context dependent. However, the exact context is still unresolved.

  6. An interdisciplinary model of context morphology

    Directory of Open Access Journals (Sweden)

    Pál, Dániel Levente

    2016-07-01

    Full Text Available Using an abstract graph model we describe a hypothetical transformation of a literary entity through the active connections in the graph. First, we weakly define a set of transformations (“morphology” over a particular entity as a series of the recent activities distinguishing them into categories according to their effect on the entity. Second, to our conjecture, the emerging paths of forms are slowly abandoning the original “birth context”, shaping a decreased, cleaned set of entities, to replace the gap with entities derived from the dynamic set of “recipient context”.

  7. Turning art into mere illustration: concretizing art renders its influence context dependent.

    Science.gov (United States)

    Hagtvedt, Henrik; Patrick, Vanessa M

    2011-12-01

    Broadly speaking, artworks are accorded a special significance and are recognized as powerful communication tools. In the current research, the authors posit that the "specialness" of artworks may be diminished simply by emphasizing that which is depicted in them. This emphasis results in the artwork being viewed as a mere illustration rather than a work of art. Specifically, the influence of an "artwork as art" is context independent, but the influence of an "artwork as illustration" is context dependent. The authors demonstrate this phenomenon in two experiments, in the context of products associated with artworks. In a third experiment, they further demonstrate that an abstract (concrete) mind-set aligns with the influence of an artwork as art (illustration).

  8. Context-dependent effect of mood: the regulatory role of personality

    Directory of Open Access Journals (Sweden)

    Zajusz-Gawędzka Dominika

    2015-03-01

    Full Text Available This study explored the influence of the context-dependent effect of mood as well as individual differences in neuroticism and action vs. state/volatility orientation on predecisional processing in a multiattribute choice task. One hundred and twenty participants acquired information about choice options after filling out personality questionnaires. Results showed that participants in a positive mood processed the information longer in enjoy than in done-enough context. In turn, participants in a negative mood processed the information more selectively in enjoy than in done-enough context. It also appeared that this effect is reinforced for participants with low neuroticism and volatility orientation, while it is weakened for those with low neuroticism and action orientation. Results were interpreted in accordance with the differential-processual approach.

  9. Context discovery using attenuated Bloom codes: model description and validation

    NARCIS (Netherlands)

    Liu, F.; Heijenk, Geert

    A novel approach to performing context discovery in ad-hoc networks based on the use of attenuated Bloom filters is proposed in this report. In order to investigate the performance of this approach, a model has been developed. This document describes the model and its validation. The model has been

  10. and density-dependent quark mass model

    Indian Academy of Sciences (India)

    We report on the study of the mass–radius (–) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modification, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We find that the ...

  11. Context-dependent planktivory: interacting effects of turbidity and predation risk on adaptive foraging

    Science.gov (United States)

    Pangle, Kevin L.; Malinich, Timothy D.; Bunnell, David B.; DeVries, Dennis R.; Ludsin, Stuart A.

    2012-01-01

    By shaping species interactions, adaptive phenotypic plasticity can profoundly influence ecosystems. Predicting such outcomes has proven difficult, however, owing in part to the dependence of plasticity on the environmental context. Of particular relevance are environmental factors that affect sensory performance in organisms in ways that alter the tradeoffs associated with adaptive phenotypic responses. We explored the influence of turbidity, which simultaneously and differentially affects the sensory performance of consumers at multiple trophic levels, on the indirect effect of a top predator (piscivorous fish) on a basal prey resource (zooplankton) that is mediated through changes in the plastic foraging behavior of an intermediate consumer (zooplanktivorous fish). We first generated theoretical predictions of the adaptive foraging response of a zooplanktivore across wide gradients of turbidity and predation risk by a piscivore. Our model predicted that predation risk can change the negative relationship between intermediate consumer foraging and turbidity into a humped-shaped (unimodal) one in which foraging is low in both clear and highly turbid conditions due to foraging-related risk and visual constraints, respectively. Consequently, the positive trait-mediated indirect effect (TMIE) of the top predator on the basal resource is predicted to peak at low turbidity and decline thereafter until it reaches an asymptote of zero at intermediate turbidity levels (when foraging equals that which is predicted when the top predator is absent). We used field observations and a laboratory experiment to test our model predictions. In support, we found humped-shaped relationships between planktivory and turbidity for several zooplanktivorous fishes from diverse freshwater ecosystems with predation risk. Further, our experiment demonstrated that predation risk reduced zooplanktivory by yellow perch (Perca flavescens) at a low turbidity, but had no effect on consumption at

  12. Predicting invasive species impacts: a community module functional response approach reveals context dependencies.

    Science.gov (United States)

    Paterson, Rachel A; Dick, Jaimie T A; Pritchard, Daniel W; Ennis, Marilyn; Hatcher, Melanie J; Dunn, Alison M

    2015-03-01

    Predatory functional responses play integral roles in predator-prey dynamics, and their assessment promises greater understanding and prediction of the predatory impacts of invasive species. Other interspecific interactions, however, such as parasitism and higher-order predation, have the potential to modify predator-prey interactions and thus the predictive capability of the comparative functional response approach. We used a four-species community module (higher-order predator; focal native or invasive predators; parasites of focal predators; native prey) to compare the predatory functional responses of native Gammarus duebeni celticus and invasive Gammarus pulex amphipods towards three invertebrate prey species (Asellus aquaticus, Simulium spp., Baetis rhodani), thus, quantifying the context dependencies of parasitism and a higher-order fish predator on these functional responses. Our functional response experiments demonstrated that the invasive amphipod had a higher predatory impact (lower handling time) on two of three prey species, which reflects patterns of impact observed in the field. The community module also revealed that parasitism had context-dependent influences, for one prey species, with the potential to further reduce the predatory impact of the invasive amphipod or increase the predatory impact of the native amphipod in the presence of a higher-order fish predator. Partial consumption of prey was similar for both predators and occurred increasingly in the order A. aquaticus, Simulium spp. and B. rhodani. This was associated with increasing prey densities, but showed no context dependencies with parasitism or higher-order fish predator. This study supports the applicability of comparative functional responses as a tool to predict and assess invasive species impacts incorporating multiple context dependencies. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

  13. Binding and Normalization of Binary Sparse Distributed Representations by Context-Dependent Thinning

    OpenAIRE

    Rachkovskij, Dmitri A.; Kussul, Ernst M.

    2001-01-01

    Distributed representations were often criticized as inappropriate for encoding of data with a complex structure. However Plate's Holographic Reduced Representations and Kanerva's Binary Spatter Codes are recent schemes that allow on-the-fly encoding of nested compositional structures by real-valued or dense binary vectors of fixed dimensionality. In this paper we consider procedures of the Context-Dependent Thinning which were developed for representation of complex hierarchical items in the...

  14. Context-Dependent Prognostics and Health Assessment: A Condition-Based Maintenance Approach That Supports Mission Compliance

    Energy Technology Data Exchange (ETDEWEB)

    Allgood, G.O.; Kercel, S.W.

    1999-04-19

    In today's manufacturing environment, plants, systems, and equipment are being asked to perform at levels not thought possible a decade ago. The intent is to improve process operations and equipment reliability, availability, and maintainability without costly upgrades. Of course these gains must be achieved without impacting operational performance. Downsizing is also taking its toll on operations. Loss of personnel, particularly those who represent the corporate history, is depleting US industries of their valuable experiential base which has been relied on so heavily in the past. These realizations are causing companies to rethink their condition-based maintenance policies by moving away from reacting to equipment problems to taking a proactive approach by anticipating needs based on market and customer requirements. This paper describes a different approach to condition-based maintenance-context-dependent prognostics and health assessment. This diagnostic capability is developed around a context-dependent model that provides a capability to anticipate impending failures and determine machine performance over a protracted period of time. This prognostic capability links operational requirements to an economic performance model. In this context, a system may provide 100% operability with less than 100% functionality. This paradigm is used to facilitate optimal logistic supply and support.

  15. Exploring Context with Deep Structured models for Semantic Segmentation.

    Science.gov (United States)

    Lin, Guosheng; Shen, Chunhua; van den Hengel, Anton; Reid, Ian

    2017-05-26

    We propose an approach for exploiting contextual information in semantic image segmentation, and particularly investigate the use of patch-patch context and patch-background context in deep CNNs. We formulate deep structured models by combining CNNs and Conditional Random Fields (CRFs) for learning the patch-patch context between image regions. Specifically, we formulate CNN-based pairwise potential functions to capture semantic correlations between neighboring patches. Efficient piecewise training of the proposed deep structured model is then applied in order to avoid repeated expensive CRF inference during the course of back propagation.For capturing the patch-background context, we show that a network design with traditional multi-scale image inputs and sliding pyramid pooling is very effective for improving performance. We perform comprehensive evaluation of the proposed method. We achieve new state-of-the-art performance on a number of challenging semantic segmentation datasets.

  16. Context Tree Estimation in Variable Length Hidden Markov Models

    OpenAIRE

    Dumont, Thierry

    2011-01-01

    We address the issue of context tree estimation in variable length hidden Markov models. We propose an estimator of the context tree of the hidden Markov process which needs no prior upper bound on the depth of the context tree. We prove that the estimator is strongly consistent. This uses information-theoretic mixture inequalities in the spirit of Finesso and Lorenzo(Consistent estimation of the order for Markov and hidden Markov chains(1990)) and E.Gassiat and S.Boucheron (Optimal error exp...

  17. Context-induced relapse to alcohol seeking after punishment in a rat model.

    Science.gov (United States)

    Marchant, Nathan J; Khuc, Thi N; Pickens, Charles L; Bonci, Antonello; Shaham, Yavin

    2013-02-01

    Rat studies have demonstrated that exposure to environments associated with alcohol intake reinstates alcohol seeking after extinction of alcohol-reinforced responding in a different context. However, extinction is limited as an abstinence model, because humans typically abstain because of negative consequences associated with excessive drinking. It is currently unknown whether alcohol-associated contexts can provoke relapse to alcohol seeking after alcohol-taking behavior is suppressed by adverse consequences in a different context. Alcohol-preferring P rats were first given home-cage access to 20% ethanol. Next, they were trained to self-administer 20% ethanol in one context (context A). Subsequently, all rats continued to self-administer alcohol in a different context (context B). For one group, 50% of alcohol-reinforced responses were punished by mild footshock; two other groups either received noncontingent shocks or no shock. A fourth group was given extinction training in context B. All rats were then tested for relapse to alcohol seeking under extinction conditions in contexts A and B. In Context B, alcohol-taking behavior was suppressed by contingent shock (punishment) and extinction training but not by noncontingent shock. In Context A, relapse to alcohol seeking was reliably observed in the punished and extinction groups; a context switch had no effect on alcohol seeking in the no-shock or noncontingent shock groups. Our data indicate that punishment-induced suppression of alcohol-taking behavior is context-dependent. We propose that our procedure can be used to explore mechanisms of context-induced relapse to alcohol seeking after alcohol-taking behavior is suppressed by adverse consequences. Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  18. Bumble bee species' responses to a targeted conservation measure depend on landscape context and habitat quality.

    Science.gov (United States)

    Carvell, C; Osborne, J L; Bourke, A F G; Freeman, S N; Pywell, R F; Heard, M S

    2011-07-01

    The global decline of insect pollinators, especially bees, is cause for concern, and there is an urgent need for cost-effective conservation measures in agricultural landscapes. While landscape context and habitat quality are known to influence species richness and abundance of bees, there is a lack of evidence from manipulative field experiments on bees' responses to adaptive management across differently structured landscapes. We present the results of a large-scale study that investigated the effects of a targeted agri-environment scheme (AES) on bumble bees (Bombus spp.) over three years in the United Kingdom. Forage patches of different sizes were sown with a conservation flower mixture across eight sites covering a broad range of agricultural land use types. Species richness and worker densities (especially of the longer-tongued Bombus species for which the mixture was targeted) were significantly higher on sown forage patches than on existing non-crop control habitats throughout the three-year study, but the strength of this response depended on both the proportions of arable land and abundance of herbaceous forb species in the surrounding landscape. The size of sown patches also affected worker density, with smaller patches (0.25 ha) attracting higher densities of some species than larger patches (1.0 ha). Our models show that a targeted AES can deliver greater net benefits in more intensively farmed areas, in terms of the number and species richness of bumble bees supported, than in heterogeneous landscapes where other foraging habitats exist. These findings serve to strengthen the evidence base for extending agri-environment schemes to boost declining pollinator populations to a larger number of agricultural landscapes across the globe.

  19. The stress-reducing effect of music listening varies depending on the social context.

    Science.gov (United States)

    Linnemann, Alexandra; Strahler, Jana; Nater, Urs M

    2016-10-01

    Given that music listening often occurs in a social context, and given that social support can be associated with a stress-reducing effect, it was tested whether the mere presence of others while listening to music enhances the stress-reducing effect of listening to music. A total of 53 participants responded to questions on stress, presence of others, and music listening five times per day (30min after awakening, 1100h, 1400h, 1800h, 2100h) for seven consecutive days. After each assessment, participants were asked to collect a saliva sample for the later analysis of salivary cortisol (as a marker for the hypothalamic-pituitary-adrenal axis) and salivary alpha-amylase (as a marker for the autonomic nervous system). Hierarchical linear modeling revealed that music listening per se was not associated with a stress-reducing effect. However, listening to music in the presence of others led to decreased subjective stress levels, attenuated secretion of salivary cortisol, and higher activity of salivary alpha-amylase. When listening to music alone, music that was listened to for the reason of relaxation predicted lower subjective stress. The stress-reducing effect of music listening in daily life varies depending on the presence of others. Music listening in the presence of others enhanced the stress-reducing effect of music listening independently of reasons for music listening. Solitary music listening was stress-reducing when relaxation was stated as the reason for music listening. Thus, in daily life, music listening can be used for stress reduction purposes, with the greatest success when it occurs in the presence of others or when it is deliberately listened to for the reason of relaxation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (Carduelis chloris).

    Science.gov (United States)

    Herborn, Katherine; Alexander, Lucille; Arnold, Kathryn E

    2011-03-01

    Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once ("one-trial test") but switched to spatial cues when they had encountered that scenario on ten previous occasions ("repeated-trial test"). We suggest that repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts. © Springer-Verlag 2010

  1. Tourist Behavior Pattern Mining Model Based on Context

    Directory of Open Access Journals (Sweden)

    Dong-sheng Liu

    2013-01-01

    Full Text Available Personalized travel experience and service of tourist has been a hot topic research in the tourism service supply chain. In this paper, we take the context into consideration and propose an analyzed method to the tourist based on the context: firstly, we analyze the context which influences the tourist behavior patterns, select the main context factors, and construct the tourist behavior pattern model based on it; then, we calculate the interest degree of the tourist behavior pattern and mine out the rules with high interest degree with the association rule algorithm; we can make some recommendations to the tourist with better personalized travelling experience and services. At last, we make an experiment to show the feasibility and effectiveness of our method.

  2. Emotion recognition specialization and context-dependent risk of anxiety and depression in adolescents

    Science.gov (United States)

    Oldehinkel, Albertine J; Hartman, Catharina A; Van Oort, Floor V A; Nederhof, Esther

    2015-01-01

    Background Some adolescents function poorly in apparently benign environments, while others thrive despite hassles and difficulties. The aim of this study was to examine if adolescents with specialized skills in the recognition of either positive or negative emotions have a context-dependent risk of developing an anxiety or depressive disorder during adolescence, depending on exposure to positive or harsh parenting. Methods Data came from a large prospective Dutch population study (N = 1539). At age 11, perceived parental rejection and emotional warmth were measured by questionnaire, and emotion recognition skills by means of a reaction-time task. Lifetime diagnoses of anxiety and depressive disorders were assessed at about age 19, using a standardized diagnostic interview. Results Adolescents who were specialized in the recognition of positive emotions had a relatively high probability to develop an anxiety disorder when exposed to parental rejection (Bspecialization*rejection = 0.23, P anxiety or depressive disorder in adolescence, and that emotion recognition specialization may be a promising way to distinguish between various types of context-dependent reaction patterns. PMID:25642389

  3. Processing Incomplete Query Specifications in a Context-Dependent Reasoning Framework

    Directory of Open Access Journals (Sweden)

    Neli P. Zlatareva

    2013-04-01

    Full Text Available Search is the most prominent web service, which is about to change dramatically with the transition to the Semantic Web. Semantic Web applications are expected to deal with complex conjunctive queries, and not always such queries can be completely and precisely defined. Current Semantic Web reasoners built upon Description Logics have limited processing power in such environments. We discuss some of their limitations, and show how an alternative logical framework utilizing context-dependent rules can be extended to handle incomplete or imprecise query specifications.

  4. Modelling dependable systems using hybrid Bayesian networks

    International Nuclear Information System (INIS)

    Neil, Martin; Tailor, Manesh; Marquez, David; Fenton, Norman; Hearty, Peter

    2008-01-01

    A hybrid Bayesian network (BN) is one that incorporates both discrete and continuous nodes. In our extensive applications of BNs for system dependability assessment, the models are invariably hybrid and the need for efficient and accurate computation is paramount. We apply a new iterative algorithm that efficiently combines dynamic discretisation with robust propagation algorithms on junction tree structures to perform inference in hybrid BNs. We illustrate its use in the field of dependability with two example of reliability estimation. Firstly we estimate the reliability of a simple single system and next we implement a hierarchical Bayesian model. In the hierarchical model we compute the reliability of two unknown subsystems from data collected on historically similar subsystems and then input the result into a reliability block model to compute system level reliability. We conclude that dynamic discretisation can be used as an alternative to analytical or Monte Carlo methods with high precision and can be applied to a wide range of dependability problems

  5. Demographic responses to weather fluctuations are context dependent in a long-lived amphibian.

    Science.gov (United States)

    Cayuela, Hugo; Arsovski, Dragan; Thirion, Jean-Marc; Bonnaire, Eric; Pichenot, Julian; Boitaud, Sylvain; Miaud, Claude; Joly, Pierre; Besnard, Aurélien

    2016-08-01

    Weather fluctuations have been demonstrated to affect demographic traits in many species. In long-lived organisms, their impact on adult survival might be buffered by the evolution of traits that reduce variation in interannual adult survival. For example, skipping breeding is an effective behavioral mechanism that may limit yearly variation in adult survival when harsh weather conditions occur; however, this in turn would likely lead to strong variation in recruitment. Yet, only a few studies to date have examined the impact of weather variation on survival, recruitment and breeding probability simultaneously in different populations of the same species. To fill this gap, we studied the impact of spring temperatures and spring rainfall on survival, on reproductive skipping behavior and on recruitment in five populations of a long-lived amphibian, the yellow-bellied toad (Bombina variegata). Based on capture-recapture data, our findings demonstrate that survival depends on interactions between age, population and weather variation. Varying weather conditions in the spring result in strong variation in the survival of immature toads, whereas they have little effect on adult toads. Breeding probability depends on both the individual's previous reproductive status and on the weather conditions during the current breeding season, leading to high interannual variation in recruitment. Crucially, we found that the impact of weather variation on demographic traits is largely context dependent and may thus differ sharply between populations. Our results suggest that studies predicting the impact of climate change on population dynamics should be taken with caution when the relationship between climate and demographic traits is established using only one population or few populations. We therefore highly recommend further research that includes surveys replicated in a substantial number of populations to account for context-dependent variation in demographic processes.

  6. Context-dependent reproductive habitat selection: the interactive roles of structural complexity and cannibalistic conspecifics.

    Science.gov (United States)

    Sadeh, Asaf; Mangel, Marc; Blaustein, Leon

    2009-11-01

    Structural complexity generally reduces predation and cannibalism rates. Although the benefits from this effect vary among environmental contexts and through time, it has been the common explanation for high species abundance in complex habitats. We hypothesized that oviposition habitat selection for structural complexity depends on the expected trophic function of the progeny. In Salamandra infraimmaculata larvae, expected trophic function is dictated by their sequence of deposition. First cohorts cannibalize later-arriving cohorts, while all compete for shared prey resources. In a mesocosm experiment, we show that gravid salamanders facing conspecific-free pools preferred structurally simple habitats (no rocks), while females facing only pools with older conspecific larvae preferred complex habitats (with rocks). Context-dependent preference of habitat complexity for managing food/safety trade-offs may be extended from classic foraging patch decisions to breeding habitat selection. These trade-offs vary with dynamic larval processes such as priority effects and ontogenetic diet shifts, potentially leading to complex maternal parturition behaviours.

  7. World Model in the European Gothic Novel and Regional Context

    Directory of Open Access Journals (Sweden)

    Anna Zvolimbovskaya

    2016-08-01

    Full Text Available The article deals with a specificity of the world model in the European Gothic novel and its regional context. The model of the world and the concept of a person are considered as the basic criteria of modern humanitarian knowledge. The object of study is presented by the novels of Charlotte Bronte “Jane Eyre”, Abraham «Bram» Stoker “Dracula” and others.

  8. SME International Business Models: The Role of Context and Experience

    DEFF Research Database (Denmark)

    Child, John; Hsieh, Linda; Elbanna, Said

    2017-01-01

    This paper addresses two questions through a study of 180 SMEs located in contrasting industry and home country contexts. First, which business models for international markets prevail among SMEs and do they configure into different types? Second, which factors predict the international business...... models that SMEs follow? Three distinct international business models (traditional market-adaptive, technology exploiter, and ambidextrous explorer) are found among the SMEs studied. The likelihood of SMEs adopting one business model rather than another is to a high degree predictable with reference...... to a small set of factors: industry, level of home economy development, and decision-maker international experience....

  9. Topological and Orthomodular Modeling of Context in Behavioral Science

    Science.gov (United States)

    Narens, Louis

    2017-02-01

    Two non-boolean methods are discussed for modeling context in behavioral data and theory. The first is based on intuitionistic logic, which is similar to classical logic except that not every event has a complement. Its probability theory is also similar to classical probability theory except that the definition of probability function needs to be generalized to unions of events instead of applying only to unions of disjoint events. The generalization is needed, because intuitionistic event spaces may not contain enough disjoint events for the classical definition to be effective. The second method develops a version of quantum logic for its underlying probability theory. It differs from Hilbert space logic used in quantum mechanics as a foundation for quantum probability theory in variety of ways. John von Neumann and others have commented about the lack of a relative frequency approach and a rational foundation for this probability theory. This article argues that its version of quantum probability theory does not have such issues. The method based on intuitionistic logic is useful for modeling cognitive interpretations that vary with context, for example, the mood of the decision maker, the context produced by the influence of other items in a choice experiment, etc. The method based on this article's quantum logic is useful for modeling probabilities across contexts, for example, how probabilities of events from different experiments are related.

  10. Investigating the context-dependency of plant-soil-AMF-microbe interactions along a pollution gradient

    Science.gov (United States)

    Glassman, S. I.; Casper, B. B.

    2010-12-01

    Background/Question/Methods Investigating how arbuscular mycorrhizal fungi (AMF)-plant interactions vary with edaphic conditions provides an opportunity to test the context-dependency of interspecific interactions, which is currently recognized as a major avenue of future research. We study plant-mycorrhiza symbiotic relationships along a gradient of heavy metal contamination at a recently revegetated “Superfund” site on Blue Mountain, in Palmerton, Pennsylvania. We investigated the interactions involving the native mycorrhizal fungi, non-mycorrhizal soil microbes, soil, and two plant species (a C3 and C4 grass) along the contamination gradient. The native C3 study species Deschampsia flexuosa, is dominant along the gradient and established naturally; the C4 Sorghastrum nutans, is native to Pennsylvania but not to the site and was introduced during restoration. Because C4 grasses are obligate mycotrophs, we expected S. nutans to have a different effect on and response to the soil symbiont community than the C3 grass. We carried out a full factorial greenhouse experiment using field-collected seeds of D. flexuosa and S. nutans, soil, AMF spores, and non-mycorrhizal microbes from both high and low contaminated ends of the gradient. After 11 weeks of growth in the greenhouses, we harvested above and belowground plant biomass, and quantified AMF root colonization and AMF sporulation. Results/Conclusions Our results indicate that context-dependent function is an important factor driving specific ecological interactions between plants and soil microbes. We found that soil origin significantly affected plant growth. Plants from both species grew much larger in soil from low contaminated (LC) origin than high contaminated (HC) origin. Furthermore, we found that the efficacy of AMF in promoting plant growth depended on AMF origin. Specifically, AMF from LC improved growth of D. flexuosa best in either soil background and improved survivorship of S. nutans in HC soil

  11. Context Modeler for Wavelet Compression of Spectral Hyperspectral Images

    Science.gov (United States)

    Kiely, Aaron; Xie, Hua; Klimesh, matthew; Aranki, Nazeeh

    2010-01-01

    A context-modeling sub-algorithm has been developed as part of an algorithm that effects three-dimensional (3D) wavelet-based compression of hyperspectral image data. The context-modeling subalgorithm, hereafter denoted the context modeler, provides estimates of probability distributions of wavelet-transformed data being encoded. These estimates are utilized by an entropy coding subalgorithm that is another major component of the compression algorithm. The estimates make it possible to compress the image data more effectively than would otherwise be possible. The following background discussion is prerequisite to a meaningful summary of the context modeler. This discussion is presented relative to ICER-3D, which is the name attached to a particular compression algorithm and the software that implements it. The ICER-3D software is summarized briefly in the preceding article, ICER-3D Hyperspectral Image Compression Software (NPO-43238). Some aspects of this algorithm were previously described, in a slightly more general context than the ICER-3D software, in "Improving 3D Wavelet-Based Compression of Hyperspectral Images" (NPO-41381), NASA Tech Briefs, Vol. 33, No. 3 (March 2009), page 7a. In turn, ICER-3D is a product of generalization of ICER, another previously reported algorithm and computer program that can perform both lossless and lossy wavelet-based compression and decompression of gray-scale-image data. In ICER-3D, hyperspectral image data are decomposed using a 3D discrete wavelet transform (DWT). Following wavelet decomposition, mean values are subtracted from spatial planes of spatially low-pass subbands prior to encoding. The resulting data are converted to sign-magnitude form and compressed. In ICER-3D, compression is progressive, in that compressed information is ordered so that as more of the compressed data stream is received, successive reconstructions of the hyperspectral image data are of successively higher overall fidelity.

  12. Vasotocin Actions on Electric Behavior: Interspecific, Seasonal, and Social Context-Dependent Differences

    Science.gov (United States)

    Perrone, Rossana; Batista, Gervasio; Lorenzo, Daniel; Macadar, Omar; Silva, Ana

    2010-01-01

    Social behavior diversity is correlated with distinctively distributed patterns of a conserved brain network, which depend on the action of neuroendocrine messengers that integrate extrinsic and intrinsic cues. Arginine vasotocin (AVT) is a key integrator underlying differences in behavior across vertebrate taxa. Weakly electric fish use their electric organ discharges (EODs) as social behavioral displays. We examined the effect of AVT on EOD rate in two species of Gymnotiformes with different social strategies: Gymnotus omarorum, territorial and highly aggressive, and Brachyhypopomus gauderio, gregarious and aggressive only between breeding males. AVT induced a long-lasting and progressive increase of EOD rate in isolated B. gauderio, partially blocked by the V1a AVT receptor antagonist (Manning compound, MC), and had no effects in G. omarorum. AVT also induced a long-lasting increase in the firing rate (prevented by MC) of the isolated medullary pacemaker nucleus (PN) of B. gauderio when tested in an in vitro preparation, indicating that the PN is the direct effector of AVT actions. AVT is involved in the seasonal, social context-dependent nocturnal increase of EOD rate that has been recently described in B. gauderio to play a role in mate selection. AVT produced the additional nocturnal increase of EOD rate in non-breeding males, whereas MC blocked it in breeding males. Also, AVT induced a larger EOD rate increase in reproductive dyads than in agonistic encounters. We demonstrated interspecific, seasonal, and context-dependent actions of AVT on the PN that contribute to the understanding of the mechanisms the brain uses to shape sociality. PMID:20802858

  13. Vasotocin actions on electric behavior: interspecific, seasonal, and social context-dependent differences

    Directory of Open Access Journals (Sweden)

    Rossana Perrone

    2010-08-01

    Full Text Available Social behavior diversity is correlated with distinctively distributed patterns of a conserved brain network, which depend on the action of neuroendocrine messengers that integrate extrinsic and intrinsic cues. Arginine-vasotocin (AVT is a key integrator underlying differences in behavior across vertebrate taxa. Weakly electric fish use their electric organ discharges (EODs as social behavioral displays. We examined the effect of AVT on EOD rate in two species of Gymnotiformes with different social strategies: Gymnotus omarorum, territorial and highly aggressive, and Brachyhypopomus gauderio, gregarious and aggressive only between breeding males. AVT induced a long-lasting and progressive increase of EOD rate in isolated B. gauderio, partially blocked by the V1a AVT receptor antagonist (Manning compound, MC, and had no effects in G. omarorum. AVT also induced a long-lasting increase in the firing rate (prevented by MC of the isolated medullary pacemaker nucleus (PN of B. gauderio when tested in an in vitro preparation, indicating that the PN is the direct effector of AVT actions. AVT is involved in the seasonal, social context-dependent nocturnal increase of EOD rate that has been recently described in B. gauderio to play a role in mate selection. AVT produced the additional nocturnal increase of EOD rate in non-breeding males, whereas MC blocked it in breeding males. Also, AVT induced a larger EOD rate increase in reproductive dyads than in agonistic encounters. We demonstrated interspecific, seasonal, and context-dependent actions of AVT on the PN that contribute to the understanding of the mechanisms the brain uses to shape sociality.

  14. Modeling Users, Context and Devices for Ambient Assisted Living Environments

    Science.gov (United States)

    Castillejo, Eduardo; Almeida, Aitor; López-de-Ipiña, Diego; Chen, Liming

    2014-01-01

    The participation of users within AAL environments is increasing thanks to the capabilities of the current wearable devices. Furthermore, the significance of considering user's preferences, context conditions and device's capabilities help smart environments to personalize services and resources for them. Being aware of different characteristics of the entities participating in these situations is vital for reaching the main goals of the corresponding systems efficiently. To collect different information from these entities, it is necessary to design several formal models which help designers to organize and give some meaning to the gathered data. In this paper, we analyze several literature solutions for modeling users, context and devices considering different approaches in the Ambient Assisted Living domain. Besides, we remark different ongoing standardization works in this area. We also discuss the used techniques, modeled characteristics and the advantages and drawbacks of each approach to finally draw several conclusions about the reviewed works. PMID:24643006

  15. Model-based formalization of medical knowledge for context-aware assistance in laparoscopic surgery

    Science.gov (United States)

    Katić, Darko; Wekerle, Anna-Laura; Gärtner, Fabian; Kenngott, Hannes G.; Müller-Stich, Beat P.; Dillmann, Rüdiger; Speidel, Stefanie

    2014-03-01

    The increase of technological complexity in surgery has created a need for novel man-machine interaction techniques. Specifically, context-aware systems which automatically adapt themselves to the current circumstances in the OR have great potential in this regard. To create such systems, models of surgical procedures are vital, as they allow analyzing the current situation and assessing the context. For this purpose, we have developed a Surgical Process Model based on Description Logics. It incorporates general medical background knowledge as well as intraoperatively observed situational knowledge. The representation consists of three parts: the Background Knowledge Model, the Preoperative Process Model and the Integrated Intraoperative Process Model. All models depend on each other and create a concise view on the surgery. As a proof of concept, we applied the system to a specific intervention, the laparoscopic distal pancreatectomy.

  16. Context-specific graphical models for discret longitudinal data

    DEFF Research Database (Denmark)

    Edwards, David; Anantharama Ankinakatte, Smitha

    2015-01-01

    Ron et al. (1998) introduced a rich family of models for discrete longitudinal data called acyclic probabilistic finite automata. These may be represented as directed graphs that embody context-specific conditional independence relations. Here, the approach is developed from a statistical...... perspective. It is shown here that likelihood ratio tests may be constructed using standard contingency table methods, a model selection procedure that minimizes a penalized likelihood criterion is described, and a way to extend the models to incorporate covariates is proposed. The methods are applied...

  17. Context dependency and consumer acceptance of risk reducing strategies - a choice experiment study on salmonella risks in pork

    DEFF Research Database (Denmark)

    Mørkbak, Morten Raun; Christensen, Tove; Gyrd-Hansen, Dorte

    2012-01-01

    The paper investigates to what extent context dependency is present, when consumers are introduced to different risk reducing technologies and how this will affect their preferences for reductions in food risks. In particular, choice experiments are used to elicit consumer preferences for reducin...... findings of bad news having greater effect than good news – now applied to context dependency of preferences for food safety technologies.......The paper investigates to what extent context dependency is present, when consumers are introduced to different risk reducing technologies and how this will affect their preferences for reductions in food risks. In particular, choice experiments are used to elicit consumer preferences for reducing...... Salmonella risks in pork using farm level interventions vs. decontamination of meat at the abattoir. We found an interesting asymmetry in the context dependency. The presence of the least preferred risk reduction technology (lactic acid decontamination) affected the relative preferences for the two most...

  18. Value-based attentional capture influences context-dependent decision-making.

    Science.gov (United States)

    Itthipuripat, Sirawaj; Cha, Kexin; Rangsipat, Napat; Serences, John T

    2015-07-01

    Normative theories posit that value-based decision-making is context independent. However, decisions between two high-value options can be suboptimally biased by the introduction of a third low-value option. This context-dependent modulation is consistent with the divisive normalization of the value of each stimulus by the total value of all stimuli. In addition, an independent line of research demonstrates that pairing a stimulus with a high-value outcome can lead to attentional capture that can mediate the efficiency of visual information processing. Here we tested the hypothesis that value-based attentional capture interacts with value-based normalization to influence the optimality of decision-making. We used a binary-choice paradigm in which observers selected between two targets and the color of each target indicated the magnitude of their reward potential. Observers also had to simultaneously ignore a task-irrelevant distractor rendered in a color that was previously associated with a specific reward magnitude. When the color of the task-irrelevant distractor was previously associated with a high reward, observers responded more slowly and less optimally. Moreover, as the learned value of the distractor increased, electrophysiological data revealed an attenuation of the lateralized N1 and N2Pc responses evoked by the relevant choice stimuli and an attenuation of the late positive deflection (LPD). Collectively, these behavioral and electrophysiological data suggest that value-based attentional capture and value-based normalization jointly mediate the influence of context on free-choice decision-making. Copyright © 2015 the American Physiological Society.

  19. Context dependent off loading for cloudlet in mobile ad-hoc network

    Science.gov (United States)

    Bhatt, N.; Nadesh, R. K.; ArivuSelvan, K.

    2017-11-01

    Cloud Computing in Mobile Ad-hoc network is emerging part of research consideration as the demand and competency of mobile devices increased in last few years. To follow out operation within the remote cloud builds the postponement and influences the administration standard. To keep away from this trouble cloudlet is presented. Cloudlet gives identical support of the devices as cloud at low inactivity however at high transfer speed. Be that as it may, choice of a cloudlet for offloading calculation with flat energy is a noteworthy test if multiple cloud let is accessible adjacent. Here I proposed energy and bandwidth (Traffic overload for communication with cloud) aware cloudlet selection strategy based on the context dependency of the device location. It works on the basis of mobile device location and bandwidth availability of cloudlet. The cloudlet offloading and selection process using given solution is simulated in Cloud ~ Simulator.

  20. Three experimental approaches to measure the social context dependence of prejudice communication and discriminatory behavior.

    Science.gov (United States)

    Beyer, Heiko; Liebe, Ulf

    2015-01-01

    Empirical research on discrimination is faced with crucial problems stemming from the specific character of its object of study. In democratic societies the communication of prejudices and other forms of discriminatory behavior is considered socially undesirable and depends on situational factors such as whether a situation is considered private or whether a discriminatory consensus can be assumed. Regular surveys thus can only offer a blurred picture of the phenomenon. But also survey experiments intended to decrease the social desirability bias (SDB) so far failed in systematically implementing situational variables. This paper introduces three experimental approaches to improve the study of discrimination and other topics of social (un-)desirability. First, we argue in favor of cognitive context framing in surveys in order to operationalize the salience of situational norms. Second, factorial surveys offer a way to take situational contexts and substitute behavior into account. And third, choice experiments - a rather new method in sociology - offer a more valid method of measuring behavioral characteristics compared to simple items in surveys. All three approaches - which may be combined - are easy to implement in large-scale surveys. Results of empirical studies demonstrate the fruitfulness of each of these approaches. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. The relative importance of rapid evolution for plant-microbe interactions depends on ecological context.

    Science.gov (United States)

    Terhorst, Casey P; Lennon, Jay T; Lau, Jennifer A

    2014-06-22

    Evolution can occur on ecological time-scales, affecting community and ecosystem processes. However, the importance of evolutionary change relative to ecological processes remains largely unknown. Here, we analyse data from a long-term experiment in which we allowed plant populations to evolve for three generations in dry or wet soils and used a reciprocal transplant to compare the ecological effect of drought and the effect of plant evolutionary responses to drought on soil microbial communities and nutrient availability. Plants that evolved under drought tended to support higher bacterial and fungal richness, and increased fungal : bacterial ratios in the soil. Overall, the magnitudes of ecological and evolutionary effects on microbial communities were similar; however, the strength and direction of these effects depended on the context in which they were measured. For example, plants that evolved in dry environments increased bacterial abundance in dry contemporary environments, but decreased bacterial abundance in wet contemporary environments. Our results suggest that interactions between recent evolutionary history and ecological context affect both the direction and magnitude of plant effects on soil microbes. Consequently, an eco-evolutionary perspective is required to fully understand plant-microbe interactions.

  2. Integrating models that depend on variable data

    Science.gov (United States)

    Banks, A. T.; Hill, M. C.

    2016-12-01

    Models of human-Earth systems are often developed with the goal of predicting the behavior of one or more dependent variables from multiple independent variables, processes, and parameters. Often dependent variable values range over many orders of magnitude, which complicates evaluation of the fit of the dependent variable values to observations. Many metrics and optimization methods have been proposed to address dependent variable variability, with little consensus being achieved. In this work, we evaluate two such methods: log transformation (based on the dependent variable being log-normally distributed with a constant variance) and error-based weighting (based on a multi-normal distribution with variances that tend to increase as the dependent variable value increases). Error-based weighting has the advantage of encouraging model users to carefully consider data errors, such as measurement and epistemic errors, while log-transformations can be a black box for typical users. Placing the log-transformation into the statistical perspective of error-based weighting has not formerly been considered, to the best of our knowledge. To make the evaluation as clear and reproducible as possible, we use multiple linear regression (MLR). Simulations are conducted with MatLab. The example represents stream transport of nitrogen with up to eight independent variables. The single dependent variable in our example has values that range over 4 orders of magnitude. Results are applicable to any problem for which individual or multiple data types produce a large range of dependent variable values. For this problem, the log transformation produced good model fit, while some formulations of error-based weighting worked poorly. Results support previous suggestions fthat error-based weighting derived from a constant coefficient of variation overemphasizes low values and degrades model fit to high values. Applying larger weights to the high values is inconsistent with the log

  3. Pipeline Processing with an Iterative, Context-Based Detection Model

    Science.gov (United States)

    2016-01-22

    unlimited. 59 optimum choice for steering vectors is the adaptive beamformer weighting [ Capon et al ., 1967] also known as the minimum variance...AFRL-RV-PS- AFRL-RV-PS- TR-2016-0080 TR-2016-0080 PIPELINE PROCESSING WITH AN ITERATIVE, CONTEXT-BASED DETECTION MODEL T. Kværna, et al ...conditions, the capability to detect events down to magnitude 2.0 [Gibbons et al ., 2011]. Figure 3. Location of the SPITS array in relation to Novaya

  4. A Context-Dependent View on the Linguistic Interdependence Hypothesis: Language Use and SES as Potential Moderators

    Science.gov (United States)

    Prevoo, Mariëlle J. L.; Malda, Maike; Emmen, Rosanneke A. G.; Yeniad, Nihal; Mesman, Judi

    2015-01-01

    The linguistic interdependence hypothesis states that the development of skills in a second language (L2) partly depends on the skill level in the first language (L1). It has been suggested that the theory lacked attention for differential interdependence. In this study we test what we call the hypothesis of context-dependent linguistic…

  5. Modeling Concept Dependencies for Event Detection

    Science.gov (United States)

    2014-04-04

    Modeling Concept Dependencies for Event Detection Ethem F. Can Center for Intelligent Information Retrieval (CIIR) School of Computer Science UMass...Amherst, MA, 01002 efcan@cs.umass.edu R. Manmatha Center for Intelligent Information Retrieval (CIIR) School of Computer Science UMass Amherst, MA...necessarily involve any actions while other events such as “ Parkour ” may involve multiple atomic ac- tions. Further, videos may vary widely in length and

  6. A Dynamic Approach to Modeling Dependence Between Human Failure Events

    Energy Technology Data Exchange (ETDEWEB)

    Boring, Ronald Laurids [Idaho National Laboratory

    2015-09-01

    In practice, most HRA methods use direct dependence from THERP—the notion that error be- gets error, and one human failure event (HFE) may increase the likelihood of subsequent HFEs. In this paper, we approach dependence from a simulation perspective in which the effects of human errors are dynamically modeled. There are three key concepts that play into this modeling: (1) Errors are driven by performance shaping factors (PSFs). In this context, the error propagation is not a result of the presence of an HFE yielding overall increases in subsequent HFEs. Rather, it is shared PSFs that cause dependence. (2) PSFs have qualities of lag and latency. These two qualities are not currently considered in HRA methods that use PSFs. Yet, to model the effects of PSFs, it is not simply a matter of identifying the discrete effects of a particular PSF on performance. The effects of PSFs must be considered temporally, as the PSFs will have a range of effects across the event sequence. (3) Finally, there is the concept of error spilling. When PSFs are activated, they not only have temporal effects but also lateral effects on other PSFs, leading to emergent errors. This paper presents the framework for tying together these dynamic dependence concepts.

  7. Seed harvesting by a generalist consumer is context-dependent: Interactive effects across multiple spatial scales

    Science.gov (United States)

    Ostoja, Steven M.; Schupp, Eugene W.; Klinger, Rob

    2013-01-01

    Granivore foraging decisions affect consumer success and determine the quantity and spatial pattern of seed survival. These decisions are influenced by environmental variation at spatial scales ranging from landscapes to local foraging patches. In a field experiment, the effects of seed patch variation across three spatial scales on seed removal by western harvester ants Pogonomyrmex occidentalis were evaluated. At the largest scale we assessed harvesting in different plant communities, at the intermediate scale we assessed harvesting at different distances from ant mounds, and at the smallest scale we assessed the effects of interactions among seed species in local seed neighborhoods on seed harvesting (i.e. resource–consumer interface). Selected seed species were presented alone (monospecific treatment) and in mixture with Bromus tectorum (cheatgrass; mixture treatment) at four distances from P. occidentalis mounds in adjacent intact sagebrush and non-native cheatgrass-dominated communities in the Great Basin, Utah, USA. Seed species differed in harvest, with B. tectorum being least preferred. Large and intermediate scale variation influenced harvest. More seeds were harvested in sagebrush than in cheatgrass-dominated communities (largest scale), and the quantity of seed harvested varied with distance from mounds (intermediate-scale), although the form of the distance effect differed between plant communities. At the smallest scale, seed neighborhood affected harvest, but the patterns differed among seed species considered. Ants harvested fewer seeds from mixed-seed neighborhoods than from monospecific neighborhoods, suggesting context dependence and potential associational resistance. Further, the effects of plant community and distance from mound on seed harvest in mixtures differed from their effects in monospecific treatments. Beyond the local seed neighborhood, selection of seed resources is better understood by simultaneously evaluating removal at

  8. Dental hygienists' perceptions of professionalism are multidimensional and context-dependent: a qualitative study in Japan.

    Science.gov (United States)

    Nagatani, Yukiko; Imafuku, Rintaro; Takemoto, Toshinobu; Waki, Tadayuki; Obayashi, Taiji; Ogawa, Tetsuji

    2017-12-29

    Due to the declining birth rate and aging of Japanese society, the roles and responsibilities of dental hygienists are continuously expanding. Medical professionalism needs to be pursued continuously throughout one's career in order to improve dental care and treatment. Although conceptualising professionalism is essential to the education of health professionals, professionalism in the field of dental hygiene has not been defined or adequately examined in Japan. The purposes of this study are to investigate dental hygienists' perceptions of the constituent elements of professionalism and the factors affecting their perceptions. Semi-structured interviews were conducted with 18 dental hygienists in Japan. Drawing on the conceptualisation of professionalism in medicine described by Van de Camp et al., the transcribed data were thematically analysed. The dental hygienists in this study perceived 70 constituent elements that were categorised into eight core competencies related to professionalism. These competencies were further classified into three main themes: intrapersonal, interpersonal, and public professionalism. There were three sociohistorical factors that affected their perceptions of the constituent elements, namely academic background (university or technical school), the contexts of any previously provided dental care (university hospital or dental clinic), and their social interactions with their colleagues during their engagement in dental practice (dental team or interprofessional team). Moreover, according to their sociohistorical backgrounds, the dental hygienists saw themselves variously as scholars (university graduates), facilitators (university hospital), skillful artisans (dental clinic), or collaborators (interprofessional team). Dental hygienists' perceptions of professionalism are multidimensional and context-dependent, so culture- and professional-specific elements need to be included in educational curricula and continuing professional

  9. Colour dependence of zodiacal light models

    Science.gov (United States)

    Giese, R. H.; Hanner, M. S.; Leinert, C.

    1973-01-01

    Colour models of the zodiacal light in the ecliptic have been calculated for both dielectric and metallic particles in the sub-micron and micron size range. Two colour ratios were computed, a blue ratio and a red ratio. The models with a size distribution proportional to s to the -2.5 power ds (where s is the particle radius) generally show a colour close to the solar colour and almost independent of elongation. Especially in the blue colour ratio there is generally no significant dependence on the lower cutoff size (0.1-1 micron). The main feature of absorbing particles is a reddening at small elongations. The models for size distributions proportional to s to the -4 power ds show larger departures from solar colour and more variation with model parameters. Colour measurements, including red and near infra-red, therefore are useful to distinguish between flat and steep size spectra and to verify the presence of slightly absorbing particles.

  10. Dependability modeling and assessment in UML-based software development.

    Science.gov (United States)

    Bernardi, Simona; Merseguer, José; Petriu, Dorina C

    2012-01-01

    Assessment of software nonfunctional properties (NFP) is an important problem in software development. In the context of model-driven development, an emerging approach for the analysis of different NFPs consists of the following steps: (a) to extend the software models with annotations describing the NFP of interest; (b) to transform automatically the annotated software model to the formalism chosen for NFP analysis; (c) to analyze the formal model using existing solvers; (d) to assess the software based on the results and give feedback to designers. Such a modeling→analysis→assessment approach can be applied to any software modeling language, be it general purpose or domain specific. In this paper, we focus on UML-based development and on the dependability NFP, which encompasses reliability, availability, safety, integrity, and maintainability. The paper presents the profile used to extend UML with dependability information, the model transformation to generate a DSPN formal model, and the assessment of the system properties based on the DSPN results.

  11. Context-dependent risks and benefits of transfusion in the critically ill

    Directory of Open Access Journals (Sweden)

    Harahsheh Y

    2017-03-01

    Full Text Available Yusrah Harahsheh,1,2 Kwok M Ho1,3,4 1Department of Intensive Care Medicine, Royal Perth Hospital, 2School of Medicine & Pharmacology, 3School of Population Health, University of Western Australia, 4School of Veterinary & Life Sciences, Murdoch University, Perth, WA, Australia Abstract: Transfusion of red blood cells (RBCs and other blood products to critically ill patients is common. Blood products are expensive, and not without risks. Recent evidence from high-quality multicenter randomized controlled trials confirmed the safety of allogeneic RBC transfusions, including the use of aged RBCs, and mild to moderate anemia for most stable and nonbleeding critically ill patients. Emerging evidence suggests that a liberal RBC transfusion target may have potential divergent effects on patient outcomes depending on their clinical context, with possible harms for patients with gastrointestinal bleeding due to portal hypertension and, conversely, benefits for patients with severe underlying cardiovascular diseases. Despite an apparent increased risk of bleeding in critically ill patients with deranged coagulation parameters and thrombocytopenia, recent studies suggested that fresh frozen plasma (FFP and platelet transfusions may not be beneficial and, indeed, also not very effective in correcting these abnormalities. As for patients who have active severe critical bleeding, use of empirical 1:1:1 RBC: platelets: FFP transfusion appears justifiable in an attempt to reduce deaths as a result of exsanguination. In conjunction with platelet count and fibrinogen concentration, whole blood viscoelastic and platelet function tests are particularly useful to assist clinicians to rationalize FFP and platelet transfusions, when imminent death from exsanguination is not anticipated. Because the risks and benefits of blood product transfusion are heavily context-dependent, a thorough consideration of the characteristics and clinical status of the patients, in

  12. Modeling sequential context effects in diagnostic interpretation of screening mammograms.

    Science.gov (United States)

    Alamudun, Folami; Paulus, Paige; Yoon, Hong-Jun; Tourassi, Georgia

    2018-07-01

    Prior research has shown that physicians' medical decisions can be influenced by sequential context, particularly in cases where successive stimuli exhibit similar characteristics when analyzing medical images. This type of systematic error is known to psychophysicists as sequential context effect as it indicates that judgments are influenced by features of and decisions about the preceding case in the sequence of examined cases, rather than being based solely on the peculiarities unique to the present case. We determine if radiologists experience some form of context bias, using screening mammography as the use case. To this end, we explore correlations between previous perceptual behavior and diagnostic decisions and current decisions. We hypothesize that a radiologist's visual search pattern and diagnostic decisions in previous cases are predictive of the radiologist's current diagnostic decisions. To test our hypothesis, we tasked 10 radiologists of varied experience to conduct blind reviews of 100 four-view screening mammograms. Eye-tracking data and diagnostic decisions were collected from each radiologist under conditions mimicking clinical practice. Perceptual behavior was quantified using the fractal dimension of gaze scanpath, which was computed using the Minkowski-Bouligand box-counting method. To test the effect of previous behavior and decisions, we conducted a multifactor fixed-effects ANOVA. Further, to examine the predictive value of previous perceptual behavior and decisions, we trained and evaluated a predictive model for radiologists' current diagnostic decisions. ANOVA tests showed that previous visual behavior, characterized by fractal analysis, previous diagnostic decisions, and image characteristics of previous cases are significant predictors of current diagnostic decisions. Additionally, predictive modeling of diagnostic decisions showed an overall improvement in prediction error when the model is trained on additional information about

  13. Motivational Spiral Models (MSM): common and distinct motivations in context

    OpenAIRE

    Fisher, Laurel J

    2013-01-01

    Motivational Spiral Models (MSM) show links over time among self concepts, feelings, strategies, skills and participation in everyday activities. In theory, MSM have many common features, with distinct features in particular contexts. This project examined children?s motivation to participate in literacy (MSM-L), social (MSM-S) and physical activities (MSM-P). The participants in Study 1 (N?=?32) were 9 to 11 years old, and in Study 2 (N?=?73) were 4 to 12 year old children. Locations were cl...

  14. Theoretical Model of Engagement in the Context of Brand Communities

    Directory of Open Access Journals (Sweden)

    Flávia D\\u2019albergaria Freitas

    2017-01-01

    Full Text Available This essay proposes to refine the concept of consumer engagement in the context of brand communities. A comprehensive review of studies addressing the phenomenon of brand community was made. This paper follows the tradition of Marketing Research and Consumer Behavior, more specifically the perspective of cognitive psychology. The main theoretical foundation of the study is the Social Identity Theory (SIT, also incorporating relevant contributions from the perspective of Consumer Culture Theory (CCT. Therefore, this study contributes to the progress of research on the phenomenon of engagement in brand communities, proposing a theoretical model that relates engagement with its antecedents factors and reflective dimensions.

  15. The effect of consumers and mutualists of Vaccinium membranaceum at Mount St. Helens: dependence on successional context.

    Directory of Open Access Journals (Sweden)

    Suann Yang

    Full Text Available In contrast to secondary succession, studies of terrestrial primary succession largely ignore the role of biotic interactions, other than plant facilitation and competition, despite the expectation that simplified interaction webs and propagule-dependent demographics may amplify the effects of consumers and mutualists. We investigated whether successional context determined the impact of consumers and mutualists by quantifying their effects on reproduction by the shrub Vaccinium membranaceum in primary and secondary successional sites at Mount St. Helens (Washington, USA, and used simulations to explore the effects of these interactions on colonization. Species interactions differed substantially between sites, and the combined effect of consumers and mutualists was much more strongly negative for primary successional plants. Because greater local control of propagule pressure is expected to increase successional rates, we evaluated the role of dispersal in the context of these interactions. Our simulations showed that even a small local seed source greatly increases population growth rates, thereby balancing strong consumer pressure. The prevalence of strong negative interactions in the primary successional site is a reminder that successional communities will not exhibit the distribution of interaction strengths characteristic of stable communities, and suggests the potential utility of modeling succession as the consequence of interaction strengths.

  16. Modeling pairwise dependencies in precipitation intensities

    Directory of Open Access Journals (Sweden)

    M. Vrac

    2007-12-01

    Full Text Available In statistics, extreme events are classically defined as maxima over a block length (e.g. annual maxima of daily precipitation or as exceedances above a given large threshold. These definitions allow the hydrologist and the flood planner to apply the univariate Extreme Value Theory (EVT to their time series of interest. But these strategies have two main drawbacks. Firstly, working with maxima or exceedances implies that a lot of observations (those below the chosen threshold or the maximum are completely disregarded. Secondly, this univariate modeling does not take into account the spatial dependence. Nearby weather stations are considered independent, although their recordings can show otherwise.

    To start addressing these two issues, we propose a new statistical bivariate model that takes advantages of the recent advances in multivariate EVT. Our model can be viewed as an extension of the non-homogeneous univariate mixture. The two strong points of this latter model are its capacity at modeling the entire range of precipitation (and not only the largest values and the absence of an arbitrarily fixed large threshold to define exceedances. Here, we adapt this mixture and broaden it to the joint modeling of bivariate precipitation recordings. The performance and flexibility of this new model are illustrated on simulated and real precipitation data.

  17. Context-Dependent Functional Divergence of the Notch Ligands DLL1 and DLL4 In Vivo.

    Directory of Open Access Journals (Sweden)

    Kristina Preuße

    2015-06-01

    Full Text Available Notch signalling is a fundamental pathway that shapes the developing embryo and sustains adult tissues by direct communication between ligand and receptor molecules on adjacent cells. Among the ligands are two Delta paralogues, DLL1 and DLL4, that are conserved in mammals and share a similar structure and sequence. They activate the Notch receptor partly in overlapping expression domains where they fulfil redundant functions in some processes (e.g. maintenance of the crypt cell progenitor pool. In other processes, however, they appear to act differently (e.g. maintenance of foetal arterial identity raising the questions of how similar DLL1 and DLL4 really are and which mechanism causes the apparent context-dependent divergence. By analysing mice that conditionally overexpress DLL1 or DLL4 from the same genomic locus (Hprt and mice that express DLL4 instead of DLL1 from the endogenous Dll1 locus (Dll1Dll4ki, we found functional differences that are tissue-specific: while DLL1 and DLL4 act redundantly during the maintenance of retinal progenitors, their function varies in the presomitic mesoderm (PSM where somites form in a Notch-dependent process. In the anterior PSM, every cell expresses both Notch receptors and ligands, and DLL1 is the only activator of Notch while DLL4 is not endogenously expressed. Transgenic DLL4 cannot replace DLL1 during somitogenesis and in heterozygous Dll1Dll4ki/+ mice, the Dll1Dll4ki allele causes a dominant segmentation phenotype. Testing several aspects of the complex Notch signalling system in vitro, we found that both ligands have a similar trans-activation potential but that only DLL4 is an efficient cis-inhibitor of Notch signalling, causing a reduced net activation of Notch. These differential cis-inhibitory properties are likely to contribute to the functional divergence of DLL1 and DLL4.

  18. Context-Dependent Functional Divergence of the Notch Ligands DLL1 and DLL4 In Vivo.

    Science.gov (United States)

    Preuße, Kristina; Tveriakhina, Lena; Schuster-Gossler, Karin; Gaspar, Cláudia; Rosa, Alexandra Isabel; Henrique, Domingos; Gossler, Achim; Stauber, Michael

    2015-06-01

    Notch signalling is a fundamental pathway that shapes the developing embryo and sustains adult tissues by direct communication between ligand and receptor molecules on adjacent cells. Among the ligands are two Delta paralogues, DLL1 and DLL4, that are conserved in mammals and share a similar structure and sequence. They activate the Notch receptor partly in overlapping expression domains where they fulfil redundant functions in some processes (e.g. maintenance of the crypt cell progenitor pool). In other processes, however, they appear to act differently (e.g. maintenance of foetal arterial identity) raising the questions of how similar DLL1 and DLL4 really are and which mechanism causes the apparent context-dependent divergence. By analysing mice that conditionally overexpress DLL1 or DLL4 from the same genomic locus (Hprt) and mice that express DLL4 instead of DLL1 from the endogenous Dll1 locus (Dll1Dll4ki), we found functional differences that are tissue-specific: while DLL1 and DLL4 act redundantly during the maintenance of retinal progenitors, their function varies in the presomitic mesoderm (PSM) where somites form in a Notch-dependent process. In the anterior PSM, every cell expresses both Notch receptors and ligands, and DLL1 is the only activator of Notch while DLL4 is not endogenously expressed. Transgenic DLL4 cannot replace DLL1 during somitogenesis and in heterozygous Dll1Dll4ki/+ mice, the Dll1Dll4ki allele causes a dominant segmentation phenotype. Testing several aspects of the complex Notch signalling system in vitro, we found that both ligands have a similar trans-activation potential but that only DLL4 is an efficient cis-inhibitor of Notch signalling, causing a reduced net activation of Notch. These differential cis-inhibitory properties are likely to contribute to the functional divergence of DLL1 and DLL4.

  19. Context-dependent interactions and the regulation of species richness in freshwater fish

    Science.gov (United States)

    MacDougall, Andrew S.; Harvey, Eric; McCune, Jenny L.; Nilsson, Karin A.; Bennett, Joseph; Firn, Jennifer; Bartley, Timothy; Grace, James B.; Kelly, Jocelyn; Tunney, Tyler D.; McMeans, Bailey; Matsuzaki, Shin-Ichiro S.; Kadoya, Taku; Esch, Ellen; Cazelles, Kevin; Lester, Nigel; McCann, Kevin S.

    2018-01-01

    Species richness is regulated by a complex network of scale-dependent processes. This complexity can obscure the influence of limiting species interactions, making it difficult to determine if abiotic or biotic drivers are more predominant regulators of richness. Using integrative modeling of freshwater fish richness from 721 lakes along an 11olatitudinal gradient, we find negative interactions to be a relatively minor independent predictor of species richness in lakes despite the widespread presence of predators. Instead, interaction effects, when detectable among major functional groups and 231 species pairs, were strong, often positive, but contextually dependent on environment. These results are consistent with the idea that negative interactions internally structure lake communities but do not consistently ‘scale-up’ to regulate richness independently of the environment. The importance of environment for interaction outcomes and its role in the regulation of species richness highlights the potential sensitivity of fish communities to the environmental changes affecting lakes globally.

  20. Context-dependent JPEG backward-compatible high-dynamic range image compression

    Science.gov (United States)

    Korshunov, Pavel; Ebrahimi, Touradj

    2013-10-01

    High-dynamic range (HDR) imaging is expected, together with ultrahigh definition and high-frame rate video, to become a technology that may change photo, TV, and film industries. Many cameras and displays capable of capturing and rendering both HDR images and video are already available in the market. The popularity and full-public adoption of HDR content is, however, hindered by the lack of standards in evaluation of quality, file formats, and compression, as well as large legacy base of low-dynamic range (LDR) displays that are unable to render HDR. To facilitate the wide spread of HDR usage, the backward compatibility of HDR with commonly used legacy technologies for storage, rendering, and compression of video and images are necessary. Although many tone-mapping algorithms are developed for generating viewable LDR content from HDR, there is no consensus of which algorithm to use and under which conditions. We, via a series of subjective evaluations, demonstrate the dependency of the perceptual quality of the tone-mapped LDR images on the context: environmental factors, display parameters, and image content itself. Based on the results of subjective tests, it proposes to extend JPEG file format, the most popular image format, in a backward compatible manner to deal with HDR images also. An architecture to achieve such backward compatibility with JPEG is proposed. A simple implementation of lossy compression demonstrates the efficiency of the proposed architecture compared with the state-of-the-art HDR image compression.

  1. High-throughput assessment of context-dependent effects of chromatin proteins.

    Science.gov (United States)

    Brueckner, Laura; van Arensbergen, Joris; Akhtar, Waseem; Pagie, Ludo; van Steensel, Bas

    2016-01-01

    Chromatin proteins control gene activity in a concerted manner. We developed a high-throughput assay to study the effects of the local chromatin environment on the regulatory activity of a protein of interest. The assay combines a previously reported multiplexing strategy based on barcoded randomly integrated reporters with Gal4-mediated tethering. We applied the assay to Drosophila heterochromatin protein 1a (HP1a), which is mostly known as a repressive protein but has also been linked to transcriptional activation. Recruitment to over 1000 genomic locations revealed that HP1a is a potent repressor able to silence even highly expressing reporter genes. However, the local chromatin context can modulate HP1a function. In pericentromeric regions, HP1a-induced repression was enhanced by twofold. In regions marked by a H3K36me3-rich chromatin signature, HP1a-dependent silencing was significantly decreased. We found no evidence for an activating function of HP1a in our experimental system. Furthermore, we did not observe stable transmission of repression over mitotic divisions after loss of targeted HP1a. The multiplexed tethered reporter assay should be applicable to a large number of chromatin proteins and will be a useful tool to dissect combinatorial regulatory interactions in chromatin.

  2. Context-dependent effects of noise on echolocation pulse characteristics in free-tailed bats.

    Science.gov (United States)

    Tressler, Jedediah; Smotherman, Michael S

    2009-10-01

    Background noise evokes a similar suite of adaptations in the acoustic structure of communication calls across a diverse range of vertebrates. Echolocating bats may have evolved specialized vocal strategies for echolocating in noise, but also seem to exhibit generic vertebrate responses such as the ubiquitous Lombard response. We wondered how bats balance generic and echolocation-specific vocal responses to noise. To address this question, we first characterized the vocal responses of flying free-tailed bats (Tadarida brasiliensis) to broadband noises varying in amplitude. Secondly, we measured the bats' responses to band-limited noises that varied in the extent of overlap with their echolocation pulse bandwidth. We hypothesized that the bats' generic responses to noise would be graded proportionally with noise amplitude, total bandwidth and frequency content, and consequently that more selective responses to band-limited noise such as the jamming avoidance response could be explained by a linear decomposition of the response to broadband noise. Instead, the results showed that both the nature and the magnitude of the vocal responses varied with the acoustic structure of the outgoing pulse as well as non-linearly with noise parameters. We conclude that free-tailed bats utilize separate generic and specialized vocal responses to noise in a context-dependent fashion.

  3. Context-dependent effects of noise on echolocation pulse characteristics in free-tailed bats

    Science.gov (United States)

    Smotherman, Michael S.

    2010-01-01

    Background noise evokes a similar suite of adaptations in the acoustic structure of communication calls across a diverse range of vertebrates. Echolocating bats may have evolved specialized vocal strategies for echolocating in noise, but also seem to exhibit generic vertebrate responses such as the ubiquitous Lombard response. We wondered how bats balance generic and echolocation-specific vocal responses to noise. To address this question, we first characterized the vocal responses of flying free-tailed bats (Tadarida brasiliensis) to broadband noises varying in amplitude. Secondly, we measured the bats’ responses to band-limited noises that varied in the extent of overlap with their echolocation pulse bandwidth. We hypothesized that the bats’ generic responses to noise would be graded proportionally with noise amplitude, total bandwidth and frequency content, and consequently that more selective responses to band-limited noise such as the jamming avoidance response could be explained by a linear decomposition of the response to broadband noise. Instead, the results showed that both the nature and the magnitude of the vocal responses varied with the acoustic structure of the outgoing pulse as well as non-linearly with noise parameters. We conclude that free-tailed bats utilize separate generic and specialized vocal responses to noise in a context-dependent fashion. PMID:19672604

  4. Single genome retrieval of context-dependent variability in mutation rates for human germline.

    Science.gov (United States)

    Sahakyan, Aleksandr B; Balasubramanian, Shankar

    2017-01-13

    Accurate knowledge of the core components of substitution rates is of vital importance to understand genome evolution and dynamics. By performing a single-genome and direct analysis of 39,894 retrotransposon remnants, we reveal sequence context-dependent germline nucleotide substitution rates for the human genome. The rates are characterised through rate constants in a time-domain, and are made available through a dedicated program (Trek) and a stand-alone database. Due to the nature of the method design and the imposed stringency criteria, we expect our rate constants to be good estimates for the rates of spontaneous mutations. Benefiting from such data, we study the short-range nucleotide (up to 7-mer) organisation and the germline basal substitution propensity (BSP) profile of the human genome; characterise novel, CpG-independent, substitution prone and resistant motifs; confirm a decreased tendency of moieties with low BSP to undergo somatic mutations in a number of cancer types; and, produce a Trek-based estimate of the overall mutation rate in human. The extended set of rate constants we report may enrich our resources and help advance our understanding of genome dynamics and evolution, with possible implications for the role of spontaneous mutations in the emergence of pathological genotypes and neutral evolution of proteomes.

  5. Stress during Adolescence Alters Palatable Food Consumption in a Context-Dependent Manner.

    Directory of Open Access Journals (Sweden)

    Christine Handy

    Full Text Available Food consumption and preferences may be shaped by exposure to stressful environments during sensitive periods in development, and even small changes in consumption can have important effects on long term health. Adolescence is increasingly recognized as a sensitive period, in which adverse experiences can alter development, but the specific programming effects that may occur during adolescence remain incompletely understood. The current study seeks to explore the effects of stress during late adolescence on consumption of a palatable, high-fat, high-sugar food in adulthood-under basal conditions, as well following acute stress. Male Long-Evans rats were exposed to a regimen of variable stress for seven days in late adolescence (PND 45-51. During the stress regimen, stressed animals gained significantly less weight than control animals, but weight in adulthood was unaffected by adolescent stress. Palatable food consumption differed between experimental groups, and the direction of effect depended on context; stressed rats ate significantly more palatable food than controls upon first exposure, but ate less following an acute stressor. Leptin levels and exploratory behaviors did not differ between stressed and non-stressed groups, suggesting that other factors regulate preference for a palatable food. Altered food consumption following adolescent stress suggests that rats remain sensitive to stress during late adolescence, and that adult feeding behavior may be affected by previous adverse experiences. Such programming effects highlight adolescence as a period of plasticity, with the potential to shape long term food consumption patterns and preferences.

  6. Context dependence of students' views about the role of equations in understanding biology.

    Science.gov (United States)

    Watkins, Jessica; Elby, Andrew

    2013-06-01

    Students' epistemological views about biology--their ideas about what "counts" as learning and understanding biology--play a role in how they approach their courses and respond to reforms. As introductory biology courses incorporate more physics and quantitative reasoning, student attitudes about the role of equations in biology become especially relevant. However, as documented in research in physics education, students' epistemologies are not always stable and fixed entities; they can be dynamic and context-dependent. In this paper, we examine an interview with an introductory student in which she discusses the use of equations in her reformed biology course. In one part of the interview, she expresses what sounds like an entrenched negative stance toward the role equations can play in understanding biology. However, later in the interview, when discussing a different biology topic, she takes a more positive stance toward the value of equations. These results highlight how a given student can have diverse ways of thinking about the value of bringing physics and math into biology. By highlighting how attitudes can shift in response to different tasks, instructional environments, and contextual cues, we emphasize the need to attend to these factors, rather than treating students' beliefs as fixed and stable.

  7. Is Male Androphilia a Context-Dependent Cross-Cultural Universal?

    Science.gov (United States)

    Hames, Raymond; Garfield, Zachary; Garfield, Melissa

    2017-01-01

    The cross-cultural ethnographic literature has traditionally used the label male "homosexuality" to describe sexual relationships between biological males without considering whether or not the concept encompasses primary sexual attraction to adult males. Although male androphilia seems to be found in all national populations, its universal existence in tribal populations has been questioned. Our goal is to review previous cross-cultural classifications and surveys of male same sex behavior to present a system that does justice to its varied expressions, especially as it is informed by contemporary sexuality research. Previous comparative research does not effectively distinguish male same sex behavior from male androphilia. Using the standard cross-cultural sample (SCCS) as a sampling frame and the ethnographic sources in the human relations area files and elsewhere, we present distributional data on various forms of male same sex behavior. The SCCS is useful because it is designed to be representative of all historically known social formations and the sample is designed to reduce similarities as a consequence of common descent or historical origin as well as reduce the probability of diffusion of sociocultural practices from one culture to another. Our results show that male same sex behavior as well as male androphilia is much more common than previously estimated in the SCCS. With our findings, we make an argument that male androphilia is a context-dependent cross-cultural universal.

  8. Involvement of dopamine D1/D5 and D2 receptors in context-dependent extinction learning and memory reinstatement

    Directory of Open Access Journals (Sweden)

    Marion Agnes Emma Andre

    2016-01-01

    Full Text Available Dopamine contributes to the regulation of higher order information processing and executive control. It is important for memory consolidation processes, and for the adaptation of learned responses based on experience. In line with this, under aversive learning conditions, application of dopamine receptor antagonists prior to extinction result in enhanced memory reinstatement. Here, we investigated the contribution of the dopaminergic system to extinction and memory reinstatement (renewal of an appetitive spatial learning task in rodents. Rats were trained for 3 days in a T-maze (context ‘A’ to associate a goal arm with a food reward, despite low reward probability (acquisition phase. On day 4, extinction learning (unrewarded occurred, that was reinforced by a context change (‘B’. On day 5, re-exposure to the (unrewarded ‘A’-context took place (renewal of context ‘A’, followed by extinction of context ‘A’. In control animals, significant extinction occurred on day 4, that was followed by an initial memory reinstatement (renewal on day 5, that was, in turn, succeeded by extinction of renewal. Intracerebral treatment with a D1/D5-receptor antagonist prior to the extinction trials, elicited a potent enhancement of extinction in context ‘B’. By contrast, a D1/D5-agonist impaired renewal in context ’A’. Extinction in the ‘A’ context on day 5 was unaffected by the D1/D5-ligands. Treatment with a D2-receptor antagonist prior to extinction had no overall effect on extinction in context ‘B or renewal in context ‘A’, although extinction of the renewal effect was impaired on day 5, compared to controls.Taken together, these data suggest that dopamine acting on the D1/D5-receptor modulates both acquisition and consolidation of context-dependent extinction. By contrast, the D2-receptor may contribute to context-independent aspects of this kind of extinction learning.

  9. Dependence measures for non-cigarette tobacco products within the context of the global epidemic: a systematic review.

    Science.gov (United States)

    De Leon, Elaine; Smith, Katherine Clegg; Cohen, Joanna E

    2014-05-01

    Validated metrics of tobacco dependence exist, but their value for global surveillance of tobacco dependence and development of tobacco control interventions is not well understood. This paper reviews tobacco dependence metrics for non-cigarette products, and whether measures of tobacco dependence have been validated in low-income and middle-income countries (LMIC). Searches were conducted in PubMed, Scopus, PsycINFO, EMBASE, CINAHL and Global Health databases using variant terms for types of tobacco, dependence, measures and validity/reliability. Articles discussing dependence theories and/or metrics were fully reviewed and synthesised. Searches yielded 2702 unique articles. Two independent coders identified 587 articles for abstract review, and 229 were subsequently fully reviewed. Findings from 50 eligible papers are summarised. An initial thematic analysis concentrated on four concepts: general tobacco dependence, dependence metrics, tobacco dependence in LMIC and dependence on non-cigarette tobacco. Analysis identified 14 distinct tobacco dependence instruments. Existing metrics treat tobacco dependence as multifaceted. Measures have been developed almost exclusively around cigarette smoking, although some validation and application across products has occurred. Where cross-national validation has occurred, however, this has rarely included LMIC. For purposes of global surveillance of tobacco dependence, there is a compelling need for validated measures to apply universally across social contexts and a multitude of tobacco products. Alternatively, effective tobacco control interventions require validated dependence measures that integrate specific behavioural elements and social context of product use. While different measures of dependence are required to fulfil each of these goals, both have value in addressing the global tobacco epidemic.

  10. Influenza Hemifusion Phenotype Depends on Membrane Context: Differences in Cell-Cell and Virus-Cell Fusion.

    Science.gov (United States)

    Zawada, Katarzyna E; Okamoto, Kenta; Kasson, Peter M

    2018-03-02

    Influenza viral entry into the host cell cytoplasm is accomplished by a process of membrane fusion mediated by the viral hemagglutinin protein. Hemagglutinin acts in a pH-triggered fashion, inserting a short fusion peptide into the host membrane followed by refolding of a coiled-coil structure to draw the viral envelope and host membranes together. Mutations to this fusion peptide provide an important window into viral fusion mechanisms and protein-membrane interactions. Here, we show that a well-described fusion peptide mutant, G1S, has a phenotype that depends strongly on the viral membrane context. The G1S mutant is well known to cause a "hemifusion" phenotype based on experiments in transfected cells, where cells expressing G1S hemagglutinin can undergo lipid mixing in a pH-triggered fashion similar to virus but will not support fusion pores. We compare fusion by the G1S hemagglutinin mutant expressed either in cells or in influenza virions and show that this hemifusion phenotype occurs in transfected cells but that native virions are able to support full fusion, albeit at a slower rate and 10-100× reduced infectious titer. We explain this with a quantitative model where the G1S mutant, instead of causing an absolute block of fusion, alters the protein stoichiometry required for fusion. This change slightly slows fusion at high hemagglutinin density, as on the viral surface, but at lower hemagglutinin density produces a hemifusion phenotype. The quantitative model thus reproduces the observed virus-cell and cell-cell fusion phenotypes, yielding a unified explanation where membrane context can control the observed viral fusion phenotype. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Context-dependent activation of reduced autobiographical memory specificity as an avoidant coping style.

    Science.gov (United States)

    Debeer, Elise; Raes, Filip; Williams, J Mark G; Hermans, Dirk

    2011-12-01

    According to the affect-regulation hypothesis (Williams et al., 2007), reduced autobiographical memory specificity (rAMS) or overgeneral memory (OGM) might be considered a cognitive avoidance strategy; that is, people learn to avoid the emotionally painful consequences associated with the retrieval of specific negative memories. Based on this hypothesis, one would predict significant negative associations between AMS and avoidant coping. However, studies investigating this prediction have led to equivocal results. In the present study we tested a possible explanation for these contradictory findings. It was hypothesized that rAMS (in part) reflects an avoidant coping strategy, which might only become apparent under certain conditions, that is, conditions that signal the possibility of 'danger.' To test this hypothesis, we assessed AMS and behavioral avoidance but experimentally manipulated the instructions. In the neutral condition, two parallel versions of the Autobiographical Memory Test (AMT) were presented under neutral instructions. In the threat condition, the first AMT was presented under neutral instructions, while the second AMT was presented under 'threat instructions.' Results showed no significant correlations between avoidance and OGM under neutral conditions but significant and markedly stronger correlations under threat conditions, with more avoidance being associated with fewer specific and more categoric memories. In addition, high avoiders showed a stronger reduction in AMS in the threat condition as compared with the neutral condition, while low avoiders showed no such difference between conditions. The data confirm that OGM can be considered as part of a broader avoidant coping style. However, more importantly, they show that, at least in nonclinical individuals, the activation of this coping style may depend on the context. (c) 2011 APA, all rights reserved.

  12. Context-dependent regulation of feeding behaviour by the insulin receptor, DAF-2, in Caenorhabditis elegans.

    Science.gov (United States)

    Dillon, James; Holden-Dye, Lindy; O'Connor, Vincent; Hopper, Neil A

    2016-06-01

    Insulin signalling plays a significant role in both developmental programmes and pathways modulating the neuronal signalling that controls adult behaviour. Here, we have investigated insulin signalling in food-associated behaviour in adult C. elegans by scoring locomotion and feeding on and off bacteria, the worm's food. This analysis used mutants (daf-2, daf-18) of the insulin signalling pathway, and we provide evidence for an acute role for insulin signalling in the adult nervous system distinct from its impact on developmental programmes. Insulin receptor daf-2 mutants move slower than wild type both on and off food and showed impaired locomotory responses to food deprivation. This latter behaviour is manifest as a failure to instigate dispersal following prolonged food deprivation and suggests a role for insulin signalling in this adaptive response. Insulin receptor daf-2 mutants are also deficient in pharyngeal pumping on food and off food. Pharmacological analysis showed the pharynx of daf-2 is selectively compromised in its response to 5-HT compared to the excitatory neuropeptide FLP-17. By comparing the adaptive pharyngeal behaviour in intact worms and isolated pharyngeal preparations, we determined that an insulin-dependent signal extrinsic to the pharyngeal system is involved in feeding adaptation. Hence, we suggest that reactive insulin signalling modulates both locomotory foraging and pharyngeal pumping as the animal adapts to the absence of food. We discuss this in the context of insulin signalling directing a shift in the sensitivity of neurotransmitter systems to regulate the worm's response to changes in food availability in the environment.

  13. Differential surface phenotype and context-dependent reactivity of functionally diverse NKT cells.

    Science.gov (United States)

    Cameron, Garth; Godfrey, Dale I

    2018-03-05

    Natural Killer T (NKT) cells are a functionally diverse population that recognizes lipid-based antigens in association with the antigen-presenting molecule CD1d. Here, we define a technique to separate the functionally distinct thymic NKT1, NKT2 and NKT17 cell subsets by their surface expression of CD278 (ICOS) and the activation-associated glycoform of CD43, enabling the investigation of subset-specific effector-functions. We report that all three subsets express the transcription factor GATA-3 and the potential to produce IL-4 and IL-10 following activation. This questions the notion that NKT2 cells are the predominant source of IL-4 within the NKT cell pool, and suggests that IL-10-production may be more indicative of NKT cell plasticity than the existence of a distinct regulatory lineage or subset. We also show that many NKT17 cells are CD4 + and are biased toward Vβ8.3 TCR gene usage. Lastly, we demonstrate that the toll-like receptor (TLR) ligand lipopolysaccharide (LPS) can induce a NKT17 cell-biased response, even in the absence of exogenous antigen, and that combining LPS with α-GalCer resulted in enhanced IL-17A-production, and reduced levels of the immunosuppressive cytokine IL-10. This study provides a novel means to examine the context-dependent reactivity of the functionally heterogeneous NKT cell population and provides important new insight into the functional biology of these subsets. © 2018 Australasian Society for Immunology Inc.

  14. Semantic Modeling for Exposomics with Exploratory Evaluation in Clinical Context

    Directory of Open Access Journals (Sweden)

    Jung-wei Fan

    2017-01-01

    Full Text Available Exposome is a critical dimension in the precision medicine paradigm. Effective representation of exposomics knowledge is instrumental to melding nongenetic factors into data analytics for clinical research. There is still limited work in (1 modeling exposome entities and relations with proper integration to mainstream ontologies and (2 systematically studying their presence in clinical context. Through selected ontological relations, we developed a template-driven approach to identifying exposome concepts from the Unified Medical Language System (UMLS. The derived concepts were evaluated in terms of literature coverage and the ability to assist in annotating clinical text. The generated semantic model represents rich domain knowledge about exposure events (454 pairs of relations between exposure and outcome. Additionally, a list of 5667 disorder concepts with microbial etiology was created for inferred pathogen exposures. The model consistently covered about 90% of PubMed literature on exposure-induced iatrogenic diseases over 10 years (2001–2010. The model contributed to the efficiency of exposome annotation in clinical text by filtering out 78% of irrelevant machine annotations. Analysis into 50 annotated discharge summaries helped advance our understanding of the exposome information in clinical text. This pilot study demonstrated feasibility of semiautomatically developing a useful semantic resource for exposomics.

  15. No evidence for visual context-dependency of olfactory learning in Drosophila

    Science.gov (United States)

    Yarali, Ayse; Mayerle, Moritz; Nawroth, Christian; Gerber, Bertram

    2008-08-01

    How is behaviour organised across sensory modalities? Specifically, we ask concerning the fruit fly Drosophila melanogaster how visual context affects olfactory learning and recall and whether information about visual context is getting integrated into olfactory memory. We find that changing visual context between training and test does not deteriorate olfactory memory scores, suggesting that these olfactory memories can drive behaviour despite a mismatch of visual context between training and test. Rather, both the establishment and the recall of olfactory memory are generally facilitated by light. In a follow-up experiment, we find no evidence for learning about combinations of odours and visual context as predictors for reinforcement even after explicit training in a so-called biconditional discrimination task. Thus, a ‘true’ interaction between visual and olfactory modalities is not evident; instead, light seems to influence olfactory learning and recall unspecifically, for example by altering motor activity, alertness or olfactory acuity.

  16. Context-dependent fluctuation of serotonin in the auditory midbrain: the influence of sex, reproductive state and experience

    Science.gov (United States)

    Hanson, Jessica L.; Hurley, Laura M.

    2014-01-01

    In the face of changing behavioral situations, plasticity of sensory systems can be a valuable mechanism to facilitate appropriate behavioral responses. In the auditory system, the neurotransmitter serotonin is an important messenger for context-dependent regulation because it is sensitive to both external events and internal state, and it modulates neural activity. In male mice, serotonin increases in the auditory midbrain region, the inferior colliculus (IC), in response to changes in behavioral context such as restriction stress and social contact. Female mice have not been measured in similar contexts, although the serotonergic system is sexually dimorphic in many ways. In the present study, we investigated the effects of sex, experience and estrous state on the fluctuation of serotonin in the IC across contexts, as well as potential relationships between behavior and serotonin. Contrary to our expectation, there were no sex differences in increases of serotonin in response to a restriction stimulus. Both sexes had larger increases in second exposures, suggesting experience plays a role in serotonergic release in the IC. In females, serotonin increased during both restriction and interactions with males; however, the increase was more rapid during restriction. There was no effect of female estrous phase on the serotonergic change for either context, but serotonin was related to behavioral activity in females interacting with males. These results show that changes in behavioral context induce increases in serotonin in the IC by a mechanism that appears to be uninfluenced by sex or estrous state, but may depend on experience and behavioral activity. PMID:24198252

  17. Predator-Prey Interactions are Context Dependent in a Grassland Plant-Grasshopper-Wolf Spider Food Chain.

    Science.gov (United States)

    Laws, Angela N; Joern, Anthony

    2015-06-01

    Species interactions are often context dependent, where outcomes vary in response to one or more environmental factors. It remains unclear how abiotic conditions like temperature combine with biotic factors such as consumer density or food quality to affect resource availability or influence species interactions. Using the large grasshopper Melanoplus bivittatus (Say) and a common wolf spider [Rabidosa rabida (Walkenaer)], we conducted manipulative field experiments in tallgrass prairie to examine how spider-grasshopper interactions respond to manipulations of temperature, grasshopper density, and food quality. Grasshopper survival was density dependent, as were the effects of spider presence and food quality in context-dependent ways. In high grasshopper density treatments, predation resulted in increased grasshopper survival, likely as a result of reduced intraspecific competition in the presence of spiders. Spiders had no effect on grasshopper survival when grasshoppers were stocked at low densities. Effects of the experimental treatments were often interdependent so that effects were only observed when examined together with other treatments. The occurrence of trophic cascades was context dependent, where the effects of food quality and spider presence varied with temperature under high-density treatments. Temperature weakly affected the impact of spider presence on M. bivittatus survivorship when all treatments were considered simultaneously, but different context-dependent responses to spider presence and food quality were observed among the three temperature treatments under high-density conditions. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how key biotic and abiotic factors combine to influence species interactions. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Strain- and context-dependent effects of the anandamide hydrolysis inhibitor URB597 on social behavior in rats

    NARCIS (Netherlands)

    Manduca, A.; Servadio, M.; Campolongo, P.; Palmery, M.; Trabace, L.; Vanderschuren, L.J.M.J.; Cuomo, V; Trezza, V.

    2014-01-01

    Genetic and environmental factors play an important role in the cannabinoid modulation of motivation and emotion. Therefore, the aim of the present study was to test whether anandamide modulation of social behavior is strain- and context-dependent. We tested the effects of the anandamide hydrolysis

  19. Cognate effects in sentence context depend on word class, L2 proficiency, and task

    NARCIS (Netherlands)

    Bultena, S.S.; Dijkstra, A.F.J.; Hell, J.G. van

    2014-01-01

    Noun translation equivalents that share orthographic and semantic features, called "cognates", are generally recognized faster than translation equivalents without such overlap. This cognate effect, which has also been obtained when cognates and noncognates were embedded in a sentence context,

  20. Glucocorticoids exert context-dependent effects on cells of the joint in vitro.

    Science.gov (United States)

    Madsen, Suzi H; Andreassen, Kim V; Christensen, Søren T; Karsdal, Morten A; Sverdrup, Francis M; Bay-Jensen, Anne-Christine; Henriksen, Kim

    2011-12-11

    Glucocorticoids are known to attenuate bone formation in vivo leading to decreased bone volume and increased risk of fractures, whereas effects on the joint tissue are less characterized. However, glucocorticoids appear to have a reducing effect on inflammation and pain in osteoarthritis. This study aimed at characterizing the effect of glucocorticoids on chondrocytes, osteoclasts, and osteoblasts. We used four model systems to investigate how glucocorticoids affect the cells of the joint; two intact tissues (femoral head- and cartilage-explants), and two separate cell cultures of osteoblasts (2T3-pre-osteoblasts) and osteoclasts (CD14(+)-monocytes). The model systems were cultured in the presence of two glucocorticoids; prednisolone or dexamethasone. To induce anabolic and catabolic conditions, cultures were activated by insulin-like growth factor I/bone morphogenetic protein 2 and oncostatin M/tumor necrosis factor-α, respectively. Histology and markers of bone- and cartilage-turnover were used to evaluate effects of glucocorticoid treatment. Prednisolone treatment decreased collagen type-II degradation in immature cartilage, whereas glucocorticoids did not affect collagen type-II in mature cartilage. Glucocorticoids had an anti-catabolic effect on catabolic-activated cartilage from a bovine stifle joint and murine femoral heads. Glucocorticoids decreased viability of all bone cells, leading to a reduction in osteoclastogenesis and bone resorption; however, bone morphogenetic protein 2-stimulated osteoblasts increased bone formation, as opposed to non-stimulated osteoblasts. Using highly robust in vitro models of bone and cartilage turnover, we suggest that effects of glucocorticoids highly depend on the activation and differential stage of the cell targeted in the joint. Present data indicated that glucocorticoid treatment may be beneficial for articular cartilage, although detrimental effects on bone should be taken into account. Copyright © 2011 Elsevier Inc

  1. Identifying missing dictionary entries with frequency-conserving context models.

    Science.gov (United States)

    Williams, Jake Ryland; Clark, Eric M; Bagrow, James P; Danforth, Christopher M; Dodds, Peter Sheridan

    2015-10-01

    In an effort to better understand meaning from natural language texts, we explore methods aimed at organizing lexical objects into contexts. A number of these methods for organization fall into a family defined by word ordering. Unlike demographic or spatial partitions of data, these collocation models are of special importance for their universal applicability. While we are interested here in text and have framed our treatment appropriately, our work is potentially applicable to other areas of research (e.g., speech, genomics, and mobility patterns) where one has ordered categorical data (e.g., sounds, genes, and locations). Our approach focuses on the phrase (whether word or larger) as the primary meaning-bearing lexical unit and object of study. To do so, we employ our previously developed framework for generating word-conserving phrase-frequency data. Upon training our model with the Wiktionary, an extensive, online, collaborative, and open-source dictionary that contains over 100000 phrasal definitions, we develop highly effective filters for the identification of meaningful, missing phrase entries. With our predictions we then engage the editorial community of the Wiktionary and propose short lists of potential missing entries for definition, developing a breakthrough, lexical extraction technique and expanding our knowledge of the defined English lexicon of phrases.

  2. Career Persistence Model for Female Engineers in the Indonesian Context

    Directory of Open Access Journals (Sweden)

    Lies Dahlia

    2017-08-01

    Full Text Available Extant studies about female engineers have suggested their career persistency in the engineering career is influenced by the workplace, which is characterized by male dominated culture making them feel marginalized. In Indonesia, similar studies for reference are limited. This paper is based on an exploratory quantitative study using a questionnaire developed based on the Career Persistence Model. This paper is based on an empirical exploratory quantitative study by adopting Buse’s et al. Career Persistence Model (2013. The intention is to contribute to the literature in the context of Indonesia. It explores the Indonesian cultural dimensions and investigates their relationship to the roles of women in family, society and the workplace, and how women manage to navigate barriers to avoid taking alternative career paths. Contrary to extant studies, findings show women feel equally treated to men in the workplace, however some work demands may hinder. The strong acknowledgement of one’s roles in this collective society outdoes the opinions that the Islamic jurisprudence (fiqh has marginalized empowerment of women, resulting in gender-based injustices and discrimination. Future studies should look into social supports at the workplace in an attempt to retain and increase the share of women in the engineering career in Indonesia.

  3. Modelling transport phenomena in a multi-physics context

    Science.gov (United States)

    Marra, Francesco

    2015-01-01

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  4. Modelling transport phenomena in a multi-physics context

    Energy Technology Data Exchange (ETDEWEB)

    Marra, Francesco [Dipartimento di Ingegneria Chimica e Alimentare - Università degli studi di Salerno Via Ponte Don Melillo - 84084 Fisciano SA (Italy)

    2015-01-22

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  5. Modelling transport phenomena in a multi-physics context

    International Nuclear Information System (INIS)

    Marra, Francesco

    2015-01-01

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating

  6. Reply: "Function of Cryopreserved Mesenchymal Stromal Cells With and Without Interferon-γ Prelicensing Is Context Dependent".

    Science.gov (United States)

    Galipeau, Jacques

    2017-05-01

    Freshly thawed mesenchymal stromal cells (MSCs) transiently display altered cell physiology and a recent report by Chinnadurai et al. [Stem Cells 2016;34:2429-2442] demonstrated that thawed allogeneic MSCs are also susceptible to T-cell mediated lysis in vitro and that this effect can be mitigated by activating MSCs with IFN-γ prior to freeze and thaw. In the letter to the editor by Ankrum et al., "Function of Cryopreserved MSCs with and without IFN-γ pre-licensing is Context Dependent," the author provide data that IFN-γ pretreatment of human MSCs before cryobanking fails to enhance their potency post thaw in a mouse model of retinal disease. Considering that the experimental set up involves the use of human MSCs in mice with normal immune systems, we propose that IFN-γ MSC activation enhances the immune incompatibility of xenogenic human cells in a manner which may confound the predictive value for human translational use. Stem Cells 2017;35:1440-1441. © 2016 AlphaMed Press.

  7. Selector genes display tumor cooperation and inhibition in Drosophila epithelium in a developmental context-dependent manner

    Directory of Open Access Journals (Sweden)

    Ram Prakash Gupta

    2017-11-01

    Full Text Available During animal development, selector genes determine identities of body segments and those of individual organs. Selector genes are also misexpressed in cancers, although their contributions to tumor progression per se remain poorly understood. Using a model of cooperative tumorigenesis, we show that gain of selector genes results in tumor cooperation, but in only select developmental domains of the wing, haltere and eye-antennal imaginal discs of Drosophila larva. Thus, the field selector, Eyeless (Ey, and the segment selector, Ultrabithorax (Ubx, readily cooperate to bring about neoplastic transformation of cells displaying somatic loss of the tumor suppressor, Lgl, but in only those developmental domains that express the homeo-box protein, Homothorax (Hth, and/or the Zinc-finger protein, Teashirt (Tsh. In non-Hth/Tsh-expressing domains of these imaginal discs, however, gain of Ey in lgl− somatic clones induces neoplastic transformation in the distal wing disc and haltere, but not in the eye imaginal disc. Likewise, gain of Ubx in lgl− somatic clones induces transformation in the eye imaginal disc but not in its endogenous domain, namely, the haltere imaginal disc. Our results reveal that selector genes could behave as tumor drivers or inhibitors depending on the tissue contexts of their gains.

  8. Modelling electricity futures prices using seasonal path-dependent volatility

    International Nuclear Information System (INIS)

    Fanelli, Viviana; Maddalena, Lucia; Musti, Silvana

    2016-01-01

    Highlights: • A no-arbitrage term structure model is applied to the electricity market. • Volatility parameters of the HJM model are estimated by using German data. • The model captures the seasonal price behaviour. • Electricity futures prices are forecasted. • Call options are evaluated according to different strike prices. - Abstract: The liberalization of electricity markets gave rise to new patterns of futures prices and the need of models that could efficiently describe price dynamics grew exponentially, in order to improve decision making for all of the agents involved in energy issues. Although there are papers focused on modelling electricity as a flow commodity by using Heath et al. (1992) approach in order to price futures contracts, the literature is scarce on attempts to consider a seasonal volatility as input to models. In this paper, we propose a futures price model that allows looking into observed stylized facts in the electricity market, in particular stochastic price variability, and periodic behavior. We consider a seasonal path-dependent volatility for futures returns that are modelled in Heath et al. (1992) framework and we obtain the dynamics of futures prices. We use these series to price the underlying asset of a call option in a risk management perspective. We test the model on the German electricity market, and we find that it is accurate in futures and option value estimates. In addition, the obtained results and the proposed methodology can be useful as a starting point for risk management or portfolio optimization under uncertainty in the current context of energy markets.

  9. System reliability time-dependent models

    International Nuclear Information System (INIS)

    Debernardo, H.D.

    1991-06-01

    A probabilistic methodology for safety system technical specification evaluation was developed. The method for Surveillance Test Interval (S.T.I.) evaluation basically means an optimization of S.T.I. of most important system's periodically tested components. For Allowed Outage Time (A.O.T.) calculations, the method uses system reliability time-dependent models (A computer code called FRANTIC III). A new approximation, which was called Independent Minimal Cut Sets (A.C.I.), to compute system unavailability was also developed. This approximation is better than Rare Event Approximation (A.E.R.) and the extra computing cost is neglectible. A.C.I. was joined to FRANTIC III to replace A.E.R. on future applications. The case study evaluations verified that this methodology provides a useful probabilistic assessment of surveillance test intervals and allowed outage times for many plant components. The studied system is a typical configuration of nuclear power plant safety systems (two of three logic). Because of the good results, these procedures will be used by the Argentine nuclear regulatory authorities in evaluation of technical specification of Atucha I and Embalse nuclear power plant safety systems. (Author) [es

  10. Model-driven design of context-aware applications

    NARCIS (Netherlands)

    Shishkov, Boris; van Sinderen, Marten J.; Cardoso, J.; Cordeiro, J.; Filipe, J.

    2007-01-01

    In many cases, in order to be effective, software applications need to allow sensitivity to context changes. This implies however additional complexity associated with the need for applications’ adaptability (being capable of capturing context, interpreting it and reacting on it). Hence, we envision

  11. Spatiotemporal Context Awareness for Urban Traffic Modeling and Prediction: Sparse Representation Based Variable Selection.

    Directory of Open Access Journals (Sweden)

    Su Yang

    Full Text Available Spatial-temporal correlations among the data play an important role in traffic flow prediction. Correspondingly, traffic modeling and prediction based on big data analytics emerges due to the city-scale interactions among traffic flows. A new methodology based on sparse representation is proposed to reveal the spatial-temporal dependencies among traffic flows so as to simplify the correlations among traffic data for the prediction task at a given sensor. Three important findings are observed in the experiments: (1 Only traffic flows immediately prior to the present time affect the formation of current traffic flows, which implies the possibility to reduce the traditional high-order predictors into an 1-order model. (2 The spatial context relevant to a given prediction task is more complex than what is assumed to exist locally and can spread out to the whole city. (3 The spatial context varies with the target sensor undergoing prediction and enlarges with the increment of time lag for prediction. Because the scope of human mobility is subject to travel time, identifying the varying spatial context against time lag is crucial for prediction. Since sparse representation can capture the varying spatial context to adapt to the prediction task, it outperforms the traditional methods the inputs of which are confined as the data from a fixed number of nearby sensors. As the spatial-temporal context for any prediction task is fully detected from the traffic data in an automated manner, where no additional information regarding network topology is needed, it has good scalability to be applicable to large-scale networks.

  12. Smart Questions : Context-dependent mobile information exchange for military operations

    NARCIS (Netherlands)

    Streefkerk, J.W.; Heuvelink, A.

    2014-01-01

    During military mISSIOns, mobile devices allow information exchange between distributed groups of soldiers. As the context of use changes frequently and more (unstructured) information becomes available during missions, the challenge is to ensure that the right information reaches the right

  13. Context-dependent adaptation improves robustness of myoelectric control for upper-limb prostheses

    Science.gov (United States)

    Patel, Gauravkumar K.; Hahne, Janne M.; Castellini, Claudio; Farina, Dario; Dosen, Strahinja

    2017-10-01

    Objective. Dexterous upper-limb prostheses are available today to restore grasping, but an effective and reliable feed-forward control is still missing. The aim of this work was to improve the robustness and reliability of myoelectric control by using context information from sensors embedded within the prosthesis. Approach. We developed a context-driven myoelectric control scheme (cxMYO) that incorporates the inference of context information from proprioception (inertial measurement unit) and exteroception (force and grip aperture) sensors to modulate the outputs of myoelectric control. Further, a realistic evaluation of the cxMYO was performed online in able-bodied subjects using three functional tasks, during which the cxMYO was compared to a purely machine-learning-based myoelectric control (MYO). Main results. The results demonstrated that utilizing context information decreased the number of unwanted commands, improving the performance (success rate and dropped objects) in all three functional tasks. Specifically, the median number of objects dropped per round with cxMYO was zero in all three tasks and a significant increase in the number of successful transfers was seen in two out of three functional tasks. Additionally, the subjects reported better user experience. Significance. This is the first online evaluation of a method integrating information from multiple on-board prosthesis sensors to modulate the output of a machine-learning-based myoelectric controller. The proposed scheme is general and presents a simple, non-invasive and cost-effective approach for improving the robustness of myoelectric control.

  14. Context-dependent Semantic Processing in the Human Brain: Evidence from Idiom Comprehension

    NARCIS (Netherlands)

    Rommers, J.; Dijkstra, A.F.J.; Bastiaansen, M.C.M.

    2013-01-01

    Language comprehension involves activating word meanings and integrating them with the sentence context. This study examined whether these routines are carried out even when they are theoretically unnecessary, namely, in the case of opaque idiomatic expressions, for which the literal word meanings

  15. Context-dependent semantic processing in the human brain: Evidence from idiom comprehension

    NARCIS (Netherlands)

    Rommers, J.; Dijkstra, A.F.J.; Bastiaansen, M.C.M.

    2013-01-01

    Language comprehension involves activating word meanings and integrating them with the sentence context. This study examined whether these routines are carried out even when they are theoretically unnecessary, namely, in the case of opaque idiomatic expressions, for which the literal word meanings

  16. Pseudocontingencies and Choice Behavior in Probabilistic Environments with Context-Dependent Outcomes

    Science.gov (United States)

    Meiser, Thorsten; Rummel, Jan; Fleig, Hanna

    2018-01-01

    Pseudocontingencies are inferences about correlations in the environment that are formed on the basis of statistical regularities like skewed base rates or varying base rates across environmental contexts. Previous research has demonstrated that pseudocontingencies provide a pervasive mechanism of inductive inference in numerous social judgment…

  17. The Uses and Dependency Model of Mass Communication.

    Science.gov (United States)

    Rubin, Alan M.; Windahl, Sven

    1986-01-01

    Responds to criticism of the uses and gratification model by proposing a modified model integrating the dependency perspective. Suggests that this integrated model broadens the heuristic application of the earlier model. (MS)

  18. MODELS OF TOURIST DEVELOPMENT IN THE CONTEXT OF REGIONAL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Borma Afrodita

    2012-07-01

    Full Text Available Third year PhD candidate at the University of Oradea, under the guidance of Professor Mrs. Alina Bădulescu in the doctoral research project entitled: "Doctoral studies and Ph.D. candidates for competitive research on a knowledge based society", a co-financed project by the European Social Fund through the Sectoral Operational Program for Human Resources Development 2007 - 2013, Priority Axis 1. "Education and training in support for growth and development of a knowledge based society" I chose to present this subject in order to demonstrate the connection that exists between tourism and regional development. Having as research topic "Tourism and development in the Euro regional context” I felt it would be appropriate to devote a subchapter in presenting the impact of tourism in regional development. Thus I have analysed a number of specialised papers found at national and international level in order to achieve a synthesis on the approached topic. Authors such as Williams and Shaw (1991, Sharma (2004, Keskin and Cansiz (2010 were concerned with presenting the positive aspects of tourism in regional development. Condes (2004 presents on one hand the secrets regarding success in matter of tourist development, and on the other side he presents the possible risks that follow the development of tourism in a country / region (Condes 2004. Following the gathered information we found that indeed tourism plays an important role in regional development. The used research methodology consisted in using specialised literature in order to identify some models that illustrate the potential success of tourism in regional development. The space-temporal development model of tourism proposed by Opperman (1993, although it was developed at national level represents a useful tool in illustrating the potential success of tourism in regional development. Miossec's model (Sharma 2004:300 describes the structural evolution of touristic regions in

  19. Context dependence of acorn handling by the Algerian mouse (Mus spretus)

    Science.gov (United States)

    Gallego, D.; Morán-López, T.; Torre, I.; Navarro-Castilla, Á.; Barja, I.; Díaz, M.

    2017-10-01

    Perceived predation risk and competition for acorns are expected to affect scatter-hoarding decisions by Algerian mice (Mus spretus). We manipulated both factors by means of predator fecal scents and ungulate exclosures. We hypothesized that high-risk perception and ungulate presence would promote acorn dispersal. In the former case, it would stimulate acorn mobilization to safe microhabitats rather than in situ consumption. In the latter, increased competition for acorns would promote their storage for later consumption. We also expected that mice would adapt their foraging behavior to previous experience modulating the strength of these effects. In the presence of ungulates, mice focused their foraging activities on food acquisition at the expenses of vigilant behaviors. However, a more efficient foraging did not entail enhanced dispersal services. Lack of anti-predatory cover in tree surroundings may have deterred mice from transporting seeds outside canopies. Increased risk interacted with previous experience. In control trees (no predator odor), mice confidence increased throughout the night resulting in decreased vigilance and enhanced acorn mobilization rates. In contrast, in risky conditions (trees with predator odor) mice maintained a base-line vigilant behavior. Contrary to our expectations, increased risk did not result in higher acorn mobilization, but the opposite. Again, the scarcity of safe microhabitats for mobilization may have been the underlying cause of this behavior. Our results show that successful acorn dispersal depends, at least partly, on plant-animal relationships that are beyond the oak-rodent mutualism. Thus, any conservation policy aimed at restoring natural regeneration of oaks should take into account the interaction network in which oak-rodent encounters are embedded. In addition, they suggest that mice incorporate direct and indirect cues of risks (habitat structure) through recent experience. A better understanding of this process

  20. Comparing Transformation Possibilities of Topological Functioning Model and BPMN in the Context of Model Driven Architecture

    Directory of Open Access Journals (Sweden)

    Solomencevs Artūrs

    2016-05-01

    Full Text Available The approach called “Topological Functioning Model for Software Engineering” (TFM4SE applies the Topological Functioning Model (TFM for modelling the business system in the context of Model Driven Architecture. TFM is a mathematically formal computation independent model (CIM. TFM4SE is compared to an approach that uses BPMN as a CIM. The comparison focuses on CIM modelling and on transformation to UML Sequence diagram on the platform independent (PIM level. The results show the advantages and drawbacks the formalism of TFM brings into the development.

  1. On the context dependence of emotion displays: Perceptions of gold medalists' expressions of pride.

    Science.gov (United States)

    van Osch, Yvette; Zeelenberg, Marcel; Breugelmans, Seger M

    2016-11-01

    In spite of various claims for cross-cultural differences in the experience of pride, studies on the expression of pride have revealed few cross-cultural differences. Five studies using archival data from Olympic and national championships do show cross-cultural differences in the expression of pride and other positive emotions in pride-eliciting contexts, contingent on the social context of the expression, notably the in-group or out-group status of the audience. Chinese gold medalists were perceived to express less pride than American medalists when outperforming in-group competitors; when outperforming out-group members, however, no or smaller cross-cultural differences were observed. These findings are important because they indicate that cultural norms about emotion expression may be activated only in situations in which they serve a function in coordinating people's behaviour.

  2. ATL with strategy contexts: Expressiveness and Model Checking.

    OpenAIRE

    Da Costa , Arnaud; Laroussinie , François; Markey , Nicolas

    2010-01-01

    We study the alternating-time temporal logics ATL and ATL* extended with strategy contexts: these make agents commit to their strategies during the evaluation of formulas, contrary to plain ATL and ATL* where strategy quantifiers reset previously selected strategies. We illustrate the important expressive power of strategy contexts by proving that they make the extended logics, namely ATLsc and ATLsc*, equally expressive: any formula in ATLsc* can be translated into an equivalent, linear-...

  3. Crying in Context: Understanding Associations With Interpersonal Dependency and Social Support

    Directory of Open Access Journals (Sweden)

    Katherine L. Fiori

    2013-06-01

    Full Text Available This study examines the associations among interpersonal dependency, social support, and crying proneness, since crying is a behavior that is particularly relevant to the affiliative interpersonal goals characterizing maladaptive forms of dependency (Keltner & Kring, 1998. Data were collected from 305 first-year university students (M age = 18 years. A series of hierarchical linear regressions, controlling for gender, commuting status, romantic relationship status, stress, loneliness, and depressive symptoms, partially supported our hypotheses. That is, we found that a measure of maladaptive dependency (destructive overdependence, or DO and crying proneness were positively correlated, and that DO moderated the associations between social support and crying proneness. Specifically, we found that social support and crying were more closely positively associated among individuals high on DO compared to individuals low on DO. Our findings imply that interpersonal dependency may be an important factor in understanding individual differences in crying, and in determining whether crying is a successful elicitor of social support.

  4. Architecture and User-Context Models of CoCare: A Context-Aware Mobile Recommender System for Health Promotion.

    Science.gov (United States)

    Cerón-Rios, Gineth; López, Diego M; Blobel, Bernd

    2017-01-01

    Recommender systems (RS) are useful tools for filtering and sorting items and information for users. There is a wide diversity of approaches that help creating personalized recommendations. Context-aware recommender systems (CARS) are a kind of RS which provide adaptation capabilities to the user's environment, e.g., by sensing data through wearable devices or other biomedical sensors. In healthcare and wellbeing, CARS can support health promotion and health education, considering that each individual requires tailored intervention programs. Our research aims at proposing a context-aware mobile recommender system for the promotion of healthy habits. The system is adapted to the user's needs, his/her health information, interests, time, location and lifestyles. In this paper, the CARS computational architecture and the user and context models of health promotion are presented, which were used to implement and test a prototype recommender system.

  5. Embodied Semantics 150 Years After Broca: Context-Dependent Negation in Novelistic Storytelling

    Directory of Open Access Journals (Sweden)

    Anatole Pierre Fuksas

    2013-08-01

    Full Text Available The present study capitalizes on recent advances in neurophysiology concerning the involvement of the sensory-motor system in language recognition and understanding during reading and listening so as to explain the various roles played by negation in novelistic descriptions since the medieval origins of the genre. Textual evidence from a famous medieval verse novel, Chrétien de Troyes’ Chevalier de la Charrette, demonstrates that negation does not simply complicate the processing of a given description. Indeed, negative descriptions can be completely understood only if fully integrated in a complex context which entails the conceptual representation of the negated state of affairs.

  6. Absolute pitch memory: its prevalence among musicians and dependence on the testing context.

    Science.gov (United States)

    Wong, Yetta Kwailing; Wong, Alan C-N

    2014-04-01

    Absolute pitch (AP) is widely believed to be a rare ability possessed by only a small group of gifted and special individuals (AP possessors). While AP has fascinated psychologists, neuroscientists, and musicians for more than a century, no theory can satisfactorily explain why this ability is so rare and difficult to learn. Here, we show that AP ability appears rare because of the methodological issues of the standard pitch-naming test. Specifically, the standard test unnecessarily poses a high decisional demand on AP judgments and uses a testing context that is highly inconsistent with one's musical training. These extra cognitive challenges are not central to AP memory per se and have thus led to consistent underestimation of AP ability in the population. Using the standard test, we replicated the typical findings that the accuracy for general violinists was low (12.38 %; chance level = 0 %). With identical stimuli, scoring criteria, and participants, violinists attained 25 % accuracy in a pitch verification test in which the decisional demand of AP judgment was reduced. When the testing context was increasingly similar to their musical experience, verification accuracy improved further and reached 39 %, three times higher than that for the standard test. Results were replicated with a separate group of pianists. Our findings challenge current theories about AP and suggest that the prevalence of AP among musicians has been highly underestimated in prior work. A multimodal framework is proposed to better explain AP memory.

  7. GNG Motifs Can Replace a GGG Stretch during G-Quadruplex Formation in a Context Dependent Manner.

    Science.gov (United States)

    Das, Kohal; Srivastava, Mrinal; Raghavan, Sathees C

    2016-01-01

    G-quadruplexes are one of the most commonly studied non-B DNA structures. Generally, these structures are formed using a minimum of 4, three guanine tracts, with connecting loops ranging from one to seven. Recent studies have reported deviation from this general convention. One such deviation is the involvement of bulges in the guanine tracts. In this study, guanines along with bulges, also referred to as GNG motifs have been extensively studied using recently reported HOX11 breakpoint fragile region I as a model template. By strategic mutagenesis approach we show that the contribution from continuous G-tracts may be dispensible during G-quadruplex formation when such motifs are flanked by GNGs. Importantly, the positioning and number of GNG/GNGNG can also influence the formation of G-quadruplexes. Further, we assessed three genomic regions from HIF1 alpha, VEGF and SHOX gene for G-quadruplex formation using GNG motifs. We show that HIF1 alpha sequence harbouring GNG motifs can fold into intramolecular G-quadruplex. In contrast, GNG motifs in mutant VEGF sequence could not participate in structure formation, suggesting that the usage of GNG is context dependent. Importantly, we show that when two continuous stretches of guanines are flanked by two independent GNG motifs in a naturally occurring sequence (SHOX), it can fold into an intramolecular G-quadruplex. Finally, we show the specific binding of G-quadruplex binding protein, Nucleolin and G-quadruplex antibody, BG4 to SHOX G-quadruplex. Overall, our study provides novel insights into the role of GNG motifs in G-quadruplex structure formation which may have both physiological and pathological implications.

  8. GNG Motifs Can Replace a GGG Stretch during G-Quadruplex Formation in a Context Dependent Manner.

    Directory of Open Access Journals (Sweden)

    Kohal Das

    Full Text Available G-quadruplexes are one of the most commonly studied non-B DNA structures. Generally, these structures are formed using a minimum of 4, three guanine tracts, with connecting loops ranging from one to seven. Recent studies have reported deviation from this general convention. One such deviation is the involvement of bulges in the guanine tracts. In this study, guanines along with bulges, also referred to as GNG motifs have been extensively studied using recently reported HOX11 breakpoint fragile region I as a model template. By strategic mutagenesis approach we show that the contribution from continuous G-tracts may be dispensible during G-quadruplex formation when such motifs are flanked by GNGs. Importantly, the positioning and number of GNG/GNGNG can also influence the formation of G-quadruplexes. Further, we assessed three genomic regions from HIF1 alpha, VEGF and SHOX gene for G-quadruplex formation using GNG motifs. We show that HIF1 alpha sequence harbouring GNG motifs can fold into intramolecular G-quadruplex. In contrast, GNG motifs in mutant VEGF sequence could not participate in structure formation, suggesting that the usage of GNG is context dependent. Importantly, we show that when two continuous stretches of guanines are flanked by two independent GNG motifs in a naturally occurring sequence (SHOX, it can fold into an intramolecular G-quadruplex. Finally, we show the specific binding of G-quadruplex binding protein, Nucleolin and G-quadruplex antibody, BG4 to SHOX G-quadruplex. Overall, our study provides novel insights into the role of GNG motifs in G-quadruplex structure formation which may have both physiological and pathological implications.

  9. Teaching EFL Writing: An Approach Based on the Learner's Context Model

    Science.gov (United States)

    Lin, Zheng

    2017-01-01

    This study aims to examine qualitatively a new approach to teaching English as a foreign language (EFL) writing based on the learner's context model. It investigates the context model-based approach in class and identifies key characteristics of the approach delivered through a four-phase teaching and learning cycle. The model collects research…

  10. A Research on the Generative Learning Model Supported by Context-Based Learning

    Science.gov (United States)

    Ulusoy, Fatma Merve; Onen, Aysem Seda

    2014-01-01

    This study is based on the generative learning model which involves context-based learning. Using the generative learning model, we taught the topic of Halogens. This topic is covered in the grade 10 chemistry curriculum using activities which are designed in accordance with the generative learning model supported by context-based learning. The…

  11. Uncertainty Quantification in Scale-Dependent Models of Flow in Porous Media: SCALE-DEPENDENT UQ

    Energy Technology Data Exchange (ETDEWEB)

    Tartakovsky, A. M. [Computational Mathematics Group, Pacific Northwest National Laboratory, Richland WA USA; Panzeri, M. [Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Milano Italy; Tartakovsky, G. D. [Hydrology Group, Pacific Northwest National Laboratory, Richland WA USA; Guadagnini, A. [Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Milano Italy

    2017-11-01

    Equations governing flow and transport in heterogeneous porous media are scale-dependent. We demonstrate that it is possible to identify a support scale $\\eta^*$, such that the typically employed approximate formulations of Moment Equations (ME) yield accurate (statistical) moments of a target environmental state variable. Under these circumstances, the ME approach can be used as an alternative to the Monte Carlo (MC) method for Uncertainty Quantification in diverse fields of Earth and environmental sciences. MEs are directly satisfied by the leading moments of the quantities of interest and are defined on the same support scale as the governing stochastic partial differential equations (PDEs). Computable approximations of the otherwise exact MEs can be obtained through perturbation expansion of moments of the state variables in orders of the standard deviation of the random model parameters. As such, their convergence is guaranteed only for the standard deviation smaller than one. We demonstrate our approach in the context of steady-state groundwater flow in a porous medium with a spatially random hydraulic conductivity.

  12. Stabilization of the genome of the mismatch repair deficient Mycobacterium tuberculosis by context-dependent codon choice.

    Science.gov (United States)

    Wanner, Roger M; Güthlein, Carolin; Springer, Burkhard; Böttger, Erik C; Ackermann, Martin

    2008-05-28

    The rate at which a stretch of DNA mutates is determined by the cellular systems for DNA replication and repair, and by the nucleotide sequence of the stretch itself. One sequence feature with a particularly strong influence on the mutation rate are nucleotide repeats. Some microbial pathogens use nucleotide repeats in their genome to stochastically vary phenotypic traits and thereby evade host defense. However, such unstable sequences also come at a cost, as mutations are often deleterious. Here, we analyzed how these opposing forces shaped genome stability in the human pathogen Mycobacterium tuberculosis. M. tuberculosis lacks a mismatch repair system, and this renders nucleotide repeats particularly unstable. We found that proteins of M. tuberculosis are encoded by using codons in a context-dependent manner that prevents the emergence of nucleotide repeats. This context-dependent codon choice leads to a strong decrease in the estimated frame-shift mutation rate and thus to an increase in genome stability. These results indicate that a context-specific codon choice can partially compensate for the lack of a mismatch repair system, and helps to maintain genome integrity in this pathogen.

  13. Stabilization of the genome of the mismatch repair deficient Mycobacterium tuberculosis by context-dependent codon choice

    Directory of Open Access Journals (Sweden)

    Ackermann Martin

    2008-05-01

    Full Text Available Abstract Background The rate at which a stretch of DNA mutates is determined by the cellular systems for DNA replication and repair, and by the nucleotide sequence of the stretch itself. One sequence feature with a particularly strong influence on the mutation rate are nucleotide repeats. Some microbial pathogens use nucleotide repeats in their genome to stochastically vary phenotypic traits and thereby evade host defense. However, such unstable sequences also come at a cost, as mutations are often deleterious. Here, we analyzed how these opposing forces shaped genome stability in the human pathogen Mycobacterium tuberculosis. M. tuberculosis lacks a mismatch repair system, and this renders nucleotide repeats particularly unstable. Results We found that proteins of M. tuberculosis are encoded by using codons in a context-dependent manner that prevents the emergence of nucleotide repeats. This context-dependent codon choice leads to a strong decrease in the estimated frame-shift mutation rate and thus to an increase in genome stability. Conclusion These results indicate that a context-specific codon choice can partially compensate for the lack of a mismatch repair system, and helps to maintain genome integrity in this pathogen.

  14. Mutational analysis of the mycobacteriophage BPs promoter PR reveals context-dependent sequences for mycobacterial gene expression.

    Science.gov (United States)

    Oldfield, Lauren M; Hatfull, Graham F

    2014-10-01

    The PR promoter of mycobacteriophage BPs directs early lytic gene expression and is under the control of the BPs repressor, gp33. Reporter gene fusions showed that PR has modest activity in an extrachromosomal context but has activity that is barely detectable in an integrated context, even in the absence of its repressor. Mutational dissection of PR showed that it uses a canonical -10 hexamer recognized by SigA, and mutants with mutations to the sequence 5'-TATAMT had the greatest activities. It does not contain a 5'-TGN-extended -10 sequence, although mutants with mutations creating an extended -10 sequence had substantially increased promoter activity. Mutations in the -35 hexamer also influenced promoter activity but were strongly context dependent, and similar substitutions in the -35 hexamer differentially affected promoter activity, depending on the -10 and extended -10 motifs. This warrants caution in the construction of synthetic promoters or the bioinformatic prediction of promoter activity. Combinations of mutations throughout PR generated a calibrated series of promoters for expression of stably integrated recombinant genes in both Mycobacterium smegmatis and M. tuberculosis, with maximal promoter activity being more than 2-fold that of the strong hsp60 promoter. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  15. Experimental Measurement, Analysis and Modelling of Dependency ...

    African Journals Online (AJOL)

    This leads us to apply the method of optimal linearization associated the finite element method with the nonlinear problem of transfer of heat if thermal conductivity, the specific heat and the emissivity of studied material depend on the temperature. We obtain a good agreement between the resolution of the nonlinear ...

  16. Incorporating Pass-Phrase Dependent Background Models for Text-Dependent Speaker Verification

    OpenAIRE

    Sarkar, A. K.; Tan, Zheng-Hua

    2016-01-01

    In this paper, we propose pass-phrase dependent background models (PBMs) for text-dependent (TD) speaker verification (SV) to integrate the pass-phrase identification process into the conventional TD-SV system, where a PBM is derived from a text-independent background model through adaptation using the utterances of a particular pass-phrase. During training, pass-phrase specific target speaker models are derived from the particular PBM using the training data for the respective target model. ...

  17. A Model of Independent Learning Applied to the Online Context

    Science.gov (United States)

    Warring, Susan

    2013-01-01

    This case study forms a foundation for understanding the drivers for successful online learning within a constructivist paradigm. It investigates whether Chinese international students completing a degree had achieved a level of independence necessary to succeed in this context. It found that these students had not achieved the independence…

  18. Health promotion in context – a reflective-analytical model

    DEFF Research Database (Denmark)

    Liveng, Anne; Andersen, Heidi Lene; Lehn-Christiansen, Sine

    2018-01-01

    Health promotion constitutes a complex field of study, as it addresses multifaceted problems and involves a range of methods and theories. Students in the field of health promotion can find this challenging. To raise their level of reflexivity and support learning we have developed the “context m...

  19. Perceived neighborhood ethnic diversity and social outcomes: Context-dependent effects within a postindustrial city undergoing regeneration

    Science.gov (United States)

    Kearns, Ade; Whitley, Elise

    2018-01-01

    ABSTRACT This article examines whether perceived neighborhood ethnic diversity is associated with a range of social outcomes in a postindustrial city undergoing regeneration. The research included a survey in 3 types of deprived area in Glasgow: those undergoing regeneration, those directly adjoining regeneration areas, and those further removed from regeneration areas. In areas undergoing regeneration, perceived diversity was positively associated with many residential, cohesion, safety, and empowerment outcomes. This was also true, although to a lesser extent, in deprived areas at some distance from regeneration areas. In areas immediately surrounding the regeneration areas, perceived diversity had mixed associations with residential and safety outcomes and few associations with cohesion and empowerment outcomes. The results suggest that the effects of perceived diversity are context dependent within a city. Moreover, regeneration processes alter neighborhood contexts and therefore enable scale, timing, and duration of diversity to mediate the relationships between perceived diversity and social outcomes. PMID:29479290

  20. A Context-Aware Model to Provide Positioning in Disaster Relief Scenarios

    Directory of Open Access Journals (Sweden)

    Daniel Moreno

    2015-09-01

    Full Text Available The effectiveness of the work performed during disaster relief efforts is highly dependent on the coordination of activities conducted by the first responders deployed in the affected area. Such coordination, in turn, depends on an appropriate management of geo-referenced information. Therefore, enabling first responders to count on positioning capabilities during these activities is vital to increase the effectiveness of the response process. The positioning methods used in this scenario must assume a lack of infrastructure-based communication and electrical energy, which usually characterizes affected areas. Although positioning systems such as the Global Positioning System (GPS have been shown to be useful, we cannot assume that all devices deployed in the area (or most of them will have positioning capabilities by themselves. Typically, many first responders carry devices that are not capable of performing positioning on their own, but that require such a service. In order to help increase the positioning capability of first responders in disaster-affected areas, this paper presents a context-aware positioning model that allows mobile devices to estimate their position based on information gathered from their surroundings. The performance of the proposed model was evaluated using simulations, and the obtained results show that mobile devices without positioning capabilities were able to use the model to estimate their position. Moreover, the accuracy of the positioning model has been shown to be suitable for conducting most first response activities.

  1. Genetic selection for context-dependent stochastic phenotypes: Sp1 and TATA mutations increase phenotypic noise in HIV-1 gene expression.

    Directory of Open Access Journals (Sweden)

    Kathryn Miller-Jensen

    Full Text Available The sequence of a promoter within a genome does not uniquely determine gene expression levels and their variability; rather, promoter sequence can additionally interact with its location in the genome, or genomic context, to shape eukaryotic gene expression. Retroviruses, such as human immunodeficiency virus-1 (HIV, integrate their genomes into those of their host and thereby provide a biomedically-relevant model system to quantitatively explore the relationship between promoter sequence, genomic context, and noise-driven variability on viral gene expression. Using an in vitro model of the HIV Tat-mediated positive-feedback loop, we previously demonstrated that fluctuations in viral Tat-transactivating protein levels generate integration-site-dependent, stochastically-driven phenotypes, in which infected cells randomly 'switch' between high and low expressing states in a manner that may be related to viral latency. Here we extended this model and designed a forward genetic screen to systematically identify genetic elements in the HIV LTR promoter that modulate the fraction of genomic integrations that specify 'Switching' phenotypes. Our screen identified mutations in core promoter regions, including Sp1 and TATA transcription factor binding sites, which increased the Switching fraction several fold. By integrating single-cell experiments with computational modeling, we further investigated the mechanism of Switching-fraction enhancement for a selected Sp1 mutation. Our experimental observations demonstrated that the Sp1 mutation both impaired Tat-transactivated expression and also altered basal expression in the absence of Tat. Computational analysis demonstrated that the observed change in basal expression could contribute significantly to the observed increase in viral integrations that specify a Switching phenotype, provided that the selected mutation affected Tat-mediated noise amplification differentially across genomic contexts. Our study

  2. Humans but Not Chimpanzees Vary Face-Scanning Patterns Depending on Contexts during Action Observation.

    Directory of Open Access Journals (Sweden)

    Masako Myowa-Yamakoshi

    Full Text Available Human and nonhuman primates comprehend the actions of other individuals by detecting social cues, including others' goal-directed motor actions and faces. However, little is known about how this information is integrated with action understanding. Here, we present the ontogenetic and evolutionary foundations of this capacity by comparing face-scanning patterns of chimpanzees and humans as they viewed goal-directed human actions within contexts that differ in whether or not the predicted goal is achieved. Human adults and children attend to the actor's face during action sequences, and this tendency is particularly pronounced in adults when observing that the predicted goal is not achieved. Chimpanzees rarely attend to the actor's face during the goal-directed action, regardless of whether the predicted action goal is achieved or not. These results suggest that in humans, but not chimpanzees, attention to actor's faces conveying referential information toward the target object indicates the process of observers making inferences about the intentionality of an action. Furthermore, this remarkable predisposition to observe others' actions by integrating the prediction of action goals and the actor's intention is developmentally acquired.

  3. Context-dependent species identity effects within a functional group of filter-feeding bivalves.

    Science.gov (United States)

    Vaughn, Caryn C; Spooner, Daniel E; Galbraith, Heather S

    2007-07-01

    We asked whether species richness or species identity contributed more to ecosystem function in a trait-based functional group, burrowing, filter-feeding bivalves (freshwater mussels: Unionidae), and whether their importance changed with environmental context and species composition. We conducted a manipulative experiment in a small river examining the effects of mussel assemblages varying from one to eight species on benthic algal standing crop across two sets of environmental conditions: extremely low discharge and high water temperature (summer); and moderate discharge and water temperature (fall). We found strong species identity effects within this guild, with one species (Actinonaias ligamentina) influencing accrual of benthic algae more than other species, but only under summer conditions. We suspect that this effect is due to a combination of the greater biomass of this species and its higher metabolic and excretion rates at warm summer temperatures, resulting in increased nitrogen subsidies to benthic algae. We also found that Actinonaias influenced the condition of other mussel species, likely through higher consumption, interference, or both. This study demonstrates that species within trait-based functional groups do not necessarily have the same effects on ecosystem properties, particularly under different environmental conditions.

  4. Context-dependent player's movement interpretation: application to adaptive game development

    Science.gov (United States)

    Picard, Francois; Estraillier, Pascal

    2010-02-01

    Video games are more and more controlled by the real movements of the player. However, the player is constrained by the system devices, imposing a limited vocabulary of actions associated with a set of unnatural movements. To introduce more entertaining video games to players, a component-based architecture is proposed. It has been acknowledged as the starting point for the development of adaptive applications based on the hypothesis of a high level dialogue between the system and the player. The system adaptability relies on interpretation mechanisms of the player behaviors. These behaviors are defined through the representation of the real movements of the player who freely interacts with the 3D elements composing an immersive virtual environment, following a given game scenario. The efficient interpretation of the player movements relies on the introduction in the system of the management of the scene's context. The contextual information not only helps to determine the true meaning of an observed behavior but also makes the system to adapt its processes regarding this interpretation, while managing its hardware and software resources efficiently. A commercial motion capture interface has been enhanced by the elaboration of such a system.

  5. "It all depends": conceptualizing public involvement in the context of health technology assessment agencies.

    Science.gov (United States)

    Gauvin, Francois-Pierre; Abelson, Julia; Giacomini, Mita; Eyles, John; Lavis, John N

    2010-05-01

    There have been calls in recent years for greater public involvement in health technology assessment (HTA). Yet the concept of public involvement is poorly articulated and little attention has been paid to the context of HTA agencies. This article investigates how public involvement is conceptualized in the HTA agency environment. Using qualitative concept analysis methods, we reviewed the HTA literature and the websites of HTA agencies and conducted semi-structured interviews with informants in Canada, Denmark, and the United Kingdom. Our analysis reveals that HTA agencies' role as bridges or boundary organizations situated at the frontier of research and policymaking causes the agencies to struggle with the idea of public involvement. The HTA community is concerned with conceptualizing public involvement in such a way as to meet scientific and methodological standards without neglecting its responsibilities to healthcare policymakers. We offer a conceptual tool for analyzing the nature of public involvement across agencies, characterizing different domains, levels of involvement, and types of publics. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  6. Context dependency and saturating effects of loss of rare soil microbes on plant productivity

    Directory of Open Access Journals (Sweden)

    Gera eHol

    2015-06-01

    Full Text Available Land use intensification is associated with loss of biodiversity and altered ecosystem functioning. Until now most studies on the relationship between biodiversity and ecosystem functioning focused on random loss of species, while loss of rare species that usually are the first to disappear received less attention. Here we test if the effect of rare microbial species loss on plant productivity depends on the origin of the microbial soil community. Soils were sampled from three land use types at two farms. Microbial communities with increasing loss of rare species were created by inoculating sterilized soils with serially diluted soil suspensions. After 8 months of incubation, the effects of the different soil communities on abiotic soil properties, soil processes, microbial community composition and plant productivity was measured. Dilution treatments resulted in increasing species loss, which was in relation to abundance of bacteria in the original field soil, without affecting most of the other soil parameters and processes. Microbial species loss affected plant biomass positively, negatively or not at all, depending on soil origin, but not on land use history. Even within fields the effects of dilution on plant biomass varied between replicates, suggesting heterogeneity in microbial community composition. The effects of medium and severe species loss on plant biomass were similar, pointing towards a saturating effect of species loss. We conclude that changes in the composition of the soil microbial community, including rare species loss, can affect plant productivity, depending on the composition of the initial microbial community. Future work on the relation between function and species loss effects should address this variation by including multiple sampling origins.

  7. Context dependency and saturating effects of loss of rare soil microbes on plant productivity.

    Science.gov (United States)

    Hol, W H Gera; de Boer, Wietse; de Hollander, Mattias; Kuramae, Eiko E; Meisner, Annelein; van der Putten, Wim H

    2015-01-01

    Land use intensification is associated with loss of biodiversity and altered ecosystem functioning. Until now most studies on the relationship between biodiversity and ecosystem functioning focused on random loss of species, while loss of rare species that usually are the first to disappear received less attention. Here we test if the effect of rare microbial species loss on plant productivity depends on the origin of the microbial soil community. Soils were sampled from three land use types at two farms. Microbial communities with increasing loss of rare species were created by inoculating sterilized soils with serially diluted soil suspensions. After 8 months of incubation, the effects of the different soil communities on abiotic soil properties, soil processes, microbial community composition, and plant productivity was measured. Dilution treatments resulted in increasing species loss, which was in relation to abundance of bacteria in the original field soil, without affecting most of the other soil parameters and processes. Microbial species loss affected plant biomass positively, negatively or not at all, depending on soil origin, but not on land use history. Even within fields the effects of dilution on plant biomass varied between replicates, suggesting heterogeneity in microbial community composition. The effects of medium and severe species loss on plant biomass were similar, pointing toward a saturating effect of species loss. We conclude that changes in the composition of the soil microbial community, including rare species loss, can affect plant productivity, depending on the composition of the initial microbial community. Future work on the relation between function and species loss effects should address this variation by including multiple sampling origins.

  8. Toward a Process Framework of Business Model Innovation in the Global Context

    DEFF Research Database (Denmark)

    Cao, Yangfeng; Li, Peter Ping; Skat-Rørdam, Peter

    2014-01-01

    Primarily due to the large gaps in economic and institutional contexts between the developed and emerging economies, effective business models in the two distinctive contexts tend to differ. In particular, the business model innovation (BMI) at the subsidiary level plays an important role...... in a feedback loop. Hence, we contribute to the literatures of BMI and dynamic capability by enriching both research streams, especially the critical link between BMI and dynamic capability in the context of international strategic entrepreneurship....

  9. A Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds

    National Research Council Canada - National Science Library

    Raye, Julie K; Smith, Ralph C

    2004-01-01

    This paper summarizes the development of a homogenized free energy model which characterizes the temperature-dependent hysteresis and constitutive nonlinearities inherent to relaxor ferroelectric materials...

  10. Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

    Science.gov (United States)

    Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

    2008-08-01

    We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

  11. Time dependent viscous string cloud cosmological models

    Science.gov (United States)

    Tripathy, S. K.; Nayak, S. K.; Sahu, S. K.; Routray, T. R.

    2009-09-01

    Bianchi type-I string cosmological models are studied in Saez-Ballester theory of gravitation when the source for the energy momentum tensor is a viscous string cloud coupled to gravitational field. The bulk viscosity is assumed to vary with time and is related to the scalar expansion. The relationship between the proper energy density ρ and string tension density λ are investigated from two different cosmological models.

  12. Theoretical Model of Engagement in the Context of Brand Communities

    OpenAIRE

    Flávia D\\u2019albergaria Freitas; Victor Manoel Cunha de Almeida

    2017-01-01

    This essay proposes to refine the concept of consumer engagement in the context of brand communities. A comprehensive review of studies addressing the phenomenon of brand community was made. This paper follows the tradition of Marketing Research and Consumer Behavior, more specifically the perspective of cognitive psychology. The main theoretical foundation of the study is the Social Identity Theory (SIT), also incorporating relevant contributions from the perspective of Consumer Culture Theo...

  13. Using of Protectionism Policy Tools in the context of WTO from the Perspective of Dependency Theory

    Directory of Open Access Journals (Sweden)

    Göksel KARAŞ

    2017-12-01

    Full Text Available Since the 1980s, when neoliberal policies have been intensively implemented, the distribution of income between developed and less developed countries in the world has begun to increase inequality. There are discourses that the neoliberal view suggests that today's wealthy countries are successful with free market economics, so that all countries in the world must move to a free market economy system and that neoliberal policies are the only way for development. According to the neoliberal policy which advocates the state neutrality in the economy, the role of the state in the economy should be reduced. As a result, weakening the effectiveness of government policy-setting and implementation in the economy is intended. Thus, developed countries direct the underdeveloped or developing countries in the direction of their own interests. The result of these discourses, the theory of dependence which states that there is a relationship between developed and underdeveloped countries based on power and control, that underdevelopment of underdeveloped countries should be sought in the development process of developed countries has come out. The aim of the study is to assess the results of the use of defense measures in the trade policy implemented under the World Trade Organization (WTO, based on the assumptions of the dependency theory. When the use of defense instruments in trade policy is examined, it appears that these instruments have been effectively used by developed countries that advocate and enforce the free market economy in the world.

  14. What you find depends on where you look: responses to proximate habitat vary with landscape context

    Directory of Open Access Journals (Sweden)

    Mary Ann Cunningham

    2016-12-01

    Full Text Available There is persistent interest in understanding responses of passerine birds to habitat fragmentation, but research findings have been inconsistent and sometimes contradictory in conclusions about how birds respond to characteristics of sites they occupy, such as habitat patch size or edge density. We examined whether these inconsistencies could result from differences in the amount of habitat in the surrounding landscape, e.g., for woodland birds, the amount of tree cover in the surrounding landscape. We compared responses of 22 woodland bird species to proximate-scale tree cover in open landscapes versus wooded landscapes. Our main expectation was that woodland birds would tolerate less suitable sites (less tree cover at the site scale in open environments where they had little choice-where little tree cover was available in the surrounding area. We compared responses using logistic regression coefficients and loess plots in open and wooded landscapes in eastern North Dakota, USA. Responses to proximate-scale tree cover were stronger, not weaker, as expected, in open landscapes. In some cases the sign of the response changed from positive to negative in contrasting landscapes. We draw two conclusions: First, observed responses to proximate habitat measures such as habitat extent or edge density cannot be interpreted reliably unless landscape context is specified. Second, birds appear more selective, not less so, where habitat is sparse. Habitat loss and fragmentation at the landscape scale are likely to reduce the usefulness of local habitat conservation, and regional drivers in land-use change can have important effects for site-scale habitat use.

  15. Adapting authentic science practices into contexts for learning: The case of models and modelling in pre-university chemistry education

    NARCIS (Netherlands)

    Prins, G.T.; Pilot, A.

    2013-01-01

    This research study explores the potential benefits of using authentic modelling practices as contexts for learning in chemistry education. An authentic modelling practice is characterized as professionals sharing common purposes, working to a similar type of modelling procedure, while applying

  16. Long-term development of how students interpret a model; Complementarity of contexts and mathematics

    NARCIS (Netherlands)

    Vos, Pauline; Roorda, Gerrit; Stillman, Gloria Ann; Blum, Werner; Kaiser, Gabriele

    2017-01-01

    When students engage in rich mathematical modelling tasks, they have to handle real-world contexts and mathematics in chorus. This is not easy. In this chapter, contexts and mathematics are perceived as complementary, which means they can be integrated. Based on four types of approaches to modelling

  17. Context Dependent Effects of Chimeric Peptide Morpholino Conjugates Contribute to Dystrophin Exon-skipping Efficiency

    Directory of Open Access Journals (Sweden)

    HaiFang Yin

    2013-01-01

    Full Text Available We have recently reported that cell-penetrating peptides (CPPs and novel chimeric peptides containing CPP (referred as B peptide and muscle-targeting peptide (referred as MSP motifs significantly improve the systemic exon-skipping activity of morpholino phosphorodiamidate oligomers (PMOs in dystrophin-deficient mdx mice. In the present study, the general mechanistic significance of the chimeric peptide configuration on the activity and tissue uptake of peptide conjugated PMOs in vivo was investigated. Four additional chimeric peptide-PMO conjugates including newly identified peptide 9 (B-9-PMO and 9-B-PMO and control peptide 3 (B-3-PMO and 3-B-PMO were tested in mdx mice. Immunohistochemical staining, RT-PCR and western blot results indicated that B-9-PMO induced significantly higher level of exon skipping and dystrophin restoration than its counterpart (9-B-PMO, further corroborating the notion that the activity of chimeric peptide-PMO conjugates is dependent on relative position of the tissue-targeting peptide motif within the chimeric peptide with respect to PMOs. Subsequent mechanistic studies showed that enhanced cellular uptake of B-MSP-PMO into muscle cells leads to increased exon-skipping activity in comparison with MSP-B-PMO. Surprisingly, further evidence showed that the uptake of chimeric peptide-PMO conjugates of both orientations (B-MSP-PMO and MSP-B-PMO was ATP- and temperature-dependent and also partially mediated by heparan sulfate proteoglycans (HSPG, indicating that endocytosis is likely the main uptake pathway for both chimeric peptide-PMO conjugates. Collectively, our data demonstrate that peptide orientation in chimeric peptides is an important parameter that determines cellular uptake and activity when conjugated directly to oligonucleotides. These observations provide insight into the design of improved cell targeting compounds for future therapeutics studies.

  18. Dynamic learning and context-dependence in sequential, attribute-based, stated-preference valuation questions

    Science.gov (United States)

    Thomas P. Holmes; Kevin J. Boyle

    2005-01-01

    A hybrid stated-preference model is presented that combines the referendum contingent valuation response format with an experimentally designed set of attributes. A sequence of valuation questions is asked to a random sample in a mailout mail-back format. Econometric analysis shows greater discrimination between alternatives in the final choice in the sequence, and the...

  19. A unified model for context-based behavioural modelling and classification

    CSIR Research Space (South Africa)

    Dabrowski, JJ

    2015-11-01

    Full Text Available for Context-Based Behavioural Modelling and Classification Joel Janek Dabrowskia,∗, Johan Pieter de Villiersb,a,∗∗ aDepartment of Electrical, Electronic and Computer Engineering, University of Pretoria, 2 Lynnwood Rd, Pretoria, South Africa b... consists of tracked location data, ocean conditions, weather conditions, time of day, season of year, regional location data and vessel class ground truth. Each vessel in an environment is classified as either a pirate, transport or fishing vessel...

  20. The spin dependent odderon in the diquark model

    Energy Technology Data Exchange (ETDEWEB)

    Szymanowski, Lech [National Centre for Nuclear Research (NCBJ), Warsaw (Poland); Zhou, Jian, E-mail: jzhou@sdu.edu.cn [School of Physics, & Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan, Shandong 250100 (China); Nikhef and Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, NL-1081 HV Amsterdam (Netherlands)

    2016-09-10

    In this short note, we report a di-quark model calculation for the spin dependent odderon and demonstrate that the asymmetrical color source distribution in the transverse plane of a transversely polarized hadron plays an essential role in yielding the spin dependent odderon. This calculation confirms the earlier finding that the spin dependent odderon is closely related to the parton orbital angular momentum.

  1. Experimental Measurement, Analysis and Modelling of Dependency ...

    African Journals Online (AJOL)

    We propose a direct method of measurement of the total emissivity of opaque samples on a range of temperature around the ambient one. The method rests on the modulation of the temperature of the sample and the infra-red signal processing resulting from the surface of the sample we model the total emissivity obtained ...

  2. Context-dependent interpretation of the prognostic value of BRAF and KRAS mutations in colorectal cancer

    International Nuclear Information System (INIS)

    Popovici, Vlad; Budinska, Eva; Bosman, Fred T; Tejpar, Sabine; Roth, Arnaud D; Delorenzi, Mauro

    2013-01-01

    The mutation status of the BRAF and KRAS genes has been proposed as prognostic biomarker in colorectal cancer. Of them, only the BRAF V600E mutation has been validated independently as prognostic for overall survival and survival after relapse, while the prognostic value of KRAS mutation is still unclear. We investigated the prognostic value of BRAF and KRAS mutations in various contexts defined by stratifications of the patient population. We retrospectively analyzed a cohort of patients with stage II and III colorectal cancer from the PETACC-3 clinical trial (N = 1,423), by assessing the prognostic value of the BRAF and KRAS mutations in subpopulations defined by all possible combinations of the following clinico-pathological variables: T stage, N stage, tumor site, tumor grade and microsatellite instability status. In each such subpopulation, the prognostic value was assessed by log rank test for three endpoints: overall survival, relapse-free survival, and survival after relapse. The significance level was set to 0.01 for Bonferroni-adjusted p-values, and a second threshold for a trend towards statistical significance was set at 0.05 for unadjusted p-values. The significance of the interactions was tested by Wald test, with significance level of 0.05. In stage II-III colorectal cancer, BRAF mutation was confirmed a marker of poor survival only in subpopulations involving microsatellite stable and left-sided tumors, with higher effects than in the whole population. There was no evidence for prognostic value in microsatellite instable or right-sided tumor groups. We found that BRAF was also prognostic for relapse-free survival in some subpopulations. We found no evidence that KRAS mutations had prognostic value, although a trend was observed in some stratifications. We also show evidence of heterogeneity in survival of patients with BRAF V600E mutation. The BRAF mutation represents an additional risk factor only in some subpopulations of colorectal cancers, in

  3. An integrated developmental model for studying identity content in context.

    Science.gov (United States)

    Galliher, Renee V; McLean, Kate C; Syed, Moin

    2017-11-01

    Historically, identity researchers have placed greater emphasis on processes of identity development (how people develop their identities) and less on the content of identity (what the identity is). The relative neglect of identity content may reflect the lack of a comprehensive framework to guide research. In this article, we provide such a comprehensive framework for the study of the content of identity, including 4 levels of analysis. At the broadest level, we situate individual identity within historical, cultural, and political contexts, elaborating on identity development within the context of shifting cultural norms, values, and attitudes. Histories of prejudice and discrimination are relevant in shaping intersections among historically marginalized identities. Second, we examine social roles as unique and central contexts for identity development, such that relationship labels become integrated into a larger identity constellation. Third, domains of individual or personal identity content intersect to yield a sense of self in which various aspects are subjectively experienced as an integrated whole. We explore the negotiation of culturally marginalized and dominant identity labels, as well as idiosyncratic aspects of identities based on unique characteristics or group memberships. Finally, we argue that the content of identity is enacted at the level of everyday interactions, the "micro-level" of identity. The concepts of identity conflict, coherence, and compartmentalization are presented as strategies used to navigate identity content across these 4 levels. This framework serves as an organizing tool for the current literature, as well as for designing future studies on the identity development. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  4. The dependence of Germany on Russian gas: analysis and prospects in the context of the current Ukrainian crisis

    Directory of Open Access Journals (Sweden)

    Miriam Solera Ureña

    2015-12-01

    Full Text Available Germany and Russia share a strong economic interdependence, Germany being presently the largest importer of Russian gas. At the time of writing, the on-going conflict between Ukraine and Russia, compounded with economic sanctions imposed on Russia by the European Union, has raised concerns about Russia as a reliable gas supplier. This article analyses Germany’s dependence on Russian gas within the present economic and political contexts and assesses a the most plausible course of action of German energy policy, taking into account Germany’s current role as a gas transit country; and b the impact of the present context on the shaping of Germany’s foreign policy towards Russia. It is concluded that energy policy measures will not enable drastic reductions in Germany’s dependence on Russian gas in the short term and, moreover, that no abrupt change of direction in German foreign policy towards Russia is to be expected.

  5. Time-dependent intranuclear cascade model

    International Nuclear Information System (INIS)

    Barashenkov, V.S.; Kostenko, B.F.; Zadorogny, A.M.

    1980-01-01

    An intranuclear cascade model with explicit consideration of the time coordinate in the Monte Carlo simulation of the development of a cascade particle shower has been considered. Calculations have been performed using a diffuse nuclear boundary without any step approximation of the density distribution. Changes in the properties of the target nucleus during the cascade development have been taken into account. The results of these calculations have been compared with experiment and with the data which had been obtained by means of a time-independent cascade model. The consideration of time improved agreement between experiment and theory particularly for high-energy shower particles; however, for low-energy cascade particles (with grey and black tracks in photoemulsion) a discrepancy remains at T >= 10 GeV. (orig.)

  6. Implicit Valuation of the Near-Miss is Dependent on Outcome Context.

    Science.gov (United States)

    Banks, Parker J; Tata, Matthew S; Bennett, Patrick J; Sekuler, Allison B; Gruber, Aaron J

    2018-03-01

    Gambling studies have described a "near-miss effect" wherein the experience of almost winning increases gambling persistence. The near-miss has been proposed to inflate the value of preceding actions through its perceptual similarity to wins. We demonstrate here, however, that it acts as a conditioned stimulus to positively or negatively influence valuation, dependent on reward expectation and cognitive engagement. When subjects are asked to choose between two simulated slot machines, near-misses increase valuation of machines with a low payout rate, whereas they decrease valuation of high payout machines. This contextual effect impairs decisions and persists regardless of manipulations to outcome feedback or financial incentive provided for good performance. It is consistent with proposals that near-misses cause frustration when wins are expected, and we propose that it increases choice stochasticity and overrides avoidance of low-valued options. Intriguingly, the near-miss effect disappears when subjects are required to explicitly value machines by placing bets, rather than choosing between them. We propose that this task increases cognitive engagement and recruits participation of brain regions involved in cognitive processing, causing inhibition of otherwise dominant systems of decision-making. Our results reveal that only implicit, rather than explicit strategies of decision-making are affected by near-misses, and that the brain can fluidly shift between these strategies according to task demands.

  7. Wood-based bioenergy in western Montana: the importance of understanding path dependence and local context for resilience

    Directory of Open Access Journals (Sweden)

    Tyler A. Beeton

    2017-06-01

    Full Text Available The use of biomass for wood-based bioenergy (WBB has been argued as a mechanism to mitigate the impacts of climate change, reduce vulnerability to disturbance events such as fires, and to enhance rural socioeconomic development. Yet, WBB development is characterized by a multitude of feedstock sources, bioenergy pathways, scales, and end uses, the feasibility of which is contingent upon place-based and context-specific social and environmental factors. We present an exploratory case study that draws on key informant interviews among a cohort of diverse stakeholders in rural western Montana forest communities, which was informed by a social-ecological systems framework and resilience thinking from a social science lens. The purpose of this paper is the following: (a to document the ways in which key informants define the opportunities and constraints associated with WBB in local contexts; and (b to understand how, and under what contexts, WBB can contribute to forest and community resilience under change. Interviews were analyzed using a modified grounded theory approach, and supplemented by document analysis. Results illustrate the ways in which historical contingencies (i.e., path dependence, individual and group values, and social context can affect the capacity to implement WBB projects. Results also help identify multiple perspectives and trade-offs, which can provide a step toward identifying the most desirable and plausible options for WBB development. As such, these lessons can be used as a starting point to help determine WBB development pathways that contribute to the social and ecological resilience of local places and people under change.

  8. Systems dependability assessment

    CERN Document Server

    Aubry, Jean-François

    2015-01-01

    Presents recent developments of probabilistic assessment of systems dependability based on stochastic models, including graph theory, finite state automaton and language theory, for both dynamic and hybrid contexts.

  9. A random energy model for size dependence : recurrence vs. transience

    NARCIS (Netherlands)

    Külske, Christof

    1998-01-01

    We investigate the size dependence of disordered spin models having an infinite number of Gibbs measures in the framework of a simplified 'random energy model for size dependence'. We introduce two versions (involving either independent random walks or branching processes), that can be seen as

  10. Stability analysis for a general age-dependent vaccination model

    International Nuclear Information System (INIS)

    El Doma, M.

    1995-05-01

    An SIR epidemic model of a general age-dependent vaccination model is investigated when the fertility, mortality and removal rates depends on age. We give threshold criteria of the existence of equilibriums and perform stability analysis. Furthermore a critical vaccination coverage that is sufficient to eradicate the disease is determined. (author). 12 refs

  11. Modelling continuing professional development in an innovative context

    DEFF Research Database (Denmark)

    Fink, Flemming K.

    2001-01-01

    subject to very fast innovation processes. Continuing Professional Development of engineering staff is therefore very important. A model for the continuing education process will be described. The elements of the model and their interaction will be discussed. Part of the modelling is based on interviews...

  12. Context-Dependent Plastic Response during Egg-Laying in a Widespread Newt Species.

    Science.gov (United States)

    Tóth, Zoltán

    2015-01-01

    Previous research on predator-induced phenotypic plasticity mostly focused on responses in morphology, developmental time and/or behaviour during early life stages, but the potential significance of anticipatory parental responses has been investigated less often. In this study I examined behavioural and maternal responses of gravid female smooth newts, Lissotriton vulgaris, in the presence of chemical cues originating from invertebrate predators, Acilius sulcatus water beetles and Aeshna cyanea dragonfly larvae. More specifically, I tested the extent of oviposition preference, plasticity in egg-wrapping behaviour and plasticity in egg size when females had the possibility to lay eggs at oviposition sites with and without predator cues during overnight trials. I found that individuals did not avoid laying eggs in the environment with predator cues; however, individuals that deposited eggs into both environments adjusted the size of the laid eggs to the perceived environment. Females deposited larger eggs earlier in the season but egg size decreased with time in the absence of predator cues, whereas individuals laid eggs of average size throughout the investigated reproductive period when such cues were present. Also, egg size was found to be positively related to hatching success. Individuals did not adjust their wrapping behaviour to the presence of predator cues, but females differed in the extent of egg-wrapping between ponds. Females' body mass and tail depth were also different between ponds, whereas their body size was positively associated with egg size. According to these results, female smooth newts have the potential to exhibit activational plasticity and invest differently into eggs depending on temporal and environmental factors. Such an anticipatory response may contribute to the success of this caudate species under a wide range of predator regimes at its natural breeding habitats.

  13. Context-Dependent Plastic Response during Egg-Laying in a Widespread Newt Species.

    Directory of Open Access Journals (Sweden)

    Zoltán Tóth

    Full Text Available Previous research on predator-induced phenotypic plasticity mostly focused on responses in morphology, developmental time and/or behaviour during early life stages, but the potential significance of anticipatory parental responses has been investigated less often. In this study I examined behavioural and maternal responses of gravid female smooth newts, Lissotriton vulgaris, in the presence of chemical cues originating from invertebrate predators, Acilius sulcatus water beetles and Aeshna cyanea dragonfly larvae. More specifically, I tested the extent of oviposition preference, plasticity in egg-wrapping behaviour and plasticity in egg size when females had the possibility to lay eggs at oviposition sites with and without predator cues during overnight trials. I found that individuals did not avoid laying eggs in the environment with predator cues; however, individuals that deposited eggs into both environments adjusted the size of the laid eggs to the perceived environment. Females deposited larger eggs earlier in the season but egg size decreased with time in the absence of predator cues, whereas individuals laid eggs of average size throughout the investigated reproductive period when such cues were present. Also, egg size was found to be positively related to hatching success. Individuals did not adjust their wrapping behaviour to the presence of predator cues, but females differed in the extent of egg-wrapping between ponds. Females' body mass and tail depth were also different between ponds, whereas their body size was positively associated with egg size. According to these results, female smooth newts have the potential to exhibit activational plasticity and invest differently into eggs depending on temporal and environmental factors. Such an anticipatory response may contribute to the success of this caudate species under a wide range of predator regimes at its natural breeding habitats.

  14. MODELING PRECIPITATION DEPENDENT FOREST RESILIENCE IN INDIA

    Directory of Open Access Journals (Sweden)

    P. Das

    2018-04-01

    Full Text Available The impact of long term climate change that imparts stress on forest could be perceived by studying the regime shift of forest ecosystem. With the change of significant precipitation, forest may go through density change around globe at different spatial and temporal scale. The 100 class high resolution (60 meter spatial resolution Indian vegetation type map was used in this study recoded into four broad categories depending on phrenology as (i forest, (ii scrubland, (iii grassland and (iv treeless area. The percentage occupancy of forest, scrub, grass and treeless were observed as 19.9 %, 5.05 %, 1.89 % and 7.79 % respectively. Rest of the 65.37 % land area was occupied by the cropland, built-up, water body and snow covers. The majority forest cover were appended into a 5 km × 5 km grid, along with the mean annual precipitation taken from Bioclim data. The binary presence and absence of different vegetation categories in relates to the annual precipitation was analyzed to calculate their resilience expressed in probability values ranging from 0 to 1. Forest cover observed having resilience probability (Pr < 0.3 in only 0.3 % (200 km2 of total forest cover in India, which was 4.3 % < 0.5 Pr. Majority of the scrubs and grass (64.92 % Pr < 0.5 from North East India which were the shifting cultivation lands showing low resilience, having their high tendency to be transform to forest. These results have spatial explicitness to highlight the resilient and non-resilient distribution of forest, scrub and grass, and treeless areas in India.

  15. On the context dependency of implicit self-esteem in social anxiety disorder.

    Science.gov (United States)

    Hiller, Thomas S; Steffens, Melanie C; Ritter, Viktoria; Stangier, Ulrich

    2017-12-01

    Cognitive models assume that negative self-evaluations are automatically activated in individuals with Social Anxiety Disorder (SAD) during social situations, increasing their individual level of anxiety. This study examined automatic self-evaluations (i.e., implicit self-esteem) and state anxiety in a group of individuals with SAD (n = 45) and a non-clinical comparison group (NC; n = 46). Participants were randomly assigned to either a speech condition with social threat induction (giving an impromptu speech) or to a no-speech condition without social threat induction. We measured implicit self-esteem with an Implicit Association Test (IAT). Implicit self-esteem differed significantly between SAD and NC groups under the speech condition but not under the no-speech condition. The SAD group showed lower implicit self-esteem than the NC group under the speech-condition. State anxiety was significantly higher under the speech condition than under the no-speech condition in the SAD group but not in the NC group. Mediation analyses supported the idea that for the SAD group, the effect of experimental condition on state anxiety was mediated by implicit self-esteem. The causal relation between implicit self-esteem and state anxiety could not be determined. The findings corroborate hypotheses derived from cognitive models of SAD: Automatic self-evaluations were negatively biased in individuals with SAD facing social threat and showed an inverse relationship to levels of state anxiety. However, automatic self-evaluations in individuals with SAD can be unbiased (similar to NC) in situations without social threat. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Dorsoventral and Proximodistal Hippocampal Processing Account for the Influences of Sleep and Context on Memory (Reconsolidation: A Connectionist Model

    Directory of Open Access Journals (Sweden)

    Justin Lines

    2017-01-01

    Full Text Available The context in which learning occurs is sufficient to reconsolidate stored memories and neuronal reactivation may be crucial to memory consolidation during sleep. The mechanisms of context-dependent and sleep-dependent memory (reconsolidation are unknown but involve the hippocampus. We simulated memory (reconsolidation using a connectionist model of the hippocampus that explicitly accounted for its dorsoventral organization and for CA1 proximodistal processing. Replicating human and rodent (reconsolidation studies yielded the following results. (1 Semantic overlap between memory items and extraneous learning was necessary to explain experimental data and depended crucially on the recurrent networks of dorsal but not ventral CA3. (2 Stimulus-free, sleep-induced internal reactivations of memory patterns produced heterogeneous recruitment of memory items and protected memories from subsequent interference. These simulations further suggested that the decrease in memory resilience when subjects were not allowed to sleep following learning was primarily due to extraneous learning. (3 Partial exposure to the learning context during simulated sleep (i.e., targeted memory reactivation uniformly increased memory item reactivation and enhanced subsequent recall. Altogether, these results show that the dorsoventral and proximodistal organization of the hippocampus may be important components of the neural mechanisms for context-based and sleep-based memory (reconsolidations.

  17. Cosmological implication of massive neutrinos in a horizontal model context

    International Nuclear Information System (INIS)

    Goldman, C.

    1985-04-01

    An extended version of the Glashow-Weinberg-Salam model for the eletroweak interactions is studied in detail. It has an extra global horizontal symmetry, which allows the appearance of neutrino mass terms. The constraints imposed by the standard cosmological model were used to determine the allowed range of variations of the free parameters of this model. As applications, the solar neutrinos problem and the formation of large scale structures in the universe is studied. (Author) [pt

  18. The Fusion Model of Multidomain Context Information for the Internet of Things

    Directory of Open Access Journals (Sweden)

    Bing Jia

    2017-01-01

    Full Text Available The Internet of Things aims to provide the user with deep adaptive intelligence services according to the user’s personalized characteristics. Most of the characteristics are presented in the form of high-level context. But it often lacks methods to obtain high-level context information directly in the Internet of Things. In this paper, so as to achieve the corresponding high-level context information using the specific low-level multidomain context directly obtained by different sensors in the Internet of Things, we present a machine learning method to construct a context fusion model based on the feature selection algorithm and the multiclassification algorithm. First, we propose a wrapper feature selection method based on the genetic algorithm to obtain a simpler and more important subset of the context features from the low-level multidomain context, by defining a suitable fitness function and a convergence condition. Then, we use the decision tree algorithm which is a multiclassification algorithm, based on the rules obtained by training the subset of context features, to determine which high-level context the record set of the low-level context information belongs to. Experiments confirm that the model can be used to achieve higher classification accuracy without more significant time consumption.

  19. Service quality measurement in the internet context: A proposed model

    OpenAIRE

    Albassam, T; Alshawi, S

    2010-01-01

    The survival of any organisation in a highly competitive environment depends on its ability to provide the best service quality to its existing customers as the quality of service is a key factor in the success of any organisation. It is well established that the measurement of service quality is an important procedure for the improvement of the success and performance of any organisation. Facts indicate that more attention is needed toward developing an industry-specific scale for measuring ...

  20. Meaning in Context

    DEFF Research Database (Denmark)

    Christiansen, Henning; Dahl, Veronica

    2005-01-01

    A model for context-dependent natural language semantics is proposed and formalized in terms of possible worlds. The meaning of a sentence depends on context and at the same time affects that context representing the knowledge about the world collected from a discourse. The model fits well...... representations. There is a natural correspondence between the possible world semantics and a constraint solver, and it is shown how such a semantics can be defined using the programming language of Constraint Handling Rules (Frühwirth, 1995). Discourse analysis is clearly a process of abduction in this framework...

  1. Managing changes in the enterprise architecture modelling context

    Science.gov (United States)

    Khanh Dam, Hoa; Lê, Lam-Son; Ghose, Aditya

    2016-07-01

    Enterprise architecture (EA) models the whole enterprise in various aspects regarding both business processes and information technology resources. As the organisation grows, the architecture of its systems and processes must also evolve to meet the demands of the business environment. Evolving an EA model may involve making changes to various components across different levels of the EA. As a result, an important issue before making a change to an EA model is assessing the ripple effect of the change, i.e. change impact analysis. Another critical issue is change propagation: given a set of primary changes that have been made to the EA model, what additional secondary changes are needed to maintain consistency across multiple levels of the EA. There has been however limited work on supporting the maintenance and evolution of EA models. This article proposes an EA description language, namely ChangeAwareHierarchicalEA, integrated with an evolution framework to support both change impact analysis and change propagation within an EA model. The core part of our framework is a technique for computing the impact of a change and a new method for generating interactive repair plans from Alloy consistency rules that constrain the EA model.

  2. Modelling continuing professional development in an innovative context

    DEFF Research Database (Denmark)

    Fink, Flemming K.

    2001-01-01

    Being one step ahead of your competitors with incorporation of new knowledge in the products puts focus on the importance of human resources as a significant resource for industrial development. A major competitive parameter in knowledge society is engineering competence, especially in the industry...... subject to very fast innovation processes. Continuing Professional Development of engineering staff is therefore very important. A model for the continuing education process will be described. The elements of the model and their interaction will be discussed. Part of the modelling is based on interviews...

  3. Model dependence of isospin sensitive observables at high densities

    International Nuclear Information System (INIS)

    Guo, Wen-Mei; Yong, Gao-Chan; Wang, Yongjia; Li, Qingfeng; Zhang, Hongfei; Zuo, Wei

    2013-01-01

    Within two different frameworks of isospin-dependent transport model, i.e., Boltzmann–Uehling–Uhlenbeck (IBUU04) and Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport models, sensitive probes of nuclear symmetry energy are simulated and compared. It is shown that neutron to proton ratio of free nucleons, π − /π + ratio as well as isospin-sensitive transverse and elliptic flows given by the two transport models with their “best settings”, all have obvious differences. Discrepancy of numerical value of isospin-sensitive n/p ratio of free nucleon from the two models mainly originates from different symmetry potentials used and discrepancies of numerical value of charged π − /π + ratio and isospin-sensitive flows mainly originate from different isospin-dependent nucleon–nucleon cross sections. These demonstrations call for more detailed studies on the model inputs (i.e., the density- and momentum-dependent symmetry potential and the isospin-dependent nucleon–nucleon cross section in medium) of isospin-dependent transport model used. The studies of model dependence of isospin sensitive observables can help nuclear physicists to pin down the density dependence of nuclear symmetry energy through comparison between experiments and theoretical simulations scientifically

  4. Spreadsheet-Enhanced Problem Solving in Context as Modeling

    Directory of Open Access Journals (Sweden)

    Sergei Abramovich

    2003-07-01

    development through situated mathematical problem solving. Modeling activities described in this paper support the epistemological position regarding the interplay that exists between the development of mathematical concepts and available methods of calculation. The spreadsheet used is Microsoft Excel 2001

  5. Contexts for concepts: Information modeling for semantic interoperability

    NARCIS (Netherlands)

    Oude Luttighuis, P.H.W.M.; Stap, R.E.; Quartel, D.

    2011-01-01

    Conceptual information modeling is a well-established practice, aimed at preparing the implementation of information systems, the specification of electronic message formats, and the design of information processes. Today's ever more connected world however poses new challenges for conceptual

  6. Business model transformation process in the context of business ecosystem

    OpenAIRE

    Heikkinen, A.-M. (Anne-Mari)

    2014-01-01

    Abstract It is current phenomena that business environment has changed and has set new requirements for companies. Companies must adapt to the changes comes from outside its normal business environment and take into consideration wider business environment where it operates. These changes also have set new demands for company business model. Companies Business models need to be changed to match state of art business environ...

  7. School Burnout and Engagement in the Context of Demands-Resources Model

    Science.gov (United States)

    Salmela-Aro, Katariina; Upadyaya, Katja

    2014-01-01

    Background: A four-wave longitudinal study tested the demands-resources model in the school context. Aim: To examine the applicability of the demands-resources to the school context. Method: Data of 1,709 adolescents were gathered, once during the transition from comprehensive to post-comprehensive education, twice during post-comprehensive…

  8. Incorporating Pass-Phrase Dependent Background Models for Text-Dependent Speaker verification

    DEFF Research Database (Denmark)

    Sarkar, Achintya Kumar; Tan, Zheng-Hua

    2018-01-01

    is compared to conventional text-independent background model based TD-SV systems using either Gaussian mixture model (GMM)-universal background model (UBM) or Hidden Markov model (HMM)-UBM or i-vector paradigms. In addition, we consider two approaches to build PBMs: speaker-independent and speaker......In this paper, we propose pass-phrase dependent background models (PBMs) for text-dependent (TD) speaker verification (SV) to integrate the pass-phrase identification process into the conventional TD-SV system, where a PBM is derived from a text-independent background model through adaptation using...... and the selected PBM is then used for the log likelihood ratio (LLR) calculation with respect to the claimant model. The proposed method incorporates the pass-phrase identification step in the LLR calculation, which is not considered in conventional standalone TD-SV systems. The performance of the proposed method...

  9. Individual differences in context-dependent effects reveal common mechanisms underlying the direction aftereffect and direction repulsion.

    Science.gov (United States)

    McGovern, David P; Walsh, Kevin S; Bell, Jason; Newell, Fiona N

    2017-12-01

    Both spatial and temporal context influence our perception of visual stimuli. For instance, both nearby moving stimuli and recently viewed motion can lead to biases in the perceived direction of a moving stimulus. Due to similarities in the spatial tuning properties of these spatial and temporal context-dependent effects, it is often assumed that they share a functional goal in motion processing and arise from common neural mechanisms. However, the psychophysical evidence concerning this assumption is inconsistent. Here we used an individual differences approach to examine the relationship between different effects of contextual modulation on perception. We reasoned that if measures of contextual modulation share a common underlying mechanism, they should exhibit a strong positive correlation across participants. To test this hypothesis, estimates of the direction aftereffect, direction repulsion, the tilt aftereffect and contrast adaptation were obtained from 54 healthy participants. Our results show pronounced interindividual differences in the effect sizes of all four tasks. Furthermore, there was a strong positive correlation between the estimates of the direction aftereffect and direction repulsion. This correlation was also evident in the threshold elevations that accompanied these repulsive biases in perceived direction. While the effects of contrast adaptation did not correlate with any of the other tasks, there was a weak, but non-significant, correlation between the direction and tilt aftereffects. These results provide evidence for common mechanisms underlying the direction aftereffect and direction repulsion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Modeling spatial processes with unknown extremal dependence class

    KAUST Repository

    Huser, Raphaël G.

    2017-03-17

    Many environmental processes exhibit weakening spatial dependence as events become more extreme. Well-known limiting models, such as max-stable or generalized Pareto processes, cannot capture this, which can lead to a preference for models that exhibit a property known as asymptotic independence. However, weakening dependence does not automatically imply asymptotic independence, and whether the process is truly asymptotically (in)dependent is usually far from clear. The distinction is key as it can have a large impact upon extrapolation, i.e., the estimated probabilities of events more extreme than those observed. In this work, we present a single spatial model that is able to capture both dependence classes in a parsimonious manner, and with a smooth transition between the two cases. The model covers a wide range of possibilities from asymptotic independence through to complete dependence, and permits weakening dependence of extremes even under asymptotic dependence. Censored likelihood-based inference for the implied copula is feasible in moderate dimensions due to closed-form margins. The model is applied to oceanographic datasets with ambiguous true limiting dependence structure.

  11. Students’ Involvement in Authentic Modelling Practices as Contexts in Chemistry Education

    NARCIS (Netherlands)

    Prins, G.T.; Bulte, A.M.W.; van Driel, J.H.; Pilot, A.

    2009-01-01

    In science education students should come to understand the nature and significance of models. A promising strategy to achieve this goal is using authentic modelling practices as contexts for meaningful learning of models and modelling. An authentic practice is defined as professionals working with

  12. Continuum modeling of rate-dependent granular flows in SPH

    Science.gov (United States)

    Hurley, Ryan C.; Andrade, José E.

    2017-01-01

    We discuss a constitutive law for modeling rate-dependent granular flows that has been implemented in smoothed particle hydrodynamics (SPH). We model granular materials using a viscoplastic constitutive law that produces a Drucker-Prager-like yield condition in the limit of vanishing flow. A friction law for non-steady flows, incorporating rate-dependence and dilation, is derived and implemented within the constitutive law. We compare our SPH simulations with experimental data, demonstrating that they can capture both steady and non-steady dynamic flow behavior, notably including transient column collapse profiles. This technique may therefore be attractive for modeling the time-dependent evolution of natural and industrial flows.

  13. Modelling challenges in context: Lessons from malaria, HIV, and tuberculosis

    Directory of Open Access Journals (Sweden)

    Lauren M. Childs

    2015-03-01

    Full Text Available Malaria, HIV, and tuberculosis (TB collectively account for several million deaths each year, with all three ranking among the top ten killers in low-income countries. Despite being caused by very different organisms, malaria, HIV, and TB present a suite of challenges for mathematical modellers that are particularly pronounced in these infections, but represent general problems in infectious disease modelling, and highlight many of the challenges described throughout this issue. Here, we describe some of the unifying challenges that arise in modelling malaria, HIV, and TB, including variation in dynamics within the host, diversity in the pathogen, and heterogeneity in human contact networks and behaviour. Through the lens of these three pathogens, we provide specific examples of the other challenges in this issue and discuss their implications for informing public health efforts.

  14. Parameter dependence and outcome dependence in dynamical models for state vector reduction

    International Nuclear Information System (INIS)

    Ghirardi, G.C.; Grassi, R.; Butterfield, J.; Fleming, G.N.

    1993-01-01

    The authors apply the distinction between parameter independence and outcome independence to the linear and nonlinear models of a recent nonrelativistic theory of continuous state vector reduction. It is shown that in the nonlinear model there is a set of realizations of the stochastic process that drives the state vector reduction for which parameter independence is violated for parallel spin components in the EPR-Bohm setup. Such a set has an appreciable probability of occurrence (∼ 1/2). On the other hand, the linear model exhibits only extremely small parameter dependence effects. Some specific features of the models are investigated and it is recalled that, as has been pointed out recently, to be able to speak of definite outcomes (or equivalently of possessed objective elements of reality) at finite times, the criteria for their attribution to physical systems must be slightly changed. The concluding section is devoted to a detailed discussion of the difficulties met when attempting to take, as a starting point for the formulation of a relativistic theory, a nonrelativistic scheme which exhibits parameter dependence. Here the authors derive a theorem which identifies the precise sense in which the occurrence of parameter dependence forbids a genuinely relativistic generalization. Finally, the authors show how the appreciable parameter dependence of the nonlinear model gives rise to problems with relativity, while the extremely weak parameter dependence of the linear model does not give rise to any difficulty, provided the appropriate criteria for the attribution of definite outcomes are taken into account. 19 refs

  15. Context Dependent Spectral Unmixing

    Science.gov (United States)

    2014-08-01

    remote sensing [1–13]. It is also used in food safety [14–17], pharmaceutical process monitoring and quality control [18–22], as well as in biomedical...23,24], industrial [25], biometric [26] and forensic applications [27]. Hyperspectral sensors capture both the spatial and spectral information of a...imagery,” IEEE Signal Processing Magazine, vol. 19, no. 1, pp. 58–69, 2002. [12] A. Plaza, J. A. Benediktsson, J. W. Boardman, J. Brazile , L. Bruzzone, G

  16. Context-dependent cheating

    DEFF Research Database (Denmark)

    Pascual‐Ezama, David; Fosgaard, Toke Reinholt; Cardenas, Juan-Camilo

    2015-01-01

    participants. We employ a very simple task where participants face a trade-off between the joy of eating a fine chocolate and the disutility of having a threatened self-concept because of lying. Despite the incentives to cheat, we find that individuals are mostly honest. Further, international indices...

  17. Annotation-Based Learner's Personality Modeling in Distance Learning Context

    Science.gov (United States)

    Omheni, Nizar; Kalboussi, Anis; Mazhoud, Omar; Kacem, Ahmed Hadj

    2016-01-01

    Researchers in distance education are interested in observing and modeling learners' personality profiles, and adapting their learning experiences accordingly. When learners read and interact with their reading materials, they do unselfconscious activities like annotation which may be key feature of their personalities. Annotation activity…

  18. Professionals in Context: How Robust Is the Normative Model?

    NARCIS (Netherlands)

    Röling, N.G.

    2009-01-01

    Research on successful change often leads to a normative model. What was an empirical outcome becomes a prescription for action. In water management, research on platforms for decision-making, multi-stakeholder processes, social learning, and participatory interventions seems to have made this step

  19. Building Context with Tumor Growth Modeling Projects in Differential Equations

    Science.gov (United States)

    Beier, Julie C.; Gevertz, Jana L.; Howard, Keith E.

    2015-01-01

    The use of modeling projects serves to integrate, reinforce, and extend student knowledge. Here we present two projects related to tumor growth appropriate for a first course in differential equations. They illustrate the use of problem-based learning to reinforce and extend course content via a writing or research experience. Here we discuss…

  20. Models of Economic Growth and Development in the Context of ...

    African Journals Online (AJOL)

    The Way Forward for Africa. Lansana Keita* ... to such progress. Key Words: economic growth, economic development, human capital, growth models. Résumé. La littérature économique depuis l'avènement de l'économie moderne a été ..... between the economy's growth rate according to investment and the propensity to ...

  1. Using Structured Knowledge Representation for Context-Sensitive Probabilistic Modeling

    Science.gov (United States)

    2008-01-01

    Morgan Kaufmann, 1988. [24] J. Pearl, Causality: Models, Reasoning, and Inference, Cambridge University Press, 2000. [25] J. Piaget , Piaget’s theory ...Gopnik, C. Glymour, D. M. Sobel, L. E. Schulz, T. Kushnir, D. Danks, A theory of causal learning in children: Causal maps and Bayes nets, Psychological

  2. Process chain modeling and selection in an additive manufacturing context

    DEFF Research Database (Denmark)

    Thompson, Mary Kathryn; Stolfi, Alessandro; Mischkot, Michael

    2016-01-01

    This paper introduces a new two-dimensional approach to modeling manufacturing process chains. This approach is used to consider the role of additive manufacturing technologies in process chains for a part with micro scale features and no internal geometry. It is shown that additive manufacturing...... evolving fields like additive manufacturing....

  3. Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya.

    Science.gov (United States)

    Young, Hillary S; McCauley, Douglas J; Dirzo, Rodolfo; Goheen, Jacob R; Agwanda, Bernard; Brook, Cara; Otarola-Castillo, Erik; Ferguson, Adam W; Kinyua, Stephen N; McDonough, Molly M; Palmer, Todd M; Pringle, Robert M; Young, Truman P; Helgen, Kristofer M

    2015-03-01

    Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large-wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife declines on other animals in a community, we examined the effects of three common forms of large-wildlife loss (removal without replacement [using fences], removal followed by replacement with domestic stock, and removal accompanied by crop agricultural use) on small-mammal abundance, diversity, and community composition, in landscapes that varied in several abiotic attributes (rainfall, soil fertility, land-use intensity) in central Kenya. We found that small-mammal communities were indeed heavily impacted by all forms of large-wildlife decline, showing, on average: (1) higher densities, (2) lower species richness per site, and (3) different species assemblages in sites from which large wildlife were removed. However, the nature and magnitude of these effects were strongly context dependent. Rainfall, type of land-use change, and the interaction of these two factors were key predictors of both the magnitude and type of responses of small mammals. The strongest effects, particularly abundance responses, tended to be observed in low-rainfall areas. Whereas isolated wildlife removal primarily led to increased small-mammal abundance, wildlife removal associated with secondary uses (agriculture, domestic stock) had much more variable effects on abundance and stronger impacts on diversity and composition. Collectively, these results (1) highlight the importance of context in determining the impacts of large-wildlife decline on small

  4. Ad-hoc and context-dependent adjustments of selective attention in conflict control: an ERP study with visual probes.

    Science.gov (United States)

    Nigbur, R; Schneider, J; Sommer, W; Dimigen, O; Stürmer, B

    2015-02-15

    Cognitive conflict control in flanker tasks has often been described using the zoom-lens metaphor of selective attention. However, whether and how selective attention - in terms of suppression and enhancement - operates in this context has remained unclear. To examine the dynamic interplay of selective attention and cognitive control we used electrophysiological measures and presented task-irrelevant visual probe stimuli at foveal, parafoveal, and peripheral display positions. Target-flanker congruency varied either randomly from trial to trial (mixed-block) or block-wise (fixed-block) in order to induce reactive versus proactive control modes, respectively. Three EEG measures were used to capture ad-hoc adjustments within trials as well as effects of context-based predictions: the N1 component of the visual evoked potential (VEP) to probes, the VEP to targets, and the conflict-related midfrontal N2 component. Results from probe-VEPs indicate that enhanced processing of the foveal target rather than suppression of the peripheral flankers supports interference control. In incongruent mixed-block trials VEPs were larger to probes near the targets. In the fixed-blocks probe-VEPs were not modulated, but contrary to the mixed-block the preceding target-related VEP was affected by congruency. Results of the control-related N2 reveal largest amplitudes in the unpredictable context, which did not differentiate for stimulus and response incongruency. In contrast, in the predictable context, N2 amplitudes were reduced overall and differentiated between stimulus and response incongruency. Taken together these results imply that predictability alters interference control by a reconfiguration of stimulus processing. During unpredictable sequences participants adjust their attentional focus dynamically on a trial-by-trial basis as reflected in congruency-dependent probe-VEP-modulation. This reactive control mode also elicits larger N2 amplitudes. In contrast, when task demands

  5. Factor copula models for data with spatio-temporal dependence

    KAUST Repository

    Krupskii, Pavel

    2017-10-13

    We propose a new copula model for spatial data that are observed repeatedly in time. The model is based on the assumption that there exists a common factor that affects the measurements of a process in space and in time. Unlike models based on multivariate normality, our model can handle data with tail dependence and asymmetry. The likelihood for the proposed model can be obtained in a simple form and therefore parameter estimation is quite fast. Simulation from this model is straightforward and data can be predicted at any spatial location and time point. We use simulation studies to show different types of dependencies, both in space and in time, that can be generated by this model. We apply the proposed copula model to hourly wind data and compare its performance with some classical models for spatio-temporal data.

  6. Towards a context-aware multi-channel messaging model for African banks: preliminary investigations

    CSIR Research Space (South Africa)

    Salami, O

    2016-05-01

    Full Text Available Technological advancements have provided Banks several means of sending messages to their customers. In the context of business-to-customer interaction, Single Channel Messaging (SCM) model is prominently used by most Banks in Africa. SCM...

  7. An API for Integrating Spatial Context Models with Spatial Reasoning Algorithms

    DEFF Research Database (Denmark)

    Kjærgaard, Mikkel Baun

    2006-01-01

    The integration of context-aware applications with spatial context models is often done using a common query language. However, algorithms that estimate and reason about spatial context information can benefit from a tighter integration. An object-oriented API makes such integration possible...... and can help reduce the complexity of algorithms making them easier to maintain and develop. This paper propose an object-oriented API for context models of the physical environment and extensions to a location modeling approach called geometric space trees for it to provide adequate support for location...... modeling. The utility of the API is evaluated in several real-world cases from an indoor location system, and spans several types of spatial reasoning algorithms....

  8. Stochastic hyperelastic modeling considering dependency of material parameters

    Science.gov (United States)

    Caylak, Ismail; Penner, Eduard; Dridger, Alex; Mahnken, Rolf

    2018-03-01

    This paper investigates the uncertainty of a hyperelastic model by treating random material parameters as stochastic variables. For its stochastic discretization a polynomial chaos expansion (PCE) is used. An important aspect in our work is the consideration of stochastic dependencies in the stochastic modeling of Ogden's material model. To this end, artificial experiments are generated using the auto-regressive moving average process based on real experiments. The parameter identification for all data provides statistics of Ogden's material parameters, which are subsequently used for stochastic modeling. Stochastic dependencies are incorporated into the PCE using a Nataf transformation from dependent distributed random variables to independent standard normal distributed ones. The representative numerical example shows that our proposed method adequately takes into account the stochastic dependencies of Ogden's material parameters.

  9. Model Transformation in context of Driver Assistance System

    OpenAIRE

    Kappattanavar, Abhishek Mallikarjuna

    2016-01-01

    In today’s world we see that Embedded Systems forms a major part in the life of a human being. Almost every device today has an electronic chip embedded in it. When it comes to automotive, these electronic devices are multiplying. This has resulted in innovative methods of developing Embedded Systems. Among them, Model Based Development has become very popular and a standard way of developing embedded systems. Now, we can see that most embedded systems, especially the automotive systems, are ...

  10. Developing a Broadband Adoption Model in the UK Context

    Science.gov (United States)

    Dwivedi, Yogesh K.; Mustafee, Navonil; Williams, Michael D.; Lal, Banita

    This research examines the factors affecting the consumer adoption of broadband in the United Kingdom. A conceptual model of broadband adoption was developed by selecting and justifying a number of relevant constructs from the technology adoption literature. The model was then empirically tested by employing survey data that was randomly collected from 358 UK broadband consumers. The findings suggest that, with the exception of one construct that was included in the conceptual model (namely, knowledge), all of the con structs significantly influence consumers when adopting broadband in a UK household. The significant constructs include relative advantage, utilitarian outcomes, hedonic outcomes, primary influence, facilitating conditions resources, and self-efficacy. Furthermore, when considering the behavioral intention and facilitating conditions resources constructs together, they significantly explain UK broad band adoption behavior. The theoretical contri bution of this research is that it determines and integrates the appropriate constructs from the technology adoption literature in order to enhance the knowledge of technology adoption from the consumer's perspective. This research has implications for policy makers and broadband providers since the results of this study can be exploited by the aforementioned stakeholders in order to encourage and promote the adoption and usage of broadband among the general population.

  11. MOHAWC. Models of human activities in work contexts

    International Nuclear Information System (INIS)

    Brehmer, B.; Andersen, H.B.

    1993-06-01

    The overall objective of the MOHAWC Action is to formulate and extend a unifying framework for cognitive studies of human agents coping with complex work domains. Central issues are methods for analysis and representation of knowledge about complex domains, analysis of cognitive control, mental models and heuristics applied in complex work domains, distributed decision making and forms of cooperative work, the role of tacit knowledge in agents' performance in complex work domains, and cognitive simulation methods for testing models of cognitive performance. The nature of computer mediated work and how such work should be designed and organised to be optimally effective and satisfying is considered. The focus is mainly on various forms of process industry, such as nuclear power and steel production. Dynamic decision making, where the decision-maker has to make a series of interdependent decisions under conditions where the state of the system with which he or she is working changes, both as a consequence of the decision maker's actions and autonomously, and where the decisions must be made in real time is analysed. MOHAWC taxonomy has played a central role as a framework for identifying important research problems and for integrating results. The Risoe team has contributed a major analysis of and illustration of how the MOHAWC taxonomy can be used in the design of interfaces. (AB) (97 refs.)

  12. Wine Traceability: A Data Model and Prototype in Albanian Context.

    Science.gov (United States)

    Vukatana, Kreshnik; Sevrani, Kozeta; Hoxha, Elira

    2016-02-17

    Vine traceability is a critical issue that has gained interest internationally. Quality control programs and schemes are mandatory in many countries including EU members and the USA. Albania has transformed most of the EU regulations on food into laws. Regarding the vine sector, the obligation of wine producers to keep traceability data is part of the legislation. The analysis on the interviews conducted with Albanian winemakers show that these data are actually recorded only in hard copy. Another fact that emerges from the interviews is that only two producers have implemented the ISO (International Organization for Standardization) standards on food. The purpose of this paper is to develop an agile and automated traceability system based on these standards. We propose a data model and system prototype that are described in the second and third section of this work. The data model is an adaption along the lines of the GS1 (Global Standards One) specifications for a wine supply chain. The proposed prototype has a key component that is mobile access to the information about wine through barcode technology. By using this mechanism the consumer obtains transparency on his expectations concerning the quality criteria. Another important component of the proposed system in this paper is a real-time notification module that works as an alert system when a risk is identified. This can help producers and authorities to have a rapid identification of a contaminated product. It is important in cases when recalling the product from the market or preventing it from reaching the consumer.

  13. Operational model evaluation for particulate matter in Europe and North America in the context of AQMEII

    NARCIS (Netherlands)

    Solazzo, E.; Bianconi, R.; Pirovano, G.; Matthias, V.; Vautard, R.; Moran, M.D.; Wyat Appel, K.; Bessagnet, B.; Brandt, J.; Christensen, J.H.; Chemel, C.; Coll, I.; Ferreira, J.; Forkel, R.; Francis, X.V.; Grell, G.; Grossi, P.; Hansen, A.B.; Miranda, A.I.; Nopmongcol, U.; Prank, M.; Sartelet, K.N.; Schaap, M.; Silver, J.D.; Sokhi, R.S.; Vira, J.; Werhahn, J.; Wolke, R.; Yarwood, G.; Zhang, J.; Rao, S.T.; Galmarini, S.

    2012-01-01

    Ten state-of-the-science regional air quality (AQ) modeling systems have been applied to continental-scale domains in North America and Europe for full-year simulations of 2006 in the context of Air Quality Model Evaluation International Initiative (AQMEII), whose main goals are model

  14. Modeling human risk: Cell & molecular biology in context

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    It is anticipated that early in the next century manned missions into outer space will occur, with a mission to Mars scheduled between 2015 and 2020. However, before such missions can be undertaken, a realistic estimation of the potential risks to the flight crews is required. One of the uncertainties remaining in this risk estimation is that posed by the effects of exposure to the radiation environment of outer space. Although the composition of this environment is fairly well understood, the biological effects arising from exposure to it are not. The reasons for this are three-fold: (1) A small but highly significant component of the radiation spectrum in outer space consists of highly charged, high energy (HZE) particles which are not routinely experienced on earth, and for which there are insufficient data on biological effects; (2) Most studies on the biological effects of radiation to date have been high-dose, high dose-rate, whereas in space, with the exception of solar particle events, radiation exposures will be low-dose, low dose-rate; (3) Although it has been established that the virtual absence of gravity in space has a profound effect on human physiology, it is not clear whether these effects will act synergistically with those of radiation exposure. A select panel will evaluate the utilizing experiments and models to accurately predict the risks associated with exposure to HZE particles. Topics of research include cellular and tissue response, health effects associated with radiation damage, model animal systems, and critical markers of Radiation response.

  15. Modeling human risk: Cell ampersand molecular biology in context

    International Nuclear Information System (INIS)

    1997-06-01

    It is anticipated that early in the next century manned missions into outer space will occur, with a mission to Mars scheduled between 2015 and 2020. However, before such missions can be undertaken, a realistic estimation of the potential risks to the flight crews is required. One of the uncertainties remaining in this risk estimation is that posed by the effects of exposure to the radiation environment of outer space. Although the composition of this environment is fairly well understood, the biological effects arising from exposure to it are not. The reasons for this are three-fold: (1) A small but highly significant component of the radiation spectrum in outer space consists of highly charged, high energy (HZE) particles which are not routinely experienced on earth, and for which there are insufficient data on biological effects; (2) Most studies on the biological effects of radiation to date have been high-dose, high dose-rate, whereas in space, with the exception of solar particle events, radiation exposures will be low-dose, low dose-rate; (3) Although it has been established that the virtual absence of gravity in space has a profound effect on human physiology, it is not clear whether these effects will act synergistically with those of radiation exposure. A select panel will evaluate the utilizing experiments and models to accurately predict the risks associated with exposure to HZE particles. Topics of research include cellular and tissue response, health effects associated with radiation damage, model animal systems, and critical markers of Radiation response

  16. Wine Traceability: A Data Model and Prototype in Albanian Context

    Directory of Open Access Journals (Sweden)

    Kreshnik Vukatana

    2016-02-01

    Full Text Available Vine traceability is a critical issue that has gained interest internationally. Quality control programs and schemes are mandatory in many countries including EU members and the USA. Albania has transformed most of the EU regulations on food into laws. Regarding the vine sector, the obligation of wine producers to keep traceability data is part of the legislation. The analysis on the interviews conducted with Albanian winemakers show that these data are actually recorded only in hard copy. Another fact that emerges from the interviews is that only two producers have implemented the ISO (International Organization for Standardization standards on food. The purpose of this paper is to develop an agile and automated traceability system based on these standards. We propose a data model and system prototype that are described in the second and third section of this work. The data model is an adaption along the lines of the GS1 (Global Standards One specifications for a wine supply chain. The proposed prototype has a key component that is mobile access to the information about wine through barcode technology. By using this mechanism the consumer obtains transparency on his expectations concerning the quality criteria. Another important component of the proposed system in this paper is a real-time notification module that works as an alert system when a risk is identified. This can help producers and authorities to have a rapid identification of a contaminated product. It is important in cases when recalling the product from the market or preventing it from reaching the consumer.

  17. Context-dependent responses to novelty in Rainbow trout (Oncorhynchus mykiss), selected for high and low post-stress cortisol responsiveness

    DEFF Research Database (Denmark)

    Basic, D.; Winberg, S.; Schjolden, J.

    2012-01-01

    in challenging situations than the LR counterpart. The present study addressed whether such variation in behavioral flexibility traits was evident in different experimental settings using these selection lines. The fish were subjected to three sets of challenges (novel object test, resident–intruder test...... and confinement stressor test), all which were repeated a week later. Introducing a novel object evoked a divergent behavioral response in association with feeding: fish from the LR line displayed consistently suppressed feed intake while the HR fish remained unaffected. This observation was found...... to be repeatable along with attack latency and movement activity from the resident–intruder and confinement stressor tests. These results indicate that the behavioral responses in this animal model are context-dependent and shed new light on the expression of behavioral flexibility....

  18. Brief report: tailgating as a unique context for parental modeling on college student alcohol use.

    Science.gov (United States)

    Abar, Caitlin; Turrisi, Rob; Abar, Beau

    2011-10-01

    Little attention has been directed toward potential differential effects of the various contexts in which parents model alcohol use. The present study examined college football tailgating as a potential context in which parental modeling may be more or less risky. 290 college freshmen were assessed for perceptions of their parents' drinking and tailgating behaviors, individual alcohol use and consequences. Hierarchical multiple regressions were performed and results revealed that parental tailgating accounted for a significant increase in the variance explained in each of the student drinking measures. Parental drunkenness at tailgates predicted college student drinking and negative consequences, over and above the influence of typical parental heavy episodic drinking. The specific context in which students perceive their parents as drinking heavily may impact their own drinking. Tailgating at sporting events appears to be one such context where students perceive alcohol behaviors which they later model. Copyright © 2010 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

  19. Placing Health Trajectories in Family and Historical Context: A Proposed Enrichment of the Life Course Health and Development Model.

    Science.gov (United States)

    Jones, Marian Moser; Roy, Kevin

    2017-10-01

    Purpose This article offers constructive commentary on The Life Course Health and Development Model (LCHD) as an organizing framework for MCH research. Description The LCHD has recently been proposed as an organizing framework for MCH research. This model integrates biomedical, biopsychosocial, and life course frameworks, to explain how "individual health trajectories" develop over time. In this article, we propose that the LCHD can improve its relevance to MCH policy and practice by: (1) placing individual health trajectories within the context of family health trajectories, which unfold within communities and societies, over historical and generational time; and (2) placing greater weight on the social determinants that shape health development trajectories of individuals and families to produce greater or lesser health equity. Assessment We argue that emphasizing these nested, historically specific social contexts in life course models will enrich study design and data analysis for future developmental science research, will make the LCHD model more relevant in shaping MCH policy and interventions, and will guard against its application as a deterministic framework. Specific ways to measure these and examples of how they can be integrated into the LCHD model are articulated. Conclusion Research applying the LCHD should incorporate the specific family and socio-historical contexts in which development occurs to serve as a useful basis for policy and interventions. Future longitudinal studies of maternal and child health should include collection of time-dependent data related to family environment and other social determinants of health, and analyze the impact of historical events and trends on specific cohorts.

  20. NanOx, a new model to predict cell survival in the context of particle therapy

    Science.gov (United States)

    Cunha, M.; Monini, C.; Testa, E.; Beuve, M.

    2017-02-01

    Particle therapy is increasingly attractive for the treatment of tumors and the number of facilities offering it is rising worldwide. Due to the well-known enhanced effectiveness of ions, it is of utmost importance to plan treatments with great care to ensure tumor killing and healthy tissues sparing. Hence, the accurate quantification of the relative biological effectiveness (RBE) of ions, used in the calculation of the biological dose, is critical. Nevertheless, the RBE is a complex function of many parameters and its determination requires modeling. The approaches currently used have allowed particle therapy to thrive, but still show some shortcomings. We present herein a short description of a new theoretical framework, NanOx, to calculate cell survival in the context of particle therapy. It gathers principles from existing approaches, while addressing some of their weaknesses. NanOx is a multiscale model that takes the stochastic nature of radiation at nanometric and micrometric scales fully into account, integrating also the chemical aspects of radiation-matter interaction. The latter are included in the model by means of a chemical specific energy, determined from the production of reactive chemical species induced by irradiation. Such a production represents the accumulation of oxidative stress and sublethal damage in the cell, potentially generating non-local lethal events in NanOx. The complementary local lethal events occur in a very localized region and can, alone, lead to cell death. Both these classes of events contribute to cell death. The comparison between experimental data and model predictions for the V79 cell line show a good agreement. In particular, the dependence of the typical shoulders of cell survival curves on linear energy transfer are well described, but also the effectiveness of different ions, including the overkill effect. These results required the adjustment of a number of parameters compatible with the application of the model in

  1. Context-dependent effects of a single administration of mirtazapine on the expression of methamphetamine-induced conditioned place preference

    Directory of Open Access Journals (Sweden)

    Robin eVoigt

    2012-01-01

    Full Text Available Re-exposure to cues repeatedly associated with methamphetamine (Meth can trigger Meth-seeking and relapse in the abstinent abuser. Weakening the conditioned Meth-associated memory during cue re-exposure may provide a means for relapse-reduction pharmacotherapy. Accordingly, we sought to determine if the atypical antidepressant mirtazapine disrupted the long-term maintenance of Meth-induced conditioned place preference (CPP when administered in conjunction with re-exposure to contextual conditioning cues, and if this effect was altered by Meth being present during cue re-exposure. First, we evaluated the effect of mirtazapine on the maintenance of Meth-induced CPP during re-exposure to either the saline- or Meth-paired chamber 12 days after conditioning. Meth conditioned rats subsequently administered mirtazapine expressed CPP independent of re-exposure to the saline- or Meth-paired chamber; but the magnitude of CPP was significantly less for mirtazapine-treated rats re-exposed to the Meth-paired chamber. Next, we evaluated the effect of mirtazapine on a ‘reinforced re-exposure’ to the Meth-paired context. Administration of mirtazapine vehicle and Meth, prior to re-exposure to the Meth-paired chamber did not disrupt the ability of rats to demonstrate CPP on day 20; however, rats administered mirtazapine and Meth prior to re-exposure to the Meth-paired chamber did not demonstrate CPP. These results indicate a context-dependent effect of mirtazapine, and that the ability of mirtazapine to disrupt the long-term maintenance of CPP is greatest when the atypical antidepressant is tested with a combination of Meth injection and contextual cues.

  2. Functional subdivisions within the human intraparietal sulcus are involved in visuospatial transformation in a non-context-dependent manner.

    Science.gov (United States)

    Papadopoulos, Alexandra; Sforazzini, Francesco; Egan, Gary; Jamadar, Sharna

    2018-01-01

    Object-based visuospatial transformation is important for the ability to interact with the world and the people and objects within it. In this preliminary investigation, we hypothesized that object-based visuospatial transformation is a unitary process invoked regardless of current context and is localized to the intraparietal sulcus. Participants (n = 14) performed both antisaccade and mental rotation tasks while scanned using fMRI. A statistical conjunction confirmed that both tasks activated the intraparietal sulcus. Statistical parametric anatomical mapping determined that the statistical conjunction was localized to intraparietal sulcus subregions hIP2 and hIP3. A Gaussian naïve Bayes classifier confirmed that the conjunction in region hIP3 was indistinguishable between tasks. The results provide evidence that object-based visuospatial transformation is a domain-general process that is invoked regardless of current context. Our results are consistent with the modular model of the posterior parietal cortex and the distinct cytoarchitectonic, structural, and functional connectivity profiles of the subregions in the intraparietal sulcus. Hum Brain Mapp 39:354-368, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Semantic concept-enriched dependence model for medical information retrieval.

    Science.gov (United States)

    Choi, Sungbin; Choi, Jinwook; Yoo, Sooyoung; Kim, Heechun; Lee, Youngho

    2014-02-01

    In medical information retrieval research, semantic resources have been mostly used by expanding the original query terms or estimating the concept importance weight. However, implicit term-dependency information contained in semantic concept terms has been overlooked or at least underused in most previous studies. In this study, we incorporate a semantic concept-based term-dependence feature into a formal retrieval model to improve its ranking performance. Standardized medical concept terms used by medical professionals were assumed to have implicit dependency within the same concept. We hypothesized that, by elaborately revising the ranking algorithms to favor documents that preserve those implicit dependencies, the ranking performance could be improved. The implicit dependence features are harvested from the original query using MetaMap. These semantic concept-based dependence features were incorporated into a semantic concept-enriched dependence model (SCDM). We designed four different variants of the model, with each variant having distinct characteristics in the feature formulation method. We performed leave-one-out cross validations on both a clinical document corpus (TREC Medical records track) and a medical literature corpus (OHSUMED), which are representative test collections in medical information retrieval research. Our semantic concept-enriched dependence model consistently outperformed other state-of-the-art retrieval methods. Analysis shows that the performance gain has occurred independently of the concept's explicit importance in the query. By capturing implicit knowledge with regard to the query term relationships and incorporating them into a ranking model, we could build a more robust and effective retrieval model, independent of the concept importance. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. A temperature dependent slip factor based thermal model for friction ...

    Indian Academy of Sciences (India)

    This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power required, the ...

  5. A temperature dependent slip factor based thermal model for friction

    Indian Academy of Sciences (India)

    This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power required, the ...

  6. Variance-based sensitivity indices for models with dependent inputs

    International Nuclear Information System (INIS)

    Mara, Thierry A.; Tarantola, Stefano

    2012-01-01

    Computational models are intensively used in engineering for risk analysis or prediction of future outcomes. Uncertainty and sensitivity analyses are of great help in these purposes. Although several methods exist to perform variance-based sensitivity analysis of model output with independent inputs only a few are proposed in the literature in the case of dependent inputs. This is explained by the fact that the theoretical framework for the independent case is set and a univocal set of variance-based sensitivity indices is defined. In the present work, we propose a set of variance-based sensitivity indices to perform sensitivity analysis of models with dependent inputs. These measures allow us to distinguish between the mutual dependent contribution and the independent contribution of an input to the model response variance. Their definition relies on a specific orthogonalisation of the inputs and ANOVA-representations of the model output. In the applications, we show the interest of the new sensitivity indices for model simplification setting. - Highlights: ► Uncertainty and sensitivity analyses are of great help in engineering. ► Several methods exist to perform variance-based sensitivity analysis of model output with independent inputs. ► We define a set of variance-based sensitivity indices for models with dependent inputs. ► Inputs mutual contributions are distinguished from their independent contributions. ► Analytical and computational tests are performed and discussed.

  7. Time-Dependent Toroidal Compactification Proposals and the Bianchi Type I Model: Classical and Quantum Solutions

    Directory of Open Access Journals (Sweden)

    L. Toledo Sesma

    2016-01-01

    Full Text Available We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW equation in the context of standard quantum cosmology.

  8. Model-driven dependability assessment of software systems

    CERN Document Server

    Bernardi, Simona; Petriu, Dorina C

    2013-01-01

    In this book, the authors present cutting-edge model-driven techniques for modeling and analysis of software dependability. Most of them are based on the use of UML as software specification language. From the software system specification point of view, such techniques exploit the standard extension mechanisms of UML (i.e., UML profiling). UML profiles enable software engineers to add non-functional properties to the software model, in addition to the functional ones. The authors detail the state of the art on UML profile proposals for dependability specification and rigorously describe the t

  9. Energy based model for temperature dependent behavior of ferromagnetic materials

    International Nuclear Information System (INIS)

    Sah, Sanjay; Atulasimha, Jayasimha

    2017-01-01

    An energy based model for temperature dependent anhysteretic magnetization curves of ferromagnetic materials is proposed and benchmarked against experimental data. This is based on the calculation of macroscopic magnetic properties by performing an energy weighted average over all possible orientations of the magnetization vector. Most prior approaches that employ this method are unable to independently account for the effect of both inhomogeneity and temperature in performing the averaging necessary to model experimental data. Here we propose a way to account for both effects simultaneously and benchmark the model against experimental data from ~5 K to ~300 K for two different materials in both annealed (fewer inhomogeneities) and deformed (more inhomogeneities) samples. This demonstrates that this framework is well suited to simulate temperature dependent experimental magnetic behavior. - Highlights: • Energy based model for temperature dependent ferromagnetic behavior. • Simultaneously accounts for effect of temperature and inhomogeneities. • Benchmarked against experimental data from 5 K to 300 K.

  10. A Dependent Hidden Markov Model of Credit Quality

    Directory of Open Access Journals (Sweden)

    Małgorzata Wiktoria Korolkiewicz

    2012-01-01

    Full Text Available We propose a dependent hidden Markov model of credit quality. We suppose that the "true" credit quality is not observed directly but only through noisy observations given by posted credit ratings. The model is formulated in discrete time with a Markov chain observed in martingale noise, where "noise" terms of the state and observation processes are possibly dependent. The model provides estimates for the state of the Markov chain governing the evolution of the credit rating process and the parameters of the model, where the latter are estimated using the EM algorithm. The dependent dynamics allow for the so-called "rating momentum" discussed in the credit literature and also provide a convenient test of independence between the state and observation dynamics.

  11. Characterization of Models for Time-Dependent Behavior of Soils

    DEFF Research Database (Denmark)

    Liingaard, Morten; Augustesen, Anders; Lade, Poul V.

    2004-01-01

    developed for metals and steel but are, to some extent, used to characterize time effects in geomaterials. The third part is a review of constitutive laws that describe not only viscous effects but also the inviscid ( rate-independent) behavior of soils, in principle, under any possible loading condition......  Different classes of constitutive models have been developed to capture the time-dependent viscous phenomena ~ creep, stress relaxation, and rate effects ! observed in soils. Models based on empirical, rheological, and general stress-strain-time concepts have been studied. The first part....... Special attention is paid to elastoviscoplastic models that combine inviscid elastic and time-dependent plastic behavior. Various general elastoviscoplastic models can roughly be divided into two categories: Models based on the concept of overstress and models based on nonstationary flow surface theory...

  12. Memories in context.

    Science.gov (United States)

    Pomi Brea, A; Mizraji, E

    1999-06-01

    Context-dependent associative memories are models that allow the retrieval of different vectorial responses given a same vectorial stimulus, depending on the context presented to the memory. The contextualization is obtained by doing the Kronecker product between two vectorial entries to the associative memory: the key stimulus and the context. These memories are able to display a wide variety of behaviors that range from all the basic operations of the logical calculus (including fuzzy logics) to the selective extraction of features from complex vectorial patterns. In the present contribution, we show that a context-dependent memory matrix stores a large amount of possible virtual associative memories, that awaken in the presence of a context. We show how the vectorial context allows a memory matrix to be representable in terms of its singular-value decomposition. We describe a neural interpretation of the model in which the Kronecker product is performed on the same neurons that sustain the memory. We explored, with numerical experiments, the reliability of chains of contextualized associations. In some cases, random disconnection produces the emergence of oscillatory behaviors of the system. Our results show that associative chains retain their performances for relatively large dimensions. Finally, we analyze the properties of some modules of context-dependent autoassociative memories inserted in recursive nets: the perceptual autoorganization in the presence of ambiguous inputs (e.g. the disambiguation of the Necker's cube figure), the construction of intersection filters, and the feature extraction capabilities.

  13. Comparing the epidermal growth factor interaction with four different cell lines: intriguing effects imply strong dependency of cellular context.

    Directory of Open Access Journals (Sweden)

    Hanna Björkelund

    Full Text Available The interaction of the epidermal growth factor (EGF with its receptor (EGFR is known to be complex, and the common over-expression of EGF receptor family members in a multitude of tumors makes it important to decipher this interaction and the following signaling pathways. We have investigated the affinity and kinetics of (125I-EGF binding to EGFR in four human tumor cell lines, each using four culturing conditions, in real time by use of LigandTracer®.Highly repeatable and precise measurements show that the overall apparent affinity of the (125I-EGF - EGFR interaction is greatly dependent on cell line at normal culturing conditions, ranging from K(D ≈ 200 pM on SKBR3 cells to K(D≈8 nM on A431 cells. The (125I-EGF - EGFR binding curves (irrespective of cell line have strong signs of multiple simultaneous interactions. Furthermore, for the cell lines A431 and SKOV3, gefitinib treatment increases the (125I-EGF - EGFR affinity, in particular when the cells are starved. The (125I-EGF - EGFR interaction on cell line U343 is sensitive to starvation while as on SKBR3 it is insensitive to gefitinib and starvation.The intriguing pattern of the binding characteristics proves that the cellular context is important when deciphering how EGF interacts with EGFR. From a general perspective, care is advisable when generalizing ligand-receptor interaction results across multiple cell-lines.

  14. Mutation rate, spectrum, topology, and context-dependency in the DNA mismatch repair-deficient Pseudomonas fluorescens ATCC948.

    Science.gov (United States)

    Long, Hongan; Sung, Way; Miller, Samuel F; Ackerman, Matthew S; Doak, Thomas G; Lynch, Michael

    2014-12-23

    High levels of genetic diversity exist among natural isolates of the bacterium Pseudomonas fluorescens, and are especially elevated around the replication terminus of the genome, where strain-specific genes are found. In an effort to understand the role of genetic variation in the evolution of Pseudomonas, we analyzed 31,106 base substitutions from 45 mutation accumulation lines of P. fluorescens ATCC948, naturally deficient for mismatch repair, yielding a base-substitution mutation rate of 2.34 × 10(-8) per site per generation (SE: 0.01 × 10(-8)) and a small-insertion-deletion mutation rate of 1.65 × 10(-9) per site per generation (SE: 0.03 × 10(-9)). We find that the spectrum of mutations in prophage regions, which often contain virulence factors and antibiotic resistance, is highly similar to that in the intergenic regions of the host genome. Our results show that the mutation rate varies around the chromosome, with the lowest mutation rate found near the origin of replication. Consistent with observations from other studies, we find that site-specific mutation rates are heavily influenced by the immediately flanking nucleotides, indicating that mutations are context dependent. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  15. The maintenance of sperm variability: context-dependent selection on sperm morphology in a broadcast spawning invertebrate.

    Science.gov (United States)

    Johnson, Darren W; Monro, Keyne; Marshall, Dustin J

    2013-05-01

    Why are sperm so variable despite having a singular, critical function and an intimate relationship with fitness? A key to understanding the evolution of sperm morphology is identifying which traits enable sperm to be successful fertilizers. Several sperm traits (e.g., tail length, overall size) are implicated in sperm performance, but the benefits of these traits are likely to be highly context dependent. Here, we examined phenotypic selection on sperm morphology of a broadcast spawning tube worm (Galeolaria gemineoa). We conducted laboratory experiments to measure the relationship between average sperm morphology and relative fertilization success across a range of sperm environments that were designed to approximate the range of sperm concentrations and ages encountered by eggs in nature. We found that the strength and form of multivariate selection varied substantially across our environmental gradients. Sperm with long tails and small heads were favored in high-concentration environments, whereas sperm with long heads were favored at low concentrations and old ages. We suggest variation in the local fertilization environment and resulting differences in selection can preserve variability in sperm morphology both within and among males. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

  16. COMT Val158Met Polymorphism, Executive Dysfunction, and Sexual Risk Behavior in the Context of HIV Infection and Methamphetamine Dependence

    Directory of Open Access Journals (Sweden)

    C. A. Bousman

    2010-01-01

    Full Text Available Catechol-O-methyltransferease (COMT metabolizes prefrontal cortex dopamine (DA, a neurotransmitter involved in executive behavior; the Val158Met genotype has been linked to executive dysfunction, which might increase sexual risk behaviors favoring HIV transmission. Main and interaction effects of COMT genotype and executive functioning on sexual risk behavior were examined. 192 sexually active nonmonogamous men completed a sexual behavior questionnaire, executive functioning tests, and were genotyped using blood-derived DNA. Main effects for executive dysfunction but not COMT on number of sexual partners were observed. A COMT x executive dysfunction interaction was found for number of sexual partners and insertive anal sex, significant for carriers of the Met/Met and to a lesser extent Val/Met genotypes but not Val/Val carriers. In the context of HIV and methamphetamine dependence, dopaminergic overactivity in prefrontal cortex conferred by the Met/Met genotype appears to result in a liability for executive dysfunction and potentially associated risky sexual behavior.

  17. Mutualists or parasites? Context-dependent influence of symbiotic fly larvae on carnivorous investment in the Albany pitcher plant.

    Science.gov (United States)

    Lymbery, Samuel J; Didham, Raphael K; Hopper, Stephen D; Simmons, Leigh W

    2016-11-01

    Carnivorous plants allocate more resources to carnivorous structures under nutrient-limited conditions, and relative investment can also be influenced by animals (infauna) that live in association with these plants and feed on their prey. We investigated these effects within a population of the pitcher plant Cephalotus follicularis containing varying densities of larvae of the fly Badisis ambulans . For plants with a relatively high proportion of adult pitchers, increasing larval density was associated with lower relative leaf allocation to new pitcher buds. For plants with relatively few adult pitchers, however, there was greater relative leaf allocation to pitcher buds with increasing larval density. In a field experiment, there was no significant effect of experimental larval presence or absence on the change in carbon-to-nitrogen (C/N) ratio of plants. Although the direction of the correlation between B. ambulans larvae and relative investment in carnivorous and non-carnivorous structures depends on the relative number of mature structures, whether the larvae enhance or reduce nutrient stress under different conditions remains unclear. The change in C/N was, however, less variable for pitchers that contained larvae, suggesting a stabilizing effect. Eighteen of 52 experimental pitchers were damaged by an unknown species, causing the pitcher fluid to drain. These pitchers were significantly more likely to survive if they contained larvae. These results suggest that the relationship between infauna and host varies with the initial resource status and environmental context of the host plant.

  18. Five-factor model personality traits in opioid dependence

    OpenAIRE

    Kornør, Hege; Nordvik, Hilmar

    2007-01-01

    Background: Personality traits may form a part of the aetiology of opioid dependence. For instance, opioid dependence may result from self-medication in emotionally unstable individuals, or from experimenting with drugs in sensation seekers. The five factor model (FFM) has obtained a central position in contemporary personality trait theory. The five factors are: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness. Few studies have examined whether the...

  19. Nuclear symmetry energy in density dependent hadronic models

    International Nuclear Information System (INIS)

    Haddad, S.

    2008-12-01

    The density dependence of the symmetry energy and the correlation between parameters of the symmetry energy and the neutron skin thickness in the nucleus 208 Pb are investigated in relativistic Hadronic models. The dependency of the symmetry energy on density is linear around saturation density. Correlation exists between the neutron skin thickness in the nucleus 208 Pb and the value of the nuclear symmetry energy at saturation density, but not with the slope of the symmetry energy at saturation density. (author)

  20. Context-Aware Mobile Collaborative Systems: Conceptual Modeling and Case Study

    Directory of Open Access Journals (Sweden)

    Luis G. Montané-Jiménez

    2012-10-01

    Full Text Available A Mobile Collaborative System (MCOS enable the cooperation of the members of a team to achieve a common goal by using a combination of mobile and fixed technologies. MCOS can be enhanced if the context of the group of users is considered in the execution of activities. This paper proposes a novel model for Context-Aware Mobile COllaborative Systems (CAMCOS and a functional architecture based on that model. In order to validate both the model and the architecture, a prototype system in the tourism domain was implemented and evaluated.

  1. USING COPULAS TO MODEL DEPENDENCE IN SIMULATION RISK ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    Dana L. Kelly

    2007-11-01

    Typical engineering systems in applications with high failure consequences such as nuclear reactor plants often employ redundancy and diversity of equipment in an effort to lower the probability of failure and therefore risk. However, it has long been recognized that dependencies exist in these redundant and diverse systems. Some dependencies, such as common sources of electrical power, are typically captured in the logic structure of the risk model. Others, usually referred to as intercomponent dependencies, are treated implicitly by introducing one or more statistical parameters into the model. Such common-cause failure models have limitations in a simulation environment. In addition, substantial subjectivity is associated with parameter estimation for these models. This paper describes an approach in which system performance is simulated by drawing samples from the joint distributions of dependent variables. The approach relies on the notion of a copula distribution, a notion which has been employed by the actuarial community for ten years or more, but which has seen only limited application in technological risk assessment. The paper also illustrates how equipment failure data can be used in a Bayesian framework to estimate the parameter values in the copula model. This approach avoids much of the subjectivity required to estimate parameters in traditional common-cause failure models. Simulation examples are presented for failures in time. The open-source software package R is used to perform the simulations. The open-source software package WinBUGS is used to perform the Bayesian inference via Markov chain Monte Carlo sampling.

  2. THE COMPETENCE-CONTEXT MODEL OF TRAINING AND EDUCATION IN COMPREHENSIVE SCHOOLS

    Directory of Open Access Journals (Sweden)

    N. A. Rybakina

    2017-01-01

    Full Text Available Introduction. The article is devoted to the problem of finding models of implementation of continuing education.Aim. The article deals with the competence and context-based model of learning and education in a comprehensive school as a part of lifelong education. The structural components of the competence-context model are described. The author also presents results of the model testing.Methodology and research methods. The competence-based approach is a methodological base of the presented research. The article carries out theoretical analysis of psychological and pedagogical literature concerning with the research problem. The author also applies such methods as: modeling of teaching objects, pedagogical experiment, quantitative and qualitative analysis.Results. The author suggests an educational model of competence formation and development in the framework of the theory of context-based education, which supports continuing personal development in the system of lifelong education. The paper describes the essence of the components of the competence-context model of training and upbringing.Scientific novelty. The research justifies the need to distinguish an invariant result of the continuing education. It is shown that competence as a combination of cognitive, social and reflective experience can act as an invariant.Practical significance. The proposed results of testing of the competencecontext model of training and education in comprehensive schools of the Samara region can be in-demand among school teachers for their educational work.

  3. A Context-Adaptive Teacher Training Model in a Ubiquitous Learning Environment

    Science.gov (United States)

    Chen, Min; Chiang, Feng Kuang; Jiang, Ya Na; Yu, Sheng Quan

    2017-01-01

    In view of the discrepancies in teacher training and teaching practice, this paper put forward a context-adaptive teacher training model in a ubiquitous learning (u-learning) environment. The innovative model provides teachers of different subjects with adaptive and personalized learning content in a u-learning environment, implements intra- and…

  4. A New Theory-to-Practice Model for Student Affairs: Integrating Scholarship, Context, and Reflection

    Science.gov (United States)

    Reason, Robert D.; Kimball, Ezekiel W.

    2012-01-01

    In this article, we synthesize existing theory-to-practice approaches within the student affairs literature to arrive at a new model that incorporates formal and informal theory, institutional context, and reflective practice. The new model arrives at a balance between the rigor necessary for scholarly theory development and the adaptability…

  5. Willingness to Communicate in English: A Microsystem Model in the Iranian EFL Classroom Context

    Science.gov (United States)

    Khajavy, Gholam Hassan; Ghonsooly, Behzad; Fatemi, Azar Hosseini; Choi, Charles W.

    2016-01-01

    This study examined willingness to communicate (WTC) in English among Iranian EFL learners in the classroom context. For this purpose, a second language willingness to communicate (L2WTC) model based on WTC theory (MacIntyre, Clément, Dörnyei, and Noels, 1998) and empirical studies was proposed and tested using structural equation modeling (SEM).…

  6. A review of communication models and frameworks in a healthcare context.

    Science.gov (United States)

    Cheng, Brenda S S; Bridges, Susan M; Yiu, Cynthia K Y; McGrath, Colman P

    2015-03-01

    This paper reviews six key communication models and frameworks in healthcare contexts. Comparison suggests key inter-relationships between the different stages of the clinical consultations. Implications are identified for future study in healthcare provider-patient communication. Clinical Relevance: To understand the healthcare provider-patient interaction through communication models.

  7. A Model of Situational Willingness to Communicate (WTC) in the Study Abroad Context

    Science.gov (United States)

    Robson, Graham

    2015-01-01

    The use of structural modeling has helped to explain constructs leading to Willingness to Communicate (WTC) in L1 and L2 contexts. When WTC was conceptualized as a trait in the L1, more personality variables were used in models. When WTC moved into the realm of second language, researchers still used trait measurements to explain the construct,…

  8. Beyond Motivation: Exploring Mathematical Modeling as a Context for Deepening Students' Understandings of Curricular Mathematics

    Science.gov (United States)

    Zbiek, Rose Mary; Conner, Annamarie

    2006-01-01

    Views of mathematical modeling in empirical, expository, and curricular references typically capture a relationship between real-world phenomena and mathematical ideas from the perspective that competence in mathematical modeling is a clear goal of the mathematics curriculum. However, we work within a curricular context in which mathematical…

  9. Micromechanical modeling of rate-dependent behavior of Connective tissues.

    Science.gov (United States)

    Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M

    2017-03-07

    In this paper, a constitutive and micromechanical model for prediction of rate-dependent behavior of connective tissues (CTs) is presented. Connective tissues are considered as nonlinear viscoelastic material. The rate-dependent behavior of CTs is incorporated into model using the well-known quasi-linear viscoelasticity (QLV) theory. A planar wavy representative volume element (RVE) is considered based on the tissue microstructure histological evidences. The presented model parameters are identified based on the available experiments in the literature. The presented constitutive model introduced to ABAQUS by means of UMAT subroutine. Results show that, monotonic uniaxial test predictions of the presented model at different strain rates for rat tail tendon (RTT) and human patellar tendon (HPT) are in good agreement with experimental data. Results of incremental stress-relaxation test are also presented to investigate both instantaneous and viscoelastic behavior of connective tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. System of systems dependability – Theoretical models and applications examples

    International Nuclear Information System (INIS)

    Bukowski, L.

    2016-01-01

    The aim of this article is to generalise the concept of "dependability" in a way, that could be applied to all types of systems, especially the system of systems (SoS), operating under both normal and abnormal work conditions. In order to quantitatively assess the dependability we applied service continuity oriented approach. This approach is based on the methodology of service engineering and is closely related to the idea of resilient enterprise as well as to the concept of disruption-tolerant operation. On this basis a framework for evaluation of SoS dependability has been developed in a static as well as dynamic approach. The static model is created as a fuzzy logic-oriented advisory expert system and can be particularly useful at the design stage of SoS. The dynamic model is based on the risk oriented approach, and can be useful both at the design stage and for management of SoS. The integrated model of dependability can also form the basis for a new definition of the dependability engineering, namely as a superior discipline to reliability engineering, safety engineering, security engineering, resilience engineering and risk engineering. - Highlights: • A framework for evaluation of system of systems dependability is presented. • The model is based on the service continuity concept and consists of two parts. • The static part can be created as a fuzzy logic-oriented advisory expert system. • The dynamic, risk oriented part, is related to the concept of throughput chain. • A new definition of dependability engineering is proposed.

  11. On the Temperature Dependence of the UNIQUAC/UNIFAC Models

    DEFF Research Database (Denmark)

    Skjold-Jørgensen, Steen; Rasmussen, Peter; Fredenslund, Aage

    1980-01-01

    of the simultaneous correlation. The temperature dependent parameters have, however, little physical meaning and very odd results are frequently obtained when the interaction parameters obtained from excess enthalpy information alone are used for the prediction of vapor-liquid equilibria. The UNIQUAC/UNIFAC models...... are modified in this work by the introduction of a general temperature dependence of the coordination number. The modified UNIQUAC/UNIFAC models are especially suited for the representation of mixtures containing non-associating components. The modified models contain the same number of interaction parameters...... parameters based on excess enthalpy data, and the prediction of excess enthalpy information from only one isothermal set of vapor-liquid equilibrium data is qualitatively acceptable. A parameter table for the modified UNIFAC model is given for the five main groups: CH2, C = C, ACH, ACCH2 and CH2O....

  12. A plastic damage model with stress triaxiality-dependent hardening

    International Nuclear Information System (INIS)

    Shen Xinpu; Shen Guoxiao; Zhou Lin

    2005-01-01

    Emphases of this study were placed on the modelling of plastic damage behaviour of prestressed structural concrete, with special attention being paid to the stress-triaxiality dependent plastic hardening law and the corresponding damage evolution law. A definition of stress triaxiality was proposed and introduced in the model presented here. Drucker-Prager -type plasticity was adopted in the formulation of the plastic damage constitutive equations. Numerical validations were performed for the proposed plasticity-based damage model with a driver subroutine developed in this study. The predicted stress-strain behaviour seems reasonably accurate for the uniaxial tension and uniaxial compression compared with the experimental data reported in references. Numerical calculations of compressions under various hydrostatic stress confinements were carried out in order to validate the stress triaxiality dependent properties of the model. (authors)

  13. Five-factor model personality traits in opioid dependence.

    Science.gov (United States)

    Kornør, Hege; Nordvik, Hilmar

    2007-08-06

    Personality traits may form a part of the aetiology of opioid dependence. For instance, opioid dependence may result from self-medication in emotionally unstable individuals, or from experimenting with drugs in sensation seekers. The five factor model (FFM) has obtained a central position in contemporary personality trait theory. The five factors are: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness. Few studies have examined whether there is a distinct personality pattern associated with opioid dependence. We compared FFM personality traits in 65 opioid dependent persons (mean age 27 years, 34% females) in outpatient counselling after a minimum of 5 weeks in buprenorphine replacement therapy, with those in a non-clinical, age- and sex-matched sample selected from a national database. Personality traits were assessed by a Norwegian version of the Revised NEO Personality Inventory (NEO PI-R), a 240-item self-report questionnaire. Cohen's d effect sizes were calculated for the differences in personality trait scores. The opioid-dependent sample scored higher on Neuroticism, lower on Extraversion and lower on Conscientiousness (d = -1.7, 1.2 and 1.7, respectively) than the controls. Effects sizes were small for the difference between the groups in Openness to experience scores and Agreeableness scores. We found differences of medium and large effect sizes between the opioid dependent group and the matched comparison group, suggesting that the personality traits of people with opioid dependence are in fact different from those of non-clinical peers.

  14. Tree Memory Networks for Modelling Long-term Temporal Dependencies

    OpenAIRE

    Fernando, Tharindu; Denman, Simon; McFadyen, Aaron; Sridharan, Sridha; Fookes, Clinton

    2017-01-01

    In the domain of sequence modelling, Recurrent Neural Networks (RNN) have been capable of achieving impressive results in a variety of application areas including visual question answering, part-of-speech tagging and machine translation. However this success in modelling short term dependencies has not successfully transitioned to application areas such as trajectory prediction, which require capturing both short term and long term relationships. In this paper, we propose a Tree Memory Networ...

  15. Developmental plasticity of spatial hearing following asymmetric hearing loss: context-dependent cue integration and its clinical implications

    Directory of Open Access Journals (Sweden)

    Peter eKeating

    2013-12-01

    Full Text Available Under normal hearing conditions, comparisons of the sounds reaching each ear are critical for accurate sound localization. Asymmetric hearing loss should therefore degrade spatial hearing and has become an important experimental tool for probing the plasticity of the auditory system, both during development and adulthood. In clinical populations, hearing loss affecting one ear more than the other is commonly associated with otitis media with effusion, a disorder experienced by approximately 80% of children before the age of two. Asymmetric hearing may also arise in other clinical situations, such as after unilateral cochlear implantation. Here, we consider the role played by spatial cue integration in sound localization under normal acoustical conditions. We then review evidence for adaptive changes in spatial hearing following a developmental hearing loss in one ear, and argue that adaptation may be achieved either by learning a new relationship between the altered cues and directions in space or by changing the way different cues are integrated in the brain. We next consider developmental plasticity as a source of vulnerability, describing maladaptive effects of asymmetric hearing loss that persist even when normal hearing is provided. We also examine the extent to which the consequences of asymmetric hearing loss depend upon its timing and duration. Although much of the experimental literature has focused on the effects of a stable unilateral hearing loss, some of the most common hearing impairments experienced by children tend to fluctuate over time. We therefore argue that there is a need to bridge this gap by investigating the effects of recurring hearing loss during development, and outline recent steps in this direction. We conclude by arguing that this work points toward a more nuanced view of developmental plasticity, in which plasticity may be selectively expressed in response to specific sensory contexts, and consider the clinical

  16. Aged dominant negative p38α MAPK mice are resistant to age-dependent decline in adult-neurogenesis and context discrimination fear conditioning.

    Science.gov (United States)

    Cortez, IbDanelo; Bulavin, Dmitry V; Wu, Ping; McGrath, Erica L; Cunningham, Kathryn A; Wakamiya, Maki; Papaconstantinou, John; Dineley, Kelly T

    2017-03-30

    A major aspect of mammalian aging is the decline in functional competence of many self-renewing cell types, including adult-born neuronal precursors. Since age-related senescence of self-renewal occurs simultaneously with chronic up-regulation of the p38MAPKalpha (p38α) signaling pathway, we used the dominant negative mouse model for attenuated p38α activity (DN-p38α AF/+ ) in which Thr180 and Tyr182 are mutated (T→A/Y→F) to prevent phosphorylation activation (DN-p38α AF/+ ) and kinase activity. As a result, aged DN-p38α AF/+ mice are resistant to age-dependent decline in proliferation and regeneration of several peripheral tissue progenitors when compared to wild-type littermates. Aging is the major risk factor for non-inherited forms of Alzheimer's disease (AD); environmental and genetic risk factors that accelerate the senescence phenotype are thought to contribute to an individual's relative risk. In the present study, we evaluated aged DN-p38α AF/+ and wildtype littermates in a series of behavioral paradigms to test if p38α mutant mice exhibit altered baseline abnormalities in neurological reflexes, locomotion, anxiety-like behavior, and age-dependent cognitive decline. While aged DN-p38α AF/+ and wildtype littermates appear equal in all tested baseline neurological and behavioral parameters, DN-p38α AF/+ exhibit superior context discrimination fear conditioning. Context discrimination is a cognitive task that is supported by proliferation and differentiation of adult-born neurons in the dentate gyrus of the hippocampus. Consistent with enhanced context discrimination in aged DN-p38α AF/+ , we discovered enhanced production of adult-born neurons in the dentate gyrus of DN-p38α AF/+ mice compared to wildtype littermates. Our findings support the notion that p38α inhibition has therapeutic utility in aging diseases that affect cognition, such as AD. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Graphical models for inference under outcome-dependent sampling

    DEFF Research Database (Denmark)

    Didelez, V; Kreiner, S; Keiding, N

    2010-01-01

    We consider situations where data have been collected such that the sampling depends on the outcome of interest and possibly further covariates, as for instance in case-control studies. Graphical models represent assumptions about the conditional independencies among the variables. By including...

  18. A flexible model for actuarial risks under dependence

    NARCIS (Netherlands)

    Albers, Willem/Wim; Kallenberg, W.C.M.; Lukocius, V.

    Methods for computing risk measures, such as stop-loss premiums, tacitly assume independence of the underlying individual risks. This can lead to huge errors even when only small dependencies occur. In the present paper, a general model is developed which covers what happens in practice in a

  19. Solute transport modelling with the variable temporally dependent ...

    Indian Academy of Sciences (India)

    Pintu Das

    2018-02-07

    Feb 7, 2018 ... Abstract. In this present study, analytical and numerical solutions are obtained for solute transport modelling in homogeneous semi-infinite porous medium. The dispersion coefficient is assumed to be initial dispersion and velocity is assumed to be temporally dependent with initial seepage velocity. Also ...

  20. A compositional method to model dependent failure behavior based on PoF models

    Directory of Open Access Journals (Sweden)

    Zhiguo ZENG

    2017-10-01

    Full Text Available In this paper, a new method is developed to model dependent failure behavior among failure mechanisms. Unlike the existing methods, the developed method models the root cause of the dependency explicitly, so that a deterministic model, rather than a probabilistic one, can be established. Three steps comprise the developed method. First, physics-of-failure (PoF models are utilized to model each failure mechanism. Then, interactions among failure mechanisms are modeled as a combination of three basic relations, competition, superposition and coupling. This is the reason why the method is referred to as “compositional method”. Finally, the PoF models and the interaction model are combined to develop a deterministic model of the dependent failure behavior. As a demonstration, the method is applied on an actual spool and the developed failure behavior model is validated by a wear test. The result demonstrates that the compositional method is an effective way to model dependent failure behavior.

  1. Random neuronal ensembles can inherently do context dependent coarse conjunctive encoding of input stimulus without any specific training.

    Science.gov (United States)

    George, Jude Baby; Abraham, Grace Mathew; Rashid, Zubin; Amrutur, Bharadwaj; Sikdar, Sujit Kumar

    2018-01-23

    Conjunctive encoding of inputs has been hypothesized to be a key feature in the computational capabilities of the brain. This has been inferred based on behavioral studies and electrophysiological recording from animals. In this report, we show that random neuronal ensembles grown on multi-electrode array perform a coarse-conjunctive encoding for a sequence of inputs with the first input setting the context. Such an encoding scheme creates similar yet unique population codes at the output of the ensemble, for related input sequences, which can then be decoded via a simple perceptron and hence a single STDP neuron layer. The random neuronal ensembles allow for pattern generalization and novel sequence classification without needing any specific learning or training of the ensemble. Such a representation of the inputs as population codes of neuronal ensemble outputs, has inherent redundancy and is suitable for further decoding via even probabilistic/random connections to subsequent neuronal layers. We reproduce this behavior in a mathematical model to show that a random neuronal network with a mix of excitatory and inhibitory neurons and sufficient connectivity creates similar coarse-conjunctive encoding of input sequences.

  2. Anxiety in the context of cancer: A systematic review and development of an integrated model.

    Science.gov (United States)

    Curran, Leah; Sharpe, Louise; Butow, Phyllis

    2017-08-01

    Anxiety is common in the context of cancer, but there are few theoretical models that apply to people with cancer across the trajectory of their illness. The aims of this review are to identify existing theories and to propose an integrated model of cancer-related anxiety. Using a systematic literature search of Medline, Premedline and PsycINFO databases, we identified nine theoretical models of anxiety in the context of cancer. We reviewed these for psychological concepts that fell under five themes: pre-existing schema, the inherent nature of cancer, cognitive factors, coping responses and contextual factors. From these themes, we integrated concepts from different models to develop a theoretical framework to explain the development and maintenance of anxiety in the context of cancer. The resulting model suggests that pre-existing schema, past experiences of cancer, an intolerance of uncertainty and meta-cognitive beliefs about worry interact with the inherent nature of cancer to produce overwhelming distress. The distress activates cognitive processes characterized by vigilance, worry and rumination. Attempts to cope by re-establishing control, and a pattern of vigilance to cancer-related cues and/or avoidance reinforce anxiety, in the context of a range of systemic factors that can either buffer against or worsen the anxiety. Copyright © 2017. Published by Elsevier Ltd.

  3. Modeling electricity spot and futures price dependence: A multifrequency approach

    Science.gov (United States)

    Malo, Pekka

    2009-11-01

    Electricity prices are known to exhibit multifractal properties. We accommodate this finding by investigating multifractal models for electricity prices. In this paper we propose a flexible Copula-MSM (Markov Switching Multifractal) approach for modeling spot and weekly futures price dynamics. By using a conditional copula function, the framework allows us to separately model the dependence structure, while enabling use of multifractal stochastic volatility models to characterize fluctuations in marginal returns. An empirical experiment is carried out using data from Nord Pool. A study of volatility forecasting performance for electricity spot prices reveals that multifractal techniques are a competitive alternative to GARCH models. We also demonstrate how the Copula-MSM model can be employed for finding optimal portfolios, which minimizes the Conditional Value-at-Risk.

  4. Model dependence of the 2H electric dipole moment

    International Nuclear Information System (INIS)

    Afnan, I. R.; Gibson, B. F.

    2010-01-01

    Background: Direct measurement of the electric dipole moment (EDM) of the neutron is in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the 3 P 1 channel, the latter being sensitive to the off-shell behavior of the 3 P 1 amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short-range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the 2 H EDM until such time as a measurement better than 10% is obtained.

  5. Modeling the time-changing dependence in stock markets

    International Nuclear Information System (INIS)

    Frezza, Massimiliano

    2012-01-01

    The time-changing dependence in stock markets is investigated by assuming the multifractional process with random exponent (MPRE) as model for actual log price dynamics. By modeling its functional parameter S(t, ω) via the square root process (S.R.) a twofold aim is obtained. From one hand both the main financial and statistical properties shown by the estimated S(t) are captured by surrogates, on the other hand this capability reveals able to model the time-changing dependence shown by stocks or indexes. In particular, a new dynamical approach to interpreter market mechanisms is given. Empirical evidences are offered by analysing the behaviour of the daily closing prices of a very known index, the Industrial Average Dow Jones (DJIA), beginning on March,1990 and ending on February, 2005.

  6. Chromospheric extents predicted by time-dependent acoustic wave models

    Science.gov (United States)

    Cuntz, Manfred

    1990-01-01

    Theoretical models for chromospheric structures of late-type giant stars are computed, including the time-dependent propagation of acoustic waves. Models with short-period monochromatic shock waves as well as a spectrum of acoustic waves are discussed, and the method is applied to the stars Arcturus, Aldebaran, and Betelgeuse. Chromospheric extent, defined as the monotonic decrease with height of the time-averaged electron densities, are found to be 1.12, 1.13, and 1.22 stellar radii for the three stars, respectively; this corresponds to a time-averaged electron density of 10 to the 7th/cu cm. Predictions of the extended chromospheric obtained using a simple scaling law agree well with those obtained by the time-dependent wave models; thus, the chromospheres of all stars for which the scaling law is valid consist of the same number of pressure scale heights.

  7. Chromospheric extents predicted by time-dependent acoustic wave models

    Energy Technology Data Exchange (ETDEWEB)

    Cuntz, M. (Joint Institute for Laboratory Astrophysics, Boulder, CO (USA) Heidelberg Universitaet (Germany, F.R.))

    1990-01-01

    Theoretical models for chromospheric structures of late-type giant stars are computed, including the time-dependent propagation of acoustic waves. Models with short-period monochromatic shock waves as well as a spectrum of acoustic waves are discussed, and the method is applied to the stars Arcturus, Aldebaran, and Betelgeuse. Chromospheric extent, defined as the monotonic decrease with height of the time-averaged electron densities, are found to be 1.12, 1.13, and 1.22 stellar radii for the three stars, respectively; this corresponds to a time-averaged electron density of 10 to the 7th/cu cm. Predictions of the extended chromospheric obtained using a simple scaling law agree well with those obtained by the time-dependent wave models; thus, the chromospheres of all stars for which the scaling law is valid consist of the same number of pressure scale heights. 74 refs.

  8. Model dependence in the density content of nuclear symmetry energy

    International Nuclear Information System (INIS)

    Mondal, C.; Agrawal, B.K.; Singh, S.K.; Patra, S.K.; Centelles, M.; Viñas, X.; Colò, G.; Roca-Maza, X.; Paar, N.

    2014-01-01

    Apart from very few light nuclei, all nuclear systems in nature, starting from tiny finite nuclei to huge astrophysical objects like neutron stars, are asymmetric. Densities of these systems vary over a wide range. So, accurate knowledge of symmetry energy over a wide range of density is very essential to understand several phenomena in finite nuclei as well as in neutron stars. We have shown using a representative set of systematically varied mean models that the correlation of symmetry energy slope parameter with the neutron skin thickness in 208 Pb nucleus has a noticeable amount of model dependence. The investigations in order to unveil the source of the model dependence in such correlations are underway

  9. Constructing a coherent problem model to facilitate algebra problem solving in a chemistry context

    Science.gov (United States)

    Hiong Ngu, Bing; Seeshing Yeung, Alexander; Phan, Huy P.

    2015-04-01

    An experiment using a sample of 11th graders compared text editing and worked examples approaches in learning to solve dilution and molarity algebra word problems in a chemistry context. Text editing requires students to assess the structure of a word problem by specifying whether the problem text contains sufficient, missing, or irrelevant information for reaching a solution. Worked examples direct students to follow steps toward the solution, and its emphasis is on computation instead of the formation of a coherent problem model. Text editing yielded higher scores in a transfer test (which shared the same solution procedure as in the acquisition problems but differed in contexts), but not a similar test (which resembled acquisition problems in terms of both solution procedure and context). Results provide some theoretical support and practical implications for using text editing to develop a coherent problem model to facilitate problem-solving skills in chemistry.

  10. Time dependent modeling of non-LTE plasmas: Final report

    International Nuclear Information System (INIS)

    1988-06-01

    During the period of performance of this contract Science Applications International Corporation (SAIC) has aided Lawrence Livermore National Laboratory (LLNL) in the development of an unclassified modeling tool for studying time evolution of high temperature ionizing and recombining plasmas. This report covers the numerical code developed, (D)ynamic (D)etailed (C)onfiguration (A)ccounting (DDCA), which was written to run on the National Magnetic Fusion Energy Computing Center (NMFECC) network as well as the classified Livermore Computer Center (OCTOPUS) network. DDCA is a One-Dimensional (1D) time dependent hydrodynamic model which makes use of the non-LTE detailed atomic physics ionization model DCA. 5 refs

  11. Estimating Drilling Cost and Duration Using Copulas Dependencies Models

    Directory of Open Access Journals (Sweden)

    M. Al Kindi

    2017-03-01

    Full Text Available Estimation of drilling budget and duration is a high-level challenge for oil and gas industry. This is due to the many uncertain activities in the drilling procedure such as material prices, overhead cost, inflation, oil prices, well type, and depth of drilling. Therefore, it is essential to consider all these uncertain variables and the nature of relationships between them. This eventually leads into the minimization of the level of uncertainty and yet makes a "good" estimation points for budget and duration given the well type. In this paper, the copula probability theory is used in order to model the dependencies between cost/duration and MRI (mechanical risk index. The MRI is a mathematical computation, which relates various drilling factors such as: water depth, measured depth, true vertical depth in addition to mud weight and horizontal displacement. In general, the value of MRI is utilized as an input for the drilling cost and duration estimations. Therefore, modeling the uncertain dependencies between MRI and both cost and duration using copulas is important. The cost and duration estimates for each well were extracted from the copula dependency model where research study simulate over 10,000 scenarios. These new estimates were later compared to the actual data in order to validate the performance of the procedure. Most of the wells show moderate - weak relationship of MRI dependence, which means that the variation in these wells can be related to MRI but to the extent that it is not the primary source.

  12. Anomalous scaling in an age-dependent branching model.

    Science.gov (United States)

    Keller-Schmidt, Stephanie; Tuğrul, Murat; Eguíluz, Víctor M; Hernández-García, Emilio; Klemm, Konstantin

    2015-02-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point.

  13. Stimulus-dependent maximum entropy models of neural population codes.

    Directory of Open Access Journals (Sweden)

    Einat Granot-Atedgi

    Full Text Available Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME model-a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population.

  14. Revising explanatory models to accommodate anomalous genetic phenomena: Problem solving in the context of discovery

    Science.gov (United States)

    Hafner, Robert; Stewart, Jim

    Past problem-solving research has provided a basis for helping students structure their knowledge and apply appropriate problem-solving strategies to solve problems for which their knowledge (or mental models) of scientific phenomena is adequate (model-using problem solving). This research examines how problem solving in the domain of Mendelian genetics proceeds in situations where solvers' mental models are insufficient to solve problems at hand (model-revising problem solving). Such situations require solvers to use existing models to recognize anomalous data and to revise those models to accommodate the data. The study was conducted in the context of 9-week high school genetics course and addressed: the heuristics charactenstic of successful model-revising problem solving: the nature of the model revisions, made by students as well as the nature of model development across problem types; and the basis upon which solvers decide that a revised model is sufficient (that t has both predictive and explanatory power).

  15. The role of flexibility in the Context-adaptive Model for language ...

    African Journals Online (AJOL)

    CAM). This article explores the role of flexibility in the CAM in theory and in practice. The first section presents a description of the model that highlights its flexible evaluation approach. The second section sketches the specific education context ...

  16. A Measurable Model of the Creative Process in the Context of a Learning Process

    Science.gov (United States)

    Ma, Min; Van Oystaeyen, Fred

    2016-01-01

    The authors' aim was to arrive at a measurable model of the creative process by putting creativity in the context of a learning process. The authors aimed to provide a rather detailed description of how creative thinking fits in a general description of the learning process without trying to go into an analysis of a biological description of the…

  17. Promoting Modeling and Covariational Reasoning among Secondary School Students in the Context of Big Data

    Science.gov (United States)

    Gil, Einat; Gibbs, Alison L.

    2017-01-01

    In this study, we follow students' modeling and covariational reasoning in the context of learning about big data. A three-week unit was designed to allow 12th grade students in a mathematics course to explore big and mid-size data using concepts such as trend and scatter to describe the relationships between variables in multivariate settings.…

  18. Informed Conjecturing of Solutions for Differential Equations in a Modeling Context

    Science.gov (United States)

    Winkel, Brian

    2015-01-01

    We examine two differential equations. (i) first-order exponential growth or decay; and (ii) second order, linear, constant coefficient differential equations, and show the advantage of learning differential equations in a modeling context for informed conjectures of their solution. We follow with a discussion of the complete analysis afforded by…

  19. An Econometric Examination of the Behavioral Perspective Model in the Context of Norwegian Retailing

    Science.gov (United States)

    Sigurdsson, Valdimar; Kahamseh, Saeed; Gunnarsson, Didrik; Larsen, Nils Magne; Foxall, Gordon R.

    2013-01-01

    The behavioral perspective model's (BPM; Foxall, 1990) retailing literature is built on extensive empirical research and techniques that were originally refined in choice experiments in behavioral economics and behavior analysis, and then tested mostly on British consumer panel data. We test the BPM in the context of Norwegian retailing. This…

  20. Socialization of Coping with Community Violence: Influences of Caregiver Coaching, Modeling, and Family Context

    Science.gov (United States)

    Kliewer, Wendy; Parrish, Katie Adams; Taylor, Kelli W.; Jackson, Kate; Walker, Jean M.; Shivy, Victoria A.

    2006-01-01

    A socialization model of coping with community violence was tested in 101 African American adolescents (55% male, ages 9-13) and their maternal caregivers living in high-violence areas of a mid-sized, southeastern city. Participants completed interviews assessing caregiver coping, family context, and child adjustment. Caregiver-child dyads also…

  1. Model of erosion–landslide interaction in the context of the reservoir ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 122; Issue 6. Model of erosion–landslide interaction in the context of the reservoir water level variations (East Siberia, Russia): Factors, environment and mechanisms. Oksana Mazaeva Viktoria Khak Elena Kozyreva. Volume 122 Issue 6 December 2013 pp 1515- ...

  2. Framing ICT Implementation in a Context of Educational Change: A Structural Equation Modelling Analysis

    Science.gov (United States)

    Wong, Emily M. L.; Li, Sandy C.

    2011-01-01

    Despite the common belief that information and communication technology (ICT) has the potential to support certain fundamental changes in learning, few have examined ICT implementation conceptually within a wider context of educational change. Methodologically, we are by and large limited to building simple models that accommodate only a single…

  3. Neutrino flavor instabilities in a time-dependent supernova model

    Directory of Open Access Journals (Sweden)

    Sajad Abbar

    2015-12-01

    Full Text Available A dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial spherical symmetry about the center of the supernova and the (directional axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this letter we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collective neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.

  4. A hydrostatic stress-dependent anisotropic model of viscoplasticity

    Science.gov (United States)

    Robinson, D. N.; Tao, Q.; Verrilli, M. J.

    1994-01-01

    A hydrostatic stress-dependent, anisotropic model of viscoplasticity is formulated as an extension of Bodner's model. This represents a further extension of the isotropic Bodner model over that made to anisotropy by Robinson and MitiKavuma. Account is made of the inelastic deformation that can occur in metallic composites under hydrostatic stress. A procedure for determining the material parameters is identified that is virtually identical to the established characterization procedure for the original Bodner model. Characterization can be achieved using longitudinal/transverse tensile and shear tests and hydrostatic stress tests; alternatively, four off-axis tensile tests can be used. Conditions for a yield stress minimum under off-axis tension are discussed. The model is applied to a W/Cu composite; characterization is made using off-axis tensile data generated at NASA Lewis Research Center (LeRC).

  5. Geometry-dependent atomic multipole models for the water molecule.

    Science.gov (United States)

    Loboda, O; Millot, C

    2017-10-28

    Models of atomic electric multipoles for the water molecule have been optimized in order to reproduce the electric potential around the molecule computed by ab initio calculations at the coupled cluster level of theory with up to noniterative triple excitations in an augmented triple-zeta quality basis set. Different models of increasing complexity, from atomic charges up to models containing atomic charges, dipoles, and quadrupoles, have been obtained. The geometry dependence of these atomic multipole models has been investigated by changing bond lengths and HOH angle to generate 125 molecular structures (reduced to 75 symmetry-unique ones). For several models, the atomic multipole components have been fitted as a function of the geometry by a Taylor series of fourth order in monomer coordinate displacements.

  6. A Gloss Composition and Context Clustering Based Distributed Word Sense Representation Model

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2015-08-01

    Full Text Available In recent years, there has been an increasing interest in learning a distributed representation of word sense. Traditional context clustering based models usually require careful tuning of model parameters, and typically perform worse on infrequent word senses. This paper presents a novel approach which addresses these limitations by first initializing the word sense embeddings through learning sentence-level embeddings from WordNet glosses using a convolutional neural networks. The initialized word sense embeddings are used by a context clustering based model to generate the distributed representations of word senses. Our learned representations outperform the publicly available embeddings on half of the metrics in the word similarity task, 6 out of 13 sub tasks in the analogical reasoning task, and gives the best overall accuracy in the word sense effect classification task, which shows the effectiveness of our proposed distributed distribution learning model.

  7. Relative Contributions of the Dorsal vs. Ventral Speech Streams to Speech Perception are Context Dependent: a lesion study

    Directory of Open Access Journals (Sweden)

    Corianne Rogalsky

    2014-04-01

    Full Text Available The neural basis of speech perception has been debated for over a century. While it is generally agreed that the superior temporal lobes are critical for the perceptual analysis of speech, a major current topic is whether the motor system contributes to speech perception, with several conflicting findings attested. In a dorsal-ventral speech stream framework (Hickok & Poeppel 2007, this debate is essentially about the roles of the dorsal versus ventral speech processing streams. A major roadblock in characterizing the neuroanatomy of speech perception is task-specific effects. For example, much of the evidence for dorsal stream involvement comes from syllable discrimination type tasks, which have been found to behaviorally doubly dissociate from auditory comprehension tasks (Baker et al. 1981. Discrimination task deficits could be a result of difficulty perceiving the sounds themselves, which is the typical assumption, or it could be a result of failures in temporary maintenance of the sensory traces, or the comparison and/or the decision process. Similar complications arise in perceiving sentences: the extent of inferior frontal (i.e. dorsal stream activation during listening to sentences increases as a function of increased task demands (Love et al. 2006. Another complication is the stimulus: much evidence for dorsal stream involvement uses speech samples lacking semantic context (CVs, non-words. The present study addresses these issues in a large-scale lesion-symptom mapping study. 158 patients with focal cerebral lesions from the Mutli-site Aphasia Research Consortium underwent a structural MRI or CT scan, as well as an extensive psycholinguistic battery. Voxel-based lesion symptom mapping was used to compare the neuroanatomy involved in the following speech perception tasks with varying phonological, semantic, and task loads: (i two discrimination tasks of syllables (non-words and words, respectively, (ii two auditory comprehension tasks

  8. Five-factor model personality traits in opioid dependence

    Directory of Open Access Journals (Sweden)

    Nordvik Hilmar

    2007-08-01

    Full Text Available Abstract Background Personality traits may form a part of the aetiology of opioid dependence. For instance, opioid dependence may result from self-medication in emotionally unstable individuals, or from experimenting with drugs in sensation seekers. The five factor model (FFM has obtained a central position in contemporary personality trait theory. The five factors are: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness. Few studies have examined whether there is a distinct personality pattern associated with opioid dependence. Methods We compared FFM personality traits in 65 opioid dependent persons (mean age 27 years, 34% females in outpatient counselling after a minimum of 5 weeks in buprenorphine replacement therapy, with those in a non-clinical, age- and sex-matched sample selected from a national database. Personality traits were assessed by a Norwegian version of the Revised NEO Personality Inventory (NEO PI-R, a 240-item self-report questionnaire. Cohen's d effect sizes were calculated for the differences in personality trait scores. Results The opioid-dependent sample scored higher on Neuroticism, lower on Extraversion and lower on Conscientiousness (d = -1.7, 1.2 and 1.7, respectively than the controls. Effects sizes were small for the difference between the groups in Openness to experience scores and Agreeableness scores. Conclusion We found differences of medium and large effect sizes between the opioid dependent group and the matched comparison group, suggesting that the personality traits of people with opioid dependence are in fact different from those of non-clinical peers.

  9. Mean photon number dependent variational method to the Rabi model

    International Nuclear Information System (INIS)

    Liu, Maoxin; Ying, Zu-Jian; Luo, Hong-Gang; An, Jun-Hong

    2015-01-01

    We present a mean photon number dependent variational method, which works well in the whole coupling regime if the photon energy is dominant over the spin-flipping, to evaluate the properties of the Rabi model for both the ground state and excited states. For the ground state, it is shown that the previous approximate methods, the generalized rotating-wave approximation (only working well in the strong coupling limit) and the generalized variational method (only working well in the weak coupling limit), can be recovered in the corresponding coupling limits. The key point of our method is to tailor the merits of these two existing methods by introducing a mean photon number dependent variational parameter. For the excited states, our method yields considerable improvements over the generalized rotating-wave approximation. The variational method proposed could be readily applied to more complex models, for which it is difficult to formulate an analytic formula. (paper)

  10. Anomalous scaling in an age-dependent branching model

    OpenAIRE

    Keller-Schmidt, Stephanie; Tugrul, Murat; Eguíluz, Víctor M.; Hernández-García, Emilio; Klemm, Konstantin

    2015-01-01

    We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age $\\tau$ as $\\tau^{-\\alpha}$. Depending on the exponent $\\alpha$, the scaling of tree depth with tree size $n$ displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition ($\\alpha=1$) tree depth grows as $(\\log n)^2$. This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus p...

  11. Econometric model for age- and population-dependent radiation exposures

    International Nuclear Information System (INIS)

    Sandquist, G.M.; Slaughter, D.M.; Rogers, V.C.

    1991-01-01

    The economic impact associated with ionizing radiation exposures in a given human population depends on numerous factors including the individual's mean economic status as a function age, the age distribution of the population, the future life expectancy at each age, and the latency period for the occurrence of radiation-induced health effects. A simple mathematical model has been developed that provides an analytical methodology for estimating the societal econometrics associated with radiation effects are to be assessed and compared for economic evaluation

  12. A Context-Recognition-Aided PDR Localization Method Based on the Hidden Markov Model

    Directory of Open Access Journals (Sweden)

    Yi Lu

    2016-11-01

    Full Text Available Indoor positioning has recently become an important field of interest because global navigation satellite systems (GNSS are usually unavailable in indoor environments. Pedestrian dead reckoning (PDR is a promising localization technique for indoor environments since it can be implemented on widely used smartphones equipped with low cost inertial sensors. However, the PDR localization severely suffers from the accumulation of positioning errors, and other external calibration sources should be used. In this paper, a context-recognition-aided PDR localization model is proposed to calibrate PDR. The context is detected by employing particular human actions or characteristic objects and it is matched to the context pre-stored offline in the database to get the pedestrian’s location. The Hidden Markov Model (HMM and Recursive Viterbi Algorithm are used to do the matching, which reduces the time complexity and saves the storage. In addition, the authors design the turn detection algorithm and take the context of corner as an example to illustrate and verify the proposed model. The experimental results show that the proposed localization method can fix the pedestrian’s starting point quickly and improves the positioning accuracy of PDR by 40.56% at most with perfect stability and robustness at the same time.

  13. Context-Specific Proportion Congruency Effects: An Episodic Learning Account and Computational Model.

    Science.gov (United States)

    Schmidt, James R

    2016-01-01

    In the Stroop task, participants identify the print color of color words. The congruency effect is the observation that response times and errors are increased when the word and color are incongruent (e.g., the word "red" in green ink) relative to when they are congruent (e.g., "red" in red). The proportion congruent (PC) effect is the finding that congruency effects are reduced when trials are mostly incongruent rather than mostly congruent. This PC effect can be context-specific. For instance, if trials are mostly incongruent when presented in one location and mostly congruent when presented in another location, the congruency effect is smaller for the former location. Typically, PC effects are interpreted in terms of strategic control of attention in response to conflict, termed conflict adaptation or conflict monitoring. In the present manuscript, however, an episodic learning account is presented for context-specific proportion congruent (CSPC) effects. In particular, it is argued that context-specific contingency learning can explain part of the effect, and context-specific rhythmic responding can explain the rest. Both contingency-based and temporal-based learning can parsimoniously be conceptualized within an episodic learning framework. An adaptation of the Parallel Episodic Processing model is presented. This model successfully simulates CSPC effects, both for contingency-biased and contingency-unbiased (transfer) items. The same fixed-parameter model can explain a range of other findings from the learning, timing, binding, practice, and attentional control domains.

  14. A Context-Recognition-Aided PDR Localization Method Based on the Hidden Markov Model.

    Science.gov (United States)

    Lu, Yi; Wei, Dongyan; Lai, Qifeng; Li, Wen; Yuan, Hong

    2016-11-30

    Indoor positioning has recently become an important field of interest because global navigation satellite systems (GNSS) are usually unavailable in indoor environments. Pedestrian dead reckoning (PDR) is a promising localization technique for indoor environments since it can be implemented on widely used smartphones equipped with low cost inertial sensors. However, the PDR localization severely suffers from the accumulation of positioning errors, and other external calibration sources should be used. In this paper, a context-recognition-aided PDR localization model is proposed to calibrate PDR. The context is detected by employing particular human actions or characteristic objects and it is matched to the context pre-stored offline in the database to get the pedestrian's location. The Hidden Markov Model (HMM) and Recursive Viterbi Algorithm are used to do the matching, which reduces the time complexity and saves the storage. In addition, the authors design the turn detection algorithm and take the context of corner as an example to illustrate and verify the proposed model. The experimental results show that the proposed localization method can fix the pedestrian's starting point quickly and improves the positioning accuracy of PDR by 40.56% at most with perfect stability and robustness at the same time.

  15. Terminal-Dependent Statistical Inference for the FBSDEs Models

    Directory of Open Access Journals (Sweden)

    Yunquan Song

    2014-01-01

    Full Text Available The original stochastic differential equations (OSDEs and forward-backward stochastic differential equations (FBSDEs are often used to model complex dynamic process that arise in financial, ecological, and many other areas. The main difference between OSDEs and FBSDEs is that the latter is designed to depend on a terminal condition, which is a key factor in some financial and ecological circumstances. It is interesting but challenging to estimate FBSDE parameters from noisy data and the terminal condition. However, to the best of our knowledge, the terminal-dependent statistical inference for such a model has not been explored in the existing literature. We proposed a nonparametric terminal control variables estimation method to address this problem. The reason why we use the terminal control variables is that the newly proposed inference procedures inherit the terminal-dependent characteristic. Through this new proposed method, the estimators of the functional coefficients of the FBSDEs model are obtained. The asymptotic properties of the estimators are also discussed. Simulation studies show that the proposed method gives satisfying estimates for the FBSDE parameters from noisy data and the terminal condition. A simulation is performed to test the feasibility of our method.

  16. Assessing Reading Strategy Training based on CALLA model in EFL and ESL Context

    Directory of Open Access Journals (Sweden)

    Alireza Karbalaei

    2011-04-01

    Full Text Available Reading strategies instruction is currently gaining much attention as an effective means of enhancing reading comprehension. In this research, we examined the effect of Underlining Strategy Intervention, based on the CALLA model in EFL and ESL contexts. A group of 189 college students were randomly selected from different universities in Iran and India. Based on a proficiency test, students were grouped into high, moderate, and low level. Then, the underlining strategy was taught during the treatment sessions. The results suggest that intervention or explicit instruction was effective in increasing the reading comprehension of both Iranian and Indian students although Indian ESL students were able to perform better in comparison to their Iranian EFL counterparts. There was no significant difference between proficiency level and students' performance in reading comprehension in EFL and ESL contexts. In addition, there was no significant difference between males and females in both contexts.

  17. Development of constitutive model for composites exhibiting time dependent properties

    International Nuclear Information System (INIS)

    Pupure, L; Joffe, R; Varna, J; Nyström, B

    2013-01-01

    Regenerated cellulose fibres and their composites exhibit highly nonlinear behaviour. The mechanical response of these materials can be successfully described by the model developed by Schapery for time-dependent materials. However, this model requires input parameters that are experimentally determined via large number of time-consuming tests on the studied composite material. If, for example, the volume fraction of fibres is changed we have a different material and new series of experiments on this new material are required. Therefore the ultimate objective of our studies is to develop model which determines the composite behaviour based on behaviour of constituents of the composite. This paper gives an overview of problems and difficulties, associated with development, implementation and verification of such model

  18. Voter model with arbitrary degree dependence: clout, confidence and irreversibility

    Science.gov (United States)

    Fotouhi, Babak; Rabbat, Michael G.

    2014-03-01

    The voter model is widely used to model opinion dynamics in society. In this paper, we propose three modifications to incorporate heterogeneity into the model. We address the corresponding oversimplifications of the conventional voter model which are unrealistic. We first consider the voter model with popularity bias. The influence of each node on its neighbors depends on its degree. We find the consensus probabilities and expected consensus times for each of the states. We also find the fixation probability, which is the probability that a single node whose state differs from every other node imposes its state on the entire system. In addition, we find the expected fixation time. Then two other extensions to the model are proposed and the motivations behind them are discussed. The first one is confidence, where in addition to the states of neighbors, nodes take their own state into account at each update. We repeat the calculations for the augmented model and investigate the effects of adding confidence to the model. The second proposed extension is irreversibility, where one of the states is given the property that once nodes adopt it, they cannot switch back. This is motivated by applications where, agents take an irreversible action such as seeing a movie, purchasing a music album online, or buying a new product. The dynamics of densities, fixation times and consensus times are obtained.

  19. The Context, Process, and Outcome Evaluation Model for Organisational Health Interventions

    Science.gov (United States)

    Fridrich, Annemarie; Jenny, Gregor J.; Bauer, Georg F.

    2015-01-01

    To facilitate evaluation of complex, organisational health interventions (OHIs), this paper aims at developing a context, process, and outcome (CPO) evaluation model. It builds on previous model developments in the field and advances them by clearly defining and relating generic evaluation categories for OHIs. Context is defined as the underlying frame that influences and is influenced by an OHI. It is further differentiated into the omnibus and discrete contexts. Process is differentiated into the implementation process, as the time-limited enactment of the original intervention plan, and the change process of individual and collective dynamics triggered by the implementation process. These processes lead to proximate, intermediate, and distal outcomes, as all results of the change process that are meaningful for various stakeholders. Research questions that might guide the evaluation of an OHI according to the CPO categories and a list of concrete themes/indicators and methods/sources applied within the evaluation of an OHI project at a hospital in Switzerland illustrate the model's applicability in structuring evaluations of complex OHIs. In conclusion, the model supplies a common language and a shared mental model for improving communication between researchers and company members and will improve the comparability and aggregation of evaluation study results. PMID:26557665

  20. Collaboration of 3D context and extracellular matrix in the development of glioma stemness in a 3D model.

    Science.gov (United States)

    Ma, Nina K L; Lim, Jia Kai; Leong, Meng Fatt; Sandanaraj, Edwin; Ang, Beng Ti; Tang, Carol; Wan, Andrew C A

    2016-02-01

    A hierarchy of cellular stemness exists in certain cancers, and any successful strategy to treat such cancers would have to eliminate the self-renewing tumor-initiating cells at the apex of the hierarchy. The cellular microenvironment, in particular the extracellular matrix (ECM), is believed to have a role in regulating stemness. In this work, U251 glioblastoma cells are cultured on electrospun polystyrene (ESPS) scaffolds coated with an array of 7 laminin isoforms to provide a 3D model for stem cell-related genes and proteins expression studies. We observed collaboration between 3D context and laminins in promoting glioma stemness. Depending on the laminin isoform presented, U251 cells cultured on ESPS scaffolds (3D) exhibited increased expression of stemness markers compared to those cultured on tissue culture polystyrene (2D). Our results indicate the influence of 3D (versus 2D) context on integrin expression, specifically, the upregulation of the laminin-binding integrins alpha 6 and beta 4. By a colony forming assay, we showed enhanced clonogenicity of cells grown on ESPS scaffolds in collaboration with laminins 411, 421, 511 and 521. Evaluation of patient glioma databases demonstrated significant enrichment of integrin and ECM pathway networks in tumors of worse prognosis, consistent with our observations. The present results demonstrate how 3D versus 2D context profoundly affects ECM signaling, leading to stemness. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. The priming of priming: Evidence that the N400 reflects context-dependent post-retrieval word integration in working memory.

    Science.gov (United States)

    Steinhauer, Karsten; Royle, Phaedra; Drury, John E; Fromont, Lauren A

    2017-06-09

    Which cognitive processes are reflected by the N400 in ERPs is still controversial. Various recent articles (Lau et al., 2008; Brouwer et al., 2012) have revived the idea that only lexical pre-activation processes (such as automatic spreading activation, ASA) are strongly supported, while post-lexical integrative processes are not. Challenging this view, the present ERP study replicates a behavioral study by McKoon and Ratcliff (1995) who demonstrated that a prime-target pair such as finger - hand shows stronger priming when a majority of other pairs in the list share the analogous semantic relationship (here: part-whole), even at short stimulus onset asynchronies (250ms). We created lists with four different types of semantic relationship (synonyms, part-whole, category-member, and opposites) and compared priming for pairs in a consistent list with those in an inconsistent list as well as unrelated items. Highly significant N400 reductions were found for both relatedness priming (unrelated vs. inconsistent) and relational priming (inconsistent vs. consistent). These data are taken as strong evidence that N400 priming effects are not exclusively carried by ASA-like mechanisms during lexical retrieval but also include post-lexical integration in working memory. We link the present findings to a neurocomputational model for relational reasoning (Knowlton et al., 2012) and to recent discussions of context-dependent conceptual activations (Yee and Thompson-Schill, 2016). Copyright © 2017 Elsevier B.V. All rights reserved.

  2. AN ANALYSIS OF CONTEXT-AWARE DATA MODELS FOR SMART CITIES: TOWARDS FIWARE AND ETSI CIM EMERGING DATA MODEL

    Directory of Open Access Journals (Sweden)

    A. J. Jara

    2017-09-01

    Full Text Available Smart Cities requires the support of context-aware and enriched semantic descriptions to support a scalable and cross-domain development of smart applications. For example, nowadays general purpose sensors such as crowd monitoring (counting people in an area, environmental information (pollution, air quality, temperature, humidity, noise etc. can be used in multiple solutions with different objectives. For that reason, a data model that offers advanced capabilities for the description of context is required. This paper presents an overview of the available technologies for this purpose and how it is being addressed by the Open and Agile Smart Cities principles and FIWARE platform through the data models defined by the ETSI ISG Context Information Management (ETSI CIM.

  3. An Analysis of Context-Aware Data Models for Smart Cities: Towards Fiware and Etsi Cim Emerging Data Model

    Science.gov (United States)

    Jara, A. J.; Bocchi, Y.; Fernandez, D.; Molina, G.; Gomez, A.

    2017-09-01

    Smart Cities requires the support of context-aware and enriched semantic descriptions to support a scalable and cross-domain development of smart applications. For example, nowadays general purpose sensors such as crowd monitoring (counting people in an area), environmental information (pollution, air quality, temperature, humidity, noise) etc. can be used in multiple solutions with different objectives. For that reason, a data model that offers advanced capabilities for the description of context is required. This paper presents an overview of the available technologies for this purpose and how it is being addressed by the Open and Agile Smart Cities principles and FIWARE platform through the data models defined by the ETSI ISG Context Information Management (ETSI CIM).

  4. A new model dependency ratio for European cities

    Directory of Open Access Journals (Sweden)

    Gianna Zamaro

    2008-09-01

    Full Text Available

    Background: Sometimes referred to as ‘the demographic time bomb,’ the European Union, state and local governments are concerned about the impact of an ageing population on both sustainable economic development and the demand for health and social support services. Seeking to mitigate these pressures, the Organisation for Economic Co-operation and Development (OECD has developed a policy framework Live Longer: Work Longer and the World Health Organization (WHO has set a policy framework for Active Ageing which maintains that early life course interventions can reduce levels of disability and dependency in older age. The WHO European Healthy Cities Network (WHO-EHCN promotes healthy urban planning to encourage healthy lifestyles and maintain older people as a resource in the workplace and to their communities. Our objective is to develop a new model dependency ratio (NMDR for European cities which synthesises these three policy frameworks.

    Methods: Starting from the classic formulation of the dependency ratio (DR, which compares the 'dependent' population segments with the working-age or 'productive' segments, the model is developed in six stages, drawing on data from secondary European and national sources and from primary sources contained in Healthy Ageing Profiles of fifteen (WHO-EHCN cities.

    Results: From an orthodox baseline, the second stage of modelling increases the DR by moving economically inactive people of working age from denominator to numerator. Thereafter, refinements introduced in stages three to six, gradually reduce the DR.

    Conclusions: The NMDR challenges the 'demographic time bomb' predicted by orthodox formulations and can be used as a tool by city decision makers.

  5. The relationship between the neural computations for speech and music perception is context-dependent: an activation likelihood estimate study

    Directory of Open Access Journals (Sweden)

    Arianna eLaCroix

    2015-08-01

    Full Text Available The relationship between the neurobiology of speech and music has been investigated for more than a century. There remains no widespread agreement regarding how (or to what extent music perception utilizes the neural circuitry that is engaged in speech processing, particularly at the cortical level. Prominent models such as Patel’s Shared Syntactic Integration Resource Hypothesis (SSIRH and Koelsch’s neurocognitive model of music perception suggest a high degree of overlap, particularly in the frontal lobe, but also perhaps more distinct representations in the temporal lobe with hemispheric asymmetries. The present meta-analysis study used activation likelihood estimate analyses to identify the brain regions consistently activated for music as compared to speech across the functional neuroimaging (fMRI and PET literature. Eighty music and 91 speech neuroimaging studies of healthy adult control subjects were analyzed. Peak activations reported in the music and speech studies were divided into four paradigm categories: passive listening, discrimination tasks, error/anomaly detection tasks and memory-related tasks. We then compared activation likelihood estimates within each category for music versus speech, and each music condition with passive listening. We found that listening to music and to speech preferentially activate distinct temporo-parietal bilateral cortical networks. We also found music and speech to have shared resources in the left pars opercularis but speech-specific resources in the left pars triangularis. The extent to which music recruited speech-activated frontal resources was modulated by task. While there are certainly limitations to meta-analysis techniques particularly regarding sensitivity, this work suggests that the extent of shared resources between speech and music may be task-dependent and highlights the need to consider how task effects may be affecting conclusions regarding the neurobiology of speech and music.

  6. Density-dependent microbial turnover improves soil carbon model predictions of long-term litter manipulations

    Science.gov (United States)

    Georgiou, Katerina; Abramoff, Rose; Harte, John; Riley, William; Torn, Margaret

    2017-04-01

    Climatic, atmospheric, and land-use changes all have the potential to alter soil microbial activity via abiotic effects on soil or mediated by changes in plant inputs. Recently, many promising microbial models of soil organic carbon (SOC) decomposition have been proposed to advance understanding and prediction of climate and carbon (C) feedbacks. Most of these models, however, exhibit unrealistic oscillatory behavior and SOC insensitivity to long-term changes in C inputs. Here we diagnose the sources of instability in four models that span the range of complexity of these recent microbial models, by sequentially adding complexity to a simple model to include microbial physiology, a mineral sorption isotherm, and enzyme dynamics. We propose a formulation that introduces density-dependence of microbial turnover, which acts to limit population sizes and reduce oscillations. We compare these models to results from 24 long-term C-input field manipulations, including the Detritus Input and Removal Treatment (DIRT) experiments, to show that there are clear metrics that can be used to distinguish and validate the inherent dynamics of each model structure. We find that widely used first-order models and microbial models without density-dependence cannot readily capture the range of long-term responses observed across the DIRT experiments as a direct consequence of their model structures. The proposed formulation improves predictions of long-term C-input changes, and implies greater SOC storage associated with CO2-fertilization-driven increases in C inputs over the coming century compared to common microbial models. Finally, we discuss our findings in the context of improving microbial model behavior for inclusion in Earth System Models.

  7. TIME-DEPENDENT MODELS OF FLARES FROM SAGITTARIUS A*

    International Nuclear Information System (INIS)

    Dodds-Eden, Katie; Genzel, Reinhard; Gillessen, Stefan; Eisenhauer, Frank; Sharma, Prateek; Quataert, Eliot; Porquet, Delphine

    2010-01-01

    The emission from Sgr A*, the supermassive black hole in the Galactic Center, shows order of magnitude variability ('flares') a few times a day that is particularly prominent in the near-infrared (NIR) and X-rays. We present a time-dependent model for these flares motivated by the hypothesis that dissipation of magnetic energy powers the flares. We show that episodic magnetic reconnection can occur near the last stable circular orbit in time-dependent magnetohydrodynamic simulations of black hole accretion-the timescales and energetics of these events are broadly consistent with the flares from Sgr A*. Motivated by these results, we present a spatially one-zone time-dependent model for the electron distribution function in flares, including energy loss due to synchrotron cooling and adiabatic expansion. Synchrotron emission from transiently accelerated particles can explain the NIR/X-ray light curves and spectra of a luminous flare observed on 2007 April 4. A significant decrease in the magnetic field strength during the flare (coincident with the electron acceleration) is required to explain the simultaneity and symmetry of the simultaneous light curves. Our models predict that the NIR and X-ray spectral indices are related by Δα ≅ 0.5 (where νF ν ∝ ν α ) and that there is only modest variation in the spectral index during flares. We also explore implications of this model for longer wavelength (radio-submillimeter) emission seemingly associated with X-ray and NIR flares; we argue that a few hour decrease in the submillimeter emission is a more generic consequence of large-scale magnetic reconnection than delayed radio emission from adiabatic expansion.

  8. From the Stimulus-Response to the Person-Context Model

    Directory of Open Access Journals (Sweden)

    Arturo Barraza Macías

    2007-07-01

    Full Text Available In this manuscript, an alternative reading of the field of study of the stress is made that leads to raise the existence of two models: the Stimulus-Response and the Person-Context Models about Stress. Each one of them is presented with base in four indicators: historical antecedents, postulates, development and characteristics. In the end a critical valuation is made that the author leads to recognize in the Person-Surroundings Research Program of Stress, and in its tendency to the modeling, the route of development of the field of study of stress.

  9. Computable general equilibrium modelling in the context of trade and environmental policy

    International Nuclear Information System (INIS)

    Koesler, Simon Tobias

    2014-01-01

    This thesis is dedicated to the evaluation of environmental policies in the context of climate change. Its objectives are twofold. Its first part is devoted to the development of potent instruments for quantitative impact analysis of environmental policy. In this context, the main contributions include the development of a new computable general equilibrium (CGE) model which makes use of the new comprehensive and coherent World Input-Output Dataset (WIOD) and which features a detailed representation of bilateral and bisectoral trade flows. Moreover it features an investigation of input substitutability to provide modellers with adequate estimates for key elasticities as well as a discussion and amelioration of the standard base year calibration procedure of most CGE models. Building on these tools, the second part applies the improved modelling framework and studies the economic implications of environmental policy. This includes an analysis of so called rebound effects, which are triggered by energy efficiency improvements and reduce their net benefit, an investigation of how firms restructure their production processes in the presence of carbon pricing mechanisms, and an analysis of a regional maritime emission trading scheme as one of the possible options to reduce emissions of international shipping in the EU context.

  10. Highchair Philosophers: The Impact of Seating Context-Dependent Exploration on Children's Naming Biases

    Science.gov (United States)

    Perry, Lynn K.; Samuelson, Larissa K.; Burdinie, Johanna B.

    2014-01-01

    We examine developmental interactions between context, exploration, and word learning. Infants show an understanding of how nonsolid substances are categorized that does not reliably transfer to learning how these categories are named in laboratory tasks. We argue that what infants learn about naming nonsolid substances is contextually bound--most…

  11. Modeling multisite streamflow dependence with maximum entropy copula

    Science.gov (United States)

    Hao, Z.; Singh, V. P.

    2013-10-01

    Synthetic streamflows at different sites in a river basin are needed for planning, operation, and management of water resources projects. Modeling the temporal and spatial dependence structure of monthly streamflow at different sites is generally required. In this study, the maximum entropy copula method is proposed for multisite monthly streamflow simulation, in which the temporal and spatial dependence structure is imposed as constraints to derive the maximum entropy copula. The monthly streamflows at different sites are then generated by sampling from the conditional distribution. A case study for the generation of monthly streamflow at three sites in the Colorado River basin illustrates the application of the proposed method. Simulated streamflow from the maximum entropy copula is in satisfactory agreement with observed streamflow.

  12. Model Penjadwalan Batch Multi Item dengan Dependent Processing Time

    Directory of Open Access Journals (Sweden)

    Sukoyo Sukoyo

    2010-01-01

    Full Text Available This paper investigates a development of single machine batch scheduling for multi items with dependent processing time. The batch scheduling problem is to determine simultaneously number of batch (N, which item and its size allocated for each batch, and processing sequences of resulting batches. We use total actual flow time as the objective of schedule performance. The multi item batch scheduling problem could be formulated into a biner-integer nonlinear programming model because the number of batch should be in integer value, the allocation of items to resulting batch need binary values, and also there are some non-linearity on objective function and constraint due to the dependent processing time. By applying relaxation on the decision variable of number of batch (N as parameter, a heuristic procedure could be applied to find solution of the single machine batch scheduling problem for multi items.

  13. Analysis of local dependence and multidimensionality in graphical loglinear Rasch models

    DEFF Research Database (Denmark)

    Kreiner, Svend; Christensen, Karl Bang

    local independence; multidimensionality, differential item functioning; uniform local dependency and DIF; graphical Rasch models; loglinear Rasch models......local independence; multidimensionality, differential item functioning; uniform local dependency and DIF; graphical Rasch models; loglinear Rasch models...

  14. Analysis of Local Dependence and Multidimensionality in Graphical Loglinear Rasch Models

    DEFF Research Database (Denmark)

    Kreiner, Svend; Christensen, Karl Bang

    2004-01-01

    Local independence; Multidimensionality; Differential item functioning; Uniform local dependence and DIF; Graphical Rasch models; Loglinear Rasch model......Local independence; Multidimensionality; Differential item functioning; Uniform local dependence and DIF; Graphical Rasch models; Loglinear Rasch model...

  15. Assessing Reading Strategy Training based on CALLA model in EFL and ESL Context

    OpenAIRE

    Alireza Karbalaei

    2011-01-01

    Reading strategies instruction is currently gaining much attention as an effective means of enhancing reading comprehension. In this research, we examined the effect of Underlining Strategy Intervention, based on the CALLA model in EFL and ESL contexts. A group of 189 college students were randomly selected from different universities in Iran and India. Based on a proficiency test, students were grouped into high, moderate, and low level. Then, the underlining strategy was taught during the t...

  16. Communication: Modeling electrolyte mixtures with concentration dependent dielectric permittivity

    Science.gov (United States)

    Chen, Hsieh; Panagiotopoulos, Athanassios Z.

    2018-01-01

    We report a new implicit-solvent simulation model for electrolyte mixtures based on the concept of concentration dependent dielectric permittivity. A combining rule is found to predict the dielectric permittivity of electrolyte mixtures based on the experimentally measured dielectric permittivity for pure electrolytes as well as the mole fractions of the electrolytes in mixtures. Using grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to accurately reproduce the mean ionic activity coefficients of NaCl in NaCl-CaCl2 mixtures at ionic strengths up to I = 3M. These results are important for thermodynamic studies of geologically relevant brines and physiological fluids.

  17. NEW MODEL FOR QUANTIFICATION OF ICT DEPENDABLE ORGANIZATIONS RESILIENCE

    Directory of Open Access Journals (Sweden)

    Zora Arsovski

    2011-03-01

    Full Text Available Business environment today demands high reliable organizations in every segment to be competitive on the global market. Beside that, ICT sector is becoming irreplaceable in many fields of business, from the communication to the complex systems for process control and production. To fulfill those requirements and to develop further, many organizations worldwide are implementing business paradigm called - organizations resilience. Although resilience is well known term in many science fields, it is not well studied due to its complex nature. This paper is dealing with developing the new model for assessment and quantification of ICT dependable organizations resilience.

  18. Modelling interactions of toxicants and density dependence in wildlife populations

    Science.gov (United States)

    Schipper, Aafke M.; Hendriks, Harrie W.M.; Kauffman, Matthew J.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2013-01-01

    1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to

  19. Indoor Localisation Using a Context-Aware Dynamic Position Tracking Model

    Directory of Open Access Journals (Sweden)

    Montserrat Ros

    2012-01-01

    Full Text Available Indoor wireless localisation is a widely sought feature for use in logistics, health, and social networking applications. Low-powered localisation will become important for the next generation of pervasive media applications that operate on mobile platforms. We present an inexpensive and robust context-aware tracking system that can track the position of users in an indoor environment, using a wireless smart meter network. Our context-aware tracking system combines wireless trilateration with a dynamic position tracking model and a probability density map to estimate indoor positions. The localisation network consisted of power meter nodes placed at known positions in a building. The power meter nodes are tracked by mobile nodes which are carried by users to localise their position. We conducted an extensive trial of the context-aware tracking system and performed a comparison analysis with existing localisation techniques. The context-aware tracking system was able to localise a person's indoor position with an average error of 1.21 m.

  20. Analyzing the pathways enriched in genes associated with nicotine dependence in the context of human protein-protein interaction network.

    Science.gov (United States)

    Hu, Ying; Fang, Zhonghai; Yang, Yichen; Fan, Ting; Wang, Ju

    2018-03-16

    Nicotine dependence is the primary addictive stage of cigarette smoking. Although a lot of studies have been performed to explore the molecular mechanism underlying nicotine dependence, our understanding on this disorder is still far from complete. Over the past decades, an increasing number of candidate genes involved in nicotine dependence have been identified by different technical approaches, including the genetic association analysis. In this study, we performed a comprehensive collection of candidate genes reported to be genetically associated with nicotine dependence. Then, the biochemical pathways enriched in these genes were identified by considering the gene's propensity to be related to nicotine dependence. One of the most widely used pathway enrichment analysis approach, over-representation analysis, ignores the function non-equivalence of genes in candidate gene set and may have low discriminative power in identifying some dysfunctional pathways. To overcome such drawbacks, we constructed a comprehensive human protein-protein interaction network, and then assigned a function weighting score to each candidate gene based on their network topological features. Evaluation indicated the function weighting score scheme was consistent with available evidence. Finally, the function weighting scores of the candidate genes were incorporated into pathway analysis to identify the dysfunctional pathways involved in nicotine dependence, and the interactions between pathways was detected by pathway crosstalk analysis. Compared to conventional over-representation based pathway analysis tool, the modified method exhibited improved discriminative power and detected some novel pathways potentially underlying nicotine dependence. In summary, we conducted a comprehensive collection of genes associated with nicotine dependence and then detected the biochemical pathways enriched in these genes using a modified pathway enrichment analysis approach with function weighting

  1. A person-task-context model for designing curriculum and in-training assessment in postgraduate education

    DEFF Research Database (Denmark)

    Skaarup, Anne Marie; Ringsted, Charlotte Vibeke; Henriksen, Ann-Helen

    2006-01-01

    The aim of this study was to trial a person-task-context model in designing a curriculum and in-training assessment programme that embraces trainee level of professional development and the work-based context of postgraduate medical education. The model was applied to the design of a programme...

  2. Fuzzy economic production quantity model with time dependent demand rate

    Directory of Open Access Journals (Sweden)

    Susanta Kumar Indrajitsingha

    2016-09-01

    Full Text Available Background: In this paper, an economic production quantity model is considered under a fuzzy environment. Both the demand cost and holding cost are considered using fuzzy pentagonal numbers. The Signed Distance Method is used to defuzzify the total cost function. Methods: The results obtained by these methods are compared with the help of a numerical example. Sensitivity analysis is also carried out to explore the effect of changes in the values of some of the system parameters. Results and conclusions: The fuzzy EPQ model with time dependent demand rate was presented together with the possible implementation. The behavior of changes in parameters was analyzed. The possible extension of the implementation of this method was presented.

  3. Model for thickness dependence of radiation charging in MOS structures

    Science.gov (United States)

    Viswanathan, C. R.; Maserjian, J.

    1976-01-01

    The model considers charge buildup in MOS structures due to hole trapping in the oxide and the creation of sheet charge at the silicon interface. The contribution of hole trapping causes the flatband voltage to increase with thickness in a manner in which square and cube dependences are limiting cases. Experimental measurements on samples covering a 200 - 1000 A range of oxide thickness are consistent with the model, using independently obtained values of hole-trapping parameters. An important finding of our experimental results is that a negative interface charge contribution due to surface states created during irradiation compensates most of the positive charge in the oxide at flatband. The tendency of the surface states to 'track' the positive charge buildup in the oxide, for all thicknesses, applies both in creation during irradiation and in annihilation during annealing. An explanation is proposed based on the common defect origin of hole traps and potential surface states.

  4. Computational modeling of geometry dependent phonon transport in silicon nanostructures

    Science.gov (United States)

    Cheney, Drew A.

    Recent experiments have demonstrated that thermal properties of semiconductor nanostructures depend on nanostructure boundary geometry. Phonons are quantized mechanical vibrations that are the dominant carrier of heat in semiconductor materials and their aggregate behavior determine a nanostructure's thermal performance. Phonon-geometry scattering processes as well as waveguiding effects which result from coherent phonon interference are responsible for the shape dependence of thermal transport in these systems. Nanoscale phonon-geometry interactions provide a mechanism by which nanostructure geometry may be used to create materials with targeted thermal properties. However, the ability to manipulate material thermal properties via controlling nanostructure geometry is contingent upon first obtaining increased theoretical understanding of fundamental geometry induced phonon scattering processes and having robust analytical and computational models capable of exploring the nanostructure design space, simulating the phonon scattering events, and linking the behavior of individual phonon modes to overall thermal behavior. The overall goal of this research is to predict and analyze the effect of nanostructure geometry on thermal transport. To this end, a harmonic lattice-dynamics based atomistic computational modeling tool was created to calculate phonon spectra and modal phonon transmission coefficients in geometrically irregular nanostructures. The computational tool is used to evaluate the accuracy and regimes of applicability of alternative computational techniques based upon continuum elastic wave theory. The model is also used to investigate phonon transmission and thermal conductance in diameter modulated silicon nanowires. Motivated by the complexity of the transmission results, a simplified model based upon long wavelength beam theory was derived and helps explain geometry induced phonon scattering of low frequency nanowire phonon modes.

  5. A multicriteria decision making model for assessment and selection of an ERP in a logistics context

    Science.gov (United States)

    Pereira, Teresa; Ferreira, Fernanda A.

    2017-07-01

    The aim of this work is to apply a methodology of decision support based on a multicriteria decision analyses (MCDA) model that allows the assessment and selection of an Enterprise Resource Planning (ERP) in a Portuguese logistics company by Group Decision Maker (GDM). A Decision Support system (DSS) that implements a MCDA - Multicriteria Methodology for the Assessment and Selection of Information Systems / Information Technologies (MMASSI / IT) is used based on its features and facility to change and adapt the model to a given scope. Using this DSS it was obtained the information system that best suited to the decisional context, being this result evaluated through a sensitivity and robustness analysis.

  6. Mobility dependent recombination models for organic solar cells

    Science.gov (United States)

    Wagenpfahl, Alexander

    2017-09-01

    Modern solar cell technologies are driven by the effort to enhance power conversion efficiencies. A main mechanism limiting power conversion efficiencies is charge carrier recombination which is a direct function of the encounter probability of both recombination partners. In inorganic solar cells with rather high charge carrier mobilities, charge carrier recombination is often dominated by energetic states which subsequently trap both recombination partners for recombination. Free charge carriers move fast enough for Coulomb attraction to be irrelevant for the encounter probability. Thus, charge carrier recombination is independent of charge carrier mobilities. In organic semiconductors charge carrier mobilities are much lower. Therefore, electrons and holes have more time react to mutual Coulomb-forces. This results in the strong charge carrier mobility dependencies of the observed charge carrier recombination rates. In 1903 Paul Langevin published a fundamental model to describe the recombination of ions in gas-phase or aqueous solutions, known today as Langevin recombination. During the last decades this model was used to interpret and model recombination in organic semiconductors. However, certain experiments especially with bulk-heterojunction solar cells reveal much lower recombination rates than predicted by Langevin. In search of an explanation, many material and device properties such as morphology and energetic properties have been examined in order to extend the validity of the Langevin model. A key argument for most of these extended models is, that electron and hole must find each other at a mutual spatial location. This encounter may be limited for instance by trapping of charges in trap states, by selective electrodes separating electrons and holes, or simply by the morphology of the involved semiconductors, making it impossible for electrons and holes to recombine at high rates. In this review, we discuss the development of mobility limited

  7. Investigating students’ mental models about the nature of light in different contexts

    Science.gov (United States)

    Özcan, Özgür

    2015-11-01

    In this study, we investigated pre-service physics teachers’ mental models of light in different contexts, such as blackbody radiation, the photoelectric effect and the Compton effect. The data collected through the paper-and-pencil questionnaire (PPQ) were analyzed both quantitatively and qualitatively. Sampling of this study consists of a total of 110 physics education students who were taking a modern physics course at two different state universities in Turkey. As a result, three mental models, which were called the beam ray model (BrM), hybrid model (HM) and particle model (PM), were being used by the students while explaining these phenomena. The most model fluctuation was seen in HM and BrM. In addition, some students were in a mixed-model state where they use multiple mental models in explaining a phenomenon and used these models inconsistently. On the other hand, most of the students who used the particle model can be said to be in a pure model state.

  8. Modeling Battery Behavior on Sensory Operations for Context-Aware Smartphone Sensing

    Directory of Open Access Journals (Sweden)

    Ozgur Yurur

    2015-05-01

    Full Text Available Energy consumption is a major concern in context-aware smartphone sensing. This paper first studies mobile device-based battery modeling, which adopts the kinetic battery model (KiBaM, under the scope of battery non-linearities with respect to variant loads. Second, this paper models the energy consumption behavior of accelerometers analytically and then provides extensive simulation results and a smartphone application to examine the proposed sensor model. Third, a Markov reward process is integrated to create energy consumption profiles, linking with sensory operations and their effects on battery non-linearity. Energy consumption profiles consist of different pairs of duty cycles and sampling frequencies during sensory operations. Furthermore, the total energy cost by each profile is represented by an accumulated reward in this process. Finally, three different methods are proposed on the evolution of the reward process, to present the linkage between different usage patterns on the accelerometer sensor through a smartphone application and the battery behavior. By doing this, this paper aims at achieving a fine efficiency in power consumption caused by sensory operations, while maintaining the accuracy of smartphone applications based on sensor usages. More importantly, this study intends that modeling the battery non-linearities together with investigating the effects of different usage patterns in sensory operations in terms of the power consumption and the battery discharge may lead to discovering optimal energy reduction strategies to extend the battery lifetime and help a continual improvement in context-aware mobile services.

  9. Leader emotional intelligence, transformational leadership, trust and team commitment: Testing a model within a team context

    Directory of Open Access Journals (Sweden)

    Anton F. Schlechter

    2008-06-01

    Full Text Available This exploratory study tested a model within a team context consisting of transformational-leadership behaviour, team-leader emotional intelligence, trust (both in the team leader and in the team members and team commitment. It was conducted within six manufacturing plants, with 25 teams participating. Of the 320 surveys distributed to these teams, 178 were received (which equals a 56% response rate. The surveys consisted of the multi-factor leadership questionnaire (MLQ, the Swinburne University emotional intelligence test (SUEIT, the organisational-commitment scale (OCS (adapted for team commitment and the workplace trust survey (WTS. The validity of these scales was established using exploratory factor analysis (EFA and confrmatory factor analysis (CFA. The Cronbach alpha was used to assess the reliability of the scales. The model was tested using structural equation modelling (SEM; an acceptable level of model ft was found. Signifcant positive relationships were further found among all the constructs. Such an integrated model has not been tested in a team context before and the positive fndings therefore add to existing teamwork literature. The fnding that transformational leadership and leader emotional intelligence are positively related to team commitment and trust further emphasises the importance of effective leadership behaviour in team dynamics and performance.

  10. A Simple Technique For Visualising Three Dimensional Models in Landscape Contexts

    Directory of Open Access Journals (Sweden)

    Stuart Jeffrey

    2001-05-01

    Full Text Available One of the Scottish Early Medieval Sculptured Stones project (SEMSS project's objectives is to generate accurate three dimensional models of these monuments using a variety of data capture techniques from photogrammetry to Time of Flight laser measurement. As the landscape context of these monuments is often considered crucial to their understanding, the model's ultimate presentation to the user should include some level of contextual information. In addition there are a number of presentation issues that must be considered such as interactivity, the relationship of reconstructed to non-reconstructed sections, lighting and suitability for presentation over the WWW. This article discusses the problem of presenting three dimensional models of monumental stones in their landscape contexts. This problem is discussed in general, but special attention is paid to the difficulty of capturing landscape detail,interactivity, reconstructing landscapes and providing accurate representations of landscapes to the horizon. Comparison is made between 3D modelling packages and Internet specific presentation formats such as VRML and QTVR. The proposed technique provides some level of interactivity as well as photorealistic landscape representation extended to the horizon, without the need for a complete DEM/DTM, thereby making file sizes manageable and capable of WWW presentation. It also allows for the issues outlined to be tackled in a more efficient manner than by using either 3D modelling or QTVR on their own.

  11. Modeling battery behavior on sensory operations for context-aware smartphone sensing.

    Science.gov (United States)

    Yurur, Ozgur; Liu, Chi Harold; Moreno, Wilfrido

    2015-05-26

    Energy consumption is a major concern in context-aware smartphone sensing. This paper first studies mobile device-based battery modeling, which adopts the kinetic battery model (KiBaM), under the scope of battery non-linearities with respect to variant loads. Second, this paper models the energy consumption behavior of accelerometers analytically and then provides extensive simulation results and a smartphone application to examine the proposed sensor model. Third, a Markov reward process is integrated to create energy consumption profiles, linking with sensory operations and their effects on battery non-linearity. Energy consumption profiles consist of different pairs of duty cycles and sampling frequencies during sensory operations. Furthermore, the total energy cost by each profile is represented by an accumulated reward in this process. Finally, three different methods are proposed on the evolution of the reward process, to present the linkage between different usage patterns on the accelerometer sensor through a smartphone application and the battery behavior. By doing this, this paper aims at achieving a fine efficiency in power consumption caused by sensory operations, while maintaining the accuracy of smartphone applications based on sensor usages. More importantly, this study intends that modeling the battery non-linearities together with investigating the effects of different usage patterns in sensory operations in terms of the power consumption and the battery discharge may lead to discovering optimal energy reduction strategies to extend the battery lifetime and help a continual improvement in context-aware mobile services.

  12. Leader emotional intelligence, transformational leadership, trust and team commitment: Testing a model within a team context

    Directory of Open Access Journals (Sweden)

    Anton F. Schlechter

    2008-09-01

    Full Text Available This exploratory study tested a model within a team context consisting of transformational-leadership behaviour, team-leader emotional intelligence, trust (both in the team leader and in the team members and team commitment. It was conducted within six manufacturing plants, with 25 teams participating. Of the 320 surveys distributed to these teams, 178 were received (which equals a 56% response rate. The surveys consisted of the multi-factor leadership questionnaire (MLQ, the Swinburne University emotional intelligence test (SUEIT, the organisational-commitment scale (OCS (adapted for team commitment and the workplace trust survey (WTS. The validity of these scales was established using exploratory factor analysis (EFA and confrmatory factor analysis (CFA. The Cronbach alpha was used to assess the reliability of the scales. The model was tested using structural equation modelling (SEM; an acceptable level of model ft was found. Signifcant positive relationships were further found among all the constructs. Such an integrated model has not been tested in a team context before and the positive fndings therefore add to existing teamwork literature. The fnding that transformational leadership and leader emotional intelligence are positively related to team commitment and trust further emphasises the importance of effective leadership behaviour in team dynamics and performance.

  13. A comprehensive approach to age-dependent dosimetric modeling

    Energy Technology Data Exchange (ETDEWEB)

    Leggett, R.W.; Cristy, M.; Eckerman, K.F.

    1986-01-01

    In the absence of age-specific biokinetic models, current retention models of the International Commission on Radiological Protection (ICRP) frequently are used as a point of departure for evaluation of exposures to the general population. These models were designed and intended for estimation of long-term integrated doses to the adult worker. Their format and empirical basis preclude incorporation of much valuable physiological information and physiologically reasonable assumptions that could be used in characterizing the age-specific behavior of radioelements in humans. In this paper we discuss a comprehensive approach to age-dependent dosimetric modeling in which consideration is given not only to changes with age in masses and relative geometries of body organs and tissues but also to best available physiological and radiobiological information relating to the age-specific biobehavior of radionuclides. This approach is useful in obtaining more accurate estimates of long-term dose commitments as a function of age at intake, but it may be particularly valuable in establishing more accurate estimates of dose rate as a function of age. Age-specific dose rates are needed for a proper analysis of the potential effects on estimates or risk of elevated dose rates per unit intake in certain stages of life, elevated response per unit dose received during some stages of life, and age-specific non-radiogenic competing risks.

  14. A comprehensive approach to age-dependent dosimetric modeling

    International Nuclear Information System (INIS)

    Leggett, R.W.; Cristy, M.; Eckerman, K.F.

    1986-01-01

    In the absence of age-specific biokinetic models, current retention models of the International Commission on Radiological Protection (ICRP) frequently are used as a point of departure for evaluation of exposures to the general population. These models were designed and intended for estimation of long-term integrated doses to the adult worker. Their format and empirical basis preclude incorporation of much valuable physiological information and physiologically reasonable assumptions that could be used in characterizing the age-specific behavior of radioelements in humans. In this paper we discuss a comprehensive approach to age-dependent dosimetric modeling in which consideration is given not only to changes with age in masses and relative geometries of body organs and tissues but also to best available physiological and radiobiological information relating to the age-specific biobehavior of radionuclides. This approach is useful in obtaining more accurate estimates of long-term dose commitments as a function of age at intake, but it may be particularly valuable in establishing more accurate estimates of dose rate as a function of age. Age-specific dose rates are needed for a proper analysis of the potential effects on estimates or risk of elevated dose rates per unit intake in certain stages of life, elevated response per unit dose received during some stages of life, and age-specific non-radiogenic competing risks

  15. An inventory control model for biomass dependent production systems

    International Nuclear Information System (INIS)

    Grado, S.C.; Strauss, C.H.

    1993-01-01

    The financial performance of a biomass dependent production system was critiqued based on the development and validation of an inventory control model. Dynamic programming was used to examine the constraints and capabilities of producing ethanol from various biomass crops. In particular, the model evaluated the plantation, harvest, and manufacturing components of a woody biomass supply system. The optimum wood to ethanol production scheme produced 38 million litres of ethanol in the harvest year, at 13.6 million litre increase over the least optimal policy as demonstrated in the dynamic programming results. The system produced ethanol at a delivered cost of $0.38 L -1 which was consistent with the unit costs from other studies. Nearly 60% of the delivered costs were in ethanol production. The remaining costs were attributed to growing biomass (14%), harvest and shipment of the crop (18%), storage of the raw material and finished product (7%) and open-quotes lost salesclose quotes (2%). Inventory control, in all phases of production, proved to be an important cost consideration throughout the model. The model also analyzed the employment of alternative harvesting policies and the use of different or multiple feedstocks. A comparison between the least cost wood system and an even cut wood system further revealed the benefits of using an inventory control system

  16. Understanding Prospective Teachers' Mathematical Modeling Processes in the Context of a Mathematical Modeling Course

    Science.gov (United States)

    Zeytun, Aysel Sen; Cetinkaya, Bulent; Erbas, Ayhan Kursat

    2017-01-01

    This paper investigates how prospective teachers develop mathematical models while they engage in modeling tasks. The study was conducted in an undergraduate elective course aiming to improve prospective teachers' mathematical modeling abilities, while enhancing their pedagogical knowledge for the integrating of modeling tasks into their future…

  17. Cognitive and social learning models of drug dependence: implications for the assessment of tobacco dependence in adolescents.

    Science.gov (United States)

    Brandon, Thomas H; Herzog, Thaddeus A; Irvin, Jennifer E; Gwaltney, Chad J

    2004-06-01

    This paper is part of a series that has the goal of identifying potential approaches toward developing new instruments for assessing tobacco dependence among adolescents. The fundamental assumption underlying the series is that contemporary theories of drug dependence offer a rich source of opportunities for the development of theoretically based assessment tools. The present paper focuses on cognitive and social-learning models of drug dependence and the implications of these models for novel assessment instruments. In particular, the paper focuses on Mark Goldman's model of drug expectancies, Albert Bandura's model of self-efficacy, Thomas Wills's model of stress and coping and Stephen Tiffany's cognitive-processing model of drug urges and cravings. In addition to traditional self-report measures, naturalistic and laboratory-based assessments are identified that may yield information relevant to multi-dimensional measurement of tobacco dependence.

  18. Sex-specific modulation of juvenile social play behavior by vasopressin and oxytocin depends on social context

    Science.gov (United States)

    Bredewold, Remco; Smith, Caroline J. W.; Dumais, Kelly M.; Veenema, Alexa H.

    2014-01-01

    We recently demonstrated that vasopressin (AVP) in the lateral septum modulates social play behavior differently in male and female juvenile rats. However, the extent to which different social contexts (i.e., exposure to an unfamiliar play partner in different environments) affect the regulation of social play remains largely unknown. Given that AVP and the closely related neuropeptide oxytocin (OXT) modulate social behavior as well as anxiety-like behavior, we hypothesized that these neuropeptides may regulate social play behavior differently in novel (novel cage) as opposed to familiar (home cage) social environments. Administration of the specific AVP V1a receptor (V1aR) antagonist (CH2)5Tyr(Me2)AVP into the lateral septum enhanced home cage social play behavior in males but reduced it in females, confirming our previous findings. These effects were context-specific because V1aR blockade did not alter novel cage social play behavior in either sex. Furthermore, social play in females was reduced by AVP in the novel cage and by OXT in the home cage. Additionally, females administered the specific OXT receptor antagonist desGly-NH2,d(CH2)5−[Tyr(Me)2,Thr4]OVT showed less social play in the novel as compared to the home cage. AVP enhanced anxiety-related behavior in males (tested on the elevated plus-maze), but failed to do so in females, suggesting that exogenous AVP alters social play and anxiety-related behavior via distinct and sex-specific mechanisms. Moreover, none of the other drug treatments that altered social play had an effect on anxiety, suggesting that these drug-induced behavioral alterations are relatively specific to social behavior. Overall, we showed that AVP and OXT systems in the lateral septum modulate social play in juvenile rats in neuropeptide-, sex- and social context-specific ways. These findings underscore the importance of considering not only sex, but also social context, in how AVP and OXT modulate social behavior. PMID:24982623

  19. Sex-specific modulation of juvenile social play behavior by vasopressin and oxytocin depends on social context

    Directory of Open Access Journals (Sweden)

    Remco eBredewold

    2014-06-01

    Full Text Available We recently demonstrated that vasopressin (AVP in the lateral septum modulates social play behavior differently in male and female juvenile rats. However, the extent to which different social contexts (i.e., exposure to an unfamiliar play partner in different environments affect the regulation of social play remains largely unknown. Given that AVP and the closely related neuropeptide oxytocin (OXT modulate social behavior as well as anxiety-like behavior, we hypothesized that these neuropeptides may regulate social play behavior differently in novel (novel cage as opposed to familiar (home cage social environments. Administration of the specific AVP V1a receptor (V1aR antagonist (CH25Tyr(Me2AVP into the lateral septum enhanced home cage social play behavior in males but reduced it in females, confirming our previous findings. These effects were context-specific because V1aR blockade did not alter novel cage social play behavior in either sex. Furthermore, social play in females was reduced by AVP in the novel cage and by OXT in the home cage. Additionally, females administered the specific OXT receptor antagonist desGly-NH2,d(CH25-[Tyr(Me2,Thr4]OVT showed less social play in the novel as compared to the home cage. AVP enhanced anxiety-related behavior in males (tested on the elevated plus-maze, but failed to do so in females, suggesting that exogenous AVP alters social play and anxiety-related behavior via distinct and sex-specific mechanisms. Moreover, none of the other drug treatments that altered social play had an effect on anxiety, suggesting that these drug-induced behavioral alterations are relatively specific to social behavior. Overall, we showed that AVP and OXT systems in the lateral septum modulate social play in juvenile rats in neuropeptide-, sex- and social context-specific ways. These findings underscore the importance of considering not only sex, but also social context, in how AVP and OXT modulate social behavior.

  20. Putting structure into context: fitting of atomic models into electron microscopic and electron tomographic reconstructions.

    Science.gov (United States)

    Volkmann, Niels

    2012-02-01

    A complete understanding of complex dynamic cellular processes such as cell migration or cell adhesion requires the integration of atomic level structural information into the larger cellular context. While direct atomic-level information at the cellular level remains inaccessible, electron microscopy, electron tomography and their associated computational image processing approaches have now matured to a point where sub-cellular structures can be imaged in three dimensions at the nanometer scale. Atomic-resolution information obtained by other means can be combined with this data to obtain three-dimensional models of large macromolecular assemblies in their cellular context. This article summarizes some recent advances in this field. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Evaluation of soft segment modeling on a context independent phoneme classification system

    International Nuclear Information System (INIS)

    Razzazi, F.; Sayadiyan, A.

    2007-01-01

    The geometric distribution of states duration is one of the main performance limiting assumptions of hidden Markov modeling of speech signals. Stochastic segment models, generally, and segmental HMM, specifically overcome this deficiency partly at the cost of more complexity in both training and recognition phases. In addition to this assumption, the gradual temporal changes of speech statistics has not been modeled in HMM. In this paper, a new duration modeling approach is presented. The main idea of the model is to consider the effect of adjacent segments on the probability density function estimation and evaluation of each acoustic segment. This idea not only makes the model robust against segmentation errors, but also it models gradual change from one segment to the next one with a minimum set of parameters. The proposed idea is analytically formulated and tested on a TIMIT based context independent phenomena classification system. During the test procedure, the phoneme classification of different phoneme classes was performed by applying various proposed recognition algorithms. The system was optimized and the results have been compared with a continuous density hidden Markov model (CDHMM) with similar computational complexity. The results show 8-10% improvement in phoneme recognition rate in comparison with standard continuous density hidden Markov model. This indicates improved compatibility of the proposed model with the speech nature. (author)

  2. Tilted dipole model for bias-dependent photoluminescence pattern

    Science.gov (United States)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-12-01

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission.

  3. Tilted dipole model for bias-dependent photoluminescence pattern

    International Nuclear Information System (INIS)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-01-01

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission

  4. Are Invasive Species Stressful? The Glucocorticoid Profile of Native Lizards Exposed to Invasive Fire Ants Depends on the Context.

    Science.gov (United States)

    Graham, Sean P; Freidenfelds, Nicole A; Thawley, Christopher J; Robbins, Travis R; Langkilde, Tracy

    Invasive species represent a substantial threat to native species worldwide. Research on the impacts of invasive species on wild living vertebrates has focused primarily on population-level effects. The sublethal, individual-level effects of invaders may be equally important but are poorly understood. We investigated the effects of invasive fire ants (Solenopsis invicta) on the physiological stress response of a native lizard (Sceloporus undulatus) within two experimental contexts: directly exposing lizards to a fire ant attack and housing lizards with fire ants in seminatural field enclosures. Lizards directly exposed to brief attack by fire ants had elevated concentrations of the stress hormone corticosterone (CORT), suggesting that these encounters can be physiologically stressful. However, lizards exposed for longer periods to fire ants in field enclosures had lower concentrations of CORT. This may indicate that the combined effects of confinement and fire ant exposure have pushed lizards into allostatic overload. However, lizards from fire ant enclosures appeared to have intact negative feedback controls of the stress response, evidenced by functioning adrenocorticotropic hormone responsiveness and lack of suppression of innate immunity (plasma bactericidal capacity). We review previous studies examining the stress response of wild vertebrates to various anthropogenic stressors and discuss how these-in combination with our results-underscore the importance of considering context (the length, frequency, magnitude, and types of threat) when assessing these impacts.

  5. OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells

    Directory of Open Access Journals (Sweden)

    Ravinder Kaur

    2015-10-01

    Full Text Available Medulloblastoma (MB is the most common malignant primary pediatric brain tumor and is currently divided into four subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH, Group 3 and Group 4. This extensive heterogeneity has made it difficult to assess the functional relevance of genes to malignant progression. For example, expression of the transcription factor Orthodenticle homeobox2 (OTX2 is frequently dysregulated in multiple MB variants; however, its role may be subtype specific. We recently demonstrated that neural precursors derived from transformed human embryonic stem cells (trans-hENs, but not their normal counterparts (hENs, resemble Groups 3 and 4 MB in vitro and in vivo. Here, we tested the utility of this model system as a means of dissecting the role of OTX2 in MB using gain- and loss-of-function studies in hENs and trans-hENs, respectively. Parallel experiments with MB cells revealed that OTX2 exerts inhibitory effects on hEN and SHH MB cells by regulating growth, self-renewal and migration in vitro and tumor growth in vivo. This was accompanied by decreased expression of pluripotent genes, such as SOX2, and was supported by overexpression of SOX2 in OTX2+ SHH MB and hENs that resulted in significant rescue of self-renewal and cell migration. By contrast, OTX2 is oncogenic and promotes self-renewal of trans-hENs and Groups 3 and 4 MB independent of pluripotent gene expression. Our results demonstrate a novel role for OTX2 in self-renewal and migration of hENs and MB cells and reveal a cell-context-dependent link between OTX2 and pluripotent genes. Our study underscores the value of human embryonic stem cell derivatives as alternatives to cell lines and heterogeneous patient samples for investigating the contribution of key developmental regulators to MB progression.

  6. Modelling the economics of farm-based anaerobic digestion in a UK whole-farm context

    International Nuclear Information System (INIS)

    Jones, Philip; Salter, Andrew

    2013-01-01

    Anaerobic digestion (AD) technologies convert organic wastes and crops into methane-rich biogas for heating, electricity generation and vehicle fuel. Farm-based AD has proliferated in some EU countries, driven by favourable policies promoting sustainable energy generation and GHG mitigation. Despite increased state support there are still few AD plants on UK farms leading to a lack of normative data on viability of AD in the whole-farm context. Farmers and lenders are therefore reluctant to fund AD projects and policy makers are hampered in their attempts to design policies that adequately support the industry. Existing AD studies and modelling tools do not adequately capture the farm context within which AD interacts. This paper demonstrates a whole-farm, optimisation modelling approach to assess the viability of AD in a more holistic way, accounting for such issues as: AD scale, synergies and conflicts with other farm enterprises, choice of feedstocks, digestate use and impact on farm Net Margin. This modelling approach demonstrates, for example, that: AD is complementary to dairy enterprises, but competes with arable enterprises for farm resources. Reduced nutrient purchases significantly improve Net Margin on arable farms, but AD scale is constrained by the capacity of farmland to absorb nutrients in AD digestate. -- Highlights: •Lack of empirical data on UK farm AD is barrier to investment and policy formulation. •A modelling approach used to assess economic viability of AD in whole-farm context. •AD increases dairy and arable farm net margin including by savings in nutrient costs. •AD margins better for a few crops than other uses, especially wheat and beet crops. •AD co-exists with dairy, but to obtain best margin displaces conventional cropping

  7. A Probabilistic Model for Sequence Alignment with Context-Sensitive Indels

    Science.gov (United States)

    Hickey, Glenn; Blanchette, Mathieu

    Probabilistic approaches for sequence alignment are usually based on pair Hidden Markov Models (HMMs) or Stochastic Context Free Grammars (SCFGs). Recent studies have shown a significant correlation between the content of short indels and their flanking regions, which by definition cannot be modelled by the above two approaches. In this work, we present a context-sensitive indel model based on a pair Tree-Adjoining Grammar (TAG), along with accompanying algorithms for efficient alignment and parameter estimation. The increased precision and statistical power of this model is shown on simulated and real genomic data. As the cost of sequencing plummets, the usefulness of comparative analysis is becoming limited by alignment accuracy rather than data availability. Our results will therefore have an impact on any type of downstream comparative genomics analyses that rely on alignments. Fine-grained studies of small functional regions or disease markers, for example, could be significantly improved by our method. The implementation is available at http://www.mcb.mcgill.ca/~blanchem/software.html

  8. An Ontology-Based Context Model for Wireless Sensor Network (WSN Management in the Internet of Things

    Directory of Open Access Journals (Sweden)

    Adnan Al-Anbuky

    2013-09-01

    Full Text Available Wireless sensor networks (WSNs are an enabling technology of context-aware systems. The Internet of Things (IoT, which has attracted much attention in recent years, is an emerging paradigm where everyday objects and spaces are made context-aware and interconnected through heterogeneous networks on a global scale. However, the IoT system can suffer from poor performances when its underlying networks are not optimized. In this paper, an ontology model for representing and facilitating context sharing between network entities in WSNs is proposed for the first time. The context model aims to enable optimal context-aware management of WSNs in IoT, which will also harness the rich context knowledge of IoT systems.

  9. Natural Model based Design in Context: an Effective Method for Environmental Problems

    Directory of Open Access Journals (Sweden)

    Eric D. Kameni

    2017-10-01

    Full Text Available Analyzing complex problem domains is not easy. Simulation tools support decision makers to find the best policies. Model-based system development is an approach where a model of the application domain is the central driving force when designing simulation tools. State-of-the-art techniques however still require both expert knowledge of the application domain and the implementation techniques as provided by ICT (such as multilevel agent technology. Domain experts, however, usually do not master ICT sufficiently. Modeling is more insightful for the domain expert when its goal is to formalize the language being used in that domain as a semi-natural language. At the meta level, this language describes the main concepts of the type of application domain. The model then is a concretization of this meta model. The main focus of this article is (1 to propose a natural-language-based approach to modeling application domains, (2 to show how these models can be transformed systematically into computational models, and (3 to propose the tool TiC (Tool in Context that supports the domain expert when developing a model and generating a simulation tool. Our research methodology is based on Design Science. We verify our approach by describing the various transformation steps in detail, and by demonstrating the way of working via a sample session applying a real problem of Laf Forest Reserve deforestation in North Cameroon.

  10. Model for temperature-dependent magnetization of nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Q.; Niewczas, M. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S4M1 (Canada)

    2015-01-07

    A magnetization model of nanocrystalline materials incorporating intragrain anisotropies, intergrain interactions, and texture effects has been extended to include the thermal fluctuations. The method relies on the stochastic Landau–Lifshitz–Gilbert theory of magnetization dynamics and permits to study the magnetic properties of nanocrystalline materials at arbitrary temperature below the Currie temperature. The model has been used to determine the intergrain exchange constant and grain boundary anisotropy constant of nanocrystalline Ni at 100 K and 298 K. It is found that the thermal fluctuations suppress the strength of the intergrain exchange coupling and also reduce the grain boundary anisotropy. In comparison with its value at 2 K, the interparticle exchange constant decreases by 16% and 42% and the grain boundary anisotropy constant decreases by 28% and 40% at 100 K and 298 K, respectively. An application of the model to study the grain size-dependent magnetization indicates that when the thermal activation energy is comparable to the free energy of grains, the decrease in the grain size leads to the decrease in the magnetic permeability and saturation magnetization. The mechanism by which the grain size influences the magnetic properties of nc–Ni is discussed.

  11. Thanks, but No Thanks: Women's Avoidance of Help-Seeking in the Context of a Dependency-Related Stereotype

    Science.gov (United States)

    Wakefield, Juliet R. H.; Hopkins, Nick; Greenwood, Ronni M.

    2012-01-01

    The stereotype that women are dependent on men is a commonly verbalized, potentially damaging aspect of benevolent sexism. We investigated how women may use behavioral disconfirmation of the personal applicability of the stereotype to negotiate such sexism. In an experiment (N = 86), we manipulated female college students' awareness that women may…

  12. Experience-Dependent Enhancement of Linguistic Pitch Representation in the Brainstem Is Not Specific to a Speech Context

    Science.gov (United States)

    Krishnan, Ananthanarayan; Swaminathan, Jayaganesh; Gandour, Jackson T.

    2009-01-01

    Neural representation of pitch is influenced by lifelong experiences with music and language at both cortical and subcortical levels of processing. The aim of this article is to determine whether neural plasticity for pitch representation at the level of the brainstem is dependent upon specific "dimensions" of pitch contours that commonly occur as…

  13. Increased opioid dependence in a mouse model of panic disorder

    Directory of Open Access Journals (Sweden)

    Xavier Gallego

    2010-02-01

    Full Text Available Panic disorder is a highly prevalent neuropsychiatric disorder that shows co-occurrence with substance abuse. Here, we demonstrate that TrkC, the high affinity receptor for neurotrophin-3, is a key molecule involved in panic disorder and opiate dependence, using a transgenic mouse model (TgNTRK3. Constitutive TrkC overexpression in TgNTRK3 mice dramatically alters spontaneous firing rates of locus coeruleus neurons and the response of the noradrenergic system to chronic opiate exposure, possibly related to the altered regulation of neurotrophic peptides observed. Notably, TgNTRK3 locus coeruleus neurons showed an increased firing rate in saline-treated conditions and profound abnormalities in their response to met5-enkephalin. Behaviorally, chronic morphine administration induced a significantly increased withdrawal syndrome in TgNTRK3 mice. In conclusion, we show here that the NT-3/TrkC system is an important regulator of neuronal firing in locus coeruleus and could contribute to the adaptations of the noradrenergic system in response to chronic opiate exposure. Moreover, our results indicate that TrkC is involved in the molecular and cellular changes in noradrenergic neurons underlying both panic attacks and opiate dependence and support a functional endogenous opioid deficit in panic disorder patients.

  14. Mathematical model of SPOC with a time dependent reactive field

    Energy Technology Data Exchange (ETDEWEB)

    Ohtaki, Masako [Department of Physics, School of Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2006-03-21

    In general the muscle is in one of the two state possible states, relaxation or contraction. These contractions result from relative sliding of myosin and actin in the sarcomere, which is the contraction structure unit of skeletal muscle. The switching between two states is depending on the Ca2{sup +} concentrations. However another state has been detected between these two states. In the third state, that is SPontaneous Oscillatory Contraction (SPOC), sarcomere repeats contraction and extension spontaneously. Muscle fibers are composed of hundreds of sarcomeres in series and one sarcomea also is composed of hundreds of myosin. In microscopic, the force generated by actin and myosin interaction occurs stochastically. SPOC, however, is macroscopically observable and there are regular oscillations. To understand SPOC mechanism, we propose a model for SPOC based on chemical reaction including mechanical process.

  15. Instrumental learning: an animal model for sleep dependent memory enhancement.

    Science.gov (United States)

    Leenaars, Cathalijn H C; Girardi, Carlos E N; Joosten, Ruud N J M A; Lako, Irene M; Ruimschotel, Emma; Hanegraaf, Maaike A J; Dematteis, Maurice; Feenstra, Matthijs G P; Van Someren, Eus J W

    2013-07-15

    The relationship between learning and sleep is multifaceted; learning influences subsequent sleep characteristics, which may in turn influence subsequent memory. Studies in humans indicate that sleep may not only prevent degradation of acquired memories, but even enhance performance without further practice. In a rodent instrumental learning task, individual differences occur in how fast rats learn to associate lever pressing with food reward. Rats habitually sleep between learning sessions, and may differ in this respect. The current study assessed if the instrumental leaning paradigm could serve as a model to study sleep-dependent memory enhancement. Male Wistar rats performed 2 sessions of instrumental learning per day for 1-3 days. Electroencephalography was recorded both before and after the sessions. Sleep deprivation (3 h) was applied between the first and second session in a subgroup of rats. Measurements comprised the number of lever presses in each session, slow wave sleep (SWS) duration, Rapid Eye Movement Sleep (REMS) duration and sleep spindles. Baseline sleep parameters were similar for fast and slow learning rats. Task-exposure increased REMS-duration. The increase in REMS-duration was observed specifically after sessions in which learning occurred, but not after a later session. Sleep deprivation during the 3h period between the initial two sessions interfered with performance enhancement, but did not prevent this in all rats. Our considered movement control protocol induced partial sleep deprivation and also interfered with performance enhancement. The classic instrumental learning task provides a practical model for animal studies on sleep-dependent memory enhancement. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Positive Psychology in Context: Effects of Expressing Gratitude in Ongoing Relationships Depend on Perceptions of Enactor Responsiveness.

    Science.gov (United States)

    Algoe, Sara B; Zhaoyang, Ruixue

    2016-01-01

    Recent correlational evidence implicates gratitude in personal and relational growth, for both members of ongoing relationships. From these observations, it would be tempting to prescribe interpersonal gratitude exercises to improve relationships. In this experiment, couples were randomly assigned to express gratitude over a month, or to a relationally-active control condition. Results showed modest effects of condition on personal and relational well-being. However, those whose partners were perceived as being particularly responsive when expressing gratitude at the initial lab session showed greater well-being across a range of outcomes, whereas this was not so for people in the control condition. Notably, evidence raises concerns about the effectiveness of artificial injections of gratitude when the partner is perceived to be low in responsiveness. Given the importance of close relationships, this work highlights the need for more theory-driven basic research tested in context before assuming what appears to work naturally will also work artificially.

  17. Validated context-dependent associations of coronary heart disease risk with genotype variation in the chromosome 9p21 region

    DEFF Research Database (Denmark)

    Lusk, Christine M; Dyson, Greg; Clark, Andrew G

    2014-01-01

    variations marking the 9p21 region for explaining variation in CHD risk? We analyzed a sample of 7,589 (3,869 females and 3,720 males) European American participants of the Atherosclerosis Risk in Communities study. We confirmed CHD-SNP genotype associations for two 9p21 region marker SNPs previously......Markers of the chromosome 9p21 region are regarded as the strongest and most reliably significant genome-wide association study (GWAS) signals for Coronary heart disease (CHD) risk; this was recently confirmed by the CARDIoGRAMplusC4D Consortium meta-analysis. However, while these associations...... are significant at the population level, they may not be clinically relevant predictors of risk for all individuals. We describe here the results of a study designed to address the question: What is the contribution of context defined by traditional risk factors in determining the utility of DNA sequence...

  18. Context-dependent neural activation: internally and externally guided rhythmic lower limb movement in individuals with and without neurodegenerative disease

    Directory of Open Access Journals (Sweden)

    Madeleine Eve Hackney

    2015-12-01

    Full Text Available Parkinson’s Disease (PD is a neurodegenerative disorder that has received considerable attention in allopathic medicine over the past decades. However, it is clear that, to date, pharmacological and surgical interventions do not fully address symptoms of PD and patients’ quality of life. As both an alternative therapy and as an adjuvant to conventional approaches, several types of rhythmic movement (e.g., movement strategies, dance, tandem biking, tai chi have shown improvements to motor symptoms, lower limb control and postural stability in people with PD (Amano, Nocera, Vallabhajosula, Juncos, Gregor, Waddell et al., 2013; Earhart, 2009; M. E. Hackney & Earhart, 2008; Kadivar, Corcos, Foto, & Hondzinski, 2011; Morris, Iansek, & Kirkwood, 2009; Ridgel, Vitek, & Alberts, 2009. However, while these programs are increasing in number, still little is known about the neural mechanisms underlying motor improvements attained with such interventions. Studying limb motor control under task specific contexts can help determine the mechanisms of rehabilitation effectiveness. Both internally guided (IG and externally guided (EG movement strategies have evidence to support their use in rehabilitative programs. However, there appears to be a degree of differentiation in the neural substrates involved in IG versus EG designs. Because of the potential task specific benefits of rhythmic training within a rehabilitative context, this report will consider the use of IG and EG movement strategies, and observations produced by functional magnetic resonance imaging (fMRI and other imaging techniques. This review will present findings from lower limb imaging studies, under IG and EG conditions for populations with and without movement disorders. We will discuss how these studies might inform movement disorders rehabilitation (in the form of rhythmic, music-based movement training and highlight research gaps. We believe better understanding of lower limb neural

  19. Geometric Context and Orientation Map Combination for Indoor Corridor Modeling Using a Single Image

    Science.gov (United States)

    Baligh Jahromi, Ali; Sohn, Gunho

    2016-06-01

    Since people spend most of their time indoors, their indoor activities and related issues in health, security and energy consumption have to be understood. Hence, gathering and representing spatial information of indoor spaces in form of 3D models become very important. Considering the available data gathering techniques with respect to the sensors cost and data processing time, single images proved to be one of the reliable sources. Many of the current single image based indoor space modeling methods are defining the scene as a single box primitive. This domain-specific knowledge is usually not applicable in various cases where multiple corridors are joined at one scene. Here, we addressed this issue by hypothesizing-verifying multiple box primitives which represents the indoor corridor layout. Middle-level perceptual organization is the foundation of the proposed method, which relies on finding corridor layout boundaries using both detected line segments and virtual rays created by orthogonal vanishing points. Due to the presence of objects, shadows and occlusions, a comprehensive interpretation of the edge relations is often concealed. This necessitates the utilization of virtual rays to create a physically valid layout hypothesis. Many of the former methods used Orientation Map or Geometric Context to evaluate their proposed layout hypotheses. Orientation map is a map that reveals the local belief of region orientations computed from line segments, and in a segmented image geometric context uses color, texture, edge, and vanishing point cues to estimate the likelihood of each possible label for all super-pixels. Here, the created layout hypotheses are evaluated by an objective function which considers the fusion of orientation map and geometric context with respect to the horizontal viewing angle at each image pixel. Finally, the best indoor corridor layout hypothesis which gets the highest score from the scoring function will be selected and converted to a 3D

  20. Modelling polarization dependent absorption: The vectorial Lambert-Beer law

    Science.gov (United States)

    Franssens, G.

    2014-07-01

    The scalar Lambert-Beer law, describing the absorption of unpolarized light travelling through a linear non-scattering medium, is simple, well-known, and mathematically trivial. However, when we take the polarization of light into account and consider a medium with polarization dependent absorption, we now need a Vectorial Lambert-Beer Law (VLBL) to quantify this interaction. Such a generalization of the scalar Lambert-Beer law appears not to be readily available. A careful study of this topic reveals that it is not a trivial problem. We will see that the VLBL is not and cannot be a straightforward vectorized version of its scalar counterpart. The aim of the work is to present the general form of the VLBL and to explain how it arises. A reasonable starting point to derive the VLBL is the Vectorial Radiative Transfer Equation (VRTE), which models the absorption and scattering of (partially) polarized light travelling through a linear medium. When we turn off scattering, the VRTE becomes an infinitesimal model for the VLBL holding in the medium. By integrating this equation, we expect to find the VLBL. Surprisingly, this is not the end of the story. It turns out that light propagation through a medium with polarization-dependent absorption is mathematically not that trivial. The trickiness behind the VLBL can be understood in the following terms. The matrix in the VLBL, relating any input Stokes vector to the corresponding output Stokes vector, must necessarily be a Mueller matrix. The subset of invertible Mueller matrices forms a Lie group. It is known that this Lie group contains the ortho-chronous Lorentz group as a subgroup. The group manifold of this subgroup has a (well-known) non-trivial topology. Consequently, the manifold of the Lie group of Mueller matrices also has (at least the same, but likely a more general) non-trivial topology (the full extent of which is not yet known). The type of non-trivial topology, possessed by the manifold of (invertible

  1. Economic Models for Inland Navigation in the Context of Climate Change

    International Nuclear Information System (INIS)

    Demirel, E.

    2011-01-01

    The inland navigation market of North-Western Europe faces potential problems due to climate change. Different measures may be taken by governments, carriers, and customers to cope with the negative effects of climate change. The effects of climate change on the inland navigation market may also be different for regions with different demand for transport by inland navigation. The research carried out in this dissertation can be seen as an investigation into adaptation strategies and the interaction-effects of imbalance and climate change on the inland navigation market. This gives rise to the following two main research questions for this dissertation: (1) What is the optimal barge-size adjustment for barge operators to cope with climate change, and what are the implications of climate change for investments in inland waterway infrastructure by the public sector?; (2) What is the impact of climate change on freight prices in the inland navigation market in the presence of direction dependent freight imbalances? There is still a gap in the scientific literature on the transport economic aspects of inland navigation in general. This dissertation contributes to this literature by approaching the field in a climate change context. In addition, the incorporation of imperfect information to the backhaul literature can be seen as a contribution to the economic theory. We show that imbalance leads to different impacts of climate change in different regions (even though the climate change may be the same for these regions). As a contribution to decision making, the adaptation strategies that are evaluated from a welfare economic perspective can be mentioned. Both private decision making (choice of barge size) and public decision making (choice of amount to invest in infrastructure) are supported, by providing the optimal values to be chosen for the instruments available. By taking the imbalance issue into account, this study gives insights into how to achieve a fair

  2. Default risk modeling with position-dependent killing

    Science.gov (United States)

    Katz, Yuri A.

    2013-04-01

    Diffusion in a linear potential in the presence of position-dependent killing is used to mimic a default process. Different assumptions regarding transport coefficients, initial conditions, and elasticity of the killing measure lead to diverse models of bankruptcy. One “stylized fact” is fundamental for our consideration: empirically default is a rather rare event, especially in the investment grade categories of credit ratings. Hence, the action of killing may be considered as a small parameter. In a number of special cases we derive closed-form expressions for the entire term structure of the cumulative probability of default, its hazard rate, and intensity. Comparison with historical data on aggregate global corporate defaults confirms the validity of the perturbation method for estimations of long-term probability of default for companies with high credit quality. On a single company level, we implement the derived formulas to estimate the one-year likelihood of default of Enron on a daily basis from August 2000 to August 2001, three months before its default, and compare the obtained results with forecasts of traditional structural models.

  3. A Programming Model for Massive Data Parallelism with Data Dependencies

    International Nuclear Information System (INIS)

    Cui, Xiaohui; Mueller, Frank; Potok, Thomas E.; Zhang, Yongpeng

    2009-01-01

    Accelerating processors can often be more cost and energy effective for a wide range of data-parallel computing problems than general-purpose processors. For graphics processor units (GPUs), this is particularly the case when program development is aided by environments such as NVIDIA s Compute Unified Device Architecture (CUDA), which dramatically reduces the gap between domain-specific architectures and general purpose programming. Nonetheless, general-purpose GPU (GPGPU) programming remains subject to several restrictions. Most significantly, the separation of host (CPU) and accelerator (GPU) address spaces requires explicit management of GPU memory resources, especially for massive data parallelism that well exceeds the memory capacity of GPUs. One solution to this problem is to transfer data between the GPU and host memories frequently. In this work, we investigate another approach. We run massively data-parallel applications on GPU clusters. We further propose a programming model for massive data parallelism with data dependencies for this scenario. Experience from micro benchmarks and real-world applications shows that our model provides not only ease of programming but also significant performance gains

  4. A copula method for modeling directional dependence of genes

    Directory of Open Access Journals (Sweden)

    Park Changyi

    2008-05-01

    Full Text Available Abstract Background Genes interact with each other as basic building blocks of life, forming a complicated network. The relationship between groups of genes with different functions can be represented as gene networks. With the deposition of huge microarray data sets in public domains, study on gene networking is now possible. In recent years, there has been an increasing interest in the reconstruction of gene networks from gene expression data. Recent work includes linear models, Boolean network models, and Bayesian networks. Among them, Bayesian networks seem to be the most effective in constructing gene networks. A major problem with the Bayesian network approach is the excessive computational time. This problem is due to the interactive feature of the method that requires large search space. Since fitting a model by using the copulas does not require iterations, elicitation of the priors, and complicated calculations of posterior distributions, the need for reference to extensive search spaces can be eliminated leading to manageable computational affords. Bayesian network approach produces a discretely expression of conditional probabilities. Discreteness of the characteristics is not required in the copula approach which involves use of uniform representation of the continuous random variables. Our method is able to overcome the limitation of Bayesian network method for gene-gene interaction, i.e. information loss due to binary transformation. Results We analyzed the gene interactions for two gene data sets (one group is eight histone genes and the other group is 19 genes which include DNA polymerases, DNA helicase, type B cyclin genes, DNA primases, radiation sensitive genes, repaire related genes, replication protein A encoding gene, DNA replication initiation factor, securin gene, nucleosome assembly factor, and a subunit of the cohesin complex by adopting a measure of directional dependence based on a copula function. We have compared

  5. Disentangling density-dependent dynamics using full annual cycle models and Bayesian model weight updating

    Science.gov (United States)

    Robinson, Orin J.; McGowan, Conor P.; Devers, Patrick K.

    2017-01-01

    Density dependence regulates populations of many species across all taxonomic groups. Understanding density dependence is vital for predicting the effects of climate, habitat loss and/or management actions on wild populations. Migratory species likely experience seasonal changes in the relative influence of density dependence on population processes such as survival and recruitment throughout the annual cycle. These effects must be accounted for when characterizing migratory populations via population models.To evaluate effects of density on seasonal survival and recruitment of a migratory species, we used an existing full annual cycle model framework for American black ducks Anas rubripes, and tested different density effects (including no effects) on survival and recruitment. We then used a Bayesian model weight updating routine to determine which population model best fit observed breeding population survey data between 1990 and 2014.The models that best fit the survey data suggested that survival and recruitment were affected by density dependence and that density effects were stronger on adult survival during the breeding season than during the non-breeding season.Analysis also suggests that regulation of survival and recruitment by density varied over time. Our results showed that different characterizations of density regulations changed every 8–12 years (three times in the 25-year period) for our population.Synthesis and applications. Using a full annual cycle, modelling framework and model weighting routine will be helpful in evaluating density dependence for migratory species in both the short and long term. We used this method to disentangle the seasonal effects of density on the continental American black duck population which will allow managers to better evaluate the effects of habitat loss and potential habitat management actions throughout the annual cycle. The method here may allow researchers to hone in on the proper form and/or strength of

  6. Elaboration Likelihood Model and an Analysis of the Contexts of Its Application

    Directory of Open Access Journals (Sweden)

    Aslıhan Kıymalıoğlu

    2014-12-01

    Full Text Available Elaboration Likelihood Model (ELM, which supports the existence of two routes to persuasion: central and peripheral routes, has been one of the major models on persuasion. As the number of studies in the Turkish literature on ELM is limited, a detailed explanation of the model together with a comprehensive literature review was considered to be contributory for this gap. The findings of the review reveal that the model was mostly used in marketing and advertising researches, that the concept most frequently used in elaboration process was involvement, and that argument quality and endorser credibility were the factors most often employed in measuring their effect on the dependant variables. The review provides valuable insights as it presents a holistic view of the model and the variables used in the model.

  7. Bayes factor between Student t and Gaussian mixed models within an animal breeding context

    Directory of Open Access Journals (Sweden)

    García-Cortés Luis

    2008-07-01

    Full Text Available Abstract The implementation of Student t mixed models in animal breeding has been suggested as a useful statistical tool to effectively mute the impact of preferential treatment or other sources of outliers in field data. Nevertheless, these additional sources of variation are undeclared and we do not know whether a Student t mixed model is required or if a standard, and less parameterized, Gaussian mixed model would be sufficient to serve the intended purpose. Within this context, our aim was to develop the Bayes factor between two nested models that only differed in a bounded variable in order to easily compare a Student t and a Gaussian mixed model. It is important to highlight that the Student t density converges to a Gaussian process when degrees of freedom tend to infinity. The twomodels can then be viewed as nested models that differ in terms of degrees of freedom. The Bayes factor can be easily calculated from the output of a Markov chain Monte Carlo sampling of the complex model (Student t mixed model. The performance of this Bayes factor was tested under simulation and on a real dataset, using the deviation information criterion (DIC as the standard reference criterion. The two statistical tools showed similar trends along the parameter space, although the Bayes factor appeared to be the more conservative. There was considerable evidence favoring the Student t mixed model for data sets simulated under Student t processes with limited degrees of freedom, and moderate advantages associated with using the Gaussian mixed model when working with datasets simulated with 50 or more degrees of freedom. For the analysis of real data (weight of Pietrain pigs at six months, both the Bayes factor and DIC slightly favored the Student t mixed model, with there being a reduced incidence of outlier individuals in this population.

  8. Agonistic interactions between the honeybee (Apis mellifera ligustica and the European wasp (Vespula germanica reveal context-dependent defense strategies.

    Directory of Open Access Journals (Sweden)

    Michelina Pusceddu

    Full Text Available Predator-prey relationships between sympatric species allow the evolution of defense behaviors, such as honeybee colonies defending their nests against predatory wasps. We investigated the predator-prey relationship between the honeybee (Apis mellifera ligustica and the European wasp (Vespula germanica by evaluating the effectiveness of attack and defense behaviors, which have coevolved in these sympatric species, as well as the actual damage and disturbance caused to the colonies under attack. Attack and defense behaviors were recorded in front of the hive to observe attacks at the hive entrance (68 attacks in 279 h and at ground level on isolated and weakened honeybees close to the hive (465 attacks in 32 h. We found that V. germanica attacked the hive entrance infrequently due to the low success rate of this strategy and instead preferred a specialized attack method targeting adult honeybees at ground level, demonstrating opportunistic scavenger behavior. Individual honeybees usually responded effectively to an attack by recruiting an average of two nestmates, causing the wasp to flee, whereas collective balling behavior was only observed on four occasions. V. germanica does not appear to disrupt the foraging activity of the colonies under attack. We found that agonistic events supported by other nestmates were typically the most intense ones, involving physical combat and prolonged attacks at the entrance to the hive. These observations support the hypothesis that A. mellifera ligustica can adapt its behavior to match the severity of the threat and the context of the attack.

  9. Agonistic interactions between the honeybee (Apis mellifera ligustica) and the European wasp (Vespula germanica) reveal context-dependent defense strategies.

    Science.gov (United States)

    Pusceddu, Michelina; Floris, Ignazio; Buffa, Franco; Salaris, Emanuele; Satta, Alberto

    2017-01-01

    Predator-prey relationships between sympatric species allow the evolution of defense behaviors, such as honeybee colonies defending their nests against predatory wasps. We investigated the predator-prey relationship between the honeybee (Apis mellifera ligustica) and the European wasp (Vespula germanica) by evaluating the effectiveness of attack and defense behaviors, which have coevolved in these sympatric species, as well as the actual damage and disturbance caused to the colonies under attack. Attack and defense behaviors were recorded in front of the hive to observe attacks at the hive entrance (68 attacks in 279 h) and at ground level on isolated and weakened honeybees close to the hive (465 attacks in 32 h). We found that V. germanica attacked the hive entrance infrequently due to the low success rate of this strategy and instead preferred a specialized attack method targeting adult honeybees at ground level, demonstrating opportunistic scavenger behavior. Individual honeybees usually responded effectively to an attack by recruiting an average of two nestmates, causing the wasp to flee, whereas collective balling behavior was only observed on four occasions. V. germanica does not appear to disrupt the foraging activity of the colonies under attack. We found that agonistic events supported by other nestmates were typically the most intense ones, involving physical combat and prolonged attacks at the entrance to the hive. These observations support the hypothesis that A. mellifera ligustica can adapt its behavior to match the severity of the threat and the context of the attack.

  10. Boys vs. girls: Gender differences in the neural development of trust and reciprocity depend on social context.

    Science.gov (United States)

    Lemmers-Jansen, Imke L J; Krabbendam, Lydia; Veltman, Dick J; Fett, Anne-Kathrin J

    2017-06-01

    Trust and cooperation increase from adolescence to adulthood, but studies on gender differences in this development are rare. We investigated gender and age-related differences in trust and reciprocity and associated neural mechanisms in 43 individuals (16-27 years, 22 male). Participants played two multi-round trust games with a cooperative and an unfair partner. Males showed more basic trust towards unknown others than females. Both genders increased trust during cooperative interactions, with no differences in average trust. Age was unrelated to trust during cooperation. During unfair interactions males decreased their trust more with age than females. ROI analysis showed age-related increases in activation in the temporo-parietal junction (TPJ) and dorsolateral prefrontal cortex (dlPFC) during cooperative investments, and increased age-related caudate activation during both cooperative and unfair repayments. Gender differences in brain activation were only observed during cooperative repayments, with males activating the TPJ more than females, and females activating the caudate more. The findings suggest relatively mature processes of trust and reciprocity in the investigated age range. Gender differences only occur in unfair contexts, becoming more pronounced with age. Largely similar neural activation in males and females and few age effects suggest that similar, mature cognitive strategies are employed. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Linking context, competencies and modeling. Is it possible to teach science to all people?

    Directory of Open Access Journals (Sweden)

    Mercè Izquierdo Aymerich

    2017-01-01

    Full Text Available The  recommendation  to  teach  science  in  context,  through  Models,  to  acquire  competences,  applies  to all  teaching  without  differentiating  between  the  basic  and  the  non-compulsory  levels.  But the purpose of learning science in the stage of compulsory education (for what and why teach is very different from that of the non-compulsory stage, when science students have chosen this subject among others. Therefore, to teach  science  to  all,  the  curriculum  of  the  basic  cycle  must  be  designed  with  more  freedom,  so  that  the school sciences provide resources to understand the functioning of the world in which we live, to be able to speak of it with a language (scientific that has in account the experimental intervention in context and the values that regulate it. Learning should be evaluated according to this recommendation. In this lecture we will reflect on the design of a curriculum for the teaching of a `science for all' that develops genuine scientific activity, in which the Theoretical Models of the different scientific disciplines converge.

  12. On the context-dependent nature of the contribution of the ventral premotor cortex to speech perception

    Science.gov (United States)

    Tremblay, Pascale; Small, Steven L.

    2011-01-01

    What is the nature of the interface between speech perception and production, where auditory and motor representations converge? One set of explanations suggests that during perception, the motor circuits involved in producing a perceived action are in some way enacting the action without actually causing movement (covert simulation) or sending along the motor information to be used to predict its sensory consequences (i.e., efference copy). Other accounts either reject entirely the involvement of motor representations in perception, or explain their role as being more supportive than integral, and not employing the identical circuits used in production. Using fMRI, we investigated whether there are brain regions that are conjointly active for both speech perception and production, and whether these regions are sensitive to articulatory (syllabic) complexity during both processes, which is predicted by a covert simulation account. A group of healthy young adults (1) observed a female speaker produce a set of familiar words (perception), and (2) observed and then repeated the words (production). There were two types of words, varying in articulatory complexity, as measured by the presence or absence of consonant clusters. The simple words contained no consonant cluster (e.g. “palace”), while the complex words contained one to three consonant clusters (e.g. “planet”). Results indicate that the left ventral premotor cortex (PMv) was significantly active during speech perception and speech production but that activation in this region was scaled to articulatory complexity only during speech production, revealing an incompletely specified efferent motor signal during speech perception. The right planum temporal (PT) was also active during speech perception and speech production, and activation in this region was scaled to articulatory complexity during both production and perception. These findings are discussed in the context of current theories theory of

  13. The prognostic implications of macrophages expressing proliferating cell nuclear antigen in breast cancer depend on immune context.

    Directory of Open Access Journals (Sweden)

    Michael J Campbell

    Full Text Available Tumor associated macrophages (TAMs are recruited from the circulation to the tumor site, and can undergo a spectrum of phenotypic changes, with two contrasting activation states described in the literature: the M1 and M2 phenotypes. We previously identified a population of TAMs that express proliferating cell nuclear antigen (PCNA and are associated with high grade, hormone receptor negative breast cancers and poor outcomes. In the present exploratory study we again found that high PCNA(+ TAM counts in pre-treatment tumor biopsies (102 invasive breast cancer cases from the I-SPY 1 Trial, a prospective neoadjuvant trial with serial core biopsies and gene array data were associated with high grade, hormone receptor negativity, and decreased recurrence free survival. We explored the association of these PCNA(+ TAMs with the expression of M1 and M2 related genes and, contrary to expectation, observed that high PCNA(+ TAM levels were associated with more M1- than M2-related genes. An immune gene signature, derived from cytotoxic T cell and MHC Class II genes (Tc/ClassII, was developed and we found that high PCNA(+ TAM counts, in the context of a low Tc/ClassII signature score, were associated with significantly worse recurrence free survival in all cases and in hormone receptor negative only cases. We observed similar results using a gene signature-proxy for PCNA(+ TAMs in a larger independent set of 425 neoadjuvant-treated breast cancer cases. The results of this exploratory study indicate that high numbers of PCNA(+ TAMs, in the absence of an anti-tumor immune microenvironment (as indicated by a low Tc/ClassII signature score, are associated with poor outcomes in breast cancer patients treated with neoadjuvant chemotherapy. This, along with the observation that PCNA(+ TAMs were associated predominantly with M1-related genes, may provide new insights into the role of the immune microenvironment in breast cancer.

  14. Matching Aerial Images to 3D Building Models Using Context-Based Geometric Hashing

    Science.gov (United States)

    Jung, Jaewook; Sohn, Gunho; Bang, Kiin; Wichmann, Andreas; Armenakis, Costas; Kada, Martin

    2016-01-01

    A city is a dynamic entity, which environment is continuously changing over time. Accordingly, its virtual city models also need to be regularly updated to support accurate model-based decisions for various applications, including urban planning, emergency response and autonomous navigation. A concept of continuous city modeling is to progressively reconstruct city models by accommodating their changes recognized in spatio-temporal domain, while preserving unchanged structures. A first critical step for continuous city modeling is to coherently register remotely sensed data taken at different epochs with existing building models. This paper presents a new model-to-image registration method using a context-based geometric hashing (CGH) method to align a single image with existing 3D building models. This model-to-image registration process consists of three steps: (1) feature extraction; (2) similarity measure; and matching, and (3) estimating exterior orientation parameters (EOPs) of a single image. For feature extraction, we propose two types of matching cues: edged corner features representing the saliency of building corner points with associated edges, and contextual relations among the edged corner features within an individual roof. A set of matched corners are found with given proximity measure through geometric hashing, and optimal matches are then finally determined by maximizing the matching cost encoding contextual similarity between matching candidates. Final matched corners are used for adjusting EOPs of the single airborne image by the least square method based on collinearity equations. The result shows that acceptable accuracy of EOPs of a single image can be achievable using the proposed registration approach as an alternative to a labor-intensive manual registration process. PMID:27338410

  15. Matching Aerial Images to 3D Building Models Using Context-Based Geometric Hashing

    Directory of Open Access Journals (Sweden)

    Jaewook Jung

    2016-06-01

    Full Text Available A city is a dynamic entity, which environment is continuously changing over time. Accordingly, its virtual city models also need to be regularly updated to support accurate model-based decisions for various applications, including urban planning, emergency response and autonomous navigation. A concept of continuous city modeling is to progressively reconstruct city models by accommodating their changes recognized in spatio-temporal domain, while preserving unchanged structures. A first critical step for continuous city modeling is to coherently register remotely sensed data taken at different epochs with existing building models. This paper presents a new model-to-image registration method using a context-based geometric hashing (CGH method to align a single image with existing 3D building models. This model-to-image registration process consists of three steps: (1 feature extraction; (2 similarity measure; and matching, and (3 estimating exterior orientation parameters (EOPs of a single image. For feature extraction, we propose two types of matching cues: edged corner features representing the saliency of building corner points with associated edges, and contextual relations among the edged corner features within an individual roof. A set of matched corners are found with given proximity measure through geometric hashing, and optimal matches are then finally determined by maximizing the matching cost encoding contextual similarity between matching candidates. Final matched corners are used for adjusting EOPs of the single airborne image by the least square method based on collinearity equations. The result shows that acceptable accuracy of EOPs of a single image can be achievable using the proposed registration approach as an alternative to a labor-intensive manual registration process.

  16. Modeling particle shape-dependent dynamics in nanomedicine.

    Science.gov (United States)

    Shah, Samar; Liu, Yaling; Hu, Walter; Gao, Jinming

    2011-02-01

    One of the major challenges in nanomedicine is to improve nanoparticle cell selectivity and adhesion efficiency through designing functionalized nanoparticles of controlled sizes, shapes, and material compositions. Recent data on cylindrically shaped filomicelles are beginning to show that non-spherical particles remarkably improved the biological properties over spherical counterpart. Despite these exciting advances, non-spherical particles have not been widely used in nanomedicine applications due to the lack of fundamental understanding of shape effect on targeting efficiency. This paper intends to investigate the shape-dependent adhesion kinetics of non-spherical nanoparticles through computational modeling. The ligand-receptor binding kinetics is coupled with Brownian dynamics to study the dynamic delivery process of nanorods under various vascular flow conditions. The influences of nanoparticle shape, ligand density, and shear rate on adhesion probability are studied. Nanorods are observed to contact and adhere to the wall much easier than their spherical counterparts under the same configuration due to their tumbling motion. The binding probability of a nanorod under a shear rate of 8 s(-1) is found to be three times higher than that of a nanosphere with the same volume. The particle binding probability decreases with increased flow shear rate and channel height. The Brownian motion is found to largely enhance nanoparticle binding. Results from this study contribute to the fundamental understanding and knowledge on how particle shape affects the transport and targeting efficiency of nanocarriers, which will provide mechanistic insights on the design of shape-specific nanomedicine for targeted drug delivery applications.

  17. Periodicity in a intensity dependent Haynes-Cummings model

    International Nuclear Information System (INIS)

    Silva Freitas, Dagoberto da; Roversi, J.A.; Vidiella-Barranco, A.

    1997-01-01

    The Jaynes-Cummings (JCM) is the most simple and fundamental model describing the interaction between electromagnetic field and the matter, where a two-level atom is coupled, under the rotating wave approximation, to a quantized field mode. Recently Matsuo, studying the origin of the Q function partitioning in terms of the field density matrix, has separated the effect of the initial atomic state on the Q function clockwise (Cw), counter-clockwise (Ccw) and non rotating (N R) components. Matsuo shows that the inversion of the atomic state population is directly related to the N R component of the density matrix, and is independent of the clockwise and counter-clockwise components. Using the same procedure, we study the case where the atom-field coupling constant depends on the field intensity. We investigate some basic aspects of the field interaction, initially in coherent state, with a two-level atom. The collapse, revival and purity of the atomic state were analysed together with time evolution of the Q function and her partitioning in clockwise, counterclockwise and non-rotating components

  18. A Functional Model of Language, Interrelations of Language, Text and Context, and the Implications for Language Teaching

    OpenAIRE

    Simaibang, Baginda

    2011-01-01

    The purpose of this research is to explore the interrelations of language, context and text and the implications for language teaching. In this investigation, the children were recorded and their conversations were transcribed. The transcription of the conversation and the language of advertisement were analysed using the Halliday and the Jacobson models of language functions. How the functional model was used in the assessment of texts and how were language, context and text were interrelate...

  19. Challenges for Cloud Modeling in the Context of Aerosol–Cloud–Precipitation Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lebo, Zachary J. [Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming; Shipway, Ben J. [Met Office, Exeter, United Kingdom; Fan, Jiwen [Pacific Northwest National Laboratory, Richland, Washington; Geresdi, Istvan [Faculty of Science, University of Pécs, Pécs, Hungary; Hill, Adrian [Met Office, Exeter, United Kingdom; Miltenberger, Annette [School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Morrison, Hugh [Mesoscale and Microscale Meteorology Laboratory, National Center for Atmospheric Research, Boulder, Colorado; Rosenberg, Phil [School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Varble, Adam [Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah; Xue, Lulin [Research Applications Laboratory, National Center for Atmospheric Research, Boulder, Colorado

    2017-08-01

    The International Cloud Modeling Workshop (CMW) has been a longstanding tradition in the cloud microphysics modeling community and is typically held the week prior to the International Conference on Clouds and Precipitation (ICCP). For the Ninth CMW, more than 40 participants from 10 countries convened at the Met Office in Exeter, United Kingdom. The workshop included 4 detailed case studies (described in more detail below) rooted in recent field campaigns. The overarching objective of these cases was to utilize new observations to better understand inter-model differences and model deficiencies, explore new modeling techniques, and gain physical insight into the behavior of clouds. As was the case at the Eighth CMW, there was a general theme of understanding the role of aerosol impacts in the context of cloud-precipitation interactions. However, an additional objective was the focal point of several cases at the most recent workshop: microphysical-dynamical interactions. Many of the cases focused less on idealized small-domain simulations (as was the general focus of previous workshops) and more on large-scale nested configurations examining effects at various scales.

  20. Network Statistical Models for Language Learning Contexts: Exponential Random Graph Models and Willingness to Communicate

    Science.gov (United States)

    Gallagher, H. Colin; Robins, Garry

    2015-01-01

    As part of the shift within second language acquisition (SLA) research toward complex systems thinking, researchers have called for investigations of social network structure. One strand of social network analysis yet to receive attention in SLA is network statistical models, whereby networks are explained in terms of smaller substructures of…

  1. Selector genes display tumor cooperation and inhibition in Drosophila epithelium in a developmental context-dependent manner

    OpenAIRE

    Ram Prakash Gupta; Anjali Bajpai; Pradip Sinha

    2017-01-01

    During animal development, selector genes determine identities of body segments and those of individual organs. Selector genes are also misexpressed in cancers, although their contributions to tumor progression per se remain poorly understood. Using a model of cooperative tumorigenesis, we show that gain of selector genes results in tumor cooperation, but in only select developmental domains of the wing, haltere and eye-antennal imaginal discs of Drosophila larva. Thus, the field selector, Ey...

  2. Selector genes display tumor cooperation and inhibition in Drosophila epithelium in a developmental context-dependent manner

    OpenAIRE

    Gupta, Ram Prakash; Bajpai, Anjali; Sinha, Pradip

    2017-01-01

    ABSTRACT During animal development, selector genes determine identities of body segments and those of individual organs. Selector genes are also misexpressed in cancers, although their contributions to tumor progression per se remain poorly understood. Using a model of cooperative tumorigenesis, we show that gain of selector genes results in tumor cooperation, but in only select developmental domains of the wing, haltere and eye-antennal imaginal discs of Drosophila larva. Thus, the field sel...

  3. Consistently modeling the same movement strategy is more important than model skill level in observational learning contexts.

    Science.gov (United States)

    Buchanan, John J; Dean, Noah

    2014-02-01

    The experiment undertaken was designed to elucidate the impact of model skill level on observational learning processes. The task was bimanual circle tracing with a 90° relative phase lead of one hand over the other hand. Observer groups watched videos of either an instruction model, a discovery model, or a skilled model. The instruction and skilled model always performed the task with the same movement strategy, the right-arm traced clockwise and the left-arm counterclockwise around circle templates with the right-arm leading. The discovery model used several movement strategies (tracing-direction/hand-lead) during practice. Observation of the instruction and skilled model provided a significant benefit compared to the discovery model when performing the 90° relative phase pattern in a post-observation test. The observers of the discovery model had significant room for improvement and benefited from post-observation practice of the 90° pattern. The benefit of a model is found in the consistency with which that model uses the same movement strategy, and not within the skill level of the model. It is the consistency in strategy modeled that allows observers to develop an abstract perceptual representation of the task that can be implemented into a coordinated action. Theoretically, the results show that movement strategy information (relative motion direction, hand lead) and relative phase information can be detected through visual perception processes and be successfully mapped to outgoing motor commands within an observational learning context. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. TGF-β signal transduction spreading to a wider field: a broad variety of mechanisms for context-dependent effects of TGF-β.

    Science.gov (United States)

    Ikushima, Hiroaki; Miyazono, Kohei

    2012-01-01

    Transforming growth factor (TGF)-β signaling is involved in almost all major cell behaviors under physiological and pathological conditions, and its regulatory system has therefore been vigorously investigated. The fundamental elements in TGF-β signaling are TGF-β ligands, their receptors, and intracellular Smad effectors. The TGF-β ligand induces the receptors directly to phosphorylate and activate Smad proteins, which then form transcriptional complexes to control target genes. One of the classical questions in the field of research on TGF-β signaling is how this cytokine induces multiple cell responses depending on cell type and cellular context. Possible answers to this question include cross-interaction with other signaling pathways, different repertoires of Smad-binding transcription factors, and genetic alterations, especially in cancer cells. In addition to these genetic paradigms, recent work has extended TGF-β research into new fields, including epigenetic regulation and non-coding RNAs. In this review, we first describe the basic machinery of TGF-β signaling and discuss several factors that comprise TGF-β signaling networks. We then address mechanisms by which TGF-β induces several responses in a cell-context-dependent fashion. In addition to classical frames, the interaction of TGF-β signaling with epigenetics and microRNA is discussed.

  5. Integrating the context-appropriate balanced attention model and reinforcement sensitivity theory: Towards a domain-general personality process model.

    Science.gov (United States)

    Collins, Michael D; Jackson, Chris J; Walker, Benjamin R; O'Connor, Peter J; Gardiner, Elliroma

    2017-01-01

    Over the last 40 years or more the personality literature has been dominated by trait models based on the Big Five (B5). Trait-based models describe personality at the between-person level but cannot explain the within-person mental mechanisms responsible for personality. Nor can they adequately account for variations in emotion and behavior experienced by individuals across different situations and over time. An alternative, yet understated, approach to personality architecture can be found in neurobiological theories of personality, most notably reinforcement sensitivity theory (RST). In contrast to static trait-based personality models like the B5, RST provides a more plausible basis for a personality process model, namely, one that explains how emotions and behavior arise from the dynamic interaction between contextual factors and within-person mental mechanisms. In this article, the authors review the evolution of a neurobiologically based personality process model based on RST, the response modulation model and the context-appropriate balanced attention model. They argue that by integrating this complex literature, and by incorporating evidence from personality neuroscience, one can meaningfully explain personality at both the within- and between-person levels. This approach achieves a domain-general architecture based on RST and self-regulation that can be used to align within-person mental mechanisms, neurobiological systems and between-person measurement models. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  6. A Bio-Inspired Model-Based Approach for Context-Aware Post-WIMP Tele-Rehabilitation

    Directory of Open Access Journals (Sweden)

    Víctor López-Jaquero

    2016-10-01

    Full Text Available Tele-rehabilitation is one of the main domains where Information and Communication Technologies (ICT have been proven useful to move healthcare from care centers to patients’ home. Moreover, patients, especially those carrying out a physical therapy, cannot use a traditional Window, Icon, Menu, Pointer (WIMP system, but they need to interact in a natural way, that is, there is a need to move from WIMP systems to Post-WIMP ones. Moreover, tele-rehabilitation systems should be developed following the context-aware approach, so that they are able to adapt to the patients’ context to provide them with usable and effective therapies. In this work a model-based approach is presented to assist stakeholders in the development of context-aware Post-WIMP tele-rehabilitation systems. It entails three different models: (i a task model for designing the rehabilitation tasks; (ii a context model to facilitate the adaptation of these tasks to the context; and (iii a bio-inspired presentation model to specify thoroughly how such tasks should be performed by the patients. Our proposal overcomes one of the limitations of the model-based approach for the development of context-aware systems supporting the specification of non-functional requirements. Finally, a case study is used to illustrate how this proposal can be put into practice to design a real world rehabilitation task.

  7. Context-dependent wiring of Sox2 regulatory networks for self-renewal of embryonic and trophoblast stem cells.

    Science.gov (United States)

    Adachi, Kenjiro; Nikaido, Itoshi; Ohta, Hiroshi; Ohtsuka, Satoshi; Ura, Hiroki; Kadota, Mitsutaka; Wakayama, Teruhiko; Ueda, Hiroki R; Niwa, Hitoshi

    2013-11-07

    Sox2 is a transcription factor required for the maintenance of pluripotency. It also plays an essential role in different types of multipotent stem cells, raising the possibility that Sox2 governs the common stemness phenotype. Here we show that Sox2 is a critical downstream target of fibroblast growth factor (FGF) signaling, which mediates self-renewal of trophoblast stem cells (TSCs). Sustained expression of Sox2 together with Esrrb or Tfap2c can replace FGF dependency. By comparing genome-wide binding sites of Sox2 in embryonic stem cells (ESCs) and TSCs combined with inducible knockout systems, we found that, despite the common role in safeguarding the stem cell state, Sox2 regulates distinct sets of genes with unique functions in these two different yet developmentally related types of stem cells. Our findings provide insights into the functional versatility of transcription factors during embryogenesis, during which they can be recursively utilized in a variable manner within discrete network structures. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Considering Time-Dependency of Social Vulnerability in Crisis Modeling and Management

    Science.gov (United States)

    Aubrecht, C.; Steinnocher, K.; Freire, S.; Loibl, W.; Peters-Anders, J.; Ungar, J.

    2012-04-01

    Crisis and disaster management is much more than the immediate first-response actions following an incident. In many projects the main focus has been on the phase starting at the point when an unwanted event happens and lasting until the activities return to normal routines (i.e., ad hoc reaction rather than proactive mitigation). There has been less emphasis on the other phases of the disaster management cycle such as prevention, preparedness, recovery and reconstruction, even though those phases have a strong influence on the general status of a society and its citizens. Especially the potential of a crisis to escalate into a large-scale disaster is heavily dependent on the overall level of preparedness as well as on the planning of mitigation and response actions and their timely execution. There is a need for improved decision-making support that enables modeling of different crisis scenarios and their impacts according to chosen prevention and response actions. Vulnerability describing the status of a society with respect to an imposed hazard or potential impact is considered a strongly multidisciplinary concept. A central objective of vulnerability assessment is to provide indications where and how people - and more specifically, what kind of people - might be affected by a certain impact. Results should provide decision- and policy-makers with supporting information to target response and mitigation actions adequately. For assessment of the social dimension of vulnerability, population exposure mapping is usually considered the starting point. Integration of social structure and varying aspects of resilience further differentiate situation-specific vulnerability patterns on a local scale. In a disaster risk management context, assessment of human vulnerability has generally been lagging behind hazard analysis efforts. Accurately estimating population exposure is a key component of catastrophe loss modeling, one element of effective integrated risk analysis

  9. Health psychology as a context for massage therapy: a conceptual model with CAM as mediator.

    Science.gov (United States)

    Hymel, Glenn M; Rich, Grant J

    2014-04-01

    Health psychology represents a context within which massage therapy research, education, and practice can be positioned for the mutual benefit of both. Furthermore, complementary and alternative medicine (CAM) more often than not plays a mediating role in relating massage therapy to health psychology. On occasion, though, the linkage between health psychology and massage therapy can be quite direct without the mediating influence of CAM. This paper, accordingly, advances a conceptual model via both flowchart and Venn diagram displays for viewing the health psychology context for massage therapy with the possibility of CAM as a mediating factor. Attention is also given to the broad range of issues constituting contemporary health psychology as well as its correspondence to an equally diverse array of client populations and health conditions addressed in massage therapy research. Future directions in the areas of health psychology, CAM, and massage therapy are proposed with a view toward a mutual and reciprocal benefit accruing to these behavioral and health science arenas. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Sustainable growth of EU economies and Baltic context: Characteristics and modelling

    Directory of Open Access Journals (Sweden)

    Girts Karnitis

    2017-05-01

    Full Text Available The united general growth strategy for all EU Member States, a common economic and political vision as well as location in the same geographic region provides a necessary basis for the benchmarking modelling of economies. The main objective of this study is determination of the functional regularities and drivers of the growth of EU economies and the context of the Baltic States in line with the general trend of the EU, as well as development of the growth model, which can be used for sustainable planning and prediction. Analysis of several regularly published analytical indexes suggests a thesis on innovation as the real basic driving force for EU economies and outlines Innovation Performance Index, which have a very strong compliance with the economic growth of particular country. At the same time study of the data set and methodology of the Index indicates space for further optimization. By use of several linear regression tools the growth model was created. It is based on three hard independent statistical indicators (predictors only; of course, these indicators is a peak of a complex pyramid. Despite of the simplicity of the model, the long-term correlation of fitted values with the real GDP per capita is extremely strong 0.961 – 0.987.

  11. An evaluation of a psychosocial stress and coping model in the police work context

    Directory of Open Access Journals (Sweden)

    Gerrit J. Louw

    2010-03-01

    Research purpose: The purpose of the study was to determine how Moos's hypothesised stress and coping model (1994 fitted a sample of police officers. Motivation for the study: The study was an attempt to understand police officers' unique needs and how the frequency and/or intensity of perceived stress could be reduced so that they would be able to cope more effectively with stress. Research design, approach and method: A non-experimental survey design, following the quantitative tradition, was used in pursuit of the research objectives. A random sample of 505 participants was extracted from a population of serving male and female police officers reflecting the typical South African ethnic groups. Structural equation modelling (SEM was used to establish the adequacy of between the hypothesised Moos model and the sample. Main findings: The hypothesised theoretical framework was disproved. A respecified model and inter-correlations confirm that some officers experience burnout, while, paradoxically, others continue to be unaffected because of the buffering effect of social support, personality factors and other resilience factors not revealed in this study. Practical/managerial implications: The study calls on police management for awareness of the negative health consequences of prolonged stressors. Simultaneously, employee assistance programmes could be directed to problem-solving strategies, perceived self-efficacy and learned resourcefulness to improve control over prolonged negative stress consequences among members. Contribution/value-add: This research provides a theoretical framework to understand, describe and assess individual well-being in the police work context.

  12. Dependence in probabilistic modeling Dempster-Shafer theory and probability bounds analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ferson, Scott [Applied Biomathematics, Setauket, NY (United States); Nelsen, Roger B. [Lewis & Clark College, Portland OR (United States); Hajagos, Janos [Applied Biomathematics, Setauket, NY (United States); Berleant, Daniel J. [Iowa State Univ., Ames, IA (United States); Zhang, Jianzhong [Iowa State Univ., Ames, IA (United States); Tucker, W. Troy [Applied Biomathematics, Setauket, NY (United States); Ginzburg, Lev R. [Applied Biomathematics, Setauket, NY (United States); Oberkampf, William L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    This report summarizes methods to incorporate information (or lack of information) about inter-variable dependence into risk assessments that use Dempster-Shafer theory or probability bounds analysis to address epistemic and aleatory uncertainty. The report reviews techniques for simulating correlated variates for a given correlation measure and dependence model, computation of bounds on distribution functions under a specified dependence model, formulation of parametric and empirical dependence models, and bounding approaches that can be used when information about the intervariable dependence is incomplete. The report also reviews several of the most pervasive and dangerous myths among risk analysts about dependence in probabilistic models.

  13. A comparative study of Caribbean return migration from Britain and France: towards a context-dependent explanation.

    Science.gov (United States)

    Byron, M; Condon, S

    1996-01-01

    "The currently dominant element in the labour migration from the Caribbean to Britain and France is a return flow of migrants. This paper focuses on the migrations from the Commonwealth and the French Caribbean to Britain and France respectively. While these migrations are historically similar in origin, subsequent differences in the colonial and immigration policies of Britain and France have resulted in divergent migration trends and experiences. New sources of data are drawn on in this comparative study of return migration to the Caribbean, providing up-to-date information on the size and demographic characteristics of the returnee populations. Equally important to this study is the section of the migrant population who are likely to remain in Europe. The authors argue that a comprehensive model of labour migration would need to incorporate the non-return situation in its dynamic entirety." excerpt

  14. Retrieval of context-associated memory is dependent on the Ca(v)3.2 T-type calcium channel.

    Science.gov (United States)

    Chen, Chien-Chang; Shen, Jhe-Wei; Chung, Ni-Chun; Min, Ming-Yuan; Cheng, Sin-Jong; Liu, Ingrid Y

    2012-01-01

    Among all voltage-gated calcium channels, the T-type Ca²⁺ channels encoded by the Ca(v)3.2 genes are highly expressed in the hippocampus, which is associated with contextual, temporal and spatial learning and memory. However, the specific involvement of the Ca(v)3.2 T-type Ca²⁺ channel in these hippocampus-dependent types of learning and memory remains unclear. To investigate the functional role of this channel in learning and memory, we subjected Ca(v)3.2 homozygous and heterozygous knockout mice and their wild-type littermates to hippocampus-dependent behavioral tasks, including trace fear conditioning, the Morris water-maze and passive avoidance. The Ca(v)3.2 ⁻/⁻ mice performed normally in the Morris water-maze and auditory trace fear conditioning tasks but were impaired in the context-cued trace fear conditioning, step-down and step-through passive avoidance tasks. Furthermore, long-term potentiation (LTP) could be induced for 180 minutes in hippocampal slices of WTs and Ca(v)3.2 ⁺/⁻ mice, whereas LTP persisted for only 120 minutes in Ca(v)3.2 ⁻/⁻ mice. To determine whether the hippocampal formation is responsible for the impaired behavioral phenotypes, we next performed experiments to knock down local function of the Ca(v)3.2 T-type Ca²⁺ channel in the hippocampus. Wild-type mice infused with mibefradil, a T-type channel blocker, exhibited similar behaviors as homozygous knockouts. Taken together, our results demonstrate that retrieval of context-associated memory is dependent on the Ca(v)3.2 T-type Ca²⁺ channel.

  15. Retrieval of context-associated memory is dependent on the Ca(v3.2 T-type calcium channel.

    Directory of Open Access Journals (Sweden)

    Chien-Chang Chen

    Full Text Available Among all voltage-gated calcium channels, the T-type Ca²⁺ channels encoded by the Ca(v3.2 genes are highly expressed in the hippocampus, which is associated with contextual, temporal and spatial learning and memory. However, the specific involvement of the Ca(v3.2 T-type Ca²⁺ channel in these hippocampus-dependent types of learning and memory remains unclear. To investigate the functional role of this channel in learning and memory, we subjected Ca(v3.2 homozygous and heterozygous knockout mice and their wild-type littermates to hippocampus-dependent behavioral tasks, including trace fear conditioning, the Morris water-maze and passive avoidance. The Ca(v3.2 ⁻/⁻ mice performed normally in the Morris water-maze and auditory trace fear conditioning tasks but were impaired in the context-cued trace fear conditioning, step-down and step-through passive avoidance tasks. Furthermore, long-term potentiation (LTP could be induced for 180 minutes in hippocampal slices of WTs and Ca(v3.2 ⁺/⁻ mice, whereas LTP persisted for only 120 minutes in Ca(v3.2 ⁻/⁻ mice. To determine whether the hippocampal formation is responsible for the impaired behavioral phenotypes, we next performed experiments to knock down local function of the Ca(v3.2 T-type Ca²⁺ channel in the hippocampus. Wild-type mice infused with mibefradil, a T-type channel blocker, exhibited similar behaviors as homozygous knockouts. Taken together, our results demonstrate that retrieval of context-associated memory is dependent on the Ca(v3.2 T-type Ca²⁺ channel.

  16. Asymptotic distribution of motifs in a stochastic context-free grammar model of RNA folding.

    Science.gov (United States)

    Poznanović, Svetlana; Heitsch, Christine E

    2014-12-01

    We analyze the distribution of RNA secondary structures given by the Knudsen-Hein stochastic context-free grammar used in the prediction program Pfold. Our main theorem gives relations between the expected number of these motifs--independent of the grammar probabilities. These relations are a consequence of proving that the distribution of base pairs, of helices, and of different types of loops is asymptotically Gaussian in this model of RNA folding. Proof techniques use singularity analysis of probability generating functions. We also demonstrate that these asymptotic results capture well the expected number of RNA base pairs in native ribosomal structures, and certain other aspects of their predicted secondary structures. In particular, we find that the predicted structures largely satisfy the expected relations, although the native structures do not.

  17. The nuclear agreement with Germany in the context of Brazilian 'model' and the crisis

    International Nuclear Information System (INIS)

    Rosa, L.P.; Pires, R.L.N.F.

    1984-01-01

    The Brazilian Nuclear Program is discussed in the context of the so-called Brazilian 'model' which conditions the industrial and technological structure of Brazil. The relations between the Brazilian private industry, the Brazilian state industry and the foreign multinational industry in the nuclear agreement Brazil - Germany are indicated. The economic crisis, the 'energy crisis', the mistakes of the nuclear program, the political fight for the revision of the agreement, the present situation and the problems of technological transfer are also discussed. Some alternatives are suggested for NUCLEBRAS. In an annex, comments are made on the question of Brazilian reactors safety. The so-called system of Protection to the Nucleare Program is also mentioned. (I. de C.R.) [pt

  18. Models and numerical methods for time- and energy-dependent particle transport

    Energy Technology Data Exchange (ETDEWEB)

    Olbrant, Edgar

    2012-04-13

    Particles passing through a medium can be described by the Boltzmann transport equation. Therein, all physical interactions of particles with matter are given by cross sections. We compare different analytical models of cross sections for photons, electrons and protons to state-of-the-art databases. The large dimensionality of the transport equation and its integro-differential form make it analytically difficult and computationally costly to solve. In this work, we focus on the following approximative models to the linear Boltzmann equation: (i) the time-dependent simplified P{sub N} (SP{sub N}) equations, (ii) the M{sub 1} model derived from entropy-based closures and (iii) a new perturbed M{sub 1} model derived from a perturbative entropy closure. In particular, an asymptotic analysis for SP{sub N} equations is presented and confirmed by numerical computations in 2D. Moreover, we design an explicit Runge-Kutta discontinuous Galerkin (RKDG) method to the M{sub 1} model of radiative transfer in slab geometry and construct a scheme ensuring the realizability of the moment variables. Among other things, M{sub 1} numerical results are compared with an analytical solution in a Riemann problem and the Marshak wave problem is considered. Additionally, we rigorously derive a new hierarchy of kinetic moment models in the context of grey photon transport in one spatial dimension. For the perturbed M{sub 1} model, we present numerical results known as the two beam instability or the analytical benchmark due to Su and Olson and compare them to the standard M{sub 1} as well as transport solutions.

  19. Context-dependent consequences of Marenzelleria spp. (Spionidae: Polychaeta invasion for nutrient cycling in the Northern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Alexey Maximov

    2015-10-01

    Full Text Available Marenzelleria spp. are among the most successful non-native benthic species in the Baltic Sea. These burrowing polychaetes dig deeper than most native Baltic species, performing previously lacking ecosystem functions. We examine evidence from experiments, field sampling and modelling that the introduction of Marenzelleria spp. affects nutrient cycling and biogeochemical processes at the sediment–water interface. Over longer time scales, bioirrigation by Marenzelleria spp. has the potential to increase phosphorus retention in bottom deposits because of deeper oxygen penetration into sediments and formation of a deeper oxidized layer. In contrast, nitrogen fluxes from the sediment increase. As a consequence of a decline of the phosphate concentration and/or rising nitrogen/phosphorus ratio, some Northern Baltic ecosystems may experience improvement of the environment because of mitigation of eutrophication and harmful cyanobacteria blooms. Although it is difficult to unambiguously estimate the ecosystem-level consequences of invasion, in many cases it could be considered as positive due to increased structural and functional diversity. The long-term interactions with the native fauna still remain unknown, however, and in this paper we highlight the major knowledge gaps.

  20. Context-dependent interactive effects of non-lethal predation on larvae impact adult longevity and body composition

    Science.gov (United States)

    Kandregula, Samyuktha Rao; Quader, Suhel; Juliano, Steven A.

    2018-01-01

    Predation impacts development, behavior and morphology of prey species thereby shaping their abundances, distribution and community structure. Non-lethal threat of predation, specifically, can have a strong influence on prey lifehistory characteristics. While investigations often focus on the impact of predation threat on prey in isolation, tests of its interactive effects with food availability and resource competition on prey survival and fitness can improve understanding of costs, benefits and trade-offs of anti-predator strategies. This study, involving Aedes aegypti mosquitoes as a model organism, investigates both simple and interactive effects of predation threat during the larval stage on survival, size at and time to maturity, stored teneral reserves of glycogen, protein and lipid in adults, and adult longevity. Our results show that development times of mosquito larvae were increased (by 14.84% in males and by 97.63% in females), and size of eclosing adults decreased (by 62.30% in males and by 58.33% in females) when exposed to lowered nutrition and elevated intraspecific competition, but that predation had no detectable effect on these simple traits. Teneral reserves of glycogen, protein and lipid and adult longevity were positively correlated with adult body size. Non-lethal predation threat had significant interactive effects with nutrition and larval competition on teneral reserves in males and adult longevity in males and females. The sexes responded differently to conditions encountered as larvae, with the larval environment affecting development and adult characteristics more acutely for females than for males. The outcome of this study shows how threat of predation on juveniles can have long-lasting effects on adults that are likely to impact mosquito population dynamics and that may impact disease transmission. PMID:29401513

  1. Simulation of time-dependent Heisenberg models in one dimension

    DEFF Research Database (Denmark)

    Volosniev, A. G.; Hammer, H. -W.; Zinner, N. T.

    2016-01-01

    constants can be manipulated by time-dependent driving of the shape of the external confinement. As illustrative examples, we consider a harmonic trapping potential with a variable frequency and an infinite square well potential with a time-dependent barrier in the middle.......In this Letter, we provide a theoretical analysis of strongly interacting quantum systems confined by a time-dependent external potential in one spatial dimension. We show that such systems can be used to simulate spin chains described by Heisenberg Hamiltonians in which the exchange coupling...

  2. On the energy dependence of the optical model of neutron scattering from niobium

    International Nuclear Information System (INIS)

    Smith, A.B.; Guenther, P.T.; Lawson, R.D.

    1986-01-01

    Neutron differential-elastic-scattering cross sections of niobium were measured from 1.5 to 10.0 MeV at intervals of 0 . The observed values were interpreted in the context of the spherical optical-statistical model. It was found that the volume integral of the real potential decreased with energy whereas the integral of the imaginary potential increased. The energy dependence in both cases was consistent with a linear variation. There is a dispersion relationship between the real and imaginary potentials, and when this was used, in conjunction with the experimental imaginary potential, it was possible to predict the observed energy dependence of the real potential to a good degree of accuracy, thus supporting the consistency of the data and its analysis. The real-potential well depths needed to give the correct binding energies of the 2dsub(5/2), 3ssub(1/2), 2dsub(3/2) and 1gsub(7/2) particle states and of the 1gsub(9/2) hole state are in reasonable agreement with those given by a linear extrapolation of our neutron-scattering-based potential. However, the well depths needed to give the observed of the 2psub(3/2), 1fsub(5/2) and 2psub(1/2) hole states are about 10% less than the extrapolated values. (orig.)

  3. How Users Search the Mobile Web: A Model for Understanding the Impact of Motivation and Context on Search Behaviors

    Directory of Open Access Journals (Sweden)

    Dan Wu

    2016-03-01

    Full Text Available Purpose: This study explores how search motivation and context influence mobile Web search behaviors. Design/methodology/approach: We studied 30 experienced mobile Web users via questionnaires, semi-structured interviews, and an online diary tool that participants used to record their daily search activities. SQLite Developer was used to extract data from the users' phone logs for correlation analysis in Statistical Product and Service Solutions (SPSS. Findings: One quarter of mobile search sessions were driven by two or more search motivations. It was especially difficult to distinguish curiosity from time killing in particular user reporting. Multi-dimensional contexts and motivations influenced mobile search behaviors, and among the context dimensions, gender, place, activities they engaged in while searching, task importance, portal, and interpersonal relations (whether accompanied or alone when searching correlated with each other. Research limitations: The sample was comprised entirely of college students, so our findings may not generalize to other populations. More participants and longer experimental duration will improve the accuracy and objectivity of the research. Practical implications: Motivation analysis and search context recognition can help mobile service providers design applications and services for particular mobile contexts and usages. Originality/value: Most current research focuses on specific contexts, such as studies on place, or other contextual influences on mobile search, and lacks a systematic analysis of mobile search context. Based on analysis of the impact of mobile search motivations and search context on search behaviors, we built a multi-dimensional model of mobile search behaviors.

  4. Snowpack modeling in the context of radiance assimilation for snow water equivalent mapping

    Science.gov (United States)

    Durand, M. T.; Kim, R. S.; Li, D.; Dumont, M.; Margulis, S. A.

    2017-12-01

    Data assimilation is often touted as a means of overcoming deficiences in both snowpack modeling and snowpack remote sensing. Direct assimilation of microwave radiances, rather than assimilating microwave retrievals, has shown promise, in this context. This is especially the case for deep mountain snow, which is often assumed to be infeasible to measure with microwave measurements, due to saturation issues. We first demonstrate that the typical way of understanding saturation has often been misunderstood. We show that deep snow leads to a complex microwave signature, but not to saturation per se, because of snowpack stratigraphy. This explains why radiance assimilation requires detailed snowpack models that adequatley stratgigraphy to function accurately. We examine this with two case studies. First, we show how the CROCUS predictions of snowpack stratigraphy allows for assimilation of airborne passive microwave measurements over three 1km2 CLPX Intensive Study Areas. Snowpack modeling and particle filter analysis is performed at 120 m spatial resolution. When run without the benefit of radiance assimilation, CROCUS does not fully capture spatial patterns in the data (R2=0.44; RMSE=26 cm). Assimlilation of microwave radiances for a single flight recovers the spatial pattern of snow depth (R2=0.85; RMSE = 13 cm). This is despite the presence of deep snow; measured depths range from 150 to 325 cm. Adequate results are obtained even for partial forest cover, and bias in precipitation forcing. The results are severely degraded if a three-layer snow model is used, however. The importance of modeling snowpack stratigraphy is highlighted. Second, we compare this study to a recent analysis assimilating spaceborne radiances for a 511 km2 sub-watershed of the Kern River, in the Sierra Nevada. Here, the daily Level 2A AMSR-E footprints (88 km2) are assimilated into a model running at 90 m spatial resolution. The three-layer model is specially adapted to predict "effective

  5. NOX5-L can stimulate proliferation and apoptosis depending on its levels and cellular context, determining cancer cell susceptibility to cisplatin

    Science.gov (United States)

    Kwon, Eun-Soo; Lim, Jae Cheong; Park, Sung Sup; Kwon, Ki-Sun

    2015-01-01

    The NADPH oxidase, NOX5, is known to stimulate cell proliferation in some cancers by generating reactive oxygen species (ROS). We show here that the long form of NOX5 (NOX5-L) also promotes cell death, and thus determines the balance of proliferation and death, in skin, breast and lung cancer cells. Moderate expression of NOX5-L induced cell proliferation accompanied by AKT and ERK phosphorylation, whereas an increase in NOX5-L above a certain threshold promoted cancer cell death accompanied by caspase-3 activation. Notably, cisplatin treatment increased NOX5-L levels through CREB activation and enhanced NOX5-L activity through augmentation of Ca2+ release and c-Abl expression, ultimately triggering ROS-mediated cancer cell death—a distinct pathway absent in normal cells. These results indicate that NOX5-L determines cellular responses in a concentration- and context-dependent manner. PMID:26513170

  6. Characterisation of the Context-Dependence of the Gene Concept in Research Articles. Possible Consequences for Teaching Concepts with Multiple Meanings

    Science.gov (United States)

    Flodin, Veronica S.

    2017-03-01

    The purpose of this study is to interpret and qualitatively characterise the content in some research articles and evaluate cases of possible difference in meanings of the gene concept used. Using a reformulation of Hirst's criteria of forms of knowledge, articles from five different sub-disciplines in biology (transmission genetic, molecular biology, genomics, developmental biology and population genetics) were characterised according to knowledge project, methods used and conceptual contexts. Depending on knowledge project, the gene may be used as a location of recombination, a target of regulatory proteins, a carrier of regulatory sequences, a cause in organ formation or a basis for a genetic map. Methods used range from catching wild birds and dissecting beetle larvae to growing yeast cells in 94 small wells as well as mapping of recombinants, doing statistical calculations, immunoblotting analysis of protein levels, analysis of gene expression with PCR, immunostaining of embryos and automated constructions of multi-locus linkage maps. The succeeding conceptual contexts focused around concepts as meiosis and chromosome, DNA and regulation, cell fitness and production, development and organ formation, conservation and evolution. These contextual differences lead to certain content leaps in relation to different conceptual schemes. The analysis of the various uses of the gene concept shows how differences in methodologies and questions entail a concept that escapes single definitions and "drift around" in meanings. These findings make it important to ask how science might use concepts as tools of specific inquiries and to discuss possible consequences for biology education.

  7. The social contexts of depression during motherhood: a study of Explanatory Models in Vietnam.

    Science.gov (United States)

    Niemi, Maria E; Falkenberg, Torkel; Nguyen, Mai T T; Nguyen, Minh T N; Patel, Vikram; Faxelid, Elisabeth

    2010-07-01

    Major depression is increasing world-wide, and is the fourth leading cause of the global disease burden. Depression is rarely diagnosed in primary care settings in Vietnam, and those afflicted usually only seek professional care when the illness has become very severe. Depressive disorders affecting mothers are an important cause of low birth-weight, childhood stunting, under nutrition and adverse mental development, and a study has shown a 33% prevalence of postnatal depression symptoms in Ho Chi Minh City. The aim of this study was to elicit Illness Explanatory Models (EMs) of depression and postnatal depression from nine mothers and nine health workers. The study was conducted in a semi-rural area in Vietnam, and the EMs were elicited through semi-structured interviews where a case vignette of depression was used as the basis of questioning. The EMs elicited were predominantly somatosocial in nature and the mothers assigned a strong personal responsibility for care. Psychiatric treatment and care was seldom recommended. Lack of communication was described as an important factor concealing depression, and together with the lack of care-seeking can be expected to impede effective treatment. The results of this study cannot be generalised beyond the group studied, or the context of Ba Vi, though we believe that analytical generalisation to other contexts can be made. CONCLUSION (CLINICAL RELEVANCE): The results of this study highlight the importance of depression and postnatal depression being diagnosed in primary care, and of a cross-sectoral approach for the prevention of depression in Vietnam, which takes into account the social causation of depression in women.

  8. Dual-Source Linear Energy Prediction (LINE-P) Model in the Context of WSNs.

    Science.gov (United States)

    Ahmed, Faisal; Tamberg, Gert; Le Moullec, Yannick; Annus, Paul

    2017-07-20

    Energy harvesting technologies such as miniature power solar panels and micro wind turbines are increasingly used to help power wireless sensor network nodes. However, a major drawback of energy harvesting is its varying and intermittent characteristic, which can negatively affect the quality of service. This calls for careful design and operation of the nodes, possibly by means of, e.g., dynamic duty cycling and/or dynamic frequency and voltage scaling. In this context, various energy prediction models have been proposed in the literature; however, they are typically compute-intensive or only suitable for a single type of energy source. In this paper, we propose Linear Energy Prediction "LINE-P", a lightweight, yet relatively accurate model based on approximation and sampling theory; LINE-P is suitable for dual-source energy harvesting. Simulations and comparisons against existing similar models have been conducted with low and medium resolutions (i.e., 60 and 22 min intervals/24 h) for the solar energy source (low variations) and with high resolutions (15 min intervals/24 h) for the wind energy source. The results show that the accuracy of the solar-based and wind-based predictions is up to approximately 98% and 96%, respectively, while requiring a lower complexity and memory than the other models. For the cases where LINE-P's accuracy is lower than that of other approaches, it still has the advantage of lower computing requirements, making it more suitable for embedded implementation, e.g., in wireless sensor network coordinator nodes or gateways.

  9. HIV-1 envelope glycoprotein resistance to monoclonal antibody 2G12 is subject-specific and context-dependent in macaques and humans.

    Directory of Open Access Journals (Sweden)

    Delphine C Malherbe

    Full Text Available HIV-1 Envelope (Env protein is the sole target of neutralizing antibodies (NAbs that arise during infection to neutralize autologous variants. Under this immune pressure, HIV escape variants are continuously selected and over the course of infection Env becomes more neutralization resistant. Many common alterations are known to affect sensitivity to NAbs, including residues encoding potential N-linked glycosylation sites (PNGS. Knowledge of Env motifs associated with neutralization resistance is valuable for the design of an effective Env-based vaccine so we characterized Envs isolated longitudinally from a SHIV(SF162P4 infected macaque for sensitivity to neutralizing monoclonal antibodies (MAbs B12, 2G12, 4E10 and 2F5. The early Env, isolated from plasma at day 56 after infection, was the most sensitive and the late Env, from day 670, was the most resistant to MAbs. We identified four PNGS in these Envs that accumulated over time at positions 130, 139, 160 and 397. We determined that removal of these PNGS significantly increased neutralization sensitivity to 2G12, and conversely, we identified mutations by in silico analyses that contributed resistance to 2G12 neutralization. In order to expand our understanding of these PNGS, we analyzed Envs from clade B HIV-infected human subjects and identified additional glycan and amino acid changes that could affect neutralization by 2G12 in a context-dependent manner. Taken together, these in vitro and in silico analyses of clade B Envs revealed that 2G12 resistance is achieved by previously unrecognized PNGS substitutions in a context-dependent manner and by subject-specific pathways.

  10. Modeling the Economic Behavior of Households within the Context of Development of Economic Thought

    Directory of Open Access Journals (Sweden)

    Ivanov Roman V.

    2017-04-01

    Full Text Available The main purpose of the publication is to study formation of the household economic behavior modeling in the context of development of economic thought and methods of the economic-mathematical modeling. The study was carried out under the assumption that, when studying the development of theoretical and methodological foundations of the economic behavior of households one must take into account not only the history of development of economic theory, but also the transformation of attitudes in other areas of human knowledge, in particular the paradigm shift in scientific thinking. It has been specified that the massive use of mathematical methods in economics is associated with formation of the marginal theory and at the same time – with the proliferation of the marginal analysis. At the present stage, the economic behavior of households is being analyzed in the terms of concepts such as neoclassicism, institutionalism and behaviorism. But by dividing the concepts of «individual» and «household», it can be argued that precisely the institutionalism in conjunction with synergistic approach provide the basis for elaboration of strategies for the economic behavior of households, ensuring their economic security.

  11. Going Global: A Model for Evaluating Empirically Supported Family-Based Interventions in New Contexts.

    Science.gov (United States)

    Sundell, Knut; Ferrer-Wreder, Laura; Fraser, Mark W

    2014-06-01

    The spread of evidence-based practice throughout the world has resulted in the wide adoption of empirically supported interventions (ESIs) and a growing number of controlled trials of imported and culturally adapted ESIs. This article is informed by outcome research on family-based interventions including programs listed in the American Blueprints Model and Promising Programs. Evidence from these controlled trials is mixed and, because it is comprised of both successful and unsuccessful replications of ESIs, it provides clues for the translation of promising programs in the future. At least four explanations appear plausible for the mixed results in replication trials. One has to do with methodological differences across trials. A second deals with ambiguities in the cultural adaptation process. A third explanation is that ESIs in failed replications have not been adequately implemented. A fourth source of variation derives from unanticipated contextual influences that might affect the effects of ESIs when transported to other cultures and countries. This article describes a model that allows for the differential examination of adaptations of interventions in new cultural contexts. © The Author(s) 2012.

  12. Challenges and gaps for energy planning models in the developing-world context

    Science.gov (United States)

    Debnath, Kumar Biswajit; Mourshed, Monjur

    2018-03-01

    Energy planning models (EPMs) support multi-criteria assessments of the impact of energy policies on the economy and environment. Most EPMs originated in developed countries and are primarily aimed at reducing greenhouse gas emissions while enhancing energy security. In contrast, most, if not all, developing countries are predominantly concerned with increasing energy access. Here, we review thirty-four widely used EPMs to investigate their applicability to developing countries and find an absence of consideration of the objectives, challenges, and nuances of the developing context. Key deficiencies arise from the lack of deliberation of the low energy demand resulting from lack of access and availability of supply. Other inadequacies include the lack of consideration of socio-economic nuances such as the prevalence of corruption and resulting cost inflation, the methods for adequately addressing the shortcomings in data quality, availability and adequacy, and the effects of climate change. We argue for further research on characterization and modelling of suppressed demand, climate change impacts, and socio-political feedback in developing countries, and the development of contextual EPMs.

  13. A Hierarchical Multi-Output Nearest Neighbor Model for Multi-Output Dependence Learning

    OpenAIRE

    Morris, Richard G.; Martinez, Tony; Smith, Michael R.

    2014-01-01

    Multi-Output Dependence (MOD) learning is a generalization of standard classification problems that allows for multiple outputs that are dependent on each other. A primary issue that arises in the context of MOD learning is that for any given input pattern there can be multiple correct output patterns. This changes the learning task from function approximation to relation approximation. Previous algorithms do not consider this problem, and thus cannot be readily applied to MOD problems. To pe...

  14. Challenges and priorities for modelling livestock health and pathogens in the context of climate change.

    Science.gov (United States)

    Özkan, Şeyda; Vitali, Andrea; Lacetera, Nicola; Amon, Barbara; Bannink, André; Bartley, Dave J; Blanco-Penedo, Isabel; de Haas, Yvette; Dufrasne, Isabelle; Elliott, John; Eory, Vera; Fox, Naomi J; Garnsworthy, Phil C; Gengler, Nicolas; Hammami, Hedi; Kyriazakis, Ilias; Leclère, David; Lessire, Françoise; Macleod, Michael; Robinson, Timothy P; Ruete, Alejandro; Sandars, Daniel L; Shrestha, Shailesh; Stott, Alistair W; Twardy, Stanislaw; Vanrobays, Marie-Laure; Ahmadi, Bouda Vosough; Weindl, Isabelle; Wheelhouse, Nick; Williams, Adrian G; Williams, Hefin W; Wilson, Anthony J; Østergaard, Søren; Kipling, Richard P

    2016-11-01

    Climate change has the potential to impair livestock health, with consequences for animal welfare, productivity, greenhouse gas emissions, and human livelihoods and health. Modelling has an important role in assessing the impacts of climate change on livestock systems and the efficacy of potential adaptation strategies, to support decision making for more efficient, resilient and sustainable production. However, a coherent set of challenges and research priorities for modelling livestock health and pathogens under climate change has not previously been available. To identify such challenges and priorities, researchers from across Europe were engaged in a horizon-scanning study, involving workshop and questionnaire based exercises and focussed literature reviews. Eighteen key challenges were identified and grouped into six categories based on subject-specific and capacity building requirements. Across a number of challenges, the need for inventories relating model types to different applications (e.g. the pathogen species, region, scale of focus and purpose to which they can be applied) was identified, in order to identify gaps in capability in relation to the impacts of climate change on animal health. The need for collaboration and learning across disciplines was highlighted in several challenges, e.g. to better understand and model complex ecological interactions between pathogens, vectors, wildlife hosts and livestock in the context of climate change. Collaboration between socio-economic and biophysical disciplines was seen as important for better engagement with stakeholders and for improved modelling of the costs and benefits of poor livestock health. The need for more comprehensive validation of empirical relationships, for harmonising terminology and measurements, and for building capacity for under-researched nations, systems and health problems indicated the importance of joined up approaches across nations. The challenges and priorities identified can

  15. The Eurasian Model of International Labour Legislation in the Context of Globalization

    Directory of Open Access Journals (Sweden)

    Andrey Lushnikov

    2016-01-01

    Full Text Available The current article seeks to provide a comparative legal analysis of the Eurasian model of international labor legislation. It explores the multi-layered nature of contemporary international labor law in the context of globalization and regionalization, emphasizing the growing importance of cross-border legal labor standards in regional structures in the early 21st century and defines how global and regional cross-border legislation is incorporated on the basis of in favorem. The authors propose their own original concept of international labor legislation, based on the four characteristics: 1 The overall aim of legal regulation; 2 The extent of integration within those regulations; 3 Sources of labor law and their characteristics; 4 Systems of international control over labor rights. To define an original model for the legal regulation of labor, the authors investigate case studies of labour legal regulation in inter-state regional organizations including the European Union, the Council of Europe and ASEAN. The authors’ theoretical model identifies the defining features of Eurasia’s model of labor regulation. The research also follows the establishment and development of Eurasian labor law and attempts to give an informed judgment about its future path. In their conclusions, the authors assert that modern Eurasian labor law is a ‘live law’, still under development as it incorporates the non-uniform integration between the former Soviet Republics. Two primary trends leading regional co-operation in the labor market are identified: 1 A social model, implementing international labor rights across Eurasia; 2 An economic model, built on the free movement of labor in a common market. In today’s environment, the Commonwealth of Independent States goes some way toward representing the first trend through its attempts to serve as an international coordinating organization. The second trend is supported by supranational organizations promoting

  16. 3D modelling in salt tectonic context: the Crocodile minibasin in Sivas (Turkey)

    Science.gov (United States)

    Collon, Pauline; Pichat, Alexandre; Kergaravat, Charlie; Botella, Arnaud; Caumon, Guillaume; Favreau, Océane; Fuss, Gaétan; Godefroy, Gabriel; Lerat, Marine; Mazuyer, Antoine; Parquer, Marion; Charreau, Julien; Callot, Jean-Paul; Ringenbach, Jean-Claude

    2015-04-01

    Impermeable, with a low density and acting as a viscous fluid at the geological time scale, salt plays a unique tectonic role favouring hydrocarbon trap formations. Halokinetic structures are various and difficult to image with classic seismic techniques. Thus, outcrop analogues are precious and sought after. Since the re-interpretation in September 2011 of its evaporite deposits, the Oligo-Miocene basin of Sivas (Turkey) is a new choice analogue for the study of salt tectonic with outstanding outcrops reflecting the variety of salt related structures: minibasins, diapirs, welds... While studying these structures requires an important field work, building 3D models becomes an interesting way to better help understanding the three-dimensional organisation and to further perform numerical simulations (e.g., restoration, potential field measurement campaign simulation). The complex geometries observed in salt tectonic context make these 3D geological models particularly challenging to build, especially when only outcrops data are available. We focus on the Crocodile minibasin (Sivas) and present a modelling strategy using a subtle combination of recently developed techniques. Available data are: a Digital Elevation Model, satellite images and associated interpreted bedding traces on topography, orientation measurements of the strata and a conceptual interpretation. Located on an ancient salt extrusion, this minibasin is filled with lacustrine and sabkha sediments. It is interpreted with a closed synclinal structure on North. On its southern part, a central diapir has risen up, separating two tightened synclinals. The salt surface is modelled first as a triangulated surface using a classical explicit surface patch construction method and a manual post-process mesh improvement. Then, the minibasin sediments are modelled with an implicit approach that considers interfaces as equipotentials of a 3D scalar field. This requires to build a volumetric mesh conformable to the

  17. A congested and dwell time dependent transit corridor assignment model

    OpenAIRE

    Alonso Oreña, Borja; Muñoz, Juan Carlos; Ibeas Portilla, Ángel; Moura Berodia, José Luis

    2016-01-01

    This research proposes an equilibrium assignment model for congested public transport corridors in urban areas. In this model, journey times incorporate the effect of bus queuing on travel times and boarding and alighting passengers on dwell times at stops. The model also considers limited bus capacity leading to longer waiting times and more uncomfortable journeys. The proposed model is applied to an example network, and the results are compared with those obtained in a recent study. This is...

  18. A dependence modelling study of extreme rainfall in Madeira Island

    Science.gov (United States)

    Gouveia-Reis, Délia; Guerreiro Lopes, Luiz; Mendonça, Sandra

    2016-08-01

    The dependence between variables plays a central role in multivariate extremes. In this paper, spatial dependence of Madeira Island's rainfall data is addressed within an extreme value copula approach through an analysis of maximum annual data. The impact of altitude, slope orientation, distance between rain gauge stations and distance from the stations to the sea are investigated for two different periods of time. The results obtained highlight the influence of the island's complex topography on the spatial distribution of extreme rainfall in Madeira Island.

  19. Temperature-dependent rate models of vascular cambium cell mortality

    Science.gov (United States)

    Matthew B. Dickinson; Edward A. Johnson

    2004-01-01

    We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of...

  20. Adaptive cerebellar spiking model embedded in the control loop: context switching and robustness against noise.

    Science.gov (United States)

    Luque, N R; Garrido, J A; Carrillo, R R; Tolu, S; Ros, E

    2011-10-01

    This work evaluates the capability of a spiking cerebellar model embedded in different loop architectures (recurrent, forward, and forward&recurrent) to control a robotic arm (three degrees of freedom) using a biologically-inspired approach. The implemented spiking network relies on synaptic plasticity (long-term potentiation and long-term depression) to adapt and cope with perturbations in the manipulation scenario: changes in dynamics and kinematics of the simulated robot. Furthermore, the effect of several degrees of noise in the cerebellar input pathway (mossy fibers) was assessed depending on the employed control architecture. The implemented cerebellar model managed to adapt in the three control architectures to different dynamics and kinematics providing corrective actions for more accurate movements. According to the obtained results, coupling both control architectures (forward&recurrent) provides benefits of the two of them and leads to a higher robustness against noise.