990 resultados para Descriptive models


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Seizure freedom in patients suffering from pharmacoresistant epilepsies is still not achieved in 20–30% of all cases. Hence, current therapies need to be improved, based on a more complete understanding of ictogenesis. In this respect, the analysis of functional networks derived from intracranial electroencephalographic (iEEG) data has recently become a standard tool. Functional networks however are purely descriptive models and thus are conceptually unable to predict fundamental features of iEEG time-series, e.g., in the context of therapeutical brain stimulation. In this paper we present some first steps towards overcoming the limitations of functional network analysis, by showing that its results are implied by a simple predictive model of time-sliced iEEG time-series. More specifically, we learn distinct graphical models (so called Chow–Liu (CL) trees) as models for the spatial dependencies between iEEG signals. Bayesian inference is then applied to the CL trees, allowing for an analytic derivation/prediction of functional networks, based on thresholding of the absolute value Pearson correlation coefficient (CC) matrix. Using various measures, the thus obtained networks are then compared to those which were derived in the classical way from the empirical CC-matrix. In the high threshold limit we find (a) an excellent agreement between the two networks and (b) key features of periictal networks as they have previously been reported in the literature. Apart from functional networks, both matrices are also compared element-wise, showing that the CL approach leads to a sparse representation, by setting small correlations to values close to zero while preserving the larger ones. Overall, this paper shows the validity of CL-trees as simple, spatially predictive models for periictal iEEG data. Moreover, we suggest straightforward generalizations of the CL-approach for modeling also the temporal features of iEEG signals.

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The international tourism system has deeply undergone structural changes in the last decades which not remain outside the subsystem higher education in tourism, especially in the European case. This article has two objectives: firstly, describes the European higher education area and the objectives, skills and subjects taught in the main Spanish universities that offer higher education in tourism. On the other hand, in the light of knowledge that researchers' descriptive models, provide experience of the implementation of European credit and thorough a deeply review of the literature on the topic higher education in tourism, to propose strategies that will enable other tourism higher education systems approach to the European reality. These policy proposals are aimed at agents and elements from higher education in tourism subsystem and they specifically include: the institutions providing education in tourism, the curriculum, the teaching methods, teachers and students.

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In this study, the metabolomics characterization focusing on the carotenoid composition of ten cassava (Manihot esculenta) genotypes cultivated in southern Brazil by UV-visible scanning spectrophotometry and reverse phase-high performance liquid chromatography was performed. Cassava roots rich in -carotene are an important staple food for populations with risk of vitamin A deficiency. Cassava genotypes with high pro-vitamin A activity have been identified as a strategy to reduce the prevalence of deficiency of this vitamin. The data set was used for the construction of a descriptive model by chemometric analysis. The genotypes of yellow-fleshed roots were clustered by the higher concentrations of cis--carotene and lutein. Inversely, cream-fleshed roots genotypes were grouped precisely due to their lower concentrations of these pigments, as samples rich in lycopene (redfleshed) differed among the studied genotypes. The analytical approach (UV-Vis, HPLC, and chemometrics) used showed to be efficient for understanding the chemodiversity of cassava genotypes, allowing to classify them according to important features for human health and nutrition.

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Simple Heuristics in a Social World invites readers to discover the simple heuristics that people use to navigate the complexities and surprises of environments populated with others. The social world is a terrain where humans and other animals compete with conspecifics for myriad resources, including food, mates, and status, and where rivals grant the decision maker little time for deep thought, protracted information search, or complex calculations. Yet, the social world also encompasses domains where social animals such as humans can learn from one another and can forge alliances with one another to boost their chances of success. According to the book's thesis, the undeniable complexity of the social world does not dictate cognitive complexity as many scholars of rationality argue. Rather, it entails circumstances that render optimization impossible or computationally arduous: intractability, the existence of incommensurable considerations, and competing goals. With optimization beyond reach, less can be more. That is, heuristics--simple strategies for making decisions when time is pressing and careful deliberation an unaffordable luxury--become indispensible mental tools. As accurate as or even more accurate than complex methods when used in the appropriate social environments, these heuristics are good descriptive models of how people make many decisions and inferences, but their impressive performance also poses a normative challenge for optimization models. In short, the Homo socialis may prove to be a Homo heuristicus whose intelligence reflects ecological rather than logical rationality.

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This project is concerned with the way that illustrations, photographs, diagrams and graphs, and typographic elements interact to convey ideas on the book page. A framework for graphic description is proposed to elucidate this graphic language of ‘complex texts’. The model is built up from three main areas of study, with reference to a corpus of contemporary children’s science books. First, a historical survey puts the subjects for study in context. Then a multidisciplinary discussion of graphic communication provides a theoretical underpinning for the model; this leads to various proposals, such as the central importance of ratios and relationships among parts in creating meaning in graphic communication. Lastly a series of trials in description contribute to the structure of the model itself. At the heart of the framework is an organising principle that integrates descriptive models from fields of design, literary criticism, art history, and linguistics, among others, as well as novel categories designed specifically for book design. Broadly, design features are described in terms of elemental component parts (micro-level), larger groupings of these (macro-level), and finally in terms of overarching, ‘whole book’ qualities (meta-level). Various features of book design emerge at different levels; for instance, the presence of nested discursive structures, a form of graphic recursion in editorial design, is proposed at the macro-level. Across these three levels are the intersecting categories of ‘rule’ and ‘context’, offering different perspectives with which to describe graphic characteristics. Contextbased features are contingent on social and cultural environment, the reader’s previous knowledge, and the actual conditions of reading; rule-based features relate to the systematic or codified aspects of graphic language. The model aims to be a frame of reference for graphic description, of use in different forms of qualitative or quantitative research and as a heuristic tool in practice and teaching.

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Human brain imaging techniques, such as Magnetic Resonance Imaging (MRI) or Diffusion Tensor Imaging (DTI), have been established as scientific and diagnostic tools and their adoption is growing in popularity. Statistical methods, machine learning and data mining algorithms have successfully been adopted to extract predictive and descriptive models from neuroimage data. However, the knowledge discovery process typically requires also the adoption of pre-processing, post-processing and visualisation techniques in complex data workflows. Currently, a main problem for the integrated preprocessing and mining of MRI data is the lack of comprehensive platforms able to avoid the manual invocation of preprocessing and mining tools, that yields to an error-prone and inefficient process. In this work we present K-Surfer, a novel plug-in of the Konstanz Information Miner (KNIME) workbench, that automatizes the preprocessing of brain images and leverages the mining capabilities of KNIME in an integrated way. K-Surfer supports the importing, filtering, merging and pre-processing of neuroimage data from FreeSurfer, a tool for human brain MRI feature extraction and interpretation. K-Surfer automatizes the steps for importing FreeSurfer data, reducing time costs, eliminating human errors and enabling the design of complex analytics workflow for neuroimage data by leveraging the rich functionalities available in the KNIME workbench.

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This paper analyzes the effects of the mlmmum wage on both, eammgs and employment, using a Brazilian rotating panel data (Pesquisa Mensal do Emprego - PME) which has a similar design to the US Current Population Survey (CPS). First an intuitive description of the data is done by graphical analysis. In particular, Kemel densities are used to show that an increase in the minimum wage compresses the eamings distribution. This graphical analysis is then forrnalized by descriptive models. This is followed by a discussion on identification and endogeneity that leads to the respecification of the model. Second, models for employment are estimated, using an interesting decomposition that makes it possible to separate out the effects of an increase in the minimum wage on number of hours and on posts of jobs. The main result is that an increase in the minimum wage was found to compress the eamings distribution, with a moderately small effect on the leveI of employment, contributing to alleviate inequality.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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During Ocean Drilling Program Leg 123, two sites were drilled in the deep Indian Ocean. Physical properties were measured in soft Quaternary and Lower Cretaceous sediments to relatively fresh, glass-bearing pillow lavas and massive basalts. Porosities ranged from 89% near the seafloor to 1.6% for the dense basalts. This self-consistent set of measurements permitted some descriptive models of physical properties to be more rigorously tested than before. Predictive relationships between porosity and compressional-wave velocity have generally been based upon the Wyllie time average equation. However, this equation does not adequately describe the actual relationship between these two parameters, and many have attempted to improve it. In most cases, models were derived by testing them against a set of data representing a relatively narrow range of porosity values. Similarly, the use of the Wyllie equation has often been justified by a pseudolinear fit to the data over a narrow range of porosity values. The limitations of the Wyllie relationship have been re-emphasized here. A semi-empirical acoustic impedance equation is developed that provides a more accurate porosity-velocity transform, using realistic material parameters, than has hitherto been possible. A closer correlation can be achieved with this semi-empirical relationship than with more theoretically based equations. In addition, a satisfactory empirical equation can be used to describe the relationship between thermal conductivity and porosity. If enough is known about core sample lithologies to provide estimates of the matrix and pore water parameters, then these predictive equations enable one to describe completely the behavior of a saturated rock core in terms of compressional-wave velocity, thermal conductivity, porosity, and bulk density.

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Las nanopartículas de metales nobles (especialmente las de oro) tienen un gran potencial asociado al desarrollo de sistemas de terapia contra el cáncer debido principalmente a sus propiedades ópticas, ya que cuando son irradiadas con un haz de luz sintonizado en longitud de onda con su máximo de Resonancia de Plasmón Superficial, absorben de manera muy eficiente dicha luz y la disipan rápidamente al medio en forma de calor localizado. Esta característica por tanto, puede ser aprovechada para conseguir elevar la temperatura de células tumorales hasta sobrepasar umbrales a partir de los cuales se produciría la muerte celular. Partiendo de estos principios, esta tesis se centra en el desarrollo y la caracterización de una serie de prototipos de hipertermia óptica basados en la irradiación de nanopartículas de oro con un haz de luz adecuado, así como en la aplicación in vitro de la terapia sobre células cancerígenas. Además, el trabajo se orienta a identificar y comprender los procesos mecánicos y térmicos asociados a este tipo de hipertermia, y a desarrollar modelos que los describan, estudiando y planteando nuevas formas de irradiación, para, en última instancia, poder optimizar los procesos descritos y hacerlos más efectivos. Los resultados obtenidos indican que, el uso de nanopartículas de oro, y más concretamente de nanorods de oro, para llevar a cabo terapias de hipertermia óptica, permite desarrollar terapias muy efectivas para inducir muerte en células cancerígenas, especialmente en tumores superficiales, o como complemento quirúrgico en tumores internos. Sin embargo, los efectos de la toxicidad de las nanopartículas de oro, aún deben ser detalladamente estudiados, ya que este tipo de terapias sólo será viable si se consigue una completa biocompatibilidad. Por otro lado, el estudio exhaustivo de los procesos térmicos que tienen lugar durante la irradiación de las nanopartículas ha dado lugar a una serie de modelos que permiten determinar la efectividad fototérmica de las nanopartículas y además, visualizar la evolución de la temperatura tanto a escala nanométrica como a escala macrométrica, en función de los parámetros ópticos y térmicos del sistema. El planteamiento de nuevas formas de irradiación y el desarrollo de dispositivos orientados a estudiar los fenómenos mecánicos que tienen lugar durante la irradiación pulsada de baja frecuencia y baja potencia de nanopartículas de oro, ha dado lugar a la detección de ondas de presión asociadas a procesos de expansión termoelástica, abriendo la puerta al desarrollo de terapias de hipertermia que combinen la muerte celular producida por calentamiento con la muerte derivada de los fenómenos mecánicos descritos.VII Noble metal nanoparticles (especially gold ones), have a huge potential in the development of therapy systems against cancer mainly due to their optical properties, so that, when these particles are irradiated with a light that is syntonized in wavelength with their maximum of Surface Plasmon Resonance, they effectively absorb and dissipate the light to the surrounding medium as localized heat. We can take advantage of this characteristic for rising the temperature of cancer cells above the threshold at which cellular death would occur. From these principles, this thesis is oriented to the development and characterization of a series of optical hyperthermia prototypes based on the irradiation of gold nanoparticles using the suitable light, and on the in vitro application of this therapy over cancer cells, to understand the mechanical and thermal processes associated with this kind of hyperthermia, developing descriptive models, and to study and to approach new ways of irradiation in order to, ultimately, optimize the described processes and make them more effective. The obtained results show that, the use of gold nanoparticles, and more specifically, of gold nanorods, to carry out optical hyperthermia therapies, allows the development of very effective therapies in order to induce death in VIII cancer cells, especially in superficial tumors, or like surgical complement in more internal tumors. However, the toxicity effects of the gold nanoparticles still need to be studied more detail, because this kind of therapies will be feasible only if a complete biocompatibility is achieved. On the other hand, the exhaustive study of the thermal processes that take place during the irradiation of the nanoparticles resulted in a series of models that allow the determination of the photothermal efficiency of the nanoparticles and also the visualization of the temperature evolution, both at nanoscale and at macroscale, as a function of the optical and thermal parameters of the system. The proposal of new ways of irradiation and the development of devices oriented to study the mechanical effects that take place during the low frequency and low power pulsing irradiation of gold nanoparticles has led to the detection of pressure waves associated to thermoelastic expansion processes, opening the door to the development of hyperthermia therapies that combine the cellular death due to the heating with the death derived from the described mechanical phenomena.

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Descriptive models of social response are concerned with identifying and discriminating between different types of response to social influence. In a previous article (Nail, MacDonald, & Levy, 2000), the authors demonstrated that 4 conceptual dimensions are necessary to adequately distinguish between such phenomena as conformity, compliance, contagion, independence, and anticonformity in a single model. This article expands the scope of the authors' 4-dimensional approach by reviewing selected experimental and cultural evidence, further demonstrating the integrative power of the model. This review incorporates political psychology, culture and aggression, self-persuasion, group norms, prejudice, impression management, psychotherapy, pluralistic ignorance, bystander intervention/nonintervention, public policy, close relationships, and implicit attitudes.

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Metaphor has been widely discussed within the discipline of Translation Studies, predominantly with respect to translatability and transfer methods. It has been argued that metaphors can become a translation problem, since transferring them from one language and culture to another one may be hampered by linguistic and cultural differences. A number of translation procedures for dealing with this problem have been suggested, e.g., substitution (metaphor into different metaphor), paraphrase (metaphor into sense), or deletion. Such procedures have been commented on both in normative models of translation (how to translate metaphors) and in descriptive models (how metaphors have been dealt with in actual translations). After a short overview of how metaphor has been dealt with in the discipline of Translation Studies, this paper discusses some implications of a cognitive approach to metaphors for translation theory and practice. Illustrations from authentic source and target texts (English and German, political discourse) show how translators handled metaphorical expressions, and what effects this had for the text itself, for text reception by the addressees, and for subsequent discursive developments. © 2004 Elsevier B.V. All right reserved.

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The initial aim of this research was to investigate the application of expert Systems, or Knowledge Base Systems technology to the automated synthesis of Hazard and Operability Studies. Due to the generic nature of Fault Analysis problems and the way in which Knowledge Base Systems work, this goal has evolved into a consideration of automated support for Fault Analysis in general, covering HAZOP, Fault Tree Analysis, FMEA and Fault Diagnosis in the Process Industries. This thesis described a proposed architecture for such an Expert System. The purpose of the System is to produce a descriptive model of faults and fault propagation from a description of the physical structure of the plant. From these descriptive models, the desired Fault Analysis may be produced. The way in which this is done reflects the complexity of the problem which, in principle, encompasses the whole of the discipline of Process Engineering. An attempt is made to incorporate the perceived method that an expert uses to solve the problem; keywords, heuristics and guidelines from techniques such as HAZOP and Fault Tree Synthesis are used. In a truly Expert System, the performance of the system is strongly dependent on the high quality of the knowledge that is incorporated. This expert knowledge takes the form of heuristics or rules of thumb which are used in problem solving. This research has shown that, for the application of fault analysis heuristics, it is necessary to have a representation of the details of fault propagation within a process. This helps to ensure the robustness of the system - a gradual rather than abrupt degradation at the boundaries of the domain knowledge.

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Despite abundant literature on human behaviour in the face of danger, much remains to be discovered. Some descriptive models of behaviour in the face of danger are reviewed in order to identify areas where documentation is lacking. It is argued that little is known about recognition and assessment of danger and yet, these are important aspects of cognitive processes. Speculative arguments about hazard assessment are reviewed and tested against the results of previous studies. Once hypotheses are formulated, the reason for retaining the reportory grid as the main research instrument are outlined, and the choice of data analysis techniques is described. Whilst all samples used repertory grids, the rating scales were different between samples; therefore, an analysis is performed of the way in which rating scales were used in the various samples and of some reasons why the scales were used differently. Then, individual grids are looked into and compared between respondents within each sample; consensus grids are also discussed. the major results from all samples are then contrasted and compared. It was hypothesized that hazard assessment would encompass three main dimensions, i.e. 'controllability', 'severity of consequences' and 'likelihood of occurrence', which would emerge in that order. the results suggest that these dimensions are but facets of two broader dimensions labelled 'scope of human intervention' and 'dangerousness'. It seems that these two dimensions encompass a number of more specific dimensions some of which can be further fragmented. Thus, hazard assessment appears to be a more complex process about which much remains to be discovered. Some of the ways in which further discovery might proceed are discussed.

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La ricerca prende in esame la produzione della stampa periodica bibliografica italiana nel corso del Seicento e Settecento. Da un lato mira a ricostruirne il percorso storico attraverso la raccolta, la selezione e l’analisi delle principali testimonianze; dall’altro a indagarne le diverse forme e fisionomie assunte nel corso del tempo, nonché le modalità attraverso le quali fu somministrata la notitia librorum. A questo primo piano di indagine se ne è affiancato un secondo, per mezzo dell’elaborazione di due modelli descrittivi. Il primo è finalizzato alla raccolta delle principali generalità ed evidenze formali di una testata. Il secondo, invece, rappresenta un tentativo di spoglio e analisi approfondita dei contributi offerti da due campioni periodici presi come modelli di riferimento: La Galleria di Minerva, relativamente al biennio 1696-1697, e il Giornale della letteratura italiana (Mantova, 1793-1795). L’intento è quello di ricostruire, anche attraverso un processo di formulazione di keywords, le principali tematiche e i principali interessi emersi dalle esperienze menzionate. E mostrare, pertanto, il valore rappresentativo e identificativo del periodico bibliografico relativamente al contesto erudito di riferimento, nella sua veste di fonte informativa all’interno della quale si rispecchiarono le principali istanze scientifico-culturali del periodo.