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Model Takes (model + take)
Selected AbstractsDocuments and queries as random variables: History and implicationsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 9 2006David Bodoff The view of documents and/or queries as random variables is gaining importance in the theory of information retrieval. We argue that traditional probabilistic models consider documents and queries as random variables, but that newer models such as language modeling and our unified model take this one step further. The additional step is called error in predictors. Such models consider that we don't observe the document and query random variables that are modeled to predict relevance probabilistically. Rather, there are additional random variables, which are the observed documents and queries. We discuss some important implications of this idea for parameter estimation, relevance prediction, and even test-collection construction. By clarifying the positions of various probabilistic models on this question, and presenting in one place many of its implications, this article aims to deepen our common understanding of the theories behind traditional probabilistic models, and to strengthen the theoretical basis for further development of more recent approaches such as language modeling. [source] Friction effect on the characteristic performance of Diesel enginesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2002Lingen Chen Abstract An irreversible model for an air standard Diesel engine is presented in this paper. This model takes into account the finite-time evolution of the cycle's compression and power strokes and it considers global losses lumped in a friction-like term. The relations between the power output and the compression ratio, as well as between the thermal efficiency and the compression ratio are derived. The maximum power output with the corresponding efficiency, and the maximum efficiency with the corresponding power output are calculated versus compression ratio. Copyright © 2002 John Wiley & Sons, Ltd. [source] Aid, Relief, and Containment: The First Asylum Country and BeyondINTERNATIONAL MIGRATION, Issue 5 2002B.S. Chimni A fundamental problem that confronts the European Union today is how it can maintain its commitment to the institution of asylum while checking irregular migration and the abuse of its asylum system. In order to explore a response to this dilemma the paper addresses the following questions: what role can relief and aid policies play in influencing migration patterns? What should be the appropriate approach to the granting of relief and aid to developing countries of first asylum? Should it be viewed as a part of the larger problem of development or be treated as a distinct issue? What kind of a relief/aid model will help refugees return to post,conflict societies and stop the conflict from reproducing itself? The paper examines two different approaches to address these questions: the alliance,containment approach and the distributive,developmental approach. It also looks at some empirical evidence, which reveals that at present it is a conservative alliance,containment approach that informs EU relief and aid practices. This approach, however, does not help achieve the stated objective of checking abuse of asylum and migration procedures while sustaining a commitment to a liberal asylum regime. The paper goes on to identify the gaps in EU policy and the lessons that can be drawn. It concludes by looking at different policy alternatives and suggesting the adoption of a reformist distributive,developmental model. The implementation of this model holds out the hope of reverting to a more liberal asylum regime while controlling irregular migration and "bogus" asylum seekers, for the reformist distributive developmental model takes a more long,term view of migration trends and also seeks to address the growing North,South divide. [source] Mechanics of column beds: II.AICHE JOURNAL, Issue 3 2003Modeling of coupled stress-strain-flow behavior The rheological behavior of a bed of packing material during its consolidation was investigated using an elastic-plastic model, the Frictional Material Model. This model takes into account the behavior of the packing material under compression stress, its consolidation, its internal friction, its friction against the column wall, and the dependence of the bed's permeability on the local void fraction. The complexity of the problem arises from the nonlinear behavior of the relationships between the critical parameters controlling the column bed behavior and the external stresses applied to this bed. Solutions of the model were calculated for combinations of axial compression and seepage stresses, the latter corresponding to the flow of the mobile-phase stream under typical conditions used in HPLC. The results demonstrate the importance of the internal angle of friction of the packing material used on the degree of radial and axial heterogeneity of the beds of chromatographic columns packed with this material. [source] Mechanistic understanding of degradation in bioerodible polymers for drug deliveryAICHE JOURNAL, Issue 12 2002Domenico Larobina A new model was developed to understand the mechanism of erosion in bioerodible polymers, which is essential to accurately predict drug release and precisely design controlled release devices. This model takes into account the phenomenon of microphase separation observed for polyanhydrides of certain copolymer compositions, and assumes that erosion is dominated by degradation and, thus, in a system with a fast eroding and a slow eroding species, two rate constants,one for each species,essentially control the evolution of the polymer microstructure. Expressions were derived for the fraction of each monomer released, as well as for the porosity in the system. A partition coefficient accounts for thermodynamic partitioning of a drug into the microdomains. The solutions of the model equations were fitted to experimental data on monomer release kinetics from two polyanhydride systems to obtain the erosion rate constants. Drug release kinetics experiments are compared to the model solution for drug release, and the partition coefficient of the drug is obtained from the fits. The comparisons to the data are promising, while pointing out the limitations of the model. The model does not account for oligomer formation prior to monomer release or for the dependence of the rate constants on parameters such as the degree of crystallinity, the local pH, and the polymer molecular weight. [source] IMPACT ASSESSMENT MODEL FOR CLEAR WATER FISHES EXPOSED TO EXCESSIVELY CLOUDY WATER,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2003Charles P. Newcombe ABSTRACT: A new type of empirical model described here enables real time assessment of impacts caused by excessive water cloudiness as a function of (a) reduced visual clarity (excessive cloudiness) and (b) duration of exposure to cloudy conditions, in fisheries or fish life stages adapted to life in clear water ecosystems. This model takes the familiar form used in earlier suspended sediment dose effect models where z is severity of ill effect (SEV), x is duration of exposure (h), y is black disk sighting range (y BD, m),a measure of water clarity, a is the intercept, and b and c are slope coefficients. As calibrated in this study the model is Severity of ill effect is ranked on a 15-step scale that ranges from 0 to 14, where zero represents nil effect and 14 represents 100 percent mortality. This model, based on peer consultation and limited meta analysis of peer reviewed reports, accomplishes the following: (a) identifies the threshold of the onset of ill effects among clear water fishes; (b) postulates the rate at which serious ill effects are likely to escalate as a function of reduced visual clarity and persistence; (c) provides a context (the "visual clarity" matrix, with its cell coordinates) to share and compare information about impacts as a function of visual clarity "climate" (d) demonstrates changes in predator prey interactions at exposures greater than and less than the threshold of direct ill effects; (e) calibrates trout reactive distance (cm) as function of water clarity in the form where y represents reactive distance (cm) and x represents visual clarity (black disk sighting range, cm), and where a and b are intercept and slope respectively, such that (f) identifies black disk sighting range, in meters, and its reciprocal, beam attenuation, as preferred monitoring variables; and (g) provides two additional optical quality variables (Secchi disk extinction distance and turbidity) which, suitably calibrated as they have been in this study, expand the range of monitoring options in situations in which the preferred technology,beam attenuation equipment or black disk sighting equipment,is unavailable or impractical to use. This new model demonstrates the efficacy of peer collaboration and defines new research horizons for its refinement. [source] Modelling species diversity through species level hierarchical modellingJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 1 2005Alan E. Gelfand Summary., Understanding spatial patterns of species diversity and the distributions of individ-ual species is a consuming problem in biogeography and conservation. The Cape floristic region of South Africa is a global hot spot of diversity and endemism, and the Protea atlas project, with about 60 000 site records across the region, provides an extraordinarily rich data set to model patterns of biodiversity. Model development is focused spatially at the scale of 1, grid cells (about 37 000 cells total for the region). We report on results for 23 species of a flowering plant family known as Proteaceae (of about 330 in the Cape floristic region) for a defined subregion. Using a Bayesian framework, we developed a two-stage, spatially explicit, hierarchical logistic regression. Stage 1 models the potential probability of presence or absence for each species at each cell, given species attributes, grid cell (site level) environmental data with species level coefficients, and a spatial random effect. The second level of the hierarchy models the probability of observing each species in each cell given that it is present. Because the atlas data are not evenly distributed across the landscape, grid cells contain variable numbers of sampling localities. Thus this model takes the sampling intensity at each site into account by assuming that the total number of times that a particular species was observed within a site follows a binomial distribution. After assigning prior distributions to all quantities in the model, samples from the posterior distribution were obtained via Markov chain Monte Carlo methods. Results are mapped as the model-estimated probability of presence for each species across the domain. This provides an alternative to customary empirical ,range-of-occupancy' displays. Summing yields the predicted richness of species over the region. Summaries of the posterior for each environmental coefficient show which variables are most important in explaining the presence of species. Our initial results describe biogeographical patterns over the modelled region remarkably well. In particular, species local population size and mode of dispersal contribute significantly to predicting patterns, along with annual precipitation, the coefficient of variation in rainfall and elevation. [source] Simplified heat exchange model for semiconductor laser diodes thermal parameters extractionLASER PHYSICS LETTERS, Issue 11 2005P. S. André Abstract By investigating the heat flow mechanism in a semiconductor laser diode, we demonstrate a comprehensive technique for optical device thermal parameters extraction to be used in the prediction of the laser performance This accurate and precise heat exchange model takes into account the relevant heat exchange mechanism and mechanical considerations of the laser diode mounting. We measured the thermal response of a semiconductor laser diode attach to a substrate, deriving from those the device thermal parameters such as heat capacity and thermal conductance for the device and subtract. From the estimated values a prediction of the real laser temperature response is obtained directly from the measurements realized in the substrate. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] A supply chain design model with unreliable supplyNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 8 2007Lian Qi Abstract Uncertainties abound within a supply chain and have big impacts on its performance. We propose an integrated model for a three-tiered supply chain network with one supplier, one or more facilities and retailers. This model takes into consideration the unreliable aspects of a supply chain. The properties of the optimal solution to the model are analyzed to reveal the impacts of supply uncertainty on supply chain design decisions. We also propose a general solution algorithm for this model. Computational experience is presented and discussed. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 [source] AN ANALYSIS OF DURATION ON THE DISABILITY SUPPORT PENSION PROGRAM,AUSTRALIAN ECONOMIC PAPERS, Issue 2 2006LIXIN CAI The paper examines the factors that determine the duration on the Disability Support Pension (DSP) program using administrative data. We estimate two models based on two competing assumptions: the first model takes the standard assumption in duration models that all recipients will eventually leave the program. The second one takes into account the possibility that there may be some recipients who will never recover from their disabilities and hence not leave the program. Both models indicate that female recipients, recipients who enter DSP at a very young or very old age, recipients with a partner on income support, and recipients who transfer from unemployment benefits have the potential of a longer DSP duration. [source] INTENTION, AUTONOMY, AND BRAIN EVENTSBIOETHICS, Issue 6 2009GRANT GILLETT ABSTRACT Informed consent is the practical expression of the doctrine of autonomy. But the very idea of autonomy and conscious free choice is undercut by the view that human beings react as their unconscious brain centres dictate, depending on factors that may or may not be under rational control and reflection. This worry is, however, based on a faulty model of human autonomy and consciousness and needs close neurophilosophical scrutiny. A critique of the ethics implied by the model takes us towards a ,care of the self' view of autonomy and the subject's attunement to the truth as the crux of reasoning rather than the inner mental/neural state views of autonomy and human choice on offer at present. [source] Combining Information from Cancer Registry and Medical Records Data to Improve Analyses of Adjuvant Cancer TherapiesBIOMETRICS, Issue 3 2009Yulei He Summary Cancer registry records contain valuable data on provision of adjuvant therapies for cancer patients. Previous studies, however, have shown that these therapies are underreported in registry systems. Hence direct use of the registry data may lead to invalid analysis results. We propose first to impute correct treatment status, borrowing information from an additional source such as medical records data collected in a validation sample, and then to analyze the multiply imputed data, as in Yucel and Zaslavsky (2005,,Journal of the American Statistical Association,100, 1123,1132). We extend their models to multiple therapies using multivariate probit models with random effects. Our model takes into account the associations among different therapies in both administration and probability of reporting, as well as the multilevel structure (patients clustered within hospitals) of registry data. We use Gibbs sampling to estimate model parameters and impute treatment status. The proposed methodology is applied to the data from the Quality of Cancer Care project, in which stage II or III colorectal cancer patients were eligible to receive adjuvant chemotherapy and radiation therapy. [source] Reflections on the Challenges of Effective Dissemination of Behavioural Family Intervention: Our Experience with the Triple P , Positive Parenting ProgramCHILD AND ADOLESCENT MENTAL HEALTH, Issue 4 2005Matthew R. Sanders This paper draws on learnings from dissemination and diffusion research to discuss predictors of dissemination outcomes, obstacles to effective dissemination, and phases of dissemination failure. A model is presented of effective dissemination of a multilevel system of intervention known as the Triple P-Positive Parenting Program (Triple P). This model takes a systems-contextual approach, addressing program design, skills training, practitioner confidence and self-regulation, and workplace support. Recommendations are made for agencies adopting evidence-based programs, particularly in relation to the selection, establishment and maintenance of new programs as well as guiding ongoing program development. Future directions for research into the dissemination of evidence-based practice are also discussed. [source] | ||||||||||||||||