20,235 research outputs found

    New directions for Artificial Intelligence (AI) methods in optimum design

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    Developments and applications of artificial intelligence (AI) methods in the design of structural systems is reviewed. Principal shortcomings in the current approach are emphasized, and the need for some degree of formalism in the development environment for such design tools is underscored. Emphasis is placed on efforts to integrate algorithmic computations in expert systems

    The Missing Link between Morphemic Assemblies and Behavioral Responses:a Bayesian Information-Theoretical model of lexical processing

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    We present the Bayesian Information-Theoretical (BIT) model of lexical processing: A mathematical model illustrating a novel approach to the modelling of language processes. The model shows how a neurophysiological theory of lexical processing relying on Hebbian association and neural assemblies can directly account for a variety of effects previously observed in behavioural experiments. We develop two information-theoretical measures of the distribution of usages of a morpheme or word, and use them to predict responses in three visual lexical decision datasets investigating inflectional morphology and polysemy. Our model offers a neurophysiological basis for the effects of morpho-semantic neighbourhoods. These results demonstrate how distributed patterns of activation naturally result in the arisal of symbolic structures. We conclude by arguing that the modelling framework exemplified here, is a powerful tool for integrating behavioural and neurophysiological results

    A Statistical Model of Abstention under Compulsory Voting

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    Invalid voting and electoral absenteeism are two important sources of abstention in compulsory voting systems. Previous studies in this area have not considered the correlation between both variables and ignored the compositional nature of the data, potentially leading to unfeasible results and discarding helpful information from an inferential standpoint. In order to overcome these problems, this paper develops a statistical model that accounts for the compositional and hierarchical structure of the data and addresses robustness concerns raised by the use of small samples that are typical in the literature. The model is applied to analyze invalid voting and electoral absenteeism in Brazilian legislative elections between 1945 and 2006 via MCMC simulations. The results show considerable differences in the determinants of both forms of non-voting; while invalid voting was strongly positively related both to political protest and to the existence of important informational barriers to voting, the influence of these variables on absenteeism is less evident. Comparisons based on posterior simulations indicate that the model developed in this paper fits the dataset better than several alternative modeling approaches and leads to different substantive conclusions regarding the effect of different predictors on the both sources of abstention

    Vaccine coverage and determinants of incomplete vaccination in children aged 12-23 months in dschang, west region, cameroon: a cross-sectional survey during a polio outbreak

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    Inadequate immunization coverage with increased risk of vaccine preventable diseases outbreaksremains a problem in Africa. Moreover, different factors contribute to incomplete vaccination status. This study wasperformed in Dschang (West Region, Cameroon), during the polio outbreak occurred in October 2013, in order toestimate the immunization coverage among children aged 12–23 months, to identify determinants for incompletevaccination status and to assess the risk of poliovirus spread in the study population.Methods:A cross-sectional household survey was conducted in November-December 2013, using the WHOtwo-stage sampling design. An interviewer-administered questionnaire was used to obtain information fromconsenting parents of children aged 12–23 months. Vaccination coverage was assessed by vaccination card andparents’recall. Chi-square test and multilevel logistic regression model were used to identify the determinants ofincomplete immunization status. Statistical significance was set atp90 %, and 73.4 % children completedthe recommended vaccinations before 1-year of age. In the final multilevel logistic regression model, factorssignificantly associated with incomplete immunization status were: retention of immunization card (AOR: 7.89;95 % CI: 1.08–57.37), lower mothers’utilization of antenatal care (ANC) services (AOR:1.25; 95 % CI: 1.07–63.75),being the≥3rdborn child in the family (AOR: 425.4; 95 % CI: 9.6–18,808), younger mothers’age (AOR: 49.55;95 % CI: 1.59–1544), parents’negative attitude towards immunization (AOR: 20.2; 95 % CI: 1.46–278.9), and poorerparents’exposure to information on vaccination (AOR: 28.07; 95 % CI: 2.26–348.1). Longer distance from the vaccinationcenters was marginally significant (p=0.05).Conclusion:Vaccination coverage was high; however, 1 out of 7 children was partially vaccinated, and 1 out of 4 didnot complete timely the recommended vaccinations. In order to improve the immunization coverage, it is necessary tostrengthen ANC services, and to improve parents’information and attitude towards immunization, targeting youngerparents and families living far away from vaccination centers, using appropriate communication strategies. Finally, theestimated OPV-3 coverage is reassuring in relation to the ongoing polio outbrea
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