754 resultados para Mathematical problem solving


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Es una traducci??n al espa??ol de la publicaci??n original de la OCDE "PISA 2012 Assessment and Analytical Framework Mathematics, Reading, Science, Problem Solving and Financial Literacy "

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En problemes d'assignació de recursos, normalment s'han de tenir en compte les incerteses que poden provocar canvis en les dades inicials. Aquests canvis dificulten l'aplicabilitat de les planificacions que s'hagin fet inicialment. Aquesta tesi se centra en l'elaboració de tècniques que consideren la incertesa alhora de cercar solucions robustes, és a dir solucions que puguin continuar essent vàlides encara que hi hagi canvis en l'entorn. Particularment, introduïm el concepte de robustesa basat en reparabilitat, on una solució robusta és una que pot ser reparada fàcilment en cas que hi hagi incidències. La nostra aproximació es basa en lògica proposicional, codificant el problema en una fórmula de satisfactibilitat Booleana, i aplicant tècniques de reformulació per a la generació de solucions robustes. També presentem un mecanisme per a incorporar flexibilitat a les solucions robustes, de manera que es pugui establir fàcilment el grau desitjat entre robustesa i optimalitat de les solucions.

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La implantació de Sistemes de Suport a la presa de Decisions (SSD) en Estacions Depuradores d'Aigües Residuals Urbanes (EDAR) facilita l'aplicació de tècniques més eficients basades en el coneixement per a la gestió del procés, assegurant la qualitat de l'aigua de sortida tot minimitzant el cost ambiental de la seva explotació. Els sistemes basats en el coneixement es caracteritzen per la seva capacitat de treballar amb dominis molt poc estructurats, i gran part de la informació rellevant de tipus qualitatiu i/o incerta. Precisament aquests són els trets característics que es poden trobar en els sistemes biològics de depuració, i en conseqüència en una EDAR. No obstant, l'elevada complexitat dels SSD fa molt costós el seu disseny, desenvolupament i aplicació en planta real, pel que resulta determinant la generació d'un protocol que faciliti la seva exportació a EDARs de tecnologia similar. L'objectiu del present treball de Tesi és precisament el desenvolupament d'un protocol que faciliti l'exportació sistemàtica de SSD i l'aprofitament del coneixement del procés prèviament adquirit. El treball es desenvolupa en base al cas d'estudi resultant de l'exportació a l'EDAR Montornès del prototipus original de SSD implementat a l'EDAR Granollers. Aquest SSD integra dos tipus de sistemes basats en el coneixement, concretament els sistemes basats en regles (els quals són programes informàtics que emulen el raonament humà i la seva capacitat de solucionar problemes utilitzant les mateixes fonts d'informació) i els sistemes de raonament basats en casos (els quals són programes informàtics basats en el coneixement que volen solucionar les situacions anormals que pateix la planta en el moment actual mitjançant el record de l'acció efectuada en una situació passada similar). El treball està estructurat en diferents capítols, en el primer dels quals, el lector s'introdueix en el món dels sistemes de suport a la decisió i en el domini de la depuració d'aigües. Seguidament es fixen els objectius i es descriuen els materials i mètodes utilitzats. A continuació es presenta el prototipus de SSD desenvolupat per la EDAR Granollers. Una vegada el prototipus ha estat presentat es descriu el primer protocol plantejat pel mateix autor de la Tesi en el seu Treball de Recerca. A continuació es presenten els resultats obtinguts en l'aplicació pràctica del protocol per generar un nou SSD, per una planta depuradora diferent, partint del prototipus. L'aplicació pràctica del protocol permet l'evolució del mateix cap a un millor pla d'exportació. Finalment, es pot concloure que el nou protocol redueix el temps necessari per realitzar el procés d'exportació, tot i que el nombre de passos necessaris ha augmentat, la qual cosa significa que el nou protocol és més sistemàtic.

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This literature review examines the use of private speech among typically developing and hearing impaired children. This paper supports the view that private speech provides a self-regulatory function and guides behavior and problem-solving.

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Children may be at higher risk than adults from pesticide exposure, due to their rapidly developing physiology, unique behavioral patterns, and interactions with the physical environment. This preliminary study conducted in Ecuador examines the association between household and environmental risk factors for pesticide exposure and neurobehavioral development. We collected data over 6 months in the rural highland region of Cayambe, Ecuador (2003–2004). Children age 24–61 months residing in 3 communities were assessed with the Ages and Stages Questionnaire and the Visual Motor Integration Test. We gathered information on maternal health and work characteristics, the home and community environment, and child characteristics. Growth measurements and a hemoglobin finger-prick blood test were obtained. Multiple linear regression analyses were conducted. Current maternal employment in the flower industry was associated with better developmental scores. Longer hours playing outdoors were associated with lower gross and fine motor and problem solving skills. Children who played with irrigation water scored lower on fine motor skills (8% decrease; 95% confidence interval 9.31 to 0.53), problem-solving skills (7% decrease; 8.40 to 0.39), and Visual Motor Integration test scores (3% decrease; 12.00 to 1.08). These results suggest that certain environmental risk factors for exposure to pesticides may affect child development, with contact with irrigation water of particular concern. However, the relationships between these risk factors and social characteristics are complex, as corporate agriculture may increase risk through pesticide exposure and environmental contamination, while indirectly promoting healthy development by providing health care, relatively higher salaries, and daycare options.

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To identify and describe the sociodemographic and nutritional characteristics associated with neurobehavioral development among young children living in three communities in the northeastern Andean region of Cayambe-Tabacundo, Ecuador. Women in the study communities who had a child 3 to 61 months of age completed a questionnaire about maternal and child health and sociodemographic characteristics. The Ages and Stages Questionnaire (ASQ) was directly administered to 283 children by two trained interviewers. Growth measurements and a hemoglobin finger-prick blood test were obtained in 2003–2004. Prevalence of developmental delay was calculated, and associations between child development and maternal, child, and household characteristics were explored. High frequencies of developmental delay were observed. Children 3 to 23 months old displayed delay in gross motor skills (30.1%), and children 48 to 61 months old displayed delay in problem-solving skills (73.4%) and fine motor skills (28.1%). A high frequency of both anemia (60.4%) and stunting (53.4%) was observed for all age groups. Maternal educational level was positively associated with communication and problem-solving skills, and monthly household income was positively associated with communication, gross motor, and problem-solving skills. The results suggest a high prevalence of developmental delay and poor child health in this population. Child health status and the child’s environment may contribute to developmental delay in this region of Ecuador, but sociodemographic factors affecting opportunities for stimulation may also play a role. Research is needed to identify what is causing high percentages of neurobehavioral developmental delay in this region of Ecuador.

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A generic Nutrient Export Risk Matrix (NERM) approach is presented. This provides advice to farmers and policy makers on good practice for reducing nutrient loss and is intended to persuade them to implement such measures. Combined with a range of nutrient transport modelling tools and field experiments, NERMs can play an important role in reducing nutrient export from agricultural land. The Phosphorus Export Risk Matrix (PERM) is presented as an example NERM. The PERM integrates hydrological understanding of runoff with a number of agronomic and policy factors into a clear problem-solving framework. This allows farmers and policy makers to visualise strategies for reducing phosphorus loss through proactive land management. The risk Of Pollution is assessed by a series of informed questions relating to farming intensity and practice. This information is combined with the concept of runoff management to point towards simple, practical remedial strategies which do not compromise farmers' ability to obtain sound economic returns from their crop and livestock.

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The experiments examine the influence of metacognitive experience on the transfer of logical processes in a problem solving setting. Subjects were presented with two versions of Wason's (1966) selection task. Although they were able to perform successfully on the concrete tasks (following a minimal explanation of the correct solution on an initial trial), the majority were not able to transfer a successful method to the abstract tasks. Verbalization during, or following, the concrete tasks produced substantial transfer effects however. It is suggested that verbalization may lead to an increased awareness of past behaviour, particularly of those aspects necessary for successful solution.

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The concept of “working” memory is traceable back to nineteenth century theorists (Baldwin, 1894; James 1890) but the term itself was not used until the mid-twentieth century (Miller, Galanter & Pribram, 1960). A variety of different explanatory constructs have since evolved which all make use of the working memory label (Miyake & Shah, 1999). This history is briefly reviewed and alternative formulations of working memory (as language-processor, executive attention, and global workspace) are considered as potential mechanisms for cognitive change within and between individuals and between species. A means, derived from the literature on human problem-solving (Newell & Simon, 1972), of tracing memory and computational demands across a single task is described and applied to two specific examples of tool-use by chimpanzees and early hominids. The examples show how specific proposals for necessary and/or sufficient computational and memory requirements can be more rigorously assessed on a task by task basis. General difficulties in connecting cognitive theories (arising from the observed capabilities of individuals deprived of material support) with archaeological data (primarily remnants of material culture) are discussed.

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The disuse hypothesis of cognitive aging attributes decrements in fluid intelligence in older adults to reduced cognitively stimulating activity. This study experimentally tested the hypothesis that a period of increased mentally stimulating activities thus would enhance older adults' fluid intelligence performance. Participants (N = 44, mean age 67.82) were administered pre- and post-test measures, including the fluid intelligence measure, Cattell's Culture Fair (CCF) test. Experimental participants engaged in diverse, novel, mentally stimulating activities for 10-12 weeks and were compared to a control condition. Results supported the hypothesis; the experimental group showed greater pre- to post-CCF gain than did controls (effect size d = 0.56), with a similar gain on a spatial-perceptual task (WAIS-R Blocks). Even brief periods of increased cognitive stimulation can improve older adults' problem solving and flexible thinking.

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Williams syndrome (WS) is characterized by apparent relative strengths in language, facial processing and social cognition but by profound impairment in spatial cognition, planning and problem solving. Following recent research which suggests that individuals with WS may be less linguistically able than was once thought, in this paper we begin to investigate why and how they may give the impression of linguistic proficiency despite poor standardized test results. This case study of Brendan, a 12-year-old boy with WS, who presents with a considerable lack of linguistic ability, suggests that impressions of linguistic competence may to some extent be the result of conversational strategies which enable him to compensate for various cognitive and linguistic deficits with a considerable degree of success. These conversational strengths are not predicted by his standardized language test results, and provide compelling support for the use of approaches such as Conversation Analysis in the assessment of individuals with communication impairments.

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We consider the Stokes conjecture concerning the shape of extreme two-dimensional water waves. By new geometric methods including a nonlinear frequency formula, we prove the Stokes conjecture in the original variables. Our results do not rely on structural assumptions needed in previous results such as isolated singularities, symmetry and monotonicity. Part of our results extends to the mathematical problem in higher dimensions.

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In his book Democratic Authority, David Estlund puts forward a case for democracy, which he labels epistemic proceduralism, that relies on democracy's ability to produce good – that is, substantively just – results. Alongside this case for democracy Estlund attacks what he labels ‘utopophobia’, an aversion to idealistic political theory. In this article I make two points. The first is a general point about what the correct level of ‘idealisation’ is in political theory. Various debates are emerging on this question and, to the extent that they are focused on ‘political theory’ as a whole, I argue, they are flawed. This is because there are different kinds of political concept, and they require different kinds of ideal. My second point is about democracy in particular. If we understand democracy as Estlund does, then we should see it as a problem-solving concept – the problem being that we need coercive institutions and rules, but we do not know what justice requires. As democracy is a response to a problem, we should not allow our theories of it, even at the ideal level, to be too idealised – they must be embedded in the nature of the problem they are to solve, and the beings that have it.