509 research outputs found

    Conservation Laws in Cellular Automata

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    If X is a discrete abelian group and B a finite set, then a cellular automaton (CA) is a continuous map F:B^X-->B^X that commutes with all X-shifts. If g is a real-valued function on B, then, for any b in B^X, we define G(b) to be the sum over all x in X of g(b_x) (if finite). We say g is `conserved' by F if G is constant under the action of F. We characterize such `conservation laws' in several ways, deriving both theoretical consequences and practical tests, and provide a method for constructing all one-dimensional CA exhibiting a given conservation law.Comment: 19 pages, LaTeX 2E with one (1) Encapsulated PostScript figure. To appear in Nonlinearity. (v2) minor changes/corrections; new references added to bibliograph

    Control of wind-wave power on morphological shape of salt marsh margins

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    Salt marshes are among the most common morphological features found in tidal landscapes and provide ecosystem services of primary ecological and economic importance. However, the continued rise in relative sea level and increasing anthropogenic pressures threaten the sustainability of these environments. The alarmingly high rates of salt marsh loss observed worldwide, mainly dictated by the lateral erosion of their margins, call for new insights into the mutual feedbacks among physical, biological, and morphological processes that take place at the critical interface between salt marshes and the adjoining tidal flats. We combined field measurements, remote sensing data, and numerical modeling to investigate the interplays between wind waves and the morphology, ecology, and planform evolution of salt marsh margins in the Venice Lagoon of Italy. Our results confirm the existence of a positive linear relationship between incoming wave power density and rates of salt marsh lateral retreat. In addition, we show that lateral erosion significantly decreases when halophytic vegetation colonizes the marsh margins, and that different erosion rates in vegetated margins are associated with different halophytes. High marsh cliffs and smooth shorelines are expected along rapidly eroding margins, whereas erosion rates are reduced in gently sloped, irregular edges facing shallow tidal flats that are typically exposed to low wind-energy conditions. By highlighting the relationships between the dynamics and functional forms of salt marsh margins, our results represent a critical step to address issues related to conservation and restoration of salt marsh ecosystems, especially in the face of changing environmental forcings

    Fetal development and blood hematological-biochemical parameters in Campeiro and Pantaneiro foals.

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    Made available in DSpace on 2019-01-02T23:37:38Z (GMT). No. of bitstreams: 1 2018Vieiraetal..pdf: 293128 bytes, checksum: 55472a23573b40b9efd496c73b492ee6 (MD5) Previous issue date: 2019-01-02bitstream/item/189575/1/2018-Vieira-et-al.-.pd

    Remote sensing for optimal estimation of water temperature dynamics in shallow tidal environments

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    Given the increasing anthropogenic pressures on lagoons, estuaries, and lakes and considering the highly dynamic behavior of these systems, methods for the continuous and spatially distributed retrieval of water quality are becoming vital for their correct monitoring and management. Water temperature is certainly one of the most important drivers that influence the overall state of coastal systems. Traditionally, lake, estuarine, and lagoon temperatures are observed through point measurements carried out during field campaigns or through a network of sensors. However, sporadic measuring campaigns or probe networks rarely attain a density sufficient for process understanding, model development/validation, or integrated assessment. Here, we develop and apply an integrated approach for water temperature monitoring in a shallow lagoon which incorporates satellite and in-situ data into a mathematical model. Specifically, we use remote sensing information to constrain large-scale patterns of water temperature and high-frequency in situ observations to provide proper time constraints. A coupled hydrodynamic circulation-heat transport model is then used to propagate the state of the system forward in time between subsequent remote sensing observations. Exploiting the satellite data high spatial resolution and the in situ measurements high temporal resolution, the model may act a physical interpolator filling the gap intrinsically characterizing the two monitoring techniques

    Risk factors associated with calcinosis of juvenile dermatomyositis

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    OBJETIVO: Identificar fatores de risco associados à calcinose em crianças e adolescentes com dermatomiosite juvenil. MÉTODOS: Prontuários de 54 pacientes com dermatomiosite juvenil foram estudados. Foram avaliados dados demográficos; características clínicas: grau de força muscular (I a V do Medical Research Council), presença de comprometimentos pulmonar (distúrbio ventilatório restritivo com presença ou ausência do anticorpo anti-Jo-1), gastrointestinal (refluxo gastroesofágico) e cardíaco (pericardite e/ou miocardite); exames laboratoriais: elevação de enzimas musculares (creatinoquinase, aspartato aminotransferase, alanina aminotransferase e desidrogenase lática) e terapias utilizadas: corticoterapia isolada ou associada à cloroquina e/ou imunossupressor. Os pacientes foram divididos em dois grupos de acordo com a presença ou ausência de calcinose e foram avaliados através de análise univariada e multivariada. RESULTADOS: Calcinose foi evidenciada em 23 (43%) pacientes, sendo em seis (26%) antes do diagnóstico e em 17 (74%) após. A análise univariada revelou que comprometimentos cardíaco (p = 0,01) e pulmonar (p = 0,02) e necessidade da utilização de um ou mais imunossupressores (metotrexato, ciclosporina A e/ou pulsoterapia com ciclofosfamida endovenosa) no tratamento da dermatomiosite juvenil (p = 0,03) foram associados com uma maior incidência de calcinose. A análise multivariada mostrou que comprometimento cardíaco (OR = 15,56; IC95% 1,59-152,2) e uso de um ou mais imunossupressores (OR = 4,01; IC95% 1,08-14,87) foram as únicas variáveis independentes associadas à presença de calcinose. CONCLUSÕES: O aparecimento da calcinose foi freqüente na dermatomiosite juvenil, habitualmente na evolução da doença. A calcinose foi associada aos casos mais graves, que apresentaram envolvimento cardíaco e necessitaram da utilização de imunossupressores no seu tratamento.OBJECTIVE: To identify risk factors associated with calcinosis in children and adolescents with juvenile dermatomyositis. METHODS: A review was carried out of the medical records of 54 patients with juvenile dermatomyositis. Data were collected on demographic characteristics, clinical features: muscle strength (stages I to V of the Medical Research Council scale), pulmonary involvement (restrictive pulmonary disease with presence or absence of anti-Jo1 antibodies), gastrointestinal problems (gastroesophageal reflux) and/or heart disease (pericarditis and/or myocarditis); laboratory tests: elevated muscle enzyme levels in serum (creatine phosphokinase, aspartate aminotransferase, alanine aminotransferase and/or lactate dehydrogenase); and on the treatments given: corticoid therapy in isolation or associated with hydroxychloroquine and/or immunosuppressants. The patients were divided into two groups, depending on presence or absence of calcinosis and data were evaluated by both univariate and multivariate analyses. RESULTS: Calcinosis was identified in 23 (43%) patients, and in six (26%) patients it had emerged prior to diagnosis while in 17 (74%) it was post diagnosis. The univariate analysis revealed that cardiac (p = 0.01) and pulmonary (p = 0.02) involvement and the need for one or more immunosuppressor (methotrexate, cyclosporine A and/or pulse therapy with intravenous cyclophosphamide) to treat juvenile dermatomyositis (p = 0.03) were all associated with an increased incidence of calcinosis. The multivariate analysis then demonstrated that only cardiac involvement (OR = 15.56; 95%CI 1.59-152.2) and the use of one or more immunosuppressor (OR = 4.01; 95%CI 1.08-14.87) were independently associated with the presence of calcinosis. CONCLUSIONS: Calcinosis was a frequent development among these juvenile dermatomyositis cases, generally emerging as the disease progressed. Calcinosis was associated with the more severe cases that also had cardiac involvement and where immunosuppressors had to be included in the treatment

    Divergent mathematical treatments in utility theory

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    In this paper I study how divergent mathematical treatments affect mathematical modelling, with a special focus on utility theory. In particular I examine recent work on the ranking of information states and the discounting of future utilities, in order to show how, by replacing the standard analytical treatment of the models involved with one based on the framework of Nonstandard Analysis, diametrically opposite results are obtained. In both cases, the choice between the standard and nonstandard treatment amounts to a selection of set-theoretical parameters that cannot be made on purely empirical grounds. The analysis of this phenomenon gives rise to a simple logical account of the relativity of impossibility theorems in economic theory, which concludes the paper
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