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Search Results: 1 - 10 of 20263 matches for " Pierre Augusto "
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Density of bounded maps in Sobolev spaces into complete manifolds
Pierre Bousquet,Augusto Ponce,Jean Van Schaftingen
Mathematics , 2015,
Abstract: Given a complete noncompact Riemannian manifold $N^n$, we study the density of the set of bounded Sobolev maps on the cube $(W^{1, p} \cap L^\infty) (Q^m; N^n)$ in the Sobolev space $W^{1, p} (Q^m; N^n)$ for $1 \le p \le m$. The density always holds when $p$ is not integer. When $p$ is an integer, the density can fail, and we prove that a quantitative levelling property is equivalent with the density. This new condition is ensured by a uniform Lipschitz geometry or by bounds on the injectivity radius and on the curvature. As a byproduct, we give necessary and sufficent conditions for the density of the set of smooth maps $C^\infty (\bar{Q^m}; N^n)$ in the space $W^{1, p} (Q^m; N^n)$.
Strong density for higher order Sobolev spaces into compact manifolds
Pierre Bousquet,Augusto Ponce,Jean Van Schaftingen
Mathematics , 2012, DOI: 10.4171/JEMS/518
Abstract: Given a compact manifold $N^n$, an integer $k \in \mathbb{N}_*$ and an exponent $1 \le p < \infty$, we prove that the class $C^\infty(\overline{Q}^m; N^n)$ of smooth maps on the cube with values into $N^n$ is dense with respect to the strong topology in the Sobolev space $W^{k, p}(Q^m; N^n)$ when the homotopy group $\pi_{\lfloor kp \rfloor}(N^n)$ of order $\lfloor kp \rfloor$ is trivial. We also prove the density of maps that are smooth except for a set of dimension $m - \lfloor kp \rfloor - 1$, without any restriction on the homotopy group of $N^n$
Density of smooth maps for fractional Sobolev spaces $W^{s, p}$ into $\ell$ simply connected manifolds when $s \ge 1$
Pierre Bousquet,Augusto C. Ponce,Jean Van Schaftingen
Mathematics , 2012,
Abstract: Given a compact manifold $N^n \subset \mathbb{R}^\nu$, $s \ge 1$ and $1 \le p < \infty$, we prove that the class of smooth maps on the cube with values into $N^n$ is strongly dense in the fractional Sobolev space $W^{s, p}(Q^m; N^n)$ when $N^n$ is $\lfloor sp \rfloor$ simply connected. For $sp$ integer, we prove weak density of smooth maps with values into $N^n$ when $N^n$ is $sp - 1$ simply connected. The proofs are based on the existence of a retraction of $\mathbb{R}^\nu$ onto $N^n$ except for a small subset of $N^n$ and on a pointwise estimate of fractional derivatives of composition of maps in $W^{s, p} \cap W^{1, sp}$.
Strong approximation of fractional Sobolev maps
Pierre Bousquet,Augusto C. Ponce,Jean Van Schaftingen
Mathematics , 2013, DOI: 10.1007/s11784-014-0172-5
Abstract: Brezis and Mironescu have announced several years ago that for a compact manifold $N^n \subset \mathbb{R}^\nu$ and for real numbers $0 < s < 1$ and $1 \le p < \infty$ the class $C^\infty(\overline{Q}^m; N^n)$ of smooth maps on the cube with values into $N^n$ is dense with respect to the strong topology in the Sobolev space $W^{s, p}(Q^m; N^n)$ when the homotopy group $\pi_{\lfloor sp \rfloor}(N^n)$ of order $\lfloor sp \rfloor$ is trivial. The proof of this beautiful result is long and rather involved. Under the additional assumption that $N^n$ is $\lfloor sp \rfloor$ simply connected, we give a shorter proof of their result. Our proof for $sp \ge 1$ is based on the existence of a retraction of $\mathbb{R}^\nu$ onto $N^n$ except for a small subset in the complement of $N^n$ and on the Gagliardo-Nirenberg interpolation inequality for maps in $W^{1, q} \cap L^\infty$. In contrast, the case $sp < 1$ relies on the density of step functions on cubes in $W^{s, p}$.
Asma e rinite alérgica como express?o de uma única doen?a: um paradigma em constru??o
Camargos, Paulo Augusto Moreira;Rodrigues, Mary Elisabeth Santos Moura;Solé, Dirceu;Scheinmann, Pierre;
Jornal de Pediatria , 2002, DOI: 10.1590/S0021-75572002000800003
Abstract: objective: to describe current ideas about the relation between upper and lower respiratory tract and to review the epidemiological, immunological, and pathological aspects that support the paradigm of united airways disease. sources: literature review using the medline, md consult, highwire, medscape and lilacs databases. we used allergic rhinitis and asthma as keywords, and searched articles published in the past 20 years. summary of the findings: epidemiological evidence includes prevalence of allergic rhinitis in asthmatic patients and vice-versa, results of cross-sectional studies, bronchial hyperresponsiveness in patients with allergic rhinitis, importance of genetic and environmental factors, and the age of onset of atopic disease. morphological and physiological aspects show structural differences between the nasal and bronchial mucosa, and the mechanisms that could explain the effect of rhinitis on asthma. immunological aspects including the participation of bone marrow in the production of inflammatory cells and allergic reactions after allergen challenge are the same in allergic rhinitis and asthma. finally, the results of the therapy for allergic rhinitis in bronchial hyperresponsiveness and in clinical and functional control of asthma are also reported. conclusions: epidemiological evidence and immunological and pathological aspects suggest that there is a relation between allergic rhinitis and asthma. the paradigm of united airways disease suggests the implementation of an integrated therapeutic approach.
Pyroelectric composite film for X-ray intensity detection
Sakamoto, Walter Katsumi;Estevam, Giuliano Pierre;Carvalho, Aparecido Augusto de;Pontes, Wesley;Paula, Mauro Henrique de;
Materials Research , 2012, DOI: 10.1590/S1516-14392012005000030
Abstract: composite material obtained with modified lead titanate (pz34) ferroelectric ceramic and polyether-ether-ketone (peek) polymer matrix was used as sensitive component to measure x-ray intensity in a novel detection system. the sensing element works as a thermal transducer, converting a non-quantified thermal flux into an output measurable quantity of electrical voltage. the samples were obtained up to 60 vol.% of ceramic, by hot pressing the mixture of pz34 and peek powders at 368 °c and applying 12 mpa pressure for 2.0 hours. the sensor response varies from 2.70 to 0.80 v in the energy fluence rate range of 6.30 to 37.20 w.m-2. the absorbed incident energy was analyzed as a function of the ionizing energy. furthermore, by measuring the pyroelectric activity of the composite film it was observed that there is no degradation of the sensor after the irradiation.
Concentra??es plasmáticas de paroxetina em pacientes adultos e idosos com depress?o
Lima, Carlos Augusto de Mendon?a;Baumann, Pierre;Eap, Chin Bin;
Revista de Psiquiatria do Rio Grande do Sul , 2008, DOI: 10.1590/S0101-81082008000100006
Abstract: introduction: the effect of aging on steady-state plasma concentrations of paroxetine was investigated in 136 depressive patients treated with paroxetine 10-120 mg/day. methods: the patients were divided into three groups: aged up to 64 years (mean age ± standard deviation: 41.7±12.6 years; n = 44), between 65 and 79 years (72.8±4.7 years; n = 64), and 80 years or older (82.8±3.3 years; n = 28). paroxetine doses were normalized to 20 mg/day. blood samples were collected under steady-state conditions. paroxetine plasma levels were measured by gas chromatography/mass spectrometry. hepatic and renal functions were measured by standardized clinical laboratory tests. results: a large interindividual variability of paroxetine plasma levels (37-fold) was measured for a given dose. the mean plasma levels of paroxetine corrected for a 20 mg daily dose were 87% higher in the very elderly (≥ 80 years) patients (56.4±64.1 ng/ml; p < 0.05) and 57% higher in the elderly (65-79 years) patients (46.7±33.4 ng/ml; p < 0.001) when compared to the adult patients (< 64 years) (29.9±11.9ng/ml). age correlated significantly with paroxetine plasma levels (r = 0.21, p < 0.05). conclusion: recommended dose reduction of paroxetine in elderly patients seems therefore justified.
Elton Pereira,Darlan de Sousa Santos Junior,álvaro Dutra de Souza,Pierre Augusto
Perspectivas Online : Biológicas e Saúde , 2011,
Abstract: O objetivo deste estudo foi avaliar quanto risco um exercício de resistência excêntrico pode proporcionar aosindivíduos que apresentem distintas respostas de hiperCKemia. Vinte e seis homens saudáveis realizaram umprotocolo de exercício, durante o qual duas séries de 30 repeti es excêntricas de rosca bíceps foramrealizadas com 120% de 1 repeti o máxima (1RM). Os indivíduos forneceram amostras de sangue antes e48h após o exercício para avaliar níveis séricos da creatina quinase (CK). Baseado nas respostas da atividadesérica de CK os sujeitos foram separados em dois grupos, denominados: Respondedores Normais (NR) ouAltos Respondedores (HR). Uma grande variabilidade interindividual na atividade sérica de CK após oexercício e uma diferen a significativa entre NR e HR foram observadas. O volume de treino n odemonstrou diferen a significativa entre NR e HR. O principal achado foi a grande variabilidadeinterindividual da atividade sérica da CK, que é observada mesmo quando se usa um único exercíciomostrando varia o no risco de les es entre os indivíduos.
Asma e rinite alérgica como express o de uma única doen a: um paradigma em constru o
Camargos Paulo Augusto Moreira,Rodrigues Mary Elisabeth Santos Moura,Solé Dirceu,Scheinmann Pierre
Jornal de Pediatria , 2002,
Abstract: Objetivos: abordar os conceitos atuais sobre as inter-rela es das vias aéreas superiores e inferiores e apresentar as evidências epidemiológicas, imunológicas e fisiopatológicas que respaldam o paradigma da entidade que se convencionou denominar de "doen a das vias aéreas unidas". Fontes dos dados: realizou-se levantamento bibliográfico, através de bancos de dados eletr nicos (Medline, MD Consult, HighWire, Medscape e LILACS) abrangendo os últimos 20 anos, utilizando-se as palavras-chave asma e rinite alérgica. Síntese dos dados: as evidências epidemiológicas das inter-rela es de rinite alérgica com asma incluem a prevalência de asma em pacientes com rinite alérgica e vice-versa, os resultados relatados pelo International Study of Asthma and Allergies in Childhood, a presen a da hiper-responsividade br nquica em pacientes com rinite alérgica, bem como a importancia dos fatores genéticos, ambientais e a idade de início da atopia como determinantes dessa associa o. Aspectos morfológicos e fisiológicos também revelam as semelhan as e diferen as estruturais entre a mucosa nasal e br nquica, bem como os mecanismos que explicariam a influência da rinite alérgica na asma, especialmente a respira o oral secundária à obstru o nasal. Da mesma forma, evidências imunológicas revelam as conex es entre ambas, a saber, rea es inflamatórias desencadeadas pela exposi o aos alérgenos e a participa o da medula óssea como provedora de precursores das células inflamatórias. Finalmente, s o apresentados os resultados dos estudos sobre o efeito protetor do tratamento da rinite alérgica na redu o da hiper-responsividade br nquica e no controle clínico e funcional da asma. Conclus es: diante destas evidências é lícito admitir a rinite alérgica e a asma como doen as inter-relacionadas, e o paradigma da unicidade das vias aéreas abre perspectivas promissoras para o advento de estratégias terapêuticas integradas para estas afec es.
Compressed and quantized correlation estimators
Augusto Zebadua,Pierre-Olivier Amblard,Eric Moisan,Olivier . J. J. Michel
Statistics , 2015,
Abstract: In passive monitoring using sensor networks, low energy supplies drastically constrain sensors in terms of calculation and communication abilities. Designing processing algorithms at the sensor level that take into account these constraints is an important problem in this context. We study here the estimation of correlation functions between sensors using compressed acquisition and one-bit-quantization. The estimation is achieved directly using compressed samples, without considering any reconstruction of the signals. We show that if the signals of interest are far from white noise, estimation of the correlation using $M$ compressed samples out of $N\geq M$ can be more advantageous than estimation of the correlation using $M$ consecutive samples. The analysis consists of studying the asymptotic performance of the estimators at a fixed compression rate. We provide the analysis when the compression is realized by a random projection matrix composed of independent and identically distributed entries. The framework includes widely used random projection matrices, such as Gaussian and Bernoulli matrices, and it also includes very sparse matrices. However, it does not include subsampling without replacement, for which a separate analysis is provided. When considering one-bit-quantization as well, the theoretical analysis is not tractable. However, empirical evidence allows the conclusion that in practical situations, compressed and quantized estimators behave sufficiently correctly to be useful in, for example, time-delay estimation and model estimation.
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