354 research outputs found

    Uniform convergence to equilibrium for granular media

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    We study the long time asymptotics of a nonlinear, nonlocal equation used in the modelling of granular media. We prove a uniform exponential convergence to equilibrium for degenerately convex and non convex interaction or confinement potentials, improving in particular results by J. A. Carrillo, R. J. McCann and C. Villani. The method is based on studying the dissipation of the Wasserstein distance between a solution and the steady state

    A comparison between preterm and full-term infants\u2019 preference for faces [Uma compara\ue7\ue3o entre rec\ue9m-nascidos prematuros e a termo na prefer\ueancia por faces]

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    Objective: Visual preference for faces at birth is the product of a multimodal sensory experience experienced by the fetus even during the gestational period. The ability to recognize faces allows an ecologically advantageous interaction with the social environment. However, perinatal events such as premature birth, may adversely affect the adequate development of this capacity. In this study, we evaluated the preference for facial stimuli in preterm infants within the first few hours after birth. Methods: This is a cross-sectional observational study of 59 newborns, 28 preterm and 31 full-term infants. The babies were assessed in the first hours of life, with two white boards in the shape of a head and neck: one with the drawing of a face similar to the human face (natural face), and one with the drawing of misaligned eyes, mouth and nose (distorted face). After the newborn fixated the eyes on the presented stimulus, it was slowly moved along the visual field. The recognition of the stimulus was considered present when the baby had eye or head movements toward the stimulus. Results: The preterm infants, in addition to showing a lower occurrence of orientation movements for both stimuli, on average (1.8 ± 1.1 to natural faces and 2.0 ± 1.2 for distorted ones) also showed no preference for any of them (p = 0.35). Full-term newborns showed a different behavior, in which they showed a preference for natural faces (p = 0.002) and a higher number of orientations for the stimulus, for both natural (3.2 ± 0.8) and distorted faces (2.5 ± 0.9). Conclusion: Preterm newborns recognize facial stimuli and disclose no preference for natural faces, different from full-term newborns. Resumo: Objetivo: A preferência visual por faces ao nascimento é produto de uma experiência sensorial multimodal vivenciada pelo feto ainda no período gestacional. A habilidade de reconhecer faces possibilita uma interação ecologicamente vantajosa com o ambiente social. Entretanto, eventos perinatais, como o nascimento prematuro, podem prejudicar o desenvolvimento adequado dessa habilidade. Nesse trabalho, avaliamos a preferência por estímulos faciais de recém-nascidos prematuros nas primeiras horas após o nascimento. Métodos: Trata-se de um estudo observacional transversal realizado com 59 recém-nascidos, 28 prematuros e 31 nascidos termos. Os bebês foram avaliados, nas primeiras horas de vida, com duas pranchas brancas em formato de cabeça e pescoço: uma com o desenho de uma face similar ao rosto humano (face natural), e outra com o desenho de olhos, boca e nariz desalinhados (face distorcida). Após o recém-nascido fixar o olhar no estímulo apresentado o mesmo era lentamente movimentado ao longo do campo visual. O reconhecimento do estímulo foi considerado presente quando o bebê apresentou movimentos dos olhos ou cabeça em direção ao estímulo. Resultados: Os recém-nascidos prematuros além de apresentarem menor ocorrência de movimentos de orientação para ambos os estímulos, em média (1,8 ± 1,1 para faces naturais e 2,0 ± 1,2 para faces distorcidas), também não apresentaram preferência por qualquer um deles (p = 0,35). Diferente foi o comportamento dos recém-nascidos a termo que apresentaram preferência por faces naturais (p = 0,002) e um número maior de orientações para o estímulo, tanto para faces naturais (3,2 ± 0,8) quanto para faces distorcidas (2,5 ± 0,9). Conclusão: Recém-nascidos prematuros reconhecem os estímulos faciais e não apresentam preferência por faces naturais, diferente de recém-nascidos a termos. Keywords: Model of visual recognition, Visual perception, Newborn, Preterm infant, Full-term infant, Palavras-chave: Reconhecimento visual de modelos, Percepção visual, Recém-nascido, Prematuro, Nascimento a term

    Oval Domes: History, Geometry and Mechanics

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    An oval dome may be defined as a dome whose plan or profile (or both) has an oval form. The word Aoval@ comes from the latin Aovum@, egg. Then, an oval dome has an egg-shaped geometry. The first buildings with oval plans were built without a predetermined form, just trying to close an space in the most economical form. Eventually, the geometry was defined by using arcs of circle with common tangents in the points of change of curvature. Later the oval acquired a more regular form with two axis of symmetry. Therefore, an “oval” may be defined as an egg-shaped form, doubly symmetric, constructed with arcs of circle; an oval needs a minimum of four centres, but it is possible also to build polycentric ovals. The above definition corresponds with the origin and the use of oval forms in building and may be applied without problem until, say, the XVIIIth century. Since then, the teaching of conics in the elementary courses of geometry made the cultivated people to define the oval as an approximation to the ellipse, an “imperfect ellipse”: an oval was, then, a curve formed with arcs of circles which tries to approximate to the ellipse of the same axes. As we shall see, the ellipse has very rarely been used in building. Finally, in modern geometrical textbooks an oval is defined as a smooth closed convex curve, a more general definition which embraces the two previous, but which is of no particular use in the study of the employment of oval forms in building. The present paper contains the following parts: 1) an outline the origin and application of the oval in historical architecture; 2) a discussion of the spatial geometry of oval domes, i. e., the different methods employed to trace them; 3) a brief exposition of the mechanics of oval arches and domes; and 4) a final discussion of the role of Geometry in oval arch and dome design

    Population analysis of vitamin D receptor polymorphisms and the role of genetic ancestry in an admixed population

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    The vitamin D receptor (VDR) is an essential protein related to bone metabolism. Some VDR alleles are differentially distributed among ethnic populations and display variable patterns of linkage disequilibrium (LD). In this study, 200 unrelated Brazilians were genotyped using 21 VDR single nucleotide polymorphisms (SNPs) and 28 ancestry informative markers. The patterns of LD and haplotype distribution were compared among Brazilian and the HapMap populations of African (YRI), European (CEU) and Asian (JPT+CHB) origins. Conditional regression and haplotype-specific analysis were performed using estimates of individual genetic ancestry in Brazilians as a quantitative trait. Similar patterns of LD were observed in the 5′ and 3′ gene regions. However, the frequency distribution of haplotype blocks varied among populations. Conditional regression analysis identified haplotypes associated with European and Amerindian ancestry, but not with the proportion of African ancestry. Individual ancestry estimates were associated with VDR haplotypes. These findings reinforce the need to correct for population stratification when performing genetic association studies in admixed populations

    The encounter with the unknown: Nurses lived experiences of their responsibility for the care of the patient in the Swedish ambulance service

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    Registered nurses (RNs) have, according to the Swedish National Board of Health and Welfare, the overall responsibility for the medical care in the ambulance care setting. Bringing RNs into the ambulance service are judged, according to earlier studies, to lead to a degree of professionalism with a higher quality of medical care. Implicitly in earlier studies, the work in the ambulance service involves interpersonal skills. The aim of this study was to describe RNs' experiences of being responsible for the care of the patient in the Swedish ambulance service. A reflective lifeworld approach within the perspective of caring science was used. Five RNs with at least five years experience from care in the ambulance care setting were interviewed. The findings show that the essence of the phenomenon is to prepare and create conditions for care and to accomplish care close to the patient. Three meaning constituents emerged in the descriptions: prepare and create conditions for the nursing care, to be there for the patient and significant others and create comfort for the patient and significant others. The responsibility is a complex phenomenon, with a caring perspective, emerging from the encounter with the unique human being

    Primary headaches in patients with generalized anxiety disorder

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    Although anxiety disorders and headaches are comorbid conditions, there have been no studies evaluating the prevalence of primary headaches in patients with generalized anxiety disorder (GAD). The aim of this study was to analyze the lifetime prevalence of primary headaches in individuals with and without GAD. A total of 60 individuals were evaluated: 30 GAD patients and 30 controls without mental disorders. Psychiatric assessments and primary headache diagnoses were made using structured interviews. Among the GAD patients, the most common diagnosis was migraine, which was significantly more prevalent among the GAD patients than among the controls, as were episodic migraine, chronic daily headache and aura. Tension-type headache was equally common in both groups. Primary headaches in general were significantly more common and more severe in GAD patients than in controls. In anxiety disorder patients, particularly those with GAD, accurate diagnosis of primary headache can improve patient management and clinical outcomes

    The influence of socio-economic and surveillance characteristics on breast cancer survival: a French population-based study

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    Survival data on female invasive breast cancer with 9-year follow-up from five French cancer registries were analysed by logistic regression for prognostic factors of cancer stage. The Kaplan–Meier method and log-rank test were used to estimate and compare the overall survival probability at 5 and 7 years, and at the endpoint. The Cox regression model was used for multivariate analysis. County of residence, age group, occupational status, mammographic surveillance, gynaecological prevention consultations and the diagnosis mammography, whether within a screening framework or not, were independent prognostic factors of survival. Moreover, for the same age group, and only for cancers T2 and/or N+ (whether 1, 2 or 3) and M0, the prognosis was significantly better when the diagnosis mammography was done within the framework of screening. Socio-economic and surveillance characteristics are independent prognostic factors of both breast cancer stage at diagnosis and of survival. Screening mammography is an independent prognostic factor of survival
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