994 resultados para 499
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Mode of access: Internet.
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Item 1038-A, 1038-B (microfiche)
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v.1. Political.--v.2. Civil.--v.3. Criminal
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El bajo peso al nacer definido por la Academia Americana de Pediatría como un peso igual a 2 500 g o menor, independientemente de la edad gestacional, se ha convertido en una entidad en ascenso en países en desarrollo y factor de riesgo para morbi-mortalidad. La proporción de niños con peso bajo al nacer que son prematuros en comparación con los que tuvieron un crecimiento intrauterino anormal, varía en el mundo, en países desarrollados, casi todos los pacientes con bajo peso al nacer son prematuros, mientras que en naciones en desarrollo los principales contribuyentes a la tasa de peso bajo al nacer son niños a término con un crecimiento menor. De etiología multifactorial incluidos factores propios del embarazo como trastornos hipertensivos del embarazo, trastornos metabólicos derivados del embarazo como la diabetes gestacional y los embarazos múltiples; y otros que no están en relación directa pero que siendo patologías crónicas preexistentes comprometen el flujo sanguíneo placentario y pueden restringir así el crecimiento intrauterino. El presente estudio es un estudio descriptivo que persigue como objetivo tener un panorama del perfil epidemiológico que presentan los recién nacidos con bajo peso al nacer, que nacen en el Hospital Especializado de Maternidad “Dr. Raúl Argüello Escolán” se revisó 130 expedientes de recién nacidos con peso al nacer entre 2,000 grs. y 2,499 grs. encontrando que las madres de estos recién nacidos, se encuentran principalmente entre las edades de 14-19 años en el 29% de los recién nacidos, en su primer embarazo en el 56.9%, en cuanto a sus controles prenatales el 99.2% llevo controles prenatales, captadas en el 69% antes de las 20 semanas de gestación y teniendo más del 60% de los casos más de 4 controles prenatales, observando que el 23% de las madres presentan condiciones clínicas preexistentes en el embarazo en las que destacan la hipertensión arterial y los problemas infecciosos en las vías urinarias, en tanto los problemas relacionados al embarazo los trastornos hipertensivos siguen a la cabeza compartiendo lugar con el embarazo múltiple y la ruptura prematura de membranas.
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High-speed videokeratoscopy is an emerging technique that enables study of the corneal surface and tear-film dynamics. Unlike its static predecessor, this new technique results in a very large amount of digital data for which storage needs become significant. We aimed to design a compression technique that would use mathematical functions to parsimoniously fit corneal surface data with a minimum number of coefficients. Since the Zernike polynomial functions that have been traditionally used for modeling corneal surfaces may not necessarily correctly represent given corneal surface data in terms of its optical performance, we introduced the concept of Zernike polynomial-based rational functions. Modeling optimality criteria were employed in terms of both the rms surface error as well as the point spread function cross-correlation. The parameters of approximations were estimated using a nonlinear least-squares procedure based on the Levenberg-Marquardt algorithm. A large number of retrospective videokeratoscopic measurements were used to evaluate the performance of the proposed rational-function-based modeling approach. The results indicate that the rational functions almost always outperform the traditional Zernike polynomial approximations with the same number of coefficients.
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Many surveillance applications (object tracking, abandoned object detection) rely on detecting changes in a scene. Foreground segmentation is an effective way to extract the foreground from the scene, but these techniques cannot discriminate between objects that have temporarily stopped and those that are moving. We propose a series of modifications to an existing foreground segmentation system\cite{Butler2003} so that the foreground is further segmented into two or more layers. This yields an active layer of objects currently in motion and a passive layer of objects that have temporarily ceased motion which can itself be decomposed into multiple static layers. We also propose a variable threshold to cope with variable illumination, a feedback mechanism that allows an external process (i.e. surveillance system) to alter the motion detectors state, and a lighting compensation process and a shadow detector to reduce errors caused by lighting inconsistencies. The technique is demonstrated using outdoor surveillance footage, and is shown to be able to effectively deal with real world lighting conditions and overlapping objects.
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The highly variable flagellin-encoding flaA gene has long been used for genotyping Campylobacter jejuni and Campylobacter coli. High-resolution melting (HRM) analysis is emerging as an efficient and robust method for discriminating DNA sequence variants. The objective of this study was to apply HRM analysis to flaA-based genotyping. The initial aim was to identify a suitable flaA fragment. It was found that the PCR primers commonly used to amplify the flaA short variable repeat (SVR) yielded a mixed PCR product unsuitable for HRM analysis. However, a PCR primer set composed of the upstream primer used to amplify the fragment used for flaA restriction fragment length polymorphism (RFLP) analysis and the downstream primer used for flaA SVR amplification generated a very pure PCR product, and this primer set was used for the remainder of the study. Eighty-seven C. jejuni and 15 C. coli isolates were analyzed by flaA HRM and also partial flaA sequencing. There were 47 flaA sequence variants, and all were resolved by HRM analysis. The isolates used had previously also been genotyped using single-nucleotide polymorphisms (SNPs), binary markers, CRISPR HRM, and flaA RFLP. flaAHRManalysis provided resolving power multiplicative to the SNPs, binary markers, and CRISPR HRM and largely concordant with the flaA RFLP. It was concluded that HRM analysis is a promising approach to genotyping based on highly variable genes.
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Any biomaterial implanted within the human body is influenced by the interactions that take place between its surface and the surrounding biological milieu. These interactions are known to influence the tissue interface dynamic, and thus act to emphasize the need to study cell-surface interactions as part of any biomaterial design process. The work described here investigates the relationship between human osteoblast attachment, spreading and focal contact formation on selected surfaces using immunostaining and digital image processing for vinculin, a key focal adhesion component. Our observations show that a relationship exists between levels of cell attachment, the degree of vinculin-associated plaque formation and biocompatibility. It also suggests that cell adhesion is not indicative of how supportive a substrate is to cell spreading, and that cell spreading