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1.
IEEE Trans Image Process ; 16(5): 1355-69, 2007 May.
Artículo en Inglés | MEDLINE | ID: mdl-17491465

RESUMEN

The Fourier transform is one of the most important transformations in image processing. A major component of this influence comes from the ability to implement it efficiently on a digital computer. This paper describes a new methodology to perform a fast Fourier transform (FFT). This methodology emerges from considerations of the natural physical constraints imposed by image capture devices (camera/eye). The novel aspects of the specific FFT method described include: 1) a bit-wise reversal re-grouping operation of the conventional FFT is replaced by the use of lossless image rotation and scaling and 2) the usual arithmetic operations of complex multiplication are replaced with integer addition. The significance of the FFT presented in this paper is introduced by extending a discrete and finite image algebra, named Spiral Honeycomb Image Algebra (SHIA), to a continuous version, named SHIAC.


Asunto(s)
Algoritmos , Análisis de Fourier , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Almacenamiento y Recuperación de la Información/métodos , Procesamiento de Señales Asistido por Computador , Análisis Numérico Asistido por Computador , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
2.
J Asthma ; 44(2): 113-8, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17454325

RESUMEN

Children with asthma in low-income households in Chicago were participants in a school-based mobile van clinic, Mobile C.A.R.E. Our objective was to investigate whether long-term follow-up changed clinical markers and resource utilization. Children were evaluated by a pediatrician in a mobile allergy clinic and classified and treated based on National Asthma Education and Prevention Program (NAEPP) guidelines. Intervention consisted of assessment of allergic environment with avoidance recommendations, institution of appropriate controller therapy and inhaler technique, education on asthma and asthma management, and expectations for asthma control. Over 20,000 children were screened, 2041 were examined at least once, and 677 children had four follow-up visits. With follow-up, there was a decrease in hospitalizations and emergency room visits. Symptomatic markers (daytime and nighttime cough, wheezing, and dyspnea symptoms), frequency of rescue inhaler use, and a quality-of-life score improved from baseline. These findings suggest that ongoing school interventions may reduce resource utilization and improve clinical symptoms. Primary care physicians may be able to deliver specialized care to large numbers of inner-city children with asthma.


Asunto(s)
Antiasmáticos/uso terapéutico , Asma/terapia , Manejo de la Enfermedad , Servicios de Salud Escolar , Adolescente , Adulto , Asma/tratamiento farmacológico , Chicago , Niño , Preescolar , Estudios de Cohortes , Femenino , Humanos , Lactante , Modelos Lineales , Masculino , Educación del Paciente como Asunto , Estudios Retrospectivos , Población Urbana
3.
Vision Res ; 44(9): 857-76, 2004 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-14992831

RESUMEN

The local-global map hypothesis states that locally organized response properties--such as orientation preference--result from visuotopically organized local maps of non-retinotopic response properties. In the tree shrew, the lateral extent of horizontal patchy connections is as much as 80-100% of V1 and is consistent with the length summation property. We argue that neural signals can be transmitted across the entire extent of V1 and this allows the formation of maps at the local scale that are visuotopically organized. We describe mechanisms relevant to the formation of local maps and report modeling results showing the same patterns of horizontal connectivity, and relationships to orientation preference, seen in vivo. The structure of the connectivity that emerges in the simulations reveals a 'hub and spoke' organization. Singularities form the centers of local maps, and linear zones and saddle-points arise as smooth border transitions between maps. These findings are used to present the case for the local-global map hypothesis for tree shrew V1.


Asunto(s)
Red Nerviosa , Orientación , Tupaia/fisiología , Corteza Visual/fisiología , Animales , Tupaia/anatomía & histología , Corteza Visual/anatomía & histología
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