Papers by Alejandro Flores
Journal of Pediatrics, 1991
We tested the hypothesis that children with chronic relapsing colitis induced by Clostridium diff... more We tested the hypothesis that children with chronic relapsing colitis induced by Clostridium difficile toxin have defective antibody responses to C. difficile toxins as a cause of their underlying illness. Six such children were tested for serum IgG and IgA antibody to C. difficile toxin A. These six children had lower IgG anti-toxin A levels than 24 healthy children (p = 0.026) and 18 healthy adults (p = 0.0008). Five patients treated with 400 mg intravenously administered ~'-globulin per kilogram every 3 weeks had significant increases in IgG (p = 0.0t) but not IgA anti-toxin A (p = 0.406) levels, and all five had clinical resolution of their gastrointestinal symptoms as well as clearing of C. difficile cytotoxin B from their stools. These observations suggest that a dificiency of IgG anti-toxin A may predispose children to the development of chronic relapsing C. difficileinduced colitis. In such cases, intravenous ~-globulin therapy may be effective in producing clinical remission. (J PEDIATR 199t;t18:633-7)
IEEE Transactions on Geoscience and Remote Sensing, 2001
The application of tomographic techniques to the troposphere with GPS signals was demonstrated in... more The application of tomographic techniques to the troposphere with GPS signals was demonstrated in previous work using data from the Kilauea permanent network, Hawaii. Local orography of the network considered there, however, played a key role in the resolution capabilities of the technique. Here we explore the possibilities of tomographic reconstruction of the four-dimensional (4-D) structure of water vapor using a very small network of global positioning satellite (GPS) receivers with virtually no height differences between the stations. The analyzed campaign consisted of seven GPS receivers located at the Onsala Space Observatory, Onsala, Sweden, and was carried out in August 1998. Traditional meteorological data sources and tools such as the numerical weather model NCAR Mesoscale Model (MM5), satellite data from the National Oceanic and Atmospheric Administration (NOAA), Washington, DC, and data and analysis from the European Center for Medium-Range Weather Forecasting (ECMWF), Reading, U.K., have been used to evaluate our results.
IEEE Transactions on Geoscience and Remote Sensing, 1998
The authors develop a minimization functional in order to regularize the inverse problem associat... more The authors develop a minimization functional in order to regularize the inverse problem associated with three-dimensional (3D) ionospheric stochastic tomography. This functional is designed to yield, upon minimization, a solution which maximizes the frequency content of the solution below a certain cutoff, while keeping χ2 constant. The authors show how this functional can be rewritten in terms of the correlation function of the image, thereby facilitating the algorithmic implementation of the method. They then implement this functional in a Kalman filter and obtain a smoothing algorithm that acts in both space and time. Finally, they use this technique to perform global scale Global Positioning System (GPS) tomography of the ionospheric electron content
IEEE Transactions on Geoscience and Remote Sensing, 2001
The application of tomographic techniques to the troposphere with GPS signals was demonstrated in... more The application of tomographic techniques to the troposphere with GPS signals was demonstrated in previous work using data from the Kilauea permanent network, Hawaii. Local orography of the network considered there, however, played a key role in the resolution capabilities of the technique. Here we explore the possibilities of tomographic reconstruction of the four-dimensional (4-D) structure of water vapor using a very small network of global positioning satellite (GPS) receivers with virtually no height differences between the stations. The analyzed campaign consisted of seven GPS receivers located at the Onsala Space Observatory, Onsala, Sweden, and was carried out in August 1998. Traditional meteorological data sources and tools such as the numerical weather model NCAR Mesoscale Model (MM5), satellite data from the National Oceanic and Atmospheric Administration (NOAA), Washington, DC, and data and analysis from the European Center for Medium-Range Weather Forecasting (ECMWF), Reading, U.K., have been used to evaluate our results.
IEEE Transactions on Geoscience and Remote Sensing, 1998
The authors develop a minimization functional in order to regularize the inverse problem associat... more The authors develop a minimization functional in order to regularize the inverse problem associated with three-dimensional (3D) ionospheric stochastic tomography. This functional is designed to yield, upon minimization, a solution which maximizes the frequency content of the solution below a certain cutoff, while keeping χ2 constant. The authors show how this functional can be rewritten in terms of the correlation function of the image, thereby facilitating the algorithmic implementation of the method. They then implement this functional in a Kalman filter and obtain a smoothing algorithm that acts in both space and time. Finally, they use this technique to perform global scale Global Positioning System (GPS) tomography of the ionospheric electron content
Lugar y fecha: Monterrey Nuevo León 2 de Noviembre del 2012 3
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Papers by Alejandro Flores