2001
Stability in a mathematical model for HIV-l infection
Horacio Ortega, Miguel Martin-Landrove, Jorge A. Gonzalez
CIENCIA 9(4), 442-447, 2001 Maracaibo, Venezuela
We extend a previous epitope model for HIV-l infection originally developed by Nowak et al. (1995) by considering not only continually mutant free virions but also viral reservoirs as monocytes. The immunological system response to viral infections includes the attack to monocytes by specific cytotoxic cells addressed against each one of the exhibiting epitope monocytes and the removal of free viral particles by T cell mediated interactions. We obtain a non lineal system of equations that allows only numerical treatment. Under the additional hypothesis that there is no immune attack to monocytes and only a viral variant. we got a simpler model that admits the usual linearization procedure. The inclusion of immune attack against infected monocytes in general stabilizes previously unstable solutions, but if new viral variants appear the system becomes unstable. These results suggest that the whole role played by reservoirs in HIV infection is a very important one and therapy should not go on ignoring it.
Corrección, alineación y reconstrucción 3D de cortes seriados: Un caso de estudio [Correction, alignment and reconstruction of serial 3D slices: A case study]
Rhadamés E. Carmona, Marco Paluszny
XXVII Conferencia Latinoamericana de Informática, CLEI 2001, Mérida, Venezuela [article in spanish]
We present a study case of 3D reconstruction of missaligned serial sections of a biological organism, without the support of artificial landmarks. Furthermore, the illumination of the images had to be corrected. The latter consisted in the gray level adjustment of the background pixels using a correcting polynomial function, which determined the right intensity for each pixel in the whole image. Many researchers have worked in the alignment problem, mainly using techniques to minimize various cost functions. We use the average of gray level differences between corresponding pixels in every pair of consecutive images. This function is minimized using a genetic algorithm. For the 3D reconstruction, the system detects contours in the aligned images in an interactive fashion. Thus, the user can selectwhich structures to reconstruct and visualize.
