Hector Castellanos - Academia.edu (original) (raw)

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Papers by Hector Castellanos

This paper has to do with the introduction of an algebraic operator method suitable for applicati... more This paper has to do with the introduction of an algebraic operator method suitable for applications in a wide area of optics. The algebraic structure of this method allows us to derive results usually obtained by using the method of rays in classical optics. Here, we treat the propagation of electromagnetic waves in the framework of paraxial approach, where the paraxial wave equation is viewed as the Schrödinger's wave equation of quantum theory. The time variable of the Schrödinger's equation plays the role of a coordinate along the propagation axis. From this point of view, a formal analogy among the wave optics and quantum mechanics is constructed. In this work, the impulse response function (IRF) for a thick lens is obtained, and from this, the well known corresponding matrix transformation in classical optics is deduced.

Gastrointestinal Endoscopy, 2004

Ideal management for choledocholithiasis (CBDS) in the laparoscopic era is not well established, ... more Ideal management for choledocholithiasis (CBDS) in the laparoscopic era is not well established, let alone have we an idea about the cost of each treatment. AIMS & METHODS: We present a prospective and randomized study of laparoscopic cholecystectomy (LC) with two different approaches: preoperative ERCP(Pre) vs intraoperative ERCP(Intra) for Cholelithiasis with intermediate clinical, analytical or ultrasound suspicion of CBDS. We obtained hospital cost per patient (pts) trough a full costing accounting system. IntraoperativeERCP were performed using a rendez vous technique. We performed a thoroughly follow up of all complications occurred. We considered treatment failure if patient could not get rid of CBDS within the group of treatment that were firstly allocated. RESULTS: 58 and 53 pts ASA I or II, [18-80 y-o] were allocated into Pre and Intra group respectively. Two pts of the Intra were changed to the Pre group because of cholangitis while they were waiting for surgery. By Intention-to-treat both groups were homogeneous saving that bilirubin level was higher in the Pre group but also the number of pts whom we performed ERCP during their first admission. The rate of success on CBDS management were similar (Pre 96,6% and Intra 86,5%).If we had excluded as a failure the two patients of Intra group, the success rate would be raised to 90.2%. We did not have mortality.

Objetivo: Reconocer la relación entre el tipo de lactancia materna y el riesgo de asma bronquial.... more Objetivo: Reconocer la relación entre el tipo de lactancia materna y el riesgo de asma bronquial. Métodos: Estudio de casos y controles. Los casos (asmáticos, n= 31) y controles (no asmáticos, n=79) se seleccionaron de una muestra no probabilística de tipo accidental. El análisis se realizó por regresión múltiple. Ambiente: Dos comunidades de los Estados Lara y Yaracuy, entre 1998 y 1999. resultados: La lactancia materna complementaria, así como la suplementaria se asociaron a mayor riesgo de presentar el diagnóstico de asma bronquial (razones de posibilidades iguales a 4,5 y 17,8, respectivamente). Conclusiones: La lactancia materna exclusiva parece asociarse a protección contra el asma bronquial, por lo que debe ser promovida en las comunidades.

... questionnaire for prostate cancer patients was applied over a period of 5 consecutive months ... more ... questionnaire for prostate cancer patients was applied over a period of 5 consecutive months (from March to July 2008) to ... 1 Shuck-Bello Carlos,1 Cantellano-Orozco Mauricio,1 Morales-Montor Jorge,1 Pacheco-Gabhler Carlos,1 Calderón-Ferro Francisco ... Vázquez-Ortega L et al ...

Journal of Protein Chemistry, 1997

A simple, reliable procedure for practically quantitative (90–98%) and fast (EDTA 100 mM (100 μl ... more A simple, reliable procedure for practically quantitative (90–98%) and fast (EDTA 100 mM (100 μl for a 100-pmol BSA band), at room temperature. Eluted proteins can be directly analyzed by RP-HPLC, quantitatively loaded onto a PVDF membrane, or, provided that they are previously renatured on-gel, analyzed by biological activity tests. The application of the procedure to in-solution enrichment of scarce proteins for N-terminal analysis is shown.

This paper describes the need to interconnect the isolated electric grid in the state of Baja Cal... more This paper describes the need to interconnect the isolated electric grid in the state of Baja California Sur to the Mexican interconnected electrical system by means of a submarine cable. For this purpose, two technologies are considered: HVDC classic and HVDC light. Relevant results from an initial feasibility study are presented, along with system performance with both alternatives.

Clinical & Translational Oncology, 2003

Grupo Cooperativo-Instituto Venezolano de los Seguros Sociales (GC-IVSS). Caracas. Venezuela. aHo... more Grupo Cooperativo-Instituto Venezolano de los Seguros Sociales (GC-IVSS). Caracas. Venezuela. aHospital Miguel Pérez Carreño IVSS. bHospital Universitario de Caracas. cHospital Central de Valencia. dHospital Raúl Leoni San Félix IVSS. eHospital Central de San ...

American Journal of Physical Anthropology, 2009

All major ABO blood alleles are found in most populations worldwide, whereas the majority of Nati... more All major ABO blood alleles are found in most populations worldwide, whereas the majority of Native Americans are nearly exclusively in the O group. O allele molecular characterization could aid in elucidating the possible causes of group O predominance in Native American populations. In this work, we studied exon 6 and 7 sequence diversity in 180 O blood group individuals from four different Mesoamerican populations. Additionally, a comparative analysis of genetic diversity and population structure including South American populations was performed. Results revealed no significant differences among Mesoamerican and South American groups, but showed significant differences within population groups attributable to previously detected differences in genetic drift and founder effects throughout the American continent. Interestingly, in all American populations, the same set of haplotypes O1, O1v, and O1v(G542A) was present, suggesting the following: (1) that they constitute the main genetic pool of the founding population of the Americas and (2) that they derive from the same ancestral source, partially supporting the single founding population hypothesis. In addition, the consistent and restricted presence of the G542A mutation in Native Americans compared to worldwide populations allows it to be employed as an Ancestry informative marker (AIM). Present knowledge of the peopling of the Americas allows the prediction of the way in which the G542A mutation could have emerged in Beringia, probably during the differentiation process of Asian lineages that gave rise to the founding population of the continent. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc.

Forensic Science International-genetics, 2010

Industrial & Engineering Chemistry Research, 2004

Silica colloids were sterically stabilized in supercritical CO2 by end-grafting poly (1H, 1H-dihy... more Silica colloids were sterically stabilized in supercritical CO2 by end-grafting poly (1H, 1H-dihydroperfluorooctyl methacrylate)(PFOMA) onto the particle surfaces. Turbidity versus time measurements were used to determine the CO2 density below which the colloids ...

Journal of Supercritical Fluids, 2004

Spectroscopic ellipsometry was used to characterize the chain extension and optical properties of... more Spectroscopic ellipsometry was used to characterize the chain extension and optical properties of end-grafted deuterated poly(dimethylsiloxane) (d-PDMS) brushes on SiO x wafers exposed to liquid and supercritical carbon dioxide (CO 2 ). The brush properties were manipulated by tuning the CO 2 solvent quality over a large range from ideal gas conditions (non-solvent) to a near-solvent by varying temperature and CO 2 density. The chain extension determined by ellipsometry, for an average value of the pure component refractive index of CO 2 in the film (average n CO 2 model), is in good agreement with that determined from neutron reflectivity. The d-PDMS chains extend into the CO 2 and the brush refractive index decreases as the solvent density is increased, especially at densities above the upper critical solution density for bulk PDMS in CO 2 .

Obstetrical & Gynecological Survey, 1964