Foam front propagation in anisotropic oil reservoirs

The pressure-driven growth model is considered, describing the motion of a foam front through an oil reservoir during foam improved oil recovery, foam being formed as gas advances into an initially liquid-filled reservoir. In the model, the foam front is represented by a set of so called ‘material points’ that track the advance of gas into the liquid-filled region. According to the model, the shape of the foam front is prone to develop concave sharply-curved concavities, where the orientation of the front changes rapidly over a small spatial distance: these are referred to as 'concave corners'. These concave corners need to be propagated differently from the material points on the foam front itself. Typically the corner must move faster than those material points, otherwise spurious numerical artifacts develop in the comp uted shape of the front. A propagation rule or ‘speed up’ rule is derived for the concave corners, which is shown to be sensitive to the level of anisotropy in the permeability of the reservoir and also sensitive to the orientation of the corners themselves. In particular if a corner in an anisotropic reservoir were to be propagated according to an isotropic speed up rule, this might not be sufficient to suppress spurious numerical artifacts, at least for certain orientations of the corner. On the other hand, systems that are both heterogeneous and anisotropic tend to be well behaved numerically, regard less of whether one uses the isotropic or anisotropic speed up rule for corners. This comes about be cause, in the heterogeneous and anisotropic case, the orientation of the corner is such that the 'correct' anisotropic speed is just very slightly less than the ‘incorrect’ isotropic one. The anisotropic rule does however manage to keep the corner very slightly sharper than the isotropic rule does

Medical Students’ Perception Towards the COVID-19 Pandemic in Mexico: Distance Learning, Assisting Hospitals, and Vaccination

Background: Mexico has been one of the most affected countries by the COVID-19 pandemic. Its health workers are playing a substantial role, but they are suffering from a high mortality rate, which highlights the need of vaccinating them before any other population. Medical interns have reduced their practices, some continue to assist clinical rotations without the protective equipment, and they are not being considered for vaccination. We wanted to determine the attitude of medical students and interns towards distance learning, assisting hospitals, and vaccination. Methods: We conducted a paired survey of a cohort of medical students who were evaluated twice, in June 2020 and in December 2020, using an online survey (32-online questions) to assess their perception of the pandemic. Results: We collected the response of 384 students in the summer period and 331 in the winter period; the majority were women from non-clinical semesters, and the median age of response was 21 years old (IQR 19 – 22). We found that the percentage of acceptance for vaccination was 95.6% in the summer and 93.7% in the winter, a remarkable acceptance in both periods. The percentage of students who manifested having someone close to them with symptoms suggestive of COVID-19 was 38.5% in the summer, showing an increase to 77.6% in the winter. Conclusion: We observed that medical students had a positive attitude towards vaccination and that the probable COVID-19 cases among them have increased in just a few months

Influencia del mucílago de cactus y extracto de algas pardas marinas en la resistencia a compresión y durabilidad del hormigón

This paper presents the mechanical performance and durability of concrete with water/cement (w/c) ratios of 0.30 and 0.60 containing cactus mucilage and brown marine seaweed extract solutions (at 0.5° Brix concentrations). Cylindrical specimens (100 mm x 200 mm) were cast and moist-cured for 0 and 28 days. Compressive strength, rapid chloride permeability, and chloride diffusion tests were conducted to evaluate all of the concrete mixes at the ages of 60 and 120 days. In addition, accelerated carbonation tests were carried out on specimens at the age of 180 days by exposure to 23 °C, 60% RH and at 4.4% CO2 for 120 days. The compressive strength results showed that only one concrete mix with admixtures increased in strength compared to the control. Regarding the rapid chloride permeability, chloride diffusion and carbonation, the results indicated that the durability of concretes containing organic additions was enhanced compared to the control.Este trabajo presenta el comportamiento mecánico y de durabilidad de concretos con relaciones agua/cemento de 0.30 y 0.60, conteniendo soluciones de mucílago de nopal y extracto de algas marinas cafés (0.5 °Brix de concentración). Especímenes cilíndricos (100 mm x 200 mm) fueron elaborados y curados en húmedo por 0 y 28 días. Se evaluó la resistencia a la compresión, permeabilidad rápida y difusión de cloruros a los 60 y 120 días de edad. Adicionalmente, se realizaron pruebas de carbonatación acelerada en especímenes con 180 días de edad, expuestos a 23 °C, 60% HR y 4.4% de CO2 por 120 días. Los resultados de resistencia a la compresión muestran que únicamente una mezcla de concreto con adición orgánica incrementó su resistencia con respecto al control. Con respecto a la permeabilidad rápida a cloruros, difusión de cloruros y carbonatación, los resultados indican que la durabilidad de los concretos que contenían adiciones orgánicas fue mejorada con respecto al control

Actividad acaricida de Bacillus thuringiensis sobre el acaro rojo de las aves, Dermanyssus gallinae

El ácaro rojo Dermanyssus gallinae es limitante en la producción de aves de corral. En este estudio se evaluó el efecto de Bacillus thuringiensis var.kurstaki (Btk) sobre larvas del ácaro rojo. Se utilizó el método de bioensayos por contacto sobre larvas de D. gallinae por unidad experimental. Las concentraciones evaluadas de Btk fueron: 15, 25, 35 y 45 mg/ml. Se realizaron observaciones cada 24 horas durante 7 días. Se observó una mortalidad moderada de D. gallinae a partir del segundo día de aplicación de la bacteria (66%) y al séptimo día aumentó a 78% a 35 mg/ ml de concentración. La comparación de medias de Tukey (95% de confianza) no presentó diferencias significas (p≥0,05) entre la mortalidad de las ninfas de D. gallinae producida por las concentraciones 25, 35 y 45 mg/ml, mientras que sí se presentaron cuando se utilizaron concentraciones de 0 y 15 mg/ml. La CL50 obtenida fue de 17,8 mg/ml. Btk causó daños sobre la cutícula de D. galllinae y generó pérdida de la movilidad del ácaro rojo en un periodo de 24 horas, por lo cual puede ser considerado como un método de control alternativo a los acaricidas químicos para el control de D. gallinae en programas de manejo integrado

Valor del índice de resistencia arterial medido por Doppler en la función del injerto renal a mediano y largo plazos

Objective: To evaluate the association between the value of the arterial resistance index (RI) measured by Doppler at the month after transplantation, and the loss of graft. Secondary outcomes of loss greater than or equal to 50% of renal function, eath with functioning graft, biopsy findings (inflammation, hyalinosis, rejection, interstitial fibrosis - tubular atrophy, IFTA) are reported. Methods: A cohort study of 66 patients, who underwent renal transplantation at San José Hospital of Bogotá between October 2007 and April 2011. The RI of the hilar artery was measured by Doppler ultrasound at the month post-transplant. Most patients had follow-up until the second year. We describe the cumulative incidence of renal graft loss, loss greater than or equal to 50% of the glomerular filtration rate. At the second year after transplantation, rejection, IFTA, hyalinosis and documented inflammation were reported in protocol biopsies. Association analysis was performed on the histological outcomes. Results: only 2 cases of renal graft loss were reported, belonging to the group with normal RI (3.8%). At 3 years of follow-up, 5 patients had lost more than 50% of GFR compared to baseline, 4 occurred in patients with RI <0.8, 2 of them (3.7%) ocurred in the first year and only one patient with RI> 0.8 ocurred at 3 years. The median GFR at 3 years of follow-up in both groups is greater than 60 ml / min. In the first year of follow-up 22 (47%) patients with normal RI had IFTA, and 7 (54%) with RI> 0.8 had IFTA. Hyalinosis was reported for 23% with RI> 0.8 and 25.5% with RI <0.8. Conclusion: the outcome of the grafts depends not only on RI, but also on factors such as cold ischemia, induction and maintenance immunosuppressive treatment, degree of incompatibility between donor and recipient. Histopathological changes such as IFTA, inflammation, hyalinosis, were observed in both groups, suggesting that there are other factors stronger than the RI, which correlates with the occurrence of these findings.Objetivo: evaluar la asociación entre el valor del índice de resistencia arterial (IR) medido por doppler al mes postrasplante y la pérdida de injerto. Se reportan los desenlaces secundarios de pérdida mayor o igual al 50% de la función renal, muerte con injerto funcionante, hallazgos de la biopsia (inflamación, hialinosis, rechazo, fibrosis intersticial - atrofia tubular, IFTA, por sus siglas en inglés). Métodos: se realizó un estudio de cohorte de 66 pacientes, que recibieron trasplante renal, del Hospital San José de Bogotá, entre octubre de 2007 y abril de 2011; se midió el IR de la arteria hilar por ecografía doppler al mes postrasplante. La mayoría de los pacientes fueron seguidos hasta el segundo año. Se describe la incidencia acumulada de pérdida del injerto renal, pérdida mayor o igual al 50% de la tasa filtración glomerular; al segundo año postrasplante se reporta el rechazo, IFTA, hialinosis e inflamación documentada en las biopsias de protocolo. Se realizó análisis de asociación en los desenlaces histológicos. Resultados: solo se reportaron 2 casos de pérdida del injerto renal, pertenecientes al grupo con IR normal (3.8%). A los 3 años de seguimiento 5 pacientes habían perdido más del 50% de la TFG respecto a la basal, 4 ocurrieron en los pacientes con IR <0.8, 2 de ellos (3.7%) fueron al primer año y solo un paciente con IR >0.8 a los 3 años. La mediana de la TFG a los 3 años de seguimiento en ambos grupos es mayor de 60 ml/ min. En el primer año de seguimiento 22 (47%) pacientes con IR normal presentaron IFTA y 7 (54%) con IR >0.8 presentaron IFTA; la hialinosis con un 23% para IR >0.8 y 25.5% para IR <0.8. Conclusión: los desenlaces de los injertos no solo dependen del IR, hay otros factores que pueden influir como es el tiempo de isquemia fría, esquema de tratamiento inmunosupresor de inducción y mantenimiento, grado de incompatibilidades entre donante, receptor. Cambios histopatológicos como IFTA, inflamación, hialinosis, se observaron en cualquiera de los 2 grupos, lo que sugiere que hay otros factores más fuertes que el IR, que se correlaciona con la aparición de estos hallazgos

Assessment of quality of life in oral cancer

Quality of life (QL) in oral cancer patients has become one of the most important parameters to consider in the diagnosis and post-treatment follow-up. The purpose of this article has been to review the papers published that study the QL in oral cancer patients, the different QL questionnaires used, the clinical results obtained, and the systematic revisions available in the indexed literature for the last 10 years. The term QL appears as a keyword in an increasing number of articles throughout the past 10 years; however, few studies focus on oral cancer. Most of them assess all head and neck cancers, which conform to a heterogeneous group with several different features depending on location (oral cavity, oropharynx, larynx, hypopharynx, nasopharynx and salivary glands). Most studies evaluate QL in short periods of time, normally within the first year after the diagnosis. Series do not discern between different therapeutic options, and they generally center on Northern European or Northern American populations. There are few instruments translated and validated into Spanish that measure QL, a fundamental characteristic to link QL to own patients? socio-cultural parameters. Data related with QL are mostly related to patient (age, sex, co-morbidity), tumour (location, size), and treatment (surgical treatment, radiotherapy association, reconstruction, cervical dissection, and/or feeding tube). Nowadays QL?s assessment is considered an essential component of an oral cancer patient as well as the survival, morbidity and years free of disease. Although many aspects related to QL in oral cancer patients have been published throughout the past 10 years, more systematic research is needed to be able to apply it on a daily basis

Caracterización de la respuesta in vitro de callos de Phaseolus vulgaris cultivar ʹBAT-93ʹ a estrés hídrico inducido con PEG-6000

Water stress is one of the major abiotic factors that limits the growth and productivity of many cultures including Phaseolus. In this research the in vitro callus response of cultivar ʹBAT-93ʹ, in multiplication culture media with 6% of polyethylenglycol-6000 (PEG-6000) as water stress inductor was characterize. First, the callus response at 21 days of culture under water stress conditions was assessed. At the same time, the effect of subculture number on callus response with the use of two treatments was also determined. In the treatment I, the callus were subculture at 7 and 14 days of culture and then evaluated at 14 and 21 days respectively. In the treatment II, the callus were subcultivated at 14 days and subsequently assessed one week later. In each test, the degree of callus affectation as well as the frequency of its appearance was evaluated. The experimental design included 35 explants for both control as well as for every stress induction analysis. The callus growing in PEG-6000 free culture medium was considered as control. In this research, the water stress induction with 6% of PEG-6000 affected the in vitro response of ʹBAT-93ʹ callus. In the treatment II the use of only one in vitro callus subculture, reduced the affectation of them under stressing conditions respect to the use of two subcultures. The results constituted a step in advance in genetic focus on water stress tolerance in Phaseolus.El estrés hídrico es uno de los principales factores abióticos que limita el crecimiento y productividad de muchos cultivos incluyendo Phaseolus. En esta investigación se caracterizó la respuesta in vitro de callos del cultivar ʹBAT-93ʹ, en medio de cultivo de multiplicación con 6% de polietilenglicol-6000 (PEG-6000) como inductor de estrés hídrico. Primero, se evaluó la respuesta de los callos a los 21 días de cultivo bajo condiciones de estrés hídrico. Al mismo tiempo, se determinó el efecto del número de subcultivos en la respuesta de los callos con el uso de dos tratamientos. En el tratamiento I, los callos fueron subcultivados a los 7 y 14 días de cultivo y posteriormente evaluados a los 14 y 21 días respectivamente. En el tratamiento II, los callos se subcultivaron a los 14 días y posteriormente evaluados una semana después. En cada ensayo se evaluó el grado de afectación de los callos así como la frecuencia de su aparición. El diseño experimental incluyó 35 explantes tanto para el control así como para cada análisis de inducción de estrés. El crecimiento de los callos en medio de cultivo libre de PEG-6000 se consideró como control. En esta investigación la inducción de estrés hídrico con 6% de PEG-6000 afectó la respuesta in vitro de los callos de ʹBAT-93ʹ. En el tratamiento II la utilización de un solo subcultivo in vitro de los callos, redujo su afectación bajo condiciones estresantes respecto al uso de dos subcultivos. Los resultados constituyeron un paso de avance en los estudios de mejoramiento genético, enfocados hacia la tolerancia a estrés hídrico en Phaseolus