Radial imbibition in paper under temperature differences

Spontaneous radial imbibition into thin circular samples of porous material when they have been subjected to radial temperature differences was analyzed theoretically and experimentally. The use of the Darcy equation allows us to take into account temperature variations in the dynamic viscosity and surface tension in order to found the one-dimensional equation for the imbibition fronts. Experiments in blotting paper show the good fit between the experimental data to theoretical profiles.Fil: Lopez Villa, Abel. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados. Departamento de Investigaciones Educativas.; MéxicoFil: Medina, Abraham. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados. Departamento de Investigaciones Educativas.; MéxicoFil: Higuera, F. J.. No especifíca;Fil: Mac Intyre, Jonatan Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; ArgentinaFil: Perazzo, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; ArgentinaFil: Gomba, Juan Manuel. Universidad Favaloro; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. Sede Olavarria del Centro de Investifaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires | Universidad Nacional del Centro de la Pcia.de Bs.as.. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. Sede Olavarria del Centro de Investifaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires.; Argentin

Experiences of HIV-positive postpartum women and health workers involved with community-based antiretroviral therapy adherence clubs in Cape Town, South Africa

Background The rollout of universal, lifelong treatment for all HIV-positive pregnant and breastfeeding women (“Option B+”) has rapidly increased the number of women initiating antiretroviral treatment (ART) and requiring ART care postpartum. In a pilot project in South Africa, eligible postpartum women were offered the choice of referral to the standard of care, a local primary health care clinic, or a community-based model of differentiated ART services, the adherence club (AC). ACs have typically enrolled only non-pregnant and non-postpartum adults; postpartum women had not previously been referred directly from antenatal care. There is little evidence regarding postpartum women’s preferences for and experiences of differentiated models of care, or the capacity of this particular model to cater to their specific needs. This qualitative paper reports on feedback from both postpartum women and health workers who care for them on their respective experiences of the AC. Methods One-on-one in-depth qualitative interviews were conducted with 19 (23%) of the 84 postpartum women who selected the AC and were retained at approximately 12 months postpartum, and 9 health workers who staff the AC. Data were transcribed and thematically analysed using NVivo 11. Results Postpartum women’s inclusion in the AC was acceptable for both participants and health workers. Health workers were welcoming of postpartum women but expressed concerns about prospects for longer term adherence and retention, and raised logistical issues they felt might compromise trust with AC members in general. Conclusions Enrolling postpartum women in mixed groups with the general adult population is feasible and acceptable. Preliminary recommendations are offered and may assist in supporting the specific needs of postpartum women transitioning from antenatal ART care. Trial registration Number NCT02417675 clinicaltrials.gov/ct2/show/record/NCT02417675 (retrospective reg.

Migración de gotas por efecto termocapilar: dependencia cuadrática de la tensión superficial con la temperatura

Se estudia la migración de gotas depositadas sobre una superficie sólida a la cual se le aplica un gradiente uniforme de temperatura. El presente estudio está enfocado en líquidos parcialmente mojantes denominados “self-rewetting”, cuya característica distintiva es la dependencia cuadrática de la tensión superficial con la temperatura. A pesar de que estos líquidos presentan una dinámica compleja, aquí se mostrará como las soluciones obtenidas para líquidos con dependencia lineal en la temperatura pueden adaptarse y ser utilizadas para describir su flujo. A diferencia de los líquidos con tensión superficial lineal en la temperatura, el ancho de las gotas de líquido self-rewetting crece con el tiempo.We study the migration of droplets on a solid surface which is under a uniform temperature gradient. The present article focus on partial wetting fluids which surface tension depends on the squared temperature. These type of liquids, called self-rewetting, show a complex dynamics and here we will compare with those liquids of linear dependence in the temperature. Unlike to the latter ones, the droplet width increases with the time.Fil: Mac Intyre, J. R.. Aalto University; FinlandiaFil: Gomba, Juan Manuel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perazzo, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Medicina Traslacional, Trasplante y Bioingeniería. Fundación Favaloro. Instituto de Medicina Traslacional, Trasplante y Bioingeniería; Argentina. Universidad Favaloro; Argentin

Supplementary data for article: Opsenica, I.; Tot, M.; Gomba, L.; Nuss, J. E.; Sciotti, R. J.; Bavari, S.; Burnett, J. C.; Šolaja, B. A. 4-Amino-7-Chloroquinolines: Probing Ligand Efficiency Provides Botulinum Neurotoxin Serotype A Light Chain Inhibitors with Significant Antiprotozoal Activity. Journal of Medicinal Chemistry 2013, 56 (14), 5860–5871. https://doi.org/10.1021/jm4006077

Supporting information for: [https://doi.org/10.1021/jm4006077]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1381

Droplet actuation induced by coalescence: experimental evidences and phenomenological modeling

This paper considers the interaction between two droplets placed on a substrate in immediate vicinity. We show here that when the two droplets are of different fluids and especially when one of the droplet is highly volatile, a wealth of fascinating phenomena can be observed. In particular, the interaction may result in the actuation of the droplet system, i.e. its displacement over a finite length. In order to control this displacement, we consider droplets confined on a hydrophilic stripe created by plasma-treating a PDMS substrate. This controlled actuation opens up unexplored opportunities in the field of microfluidics. In order to explain the observed actuation phenomenon, we propose a simple phenomenological model based on Newton's second law and a simple balance between the driving force arising from surface energy gradients and the viscous resistive force. This simple model is able to reproduce qualitatively and quantitatively the observed droplet dynamics

Feedback Mechanisms of DepEd English Teachers in Modular Distance Learning: A Case Study

With the shift in the educational setting from traditional classrooms to online learning for most countries and modular distance learning in the Philippines, giving feedback to the students proves to be a challenge. Research conducted during the COVID-19 pandemic, whether online or through modular learning, only included feedback as a part of the problems encountered, not as the main aspect of the research. Thus, this study explored the nature of the feedback practices delivered by English DepEd teachers to their students through modular learning. Moreover, this is primarily concerned with the teachers' experiences and methods of developing feedback for their students in this modular distance learning scheme. The study employed a qualitative research design, utilizing a single explanatory case study. The study involved eight public English high school teachers and was conducted in two public secondary high schools in Leyte. The data was collected through an interview protocol, analysed using thematic analysis, and validated through triangulation. The findings of this study revealed that explicit error correction through annotation and positive feedback through commendation are the only feedback mechanisms/corrections used by the English DepEd teachers on their modular instruction. While these practices address some of the problems in English learning through modular distance learning, it is observed that they are severely limited by internal and external factors from both teachers and students. Keywords: Feedback Practices; modular learning; teachers’ experiences and method; error correction; and positive feedback

3D NUMERICAL SIMULATIONS OF THE FLOW OF A DROP UNDER THE EFFECTSOF A RADIAL TEMPERATURE GRADIENT

It has been shown experimentally that when a drop is deposited at the center of a substrate with an axial temperature gradient (hotter in the center), thermocapillarity effects makes an outward flow to appear so that the drop evolves towards a ring whose radius increases with time. Upon reaching a critical radius, the contact line becomes unstable, showing gentle undulations whose amplitudes grow with time. Using the lubrication approximation and adopting appropriate dimensionless variables, a parameter-free differential equation is obtained that governs this type of thermocapillary flow. Numerical solutions of this equation are presented to study the unstable stage. Experimental results are compared with those obtained from the numerical solutions

Distribution épidémiologique de l’infection à VIH chez les femmes enceintes dans les dix régions du Cameroun et implications stratégiques pour les programmes de prévention

Introduction: le Cameroun se situe dans un contexte d'épidémie  généralisée du VIH. La sous-population des femmes enceintes, facilementaccessible au sein de la population générale, représente une cible  robante pour mener la surveillance du VIH et estimer l'évolution épidémiologique. L'objectif de notre étude était d'évaluer la distribution épidémiologique du VIH chez les femmes enceintes.Méthodes: étude transversale menée en 2012 chez 6521 femmes  enceintes (49,3% âgées de 15-24 ans) en première consultation prénatale (CPN1) dans 60 sites des 10 régions Camerounaises. L'algorithme en série a été utilisé pour le sérodiagnostic du VIH.Résultats: la prévalence du VIH était de 7,8% (508/6521), avec une  différence non significative (p=0,297) entre milieu rural (7,4%) et milieu urbain (8,1%). En zone rurale, cette prévalence variait de 0,7% à  l'Extrême-Nord à 11,8% au Sud. Cependant, en zone urbaine elle variait de 4% à l'Ouest à 11,1% au Sud-Ouest. Suivant l'âge, la prévalence était plus élevée (11,3%) chez les femmes de 35-39 ans. Suivant le niveau de scolarisation, la prévalence du VIH était plus faible (4,4%) chez celles non-scolarisées, et plus élevée (9,3%) chez celles ayant un niveau  primaire. Selon la profession, l'infection était plus élevée chez les  coiffeuses (15,5%), secrétaires (14,8%), commerçantes (12,9%) et  institutrices/enseignantes (10,8%). Conclusion: la prévalence du VIH reste élevée chez les femmes enceintes au Cameroun, sans distinction entre milieux rural et urbain. Les stratégies de prévention devraient s'orienter préférentiellement chez les femmes enceintes âgées, celles du niveau d'instruction primaire, et celles du  secteur des petites et moyennes entreprises

Derivas debidas al azar en una población conformada por grupos que no interactúan. Un posible mecanismo de autorregulación

Para explorar derivas de poblaciones debidas a la introducción de términos azarosos en las tasas de natalidad y mortalidad, estudiamos la dinámica de una población formada por muchos grupos de Nj integrantes inicialmente idénticos. La evolución de Nj en cada grupo está dada por dichas tasas compuestas por una parte no azarosa fija, o bien variable según una ley que la vincula con Nj, y una parte azarosa de valor medio nulo y amplitud máxima igual a una dada fracción de la primera. La parte azarosa cambia tras lapsos cuya duración contiene también una parte azarosa diferente de grupo a grupo. Un grupo se extingue si Nj se hace menor o igual a un valor mínimo. Comenzamos confirmando y agregando datos a resultados ya obtenidos: la dinámica de una tal población con tasa neta media nula muestra derivas tanto en la población total (sumatoria de los Nj), que crece, como en el número de grupos, que decrece. Agregando una regla de subdivisión de grupos la deriva de la población total es aún mayor, aunque el valor medio de Nj baja ligeramente. Finalmente introducimos un mecanismo de autorregulación asumiendo que una parte de la tasa media de mortalidad depende linealmente de Nj, con lo cual se genera para Nj, un atractor Na (valor que anula la tasa neta media). En este caso desaparecen las derivas y Nj fluctúa alrededor de Na, pero surge una condición de estabilidad en la que interviene Na y la amplitud máxima de los términos azarososWe study the dynamics of a meta-population formed by many groups with initially identical populations, Nj, to explore drifts due to the introduction of random terms in the birth and death rates. The evolution of Nj in each group is given by such rates, and these are made up by a random part with a medium value equal to zero and with a maximum amplitude equal to a given fraction of the first, and by a deterministic part, or variable according to a law that links it to Nj. The random part change after periods which lenght also contains a random part different from group to group. A group dissapeared if Nj is less than or equal to a minimum. We began by confirming and adding data to results already obtained: the dynamics of such a population with average net zero growth rate shows drifts, both in the meta-population which grows, as in the number of groups, which decreases. By adding a subdivision groups rule, the drift of the meta-population is even higher, although the average value of Nj down slightly. Finally we introduce a self-regulatory mechanism assuming that part of the average death rate is linearly dependent on Nj, this generates an attractor Na (value that overrides the average net rate). In this case, the drifts disappeares and Nj fluctuates around Na, but emerges a stability condition involving both, Na and the maximum amplitude of the random termsFil: Mac Intyre, J. R.. Universidad Nacional Del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco (UNCPBA-IFAS). Buenos Aires. ArgentinaFil: Gomba, Juan Manuel. Universidad Nacional Del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco (UNCPBA-IFAS). Buenos Aires. ArgentinaFil: Gere, José Ignacio. Universidad Nacional Del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco (UNCPBA-IFAS). Buenos Aires. ArgentinaFil: Juliarena, María Paula. Universidad Nacional Del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco (UNCPBA-IFAS). Buenos AiresFil: Gratton, Roberto. Universidad Nacional Del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física Arroyo Seco (UNCPBA-IFAS). Buenos Aires. Argentin

Re-recruiting postpartum women living with HIV into a follow-up study in Cape Town, South Africa

Objective Recruitment and retention present major challenges to longitudinal research in maternal and child health, yet there are few insights into optimal strategies that can be employed in low-resource settings. Following prior participation in a longitudinal study following women living with HIV through pregnancy and breastfeeding in Cape Town, women were re-contacted at least 18 months after the last study contact and were invited to attend an additional follow-up visit. We describe lessons learnt and offer recommendations for a multiphase recruitment approach. Results Using telephone calls, home visits, clinic tracing and Facebook/WhatsApp messages, we located 387 of the 463 eligible women and successfully enrolled 353 (91% of those contacted). Phone calls were the most successful strategy, yielding 67% of enrolments. Over half of the women had changed their contact information since participation in the previous study. We recommend that researchers collect multiple contact details and use several recruitment strategies in parallel from the start of a study. Participants in longitudinal studies may require frequent contact to update contact information, particularly in settings where mobility is common