Synchronous oscillatory electro-inertial focusing of microparticles

Here, results are presented on the focusing of $1 \ \mu$m polystyrene particle suspensions using a synchronous oscillatory pressure-driven flow and oscillatory electric field in a microfluidic device. The effect of the phase difference between the oscillatory fields on the focusing position and focusing efficiency was investigated. The focusing position of negatively charged polystyrene particles could be tuned anywhere between the channel centerline to the channel walls. Similarly, the focusing efficiency could range from $20\%$ up to $90\%$, depending on the phase difference, for particle Reynolds numbers of order $O(10^{-4})$. The migration velocity profile was measured and the peak velocity was found to scale linearly with both the oscillatory pressure-driven flow amplitude and oscillatory electric field amplitude. Furthermore, the average migration velocity was observed to scale with the cosine of the phase difference between the fields, indicating the coupled non-linear nature of the phenomenon. Lastly, the peak migration velocity was measured for different particle radii and found to have an inverse relation, where the velocity increased with decreasing particle radius for identical conditions

Growth-induced phase changes in swimming bacteria at finite liquid interfaces

We introduce a system of bacteria confined to a finite 2D oil-water interface and driven on two distinct time scales by motility and by growth. The combined effect of activity on different time scales creates transitions between several common collective behaviors. These transitions are observed using time-lapse microscopy with high spatial and temporal resolution over eight hours. We sequentially observe an initial dilute state, a clustered state, an active turbulent state, and a glassy state, and we are able to directly observe and characterize the transitions between these states. This system allows the investigation of emergent effects surrounding transitions between phases, expanding on studies that have considered them in isolation. In particular, a peak in the velocity correlation length is observed at the turbulent-glassy transition, suggesting that this transition significantly increases the active turbulent length scale

EFECTIVIDAD Y ACTIVIDAD. MEDICIONES PARA EVALUAR DOCENTES

La evaluación de docentes se puede realizar desde diferentes puntos de vista, desde diferentes observadores y con distinto propósito. Este artículo intenta plantear algunos de los objetivos que normalmente se usan y las formas actuales de entender y medir aproximaciones a esos objetivos. Efectividad se refiere a lograr los objetivos, en este caso cuántos alumnos aprenden lo suficiente para aprobar una asignatura. Actividad se refiere a cuán intenso es el esfuerzo docente para ese logro. Ambas son medidas que ayudan a administrar y gestionar el proceso educativo. Todas estas mediciones están teñidas por las formas y métodos pedagógicos utilizados en cada situación. Hay características que se pueden medir para toda una cátedra en forma separada de las de docentes individuales. Tampoco son idénticas las mediciones para docentes que dictan clases con asistencia obligatoria o sin ella. En este artículo se tratan indicadores que cada cátedra puede medir respecto de las tareas docentes en sus diferentes aspectos y se elaboran algunos índices que resultaron útiles en la aplicación práctica en la Facultad de Ciencias Económicas de la Universidad Nacional de Tucumán

Modeling the impact of dilution on the microbial degradation time of dispersed oil in marine environments

Dispersants aid the breakup of crude oil masses and increase the available interfacial surface area for bacteria to degrade insoluble hydrocarbons in the marine environment. However, this common view neglects key aspects of the microscale interactions between bacteria and oil droplets, particularly the encounters between these elements that are required for degradation to occur. This chapter discusses a biophysical model for hydrocarbon consumption of suspended oil droplets under conditions of rapid dilution that occur in natural environments. Based on the model, which includes typical biological growth parameters, dilution is found to produce an effective delay in the onset of biodegradation by approximately a week. The steady and rapid reduction in oil concertation, due to dilution, is found to outpace the production of oil-degrading bacteria that result from colonization of degrading oil droplets, maintaining the process in an encounter-limited state. This mechanistic model provides a baseline for better understanding of microscale biodegradation in dilute oil environments and can help inform the design of mitigation strategies in marine systems

Circulating anti-galectin-1 antibodies are associated with the severity of ocular disease in autoimmune and infectious uveitis

Galectin (Gal)-1, an endogenous lectin found at sites of immune privilege, plays a critical role in the regulation of the immune response. Therapeutic administration of Gal-1 or its genetic delivery suppresses chronic inflammation in experimental models of autoimmunity. The purpose of this work was to investigate the occurrence of circulating anti-Gal-1 antibodies in patients with autoimmune and infectious uveitis as potential determinant factors of disease progression.Fil: Romero, Marta D.. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Fundación Ver; Argentina. Laboratorio Inmunopatología Investigación y Docencia LIIDO; ArgentinaFil: Muiño, Juan Carlos. Universidad Nacional de Córdoba; Argentina. Fundación Ver; ArgentinaFil: Bianco, German Ariel. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Ferrero, Mercedes. Laboratorio Inmunopatología Investigación y Docencia LIIDO; Argentina. Fundación Ver; ArgentinaFil: Juarez, Claudio P.. Fundación Ver; ArgentinaFil: Luna, José Domingo. Fundación Ver; ArgentinaFil: Rabinovich, Gabriel A.. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentin

Eye drop Self-medication: Comparative Questionnaire-based study of two Latin American cities.

A broad spectrum of ocular symptoms are treated by self-medication with commercial eye-drops.  This behavior threatens individuals' visual health. In Latin America, evidence is poor. Objective:  To  detect,  characterize  and  compare  patterns  of  ophthalmic  self-medication  between  Córdoba (Argentina) and Barranquilla (Colombia).Design:  Analytic, cross-sectional and comparative population-based study. Setting: Two private tertiary care ophthalmology centers from Córdoba, Argentina, and Barranquilla, Colombia.Participants:  Patients 18 years of age or older who consulted for the first time in this two institutions duringAugust-November 2009, were included. A number of 570 patients were enrrolled.Methods:  Data collected through a semi-structured questionnaire. Main outcome measure: To determine thefrequency of self-medication with eyedrops on a specific population of two cities in Latin America.Results:  Comparable  rates  of  ocular  self-medication  were  found  (25.6%  and  25.7%  for  Cordoba  and Barranquilla, respectively). The percentage of men and women who self-medicated was not significantly different between both samples. The major source of eye drops recommendation in the Argentineans patients was the pharmacist (31%); while the social source was predominant in Colombian individuals (53%). In Cordoba, the most frequently used product was a non-steroidal anti-inflammatory drop in combination with a vasoconstrictive agent (32%); while in Barranquilla, antibiotic eye drops were preferred (33%). Self-medication was higher between the ages of 31 and 50 years old in Argentinean citizens (28%) and between 18 to 31 years old in the Colombiancommunity (39%). This habit was found mostly in patients who completed university studies in Cordoba (33%); in Barranquilla, individuals with lower educational level practice more this behavior (36%).Conclusion:  In both populations, patients commonly treat ocular conditions by self-medicating. Currently, anincreasing number of eye drops are obtainable without prescription and a high percentage of self-medicated patients in both samples ignore the possible side effects of the used medication.Fil: Marquez, Gabriel. Fundación VER; ArgentinaFil: Hildegard Piñeros-Heilbron. Fundación Oftalmológica del Caribe; ColombiaFil: Sanchez, Victoria M.. Fundación VER; ArgentinaFil: Torres, Victor Eduardo Roque. Fundación VER; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad. Universidad Nacional de Córdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad; ArgentinaFil: Gramajo, Ana L.. Fundación VER; ArgentinaFil: Juarez, Claudio P.. Fundación VER; Argentina. Fundación Oftalmológica del Caribe; ColombiaFil: Peña, Fernando. Fundación Oftalmológica del Caribe; ColombiaFil: Luna, José D.. Fundación VER; Argentin

Splash control of drop impacts with geometric targets

Drop impacts on solid and liquid surfaces exhibit complex dynamics due to the competition of inertial, viscous, and capillary forces. After impact, a liquid lamella develops and expands radially, and under certain conditions, the outer rim breaks up into an irregular arrangement of filaments and secondary droplets. We show experimentally that the lamella expansion and subsequent break up of the outer rim can be controlled by length scales that are of comparable dimension to the impacting drop diameter. Under identical impact parameters, ie. fluid properties and impact velocity, we observe unique splashing dynamics by varying the target cross-sectional geometry. These behaviors include: (i) geometrically-shaped lamellae and (ii) a transition in splashing stability, from regular to irregular splashing. We propose that regular splashes are controlled by the azimuthal perturbations imposed by the target cross-sectional geometry and that irregular splashes are governed by the fastest-growing unstable Plateau-Rayleigh mode