Avoidance Control on Time Scales

We consider dynamic systems on time scales under the control of two agents. One of the agents desires to keep the state of the system out of a given set regardless of the other agent's actions. Leitmann's avoidance conditions are proved to be valid for dynamic systems evolving on an arbitrary time scale.Comment: Revised edition in JOTA format. To appear in J. Optim. Theory Appl. 145 (2010), no. 3. In Pres

Solvability for a third order discontinuous fully equation with nonlinear functional boundary conditions

We prove an existence and location result for the third order functional nonlinear boundary value problem u′′′(t) = f(t,u,u′(t),u′′(t)), for t∈[a,b], 0 = L₀(u,u′,u(t₀)), 0 = L₁(u,u′,u′(a),u′′(a)), 0 = L₂(u,u′,u′(b),u′′(b)), with t₀∈[a,b] given, f:I×C(I)×R²→R is a L¹- Carathéodory function allowing some discontinuities on t and L₀,L₁, L₂ are continuous functions depending functionally on u and u′. The arguments make use of an a priori estimate on u′′, lower and upper solutions method and degree theory. Applications to a multipoint problem and to a beam equation will be presented

Periodic solutions for some phi-Laplacian and reflection equations

This work is devoted to the study of the existence and periodicity of solutions of initial differential problems, paying special attention to the explicit computation of the period. These problems are also connected with some particular initial and boundary value problems with reflection, which allows us to prove existence of solutions of the latter using the existence of the formerThe work was partially supported by FEDER and Ministerio de Economía y Competitividad, Spain, project MTM2013-43014-P. The second author was supported by FPU scholarship, Ministerio de Educación, Cultura y Deporte, Spain and Xunta de Galicia (Spain), project EM2014/032S

Knowledge and practices of tour guides in Cuzco on the prevention and treatment of traveler's diarrhea

Objectives: To describe the knowledge and practices among tour guides in Cuzco, Peru regarding prevention and treatment of traveler's diarrhea. Methods: The main tour guide association in Cuzco organized a mandatory re-certification course for tour guides in February 2004. We invited tour guides attending this course to participate in the study. Those aged 18 to 50 who had worked as a tour guide for at least one year were asked to complete a brief anonymous questionnaire. Results: A total of 173 questionnaires were returned; 137 met the inclusion criteria and were included in the analysis. The median age was 31 years (interquartile range (IQR): 28-34 years), and 56.7% were male. The median number of foreign languages spoken by subjects included was 1, being English (91.9%) the most common, followed by French (17.9%) and Italian (16.8%). The median time working as a tour guide was 4 years (IQR: 2-8 years). Tour guidance was a full-time job for 47.1% of the subjects, and for 82.4% Inca Trail was the most commonly covered route. Traveler's diarrhea was considered a food-borne disease by 85.4%, but only 60.6% considered it a water-borne disease. The majority of subjects identified raw salads (84.4%), cold sauces (81.5%) and tap water (81.1%) as risky products whereas hot soups (77 8%) and bread (75.0%) were mainly considered as safe. Most of the tour guides considered bloody stools (84.8%) and fever (60.6%) as indications to seek medical attention. The medications most frequently recommended by tour guides were oral re-hydration solutions ( 85.1%), trimethoprim-sulphamethoxazole (26.1%) and loperamide (20.1%). Conclusions: Tour guides have a basic knowledge about traveler's diarrhea. However, more training is necessary to improve management while trekking outside of Cuzco The recommendation to seek pharmacists should be particularly addressed

Biorremediación en suelos contaminados con hidrocarburos

Se estudia la bioremediación de suelos contaminados con el interés de disminuir el efecto contaminante de hidrocarburos a niveles no tóxicos. Los ensayos a escala laboratorio, desarrollados en condiciones de temperatura, aireación y humedad controlada permiten evaluar alternativas de utilización de nutrientes, inoculación de bacterias y/o aprovechamiento de la microflora natural del suelo. Los resultados muestran la activación de la microflora natural por la utilización de nutrientes en proporción adecuada, obteniéndose remociones de hidrocaburo de 70 % en 55 días de proceso. Asimismo, se analiza la efectividad del proceso de bioremediación cuando se utiliza suelo recuperado. Así, la utilización de suelo virgen puede limitarse al mínimo evitando desmontes innecesarios para su provisión.Fil: Plaza, Gloria del Carmen. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Otero Cabada, M.. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Torres, N.. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Velásquez, M.. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Corbalán, E.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Rodríguez, T.. Instituto Nacional de Tecnología Agropecuaria; Argentin

Electrostatic polarization fields trigger glioblastoma stem cell differentiation

Over the last few years it has been understood that the interface between living cells and the underlying materials can be a powerful tool to manipulate cell functions. In this study, we explore the hypothesis that the electrical cell/material interface can regulate the differentiation of cancer stem-like cells (CSCs). Electrospun polymer fibres, either polyamide 66 or poly(lactic acid), with embedded graphene nanoplatelets (GnPs), have been fabricated as CSC scaffolds, providing both the 3D microenvironment and a suitable electrical environment favorable for CSCs adhesion, growth and differentiation. We have investigated the impact of these scaffolds on the morphological, immunostaining and electrophysiological properties of CSCs extracted from human glioblastoma multiform (GBM) tumor cell line. Our data provide evidence in favor of the ability of GnP-incorporating scaffolds to promote CSC differentiation to the glial phenotype. Numerical simulations support the hypothesis that the electrical interface promotes the hyperpolarization of the cell membrane potential, thus triggering the CSC differentiation. We propose that the electrical cell/material interface can regulate endogenous bioelectrical cues, through the membrane potential manipulation, resulting in the differentiation of CSCs. Material-induced differentiation of stem cells and particularly of CSCs, can open new horizons in tissue engineering and new approaches to cancer treatment, especially GBM

Biorremediación en suelos contaminados con hidrocarburos

Se estudia la bioremediación de suelos contaminados con el interés de disminuir el efecto contaminante de hidrocarburos a niveles no tóxicos. Los ensayos a escala laboratorio, desarrollados en condiciones de temperatura, aireación y humedad controlada permiten evaluar alternativas de utilización de nutrientes, inoculación de bacterias y/o aprovechamiento de la microflora natural del suelo. Los resultados muestran la activación de la microflora natural por la utilización de nutrientes en proporción adecuada, obteniéndose remociones de hidrocaburo de 70 % en 55 días de proceso. Asimismo, se analiza la efectividad del proceso de bioremediación cuando se utiliza suelo recuperado. Así, la utilización de suelo virgen puede limitarse al mínimo evitando desmontes innecesarios para su provisión.It was studied contaminated soils bioremediation with the interest to decrease the hydrocarbon contaminant effect to no toxic levels. The laboratory assays, developed at temperature, aeration, and moisture controlled conditions let alternative nutrients, commercial microbes addition, and/or natural soil micro flora profit evaluation. The results show the natural micro flora activation because of the adequate proportions nutrients utilization. It was obtained 70 % petroleum hydrocarbon removal in 55 process days. Also, It can limit the native soils utilization and not allowing cutting trees when it is not necessary.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES