Shiga Toxin Detection Methods : A Short Review

The Shiga toxins comprise a family of related protein toxins secreted by certain types of bacteria. Shigella dysenteriae, some strain of Escherichia coli and other bacterias can express toxins which caused serious complication during the infection. Shiga toxin and the closely related Shiga-like toxins represent a group of very similar cytotoxins that may play an important role in diarrheal disease and hemolytic-uremic syndrome. The outbreaks caused by this toxin raised serious public health crisis and caused economic losses. These toxins have the same biologic activities and according to recent studies also share the same binding receptor, globotriosyl ceramide (Gb3). Rapid detection of food contamination is therefore relevant for the containment of food-borne pathogens. The conventional methods to detect pathogens, such as microbiological and biochemical identification are time-consuming and laborious. The immunological or nucleic acid-based techniques require extensive sample preparation and are not amenable to miniaturization for on-site detection. In the present are necessary of techniques of rapid identification, simple and sensitive which can be employed in the countryside with minimally-sophisticated instrumentation. Biosensors have shown tremendous promise to overcome these limitations and are being aggressively studied to provide rapid, reliable and sensitive detection platforms for such applications.Comment: 16 pages, 2 figure

Shot-noise anomalies in nondegenerate elastic diffusive conductors

We present a theoretical investigation of shot-noise properties in nondegenerate elastic diffusive conductors. Both Monte Carlo simulations and analytical approaches are used. Two new phenomena are found: (i) the display of enhanced shot noise for given energy dependences of the scattering time, and (ii) the recovery of full shot noise for asymptotic high applied bias. The first phenomenon is associated with the onset of negative differential conductivity in energy space that drives the system towards a dynamical electrical instability in excellent agreement with analytical predictions. The enhancement is found to be strongly amplified when the dimensionality in momentum space is lowered from 3 to 2 dimensions. The second phenomenon is due to the suppression of the effects of long range Coulomb correlations that takes place when the transit time becomes the shortest time scale in the system, and is common to both elastic and inelastic nondegenerate diffusive conductors. These phenomena shed new light in the understanding of the anomalous behavior of shot noise in mesoscopic conductors, which is a signature of correlations among different current pulses.Comment: 9 pages, 6 figures. Final version to appear in Phys. Rev.

Exciton Gas Compression and Metallic Condensation in a Single Semiconductor Quantum Wire

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidences of metallic liquid condensation at low temperatures. Firstly, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Secondly, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at $n_c\sim1\times10^5$ cm$^{-1}$ and $T_c\sim35$ K, respectively.Comment: 4 pages, 5 figure

Soliton tunneling with sub-barrier kinetic energies

We investigate (theoretically and numerically) the dynamics of a soliton moving in an asymmetrical potential well with a finite barrier. For large values of the width of the well, the width of the barrier and/or the height of the barrier, the soliton behaves classically. On the other hand, we obtain the conditions for the existence of soliton tunneling with sub-barrier kinetic energies. We apply these results to the study of soliton propagation in disordered systems.Comment: 6 eps figures. To appear in Physical Review E (Rapid Communications

Characterisation of the Interaction among Oil-In-Water Nanocapsules and Mucin

Mucins are glycoproteins present in all mucosal surfaces and in secretions such as saliva. Mucins are involved in the mucoadhesion of nanodevices carrying bioactive molecules to their target sites in vivo. Oil-in-water nanocapsules (NCs) have been synthesised for carrying N,N′-(di-m-methylphenyl)urea (DMTU), a quorum-sensing inhibitor, to the oral cavity. DMTU-loaded NCs constitute an alternative for the treatment of plaque (bacterial biofilm). In this work, the stability of the NCs after their interaction with mucin is analysed. Mucin type III from Sigma-Aldrich has been used as the mucin model. Mucin and NCs were characterised by the multi-detection asymmetrical flow field-flow fractionation technique (AF4). Dynamic light scattering (DLS) and ζ-potential analyses were carried out to characterise the interaction between mucin and NCs. According to the results, loading DMTU changes the conformation of the NC. It was also found that the synergistic interaction between mucin and NCs was favoured within a specific range of the mucin:NC ratio within the first 24 h. Studies on the release of DMTU in vitro and the microbial activity of such NCs are ongoing in our lab

Charge control in laterally coupled double quantum dots

We investigate the electronic and optical properties of InAs double quantum dots grown on GaAs (001) and laterally aligned along the [110] crystal direction. The emission spectrum has been investigated as a function of a lateral electric field applied along the quantum dot pair mutual axis. The number of confined electrons can be controlled with the external bias leading to sharp energy shifts which we use to identify the emission from neutral and charged exciton complexes. Quantum tunnelling of these electrons is proposed to explain the reversed ordering of the trion emission lines as compared to that of excitons in our system.Comment: 4 pages, 4 figures submitted to PRB Rapid Com

Resonance phenomena of a solitonlike extended object in a bistable potential

We investigate the dynamics of a soliton that behaves as an extended particle. The soliton motion in an effective bistable potential can be chaotic in a similar way as the Duffing oscillator. We generalize the concept of geometrical resonance to spatiotemporal systems and apply it to design a nonfeedback mechanism of chaos control using localized perturbations.We show the existence of solitonic stochastic resonance.Comment: 3 postscript figure

Discrete breathers in a nonlinear electric line: Modeling, Computation and Experiment

We study experimentally and numerically the existence and stability properties of discrete breathers in a periodic nonlinear electric line. The electric line is composed of single cell nodes, containing a varactor diode and an inductor, coupled together in a periodic ring configuration through inductors and driven uniformly by a harmonic external voltage source. A simple model for each cell is proposed by using a nonlinear form for the varactor characteristics through the current and capacitance dependence on the voltage. For an electrical line composed of 32 elements, we find the regions, in driver voltage and frequency, where $n$-peaked breather solutions exist and characterize their stability. The results are compared to experimental measurements with good quantitative agreement. We also examine the spontaneous formation of $n$-peaked breathers through modulational instability of the homogeneous steady state. The competition between different discrete breathers seeded by the modulational instability eventually leads to stationary $n$-peaked solutions whose precise locations is seen to sensitively depend on the initial conditions

University plan for indigenous peoples: participatory construction experience of Universidad Nacional

[ES] Este ensayo busca aportar a la discusión relacionado con la construcción de universidades más inclusivas e interculturales, desde la sistematización de la estrategia adoptada por la Universidad Nacional (UNA) en Costa Rica para la pertinente implementación del Plan para Pueblos Indígenas Quinquenal (PPIQ) suscrito por cuatro universidades públicas costarricenses en 2014, el cual tomó características diferenciadas de implementación debido a la diversidad histórica entre ellas en la construcción de relaciones con pueblos indígenas y en las formas de gestión académica y administrativa, las cuales  obligan a una adecuación singular de los acuerdos conjuntos del PPIQ.  En el caso de la UNA, la ejecución del Plan y el cumplimiento de sus compromisos se fundamenta en la participación propositiva de cada instancia involucrada desde sus experiencias y posibilidades.  Así, la coordinación original del PPIQ se amplió para absorber a los diferentes actores, con actividades propuestas y ejecutadas[EN] This essay aims to contribute to the discussion around the construction of more inclusive and intercultural universities, from the systematization of the strategy adopted by Universidad National (UNA) in Costa Rica for the pertinent implementation of the Quinquennial Plan for Indigenous Peoples (PPIQ) signed by four of the Costa Rican public universities in 2014. Its implementation took differentiated characteristics in each university, due to the diversity historically built among them in the construction of relations with indigenous peoples and in the forms of academic and administrative management, which require a singular  adaptation in each University of the PPIQ joint agreements. In the case of UNA, the execution of the Plan and the fulfillment of its commitments is based on the proactive participation of each instance involved base on their experiences and possibilities. Thus, the former coordination team of PPIQ was extended to absorb the different actors, each one of them propPino, G.; Cerdas, Y.; González, C. (2019). Plan universitario para pueblos indígenas: experiencia de construcción participativa de la Universidad Nacional. REDU. Revista de Docencia Universitaria. 17(2):127-142. https://doi.org/10.4995/redu.2019.10642127142172Asamblea Legislativa de la República de Costa Rica (1 de octubre de 2015). Reforma el artículo 1° de la Constitución Política para establecer el carácter Multiétnico y Pluricultural de Costa Rica (Ley 9305). Recuperado de: http://www.pgrweb.go.cr/scij/Busqueda/Normativa/Normas/nrm_texto_completo.aspx?param1=NRTC&nValor1=1&nValor2=80269&nValor3=101779&strTipM=TC#ddownBorges, C. (2012). Costa Rica: Estado de la educación en territorios indígenas. Informe Final. En: Programa Estado de la Nación en Desarrollo Humano Sostenible. Cuarto Informe del Estado de la Educación. San José: CONARE. Recuperado en https://estadonacion.or.cr/files/biblioteca_virtual/educacion/004/borge_educacion_indigena.pdfCamacho, C. (1998). Las paradojas de la identidad indígena: ideologías y realidades en Costa Rica. En: Bozzoli, María Eugenia, Barrantes, Ramiro, Obando, Dinorah. & Rojas, Mirna. (Comp.). (1998). Congreso Científico sobre pueblos indígenas de Costa Rica y sus fronteras. San José: EUNED.Consejo Nacional de Rectores. (2012). Proyecto de Mejora de la Educación Superior. Marco de Planificación para Pueblos Indígenas (MPPI). San José: sin publicar. Recuperado en: https://www.uned.ac.cr/images/ami/documentos/mppi_marco_planificacion_pueblos_indigenas.pdfConsejo Nacional de Rectores. (2013). Plan Quinquenal para la inclusión de Pueblos Indígenas en la Educación Superior (PPIQ). San José. Recuperado en http://documents.worldbank.org/curated/en/509651468026356958/pdf/IPP5580V20SPAN00Box385429B00PUBLIC0.pdfDe Sousa Santos, B. (2010). Descolonizar el saber, reinventar el poder. Uruguay: Ediciones Trilce.Ibarra Rojas, E. (2010). Las manchas del jaguar: huellas indígenas en la historia de Costa Rica: Valle Central, siglos XVI-XX. Costa Rica: Editorial UCR.Instituto Nacional de Estadística y Censos. (2011). X Censo Nacional de Población y VI de Vivienda: Resultados Generales. Costa Rica: INEC.Jara, O. (2012). La sistematización de experiencias, práctica y teoría para otros mundos posibles. Costa Rica: Centro de Estudios y Publicaciones Alforja.Lorente, M. (2016). Derecho a la educación de la infancia y desigualdades de origen en Centroamérica. Revista Española de Educación Comparada, 0(27), 53-71. https://doi.org/10.5944/reec.27.2016.15047Mato, D. (2009). Educación Superior, Colaboración Intercultural y Desarrollo Sostenible/Buen Vivir. Experiencias en América Latina, modalidades de colaboración, logros, innovaciones, obstáculos y desafíos. En: Mato, D. (coord.). Educación Superior, Colaboración Intercultural y Desarrollo Sostenible/Buen Vivir. Experiencias en América Latina. Venezuela: Instituto Internacional de la UNESCO para la Educación Superior en América Latina y el Caribe (IESALC-UNESCO). (pp. 11-64).Mato, D. (2010). Las iniciativas de los movimientos indígenas en educación superior: un aporte para la profundización de la democracia. Revista Nueva Sociedad 227, mayo-junio de 2010, Recuperado en http://nuso.org/buscar/?q=matoMato, D. (coordinador). (2015). Educación superior y pueblos indígenas en América Latina: contextos y experiencias. Argentina: Sáenz Peña. Universidad Nacional de Tres de Febrero.Mato, D. (2016). Educación Superior y Pueblos Indígenas en América Latina: Del "Diálogo de Saberes" a la construcción de "modalidades sostenibles de Colaboración Intercultural". Revista del Cisen Tramas/Maepova, 4 (2), 71-94.Maturana, H. (1999). Transformación en la convivencia. Chile: Dolmen Ediciones.Mejía, N., Vargas, M., Chacón., R., Campos, S., Guzmán, A., Sánchez, E. (2012). Evaluación Socioeducativo-cultural de los pueblos indígenas: acceso, permanencia y éxito en la Educación Superior Costarricense. Costa Rica: sin publicar. Recuperado en http://www.documentos.una.ac.cr/bitstream/handle/unadocs/3289/Evaluaci%C3%B3n%20Socioeducativo%20y%20Cultural%20de%20los%20Pueblos%20Ind%C3%ADgenas.pdf?sequence=1Mesa Nacional Indígena. (2010). "Así vivimos los pueblos indígenas…" Diagnóstico niñez y adolescencia indígena. UNICEF-Costa Rica. Disponible en https://www.unicef.org/costarica/docs/cr_pub_Asi_vivimos_los_pueblos_indigenas.pdfOrganización Internacional del Trabajo. (2014). Convenio Núm. 169 de la OIT sobre pueblos indígenas y tribales en países independientes. Declaración de las Naciones Unidas sobre los Derechos de los Pueblos Indígenas. Recuperado de: https://www.ilo.org/wcmsp5/groups/public/---americas/---ro-lima/documents/publication/wcms_345065.pdfOrtelli, P., Sartorello, S. (2011) Jóvenes universitarios y conflicto intercultural Estudiantes indígenas y mestizos en San Cristóbal de Las Casas, Chiapas. En: Perfiles Educativos, vol. XXXIII, número especial. México: IISUE-UNAM. Páginas 115-128. Recuperado en http://www.scielo.org.mx/pdf/peredu/v33nspe/v33nspea11.pdfRollo, T. (2016). Democracy, agency and radical children's geographies. The Practice of Freedom: Anarchism, Geography and the Spirit of Revolt. Estados Unidos: Rowman & Littlefield. Recuperado en: file:///C:/Users/Gabriela%20Pino/Downloads/Rollo-2016-DemocracyAgencyandRadicalChil.pdfSanabria, L. (2015, junio 22). Entrevista a Oscar Jara: La sistematización de experiencias produce un conocimiento crítico, dialógico, transformador. Revista Docencia de Chile (año XX, número55. Mayo 2015). Recuperado en: http://www.cepalforja.org/sistem/bvirtual/?p=1054Solano, E. (2001). La población indígena en Costa Rica según el Censo 2000. Recuperado en http://ccp.ucr.ac.cr/bvp/pdf/censo2000/libro-censo/4.1-Solano-2.doc.pdfUniversidad Nacional (UNA). (2019). Lugar de Publicación: Estadísticas Estudiantiles. Programa de interés institucional. Heredia. Recuperado de: https://www.registro.una.ac.cr/see/index.php/formacion-de-estudiantes-indigena