297 research outputs found

    Informe final diagnóstico en cosecha y poscosecha de mora y lulo en las provincias del Sumapaz y Tequendama.

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    Se presenta el diagnóstico en cosecha y postcosecha de los cultivos de mora, Rubus glaucus y lulo, Solanum quitoense, en las provincias del Sumapáz y Tequendama del departamento de Cundinamárca. Se indica la metodología del estudio realizado que incluye el diagnóstico participativo e individual, la identificación de pérdidas cosecha y postcosecha desde el campo a la ciudad, la toma de información de fuentes secundarias y el mapeo de zonas potenciales para los cultivosEstudio de caracterización de las zonas de producción de mora y lulo en el que a través de una metodología de diagnóstico participativo e individual, se observaron específicamente: las condiciones de cultivo (uso de agroquímicos), las formas de cosecha, el manejo poscosecha, el empaque y las tipologías de mercados, buscando identificar los puntos críticos de las pérdidas de cosecha y poscosecha desde el campo (sitios de producción), hasta la cuidad (centros de consumo). Como resultado se logró identificar que los productores no aplican criterios técnicos en el proceso de cosecha y acondicionamiento, que la comercialización está centrada en el esquema de intermediario-transportista, no existe organización de parte de los productores para producción y venta del producto, ausencia de estímulos para el productor en cuanto al mejoramiento de la calidad y presentación, ausencia de programas de capacitación en áreas de planificación y administración de labores del cultivo, excesiva oferta y uso de agroquímicos sin criterios técnicos ni recomendaciones adecuados y ausencia en la región de planes orientados a solucionar estos problemasLulo-Solanum quitoense - Solanum hyporhodiumMora-Rubus ulmifoliu

    The Apprentice Researcher: Using Undergraduate Researchers\u27 Personal Essays to Shape Instruction and Services

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    Little is known about the intellectual journey of advanced undergraduates engaged in the research process. Moreover, few studies of this population of library users include students\u27 personal essays as a point of analysis in their scholarly pursuits. To gain insights into the research trajectory of apprentice researchers at the University of Michigan, the Library examined the personal essays that students submitted for its inaugural undergraduate research award. These essays chronicled students\u27 intellectual growth and development throughout the research process. Drawing on observations about the unique needs of these students, the authors analyze the implications for library instruction and services

    Optimization of the experimental set-up for a turbulent separated shear flow control by plasma actuator using genetic algorithms

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    Since 1947, when Schubauer and Skramstad established the basis of the technology with its revolutionary work about steady state tools and mechanisms for the flow management, the progress of the flow control technology and the development of devices have progressed constantly. Anyway, the applicability of such devices is limited, and only few of them have arrived to the assembly workshop. The problem is that the range of actuation is still limited. Despite their operability limitations, flow control devices are of great interest for the aeronautical industry. The number of projects investigating this technology demonstrates the relevance of in the Fluid Dynamic field. The scientific interest focus not only on the industrial applications and the improvement of the technology, but also on the deep understanding of the physical phenomena associated to the flow separation, turbulence formation associated to the final drag reduction aim. A clear example of what has been mentioned is the EC MARS research project (MARS project, FP7 project number 266326). Its objectives are aimed to a better understanding of the Reynolds Stress and turbulent flow related to both drag reduction and flow control. The research was carried out through the analysis of several flow control devices and the optimization of the parameters for some of them was an important element of the research. When solving a traditional fluid dynamics optimisation problem numerical flowanalysis are used instead of experimental ones due to their lower cost and shorter needed time for evaluation of candidate solutions. Nevertheless, in the particular case of the selected flow control plasma devices the experimental measurement of the performance of each candidate configuration has been much quicker than a numerical analysis. For this reason, the corresponding optimisation problem has been solved by coupling an evolutionary optimization algorithm with an experimental device. This paper discusses the design quality and efficiency gained by this innovative coupling.Peer ReviewedPostprint (author's final draft

    Turbulent separated shear flow control by surface plasma actuator: experimental optimization by genetic algorithm approach

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    The potential benefits of active flow control are no more debated. Among many others applications, flow control provides an effective mean for manipulating turbulent separated flows. Here, a nonthermal surface plasma discharge (dielectric barrier discharge) is installed at the step corner of a backward-facing step (U 0 = 15 m/s, Re h  = 30,000, Re θ  = 1650). Wall pressure sensors are used to estimate the reattaching location downstream of the step (objective function #1) and also to measure the wall pressure fluctuation coefficients (objective function #2). An autonomous multi-variable optimization by genetic algorithm is implemented in an experiment for optimizing simultaneously the voltage amplitude, the burst frequency and the duty cycle of the high-voltage signal producing the surface plasma discharge. The single-objective optimization problems concern alternatively the minimization of the objective function #1 and the maximization of the objective function #2. The present paper demonstrates that when coupled with the plasma actuator and the wall pressure sensors, the genetic algorithm can find the optimum forcing conditions in only a few generations. At the end of the iterative search process, the minimum reattaching position is achieved by forcing the flow at the shear layer mode where a large spreading rate is obtained by increasing the periodicity of the vortex street and by enhancing the vortex pairing process. The objective function #2 is maximized for an actuation at half the shear layer mode. In this specific forcing mode, time-resolved PIV shows that the vortex pairing is reduced and that the strong fluctuations of the wall pressure coefficients result from the periodic passages of flow structures whose size corresponds to the height of the step model

    Multi-input genetic algorithm for experimental optimization of the reattachment downstream of a backward-facing step with surface plasma actuator

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    The practical interest of flow control approaches is no more debated as flow control provides an effective mean for considerably increasing the performances of ground or air transport systems, among many others applications. Here a fundamental configuration is investigated by using non-thermal surface plasma discharge. A dielectric barrier discharge is installed at the step corner of a backward-facing step (Reh=30000, Re¿=1650). Wall pressure sensors are used to estimate the reattaching location downstream of the step. The primary objective of this paper is the coupling of a numerical optimizer with an experiment. More specifically, optimization by genetic algorithm is implemented experimentally in order to minimize the reattachment point downstream of the step model. Validation through inverse problem is firstly demonstrated. When coupled with the plasma actuator and the wall pressure sensors, the genetic algorithm finds the optimum forcing conditions with a good convergence rate, the best control design variables being in agreement with the literature that uses other types of control devices than plasma. Indeed, the minimum reattaching position is achieved by forcing the flow at the shear layer mode where a large spreading rate is obtained by increasing the periodicity of the vortex street and by enhancing the vortex pairing phenomena. At the best forcing conditions, the mean flow reattachment is reduced by 20%. This article, with its experiment-based approach, demonstrates the robustness of a single-objective multi-design optimization method, and its feasibility for wind tunnel experiments.Postprint (published version

    L'aseptisation des ambiances piétonnes au XXIe siècle, entre passivité et plasticité des corps en marche

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    CRESSON UMR CNRS 1563 - Ecole Nationale Supérieure d'Architecture de Grenoble (France)Les préoccupations environnementales à l'oeuvre au XXIe siècle modifient considérablement les ambiances de la ville piétonne. En Europe et sur le continent américain, l'engouement pour la marche à pied s'accompagne d'un lissage de la ville et d'une standardisation des décors urbains dont on peut se demander s'ils ne sont pas à l'origine de nouvelles esthétiques urbaines. Dans les sociétés émergentes, le retour des énoncés hygiénistes s'accompagne de mesures explicites de pacification de la vie publique. A chaque fois, ces évolutions produisent de nouveaux jeux d'ambiance dont on connaît, depuis les travaux fondateurs de Georg Simmel (1903), Siegfried Kracauer (1926) ou encore Walter Benjamin (1936), les incidences sur les sensibilités et les sociabilités d'une époque, les pratiques urbaines et les relations à l'environnement. À l'heure où la figure du piéton est érigée en atout majeur de la ville durable, il est donc intéressant d'interroger les variations de l'expérience piétonne ordinaire auxquelles ces nouvelles esthétiques piétonnes donnent lieu. De quelles dynamiques sensibles ces variations procèdent-elles ? A quels états sensibles donnent-elles naissance ? C'est en croisant les points de vue de chercheurs issus de champs disciplinaires différents (architecture, sociologie, danse, géographie) sur trois pays (France, Brésil, Canada), et en les impliquant dans une démarche méthodologique novatrice (faire corps - prendre corps - donner corps), que nous avons tenté de révéler cette dimension processuelle des rapports entre ambiances urbaines et corps en marche. À terme, cette recherche montre comment l'évolution des cadres sensibles urbains s'incarne dans le quotidien du piéton et en quoi celle-ci procède d'une dynamique de la coplasticité

    Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

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    Metarhizium spp. fungi are able to produce resistant structures termed microsclerotia, formed by compacted and melanized threads of hyphae. These propagules are tolerant to desiccation and produce infective conidia, thus they are promising candidates to use in biological control programs. In this study, we investigated the tolerance to both UV-B radiation and heat of microsclerotia of M. robertsii strain ARSEF 2575. We also adapted the liquid medium and culture conditions to obtain mycelial pellets from the same isolate in order to compare these characteristics between both types of propagules. We followed the peroxisome biogenesis and studied the oxidative stress during differentiation from conidia to microsclerotia by transmission electron microscopy after staining with a peroxidase activity marker, and by the expression pattern of genes potentially involved in these processes. We found that despite their twice smaller size, microsclerotia exhibited higher dry biomass, yield, and conidial productivity than mycelial pellets, both with and without UV-B and heat stresses.. From the sixteen genes measured, we found an induction after 96-h differentiation in the oxidative stress marker genes MrcatA, MrcatP, and Mrgpx, the peroxisome biogenesis factors Mrpex5 and Mrpex14/17, and the photoprotection genes Mrlac1, Mrlac2, and Mrlac3. We concluded that an oxidative stress scenario is induced during microsclerotia differentiation in M. robertsii, and confirmed that due to its tolerance to desiccation, heat, and UV-B, this fungal structure could be an excellent candidate for use in biological control of pests under tropical and subtropical climates where heat and UV radiation are detrimental to entomopathogenic fungi survival and persistence.Fil: Paixão, Flávia R. S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Huarte Bonnet, Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Ribeiro-Silva, Cárita de S.. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; BrasilFil: Mascarin, Gabriel M.. Empresa Brasilera de Pesquisa Agropecuaria.; BrasilFil: Fernandes, Éverton. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; BrasilFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; Argentin

    A 2.4 - 12 microns spectrophotometric study with ISO of Cygnus X-3 in quiescence

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    We present mid-infrared spectrophotometric results obtained with the ISO on the peculiar X-ray binary Cygnus X-3 in quiescence, at orbital phases 0.83 to 1.04. The 2.4-12 microns continuum radiation observed with ISOPHOT-S can be explained by thermal free-free emission in an expanding wind with, above 6.5 microns, a possible additional black-body component with temperature T ~ 250 K and radius R ~ 5000 solar radii at 10 kpc, likely due to thermal emission by circumstellar dust. The observed brightness and continuum spectrum closely match that of the Wolf-Rayet star WR 147, a WN8+B0.5 binary system, when rescaled at the same 10 kpc distance as Cygnus X-3. A rough mass loss estimate assuming a WN wind gives ~ 1.2 10^{-4} M(sun)/yr. A line at ~ 4.3 microns with a more than 4.3 sigma detection level, and with a dereddened flux of 126 mJy, is interpreted as the expected He I 3p-3s line at 4.295 microns, a prominent line in the WR 147 spectrum. These results are consistent with a Wolf-Rayet-like companion to the compact object in Cygnus X-3 of WN8 type, a later type than suggested by earlier works.Comment: 8 pages, 10 figures ; Accepted in A&

    Recent advances in micromanipulation and transgenesis in domestic mammals

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    Background: Intracytoplasmic sperm injection (ICSI) involves mechanical transfer of a single sperm cell into ooplasm. A new application has been recently found for ICSI, the production of transgenic animals. Since the birth of ‘‘Dolly’’, the first adult somatic cloned mammal, viable offspring has been produced by nuclear transfer in many species including cattle. The present review briefly summarizes our experience with ICSI and somatic cell nuclear transfer mainly to produce transgenic embryos, as well as for the generation of new micromanipulation technique. Review: We have evaluated different factors that affect SCNT and transgenesis including the chemical activator, the transfection event and the effect of recloning. Also, we included a brief description of the ICSI technique, which we used in five different species, examining its potential to produce transgenic embryos. Finally different strategies to produce transgenic animals were analyzed: ICSI- mediated gen transfer (ICSI-MGT), Injection of cumulus cell and ooplasmic vesicle incubated for 5 min with the transgene or injection of the plasmid alone. All of them were very efficient in exogenous DNA expression at embryo stages but resulted in mosaic embryos. We demonstrated that “ICSI-MGT” assisted by chemical activation is the only treatment of sperm mediated gen transfer capable to generated transgenic embryos in ovine. Besides, after ICSI-MGT, it is possible to obtain enhanced green fluorescent protein (EGFP)-expressing embryos in five diferent species: ovine, porcine, feline, bovine and equine. Our studies also established for the first time that short term transgene co-incubation with somatic cells can produce transgene-expressing mammalian SCNT embryos, and also that parthenogenic, eDNA- expressing embryos can be obtained by injection of vesicles or eDNA alone. Moreover, eDNA-expressing embryos can be also obtained by cytoplasmic injection of vesicles in IVF zygotes, simplifying the traditional IVF pronuclear injection technique. We tried a further simplification of the technique in bovine oocytes and zygotes, by intracytoplasmically injecting them with eDNA-liposomes complexes. Approximately 70% of the cleaved embryos and 50% of the blastocysts expressed EGFP, when egfp–liposome was injected 16 h post-fertilization. Different approaches were assayed to reverse the mosaicism including a novel technique of gamete cloning. Our first approach consisted of the production of transgenic IVF embryos by vesicle microinjection to generate transgenic blastomeres to be used as donor cells for cloning. A high efficiency in mosaicism reversal and multiplication of transgenic embryos was attaineded. Other technique assayed was the separation of transgenic blastomeres followed by the aggregation of two-cell fused embryos or by the asynchronous younger blastomere successfully multiplied transgenic embryos, and theoretically reduces mosaicism rates in future offspring [15]. This technology can also be used to multiply embryos from animals with high genetic value. We demonstrated that a sperm and oocyte can be efficiently cloned. Green haploid androgenic blastomeres produced with the injection of a single sperm by egfp ICSI-MGT could be used to fertilized oocytes resulting in several homogeneous expressing embryos. This approach shows great potential because it allows for determination of the sex of the sperm nucleus prior to fertilization. It is also possible to clone previously transfected oocytes followed by the reconstruction of biparental bovine embryos to generate homogeneous transgene-expressing embryos. This review summarizes recent experiments in micromanipulation and gene transfer in domestic animals. The objective is not to exhaustedly describe the research done in this field but to present the promising methods recently developed or evaluated in our lab. Conclusion: Significant advancements have been made in the course of the recent years in micromanipulation and transgenesis techniques. In our lab we have been evaluating ICSI and Nuclear transfer mainly to produce transgenic embryos. We used also transgensis to apply or developed new micromanipulation technique in domestic animals linke sperm and oocyte cloning.Fil: Salamone, Daniel Felipe. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Unidad Ejecutora de Investigaciones En Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones En Producción Animal; ArgentinaFil: Bevacqua, Romina Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Unidad Ejecutora de Investigaciones En Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones En Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; ArgentinaFil: Pereyra Bonnet, Federico Alberto. Hospital Italiano; ArgentinaFil: Gambini, Andres. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Fisiología Animal; ArgentinaFil: Canel, Natalia Gabriela. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Fisiología Animal; ArgentinaFil: Hiriart, María Inés. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Fisiología Animal; ArgentinaFil: Vichera, Gabriel Damian. Universidad Nacional de San Martín; ArgentinaFil: Moro, Lucía Natalia. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Jarazo, Javier
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