418 research outputs found

    Propiedades dinámicas de las gravas de Santiago

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    Aportes de Danzaterapia a la visión holística de Terapia Ocupacional en el área de rehabilitación física

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    Tesis (Terapeuta Ocupacional)... respecto a Danzaterapia no hay estudios ni investigaciones como complemento a la práctica tradicional de la Terapia Ocupacional. Algunas de las áreas de Terapia Ocupacional donde es más utilizada la Danzaterapia son visual, discapacidad auditiva, entre otros. (Lavandez G, 2009). Es por esto que consideramos relevante poder indagar en esta disciplina para conocer los fundamentos de la Danzaterapia y como se puede complementar con la práctica de la Terapia Ocupacional, en donde esta tiene una mirada que se enfoca en recuperar la funcionalidad y normalizar un cuerpo para realizar una ocupación que sea efectiva en el ambiente (Gary Kielhofner)

    Synthesis, characterization of a new carbonylated zirconium metallocene using a dichloro-zirconocene derived from partially alkylated s-indacene

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    Indexación: ScieloThis work describes the synthesis and characterization of new organometallic species, an unprecedented mononuclear zirconium complex bearing a tetraalkylated s-indacene ligand, and secondly, its respective dicarbonyl complex obtained by reduction with Mg/HgCl2. Theoretical calculations of these two compounds were carried out to gain further understanding of these novel molecular systems.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000300014&lng=es&nrm=is

    Grooming behaviour of honey bees (Hymenoptera: Apidae) on varroa (Mesostigmata: Varroidae)

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    Resumen: Entre los factores que pueden ayudar a disminuir y controlar la población de Varroa destructor en colonias de Apis mellifera está el comportamiento de acicalamiento. Este comportamiento consiste en la capacidad de la abeja de detectar, morder y eliminar los parásitos en etapa forética. En esta investigación se analizó la presencia del comportamiento de acicalamiento en colonias de abejas a través de la observación de ácaros dañados. Para ello se utilizaron seis colonias de abejas de la especie A. mellifera en colmenas tipo Langstroth, las cuales se evaluaron diariamente durante 30 días en abril y mayo del año 2008. Las muestras correspondieron a la caída diaria de ácaros a placas de metal con vaselina, ubicada en el piso de cada colmena por un periodo de 24 horas. Los resultados indicaron 95% de varroas caídas muertas y 5% vivas de un total de 2.005 varroas. Se encontró un 49% de ácaros con daños y 51% sin daños. Con base en lo observado existe la posibilidad de elegir colonias con comportamiento de acicalamiento de importancia como daño dorsal y daño completo sobre el acaro, lo cual puede ser muy útil para estudiar selección de abejas y diseñar estrategias de manejo integrado del ácaro V. destructor

    Evaluation of the viability of bee eggs Apis mellifera L. when submited to ultra-violet radiation.

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    En esta investigación se evaluó la viabilidad de huevos de Apis mellifera L. expuestos a radiación UV-A y UV-B mediante un tubo fluorescente con espectro entre los 280 nm a los 720 nm de 30 watts de potencia. El diseño experimental fue completamente al azar evaluándose viabilidad con tiempos de exposición de 0 s, 10 s, 30 s, 60 s y 90 s. El método de evaluación fue la presencia de celdillas operculadas al noveno día después de exponer los huevos de 24 horas a radiación. Los resultados obtenidos de las medias entre los distintos tiempos de exposición demostraron que existen diferencias estadísticamente significativas entre los tratamientos. Se presentó una mayor viabilidad a 0 s con 89,26%, para 10 s de exposición 56,59%, para 30 s 36,47%, para 60 s 31,46% y para 90 s de exposición 21,83% de viabilidad. Con este experimento se obtienen valiosos antecedentes sobre los cuales trabajar a fin de reducir pérdidas en crías de abejas, las cuales son sensibles a exposiciones de radiación UV.This study evaluated the viability of the eggs of Apis mellifera L. (honeybee) when exposed to UV-A and UV-B radiation using a fluorescent tube of 30 watts power with a spectrum between 280 nm and 720 nm. The design of the experiment was completely random, with evaluations of viability after exposure times of 0, 10, 30, 60 and 90 seconds. The evaluation method was the presence of operculate cells on the ninth day after exposure of 24-hour old eggs to radiation. The results obtained from the measurements among the different exposure times showed that there were statistically significant differences between the treatments. The greatest viability occurred at 0 exposure with 89.26%, followed by 56.59% for 10 s exposure, 36.47% for 30 s, 31.46% for 60 s, and 21.83% viability with 90 s exposure,. This experiment provides valuable information with which to reduce bee losses in breeding programmes, since they are sensitive to exposure to UV radiation

    Reconstruction of a Broadband Spectrum of Alfvenic Fluctuations

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    Alfvenic fluctuations in the solar wind exhibit a high degree of velocities and magnetic field correlations consistent with Alfven waves propagating away and toward the Sun. Two remarkable properties of these fluctuations are the tendencies to have either positive or negative magnetic helicity (-1 less than or equal to sigma(sub m) less than or equal to +1) associated with either left- or right- topological handedness of the fluctuations and to have a constant magnetic field magnitude. This paper provides, for the first time, a theoretical framework for reconstructing both the magnetic and velocity field fluctuations with a divergence-free magnetic field, with any specified power spectral index and normalized magnetic- and cross-helicity spectrum field fluctuations for any plasma species. The spectrum is constructed in the Fourier domain by imposing two conditions-a divergence-free magnetic field and the preservation of the sense of magnetic helicity in both spaces-as well as using Parseval's theorem for the conservation of energy between configuration and Fourier spaces. Applications to the one-dimensional spatial Alfvenic propagation are presented. The theoretical construction is in agreement with typical time series and power spectra properties observed in the solar wind. The theoretical ideas presented in this spectral reconstruction provide a foundation for more realistic simulations of plasma waves, solar wind turbulence, and the propagation of energetic particles in such fluctuating fields

    Breaking the entangling gate speed limit for trapped-ion qubits using a phase-stable standing wave

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    All laser-driven entangling operations for trapped-ion qubits have hitherto been performed without control of the optical phase of the light field, which precludes independent tuning of the carrier and motional coupling. By placing 88^{88}Sr+^+ ions in a λ=674\lambda=674 nm standing wave, whose relative position is controlled to λ/100\approx\lambda/100, we suppress the carrier coupling by a factor of 1818, while coherently enhancing the spin-motion coupling. We experimentally demonstrate that the off-resonant carrier coupling imposes a speed limit for conventional traveling-wave M{\o}lmer-S{\o}rensen gates; we use the standing wave to surpass this limit and achieve a gate duration of $15\ \mu$s, restricted by the available laser power.Comment: S. Saner and O. B\u{a}z\u{a}van contributed equally to this wor

    Effects of gamma irradiation on instream leaf litter decomposition

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    Leaf litter decomposition is a key process in stream ecosystems, the rates of which can vary with changes in litter quality or its colonization by microorganisms. Decomposition in streams is increasingly used to compare ecosystem functioning globally, often requiring the distribution of litter across countries. It is important to understand whether litter sterilization, which is required by some countries, can alter the rates of decomposition and associated processes. We examined whether litter sterilization with gamma irradiation (25 kGy) influenced decomposition rates, litter stoichiometry, and colonization by invertebrates after weeks of instream incubation within coarse-mesh and fine-mesh litterbags. We used nine plant species from three families that varied widely in litter chemistry but found mostly consistent responses, with no differences in decomposition rates or numbers of invertebrates found at the end of the incubation period. However, litter stoichiometry differed between irradiated and control litter, with greater nutrient losses (mostly phosphorus) in the former. Therefore, the effects of irradiation on litter chemistry should be taken into account in studies focused on stoichiometry but not necessarily in those focused on decomposition rates, at least within the experimental timescale considered here

    The Analysis of Field Strains Isolated From Food, Animal and Clinical Sources Uncovers Natural Mutations in Listeria monocytogenes Nisin Resistance Genes

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    Nisin is a commonly used bacteriocin for controlling spoilage and pathogenic bacteria in food products. Strains possessing high natural nisin resistance that reduce or increase the potency of this bacteriocin against Listeria monocytogenes have been described. Our study sought to gather more insights into nisin resistance mechanisms in natural L. monocytogenes populations by examining a collection of 356 field strains that were isolated from different foods, food production environments, animals and human infections. A growth curve analysis-based approach was used to access nisin inhibition levels and assign the L. monocytogenes strains into three nisin response phenotypic categories; resistant (66%), intermediate (26%), and sensitive (8%). Using this categorization isolation source, serotype, genetic lineage, clonal complex (CC) and strain-dependent natural variation in nisin phenotypic resistance among L. monocytogenes field strains was revealed. Whole genome sequence analysis and comparison of high nisin resistant and sensitive strains led to the identification of new naturally occurring mutations in nisin response genes associated with increased nisin resistance and sensitivity in this bacterium. Increased nisin resistance was detected in strains harboring RsbUG77S and PBPB3V240F amino acid substitution mutations, which also showed increased detergent stress resistance as well as increased virulence in a zebra fish infection model. On the other hand, increased natural nisin sensitivity was detected among strains with mutations in sigB, vir, and dlt operons that also showed increased lysozyme sensitivity and lower virulence. Overall, our study identified naturally selected mutations involving pbpB3 (lm0441) as well as sigB, vir, and dlt operon genes that are associated with intrinsic nisin resistance in L. monocytogenes field strains recovered from various food and human associated sources. Finally, we show that combining growth parameter-based phenotypic analysis and genome sequencing is an effective approach that can be useful for the identification of novel nisin response associated genetic variants among L. monocytogenes field strains.Peer reviewe
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