464 research outputs found

    Tendencias en el desarrollo temporal del mal del ciprés en parcelas permanentes de una reserva forestal nacional de Austrocedrus chilensis (Patagonia, Argentina)

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    Longevity is a characteristic of forest trees that influences their responses to challenges by biotic and abiotic stresses and the temporal development of symptoms. Monitoring programs have been extensively used to detect the impact of climatic change, air pollution and outbreaks of pathogens on forest health, growth and dynamics. In Argentina, forests of Patagonian cypress are affected since mid twenty century by a mortality process called «mal del ciprés» (cypress mortality), but information about their temporal progression is scarce. In the present work we used a database from a program of dasometric permanent plots to analyse the temporal development of cypress mortality on plot and tree level, and determine qualitatively the spatial distribution of affected trees. Particular pulses of appearance of affected trees shared by all plots, rapid or slow progress of mortality at tree level and a homogeneous distribution of affected trees without a clear pattern of expansion from a central point were determined. The results indicate that the episodic appearance of affected trees can be related with warm and dry climatic periods and suggest that the individuals affected by cypress mortality share some special characteristics such as genetic background, developmental conditions or physiological mechanisms for drought responses.La longevidad de las especies arbóreas afecta la respuesta a estreses bióticos o abióticos y, en gran medida, determina el desarrollo temporal de los síntomas. Por tal motivo, los programas de monitoreo se han empleado para detectar el impacto del cambio climático, la polución ambiental o estallidos de patógenos en la sanidad y dinámica de los bosques. En Argentina, los bosques de Austrocedrus chilensis sufren desde 1945 una mortalidad masiva conocida como «mal del ciprés»; sin embargo, hay escasa información sobre su progresión temporal. En el presente trabajo una base de datos de un programa de parcelas permanentes se empleó para analizar el desarrollo temporal de la mortalidad a nivel de parcela e individuo y la distribución espacial de los árboles afectados. Se determinó que la aparición de síntomas sigue un patrón de pulsos compartido por todas las parcelas, con mortalidad rápida o lenta a nivel de individuo y una distribución homogénea de la mortalidad sin un patrón de expansión desde un punto central. Los resultados indican que los episodios de afectación pueden ser relacionados con períodos climáticos cálidos y secos, sugiriendo que los individuos afectados comparten características tales como background genético, condiciones de sitio o respuesta a la sequía.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

    Tendencias en el desarrollo temporal del mal del ciprés en parcelas permanentes de una reserva forestal nacional de Austrocedrus chilensis (Patagonia, Argentina)

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    Longevity is a characteristic of forest trees that influences their responses to challenges by biotic and abiotic stresses and the temporal development of symptoms. Monitoring programs have been extensively used to detect the impact of climatic change, air pollution and outbreaks of pathogens on forest health, growth and dynamics. In Argentina, forests of Patagonian cypress are affected since mid twenty century by a mortality process called «mal del ciprés» (cypress mortality), but information about their temporal progression is scarce. In the present work we used a database from a program of dasometric permanent plots to analyse the temporal development of cypress mortality on plot and tree level, and determine qualitatively the spatial distribution of affected trees. Particular pulses of appearance of affected trees shared by all plots, rapid or slow progress of mortality at tree level and a homogeneous distribution of affected trees without a clear pattern of expansion from a central point were determined. The results indicate that the episodic appearance of affected trees can be related with warm and dry climatic periods and suggest that the individuals affected by cypress mortality share some special characteristics such as genetic background, developmental conditions or physiological mechanisms for drought responses.La longevidad de las especies arbóreas afecta la respuesta a estreses bióticos o abióticos y, en gran medida, determina el desarrollo temporal de los síntomas. Por tal motivo, los programas de monitoreo se han empleado para detectar el impacto del cambio climático, la polución ambiental o estallidos de patógenos en la sanidad y dinámica de los bosques. En Argentina, los bosques de Austrocedrus chilensis sufren desde 1945 una mortalidad masiva conocida como «mal del ciprés»; sin embargo, hay escasa información sobre su progresión temporal. En el presente trabajo una base de datos de un programa de parcelas permanentes se empleó para analizar el desarrollo temporal de la mortalidad a nivel de parcela e individuo y la distribución espacial de los árboles afectados. Se determinó que la aparición de síntomas sigue un patrón de pulsos compartido por todas las parcelas, con mortalidad rápida o lenta a nivel de individuo y una distribución homogénea de la mortalidad sin un patrón de expansión desde un punto central. Los resultados indican que los episodios de afectación pueden ser relacionados con períodos climáticos cálidos y secos, sugiriendo que los individuos afectados comparten características tales como background genético, condiciones de sitio o respuesta a la sequía.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

    T Cells Prevent Hemorrhagic Transformation in Ischemic Stroke by P-Selectin Binding

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    Objective Hemorrhagic transformation is a serious complication of ischemic stroke after recanalization therapies. This study aims to identify mechanisms underlying hemorrhagic transformation after cerebral ischemia/reperfusion. Approach and Results We used wild-type mice and Selplg(-/-) and Fut7(-/-) mice defective in P-selectin binding and lymphopenic Rag2(-/-) mice. We induced 30-minute or 45-minute ischemia by intraluminal occlusion of the middle cerebral artery and assessed hemorrhagic transformation at 48 hours with a hemorrhage grading score, histological means, brain hemoglobin content, or magnetic resonance imaging. We depleted platelets and adoptively transferred T cells of the different genotypes to lymphopenic mice. Interactions of T cells with platelets in blood were studied by flow cytometry and image stream technology. We show that platelet depletion increased the bleeding risk only after large infarcts. Lymphopenia predisposed to hemorrhagic transformation after severe stroke, and adoptive transfer of T cells prevented hemorrhagic transformation in lymphopenic mice. CD4(+) memory T cells were the subset of T cells binding P-selectin and platelets through functional P-selectin glycoprotein ligand-1. Mice defective in P-selectin binding had a higher hemorrhagic score than wild-type mice. Adoptive transfer of T cells defective in P-selectin binding into lymphopenic mice did not prevent hemorrhagic transformation. Conclusions The study identifies lymphopenia as a previously unrecognized risk factor for secondary hemorrhagic transformation in mice after severe ischemic stroke. T cells prevent hemorrhagic transformation by their capacity to bind platelets through P-selectin. The results highlight the role of T cells in bridging immunity and hemostasis in ischemic stroke

    Classical Ising model test for quantum circuits

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    We exploit a recently constructed mapping between quantum circuits and graphs in order to prove that circuits corresponding to certain planar graphs can be efficiently simulated classically. The proof uses an expression for the Ising model partition function in terms of quadratically signed weight enumerators (QWGTs), which are polynomials that arise naturally in an expansion of quantum circuits in terms of rotations involving Pauli matrices. We combine this expression with a known efficient classical algorithm for the Ising partition function of any planar graph in the absence of an external magnetic field, and the Robertson-Seymour theorem from graph theory. We give as an example a set of quantum circuits with a small number of non-nearest neighbor gates which admit an efficient classical simulation.Comment: 17 pages, 2 figures. v2: main result strengthened by removing oracular settin

    Simulation of pulse width modulation using Tinkercard

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    Este trabajo tiene como finalidad usar la plata-forma Tinkercard para comprender los conceptos de la señal PWM (modulación por ancho de pulso). Dicha plataforma nos permite crear una simulación don se pueda observar fácil-mente términos como el DutyCycle (ciclo de trabajo), el periodo de la señal, la frecuencia de la señal, el tiempo de encendido de la señal, el tiempo de apagado de la señal, entro otras ter-minologías que se deben tener en cuenta al hacer uso de esta modulación por ancho de pulso. La ventaja más importante del uso de tinkercard es su facilidad de uso y su accesibilidad ya que es gratuita y muy intuitiva, así cualquier persona puede usarla sin previo conocimiento sobre ella

    Third San Juan photoelectric astrolabe catalogue (CPASJ3)

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    Resulting from the cooperation between Beijing, San Juan and La Plata Astronomical Observatories, the photoelectric astrolabe Mark II(PAII) of the Beijing Astronomical Observatory was moved and installed at the San Juan Observatory, Argentina in January, 1992 for observations of stars in the southern hemisphere. Using the data observed with the instrument from Feb. 23 1992 to Mar. 11, 2000 over 2382 days, the Third San Juan photoelectric astrolabe catalogue has been compiled from double transits at both the eastern and western passages. There are 6762 stars in this catalogue, including 6156 Hipparcos stars (in which there are 69 radio stars), 8 FK5 stars, 47 SRS stars, 551 CAMC4 stars. The mean precisions are ±3.0 ms and ±0.053'' in right ascension and declination, respectively. The magnitudes of stars are from 1.0 to 11.5. The declinations are from -3° to -60°. The mean epoch is 1996.3. Systematic corrections of (CPASJ3-Hipp) are given.Facultad de Ciencias Astronómicas y Geofísica

    Quality appraisal of clinical guidelines for recurrent urinary tract infections using AGREE II:a systematic review

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    INTRODUCTION AND HYPOTHESIS: Recommendations for preventing and diagnosing recurrent urinary tract infection (UTI) tend to vary between clinical practice guidelines (CPGs) because of low-quality scientific evidence, potentially leading to practice variation and suboptimal care. We assessed the quality of existing CPGs for recurrent UTI. METHODS: A systematic search was performed from January 2000 to June 2021 in PubMed and EMBASE for CPGs on recurrent UTI prevention or hospital diagnostics in Dutch, English, and Spanish. Each CPG was assessed by four appraisers in a multidisciplinary review team, using the Appraisal of Guidelines, Research, and Evaluation II (AGREE II) instrument. RESULTS: We identified and assessed eight CPGs published between 2013 and 2021. The scope and purpose (mean and standard deviation: 67.3 ± 21.8) and clarity of presentation (74.8 ± 17.6) domains scored highly. However, issues with methods, patient participation, conflict of interests, and facilitators and barriers were common and resulted in lower scores for the rigour of development (56.9 ± 25.9), applicability (19.6 ± 23.4), stakeholder involvement (50.4 ± 24.6), and editorial independence (62.1 ± 23.1) domains. Overall, two CPGs were recommended, three were recommended with modifications, and three were not recommended. CONCLUSIONS: Significant room for improvement exists in the quality of CPGs for recurrent UTI, with most displaying serious limitations in the stakeholder involvement, rigour of development, and applicability domains. These aspects must be improved to decrease diagnostic and therapeutic uncertainty. Developers could benefit from using checklists and following guidelines when developing de novo CPGs

    Tendencias en el desarrollo temporal del mal del ciprés en parcelas permanentes de una reserva forestal nacional de Austrocedrus chilensis (Patagonia, Argentina)

    Get PDF
    Longevity is a characteristic of forest trees that influences their responses to challenges by biotic and abiotic stresses and the temporal development of symptoms. Monitoring programs have been extensively used to detect the impact of climatic change, air pollution and outbreaks of pathogens on forest health, growth and dynamics. In Argentina, forests of Patagonian cypress are affected since mid twenty century by a mortality process called «mal del ciprés» (cypress mortality), but information about their temporal progression is scarce. In the present work we used a database from a program of dasometric permanent plots to analyse the temporal development of cypress mortality on plot and tree level, and determine qualitatively the spatial distribution of affected trees. Particular pulses of appearance of affected trees shared by all plots, rapid or slow progress of mortality at tree level and a homogeneous distribution of affected trees without a clear pattern of expansion from a central point were determined. The results indicate that the episodic appearance of affected trees can be related with warm and dry climatic periods and suggest that the individuals affected by cypress mortality share some special characteristics such as genetic background, developmental conditions or physiological mechanisms for drought responses.La longevidad de las especies arbóreas afecta la respuesta a estreses bióticos o abióticos y, en gran medida, determina el desarrollo temporal de los síntomas. Por tal motivo, los programas de monitoreo se han empleado para detectar el impacto del cambio climático, la polución ambiental o estallidos de patógenos en la sanidad y dinámica de los bosques. En Argentina, los bosques de Austrocedrus chilensis sufren desde 1945 una mortalidad masiva conocida como «mal del ciprés»; sin embargo, hay escasa información sobre su progresión temporal. En el presente trabajo una base de datos de un programa de parcelas permanentes se empleó para analizar el desarrollo temporal de la mortalidad a nivel de parcela e individuo y la distribución espacial de los árboles afectados. Se determinó que la aparición de síntomas sigue un patrón de pulsos compartido por todas las parcelas, con mortalidad rápida o lenta a nivel de individuo y una distribución homogénea de la mortalidad sin un patrón de expansión desde un punto central. Los resultados indican que los episodios de afectación pueden ser relacionados con períodos climáticos cálidos y secos, sugiriendo que los individuos afectados comparten características tales como background genético, condiciones de sitio o respuesta a la sequía.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula
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