2,331 research outputs found

    Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography

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    Quantum state reconstruction involves measurement devices that are usually described by idealized models, but not known in full detail in experiments. For weak propagating microwaves, the detection process requires linear amplifiers which obscure the signal with random noise. Here, we introduce a theory which nevertheless allows one to use these devices for measuring all quadrature moments of propagating quantum microwaves based on cross-correlations from a dual-path amplification setup. Simultaneously, the detector noise properties are determined, allowing for tomography. We demonstrate the feasibility of our novel concept by proof-of-principle experiments with classical mixtures of weak coherent microwaves.Comment: 11 pages, 3 figure

    Agroforestry systems of timber species and cacao: survival and growth during the early stages

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    In recent times, increased emphasis has been placed on diversifying the types of trees to shade cacao (Theobromacacao L.) and to achieve additional services. Agroforestry systems that include profitable and native timber trees are a viable alternative but it is necessary to understand the growth characteristics of these species under different environmental conditions. Thus, timber tree species selection should be based on plant responses to biotic and abiotic factors. The aims of this study were (1) to evaluate growth rates and leaf area indices of the four commercial timber species: Cordia thaisiana, Cedrela odorata, Swietenia macrophylla and Tabebuia rosea in conjunction with incidence of insect attacks and (2) to compare growth rates of four Venezuelan Criollo cacao cultivars planted under the shade of these four timber species during the first 36 months after establishment. Parameters monitored in timber trees were: survival rates, growth rates expressed as height and diameter at breast height and leaf area index. In the four Cacao cultivars: height and basal diameter. C. thaisiana and C. odorata had the fastest growth and the highest survival rates. Growth rates of timber trees will depend on their susceptibility to insect attacks as well as to total leaf area. All cacao cultivars showed higher growth rates under the shade of C. odorata. Growth rates of timber trees and cacao cultivars suggest that combinations of cacao and timber trees are a feasible agroforestry strategy in Venezuela

    Stroke etiologies in patients with COVID-19: the SVIN COVID-19 multinational registry

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    Coronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Ictus; MortalitatCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Ictus; MortalidadCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Stroke; MortalityBackground and purpose Coronavirus disease 2019 (COVID-19) is associated with a small but clinically significant risk of stroke, the cause of which is frequently cryptogenic. In a large multinational cohort of consecutive COVID-19 patients with stroke, we evaluated clinical predictors of cryptogenic stroke, short-term functional outcomes and in-hospital mortality among patients according to stroke etiology. Methods We explored clinical characteristics and short-term outcomes of consecutively evaluated patients 18 years of age or older with acute ischemic stroke (AIS) and laboratory-confirmed COVID-19 from 31 hospitals in 4 countries (3/1/20–6/16/20). Results Of the 14.483 laboratory-confirmed patients with COVID-19, 156 (1.1%) were diagnosed with AIS. Sixty-one (39.4%) were female, 84 (67.2%) white, and 88 (61.5%) were between 60 and 79 years of age. The most frequently reported etiology of AIS was cryptogenic (55/129, 42.6%), which was associated with significantly higher white blood cell count, c-reactive protein, and D-dimer levels than non-cryptogenic AIS patients (p</=0.05 for all comparisons). In a multivariable backward stepwise regression model estimating the odds of in-hospital mortality, cryptogenic stroke mechanism was associated with a fivefold greater odds in-hospital mortality than strokes due to any other mechanism (adjusted OR 5.16, 95%CI 1.41–18.87, p = 0.01). In that model, older age (aOR 2.05 per decade, 95%CI 1.35–3.11, p < 0.01) and higher baseline NIHSS (aOR 1.12, 95%CI 1.02–1.21, p = 0.01) were also independently predictive of mortality. Conclusions Our findings suggest that cryptogenic stroke among COVID-19 patients carries a significant risk of early mortality.MER-A was funded by The Instituto de Salud Carlos III (JR19/00020), Spain

    Role of the Fractalkine Receptor in CNS Autoimmune Inflammation: New Approach Utilizing a Mouse Model Expressing the Human CX3CR1

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    Multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS) is the leading cause of non-traumatic neurological disability in young adults. Immune mediated destruction of myelin and oligodendrocytes is considered the primary pathology of MS, but progressive axonal loss is the major cause of neurological disability. In an effort to understand microglia function during CNS inflammation, our laboratory focuses on the fractalkine/CX3CR1 signaling as a regulator of microglia neurotoxicity in various models of neurodegeneration. Fractalkine (FKN) is a transmembrane chemokine expressed in the CNS by neurons and signals through its unique receptor CX3CR1 present in microglia. During experimental autoimmune encephalomyelitis (EAE), CX3CR1 deficiency confers exacerbated disease defined by severe inflammation and neuronal loss. The CX3CR1 human polymorphism I249/M280 present in ∼20% of the population exhibits reduced adhesion for FKN conferring defective signaling whose role in microglia function and influence on neurons during MS remains unsolved. The aim of this study is to assess the effect of weaker signaling through hCX3CR1I249/M280 during EAE. We hypothesize that dysregulated microglial responses due to impaired CX3CR1 signaling enhance neuronal/axonal damage. We generated an animal model replacing the mouse CX3CR1 locus for the hCX3CR1I249/M280 variant. Upon EAE induction, these mice exhibited exacerbated EAE correlating with severe inflammation and neuronal loss. We also observed that mice with aberrant CX3CR1 signaling are unable to produce FKN and ciliary neurotrophic factor during EAE in contrast to wild type mice. Our results provide validation of defective function of the hCX3CR1I249/M280 variant and the foundation to broaden the understanding of microglia dysfunction during neuroinflammation. © 2018 Cardona et al

    JUEGOS DIDÁCTICOS PARA LA ENSEÑANZA DE ESCALADA DEPORTIVA EN NIÑOS DE 6 A 8 AÑOS. DIDACTIC GAMES FOR SPORTS CLIMBING IN CHILDREN FROM 6 TO 8 YEARS OLD

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    El propósito de este trabajo fue diseñar un programa de juegos didácticos para la enseñanza de escalada deportiva en niños con edades comprendidas entre los 6 a 8 años, en la escuela de escalada deportiva del Estado Mérida- Venezuela, ubicada en la Avenida Las Américas, pasos abajo del seguro social. Para su realización se llevó a cabo una investigación de enfoque cualitativo de tipo exploratorio, con un diseño de campo no experimental donde se desarrolló observaciones directas durante la práctica en la escuela deportiva y se aplicó  entrevista no estructurada con preguntas abiertas,  a una población de (20) veinte niños de ambos género. Se utilizó  la técnica de registro de observaciones y se procedió a revisar el material producto de los instrumentos utilizados para el diagnóstico inicial y comprender la realidad en cuanto a las habilidades motrices y reconocimiento básico de operaciones de matemáticas, deletreo y colores y formas. Permitiendo recolectar información a través del material utilizado con la aplicación de los juegos didácticos en la escuela de escalada. Los resultados del diagnóstico inicial  permiten concluir que durante las clases teóricas hubo falta de atención y participación por parte de los niños; mientras que en las clases de práctica en el rocódromo se mostraron entusiasta. Se observó carencias de material y recursos didácticos para la enseñanza del tipo de técnica que se desea implementar. Luego de la aplicación de los juegos didácticos se observó interés, organización y aprendizaje eficaz en los niños. Finalmente, la enseñanza de la escalada deportiva busca acercar a  los niños a este deporte a través de juegos didácticos y motivarlos a la práctica, de tal manera asegurar la generación de relevo para nuestra entidad. Descriptores: Escalada deportiva, Juegos didácticos, motivación, recreación, matemáticas, lenguaje, arte.AbstractThe purpose of this work was a program of educational games for the teaching of sports climbing in children between the ages of 6 and 8, at the sports climbing school of the State of Mérida-Venezuela, located on Avenida Las Américas, steps down from social insurance. So that an investigation of a qualitative approach of an explorer can be carried out, a design of a non-experimental field. 20) Twenty children of both genders. This involves the technique of recording the observations and processing the material product of the instruments used for the initial diagnosis and the objective of the motor skills and the basic recognition of operations of mathematics, spelling and colors and shapes. Allowing to collect information through the material used with the application of the didactic games in the climbing school. The results of the diagnosis are based on the children; while in the practice classes in the climbing wall he is enthusiastic. They are considered lacking materials and teaching resources for teaching the type of technique that can be implemented. After the application of the games. Finally, the teaching of sports climbing seeks to bring children to this sport through educational games and motivators to practice, thus ensuring the generation of energy for our entity. Keywords: Sport climbing, didactic games, motivation, recreation, mathematics, language, art

    Double or nothing: red flag symptoms of critical carotid stenosis, a case report

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    Abstract Background Detailed knowledge of every possible manifestation of Internal Carotid Artery (ICA) disease is important. For improving detection and a timely adoption of secondary prevention procedures or treatments. Transient oculomotor nerve palsies have been described associated with stenosis or occlusion of the ICA. Case presentation We described a patient that develop a sequential combination of transient monocular loss of vision followed by binocular diplopia secondary to an unstable atherosclerotic preocclusive stenosis of an internal carotid artery previously treated with radiotherapy. Conclusions The peculiar sequence of transient monocular vision that give rise later into a transient binocular diplopia (double or nothing) should be kept in mind as a possible manifestation of critical stenosis of ICA

    Stroke etiologies in patients with COVID-19: the SVIN COVID-19 multinational registry

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    Background and purpose: Coronavirus disease 2019 (COVID-19) is associated with a small but clinically significant risk of stroke, the cause of which is frequently cryptogenic. In a large multinational cohort of consecutive COVID-19 patients with stroke, we evaluated clinical predictors of cryptogenic stroke, short-term functional outcomes and inhospital mortality among patients according to stroke etiology. Methods: We explored clinical characteristics and short-term outcomes of consecutively evaluated patients 18 years of age or older with acute ischemic stroke (AIS) and laboratory-confirmed COVID-19 from 31 hospitals in 4 countries (3/1/20–6/16/20). Results:Of the 14.483 laboratory-confirmed patients with COVID-19, 156 (1.1%) were diagnosed with AIS. Sixty-one (39.4%) were female, 84 (67.2%) white, and 88 (61.5%) were between 60 and 79 years of age. The most frequently reported etiology of AIS was cryptogenic (55/129, 42.6%), which was associated with significantly higher white blood cell count, c-reactive protein, and D-dimer levels than non-cryptogenic AIS patients (p Conclusions: Our findings suggest that cryptogenic stroke among COVID-19 patients carries a significant risk of early mortality
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