4,019 research outputs found

    High Resolution Spectrometry of Leaf and Canopy Chemistry for Biochemical Cycling

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    High-resolution laboratory spectrophotometer and Airborne Imaging Spectrometer (AIS) data were used to analyze forest leaf and canopy chemistry. Fundamental stretching frequencies of organic bonds in the visible, near infrared and short-wave infrared are indicative of concentrations and total content of nitrogen, phosphorous, starch and sugar. Laboratory spectrophotometer measurements showed very strong negative correlations with nitrogen (measured using wet chemistry) in the visible wavelengths. Strong correlations with green wet canopy weight in the atmospheric water absorption windows were observed in the AIS data. A fairly strong negative correlation between the AIS data at 1500 nm and total nitrogen and nitrogen concentration was evident. This relationship corresponds very closely to protein absorption features near 1500 nm

    Studies on the clinical significance of nonesterified and total cholesterol in urine

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    Gas-liquid chromatographic determinations of nonesterified and total urinary cholesterol were performed in 137 normals, 264 patients with various internal diseases without evidence of neoplasias or diseases of the kidney or urinary tract, 497 patients with malignancies and 236 patients with diseases of the kidney, urinary tract infections or prostatic adenoma with residual urine. A normal range (mean±2 SD) of 0.2–2.2 mg/24 hours nonesterified cholesterol (NEC) and of 0.3–3.0 mg/24 hours total cholesterol (TC) was calculated. Values of urinary cholesterol excretion were independent of age and sex and did not correlate with cholesterol levels in plasma. Patients with various internal diseases, without evidence of neoplasias nor diseases of the kidney or obstruction of the urinary tract, showed normal urinary cholesterol excretions, as did patients with infections of the urinary tract. However, elevated urinary cholesterol was found in patients with diseases of the kidney or urinary tract obstruction (prostatic adenoma with residual urine), malignant diseases of the urogenital tract and metastasing carcinoma of the breast. In patients with other malignant diseases urinary cholesterol was usually normal. Lesions of the urothelial cell membranes are considered to be the most likely cause of urinary cholesterol hyperexcretion. The clinical value of urinary cholesterol determinations as a possible screening test for urogenital carcinomas in unselected populations is limited by lacking specificity, expensive methodology and low prevalence of the mentioned carcinomas, although elevated urinary cholesterol excretions have been observed in early clinical stages of urogenital cancers

    K VALUES OF THE SOILS OF PUERTO RICO

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    K VALUES OF THE SOILS OF PUERTO RIC

    Phase diagram study of a two-dimensional frustrated antiferromagnet via unsupervised machine learning

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    We apply unsupervised learning techniques to classify the different phases of the J1J2J_1-J_2 antiferromagnetic Ising model on the honeycomb lattice. We construct the phase diagram of the system using convolutional autoencoders. These neural networks can detect phase transitions in the system via `anomaly detection', without the need for any label or a priori knowledge of the phases. We present different ways of training these autoencoders and we evaluate them to discriminate between distinct magnetic phases. In this process, we highlight the case of high temperature or even random training data. Finally, we analyze the capability of the autoencoder to detect the ground state degeneracy through the reconstruction error.Comment: 11 pages, 15 figure

    Adjuvants : an essential component of neisseria vaccines

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    Adjuvants may be classified into delivery systems and immune potentiator or modulator molecules based on their mechanism of action. Neisseria vaccines containing traditional adjuvants such as aluminium salts have existed for long time, but meningitis caused by Neisseria meningitidis serogroups, particularly serogroup B, continues to be a global health problem. Novel strategies have applied in silico and recombinant technologies to develop "universal" antigens (e.g. proteins, peptides and plasmid DNA) for vaccines, but these antigens have been shown to be poorly immunogenic even when alum adjuvanted, implying a need for better vaccine design. In this work we review the use of natural, detoxified, or synthetic molecules in combination with antigens to activate the innate immune system and to modulate the adaptive immune responses. In the main, antigenic and imune potentiator signals are delivered using nano-, micro-particles, alum, or emulsions. The importance of interaction between adjuvants and antigens to activate and target dendritic cells, the bridge between the innate and adaptive immune systems, will be discussed. In addition, nasal vaccine strategies based on the development of mucosal adjuvants and Neisseria derivatives to eliminate the pathogen at the site of infection provide promising adjuvants effective not only against respiratory pathogens, but also against pathogens responsible for enteric and sexually transmitted diseases

    Régimen de Ventanilla Única de Comercio Exterior y su impacto en el Sector Agrario

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    El atractivo perfil exportador que posee Argentina, gracias a su extensión geográfica, variedad de climas, y amplia oferta en recursos naturales no siempre es acompañado por la eficiencia en la gestión de trámites implicados en la logística. Una de las herramientas del Acuerdo de Facilitación del Comercio Internacional, es el Régimen de Ventanilla Única del Comercio Exterior. Por medio del cual, la documentación se presenta en un solo punto de entrada, simplificando el procedimiento de la exportación. El objetivo de este trabajo es profundizar sobre el impacto del Régimen V.U.C.E.A en las pymes del Sector Agrario. Por lo cual se ha realizado un relevamiento bibliográfico en fuentes nacionales e internacionales, proyectos, acuerdos y leyes relacionas al Sistema de Ventanilla Única y Facilitación Comercial. Nuestra investigación nos indica que las innovaciones tecnológicas que el Estado Nacional está desarrollando en función del Acuerdo de Facilitación del Comercio, permitirán al Sector Agrario expandir sus exportaciones, con alto valor agregado y libre de trabas. La implementación de la Ventanilla Única de Comercio Exterior será de manera gradual y paulatina. En la actualidad, ya se encuentra en marcha el Tablero V.U.C.E, plataforma digital, a través del cual el empresario gestiona y realiza un seguimiento de los trámites y requisitos que deba cumplir previo a exportar. Nuestra conclusión está orientada a marcar la vacancia de un Plan de Gestión Administrativa, cuyo propósito consiste en generar un contexto de aprendizaje y capacitación dentro del sector que acompañe aquellas empresas agrarias que deseen internacionalizarse, en función de sus debilidades y fortalezas. Pensamos que sería importante reflexionar sobre el uso de la herramienta en las empresas agropecuarias y su potencial para modificar la actual cadena comercial de productos exportables

    Drought-stress-induced up-regulation of CAM in seedlings of a tropical cactus, Opuntia elatior, operating predominantly in the C3 mode

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    Immediately after unfolding, cotyledons of the tropical platyopuntoid cactus, Opuntia elatior Mill., exhibited a C3-type diel CO2 exchange pattern characterized by net CO2 uptake in the light. Significant nocturnal increases in titratable acidity typical of crassulacean acid metabolism (CAM) were not detected at this early developmental stage. As cotyledons matured and the first cladode (flattened stem) developed, features of CAM were observed and the magnitude of CAM increased. Nonetheless, in well-watered seedlings up to 10 cm tall, C3 photosynthetic CO2 fixation in the light remained the major pathway of carbon fixation. Reduced soil water availability led to an up-regulation of net dark CO2 fixation and greater nocturnal increases in tissue acidity, consistent with facultative CAM. These observations demonstrate that C3 photosynthesis, drought-stress-related facultative CAM, and developmentally controlled constitutive CAM can all contribute to the early growth of O. elatior. The strong C3 component and facultative CAM features expressed in young O. elatior contrast with mature plants in which obligate CAM is the major pathway of carbon acquisition
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