1,761 research outputs found

    Morphofunctional correlations in the experimental study of myocardiopathies under the stress of forced restraint. Note 2: The influence of adrenal imbalance

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    Tests were performed with 70 rats to determine the effects of restraint on the functions and structure of the myocardium under varying conditions of adrenal imbalance. Results showed that in rats with adrenal imbalance, fasting and restraint produced the same biochemical alterations as in the controls. The morphologic alteractions, as well as their electric expression, were more varied and evident in the animals with adrenal imbalance. Persistence of the microscopic and electrocardiographic alterations after 72 hours restraint in the animals subjected to unilateral adrenalectomy suggests chronic evolution of the myocardial lesions. This proves the necessity of intact adrenals for a good adaptability to stress

    Simulation of guard ring influence on the performance of ATLAS pixel detectors for inner layer replacement

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    Electric field magnitude and depletion in the bulk of silicon pixel detectors, which influence its breakdown behaviour, was studied using finite-element method to solve the drift-diffusion equation coupled to Poisson's equation in a simplified two dimensional model of the ATLAS pixel sensor. Based on this model, the number of guard rings and dead edges width were modified to investigate their influence on the detector's depletion at the edge and on its internal electrical field distribution. Final ly, the 3 level model was implemented into the simulation to study the behaviour of such detector under different level of irradiation

    An Efficient Rank Based Approach for Closest String and Closest Substring

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    This paper aims to present a new genetic approach that uses rank distance for solving two known NP-hard problems, and to compare rank distance with other distance measures for strings. The two NP-hard problems we are trying to solve are closest string and closest substring. For each problem we build a genetic algorithm and we describe the genetic operations involved. Both genetic algorithms use a fitness function based on rank distance. We compare our algorithms with other genetic algorithms that use different distance measures, such as Hamming distance or Levenshtein distance, on real DNA sequences. Our experiments show that the genetic algorithms based on rank distance have the best results

    THE INFLUENCE OF FOLIAR FERTILIZATION WITH HUMIC ACIDS ON THE PRODUCTION OF WHITE CABBAGE

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    The main purpose of the study was to test the effect of some fertilizers based on humic acids on autumn cabbage,Bucharest F1 in the ecological conditions of the South-West of Romania. The foliar products applied were formulated and obtained by ICPA Bucharest. The biological material was represented by the Bucharest F1 hybrid. The experience included three variants: V1-untreated, V2-foliar fertilization with Deceneu and V3 foliar fertilization with Humifert Plus. In order to achieve the proposed objectives, biometric determinations have been carried out on the eatable organs: height and diameter of the head, the shape index and the degree of stuffi,but also the quantity and quality of the cabbage production. Application of fertilizers led to increased production at the fertilized variants, significant differences were at the variant with the Deceneu product, 132.5 kg/ha and a good accumulation of ascorbic acid, 35.78 mg/100g fresh matter, when applying Humifert Plu

    Molecular architecture of softwood revealed by solid-state NMR

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    Economically important softwood from conifers is mainly composed of the polysaccharides cellulose, galactoglucomannan and xylan, and the phenolic polymer, lignin. The interactions between these polymers lead to wood mechanical strength and must be overcome in biorefining. Here, we use 13C multidimensional solid-state NMR to analyse the polymer interactions in never-dried cell walls of the softwood, spruce. In contrast to some earlier softwood cell wall models, most of the xylan binds to cellulose in the two-fold screw conformation. Moreover, galactoglucomannan alters its conformation by intimately binding to the surface of cellulose microfibrils in a semi-crystalline fashion. Some galactoglucomannan and xylan bind to the same cellulose microfibrils, and lignin is associated with both of these cellulose-bound polysaccharides. We propose a model of softwood molecular architecture which explains the origin of the different cellulose environments observed in the NMR experiments. Our model will assist strategies for improving wood usage in a sustainable bioeconomy

    Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source

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    We report radiation hardness tests performed at the Frascati Neutron Generator on silicon Photo-Multipliers, semiconductor photon detectors built from a square matrix of avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to 7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been recorded during the neutron irradiation and a gradual deterioration of their properties was found to happen already after an integrated fluence of the order of 10^8 1-MeV-equivalent neutrons per cm^2.Comment: 7 pages, 6 figures, Submitted to Nucl. Inst. Meth.

    Photon polarization in light-by-light scattering: Finite size effects

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    We derive a simple expression for the photon helicity and polarization-flip probabilities in arbitrary background fields, in the low-energy regime. Taking the background to model a focused laser beam, we study the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence. We find that models which do not account for pulse duration can overestimate all signals in near head-on collisions by up to an order of magnitude. Taking pulse duration into account, the flip probability becomes relatively insensitive to both angular incidence and the fine details of the pulse structure
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