2,078 research outputs found

    Theoretical design proposal for simulated hot asphalt mixture at a temperature below zero degrees Celsius

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    In the world there are adverse climates, climates that hinder the good construction and paving of roads, generating insecurity among the locals and visitors. This over time affects the economy of a country, as a road boosts tourism, transport and commerce. Therefore, a mixture was designed to mitigate a problem in the placement of hot asphalt mixture at temperatures below zero degrees Celsius. That is, a conventional mix design was proposed, but with different types of filler (lime, Portland cement type I and silica) tested with the Marshall and Lottman method which are governed according to the EG-2013 standards [1] and parameters established in the Asphalt Institute [2]. To find the optimum, it was tested with 5.0%, 5.5% 6.0% and 6.5% asphalt cement. Then with the results obtained a comparative analysis was performed. Finally, specimens without any additives were made, the specimens once prepared at 140°C were subjected to freezing, resulting in the three types of filler, that the hot asphalt mixture with incorporation of Portland cement type I to a 5, 90% of asphalt cement is the optimum since, subject to extreme temperatures below 0°C they comply with the parameters required in the standards

    Spin effects in strong-field laser-electron interactions

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    The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.Comment: 9 pages, 6 figure

    Supermetric search with the four-point property

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    Metric indexing research is concerned with the efficient evaluation of queries in metric spaces. In general, a large space of objects is arranged in such a way that, when a further object is presented as a query, those objects most similar to the query can be efficiently found. Most such mechanisms rely upon the triangle inequality property of the metric governing the space. The triangle inequality property is equivalent to a finite embedding property, which states that any three points of the space can be isometrically embedded in two-dimensional Euclidean space. In this paper, we examine a class of semimetric space which is finitely 4-embeddable in three-dimensional Euclidean space. In mathematics this property has been extensively studied and is generally known as the four-point property. All spaces with the four-point property are metric spaces, but they also have some stronger geometric guarantees. We coin the term supermetric space as, in terms of metric search, they are significantly more tractable. We show some stronger geometric guarantees deriving from the four-point property which can be used in indexing to great effect, and show results for two of the SISAP benchmark searches that are substantially better than any previously published

    Reference point hyperplane trees

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    Our context of interest is tree-structured exact search in metric spaces. We make the simple observation that, the deeper a data item is within the tree, the higher the probability of that item being excluded from a search. Assuming a fixed and independent probability p of any subtree being excluded at query time, the probability of an individual data item being accessed is (1−p)d for a node at depth d. In a balanced binary tree half of the data will be at the maximum depth of the tree so this effect should be significant and observable. We test this hypothesis with two experiments on partition trees. First, we force a balance by adjusting the partition/exclusion criteria, and compare this with unbalanced trees where the mean data depth is greater. Second, we compare a generic hyperplane tree with a monotone hyperplane tree, where also the mean depth is greater. In both cases the tree with the greater mean data depth performs better in high-dimensional spaces. We then experiment with increasing the mean depth of nodes by using a small, fixed set of reference points to make exclusion decisions over the whole tree, so that almost all of the data resides at the maximum depth. Again this can be seen to reduce the overall cost of indexing. Furthermore, we observe that having already calculated reference point distances for all data, a final filtering can be applied if the distance table is retained. This reduces further the number of distance calculations required, whilst retaining scalability. The final structure can in fact be viewed as a hybrid between a generic hyperplane tree and a LAESA search structure

    Comportamiento clínico, epidemiológico y uso de suero antiofídico BIOL, en el manejo de accidentes ofídico en hospitales de Chontales, Rio San Juan, Matagalpa y Jinotega, en el período de Enero a Agosto de 2013

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    Las mordeduras por serpientes constituyen algunas de las urgencias más importantes que se atienden en las unidades de salud de Nicaragua, el tratamiento clave para este tipo de lesiones es el suero antiofídico. Existen dos familias venenosas de serpientes, elapidaes o corales manejadas con suero anticoral, y familia Viperidaes tratadas con suero polivalente. El suero utilizado para Viperidaes tradicionalmente ha sido el suero del Instituto de Clodomiro Picado, pero recientemente se ha incluido un nuevo suero polivalente (BIOL) para el manejo de los mismos. Con el objetivo de determinar el comportamiento clínico, epidemiológico y uso del suero BIOL en mejorar el cuadro clínico, se realizó un estudio descriptivo de corte transversal, donde se analizaron datos recolectados de los expedientes clínicos de 70 pacientes, con antecedentes de accidentes ofídicos en los departamentos de Matagalpa, Jinotega, Chontales y Río San Juan, entre enero y agosto de 2013. La tasa de incidencia fue de 5.5 casos por 100,000 habitantes, con predominio en el sexo masculino (73%), en edades comprendidas entre 10 y 49 años(62%), realizaban en su mayoría labores agrícolas (32.8%). El género Bothrops asper fue el responsable del 71.4% de los casos. Del total de pacientes lesionados, el 71.4 % acudió por atención a los puestos y centros de salud de su comunidad o municipio, y a un 86 % de estos les fue suministrado suero antiveneno. Los cuadros clínicos más frecuentes al momento del ingreso al hospital fueron edema y dolor en la extremidad. A 38 pacientes se les suministró suero BIOL-CLB, 22 se clasificaron como envenenamiento leve (57.8 %), 12 pacientes en la categoría de envenenamiento moderado (31.6%) y 4 pacientes (10.5 %) en cuadro de envenenamiento severo. Una vez aplicado el suero hubo mejoría en los síntomas y en las determinaciones de laboratorio, además solamente 3 de 38 pacientes sufrieron algún tipo de reacción al suero, prurito generalizado y aumento de calo

    Coevolution of agents and networks: Opinion spreading and community disconnection

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    We study a stochastic model for the coevolution of a process of opinion formation in a population of agents and the network which underlies their interaction. Interaction links can break when agents fail to reach an opinion agreement. The structure of the network and the distribution of opinions over the population evolve towards a state where the population is divided into disconnected communities whose agents share the same opinion. The statistical properties of this final state vary considerably as the model parameters are changed. Community sizes and their internal connectivity are the quantities used to characterize such variations.Comment: To appear in Phys. Lett.

    Urbanise in roman times: rituality and practicality. Proposal for an approved execution procedure

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    En época romana la orientación conferida a las construcciones solía tener significados simbólicos, reflejos de una ritualidad, especialmente en el caso de ciudades o santua - rios. Aunque también podía responder simplemente a cuestio - nes de tipo práctico. En cualquier caso, el beneplácito de los dioses era condición sine qua non para iniciar la obra y dibu - jar sobre el terreno el diseño de la misma. Frente a la cuestión de su significado, se plantea una pregunta: ¿cuál fue el proce - dimiento de ejecución? En publicaciones precedentes, nues - tra propuesta iba encaminada a identificar sistemas utiliza - dos para conferir a las obras una orientación determinada. En este artículo planteamos un modelo de operar que va en para - lelo con las interpretaciones dadas a las orientaciones, ya sean simbólicas o prácticas, proponiendo como modo de ejecución el explicado por Nypsius en el siglo I d.C. al describir la téc - nica de la varatio.In Roman times, the orientation given to the build - ings usually had symbolic meanings, reflection of a ritual, es - pecially in the case of cities or sanctuaries, although the ori - entation could also simply respond to practical issues. In any case, the gods’ support was essential for the beginning of the works, and the drawing of the design on the ground. Besides the topic of the meaning of the orientations, another question arises: what was the procedure? In previous publications, our proposal was intended to identify the systems used to give the works a certain orientation. In this paper we propose im - plementation rules which run parallel with the symbolic or pragmatic interpretations of orientations, proposing as the ex - ecution procedure the one explained by Nypsius in the first century AD when he describes the technique of varatio
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