539 research outputs found

    Mathematical modeling of reaction mechanism of formation of photochemical smog by applying the semi-implicit method

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    To simulate the different mechanisms we considered a reactor of constant temperature and volume, where the only reactions that are carried out are those with reported kinetic constants [1]. For example, to simulate the formaldehyde kinetic you make a serial of seven chemical reactions where intervene nine chemical species [2].The change in concentration with respect to the time of one specie is mathematically represented by means of an ordinary differential equation. In the studied cases, the mechanism of reaction can be represented as a system of nonlinear ordinary differential equations. In the simulation of the mechanism of reaction, the medullar part is the solution of all the ordinary differential equation that describe the temporary evolution of the concentration of each the species. The differential equation that comes from the kinetic present what it is called rigidity, principally due to the simultaneous presence of radical with called rigidity, principally due to the simultaneous presence of radicals with a really short life time as the presence of hydroperoxide HO2• and species that remain almost constant as the oxygen. The main problem to carry out the precise integration of the differential equation system that represents the mechanism of reaction of the atmospheric chemistry, is the wide when variation of the kinetic constant as it appears in the reactions 2 and 7 which brings as a consequence the instability when applying an explicit numerical method because for any change in so different scales. When this happens, it is said that the differential equation system is rigid. In order to solve the problem that the rigidity of a differential equation system represented we should use special numerical method that ensures precision and stability in its integration. To achieve this whit a classical explicit method it is required a lot of computing time, besides the possible instability. When using the semi implicit method, we developed a computer package using language C++ to solve the system of nonlinear ordinary differential equation. Solving the matrix system with the method mentioned above, it is found the numerical value of the concentration of the five chemical species for every time step, given the initial concentration. The computer program used to solve the system of differential equation was developed in UNAM

    Metabolic response to water shortage in an isolated feral sheep population

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    To establish metabolic responses for biochemical analytes related to freshwater shortage adaptation, a total of 376 blood samples were collected from feral sheep at the Socorro Island, Revillagigedo Archipelago. Comparisons were made between four sampling periods with repeated measurements at 0, 7, 14, and 21 d (94 blood serums: 84 females and 10 males). During the first week, the sheep received daily water ad libitum. During the second and third week, the sheep received 60% daily water in relation to the first 7 days intake. Analysis of variance was used to compare the mean values between sampling days. Stepwise regression analysis was used to evaluate the relationships between the biochemical analytes. The glucose (GLU), total cholesterol (COL-T), triglycerides (TAG), urea, albumin (ALB), total protein (PROT-T), sodium ion (Na+), creatine kinase (CK), arginine vasopressin (AVP), and aldosterone (Aldo), were determined. With the exception of GLU, the COL-T, TAG, urea, ALB, PROT-T, Na+, CK, AVP, and Aldo showed differences between sampling days with the higher values corresponding to 14 d with limited water intake. Negative correlations (P<0.05) between ALB with COL-T and TAG, were quantified. Positive correlations (P<0.05) between COL-T with TAG, and Aldo; between urea with PROT-T, between CK with ALB and PROT-T, between AVP with COL-T, TAG, urea, PROT-T and Aldo, and between Aldo with Na+, were quantified. Results could help improve the accuracy of metabolic profiles used as a tool for evaluating dehydration indicators and to describe the physiological mechanisms employed by feral sheep to cope with limited availability of freshwater

    Assisted surface redesign by perturbing its point cloud representation

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    [Abstract] This research study explores the use of point clouds for design geometrically complex surfaces based on genetic morphogenesis. To this end, a point-based genetic algorithm and the use of massive unstructured point clouds are proposed as a manipulation method of complex geometries. The intent of the algorithm is to improve the design experience, thus different solutions can be presented to designers. The main objective of this work is to provide examples to be adopted as user own or to help them in the creative process. This is not about providing them with a tool to ‘do’ the designer's creative work, but using it as a creative tool in which the user retains control of it. The powerfulness of this approach relies on the fact that the user can use any/diverse criteria (objective or subjective) to evaluate the individuals proposed as possible solutions. As part of this study, the convergence of the algorithm and the ability of diversity in the final populations of the search process will be demonstrated. Various examples of the use of the algorithm are displayed

    Assisted surface redesign by perturbing its point cloud representation

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    [Abstract] This research study explores the use of point clouds for design geometrically complex surfaces based on genetic morphogenesis. To this end, a point-based genetic algorithm and the use of massive unstructured point clouds are proposed as a manipulation method of complex geometries. The intent of the algorithm is to improve the design experience, thus different solutions can be presented to designers. The main objective of this work is to provide examples to be adopted as user own or to help them in the creative process. This is not about providing them with a tool to ‘do’ the designer's creative work, but using it as a creative tool in which the user retains control of it. The powerfulness of this approach relies on the fact that the user can use any/diverse criteria (objective or subjective) to evaluate the individuals proposed as possible solutions. As part of this study, the convergence of the algorithm and the ability of diversity in the final populations of the search process will be demonstrated. Various examples of the use of the algorithm are displayed

    Predicting vertical urban growth using genetic evolutionary algorithms in Tokyo’s minato ward

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    [Abstract] This article explores the use of evolutionary genetic algorithms to predict scenarios of urban vertical growth in large urban centers. Tokyo’s Minato Ward is used as a case study because it has been one of the fastest growing skylines over the last 20 years. This study uses a genetic algorithm that simulates the vertical urban growth of Minato Ward to make predictions from pre-established inputted parameters. The algorithm estimates not only the number of future high-rise buildings but also the specific areas in the ward that are more likely to accommodate new high-rise developments in the future. The evolutionary model results are compared with ongoing high-rise developments in order to evaluate the accuracy of the genetic algorithm in simulating future vertical urban growth. The results of this study show that the use of genetic evolutionary computation is a promising way to predict scenarios of vertical urban growth in terms of location as well as the number of future buildings

    Expansion model for the external envelopes of the SN 1987A

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    Assuming the existence of a polarization produced by Thompson scattering, as suggested by the observations, a model has been computed for the optically thin layers of SN 1987A. Supposing that the isodensities in this region are oblate ellipsoids, we found the equation that describes the observable polarization as a function of its parameters. If we assumed that the inclination of the axis of symmetry and the eccentricity of the envelope are constant and using a model for the mass ejection, we were able to study the evolution of the size and density of the region as a function of time.Asociación Argentina de Astronomí

    ATIPICIDADES EN UN CASO CON DISPLASIA ARRITMOGÉNICA DEL VENTRÍCULO DERECHO O ENFERMEDAD DE UHL / Report of an atypical case with arrhythmogenic right ventricular dysplasia or Uhl´s anomaly

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    ResumenLa displasia arritmogénica del ventrículo derecho es una miocardiopatía caracterizada por arritmias ventriculares malignas y anomalías estructurales progresivas, que afectan primariamente al ventrículo derecho. Se presenta por una sustitución progresiva parcial o masiva del miocardio por tejido adiposo o fibroadiposo. La enfermedad de Uhl puede ser una manifestación extrema y generalizada de la displasia arritmogénica del ventrículo derecho, trastorno congénito muy poco frecuente con ausencia de miocardio ventricular derecho, por lo que sus paredes son delgadas como el papel. Se comenta el caso de un paciente masculino de 56 años que presentó pérdida de conocimiento y se le realizó el diagnóstico clínico y ecocardiográfico. Se discuten las características clínicas, el diagnóstico y la conducta a seguir ante esta cardiopatía potencialmente letal en pacientes que sufren síncope, taquicardia ventricular o parada cardíaca. / AbstractArrhythmogenic right ventricular dysplasia is a cardiomyopathy characterized by malignant ventricular arrhythmias and progressive structural abnormalities, affecting primarily the right ventricle. It appears due to a partial or massive progressive replacement of the myocardium by fibroadipose or adipose tissue. Uhl's disease may be an extreme and widespread manifestation of arrhythmogenic right ventricular dysplasia, a rare congenital disorder with absence of right ventricular myocardium, so that its walls are paper thin. The case of a 56 year old male patient who had loss of consciousness and underwent clinical and echocardiographic diagnosis is presented. The clinical features, diagnosis and action to take against this potentially fatal heart disease in patients with syncope, ventricular tachycardia or cardiac arrest are discussed

    Identification of non-tuberculous mycobacteria isolated from opossum (Didelphis virginiana) lymph nodes and characterisation of lesions

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    The aim of this study was to investigate the presence of NTM in the lymph nodes of opossums (D. virginiana) and to characterise the microscopic changes in affected tissue. Retropharyngeal and tracheobronchial lymph nodes were collected postmortem from 18 opossums in the state of Colima, Mexico in 2013. The lymph nodes were also cultured for mycobacterial organisms and processed for histopathological examination. Bacteriological cultures yielded 5/18X100 (28%) isolates of NTM, which were subsequently identified as M. terrae, M. szulgai, M. gastri and M. asiaticum. Microscopic examination of the affected nodes revealed a necrotic granulomatous lymphadenitis (3/60%) composed of histiocytes, epithelioid cells and giant cells with intralesional alcoholresistant acid bacteria. An association between the sex of the opossum and the presence of NTM was observed. To our knowledge, this is the first report of NTM isolation in opossums with granulomatous lymphadenitis in Mexico

    Diffuse reflectance optical topography: location of inclusions in 3D and detectability limits

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    In the present contribution we investigate the images of CW diffusely reflected light for a point-like source, registered by a CCD camera imaging a turbid medium containing an absorbing lesion. We show that detection of μa variations (absorption anomalies) is achieved if images are normalized to background intensity. A theoretical analysis based on the diffusion approximation is presented to investigate the sensitivity and the limitations of our proposal and a novel procedure to find the location of the inclusions in 3D is given and tested. An analysis of the noise and its influence on the detection capabilities of our proposal is provided. Experimental results on phantoms are also given, supporting the proposed approach.Fil: Carbone, Nicolás Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Baez, Guido Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: García, Héctor Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Waks Serra, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Di Rocco, Hector Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Iriarte, Daniela Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Pomarico, Juan Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; ArgentinaFil: Grosenick, D.. Physikalisch-Technische Bundesanstalt; AlemaniaFil: Macdonald, R.. Physikalisch-Technische Bundesanstalt; Alemani
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