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Search Results: 1 - 10 of 10806 matches for " Diego; Améndola "
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Comparación de dos métodos de fraccionamiento físico de la materia orgánica del suelo
Irizar,Alicia; Andriulo,Adrián; Cosentino,Diego; Améndola,Catalina;
Ciencia del suelo , 2010,
Abstract: regression analysis was used to compare particulate organic carbon (cop) and light carbon (cs) concentrations obtained by size (fraction > 53 μm) and density fractionation (liquor density = 2 g cm-3) methods, respectively. the soil samples were taken from a long-term experiment located at the eea-inta pergamino comparing four cropping sequences and two tillage systems. both methods were linearly and positively correlated to depths of 0-5 and 5-10 cm and the y-intercept did not differ from zero, indicating that both methods resulted in a similar estimate for labile c. as the slopes did not different from unity, the differences between the two methods remained constant throughout all the labile range measured. there was no correlation for a depth of 10-20 cm, and cs concentrations were higher and less variable than those of cop. the liquor density used might explain the obtention of similar or greater amounts of cs than of cop because of the important contribution of the organomineral complex to the light fraction.
Comparación de dos métodos de fraccionamiento físico de la materia orgánica del suelo Comparison of two physical fractionation methods for soil organic matter
Alicia Irizar,Adrián Andriulo,Diego Cosentino,Catalina Améndola
Ciencia del Suelo , 2010,
Abstract: Se compararon las concentraciones de carbono orgánico particulado (COP) y carbono sobrenadante (Cs) obtenidas por los métodos de fraccionamiento granulométrico (fracción > 53 μm) y densimétrico (densidad de licor: 2 g cm-3), respectivamente, utilizando el análisis de regresión. Las muestras de suelo fueron tomadas de un ensayo de larga duración ubicado en la EEA-INTA Pergamino que compara cuatro secuencias de cultivo y dos sistemas de labranza. Los dos métodos estuvieron lineal y positivamente correlacionados para las profundidades 0-5 y 5-10 cm y las ordenadas al origen no difirieron de cero, indicando que ambos estimaron el carbono lábil de manera similar. Debido a que las pendientes no fueron distintas de uno, las diferencias entre los dos métodos fueron constantes en todo el rango de carbono lábil medido. Para la profundidad 10-20 cm, no hubo correlación y las concentraciones de Cs fueron superiores y menos variables que las de COP. La densidad del licor utilizada puede explicar la obtención de cantidades similares o superiores de Cs con respecto a COP, debido a una contribución importante del complejo órgano-mineral a la fracción sobrenadante. Regression analysis was used to compare particulate organic carbon (COP) and light carbon (Cs) concentrations obtained by size (fraction > 53 μm) and density fractionation (liquor density = 2 g cm-3) methods, respectively. The soil samples were taken from a long-term experiment located at the EEA-INTA Pergamino comparing four cropping sequences and two tillage systems. Both methods were linearly and positively correlated to depths of 0-5 and 5-10 cm and the y-intercept did not differ from zero, indicating that both methods resulted in a similar estimate for labile C. As the slopes did not different from unity, the differences between the two methods remained constant throughout all the labile range measured. There was no correlation for a depth of 10-20 cm, and Cs concentrations were higher and less variable than those of COP. The liquor density used might explain the obtention of similar or greater amounts of Cs than of COP because of the important contribution of the organomineral complex to the light fraction.
Maximum Likelihood Estimates for Gaussian Mixtures Are Transcendental
Carlos Améndola,Mathias Drton,Bernd Sturmfels
Mathematics , 2015,
Abstract: Gaussian mixture models are central to classical statistics, widely used in the information sciences, and have a rich mathematical structure. We examine their maximum likelihood estimates through the lens of algebraic statistics. The MLE is not an algebraic function of the data, so there is no notion of ML degree for these models. The critical points of the likelihood function are transcendental, and there is no bound on their number, even for mixtures of two univariate Gaussians.
Introducción de cultivos de cobertura en la rotación soja-maíz: efecto sobre algunas propiedades del suelo
Restovich,Silvina Beatriz; Andriulo,Adrián Enrique; Améndola,Catalina;
Ciencia del suelo , 2011,
Abstract: silt loam soils of the rolling pampas cultivated with soybean and, secondarily, corn under no-tillage (nt) show a progressive decline in their physical and chemical fertility. the inclusion of cover crops (cc) in these agricultural systems could help mitigate these types of degradation. the objectives of this study were: 1) to evaluate the effect of different cc on some soil properties (porosity distribution, structural stability, bulk density, soil organic carbon (soc) and labile carbon) and 2) to analyze the evolution of these properties during the inclusion of cc in a soybean-corn rotation under nt. in 2005, a two-year study was carried out on a silt loam typic argiudoll using different winter species as cc: barley (hordeum vulgare l.), ryegrass (lolium multiflorum l.), oats (avena sativa l.), rescue grass (brumus unioloides l.), vetch (vicia sativa l.), rape seed (brassica napus l.) and forage radish (raphanus sativus l.), a mixture of vetch and oats, and a control without cc. we measured an increase in soil macroporosity and structural stability and an increase in soc content and the labile fraction. these changes were of moderate to low magnitude, occurring mainly near the soil surface (0-5 cm); they were associated with moments of important residue contributions and disappeared in periods of heavy rain. the rotations that included cc accumulated more soc. forage radish outstanded as a generator of porosity and oats as a stabilizer of the porous system.
Prototipo compactador de forraje
Cruz Meza,Pedro; Améndola Massiotti,Ricardo D;
Revista Ciencias T??cnicas Agropecuarias , 2011,
Abstract: one of the most troubles about the cattle farming in méxico country is the shortage of fodder in the drought season. the preservation of fodder is the solution for that problem. for this objective, the department of agricultural mechanical engineering of the chapingo autonomous university, developed and build a prototype to compact the fodder chopped previously. the mechanism consist in a cylinder that turn in 7 rev/min into a cylindrical steel container, the layers in order to compact are of 15 centimeters of thickness, once the material was compacted, the container is opened by the side, loosen the screws. then the compacted fodder is wrapped in plastic material. the cylinder go up and go down though a block and tackle. it takes two people to operate the equipment. the capacity of equipment is 4,26 m3/h (3,2 t/h).
Moment Varieties of Gaussian Mixtures
Carlos Améndola,Jean-Charles Faugère,Bernd Sturmfels
Statistics , 2015,
Abstract: The points of a moment variety are the vectors of all moments up to some order of a family of probability distributions. We study this variety for mixtures of Gaussians. Following up on Pearson's classical work from 1894, we apply current tools from computational algebra to recover the parameters from the moments. Our moment varieties extend objects familiar to algebraic geometers. For instance, the secant varieties of Veronese varieties are the loci obtained by setting all covariance matrices to zero. We compute the ideals of the 5-dimensional moment varieties representing mixtures of two univariate Gaussians, and we offer a comparison to the maximum likelihood approach.
Morphometric Analysis on Shape Transition during Growth of the Red Snapper (Lutjanus campechanus, Poey, 1860)  [PDF]
Elvia Teresa Mendoza-Barrera, María Eugenia Vega-Cendejas, Monica Améndola-Pimenta, Rossanna Rodríguez-Canul
Open Journal of Marine Science (OJMS) , 2018, DOI: 10.4236/ojms.2018.84023
Abstract:
The red snapper Lutjanus campechanus (Poey, 1860) has a high commercial value that sustains an important fishery in Mexico. In this study, the patterns in morphological variations from early juvenile to adult stages were assessed by geometric methods (GM) in 194 organisms. Changes in shape were more evident and rapid in the early juvenile stage and decreased during adulthood. The principal components analysis of shape (Relative Warp Analysis, or RWA) identified size and body depth as the main sources of variance associated to both juvenile and adult organisms. The outline of the head and the tail showed the most noticeable differences following the ontogenic pathway visualized by thin-plate splines indicating that the ontogenetic pathway of the upper half and the lower half of the dorsal head profile (DHP) are in relatively opposite directions than those from the tail that bends ventrally. The Two-Block Partial Least Square analysis (2B-PLS) and their CR coefficients showed that the two modules had a moderate linear trend (p = 0.001). Although the blocks have morphological changes at different rates, there is a moderate synchrony in growth by modules. This study is the first to report the use of geometrical morphometry in L. campechanus in Mexico.
El desarrollo nuclear pacífico y las “3 S” (‘safety’, ‘security’ y ‘safeguards’)
González Améndola,Abel Julio; González Villa,Martín Abel;
Nucleus , 2010,
Abstract: abstract we should agree on a comprehensive solution for a commensurate international control of both nuclear and radioactive material designed to ensure that peaceful nuclear development will not cause harm to the human race. the concept international security system is clouded by the confusing semantics of its parts: the english concepts ‘safeguards’, ‘safety’ and ‘security’, on one hand, and nuclear and radioactive materials on the other hand. the objectives should be: to ensure, through appropriate safeguards, that nuclear materials are not diverted to non-peaceful purposes; to prevent, through appropriate security, the unauthorized possession or use, illegal or malicious, of nuclear and radioactive materials; and, to ensure, through appropriate safety, that the use of nuclear and radioactive material will not cause harm to people and the environment. security must be understood as an integral part of safeguards and safety, because materials that are secure are not necessarily safeguarded or safe, and materials may not be safeguarded or safe unless they are secure. security is a necessary but not sufficient condition for safeguards and safety; security is an important but subsidiary condition of safeguards and safety; security is necessary but not sufficient to ensure nuclear control via safeguards and safety. in conclusion an international treaty for the control (‘safeguards’, ‘safety’ and ‘security’) of the peaceful development of nuclear energy and its byproducts is proposed. it should clearly regulate the obligations and (non-compliance) penalties of the parties, and, based on existing agreements, should be clear, logical, rational, fundamental, methodical, systematic, universal, equitable, impartial, fair and non discriminatory.
Insuficiencia renal secundaria a litiasis urinaria en ni?os
Medina-Escobedo, C. Martha;León-Burgos, Verónica;Duarte y Amándola, Antonio;Salha Villanueva, Jorge;
Boletín médico del Hospital Infantil de México , 2006,
Abstract: introduction. because urolithiasis (ul) in an endemic disease in the yucatan peninsula, we carried out a prospective to study over a 5 year period to determine the prevalence, clinical course and metabolic disturbances of renal failure (rf) secondary to ul in children admitted to our institution. material and methods. patients 15 years old and younger, diagnosed with rf, and hospitalized from march 2001 to february 2006, were prospectively examined. cases associated to ul were selected. age, sex, hospitalization conditions, litho locus, medical and surgical treatment, complications, and evolution, were registered. metabolic tests were performed in those in whom rf reverted, posterior to the recovery of renal function. results. one hundred four patients with rf were detected; 13 cases (8 females and 5 males) had rf and ul. age was between 8 months and 12 years old and 10 patients were registered to be less than 3 years old. anuria was the principal clinical data. every case had multiple stones. some undernourishment degree was diagnosed in 10 patients. hypouricemia and hypouricosuria were present in one case whereas hyperuricosuria and hypercalciuria were present in another; hyperuricosuria was found in 8 cases and the metabolic cause for ul in 3 cases could not be identified. dialysis was required in 2 cases and nephrostomy probes were used in 2 more cases. all cases needed lithotomy. a satisfactory evolution was achieved in 10 patients and chronic rf developed in 2; one patient died due to urosepsis after few hours of been hospitalized in the emergency room. conclusions. rf in children can be caused by ul and in some cases irreversible damage and even death can occur. hyperuricosuria was the predominant metabolic alteration.
Análisis de la eficacia de agentes químicos de desinfección en materiales elastoméricos
Rogéli Tibúrcio Ribeiro da Cunha Peixoto,Herbert Haueisen Sander,Paulo Henrique Amêndola Couto,Leandro Martins Diniz
Acta Odontológica Venezolana , 2007,
Abstract: El objetivo de este estudio fue evaluar la eficacia de agentes de desinfección indicados para polisulfuros (mercaptanos), poliéteres y siliconas por condensación y por adición. Fueron confeccionadas noventa muestras de cada material, siendo treinta de ellas contaminadas con Streptococcus mutans o Staphylococcus aureus o Candida albicans. De cada solución microbiana fueron retiradas diez muestras del polisulfeto y de ambas las siliconas, que fueron inmersas por diez minutos en glutaraldehído al 2% y otras diez inmersas en agua destilada estéril (controle negativo). Después de un nuevo lavado en agua destilada, las muestras fueron transferidas a medios de cultivo estériles. Las diez muestras restantes no fueron sometidas al agente de desinfección y fueron transferidas a medios asociados a agentes antimicrobianos específicos (control positivo). La turbidez de los medios de cultivo fue evaluada como indicativo del crecimiento microbiano siguiéndose a la incubación por 24 h a 37O C y se realizó la dilución y sembrado en placas de Petri para contar las colonias. Para el poliéter fue ejecutado el mismo procedimiento, pero el agente de desinfección usado fue el hipoclorito de sodio a 1%. No hubo turbidez comprobatoria del crecimiento microbiano en ninguno de los medios de cultivo que contenían los especimenes sometidos a los agentes de desinfección. Se concluyó que el glutaraldehído al 2% es un agente de desinfección eficaz para el polisulfuro y para las siliconas por adición y por condensación, así como el hipoclorito a 1% es eficaz para el poliéter, para los microorganismos evaluados. O objetivo deste estudo in vitro foi avaliar a eficácia de agentes de desinfec o indicados para polissulfetos, poliéteres e siliconas de condensa o e adi o. Foram confeccionadas noventa amostras de cada material, sendo cada trinta contaminadas com Streptococcus mutans, Staphylococcus aureus ou Candida albicans. De cada solu o microbiana foram retiradas dez amostras do polissulfeto e de ambas as siliconas, que foram imersas por dez minutos no glutaraldeído a 2% e outras dez imersas em água destilada estéril (controle negativo). Após nova lavagem em água destilada, as amostras foram transferidas para meios de cultura estéreis. As dez amostras restantes n o foram submetidas ao agente de desinfec o e foram transferidas para meios associados a agentes antimicrobianos específicos (controle positivo). A turbidez dos meios de cultura foi avaliada como indicativo de crescimento microbiano após incuba o por 24 h a 37O C e realizou-se a dilui o e semeadura nas placas de Petri para co
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