Abstract:
Los metales pesados (MP) son parte de los contaminantes que contiene el lixiviado, este es generado por la descomposición de los residuos sólidos urbanos (RSU), el cual por su toxicidad puede causar severos problemas al ambiente. El propósito de este trabajo fue conocer el efecto de diferentes tasas de recirculación de lixiviados en la concentración de MP, así como en la matriz de residuos de biorreactores anaerobios (BrA) a escala laboratorio, para determinar la tasa que produzca la menor lixiviación de MP. Se utilizaron 20 BrA con RSU del relleno sanitario de Pátzcuaro, Michoacán, México; cuatro como testigos y al resto se les recircularon sus lixiviados dos veces por semana, para mantener los contenidos de humedad de 50, 60, 70 y 80 % base húmeda (%Hbh) por cuadruplicado. Se dio seguimiento durante 126 días a los lixiviados producidos, a los cuales se les determinó pH y metales pesados totales (MPT). A los residuos sólidos descargados se les determinó pH, materia orgánica (MO), MPT y metales pesados disponibles (MPD), Ni, Pb y Zn. Los lixiviados generados a 80 y 70 % Hbh, presentaron menor lixiviación de MP, mientras que a 50 % Hbh durante las fases de hidrólisis y acidogénesis mostraron concentraciones elevadas. Para MPT en los residuos sólidos, Ni y Pb presentaron diferencias significativas entre las muestras y en cuanto a los MPD sólo existieron diferencias significativas para Zn. Los residuos sólidos de todas las tasas de recirculación pueden utilizarse como mejoradores de suelo por su alto contenido de MO y baja concentración de MP.

Abstract:
An extensive analysis was performed on 8.0 pb-1 of dimuon data produced in pi- - A collisions at 515 GeV/c to search for Lambda_b events in the decay channel Lambda_b --> J/psi Lambda^0, with J/psi --> mu^+ mu^- and Lambda^0 --> p pi^- (and for the conjugate reactions). The data was collected by the Fermilab fixed target experiments E672 and E706. Several cuts were applied to the Lambda^0 (and anti-Lambda^0) to make a clean Lambda^0 (and anti-Lambda^0) data sample. Among the cuts there was a K^0_s mass cut, in which if the Lambda^0 --> p pi^- (or conjugate reaction) had the mass of the K^0_s under the hypothesis of both tracks being pi^+ pi^-, the Lambda^0 (or anti-Lambda^0) candidates were rejected. The results show 2 events in the Lambda_b mass region. Using the E672/E706 measurement of the bb_bar cross-section, and considering the 2 Lambda_b event candidates as signal with zero background, an upper limit to F(Lambda_b) * Br(Lambda_b --> J/psi Lambda^0) was found to be less than 6.2x10^-2 at 90 % C. L. An upper limit was also calculate without using the K^0_s mass cut for the Lambda^0 s (and anti-Lambda^0 s), and again, requiring that the J/psi s originate from secondary vertices, giving that F(Lambda_b) * Br(Lambda_b --> J/psi Lambda^0) < 3.1x10^-2 at 90 % C. L. and F(Lambda_b) * Br(Lambda_b --> J/psi Lambda^0) < 3.2x10$^-2 at 90 % C.L., respectively.

Abstract:
In this paper we construct a combinatorial algorithm of resolution of singularities for binomial ideals, over a field of arbitrary characteristic. This algorithm is applied to any binomial ideal. This means ideals generated by binomial equations without any restriction, including monomials and $p$-th powers, where $p$ is the characteristic of the base field. In particular, this algorithm works for toric ideals. However, toric geometry tools are not needed, the algorithm is constructed following the same point of view as Villamayor algorithm of resolution of singularities in characteristic zero.

Abstract:
This paper is devoted to give all the technical constructions and definitions that will lead to the construction of an algorithm of resolution of singularities for binomial ideals. We construct a resolution function that will provide a resolution of singularities for binomial ideals, over a field of arbitrary characteristic. For us, a binomial ideal means an ideal generated by binomial equations without any restriction, including monomials and $p$-th powers, where $p$ is the characteristic of the base field. This resolution function is based in a modified order function, called $E$-order. The $E$-order of a binomial ideal is the order of the ideal along a normal crossing divisor $E$. The resolution function allows us to construct an algorithm of $E$-\emph{resolution of binomial basic objects}, that will be a subroutine of the main resolution algorithm.

Abstract:
We study monomial ideals, always locally given by a monomial, like a reasonable first step to estimate in general the number of monoidal transformations of Villamayor's algorithm of resolution of singularities. The resolution of a monomial ideal $$ is interesting due to its identification with the particular toric problem $$. In the special case, when all the exponents $a_i$ are greater than or equal to the critical value $c$, we construct the largest branch of the resolution tree which provides an upper bound involving partial sums of Catalan numbers. This case will be called ``minimal codimensional case''. Partial sums of Catalan numbers (starting $1,2,5,...$) are $1,3,8,22,...$ These partial sums are well known in Combinatorics and count the number of paths starting from the root in all ordered trees with $n+1$ edges. Catalan numbers appear in many combinatorial problems, counting the number of ways to insert $n$ pairs of parenthesis in a word of $n+1$ letters, plane trees with $n+1$ vertices, $... $, etc. The non minimal case, when there exists some exponent $a_{i_0}$ smaller than $c$, will be called ``case of higher codimension''. In this case, still unresolved, we give an example to state the foremost troubles. Computation of examples has been helpful in both cases to study the behaviour of the resolution invariant. Computations have been made in Singular (see \cite{sing}) using the \emph{desing} package by G. Bodn\'ar and J. Schicho, see \cite{lib}.

Abstract:
this project was part of the research line entitled "violence and the media" developed by the faculty of psychology of the universidad de la sabana. , the aim of the study was to enquire about the meaning that children give to violent contents of videogames. participants were four children between the ages of 11 and 14, who attended public schools in the village of chía (colombia). the research had a qualitative approach and used a descriptive-explanatory method, adopting the single-case study strategy. based on the participants？ narratives an analysis was made of the meanings that children gave to topics such as recognition of violence, conflict perception, conflict resolution, gender identity, relationship between family and videogames and the power of videogames. data were collected through the use of focus groups and analyzed according to strauss and corbin？s theory (2002). results show that there is a relationship between the violent contents of videogames and the meaning given to them by the participants in the focus group. this underlines the influence that videogames have on the development of values and beliefs in children.

Abstract:
This project was part of the research line entitled "Violence and the Media" developed by the Faculty of Psychology of the Universidad de la Sabana. , The aim of the study was to enquire about the meaning that children give to violent contents of videogames. Participants were four children between the ages of 11 and 14, who attended public schools in the village of Chía (Colombia). The research had a qualitative approach and used a descriptive-explanatory method, adopting the single-case study strategy. Based on the participants' narratives an analysis was made of the meanings that children gave to topics such as recognition of violence, conflict perception, conflict resolution, gender identity, relationship between family and videogames and the power of videogames. Data were collected through the use of Focus Groups and analyzed according to Strauss and Corbin's theory (2002). Results show that there is a relationship between the violent contents of videogames and the meaning given to them by the participants in the focus group. This underlines the influence that videogames have on the development of values and beliefs in children

We give a new way to price American options by using Samuelson’s formula. We first obtain the option price corresponding to a European option at time t, weighing it by the probability that the underlying asset takes the value S at time t. We then use Samuelson’s formula with this factor which is given by the solution of the Fokker-Planck (Kolmogorov) equation for the transition probability density. The main advantage of this approach is that we can systematically introduce the effect of macroeconomic factors. If a macroeconomic framework is given by a dynamical system in the form of a set of ordinary differential equations we only have to solve a partial differential equation for the transition probability density. In this context, we verify, for the sake of consistency, that this formula coincides with the Black-Scholes model and compare several numerical implementations.

Abstract:
republic or argentina is characterized by a sharp inequality in the development level of it regions. this paper reviews the way in which that regional asymmetry is originated, and how it was reproduced along the different stages of argentinean history. a series of hypothesis regarding it main features in the present stage is developed

Abstract:
this paper has the objective of carrying out a critical analysis of the theories that justified the decentralizing process in the republic of argentina, trying to determine, from the perspective of their failure, their most fundamental weaknesses. with this objective in mind, i start with a succinct description of the decentralizing process in argentina and the advantages that, according to its supporters, these actions would bring about. afterwards, i criticize these concepts, detailing, according to the authors, the reasons why the expected results could not be achieved.