Numerical semigroups II: pseudo-symmetric AA-Semigroups

This paper is a continuation of the paper " Numerical Semigroups: Apéry Sets and Hilbert Series". We consider the general numerical AA-semigroup, i.e., semigroups consisting of all non-negative integer linear combinations of relatively prime positive integers of the form $a, a+d, a+2d,. .. , a+kd, c$. We first prove that, in contrast to arbitrary numerical semigroups, there exists an upper bound for the type of AA-semigroups that only depends on the number of generators of the semigroup. We then present two characterizations of pseudo-symmetric AA-semigroups. The first one leads to a polynomial time algorithm to decide whether an AA-semigroup is pseudo-symmetric. The second one gives a method to construct pseudo-symmetric AA-semigroups and provides explicit families of pseudo-symmetric semigroups with arbitrarily large number of generators

Simple model of a glow discharge electron beam for materials processing, A

Includes bibliographical references (page 432).A simple semiempirical model of the electron beam generated by a pulsed cold cathode electron gun has been developed. The model describes analytically the observed self-focusing of the discharge and predicts the dynamical variation of the focal distance, in good agreement with experiments. This effect plays a major role in the determination of the effective duration of the energy pulse. The model was used to conduct simple calculations of energy thresholds for melting of solid materials, giving helpful insight on ranges of operation of this kind of electron gun for its application to material processing. A comparison with available experimental data for Mg70Zn30 samples is given

Negociación: competencia gerencial por antonomasia

Los conflictos son inherentes al ser humano y surgen cuando las personas se relacionan e interactúan, cuando manejan posiciones contrarias, las sostienen y las defienden. Las buenas decisiones surgen de la creatividad por el desacuerdo. Negociar es redefinir el problema para generar la mejor opción que satisfaga los intereses de las partes y, en consecuencia, éstas puedan comprometerse en un acuerdo que puedan cumplir. Dentro de la nueva concepción de la gerencia como suministradora de conocimientos para generar resultados, la competencia de negociación ha venido adquiriendo un gran protagonismo e importancia, esencialmente por constituirse en la herramienta fundamental para la solución de conflictos y para el establecimiento y mantenimiento de relaciones perdurables.Conflicts are inherent in human beings. Conflicts occur when people interact and have opposing viewpoints that they sustain and defend. The right management decisions come from the creativity spurred by a disagreement. Negotiating is to redefine an issue in order to generate the best option that satisfies the interests of all parties, thus obtaining commitments to an agreement that the parties involved can maintain. Inside the new conception of management as the source of knowledge to generate results, the ability to negotiate conflicts has been acquiring high importance, essentially because it constitutes the fundamental tool for conflict resolution and for settling down durable relationships

La globalización: más que una amenaza es una oportunidad

El fenómeno de la internacionalización evoluciona, al terminar la Guerra Fría, hacia una globalización en la sociedad poscapitalista, en la cual el conocimiento es el recurso fundamental para generar riqueza. Al entender la globalización como un proceso de interconexión financiera, económica, social, política y cultural se abre la oportunidad para el progreso de los pueblos que desarrollen su economía al abrirse hacia el exterior. Ya no es momento para teorizar sobre la conveniencia o no de la globalización, ésta es una realidad irreversible que en Colombia debemos aprovechar.After the Cold War, the process of internationalization evolves towards globalization in the post-capitalistic society, where knowledge is considered the most critical resource to create wealth. Understanding globalization as an interconnected process among financial, economic, social, political, and cultural elements provides the opportunity to any country to develop itself by eliminating its geographic boundaries. It is no longer the time to theorize over the pertinence of globalization, since it has become a reality that we should take advantage in Colombia

AMELIE: Authoring Multimedia-Enhanced Learning Interactive Environment for medical contents

This paper presents the AMELIE Authoring Tool for medical e-learning applications. The tool allows for the creation of enhanced-video based didactic contents, and can be adjusted to any number of platforms and applications. Validation provides preliminary good results on its acceptance and usefulness

Trasplante hepático

Liver transplantation is an efficient therapeutic option for terminal hepatic diseases. The principal indications of liver transplantation are hepatic cirrhosis, hepatic tumours (mainly, hepotocellular carcinoma) and acute liver failure. Over the years, the absolute contraindications for a transplant have lessened. Surgical techniques have also undergone changes. The results of liver transplant have improved so that survival one year after the transplant is close to 90% and after five years some 80% of transplanted patients continue to live

Instabilities of naked singularities and black hole interiors in general relativity

Metrics representing black holes in General Relativity may exhibit naked singularities for certain values of their parameters. This is the case for super-extremal (J2 \u3e M \u3e 0) Kerr and super-extremal (|Q| \u3e M \u3e 0) Reissner-Nördstrom spacetimes, and also for the negative mass Schwarzschild spacetime. We review our recent work where we show that these nakedly singular spacetimes are unstable under linear gravitational perturbations, a result that supports the cosmic censorship conjecture, and also that the inner stationary region beyond the inner horizon of a Kerr black hole (J2 \u3c M) is linearly unstable. © 2009 World Scientific Publishing Company

Commitment and the Dynamics of Household Labor Supply

The extent to which individuals commit to their partner for life has important implications. This paper develops a lifecycle collective model of the household, through which it characterizes behavior in three prominent alternative types of commitment: full, limited, and no commitment. We propose a test that distinguishes between all three types based on how contemporaneous and historical news affect household behavior. Our test permits heterogeneity in the degree of commitment across households. Using recent data from the Panel Study of Income Dynamics, we reject full and no commitment, while we find strong evidence for limited commitment