Exact effective action for fermions in one dimension with backscattering at a boundary

We report exact results for the partition function for free Dirac fermions on a half line with physically sensible boundary conditions. An exact effective action for general backscattering amplitudes is derived. The action also includes the effects of both a (time-dependent) forward scattering amplitude and a dynamical chiral twist of the fermion boundary conditions. For a small backscattering amplitude, the effective action has the expected boundary Sine-Gordon form. We discuss applications of our results to one-dimensional Fermi systems with local backscattering.Comment: 4 pages, revtex, no figure

10 años de la 4ta Mesa : análisis retrospectivo de la flexibilización del régimen de promoción de 3er. año de la carrera de Medicina de la FCM, UNCuyo

Los procesos de democratización en el acceso a la universidad exigen considerar y realizar modificaciones organizacionales y de concepciones sobre la educación que garanticen, no sólo el ingreso, sino que hagan posible la permanencia y egreso del estudiante. En la carrera de Medicina de la UNCuyo, a partir de la reforma curricular, se adoptó un régimen de promoción estricto que no permite cursar materias del año siguiente sin haber regularizado, rendido y aprobado la totalidad de las materias de año cursado, teniendo un importante impacto en la reducción del tiempo promedio de duración de carrera. Por supuesto, tales resultados no sólo pueden ser atribuidos al régimen de promoción, sino al cambio curricular que implicó modificaciones sustanciales del plan de estudio, régimen de evaluación, estrategias docentes y rol del docente. La 4ta mesa es una mesa especial que se incorpora en el 2006 con el objetivo de flexibilizar el régimen de promoción. Permite que estudiantes que adeuden materias de tercero, puedan tener la posibilidad de acreditar en junio en esta mesa excepcional y puedan rendir la Prueba Global de Ciclo Básico en Julio y si aprueban iniciar 4to año en el segundo semestre. El presente trabajo recopila información, luego de 10 años de instaurada esta 4ta mesa, presentando los datos encontrados de los estudiantes que utilizaron esta mesa excepcional con el objetivo de poner en discusión el tema y tener la posibilidad de incluir elementos o perspectivas de análisis no habituales.Fil: Fuentes, Ana. Universidad Nacional de Cuyo. Facultad de Ciencias MédicasFil: Horen, Ludmila . Universidad Nacional de Cuyo. Facultad de Ciencias Médica

Entrepreneurship, principios de un largo recorrido

La evolución del Entrepreneurship como área de investigación ha sido objeto de varios estudios desde disciplinas como la economía, la gestión empresarial o la historia de la ciencia, dada su juventud y la polémica generada en torno a su definición. El presente trabajo se propone realizar una breve revisión de la literatura creada alrededor de este concepto, desde la perspectiva de organización de empresas, destacando el camino hacia lo que hoy en día se ha convertido en su paradigma dominante: el proceso de descubrimiento, evaluación y explotación de oportunidades

Interacting electrons on a half line coupled to impurities

We generalize the bosonization methods for systems in the half line that we discussed elsewhere, to study the effects of interactions on electronic systems coupled to impurities. We introduce a model for a quantum wire coupled with a quantum dot by a purely capacitive interaction. We show that the effect on the quantum wire is a dynamical boundary condition which reflects the charge fluctuations of the quantum dot. Special attention is given to the role of the fermion boundary conditions and their interplay with the electron interactions on the bosonized effective theory.Comment: 34 page

Agricultura urbana en el marco de un urbanismo sostenible

L'agricultura es considerada uns dels avenços fonamentals en el desenvolupament de la humanitat. Tot i que la ciutat, des del seu naixement, ha estat estretament relacionada amb l'agricultura, que tenia una presència essencial en les civilitzacions antigues, en els plantejaments urbans moderns del segle XX -com ara Chandigarh de Le Corbusier i Brasília de Lucio Costa- l'agricultura va ser expulasada de les grans ciutats.Agriculture represents a crucial phase in the development of mankind. Although cities initially had close ties with agriculture, which was a key element in ancient civilisations, in modern twentieth-century urban plans, such as Le Corbusier's Chandigarh or Lucio Costa's Brazilia, agriculture was banished from large cities. The demographic growth of urban areas today and its predictions for the short and long term have increased the value of urban agriculture.La agricultura es considerada uno de los pasos clave en el desarrollo de la humanidad. Si bien desde sus inicios la ciudad ha estado estrechamente relacionada con la agricultura, cuya presencia fue esencial en las antiguas civilizaciones, en los planeamientos urbanos modernos del siglo XX, como por ejemplo Chandigarh de Le Corbusier y Brasilia de Lucio Costa, la agricultura fue expulsada de las grandes ciudades

Entrepreneurship, principios de un largo recorrido.

La evolución del Entrepreneurship como área de investigación ha sido objeto de varios estudios desde disciplinas como la economía, la gestión empresarial o la historia de la ciencia, dada su juventud y la polémica generada en torno a su definición. El presente trabajo se propone realizar una breve revisión de la literatura creada alrededor de este concepto, desde la perspectiva de organización de empresas, destacando el camino hacia lo que hoy en día se ha convertido en su paradigma dominante: el proceso de descubrimiento, evaluación y explotación de oportunidades.Entrepreneurship, emprendedor, reconocimiento y explotación de oportunidades.

A Q Methodology approach to define urban sustainability challenges in a small insular city

The objective of this paper is to define what problems the city of Angra do Heroísmo (Terceira Island, Azores) faces in what regards urban sustainability, so as to improve the quality of life of the residents and to ensure the adequate growth and progress of the city in all areas, as possible. The main themes approached in this work were urbanism, the city’s current development level, public security, environment, culture and education, economy, funding, governance, migration, public participation and poverty. Selected stakeholders ranked statements pertaining each of these themes, from which we extracted three distinct social perspectives, one concerned with employment and the recovery of the city, another that praises the quality of human resources and a third that trusts the quality of the social infrastructure. All perspectives seem to agree that there are no public security problems in Angra, and that rebuilding is a more sustainable option. They also believe that there is adequate support for migrants, good dialogue between public bodies and social organizations, and that the population is willing to play a greater role in the city’s governance. Key-words: urban sustainability, q methodology, stakeholder perspectives

Concept lattices associated with L-Fuzzy W-contexts

\begin{abstract} \noindent We generalize in this paper the $L$-Fuzzy concept theory we developed in a previous paper ([1]), using the composition of $L$-Fuzzy relations. This theory models knowledge acquisition and classification and takes as departure point Wille's idea ([5]). We begin the work defining $L$-Fuzzy W-contexts as the tuples (L,W,X,Y, $\underset{\textstyle \backsim}{R}$) where W, X and Y are the sets of labels, objects and attributes respectively, and $\underset{\textstyle \backsim}{R}\in L^{X\times Y}$ is an $L$-Fuzzy relation. From these contexts, we will give the operators needed to define the \linebreak $L$-Fuzzy W-concepts. These concepts will be pairs of relations ($\underset{\textstyle \backsim}{P}, \underset{\textstyle \backsim}{Q}$) where $\underset{\textstyle \backsim}{P}\in L^{W\times X}$, $\underset{\textstyle \backsim}Q\in L^{W\times Y}$ satisfying $\underset{\textstyle \backsim}{P_{1}}= \underset{\textstyle \backsim}Q$ and $\underset{\textstyle \backsim}Q_{2}= \underset{\textstyle \backsim}P$ with the operator 1 and 2 definitions given. After proving the lattice structure of the $L$-Fuzzy W-concepts set, we analyse a practical example where we interpret the new concept definition \bigskip \noindent {\bf Key words:} $L$-Fuzzy concepts, $L$-Fuzzy W-concepts, $L$-Fuzzy W-contexts, Conceptual knowledge. \end{abstract

Simulating climate change and land use effects on soil nitrous oxide emissions in Mediterranean conditions using the Daycent model

In Mediterranean agroecosystems, limited information exists about possible impacts of climate change on soil N2O emissions under different land uses. This paper presents a modelling study with a dual objective. Firstly, the biogeochemical Daycent model was evaluated to predict soil N2O emissions in different land uses in a typical Mediterranean agroecosystem. Secondly, the study aimed to determine the impact of climate change on soil N2O emissions in different Mediterranean land uses over an 85-year period. Soil N2O emissions were measured in three land uses (cropland, abandoned land and afforested land) over 18 months (December 2011 to June 2013) in a characteristic Mediterranean site in Spain. For climate change simulations, Daycent was run with and without atmospheric CO2 enrichment using climate data from the CGCM2-A2 model. The cumulative N2O emissions predicted by the Daycent model agreed well with the observed values. The lack of fit (LOFIT) and the relative error (E) statistics determined that the model error was not greater than the error in the measurements and that the bias in the simulation values was lower than the 95% confidence interval of the measurements. For the different land uses and climate scenarios, annual cumulative N2O emissions ranged from 126 to 642 g N2O-N ha−1 yr−1. Over the simulated 85-year period, climate change decreased soil N2O emissions in all three land uses. At the same time, under climate change, water filled pore space (WFPS) values decreased between 4% and 15% depending on the land use and climate change scenario considered. This study demonstrated the ability of the Daycent model to simulate soil N2O emissions in different land uses. According to model predictions, in Mediterranean conditions, climate change would lead to reduced N2O emissions in a range of land uses.Jorge Álvaro-Fuentes acknowledges the receipt of a fellowship from the OECD Co-operative Research Programme: Biological Resource Management in Sustainable Agricultural Systems in 2013. Daniel Plaza-Bonilla received a “Juan de la Cierva” grant from the Ministerio de Economía y Competitividad of Spain. This study was also possible through funds provided by the Aragon Regional Government and La Caixa (grant GA-LC-050/2011), the Ministry of Economy and Competitiveness of Spain (grant AGL2013-49062-C4-4-R) and the COMET-Global project (FACCE-JPI grant). We are grateful to María José Salvador and Javier Bareche for laboratory assistance