Análisis de la evolución del precio en el Mercado Eléctrico Mayorista de la República Argentina entre 1992 y 1997

El presente trabajo busca determinar las causas de la evolución del precio en el Mercado Eléctrico Mayorista de la República Argentina en el periodo comprendido entre los años 1992 y 1997. El precio mayorista de la energía eléctrica tuvo una caída a casi el 50 por ciento de su valor inicial mientras se registraba un aumento en la demanda del 45,9 por ciento. En este periodo, se produjeron cambios muy importantes en el sector, que pueden ser explicados a través de diversos indicadores como la potencia instalada en cada región, la disponibilidad de los equipos, el aporte de agua de los ríos donde se ubican las centrales hidráulicas, la capacidad de transporte del sistema, los precios de los combustibles que usan las centrales de generación térmica y la disponibilidad de combustibles baratos.Mercado Eléctrico Mayorista; Precio

Oferta y demanda de electricidad en la Argentina: un modelo de ecuaciones simultáneas

El presente trabajo busca cuantificar el impacto de los diferentes determinantes de la evolución del precio de la electricidad en el Mercado Eléctrico Mayorista de la República Argentina en el período comprendido entre Agosto de 1992, momento en el que se crea el Mercado Eléctrico Mayorista y Diciembre de 1998. Para ello se estimó un modelo de ecuaciones simultáneas con mínimos cuadrados en dos etapas, encontrándose que las variaciones del precio pueden ser explicadas, vía demanda, por las variaciones en el nivel de actividad y la temperatura, y vía oferta, por la potencia disponible, el precio del gas natural y la hidraulicidad.precio electricidad; Mercado Eléctrico Mayorista; modelo de ecuaciones simultáneas

Gradient-Based Spectral Embeddings of Random Dot Product Graphs

The Random Dot Product Graph (RDPG) is a generative model for relational data, where nodes are represented via latent vectors in low-dimensional Euclidean space. RDPGs crucially postulate that edge formation probabilities are given by the dot product of the corresponding latent positions. Accordingly, the embedding task of estimating these vectors from an observed graph is typically posed as a low-rank matrix factorization problem. The workhorse Adjacency Spectral Embedding (ASE) enjoys solid statistical properties, but it is formally solving a surrogate problem and can be computationally intensive. In this paper, we bring to bear recent advances in non-convex optimization and demonstrate their impact to RDPG inference. We advocate first-order gradient descent methods to better solve the embedding problem, and to organically accommodate broader network embedding applications of practical relevance. Notably, we argue that RDPG embeddings of directed graphs loose interpretability unless the factor matrices are constrained to have orthogonal columns. We thus develop a novel feasible optimization method in the resulting manifold. The effectiveness of the graph representation learning framework is demonstrated on reproducible experiments with both synthetic and real network data. Our open-source algorithm implementations are scalable, and unlike the ASE they are robust to missing edge data and can track slowly-varying latent positions from streaming graphs

Online change point detection for weighted and directed random dot product graphs

Given a sequence of random (directed and weighted) graphs, we address the problem of online monitoring and detection of changes in the underlying data distribution. Our idea is to endow sequential change-point detection (CPD) techniques with a graph representation learning substrate based on the versatile Random Dot Product Graph (RDPG) model. We consider efficient, online updates of a judicious monitoring function, which quantifies the discrepancy between the streaming graph observations and the nominal RDPG. This reference distribution is inferred via spectral embeddings of the first few graphs in the sequence. We characterize the distribution of this running statistic to select thresholds that guarantee error-rate control, and under simplifying approximations we offer insights on the algorithm’s detection resolution and delay. The end result is a lightweight online CPD algorithm, that is also explainable by virtue of the well-appreciated interpretability of RDPG embeddings. This is in stark contrast with most existing graph CPD approaches, which either rely on extensive computation, or they store and process the entire observed time series. An apparent limitation of the RDPG model is its suitability for undirected and unweighted graphs only, a gap we aim to close here to broaden the scope of the CPD framework. Unlike previous proposals, our non-parametric RDPG model for weighted graphs does not require a priori specification of the weights’ distribution to perform inference and estimation. This network modeling contribution is of independent interest beyond CPD. We offer an open-source implementation of the novel online CPD algorithm for weighted and direct graphs, whose effectiveness and efficiency are demonstrated via (reproducible) synthetic and real network data experimentsWork in this paper is supported in part by ANII (grant FMV 3 2018 1 148149) and the NSF (awards CCF-1750428, CCF-1934962 and ECCS-1809356). Part of the results in this paper were submitted to the 2021 EUSIPCO and Asilomar Conference

Prospects of Mobile Search

Search faces (at least) two major challenges. One is to improve efficiency of retrieving relevant content for all digital formats (images, audio, video, 3D shapes, etc). The second is making relevant information retrievable in a range of platforms, particularly in high diffusion ones as mobiles. The two challenges are interrelated but distinct. This report aims at assessing the potential of future Mobile Search. Two broad groups of search-based applications can be identified. The first one is the adaptation and emulation of web search processes and services to the mobile environment. The second one is services exploiting the unique features of the mobile devices and the mobile environments. Examples of these context-aware services include location-based services or interfacing to the internet of things (RFID networks). The report starts by providing an introduction to mobile search. It highlights differences and commonalities with search technologies on other platforms (Chapter 1). Chapter 2 is devoted to the supply side of mobile search markets. It describes mobile markets, presents key figures and gives an outline of main business models and players. Chapter 3 is dedicated to the demand side of the market. It studies users¿ acceptance and demand using the results on a case study in Sweden. Chapter 4 presents emerging trends in technology and markets that could shape mobile search. It is the author's view after discussing with many experts. One input to this discussion was the analysis of on forward-looking scenarios for mobile developed by the authors (Chapter 5). Experts were asked to evaluate these scenarios. Another input was a questionnaire to which 61 experts responded. Drivers, barriers and enablers for mobile search have been synthesised into SWOT analysis. The report concludes with some policy recommendations in view of the likely socio-economic implications of mobile search in Europe.JRC.DG.J.4-Information Societ

Daños ocasionados por el gorgojo Listroderes foveatus (Coleoptera: Curculionidae) en cultivos de girasol del sudeste de Buenos Aires (Argentina)

El cultivo del girasol es afectado por insectos plaga en sus diferentes estadios de desarrollo vegetativo. Entre estos, se encuentra un complejo coleópteros del género Listroderes Schoenhere conocidos vulgarmente como “gorgojos del girasol”. Los adultos afecta al cultivo en las primeras etapas de su desarrollo. Durante el ciclo agrícola 2019-2020, adultos de especie Listroderes Foveatus (Lea) causaron pérdidas significativas en la densidad de plantas logradas de girasol, en varios cultivos de la región del sudoeste de la provincia de Buenos Aires. Se registraron daños a nivel de la base de la plantas y, dependiendo del desarrollo de su estado vegetativo, los gorgojos ocasionaron corte y estrangulamiento seguido por vuelco y posterior muerte. La magnitud de los daños producidos se reflejó en la necesidad de resiembra parcial o total en varios lotes de girasol.Sunflowers are attacked by insect pests at various stages of crop development. Among them there is a complex of species of Coleoptera order, genus Listroderes Schoenherr, commonly known as “sunflower weevils”. The adults affect the crop at the early stages of its development. During 2019-2020 growing season, adult of Listroderes foveatus (Lea) species caused significant losses in the sunflower plant stand, in several sunflower plots of the southeastern region of Buenos Aires province. Damage at basal level of the plant stem was registered. Depending on the vegetative development stage, they caused their cut or strangulation, followed by overturning and subsequent death. The magnitude of the damage caused was reflected in the need for total or partial resowing in several sunflower plots.EEA BalcarceFil: Tulli, María Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Martiarena, Diego. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina.Fil: Divita, Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Mateos Inchauspe, Facundo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Carmona, Dora. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina.Fil: Del Río, María. Universidad de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Trayecto curricular de la Materia Optativa “Lógicas Ambientales para el Proyecto Arquitectónico”

The epistemological foundations and the operational modalities of the elective subject “Environmental Logics for Architectonic Project” are presented. The subject is being dictaded since 2009 at the FAPyD at UNR. It focuses on the dissociation between society and nature pointing out the need of implementing strategies to reduce anthropic impacts on available resources. The concept of Habitat Environmental Efficiency is proposed on various scales, as part of the theoretical contents. This issue aims to recognize the environmental problems associated with inefficient use of land, matter and energy in relation with the principles of environmentally conscious design in the Architectural and Urban Field. The criteria adopted are described for the development of the practical works through the years of teaching. Relevant variables in the process of contextualized design project focuses on rational use of resources and habitability in Social Housing.Se presentan los fundamentos epistemológicos y las modalidades operativas de la materia optativa “Lógicas Ambientales para el Proyecto Arquitectónico”, dictada desde 2009 en la FAPyD – UNR, la cual plantea la disociación sociedad-naturaleza, fundamentando la necesidad de implementar estrategias que reduzcan los impactos antrópicos sobre los recursos disponibles. Se explicita el concepto de Eficiencia Ambiental del Hábitat en sus diversas escalas, como parte de los contenidos teóricos orientados a reconocer las problemáticas ambientales asociadas al uso ineficiente del suelo, la materia y la energía en el campo Arquitectónico y Urbanístico, en relación con las lógicas generales del diseño ambientalmente consciente. Se describen los criterios adoptados para el desarrollo de los trabajos prácticos a lo largo de los años de dictado, y las variables significativas inherentes al proceso crítico de toma de decisiones proyectuales contextualizadas y atentas al uso racional de los recursos y a la habitabilidad en el diseño del Hábitat Social

Correction: Effectiveness of a scalable, remotely delivered stepped-care intervention to reduce symptoms of psychological distress among Polish migrant workers in the Netherlands: study protocol for the RESPOND randomised controlled trial

Following the publication of the original article [1], the authors identified that the sentence under the subheading Sample size was incorrect. The correct sentence is given below. The incorrect sentence is: Power calculations suggested a minimum sample size of 74 per group (power = 0.80, α = 0.05, two-sided). The correct sentence is: Power calculations suggested a minimum sample size of 74 per group (power = 0.95, α = 0.05, two-sided). The original article [1] has been corrected