Arquitecturas miniaturizadas y su contextualización en el arte contemporáneo

Los últimos años nos han dejado numerosos ejemplos de trabajos artísticos consistentes en modelos de edificios a escala reducida, un ejemplo más del prolífico diálogo entre arte y arquitectura. En este artículo se analiza lo específico de estos trabajos por su escala reducida y, a partir de varios ejemplos, se plantean cuatro tendencias presentes en el arte contemporáneo, sintomáticas de una emancipación de las formas e ideas de la modernidad: su carácter narrativo, el retorno de la figuración, el gusto por lo artesanal y una actitud posindividualista. Se describe cómo estas tendencias están también presentes, con algunas diferencias, en la arquitectura contemporánea, por lo que puede hablarse de rasgos comunes a ambas disciplinas y de una retroalimentación bidireccional. Desde el punto de vista del arquitecto, estas obras artísticas amplían el potencial expresivo de la maqueta arquitectónica y le permiten replantearse su papel, teniendo en cuenta consideraciones más allá del diseño formal, tales como la percepción emocional, la percepción simbólica, etc. In recent years we have seen numerous examples of artwork consisting of small–scale models of buildings, another example of the close relationship between art and architecture. This article analyses the specifics of these pieces of work through their reduced scale using several examples to do so, addressing four trends that are currently present in contemporary art, symptomatic of an emancipation away from forms and ideas of modernity: their narrative character, the return to figuration, a taste for craft and a post–individualist attitude. We describe how these trends are also present in contemporary architecture, albeit with some differences, therefore enabling us to talk about features that are common to both disciplines and two–way feedback. From the point of view of architects these pieces of artwork amplify the expressive potential of architectural modelling and permit redefining their role, taking into account considerations that go beyond formal design, such as emotion perception, symbolic perception, etc

Oil price effect on sectoral stock returns: A conditional covariance and correlation approach for Mexico

Efecto del precio del petróleo en las rentabilidades de las acciones sectoriales: Un enfoque condicional de covarianza y correlación para MéxicoEste trabajo analiza la relación entre la volatilidad del precio del petróleo y rendimientos bursátiles sectoriales seleccionados en México (Industrial, materiales, financiero y de consumo discrecional) a través de la implementación de un modelo GARCH bivariado tipo VECH Diagonal para estimar sus covarianzas y correlaciones condicionales. El hallazgo más importante es que existe una relación estadística significativa entre los índices sectoriales y las variaciones en el precio del petróleo. Las correlaciones condicionales sugieren que durante la mayor parte del periodo del análisis la relación entre el precio del petróleo y los rendimientos sectoriales es positiva. La recomendación apoyada por los resultados descritos es que los inversionistas deben tomar en cuenta la interacción mencionada para generar coberturas de riesgo más robustas. Dentro de las limitantes de la investigación, se encuentra la escasez de información a nivel sector en el mercado bursátil del país. La aportación original de este estudio radica en el análisis con enfoque sectorial. Los resultados apoyan a la corriente que sugiere que las fluctuaciones en el precio del petróleo tienen un efecto directo en el mercado bursátil.This paper analyzes the relationship between the volatility of oil price and selected sectoral stock returns in Mexico (industrials, materials, financials and consumer discretionary) by implementing a Diagonal VECH-type bivariate GARCH model in order to estimate conditional covariances and correlations. The econometric results suggest that there exists a statistically significant relationship between sector indices, as well as between Mexico’s aggregate stock exchange returns, and variations in oil prices. Conditional correlations suggest that during most of the analyzed period, the relationship between oil price fluctuations and sectoral stock returns is positive. The recommendation, supported by these results, is that investors should take into consideration the interaction between the analyzed variables in order to generate more robust risk-hedge strategies. An important limitation for this work is information availability at sector level in the country. The original contribution of this paper lies mainly in the analysis of the influence of oil prices over sectoral indices of the Mexican Stock Exchange. These results provide more support to the current that suggests that a price increase in oil has a direct spillover effect on stock market performance

SANS study of hybrid silica aerogels under "in situ" uniaxial compression

We have modified the inorganic silica network of aerogels with polydimethylsiloxane (PDMS), a hydroxyl-terminated polymer, to obtain an organic modified silicate (ORMOSIL). Reactions were assisted by high-power ultrasounds. The resulting gels were dried under supercritical conditions of the solvent to obtain a monolithic sono-aerogel. The mechanical behaviour of these aerogels can be tuned from brittle to rubbery as a function of the organic polymer content. In order to determine the links between the mechanical behaviour and modifications made to the microstructure, SANS (small-angle neutron scattering) experiments were carried out. To measure the intensities under "in situ" uniaxial compression of the aerogel, a specific sample-holder was built. Under uniaxial compression the 2D-diagrams were significantly anisotropic (butterfly pattern), indicating the rearrangement of the polymer. The form factor of these aerogels is described well by two correlation lengths, small microporous silica clusters surrounded by entangled polymer chains of 6 nm average size (blobs), which form a larger secondary level of agglomerates governed by the "frozen-in" elastic constraints.Comisión Interministerial de Ciencia y Tecnología MAT2005-1583European Commission CT-2003-50592

Automated Early Detection of Drops in Commercial Egg Production Using Neural Networks

[Abstract] 1. The purpose of this work was to support decision-making in poultry farms by performing automatic early detection of anomalies in egg production. 2. Unprocessed data were collected from a commercial egg farm on a daily basis over 7 years. Records from a total of 24 flocks, each with approximately 20 000 laying hens, were studied. 3. Other similar works have required a prior feature extraction by a poultry expert, and this method is dependent on time and expert knowledge. 4. The present approach reduces the dependency on time and expert knowledge because of the automatic selection of relevant features and the use of artificial neural networks capable of cost-sensitive learning. 5. The optimum configuration of features and parameters in the proposed model was evaluated on unseen test data obtained by a repeated cross-validation technique. 6. The accuracy, sensitivity, specificity and positive predictive value are presented and discussed at 5 forecasting intervals. The accuracy of the proposed model was 0.9896 for the day before a problem occurs.Galicia. Consellería de Cultura, Educación e Ordenación Universitaria; GRC2014/04

Early Warning in Egg Production Curves from Commercial Hens: a SVM Approach

[Abstract] Artificial Intelligence allows the improvement of our daily life, for instance, speech and handwritten text recognition, real time translation and weather forecasting are common used applications. In the livestock sector, machine learning algorithms have the potential for early detection and warning of problems, which represents a significant milestone in the poultry industry. Production problems generate economic loss that could be avoided by acting in a timely manner. In the current study, training and testing of support vector machines are addressed, for an early detection of problems in the production curve of commercial eggs, using farm’s egg production data of 478,919 laying hens grouped in 24 flocks. Experiments using support vector machines with a 5 k-fold cross-validation were performed at different previous time intervals, to alert with up to 5 days of forecasting interval, whether a flock will experience a problem in production curve. Performance metrics such as accuracy, specificity, sensitivity, and positive predictive value were evaluated, reaching 0-day values of 0.9874, 0.9876, 0.9783 and 0.6518 respectively on unseen data (test-set). The optimal forecasting interval was from zero to three days, performance metrics decreases as the forecasting interval is increased. It should be emphasized that this technique was able to issue an alert a day in advance, achieving an accuracy of 0.9854, a specificity of 0.9865, a sensitivity of 0.9333 and a positive predictive value of 0.6135. This novel application embedded in a computer system of poultry management is able to provide significant improvements in early detection and warning of problems related to the production curve

Possible ring material around centaur (2060) Chiron

We propose that several short duration events observed in past stellar occultations by Chiron were produced by rings material. From a reanalysis of the stellar occultation data in the literature we determined two possible orientations of the pole of Chiron's rings, with ecliptic coordinates l=(352+/-10) deg, b=(37+/-10) deg or l=(144+/-10) deg, b=(24+/-10) deg . The mean radius of the rings is (324 +/- 10) km. One can use the rotational lightcurve amplitude of Chiron at different epochs to distinguish between the two solutions for the pole. Both imply lower lightcurve amplitude in 2013 than in 1988, when the rotational lightcurve was first determined. We derived Chiron's rotational lightcurve in 2013 from observations at the 1.23-m CAHA telescope and indeed its amplitude is smaller than in 1988. We also present a rotational lightcurve in 2000 from images taken at CASLEO 2.15-m telescope that is consistent with our predictions. Out of the two poles the l=(144+/-10) deg, b=(24+/-10) deg solution provides a better match to a compilation of rotational lightcurve amplitudes from the literature and those presented here. We also show that using this preferred pole, Chiron's long term brightness variations are compatible with a simple model that incorporates the changing brightness of the rings as the tilt angle with respect to the Earth changes with time. Also, the variability of the water ice band in Chiron's spectra in the literature can be explained to a large degree by an icy ring system whose tilt angle changes with time and whose composition includes water ice, analogously to the case of Chariklo. We present several possible formation scenarios for the rings from qualitative points of view and speculate on the reasons why rings might be common in centaurs. We speculate on whether the known bimodal color distribution of centaurs could be due to presence of rings and lack of them