A genetic algorithm to obtain the optimal recurrent neural network

AbstractSelecting the optimal topology of a neural network for a particular application is a difficult task. In the case of recurrent neural networks, most methods only induce topologies in which their neurons are fully connected. In this paper, we present a genetic algorithm capable of obtaining not only the optimal topology of a recurrent neural network but also the least number of connections necessary. Finally, this genetic algorithm is applied to a problem of grammatical inference using neural networks, with very good results

R&D expenditure in the EU: convergence or divergence?

This article examines the convergence of the R&D expenditure in the EU28 for 2004–2015. We initially run a sigma convergence analysis and the results show convergence in the total expenditure, due to the behaviour of the business and higher education sectors, despite government sector divergence. However, noticeable differences between the EU15 and 13 EU countries are apparent. The business enterprise sector is the main driver of EU15 R&D convergence, whereas for the EU13 this role is played by the government expenditure. In addition, the economic crisis has impacted differently on both groups. The club convergence approach allows us to explore these insights through individualized analysis and clusterization. Results for the EU28 show two clubs for the total expenditure, but the analysis of its components reveals a larger grouping. Our results evidence the necessity of revising the EU R&D policies towards greater coordination and resources, and the implementation of new instruments, due to the impact of this expenditure on growth, development and integration

The AMBRE Project: searching for the closest solar siblings

Finding solar siblings, that is, stars that formed in the same cluster as the Sun, will yield information about the conditions at the Sun's birthplace. We search for solar sibling candidates in AMBRE, the very large spectra database of solar vicinity stars. Since the ages and chemical abundances of solar siblings are very similar to those of the Sun, we carried out a chemistry- and age-based search for solar sibling candidates. We used high-resolution spectra to derive precise stellar parameters and chemical abundances of the stars. We used these spectroscopic parameters together with Gaia DR2 astrometric data to derive stellar isochronal ages. Gaia data were also used to study the kinematics of the sibling candidates. From the about 17000 stars that are characterized within the AMBRE project, we first selected 55 stars whose metallicities are closest to the solar value (-0.1 < [Fe/H] < 0.1 dex). For these stars we derived precise chemical abundances of several iron-peak, alpha- and neutron-capture elements, based on which we selected 12 solar sibling candidates with average abundances and metallicities between -0.03 to 0.03 dex. Our further selection left us with 4 candidates with stellar ages that are compatible with the solar age within observational uncertainties. For the 2 of the hottest candidates, we derived the carbon isotopic ratios, which are compatible with the solar value. HD186302 is the most precisely characterized and probably the most probable candidate of our 4 best candidates. Very precise chemical characterization and age estimation is necessary to identify solar siblings. We propose that in addition to typical chemical tagging, the study of isotopic ratios can give further important information about the relation of sibling candidates with the Sun. Ideally, asteroseismic age determinations of the candidates could solve the problem of imprecise isochronal ages.Comment: Accepted for publication in A&

Tratamiento asistido por artroscopia de las fracturas de radio distal

ResumenLa artroscopia proporciona una valoración directa de la superficie articular y permite detectar lesiones asociadas en las fracturas de la extremidad distal del radio. Su incorporación al tratamiento de estas fracturas ha supuesto un mejor control de la reducción de los trazos articulares, pero se trata de una técnica compleja que aún no está generalizada entre la mayoría de los cirujanos ortopédicos y/o de la mano y la muñeca.Se realiza una revisión y actualización de las ventajas, las indicaciones, las claves técnicas, los resultados y los datos científicos de su utilidad para el tratamiento de las fracturas del radio distal.AbstractArthroscopy provides a direct evaluation of the joint surface and enables associated injuries to be detected in fractures of the distal end of the radius. Although its incorporation into the treatment of these fractures has led to a better control in the reduction of joint traces, it is a complicated technique that is still not in general use by the majority of orthopaedic and/or hand and wrist surgeons.A review is presented here, as well as an update of the advantages, indications, the key techniques, results, and scientific data of its use in the treatment of distal radius fractures

Multinational tagging efforts illustrate regional scale of distribution and threats for east pacific green turtles (Chelonia mydas agassizii).

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tThis is the final version of the article. Available from Public Library of Science via the DOI in this record.To further describe movement patterns and distribution of East Pacific green turtles (Chelonia mydas agassizii) and to determine threat levels for this species within the Eastern Pacific. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite tracked green turtles (1996-2006). Three of these were tracked from their foraging grounds in the Gulf of California along the east coast of the Baja California peninsula to their breeding grounds in Michoacán (1337-2928 km). In addition, three post-nesting females were satellite tracked from Colola beach, Michoacán to their foraging grounds in southern Mexico and Central America (941.3-3020 km). A further six turtles were tracked in the Gulf of California within their foraging grounds giving insights into the scale of ranging behaviour. Turtles undertaking long-distance migrations showed a tendency to follow the coastline. Turtles tracked within foraging grounds showed that foraging individuals typically ranged up to 691.6 km (maximum) from release site location. Additionally, we carried out threat analysis (using the cumulative global human impact in the Eastern Pacific) clustering pre-existing satellite tracking studies from Galapagos, Costa Rica, and data obtained from this study; this indicated that turtles foraging and nesting in Central American waters are subject to the highest anthropogenic impact. Considering that turtles from all three rookeries were found to migrate towards Central America, it is highly important to implement conservation plans in Central American coastal areas to ensure the survival of the remaining green turtles in the Eastern Pacific. Finally, by combining satellite tracking data from this and previous studies, and data of tag returns we created the best available distributional patterns for this particular sea turtle species, which emphasized that conservation measures in key areas may have positive consequences on a regional scale.The work was supported by Earthwatch Institute, David and Lucile Packard Foundation, Wallace Research Foundation, PADI Foundation and the Arizona-Sonora Desert Museum. C. E. H. received a Masters degree bursary from the University of Exeter and the European Social Fund and would like to thank Consejo Nacional de Ciencia y Tecnología (Mexico) for support through a PhD scholarship. W. J. N. was supported by a Fulbright Fellowship and a Marshall Fellowship during the period field research in Baja California was conducted. B. J. G. is supported by the Darwin Initiative, European Social Fund and The Natural Environment Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Chapter 12 - Human settlements, infrastructure and spatial planning

Urbanization is a process that involves simultaneous transitions and transformations across multiple dimensions, including demographic, economic, and physical changes in the landscape. Each of these dimensions presents different indicators and definitions of urbanization. The chapter begins with a brief discussion of the multiple dimensions and definitions of urbanization, including implications for GHG emissions accounting, and then continues with an assessment of historical, current, and future trends across different dimensions of urbanization in the context of GHG emissions (12.2). It then discusses GHG accounting approaches and challenges specific to urban areas and human settlements. In Section 12.3, the chapter assesses the drivers of urban GHG emissions in a systemic fashion, and examines the impacts of drivers on individuals sectors as well as the interaction and interdependence of drivers. In this section, the relative magnitude of each driver's impact on urban GHG emissions is discussed both qualitatively and quantitatively, and provides the context for a more detailed assessment of how urban form and infrastructure affect urban GHG emissions (12.4). Here, the section discusses the individual urban form drivers such as density, connectivity, and land use mix, as well as their interactions with each other. Section 12.4 also examines the links between infrastructure and urban form, as well as their combined and interacting effects on GHG emissions. Section 12.5 identifies spatial planning strategies and policy instruments that can affect multiple drivers, and Section 12.6 examines the institutional, governance, and financial requirements to implement such policies. Of particular importance with regard to mitigation potential at the urban or local scale is a discussion of the geographic and administrative scales for which policies are implemented, overlapping, and / or in conflict. The chapter then identifies the scale and range of mitigation actions currently planned and / or implemented by local governments, and assesses the evidence of successful implementation of the plans, as well as barriers to further implementation (12.7). Next, the chapter discusses major co-benefits and adverse side-effects of mitigation at the local scale, including opportunities for sustainable development (12.8). The chapter concludes with a discussion of the major gaps in knowledge with respect to mitigation of climate change in urban areas (12.9)

The Gaia-ESO Survey: metallicity of the Chamaeleon I star forming region

Context. Recent metallicity determinations in young open clusters and star-forming regions suggest that the latter may be characterized by a slightly lower metallicity than the Sun and older clusters in the solar vicinity. However, these results are based on small statistics and inhomogeneous analyses. The Gaia-ESO Survey is observing and homogeneously analyzing large samples of stars in several young clusters and star-forming regions, hence allowing us to further investigate this issue. Aims. We present a new metallicity determination of the Chamaeleon I star-forming region, based on the products distributed in the first internal release of the Gaia-ESO Survey. Methods. 48 candidate members of Chamaeleon I have been observed with the high-resolution spectrograph UVES. We use the surface gravity, lithium line equivalent width and position in the Hertzsprung-Russell diagram to confirm the cluster members and we use the iron abundance to derive the mean metallicity of the region. Results. Out of the 48 targets, we confirm 15 high probability members. Considering the metallicity measurements for 9 of them, we find that the iron abundance of Chamaeleon I is slightly subsolar with a mean value [Fe/H]=-0.08+/-0.04 dex. This result is in agreement with the metallicity determination of other nearby star-forming regions and suggests that the chemical pattern of the youngest stars in the solar neighborhood is indeed more metal-poor than the Sun. We argue that this evidence may be related to the chemical distribution of the Gould Belt that contains most of the nearby star-forming regions and young clusters.Comment: 13 pages, 11 figures, 3 tables, Accepted for publication in Astronomy & Astrophysic

Auge y colapso de la demanda de viviendas en España : factores determinantes

En este artículo se presenta un modelo de demanda de viviendas que permite analizar las causas que motivaron el boom inmobiliario protagonizado por la economía española, así como su posterior colapso. Según nuestro modelo, el boom tuvo su origen en el alza especulativa de precios, que produjo un doble efecto. Por un lado, el aumento de la riqueza inmobiliaria incrementó la capacidad financiera familiar, induciendo una mayor propensión al endeudamiento y a la inversión residencial. Por otro, el hecho de que la revalorización de la vivienda superara por momentos la cuota hipotecaria indujo un incremento adicional de la demanda de aquéllas. Sin embargo, estas fuerzas comenzaron a jugar en sentido contrario tras la explosión de la burbuja, provocando un brusco desplome de las compraventas. El modelo pone de relieve que la secular preferencia de los españoles por la vivienda en propiedad tenía un fundamento económico que ahora ha desaparecidoThis article presents a model for the demand for housing which allows one to analyze the determinants of the housing boom and bust experienced by the Spanish economy. According to this model, the boom was caused by a speculative increase in prices, which yielded two effects: on the one hand, the rise in wealth associated with the value of real estate increased households’ financial capacity, leading to a higher propensity to engage in debt and to invest in real estate. On the other hand, the fact that the appreciation in the value of housing was larger at certain times than the value of the mortgage to be paid, led to an even larger increase in the demand for housing. However, these forces began to act in the opposite direction after the bust of the housing bubble, causing an abrupt reduction in the demand for real estate. The model shows that the long term preference of Spaniards for house ownership rested on economic foundations which have now disappeare

Auge y colapso de la demanda de viviendas en España : factores determinantes

En este artículo se presenta un modelo de demanda de viviendas que permite analizar las causas que motivaron el boom inmobiliario protagonizado por la economía española, así como su posterior colapso. Según nuestro modelo, el boom tuvo su origen en el alza especulativa de precios, que produjo un doble efecto. Por un lado, el aumento de la riqueza inmobiliaria incrementó la capacidad financiera familiar, induciendo una mayor propensión al endeudamiento y a la inversión residencial. Por otro, el hecho de que la revalorización de la vivienda superara por momentos la cuota hipotecaria indujo un incremento adicional de la demanda de aquéllas. Sin embargo, estas fuerzas comenzaron a jugar en sentido contrario tras la explosión de la burbuja, provocando un brusco desplome de las compraventas. El modelo pone de relieve que la secular preferencia de los españoles por la vivienda en propiedad tenía un fundamento económico que ahora ha desaparecidoThis article presents a model for the demand for housing which allows one to analyze the determinants of the housing boom and bust experienced by the Spanish economy. According to this model, the boom was caused by a speculative increase in prices, which yielded two effects: on the one hand, the rise in wealth associated with the value of real estate increased households’ financial capacity, leading to a higher propensity to engage in debt and to invest in real estate. On the other hand, the fact that the appreciation in the value of housing was larger at certain times than the value of the mortgage to be paid, led to an even larger increase in the demand for housing. However, these forces began to act in the opposite direction after the bust of the housing bubble, causing an abrupt reduction in the demand for real estate. The model shows that the long term preference of Spaniards for house ownership rested on economic foundations which have now disappeare