On the asymptotic optimality of error bounds for some linear complementarity problems

We introduce strong B-matrices and strong B-Nekrasov matrices, for which some error bounds for linear complementarity problems are analyzed. In particular, it is proved that the bounds of García-Esnaola and Peña (Appl. Math. Lett. 22, 1071–1075, 2009) and of (Numer. Algor. 72, 435–445, 2016) are asymptotically optimal for strong B-matrices and strong B-Nekrasov matrices, respectively. Other comparisons with a bound of Li and Li (Appl. Math. Lett. 57, 108–113, 2016) are performed

B-Nekrasov matrices and error bounds for linear complementarity problems

The class of B-Nekrasov matrices is a subclass of P-matrices that contains Nekrasov Z-matrices with positive diagonal entries as well as B-matrices. Error bounds for the linear complementarity problem when the involved matrix is a B-Nekrasov matrix are presented. Numerical examples show the sharpness and applicability of the bounds

Kinematic study of planetary nebulae in NGC 6822

By measuring precise radial velocities of planetary nebulae (which belong to the intermediate age population), H II regions, and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine if both types of population share the kinematics of the disk of H I found in this galaxy. Spectroscopic data for four planetary nebulae were obtained with the high spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the Magellan telescope at Las Campanas Observatory. Data for other three PNe and one H II region were obtained from the SPM Catalog of Extragalactic Planetary Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 5-6 km s$^{-1}$. Data for three additional H II regions and a couple of A-type supergiant stars were collected from the literature. The heliocentric radial velocities of the different objects were compared to the velocities of the H i disk at the same position. From the analysis of radial velocities it is found that H II regions and A-type supergiants do share the kinematics of the H I disk at the same position, as expected for these young objects. On the contrary, planetary nebula velocities differ significantly from that of the H I at the same position. The kinematics of planetary nebulae is independent from the young population kinematics and it is closer to the behavior shown by carbon stars, which are intermediate-age members of the stellar spheroid existing in this galaxy. Our results are confirming that there are at least two very different kinematical systems in NGC 6822

Manufacturing to motorsport by students

[EN] The student s participation from the Polytechnic University of Valencia in the international competition Formula Student and the teacher s collaboration in the area of manufacturing processes has created a framework for the academic improvement. This article describes the conceptual and ideological framework of the project and also the new development.García Manrique, JA.; Peña Miñano, S.; Rivas Perea, ME. (2015). Manufacturing to motorsport by students. Procedia Engineering. 132:259-266. doi:10.1016/j.proeng.2015.12.493S25926613

Distribución biogeográfica de las especies de hidrozoos tecados bentónicos recogidas durante la campaña “Antártida 8611”

The biogeographical distribution of the benthic hydroid species collected during the Spanish Antarctic expedition Antártida 8611 has been studied. An inventory of the Antarctic and Magellan benthic thecate hydroid faunas, along with a comparison between the two, have been also carried out. 104 and 126 species of thecate hydroids have been considered in the Antarctic and Magellan areas, respectively. 72 species (69%) of the Antarctic species and 49 (39%) of the Magellan species are endemic. 23 species are present both in the Antarctic Region and in the Magellan area, representing 22% and 18% respectively, and indicating an important relationship between both faunas.Se ha estudiado la distribución biogeográfica de las especies de hidrozoos bentónicos recogidos durante la campaña de prospección científico-pesquera “Antártida 8611”. Asimismo, se ha realizado un inventario de la fauna de hidrozoos tecados bentónicos antárticos y magallánicos, habiéndose llevado a cabo una comparación entre ambas faunas. 104 y 126 especies de hidrozoos tecados se han considerado en las áreas antártica y magallánica respectivamente. 72 especies (69%) de las especies antárticas y 49 (39%) de las magallánicas son endémicas. 23 especies están presentes en ambas regiones, representando un 22% y un 18% respectivamente e indicando una importante relación entre ambas faunas

Sobre el origen de las razas caprinas españolas

Aún hoy, transcurridos más de 50 años desde que Aparicio Sánchez estableciera el origen de las razas caprinas españolas, su hipótesis está llena de contenido y actualidad. Las tres formas prehistóricas propuestas por este autor como troncos originarios, la Capra Prisca, la Capra Aegagrus y otra forma desconocida de procedencia africana son asumidas, así como las variedades Alpina y Pirenaica de la cabra Aegagrus anteriormente reconocida por Sanson (1903) y que fueron desarrolladas por este autor para el ámbito español. En este trabajo, matizamos las convergencias y divergencias con los autores antes mencionados, se reconoce al Íbice africano como posible forma prehistórica que intervino en la formación del sustrato a partir del cual se formaron nuestras razas y añadimos los posibles orígenes de razas actuales que no estaban caracterizadas ni reconocidas hace 50 años (Verata, Retinta Cacereña, Florida, Canaria, etc), si bien aún, no es posible determinar los orígenes de algunas de ellas ante los escasos conocimientos que se tienen de sus caracteres étnicos