A new special class of Petrov type D vacuum space-times in dimension five

Using extensions of the Newman-Penrose and Geroch-Held-Penrose formalisms to five dimensions, we invariantly classify all Petrov type $D$ vacuum solutions for which the Riemann tensor is isotropic in a plane orthogonal to a pair of Weyl alligned null directionsComment: 4 pages, 1 table, no figures. Contribution to the proceedings of the Spanish Relativity Meeting 2010 held in Granada (Spain

Formation of asymmetric arms in barred galaxies

ABSTRACTWe establish a dynamical mechanism to explain the origin of the asymmetry between the arms observed in some barred disc galaxies, where one of the two arms emanating from the bar ends is very well defined, while the second one displays a ragged structure, extending between its ridge and the bar. To this purpose, we study the invariant manifolds associated with the Lyapunov periodic orbits around the unstable equilibrium points at the ends of the bar. Matter from the galaxy centre is transported along these manifolds to the periphery, forming this way the spiral arms that emanate from the bar ends. If the mass distribution in the galaxy centre is not homogeneous, because of an asymmetric bar with one side stronger than the other, or because of a non-centred bulge, the dynamics about the two unstable Lagrange points at the ends of the bar will not be symmetric as well. One of their invariant manifolds becomes more extended than the other, enclosing a smaller section and the escaping orbits on it are fewer and dispersed in a wider region. The result is a weaker arm and more ragged than the one at the other end of the bar

Forming first-ranked early-type galaxies through hierarchical dissipationless merging

We have developed a computationally competitive N-body model of a previrialized aggregation of galaxies in a flat LambdaCDM universe to assess the role of the multiple mergers that take place during the formation stage of such systems in the configuration of the remnants assembled at their centres. An analysis of a suite of 48 simulations of low-mass forming groups (of about 1E13 solar masses) demonstrates that the gravitational dynamics involved in their hierarchical collapse is capable of creating realistic first-ranked galaxies without the aid of dissipative processes. Our simulations indicate that the brightest group galaxies (BGGs) constitute a distinct population from other group members, sketching a scenario in which the assembly path of these objects is dictated largely by the formation of their host system. We detect significant differences in the distribution of Sersic indices and total magnitudes, as well as a luminosity gap between BGGs and the next brightest galaxy that is positively correlated with the total luminosity of the parent group. Such gaps arise from both the grow of BGGs at the expense of lesser companions and the decrease in the relevance of second-ranked objects in equal measure. This results in a dearth of intermediate-mass galaxies which explains the characteristic central dip detected in their luminosity functions in dynamically young galaxy aggregations. The fact that the basic global properties of our BGGs define a thin mass fundamental plane strikingly similar to that followed giant early-type galaxies in the local universe reinforces confidence in the results obtained.Comment: 25 pages, 14 figures, 3 tables. Accepted to MNRA

Respuestas vegetativa, productiva y calidad del aceite a la aplicación foliar de P y K a olivos “Arbequinos” y “Picual”

A completed hedgerow of cv. Arbequina and a youth vase trained orchard of cv. Picual were fertilized with foliar applications of Phosphorus (P) or Potassium (K) throughout four seasons. The orchards were located near Valdepeñas in the dry area of La Mancha (Spain). Vegetative growth, yield and oil quality were evaluated. Foliar treatments did not increase P or K leaf concentration. Most of the evaluated parameters were not significantly affected by treatments. It was observed that the P treatment increased olive growth and oil yield in both orchards and in certain seasons due to an increment in fruit number. P and K application significantly increased ‘Arbequina’ olive and oil yield in 2008 when spring was wetter than the other years. Oil quality was not modified by fertilizer treatments in the ‘Arbequina’orchard. However, oxidative stability was negatively affected by P and K treatments in ‘Picual’. Oil extraction could be negatively affected by treatments because of the increase in the water content in the fruit obtained from both orchards.Un olivar en seto completamente formado de la variedad Arbequina y otro olivar en vaso joven de la variedad Picual fueron tratados vía foliar con Fósforo (P) y Potasio (K) durante cuatro años. Los olivares estuvieron localizados cerca de Valdepeñas, en la zona árida de La Mancha (España). Se evaluaron el crecimiento vegetativo, el rendimiento y la calidad del aceite. Los tratamientos foliares no aumentaron los niveles foliares de P y K. La mayoría de parámetros de crecimiento y producción evaluados no se vieron afectados por los tratamientos. En ambos olivares y en algún año del ensayo, el tratamiento con P incrementó el crecimiento y el rendimiento, debido al incremento en el número de frutos. Las aplicaciones de P y K aumentaron significativamente el rendimiento en aceituna y aceite en Arbequina en 2008, cuando la primavera fue más húmeda que el resto de años. Los tratamientos no modificaron la calidad del aceite obtenido en ‘Arbequina’. Sin embargo, en ‘Picual’ los tratamientos con P y K afectaron negativamente a la estabilidad oxidativa del aceite. La extracción del aceite podría verse perjudicada por los tratamientos, debido al incremento en el contenido de agua en el fruto obtenido en ambos olivares

Associations between sedentary time, physical activity and bone health among older people using compositional data analysis

Introduction : Aging is associated with a progressive decrease in bone mass (BM), and being physical active is one of the main strategies to combat this continuous loss. Nonetheless, because daily time is limited, time spent on each movement behavior is co-dependent. The aim of this study was to determine the relationship between BM and movement behaviors in elderly people using compositional data analysis. Methods : We analyzed 871 older people [395 men (76.9 +/- 5.3y) and 476 women (76.7 +/- 4.7y)]. Time spent in sedentary behavior (SB), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA), was assessed using accelerometry. BM was determined by bone densitometry (DXA). The sample was divided according to sex and bone health indicators. Results : The combined effect of all movement behaviors (PA and SB) was significantly associated with whole body, leg and femoral region BM in the whole sample (p<0.05), with leg and pelvic BM (p<0.05) in men and, with whole body, arm and leg BM (p<0.05) in women. In men, arm and pelvic BM were negatively associated with SB and whole body, pelvic and leg BM were positively associated with MVPA (p<0.05). In women, whole body and leg BM were positively associated with SB. Arm and whole body BM were positively associated and leg BM was negatively associated with LPA and arm BM was negatively associated with MVPA (p<0.05). Women without bone fractures spent less time in SB and more in LPA and MVPA than the subgroup with bone fractures. Conclusion : We identified that the positive effect of MVPA relative to the other behaviors on bone mass is the strongest overall effect in men. Furthermore, women might decrease bone fracture risk through PA increase and SB reduction, despite the fact that no clear benefits of PA for bone mass were found

Redescription of Caprella hirsuta Mayec 1890 (Crustacea, Amphipoda, Caprellidea) from the Strait of Gibraltar

Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription.Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription.Caprella hirsuta Mayer, 1890 is redescribed based on specimens collected from the Strait of Gibraltar (Southern Spain-Northern Africa) during a study of the amphipod fauna from these coasts. Careful examination of these caprellids revealed differences with the previous descriptions, mainly the structure of gnathopod 2, pereopods and abdomen. Key words: Crustacea, Amphipoda, Caprellidea, Caprella hirsuta, Strait of Gibraltar, Redescription

Valoración eco-pastoral de los pastos del Monte Lakora (Navarra, Pirineo occidental)

7 páginasSe aplica el método del índice eco-pastoral, desarrollado en trabajos previos, a los pastos del monte Lakora (Navarra) situado en el Pirineo occidental. Se ha utilizado un mapa de vegetación digitalizado (escala 1/5.000). Las comunidades de Primulion intricatae, Nardion strictae, brezales subalpinos de Vaccinium uliginosum y pastos de Festuca eskia son los que tienen un mayor valor ecológico. Las comunidades de Bromion erecti y Primulion intricatae son las que tienen un mayor valor pastoral potencial. El monte Lakora presenta un valor ecológico mayor que el pastoral, por lo que se justifica su inclusión dentro del Lugar de Importancia Comunitaria (LIC) “ES2200001 Larra-Aztaparreta” así como la priorización de su conservación mediante el adecuado manejo ganadero.Peer reviewe