Effects of experimental tail shortening on the phenotypic condition of barn swallows Hirundo rustica: Implications for tail-length evolution

Some studies have suggested that tail streamers in the barn swallow Hirundo rustica may have been elongated 10-12 mm by sexual selection, but according to other studies, the length of these feathers is at the aerodynamic optimum or very close to it. To shed light on this issue, outermost tail feathers were experimentally shortened in male and female barn swallows by 1, 11 or 21 mm. Changes in four physiological parameters commonly used to estimate phenotypic condition in birds (weight, erythrocyte sedimentation rate, blood leukocyte concentration and heterophil/lymphocyte ratio) were checked one month later. Health improved (blood leukocyte concentration decreased) in the group of birds with tails shortened by 11 mm (both males and females), but body condition deteriorated (weight decreased) compared to the other two experimental groups. There was no significant effect of tail-length manipulation on the other two physiological parameters. These contradictory results suggest trade-offs between components of phenotypic condition. Possible negative relationships between condition-related traits imply that using one or very few physiological parameters to estimate phenotypic condition might not be appropriate. The most plausible explanation for the turning point in phenotypic condition when streamers were shortened by 11 mm is that these feathers are 7-15 mm longer than the aerodynamic optimum in both sexes. Therefore, our results are consistent with the hypothesis that tail streamers have been elongated 10-12 mm by sexual selection. This conclusion disagrees with a previous study on the effect of experimental tail shortening on haematocrit, but the complexity of interpreting changes in haematocrit might account for this discrepancy. © 2014 The Authors.The study was funded by the Andalusian Regional Government (Acc. Coord. 2001) and by the Spanish Ministry of Science and Technology and the European Regional Development Fund (projects BOS2001-1717 and CGL2008-00137/BOS).Peer Reviewe

Dispersive ππ→KKˉ\pi\pi\rightarrow K\bar K amplitude and giant CP violation in B to three light-meson decays at LHCb

The LHCb collaboration has recently reported the largest CP violation effect from a single amplitude, as well as other giant CP asymmetries in several $B$-meson decays into three charmless light mesons. It is also claimed that this is predominantly due to $\pi\pi\rightarrow K\bar K$ rescattering in the final state, particularly in the 1 to 1.5 GeV region. In these analyses the $\pi\pi\rightarrow K\bar K$ amplitude is by default estimated from the $\pi\pi$ elastic scattering amplitude and does not describe the existing $\pi\pi\rightarrow K\bar K$ scattering data. Here we show how the recent model-independent dispersive analysis of $\pi\pi\rightarrow K\bar K$ data can be easily implemented in the LHCb formalism. This leads to a more accurate description of the asymmetry, while being consistent with the measured scattering amplitude and confirming the prominent role of hadronic final state interactions, paving the way for more elaborated analyses.Comment: 9 pages, 6 figures. Minor corrections and discussions were added. Extended appendix with an additional improved model of the S-wave. Final version to appear in Phys.Rev.Let

Anisotropic Dirac cones in monatomic hexagonal lattices

In the last few years, the fascinating properties of graphene have been thoroughly investigated. The existence of Dirac cones is the most important characteristic of the electronic band-structure of graphene. In this theoretical paper, hexagonal monolayers of silicon (h-Si) and germanium (h-Ge) are examined using density functional theory, within the generalized gradient approximation. Our numerical results indicate that both h-Si and h-Ge are chemically stable. The lattice parameters, electronic dispersion relations and densities of states for these systems are reported. The electronic dispersion relations display Dirac cones with the symmetry of an equilateral triangle (the group D$_3$) in the vicinity of the K points. Hence, the Fermi velocity depends on the wave vector direction around $K$ points. Fermi velocities for holes and electrons are significantly different. The maximum and minimum Fermi velocities are also reported.Comment: 7 pages, 9 figures. Accepted for publication in The European Physical Journal B (EPJB

Determinación del eje de la carretera y la distancia de visibilidad utilizando datos GPS y herramientas SIG

Hoy en día, tanto en el proceso de diseño de las carreteras como en el análisis del funcionamiento de las ya construidas, se está dando cada vez más importancia a la seguridad vial. Entre los distintos aspectos que se consideran se encuentra la distancia de visibilidad. Por otra parte, uno de los problemas que aparecen en la práctica al tratar de analizar carreteras en servicio es la falta de datos de la geometría del eje que estén actualizados y tengan la precisión requerida. En esta comunicación se presenta un procedimiento para determinar el eje de la carretera mediante información GPS y calcular la distancia de visibilidad aplicando herramientas SIG. El procedimiento se ha aplicado a un tramo de carretera convencional de doble sentido de circulación. El método propuesto puede ser especialmente útil en aquellas carreteras en servicio y de las que, por no contar con la información sobre su trazado (original o posteriores modificaciones), no es posible utilizar los programas de diseño de carreteras para el cálculo de la distancia de visibilidad.Nowadays road safety aspects are very important, both for the designing process and for the analysis of already built roads. Sight distance is one of the most important road safety aspects to consider. On the other hand, the geometric definition of already built roads is one of the most difficult issues that arise in practice. This road geometry must be accurate and up to date. In this paper, a procedure to determine the alignment of a road using a GPS and to calculate sight distances using GIS tools is presented. Also, the use of this procedure in a two-lane rural road is described. The proposed method can be especially useful for those roads whose design data are not available because, on them, road design software could not be used for sight distance calculation

Twin disc assessment of wear regime transitions and rolling contact fatigue in R400HT – E8 pairs

Twin disc tests were carried out to evaluate the wear resistance and Rolling Contact Fatigue (RCF) of premium R400HT rail samples in contact with E8 wheel samples. The wear rate and friction coefficient were correlated with the frictional work expended at the contact interface (the Tgamma approach). Accelerated RCF tests were also carried out on the premium R400HT rail and the results were compared to those obtained for standard R260 rail. The wear rates of rail samples were consistently lower than those reported in the literature for other contacting pairs in which the rail material studied is softer than R400HT. Also, the energy needed for the transition from the moderate to severe wear regime significantly increased for the hardened rail. Fatigue cracks were shallower for R400HT when compared with standard rail material. Hardened rails also showed lower mean spacing between fatigue cracks. This new information can be used to improve wear simulations of wheels and rails by using more realistic wear equations

Metallic spin-glasses beyond mean-field: An approach to the impurity-concentration dependence of the freezing temperature

A relation between the freezing temperature ($T^{}_{\rm g}$) and the exchange couplings ($J^{}_{ij}$) in metallic spin-glasses is derived, taking the spin-correlations ($G^{}_{ij}$) into account. This approach does not involve a disorder-average. The expansion of the correlations to first order in $J^{}_{ij}/T^{}_{\rm g}$ leads to the molecular-field result from Thouless-Anderson-Palmer. Employing the current theory of the spin-interaction in disordered metals, an equation for $T^{}_{\rm g}$ as a function of the concentration of impurities is obtained, which reproduces the available data from {\sl Au}Fe, {\sl Ag}Mn, and {\sl Cu}Mn alloys well.Comment: 4 figures. This is a strongly revised version, where several aspects have been improved, and the equation for the freezing temperature has been refined. It is equivalent to the published version in J. Phys.: Condens. Matter 25 (2013) 13600

Influencia de la inclinación acetabular en la luxación de la artroplastia parcial de cadera

La luxación de la prótesis parcial de cadera, representa en la actualidad un grave problema de incapacidad para el paciente, debido no solo, a la complicación de la marcha en sí, sino a todas aquellas derivadas de la estancia hospitalaria de estos pacientes en nuestros centros. Respecto a la vía de abordaje, se ha sentado una mayor incidencia de luxaciones en la vía posterolateral, frente a las anteriores o laterales transtrocantéreas en decúbito supino. Objetivo: evaluar la influencia del ángulo de inclinación anatómico del acetábulo, techo y cobertura en la luxación de la artroplastia parcial de cadera. Material y método: el estudio incluyó un total de 718 pacientes intervenidos por fractura cervical de fémur, durante los años de 1992 a 2005. Las prótesis parciales implantadas fueron del modelo Thompson; los tipos de vías de abordaje quirúrgico utilizados fueron; la anterior de Smith Petersen, y la posterior de Gibson Moore. Se realizaron las mediciones radiográficas del ángulo formado entre las línea trazada en el borde externo del acetábulo y la línea biisquiática. Resultados: Del total de pacientes incluidos en el estudio el número de luxaciones fue de 24 prótesis, lo que representa el 3,3 %. La edad media fue de 84 años, y un intervalo de 76 a 92 años. El sexo predominante fue el femenino con un 83%. La vía más utilizada fue la anterior con un 67 %. El mayor porcentaje de luxación fue para aquellas pacientes con un ángulo de inclinación anatómico del acetábulo de > 55º. El tiempo medio seguimiento hasta producirse la luxación fue de 35 días y un intervalo entre 1 a 89 días. El tratamiento más frecuente fue el conservador 88%. Conclusión: El presente estudio demuestra que la luxación temprana de una prótesis parcial de cadera está directamente relacionado con un ángulo de inclinación anatómico del acetábulo mayor de 55º.The dislocation of partial hip replacements represents an important postoperative complication. Apart from the most important problem which is patient mobility, another aspect is the prolonged hospital stay detrimental to patient health and the evonawy of hospital. With respect to the incidence of pos- toperative dislocations and the type of surgical approach, it seated that there is a greater incidence using the lateroposterior hip sur- gical approach, in comparision to the anterior or lateral access. Objective: To evidence the influence of acetabular inclination in postoperative dislocations of partial hip arthroplasty. Methods: A study involuing 718 cases of intervened femoral neck fractures using Thompson endoprosthesis during the period including 1992 to 2005.With respect to type of surgical approaches, these included the Smith-Petersen anterior and the Gibson-Moore posterior access. The acetabular inclination was measurements radiologi- cally, obtaining the angle between the bi-ischial line and the exter- nal border of the acetabulum. Results: A total of twentyfour (24) prosthesis suffered dislocation, with respect to the total of seven hundred and eighteen (718) patients intervened for partial hip arth- roplasty, representing 3,3% of the total. The average age for dislocated arthroplasties was 84 years, with a range between 76-92 years, and the predominant sex was female. Concerning surgical access, the anterior was the most frecuently used (67%). There was found to be a greater percentage of dislo- cated arthroplasties when the angle of acetabular inclination exce- eded fifty five (55º) degrees. The average time elapsed before dis- location was diagnosed included a 35 days time period, with a range between to 89 days. The most frequent management of pos- toperative dislocations was conservative treatment. Conclusion: This study demonstrates that when the acetabular inclination is greater than 55º, there is a greater incidence of early dislocation of partial hip replacements

A Catalog of Architectural Tactics for Cyber-Foraging

Mobile devices have become for many the preferred way of interacting with the Internet, social media and the enterprise. However, mobile devices still do not have the computing power or battery life that will allow them to perform effectively over long periods of time or for executing applications that require extensive communication or computation, or low latency. Cyber-foraging is a technique enabling mobile devices to extend their computing power and storage by offloading computation or data to more powerful servers located in the cloud or in single-hop proximity. This paper presents a catalog of architectural tactics for cyber-foraging that was derived from the results of a systematic literature review on architectures for cyber-foraging systems. Elements of the architectures identified in the primary studies were codified in the form of Architectural Tactics for Cyber-Foraging. These tactics will help architects extend their design reasoning towards cyber-foraging as a way to support the mobile applications of the present and the future