Statistical analysis of Ni nanowires breaking processes: a numerical simulation study

A statistical analysis of the breaking behavior of Ni nanowires is presented. Using molecular dynamic simulations, we have determined the time evolution of both the nanowire atomic structure and its minimum cross section (Sm(t)). Accumulating thousands of independent breaking events, Sm histograms are built and used to study the influence of the temperature, the crystalline stretching direction and the initial nanowire size. The proportion of monomers, dimers and more complex structures at the latest stages of the breaking process are calculated, finding important differences among results obtained for different nanowire orientations and sizes. Three main cases have been observed. (A) [111] stretching direction and large nanowire sizes: the wire evolves from more complex structures to monomers and dimers prior its rupture; well ordered structures is presented during the breaking process. (B) Large nanowires stretched along the [100] and [110] directions: the system mainly breaks from complex structures (low probability of finding monomers and dimers), having disordered regions during their breakage; at room temperature, a huge histogram peak around Sm=5 appears, showing the presence of long staggered pentagonal Ni wires with ...-5-1-5-... structure. (C) Initial wire size is small: strong size effects independently on the temperature and stretching direction. Finally, the local structure around monomers and dimmers do not depend on the stretching direction. These configurations differ from those usually chosen in static studies of conductance.Comment: 18 pages, 13 figure

The illegal wildlife trade is a likely source of alien species

The illegal wildlife trade is driving biodiversity declines worldwide, yet its role in transporting alien species with a high likelihood of establishment is seldom considered. We demonstrate the threat posed by the illegal reptile trade in Australia. We modeled the establishment success of alien reptiles in Australia, revealing the importance of both minimum number of release events and the body length of the species. Using our model, we screened 28 alien reptiles illegally traded in Victoria, Australia. Establishment risk varied widely across species, and a whole-pathway analysis revealed that 5 out of the 28 species (17.9%) are likely to become established if released. The global dimension of the illegal wildlife trade calls for a tight transnational collaboration, via multilateral cooperation agreements arranging the share of resources. Complementary to this, we encourage conducting campaigns to raise public awareness about the risk and legal consequences of participating in the wildlife black market.Pablo García-Díaz, Joshua V. Ross, Andrew P. Woolnough, and Phillip Casse

Gravitino Dark Matter and Neutrino Masses in Partial Split Supersymmetry

Partial Split Supersymmetry with bilinear R-parity violation allows to reproduce all neutrino mass and mixing parameters. The viable dark matter candidate in this model is the gravitino. We study the hypothesis that both possibilities are true: Partial Split Supersymmetry explains neutrino physics and that dark matter is actually composed of gravitinos. Since the gravitino has a small but non-zero decay probability, its decay products could be observed in astrophysical experiments. Combining bounds from astrophysical photon spectra with the bounds coming from the mass matrix in the neutrino sector we derive a stringent upper limit for the allowed gravitino mass. This mass limit is in good agreement with the results of direct dark matter searches.Comment: 22 pages, 3 figure

The structure of algebraic covariant derivative curvature tensors

We use the Nash embedding theorem to construct generators for the space of algebraic covariant derivative curvature tensors

The merger history of massive spheroids since z~1 is size independent

Using a compilation of 379 massive (stellar mass M > 10^{11} M_Sun) spheroid-like galaxies from the near-infrared Palomar/DEEP-2 survey, we have probed, up to z~1, whether the presence of companions depends on the size of the host galaxies. We have explored the presence of companions with mass ratios down to 1:10 and 1:100, with respect to the central massive galaxy, and within a projected distance of 30, 50 and 100 kpc of these objects. We find evidence for these companions being equally distributed around both compact and extended massive spheroids. This finding suggests that, at least since z~1, the merger activity in these objects is rather homogeneous across the whole population and its merger history is not affected for the size of the host galaxy. Our result could indicate that both compact and extended massive spheroid-like galaxies are growing in size at the same rate.Comment: 9 pages, 6 figures, accepted for publication in MNRA

Enfermedades y fisiopatías que afectan a la calidad del ajo en postcosecha

Las enfermedades y fisiopatías que afectan al ajo pueden llegar a ocasionar importantes pérdidas en postcosecha, de vital importancia cuando el producto se destina a la exportación a mercados que cada día son más exigentes. En 2008, distintos agricultores de varios municipios de Castilla y León detectaron bulbos de ajo que presentaban síntomas de podredumbre húmeda durante el almacenamiento. Posteriormente, en el año 2009, esta misma podredumbre se observó también en las provincias de Albacete y Cuenca y en muestras procedentes de Córdoba. Hasta la fecha se ha identificado a Fusarium proliferatum como el agente causal de la podredumbre del diente

Efecto de la suplementación con concentrado de soja entera extrusionada en vacas Jersey en pastoreo sobre el contenido de ácido linoléico conjugado en la leche

Contradictory results has been found on the effects of soybean supplementation and conjugated linoleic acid (CLA) content in milk on feeding systems based on fresh forage The objective of the study was to evaluate the effect of a dietary supplement with different quantities of extruded whole soybean on the production and composition of milk, and CLA concentration or their isomers in Jersey cows under pasture conditions. Twenty-one Jersey cows were randomly assigned into 3 groups of 7 animals each. The cows were supplemented with a dietary concentrate (5 kg d–1), and each group received one of the three next treatments: control without soybean (0-SB), with extruded whole soybean at 0.5 kg d–1 (0.5-SB) or at 1 kg d–1 (1-SB). The basic diet was a pasture composed of Lolium perenne (70%), Trifolium repens (25%) and other species. The duration of the study was 75 d. Milk production (p = 0.706) and protein production (p = 0.926) were not affected by treatments. Fat (p = 0.015) and protein (p = 0.045) content as well as fat production (p = 0.010) were lower in the 1-SB group. There was no effect of the inclusion of extruded soybean on total CLA content (p = 0.290) or the content of cis-9, trans-11 (p = 0.582), trans-10, cis-12 (p = 0.136) and cis-10, cis-12 (p = 0.288) isomers. However, concentrations of all isomers were affected by the nutritional quality of the pasture, with low values observed at greater maturity stages of pastureleche es contradictorio. El objetivo de este estudio fue evaluar en vacas Jersey en pastoreo, el efecto de la suplementación de un concentrado con diferentes cantidades de soja entera extrusionada sobre la producción de leche y su composición, especialmente sobre el contenido en CLA y sus isómeros. 21 vacas Jersey fueron divididas al azar en 3 grupos de 7 animales cada uno. Los animales fueron suplementados con un concentrado (5 kg d–1) y a cada grupo se le asignó uno de los tres siguientes tratamientos: control sin soja (0-SB), con 0.5 kg d–1 de soja (0.5-SB) y con 1 kg d–1 de soja (1-SB). La base de la alimentación fue el pasto, compuesto mayoritariamente por Lolium perenne (70%) y Trifolium repens (25%). La duración del estudio fue de 75 días. La producción de leche (p = 0.706) y la producción de proteína (p = 0.926) no se vieron afectados. Los porcentajes de grasa (p = 0.015) y proteína (p = 0.045) y la producción de grasa (p = 0.010) fueron más bajos en el grupo 1-SB. Las cantidades de soja no modificaron los contenidos de CLA total (p = 0.290) y de los isómeros cis-9, trans-11 (p = 0.582), trans-10, cis-12 (p = 0.136) y cis-10, cis-12 (p = 0.288), pero si fueron afectados por la calidad nutritiva del pasto, observándose menores valores al aumentar la madurez del pasto

A complete 0D thermodynamic predictive model for direct injection diesel engines

[EN] Ideal models provide the simplest way to reproduce internal combustion engine (ICE) cycles, but they usually do not represent with sufficient accuracy the actual behaviour of an ICE. A suitable alternative for research and development applications is provided by zero-dimensional (0D) thermodynamic models. Such models are very useful for predicting the instantaneous pressure and temperature in the combustion chamber, which in turn allows the prediction of engine operation characteristics. However, they use simplifying hypotheses which lead, in some cases, to a lack of accuracy or a limited predictive capability.This paper describes a 0D single-zone thermodynamic model that takes into account the heat transfer to the chamber walls, the blow-by leakage, the fuel injection and engine deformations, along with the instantaneous change in gas properties. Special attention has been paid to the description of the specific sub-models that have been used for the calculation of the energy and mass equations terms. The procedures followed for the estimation of some mechanical and heat transfer parameters and the combustion model fitting are also detailed. After the fitting, the model was validated in different operation points in a 4-cylinder 2-l DI diesel engine, showing a good capability for accurate predictions of engine performance and the gas state in the closed cycle. © 2011 Elsevier Ltd.The authors thank the Universitat Politecnica de Valencia (PAID-06-09) and Generalitat Valenciana (GV/2010/045) for their valuable support to this work and the referees for their worthy comments.Payri González, F.; Olmeda, P.; Martín Díaz, J.; García Martínez, A. (2011). A complete 0D thermodynamic predictive model for direct injection diesel engines. Applied Energy. 88:4632-4641. doi:10.1016/j.apenergy.2011.06.005S463246418