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San Sebastián de los Reyes, Spain

Colmenero J.,Donostia International Physics Center | Colmenero J.,University of the Basque Country | Alvarez F.,Apartado | Alvarez F.,University of the Basque Country | And 2 more authors.
Journal of Chemical Physics

In a recent paper [V. N. Novikov, K. S. Schweizer, and A. P. Sokolov, J. Chem. Phys. 138, 164508 (2013)]10.1063/1.4802771 a simple analytical ansatz has been proposed to describe the momentum transfer (Q) dependence of the collective relaxation time of glass-forming systems in a wide Q-range covering the region of the first maximum of the static structure factor S(Q) and the so-called intermediate length scale regime. In this work we have generalized this model in order to deal with glass-forming systems where the atomic diffusive processes are sub-linear in nature. This is for instance the case of glass-forming polymers. The generalized expression considers a sub-linear jump-diffusion model and reduces to the expression previously proposed for normal diffusion. The generalized ansatz has been applied to the experimental results of the Q- and temperature-dependence of polyisobutylene (PIB), which were previously published. To reduce the number of free parameters of the model to only one, we have taken advantage of atomistic molecular dynamics simulations of PIB properly validated by neutron scattering results. The model perfectly describes the experimental results capturing both, Q- and temperature-dependences. Moreover, the model also reproduces the experimental Q-dependence of the effective activation energy of the collective relaxation time in the temperature range of observation. This non-trivial result gives additional support to the way the crossover between two different relaxation mechanisms of density fluctuations is formulated in the model. © 2013 AIP Publishing LLC. Source

Soderstrom L.,Norwegian University of Science and Technology | Hagborg A.,Field Museum | Von Konrat M.,Field Museum | Bartholomew-Began S.,West Chester University | And 36 more authors.

A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora. The checklist is derived from a working data set centralizing nomenclature, taxonomy and geography on a global scale. Prior to this effort a lack of centralization has been a major impediment for the study and analysis of species richness, conservation and systematic research at both regional and global scales. The success of this checklist, initiated in 2008, has been underpinned by its community approach involving taxonomic specialists working towards a consensus on taxonomy, nomenclature and distribution. Source

Stature estimation is one of the four attributes of the biological profile obtained from human skeletal remains. The length of the long bones has been consistently used to estimate stature from regression equations, but these may be useless when dealing with fresh or decomposed mutilated remains. Until recently, there was no consistent assessment of the reliability of measurements of the sternum for stature estimation. The purpose of this paper is to test previously developed regression formulae for stature based on measurements of the dry sternum and to assess the reliability of measurements of the fresh sternum in estimating stature. The formulae developed by Menezes et al. and Singh et al. were applied to a sample of 5 known stature skeletons from the identified human skeletal collection curated at the National Museum of Natural History, in Lisbon, Portugal. Testing of these formulae showed that estimated stature confidence intervals do not allow discrimination between individuals with similar stature. The length of the fresh sternum was measured on a sample of 45 male individuals autopsied at the National Institute of Legal Medicine - North Delegation (Porto, Portugal). Cadaver length was regressed on sternum length and a simple linear regression formula was obtained. The regression model provided a 95% confidence interval of 13.32 cm and a correlation coefficient of only 0.329. Compared to other studies, regression formulae based on the length of the sternum provided considerably larger standard errors than that based on long bone lengths. These results suggest that the length of the sternum has limited forensic value and relatively low reliability in estimating stature from mutilated human skeletal remains, either skeletonized or fresh. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved. Source

Svec M.,ASCR Institute of Physics Prague | Hapala P.,ASCR Institute of Physics Prague | OndraAek M.,ASCR Institute of Physics Prague | Merino P.,CSIC - National Institute of Aerospace Technology | And 9 more authors.
Physical Review B - Condensed Matter and Materials Physics

We discuss the possibility of a two-dimensional ordered structure formed upon deposition of Si on metal surfaces. We investigate the atomic and electronic structure of the Si-(19×19)R23.4°/Pt(111) surface reconstruction by means of a set of experimental surface-science techniques supported by theoretical calculations. The theory achieves very good agreement with the experimental results and is corroborating beyond any doubt that this phase is a surface alloy consisting of Si3Pt tetramers that resembles a twisted kagome lattice. These findings render unlikely any formation of silicene or germanene on Pt(111) and other transition-metal surfaces. © 2014 American Physical Society. Source

Smiley G.L.,University of Hohenheim | Kroschel J.,Apartado
Agroforestry Systems

In the Napu and Palolo Valleys of Central Sulawesi, Indonesia, a chronosequence sought to identify the relationship between tree age, nutrient dynamics and cocoa (Theobroma cacao L.) yield in association with gliricidia (Gliricidia sepium (Jacq.) Steud.). The chronosequence surveyed cocoa-gliricidia plantations with a maximum age of 8 and 15 years, respectively, in Napu and Palolo. The characteristics of the valleys were also quite different, with an altitude of 1,139-1,166 m a.s.l. in Napu and 592-651 m a.s.l. in Palolo. Annual rainfall was 1,543 mm in Napu and 1,811 mm in Palolo. The yield of cocoa increased fairly steadily, with growth rates higher in Palolo than in Napu. Whereas a higher level of bean P led to a higher single bean weight (g d.w.) in Napu, a higher level of bean K led to a lower single bean weight in Palolo. The relatively high level of K appeared to have coincided with immature growth stages of cocoa. As trees matured, their increased rate of C assimilation was seen in the form of higher single bean weight. We found no statistically significant change in the soil's carbon-nutrient levels when viewed over the entire timeframe of 8 and 15 years in the 2 valleys. In addition, there was no correlation between the soil's carbon-nutrient levels and the single bean weight. Nor did we find any correlation between the soil's carbon-nutrient levels impacting the bean's carbon-nutrient levels. Of regression lines, P had the steepest slope and was considered the most limited nutrient relative to the other nutrients although its correlation was insignificant. The farmers' estimation of cocoa yield was about 68% less than our measured bean weight per area per year (kg d. w. ha-1 year-1), implying a more refined definition of ripeness. In a cocoa agroforest, income could be supplemented by durable tree crops instead of growing gliricidia which is removed after several years of growth. This removal and the shallow rooting of cocoa indicate that the cocoa production would be sustainable only in the immediate future. © Springer Science+Business Media B.V. 2009. Source

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