H2_2 dissociation over Au-nanowires and the fractional conductance quantum

The dissociation of H$_2$ molecules on stretched Au nanowires and its effect on the nanowire conductance are analyzed using a combination of Density Functional (DFT) total energy calculations and non-equilibrium Keldish-Green function methods. Our DFT simulations reproduce the characteristic formation of Au monoatomic chains with a conductance close to % the conductance quantum $G_0 = 2e^2/h$. These stretched Au nanowires are shown to be better catalysts for H$_2$ dissociation than Au surfaces. This is confirmed by the nanowire conductance evidence: while not affected practically by molecular hydrogen, atomic hydrogen induces the appearance of fractional conductances ($G \sim 0.5 G_0$) as observed experimentally.Comment: 4 pages, 3 figure

Structural Path Analysis: Applications to Structural Changes in the Andalusian economy (1990-1999)

Social Accounting Matrices (SAM) are an useful tool that enables to get extenser information than Input-Output analysis as far as they work not only with an economy´s intersectorial relations, but also with consumers' behaviour, government or foreign sector; reflecting the income flow of rent. In this paper, we use Social Accounting Matrices for Andalusia for years 1990, 1995 y 1999, that we got from previous works. With this information we use "path analysis" technique to obtain the main changes in the productive structure and demand in Andalusia for the last ten years. Those changes will be represented in a three-dimensional picture. We also want to know which are the sectors that have strongly contributed to regional economic growth. Finally we measure the influence of sectorial shocks on themselves and also on the other sectors of this regional economy. Keywords: social accounting matrix, regional accounting, structural analysis. JEL: C67, D57, R15.

Lo que todos debemos saber sobre la nueva Ley de Amparo

Enrique Ochoa y Juan Manuel Arballo presentan, de una manera muy simple, lo que todos debemos saber sobre la Ley de Amparo. Afirman que se puso a la dignidad del ser humano como centro indiscutible del sistema político y jurídico mexicano. Hacen un recuento de los avances en materia de defensa, así como los espacios de protección que incorpora.ITESO, A.C

MULTIMODAL AND MULTIDIMENSIONAL GEODATA VISUALIZATION SYSTEM

It has been observed that Virtual Geographic Environments (VGEs) has been taking a lot of attention over the last decade, particularly within the domain of geographical information systems (GIS) and geographic analysis area. In this paper, we shed the light on the benefits of implementing archaeological visualization systems through the use of Google Earth application. Our application helps the end users and archaeologists working in data exploration and excavation analysis to deal with new web services that allows them to visualize huge amount of data in a new and usable way. For the purposed of our study, have tested our system with data from The Rocha Castle (an historic castle in the Galicia region (Spain) that was built in the 12th century). The system provides access to the excavation database and automatically updates the visualization, whenever the database is changed. The system can handle various types of Data, which could be, one, two or three-dimensional data. The paper aims to answer four fundamental questions regarding archaeological GIS systems: I. How to integrate a one and three dimensions representation into the same scenes? II. How to adapt data resolution to fit them into a particular Level of Visualization Detail (LOD) III. How to optimize data retrieval for efficient recovery data interpolation or continuous visualization? And finally IV. How to represent many objects in the same coordinates without overlapping

Enhancing the superconducting transition temperature of BaSi2 by structural tuning

We present a joint experimental and theoretical study of the superconducting phase of the layered binary silicide BaSi2. Compared with the layered AlB2 structure of graphite or diboride-like superconductors, in the hexagonal structure of binary silicides the sp3 arrangement of silicon atoms leads to corrugated sheets. Through a high-pressure synthesis procedure we are able to modify the buckling of these sheets, obtaining the enhancement of the superconducting transition temperature from 4 K to 8.7 K when the silicon planes flatten out. By performing ab-initio calculations based on density functional theory we explain how the electronic and phononic properties of the system are strongly affected by changes in the buckling. This mechanism is likely present in other intercalated layered superconductors, opening the way to the tuning of superconductivity through the control of internal structural parameters.Comment: Submitte

Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography

BACKGROUND: World-wide phylogeographic distribution of human complete mitochondrial DNA sequences suggested a West Asian origin for the autochthonous North African lineage U6. We report here a more detailed analysis of this lineage, unraveling successive expansions that affected not only Africa but neighboring regions such as the Near East, the Iberian Peninsula and the Canary Islands. RESULTS: Divergence times, geographic origin and expansions of the U6 mitochondrial DNA clade, have been deduced from the analysis of 14 complete U6 sequences, and 56 different haplotypes, characterized by hypervariable segment sequences and RFLPs. CONCLUSIONS: The most probable origin of the proto-U6 lineage was the Near East. Around 30,000 years ago it spread to North Africa where it represents a signature of regional continuity. Subgroup U6a reflects the first African expansion from the Maghrib returning to the east in Paleolithic times. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent

Improving the Working Memory During Early Childhood Education Through the Use of an Interactive Gesture Game-Based Learning Approach

One of the most socially and culturally advantageous uses of human–computer interaction is enhancing playing and learning for children. In this paper, gesture interactive game-based learning (GIGL) is tested to see if these kinds of applications are suitable to stimulate working memory (WM) and basic mathematical skills (BMS) in early childhood (5–6 years old) using a hand gesture recognition system. Hand gesture is being performed by the user and to control a computer system by that incoming information. The research was developed using a quasi-experimental design with a pre-test and post-test, using both an experimental and control group through three phases: the first one was the prior evaluation of the learner’s skills; a second phase in which the use of the technology was developed; and a final phase of evaluation. In the evaluation phases, working memory was measured using the Corsi task, and the basic mathematical skills using the test for the diagnosis of basic mathematical competencies (TEDI-MATH). The results provide clear evidence that the use of these technologies improved both working memory and basic mathematical skills. We can conclude that the children who used GIGL technology showed a significant increase in their learning performance in WM and BMS, surpassing those who did normal school activitiesS

Effect of biochar amendment on morphology, productivity and water relations of sunflower plants under non-irrigation conditions

páginas.-- 6 figuras.-- 2 tablas.-- 56 referencias.-- Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.catena.2016.07.037.Three biochars (B1: pine wood, B2: paper-sludge, B3: sewage-sludge) produced under controlled pyrolysis conditions and one produced in kilns (B4: grapevine wood) were used as organic ameliorants in a Calcic Cambisol, which represents a typical agricultural soil of the Mediterranean region. This field study was performed with plants of sunflower (Helianthus annuus L.) at the experimental station “La Hampa”, located in the Guadalquivir river valley (SW Spain). The soil was amended with doses equivalent to 1.5 and 15 t ha− 1 of the four biochars in two independent plantations. In addition, un-amended plots were prepared in both experiments for comparison purposes. The major goal of this study was the assessment of the effect of biochar amendment on the physiology and development of sunflower plants at field conditions. During most of the growing period plants of un-amended and amended plots showed no stress symptoms either by their appearance or by stress-sensitive biochemical parameters such as the stability of the photosystem II (QY). Biochar addition had no effect on seed germination. Addition of 1.5 t ha− 1 biochar did not significantly change the pH of the soil, its electrical conductivity (EC) or its water holding capacity (WHC). Concomitantly the plant development and plant biomass production remained unaltered. Amendments with 15 t ha− 1 slightly increased the WHC of the soil but showed no lasting impact on the soil pH. It stimulated plant growth and led to a greater leaf area, larger plant stems and wider inflorescences of the sunflower plants than those cultivated on the un-amended soil. At the end of the experiment, biochar amendment of soil caused no significant increase of the total biomass production excepting B4, the biochar with the lowest capacity of water retention, which exhibited the highest vegetative growth and seed production. The lack of rain during the last weeks caused a water shortage in the culture that produced greater QY loss in non-amended plants. Interestingly, better growth of amended plants during the drought period correlated with higher reduction of stomatal conductance, indicating that the greater water use efficiency is at the origin of the better crop performance of biochar-amended plants. This finding points to the agronomic relevance of biochar amendment of Mediterranean rain fed crops.The Marie Skłodowska-Curie actions of the European Union's FP7 People Programme (REA grant agreement no PCIG12-GA-2012-333784-Biocharisma project) and the Spanish Ministry of Economy and Competitiveness (MINECO) (project PCGL2012-37041) are thanked for the financial support of the present study. The Spanish Ministry of Education, Culture and Sport is acknowledged for funding the FPU fellowship (FPU 13/05831) of Marina Paneque, and the contract of Juan De Dios Franco-Navarro (AGL2009-08339/AGR). The European Biochar Network (Biochar as option for sustainable resource management-COST action TD1107) and Bodegas Torres (Spain) are acknowledged for providing the biochar samples. M. Velasco is gratefully acknowledged for her technical assistance at field.Peer reviewe

Confinement-induced vitrification in polyethylene terephthalate

9 págs.; 5 figs.; 1 app; PACS number s : 61.82.Pv, 61.82.Rx, 64.70.Pf, 05.20. y; Erratum Phys. Rev. B 79, 019903 (2009)Dynamic mechanical thermal analysis performed on cold-drawn polyethylene terephthalate (PET), cold crystallized (annealed) in the temperature interval 100-140°C, reveals the presence of marginally glassy domains above the annealing temperature Ta. This suggests that the thermodynamic force driving crystallization causes the structural arrest of some noncrystalline domains. The latter thus need a temperature higher than Ta to completely defreeze. Differential scanning calorimetry supports this point of view. Analogous investigations on unoriented PET, cold crystallized in the same conditions, do not show the same peculiarities; thus, chain orientation is relevant to vitrification. This phenomenology is first cast in the language of thermodynamics by introducing an excess chemical potential δμ describing the presence of structural constraints in the amorphous domains and the effect of chain orientation. For a first test of this picture, the orientation contribution to δμ is calculated by means of the Gaussian chain model (this implicitly assumes that δμ is related to the density fluctuations). The resulting expression is then used to discuss the structural differences between cold-drawn and unoriented PET samples reported in the literature. © 2007 The American Physical Society.Peer Reviewe

Revisión crítica de los estudios sobre biogeografía de macroalgas marinas del Mediterráneo.

Revisión crítica de los estudios sobre biogeografía de macroalgas marinas del Mediterráneo. Teniendo en cuenta los procedimientos metodológicos que se siguen en los estudios biogeográficos, se reconocen tres tipos básicos de aproximaciones: biogeografía descriptiva, biogeografía narrativa y biogeografía analítica. En este trabajo se analizan las aportaciones realizadas a la ficogeografía de las macroalgas marinas del mar Mediterráneo, atendiendo a cada una de las tres aproximaciones posibles. Existen escasas floras del Mediterráneo oriental y la costa africana, además de un estancamiento metodológico en los estudios narrativos y analíticos, impidiendo el avance de la ficogeografía. Se discuten las posibles líneas futuras de investigación con el objeto de incentivar un avance significativo en los conocimientos ficogeográficos del Mediterráneo