3,908 research outputs found

    Deformation Monitoring of the Submillimetric UPV Calibration Baseline

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    [EN] A 330 m calibration baseline was established at the Universitat Politecnica de Valencia (UPV) in 2007. Absolute scale was subsequently transferred in 2012 from the Nummela Standard Baseline in Finland and distances between pillars were determined with uncertainties ranging from 0.1 mm to 0.3 mm. In order to assess the longterm stability of the baseline three field campaigns were carried out from 2013 to 2015 in a co-operative effort with the Universidad Complutense de Madrid (UCM), which-provided the only Mekometer ME5000 distance meter available in Spain. Since the application of the ISO17123-4 full procedure did not suffice to come to a definite conclusion about possible displacements of the pillars, we opted for the traditional geodetic network approach. This approach had to be adapted to the case at hand in order to deal with problems such as the geometric weakness inherent to calibration baselines and scale uncertainty derived from both the use of different instruments and the high correlation between the meteorological correction and scale determination. Additionally, the so- called the maximum number of stable points method was also tested. In this contribution it is described the process followed to assess the stability of the UPV submillimetric calibration baseline during the period of time from 2012 to 2015.Spanish Ministry of Science and Innovation, (Grant/Award Number: 'AYA2011-23232').García-Asenjo Villamayor, L.; Baselga Moreno, S.; Garrigues Talens, P. (2017). Deformation Monitoring of the Submillimetric UPV Calibration Baseline. Journal of Applied Geodesy. 11(2):107-114. https://doi.org/10.1515/jag-2016-0018S10711411

    Reversible quantum teleportation in an optical lattice

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    We propose a protocol, based on entanglement procedures recently suggested by [D. Jaksch et al., Phys. Rev. Lett. 82, 1975 (1999)], which allows the teleportation of an unknown state of a neutral atom in an optical lattice to another atom in another site of the lattice, without any irreversible detection.Comment: 8 pages, 3 figure

    Assessing the Influence of Living and Working Conditions on Alcohol Consumption in Migrant Farmworkers in Mexico

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    Background and Purpose: Inadequate working and living conditions are associated with alcohol consumption in farmworkers in the U.S. However, the influence of these factors on alcohol consumption patterns in migrant farmworkers in Mexico remains unclear. The purpose of this analysis was to assess the influence of housing and working conditions on alcohol use in migrant farmworkers in Mexico. Methods: We used logistic and ordinal logistic regression to examine the association of living and working conditions on alcohol consumption and frequency in 3,132 farmworkers in Mexico with data from a Mexican national farmworker’s survey. Results: Living in inadequately built homes (OR=0.84; 95% CI=0.72, 0.98; p<0.05) and limited access to luxury items (OR=0.69; 95% CI=0.52, 0.94; p<0.01), were associated with a decreased likelihood to consume alcohol compared to living in better conditions. In contrast, living in employer provided housing (OR=1.79; 95% CI=1.40, 2.31; p<0.0001) and experiencing hazards related to safety (OR= 1.69; 95% CI= 1.35, 2.12; p<0.0001), work organization (OR= 1.29; CI= 1.03, 1.63; p<0.05), and ergonomics (OR= 2.04; CI= 1.18, 3.52; p<0.05) increased the likelihood of consuming alcohol. Conclusion: Living and working conditions of farmworkers may affect alcohol consumption. However, these findings require replication and specific mechanisms, which may influence these results warrants investigation

    Agriculture and Food Security in Mozambique

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    The objective of this short review is to contribute to the debate on the role of agriculture transformation in the development process and as an engine to reduce poverty and improve general wellbeing through better access to nutrients in Mozambique. Agricultural services are organized by Provinces but still there is no accurate data on food production, consumption and trade trends in a large sample. It is recognized the complexity of the food security concept and the need of a multidimensional definition and approach. The increase in agricultural productivity can probably be seen as a necessary but not a sufficient condition to achieve long term food security in Mozambique or Sub-Saharan Africa.  Competing views about the relevance of agriculture for growth and development imply different policy priorities in Africa

    Aplicaciones de la tecnología geofísica de georradar junto con la termografía infrarroja, el perfilómetro y otras tecnologías complementarias, en la construcción. Limitaciones y posibilidades

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    Georadar technology has proven to be highly effective in the diagnosis and analysis of soils and the most diverse applications thanks to its effectiveness and non-destructive characteristics. This article describes and analyzes the use of georadar technology supported by other complementary ones, such as the ground electromagnetic survey, infrared thermography, infrared photography and multispectral photography, all of them used together for a common objective in concrete examples related to the field of the construction. Subsequently, the characteristics of the construction systems and the environment that can condition the effectiveness of the results and reduce the advantages of the joint use of the different systems are analyzed, which will allow future actions to adjust the scope of the objectives, optimize the advantages the complementarity of the different systems and, therefore, will open a range of possibilities for future use.La tecnología del georradar se ha probado de gran eficacia en la diagnosis y análisis de suelos y las más diversas aplicaciones gracias a su efectividad y sus características no destructivas. El presente artículo describe y analiza la utilización de la tecnología del georradar apoyada en otras complementarias, como son el perfilómetro, la termografía infrarroja, la fotografía infrarroja y la fotografía multiespectral, empleadas conjuntamente en ejemplos concretos de análisis de construcciones con objetivos relacionados con la detección y diagnóstico de deficiencias en los proyectos. Posteriormente, se analizan las características de los sistemas constructivos y del entorno que pueden condicionar la efectividad de los resultados y merma las ventajas de la utilización conjunta de los distintos sistemas, lo que permitirá en futuras actuaciones ajustar el alcance de los objetivos, optimizar las ventajas de la complementariedad de los distintos sistemas y, por tanto, permitirá abrir un abanico de posibilidades de utilización futura

    Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid–graphene electrode interfaces

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    In this work we study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion–electrode interactions in ionic liquids. We compare the interfacial behaviour of Li+ and K+ at a charged graphene sheet in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, and its mixtures with lithium and potassium tetrafluoroborate salts. Our results show that there are dense interfacial solvation structures in these electrolytes that lead to the formation of high free energy barriers for these alkali metal cations between the bulk and direct contact with the negatively charged surface. We show that the stronger solvation of Li+ in the ionic liquid leads to the formation of significantly higher interfacial free energy barriers for Li+ than for K+. The high free energy barriers observed in our simulations can explain the generally high interfacial resistance in electrochemical storage devices that use ionic liquid-based electrolytes. Overcoming these barriers is the rate-limiting step in the interfacial transport of alkali metal ions and, hence, appears to be a major drawback for a generalised application of ionic liquids in electrochemistry. Some plausible strategies for future theoretical and experimental work for tuning them are suggested

    A Mutation in F-actin Polymerization Factor Suppresses the Distal Arthrogryposis Type 5 Piezo2 Pathogenic Variant in Caenorhabditis Elegans

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    The mechanosensitive PIEZO channel family has been linked to over 26 disorders and diseases. Although progress has been made in understanding these channels at the structural and functional levels, the underlying mechanisms of PIEZO-associated diseases remain elusive. In this study, we engineered four PIEZO-based disease models using CRISPR/Cas9 gene editing. We performed an unbiased chemical mutagen-based genetic suppressor screen to identify putative suppressors of a conserved gain-of-function variant pezo-1[R2405P] that in human PIEZO2 causes distal arthrogryposis type 5 (DA5; p. R2718P). Electrophysiological analyses indicate that pezo-1(R2405P) is a gain-of-function allele. Using genomic mapping and whole-genome sequencing approaches, we identified a candidate suppressor allele in the C. elegans gene gex-3. This gene is an ortholog of human NCKAP1 (NCK-associated protein 1), a subunit of the Wiskott-Aldrich syndrome protein (WASP)-verprolin homologous protein (WAVE/SCAR) complex, which regulates F-actin polymerization. Depletion of gex-3 by RNAi, or with the suppressor allele gex-3(av259[L353F]), significantly increased brood size and ovulation rate, as well as alleviating the crushed oocyte phenotype of the pezo-1(R2405P) mutant. Expression of GEX-3 in the soma is required to rescue the brood size defects in pezo-1(R2405P) animals. Actin organization and orientation were disrupted and distorted in the pezo-1 mutants. Mutation of gex-3(L353F) partially alleviated these defects. The identification of gex-3 as a suppressor of the pathogenic variant pezo-1(R2405P) suggests that the PIEZO coordinates with the cytoskeleton regulator to maintain the F-actin network and provides insight into the molecular mechanisms of DA5 and other PIEZO-associated diseases

    A measurable entanglement criterion for two qubits

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    We propose a directly measurable criterion for the entanglement of two qubits. We compare the criterion with other criteria, and we find that for pure states, and some mixed states, it coincides with the state's concurrency. The measure can be obtained with a Bell state analyser and the ability to make general local unitary transformations. However, the procedure fails to measure the entanglement of a general mixed two-qubit state.Comment: 5 page

    Seeking the Local Convergence Depth. V. Tully-Fisher Peculiar Velocities for 52 Abell Clusters

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    We have obtained I band Tully-Fisher (TF) measurements for 522 late-type galaxies in the fields of 52 rich Abell clusters distributed throughout the sky between 50 and 200\h Mpc. Here we estimate corrections to the data for various forms of observational bias, most notably Malmquist and cluster population incompleteness bias. The bias-corrected data are applied to the construction of an I band TF template, resulting in a relation with a dispersion of 0.38 magnitudes and a kinematical zero-point accurate to 0.02 magnitudes. This represents the most accurate TF template relation currently available. Individual cluster TF relations are referred to the average template relation to compute cluster peculiar motions. The line-of-sight dispersion in the peculiar motions is 341+/-93 km/s, in general agreement with that found for the cluster sample of Giovanelli and coworkers.Comment: 31 pages, 14 figures, uses AAS LaTeX; to appear in the Astronomical Journa
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