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  • 2010-2014  (19)
  • 2000-2004
  • 2013  (19)
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  • 2010-2014  (19)
  • 2000-2004
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  • 1
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    Three-dimensional flow in centered pool-riffle sequences (2013)
    Wiley
    Details
    Publication Date: 2013-01-17
    Description: Pool-riffle sequences are geomorphological features of many streams, thought to contribute to the hydrodynamic variability necessary to support healthy habitat conditions. Due to this fact, the addition of artificial pools and riffles is a common alternative for restoration projects on channelized streams. In this paper, detailed three-dimensional (3-D) flow measurements conducted on a scale model of an existing pool-riffle design implemented as part of a restoration project is presented. The design incorporated the basic features of natural pool-riffle sequences but maintained the deepest part of the pool in the center of the cross section and away from the banks. Results showed that the 3-D flow patterns were qualitatively different for two discharge conditions tested. The lower discharge case was strongly affected by the topography, displaying a pattern consistent with a secondary flow generated by the curvature of the streamlines. The higher discharge case was less affected by the topography, presenting a secondary flow pattern similar to that observed over a flat bed and typically associated with turbulence anisotropy. Self-maintenance and flow variability were also investigated. Even though convergence of the values of bed shear stresses at pool and riffle sections with increasing discharge did take place, reversal conditions did not occur. The difference in flow structure with flow stage was also reflected in the spatial flow variability, the lower discharge displaying larger variability than the higher discharge. The higher discharge generated a level of variability comparable with the values obtained over a flat bed.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    The effects of floodplain soil heterogeneity on meander planform shape (2013)
    Wiley
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    Publication Date: 2013-01-03
    Description: [1]  Past analytical studies of meander planform development have mostly focused on the complexity of the governing equations, i.e., hydrodynamics, and less so on the stream bank resistance to erosion, whose spatial heterogeneity is difficult to describe deterministically. This motivated the use of a Monte Carlo approach to examine the effects of floodplain soils and their distribution on planform development, with the goal of including bank erosion properties in the analysis. Simulated bank erosion rates are controlled by the resistance to hydraulic erosion of the bank soils using an excess shear stress approach. The spatial distribution of critical shear stress across the floodplain is delineated on a rectangular, equidistant grid with varying degrees of variability. The corresponding erodibility coefficient is computed using a field-derived empirical relation. For a randomly disturbed distribution, in which the mean resistance to erosion exponentially increases away from the valley centerline, two relevant parameters are identified: the standard deviation of the critical shear stress distribution, which controls skewness and variability of the channel centerline, and the cross-valley increase in soil resistance, which constrains lateral migration and also affects bend skewness. For a purely random distribution, migrated centerlines exhibit larger variability for increasing spatial scales of floodplain soil heterogeneity. For equal stochastic variability of the corresponding governing parameters, relating meander migration to hydraulic erosion of the bank soils produces more variability and shape complexity than the “classic” bank migration approach of Ikeda et al. (1981), which relates migration rate to excess velocity at the outer bank. Finally, the proposed stochastic approach provides a foundation for estimating a suitable spatial density of measurements to characterize the physical properties of floodplain soils and vegetation.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Genome-wide copy number variation study in anorectal malformations (2013)
    Oxford University Press
    Details
    Publication Date: 2013-01-12
    Description: Anorectal malformations (ARMs, congenital obstruction of the anal opening) are among the most common birth defects requiring surgical treatment (2–5/10 000 live-births) and carry significant chronic morbidity. ARMs present either as isolated or as part of the phenotypic spectrum of some chromosomal abnormalities or monogenic syndromes. The etiology is unknown. To assess the genetic contribution to ARMs, we investigated single-nucleotide polymorphisms and copy number variations (CNVs) at genome-wide scale. A total of 363 Han Chinese sporadic ARM patients and 4006 Han Chinese controls were included. Overall, we detected a 1.3-fold significant excess of rare CNVs in patients. Stratification of patients by presence/absence of other congenital anomalies showed that while syndromic ARM patients carried significantly longer rare duplications than controls ( P = 0.049), non-syndromic patients were enriched with both rare deletions and duplications when compared with controls ( P = 0.00031). Twelve chromosomal aberrations and 114 rare CNVs were observed in patients but not in 868 controls nor 11 943 healthy individuals from the Database of Genomic Variants. Importantly, these aberrations were observed in isolated ARM patients. Gene-based analysis revealed 79 genes interfered by CNVs in patients only. In particular, we identified a de novo DKK4 duplication . DKK4 is a member of the WNT signaling pathway which is involved in the development of the anorectal region. In mice, Wnt disruption results in ARMs. Our data suggest a role for rare CNVs not only in syndromic but also in isolated ARM patients and provide a list of plausible candidate genes for the disorder.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 4
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    Modulation of the flow structure by progressive bedforms in the Kinoshita meandering channel (2013)
    Wiley
    Details
    Publication Date: 2013-06-27
    Description: ABSTRACT An in-house fully three-dimensional general-purpose finite element model is applied to solve the hydrodynamic structure in a periodic Kinoshita-generated meandering channel. The numerical model solves the incompressible Reynolds-Averaged Navier-Stokes (RANS) equations for mass and momentum, while solving the k-ε equations for turbulence. The free surface is described by the rigid-lid approximation (using measured water surface data) for flat (smooth-bed) and self-formed (rough-bed) conditions. The model results are compared against experimental measurements in the “Kinoshita channel” where three-dimensional (3D) flow velocities and turbulence parameters were measured. This validation was carried out for the upstream-valley meander bend orientation under smooth (flat bed) condition. After validation, several simulations were carried out to predict the hydrodynamics in conditions where either it was not possible to perform measurements (e.g. applicability of the laboratory acoustic instruments) and to extrapolate the model to other planform configurations. For the flat smooth-bed case, asymmetric (no skewness) planform configuration was modeled and compared to the upstream-skewed case. For the self-formed rough-bed case, prediction of the hydrodynamics during the progression of bedforms was performed. It appears that the presence of bedforms on a bend induces: [1] the natural secondary flow of the bend is disrupted by the presence of the bedforms, thus depending on the location of the dune, secondary flows might differ completely from the traditional orientation, [2] an increment on both the bed and bank shear stresses, having as much as 50 % more fluvial erosion, and thus, a potential increment on the migration rate of the bend. Implications on sediment transport and bend morphodynamics are also discussed along the paper. This article is protected by copyright. All rights reserved.
    Print ISSN: 0197-9337
    Electronic ISSN: 1096-9837
    Topics: Geography , Geosciences
    Published by Wiley
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  • 5
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    The relative importance of solar radiation and soil origin in cactus seedling survivorship at two spatial scales: plant association and microhabitat (2013)
    Wiley
    Details
    Publication Date: 2013-12-17
    Description: Question What is the relative importance of solar radiation intensity and soil origin for cactus establishment at the spatial scales of microhabitat and plant association? Location Tehuacán-Cuicatlán region, central Mexico. Methods The seedling survivorship of Myrtillocactus geometrizans , Neobuxbaumia tetetzo and Opuntia pilifera was assessed. A garden experiment was conducted involving two light treatments (direct solar radiation and artificial shade) for seedlings growing in soil from different microhabitats (under the canopy of a Parkinsonia praecox nurse plant and in an open area) from three plant associations ( tetechera , sotolinera and mezquitera ) in a semi-arid inter-tropical ecosystem. It was predicted that seedling survival would be higher: (1) under the artificial shade treatment; (2) in soil from the microhabitat under the canopy of the nurse tree; (3) in soil from the plant association with the highest concentrations of carbon (C), nitrogen (N) and phosphorus (P); and (iv) in the species with the largest seed mass. Results Seedlings of the three species survived better in the shade. Despite the fact that soil taken under nurse plants has a higher concentration of nutrients than that from open areas, seedling survivorship did not differ between these microhabitats. Opuntia pilifera , the species with higher seed mass, survived better than M. geometrizans and N. tetetzo , whose seedling survival did not differ. Seedling survivorship differed between soils taken from the different plant associations. Higher survival rates were observed in soil from plant associations with the lowest concentration of total and available P (i.e. sotolinera and tetechera ) but with a high concentration of C, total N, nitrate and ammonium. Conclusions The relative importance of shade and soil origin on seedling survivorship depends on the spatial scale. At the microhabitat level, shade is crucial for seedling establishment, whereas soil type is not. However, soil seems important at the plant association scale. An adaptation to the most common habitat of the Zapotitlán Valley, where soil has high quantities of Ca (as carbonate), little available P but relatively high available N, could explain the better early cactus seedling survivorship in the tetechera and sotolinera . Factors that influence cactus seedling differ at the spatial scales of microhabitat and plant association. At the microhabitat scale, seedling survivorship depends more on the intensity of solar radiation than on soil fertility. At the plant-association scale, soil seems to play a more important role for the survivorship of the studied cactus species.
    Print ISSN: 1100-9233
    Electronic ISSN: 1654-1103
    Topics: Biology
    Published by Wiley on behalf of The International Association for Vegetation Science (IAVS).
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  • 6
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    Combinaciones de preservantes para un producto untable natural (2013)
    Details
    Publication Date: 2021-05-19
    Description: Se valoró el uso de diferentes combinaciones de preservantes químicos en la elaboración de un producto untable no fermentado, con vistas a incrementar el tiempo de vida útil del mismo. Los preservantes utilizados fueron sorbato de potasio, ácido benzoico y ácido sórbico, estableciéndose las combinaciones posibles de dos conservantes, que no superara 0,1 % por combinación en el producto final. Se determinó el tiempo de vida útil del untable elaborado con cada combinación, mantenidos a 6 ± 2 ºC. El estudio se realizó siguiendo un diseño de muestreo parcialmente escalonado y tomando como rechazo la modificación de los atributos de calidades físico-químicas, microbiológicas y sensoriales. Se precisó que con las 3 combinaciones estudiadas se incrementó la durabilidad del untable no fermentado elaborado en el país (28 días) en más de un mes y la mejor combinación fue: sorbato de potasio: ácido benzoico (0,05 %: 0,05 %) con la que se alcanzó una durabilidad de 10 semanas, considerando 20 % de muestras rechazadas y tomando el valor medio del percentil. Durante el tiempo de conservación no se detectaron cambios físico- químicos ni sensoriales; el rechazo de las muestras se debió al deterioro de su calidad microbiológica.
    Description: The use of different combinations of chemical preservers was valued in the elaboration of a not fermented spreadable product, with the objective to increasing the time of useful life of the same one. The utilized preservers were potassium sorbate, benzoic acid and the sorbic acid settling down the combinations possible of two preservers that didn’t overcome 0.1% for combination in the end product. The time of useful life of each spreadable product elaborated was determined at the temperature of 6 ± 2 ºC. The study was carried out following a design of partially stepped sampling and taking like rejection the modification of the physical-chemical, microbiologic and sensorial attributes of quality. It was established that with the 3 studied combinations, the durability of the not fermented spreadable, elaborated in the country (28 days), was increased in more than one month and the best combination was: potassium sorbate: benzoic acid (0.05%: 0.05%) with a durability of 10 weeks, considering 20% of rejected samples and taking the mean value of the percentile. During the time of conservation neither physical-chemical nor sensorial changes were detected; the rejection of the samples was due to the deterioration of its microbiologic quality.
    Description: Published
    Description: spreads
    Description: potassium sorbate
    Keywords: Benzoic acid ; Sorbic acid ; Sorbates ; Shelf life ; Preservatives
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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  • 7
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    Models for electrostatic drift waves with density variations along magnetic field lines (2013)
    Wiley
    Details
    Publication Date: 2013-10-18
    Description: [1]  Drift waves with vertical magnetic fields in gravitational ionospheres are considered where the unperturbed plasma density is enhanced in a magnetic flux-tube. The gravitational field gives rise to an overall decrease of plasma density for increasing altitude. Simple models predict that drift waves with finite vertical wave-vector components can increase in amplitude merely due to a conservation of energy density flux of the waves. Field aligned currents are some of the mechanisms that can give rise to fluctuations that are truly unstable. We suggest a self-consistent generator or “battery” mechanism that in the polar ionospheres can give rise to magnetic field aligned currents even in the absence of electron precipitation. The free energy is here supplied by steady state electric fields imposed in the direction perpendicular to the magnetic field in the collisional lower parts of the ionosphere or by neutral winds that have similar effects.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
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    All-optical control and visualization of ultrafast two-dimensional atomic motions in a single crystal of bismuth (2013)
    Springer Nature
    Details
    Publication Date: 2013-11-20
    Description: Article Controlling the motion of atoms in solids with light allows for a deeper understanding of their fundamental properties, yet most studies only deal with one spatial dimension. Katsuki et al. extend this approach to two-dimensional control and use it to visualize atomic motion in bismuth. Nature Communications doi: 10.1038/ncomms3801 Authors: H. Katsuki, J.C. Delagnes, K. Hosaka, K. Ishioka, H. Chiba, E.S. Zijlstra, M.E. Garcia, H. Takahashi, K. Watanabe, M. Kitajima, Y. Matsumoto, K.G. Nakamura, K. Ohmori
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 9
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    Electron capture on ^{116}In and implications for nuclear structure related to double-β decay (2013)
    American Physical Society (APS)
    Details
    Publication Date: 2013-03-08
    Description: Author(s): C. Wrede, S. K. L. Sjue, A. García, H. E. Swanson, I. Ahmad, A. Algora, V.-V. Elomaa, T. Eronen, J. Hakala, A. Jokinen, V. S. Kolhinen, I. D. Moore, H. Penttilä, M. Reponen, J. Rissanen, A. Saastamoinen, and J. Äystö The electron capture decay branch of 116 In has been measured to be [2.46±0.44(stat.)±0.39(syst.)]×10 −4 using Penning trap-assisted decay spectroscopy. The corresponding Gamow-Teller transition strength is shown to be compatible with the most recent value extracted from the ( p , n ) charge-exchange reac... [Phys. Rev. C 87, 031303] Published Thu Mar 07, 2013
    Keywords: Nuclear Structure
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
    Published by American Physical Society (APS)
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  • 10
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    2MeV electron irradiation effects on bulk and interface of atomic layer deposited high-k gate dielectrics on silicon (2013)
    Elsevier
    Details
    Publication Date: 2013-05-01
    Print ISSN: 0040-6090
    Electronic ISSN: 1879-2731
    Topics: Physics
    Published by Elsevier
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