590 research outputs found
Ensayo metodológico de planificación física de una autovía en el Estado Miranda (Venezuela)
La planificación física con base ecológica es fundamental para desarrollar el potencial ambiental y humano de un territorio. Sin embargo, en numerosas áreas de Latinoamérica
hay carencias de información territorial que dificultan estos procedimientos. En esta línea, se ha realizado un ensayo metodológico de una planificación física de una autovía hipotética. Para ello se han realizado modelos en SIG (Sistemas de Información Geográfica) de capacidad territorial, riesgos, calidad, fragilidad e impacto ambiental, que se han integrado en una síntesis de planificación territorial. El objetivo final ha sido modelizar un mapa de impedancia o fricción frente a la autovía, para aplicar un algoritmo cost distance / cost
path y obtener un trazado de autovía que optimizase la capacidad del territorio y minimizase el impacto ambiental. Se ha consolidado un aprendizaje y una primera transferencia
I + D dirigida a la gestión territorial y a la toma de decisiones para diversos países de Latinoamérica
Laser-Induced Crystallization of Sputtered Unhydrogenated Silicon at Low Temperatures
10-um-thick non-hydrogenated amorphous-silicon (a-Si) films were deposited at relatively high rates (_>10 Å/s) by radio-frequency magnetron sputtering (RFMS) on different large-area buffer-layer-coated glass substrates at deposition temperatures ranging from room temperature (RT) to 300oC. These amorphous samples were subsequently crystallized by means of a continuous-wave diode laser, looking for conditions to reach liquid-phase crystallization. The influence of deposition conditions on the quality of the final micro-crystalline silicon films has been studied
Water seepage beneath dams on soluble evaporite deposits: a laboratory and field study (Caspe Dam, Spain)
The paper presents analytical methods and results for assessing the variation in the concentration of sulphate (and other ions) over space and time in groundwater flowing through a soluble evaporite terrain beneath a dam. The influence of effective porosity, groundwater flow velocity and the specific rate of dissolution (K′) are considered. The theoretical analysis was tested in a scale model simulating a dam constructed on heavily karstified bedrock. A simple and useful method for assessing how much material is lost through dissolution and how the rate of dissolution changes over time is considered in the context of the Caspe Dam, Spain
Instability of the steady states of some Ginzburg–Landau-like equations with real coefficients
The instability of the steady states with nonconstant amplitude is analysed for a nonlocal Ginzburg–Landau equation with real coefficients and quasiperiodic boundary conditions. The results are obtained in terms of easily recognized, qualitative properties of the steady states. Some of the results are new, even for the standard (local) Ginzburg–Landau equation with real coefficients. A related Ginzburg–Landau equation coupled to a mean field is also considered that appears in the analyses of counter-propagating waves in extended systems, nonoscillatory instabilities with a conservation law, and viscous Faraday waves in large aspect ratio containers
Post-Retained Single Crowns versus Fixed Dental Prostheses: A 7-Year Prospective Clinical Study
Biomechanical integrity of endodontically treated teeth (ETT) is often compromised. Degree of hard tissue loss and type of final prosthetic restoration should be carefully considered when making a treatment plan. The objective of this prospective clinical trial was to assess the influence of the type of prosthetic restoration as well as the degree of hard tissue loss on 7-y clinical performance of ETT restored with fiber posts. Two groups (n = 60) were defined depending on the type of prosthetic restoration needed: 1) single unit porcelain-fused-to-metal (PFM) crowns (SCs) and 2) 3- to 4-unit PFM fixed dental prostheses (FDPs), with 1 healthy and 1 endodontically treated and fiber post-restored abutment. Within each group, samples were divided into 2 subgroups (n = 30) according to the amount of residual coronal tissues after abutment buildup and final preparation: A) >50% of coronal residual structure or B) equal to or <50% of coronal residual structure. The clinical outcome was assessed based on clinical and intraoral radiographic examinations at the recalls after 6, 12, 24, 36, 48, and 84 mo. Data were analyzed by Kaplan-Meier log-rank test and Cox regression analysis (P < 0.05). The overall 7-y survival rate of ETT restored with fiber post and either SCs or FDPs was 69.2%. The highest 84-mo survival rate was recorded in group 1A (90%), whereas teeth in group 2B exhibited the lowest performance (56.7% survival rate). The log-rank test detected statistically significant differences in survival rates among the groups (P = 0.048). Cox regression analysis revealed that the amount of residual coronal structure (P = 0.041; hazard ratio [HR], 2.026; 95% confidence interval [CI] for HR, 1.031–3.982) and the interaction between the type of prosthetic restoration and the amount of residual coronal structure (P = 0.024; HR, 1.372; 95% CI for HR, 1.042–1.806) were statistically significant factors for survival (ClinicalTrials.gov NCT01532947)
Control of Rayleigh-Taylor instability by vertical vibration in large aspect ratio containers
We consider a horizontal heavy fluid layer supported by a light, immiscible one in a wide (as compared to depth) container, which is vertically vibrated intending to counterbalance the Rayleigh-Taylor instability of the flat, rigid-body vibrating state. In the simplest case when the density and viscosity of the lighter fluid are small compared to their counterparts in the heavier fluid, we apply a long wave, weakly nonlinear analysis that yields a generalized Cahn-Hilliard equation for the evolution of the fluid interface. This equation shows that the stabilizing effect of vibration is like that of surface tension, and is used to analyze the linear stability of the flat state, the local bifurcation at the instability threshold and some global existence and stability properties concerning the steady states without dry spots. The analysis is extended to two cases of practical interest. Namely, (a) the viscosity of one of the fluids is much smaller than that of the other one, and (b) the densities and viscosities of both fluids are quite close to each other
Adaptive plasticity of killifish (Fundulus heteroclitus) embryos: dehydration-stimulated development and differential aquaporin-3 expression
13 pages, 7 figures, 3 tablesEmbryos of the marine killifish Fundulus heteroclitus are adapted to survive aerially. However, it is unknown if they are able to control development under dehydration conditions. Here, we show that air-exposed blastula embryos under saturated relative humidity were able to stimulate development, and hence the time of hatching was advanced with respect to embryos continuously immersed in seawater. Embryos exposed to air at later developmental stages did not hatch until water was added, while development was not arrested. Air-exposed embryos avoided dehydration probably because of their thickened egg envelope, although it suffered significant evaporative water loss. The potential role of aquaporins as part of the embryo response to dehydration was investigated by cloning the aquaporin-0 (FhAqp0), -1a (FhAqp1a), and -3 (FhAqp3) cDNAs. Functional expression in Xenopus laevis oocytes showed that FhaAqp1a was a water-selective channel, whereas FhAqp3 was permeable to water, glycerol, and urea. Expression of fhaqp0 and fhaqp1a was prominent during organogenesis, and their mRNA levels were similar between water- and air-incubated embryos. However, fhaqp3 transcripts were highly and transiently accumulated during gastrulation, and the protein product was localized in the basolateral membrane of the enveloping epithelial cell layer and in the membrane of ingressing and migrating blastomers. Interestingly, both fhaqp3 transcripts and FhAqp3 polypeptides were downregulated in air-exposed embryos. These data demonstrate that killifish embryos respond adaptively to environmental desiccation by accelerating development and that embryos are able to transduce dehydration conditions into molecular responses. The reduced synthesis of FhAqp3 may be one of these mechanisms to regulate water and/or solute transport in the embryo.This study was supported by the European Commission New and Emerging
Science and Technologies (NEST) program (contract no. 012674-2 Sleeping
Beauty) and by a grant from the Spanish Ministry of Education and Science
(MEC; AGL2004-00316/ACU) to J. Cerda`. Participation of C. Zapater and F.
Chauvigne´ was financed by a predoctoral fellowship from MEC (Spain) and by
the European Commission [Marie Curie Research Training Network Aqua
(glycero)porins, MRTN-CT-2006-035995], respectively.Peer reviewe
Assessment of the Potential Use of Compost Filled Plastic Void Forming Units to Serve as Vents on Historic Landfills and Related Sites
Much of the solid municipal waste generated by society is sent to landfill, where biodegrading processes result in the release of methane, a major contributor to climate change. This work examined the possibility of installing a type of biofilter within paved areas of the landfill site, making use of modified pervious paving, both to allow the escape of ground gas and to avoid contamination of groundwater, using specially designed test models with provision for gas sampling in various chambers. It proposes the incorporation of an active layer within a void forming box with a view to making dual use of the pervious pavement to provide both a drainage feature and a ground gas vent, whilst providing an active layer for the oxidation of methane by microbial action. The methane removal was observed to have been effected by microbial oxidation and as such offers great promise as a method of methane removal to allow for development of landfills.<br/
Enhancing Luminescence and X-ray Absorption Capacity of Eu3+:LaF3 Nanoparticles by Bi3+ Codoping
Bi3+ codoping has been proposed in this work with a twofold objective, namely, enhancing the luminescence emission of Eu3+:LaF3 nanoparticles (NPs) and increasing their X-ray attenuation capacity, with the purpose of obtaining a bimodal bioprobe for luminescence bioimaging and X-ray computed tomography. The synthesis method, reported here for the first time for LaF3 particles, allowed obtaining uniform, nonaggregated NPs using a homogeneous precipitation in polyol medium at room temperature in just 2 h. The simplicity of the synthesis method allows the large-scale production of NPs. LaF3 NPs with different Eu3+ contents were first synthesized to find the critical Eu3+ concentration, producing the highest emission intensity. This concentration was subsequently used to fabricate Bi3+-Eu3+-codoped LaF3 NPs using the same method. The emission intensity of the codoped NPs increased in more than one order of magnitude, thanks to the possibility of excitation through the Bi3+ ¿ Eu3+ energy-transfer band. The luminescence properties of the codoped NPs were analyzed in detail to find the mechanism responsible for the emission enhancement. Finally, it was demonstrated that the high atomic number of Bi3+, higher than that of lanthanides, was an added value of the material because it increased its X-ray attenuation capacity. In summary, the LaF3 NPs codoped with Eu3+ and Bi3+ presented in this work are promising candidates as a bimodal bioprobe for luminescence bioimaging and X-ray computed tomography
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
Meeting abstrac
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