1,969 research outputs found
Random matrix study for a three-terminal chaotic device
We perform a study based on a random-matrix theory simulation for a
three-terminal device, consisting of chaotic cavities on each terminal. We
analyze the voltage drop along one wire with two chaotic mesoscopic cavities,
connected by a perfect conductor, or waveguide, with one open mode. This is
done by means of a probe, which also consists of a chaotic cavity that measure
the voltage in different configurations. Our results show significant
differences with respect to the disordered case, previously considered in the
literature.Comment: Proccedings of the V Leopoldo Garcia-Colin Mexican Meeting on
Mathematical and Experimental Physic
Cerium-based conversion coatings on magnesium alloys
This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 Mg alloys using a range of deposition times (5 to 180 s) and temperatures (10 to 80 ºC). However, shorter deposition times (5 s) and lower deposition temperatures (~10 ºC) showed higher impedance and longer bath stability than other deposition conditions. The increase in impedance was related with fewer cracks and smaller nodule sizes. Additional investigations of post-treated CeCCs exposed to NaCl environments showed an increased in the total impedance. The increase in corrosion protection of the CeCCs was associated with an overall increase in coating thickness from 400 to 800 nm. A microstructural evolution from ~3 nm nodular nanocrystals of CeO₂/CePO₄·H₂O embedded in an amorphous matrix to \u3e50 nm CePO₄·H₂O nanocrystals was responsible for the electrochemically active corrosion protection. Exposure of CeCCs to sunlight in humid environments promoted the reduction of Ce(IV) into Ce(III) species compared to unexposed coatings. This reduction process was related with photocatalytic water oxidation reaction. --Abstract, page iv
Miscellaneous bean viruses
Bean crops are attacked by several viruses transmitted by insects among which are: (1) the alfalfa mosaic virus (aphids); susceptibility is correlated with plant age; (2) curly top (Circulifer tenellus); the best control measure is the utitilization of resistant var.; (3) bean summer death (Orosius argentatus); (4) tomato spotted wilt virus, which is transmitted mechanically and by various types of thrips; (5) red node, which is transmitted mechanically and in the seed. Insect vectors have not been reported; it can be controlled using resistant var. (CIAT)El cultivo del frijol es atacado por varios virus transmitidos por insectos, entre los cuales estan: 1) el virus del mosaico de la alfalfa (afidos); la susceptibilidad esta correlacionada con la edad de la planta; 2) el virus del apice rizado (Circulifer tenellus); la mejor medida de control es el uso de var. resistentes; 3) la muerte de verano del frijol (Orosius argentatus); 4) virus del marchitamiento manchado del tomate, el cual se transmite mecanicamente y por varias clases de trips; 5) el nudo rojo, el cual se transmite mecanicamente y por medio de la semilla. No se han observado insectos vectores; se puede controlar usando var. resistentes. (CIAT
Phantom Membrane Microfluidic Cross-Flow Filtration Device for the Direct Optical Detection of Water Pollutants
The diffusion of autonomous sensing platforms capable of a remote large-scale surveillance of environmental water basins is currently limited by the cost and complexity of standard analytical methods. In order to create a new generation of water analysis systems suitable for continuous monitoring of a large number of sites, novel technical solutions for fluid handling and detection are needed. Here we present a microfluidic device hosting a perfluorinated microporous membrane with refractive index similar to that of water, which enables the combination of filtration and label-free sensing of adsorbing substances, mainly pollutants, in environmental water samples. The cross-flow design of the microfluidic device avoids the clogging of the membrane due to particulate, whereas molecules with some hydrophobic moiety contained in the crossing flow are partially retained and their adhesion on the inner surface of the membrane yields an increase of light scattering intensity, which can be easily measured using a simple instrument based on Light Emitting Diode illumination. By cycling sample water and pure water as a reference, we demonstrate the detection of 0.5 microM of a model cationic surfactant and regeneration of the sensing surface. The optical response of the membrane sensor was characterized using a simple theoretical model that enables to quantify the concentration of target molecules from the amplitude and kinetics of the measured binding curves. The device was tested with real water samples containing large amount of environmental particles, without showing clogging of the membrane, and enabling nonspecific quantification of adsorbing substances in a few minutes.This project has received funding from the European Union’s Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration through the NAPES project(grant agreement no. 604241). FBL acknowledges the Ramón y CajalProgramme (Ministerio de Economía y Competitividad), Spain. FBL personally acknowledges to Elkartek (KK-2015/00088) Grant from the Gobierno Vasco and funding support from Gobierno de España, Ministerio de Economia y Competitividad, with Grant No. BIO2016-80417-P and to Marian M. De Pancorbo for letting him to use her laboratory facilities at UPV/EHU. PSA was generously provided byAdhesive Research, Ireland. We thank Aurora Giavazzi for helping in the collection of river water samples
Sulfur-enhanced thermoluminescence of γ-radiated zirconia
Sulfur-modified zirconia with various S contents have been characterized and analyzed for potential applications in dosimetry. The thermoluminescent signal induced by gamma radiation in pure zirconia and sulfated zirconia in the tetragonal phase has been considered. Experimental results show that the thermoluminescent glow peak depends on both the crystalline structure and sulfate concentration and that the response is linear for an ample range of irradiation.Зразки модифікованої сірого двоокису цирконію з різним вмістом сірки охарактеризовано і проаналізовано з точки зору потенційного застосування в дозиметрії. Розглянуто термолюмінісцентний сигнал, викликаний гамма-випромінюванням в чистому і сульфатованому двоокису цирконію в тетрагональної фазі. Експериментальні результати показують, що пік термолюмінісцентного світіння залежить як від кристалічної структури, так і від концентрації сульфату. Ця характеристика лінійна для великого діапазону опромінення.Образцы модифицированной серой двуокиси циркония с различным содержанием серы охарактеризованы и проанализированы с точки зрения потенциального применения в дозиметрии. Рассмотрен термолюминисцентный сигнал, вызванный гамма-излучением в чистой и сульфатированной двуокиси циркония в тетрагональной фазе. Экспериментальные результаты показывают, что пик термолюминисцентного свечения зависит как от кристаллической структуры, так и от концентрации сульфата. Эта характеристика линейна для большого диапазона облучения
Automatic plankton quantification using deep features
The study of marine plankton data is vital to monitor the health of the world’s oceans. In recent decades, automatic plankton recognition systems have proved useful to address the vast amount of data collected by specially engineered in situ digital imaging systems. At the beginning, these systems were developed and put into operation using traditional automatic classification techniques, which were fed with handdesigned local image descriptors (such as Fourier features), obtaining quite successful results. In the past few years, there have been many advances in the computer vision community with the rebirth of neural networks. In this paper, we leverage how descriptors computed using Convolutional Neural Networks (CNNs) trained with out-of-domain data are useful to replace hand-designed descriptors in the task of estimating the prevalence of each plankton class in a water sample. To achieve this goal, we have designed a broad set of experiments that show how effective these deep features are when working in combination with state-of-the-art quantification algorithms
Insights from quantitative and mathematical modelling on the proposed 2030 goal for gambiense human African trypanosomiasis (gHAT)
Gambiense human African trypanosomiasis (gHAT) is a parasitic, vector-borne neglected tropical disease that has historically affected populations across West and Central Africa and can result in death if untreated. Following from the success of recent intervention programmes against gHAT, the World Health Organization (WHO) has defined a 2030 goal of global elimination of transmission (EOT). The key proposed indicator to measure achievement of the goal is to have zero reported cases. Results of previous mathematical modelling and quantitative analyses are brought together to explore both the implications of the proposed indicator and the feasibility of achieving the WHO goal.
Whilst the indicator of zero case reporting is clear and measurable, it is an imperfect proxy for EOT and could arise either before or after EOT is achieved. Lagging reporting of infection and imperfect diagnostic specificity could result in case reporting after EOT, whereas the converse could be true due to underreporting, lack of coverage, and cryptic human and animal reservoirs. At the village-scale, the WHO recommendation of continuing active screening until there are three years of zero cases yields a high probability of local EOT, but extrapolating this result to larger spatial scales is complex.
Predictive modelling of gHAT has consistently found that EOT by 2030 is unlikely across key endemic regions if current medical-only strategies are not bolstered by improved coverage, reduced time to detection and/or complementary vector control. Unfortunately, projected costs for strategies expected to meet EOT are high in the short term and strategies that are cost-effective in reducing burden are unlikely to result in EOT by 2030. Future modelling work should aim to provide predictions while taking into account uncertainties in stochastic dynamics and infection reservoirs, as well as assessment of multiple spatial scales, reactive strategies, and measurable proxies of EOT
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