A comparison of numerical modelling techniques for tidal stream turbine analysis

To fully understand the performance of tidal stream turbines for the creation of ocean ren wable energy, a range of computational models is required. We review and compare results from several models at different length scales. Models under review include blade element momentum theory (BEMT), blade element actuation disk RANS-CFD, blade- resolved RANS-CFD and coastal models based on the shallow water equations. Three sets of experimental results are used for model validation

Traditional turbulence methods and novel visualisation techniques for coastal flow model in order to deploy tidal stream turbines

Characteristics of flow in the coastal regions are strongly influenced by the topography of the seabed and understanding of these features is necessary before installation of tidal stream turbines (TST). In this paper, the bathymetry of a potential TST deployment site is surveyed using an echosounder and the resulting data is used in the development of the geometric model. The steady state k-ɛ and transient Large Eddy Simulation (LES) turbulence methods are employed. The stream surface visualisation method employed has important inherent characteristics that can enhance the visual perception of complex flow structures [1]. In this method lighting and shading reinforce the perception of shape and depth, images or textures can be mapped to the surface primitives providing additional visual information, colour and transparency can be used to convey additional data attributes. The results of all cases are compared with the flow data transect gathered by Acoustic Doppler Current Profiler (ADCP). It has been understood that the k-ɛ method can predict the flow pattern with relatively good accuracy near the main features of the domain and the LES model has the ability to simulate some important flow patterns because of the bathymetry

The Use of Unmanned Aerial Systems to Map Intertidal Sediment

This paper describes a new methodology to map intertidal sediment using a commercially available unmanned aerial system (UAS). A fixed-wing UAS was flown with both thermal and multispectral cameras over three study sites comprising of sandy and muddy areas. Thermal signatures of sediment type were not observable in the recorded data and therefore only the multispectral results were used in the sediment classification. The multispectral camera consisted of a Red–Green–Blue (RGB) camera and four multispectral sensors covering the green, red, red edge and near-infrared bands. Statistically significant correlations (>99%) were noted between the multispectral reflectance and both moisture content and median grain size. The best correlation against median grain size was found with the near-infrared band. Three classification methodologies were tested to split the intertidal area into sand and mud: k-means clustering, artificial neural networks, and the random forest approach. Classification methodologies were tested with nine input subsets of the available data channels, including transforming the RGB colorspace to the Hue–Saturation–Value (HSV) colorspace. The classification approach that gave the best performance, based on the j-index, was when an artificial neural network was utilized with near-infrared reflectance and HSV color as input data. Classification performance ranged from good to excellent, with values of Youden’s j-index ranging from 0.6 to 0.97 depending on flight date and site

Dissemination of blaIMP-8 among Enterobacteriaceae isolates from a Buenos Aires Hospital

Entre agosto de 2008 y diciembre de 2011 se detectaron en el Hospital Interzonal General de Agudos «Evita» de Lanús 6 aislamientos de enterobacterias productoras de metalo- β-lactamasas, distribuidos en tres especies: Enterobacter cloacae (4), Klebsiella oxytoca (1) y Citrobacter freundii (1). Los seis aislamientos presentaron un perfi l de multirresistencia y se confi rmó la presencia del gen blaIMP-8. Cinco aislamientos además expresaron la β-lactamasa de espectro extendido PER-2. El gen blaIMP-8 fue hallado como primer casete de un integrón de clase 1. Sin embargo, la secuencia 3´ conservada no pudo detectarse en tres aislamientos. En todos los casos, el gen blaIMP-8 fue transferido por conjugación a Escherichia coli resistente a azida. Mediante PFGE se observó que los cuatro aislamientos de E. cloacae no estuvieron genéticamente relacionados. Estos son los primeros hallazgos de metalo-β-lactamasas en la institución, que sugieren una posible diseminación horizontal del gen blaIMP-8 intra e interespecies.From August 2008 to December 2011, six metallo-β-lactamase-producing isolates, four Enterobacter cloacae, one Klebsiella oxytoca and one Citrobacter freundii, were detected at Hospital Interzonal General de Agudos “Evita” in Lanús. All six isolates showed multiresistant profi les and the presence of the blaIMP-8 gene. Five isolates also expressed PER-2 extended spectrum β-lactamase. The blaIMP-8 gene was found as the fi rst cassette in a class 1 integron. However, the 3´ conserved sequence could not be detected in three isolates. In all cases, blaIMP-8 was transferred by conjugation to azide-resistant Escherichia coli J53. PFGE analysis revealed that the four E. cloacae isolates were not genetically related. These are the fi rst metallo-β-lactamases detected in this institution and our results suggest a possible intra- and inter-species horizontal dissemination of blaIMP-8.Fil: Togneri, Ana M.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Gómez, Sonia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Podestá, Laura B.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Pérez, Marcela P.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Faccone, Diego Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Ríos, Lidia E.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Gañete, Marcelo A.. Hospital Interzonal General de Agudos Evita. Laboratorio de Bacteriología; ArgentinaFil: Anchordoqui, María S. . Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; ArgentinaFil: Pasterán, Fernando G.. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Corso, Alejandra C.. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Area de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Characterisation of a new family of carboxyl esterases with an OsmC domain

Proteins in the serine esterase family are widely distributed in bacterial phyla and display activity against a range of biologically produced and chemically synthesized esters. A serine esterase from the psychrophilic bacterium Pseudoalteromonas arctica with a C-terminal OsmC-like domain was recently characterized; here we report on the identification and characterization of further putative esterases with OsmC-like domains constituting a new esterase family that is found in a variety of bacterial species from different environmental niches. All of these proteins contained the Ser-Asp-His motif common to serine esterases and a highly conserved pentapeptide nucleophilic elbow motif. We produced these proteins heterologously in Escherichia coli and demonstrated their activity against a range of esterase substrates. Two of the esterases characterized have activity of over two orders of magnitude higher than other members of the family, and are active over a wide temperature range. We determined the crystal structure of the esterase domain of the protein from Rhodothermus marinus and show that it conforms to the classical α/β hydrolase fold with an extended ‘lid’ region, which occludes the active site of the protein in the crystal. The expansion of characterized members of the esterase family and demonstration of activity over a wide-range of temperatures could be of use in biotechnological applications such as the pharmaceutical, detergent, bioremediation and dairy industries

Kohonen's algorithm for the numerical parametrisation of manifolds

T. Kohonen has described an algorithm for fitting a k-dimensional grid of points to a set of points taken from a k-manifold in Rn, for k⩽n. The algorithm is inspired by a neural model and bears some of the marks of its ancestry. In this paper we show that if the process converges, it converges to a locally 1-1 mapping of the grid onto the manifold. Hitherto this result has only been proved for the case where k=1

Quantifying target spotting performances with complex geoscientific imagery using ERP P300 responses

Geoscientific data interpretation is a challenging task, which requires the detection and synthesis of complex patterns within data. As a first step towards better understanding this interpretation process, our research focuses on quantitative monitoring of interpreters' brain responses associated with geoscientific target spotting. This paper presents a method that profiles brain responses using electroencephalography (EEG) to detect P300-like responses that are associated with target spotting for complex geoscientific data. In our experiment, eight interpreters with varying levels of expertise and experience were asked to detect features, which are likely to be copper-gold rich porphyry systems within magnetic geophysical data. The target features appear in noisy background and often have incomplete shape. Magnetic images with targets and without targets were shown to participants using the "oddball" paradigm. Event related potentials were obtained by averaging the EEG epochs across multiple trials and the results show delayed P3 response to the targets, likely due to the complexity of the task. EEG epochs were classified and the results show reliable single trial classification of EEG responses with an average accuracy of 83%. The result demonstrated the usability of the P300-like responses to quantify the geoscientific target spotting performances. © 2013 Elsevier Ltd

Studying the Impact of Feature Saliency for Geoscientific Target Detection using Electroencephalography (EEG)

Accuracy and efficiency in geoscientific data interpretation is critically important for the resource industry, as based on these interpretations, significant financial decisions are made for exploration and extraction of resources. This study aims to understand image characteristics that impact interpreters' ability to detect geological targets within magnetic geophysics images. We use the Brain Computer Interface (BCI) approach to profile interpreter's neurological responses to geophysical target images using electroencephalography (EEG). These results are compared with image saliency analysis outputs, specifically the spatial distribution of visual attention peaks. Our experimental results showed that images with a wider dispersion of saliency lead to a lower rate of target detection based on EEG activities of interpreters

Blade root load variations on two scaled industrial tidal turbines

This experimental study investigates blade root load fluctuations for a single turbine immersed in a regular current flow with different ambient turbulence conditions. Two scaled models of industrial prototypes were tested: a 1:28 scale model of the three-bladed horizontal axis turbine of Magallanes Renovables and a 1:20 scale model of the five-bladed horizontal axis turbine of Sabella. The rotor loads were directly measured on the rotation axis with a thrust and torque sensor. The blade roots were equipped with a load-cell measuring two forces and three moments. The variations of the rotor loads (thrust and torque) and the blade root loads (edgewise bending moments and streamwise forces) are compared and the impact of the blade angular position is investigated. A comparison of both scaled models results with those of the IFREMER generic turbine is also presented. The results are anonymised in order to ensure confidentiality

Análisis clínico-epidemiológico de la portación intestinal de enterococos resistentes a vancomicina en una unidad de terapia intensiva Clinical and epidemiologic analysis of intestinal tract colonization with vancomycin-resistant enterococci in an intensive care unit

En un período de cinco meses y 25 días se investigó la portación intestinal de enterococos resistentes a vancomicina (EVR). Se estudiaron 124 pacientes (73%) de 171 admitidos en la unidad de terapia intensiva (UTI), 35 de los cuales (28%) resultaron ser portadores. Los aislamientos de EVR (n=35) fueron identificados como Enterococcus faecium (n=18), Enterococcus gallinarum (n=16) y Enterococcus raffinosus (n=1). Todos los aislamientos estudiados fueron resistentes a vancomicina (VAN) (CIM90= 512 µg/ml) y teicoplanina (CIM90= 32 µg/ml) y portaban el gen vanA. Los estudios de tipificación molecular mostraron un alto grado de homología entre los aislamientos de E. faecium (un clon dominante) y E. gallinarum (dos tipos clonales), sugiriendo su diseminación a modo de brote. No se encontraron diferencias significativas con la edad y el sexo de los pacientes no portadores (p>0,05), pero si con el tiempo de hospitalización y el uso de esquemas antibióticos de amplio espectro (p<0,05), estando estos dos factores asociados al estado de portación. Se deduce de este estudio, la importancia de maximizar las medidas de prevención y control de las infecciones nosocomiales, analizar los esquemas empíricos empleados, tratar de disminuir el tiempo de hospitalización y continuar con los estudios de vigilancia para evaluar la eficacia de las acciones implementadas.<br>Intestinal tract colonization with vancomycin resistant enterococci (VRE) was studied during five months and 25 days. Out of 171 patients hospitalized in the intensive care unit, 124 (73%) were included in this study. Thirty five of them (28%) were recognized as colonized with VRE. VRE isolates (n = 35) were identified as Enterococcus faecium (n=18), Enterococcus gallinarum (n=16), and Enterococcus raffinosus (n=1). All of them were resistant to vancomycin (MIC90= 512 µg/ml) and to teicoplanin (MIC90= 32 µg/ml), having the vanA gene. By means of molecular methods a high homology was found among E. faecium and E. gallinarum isolates, respectively, suggesting their spread as a kind of outbreak. No significant differences in age or sex were found among colonized and non-colonized patients (p>0.05). On the other hand, the hospitalization time and the use of broad-spectrum antibiotics were associated with colonization. From this study we highlight the importance of enhancing all measures of control and prevention of hospital infections, carefully analyzing the empiric antimicrobial schemes, trying to reduce the hospital stage, and following the surveillance to evaluate the efficacy of such procedures