498 research outputs found

    High intragenomic heterogeneity of 16S rRNA genes in a subset of Vibrio vulnificus strains from the western Mediterranean coast

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    Heterogeneity among ribosomal operons in Vibrio vulnificus is purported as a probabilistic indicator of strain virulence and classifies V. vulnificus strains as 16S rRNA genes type A and B. In this study, 16S rRNA genes typing of V. vulnificus strains isolated from the Valencia city coast, in the western Mediterranean, showed that 24 out of 30 isolates were type A, one was type B and five could not be typed. Single strand conformation polymorphism (SSCP) analysis of this gene region revealed complex patterns indicative of intragenomic ribosomal operon sequence heterogeneity. The 16S rRNA genes of three untypeable isolates C27, C30, and C34, along with type A (ATCC 27562) and B (C7184) reference strains, were amplified, cloned and sequenced. The number of unique 16S rRNA gene sequences was 4, 3, and 4 for the environmental isolates. The type strain of the species (ATCC 27562) presented only two 16S rRNA gene types, while the reference isolate C7184 of clinical origin had only one 16S rRNA gene type. Sequences differed from five to 35 bp (99.6% to 97.6% sequence similarity). Areas of variability concentrated in helices 10, 18, and 37 and included variants with short intervening sequences in helix 10. Most of the substitutions showed compensatory mutations suggesting ancient sequence divergence generated by lateral genetransfer. [Int Microbiol 2010; 13(4):179-188

    Reassessing the Ranging Behavior of Black-And-White Ruffed Lemurs (Varecia variegata) in Ranomafana National Park, Madagascar

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    This study investigates black-and-white ruffed lemur (Varecia variegata) space use and movement using autocorrelated kernel density estimation (AKDE), a new methodology available from the continuous-time movement model (ctmm) package in R. Data were collected from 24 adults and subadults (10 males, 11 females, 3 subadult males) living in two adjacent V. variegata communities at Mangevo bush camp in Ranomafana National Park, Madagascar (RNP) for 11 months (February – December 2008) to estimate annual and seasonal patterns of individual and community-level range use. Autocorrelated kernel density estimates generated in this study are compared to earlier kernel density estimates from Baden et al. (2021) to determine whether and to what extent the same patterns emerge. Patterns of annual and seasonal variation are also compared across i) age-sex class, ii) reproductive seasonality, iii) site topography and iv) resource availability and distribution. Results reveal that both annual and seasonal home range size and spatial use varied between males and females, as well as within subgroups. Females exhibited larger annual home ranges than males, though not significantly so, and ranging behaviors varied by reproductive season. The topography of Mangevo appears to be a significant driver of range use, as mountain ridges, community boundaries (i.e., territorial space use), and neighborhoods are all structured around the distribution of food resources which are situated primarily at lower elevations between ridgelines throughout the ruffed lemur community

    Antiplatelet and anticoagulant therapy after coronary-artery stenting

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    To the Editor: Schömig et al. (April 25 issue) report that they did not observe neutropenia in any of the 257 patients receiving short-term ticlopidine therapy after coronary stenting

    Creep Burst Testing of a Woven Inflatable Module

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    A woven Vectran inflatable module 88 inches in diameter and 10 feet long was tested at the NASA Johnson Space Center until failure from creep. The module was pressurized pneumatically to an internal pressure of 145 psig, and was held at pressure until burst. The external environment remained at standard atmospheric temperature and pressure. The module burst occurred after 49 minutes at the target pressure. The test article pressure and temperature were monitored, and video footage of the burst was captured at 60 FPS. Photogrammetry was used to obtain strain measurements of some of the webbing. Accelerometers on the test article measured the dynamic response. This paper discusses the test article, test setup, predictions, observations, photogrammetry technique and strain results, structural dynamics methods and quick-look results, and a comparison of the module level creep behavior to the strap level creep behavior

    Atmospheric polarimetric effects on GNSS radio occultations: the ROHP-PAZ field campaign

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    The ROHP-PAZ mission will collect, for the first time, GPS radio occultations at two polarizations with the aim of characterizing rain. Prior to the mission's launch (2016), a field campaign has been conducted to identify and understand the measurements. In this study we present the set-up and the results of such a campaign: the main finding is the confirmation of sensitivity to heavy rain and, unexpectedly, to other frozen hydrometeors. This is key information for the spaceborne experiment.This study was conducted under the Spanish ACI2010-1089 and AYA2011-29183-C02-02 grant, with contributions from EUMETSAT’s ROM SAF CDOP2

    Atmospheric polarimetric effects on GNSS radio occultations: the ROHP-PAZ field campaign

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    This study describes the first experimental observations showing that hydrometeors induce polarimetric signatures in global navigation satellite system (GNSS) signals. This evidence is relevant to the PAZ low Earth orbiter, which will test the concept and applications of polarimetric GNSS radio occultation (RO) (i.e. ROs obtained with a dual-polarization antenna). A ground field campaign was carried out in preparation for PAZ to verify the theoretical sensitivity studies on this concept (Cardellach et al., 2015). The main aim of the campaign is to identify and understand the factors that might affect the polarimetric GNSS observables. Studied for the first time, GNSS signals measured with two polarimetric antennas (H, horizontal, and V, vertical) are shown to discriminate between heavy rain events by comparing the measured phase difference between the H and V phase delays (ΔΦ) in different weather scenarios. The measured phase difference indicates higher dispersion under rain conditions. When individual events are examined, significant increases in ΔΦ occur when the radio signals cross rain cells. Moreover, the amplitude of such a signal is much higher than the theoretical prediction for precipitation; thus, other sources of polarimetric signatures have been explored and identified. Modelling of other hydrometeors, such as melting particles and ice crystals, have been proposed to explain the obtained measurements, with good agreement in more than 90 % of the cases

    Diseño de un cuestionario para evaluar conocimientos didáctico-matemáticos sobre razonamiento algebraico elemental

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    La promoció del pensament algebraic en alumnes de primària requereix implementar accions formatives específiques per als professors, la qual cosa al seu torn implica elaborar instruments d'avaluació de l'estat dels seus coneixements didàctic - matemàtics sobre el tema. En aquest treball presentem resultats de l'estudi realitzat per a la construcció d'un qüestionari d'avaluació dels coneixements didàctic - matemàtics d'estudiants de magisteri sobre raonament algebraic elemental. Descrivim les categories de coneixements algebraics tingudes en compte (estructures, funcions i modelització) i les categories de coneixements didàctics (facetes epistèmica, cognitiva, instruccional i ecològica). Així mateix es descriuen i analitzen les tasques incloses en el qüestionari informant de la validesa de contingut del mateix.Promoting algebraic thinking in elementary school pupils requires implementing specific training activities for teachers, which in turn involves developing tools to assess their didactic-mathematical knowledge about this subject. In this paper we present results of a study aimed to build a questionnaire for assessing the didactic-mathematic knowledge of prospective primary teachers on elementary algebraic reasoning. We describe the categories of algebraic knowledge (structures, functions and modeling), as well as the categories of didactical knowledge (epistemic, cognitive, instructional and ecological facets) taken into account. We also describe and analyze the tasks included in the questionnaire reporting its content validity.La promoción del pensamiento algebraico en alumnos de primaria requiere implementar acciones formativas específicas para los profesores, lo que a su vez implica elaborar instrumentos de evaluación del estado de sus conocimientos didáctico - matemáticos sobre el tema. En este trabajo presentamos resultados del estudio realizado para la construcción de un cuestionario de evaluación de los conocimientos didáctico - matemáticos de estudiantes de magisterio sobre razonamiento algebraico elemental. Describimos las categorías de conocimientos algebraicos tenidas en cuenta (estructuras, funciones y modelización) y las categorías de conocimientos didácticos (facetas epistémica, cognitiva, instruccional y ecológica). Así mismo se describen y analizan las tareas incluidas en el cuestionario informando de la validez de contenido del mismo

    Designing CDIO capstone projects: a systems thinking approach

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    Given the all-pervasiveness of Systems thinking -which consists of thinking about things as systemsas a way of reasoning, in this work we will describe its application to make an interpretation of how to conceive and design a final year CDIO capstone course. Both the student teamwork structure as well as the complex engineering system itself addressed in the project are described in terms of entities, links, form and function, thereby pointing out their formal and functional interaction. The ultimate goal of the Systems thinking perspective is, given the necessary ingredients, to try maximizing the chances of the emergence of a fruitful capstone course, namely a culminating project that yields a set of students qualified to CDIO complex engineering systems.Peer ReviewedPostprint (published version

    Etnomatemáticas en artesanías de trenzado: un modelo metodológico para investigación

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    El área temática del Proyecto de Investigación, parte del cual exponemos en este artículo, es Etnomatemáticas. El propósito de investigación es la caracterización y valoración del conocimiento socio-cultural, implícito en la práctica diaria. En el contexto geográfico de Argentina, investigamos la matemática implícita en artesanías de trenzados, elaborando para esto un método propio de análisis etnomatemático. El instrumento metodológico MOMET que se crea para este estudio interpretativo formal de artesanías de trenzado tiene en cuenta dos aspectos: el producto final de la labor artesanal analizado en su complejidad global y el proceso que se lleva a cabo para realizarlo. La herramienta metodológica elaborada está constituida por dos componentes: un Método de análisis etnográfico (MET) y un Modelo de análisis matemático (MOM). El conjunto de los dos nos proporciona el instrumento metodológico MOMET, que permite la Modelización Etnomatemática de las artesanías de trenzado
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