318 research outputs found

    Phenological and molecular studies on the introduced seaweed Dictyota cyanoloma (Dictyotales, Phaeophyceae) along the Mediterranean coast of the Iberian Peninsula

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    Dictyota cyanoloma, a distinctive brown algal species characterized by a blue-iridescent margin, was recently reported as an introduced species in the Mediterranean Sea but little is known about its distribution dynamics, morphological plasticity and genetic structure. In this integrative study, we evaluate its past and present occurrence along the Mediterranean Iberian coast, assess the species' phenology in Palamos (Girona, Spain) and analyze the haplotype diversity by sequencing 49 individuals from nine sampling sites for different chloroplast and mitochondrial DNA regions. Although D. cyanoloma currently occurs along all the Mediterranean Iberian coasts (in 19 of 36 localities sampled, mostly in marinas and harbour environments), we were not able to find any herbarium material of this species (at BCN-Phyc and MA) predating the year 1987. In Palamos, D. cyanoloma is present all through the year, with a maximum development in winter and a minimum in summer. Fertile specimens are absent during summer (July and August). Sporophytes are dominant from January to June and gametophytes were found only in February, March and June. Information about the antheridia, which has never been described before, is provided. Two chloroplast and three mitochondrial haplotypes were observed, indicating that multiple introductions of D. cyanoloma occurred in the study area. Additionally, the genetic structure suggests that spread did not occur through simple advancing wave fronts but by several longdistance dispersal events. Further studies employing microsatellite markers could potentially offer a better resolution to unravel expansion and colonisation dynamics of D. cyanoloma in the Mediterranean Sea

    Detección de ruido en aprendizaje semisupervisado con el uso de flujos de datos

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    A menudo, es necesario construir conjuntos de entrenamiento. Si disponemos solamente de un número reducido de objetos etiquetados y de un conjunto numeroso de objetos no etiquetados, podemos construir el conjunto de entrenamiento simulando un flujo de datos no etiquetados de los cuales es necesario aprender para poder incorporarlos al conjunto de entrenamiento. Con el objetivo de prevenir que se deterioren los conjuntos de entrenamiento que se obtienen, en este trabajo se propone un esquema que tiene en cuenta el concept drift, ya que en muchas situaciones la distribución de las clases puede cambiar con el tiempo. Para clasificar los objetos no etiquetados hemos empleado un ensemble de clasificadores y proponemos una estrategia para detectar el ruidoOften, it is necessary to construct training sets. If we have only a small number of tagged objects and a large group of unlabeled objects, we can build the training set simulating a data stream of unlabelled objects from which it is necessary to learn and to incorporate them to the training set later. In order to prevent deterioration of the training set obtained, in this work we propose a scheme that takes into account the concept drift, since in many situations the distribution of classes may change over time. To classify the unlabelled objects we have used an ensemble of classifiers and we propose a strategy to detect the noise after the classification proces

    Engineering physiological environments to advance kidney organoid models from human pluripotent stem cells

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    During embryogenesis, the mammalian kidney arises because of reciprocal interactions between the ureteric bud (UB) and the metanephric mesenchyme (MM), driving UB branching and nephron induction. These morphogenetic processes involve a series of cellular rearrangements that are tightly controlled by gene regulatory networks and signaling cascades. Here, we discuss how kidney developmental studies have informed the definition of procedures to obtain kidney organoids from human pluripotent stem cells (hPSCs). Moreover, bioengineering techniques have emerged as potential solutions to externally impose controlled microenvironments for organoid generation from hPSCs. Next, we summarize some of these advances with major focus On recent works merging hPSC-derived kidney organoids (hPSC-kidney organoids) with organ-on-chip to develop robust models for drug discovery and disease modeling applications. We foresee that, in the near future, coupling of different organoid models through bioengineering approaches will help advancing to recreate organ-to-organ crosstalk to increase our understanding on kidney disease progression in the human context and search for new therapeutics

    Phenological and molecular studies on the introduced seaweed <i>Dictyota cyanoloma</i> (Dictyotales, Phaeophyceae) along the Mediterranean coast of the Iberian Peninsula

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    Dictyota cyanoloma, a distinctive brown algal species characterized by a blue-iridescent margin, was recently reported as an introduced species in the Mediterranean Sea (Steen et al., 2016) but little is known about its distribution dynamics, morphological plasticity and genetic structure. In the present integrative study, we evaluate its past and present occurrence along the Mediterranean Iberian coast, assess the species’ phenology in Palamós (Girona, Spain) and analyze the haplotype diversity by sequencing 49 individuals from nine sampling sites for different chloroplast and mitochondrial DNA regions. Although D. cyanoloma currently occurs along the Mediterranean Iberian coast (in 19 of 36 localities sampled between Algeciras and Llançà, mostly in marinas and harbour environments), we were not able to find any herbarium material of this species (at BCN-Phyc and MA) predating the year 1987. In Palamós, D. cyanoloma is present all through the year, with a maximum development in winter and a minimum in summer. Fertile specimens are absent during summer (July and August). Sporophytes are dominant from January to June and dioecious gametophytes were found only in February, March and June. Information about the antheridia, which has never been described before, is provided. Two chloroplast and three mitochondrial haplotypes were observed, indicating that multiple introductions of D. cyanoloma occurred in the study area. Additionally, the genetic structure suggests that spread did not occur through simple advancing wave fronts but by several long-distance dispersal events. Further studies employing microsatellite markers could potentially offer a better resolution to unravel expansion and colonisation dynamics of D. cyanoloma in the Mediterranean Sea

    Fractures of the tibial plateau. Influence of the type of fracture and precision of the articular reduction on the prognosis

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    Se realizó un estudio retrospectivo en 43 pacientes tratados de 45 fracturas de pilón tibial entre 1990 y 1998. Según la clasificación de Rüedi y Allgöwer 6 fracturas eran tipo I (13,3%), 6 tipo II (13,3%) y 33 tipo III (73,3%). El tratamiento realizado fue manipulación e inmovilización en botín de yeso en 8 fracturas, las seis del tipo I y dos del tipo II. En las 37 fracturas restantes se realizó osteotaxis y osteosíntesis. Los resultados clínicos obtenidos fueron excelentes-buenos en 27 de las fracturas (60%), valorados por parámetros objetivos, pero solo en 16 de las fracturas (35,5%) cuando se valoraron por parámetros subjetivos. Se apreciaron mejores resultados clínicos objetivos/subjetivos cuando se consiguió una buena reducción articular y cuanto menor era el grado de desplazamiento y hundimiento de la fractura; en estos casos fue más difícil obtener una buena reducción articular. En 2 fracturas (25%) tratadas conservadoramente y en 17 (46%) tratadas quirúrgicamente se presentó al menos una complicación. Las fracturas de pilón tibial son fracturas graves, por la frecuencia de lesiones de partes blandas y de otras estructuras con que se asocian y por los resultados mediocres derivados de su tratamiento, que son peores en las fracturas tipo III y cuando no se consigue una correcta reducción articular

    Rethinking organoid technology through bioengineering

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    In recent years considerable progress has been made in the development of faithful procedures for the differentiation of human pluripotent stem cells (hPSCs). An important step in this direction has also been the derivation of organoids. This technology generally relies on traditional three-dimensional culture techniques that exploit cell-autonomous self-organization responses of hPSCs with minimal control over the external inputs supplied to the system. The convergence of stem cell biology and bioengineering offers the possibility to provide these stimuli in a controlled fashion, resulting in the development of naturally inspired approaches to overcome major limitations of this nascent technology. Based on the current developments, we emphasize the achievements and ongoing challenges of bringing together hPSC organoid differentiation, bioengineering and ethics. This Review underlines the need for providing engineering solutions to gain control of self-organization and functionality of hPSC-derived organoids. We expect that this knowledge will guide the community to generate higher-grade hPSC-derived organoids for further applications in developmental biology, drug screening, disease modelling and personalized medicine

    Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR

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    We use fits to recent published CPLEAR data on neutral kaon decays to π+π\pi^+\pi^- and πeν\pi e\nu to constrain the CPT--violation parameters appearing in a formulation of the neutral kaon system as an open quantum-mechanical system. The obtained upper limits of the CPT--violation parameters are approaching the range suggested by certain ideas concerning quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures

    Bodies in the early childhood education classroom: a Bourdieusian analysis of curricular materials

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    To our knowledge, no studies have used Bourdieu's theoretical contributions to frame investigations on how early childhood education (ECE) teaching materials construct body differences in a way that justifies gender inequality. For Bourdieu, the power to classify and grant properties and signs to subjects, does not reside only in the power to impose, but also in the degree to which the vision is anchored within reality. Therefore, the aims of this study is to assess the representation of the body in the curricular materials of ECE classrooms in 10 public centers, by means of quantitative content analysis and to provide, using Pierre Bourdieu's theoretical framework on the construction of the body, a qualitative critical analysis of the gendered discourses on the construction of the body that the visual depictions of the bodies transmit in ECE classrooms based on the perceptions of a group of ECE educators and students. Our results show that these images do not represent children as individuals, but rather as subjects with socially constructed labels that favor stereotypical roles. Both teachers and students relate their own training with the curricular practices they perform in their classrooms suggesting that visual representations are both abstractly embedded into institutional practices as well as practically integrated into educational work through curricular materials. In conclusion, they recognize that the fight against taxonomies and labels with which the body is constructed is a process linked to the identity and autonomy of the agents who are participating in education

    The CPLEAR Electromagnetic Calorimeter

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    A large-acceptance lead/gas sampling electromagnetic calorimeter (ECAL) was constructed for the CPLEAR experiment to detect photons from decays of π0\pi^0s with momentum pπ0800p_{\pi^0} \le 800 MeV/c/c. The main purpose of the ECAL is to determine the decay vertex of neutral-kaon decays \ko \rightarrow \pi^0\pi^0 \rightarrow 4 \gamma and \ko \rightarrow \pi^0\pi^0\pi^0 \rightarrow 6 \gamma. This requires a position-sensitive photon detector with high spatial granularity in rr-, φ\varphi-, and zz-coordinates. The ECAL --- a barrel without end-caps located inside a magnetic field of 0.44 T --- consists of 18 identical concentric layers. Each layer of 1/31/3 radiation length (X0{_0}) contains a converter plate followed by small cross-section high-gain tubes of 2640 mm active length which are sandwiched by passive pick-up strip plates. The ECAL, with a total of 66 X0{_0}, has an energy resolution of σ(E)/E13%/E(GeV)\sigma (E)/E \approx 13\% / \sqrt{E(\mathrm{GeV})} and a position resolution of 4.5 mm for the shower foot. The shower topology allows separation of electrons from pions. The design, construction, read-out electronics, and performance of the detector are described
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