656 research outputs found

    A new non-parametric estimator of the cumulative distribution function under time-and random-censoring

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    In this paper, we first provide a review of different non-parametric estimators for the cumulative distribution function under left-censoring. We then propose a new estimator based on a non-parametric likelihood approach using reversed hazard rate. Finally, we conclude with an application to a real data

    A Tylosaurine Mosasauridae (Squamata) from the Late Cretaceous of the Basque-Cantabrian Region

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    An isolated mosasaurid tooth from the Campanian of Alava (Basque Country), previously referred to as cf. Mosasaurus sp., is here reattributed to a tylosaurine. It may belong to Tylosaurus, a nearly cosmopolitan genus known from the Santonian-Maastrichtian. This is the first occurrence of a tylosaurine mosasaurid in the Iberian Peninsula. Moreover, it corresponds to the southernmost occurrence of this clade in the northern margin of the Mediterranean Tethys. ylosaurinae fossils are known from North America, Europe, New Zealand, Antarctica, Africa and Asia, but remain unknown from the southern Mediterranean Tethyan margin and from tropical palaeolatitudes.Un diente aislado de mosasaurio procedente del Campaniense de Álava (País Vasco), previamente asignado a cf. Mosasaurus sp., se atribuye en este trabajo a un tilosaurino. Podría pertenecer a Tylosaurus, un género cuasi cosmopolita del Santoniense-Maastrichtiense. Es la primera cita de un mosasáurido tilosaurino en la Península Ibérica. Además, se trata del registro más meridional de este clado en el margen norte del Tetis mediterráneo. Los Tylosaurinae están representados por fósiles en Norteamérica, Europa, Nueva Zelanda, Antártida, África y Asia, pero carecen de registro en el margen sur del Tetis mediterráneo y en paleolatitudes tropicales

    Optically Induced Modulation of a Laser Beam in Nematic Liquid Crystals Structures

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    In this paper we report the experimental results obtained when an He-Ne laser beam crosses an MBBA homeotropic sandwich structure and is modulated by the influence of another laser beam, in our case an Ar+ laser, crossing through the same region. We extend some results previously reported by us1 2 concerning the influence of the ratio of the diameters of the laser beams on the modulation characteristics. A theoretical model, based on the one reported in Ref6 , shows good agreement with the experimental results. If the Ar+ laser is intensity chopped, the resulting He-Ne diffracted image is also intensity modulated. The highest frequency observed has been 500 p. p. s

    Los Monteros de Espinosa

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    Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

    Epidemiology of online sexual solicitation and interaction of minors with adults: A longitudinal study

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    Background: There have been very few longitudinal studies on online sexual solicitation and the online interaction between minors and adults. Still less evidence exists on the relationship of these problems with minors' Health-Related Quality of Life (HRQoL). Objective: This study aimed to analyze the point prevalence, period prevalence (prevalence over time) and incidence (new cases over time) of online sexual solicitation and interactions between minors and adults throughout three consecutive time periods and to compare the HRQoL among categories of victims (non-victims, new victims, ceased victims, intermittent victims, and stable victims). Participants and setting: The participants were 1029 Spanish students (43 % boys, 57 % girls), aged 12–15 years. Methods: A longitudinal study was conducted over a 13-month period, with measurements taken at three time points. Results: For sexual solicitation, the point prevalence was 11.3 % at wave 1 (W1), 11.9 % at wave 2 (W2), and 16.1 % at wave 3 (W3). For sexualized interactions, prevalence rates were 4.8 %, 7 %, and 7.1 %, respectively. However, throughout the study, almost 23 % of minors reported some sexual solicitation and 14 % reported some sexual interaction. In this same period of time, the incidence of new cases was 1 in 10. Being a victim during W1 meant that in W3, there was almost twice the risk of having a low HRQoL. In general, those who were not victims of either solicitation or sexualized interactions with adults presented better HRQoL than those who experienced victimization. Conclusions

    Comparative study of nonlinear properties of EEG signals of a normal person and an epileptic patient

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    Background: Investigation of the functioning of the brain in living systems has been a major effort amongst scientists and medical practitioners. Amongst the various disorder of the brain, epilepsy has drawn the most attention because this disorder can affect the quality of life of a person. In this paper we have reinvestigated the EEGs for normal and epileptic patients using surrogate analysis, probability distribution function and Hurst exponent. Results: Using random shuffled surrogate analysis, we have obtained some of the nonlinear features that was obtained by Andrzejak \textit{et al.} [Phys Rev E 2001, 64:061907], for the epileptic patients during seizure. Probability distribution function shows that the activity of an epileptic brain is nongaussian in nature. Hurst exponent has been shown to be useful to characterize a normal and an epileptic brain and it shows that the epileptic brain is long term anticorrelated whereas, the normal brain is more or less stochastic. Among all the techniques, used here, Hurst exponent is found very useful for characterization different cases. Conclusions: In this article, differences in characteristics for normal subjects with eyes open and closed, epileptic subjects during seizure and seizure free intervals have been shown mainly using Hurst exponent. The H shows that the brain activity of a normal man is uncorrelated in nature whereas, epileptic brain activity shows long range anticorrelation.Comment: Keywords:EEG, epilepsy, Correlation dimension, Surrogate analysis, Hurst exponent. 9 page

    Ultrasound-assisted exfoliation of a layered 2D coordination polymer with HER electrocatalytic activity

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    Altres ajuts: the ICN2 is funded by the CERCA programme/Generalitat de Catalunya. Noemí Contreras Pereda's project that gave rise to these results received the support of a fellowship from "laCaixa" Foundation (ID 100010434). The fellowship code is LCF/BQ/ES17/11600012. Renhao Dong acknowledgements the financial support DFG project (SPP 1928, COORNETs).Large blue rectangular crystals of the 2D layered coordination polymer 1 have been obtained. The interest for this complex is two-fold. First, complex 1 is made of 2D layers packing along the (0-11) direction favored by the presence of lattice and coordinated water molecules. And second, nanostructures that could be derived by delamination are potentially suitable for catalytic purposes. Therefore it represents an excellent example to study the role of interlayer solvent molecules on the ultrasound-assisted delamination of functionally-active 2D metal-organic frameworks in water, a field of growing interest. With this aim, ultrasound-assisted delamination of the crystals was optimized with time, leading to stable nanosheet colloidal water suspensions with very homogeneous dimensions. Alternative bottom-up synthesis of related nanocrystals under ultrasound sonication yielded similar shaped crystals with much higher size dispersions. Finally, experimental results evidence that the nanostructures have higher catalytic activities in comparison to their bulk counterparts, due to larger metallic center exposition. These outcomes confirm that the combination of liquid phase exfoliation and a suitable synthetic design of 2D coordination polymers represents a very fruitful approach for the synthesis of functional nanosheets with an enhancement of catalytic active sites, and in general, with boosted functional properties

    Solvent-tuned ultrasonic synthesis of 2D coordination polymer nanostructures and flakes

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    Altres ajuts: the ICN2 is funded by the CERCA programme / Generalitat de Catalunya. Noemí Contreras Pereda's project that gave rise to these results received the support of a fellowship from "laCaixa" Foundation (ID 100010434). The fellowship code is LCF/BQ/ES17/11600012.Herein, a new 2-dimensional coordination polymer based on copper (II), {Cu₂(L)(DMF₂)}n, where L stands for 1,2,4,5-benzenetetracarboxylate (complex 1) is synthesized. Interestingly, we demonstrate that both solvent and sonication are relevant in the top-down fabrication of nanostructures. Water molecules are intercalated in suspended crystals of complex 1 modifying not only the coordination sphere of Cu(II) ions but also the final chemical formula and crystalline structure obtaining {[Cu(L)(H₂O)₃]·H₂O}n (complex 2). On the other hand, ultrasound is required to induce the nanostructuration. Remarkably, different morphologies are obtained using different solvents and interconversion from one morphology to another seems to occur upon solvent exchange. Both complexes 1 and 2, as well as the corresponding nanostructures, have been fully characterized by different means such as infrared spectroscopy, x-ray diffraction and microscopy

    Combination of X-ray crystallography, SAXS and DEER to obtain the structure of the FnIII-3,4 domains of integrin a6b4

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    Integrin alpha6beta4 is a major component of hemidesmosomes that mediate the stable anchorage of epithelial cells to the underlying basement membrane. Integrin alpha6beta4 has also been implicated in cell proliferation and migration and in carcinoma progression. The third and fourth fibronectin type III domains (FnIII-3,4) of integrin beta4 mediate binding to the hemidesmosomal proteins BPAG1e and BPAG2, and participate in signalling. Here, it is demonstrated that X-ray crystallography, small-angle X-ray scattering and double electron– electron resonance (DEER) complement each other to solve the structure of the FnIII-3,4 region. The crystal structures of the individual FnIII-3 and FnIII-4 domains were solved and the relative arrangement of the FnIII domains was elucidated by combining DEER with site-directed spin labelling. Multiple structures of the interdomain linker were modelled by Monte Carlo methods complying with DEER constraints, and the final structures were selected against experimental scattering data. FnIII-3,4 has a compact and cambered flat structure with an evolutionary conserved surface that is likely to correspond to a protein-interaction site. Finally, this hybrid method is of general application for the study of other macromolecules and complexes

    Economic and Productive Characterization of Dairy Units Integrated to the Municipal Cattle Raising Program (PROGRAM) in the Province of Camagüey, Cuba.

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    The economic and productive behaviors  of dairy units were characterized between 2009 and 2013, integrated to the Municipal Cattle Raising Program (PROGRAM).Ten dairy farms were chosen in the study, grouped in four agricultural enterprises of Camagüey.  The main principle of the experiment was to achieve food self-sufficiency  in the farms. The study was divided into three stages: (I) characterization of limitations by a farm diagnostics; (II) proposal and incorporation of technologies; (III) follow up and evaluation of results. The analysis included economic and productive indicators suggested by the Ministry of Agriculture. Forage balances were made, and  a  pasture-forage arrangement was set up, according to the results provided by the REGPAST software. The methodology established by Toro (2011) was used for characterization  in  three stages:  variable reviewing  and selection,  Principal  Component Analysis, and Conglomerate Analysis. The results showed an increase of economic and productive indicators at the end of the stage, which helped determine system behavior. Moreover, all the indicators selected were included in some components, which explains the 89 % of total variability. Accordingly, three groups of dairy units were set up, corresponding with the development programs for each, with mean values of 1 553.0 kg per hectare for  the first group; 874.25 kg, for the second; and 1 361.67 kg, in the third group
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