21,321 research outputs found

    Empirical likelihood confidence intervals for complex sampling designs

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    We define an empirical likelihood approach which gives consistent design-based confidence intervals which can be calculated without the need of variance estimates, design effects, resampling, joint inclusion probabilities and linearization, even when the point estimator is not linear. It can be used to construct confidence intervals for a large class of sampling designs and estimators which are solutions of estimating equations. It can be used for means, regressions coefficients, quantiles, totals or counts even when the population size is unknown. It can be used with large sampling fractions and naturally includes calibration constraints. It can be viewed as an extension of the empirical likelihood approach to complex survey data. This approach is computationally simpler than the pseudoempirical likelihood and the bootstrap approaches. The simulation study shows that the confidence interval proposed may give better coverages than the confidence intervals based on linearization, bootstrap and pseudoempirical likelihood. Our simulation study shows that, under complex sampling designs, standard confidence intervals based on normality may have poor coverages, because point estimators may not follow a normal sampling distribution and their variance estimators may be biased.<br/

    Fluctuations of a surface relaxation model in interacting scale free networks

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    Isolated complex networks have been studied deeply in the last decades due to the fact that many real systems can be modeled using these types of structures. However, it is well known that the behavior of a system not only depends on itself, but usually also depends on the dynamics of other structures. For this reason, interacting complex networks and the processes developed on them have been the focus of study of many researches in the last years. One of the most studied subjects in this type of structures is the Synchronization problem, which is important in a wide variety of processes in real systems. In this manuscript we study the synchronization of two interacting scale-free networks, in which each node has keke dependency links with different nodes in the other network. We map the synchronization problem with an interface growth, by studying the fluctuations in the steady state of a scalar field defined in both networks. We find that as keke slightly increases from ke=0ke=0, there is a really significant decreasing in the fluctuations of the system. However, this considerable improvement takes place mainly for small values of keke, when the interaction between networks becomes stronger there is only a slight change in the fluctuations. We characterize how the dispersion of the scalar field depends on the internal degree, and we show that a combination between the decreasing of this dispersion and the integer nature of our growth model are the responsible for the behavior of the fluctuations with keke.Comment: 11 pages, 4 figures and 1 tabl

    SACY - a Search for Associations Containing Young stars

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    The scientific goal of the SACY (Search for Associations Containing Young-stars) was to identify possible associations of stars younger than the Pleiades Association among optical counterparts of the ROSAT X-ray bright sources. High-resolution spectra for possible optical counterparts later than G0 belonging to HIPPARCOS and/or TYCHO-2 catalogs were obtained in order to assess both the youth and the spatial motion of each target. More than 1000 ROSAT sources were observed, covering a large area in the Southern Hemisphere. The newly identified young stars present a patchy distribution in UVW and XYZ, revealing the existence of huge nearby young associations. Here we present the associations identified in this survey.Comment: 8 pages, 2 figures, to appear in the Proceedings of Open Issues in Local Formation and Early Stellar Evolution, Ouro Preto, Brazi

    Dual Role of Subphthalocyanine Dyes for Optical Imaging and Therapy of Cancer

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    This is the peer-reviewed version of the following article: van de Winckel, E., Mascaraque, M., Zamarrón, A., Juarranz de la Fuente, Á., Torres, T., & de la Escosura, A. (2018). Dual role of subphthalocyanine dyes for optical imaging and therapy of cancer. Advanced Functional Materials, 28(24), 1705938., which has been published in final form at https://doi.org/10.1002/adfm.201705938. This article may be used for non-commercial purposes in accordance with Wiley-VCH Terms and Conditions for Self-ArchivingThe family of subphthalocyanine (SubPc) macrocycles represents an interesting class of nonplanar aromatic dyes with promising features for energy conversion and optoelectronics. The use of SubPcs in biomedical research is, on the contrary, clearly underexplored, despite their documented high fluorescence and singlet oxygen quantum yields. Herein, for the first time it is shown that the interaction of these chromophores with light can also be useful for theranostic applications, which in the case of SubPcs comprise optical imaging and photodynamic therapy (PDT). In particular, the article evaluates, through a complete in vitro study, the dual-role capacity of a novel series of SubPcs as fluorescent probes and PDT agents, where the macrocycle axial substitution determines their biological activity. The 2D and 3D imaging of various cancer cell lines (i.e., HeLa, SCC-13, and A431) has revealed, for example, different subcellular localization of the studied photosensitizers (PS), depending on the axial substituent they bear. These results also show excellent photocytotoxicities, which are affected by the PS localization. With the best dual-role PS, preliminary in vivo studies have demonstrated their therapeutic potential. Overall, the present paper sets the bases for an unprecedented biomedical use of these well-known optoelectronic materials.E.v.d.W. and M.M. contributed equally to this work. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Program FP7‐PEOPLE‐2012‐ITN under REA grant agreement No. GA 316975. AdlE holds a Ramón y Cajal contract from the Spanish Ministry of Economy (MINECO). This work was supported by EU (CosmoPHOS‐nano, FP7‐NMP‐2012‐6, 310337‐2; GLOBASOL, FP7‐ENERGY‐2012‐J, 309194‐2), the Spanish MINECO (CTQ‐2014‐52869‐P (TT) and CTQ‐2014‐53673‐P (AdlE)), CAM (FOTOCARBON, S2013/MIT‐2841), grants from Instituto de Salud Carlos III, MINECO and Feder Funds (PI15/00974) and by S2010/BMD‐2359 from Comunidad de Madrid

    Synchronization in interacting Scale Free Networks

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    We study the fluctuations of the interface, in the steady state, of the Surface Relaxation Model (SRM) in two scale free interacting networks where a fraction qq of nodes in both networks interact one to one through external connections. We find that as qq increases the fluctuations on both networks decrease and thus the synchronization reaches an improvement of nearly 40%40\% when q=1q=1. The decrease of the fluctuations on both networks is due mainly to the diffusion through external connections which allows to reducing the load in nodes by sending their excess mostly to low-degree nodes, which we report have the lowest heights. This effect enhances the matching of the heights of low-and high-degree nodes as qq increases reducing the fluctuations. This effect is almost independent of the degree distribution of the networks which means that the interconnection governs the behavior of the process over its topology.Comment: 13 pages, 7 figures. Added a relevant reference.Typos fixe

    Estudio de los Portafolios en el Practicum: An álisis de un PLE - Portafolio

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    The specialized literature agrees to notice that even existing some conditions, it is not a generalized methodology at universities. In the new grades and knowledge areas is found the subject of external practices that would be able to show conditions for using the portfolios. Whereas, there are some questions in the educational area: What conditions exist for the use of the portfolios in the Practicum of the education grades in Spain? What level of utilization are evident? What problems of understanding, the students express about the documentation of evidences in portfolios? The research performs a mixed methodology: a first quantitative study with descriptive methodology, interview to 31 coordinators of Practicum of all grades in 10 (20%) Faculty of Education, along with a qualitative study and content analysis of 256 Practicum guides of all grades of 36 (72%) Faculties of Education of public universities in Spain. A second case study, perform a content analysis of 592 annotations of 212 students to show and evaluate the evidences in ePortfolios of the Practicum of the degree of Pedagogy. The results reveal that there are 11 students per tutor 2,88h medium for tutoring and assess ePortfolios. Being mail (between 37.77% and 46.66%) followed by the platforms most used technologies. The eRúbricas and video annotations help document the evidence, however, students still show difficulties in some competencesFunded by Spanish Plan of R+D+i Excellence (2014-16) No. EDU2013-41974P. Project entitled: “Study of the Impact of Federated eRubrics on Assessing Competences in the Practicum”. http://goo.gl/u07aN

    Zeta Potential of Modified Multi-walled Carbon Nanotubes in Presence of poly (vinyl alcohol) Hydrogel

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    The main objective of this study is investigate the behavior of the Zeta Potential of the MWCNT modified with SDS(Sodium Dodecyl Sulfate) and CTAB(Cetyl Tetraethyl Ammonium Bromide) in presence of PVA. Full hydrolyzed PVA was used. As a result, adding PVA in the CNT solution led to decrease the Zeta Potential. The Zeta Potential of suspended colloid varied from 42.00mV to 6.48mV and -45.00mV to -6.4mV at 1.5% concentration of PVA; according with the changing pH, the Zeta Potential dropped to near zero at pH 3 and 11. The pH and PVA has strong influence in the reduction of ZP of MWCNT solution. MWCNT-PVA solution with 33.30mV, -35.69mV at 0.01% of PVA was exposed under AC field; a uniform coat was obtained, with the SDS-MWCNT-PVA solution.National Natural Science Foundation of China Project (Grant No.51073024), the Royal Society-NSFC international joint project (Grant No.51111130207) and Beijing Municipal Science and Technology Plan Projects (No. Z111103066611005)
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