6,259 research outputs found

    Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope

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    We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different techniques are used, which are organized in an automatic periodicity-search pipeline, in order to search for evidence of periodic emission in gamma rays. Understanding the processes behind this puzzling phenomenon will provide a better view about the astrophysical nature of these extragalactic sources. However, the observation of temporal patterns in gamma-ray light curves of AGN is still challenging. Despite the fact that there have been efforts on characterizing the temporal emission of some individual sources, a systematic search for periodicities by means of a full likelihood analysis applied to large samples of sources was missing. Our analysis finds 11 AGN, of which 9 are identified for the first time, showing periodicity at more than 4sigma in at least four algorithms. These findings will help in solving questions related to the astrophysical origin of this periodic behavior.Comment: 16 pages, 5 figures, 4 tables. Accepted by Ap

    Methods for the Isolation of Sensory and Primary Cilia—An Overview

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    Detailed proteomic analyses of mammalian olfactory and rod photoreceptor sensory cilia are now available, providing an inventory of resident ciliary proteins and laying the foundation for future studies of developmental and spatio-temporal changes in the composition of sensory cilia. Cilia purification methods that were elaborated and perfected over several decades were essential for these advances. In contrast, the proteome of primary cilia is yet to be established, because purification procedures for this organelle have been developed only recently. In this chapter we review current techniques for the purification of olfactory and photoreceptor cilia, and evaluate methods designed for the selective isolation of primary cilia

    NDP Kinase Moves into Developing Primary Cilia

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    Inmunofluorescence staining of murine NIH3T3 fibroblasts grown at high density shows that conventional nucleoside diphosphate (NDP) kinases A and B localize to a sensory organelle, the primary cilium. Similar results are obtained with Xenopus A6 kidney epithelial cells, suggesting that NDP kinases are a universal component of the primary cilium. The translocation of NDP kinase into primary cilia depends on size, taking place only when cilia reach a critical length of 5-6 Όm. In mature cilia, NDP kinases are distributed along the ciliary shaft in a punctate pattern that is distinct from the continuous staining observed with acetylated α-tubulin, a ciliary marker and axonemal component. Isolation of a fraction enriched in primary cilia from A6 cells led to the finding that ciliary NDP kinase is enzymatically active, and is associated with the membrane and the matrix, but not the axoneme. In contrast, acetylated α-tubulin is found in the axoneme and to a lesser extent, in the membrane. Based on the tightly regulated translocation process and the subciliary distribution pattern of NDP kinase, we propose that it plays a role in the elongation and maintenance of primary cilia by its ability to regenerate the GTP utilized by ciliary microtubule turnover and transmembrane signaling

    Rock art recording in Khatm al Melaha (United Arab Emirates): Multirange data scanning and web mapping technologies

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    The application of geometric recording data and representation of open-air rock art is intrinsically so heterogeneous that new online web platforms are required for a more efficient analysis to link all the geo-referenced information and facilitate its scientific study. From 2015 to 2018, three geometric documentation campaigns led by the Departamento de Ingeniería Topogråfica y Cartografía of the Universidad Politécnica de Madrid (Spain) were completed in the area of Khatm al Melaha (Emirate of Sharjah, United Arab Emirates) along the Gulf of Oman. More than 370 rock art engraved motifs were documented in this area close to the southwest border with the Sultanate of Oman. All those figures were picked in 149 stone blocks with different dimensions and morphologies, distributed along the slope of an isolated 58-meter-high elevation. The aim of this project was to establish a protocol for the recording, analysis, preservation and prevention of this set of open-air rock art engravings with the following actions: developing an aerial and terrestrial recording data documentation, creating and developing a web platform called threeDcloud for visualizing three-dimensional models and web mapping, and integrating a data base by means of different JavaScript open-source libraries

    A Nonzero Gap Two-Dimensional Carbon Allotrope from Porous Graphene

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    Graphene is considered one of the most promising materials for future electronic. However, in its pristine form graphene is a gapless material, which imposes limitations to its use in some electronic applications. In order to solve this problem many approaches have been tried, such as, physical and chemical functionalizations. These processes compromise some of the desirable graphene properties. In this work, based on ab initio quantum molecular dynamics, we showed that a two-dimensional carbon allotrope, named biphenylene carbon (BPC) can be obtained from selective dehydrogenation of porous graphene. BPC presents a nonzero bandgap and well-delocalized frontier orbitals. Synthetic routes to BPC are also addressed.Comment: Published on J. Phys. Chem. C, 2012, 116 (23), pp 12810-1281

    Magnetic relaxation in finite two-dimensional nanoparticle ensembles

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    We study the slow phase of thermally activated magnetic relaxation in finite two-dimensional ensembles of dipolar interacting ferromagnetic nanoparticles whose easy axes of magnetization are perpendicular to the distribution plane. We develop a method to numerically simulate the magnetic relaxation for the case that the smallest heights of the potential barriers between the equilibrium directions of the nanoparticle magnetic moments are much larger than the thermal energy. Within this framework, we analyze in detail the role that the correlations of the nanoparticle magnetic moments and the finite size of the nanoparticle ensemble play in magnetic relaxation.Comment: 21 pages, 4 figure

    From Dyadic Ties to Information Infrastructures: Care-Coordination between Patients, Providers, Students and Researchers

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    Objective: To share how an effectual merging of local and online networks in low resource regions can supplement and strengthen the local practice of patient centered care through the use of an online digital infrastructure powered by all stakeholders in healthcare. User Driven Health Care offers the dynamic integration of patient values and evidence based solutions for improved medical communication in medical care. Introduction: This paper conceptualizes patient care-coordination through the lens of engaged stakeholders using digital infrastructures tools to integrate information technology. We distinguish this lens from the prevalent conceptualization of dyadic ties between clinician-patient, patient-nurse, clinician-nurse, and offer the holistic integration of all stakeholder inputs, in the clinic and augmented by online communication in a multi-national setting. Methods: We analyze an instance of the user-driven health care (UDHC), a network of providers, patients, students and researchers working together to help manage patient care. The network currently focuses on patients from LMICs, but the provider network is global in reach. We describe UDHC and its opportunities and challenges in care-coordination to reduce costs, bring equity, and improve care quality and share evidence. Conclusion: UDHC has resulted in coordinated global based local care, affecting multiple facets of medical practice. Shared information resources between providers with disparate knowledge, results in better understanding by patients, unique and challenging cases for students, innovative community based research and discovery learning for all

    How to Teach Health IT Evaluation: Recommendations for Health IT Evaluation Courses

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    Systematic health IT evaluation studies are needed to ensure system quality and safety and to provide the basis for evidence-based health informatics. Well-trained health informatics specialists are required to guarantee that health IT evaluation studies are conducted in accordance with robust standards. Also, policy makers and managers need to appreciate how good evidence is obtained by scientific process and used as an essential justification for policy decisions. In a consensus-based approach with over 80 experts in health IT evaluation, recommendations for the structure, scope and content of health IT evaluation courses on the master or postgraduate level have been developed, supported by a structured analysis of available courses and of available literature. The recommendations comprise 15 mandatory topics and 15 optional topics for a health IT evaluation course

    Five key attributes can increase marine protected areas performance for small-scale fisheries management

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    Marine protected areas (MPAs) have largely proven to be effective tools for conserving marine ecosystem, while socio-economic benefits generated by MPAs to fisheries are still under debate. Many MPAs embed a no-take zone, aiming to preserve natural populations and ecosystems, within a buffer zone where potentially sustainable activities are allowed. Small-scale fisheries (SSF) within buffer zones can be highly beneficial by promoting local socio-economies. However, guidelines to successfully manage SSFs within MPAs, ensuring both conservation and fisheries goals, and reaching a win-win scenario, are largely unavailable. From the peer-reviewed literature, grey-literature and interviews, we assembled a unique database of ecological, social and economic attributes of SSF in 25 Mediterranean MPAs. Using random forest with Boruta algorithm we identified a set of attributes determining successful SSFs management within MPAs. We show that fish stocks are healthier, fishermen incomes are higher and the social acceptance of management practices is fostered if five attributes are present (i.e. high MPA enforcement, presence of a management plan, fishermen engagement in MPA management, fishermen representative in the MPA board, and promotion of sustainable fishing). These findings are pivotal to Mediterranean coastal communities so they can achieve conservation goals while allowing for profitable exploitation of fisheries resources
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