1,721,031 research outputs found
Enhancing UAS safety through building-induced dangerous zones prediction: concept and simulations
Full text linkThis study presents a comprehensive approach to operational estimation of the zones of danger for the Unmanned Aerial Systems (UASs) generated at low altitudes in presence of buildings, aimed at ensuring their safer operation. The main tasks are three. The first one is the definition of an inboard measurement methodology appropriate and feasible for UAS that allows Eddy Dissipation Rate (EDR) estimation. An inboard setup with a lightweight and low-cost anemometer operating at a 1 Hz sampling rate, immediately usable on UAS, is proposed. The second one is the definition of empirical equations to estimate the size of dangerous areas for the UAS flights around buildings through numerical simulation. The third one is the validation of the empirical formulas in a real-world case, through the numerical simulation of a group of buildings belonging to a research centre. Results show a good resemblance in the size of the danger zones, highlighting that this multi-faceted approach contributes to enhanced safety protocols for UASs operating in urban environments
The role of nonlinearity in computing graph-theoretical properties of resting-state functional magnetic resonance imaging brain networks
No full textIn recent years, there has been an increasing interest in the study of large-scale brain activity interaction structure from the perspective of complex networks, based on functional magnetic resonance imaging (fMRI) measurements. To assess the strength of interaction (functional connectivity, FC) between two brain regions, the linear (Pearson) correlation coefficient of the respective time series is most commonly used. Since a potential use of nonlinear FC measures has recently been discussed in this and other fields, the question arises whether particular nonlinear FC measures would be more informative for the graph analysis than linear ones. We present a comparison of network analysis results obtained from the brain connectivity graphs capturing either full (both linear and nonlinear) or only linear connectivity using 24 sessions of human resting-state fMRI. For each session, a matrix of full connectivity between 90 anatomical parcel time series is computed using mutual information. For comparison, connectivity matrices obtained for multivariate linear Gaussian surrogate data that preserve the correlations, but remove any nonlinearity are generated. Binarizing these matrices using multiple thresholds, we generate graphs corresponding to linear and full nonlinear interaction structures. The effect of neglecting nonlinearity is then assessed by comparing the values of a range of graph-theoretical measures evaluated for both types of graphs. Statistical comparisons suggest a potential effect of nonlinearity on the local measures-clustering coefficient and betweenness centrality. Nevertheless, subsequent quantitative comparison shows that the nonlinearity effect is practically negligible when compared to the intersubject variability of the graph measures. Further, on the group-average graph level, the nonlinearity effect is unnoticeable. (C) 2011 American Institute of Physics. [doi:10.1063/1.3553181
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Lattice vibrations of ferroelectric relaxors and nanoparticles investigated by hyper-Raman scattering
No full textInternational audienceThe lattice dynamics of ferroelectric relaxors and nanoparicles is still the subject of many theoretical and experimental investigations. In addition to the usual structural techniques, spectroscopic methods sensitive to vibrational modes are widely used to elucidate phase transition mechanisms. Numerous studies have been already performed using inelastic neutron scattering (INS), Raman scattering (RS) and infrared reflectivity (IR). Using all these techniques, it is very difficult to disclose neatly the behavior at very low frequencies in these materials. Hyper-Raman scattering is a non-linear optic spectroscopy where two incident photons scatter one photon after interaction with an excitation in the media. One major interest of this technique is its selection rules that are different from both IR and RS. For example, in the Pm3 ̅m simple cubic perovskite, the polar F1u modes are active both in IR and HRS, while the "silent" F2u mode is active only in HRS. This provides HRS as an experimental tool that can probe polar and non-polar excitations and that gives details about the spectral shape down to frequencies of a few cm−1. In this talk, recent HRS experimental studies reporting the lattice vibrations of prototypical ferroectric relaxors such as PMN and PMT [1-3] and of the well-known quantum paraelectric material strontium titanate (micro- and nano-particles) [4] will be discussed. Special attention will be given to the dynamics of the low-lying vibrations such as the ferroelectric soft modes. These results show that HRS can be a very useful tool for the investigation of the vibrations of ferroelectric materials. [1] A. Al-Zein, B. Hehlen, J. Rouquette, and J. Hlinka, Phys. Rev. B 78, 134113 (2008). [2] A. Al-Zein, J. Hlinka, J. Rouquette, and B. Hehlen, Phys. Rev. Lett. 105, 017601 (2010). [3] A. Al-Zein, J. Hlinka, J. Rouquette, A. Kania, and B. Hehlen, J. Appl. Phys. 109, 124114 (2011). [4] J. M. Kiat, C. Bogicevic, P. Geimener, F. Karolak, N. Guiblin, F. Porcher, A. Al-Zein, B. Hehlen, and R. Haumont, submitted to Phys. Rev. B
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