1,721,151 research outputs found
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
Design and implementation of a biological warfare agents simulant spectral database for the automatic discrimination in unconventional scenarios
No full textThe biological agents (BAs) can exist in the form of aerosolized bacteria, fungi or viruses, and they also may be spread by vectors and other routes like water and air supply (Cenciarelli et al., 2013; Kumar et al., 2013). Among the ways which allow the propagation of BAs, certainly air has a more rapid rate of diffusion; for this reason it is important to develop systems for remote sensing of airborne biological agents. Jonsson et al. (2005) successfully present a detection system for BAs based on spectral detection of ultraviolet (UV) laser induced fluorescence (LIF); spectral characterization was also illustrated for some simulants. The most common fluorophores found in bioaerosols are phenylalanine, tyrosine, tryptophan, nicotinamide adenine dinucleotide compounds (NADH), flavins and chlorophylls. Among these main fluorophores in bioaerosols, phenylalanine has little absorption above 270 nm, while chlorophylls adsorb around 430 nm. Excitation around 260-290 nm will mainly generate fluorescence emission from tyrosine, tryptophan, NADH, and flavin, while excitation around 350-410 nm will mainly produce fluorescence emission from NADH and flavin.
Although in the literature several studies regarding the ability to discriminate BAs through methods that exploit fluorescence excitation through ultraviolet radiation were presented, it appears to be essential to build and implement a database being able to return a response about the kind of BA detected according to a revealed fluorescence spectrum. Furthermore, in order to refine the experimental procedures, it appears essential to standardize the samples preparation methods. This represents the starting point for the creation of a pitched instrument.
This PhD research activity aims to design a biological warfare agents (BWA) spectral database using biological agents simulants (BWA-S) for the automatic discrimination in unconventional scenarios, i.e. by standardizing the experimental procedures (e.g. best samples preparation) and setting the better criteria for the algorithm analysis. The
PhD in Industrial Engineering - Final Dissertation - Orlando Cenciarelli
DESIGN AND IMPLEMENTATION OF A BIOLOGICAL WARFARE AGENTS SIMULANT SPECTRAL
DATABASE FOR THE AUTOMATIC DISCRIMINATION IN UNCONVENTIONAL SCENARIOS
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automatic classification system is based on a novel adaptative algorithm, named as Universal Multi-Event Locator (UMEL). UMEL is a universal technique based on Support Vector Regression (SVR), a version of Support Vector Machines (SVM) for function estimation (Carestia et al., 2014). SVR fits the training data discarding factors such as sampling rate or noise distribution. This technique computes a fitting function and, in addition, retrieves a list of points from the training set. These points become Support Vectors (SVs). For the first time, UMEL is used in this work to discriminate between fluorescence spectral signature of BWA-S
Application of optical techniques to detect chemical and biological agents
No full textChemical or biological contamination, due to natural or man-made disasters, represents a
severe concern for safety and security of people, and of the environment. Chemical agents
(CAs) and biological agents (BAs) are commonly used for a number of civilian and military
applications, and can be deployed as a weapon with terroristic purposes. Therefore, it is
necessary to develop specific systems aimed at preventing or reducing the consequences of the
spread of these agents. To this end, the authors have developed optical systems to detect
(LIDAR) and identify (DIAL) CAs, and to detect BAs (fluorescence technique). These systems
and technologies will be presented in this work together with the analysis and discussion of the
results obtained
Spectral analysis of biological agents to implement a tool for fast biological detection
No full textBiosecurity and biosafety are key concerns of modern society. A plethora of biological agents (BAs) like toxins, bacteria, viruses, fungi and parasites, are able to cause damage to humans, animals and plants, and some of them can even be used as non-conventional weapons. Indeed, the use of BAs for military or terroristic purposes has been recorded from the ancient Roman Empire until present days and, today, it is considered one of the four main threat of the CBRN (Chemical, Biological, Radiological, Nuclear) group. One of the most remarkable characteristics of BAs is that they are able to spread unnoticed among the population for days or weeks before the first symptoms of the disease the cause become evident. Moreover, BAs are almost colorless and odorless and their sizes (that ranges from few nanometers for protein toxins to tens of micrometers for bacteria) makes them hardly noticeable to the human eye.
Finally, different BAs may cause similar symptoms but require different treatments, so it is paramount to gain the capability to detect and characterize BAs at the early stage of their diffusion.
Although the ultimate goal would be the development of a quick, field portable, user friendly tool for the unambiguous identification of BAs, together with the possibility to perform stand-off detection to reduce risks for operators and population, to date, no single technique has proved to achieve these results leading to a constant search for a compromise between rapidity, specificity, and stand-off capabilities. In this framework, UV-Light Induced Fluorescence (UV-LIF) is considered one of the most promising techniques to perform detection from medium to long distances (to date, from hundreds of meters to few kilometers), although photoluminescence from BAs is very weak and day time measurements may represent a real challenge; moreover, background aerosol UV signals poses further issues that are still to be soundly addressed.
The PhD research activity consisted of a preliminary analysis (of the characteristics) of a system for the quick classification of BAs released in the atmosphere through the use of
PhD in Industrial Engineering - Final Dissertation – Mariachiara Carestia
SPECTRAL ANALYSIS OF BIOLOGICAL AGENTS TO IMPLEMENT A TOOL FOR FAST
BIOLOGICAL DETECTION
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UV-LIF techniques, to perform detection to warn and treat. In particular, this thesis reports on new insights on the standardization of the methodology to build and test a training database of BAs signatures, the multispectral analysis of BAs optical signatures, the constitution of a multispectral database, and the statistical and mathematical tools for the automatic classification of the spectral signatures. Moreover, quantum efficiency tests have been performed on biological samples to acquire information useful for the definition of the structural features of a tool for BAs detection.
Measurements of different classes of BAs (toxins, vegetative bacteria and bacterial spores), some of them simulants of Biological Warfare Agents (BWAs), have been performed by conveniently selecting six excitation wavelengths in the UV spectral range (namely, 266, 273, 280, 300, 340 and 355 nm). The spectral signatures have been analyzed and different solutions for their automatic classification have been proposed and compared. In particular, Support Vector Regression based methods have been applied and an algorithm has been proposed with the aim of analyzing a restricted database of BAs.
This work provides valuable information both for setting the basis for the set-up of a laboratory demonstrator that will be the first step toward the implementation of a tool for quick biological detection able to be installed on an Unmanned Air Vehicle (UAV), and for selecting the criteria for the implementation and analysis of a BAs spectral signatures’ database
Electrochemical characterization of electrode materials for hydrogen-energy applications
No full textDispelling 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
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