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Full text linkFil: Piazza, Paola Andrea. Universidad de Buenos Aires. Facultad de Ciencias Económicas. Buenos Aires, Argentina
Analysis of Antarctic benthos dynamics and spatial patterns based on non-destructive techniques and image analysis: development of an integrated monitoring toolkit and general protocols
No full textIntroduction- First chapter introduces the Antarctic coastal marine environments, as part of the intriguing and challenging “puzzle” that scientific community is committed to resolve, represented by Antarctica and its changes. A brief glimpse on two of the main drivers influencing benthic communities dwelling in these areas, the sea-ice and the substrate, is given, with a special eye on the unresolved aspects of their influence on marine organisms and on the effect of their variations. Some of the major challenges of scientific researches in such extreme and fragile environment is highlighted together with an overview on ongoing and proposed strategies of the Scientific Committee on Antarctic Research (SCAR). Especially focusing on monitoring perspective, the essential requirement of the establishment of permanent sites and of specially protected areas is discussed. Later on, an overview on the study site and its inhabiting key species is presented. Recent advances in underwater technologies confer the opportunity to overcome previous technical limitations and to improve our capacity of investigation in similar areas. Between emerging techniques, non-destructive image-based ones are introduced in their theoretical aspects. Another pivotal aspect of monitoring is the strategy of sampling, one of the major issues on which relies the reliability of a monitoring project. Preliminary considerations on the relevance of choice of the best sampling design are described.
Materials and Methods- Second chapter describes the methodologies used to collect, elaborate and analyse data obtained from images. Firstly, field operations are described, corresponding to well-established protocol of nondestructive image-based SCUBA-operated sampling on shallow rocky bottoms. A particular attention is provided to the use made of sampled materials during the in-silico procedures. This is a newness element of this project, providing one of the first examples of application of some emerging image-based techniques in Antarctica. The informative potential that archived and new SCUBA-operated videos are able to store up about epifaunal communities composition and structure has been exploited by applying photogrammetric reconstruction and measurements. Due to the dated format of older videos, a procedure of adaptation to new applications was needed. In order to better explain these steps, a brief and simply panoramic on some major features of, as defined, ‘historical’ videos is given. Thanks to the proposed in-silico procedures, it has been possible to describe three-dimensional features of seafloor and dwelling organisms, also from videos not specifically meant for this purpose.
Later in the chapter, it is shown how spatial information about specimens distribution has been obtained thanks to a variety of GIS tools. Finally, it is supplied a summary of the statistical analyses used to the multiple aims of: i) exploring data, ii) describing macrobenthic populations and their spatial distribution, iii) deriving best sampling design for key species, iv) producing comparisons across years (thanks to two temporal repetitions) and sites.
Results- Third chapter reports the main results deriving from the different ‘fields of study’ of the research, including: i) a first section, specifically focusing on the photogrammetric output, with a special eye on the issues related to the use of ‘historical’ materials, as the used video samples were defined; and ii) a second, more ecological, section, reporting the results from counting procedures and spatial statistical analyses. The taxonomical composition of the megabenthic community is described: extendedly, in form of list of taxa that was
possible to distinguish and eventually recognize at the lower taxonomical level as possible; and synthetically, by the estimation of biodiversity indices. The small-scale spatial pattern analysis is, then, reported, highlighting the distribution and neighbour estimates of different taxa. Sampling strategy has different outcomes if applied to organisms with different distributions and, thus, when it is advisable to preventively study these spatial aspects. In our case, statistical analyses on sampling simulation suggest specific combinations of sample size and sampling scheme for the main keyspecies analysed. Finally, the results of the trial linear regression model between the distribution of the sea urchin Sterechinus neumayeri (Meissner, 1900) and of the encrusting algae Corallinales are reported, confirming the need of a major number of covariates in order to understand distributional pattern shaping factors.
Discussion- The final outcomes of the study are reviewed, according to the original aims and with the major issues of the research. The interpretation of some of the results is particularly investigated. The future perspectives are also mentioned, in many of the possible fields of improvement.
Conclusions- Due to the overall value of the proposed methodological approach and of the results of the study, they are presented as contibution to the definition of a standardized protocol of monitoring techniques for the Antarctic benthos, in the perspective of a shared international collaboration
A simple time-lapse apparatus for monitoring macrozoobenthos activity in Antarctica
No full textIn situ time-lapse studies in Polar Regions are uncommon because of the intrinsic limitations of scientific SCUBA diving at sub-zero temperatures and the logistical challenges linked to the deployment of underwater time-lapse systems, which are typically large and heavy. In Antarctica, a number of non-invasive approaches have been adopted to document the behaviour of benthic organisms. For example, in the McMurdo Sound, Ross Sea, Kim et al. (2007) employed time-lapse arrays to study the movement of sea-stars Odontaster validus Koehler in response to organic enrichment, and McClintock et al. (2010) recorded valve clap frequency in scallops Adamussium colbecki (E.A. Smith). At King George Island, Antarctic Peninsula,
Schories (unpublished, https://www.youtube.com/watch? v=rKV8s00SFL8) conducted a time-lapse analysis
(6 hours) of limpet Nacella concinna (Strebel) and sea urchin Sterechinus neumayeri (Meissner) movement. Here we present a simple and portable time-lapse apparatus, which was tested in TerraNova Bay, Ross Sea, at a depth of 20m below the pack ice
Un’Isola nel contesto mediterraneo: politica, cultura e arte nella Sicilia e nell’Italia meridionale in Età medievale e moderna
No full textAtti del convengo internazionale: Un’Isola nel contesto mediterraneo: politica, cultura e arte nella Sicilia e nell’Italia meridionale in Età medievale e moderna. Convegno di chiusura del Progetto FIR 2014 “Regine, re e viceré: immagini e strategie del potere in Sicilia fra tardo medioevo e prima età moderna. Le fonti materiali per una storia dinamica del territorio / Queens, kings and viceroys: images and strategies of power in Sicily between late Middle Ages and Early Modern Age. Material sources for a dynamic history of the territory”. Catania, Dipartimento di Scienze della Formazione, 21 marzo
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
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