1,721,055 research outputs found
Conservation of Anthracotherium magnum fossils from Chiuppano, Italy
No full textLignite deposits are characterized by a high probability of fossil preservation along with a high concentration of pyrite minerals. When fossils are discovered, exposure to the humidity and oxygen in the air begins
a destabilization of the minerals and activation of chemical oxidation. In the last century, it was common
practice to protect fossils by covering them with unspecified commercial varnish, but today it is clear this
method is useless for long-term preservation. Moreover, varnish obliterates the precise features of teeth
and bones, usually preventing researchers from correctly analysing and describing these specimens. In this
paper, we describe the methodology applied for conserving fossils identified as Anthracotherium magnum,
discovered in lignite deposits of Chiuppano (Vicenza, Italy) in the mid-twentieth century. We pre-prepared
the specimens, removing varnish from the fossil surfaces, and we exposed them to an aerosol solution
of PEG400 and concentrated ammonia. We discuss the colour shift of bones and the rediscovery of
anatomical characteristics to underline the importance of prompt action in the preservation of fragile
specimens for future exhibition
Conservation of Anthracotherium magnum fossils from Chiuppano, Italy
Full text linkLignite deposits are characterized by a high probability of fossil preservation along with a high concentration of pyrite minerals. When fossils are discovered, exposure to the humidity and oxygen in the air begins a destabilization of the minerals and activation of chemical oxidation. In the last century, it was common practice to protect fossils by covering them with unspecified commercial varnish, but today it is clear this method is useless for long-term preservation. Moreover, varnish obliterates the precise features of teeth and bones, usually preventing researchers from correctly analysing and describing these specimens. In this paper, we describe the methodology applied for conserving fossils identified as Anthracotherium magnum, discovered in lignite deposits of Chiuppano (Vicenza, Italy) in the mid-twentieth century. We pre-prepared the specimens, removing varnish from the fossil surfaces, and we exposed them to an aerosol solution of PEG400 and concentrated ammonia. We discuss the colour shift of bones and the rediscovery of anatomical characteristics to underline the importance of prompt action in the preservation of fragile specimens for future exhibition
ROSSIGNOLI C., PUJATTI E., VICENZUTTO D., REGGIANI P. 2015, L’insediamento tardo-neolitico di Concordia Sagittaria (Venezia), località Loncon, in LEONARDI G., TINÈ V. (a cura di), Preistoria e Protostoria del Veneto, Atti della XLVIII Riunione Scientifica dell'Istituto Italiano di Preistoria e Protostoria, Firenze, pp. 639-646.
No full text
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
From Complexity to Simplicity
No full textNear is beautiful’ was argued by Miller (2004, p. 248) in his essay on “Tobler’s First Law and Spatial Analysis”. The awareness has also grown that relations among things that are near can generate complex spatio-temporal phenomena. The simplicity of Tobler’s law invokes reflections on the complexity of interacting phenomena and the ‘simple’ laws which have been articulated in the scientific literature when attempting to ‘decode’ these phenomena. Certainly, from a spatial economic viewpoint, Tobler’s law is consistent with the minimum cost-distance principle. In addition, Miller sheds light on the meaning of ‘near’ and ‘distant’: near is central to the space-economy, it is a more flexible and powerful concept than is often appreciated, and it could be expanded to include both space and time. Thus, not only (near or distant) space, but also the time component is fundamental in the analysis of the interacting economic phenomena. In parallel with Tobler, Hägerstrand (1967) pointed to the relevance of joint space-time diffusion processes, and Wilson (1967) linked spatial interaction with statistical information principles and entropy laws. An associated microeconomic foundation of spatial interaction modelling was subsequently developed by Anas (1983) on the basis of random utility theory (McFadden, 1974). Later on, Nijkamp and Reggiani (1992) linked dynamic entropy with (dynamic) spatial interaction models.
The clear methodological interrelationships between the above-mentioned theories and models call for further reflections on the complexity of space-time phenomena and the simplicity of the laws describing these phenomena. The primary idea of complexity concerns the mapping of a system’s non-intuitive behaviour, particularly the evolutionary patterns of connections among interacting components of a system whose long-run behaviour is hard to predict. But, particularly at a dynamic level, it is noteworthy that May’s law (May, 1976) – describing the evolution of a population in discrete terms by means of a simple logistic equation – shows irregular and chaotic (and thus unpredictable) characteristics for certain values of the parameters and initial conditions. Also the ‘complex’ interacting evolution of two species can be described by the ‘simple’ Lotka-Volterra equations, whose analytical form is based on two interrelated logistic equations, and, surprisingly, the dynamic logistic equation turns out to be to be the dynamic form (under a certain condition of the utility function) of the associated logit model, and hence of the related spatial interaction model of the Wilson type (Reggiani, 2004).
The recent enormous interdisciplinary interest in network concepts, analysis, and modelling – arising from the study of complex interconnected dynamic systems – again underlines the ‘simplicity law’. Networks often show common behaviour, based on their topological characteristics, and this behaviour is mainly derived from exponential/power forms, which are strongly related to the equations that govern spatial interaction. In other words, the topological properties of a network can give useful insights into: how the network is structured; which are the most ‘important’ nodes/agents; and how network topology can influence the conventional spatial economic laws (such as equilibrium theory, spatial interaction theory, etc.). However, this topology structure is again expressed by very simple laws, and in most cases these laws can be interpreted in a spatial economic framework.
In this framework, it is still an open research issue which specific and novel contributions network analysis can offer to spatial economic analysis, and – vice versa – whether the solidity of spatial economic laws needs to be reconsidered in the light of recent advances in complexity and network theory. Hence, a dual analysis is necessary, in order to explore potential connections between these two approaches. In this respect, a synthesis of prelimin..
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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