1,721,058 research outputs found
Soil CO2 Flux Measurements in Volcanic and Seismic Areas: Laboratory Experiments and Field Applications
No full textThe measurement of the CO2 flux exhaled from the soils is a delicate operation because of unavoidable errors caused by the measuring apparatus that disturbs both the soil and the gases circulation. Several methods have been developed in order to perform accurate
measurements of soil CO2 flux. The methods used most widely to measure the emission of CO2 from the soil to the atmosphere in volcanic and geothermal areas are the dynamic method Gurrieri and Valenza 1988) and the accumulation chamber method (Baubron et al., 1990;Tonani and Miele., 1991). The flux measurements performed using the dynamic method can be influenced by soil permeability and by the rate of the sampling pump. The accumulation chamber measurements can also be affected by several problems such as wind speed, pumping flux, valuation of tangent at t 0 of the CO2 plot, etc. A laboratory apparatus able to simulate different flux regimens, under known conditions, has been developed and was used to test the performance and reliability of these two methods. The investigated fluxes fell
within the range of values close to soil respiration up to those normally measured in active volcanic and geothermal areas. The correct functioning of the laboratory apparatus was checked by comparing the experimental steady state concentration profiles with those
predicted by the advective-diffusion model. As can be inferred from the data obtained, the
flux measurements performed using the dynamic method are significantly influenced by soil
permeability especially if the measurements are taken at high pumping flux. An empirical
equation for performing careful soil CO2 flux measurements as a function of the soil
permeability was obtained by fitting experimental data to a model that explained the functioning of the system. In order to measure in situ soil permeability, a new method based on the theory of radial gas advection through an isotropic porous medium was developed. The method was tested in the laboratory and at several locations on the island of Vulcano (Aeolian Islands, Italy).
Tests performed on the accumulation chamber method have highlighted several sources of
errors in measuring CO2 flux with this method. The magnitude and sign of the obtained errors
depend on the imposed flux, on soil permeability and on the rate used to induce air circulation
in the close loop of the system.
Permeability measurements were performed with the radial gas advection method over a large sector of the island of Vulcano (Aeolian Islands, Italy) and the results compared with soil CO2 fluxes measured at the same sites using the dynamic method. Based on the results, the influence of soil permeability on the flux measurements and on their spatial distribution was assessed. Finally, the dynamic method was also applied to a seismic area of Sicily (Capo Calava) in order to study the relationships between soil degassing and tectonics.Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse ed ai Rischi Naturali (CFTA; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo;
Unione Europea Fondo Sociale EuropeoPublishedope
talia e Spagna: modelli di Stato a confronto
No full textComparazione tra le tendenze relative alla forma di Stato e di governo in Italia e Spagn
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
General interpolation scheme for thermal fluctuations in superconductors
Full text linkWe present a general interpolation theory for the phenomenological effects of thermal fluctuations in superconductors. Fluctuations are described by a simple gauge invariant extension of the gaussian effective potential for the Ginzburg-Landau static model. The approach is shown to be a genuine variational method, and to be stationary for infinitesimal gauge variations around the Landau gauge. Correlation and penetration lengths are shown to depart from the mean field behaviour in a more or less wide range of temperature below the critical regime, depending on the class of material considered. The method is quite general and yields a very good interpolation of the experimental data for very different materials
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