1,720,960 research outputs found
Measurement Of Indoor 222rn Using Cr-39 Under A Thin Film Geometry
No full textIn this work an assembly for indoor 222Rn measurement is presented. This assembly is made up of two acrylic plates (14 cm×14 cm) separated by a distance of 4 mm. To prevent radon daughters from outside entering the assembly (and produce alpha particle tracks striking the CR-39 detector placed in the central region of one of these plates), the borders of these plates were progressively closed, leaving open only a rectangular aperture of 5 mm×4 mm. The size of this opening was determined experimentally, by exposing in two indoor environments assemblies with different apertures as follows: (i) all borders open; (ii) two borders closed; (iii) three borders closed; (iv) four borders closed but one containing a 6 cm×4 mm opening; (v) four borders closed but one containing a 2.5 cm×4 mm opening and (vi) four borders closed but one containing a 0.5 cm×4 mm opening. Track density shows a noticeable decrease between assembly (i) and assembly (iii), remaining constant for smaller openings. Only 222Rn, a noble gas, should enter the assembly independently of the opening size. © 2001 Elsevier Science Ltd. All rights reserved.341-6145148Bigazzi, G., Hadler, N.J.C., Paulo, S.R., On indoor radon contamination monitoring with plastic nuclear track detectors: The influence of plate-out effect (1988) Nucl. Tracks Radiat. Meas., 15 (1-4), pp. 539-542Bigazzi, G., Hadler, N.J.C., Paulo, S.R., On indoor radon contamination monitoring with SSNTDs: Experimental results concerning plate-out and self-plate-out effects (1989) Nucl. Instr. and Meth. A, 280, pp. 506-509Guedes, S.O., Hadler, N.J.C., Iunes, P.J., Navia, L.M.S., Neman, R.S., Paulo, S.R., Rodrigues, V.C., Zúñiga, A.G., Indoor radon daughters survey at Campinas-Brazil using CR-39: First results (1999) Radiat. Meas., 31, pp. 287-290Hadler, N.J.C., Paulo, S.R., Indoor radon daughters contamination monitoring: The absolute efficiency of CR-39. Taking into account the plate-out effect and environmental conditions (1994) Radiat. Prot. Dosim., 51, pp. 283-296Nikolaev, V.A., Ilic, R., Etched track radiometers in radon measurements: A review (1999) Radiat. Meas., 30, pp. 1-13Paulo, S.R., (1991) Dosimetria ambiental de rn-222 e filhos: Medida da eficiência absoluta do CR-39 levando-se em conta os efeitos do plate-out e fatores ambientais, , Ph.D. Thesis, IFGW, UNICAMP, Brazi
Fission-track Dating Of Macusanite Glasses With Plateau And Size Correction Methods
No full textTwo Macusanite pebbles (MB1 and MB2) were dated with the fission-track method. Six irradiations were carried out in different nuclear reactors: Pavia (Italy), IPEN-CNEN (Brazil) and IPEN-Lima (Peru). Measurements of the thorium and uranium induced-fission per target nucleus using natural thorium thin films and natural U-doped glasses calibrated against natural uranium thin films, together with a λF of 8.46 × 10-17 a -1 were used to determine the ages. The apparent ages were corrected using the plateau and size correction methods. Track measurements were performed by different analysts, using different counting criteria. In addition, tracks were measured on samples which had been submitted to thermal treatment as well as on samples which had not been heated. Thermal treatments were carried out to erase the fossil tracks before neutron irradiation. No significant differences have been found in individual results, using the two Macusanite pebbles and the different nuclear reactors, age correction techniques, analysts, track-counting criteria, and thermal treatments before neutron irradiation. The great majority of the results (14/17) is compatible with the Ar-Ar ages of 5.12 ± 0.11 and 5.10 ± 0.11 Ma, Macusanite MB1 and MB2, respectively. However, the fission-track ages are systematically less (∼8%) than the Ar-Ar ages of the two Macusanite samples studied. © 2003 Published by Elsevier Ltd.361-6 SPEC.407412Balestrieri, M.A., Bigazzi, G., Bouska, V., Labrin, E., Hadler, N.J.C., Kitada, N., Osorio, A.A.M., Zúñiga, G.A., Potential glass age standards for fission-track dating: An overview (1998) Advances in Fission-Track Geochronology, pp. 287-304. , Van den Haute, P., De Corte, F. (Eds), Kluwer Academic Publishers, DordrechtBarnes, V.E., Edwuards, G., McLaughlin, W.A., Friedman, I., Joenjuu, O., Macusanite occurrence, age and composition (1970) Macusani. Peru. Geol. Soc. Am. Bull., 81, pp. 1539-1546Guedes, S., Hadler, N.J.C., Iunes, P.J., Paulo, S.R., Zuniga, G.A., The spontaneous fission decay constant of 238U using SSNTD (2000) J. Radioanal. Nucl. Chem., 245, pp. 441-442Guedes, S., Hadler, N.J.C., Iunes, P.J., Zuñiga, G.A., Tello, S.C.A., Paulo, S.R., The use of the U(n,f) reaction dosimetry in the determination of the λf value through fission-track techniques (2003) Nucl. Instrum. Methods A, 496, pp. 215-221Holden, N.E., Hoffman, D.C., Spontaneous fission half-lives for ground-state nuclides (2000) Pure Appl. Chem., 72 (8), pp. 1525-1562Iunes, P.J., Hadler, N.J.C., Bigazzi, G., Tello, S.C.A., Guedes, S., Paulo, S.R., Durango apatite fission-track dating using length-based age corrections and neutron fluence measurements by natural thorium thin films and natural U-doped glasses calibrated through natural uranium thin films (2002) Chem. Geol., 187, pp. 201-211Iunes, P.J., Bigazzi, G., Hadler, N.J.C., Tello, S.C.A., Guedes, S., Paulo, S.R., Balestrieri, M.L., Zuñiga, G.A., The Th/U ratio in minerals by a fission track technique: Application to some reference samples in order to estimate the influence of Th in fission-track dating (2002) Radiat. Meas., 35, pp. 195-201Iunes, P.J., Hadler, N.J.C., Guedes, S., Tello, S.C.A., Bigazzi, G., Osório, A.A.M., On the plateau and size correction methods in fission-track dating (2003) Radiat. Meas., , to be submittedMiller, D.S., Wagner, G.A., Fission-track ages applied to obsidian artefacts from South America using the plateau-annealing and the track size age-correction techniques (1981) Nucl. Tracks, 5, pp. 147-156Miller, D.S., Eby, N., McCorkell, R., Rosenberg, P.E., Suzuki, M., Results of interlaboratory comparison of fission track ages for 1988 fission track Workshop (1990) Nucl. Tracks Radiat. Meas., 17, pp. 237-245Naeser, C.W., Izett, G.A., Obradovitch, J.D., Fission-track and K-Ar ages of natural glasses (1980) Geol. Surv. Bull., 1489, pp. 1-31Pichavant, M., Herrera, J.V., Boulmier, S., Briqueu, L., Joron, J.L., Juteau, M., Marin, A., Vernet, M., The Macusani Glasses SE Peru: Evidence of chemical fractionation in peraluminous magmas (1987) Geochim. Soc. Special Publication, 1, pp. 359-373Poupeau, G., Sabil, N., Villa, I.M., Bigazzi, G., Vatin-Perigon, N., Flores, P., Pereyra, P., Arroyo, G., Fission-track and K-Ar ages of macusanite obsidian glasses (SE Peru): Geodynamic implications (1992) Tectonophysics, 205, pp. 295-305Poupeau, G., Labrin, E., Sabil, N., Bigazzi, G., Arroyo, P.G., Vatin-Perigon, N., Fission track dating of 15 Macusanite glass pebbles from the Macusani volcanic field (SE Peru) (1993) Nucl. Tracks Radiat. Meas., 21, pp. 499-506Storzer, D., Poupeau, G., Ages-plateaux de minéraux et verres par la méthode des traçes de fission (1973) Comp. Rend. Acad. Sci. Paris D, 276, pp. 137-139Storzer, D., Wagner, G.A., Correction of thermally lowered fission track ages of tektites (1969) Earth Planet. Sci. Lett., 5, pp. 463-468Van den Haute, P., Jonckheere, R., De Corte, F., Thermal neutron dosimetry for fission-track dating with metal activation monitors: A reinvestigation (1998) Chem. Geol., 731, pp. 233-24
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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