1,720,984 research outputs found
Surface imaging, portal imaging, and skin marker set-up vs. CBCT for radiotherapy of the thorax and pelvis
No full textAim: The aim of this study was to compare surface imaging, portal imaging, and skin marker set-up in radiotherapy of thoracic and pelvic regions, using cone beam computed tomography (CBCT) data as the gold standard. Patients and methods: Twenty patients were included in this study. CBCT, surface acquisition (SA), and two orthogonal portal images (PI) were acquired during the first four treatment sessions. Patient set-up corrections, obtained by registering the planning CT with CBCT, were used as the gold standard. Registration results of the PI and SA were evaluated and compared with those obtained with CBCT. The advantage derived from using SA or PI verification systems over a skin marker set-up was also quantified. Results: A statistically significant difference between PI and SA (in favour of PI) was observed in seven patients undergoing treatment of the pelvic region and in two patients undergoing treatment of the thoracic region. The use of SA or PI, compared with a skin marker set-up, improved patient positioning in 50% and 57 % of the thoracic fractions, respectively. For pelvic fractions, the use of PI was beneficial in 73 % of the cases, while the use of SA was beneficial in only 45 %. Patient positioning worsened with SA, particularly along longitudinal and vertical directions. Conclusion: PI yielded more accurate registration results than SA for both pelvic and thoracic fractions. Compared with the skin marker set-up, PI performances were superior to SA for pelvic fractions while comparable results were obtained for thoracic fractions
Sensitivity to ultraviolet B is a risk factor for cutaneous melanomain a Mediterranean population: results from an Italian case–control study
No full textBACKGROUND: Sun sensitivity is one of the predictors of melanoma risk, together with other individual characteristics such as skin and eye colour and number of naevi. However, it is unclear how best to measure sun sensitivity in order to quantify the individual risk of melanoma.
OBJECTIVES: In this case-control study, the relationship between minimal erythema dose (MED) and skin colour (both instrumentally assessed) was investigated, and their possible role as independent risk factors for melanoma in a Mediterranean population evaluated.
METHODS: In total, 143 patients with cutaneous melanoma and 102 controls were enrolled in the study. Skin colour was assessed using a Minolta CR-200 chromameter. For MED calculation, a fluorescent lamp (Philips TL 4W/12) was used as a source of ultraviolet B light. MED was defined as the lowest dose that produced an increase of 2.5 in the redness value, expressed by the parameter a* of the Commission Internationale d'Eclairage (CIE) L*a*b* colour space (Deltaa* = 2.5).
RESULTS: A significant excess of risk was associated with increasing L* values of skin colour (P 97.7 mJ/cm(2)), subjects with MED values 2-fold increased risk of melanoma (OR = 2.37, 95% CI 1.05-5.38). The effect of decreasing MED value as a melanoma risk factor persisted after adjustment for skin colour and atypical naevi in a multivariate model.
CONCLUSIONS: In conclusion, both instrumentally assessed skin colour and MED are significant risk factors for malignant melanoma in a Mediterranean population. MED seems be an independent variable in establishing the subject's risk profile
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
Integrated Approach for a Successful Geothermal Wells Location in the Mt. Amiata Area (Southern Tuscany)
No full textSorgenia Geothermal has been recently awarded some exploration licenses in Southern Tuscany, near the geothermal fields of Bagnore and Piancastagnaio, around the Mt. Amiata volcano complex.
In order to successfully locate the first deep wells, an integrated exploration program has been developed, firstly based on a complete collection and analysis of existing critical data, which include mining data, previously drilled geothermal wells data and some geophysical data (gradient wells data, gravimetric data, geoelectrical data, CROP 18B and SIF 12–15/87 seismic reflection raw data).
The available seismic data have been reprocessed in order to better focus on the geothermal target and at the same time a new planned 2D seismic reflection survey (approx. 50 km) will be carried out in 2014 to achieve the best coverage in the areas under exploration.
An MT survey has been carefully designed and performed (250 stations) considering the severe increase of EM noise in the areas.
Geological and hydrogeological surveys, as well as the soil CO2 degassing measurements, a useful tool in confirming the existence of a deep-seated active geothermal system, have been also carried out.
The whole dataset has been uploaded and analyzed in a dedicated geodatabase and 2D gravimetric modeling has been performed. Subsequently, the 3D structural model of the area, mainly based on the 3D resistivity and gravity models properly calibrated with wells data, has been shaped and utilized as the basis of the 3D thermofluid-dynamic model of the existing reservoir. Hydrothermal circulation has been modelled using the THOUGH2 code (simulation of multi-dimensional, multiphase and multi component flow and heat transport in porous and fractured media), a useful tool for the assessment of the geothermal potential and for the prediction of the evolution of the system.
This integrated approach contributes to substantially reduce the mining risk in deep geothermal exploration, leading to the building of a better-defined conceptual model of the geothermal reservoir towards a more precise resource detection and assessment for the most appropriate and sustainable exploitation of the field
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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