1,720,988 research outputs found
Monthly velocity and seasonal variations of the Mont Blanc glaciers derived from Sentinel-2 between 2016 and 2024
No full textWe investigated the temporal variability of the surface velocity of 30 glaciers in the Mont Blanc massif (European Alps). We calculated the monthly velocity between 2016 and 2024 using digital image correlation of Sentinel-2 optical imagery. The main objectives of the study were (i) to characterize the variability of the velocity fields of such glaciers (referring to both their temporal seasonal and inter-annual and spatial variations) and (ii) to investigate relationships between the morphology of glaciers and their kinematics. We measured monthly velocities varying from 12.7 to 487.4 m yr(-1). We observed an overall decrease in the velocity between 2016 and 2019 and an unexpected rise in 2020-2022, which are especially visible in most glaciers on the southern side of the massif. Considering the whole period, half of the glaciers showed positive acceleration, which reached values > 4 m yr(-2) in three glaciers. In general, the trend's absolute value in the cold season is higher in the case of positive acceleration and lower in the case of negative acceleration. We found that smaller glaciers have a more pronounced seasonality, with winter-summer velocity differences of 50 %-100 %. Finally, in 2016, 2018, and 2022, we observed an exceptionally high winter-summer velocity difference in the 0.3 km2 wide Charpoua Glacier, when summer velocities increased by 1 order of magnitude
A new gemstone from Italy: "Violan quartz."
No full textWe report the results of three mark-release-recapture experiments carried out in an urban area in Rome, Italy, to study the active dispersal of Aedes albopictus (Diptera: Culicidae). The 4.3% recapture rate obtained supports the use of sticky traps in MRR experiments to study the dispersal of Ae. albopictus females. Most fluorescent dust-marked females were recaptured at the gravid stage at 50-200 m from the release sites during the first 9 days after release. The average of daily-MDTs (Mean Distance Traveled) was 119 m and the maximum observed distance travelled ranged from 199 m to 290 m in the three replicates. These data provide the first information about the dispersal of Ae. albopictus in a temperate European area and appear to be consistent with the few data available on this subject from other urban areas, where dispersal was constrained by physical barriers. Although caution should be taken in generalizing these results, they should be considered when planning control activities in urban areas in Italy, as well as in other European countries. This is particularly relevant if control is intended to interrupt pathogen transmission in cases of possible arbovirus epidemics, such as the Chikungunya outbreak that occurred in Ravenna, Italy in 2007.
© 2010 The Authors. Medical and Veterinary Entomology © 2010 The Royal Entomological So
Esperimenti di “maturazione” di geomateriali argillosi con acqua solfurea e salso-bromo-iodica per la preparazione di fanghi “peloidi” termali e per trattamenti dermatologici.
No full textLandslide on glaciers: an example from Western Alps (Cogne - Italy)
No full textIn the warm summer of 2017, a landslide failed from the south-east side of the Col des Clochettes on the top of the underlying Trajo Glacier. The study area is at an elevation of about 3500 m a.s.l. in the Gran Paradiso Massif and can be hardly reached by walking from Cogne (Aosta Valley, NW Italy). Studies conducted by field surveys, photogrammetry (structure from motion) and satellite images analysis, integrated with the evaluation of data from meteorological stations have been used to reconstruct the phenomenon and infer its causes. The site is very complex to be studied especially due to logistic problems, therefore, measurements and observations that are common practice in other landslides are very difficult to apply here. So, many of the results achieved are not adequately supported by field studies. Anyway, the following factors could have affected the stability of the slope: i) the tectonic structure of the area, which is reflected on the morphology and on the geomechanics characteristics of the rock masses; ii) the meteorological conditions during 3 months before the main failure, resulting in an extremely high temperature compared to historical data. Moreover, the analysis of multitemporal satellite images allowed to recognize that it was not a single landslide but that the phenomenon is articulated over time in at least five failures in about 2 months. Moreover, several predisposing factors may have been playing an important role in causing the instability: the degradation of permafrost (probably affecting rock mass due to the circulation of warm air and water in the discontinuity systems), the alternance of the freeze-thaw cycles and the availability of a considerable amount of water from rainfalls and nival fusion infiltrating deeply in the rock mass. More common causes such as rains and earthquakes have been excluded
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
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