1,720,996 research outputs found
Efficiency of frost-cracking processes through space and time: An example from the eastern Italian Alps
No full textIt is widely accepted that climate has a strong impact and exerts important feedbacks on erosional processes and sediment transport mechanisms. However, the extent at which climate influences erosion is still a matter of debate. In this paper we test whether frost-cracking processes and related temperature variations can influence the sediment production and surface erosion in a small catchment situated in the eastern Italian Alps. To this extent, we first present a geomorphic map of the region that we complement with published 10Be-based denudation rates. We then apply a preexisting heat-flow model in order to analyze the variations of the frost-cracking intensity (FCI) in the study area, which could have controlled the sediment production in the basin. Finally, we compare the model results with the pattern of denudation rates and Quaternary deposits in the geomorphic map. The model results, combined with field observations, mapping, and quantitative geomorphic analyses, reveal that frost-cracking processes have had a primary role in the production of sediment where the intensity of sediment supply has been dictated and limited by the combined effect of temperature variations and conditions of bedrock preservation. These results highlight the importance of a yet poorly understood process for the production of sediment in mountain areas
Il divertimento geometrico
No full textIl lavoro descrive dettagliatamente un laboratorio del
Progetto Lauree Scientifiche in tutte le sue fasi: dalla
scelta del tema, lo sviluppo ed articolazione di questo
in una serie di incontri, la progettazione dettagliata
di ciascun incontro, fino all' attuazione con gli studenti.
Il tema prescelto e` dato da alcuni concetti fondamentali
di geometria differenziale: spazi tangenti e curvatura
per curve e superfici (curvatura gaussiana in questo caso),
con qualche applicazione
Pronounced increase in slope instability linked to global warming: A case study from the eastern European Alps
Full text linkIn recent decades, slope instability in high-mountain regions has often been linked to increase in temperature and the associated permafrost degradation and/or the increase in frequency/intensity of rainstorm events. In this context we analyzed the spatiotemporal evolution and potential controlling mechanisms of small- to medium-sized mass movements in a high-elevation catchment of the Italian Alps (Sulden/Solda basin). We found that slope-failure events (mostly in the form of rockfalls) have increased since the 2000s, whereas the occurrence of debris flows has increased only since 2010. The current climate-warming trend registered in the study area apparently increases the elevation of rockfall-detachment areas by approximately 300 m, mostly controlled by the combined effects of frost-cracking and permafrost thawing. In contrast, the occurrence of debris flows does not exhibit such an altitudinal shift, as it is primarily driven by extreme precipitation events exceeding the 75th percentile of the intensity-duration rainfall distribution. Potential debris-flow events in this environment may additionally be influenced by the accumulation of unconsolidated debris over time, which is then released during extreme rainfall events. Overall, there is evidence that the upper Sulden/Solda basin (above ca. 2500 m above sea level [a.s.l.]), and especially the areas in the proximity of glaciers, have experienced a significant decrease in slope stability since the 2000s, and that an increase in rockfalls and debris flows during spring and summer can be inferred. Our study thus confirms that “forward-looking” hazard mapping should be undertaken in these increasingly frequented, high-elevation areas of the Alps, as environmental change has elevated the overall hazard level in these regions
THE SULDEN/SOLDA GLACIER (EASTERN ITALIAN ALPS): FLUCTUATIONS, DYNAMICS, AND TOPOGRAPHIC CONTROL OVER THE LAST 200 YEARS
No full textThe Sulden/Solda glacier, located in the Ortler/Ortles massif (South Tyrol, Eastern Italian Alps), currently (2017 data) covers an area of ca. 5.2 km2. The glacier ranges in elevation from about 3500 m to 2440 m a.s.l., and it is largely debris-covered below 2900 m. By combining bibliographic resources, topographic maps and aerial images, we reconstructed the evolution of the Sulden Glacier since the beginning of the 19th century. The result is a detailed history of the glacier variations over the last 200 years, which reveals the complex interactions existing between glacier dynamics and valley morphology. The Sulden Glacier is formed by three ice bodies originating in the uppermost part of the Sulden catchment. In the past, the three glaciers merged to a single valley glacier that flowed northward down to the village of Sulden/Solda, at an elevation of ca. 1900 m a.s.l.. The evolution of these three ice bodies has not been uniform through time, and this heterogeneity drove some of the most impressive dynamics which have characterized the glacier history. In particular, the most prominent advances of the 19th century, including the 1818 surge, were driven by the lateral ice bodies of the Sulden Glacier that advanced and pushed the glacier tongue forward. When retreating, the morphology of the valley floor - characterized by several valley steps, played an important role in fragmenting the glacier, creating very large bodies of dead ice. The last prominent advance of the Sulden Glacier occurred in the 1920s (and lasted until 1927) and, excluding the small advance in the 1980s, the glacier hasbeen retreating since the 1930s. From topographic reconstructions we can estimate the volume of ice lost from 1936 to 2019 in ca. 169 million m3 (18.7 m w.e.). Out of these, ca. 144 million m3 (the 85%) have been lost after 1985, highlighting the inexorable impact of recent global warming
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
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