1,721,016 research outputs found
Evoluzione del suolo negli ecosistemi forestali di pecceta: ruolo e influenza degli humus studiati secondo un approccio morfologico
No full textVariabilità delle forme di humus in due siti campione di pecceta altimontana trentina
Full text linkHumus form variability at two experimental sites in the mountain Norway spruce forest, Trentino, Italy. In the Region Trentino Alto-Adige, 59 humus profiles were studied and classified in order to understand the
variability of humus forms in alpine forest ecosystems. In particular, the evolution of humus forms was investigated in relation to the development of vegetation cover, with the aim of determining whether a humus form can be representative of a specific forest phase. For the study of humus profiles, transects were traced so as to cut across all 4 principal dynamic phases of forest evolution: open canopy, regeneration, intermediate and mature. Two sub-sites (of about 1000 m2) were selected at an altitude of 1700 m. a.s.l., on parent soil material of morenic sediments on acid substrate and with a vegetation cover of alpine spruce forest: the first, having a north exposition, is located within the Municipality of Pellizzano in Val di Sole, near Mount Nambino; the second, with a south exposition, is located near Madonna di Campiglio, in Val Rendena, near Mount Ritorto. The soil temperature regime is frigid, while the moisture regime is udic. Our investigation pointed out a wide evolutionary variability of forest humus in the studied sites, permitting to identify a probable association trend between different growing-phases of forest and specific humus forms
Il ruolo della pedofauna nella variabilità spaziale e temporale delle forme di humus: indagini micromorfologiche su sezioni sottili ed osservazioni allo stereoscopio
No full textL'osservazione allo stereoscopio dei campioni di orizzonti diagnostici di diverse forme di humus permette di distinguere l'origine biologica di queste e di riconoscere i grandi gruppi di animali coinvolti nel processo di trasformazione della lettiera e della sua integrazione nel profilo del suolo.
- - - - - (ABSTRACT: In a spruce forest of the Autonomous Province of Trento, located on an acid substrate and with a north exposition, within the Village of Pellizzano, a transect has been traced; along this transect 19 humus profiles have been examined, one at every three meters. For each of them, OH and A horizons (respectively the humic organic and the organo-mineral horizon) have been sampled and studied following the methodology formulated by Ponge (1984) and Bernier et al. (1994). The morphological and semi-quantitative observation of these horizons with the stereoscope and the use of an identification key of soil fauna’s faecal pellets (Galvan et al. 2005) allowed us to determine and point out their relative abundance and to formulate interesting remarks on spatial and temporal variability of humus forms in forests. For four profiles of the transect, a micro-morphological study, with the microscope, of the thin sections of every horizon has been carried out as well, in order to observe those more detailed characters such as: the presence of fossilized coprolites, of paleo-aggregates and of those soil fauna’s dung, in particular mites’ faecal pellets, hardly identifiable with the stereoscope. Both methodology of morphological investigation proved to be necessary for an accurate research and to be a substantial aid for a better identification of humus forms, after they have been described in field following the French morphological-genetic approach (Jabiol et al. 1995)
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
Rainfall-Induced Landslides: Slope Stability Analysis Through Field Monitoring
No full textRainfall-induced shallow landslides are hazardous phenomena that could cause several damages to infrastructures and people. To understand the hydrological and mechanical triggering conditions of shallow landslides in an area of Oltrepo Pavese (Northern Apennines, Italy) a field monitoring was conducted. In this work the results of 16 months monitoring are shown, focusing on the hydrological behaviour of the studied materials as function of rainfall and its effect on slope stability
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
Determination of shallow landslides triggering factors and susceptibility through field monitoring in an area of Oltrepo Pavese
No full textRainfall-induced shallow landslides affect superficial soils above bedrock, with failure surface that is, generally, located within the soil-bedrock interface. Although they involve small volumes of soil, due to their close proximity to urbanized areas, they cause significant damage to structures and infrastructures and, sometimes, human losses.
To understand the effect of climatic parameters and of the soil unsaturated zone physical properties and hydrology on triggering of shallow landslides, a continuous monitoring in time of these factors is needed.
A monitoring station was installed in an area of Oltrepo Pavese (Northern Italy), where several shallow landslide events occurred in the last years. The test site slope, representative of Northern Apennines, is characterized by medium-high slope angle; the land use is constituted by shrubs developed on abandoned vineyards. The bedrock is made up of gravel, sand and poorly cemented conglomerates; the soils above bedrock materials are especially silty clayey loam.
The objectives of the research are: (a) to monitor the unsaturated zone response to seasonal and extreme rainfall events, determining also how antecedent precipitation affects pore pressure development; (b) to reconstruct a hydro-geotechnical model in order to identify the processes that could predispose the triggering of shallow landslides, c) to evaluate the factor of safety and its evolution in time in order to assess the shallow landslides susceptibility and hazard of the studied area.
The experimental station consists in a pluviometer, a thermo-hygrometer, a barometer, a sonic anemometer and a net radiometer. Six TDR probes (Time Domain Reflectometer) are installed at different depths from ground level to measure the soil volumetric water content. Three tensiometers and three heat dissipation sensors are installed to measure soil matric suction. The data are collected by a CR1000 datalogger (Campbell Sci. Inc.) every 10 minutes.
In this work the results obtained from a one year monitoring are presented. The response of unsaturated soil and weathered bedrock levels towards rainy and dry period in terms of hydrological parameters were linked to the monitored atmospheric parameters and the geotechnical properties of the investigated materials in order to reconstruct the pore-pressure response and to identify the main shallow landslides triggering factors.
This model provided the basis on the evaluation of the site study safety factor towards shallow landslides under unsaturated conditions. Furthermore, some physically based models were implemented to define the susceptibility and the hazard according to the main features which can cause the trigger of these phenomena
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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