1,720,985 research outputs found
Variabilità delle forme di humus in due siti campione di pecceta altimontana trentina
Full text linkAbstract: Humus 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
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
Assessment of topsoil evolution associated with land use change in Val Camonica subalpine grasslands
Full text linkAlpine pastures and meadows are agroecosystems with biological and landscape importance, protected by the European Union. Grassland areas had a rapid decline in the last decades due to changes in management and/or abandonment of traditional mountain farming in the Alps.
The aim of our study is the characterization of the relationship between historical and present-day subalpine grassland management, their plant diversity, soil properties and humus forms. Humus forms are important indicators of biological functioning of soils and of organic matter degradation pathways, easily affected by land use change.
We chose two areas in Alta Valle Camonica (Rhaetian Alps, Lombardy), between 1800-2000 m a.s.l., on sialic glacial till, characterized by strong land use changes, as visible in historical aerial photographs. Since the 70s, large herbaceous surfaces are being colonized by subalpine heath and forests, because of a decreased and more localized grazing pressure. We selected 21 sites across six dynamic phases from grazed grassland to forest, in which we performed phytosociological surveys (10x10 m) according to the Braun-Blanquet method, a soil profile and a characterization of topsoil and organic horizons to detect humus forms and properties. Standard physico/chemical soil properties were analyzed in the lab.
The widespread decrease in grazing intensity led to an expansion of less palatable grasses (e.g., Nardus stricta L.), shrubs and trees, and thus changes in plant diversity and vegetation structure.
Soils are mostly Entic/Umbric Podzols, Histosols in bogs. Humus forms are more varied: we observed Rhizo humus systems where grass roots were a main source of organic matter in soils. Mull and Amphi are the main forms in grazed areas, Dysmoders and Hemimoders in abandoned soils colonized by trees, Tangels in bogs; no Mors have been detected.
Thus, humus forms and biological activity/organic matter degradation pathways can describe the gradients in land use change. Some more differences might be observed in the experimental phases, with microbial analysis and topsoil thin section observations
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
Assessment of topsoil development associated to land use change in Val Camonica subalpine pastures
Full text linkAlpine pastures are agroecosystems with biological and landscape importance, protected by the EU; they faced a rapid decline in the last decades due to changes in management and/or abandonment of traditional mountain farming in the Alps.
The aim of our study is the characterization of the relationship between historical and present-day subalpine grassland management, their plant diversity, soil properties, erodibility, humus forms and biological quality
Monitoring of a slope affected by shallow landslides: preliminary results
Full text linkShallow landslides can be defined as slope movements, due to extreme rainfall events, affecting superficial
deposits of small thickness; their failure surface 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.
Therefore, identifying at slope scale the soil hydrological and mechanical processes which control the shallow
landslide triggering mechanisms is becoming of crucial interest in order to assess the shallow landslide suscepti-
bility using physically based models and to develop early-warning system.
For doing this an experimental monitoring station was installed in an area of the North–Eastern Oltrepo Pavese
(Northern Apennines, Italy), where several shallow landslide events occurred in the last years. The objectives
of the research are: (a) to monitor the saturated and unsaturated zone response to seasonal and extreme rainfall
events in order to identify the processes that determine the formation of shallow landslides; (b) to determine how
antecedent precipitation could affect pore pressure development.
The test site slope is representative of other sites in Northern Apennines subjected to shallow landslides: it is
characterized by medium-high gradient (more than 15
), the land use is constituted by trees and shrubs developed
on abandoned vineyards, the bedrock is made up of gravel, sand and poorly cemented conglomerates. The
geotechnical characterization of superficial deposits was based on soils analysis conducted according to the
ASTM standard, including assessment of the physical parameters of materials (grain size distribution, bulk and
dry densities and Atterberg Limits), the shear strength parameters (direct shear and triaxial tests). A pedological
and mineralogical characterization of the site were also carried out.
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 0.2, 0.4, 0.6, 1, 1.2, 1.4 meters from
ground level to measure the soil volumetric water content. To measure soil matric suction three tensiometers and
three heat dissipation sensors are installed at 0.2, 0.6, 1.2 meters from ground level. The data are collected by a
CR1000 datalogger (Campbell Sci. Inc.) every 10 minutes.
In this work preliminary results obtained from 12 months of monitoring are presented: emphasis is given to the
response of the cover materials after dry and wet periods in terms of soil water content and matric potential.
These results will be linked to determine the hydro-geotechnical processes that could predispose the triggering of
shallow landslides
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