1,720,975 research outputs found
Effect of texture on the dynamics of a water saturated biochar
No full textBiochar is defined as charred organic matter applied to soil in a deliberate manner, with the intent to improve soil properties (Lehmann et al., 2009). Biomass-derived char can be used as energy carrier, as adsorber and as material for the improvement of soil properties. Carbonized organic matter can have different physical and chemical properties depending on the technology used for its production. Moreover char texture influences deeply physical and chemical properties. In this work effect of texture on the dynamics of a water saturated biochar was analyzed by FFC NMR.
An industrial biochar derived from gasification of poplar wood was sieved to determine influence of texture on water dynamic on particles surface.
Sieves with 2, 1 and 0.3 mm have been used to separate three different texture fractions.
Each sample has been saturated with water and then analysed by FFC NMR relaxometry by applying a range of magnetic field from 40MHz to 0.01MHz.
Three profiles with different longitudinal relaxation rate have been carried out. Sample with texture 1-2mm has a profile with the lowest longitudinal relaxation rate (R1). Profile of sample with textures <0.3mm has the profile with highest R1.
Behavior of water can be explained associating an increment of longitudinal relaxation rate with an increment of porosity.
Surface area reduction is achieved when the sizes of the pores increase. As water molecules flow through larger sized pores, their motion occurs at a frequency that is broader than that of water molecules constrained in smaller sized pores. For this reason quickly moving water can not efficaciously interact with either neighboring molecules or with the molecular sites on the surface at the liquid-solid interface. As a consequence intermolecular dipolar interactions are weakened and a reduction of the proton longitudinal relaxation rate (shorter R1 values) can be observed compared with the R1 values for slowly moving or immobilized water systems
Il dissesto geomorfologico indotto dalle precipitazioni negli eventi meteorici critici degli ultimi dieci anni in Abruzzo (Italia centrale).
No full textIn the last ten years, the Abruzzi region was affected by several heavy rainfall events. Almost three of them have had daily rainfall > 100 mm and >200 mm in few days. In this work the heavy rainfall events occurred on 23-25 January 2003 (in the whole region), on 6-7 October 2007 (in a small part of the hilly and coastal Teramo area), and on 1-2 March 2011 (in the hilly and coastal Teramo and Pescara area). These events have triggered different types of geomorphological instability: landslides, soil erosion, flooding. Distribution and types of instabilities and landforms is almost different in the three cases.
In this work the 2003, 2007 and 2011 heavy rainfall events were analyzed concerning meteorological aspects, geological and geomorphological features, highlighting common and different geomorphological effects on the landscape.
Heavy rainfall were analyzed processing a >40 pluviometric station database provided by Servizio Idrografico e Mareografico (Direzione Protezione Civile e Ambiente, Regione Abruzzo) including daily and monthly historical data (30-70 years) and 5-15 min pluviometric registrations for at least six days around the main events. The data processing enabled the analysis and comparison of hourly rainfall intensity, cumulative rainfall, daily rainfall, monthly rainfall and previous month rainfall.
Geomorphological effects of heavy rainfall were analyzed through field surveys, aerial photo analysis, and inventories or technical reports, mapping the distribution of landslides, soil erosion, flooding.
The 2003 heavy rainfall event affected the almost entire region (Chieti and Pescara province and part of L’Aquila and Teramo), for almost 72 h, with moderately high intensity (~10-15 mm/hr, 80-120 mm/day), high cumulative rainfall (up to >200 mm), occurred after two month of high rainfall, on a poorly vegetated landscape due to the winter season. These features induced heavy flooding within the main alluvial plains and triggered ~1300 landslides from small to very wide, whose distribution was controlled mostly by lithology (91% on clay-sand deposits, 2% carbonate rocks and 7% on clastic Quaternary continental deposits) and by structural geomorphological setting.
The 2007 heavy rainfall event affected a local area (hilly and costal Tortoreto area between F. Salinello and T. Vibrata within the Teramo province), for a short time (14-16 h), with high intensity (10-40 mm/hr, up to >200 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of low rainfall, on a very poorly vegetated landscape, particularly on agricultural areas (arable land, vineyard and olive groves) due ploughing. These features induced heavy soil erosion processes on slopes, rapid earth flows at the base of slopes or minor drainage basins, and flooding within the main alluvial plains, mostly due to minor tributary drainage basins. This is also controlled by the structural geomorphological features of the radial drainage pattern, incorporating the coastal streams and tributary streams of the lower valleys of F. Salinello and T. Vibrata.
The 2011 heavy rainfall event affected a province area (hilly and costal Teramo area), for a moderately short time (22-26 h), with high intensity (~15-35 mm/hr, up to 180 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of moderate rainfall, on a moderately vegetated landscape on agricultural areas (arable land, vineyard and olive groves) due to initial crop growth stage and grass development. These features induced moderate soil erosion processes on slopes and rapid earth flows at the base of slopes or minor drainage basins (less than 2007 event). The crop and grass cover promoted surface runoff directly to the main rivers, protecting slopes from soil erosion. Heavy flooding affected alluvial plains and coastal plains, due to both tributary and main rivers, with the formation of widespread crevasse splay. Also in this case runoff and flooding were increased by structural geomorphological features of the radial and trellis drainage pattern of the Teramo hilly area.
This work allow to highlight that these type of methods, investigations, and data is basic in applied studies for stabilisation and management of slopes and minor or major drainage basins and for general land management. Only a high knowledge level of geomorphological instability, connected to drainage, geological-geomorphological, and morphostructural features and to meteorological events, particularly when joined to geotechnical data, allow effective stabilisation and management plans.
Finally, these type of studies is basic and complementary to recent methods for investigation and mapping of land sensitivity to geomorphological processes such as landslides, soil erosion, desertification, etc., and allow to define future scenarios, which sustainable land planning and management should be based on, taking into account specific destination of different areas, and contributing to identify proper sites for quarry, dump, purification plant, etc., or proper areas for industries, urban expansion, or in general to support the process of creating an urban plan
Analysis of soil erosion induced by heavy rainfall: A case study from the NE Abruzzo Hills Area in Central Italy
No full textSoil erosion induced by heavy rainfall deeply affects landscape changes and human activities. It depends on rainfall distribution (e.g., intensity, duration, cumulative per event) and is controlled by the interactions between lithology, orography, hydrography, land use, and vegetation. The Abruzzo piedmont coastal hilly area has been affected by several heavy rainfall events in the last decades. In this work, we investigated three ~1-day heavy rainfall ( > 35 mm/h and 100-220 mm/day) events in 2007, 2011, and 2012 that occurred in the clayey hilly coastal NE Abruzzo area, analyzing cumulative rainfall, intensity, and duration while mapping triggered geomorphological effects (soil erosion and accumulation) and evaluating average erosion. The analysis provides contributions to a soil erosion assessment of clayey landscapes that characterizes the Adriatic hilly area, with an estimation of rainfall-triggering thresholds for heavy soil erosion and a comparison of erosion in single events with rates known in the Mediterranean area. The triggering threshold for heavy soil erosion shows an expected value of ~100-110 mm. The estimated average soil erosion is from moderate to high (0.08-3.08 cm in ~1-day heavy rainfall events) and shows a good correlation with cumulative rainfall and a poor correlation with peak rainfall intensity. This work outlines the strong impact of soil erosion on the landscape changes in the Abruzzo and Adriatic hilly areas
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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