1,720,958 research outputs found
Il ruolo dell’esposizione e della pendenza dei versanti sullo stress idrico della vegetazione
Get PDFIl presente lavoro si pone l’obiettivo di descrivere gli effetti della morfologia sulle dinamiche di imbibizione del suolo, sull’evapotraspirazione e sullo stato della vegetazione. Questi processi sono strettamente collegati tra loro e influenzati dal
bilancio radiativo al suolo. La radiazione solare, infatti, che dipende dalle condizioni climatiche e dalla morfologia, può sensibilmente modificare i processi idrologici alla scala locale. Nel presente lavoro si è fatto ricorso all’approccio proposto da Allen et al. (2006) che consente di descrivere il bilancio radiativo tenendo conto degli effetti dell’esposizione e pendenza dei versanti. Ciò è estremamente utile per descrivere la distribuzione spaziale della radiazione solare e
dell’evapotraspirazione potenziale che condiziona le dinamiche di umidità del suolo così come lo stress idrico della vegetazione durante la stagione vegetativa. Le analisi sono state condotte sul bacino Rio Salado (New Mexico-USA) definendo lo stresso idrico della vegetazione attraverso il modello proposto da Porporato et al.
(2001). Le analisi hanno evidenziato che la morfologia del bacino influisce in maniera significativa sulla distribuzione spaziale dello stress idrico favorendo una diversità nella composizione della vegetazione. Questa variabilità è condizionata in modo marcato dalle condizioni iniziali del suolo legate al periodo dormiente della
vegetazione in cui si osservano maggiori differenze nel bilancio radiativo
Soil moisture estimation from high-resolution UASs imagery based on machine learning approaches for land cover classification
No full textModeling Vegetation Patterns in Semiarid Environment
No full textThe aim of this work is to deepen our understanding on the mutual relationship between climate, vegetation and soil water budget within an ecohydrological framework. To this end a coupled hydrological/ecological model is adopted to describe simultaneously vegetation pattern evolution and soil water budget in a semiarid river basin in New Mexico. This represents an ideal area to study the properties of water-controlled ecosystems. Analysis have been carried out using a recently formulated framework for the water balance at the daily level linked with a vegetation model for the description of the spatial organization of vegetation. Using this approach, we identified the dynamic water stress of vegetation during the growing season paying particular attention to the spatial distribution of solar radiation and the initial soil moisture condition at the beginning of the growing season. Several different variants of the vegetation model have been tested with the aim to identify the main drivers for the spatial organization of the vegetation. Results clearly show that vegetation patterns emerge from minimization of water stress and the maximization of water use
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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