1,720,971 research outputs found
Non-invasive monitoring and numerical modeling of the Soil-Plant continuum
Full text linkThe Earth’s critical zone (ECZ) is the near-surface domain that regulates the availability of most life-sustaining resources. Among all the subdomains of the ECZ, a crucial role is played by the Soil-Plant continuum (SP), as it is a major performer of the exchanges of mass and energy between soil and plants (and then atmosphere). However, despite its importance and its strong interconnection with human activity, the characterization of this subdomain is still in an early stage, mainly because of the lack of spatial and temporal information regarding the occurring processes. To overcome this issue, we present the combination of geophysical measurements and hydrological modeling in the framework of a hydrogeophysical approach, with the aim of characterizing the active root zone, i.e. the portion of the root system involved in the water uptake. In fact, the water uptake is performed by root hair, the microscopic cell outgrowths whose location is difficult (if not impossible) also after the removal of the root system from the soil. Nevertheless, determining its position is fundamental not only for merely scientific purposes, but most of all for practical applications, as it affects the performing of precision irrigation. Therefore, in this work I propose the identification of the active root zone on the basis of its main effect, i.e. the reduction of soil water content over time. This is achieved by means of 3-D small-scale electrical resistivity tomography (ERT) carried out combining superficial and borehole electrodes. We monitored the processes occur-ring in the root zone of three orange trees located in south-eastern Sicily. These trees are drip irrigated according to different deficit irrigation techniques to improve the exploitation of the water resource, while the plants’ transpiration is monitored thanks to sap flow and eddy covariance measurements. More in detail, in the first case study ERT measurements before and after the cut of the tree are compared, while in the second case study the ERT monitoring is focused on two orange trees drip irrigated with different treatments (i.e. full irrigation and partial root drying). The datasets thus obtained provide interesting insights into the root system activity, given their abundance of information regarding both atmospheric and underground phenomena (i.e. transpiration and root water uptake, respectively). In particular, the ERT time-lapse approach well highlights the portions subject to a decrease in water content, which can be related to the water uptake put in place by the plants. Nevertheless, the interpretation of the resistivity patterns, although combined with agronomic information, can be rather intricate. A proper hydrological modeling provides a solution to this problem, even if choosing the most suitable approach requires a specific mathematical analysis. To do this, we developed a synthetic case study with two identical hydrological models, one of which describing also the activity of an orange tree. These models resemble the real datasets provided by the ERT measurements, without all the uncertainties introduced by the geophysical acquisition and the model calibration. The location of the active root zone is reconstructed from the combination of these two models by means of Taylor series expansion, with particular reference to the effects of the approximation thus introduced. The final aim is to evaluate the proposed numerical procedure for a future application on one of real case study presented in this work
Time-lapse monitoring of the hyporheic zone of an alpine river using non-invasive methodologies
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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
TIME LAPSE ELECTRICAL RESISTIVITY TOMOGRAPHY AND DISTRIBUTED TEMPERATURE MEASUREMENTS IN THE HYPORHEIC ZONE OF AN ALPINE RIVER
No full textHydrogeophysical characterization and monitoring of the hyporheic and riparian zones: The Vermigliana Creek case study
No full textCombined geophysical surveys for the characterization of a reconstructed river embankment
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