1,720,960 research outputs found
Impact of stochastic hydrological forcing on root distribution and functioning
No full textThe objective of this thesis is to study and model the influence of climate and soil on the dynamics of root water uptake and root development. The assessment of the vertical root distribution and functioning by means of simple parameters linked to hydrologic, pedologic and vegetation characteristics can be useful for several purposes, both practical and theoretical. The more important novelty brought by this work is the analysis of the effect of the stochasticity of the hydrological forcing on these root dynamics. The stochastic ecohydrological models that we have developed show how different profiles of mean soil moisture influence the shape of the root system and favour different strategies of water uptak
Effect of water table fluctuations on phreatophytic root distribution
No full textThe verticalrootdistributionofriparianvegetationplaysarelevantroleinsoilwaterbalance,inthe
partition ofwater fluxesintoevaporationandtranspiration,inthebiogeochemistryofhyporheic
corridors, inrivermorphodynamicsevolution,andinbioengineeringapplications.Theaimofthiswork
is toassesstheeffectofthestochasticvariabilityoftheriverlevelontherootdistributionof
phreatophyticplants.Afunctiondescribingtheverticalrootprofile hasbeenanalyticallyobtainedby
coupling awhiteshotnoiserepresentationoftheriverlevelvariabilitytoadescriptionofthedynamics
of rootgrowthanddecay.Therootprofile dependsoneasilydeterminedparameters,linkedtostream
dynamics, vegetationandsoilcharacteristics.Theriparianvegetationofarivercharacterizedbyahigh
variabilityturnsouttohavearootingsystemspreadoverlargerdepths,butwithshallowermeanroot
depths. Incontrast,alowerrivervariabilitydeterminesrootprofiles withhighermeanrootdepths
Mean root depth estimation at landslide slopes
No full texttPlant rooting systems affect slope stability through the soil reinforcement given by the root network.The vertical root distribution in particular is crucial for the assessment of the critical slip surface in slopestability analyses. We propose here an expeditious way to assess the major characteristics of the rootsystem at landslide slopes.More in detail, we extend and validate an ecohydrological model proposed for flat terrain and water-dependent ecosystems by Laio et al. (2006). This model has the merit to use readily available climaticand pedologic descriptors to predict the mean root depth, but its extension to hillslopes in semi-humidenvironments requires validation. The model has been improved and then tested on a case study innorthern Tuscany (Italy) which considers 17 landslide sites where the tree rooting systems have beenmeasured.The results show a quite good match between observed and modeled mean root depths. The accuracyof the results largely depends on the improvements brought to the model in the parameters estimationphase, in particular through the application of the Curve Number method and through the refinement ofthe definition of the growing season. The results show that in 14 cases out of 17 the error is lower than30%. Furthermore, the error becomes lower than 30% at all sites if we take into account differences amongsoils in the estimation of the portion of precipitation which infiltrates into the soil. These results provethe potential of the proposed method: using few and quite readily available parameters, it allows one todetermine the mean root depths of vegetation with good accuracy: an important parameter for stabilityassessment of vegetated slopes on a large scal
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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