1,720,956 research outputs found
Coefficiente di risposta produttiva (Ky) e programmazione irrigua della melanzana per ottimizzare l’uso dell’acqua
No full textEffect of Climate Change on Water Use and Irrigation Requirements of Muskmelon and Broccoli in Southern Europe
No full textISSN 1125-471
Photosynthetic Response to Water Stress of Pigweed (Amaranthus retroflexus L.) in a Southern-Mediterranean Area
No full textPigweed is an increasingly aggressive weed in semiarid environments such as Mediterranean areas, and in general the
control of all Amaranthus species is becoming more and more difficult. Increasing pigweed aggressiveness could be a result
of its ability to keep a high water use efficiency under drought conditions. An experiment was conducted to study the effect
of water stress on the photosynthetic capacity, growth, and leaf water potential of pigweed at the field level and assess if this
species, as a model for C4 weeds, is CO2-saturated at the current level of atmospheric CO2 in a Mediterranean area.
Pigweed was studied within a naturally occurring weed population in a bell pepper field in southern Italy where a rain-fed
treatment (V0) was compared to a fully irrigated one (V100) corresponding to the restoration of 100% of the maximum
crop water evapotranspiration. Soil water content was measured periodically, and net assimilation rate, stomatal
conductance, transpiration rate, and intercellular CO2 concentration were determined on pigweed leaves. Photosynthetic
rates of 37.6 mmol m22 s21 in V100 and 13.9 mmol m22 s21 in V0 were recorded, with higher transpiration rates in V100;
consequently stomatal conductance was significantly lower in rain-fed conditions (0.08 mol m22 s21)) compared to the
irrigated treatment (0.30 mol m22 s21). Photosynthesis in pigweed is not completely CO2-saturated at the current
atmospheric CO2 level in the Mediterranean area and this could affect competition and increase of aggressiveness toward
crops at the actual CO2 atmospheric concentration in agro-ecosystems. This occurs because unlike other C4 crops already
saturated for CO2, weeds that are not CO2-saturated will remain CO2-sensitive to higher ambient CO2 levels. Thus, when
they are grown in mixed stands where competition occurs, they can still suppress the slower-growing species
Scelta del criterio di programmazione irrigua per ottimizzare l’uso della risorsa idrica
No full text
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
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