1,721,069 research outputs found
Conservation tillage and N fertilization affect soil aggregate distribution, carbon storage and enzymatic activities
Full text linkConservation agriculture is globally recommended for increasing carbon (C) stock in soil and reducing greenhouse gases emissions by modifying soil physical, chemical and biological processes. In the present study, soil aggregate fractions, soil organic C (SOC) and soil enzymatic activities in bulk soil and microaggregates within macroaggregates (mM) were measured in a long-term field experiment comparing conventional tillage (CT) and minimum tillage (MT) and N fertilizer to the rotation bread wheat (Triticum aestivum L.) – soybean (Glicine max L. Merr.). Under MT, a higher proportion of free microaggregates and a lower proportion of silt and clay was recorded compared to conventional tillage, suggesting a greater potential to form macroaggregates, despite their proportion was not modified by tillage. However, when macroaggregates were further fractionated, MT resulted in higher proportion of microaggregates. In bulk soil and in mM, all soil enzymatic activities were higher under MT than CT. Conversely, SOC in bulk soil was not modified by tillage, but was higher under MT in mM. These results demonstrate the crucial role of mM for C sequestration under reduced tillage. Thus, this fraction is proposed as an effective diagnostic tool to assess variations in carbon storage induced by agricultural practices
Fruit tree orchard establishment
No full textThe agronomic and economic success of a fruit-tree orchard is mainly determined by the choices made by the grower during the planting stage. A distinctive feature of fruit tree orchards is the very high investment cost for their establishment and the fluctuations in the revenue stream over their lifetime. Growers do not immediately make a profit after planting, and their
success depends on the proper choice of fruit tree species, on orchard design and on the specific goals they choose to pursue. Moreover, profitability will also depend on a careful analysis of the economic, environmental, technological, social and infrastructural (transportation system, energetic resources, supply chain logistic) resources available. Today, most fruit
tree growers opt to specialize and intensify their production.
However, tree density (number of plants per hectare), length of the economically unproductive period, farming methods, production stability over time and many other factors, including ecological sustainability, should be taken into account by the grower when establishing an orchard
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
Classificazione della tipologia di stress (idrico/salino) in un contesto di plant phenotyping in vite
No full textIl riconoscimento precoce e rapido dei tipi di stress abiotici potrebbe accelerare la selezione di nuove varietà resistenti allo stress, o impostare tempestivamente pratiche di gestione adeguate. Questo studio presenta una rianalisi dei dati provenienti da esperimenti di Vitis vinifera in vaso sottoposta a stress idrico e salino al fine di identificare parametri in grado di classificare il tipo di stress.
Vengono confrontati parametri di scambio gassoso dipendenti dalla conduttanza stomatica (gs) e e non-stomatici (efficienza del fotosistema II, Fv/Fm), e fenotipici (variazione della banda di colore Dark Green nelle foglie).
Nel caso dello stress salino, i valori di Fv/Fm nelle piante stressate è significativamente (p<0.05) declinato del 25% raggiungendo circa 0.6 ±0.02 SD alla fine dello stress (9 gg). Al contrario, in caso di stress idrico, i valori di Fv/Fm dopo circa 20 gg di stress erano ancora comparabili (p>0.05) a quelli iniziali (circa 0.75±0.02 SD). Tale risultato conferma che difficilmente la vite va incontro ad una fotoinibizione permanete in caso di stress idrico.
La correlazione fra gs e tasso fotosintetico netto (Pn) mostrano i valori di Pn maggiormente ridotti in caso di stress salino rispetto a quelli dello stress da siccità a valori di gs equivalenti. I modelli non-lineari (asintotici) di tali correlazioni sono risultati significativamente distinguibili (p<0.05) confermando che i due tipi di stress sottendono processi in parte diversificati.
Attraverso una PCA, le variabili Pn, traspirazione, gs, potenziale dello stelo, Fv/Fm e Dark Green sono state scomposte e le prime due PC spiegano circa 90% della varianza complessiva. Inoltre, Dark Green e Fv/Fm dominano la PC2 definita “non-stomatica” contribuendo per l’80% alla PC2 separando i tipi di stress. Il potenziale idrico dello stelo è risultato avere un peso simile fra le due PC confermando la similitudine fra i due tipi di stress e la sua bassa capacità di servire come discriminante i tipi di stress.
In conclusione, l’insieme alla classe di colore Dark Green e Fv/Fm potrebbe supportare l'identificazione precoce e non distruttiva del tipo di stress
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
Un diálogo entre Marx y Foucault. Entrevista a Antonio Negri
Full text linkAn interview with Antonio Negri about Marx and Foucault, published by Polity Press in 2017.Entrevista realizada a Antonio Negri acerca de su libro Marx and Foucault, publicado por Polity Press en 2017.Traducción del italiano: Luca Sebastiani
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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