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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
Soil microorganisms as hidden miners of phosphorus in soils under different cover crop and tillage treatments
Full text linkPhosphorus (P) is one of the most limiting plant nutrients for agricultural production. The soil microbial community plays a key role in nutrient cycling, affecting access of roots to P, as well as mobilization and mineralization of organic P (Porg). This thesis aimed to better understand the potential of cover crops to enhance plant-soil-microbe interactions to improve the availability of P.
This dissertation consists of a meta-analysis of and two field experiments.
The used methods showed that microbial P, the activity of P-cycling enzymes and PLFAs increased under cover crops, indicating an enhanced potential for organic P cycling. Gram- positive and Gram-negative bacteria, and to a lesser extent also arbuscular mycorrhizal fungi, increased their abundance with cover crops. However, saprotrophic fungi could benefit most from the substrate input derived from cover crop roots or litter. Enzyme-stable Porg shifted towards pools of a greater lability in the active soil compartments (rhizosheath and detritusphere). The effects of agricultural management, such as cover crop species choice and tillage, were detectable, but weaker compared to the effect of the presence of cover crops.
With the obtained results, the research aims of this thesis could be successfully addressed. We were able to confirm that cover crops have the potential to improve main crops access to P. Furthermore, we presented and discussed three pathways of P benefit. In the plant biomass pathway, P is cycled through cover crop biomass and becomes available for the main crop upon litter decomposition. The microbial enhancement pathway describes how the cover crops interaction with soil microbes increases their abundance and activity, thereby increasing the availability of Porg. Some cover crop species seem to be capable of utilizing a biochemical modification pathway, where changes in the sorption capacity of the soil result in a greater quantity of plant-available phosphate. However, the latter pathway was apparently not important in the crop rotations used in our field experiments. The data also allowed us to characterize ways in which plant-soil-microbe interactions under cover crops affected the relationship of soil microbial functions to the enzymatic availability of Porg pools. Cover crops increased the abundance and activity of microbes, especially fungi, as well as microbial P. This enhancement in P-cycling potential shifted Porg toward pools of greater availability to added enzymes. However, the relation between enzymes and Porg pools is complex and is possibly affected by soil P composition and other site characteristics, indicating the need for further research in this area. Finally, we elucidated how the choice of cover crop species and agricultural management can shift the relative importance of the pathways for the P benefit of the main crop, while site-specific management allows farmers to adapt to local conditions and to optimize the functions of their agroecosystems.
In conclusion, our results indicate that the pathways of cover crop derived P benefit take place simultaneously. We confirmed the potential of cover crop biomass for the cycling of P, and we suggest that our observed increases in the availability of soil Porg are related to microbial abundance and activity. The interactions of cover cropping and tillage indicate also that P benefit can be optimized by management decisions. Finally, these new insights into soil phosphorus cycling in agroecosystems have the potential to support further development of more sustainable agricultural systems.Phosphor (P) ist einer der wichtigsten limitierenden Naehrstoffe fuer das Pflanzenwachstum in der Landwirtschaft. Bodenmikroben spielen eine Schluesselrolle in Naehrstoffkreislaeufen, beeinflussen das Wachstum von Pflanzenwurzeln, die Mobilisierung sowie die Mineralisierung von organischem P (Porg) und somit den Zugang zu P. Das Ziel dieser Dissertation war die Einschaetzung des Potentials von Zwischenfruechten zur Verbesserung der Interaktionen im System Pflanze-Boden-Mikroben und einer dadurch moeglichen Steigerung der P-Verfuegbarkeit fuer die Hauptfruechte.
Diese Dissertation umfasst drei wissenschaftliche Veroeffentlichungen: Eine Literaturrecherche und Meta-Analyse sowie zwei selbst durchgefuehrte Feldexperimente.
Die verwendeten Methoden zeigten, dass Zwischenfruechte den P-Gehalt in der mikrobiellen Biomasse, die Aktivitaet von Phosphatasen und mikrobielle Fettsaeuremarker (PLFAs) erhoehen, was auf ein gesteigertes Umsatzpotential von organischen Phosphorverbindungen hindeutet. Die Abundanz von grampositiven und gramnegativen Bakterien, sowie in geringerem Umfang auch von arbuskulaeren Mykorrhizapilzen, wurde durch Zwischenfruechte erhoeht. Gleichwohl waren saprotrophe Bodenpilze die mikrobielle Gruppe, die am meisten von der Substratzufuhr der Wurzeln und Streu profitieren konnte. Stabiles P wurde in den aktiven Bodenzonen der Rhizosphaere und Detritusphaere in labilere Porg-Pools transformiert. Bewirtschaftungseffekte, wie die Wahl der Zwischenfrucht oder Bodenbearbeitung, waren erkennbar, aber wesentlich schwaecher ausgepraegt als der Zwischenfruchteffekt insgesamt.
Unsere Ergebnisse bestaetigen, dass Zwischenfruchtanbau zur Steigerung der P - Verfuegbarkeit fuer die Hauptfrucht fuehren kann. Darueber hinaus konnten wir fuer den P- Vorteil drei grundsaetzliche Wirkungspfade aufzeigen, die in aktiven Bodenraeumen stattfinden. UEber den Wirkungspfad Pflanzenbiomasse wird P aus dem Boden in die Biomasse der Zwischenfrucht aufgenommen und waehrend der Zersetzung der Streu fuer die Hauptfrucht verfuegbar. UEber den Wirkungspfad mikrobielle Verstaerkung steigert die Zwischenfrucht im Wurzelraum die Biomasse und Aktivitaet der mikrobiellen Gemeinschaft, wodurch diese die Verfuegbarkeit von Porg erhoehen kann. Durch den Wirkungspfad biochemische Modifikation scheinen manche Zwischenfruchtarten in der Lage zu sein, ueber Wurzelexsudate die P-Sorption im Boden zu senken und dadurch den Anteil an pflanzenverfuegbarem Phosphat zu erhoehen.
Weiterhin ermoeglichen die erhobenen Daten die Diskussion, inwiefern mikrobielle Funktionen und die Mineralisierbarkeit von Porg zusammenhaengen und wie die Interaktionen von Pflanzen beeinflusst werden. Zwischenfruechte steigerten sowohl die Abundanz und Aktivitaet von Mikroben, als auch die Menge an P in der mikrobiellen Biomasse. Diese Potentialsteigerung des P-Kreislaufs steigerte die Verfuegbarkeit des Porg fuer zugefuegte Enzyme. Es muss bedacht werden, dass die Rueckkopplungen zwischen Enzymaktivitaet und verschiedenen Porg-Pools komplex sind. Diese haengen von den lokalen Eigenschaften des Bodens, wie etwa der Zusammensetzung des P-Vorrats, ab und sollten durch zukuenftige Studien geklaert werden.
Drittens zeigen unsere Untersuchungen, wie die Wahl der Zwischenfrucht und die der Bewirtschaftung (z.B. Bodenbearbeitung oder Fruchtfolge) die relative Gewichtung der verschiedenen Pfade des P-Vorteils fuer die Hauptfrucht beeinflussen. Standortangepasste Zwischenfruchtsysteme erlauben es Landwirt:innen, die Funktionen ihres Agrooekosystems hinsichtlich der lokalen Bedingungen zu optimieren.
Zusammenfassend bestaetigen unsere Ergebnisse, dass der P-Bedarf der Hauptfrucht ueber die Biomasse der Zwischenfrucht gedeckt werden kann und zeigen auf, dass die charakterisierten drei Pfade des P-Vorteils durch Zwischenfruchtanbau parallel stattfinden. Schließlich koennen die hier gewonnenen Erkenntnisse ueber den Phosphorkreislauf, basierend auf der Kombination von bodenmikrobiologischen Methoden mit der Charakterisierung der Labilitaet von Porg, zur zukuenftigen Entwicklung einer nachhaltigeren Landwirtschaft beitragen
Mikroorganismen, die unsichtbaren Bergleute für Phosphor in Böden mit unterschiedlichen Zwischenfrüchten und Bodenbearbeitung
Full text linkPhosphorus (P) is one of the most limiting plant nutrients for agricultural production. The soil microbial community plays a key role in nutrient cycling, affecting access of roots to P, as well as mobilization and mineralization of organic P (Porg). This thesis aimed to better understand the potential of cover crops to enhance plant-soil-microbe interactions to improve the availability of P.
This dissertation consists of a meta-analysis of and two field experiments.
The used methods showed that microbial P, the activity of P-cycling enzymes and PLFAs increased under cover crops, indicating an enhanced potential for organic P cycling. Gram- positive and Gram-negative bacteria, and to a lesser extent also arbuscular mycorrhizal fungi, increased their abundance with cover crops. However, saprotrophic fungi could benefit most from the substrate input derived from cover crop roots or litter. Enzyme-stable Porg shifted towards pools of a greater lability in the active soil compartments (rhizosheath and detritusphere). The effects of agricultural management, such as cover crop species choice and tillage, were detectable, but weaker compared to the effect of the presence of cover crops.
With the obtained results, the research aims of this thesis could be successfully addressed. We were able to confirm that cover crops have the potential to improve main crops’ access to P. Furthermore, we presented and discussed three pathways of P benefit. In the plant biomass pathway, P is cycled through cover crop biomass and becomes available for the main crop upon litter decomposition. The microbial enhancement pathway describes how the cover crop’s interaction with soil microbes increases their abundance and activity, thereby increasing the availability of Porg. Some cover crop species seem to be capable of utilizing a biochemical modification pathway, where changes in the sorption capacity of the soil result in a greater quantity of plant-available phosphate. However, the latter pathway was apparently not important in the crop rotations used in our field experiments. The data also allowed us to characterize ways in which plant-soil-microbe interactions under cover crops affected the relationship of soil microbial functions to the enzymatic availability of Porg pools. Cover crops increased the abundance and activity of microbes, especially fungi, as well as microbial P. This enhancement in P-cycling potential shifted Porg toward pools of greater availability to added enzymes. However, the relation between enzymes and Porg pools is complex and is possibly affected by soil P composition and other site characteristics, indicating the need for further research in this area. Finally, we elucidated how the choice of cover crop species and agricultural management can shift the relative importance of the pathways for the P benefit of the main crop, while site-specific management allows farmers to adapt to local conditions and to optimize the functions of their agroecosystems.
In conclusion, our results indicate that the pathways of cover crop derived P benefit take place simultaneously. We confirmed the potential of cover crop biomass for the cycling of P, and we suggest that our observed increases in the availability of soil Porg are related to microbial abundance and activity. The interactions of cover cropping and tillage indicate also that P benefit can be optimized by management decisions. Finally, these new insights into soil phosphorus cycling in agroecosystems have the potential to support further development of more sustainable agricultural systems.Phosphor (P) ist einer der wichtigsten limitierenden Naehrstoffe fuer das Pflanzenwachstum in der Landwirtschaft. Bodenmikroben spielen eine Schluesselrolle in Naehrstoffkreislaeufen, beeinflussen das Wachstum von Pflanzenwurzeln, die Mobilisierung sowie die Mineralisierung von organischem P (Porg) und somit den Zugang zu P. Das Ziel dieser Dissertation war die Einschaetzung des Potentials von Zwischenfruechten zur Verbesserung der Interaktionen im System Pflanze-Boden-Mikroben und einer dadurch moeglichen Steigerung der P-Verfuegbarkeit fuer die Hauptfruechte.
Diese Dissertation umfasst drei wissenschaftliche Veroeffentlichungen: Eine Literaturrecherche und Meta-Analyse sowie zwei selbst durchgefuehrte Feldexperimente.
Die verwendeten Methoden zeigten, dass Zwischenfruechte den P-Gehalt in der mikrobiellen Biomasse, die Aktivitaet von Phosphatasen und mikrobielle Fettsaeuremarker (PLFAs) erhoehen, was auf ein gesteigertes Umsatzpotential von organischen Phosphorverbindungen hindeutet. Die Abundanz von grampositiven und gramnegativen Bakterien, sowie in geringerem Umfang auch von arbuskulaeren Mykorrhizapilzen, wurde durch Zwischenfruechte erhoeht. Gleichwohl waren saprotrophe Bodenpilze die mikrobielle Gruppe, die am meisten von der Substratzufuhr der Wurzeln und Streu profitieren konnte. Stabiles P wurde in den aktiven Bodenzonen der Rhizosphaere und Detritusphaere in labilere Porg-Pools transformiert. Bewirtschaftungseffekte, wie die Wahl der Zwischenfrucht oder Bodenbearbeitung, waren erkennbar, aber wesentlich schwaecher ausgepraegt als der Zwischenfruchteffekt insgesamt.
Unsere Ergebnisse bestaetigen, dass Zwischenfruchtanbau zur Steigerung der P - Verfuegbarkeit fuer die Hauptfrucht fuehren kann. Darueber hinaus konnten wir fuer den P- Vorteil drei grundsaetzliche Wirkungspfade aufzeigen, die in aktiven Bodenraeumen stattfinden. UEber den Wirkungspfad „Pflanzenbiomasse“ wird P aus dem Boden in die Biomasse der Zwischenfrucht aufgenommen und waehrend der Zersetzung der Streu fuer die Hauptfrucht verfuegbar. UEber den Wirkungspfad „mikrobielle Verstaerkung“ steigert die Zwischenfrucht im Wurzelraum die Biomasse und Aktivitaet der mikrobiellen Gemeinschaft, wodurch diese die Verfuegbarkeit von Porg erhoehen kann. Durch den Wirkungspfad „biochemische Modifikation“ scheinen manche Zwischenfruchtarten in der Lage zu sein, ueber Wurzelexsudate die P-Sorption im Boden zu senken und dadurch den Anteil an pflanzenverfuegbarem Phosphat zu erhoehen.
Weiterhin ermoeglichen die erhobenen Daten die Diskussion, inwiefern mikrobielle Funktionen und die Mineralisierbarkeit von Porg zusammenhaengen und wie die Interaktionen von Pflanzen beeinflusst werden. Zwischenfruechte steigerten sowohl die Abundanz und Aktivitaet von Mikroben, als auch die Menge an P in der mikrobiellen Biomasse. Diese Potentialsteigerung des P-Kreislaufs steigerte die Verfuegbarkeit des Porg fuer zugefuegte Enzyme. Es muss bedacht werden, dass die Rueckkopplungen zwischen Enzymaktivitaet und verschiedenen Porg-Pools komplex sind. Diese haengen von den lokalen Eigenschaften des Bodens, wie etwa der Zusammensetzung des P-Vorrats, ab und sollten durch zukuenftige Studien geklaert werden.
Drittens zeigen unsere Untersuchungen, wie die Wahl der Zwischenfrucht und die der Bewirtschaftung (z.B. Bodenbearbeitung oder Fruchtfolge) die relative Gewichtung der verschiedenen Pfade des P-Vorteils fuer die Hauptfrucht beeinflussen. Standortangepasste Zwischenfruchtsysteme erlauben es Landwirt:innen, die Funktionen ihres Agrooekosystems hinsichtlich der lokalen Bedingungen zu optimieren.
Zusammenfassend bestaetigen unsere Ergebnisse, dass der P-Bedarf der Hauptfrucht ueber die Biomasse der Zwischenfrucht gedeckt werden kann und zeigen auf, dass die charakterisierten drei Pfade des P-Vorteils durch Zwischenfruchtanbau parallel stattfinden. Schließlich koennen die hier gewonnenen Erkenntnisse ueber den Phosphorkreislauf, basierend auf der Kombination von bodenmikrobiologischen Methoden mit der Charakterisierung der Labilitaet von Porg, zur zukuenftigen Entwicklung einer nachhaltigeren Landwirtschaft beitragen
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
Efectes de la intensitat de la llaurada sobre les propietats fisicoquímiques del sòl i el desenvolupament de diferents cultius
No full textThe most widespread models of conventional agriculture worldwide are based on achieving
maximum production but have many deficiencies in terms of biodiversity conservation, soil
health, etc. Moreover, these systems are fragile and unsustainable in the face of the current
climate change situation. Agroecology is the science aimed at creating resilient and less polluting
systems by understanding the functioning of natural systems. Soil health is often an overlooked
parameter but is essential for achieving profitable crops. A soil with good health is characterized
by good structure and a healthy microbial community, thus functioning as a living system capable
of self-regulation. Tillage is a factor that can affect soil health. A study was conducted in Pallars
Jussà comparing five crops that are not widely established in the region under three different
tillage intensities (no tillage, medium intensity tillage, and high intensity tillage). The study
includes two legume crops (Lens culinaris and Vicia faba), two cereal crops (Hordeum distichon
L. and Triticum spelta), and one polyculture (Vicia sativa with Avena sativa), all managed
ecologically. This study is particularly relevant in Pallars Jussà because this region has the
potential to become self-sufficient and sustainable in response to climate change and population
needs.
The effects of tillage intensity on the soil's physicochemical properties in the short term and the
response of the five crops to different tillage intensities were studied. The results show that
tillage affects soil properties, making it more aerated and with greater water infiltration capacity.
There is no clear trend regarding its effect on chemical properties, but it is observed that untilled
soils have a more active microbial community in converting nutrients into forms usable by plants.
Tillage also affects crop growth; plants in tilled soils grow more and experience less stress.
However, there is no direct effect of tillage on the atmospheric nitrogen fixation of legumes. Nor
does any plant species show increased productivity under a specific tillage regime1
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