1,721,010 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Struktura i sastav drvenaste podzemne biomase geoksila u travnjacima i otvorenim šumama južne i središnje Angole
No full textGeoxyles, despite their ecological importance in relation to biodiversity, carbon storage, and
disturbance resistance, are often overlooked due to their life strategy of keeping most of their
biomass underground. This study fills a research gap by examining the structure and composition
of woody belowground biomass (BGB) distribution patterns in geoxyle grassland and open
woodland vegetation types across south-central Angola, using eight different sampling sites to
capture environmental variability. A direct destructive sampling approach was employed to
accurately measure BGB and corresponding carbon stocks and investigated the influence of
environmental factors on BGB allocation, with a particular emphasis on soil analysis.
The results revealed that disturbances and climate seasonality were crucial for geoxyle occurrence
and high levels of recorded BGB, while soil fertility and seasonality were identified as the primary
drivers of belowground geoxyle functional types and their diversity.
The findings of this study will contribute to a better understanding of BGB dynamics in geoxylerich ecosystems and provide valuable information for conservation and climate change mitigation
efforts. The importance of further research in this area is highlighted, as the destruction of these
habitats due to agriculture and land-use changes could result in significant losses of BGB and
contribute to global warming.Unatoč ekološkoj važnosti u kontekstu bioraznolikosti, skladištenja ugljika i otpornosti na
poremećaje, geoksili su često zanemarivani zbog svoje životne strategije držanja glavnine biomase
ispod površine zemlje. Ova studija popunjava prazninu u istraživanju ispitivanjem strukture i
sastava distribucijskih uzoraka drvenaste podzemne biomase (BGB) u vegetacijskim tipovima
geoksilnih travnjaka i otvorenih šuma diljem južno-središnje Angole, koristeći osam različitih
mjesta uzorkovanja za obuhvaćanje varijabilnosti okoliša. Pristup izravnog destruktivnog
uzorkovanja korišten je za precizno mjerenje BGB-a i odgovarajućih zaliha ugljika, te je ispitan
utjecaj okolišnih čimbenika na distribuciju BGB-a, s posebnim naglaskom na analizu tla.
Rezultati su pokazali da su učestalost poremećaja i klimatska sezonalnost bili ključni za pojavnost
geoksila i visoke razine zabilježenog BGB-a, dok su plodnost tla i sezonalnost identificirani kao
primarni pokretači podzemnih geoksilnih funkcionalnih tipova i njihove raznolikosti.
Nalazi ove studije pridonijet će boljem razumijevanju dinamike BGB-a u ekosustavima bogatim
geoksilima i pružiti relevantne informacije u svrhu konzervacije i ublažavanja klimatskih
promjena. Naglašena je važnost daljnjih istraživanja u ovom području jer bi uništavanje navedenih
staništa zbog intenziviranja poljoprivrede i promjene načina korištenja zemljišta moglo rezultirati
značajnim gubicima BGB-a i pridonijeti globalnom zatopljenju
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Struktura i sastav drvenaste podzemne biomase geoksila u travnjacima i otvorenim šumama južne i središnje Angole
No full textGeoxyles, despite their ecological importance in relation to biodiversity, carbon storage, and
disturbance resistance, are often overlooked due to their life strategy of keeping most of their
biomass underground. This study fills a research gap by examining the structure and composition
of woody belowground biomass (BGB) distribution patterns in geoxyle grassland and open
woodland vegetation types across south-central Angola, using eight different sampling sites to
capture environmental variability. A direct destructive sampling approach was employed to
accurately measure BGB and corresponding carbon stocks and investigated the influence of
environmental factors on BGB allocation, with a particular emphasis on soil analysis.
The results revealed that disturbances and climate seasonality were crucial for geoxyle occurrence
and high levels of recorded BGB, while soil fertility and seasonality were identified as the primary
drivers of belowground geoxyle functional types and their diversity.
The findings of this study will contribute to a better understanding of BGB dynamics in geoxylerich ecosystems and provide valuable information for conservation and climate change mitigation
efforts. The importance of further research in this area is highlighted, as the destruction of these
habitats due to agriculture and land-use changes could result in significant losses of BGB and
contribute to global warming.Unatoč ekološkoj važnosti u kontekstu bioraznolikosti, skladištenja ugljika i otpornosti na
poremećaje, geoksili su često zanemarivani zbog svoje životne strategije držanja glavnine biomase
ispod površine zemlje. Ova studija popunjava prazninu u istraživanju ispitivanjem strukture i
sastava distribucijskih uzoraka drvenaste podzemne biomase (BGB) u vegetacijskim tipovima
geoksilnih travnjaka i otvorenih šuma diljem južno-središnje Angole, koristeći osam različitih
mjesta uzorkovanja za obuhvaćanje varijabilnosti okoliša. Pristup izravnog destruktivnog
uzorkovanja korišten je za precizno mjerenje BGB-a i odgovarajućih zaliha ugljika, te je ispitan
utjecaj okolišnih čimbenika na distribuciju BGB-a, s posebnim naglaskom na analizu tla.
Rezultati su pokazali da su učestalost poremećaja i klimatska sezonalnost bili ključni za pojavnost
geoksila i visoke razine zabilježenog BGB-a, dok su plodnost tla i sezonalnost identificirani kao
primarni pokretači podzemnih geoksilnih funkcionalnih tipova i njihove raznolikosti.
Nalazi ove studije pridonijet će boljem razumijevanju dinamike BGB-a u ekosustavima bogatim
geoksilima i pružiti relevantne informacije u svrhu konzervacije i ublažavanja klimatskih
promjena. Naglašena je važnost daljnjih istraživanja u ovom području jer bi uništavanje navedenih
staništa zbog intenziviranja poljoprivrede i promjene načina korištenja zemljišta moglo rezultirati
značajnim gubicima BGB-a i pridonijeti globalnom zatopljenju
Struktura i sastav drvenaste podzemne biomase geoksila u travnjacima i otvorenim šumama južne i središnje Angole
No full textGeoxyles, despite their ecological importance in relation to biodiversity, carbon storage, and
disturbance resistance, are often overlooked due to their life strategy of keeping most of their
biomass underground. This study fills a research gap by examining the structure and composition
of woody belowground biomass (BGB) distribution patterns in geoxyle grassland and open
woodland vegetation types across south-central Angola, using eight different sampling sites to
capture environmental variability. A direct destructive sampling approach was employed to
accurately measure BGB and corresponding carbon stocks and investigated the influence of
environmental factors on BGB allocation, with a particular emphasis on soil analysis.
The results revealed that disturbances and climate seasonality were crucial for geoxyle occurrence
and high levels of recorded BGB, while soil fertility and seasonality were identified as the primary
drivers of belowground geoxyle functional types and their diversity.
The findings of this study will contribute to a better understanding of BGB dynamics in geoxylerich ecosystems and provide valuable information for conservation and climate change mitigation
efforts. The importance of further research in this area is highlighted, as the destruction of these
habitats due to agriculture and land-use changes could result in significant losses of BGB and
contribute to global warming.Unatoč ekološkoj važnosti u kontekstu bioraznolikosti, skladištenja ugljika i otpornosti na
poremećaje, geoksili su često zanemarivani zbog svoje životne strategije držanja glavnine biomase
ispod površine zemlje. Ova studija popunjava prazninu u istraživanju ispitivanjem strukture i
sastava distribucijskih uzoraka drvenaste podzemne biomase (BGB) u vegetacijskim tipovima
geoksilnih travnjaka i otvorenih šuma diljem južno-središnje Angole, koristeći osam različitih
mjesta uzorkovanja za obuhvaćanje varijabilnosti okoliša. Pristup izravnog destruktivnog
uzorkovanja korišten je za precizno mjerenje BGB-a i odgovarajućih zaliha ugljika, te je ispitan
utjecaj okolišnih čimbenika na distribuciju BGB-a, s posebnim naglaskom na analizu tla.
Rezultati su pokazali da su učestalost poremećaja i klimatska sezonalnost bili ključni za pojavnost
geoksila i visoke razine zabilježenog BGB-a, dok su plodnost tla i sezonalnost identificirani kao
primarni pokretači podzemnih geoksilnih funkcionalnih tipova i njihove raznolikosti.
Nalazi ove studije pridonijet će boljem razumijevanju dinamike BGB-a u ekosustavima bogatim
geoksilima i pružiti relevantne informacije u svrhu konzervacije i ublažavanja klimatskih
promjena. Naglašena je važnost daljnjih istraživanja u ovom području jer bi uništavanje navedenih
staništa zbog intenziviranja poljoprivrede i promjene načina korištenja zemljišta moglo rezultirati
značajnim gubicima BGB-a i pridonijeti globalnom zatopljenju
How root morphology and functional traits enable geoxyles to thrive in nutrient poor and disturbance prone Angolan miombo ecosystems
No full textThe miombo ecoregion encompasses a vast African dry woodland ecosystem that dominates about 47% of Angola's territory, especially in the central areas of the country. The ecoregion, which extends from the Angolan escarpment to the Indian Ocean in Mozambique and Tanzania, covers more than 3.8 million km².
In general, miombo ecosystems form a mosaic of forest and woodland patches with grasslands co-dominated by geoxyles. Geoxyles (also known as geoxylic suffrutices) are low shrubs or semi-shrubs with mostly short-lived above-ground shoots but strong development of underground woody shoots, roots and tubers. Geoxyles have their global diversity centre in the Zambezian phytochorion, where geoxyles from more than 30 different plant families occur.
As grasslands dominated by geoxyles are an important and little studied part of the miombo ecoregion, I have conducted studies on diversity, root morphology, functional traits (PFTs) and ecological functions of geoxyles on the southern slope of the Bié Plateau (Chitembo municipality, south central Angola) as part of the Future Okavango (TFO) project. My objectives were a) to provide an updated overview of the diversity and distribution of geoxyles and geoxyle grasslands in Angola, b) to describe the vegetation dynamics, root architecture, wood biomass and soil properties of geoxyle grasslands, c) to study the role of functional traits (PFTs) of geoxyles in pairwise comparisons with closely related tree species, and d) to see if the functional traits (PFTs) of certain phylogenetic groups differ and can help us explain the dominance of detarioid Fabaceae in miombo ecosystems.
Chapter 1 provides a general introduction to miombo ecosystems and to geoxyle grasslands.
An overview of the ecosystems dominated by geoxyles in Angola, information on their early scientific exploration, their distribution, biodiversity and endemisms is given in the first essay of my dissertation (Chapter 2). Based on our observations and data as well as the existing literature, I provide the reader with detailed information on the importance of geoxyle grasslands and emphasize the need to protect these special ecosystems, which have been scientifically largely unexplored so far. Together with my co-authors, I have identified the human activities that threaten these ecosystems, in particular intensive agricultural development in these areas.
A striking feature of geoxyle species is the weak development of their above-ground shoots and the comparatively very strong development of woody rhizomes, roots and tubers in the soil. This woody network of subterranean woody shoot axes and storage organs forms the main pool of biomass and carbon stocks of the geoxyle grassland ecosystems, which so far have not yet been considered in carbon balances of miombo ecosystems. To get an idea of its carbon stocks, I measured the belowground biomass pool in my second paper (Chapter 3) and described the structure of the subterranean woody organs of six dominant geoxyle species (three for each of the two soil types occurring in my study area). I selected Brachystegia russelliae, Cryptosepalum exfoliatum ssp. suffruticans and Syzygium guineense ssp. huillense from ferralitic areas and Parinari capensis, Pygmaeothamnus zeyheri and Ochna arenaria from sandy sites. I calculated and discussed the subterranean biomass and the corresponding carbon stock, whose magnitude is comparable to dry tropical forests. Both, biomass and the disturbance regime by fire differ greatly between the two geoxyle vegetation types.
Another important feature of geoxyle grasslands is the existence of phylogeneticaly related tree or shrub species for each geoxyle species. My third paper describes and discusses the differences in PFTs of six of these congeneric pairs (geoxyles versus trees) in the Chitembo study area (Chapter 4). Together with my co-authors, I measured and compared specific leaf area (SLA), leaf thickness (LT), wood density (WD), leaf contents of nitrogen (LN), carbon (LC), phosphorus (LP), potassium (LK), calcium (LCa) and magnesium (LMg) as well as leaf dry matter content (LDMC). Additionally, we measured the leaf water potential (WP) of the compared pairs during the dry and rainy season. These traits are known to show responses to a wide range of environmental factors and a close association with ecophysiological mechanisms. The results of this study suggest that differences in functional characteristics of geoxyles and trees are adaptations to the specific environmental stresses of their respective habitats.
In my fourth paper (Chapter 5) I measure and compare the functional traits (PFTs) of an extended set of geoxyle and tree species which occur frequently in my study area. For this purpose the database was extended to twelve geoxyles and fourteen trees. To investigate the different adaptations with which these species cope with the environmental conditions of their habitat, I analysed and discussed differences in PFTs between phylogenetic groups and symbiotic strategy types (Fabaceae versus non-Fabaceae; Ectomycorrhiza associated versus non-mycorrhizal species). The results clearly show ecophysiological and symbiotic adaptations that developed in certain phylogenetic lines during evolution, enabling them to successfully cope with extreme habitat conditions. The general dominance of detarioid Fabaceae on the nutrient-poor soils of the miombo belt seems to be strongly influenced by their ectomycorrhiza association and thus superior phosphorus uptake capacity. Studies from comparable ecosystems of the miombo ecoregion would be required to support this hypothesis.
Finally, I summarise and discuss the most important results of my four papers in a synthesis chapter (Chapter 6)
- …
