1,720,985 research outputs found
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
Assessment of GIS-interpolation techniques for groundwater evaluation : a case study of the Sandveld, Western Cape, South Africa
Full text linkThesis (MSc)--University of Stellenbosch, 2004ENGLISH ABSTRACT: The Sandveld, a potato growing area of the Western Cape is subject to significant
groundwater abstraction for both municipal and agriculture purposes. The climate is arid and
sensitive and important ecosystems in the area are showing varying degrees of impact.
Management measures are needed to ensure ongoing sustainable development of the area.
In this study, different interpolation techniques were evaluated to calculate values for
unsampled variables rainfall and groundwater elevation. Local deterministic techniques as
well as geostatistical techniques were used. It was found that geostatistical techniques,
especially with collateral information, such as topography, provided a more accurate result.
For environmental studies of this nature, Kriging is recommended as interpolation technique.
The underlying data will determine the selection of the particular type of Kriging.
Data was extracted from a customized relational database, geoMon, used for data capture,
retrieval, processing and reporting. Ease of data extraction facilitated analysis.
The interpolated grids were applied in two scenarios: Recharge calculations and quantification
as well as a new classification approach according to Resource Directed Measures (RDM).
Management classes were defined based on GIS-derived data.AFRIKAANSE OPSOMMING: Die Sandveld, ‘n aartappelverbouingsgebied in die Wes-Kaap, ondergaan aansienlike
grondwateronttrekking vir beide munisipale sowel as landbou doeleindes. Die klimaat is dor
en droog en sensitiewe en belangrike ekosisteme in die area ondervind wisselende
impakvlakke. Bestuursmaatreëls word benodig om volhoubare ontwikkeling van die area te
verseker.
In hierdie studie is verskillende interpolasie tegnieke om onbekende waardes vir veranderlikes
gebruik in grondwater evaluasie te bereken, evalueer. Lokale deterministiese tegnieke sowel
as geostatistiese tegnieke is gebruik. Geostatistiese tegnieke, veral gebruik saam met
addisionele inligting soos topografie, bereken meer akkurate resultate. Vir omgewingsstudies
van hierdie aard, word Kriging aanbeveel as interpolasie tegniek. Eienskappe van die
onderliggende data word gebruik om die tipe Kriging aan te dui.
Data is onttrek uit ‘n gebruikersaangepaste databasis, geoMon, wat gebruik is vir
datavaslegging, onttrekking, prosessering en verslaggewing. Die gemak waarmee data
onttrek kon word het analise vergemaklik.
Geïnterpoleerde data is gebruik vir grondwateraanvullingsberekeninge en -kwantifisering
sowel as ‘n nuwe benadering tot klassifikasie volgens hulpbron gerigte maatreëls.
Bestuursklasse gebaseer op GIS-afgeleide data, is gedefinieer
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Towards land change management using ecosystem dynamics and land cover change in rural Eastern Cape
Full text linkThesis (PhD)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Land cover change, triggered by natural and anthropogenic land use change, affects ecosystem services provided by grasslands. Woody encroachment into the grasslands is a threat to function and productivity of rangelands, and threaten rural livelihoods, intensified by rising CO2 levels associated with climate change. Processes of change can only effectively be identified after spatial land transition has been revealed and patterns of change quantified. Accurately quantifying the rates and extent of land cover change is the first step in relating underlying land use processes and the environmental effects thereof to land cover change trajectories involving grassland transformation.
The study aims to demonstrate how land cover change, in particular woody encroachment influences landscape functions provided by grasslands in the Eastern Cape. The study seeks to determine how accurately land cover transformation can be quantified and modelled using existing datasets that may contain map error and raises the question how the error pattern can affect modelling of future evapotranspiration and carbon storage. A further question is how the drivers of change vary between regions under different land tenure, i.e. dualistic or commercial systems.
Systematic land cover change analysis and future land change modelling were used to characterise land cover change trajectories and flows in the landscape. Flows were described using (1) an indicator-based approach, and (2) intensity analysis and change budget. Hypothetical map error was determined for observed and modelled land cover maps. Overall change was partitioned into quantity, exchange and shift disagreement and intensity. The change budget was computed both at catchment and local level. Map error was further investigated using a local geographically weighted method. Local geographically weighted correspondence matrices were constructed to determine spatially explicit probabilities of change and error at catchment level and per land cover class. By consulting the overall allocation difference maps, hotspots of change and probable error were identified for further investigation. Trends in remote sensing-derived biophysical variables were analysed to determine how land cover change would affect the surface energy budget and the carbon cycle, as proxies for water use and rangeland productivity.
Primary drivers of landscape modification comprised rangeland degradation, woody encroachment, urbanisation, increased dryland cultivation and commercial afforestation, with the latter concentrated in the commercial catchment. Though grassland persistence still dominated land cover in the landscape, catchments under dualistic land tenure experienced
steeper declines in the grassland area. Woody encroachment was also found predominantly in these catchments.
Overall accuracy for the input land cover maps were reported as >80%, equating to theoretical land cover change accuracy of 67–72%. Landscape change varied between 18% and 42%, with 19% estimated from direct overlay of land cover maps with 30 m resolution pixels. By applying a multi-resolution aggregation technique, the study showed that lower resolution input data would identify less change in the landscape, mainly because the allocation error diminishes at lower resolutions. For higher change accuracies and reliability, the accuracy of input land cover maps would have to be increased.
Hypothetical map error in observed land cover change maps were found to be higher in catchments under dualistic tenure for gaining transitions, whereas losing transitions showed higher error in catchments practicing commercial farming. The hypothetical error accounted for almost 50% of the reported change. The modelled land cover change showed higher allocation disagreement, suggesting that the land change model was not very reliable, particularly for the commercial catchment.
Analysis of remotely sensed data products such as albedo, net primary production and evapotranspiration, in combination with land cover change data has led to better understanding of the landscape of the catchments. Though grasslands are predicted to decrease in favour of woody invasive plant species and cultivated land, this study predicted a decrease of 12% and 6% respectively in net carbon storage and water use by vegetation. Information from multiple sources, in both quality and type, were integrated to better understand rangeland productivity degradation and to compare the impact of climate versus land management in the different catchments. Quantifying changes in biophysical parameters can assist scientists and managers in addressing global challenges.AFRIKAANSE OPSOMMING: Verandering in grondbedekking wat deur natuurlike en antropogeniese verandering in grondgebruik veroorsaak word, beïnvloed die ekostelseldienste wat deur grasvelde gelewer word. Houtagtige indringing van die grasvelde is ʼn bedreiging vir die funksionering en produktiwiteit van weivelde en bedreig landelike lewensbestaan. Hierdie proses word aangehelp deur die toenemende CO2-vlakke wat met klimaatsverandering verband hou.
Prosesse van verandering kan eers effektief geïdentifiseer word nadat ruimtelike landoorgang geopenbaar is en patrone van verandering gekwantifiseer is. Die akkurate kwantifisering van die trajek en omvang van grondbedekkingsverandering is die eerste stap om die onderliggende prosesse vir grondgebruik en die omgewingseffekte daarvan aan grondbedekkingstrajeksies te koppel. Laasgenoemde hou direkte verband met die transformasie van grasveld.
Hierdie studie het ten doel om te demonstreer hoe grondbedekkingsverandering, veral deur houtagtige indringerplante, die landskapfunksies wat grasvelde in die Oos-Kaap verrig beïnvloed. Die studie poog om te bepaal hoe akkuraat die transformasie van grondbedekking met bestaande datastelle, wat kaartfoute bevat, gekwantifiseer en gemodeller kan word. Daar is onsekerheid oor hoe die foutpatrone in die datastelle die modellering van toekomstige evapotranspirasie en koolstofopberging kan beïnvloed. 'n Verdere navorsingsvraag is hoe die drywers van verandering tussen streke onder verskillende grondbesit, te wete dualistiese of kommersiële stelsels, wissel.
Sistematiese ontleding van grondbedekking en toekomstige modellering is gebruik om die trajek en vloei van grondverandering in die landskap te beskryf. Vloei is beskryf met behulp van (1) 'n aanwyser-gebaseerde benadering, en (2) intensiteitsanalise en veranderingsbegroting. Hipotetiese kaartfoute is vir waargenome en gemodelleerde grondbedekkingskaarte bepaal. Algehele verandering is in kwantiteit, wissel en verskuiwingsverskille en intensiteit opgedeel. Die veranderingsbegroting is per opvanggebied sowel as op plaaslike vlak bereken. Kaartfoute is verder met behulp van 'n plaaslike geografies-geweegde metode ondersoek. Plaaslike geografies-geweegde korrespondensie-matrikse is opgestel om ruimtelik-sensitiewe waarskynlikhede vir veranderinge en foute per opvanggebied en grondbedekkingklas te bepaal. Die totale toekenningsverskilkaarte is geraadpleeg om brandpunte van verandering en waarskynlike foute vir verdere ondersoek te identifiseer. Die tendense in biofisiese veranderlikes wat vanaf afstandswaarneming afgely is, is ontleed om te bepaal hoe verandering in grondbedekking die oppervlakte-energiebegroting en die koolstofsiklus, wat watergebruik en graslandproduktiwiteit verteenwoordig, sou beïnvloed.
Die resultate het getoon dat weiveldagteruitgang, houtagtige indringing, verstedeliking, verhoogde droëlandverbouing en kommersiële bosbou, met laasgenoemde gekonsentreer in die kommersiële opvanggebied, die primêre drywers van grondbedekkingsverandering was. Alhoewel grasland grondbedekking die landskap steeds oorheers, het dit in opvanggebiede onder dualistiese grondbesit afgeneem. Houtagtige indringing is hoofsaaklik in hierdie opvanggebiede opgemerk.
Die algehele akkuraatheid van die inset grondbedekkingskaarte is as >80% gerapporteer, wat teoreties in die konteks van grondbedekkingverandering aan 67-72% gelykstaande is. Landskapverandering het tussen 18% en 42% gewissel, met 19% wat op direkte oorleg van 30 m resolusie grondbedekkingskaarte geraam is. 'n Multi-resolusie-samevoegingstegniek het getoon dat laer resolusie-insetdata minder verandering in die landskap identifiseer, hoofsaaklik omdat die toewysingsfout by laer resolusies verminder. Die akkuraatheid van grondbedekkingskaarte sal verhoog moet word om die akkuraatheid en betroubaarheid van veranderinge te verbeter.
Daar is bevind dat hipotetiese kaartfoute in waargenome grondebedekkingsveranderingskaarte hoër was in opvanggebiede onder dualistiese bestuur vir grondbedekkingsklasse wat toegeneem het, terwyl in die kommersiële opgevanggebied groter foute in grondbedekkingsklasse met afnemende oorgange opgetel is. Die hipotetiese fout was verantwoordelik vir byna 50% van die gemelde verandering. Die gemodelleerde gronddekkingverandering het 'n groter toewysigingsverskil getoon, wat daarop dui dat die grondbedekkingsveranderingsmodel nie baie betroubaar was nie, veral nie vir die kommersiële opvanggebied nie.
Analise van afstandswaarnemingsdataprodukte soos albedo, netto primêre produksie en evapotranspirasie, in kombinasie met grondbedekkingsveranderingsdata, het gelei tot 'n beter begrip van die landskap in die opvanggebiede. Alhoewel die voorspelling is dat grasvelde ten gunste van houtagtige indringerplantspesies en bewerkte lande sal afneem, het hierdie studie slegs 'n afname van onderskeidelik 12% en 6% in die netto koolstofopberging en watergebruik deur plantegroei voorspel. Inligting uit verskeie bronne, beide in kwaliteit en tipe, is geïntegreer om die agteruitgang van die landskapproduktiwiteit beter te verstaan en om die impak van klimaat op grondbestuur in die verskillende opvanggebiede te vergelyk. Die kwantifisering van veranderinge in biofisiese parameters kan wetenskaplikes en bestuurders help om wêreldwye uitdagings die hoof te bied.Doctora
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