1,720,972 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
Assessment of seasonal variations of teal carbon in palustrine wetlands of the grassland biome : a case study of Chrissiesmeer, Mpumalanga Lakes District, Mpumalanga Province, South Africa
Get PDFDissertation (MSc (Geoinformatics))--University of Pretoria, 2023.Wetlands are recognised as the important natural ecosystems in the world. The above-ground
biomass (AGB) of wetland vegetation is essential for providing ecosystem services related to
global climate change due to its crucial role in sequestrating anthropogenic carbon emissions.
Seasonal AGB estimation could help to understand carbon changes in wetlands and how
vegetation in these ecosystems differs across seasons at regional scales. Remote sensing
technology offers time-effective and cost-efficient ways to improve the monitoring of wetlands
and understanding of the spatial carbon changes in wetland vegetation. This study aimed to use
seasonal derived AGB of palustrine herbaceous vegetation to determine the differences in teal
carbon, using active and passive remote sensing data across the summer and winter seasons. The
study was carried out in the Chrissiesmeer catchment in the temperate Grassland Biome of the
Mpumalanga Province of South Africa. The objectives were to (1) derive different season-specific
modelling scenarios from Sentinel-1 and Sentinel-2 imagery to assess the optimal model for
estimating AGB of palustrine wetland vegetation AGB, (2) assess the performance of Random
Forest (RF) and Support Vector Regression (SVR) in predicting seasonal AGB of wetland
vegetation, (3) map the seasonal spatial patterns of teal carbon from the estimated AGB of
wetland vegetation, and (4) assess the seasonal variation in the predicted teal carbon. RF and
SVR algorithms were used as regression-based algorithms with important variable selection to
develop an optimal model from the modelling scenarios, which also incorporated field-measured
Leaf Area Index (LAI). The results showed that the combination of Sentinel-1 GLCMs and
backscatter channels yielded higher accuracy for the estimation of the AGB of palustrine
herbaceous vegetation attaining coefficient of determination (R2
) = 0.735, root mean squared
error (RMSE) = 39.848 g·m-2
, and relative RMSE (relRMSE) = 17.286% compared to a combination
of reflectance bands, vegetation indices and red-edge bands (R2
= 0.753, RMSE = 49.268 g·m-2
,
and relRMSE = 20.009%) in the summer season. For the estimation of AGB in the winter season,
Sentinel-1-derived GLCMS textures obtained higher accuracy (R2 = 0.785, RMSE = 67.582 g·m-2
,
and relRMSE = 20.885%) compared to the combination of reflectance bands, vegetation indices
and red-edge bands of optical data (R2 = 0.749, RMSE= 69.634 g·m-2 and relRMSE = 21.248%).
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These findings suggested that Sentinel-1 sensor-derived models performed better than the
optical models in both seasons. Furthermore, the addition of SAR textural measurements
improved the accuracy of modelling AGB and RF model performed better than SVR in estimating
the AGB of wetland vegetation. The study observed that there was a significant difference
between the summer (77.527 g C/m-2 DM) and winter (57.918 g C/m-2 DM) seasonal mean carbon
ranges (p < 0.05), and Tevredenpan wetland vegetation communities stored higher levels of
carbon in the AGB vegetation in summer than in winter. The study showed that vegetation of
palustrine wetlands is significant for carbon storage and fluctuates significantly between summer
and winter. Estimating carbon stock in the AGB vegetation can aid in conserving grasslands and
wetlands and notably optimise research on biomass estimation with remote sensing and machine
learning systems.SANSA, WRC, CSIRGeography, Geoinformatics and MeteorologyMSc (Geoinformatics)Unrestricte
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
Using geographical information systems for mapping commercial farmers' perceptions on land reform in Mpumalanga, RSA
Get PDFThesis (MA)--Stellenbosch University, 2000.ENGLISH ABSTRACT: Traditional top-down decision-making models have become unpopular since public
institutions have been demanding more democracy at local level. New approaches and
techniques have focused on how the majority of people can be involved in a bottom-up
approach to development and decision making. Techniques, such as Participatory Rural
Appraisals (PRAs), have identified people's concerns regarding the use of natural
resources centred on land issues. Land is essentially a subject of public concern. Land as
a spatial phenomenon controlled politically and used by all for survival and other purposes
needs to be assessed in an integrated and time-spatial way for better planning and
decision making.
Geographical Information Systems (GISs) have often been used by statutory "experts" in
evaluating, analysing and mapping of land and land-related features. GISs have a lot of
potential in being applied as decision-making tools. If this is the case, how can public
perceptions and politics be presented and mapped in a GIS to improve and democratise
decision making even further? The study has investigated new methods of representing
people's perspectives at grassroots level in a non-traditional way.
A sub-region of the Lowveld, situated in the Mpumalanga province, has been selected
because of the various kinds of land owners in the region. The Kruger National Park lies to
the east of the study area, from where some black communities claim to have been
removed. To the west of that is one of the districts of the former homeland KaNgwane,
namely Nsikazi, and west of that two areas of intensive large-scale commercial fruit and
vegetable production in the Nelspruit-White River and Kiepersol-Hazyview areas. Towards
the escarpment north-west of these lie large commercial exotic forest plantations, owned
mainly by Safcol and MandL Given the high demand and need for land from the overpopulated
Nsikazi district, the process of land reform is a matter of great concern.
White male commercial farmers in both regions where commercial farming is active were
interviewed about their knowledge and perceptions of land reform. Various themes were
presented to the farmers to comment on, namely the history of forced removals, land use,
land potential, hydrology and where land reform should take place. Interviews were taped
in Afrikaans, transcribed and translated to English. "Mental maps" were drawn on tracing paper overlaid on topographical maps of the Land Surveyor General, Mowbray. These
were digitised and managed in Arclnfo, and displayed and analysed in ArcView, from
where output maps were produced.
The results of this technique proved to be very useful and can certainly broaden the use of
GISs in decision making and public participation. However, GISs alone cannot be seen as
the solution to better development and better decision-making. Public participation is of the
utmost value in facilitating and initiating these processes. Land use planning needs to be
the responsibility and concern of all land users and owners at a local level, where GISs
can be applied as a tool to provide easier and more effective analysis and results for the
implementation of initiatives.AFRIKAANSE OPSOMMING: Tradisionele bo-na-onder besluitnemingsmodelle het in die laaste paar dekades baie
ongewild geraak met die totstandkoming van instellings wat die publiek se mening hoog ag
en demokrasie op grondvlak probeer bevorder. Nuwe benaderings en tegnieke poog nou
om die publiek se mening in 'n onder-na-bo benadering tot ontwikkeling en besluitneming
te integreer. Grondhervorming is basies die erns van die publiek, meer so as die staat.
Grond is 'n ruimtelike verskynsel wat polities beheer word maar deur die meerderheid
gebruik word vir oorlewing asook ander doeleindes. Dit behoort op 'n tyd-ruimtelike basis
op 'n geïntegreerde wyse vir beter beplanning en besluitneming ondersoek te word.
Geografiese Inligtingstelsels (GISs) word hoofsaaklik deur statutêre "kenners" gebruik in
die evaluering, analise en kartering van grond en verbandhoudende verskynsels. Dit
beskik verder oor die potensiaal om in besluitnemingsprosesse gebruik te word. Die vraag
ontstaan egter hoe die publiek se menings en politieke strukture met 'n GIS
verteenwoordig en gekarteer kan word ter verbetering van besluitneming op 'n meer
demokratiese wyse. Die studie het nuwe metodes ondersoek waarvolgens mense op
grondvlak se persepsies op nie-tradisionele maniere verteenwoordig en ondersoek kan
word.
'n Sub-streek van die Laeveld wat geleë is in die Mpumalanga provinsie, is geselekteer
vanweë die verskeidenheid grondeienaars wat daar voorkom. Die Kruger Nasionale Park
is geleë in die oostelike deel van die studiegebied vanwaar sekere swart gemeenskappe
gedurende die Apartheidsregime verskuif is. Direk wes hiervan lê die voormalige tuisland
KaNgwane se Nsikazi distrik en wes daarvan twee areas, naamlik Nelspruit-Witrivier en
Kiepersol-Hazyview, waar die kommersiële boerdery van vrugte en groente op groot skaal
beoefen word. In die noordwestelike gedeeltes van die studiegebied kom grootskaalse
uitheemse bosbouplantasies voor wat aan Safcol en Mondi behoort. Met die stygende
aanvraag na grond vir residensiële- en landbougebruik in die streek, veral vanuit die
Nsikazi distrik, is grondhervorming en die toepassing daarvan, 'n probleem, indien nie 'n
bedreiging, vir die meeste grondeienaars.
Onderhoude is met blanke manlike kommersiële boere, in albei die kommersiële streke
gevoer om hul menings en kennis van grondhervorming te ondersoek. Verskeie temas is as besprekingspunte gestel, naamlik die geskiedenis van gedwonge verskuiwings,
grondgebruik, grondpotensiaal, water hulpbronne en waar hul meen grondhervorming sou
moes plaasvind. Onderhoude was in Afrikaans opgeneem, getranskribeer en in Engels
vertaal. "Kognitiewe kaarte" was op deursigtige papier geteken wat oor 'n reeks
topografiese kaarte van die gebied gelê is. Die resultate is versyfer en in Arelnfo
gemanipuleer en daarna in ArcView ontleed en vir verslaglewering gekarteer.
Die resultate van die tegniek beloof om vir beide besluitnemers en die publiek as
deelnemers in die proses baie bruikbaar te wees. Dit verbreed ook die gebruik en
toepassing van GISs en die sisteem se vermoëns. GISs kan egter nie alleenlik aangewend
word om ontwikkeling en besluitneming vir die publiek beter of meer aanvaarbaar te maak
nie. Alle mense se deelname is van die uiterste belang en waarde in die inisiëring,
fasilitering en implementering van strategieë en projekte. Grondgebruiksbeplanning moet
die verantwoordelikheid van almal word wat grond op plaaslike vlak gebruik of besit, nie
net van die wat deur 'n probleem of program, soos grondhervorming, geraak word nie. 'n
GIS kan aangewend word om die prosesse van ontwikkeling en besluitneming te
vergemaklik deur analises vinniger en op 'n meer effektiewe manier te ondersoek vir beter
en meer demokratiese besluitneming.Master
Remote sensing of wetland tree species in the iSimangaliso Wetland Park, KwaZulu-Natal, South Africa.
Get PDFDoctor of Science in Geography.The impact of global change is expected to result in changes in the distribution and composition of species. Coastal swamp and mangrove forests are some of the most threatened forest types in the world. Remote sensing is a suitable tool for monitoring species distribution and varying condition because of its spatial extent and repeatability. The ability of remote sensing to separate between species can be attributed primarily to its capability to quantify the absorption features in the electromagnetic spectrum which relate to plant biochemical and biophysical properties such as pigments, nutrients (proteins and starch), leaf water content, leaf angle distribution, leaf area index and foliage biomass. For some species, these phenological variations are extreme, as in the case of deciduous tree species, thus enhancing the ability to differentiate between species, whereas others are less pronounced, such as with evergreen tree species, making spectral distinction between species much more challenging.
Few studies have assessed the pigment and nutrient phenology of evergreen tree species in subtropical forested wetlands, let alone their spectral differences. This study assesses whether multi-season data across a number of phenological phases of evergreen wetland tree species will improve their classification accuracy when compared to a single season and single phenological event. The objectives were to (i) assess whether tree species had unique seasonal profiles of foliar biochemicals; (ii) ascertain the spectral bands of plant properties which remain important across phenological phases for species classification; (iii) determine whether leaf reflectance spectra from multiple seasons would improve species classification when compared to a single season; and (iv) whether multi-season imagery would improve species discrimination when compared to a single season. Thus, the study made use of leaf level and canopy level spectra collected using a handheld spectrometer and spaceborne RapidEye imagery, respectively.
Six dominant evergreen tree species from forested wetlands in the subtropical region of KwaZulu-Natal, South Africa, were sampled across four seasons (winter, spring, summer and autumn). Differences in foliar biochemical concentration were assessed for two pigments, including carotenoids and chlorophylls, as well as two nutrients, nitrogen and phosphorous. The results showed that the majority of species had no significant changes in foliar pigments across the four seasons. Foliar nitrogen showed a significantly higher variability in the spring, summer and autumn seasons compared to the winter, whereas foliar phosphorus also varied across the seasons but to a lesser degree. The highest percentage of species pairs was separable using foliar nitrogen, compared to the pigments and phosphorus, emphasizing the importance of nutrients such as leaf proteins for species discrimination.
The study found a changing relationship between leaf spectra and foliar nutrient concentration across the four seasons for the six evergreen tree species. Twenty-two spectral bands which are related to known absorption features of plant properties were
identified across the four seasons as important for tree species discrimination. The relationship between leaf spectra and foliar nitrogen was highest during the spring, summer and autumn seasons for narrow bands associated with absorption features of proteins compared to the red-edge region. The spectra band combination 2130 nm and 2240 nm yielded the highest coefficient of determination between leaf spectra and foliar nitrogen across three of the four seasons. Season-specific prediction models were found to be more accurate in predicting foliar nitrogen than prediction models from across all seasons. The twenty-two bands were effective for the data reduction of the hyperspectral data and yielded a similar overall accuracy compared to 421 bands.
Multi-seasonal data improved tree species classification for multispectral sensors with a few bands. The classification, in which multi-season leaf spectra or canopy data from RapidEye imagery was used, resulted in higher overall and user’s accuracies when compared to the single-season classifications. In contrast, the use of multi-season data for the classification of leaf spectra with 22 narrow bands, showed no statistical significance of differences compared to the classification results of the single season in which the highest overall accuracy of all single seasons had been obtained. The value of an increased classification accuracy should however be measured against the increase of cost when using images from multiple seasons. The study concludes that although seasonal profiles of foliar biochemicals overlap, multi-season information do improve species discrimination at foliar biochemical, leaf-spectra and canopy-spectra levels
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
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
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