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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
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
'n Ondersoek na die invloed van 8-hidroksikinoliensulfaat en n-6-bensielaminopurien op enkele aspekte van veroudering by angelierblomme
Get PDFMSc, North-West University, Potchefstroom CampusThe effect of N-6-benzylaminopurine (BAP), 8-hydroxyquinoline
sulphate (HQS) and a BAP/HQS mixture on the display life and
external appearance of cut carnation flowers (Dianthus caryophyl
lus L. cultivar White Sim) was investigated. The effect of
these substances on changes in water content, rate of respiration,
total free amino acid content and concentration of the individual free amino acids in senescing petal tissue was examined as
well. The rate of 14co2 production from a-alanine-u- 14c solution applied in presence of the preservatives, during incubation
of petal and receptacle tissue, was determined. This was done
to elucidate the effect of these preservatives on amino acid
breakdown.
Both BAP and HQS prolong the display life and have a beneficial
effect on the appearance of the flowers. A higher water content
is maintained in the petals, especially during the climacteric
and post climacteric stages. The most efficient preservative
is the BAP/HQS mixture.
There are no noticeable changes in the pattern of respiration
and the duration of the preclimacteric period in presence of
the preservatives. The average rate of respiration in petals of
BAP treated flowers is lower than that of untreated flowers.
In the post climacteric stage, however, the rate of respiration
in petals of BAP treated flowers exceeds that of untreated flowers. HQS as well as the BAP/HQS mixture increases the rate
of respiration in the climacteric and post climacteric stages.
All treatments result in the increase of the total amino acid
level although to a lesser extent than in the petals of untreated
flowers. The effect of the preservatives becomes more prominent
in the post climacteric stage. BAP and the BAP/HQS mixture are
more effective than HQS in decreasing the total free amino acid
content.
The concentration of free threonine, serine, asparagine, glutamine, a-alanine, praline, glycine, methionine, phenylalanine,
y-amino butyric acid and histidine are lower in petals of treated
flowers than in the petals of control flowers. The differences
in the concentration of these free amino acids are more pronounced in the post climacteric stage. The preservatives have little
effect on the concentration of free aspartic acid, glutamic acid
and lycine. They also inhibit the characteristic increase in
the concentration of free praline and methionine as senescence
progresses. HQS retards the decrease in water content and prevents the accumulation of praline, glutamine and asparagine under water stress conditions. The reduction of amino acid levels
by the application of BAP is probably caused by the stimulation
of protein synthesis and inhibition of proteolysis.
The rate at which 14 co2 is produced from a-alanine-u- 14c in petal
tissue is higher than in receptacle tissue. However, the preservatives decrease the rate of 14co2 production determined over a
period of 24 hours. BAP seems to have a greater effect than
HQS.
The BAP/HQS mixture is the most effective of these preservatives
in prolonging display life of cut carnation flowers by maintaining
the moisture content of the petals and retarding protein and amino
acid breakdown.Master
Fluoorasetaat-, aminosuur- en organiese suurmetabolisme van gifblaar (Dichapetalum cymosum Engl.)
Get PDFDSc, North-West University, Potchefstroom CampusIt has been shown by means of respiration stu,dies that Gifblaar is
capable of metabolizing FAc. A method was worked out for the synthesis of
FAc-2- 14C from MeBrAc-2- 14C w1tp. a yield of 65%. When FAc-2- 14C was
applied to Gifblaar leaves it was found that one of the first radioactive components was an unknown carbohydrate. Indications were found that Grysappel
(Parinarium capense), a control plant, also metabolizes FAc-2-14c to a small
extent.
The application of fluorocitrate ( FC) was shown to inhibit the respiration of Gifblaar and lead to an accumulation of citrate. This indicates that
FAc is not metabolized via FC and that Gifblaar contains an active Krebs
cycle. The latter was confirmed in experiments with radioactive pyruvate,
citrate, acetate, alanine, serine and glycine.
It was found that Gifblaar has a relatively high free amino acid concentration and that the two amino acids present in the highest concentration
are not commonly encountered in other organisms. These two amino acids
represented more than 30% of the total nitrogen present in the tip of the
rhizome.
The two amino acids were isolated and with the aid of elementary
analysis, mass spectrometry, nuclear magnetic resonance spectrometry
and infrared spectroscopy they were characterized as N-methyl-L-alanine
(NMA) and N-methyl-L-serine (NMS) respectively. These amino acids have
not yet been encountered in other plants, as far as is known.
It was found that a high NMA and NMS concentration Usually went hand
in hand with a high FAc concentration. Furthermore these amino acids were
not poisonous to mice and it was established that they are formed in vivo by
methylation of alanine and serine.Doctora
'n Vergelykende studie van die mineraalsamestelling van Pachystigma pygmaeum [Schltr.] Robyns en 'n aantal geassosieerde plantspesies van die klipveld
Get PDFMSc, North-West University, Potchefstroom Campus"Abstract not copied"Master
Die organiese voeding van drie algsoorte van die Belmontrivier naby Grahamstad
Get PDFDSc, North-West University, Potchefstroom CampusThe diatom Achnanthes pseudohungarica is capable of
utilizing urea and a large number of amino acids as its
only sources of nitrogen. This. diatom can also assimilate
and utilize urea and a large number of amino acids and
sugars as its only sources of carbon. None of these substances
could, however, support the growth of this organism
in the dark, or stimulate its growth under conditions where
light was a limiting factor.
Although acetate, glutamic acid and phenylalanine were
found to be assimilated by the diatom Nitzschia palea in the
dark, and to stimulate the growth of this organism under
conditions where light was a limiting factor, nevertheless
none of these substances could support the growth of this
organism in the dark.
Various attempts were made to determine the cause of the
obligate phototrophy in Nitzschia palea and Achnanthes pseudo-
hungarica by comparing various aspects of the metabolism of
these organisms with that of a Scenedesmus-specie, which is
capable of heterotrophic growth.
There seems to be no significant synthesis of new cellular
material in Nitzschia palea in the absence of photosynthesis
and in the simultaneous presence of organic substrates. This
is reflected by the fact that cells which have been kept in
the dark for more than a week assimilated organic substrates
as oil drops which would normally constitute the reserve material
of this organism. For the inability of Achnanthes
pseudohungarica to grow in the dark in the simultaneous presence
of organic substrates which, moreover, it can assimilate , no
other explanation can be given than that light is required for
its growth.
Nitzschia palea grew equally well in the presence of
organic substrates and in an inorganic culture solution
where ample co was supplied. This suggests that the ;a
presence of this organism in sewage-polluted water is not
only the result of its ability to utilize organic substrates
as sources of nitrogenp carbon and energy, but
also that its ability to grow actively under these conditions
is equally important.
The importance of Achnanthes pseudohungarica in the
purification of sewage-polluted water is reflected by the
ability of this organism to oxidize a large number of
organic substrates.Doctora
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