1,720,967 research outputs found
The diversity and dynamics of indigenous yeast communities in grape must from vineyards employing different agronomic practices and their influence on wine fermentation
Get PDFCITATION: Bagheri, B., Bauer, F. F. & Setati, M. E. 2015. The diversity and dynamics of indigenous yeast communities in grape must from vineyards employing different agronomic practices and their influence on wine fermentation. South African Journal for Enology and Viticulture, 36(2):243-251, doi:10.21548/36-2-957.The original publication is available at http://www.journals.ac.za/index.php/sajevThe current study evaluated the diversity of yeast species in Cabernet Sauvignon grape must derived from three neighbouring vineyards from a similar terroir but on which significantly different management practices are employed. The fermentation kinetics and yeast population dynamics were monitored from the beginning to the end of spontaneous fermentation. The grape musts were characterised by distinct yeast populations comprising oxidative, weakly fermentative and strongly fermentative yeasts. Different combinations of dominant non-Saccharomyces yeasts were observed in each must, with significantly different assortments of dominant species, including Starmerella bacillaris (synonym Candida zemplinina), Lachancea thermotolerans, Hanseniaspora uvarum, Candida parapsilosis and Wickerhamomyces anomalus. None of these yeast consortia appeared to affect the growth of Saccharomyces cerevisiae or inhibit the overall progress of fermentation. However, the percentage of fermentative yeasts was positively correlated with the fermentation rate. Glucose and fructose consumption rates suggested active participation of both glucophilic and fructophilic yeasts from the onset of fermentation. The data highlight two parameters, viz. initial cell concentration and yeast community composition, as important fermentation drivers and open the possibility to predict fermentation behaviour based on the initial composition of the yeast community.http://www.journals.ac.za/index.php/sajev/article/view/957Publisher's versio
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
Non-saccharomyces killer toxins : possible biocontrol agents against brettanomyces in wine?
Get PDFCITATION: Mehlomakulu, N. N., Setati, M. E. & Divol, B. 2015. Non-saccharomyces killer toxins : possible biocontrol agents against brettanomyces in wine?. South African Journal for Enology and Viticulture, 36(1):94-104, doi:10.21548/36-1-939.The original publication is available at http://www.journals.ac.za/index.php/sajevRed wine spoiled by the yeast Brettanomyces bruxellensis is characterised by off-odours commonly
described as horse sweat, phenolic, varnish and band-aid. The growth of this yeast in wine is traditionally
controlled by the use of sulphur dioxide (SO2). However, the concentration of SO2, the pH of the wine,
the presence of SO2-binding chemical compounds in the wine, as well as the strain of B. bruxellensis,
determine the effectiveness of SO2. Other chemical preservatives have been tested, but are not much more
efficient than SO2, and methods used to clean barrels are only partially effective. Filtration of wine and
the use of electric currents/fields are also reported to alter the physical and sensory properties of wine. In
this context, alternative methods are currently sought to achieve full control of this yeast in wine. Killer
toxins have recently been proposed to fulfil this purpose. They are antimicrobial compounds secreted
by Saccharomyces and non-Saccharomyces yeasts, displaying killer activity against other yeasts and
filamentous fungi. They are believed to play a role in yeast population dynamics, and this killer phenotype
potentially could be exploited to inhibit the growth of undesired microorganisms within a microbial
ecosystem such as that occurring in wine. In this review, non-Saccharomyces killer toxins are described
and their potential application in inhibiting B. bruxellensis in wine is discussed in comparison to other
tried methods and techniques.http://www.journals.ac.za/index.php/sajev/article/view/939Publisher's versio
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
The production, purification and characterization of endo-1,4-ß-mannanase from newly isolated strains from Scopulariopsis candida
No full textEnglish: Mannan polysaccharides occur in hemicellulose fraction of the plant cell walls. The hydrolysis of these polymers involves the action of enzymes such as β-mannanase, β-mannosidase and α- galactosidase which are produced by both fungi and bacteria. The current study reports on the production of β-mannanase, β-mannosidase and α-galactosidase by newly isolated Scopulariopsis candida strains LMK004 and LMK008. The effect of medium composition and carbon source on growth and enzyme production was evaluated in a liquid culture. A combination of Vogel’s medium and locust bean gum was found to stimulate growth and increase β-mannanase production. Optimal β-mannanase production of 7800 nkat/g biomass for LMK004 and 13300 nkat/g biomass for LMK008 was achieved in media containing 10% NaCl, 1X Vogel’s medium, 1% yeast extract and 1% locust bean gum. Both strains secreted trace amounts (less than 1 nkat/ml) of β-mannosidase and α-galactosidase indicating that these enzymes may be retained intracellularly. Native-PAGE and SDS-PAGE were used together with the zymogram to assess purity and to estimate the molecular weight of the proteins. The molecular weight of LMK004 β-mannanase was estimated to be ≈41 kDa whereas that of LMK008 β-mannanase could not be determined due to excessive loss of protein material during dialysis. The β-mannanase from LMK004 was most active at pH 5 and 50 °C, and retained ≥ 80% of its activity at pH 5 – 6.5 after 24 hrs of incubation at 4 °C. In contrast, the LMK008 β- mannanase retained ≥ 60% activity between pH 6 – 7. Both enzymes remained stable for 3 hrs at temperature between 30 °C and 40 °C, and showed loss of activity at higher temperatures. The two enzymes displayed different degrees of halotolerance. The LMK008 β-mannanase tolerated high NaCl concentrations with 60% activity remaining after incubation for 2 hrs at 20% NaCl, whereas the LMK004 β-mannanase was only active between 0% - 10% NaCl. It is clear from the current study that the two strains of S. candida produce distinct β-mannanases which may be useful candidates in low water activity reactions.Afrikaans: Mannaanpolisakkariede kom voor in die hemisellulose fraksie van plantselwande. Ensieme soos
β-mannanase, β-mannosidase en α-galaktosidase, geproduseer deur beide fungi en bakterië, is
betrokke by die hidrolise van hierdie polimere. Hierdie studie handel oor die produksie van β-
mannanase, β-mannosidase en α-galaktosidase deur nuwe isolate van Scopulariopsis candida,
stamme LMK004 en LMK008. Die invloed van mediumsamestelling en koolstofbron op groei
en ensiemproduksie is geëvalueer in n vloeibare kultuur. Daar is gevind dat ‘n kombinasie van
Vogel se medium en locust bean gum groei stimuleer en produksie van β-mannanase verhoog.
Optimale b-mannanase produksie van 7800 nkat/g biomassa vir LMK004 en 13300 nkat/g
biomassa vir LMK008 is verkry in media bestaande uit 10% NaCl, 1X Vogel se medium, 1%
gisekstrak en 1% locust bean gum. Beide stamme het spoorhoeveelhede (minder as 1 nkat/ml) β-
mannosidase en α-galaktosidase uitgeskei, wat daarop mag dui dat hierdie ensieme intrasellulêr
behou word. “Native”-PAGE en SDS-PAGE is saam met zymogram gebruik om die suiwerheid
en molekulêre massas van die proteïene te bepaal. Die molekulêre massa van die LMK004 β-
mannanase is ≈41 kDa terwyl dié van die LMK008 β-mannanase nie bepaal kon word nie van
weë n uitermatige verlies van proteïen gedurende dialise. Die LMK004 β-mannanase was mees
aktief by pH 5 en 50 oC en het ≥ 80% aktiwiteit behou by pH 5 – 6.5 na 24 uur inkubasie by 4
oC. Inteenstelling daarmee, het die LMK008 β-mannanase ≥ 60% aktiwiteit behou by pH 6 - 7.
Beide ensieme was stabiel vir 3 ure by temperature tussen 30 oC en 40 oC en het n verlies aan
aktiwiteit getoon by hoer temperature. Die twee ensieme het verskilende grade van
halotoleransie getoon. Die LMK008 β-mannanase kon hoer NaCl konsentrasies verduur met
60% aktiwiteit na inkubasie vir 2 ure by 20% NaCl, waa die LMK004 β-mannanase slegs aktief
was tussen 0% - 10% NaCl. Uit hierdie studie blyk dit duidelik dat die twee stamme van S.
candida erskillende β-mannanases produseer wat nuttig mag wees in reaksies by lae
wateraktiwiteite.National Research Foundation (NRF
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