1,720,974 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
Black and White: investigations on the ecology, biology and biological control of sapstain fungi in New Zealand
Get PDFThis study examined ecology, colonisation, biological control and detection of sapstain fungi in New Zealand.
A nationwide survey of New Zealand sapstain fungi was undertaken between 1996 and1998. In total, 1035 sites were sampled in the North and South Islands. From these collections, 1755 potential sapstain fungi were isolated and seventeen individual species were identified. The predominant sapstain fungi identified were Sphaeropsis sapinea,
Ophiostoma ips, O. floccosum, O. piliferum, O. querci and Leptographium procerum. This data was subsequently evaluated according to ecological criteria, including geographical and temporal distribution of sapstain fungi. A greater diversity of sapstain fungi was found in areas of New Zealand that were primarily plantation forestry. S. sapinea was isolated during more generalised forest sampling, and from both native and plantation forests. Ophiostoma species were isolated more frequently from Pinus radiata plantations, processing plants including mills and ports and were mainly isolated from harvested forest material such as logs, wood chips, and other wood products. S. sapinea was isolated more frequently in spring and summer while Ophiostoma species predominated during autumn and winter periods, probably linked with insect vectoring. This was the first attempt to link the sapstain organisms identified in New Zealand with their overall distribution within sectors of the forest industry, in different wood species, and in different types of wood samples.
New Zealand is one of the world's largest exporters of softwood logs. Exports of forest products provide 4% of New Zealand’s gross domestic product (GDP) with Japan, Korea, United States and the Philippines as major export markets for P. radiata logs. Conditions found within the holds of ships were thought likely to be ideal for the rapid colonisation of the sapstain fungi that results in dark penetrating stains. Log export research was designed to determine the extent of sapstain colonisation at specific points in the processing of logs from harvesting to the export destination. Two trials were established, in New Zealand summer and in winter, where mature P. radiata logs were harvested in New Zealand and shipped to export ports in Japan. Microclimatic conditions (temperature and relative humidity) on board the ships were recorded using data loggers both above deck and below deck. Nine species of sapstain fungi were isolated from logs during the summer trial. The most common species isolated were O. floccosum, O. querci and O. setosum. In contrast, a different combination of nine species was detected during the winter trial. S. sapinea, O. querci, O. floccosum, O. setosum and Ophiostoma piceae were most commonly isolated. The results of this study showed that the New Zealand sapstain fungi were being exported on logs. However, many of these fungi were previously recorded in Japan. In addition, no serious pathogens were detected.
It was recognised during the sapstain fungal survey and export trials that a more thorough fundamental understanding of sapstain colonisation was required to properly determine the impacts of sapstain fungi to the New Zealand forest industry. In vitro and field studies were established to measure the relative colonisation of different species of sapstain fungi using synthetic media and P. radiata wood. These studies were undertaken to determine which sapstain species colonised, and how species interacted with each other following inoculation. In addition, the impacts of environmental conditions on the establishment and development of fungi and the resulting associated stains were determined. Temperature was found to affect the growth of various species of sapstain fungi on synthetic media and on P. radiata wood and logs. In the field studies O. floccosum was found to be the most successful coloniser of P. radiata logs in both winter and summer. Environmental factors such as temperature and moisture content were found to affect stain development. All fungal treatments developed sapstain discolouration from 15 days following inoculation in the summer field trial. In contrast, no stain was evident on any treatment in the winter field trial 60 days following inoculation. The colonisation of P. radiata by sapstain fungi was determined using microscopic techniques. Sapstain fungal hyphae were abundantly present in the ray parenchyma cells, tracheid lumen and resin canals of P. radiata wood. No differences in hyphal penetration were observed between the different sapstain fungal species at the cellular level. From these results a better understanding of the biology of sapstain species emerged. This new knowledge of the mechanisms and environmental triggers of fungal colonisation and stain development will aid in the more advanced technologies and management strategies to successfully control sapstain.
The many negative environmental impacts associated with traditional anti-sapstain chemical treatments led to increased interest in the more benign treatments of logs and wood using biological control technologies. The potential biological treatment of sapstain fungi using albino strains of O. floccosum, O. piceae and O. pluriannulatum was evaluated. These albino fungi demonstrated varied growth characteristics at different temperatures on both synthetic media and on P. radiata wood specimens. Comparable growth was found when evaluating wild type and albino sapstain strains in synthetic media and P. radiata wood in laboratory and field studies. Four field trials showed considerable variation in the biological control potential of the albino strains against wild type sapstain fungi. The mode of action of the albino strains was found to be competitive, through the use of primary resource capture of wood nutrients. However, albino O. floccosum strains were shown to produce zonal barriers when challenged with S. sapinea.
Proteomic analysis of cell wall proteins was undertaken to differentiate sapstain fungi from other wood inhabiting fungi and in an attempt to develop a method of determining the presence of sapstain fungi in wood prior to the development of stain. Proteins were extracted from the cell walls of various sapstain fungi (L. procerum, O. ips, O. Querci and S. sapinea) and wood inhabiting fungi (Alternaria alternata, Epicoccum nigrum, Trichoderma koningi) grown in liquid culture. Two dimensional (2D) protein profiles were made and compared. A total of 93 proteins were analysed using mass spectroscopy and the profiles compared to protein databases. This is the first investigation using proteomics of the cell wall proteins of Ophiostoma species and S. sapinea.
This study addressed the importance of sapstain fungi in New Zealand on P. radiata and increased our understanding of ecological requirements of the different sapstain species. Differences between these species with respect to colonisation and the development of associated stains were identified and investigated, enabling a critical evaluation of those species that were found to be most significant to the New Zealand forest industry. The future of sapstain management depends on a thorough ecological understanding of key sapstain fungal species involved in the cosmetic degradation of wood and an ability to manage the impacts of these species on the New Zealand forest industry using a combination of forest management practises and biological and chemical control techniques
Microbial diversity in relation to human activity in historic areas of Ross Dependency, Antarctica
Get PDFThe goal of this study was to undertake a relatively broad microbiological investigation at historic areas of Cape Evans and Ross Island. The two phylogenetically diverse targets were Bacillus anthracis, the causative agent for anthrax disease, and filamentous micro-fungi associated food products. The human activities were presumed to have played a significant contribution to the introduction of non-indigenous Bacillus anthracis and many filamentous micro-fungi at the historic areas on Ross Island.
Bacillus anthracis was suspected to be present at Cape Evans based on a circumstantial clinical analysis of the death of the member in Captain Robert F Scott's Terra Nova Expedition in 1912. Detection methods based on polymerase chain reaction (PCR) targeting B. anthracis specific genes on chromosome and two plasmids were employed. DNA extraction was performed by a bead-beating technique from 74 environmental samples. PCR efficiency was compromised probably due to inhibitors in DNA extracts, but improved with higher concentrations of Taq polymerase. Initially a total of 74 environmental samples were screened with one set of primers before positively tested 19 samples were rigorously investigated with seven sets of primers. Nested PCR also increased the target specificity and detection levels. Sequence analyses of the several positive samples from PCR reactions were characteristic to B. anthracis.
A diverse range of filamentous micro-fungi were isolated on three different media at two different temperatures, 15 °C and 25 °C, and identified by classical morphological taxonomy from the foodstuffs and internal environmental samples of Captain Robert F Scott's historic hut at Hut Point built in 1901. In total, there were 22 taxa and 14 genera recorded including many cosmopolitan species isolated from the samples, in particular Penicillium species. An extensive literature review of the :filamentous micro-fungi found in Antarctica identified that 7 taxa isolated in the study were not reported previously. Many isolates were obtained at 15 °C while some isolates grew in the presence of antibiotics
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
Effect of sapstaining fungi on structural wood integrity of radiata pine (Pinus radiata D. Don)
Get PDFSelected sapstaining fungi belonging to the Ascomycetes and Fungi Imperfecti isolated in New Zealand were evaluated for potential degradation of unseasoned radiata pine sapwood using four independent methods: i) toughness and weight loss measurements, ii) chemical analysis of wood composition, iii) enzyme assays and iv) light and scanning electron microscopy. Several isolates of albino-strains, potential candidates for use as biocontrol agents against sapstain on radiata pine, were included in the experiments.
Sets of side-matched specimens were inoculated with isolates of Ophiostoma floccosum, O. pluriannulatum, O. ips, O. piceae, Leptographium procerum and Sphaeropsis sapinea and incubated for 8 or 16 weeks, along with non-inoculated control samples. Three decay fungi, Gloeophyllum trabeum, Phlebiopsis gigantea and Schizophyllum commune, were included in the tests to serve as references for weight and toughness loss. After incubation, the samples were equilibrated to 14% moisture content before recording toughness and weight losses. Weight loss was determined by comparing the dry weights of the inoculated samples to the untreated controls rather than expressing weight loss as a percentage of the original weight of a sample.
Neither toughness nor dry weight were significantly (p<0.05) different between specimens inoculated with sapstaining fungi and their controls, except for an isolate of O. ips in one out of three experiments. This isolate of O. ips caused 18% toughness loss without causing weight loss. In one out of four experiments, there was a slight, but statistically significant (p < 0.05) overall weight loss of samples inoculated with different sapstaining isolates which was attributed to the degradation of non-lignified parenchyma cells and extractives. In comparison, the brown-rot fungus G. trabeum caused up to 61% toughness loss after 4 months’ incubation, accompanied by a weight loss of 8%, and the white-rot fungus S. commune produced a toughness loss of 32% without any significant weight loss which indicates that toughness loss is a more sensitive indicator of decay than weight loss.
None of the sapstaining fungi tested caused significant reductions of lignin or structural carbohydrates (arabinose, galactose, glucose, xylose and mannose) in radiata pine sapwood after 16 weeks’ incubation, but all fungal strains, with the exception of O. pluriannulatum, reduced the amount of extractives significantly. Of the isolates tested, O. floccosum degraded extractives most effectively (53.6% reduction). The fact that there were no major differences with regard to the composition of the structural cell wall components of sapstained wood and controls complements the results obtained in the weight loss experiments. Significant amylose and extractives consumption reflect the observation of sapstaining fungi growing extensively in the parenchyma cells and resin canals of radiata pine.
Sapstaining fungi secrete hydrolytic enzymes into the growth substrate and subsequently absorb the products of hydrolysis in the fungal mycelium. Enzyme assays demonstrated that all sapstaining isolates tested secreted low amounts of xylanase (up to 1.64 μmoles/min/ml) and pectinase (up to 0.11 μmoles/min/ml) into the growth medium, but extracellular cellulose was not detected. Under the conditions tested, mannanase was secreted only by O. piceae (0.29 μmole/min/ml). The results suggest that although galactoglucomannans are the major hemicelluloses in softwoods, the arabino-4-methylglucuronoxylans are preferably used by sapstaining as well as decay fungi when growing in softwoods. This may be attributed to the accessibility of the xylans in the S₃-layer of the wood cell wall. Amylase activity of the fungal species tested was more significant than xylanase, mannanase and pectinase activities which confirms that sapstaining fungi preferably metabolize easily accessible, non-structural wood components like starch.
A possible function of the cell-wall degrading enzymes may be the facilitation of the colonization of wood cells, specifically, pectinase may assist the fungal penetration of pit membranes. It is likely that the extracellular sheath which has been observed around hyphae of S. sapinea contains these enzymes and represents an important source of support and hyphal contact with the host cell wall. In addition, pectinase and xylanase could be involved in the pathogenesis of certain sapstaining fungi, as has been demonstrated for O. ulmi and O. novoulmi. The production of specific antibodies against xylanase and pectinase and the subsequent immunohistochemical localization in the host might resolve this question.
Hyphae of sapstaining fungi pass from one wood cell to another by growing through the pit membranes. No differences were observed with regard to the spatial distribution of the sapstaining fungi. Direct cell wall penetration was not observed. The non-lignified parenchyma cell walls of the wood samples infected with sapstaining fungi appeared to be degraded. The ray tracheids in radiata pine were less colonized than the parenchyma cells.
Although low amounts of hemicellulolytic enzymes and pectinase were detected, the effect of sapstaining fungi on wood quality of radiata pine has to be considered cosmetic and non-degradative which confirms the evaluation of sapstain according to the New Zealand Timber Grading Rules (NZS 3631, 1988). In general, sapstaining fungi do not affect the structural wood integrity of radiata pine. If severe sapstain occurs which obscures the grain, there is a possibility that decay fungi may also be present, and since decay fungi do affect the strength of timber, it seems justified not to allow for the use of severely sapstained timber for structural purposes, consistent with NZS 3631 (1988). The use of selected albino-strains of the naturally occurring sapstain population in New Zealand as biocontrol agents on radiata pine logs and timber can be recommended since these fungi were also not found to decrease toughness nor to cause weight loss in radiata pine
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