1,720,968 research outputs found
Development of a Simultaneous Saccharificationand Fermentation process using alkaline pretreated wheat straw
No full textstatus: Publishe
Biofilms of Stenotrophomonas maltophilia protect Lactobacillus brevis food spoilage bacteria against classical cleaning and disinfection protocols
No full textedition: Biofilms8status: Publishe
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
De invloed van biofilms in de voedselverwerkingsomgeving op het bederf van ready-to-heat sauzen.
No full textFood spoilage is the microbial, chemical or physical change of a product causing it to become undesirable or unacceptable for human consumption. It is generally considered that microbial spoilage is the major cause of processed food spoilage. Microbial food spoilage is caused by a sequence of events: spoilage organisms gain access to the product; they survive and adapt to the product; and they grow to sufficiently high cell counts to cause a change in the food product.
Biofilms are consortia of bacteria adhering to a surface and enveloped in a self-produced extracellular matrix. By producing biofilms, bacteria have a higher tolerance against cleaning and disinfection protocols compared to their planktonic (free-living) counterpart and may thus survive in the food processing environment. Therefore, introduction to the food product from these biofilms is possible and the presence of biofilms is often considered as a risk for the safety and quality of the food products. Thus, the goal of this PhD research was to examine the influence of biofilms in the food processing equipment on the spoilage of food products with ready-to-heat (RTH) sauces as a case study. For this, the following approach was used: we (i) isolated the microorganisms of prematurely spoiled RTH-sauces and the food processing environment of these products, (ii) determined the biofilm-forming potential of these isolates, (iii) ascertained the biofilm tolerance against conventional cleaning and disinfection (C&D) of a selection of these isolates in a reactor model which could simulate in situ C&D conditions, (iv) checked the effect of the interactions between food spoilage bacteria, with either low or high biofilm-forming ability, and the isolates from the food processing environment on the survival of the food spoilage bacteria in the food processing equipment to (v) finally evaluate both a preventive and curative biofilm removal strategy.
In a first step, the spoilage bacteria of RTH sauces, which showed signs of premature spoilage, were isolated and identified. Three main spoilage organisms were found with different spoilage profiles. Bacilli were most often isolated and appeared to cause mild acidification and liquefaction in the RTH-sauces. Lactic acid bacteria were the second most isolated and were associated with severe acidification of the product. Finally, although only infrequently isolated, yeasts caused gas formation in the food product. The presence of bacilli in the food product might be explained by their ability to form spores which enhances their heat tolerance and might allow them to survive the heat treatment during processing of the sauces. All other spoilage bacteria, however, were not able to survive this heat treatment, indicating a secondary contamination of the sauces during filling. Moreover, the presence of biofilms in the filling equipment of these sauces was shown in a previous study, pointing to the presence of biofilms as a risk for the contamination of the RTH-sauces. However, the spoilage bacteria, isolated from the RTH-sauces, were not found among the dominant bacteria, found in biofilms in the filling equipment, indicating that even at low abundancies in the food processing environment, the spoilage bacteria might pose a risk for contamination and consequent spoilage of the RTH sauces.
Subsequently, the biofilm-forming ability of both kinds of isolates was determined in vitro. The majority of the food spoilage isolates showed some degree of biofilm formation, except a number of lactic acid bacteria. The biofilm forming ability of the isolates from the filling equipment of RTH-sauces were compared to isolates from processing equipment of other food sectors, in an attempt to find similarities between the different food sectors. However, few similarities were found among the strong biofilm producers of the different companies, except for Pseudomonas spp. and Stenotrophomonas maltophilia, which were found among the strong biofilm producers in every company except one.
To determine the biofilm tolerance against conventional cleaning and disinfection, first a laboratory method was designed to study the (organic fouling and) biofilm removal from stainless steel which could simulate in situ cleaning and disinfection conditions. This biofilm reactor model was used in the next part of the research to characterize the tolerance against cleaning and disinfection of the spoilage bacteria, isolated from the RTH-sauces, and the food processing bacteria, isolated from biofilms in the filling equipment. The spoilage bacteria were able to form biofilms on stainless steel surfaces and survive cleaning and disinfection, albeit at low initial cell counts before cleaning and disinfection and/or low tolerance against cleaning and disinfection which coincided with their (hypothesized) low abundancy in situ. In contrast, biofilms of isolates from the food processing environment showed both high initial cell counts in biofilm and high residual cell counts after cleaning and disinfection. The presence of these strong biofilm producing bacteria in the food processing environment might influence the attachment and survival of the relatively low biofilm producing food spoilage strains, which was investigated in a later step of the research. In a final step of this part, the biofilm tolerance of the strongest biofilm producers of several food companies was compared. A low efficacy of the disinfectants, without prior cleaning, was observed. However, when a cleaning step was incorporated, the efficacy of the total cleaning and disinfection protocol increased, mainly due to a high biofilm removal during cleaning. Nonetheless, differences in regrowth of the residual biofilm after (cleaning and) disinfection were observed between the different bacteria. For some bacteria the number of cells after regrowth was comparable to or higher than the initial biofilm cell count, independent of the incorporation of a cleaning step or the cleaning and disinfection products used. For one strain, the use of chlorinated products induced a higher regrowth compared to the other cleaning agents and disinfectants. For the remaining bacteria, the incorporation of a cleaning step significantly inhibited the regrowth to cell counts below the initial biofilm cell count before cleaning and disinfection, independent of the cleaning and disinfection products used. These results indicated that (i) cleaning and disinfection should be optimized against the specific bacteria isolated from the food processing environment and (ii) that further optimization of the cleaning and disinfection protocols for biofilm removal and control is still needed.
Given the low biofilm forming ability and/or tolerance against cleaning and disinfection of the food spoilage bacteria, we hypothesized that the strong biofilm producing bacteria present in the food processing environment might increase the survival of the food spoilage bacteria. Therefore, in a next step, the isolates from biofilms in the filling equipment of the RTH-sauces were pairwise cocultured with the spoilage bacteria, isolated from the RTH-sauces, to determine their interactions. For most combinations, a decrease in fitness of the spoilage bacteria, with a decrease of the total biomass and EPS production, was observed. The only exception were the combinations of food spoilage bacteria with S. maltophilia, which instead showed a positive complementary effect for all food spoilage bacteria. Therefore, these combinations were further characterized for their social interactions and tolerance against cleaning and disinfection in the biofilm reactor model, indicating a dual role of S. maltophilia on the attachment and survival of different spoilage bacteria. The fitness and tolerance against cleaning and disinfection of bacilli decreased when co-cultured with S. maltophilia, as opposed to the fitness and tolerance of lactic acid bacteria, which increased when cocultured. The presence of S. maltophilia in the food processing environment might thus both prevent or increase the risk of transmission of spoilage bacteria to the food product, dependent on the specific spoiler.
Therefore, in the final step of the research, two strategies were explored for the removal of Stenotrophomonas maltophilia biofilms. Firstly, the importance of incorporating a cleaning step for the removal of biofilms was further characterized by microscopical analysis and (partial) EPS characterization. This analysis revealed that incorporating a cleaning step induced a higher EPS removal and inhibition of the α-polysaccharides production during regrowth. Based on these results, optimization of C&D was attempted, revealing that optimal S. maltophilia biofilm removal and inhibition of the regrowth of the residual biofilm was not achieved by increasing the concentration of the cleaning agent but by increasing the disinfectant concentration after a cleaning step with the lowest concentration. Secondly, we demonstrated the potential of different modified surfaces to reduce the biofilm formation and/or facilitating the biofilm removal of Stenotrophomonas maltophilia.status: Publishe
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
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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