1,720,962 research outputs found
A Rapid Enzyme-Linked Immunomagnetic Electrochemical (ELIME) Assay for the Detection of Escherichia coli O26 in Raw Milk
No full textIn this work we present a magnetic bead–based immunosensorss for the determination of Escherichia coli O26 in milk. The assay uses commercial Dynabeads® for the capture of the target bacteria from 6-h enrichment broth and horseradish peroxidase–labelled polyclonal antibodies and detection of the peroxidase activity by chronoamperometry. Bovine seroalbumin was used as blocking reagent for reducing the binding of non-specific antibodies to the beads and/or other bacteria. The effectiveness of the enzyme-linked immunomagnetic electrochemical (ELIME) assay to detect low number of E. coli O26 in milk was demonstrated using spiked milk samples from five different lots with concentrations of 9.00–18.80 or 0.90–1.88 CFU in 25 mL. Three repetitions for each concentration were analysed in parallel also by real-time PCR following the standard method ISO/TS 13136:2012, using 24-h enriched cultures. Results demonstrated that the ELIME assay can reduce the time for analyses to one working day and produce reliable results that can be confirmed by overnight cultures of the beads-bacteria complexes allowing further characterization of the virulence, including the presence of Shiga toxin–encoding genes, which is important to discriminate the enterohaemorrhagic strains
Detection and Characterization of Histamine-Producing Strains of Photobacterium damselae subsp. damselae Isolated from Mullets
Full text linkPhotobacterium damselae subsp. damselae (Pdd) is considered to be an emerging pathogen of marine fish and has also been implicated in cases of histamine food poisoning. In this study, eight strains isolated from mullets of the genera Mugil and Liza captured in the Ligurian Sea were characterized, and a method to detect histamine-producing Pdd from fish samples was developed. The histamine-producing potential of the strains was evaluated in culture media (TSB+) using a histamine biosensor. Subsequently, two strains were used to contaminate mackerel fillets (4 or 40 CFU/g), simulating a cross-contamination on the selling fish stalls. Sample homogenates were enriched in TSB+. The cultures were then inoculated on thiosulfate-citrate-bile salts-sucrose agar (TCBS) and the dark green colonies were cultured on Niven agar. The violet isolates were characterized using specific biochemical and PCR based tests. All Pdd strains were histamine producers, yielding concentration varying from 167 and 8977 µg/mL in TSB+ cultures incubated at 30 °C for 24 h. Pdd colonies were detected from the inoculated mackerel samples and their histidine decarboxylase gene was amplified using species-specific primer pairs designed for this study. The results indicate that mullets can be source of Pdd and the fish retailers needs to evaluate the risk posed by cross-contamination on the selling fish stalls
Effects of Beeswax Coating on the Oxidative Stability of Long-Ripened Italian Salami
Full text linkBeeswax coating of foods put a barrier to oxygen, light, and vapour that can help to prevent oxidation of fat and pigments and water loss. The amounts of 2-thiobarbituric acid reactive substances (TBARS) and water activity (Aw) were assessed in Italian salami coated with beeswax at 55 days of ripening and compared with controls at 5, 6, and 7 months of shelf life. The results were correlated with sensory quality. TBARS levels were below 0.8 mg kg−1 in the beeswax-coated salami until 6 months of aging (median 0.697, max 0.795) and significantly higher in the uncoated salami (median 1.176, max 1.227). A slight correlation between the amount of TBARS and Aw was observed in beeswax-coated salamis, whereas this effect was masked in controls by the large Aw variability observed at 7 months. Beeswax coating prevents case hardening and facilitated the peeling
Vertical distribution of 137Cs in the lacustrine areas and preliminary results of 7Be activity in snow samples at terra nova bay (antarctica)
No full text137Cs activity in samples from lacustrine areas around the Italian base in Antarctica is reported as an integration of a previous work. Preliminary data of cosmogenic 7Be activity determined in snowfalls, total atmospheric depositions, soil and air particulate collected during the 1990–91 and 1991–92 Italian expeditions in Antarctica is presented. The results obtained point out the efficiency of snow in the processes of air particulate scavenging and provide useful information for the development of research in Antarctica in the study of air/snow transfer processes by means of natural radionuclides. © 1994 Gordon and Breach Science Publishers S. A
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Effects of sanitizing treatments with atmospheric cold plasma, SDS and lactic acid on verotoxin-producing Escherichia coli and Listeria monocytogenes in red chicory (radicchio)
Full text linkThe main objective of this study was to evaluate the synergistic effect of atmospheric cold plasma (ACP), Sodium Dodecyl Sulphate (SDS) and lactic acid (LA) on L. monocytogenes and verotoxin-producing E. coli in red chicory. Experimentally inoculated samples were pre-treated with either SDS, or SDS + LA for 5, 10 or 15 min. Pre-treated samples were then submerged in deionized water and either exposed to ACP generated by dielectric barrier discharge device (DBD: fixed parameters: 19.15 V and 3.15 A) for 15 min or left untreated. All combinations of treatments were evaluated for sensory effects. Viable counts of verotoxin-producing E. coli on red chicory decreased by more than 4 logs (4.78 Log CFU/cm2 vs control) after a treatment with LA + SDS for 5 min and ACP for 15 min and often dropped below the limit of quantification. L. monocytogenes showed a higher tolerance to this sanitizing treatment and the level of inactivation was higher than 3 logs (3.77 Log CFU/cm2 vs control) only by increasing the duration of the washing step in LA + SDS to 15 min. The different treatments had no detrimental effects on colour, freshness and texture of red chicory, but odour and overall acceptability of the samples treated by ACP slightly decreased during storage. Further optimization of treatment parameters for maintaining fresh characteristics are needed, but the effectiveness of combinations of sanitizers and ACP on other pathogens and fresh produce worth to be investigated
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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