1,720,973 research outputs found
Pediocin A modulates intestinal microflora metabolism in swine in vitro intestinal fermentations
No full textThe aim of this study was to investigatein vitro the effects of pediocin A [a bacteriocinproduced by lactic acid bacteria (LAB) Pediococcuspentosaceus FBB61] on microbial metabolism inthe small and large intestine of pigs. Pediocin A waspartially purified by ion exchange chromatography andadded to an in vitro fermentation system. The intestinalinoculum was collected from pigs immediately afterslaughter, diluted with a buffer, and dispensed intofermentation syringes and vessels of the 2 experimentalgroups: 1) Bac+ = cecal liquor + predigested diet +pediocin A (final concentration 160 activity units/mL);2) Bac− = cecal liquor + predigested diet + partiallypurified supernatant of P. pentosaceus FBB61–2. Intestinalmicrobial growth was monitored using the cumulativegas production technique; the kinetics of fermentation,bacterial counts, VFA, ammonia, polyamines,and p-cresol production were analyzed. Pediocin A hadalmost no effects on small intestine fermentation parameters,whereas in the cecum pediocin A decreasedgas production (−16%; P < 0.05), ammonia, and VFAproduction (−52 and −21%, respectively, after 24 h;P < 0.001) compared with the control group. Significantinhibition of clostridia and LAB occurred in cecalfermentations: the Bac+ group yielded a decreasednumber of clostridia and LAB in cecal fermentations(8.19 and 7.80 cfu/mL, respectively) compared withBac− (9.32 and 8.95 cfu/mL, respectively; P < 0.001).The low clostridia counts in the pediocin-treated groupmay also explain the reduced concentration of the carcinogeniccompound p-cresol (−88%; P < 0.01). Ourresults suggest that pediocin A could be an alternativeto replace antibiotic growth promoters for the prophylaxisof enteric diseases and to improve production offarm animals.[...
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
EFFECT OF GLUCONIC ACID ON SWINE IN VITRO CECAL FERMENTATION
No full textGluconic acid (GA) derives from the incomplete oxidation of glucose by some Gluconobacter strains. When fed to monogastric animals, GA is poorly absorbed in the small intestine and can reach the lower gut where it is fermented to butyric acid. This study investigated the effect of GA on in vitro growth response and proteolytic state of swine caecal microflora. A diet for pigs (CP 15.8%, DE 15.0 MJ/kg) was predigested in vitro to simulate ileal digestion and later used as the substrate in the in vitro fermentation. Caecal content was collected from 6 pigs, diluted with buffer and used as inoculum. The inoculum was flushed with CO_{2}_ and dispensed into five glass syringes and five vessels per treatment, containing predigested diet. Syringes and vessels were incubated at 39°C for 24 h. There were 6 treatments: control diet, or control diet with GA added at 2,000, 4,000, 6,000, 8,000, and 10,000 ppm. Gas production was measured recording the cumulative volume of gas produced every 30 min. Samples of fermentation fluid were collected from each vessel at time 0, 4, 8 and 24 h for ammonia and at time 24 h for short-chain fatty acids (SCFA) determination. During the 24 h in vitro caecal fermentation, total gas production and maximum rate of gas production were increased by all GA concentrations in a dose-dependent manner (P < 0.001). Ammonia in fermentation liquor was reduced by GA at 2,000 (–26%; P < 0.01) and 4,000 ppm (–17%; P < 0.05) after 4 h and at all concentrations (P < 0.001) after 8 h and 24 h, with the only exception of GA at 2,000 ppm. After 24 h of fermentation, total SCFA, acetic acid, butyric acid, acetic to propionic acid ratio, and acetic + butyric to propionic acid ratio were linearly increased in all GA treatments (P < 0.001).This study showed that GA can positively influence the activity of the swine caecal microflora controlling the proteolysis during the 24 h of fermentation moreover implementing the production of butyric acid which maintains the mucosal health status[...
Effect of lactitol, lactic acid bacteria, or their combination (synbiotic) on intestinal proteolysis in vitro, and on feed efficiency in weaned pigs.
No full textThe purpose of the present study was to evaluate in vitro the intestinal microflora response to lactitol (LCT) as a non-digestible oligosaccharide (NDO) and/or to two swine lactic acid bacteria (LAB) isolates (Lactobacillus brevis and L. salivarius), and to select the most effective treatment to modulate intestinal fermentation in a subsequent growth study with weaning piglets. During a 24-h in vitro cecal fermentation, LCT alone or in combination with either bacteria isolate stimulated gas production rate (P < 0.05), while LAB isolates alone did not (P > 0.05). Both combinations of isolates with LCT reduced ammonia levels after 24 h by 26 and 31%, respectively (P < 0.05), while LCT alone was effective in keeping ammonia lower than the control only in the first 8 h (P < 0.05). All treatments increased (P < 0.05) the production of total volatile fatty acids. The most effective combination (LCT + L. salivarius) in vitro was selected to be used in a 49-d feeding experiment with weaned piglets (32 animals per group, eight piglets per cage, four cages per treatment). Feed efficiency was improved (13%) by LCT + L. salivarius (P < 0.05), while average daily gain and feed consumption were not affected (P > 0.05). These data substantiated the positive synergistic effect of the combination of an NDO with a LAB isolate as compared with the use of individual components in modulating the cecal microflora under in vitro conditions. This study showed that such combination may positively influence feed efficiency when fed to pigs.[...
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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