1,721,375 research outputs found
Potential impact of climate change on the reproductive success of grayling ( Thymallus thymallus )
No full textAbstract The European grayling is a salmonid species experiencing a sharp population decline, and conservation measures have been initiated through artificial propagation. As the species is not commonly cultivated in aquaculture, there is little information on their optimal reproduction conditions. Therefore, this study has combined a two‐pronged approach of examining the temperature of the natural spawning area during the spawning season, while also experimentally testing four different incubation temperatures under standardized aquaculture conditions. Nine egg clutches from pond‐reared females were fertilized with a sperm mix from 10 wild grayling. Eggs were divided into four treatment groups and incubated at 6, 8, 10 and 12°C. Hatched larvae were then collected and examined for body weight, yolk‐sac weight and length. Both the temperature of the natural habitat and the physiological parameters of the larvae indicate that 6 and 8°C are the optimal hatching temperatures for grayling reproduction. The hatching rate was highest at 8 and 6°C, at 80.35 ± 6.30% and 76.87 ± 8.01%, respectively, although it gradually decreased with increasing temperature. The impact of warmer water temperatures hindered survival rates, resulting in a significant decrease in hatching rates at 10°C (68.46 ± 13.85%) and 12°C (45.54 ± 27.14%)
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
Transcriptional profiling of the M. complexus in naked neck chickens suggest a direct pleiotropic effect of GDF7 on feathering and reduced hatchability
No full textAbstract Background The locus for naked neck (Na) in chickens reduces feather coverage and leads to increased heat dissipation from the body surface resulting in better adaptability to hot conditions. However, the Na gene is linked to significantly lower hatchability due to an increased late embryonic mortality. It has been argued that the causative gene GDF7 may have a direct pleiotropic effect on hatchability via its effect on muscle development. Thus, the study presented here analyses the transcriptome of the hatching muscle (M. complexus) and shows how GDF7 impacts development leading to reduced hatching rates in Na chickens. Results Using 12 chicken embryos (6 x wildtype (Wt) and 6 x Na) RNA was extracted from the M. complexus of each embryo and sequenced. The resulting differential expression analyses led to the discovery of 461 differentially expressed (DE) genes in the M. complexus of the experimental group. Among those, 77 genes were of uncertain function (LOC symbols), with 31 were classified as uncharacterised. The regulation of a number of pathways involved in normal embryonic development, were found to be negatively influenced by the Na genotype. Further pathways involved in cell-cell adhesion, cell signalling pathways, and amino acid (AA) metabolism/transport were also observed. GDF7 (alias BMP12), whose localised overexpression in the neck skin causes the Na/Na phenotype, was significantly overexpressed in the M. complexus of Na/Na embryos, and shows a significant increase in the number of binding sites for the transcription factor PITX2 was also observed. Conclusion In Na chickens, GDF7 is under the control of a mutated cis-regulatory element, whose actions are known to suppress the development and distribution of feathers through the sensitizing action of retinoic acid. In this study, a number of DE genes with over 10 retinoic acid response elements (RAREs) in close proximity were observed, indicating changes to the retinol metabolism. With the understanding that the Na/Na mutation leads to increased retinoic acid activity, this indicates a high likelihood of GDF7 excerpting a direct pleiotropic effect, not just in the observed reduction in feather patterning, but also impacting the development of the M.complexus, and consequently leading to the reduced hatchability observed in birds with the Na/Na genotype. Furthermore, the enrichment of PITX2 binding sites in proximity to DE genes in the M. complexus, also indicates that muscle development is still ongoing in Na embryos. This suggests that the M. complexus is not yet fully developed, further increasing the potential for late embryonic mortality in Na chicks at hatching.Open-Access-Publikationsfonds 202
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
The Effect of a Total Fishmeal Replacement by <i>Arthrospira platensis</i> on the Microbiome of African Catfish (<i>Clarias gariepinus</i>)
No full textAn increasing number of fishmeal supplements are becoming the focus of aquaculture research, with a special emphasis on microalgae/cyanobacteria such as spirulina being considered as sustainable alternatives. New feed ingredients can have a far-reaching impact on the intestinal microbiome and therefore play an important role in the development and the health of fish. However, the influence of these alternatives on the microbiome is largely unknown. We undertook a 10 weeks feeding experiment on 120 African catfish with an initial body weight of 50.1 ± 2.95 g. To understand the effect of the spirulina supplementation, two isoenergetic experimental diets were formulated, containing either fishmeal or spirulina as a protein source. The 16S rRNA sequencing was used to analyze the intestinal bacteria microbiota. Results show that the observed richness indicated no significant statistical difference, but Chao1, ACE, Shannon, and Simpson indices indicate a possible increase in bacterial richness for the spirulina diet. The most abundant bacteria in both experimental groups were Fusobacteriia with the only taxa from the genus Cetobacterium. The bacterium from genus Romboutsia was more likely to be found in the microbiome of fish fed the fishmeal diet. In spirulina-fed fish, the genera Plesiomonas and Bacteroides were the most dominant microbes observed. Even though some genera were more abundant in the spirulina group, the overall microbial community structure was not affected by diets
Feeding green: Spirulina ( Arthrospira platensis ) induced changes in production performance and quality of salmonid species
Full text linkSpirulina is an interesting candidate for fish nutrition. This study aims to investigate the effect of the complete replacement of fishmeal with spirulina (Arthrospira platensis) in the diets of brook trout (Salvelinus fontinalis), rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta fario), in relation to growth and product quality. Two isoenergetic and isonitrogenous experimental diets containing either fishmeal or spirulina as a main source of protein were used for a 10-week feeding trial. Differences in the spirulina acceptance and conversion between species were observed. The experimental diets were well accepted except for brown trout. A species–diet interaction was observed, which led to a reduction in final body weight due to the spirulina supplementation for brook and rainbow trout ((Formula presented.) < 0.05). Parallel, the feed conversion ratio increased to the same extent in the spirulina-fed fish ((Formula presented.) < 0.05), fostering the assumption, that both species did not differ in converting the spirulina diet. Spirulina led to a significant increase ((Formula presented.) < 0.05) in yellow and red coloration in both raw and cooked fillets. The diet had a significant effect on the fatty acid profile, resulting in an increase in SFA and MUFA, while PUFA levels decreased significantly in spirulina-fed fish ((Formula presented.) < 0.05). Overall, total replacement of fishmeal with Spirulina goes along with a reduced production performance and effects on major product quality traits such as fillet colour and fatty acid pattern. In particular, consumer acceptance of the yellow fillet colour should be further investigated. © 2022 The Authors. Aquaculture Research published by John Wiley & Sons Ltd
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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