1,721,230 research outputs found
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
Transgenerationele effecten van voederbeperking en een gereduceerd, gebalanceerd eiwitdieet op het welzijn, leervermogen en gedrag van vleeskuikenouderdieren
No full textTo reach desirable productivity and low mortality, controlled feeding programs need to be imposed on the broiler breeders. However the controlled feed intake could induce behavioral abnormalities like over drinking, stereotypic behavior, being more aggressive and so on. Low protein diet gets more attention of researchers because of its environmental and economical interest. It has been reported that some internal or external influence to maternal animals can be inherited by their offspring. This project is meant to see if reduced and balanced protein diet have effect on the welfare and behavior of broiler breeders over generations. Regular behavioral observation and welfare evaluation is followed for several generations.status: Publishe
Effects of protein phosphorylation on postmortem glycolysis and glycolytic enzymes in ovine muscle
No full textGlycolysis, the core metabolic pathway in muscle, is highly important to ultimate meat quality. Protein phosphorylation is one of the most frequent post-translational modifications that alter the properties of proteins by changing their structural conformation and regulating the function of these proteins in muscle. Postmortem glycolysis is a sequence of enzymatic reactions that are determined by the activities of glycolytic enzymes, while most of the glycolytic enzymes were reported as phosphoproteins in previous studies. In recent years, some proteins with different phosphorylation levels clustered in the glycolysis pathway were identified based on muscle samples of different tenderness, colour stability or water-holding capacity. The systematic research of protein phosphorylation on postmortem glycolysis was less of a concern. The objective of this research is to confirm the involvement of protein phosphorylation on postmortem glycolysis and the possible regulatory mechanism from the perspective of enzyme activity.
To analyse the relationship between protein phosphorylation and postmortem glycolysis, 60 experimental sheep with the same breed, sex, environment and slaughter method were used. Based on muscle pH values at 6 h (pH6h) postmortem, 18 sheep carcasses were selected and divided into three groups (six sheep in each group): Fast glycolytic rate group (pH6h 6.20). Phosphorylation level and glycolytic related indicators such as pH value, glycogen content and lactic acid were measured and analysed. The global phosphorylation level (phosphoproteins/total proteins by electrophoresis gel with different dyes) of sarcoplasmic protein increased early postmortem and then decreased afterwards in ovine muscle. Protein bands significantly different in phosphorylation levels were identified as glycometabolism related enzymes. The phosphorylation levels of glycogen phosphorylase and pyruvate kinase may be one possible reason for the difference of glycolytic rate at 0.5 h postmortem. The glycolytic rate attributes were negatively correlated with 4 bands that were probably phosphofructokinase, enolase and adenylate kinase isoenzyme. The results revealed that the phosphorylation of sarcoplasmic proteins was related to muscle pH decline at early postmortem.
One dimensional electrophoresis is not sufficient to clarify the specific phosphoproteins and phosphosites; quantitative proteomic tools (isobaric Tags for Relative and Absolute Quantitation, iTRAQ) and bioinformatics analysis were used to further understand the relationship. In total, 24 phosphoproteins clustered in glycolysis and muscle contraction were identified to be glycolytic rate related proteins; from which, 32 phosphopeptides were determined to have a significant difference among the fast, moderate and slow glycolytic rate groups. In addition, phosphorylation of pyruvate kinase at Thr157 was negatively correlated with the glycolytic rate. The current results illustrated that these glycolytic rate related phosphoproteins were related to early postmortem glycolysis, and four possible regulatory pathways were speculated: 1) Enzyme activities regulation pathway, 2) μ-calpain degradation pathway, 3) Energy metabolism pathway, 4) Protein kinase activity regulation pathway. Further, it was concluded that protein phosphorylation at early postmortem may indirectly affect the glycolysis pathway through the regulation of proteins involved in glycolysis and muscle contraction.
Based on the research above, the validation of protein phosphorylation on postmortem glycolysis is necessary. In addition, the regulatory mechanism from the perspective of enzyme activity should be considered. Six sheep with the same breed, sex, environment and slaughter method were selected. Ovine muscle was treated with a kinase inhibitor, dimethyl sulfoxide, or a phosphatase inhibitor. Protein phosphorylation level revealed that the kinase inhibitor and phosphatase inhibitor were effective at modulating the level of protein phosphorylation. The pH value and lactate content revealed that a high phosphorylation level was the reason for the fast glycolysis. Protein phosphorylation was positively correlated with the activity of these rate-limiting enzymes (glycogen phosphorylase, pyruvate kinase and phosphofructokinase). Protein phosphorylation plays a role in postmortem glycolysis through the regulation of enzyme activity in ovine muscle.
In conclusion, the results with different glycolytic rate groups have systematically exposed novel information of protein phosphorylation on postmortem glycolysis through the use of quantitative proteomic analysis. Protein phosphorylation is related to postmortem glycolysis and glycolytic enzymes, and the phosphorylation level of glycolytic enzymes may influence its activities, further regulating postmortem glycolysis
THE EFFECT OF AMP-ACTIVATED PROTEIN KINASE DURING HEAT STRESS ON THE INTESTINAL BARRIER AND THE REGULATION OF TIGHT JUNCTION PROTEINS OF BROILERS, RESEARCH AT SHANDONG AGRICULTURAL UNIVERSITY (CHINA)
No full textDispelling 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
AMPK en het energie metabolisme in kuikens
No full textAMPK is a heterotrimeric enzyme, which plays an important role in cellular energy balance in eukaryote species. Mammalian studies suggested that AMPK pathways in the central and peripheral tissues coordinately integrates inputs from multiple sources to regulate energy balance at a whole-body level. In this dissertation, we explored the potential role of AMPK in the regulation of energy homeostasis in broiler chickens.
During incubation, there is an inevitable spread of hatching time for late versus early hatching chicks. We found that female chicks hatched at a different time exhibited distinct neonatal performance: the feed intake and growth rate of the late hatchers were higher as compared to that of the early hatchers. The late hatchers had higher glycogen contents in the liver and the hatching muscle, and utilized yolk more rapidly compared to their early counterparts. Thereby, we investigated the involvement of hypothalamic and hepatic AMPK and potential effectors in the spread of hatching time model. As a result, hypothalamic AMPKα1 isoform gene expression was significantly higher in the late hatcher as compared to that of their early counterparts. The hypothalamic orexigenic NPY and AgRP mRNA levels were higher in the late hatchers as compared to the early. In the liver, AMPKα2 mRNA level and the phosphorylation ratio of AMPKα was significantly lower in the late hatchers, as compared to their early counterparts. The hepatic phosphorylated GS levels of the late and middle hatchers were lower than that of their early counterparts. Taken together, AMPK may play a significant role in the different neonatal performance of the spread of hatching time model. The central and peripheral AMPK in late hatchers exhibited a pattern of higher energy intake and lower energy expenditure, which resulted in a faster post-hatch growth.
In order to specifically target AMPK, a mammalian central AMPK inhibitor, α-LA, was supplemented to the diet of broiler chicks for seven days, and hypothalamic and hepatic AMPK and downstream targets were monitored. As a result, dietary α-LA decreased feed intake of broiler chicks independent of the taste aversion. The anorectic effect was due to the reduced hypothalamic phosphorylated AMPKα as reflected in its decreased mRNA and protein levels. However, the anorectic effect of α-LA was progressively diminished after 7 days of treatment, likely by a physiological counteractive feedback via changing neuropeptides involved in energy balance regulation. In liver, on the other hand, α-LA decreased the hepatic glycogenesis and lipogenesis via stimulating hepatic AMPKα in mRNA levels and phosphorylation. The stimulatory effect of α-LA on hepatic AMPK together with the inhibitory effect on hypothalamic AMPK may have altered the energy balance and hence impaired body weight gain of broiler chicks.
Recent years, there is a growing interest in studying the role of dietary protein in energy regulation using isocaloric low protein diets. Here we investigated the response of hypothalamic AMPK and (an)orexigenic neuropeptides to this diet providing lower crude protein yet sufficient energy in broiler chicks. As a result, broiler chicks fed with isocaloric low protein diet attained higher feed intake likely through decreasing hypothalamic anorexigenic POMC and SREBP-1 as an attempt to meet the protein needs. Plasma thyroid hormones and corticosterone results indicated an increment in energy expenditure resulting in a decreased growth rate of those protein malnutrition chicks. The decreased AMPKα activity suggested that AMPK is prone to be changed by the overall energy intake, but not ingested protein alone, to regulate energy balance.
In conclusion, AMPK is involved in the regulation of feed intake and energy homeostasis in chickens. However, the changes of hypothalamic AMPK, expression and/or activity, are not always consistent with the (an)norexigenic neuropeptides, indicating that the regulatory mechanism of AMPK on hypothalamic (an)orexigenic neuropeptides are indirect and not necessary. AMPK may play a role in the regulation of carbohydrate and lipid metabolisms in chickens as in mammals. Moreover, the response of chicken AMPK to the changes of energy status is tissue-specific.status: Publishe
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