1,720,980 research outputs found
Adipose tissue and lipid metabolism
No full text© 2015, 2000 Elsevier Inc. All rights reserved. Adipose tissue is the most variable carcass component and has traditionally been considered a rather inert storage tissue for energy in the form of lipids. Most of the fat in chickens is located in adipose depots, which are all late maturing. At the cellular level, preadipocyte differentiation and proliferation are under the control of multiple hormones and transcription factors. The growth of fat tissue is initially due to hyperplasia followed by hypertrophy of the mature adipocytes. The amount of fat deposited is controlled by numerous hormones and depends on genetic and nutritional factors.Dietary fat is transported as portomicrons to the liver, which is also the primary site of the de novo lipogenesis. The newly formed very-low-density lipoproteins (VLDLs) are distributed by the blood to the rest of the body. Lipoprotein lipase is a key enzyme in the further processing of these lipoproteins at the level of various tissues, in particular the lipoprotein metabolism in laying hens. All egg yolk lipids are synthesized mainly by the liver and transported to the ovary in special yolk-targeted VLDL (VLDLy) with an unusual apoprotein (apo) composition (only apoB and apoVLDLII).Recent research has, however, revealed that adipose tissue must now be regarded as a dynamic tissue, which secretes a considerable number of adipokines and hence plays a role in a multitude of bodily processes.status: Publishe
Avian molting
No full textFeathers are the characteristic feature of birds and plumage provides several vital functions, including, uniquely, flight. Feathers are replaced annually in a strictly controlled bilaterally symmetrical sequence so that the roles of plumage are not compromised. Molt is a key life history stage for all birds and its timing is important. Birds normally molt after breeding, and there is a close relationship between the end of breeding and the start of molt. Birds avoid molting during migration and do not molt during winter. The timing and rate of molt are controlled by the annual cycle in photoperiod and modulated by non-photoperiodic factors such as the duration of breeding activity. Despite decades of research, little is known about the physiological control of molt. Thyroid hormones, gonadal steroid hormones and prolactin have all been shown to affect molt, but the latter is more likely to have a direct causal role
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
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
Breast muscle myopathies: twists and turns in modern broilers
No full textAlthough poultry meat production supports the livelihood and provides food security for billions of people worldwide, it is facing substantial challenges. The emergence of broiler breast myopathies (white striping, woody breast, spaghetti meat) at large scale is one of the most significant economic and welfare challenges that menace poultry production sustainability and for which there is currently no effective prevention, due to its unknown aetiologies. Here, by inviting and gathering several experts with diverse, but complementary disciplines, the objective of the present review is to highlight the current progress and knowledge on these myopathies. Five sections are presented, describing in detail the history and geographic occurrence of these breast myopathies, their macroscopic morphologies and microscopic characteristics, their putative aetiologies and causes as well as their underlying molecular mechanisms, and potential strategies and solutions. The is review summarizes both descriptive and functional mechanistic studies, highlights the complexity of these myopathies and the kinship between broiler genome, nutrition, and management, and outlines some of the promising molecular signatures. It aims to offer new fundamental frameworks for future investigations
- …
