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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
Nutrient digestibility and predicting the energy content of pig feeds
No full textWith 11 million slaughters per year, pigs are the most important production animal in Belgium. Feed is
the biggest cost factor in pig farming, especially the energy component. The aim of feed formulation
and production is to meet the nutrient requirements of pigs under the constraint of the available feed
ingredients (Chapter 1). Correct energy and nutrient evaluation is critical, especially given the increasing
amounts of fiber-rich co-products from human food production that are being included in pig feed.
Another difficulty is that feed digestibility and utilization depend on many factors related to either the
animal or to its growing conditions (Chapter 1). The net energy (NE) reflects best the true available
energy for pigs, but NE determination requires time-consuming and expensive in vivo digestibility
experiments. Potential methods to estimate NE in feeds include the use of tabular values of ingredients,
empirical models based on chemical parameters and/or the in vitro digestibility of organic matter and
near infrared spectroscopy (NIRS).
The following research objectives (Chapter 2) were defined:
• Study the interactions between fat and fiber level on nutrient digestibility and energy utilization
of pig feeds (Chapter 4)
• Evaluate the usefulness and accuracy of NIRS calibrations based on spectra from pig feed and
feces to predict their chemical composition as well as nutrient digestibility and NE (Chapter 5)
• Compare a) the use of feed tables, b) empirical models based on chemical and in vitro analyses
and c) NIRS calibrations based on feed and feces spectra for their accuracy in predicting feed
quality and more particularly NE, their applicability in practice and their limits (Chapter 6)
Data related to these objectives were gathered via three in vivo digestibility trials. In Chapter 3, the
protocol and details of the various methods used are described and justified. Main conclusions are: the
acid insoluble ash (AIA), that is naturally present in pig feeds, is reliable as marker to determine nutrient
digestibility via spot sampling of feces; AIA and TiO2 are equally reliable as external markers; the NE
of a feed increases with 0.0021 MJ per kg higher bodyweight; once-daily sampling and pooling feces
from two or three animals per pen is sufficient to determine in vivo digestibility.
The interactions between fiber-rich co-products and fat were investigated, as well as their possible
impact on nutrient digestibility and NE (Chapter 4). For this experiment, a low fiber (LF) and a high
fiber (HF) diet were formulated. From these two basal diets, 8 additional diets were derived by adding
20 or 40 g/kg of either pig fat or soy oil. Compared to LF diets, HF diets had a lower (P<0.05)
standardized digestibility for all nutrients except for NDF. However, higher fiber levels in the diet did
not affect the digestibility of the added fat. The standardized digestibility of fat in the HF diets with
added fat was higher (P<0.05) than that of the non-fat supplemented basal diet, whereas no significant
(P>0.05) differences in fat digestibility among the LF diets were observed. Increasing fat level appeared
to negatively affect the fat-free organic matter digestibility, in particular NDF. On the other hand, the
negative effect of fat addition on digestibility and NE was relatively small in comparison to the extra
energy added by the fat. Therefore, no special consideration should be given when adding extra fat to a
fiber-rich diet to meet pigs’ energy requirements.
For prediction of the chemical composition of pig feed and feces, as well as nutrient digestibility and
NE, the usefulness and accuracy of NIRS calibrations based on combined spectra were investigated
(Chapter 5). Near infrared spectroscopy appeared to accurately predict (residual prediction deviation,
RPD>3; R²>0.8) most organic components and moisture content of pig feed and freeze-dried feces. The
NE was better estimated using feed spectra than feces spectra, with a standard error of cross validation
(SECV) of 0.33 and 0.46 MJ/kg, respectively. Combining feed and feces spectra resulted in an overall
better estimation of the digestibility and NE, especially with merging (SECV=0.26 MJ/kg) and
subtracting (SECV=0.27 MJ/kg). Finally, this study highlighted the importance of the cross-validation
method when the dataset contains several feces spectra (alone or combined) from the same feed. Indeed,
cross-validation may lead to over-optimistic results when the group to be validated contains spectra that
are not independent.
The use of tabular values, empirical models and NIRS to estimate nutrient composition and NE were
compared (Chapter 6). This evaluation was based on 62 compound feeds, and 28 among them had known
ingredient composition. In addition to the accuracy of each approach, their applicability in practice and
practical limitations were compared. Feed tables predicted most chemical components accurately
(R²>0.90), with exception of crude ash, sugar, acid detergent lignin and moisture, the latter being
strongly underestimated (-16 g/kg). The standard error of estimate (SEE) for NE with tabular values
amounted to 0.29 MJ/kg. Using empirical models based solely on chemical parameters resulted in a SEE
of 0.21 MJ/kg. Incorporating in vitro digestibility resulted in a decrease of SEE to 0.18 MJ/kg. The SEE
of a NIRS calibration based on feed spectra alone resulted in a SEE of 0.33 MJ/kg, whereas the
combination of feed and feces spectra decreased this error to 0.26 MJ/kg. The use of feed tables allows
a cheap and fast estimation of the chemical composition and NE, but it is only suitable for feeds of
known and common ingredient composition and is not so accurate. The use of empirical models allows
to accurately estimate the NE of feeds even with unknown composition, but relies on quite expensive
and time-consuming analyses. Finally, NIRS calibration based on feed and feces spectra allows for a
fast estimation of NE, but is less precise than empirical models and requires a specific sample
preparation.
Finally, the general discussion, conclusions and recommendations are presented (Chapter 7), where the
results are discussed in depth and put into perspective. Important attention points are the limitation of
NIRS accuracy for evaluating compound feeds due to the complexity and heterogeneity of the matrix;
the error (0.033 MJ/kg) in the determination of the in vivo NE reference value due to sampling, animal
variation and laboratory analysis, which represents the maximum achievable accuracy for the predicting
models; and the practical limitation and applicability of each method. Future research could consider a
combination of estimation methods and it would be interesting to integrate the energy and protein (amino
acid) balance
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Assessing plant type and the nutritive value of silage maize in the perspective of the Belgian official variety trials
Get PDFRoughage evaluation of maize and grass silage based on chewing activity measurements with cows
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