1,720,955 research outputs found
Interpopulation Genetic Variance after Reciprocal Recurrent Selection in BSSS and BSCB1 Maize Populations
Get PDFReciprocal recurrent selection is a breeding procedure designed to improve two populations simultaneously by selecting for performance in the interpopulation cross. The objective of this study was to evaluate the effects of II cycles of selection on the mean, genetic variance, and correlations amongtr aits in the interpopulationc ross of the Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic no. 1 (BSCBI) maize (Zea mays L.) populations. Oneh undredr eciprocal full-sib families from Cycle 0, Cycle 5, and Cycle II of the interpopulation cross between BSSS and BSCBI were evaluated at two locations in 1989 and three locations in 1990. Grain yield increased 0.25 Mg ha-1 per cycle (6.46%) after II cycles of selection, grain moisture increased 0.85 g kg-1 per cycle, root lodging decreased 0.23%, and stalk lodging decreased 1.64% (all changes significant at P = 0.01). Estimates of genetic variance for all traits were significantly different from zero, except for root lodging in Cycle II. Genetic variance for grain yield decreased after II cycles of selection, although the differences among cycles were not significant. Root lodging, stalk lodging, anthesis date, and silking date had significant decreases in genetic variance after II cycles of selection. Changeisn heritability generally paralleled changes in genetic variance. Genotypic and phenotypic correlations were seemingly unchangeda cross cycles of selection. The results indicate that reciprocal recurrent selection has been effective in increasing the mean performance of the population cross while maintaining genetic variance.This article is published as Schnicker, Bruce J., and Kendall R. Lamkey. "Interpopulation genetic variance after reciprocal recurrent selection in BSSS and BSCB1 maize populations." Crop science 33, no. 1 (1993): 90-95. doi: 10.2135/cropsci1993.0011183X003300010016x. Posted with permission.</p
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
Comparison of genetic variances in F2 and backcross populations of maize
No full textSecond cycle breeding is characterized by the improvement of an elite line through the addition of favorable alleles from a complimentary line. Second cycle breeding, utilizing backcross and F[subscript]2 generations, has become the predominant type of line development program in the U.S. maize industry. Epistasis and linkage have been identified as possible limits to progress from selection in F[subscript]2 and backcross populations;Objectives of this study were: (1) to provide empirical data comparing the testcross progenies of the F[subscript]2, F[subscript]2-Syn 8, and first backcross generations for means, genotypic variances, heritabilities, frequency distributions, selection responses, and trait correlations, (2) to examine the importance of epistasis in the generation testcrosses derived from inbred lines B73, B84, and Mo17, (3) to examine changes in the testcross population derived from the F[subscript]2 generation following eight generations of random mating, and (4) to recommend the superior type of segregating population to develop from the cross of elite inbred lines B73 and B84;Significant positive digenic epistatic effects were detected for grain yield. The estimate of epistasis obtained by weighted least squares regression of generation means was 0.20 Mg ha[superscript]-1. Ear height also contained significant digenic epistatic effects and evidence for higher order epistasis was detected. Epistatic effects were not significant contributors to genetic variation for any other traits. Due to a lack of significant genetic variance in the superior backcross generation, epistasis was concluded to be of minor importance in the choice of segregating population to develop for selection of superior yielding lines;The F[subscript]2 population had significantly greater mean grain yield (0.27 Mg ha[superscript]-1) while significantly lower genetic variance from 5.80 x 10[superscript]-2 to 9.02 x 10[superscript]-2 in the F[subscript]2-Syn 8 population. Random mating was considered of little value, however, considering the increased time to produce progeny for evaluation when selection is for individuals with increased grain yield;Applied breeding programs generally utilize a high selection intensity for grain yield in elite by elite segregating populations. The superior type of segregating population to develop from the cross of inbreds B73 by B84 under high selection intensity for grain yield was the F[subscript]2 generation. The backcross to B84 was the superior type of segregating population under low selection intensities.</p
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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