1,721,025 research outputs found
Linear models for diallel crosses: a review with R functions
No full textKey message: A new R-software procedure for fixed/random Diallel models was developed. We eased the diallel schemes approach by considering them as specific cases with different parameterisations of a general linear model. Abstract: Diallel experiments are based on a set of possible crosses between some homozygous (inbred) lines. For these experiments, six main diallel models are available in literature, to quantify genetic effects, such as general combining ability (GCA), specific combining ability (SCA), reciprocal (maternal) effects and heterosis. Those models tend to be presented as separate entities, to be fitted by using specialised software. In this manuscript, we reinforce the idea that diallel models should be better regarded as specific cases (different parameterisations) of a general linear model and might be fitted with general purpose software facilities, as used for all other types of linear models. We start from the estimation of fixed genetical effects within the R environment and try to bridge the gap between diallel models, linear models and ordinary least squares estimation (OLS). First, we review the main diallel models in literature. Second, we build a set of tools to enable geneticists, plant/animal breeders and students to fit diallel models by using the most widely known R functions for OLS fitting, i.e. the ‘lm()’ function and related methods. Here, we give three examples to show how diallel models can be built by using the typical process of GLMs and fitted, inspected and processed as all other types of linear models in R. Finally, we give a fourth example to show how our tools can be also used to fit random/mixed effect diallel models in the Bayesian framework
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
One-Point Calibration of Low-Cost Sensors for Particulate Air Matter (PM) Concentration Measurement
Full text linkThe use of low-cost sensors has dramatically increased in recent years in all engineering sectors. In the buildings and automotive field, low-cost sensors open very interesting perspectives, because they allow one to monitor temperature and humidity distributions together with air quality in a widespread and punctual way and allow for the control of all energy parameters. The main issue remains the validation of the measurements. In this work, we propose an innovative approach to verify the measurements given by some low-cost systems built ad hoc for automotive applications. Two independent low-cost measurement systems were set to measure Particulate Air Matter (PM) concentration, TVOC concentration, CO2 concentration, formaldehyde concentration, air temperature, relative humidity, pressure, air flow velocity, and GPS position. These systems were calibrated for PM concentration measurement by comparison with standard and certified sensors used by the regional authority of the Emilia-Romagna region (ARPAE, Italy) for characterizing air quality. The duration of the analysis, three days, is not representative of the diverse environmental conditions that occur across different seasons. However, the innovation of this approach lies in both the in-field comparison of low-cost and high-quality sensors and the use of proper conversion approaches for mass concentration measurements. A quantitative analysis of the sensors' performance is given, with a focus on the effects of time granularity, relative humidity, mass conversion from particle counts, and size detection response. The results show that the low-cost sensors' measurements of air temperature, relative humidity, and particle number concentration are in good agreement with high-quality sensors' measurements, with a strong impact of relative humidity on performance indicators. Overall, good quality and consistency of the data among the sensors were achieved
Lucerne cultivar adaptation to Italian geographic areas is affected crucially by the selection environment and encourages the breeding for specific adaptation
No full textPlant breeding programmes frequently face the dilemma whether to breed for wide or specific adaptation. This is especially true for forage crop breeding, whose genetic resources may largely include landraces that are adapted to specific growing conditions. This study aimed to (1) investigate the extent and pattern of genotype × location (GL) interaction for biomass yield of recent lucerne cultivars across organically-managed sites of Northern and Central Italy and its relationship with cultivar selection environments, (2) provide an empirical assessment of yield gains derived from specific-adaptation and wide-adaptation breeding strategies, and (3) identify top-performing cultivars for different geographic regions. Cultivar adaptive responses, modelled by additive main effects and multiplicative interaction analysis, displayed wide GL interaction of cross-over type across test sites that reflected remarkably the geographic area and/or the growing conditions (particularly for extent of summer drought) of their selection environment. GL interaction patterns suggested three putative subregions to breed for specific adaptation, namely, Northern Italy north of the Po river, Northern Italy south of the Po river, and Central Italy. Growing specifically-adapted cultivars provided an estimated average advantage of 12.9% across subregions relative to the best-performing widely-adapted cultivar. Yield gains of recent top-performing material over an historical, widely-adapted cultivar indicated that selection for specific adaptation would provide 3.2-fold greater yield gain averaged across subregions, and 3.4-fold greater yield gain over the target region when weighting yield gains on the putative proportion of the target region of each subregion, compared with selection for wide adaptation
Farmer-participatory vs. conventional market-oriented breeding of inbred crops using phenotypic and genome-enabled approaches: A pea case study
No full textParticipatory plant breeding (PPB) has gained increasing importance in developing countries, but its value for market-oriented breeding programmes of countries with developed agriculture that are committed to pure line selection (as needed to comply with DUS requirements) is unknown. This study aimed to compare PPB vs. conventional plant breeding of pea (Pisum sativum L.) targeted to organic systems of Italy, exploring phenotypic and genome-enabled selection approaches. Priority values assigned on a 0–5 scale to 14 traits by 18 farmers from Northern and Central Italy and six breeders were used to define weights of farmer and breeder selection indexes. Farmers and breeders attributed outmost importance to a visual acceptability score assigned a few weeks before crop maturity on a 1–9 scale, followed in importance by grain yield and tolerance to lodging. However, breeders and farmers differed (P < 0.05) for trait importance in a few cases. Five phenotypic selection criteria (farmer selection index; breeder selection index; average of farmer and breeder selection indexes; grain yield; farmer acceptability score) were applied onto 306 lines evaluated in two researcher-managed experiments of Northern and Central Italy under organic crop management, selecting overall nine lines per criterion that were tested in four organically-managed environments of the same regions and one conventionally-managed site. The farmer selection index exhibited greater selection efficiency (+23% based on yield gains over elite commercial cultivars under organic farming) and farmer's acceptability of selected material than the breeder selection index. Breeding values based on the farmer selection index or the farmer acceptability score exhibited greater correlation with grain yields in independent environments than those from breeder selection criteria. Compared with grain yield-based selection, selection for the farmer acceptability score performed comparably in terms of yield gains, and somewhat better according to correlations of its breeding values with line grain yields in independent environments. The accuracy of genome-enabled predictions issued by a Bayesian Lasso model with 3443 SNP markers generated by genotyping-by-sequencing, estimated by averaging cross-environment correlations between predicted and observed values over two locations, was very high for the farmer acceptability score (rAc = 0.77), and high for grain yield (rAc = 0.59). Genomic selection for the farmer acceptability score ranked first in a preliminary comparison of eight genome-enabled or phenotypic selection criteria based on correlations of breeding values with grain yields in independent environments, suggesting its adoption for preliminary screening of genotype sets that are too numerous for field-based evaluation
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
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