15,294 research outputs found
Genomic selection in rubber tree breeding: A comparison of models and methods for managing GĂE interactions
Several genomic prediction models combining genotype Ă environment (GĂE) interactions have recently been developed and used for genomic selection (GS) in plant breeding programs. GĂE interactions reduce selection accuracy and limit genetic gains in plant breeding. Two data sets were used to compare the prediction abilities of multienvironment GĂE genomic models and two kernel methods. Specifically, a linear kernel, or GB (genomic best linear unbiased predictor [GBLUP]), and a nonlinear kernel, or Gaussian kernel (GK), were used to compare the prediction accuracies (PAs) of four genomic prediction models: 1) a single-environment, main genotypic effect model (SM); 2) a multienvironment, main genotypic effect model (MM); 3) a multienvironment, single-variance GĂE deviation model (MDs); and 4) a multienvironment, environment-specific variance GĂE deviation model (MDe). We evaluated the utility of genomic selection (GS) for 435 individual rubber trees at two sites and genotyped the individuals via genotyping-by-sequencing (GBS) of single-nucleotide polymorphisms (SNPs). Prediction models were used to estimate stem circumference (SC) during the first 4 years of tree development in conjunction with a broad-sense heritability (H2) of 0.60. Applying the model (SM, MM, MDs, and MDe) and kernel method (GB and GK) combinations to the rubber tree data revealed that the multienvironment models were superior to the single-environment genomic models, regardless of the kernel (GB or GK) used, suggesting that introducing interactions between markers and environmental conditions increases the proportion of variance explained by the model and, more importantly, the PA. Compared with the classic breeding method (CBM), methods in which GS is incorporated resulted in a 5-fold increase in response to selection for SC with multienvironment GS (MM, MDe, or MDs). Furthermore, GS resulted in a more balanced selection response for SC and contributed to a reduction in selection time when used in conjunction with traditional genetic breeding programs. Given the rapid advances in genotyping methods and their declining costs and given the overall costs of large-scale progeny testing and shortened breeding cycles, we expect GS to be implemented in rubber tree breeding programs
CLIMATE FORECASTING AND EMERGENCY POLICIES EVIDENCE OF OPPORTUNITIES FROM CEARĂ, BRAZIL
We take small steps towards the approximation between economic analysis and the science of climate forecasting in the formulation of policies to alleviate the impact of climatic shocks. We do so by estimating the relationship between climate variables and corn production in CearĂĄ, an important State in the Brazilian semi-arid. Using parametric and non-parametric regression models, we first estimate the relationship between contemporaneous sea surface temperatures (SSTs) for the Pacific and Atlantic oceans and the local rainfed corn market. Next, we investigate the forecasting potential of future corn production conditional on information on current SSTs. We find strong evidence that climate determinants are important in determining current and future corn production, a key indicator of the climatic stress to which a large number of small farmers are subject in the Brazilian semi-arid. Additionally, corn production in the region is negatively correlated with federal government transfers meant to mitigate the impact of local droughts. These resources have been subject to lethargic bureaucracies, corruption and economic inefficiencies in general. The observation and forecasting of corn production can be invaluable in the design of more efficient, expeditious and transparent policies to mitigate the effects of droughts in the region.
Pine wilt disease and red ring disease of coconut: opportunities and perspectives in the study of two nematodes Bursaphelenchus xylophilus and B. cocophilus.
The xylophagous nematodes Bursaphelenchus cocophilus and B. xylophilus (Nematoda: Parasitaphelenchidae), are causative agents of two serious diseases, âred ring diseaseâ (RRD) with great importance to coconut and certain oil palm species in Central and South America, and in âpine wilt diseaseâ (PWD), which has wreaked havoc in forest areas in the Far East and now more recently in Europe (Portugal and Spain). PWD has not yet been detected in Brasil or any other country in Central or South America, but there is great risk of introduction due to worldwide movement of wood and wood products through major sea ports. Recently, for example, wood shipments originating from Brasil, infested with B. xylophilus, have been intercepted in China. Due to the taxonomical proximity between these two nematodes (the only two plant pathogenic species within the genus Bursaphelenchus, containing nearly 100 species), the similarity of life cycles (with the insect vectors Rhynchophorus palmarum for B. cocophilus and Monochamus spp. for B. xylophilus) and the likely genomic and proteomic similarities, a comparative study between these two nematodes may provide important insights into understanding RRD, in particular through the genome sequencing of B. cocophilus, and comparison with the recently sequenced genome of B. xylophilus. Knowledge on specific pathogenicity genes, involved in the RRD process, combined with past and present knowledge, should be helpful in designing new and effective control methods for this major tropical disease of coconut and palm
Visualizing test diversity to support test optimisation
Diversity has been used as an effective criteria to optimise test suites for
cost-effective testing. Particularly, diversity-based (alternatively referred
to as similarity-based) techniques have the benefit of being generic and
applicable across different Systems Under Test (SUT), and have been used to
automatically select or prioritise large sets of test cases. However, it is a
challenge to feedback diversity information to developers and testers since
results are typically many-dimensional. Furthermore, the generality of
diversity-based approaches makes it harder to choose when and where to apply
them. In this paper we address these challenges by investigating: i) what are
the trade-off in using different sources of diversity (e.g., diversity of test
requirements or test scripts) to optimise large test suites, and ii) how
visualisation of test diversity data can assist testers for test optimisation
and improvement. We perform a case study on three industrial projects and
present quantitative results on the fault detection capabilities and redundancy
levels of different sets of test cases. Our key result is that test similarity
maps, based on pair-wise diversity calculations, helped industrial
practitioners identify issues with their test repositories and decide on
actions to improve. We conclude that the visualisation of diversity information
can assist testers in their maintenance and optimisation activities
âAINâT THAT THE SAME?â: INTERSECTIONALITY AND THE SUPPLEMENTS IN TONI MORRISONâS SULA.
This research aims at discussing what happens when the concept of the âsupplementâ, as discussed by Ki Namaste (1994), is interfered by intersectionality, as coined by KimberlĂ© Crenshaw (1991). More specifically, this research establishes a dialogue between the theory of intersectional feminism and deconstruction by analyzing an excerpt from Toni Morrisonâs Sula. This research shows how an argument between the characters Nel and Sulaâs relates to the theory of intersectionality by illustrating the ways in which both gender and race issues shape black womenâs experience. Moreover, this investigation argues that Sulaâs interpretation of her own experience of race and gender relates to the concept of the âsupplementâ because she exposes how traditional (white, male) notions of womanhood are flawed and allow the concept âmenâ to be supplemented. This analysis suggests that Sula exposes how the meanings imposed upon gender are blurred and socially constructed, contributing to their reinterpretation and questioning. From this perspective, this research argues that Sula (subconsciously) engages in deconstruction by breaking with structuralist binary thinking and showing how this line of thought is questionable. Furthermore, this work points out the belief that the meanings imposed upon what it means to be a woman and to what it means to be a man are âalways alreadyâ racialized. Finally, this research argues that, for Sula, the intersection of multiple forms of oppression gives her the possibility of agency, which indicates that âintersectionalityâ and âagencyâ seems to be somewhat intertwined
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