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Automated delineation of smallholder farm fields is difficult because of their small size, irregular shape and the use of mixed-cropping systems. Edges between smallholder plots are often indistinct in satellite imagery and contours have to be identified by considering the transition of the complex textural patterns of the fields. We introduce a strategy to delineate field boundaries using a fully convolutional network in combination with a globalization and grouping algorithm to produce a hierarchical segmentation of the fields. We carry out an experimental analysis in a study area in Kofa, Nigeria, using a WorldView-3 image, comparing several state-of-the-art contour detection algorithms. The proposed strategy outperforms state-of-the-art computer vision methods and shows promising results by automatically delineating field boundaries with an accuracy close to human level photo-interpretation.

N2 - Automated delineation of smallholder farm fields is difficult because of their small size, irregular shape and the use of mixed-cropping systems. Edges between smallholder plots are often indistinct in satellite imagery and contours have to be identified by considering the transition of the complex textural patterns of the fields. We introduce a strategy to delineate field boundaries using a fully convolutional network in combination with a globalization and grouping algorithm to produce a hierarchical segmentation of the fields. We carry out an experimental analysis in a study area in Kofa, Nigeria, using a WorldView-3 image, comparing several state-of-the-art contour detection algorithms. The proposed strategy outperforms state-of-the-art computer vision methods and shows promising results by automatically delineating field boundaries with an accuracy close to human level photo-interpretation.

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AB - Automated delineation of smallholder farm fields is difficult because of their small size, irregular shape and the use of mixed-cropping systems. Edges between smallholder plots are often indistinct in satellite imagery and contours have to be identified by considering the transition of the complex textural patterns of the fields. We introduce a strategy to delineate field boundaries using a fully convolutional network in combination with a globalization and grouping algorithm to produce a hierarchical segmentation of the fields. We carry out an experimental analysis in a study area in Kofa, Nigeria, using a WorldView-3 image, comparing several state-of-the-art contour detection algorithms. The proposed strategy outperforms state-of-the-art computer vision methods and shows promising results by automatically delineating field boundaries with an accuracy close to human level photo-interpretation.

There are two heterogenous core design options for thorium based fuel cycle in PWRs. One of them is Whole Assembly Seed and Blanket (WASB) design. In WASB design, seed units and blanket units separately occupy one full-size PWR assembly each, and the assemblies are arranged in the core in a modified checkerboard array. In this study, the seed units was loaded with UO2 fuel rods and the blanket units was loaded with ThO2-UO2 . The configuration for each assemblies in both seed and blanket units were based on 17x17 KOFA (Korean Standard Fuel Assembly). Neutronics calculation was performed by using PIJ and CITATION modules of SRAC 2006 code with JENDL 3.3 as nuclear data library. The calculation showed that for the same fuel material configuration in each asssembly uints the WASB-I core loading pattern produce a better power distribution than WASB-II core loading pattern. The criticality condition for both core loading patterns can be achieved by loading 4.95 wt.% of enriched-U in seed fuel assemblies while blanket fuel assemblies were loaded by 20 % UO2 (15 wt.% of enriched-U ) and 80% ThO2.

Interpretive Summary: Some durum wheat cultivars have the genetic propensity to accumulate cadmium (Cd) in the grain. A major gene controlling grain Cd concentration designated as Cdu1 has been reported on durum chromosome 5B. The objectives of this study were to saturate the chromosomal region harboring Cdu1 with molecular markers and to investigate evolutionary relatedness of this wheat chromosomal region with regions of the rice and Brachypodium genomes. The precise physical and genetic chromosomal location of Cdu1 was determined, and new molecular markers were developed that co-segregated with Cdu1. Also, physical segments of rice chromosome 3 and of Brachypodium chromosome 1 that are evolutionarily conserved with the Cdu1 chromosomal region were identified. The molecular markers and the conserved regions of the rice and Brachypodium genomes described here represent tools that will assist in the isolation of Cdu1 and can be used to select for low Cd accumulation in durum wheat breeding programs targeting this trait. The isolation of Cdu1 will further our knowledge of Cd accumulation in cereals as well as metal accumulation in general.

Technical Abstract: Some durum wheat (Triticum turgidum L. var durum) cultivars have the genetic propensity to accumulate cadmium (Cd) in the grain. A major gene controlling grain Cd concentration designated as Cdu1 has been reported on 5B, but the genetic factor(s) conferring the low Cd phenotype are currently unknown. The objectives of this study were to saturate the chromosomal region harboring Cdu1 with newly developed PCR-based markers and to investigate the colinearity of this wheat chromosomal region with rice (Oryza sativa L.) and Brachypodium distachyon genomes. Genetic mapping of grain Cd concentration in two environments coupled with chromosome localization in aneuploid stocks indicated that the Cdu1 gene(s) associated with variation in Cd concentration resides in wheat bin 5BL9 between fraction breakpoints 0.76 and 0.79. Genetic mapping and QTL analysis of grain Cd concentration performed in 155 doubled haploid lines from the cross Kofa (high Cd) by W9262-260D3 (low Cd) revealed two expressed sequence tag markers (ESMs) and one sequence tagged site (STS) marker that co-segregated with Cdu1 and explained >80% of the phenotypic variation in grain Cd concentration. A second, minor QTL for grain Cd concentration was also identified on 5B, 67 cM distal to Cdu1. The Cdu1 interval spans 286 Kbp of rice chromosome 3 and 282 Kbp of Brachypodium chromosome 1. The markers and rice and Brachypodium colinearity described here represent tools that will assist in the positional cloning of Cdu1 and can be used to select for low Cd accumulation in durum wheat breeding programs targeting this trait. The isolation of Cdu1 will further our knowledge of Cd accumulation in cereals as well as metal accumulation in general.

Wheat stem rust caused by Puccinia graminis f. sp. tritici, can cause significant yield losses. To combat the disease, breeders have deployed resistance genes both individually and in combinations to increase resistance durability. A new race, TTKSK (Ug99), identified in Uganda in 1999 is virulent on most of the resistance genes currently deployed, and is rapidly spreading to other regions of the world. It is therefore important to identify, map, and deploy resistance genes that are still effective against TTKSK. One of these resistance genes, Sr13, was previously assigned to the long arm of chromosome 6A, but its precise map location was not known. In this study, the genome location of Sr13 was determined in four tetraploid wheat (T. turgidum ssp. durum) mapping populations involving the TTKSK resistant varieties Kronos, Kofa, Medora and Sceptre. Our results showed that resistance was linked to common molecular markers in all four populations, suggesting that these durum lines carry the same resistance gene. Based on its chromosome location and infection types against different races of stem rust, this gene is postulated to be Sr13. Sr13 was mapped within a 1.2-2.8 cM interval (depending on the mapping population) between EST markers CD926040 and BE471213, which corresponds to a 285-kb region in rice chromosome 2, and a 3.1-Mb region in Brachypodium chromosome 3. These maps will be the foundation for developing high-density maps, identifying diagnostic markers, and positional cloning of Sr13. e24fc04721