15,943 research outputs found

    Inter-image matching

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    Interimage matching is the process of determining the geometric transformation required to conform spatially one image to another. In principle, the parameters of that transformation are varied until some measure of some difference between the two images is minimized or some measure of sameness (e.g., cross-correlation) is maximized. The number of such parameters to vary is faily large (six for merely an affine transformation), and it is customary to attempt an a priori transformation reducing the complexity of the residual transformation or subdivide the image into small enough match zones (control points or patches) that a simple transformation (e.g., pure translation) is applicable, yet large enough to facilitate matching. In the latter case, a complex mapping function is fit to the results (e.g., translation offsets) in all the patches. The methods reviewed have all chosen one or both of the above options, ranging from a priori along-line correction for line-dependent effects (the high-frequency correction) to a full sensor-to-geobase transformation with subsequent subdivision into a grid of match points

    Mapping the stability field of Jupiter Trojans

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    Jupiter Trojans are a remnant of outer solar system planetesimals captured into stable or quasistable libration about the 1:1 resonance with the mean motion of Jupiter. The observed swarms of Trojans may provide insight into the original mass of condensed solids in the zone from which the Jovian planets accumulated, provided that the mechanisms of capture can be understood. As the first step toward this understanding, the stability field of Trojans were mapped in the coordinate proper eccentricity, e(sub p), and libration amplitude, D. To accomplish this mapping, the orbits of 100 particles with e(sub p) in the range of 0 to 0.8 and D in the range 0 to 140 deg were numerically integrated. Orbits of the Sun, the four Jovian planets, and the massless particles were integrated as a full N-body system, in a barycentric frame using fourth order symplectic scheme

    Genomic prediction and quantitative trait locus discovery in a cassava training population constructed from multiple breeding stages

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    Open Access Article; Published online: 11 Dec 2019Assembly of a training population (TP) is an important component of effective genomic selection‐based breeding programs. In this study, we examined the power of diverse germplasm assembled from two cassava (Manihot esculenta Crantz) breeding programs in Tanzania at different breeding stages to predict traits and discover quantitative trait loci (QTL). This is the first genomic selection and genome‐wide association study (GWAS) on Tanzanian cassava data. We detected QTL associated with cassava mosaic disease (CMD) resistance on chromosomes 12 and 16; QTL conferring resistance to cassava brown streak disease (CBSD) on chromosomes 9 and 11; and QTL on chromosomes 2, 3, 8, and 10 associated with resistance to CBSD for root necrosis. We detected a QTL on chromosome 4 and two QTL on chromosome 12 conferring dual resistance to CMD and CBSD. The use of clones in the same stage to construct TPs provided higher trait prediction accuracy than TPs with a mixture of clones from multiple breeding stages. Moreover, clones in the early breeding stage provided more reliable trait prediction accuracy and are better candidates for constructing a TP. Although larger TP sizes have been associated with improved accuracy, in this study, adding clones from Kibaha to those from Ukiriguru and vice versa did not improve the prediction accuracy of either population. Including the Ugandan TP in either population did not improve trait prediction accuracy. This study applied genomic prediction to understand the implications of constructing TP from clones at different breeding stages pooled from different locations on trait accuracy

    Estimation of (co)variance components for Jersey type traits using a repeatability model

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    (Co)variance components for final score and 15 linear type traits of Jersey cows were estimated by multitrait REML using multiple diagonalization and a repeatability model with 34,999 records of 22,354 cows. Multiple diagonalization gave relative off-diagonals (ratio of squared off-diagonals to the product of diagonals) of <0.1%. Heritabilities and repeatabilities, respectively, were estimated as 0.29 and 0.48 for final score, 0.40 and 0.57 for stature, 0.26 and 0.39 for strength, 0.28 and 0.43 for dairy form, 0.13 and 0.25 for foot angle, 0.13 and 0.25 for rear legs (side view), 0.27 and 0.41 for body depth, 0.31 and 0.52 for rump angle, 0.22 and 0.33 for thurl width, 0.22 and 0.36 for fore udder attachment, 0.28 and 0.46 for rear udder height, 0.26 and 0.42 for rear udder width, 0.32 and 0.48 for udder depth, 0.20 and 0.36 for udder cleft, 0.29 and 0.46 for front teat placement, and 0.31 and 0.48 for teat length. Estimates of heritability generally were higher, and estimates of repeatability were lower, than values used previously for USDA genetic evaluations, which were based on data from the 1970s and early 1980s. Final score was highly correlated both genetically and phenotypically with dairy form and rear udder traits. These estimates of heritabilities and (co)variance components are necessary for multitrait genetic evaluation of linear type traits of US Jerseys

    A Description of the Third Instar of Platambus flavovittaus (Larson and Wolfe, 1998) with Comments on the Larval Morphology of Platambus stagninus (Say, 1823) and a Key to the Agabini (Coleoptera: Dytiscidae) of Georgia

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    Mature Agabini larvae collected from a small temporary road-side habitat were reared to the adult stage and identified as Platambus flavovittattus (Larson and Wolfe, 1998). The mature larva is described and illustrated with an emphasis on leg morphology. Important differences between cranial temporal curvatures of P. flavovittatus and P. stagninus (Say, 1823) are described. A larval key is constructed to facilitate identification of Georgia agabine genera and species

    Phylotranscriptomics to Bring the Understudied into the Fold: Monophyletic Ostracoda, Fossil Placement, and Pancrustacean Phylogeny

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    An ambitious, yet fundamental goal for comparative biology is to understand the evolutionary relationships for all of life. However, many important taxonomic groups have remained recalcitrant to inclusion into broader scale studies. Here, we focus on collection of 9 new 454 transcriptome data sets from Ostracoda, an ancient and diverse group with a dense fossil record, which is often undersampled in broader studies. We combine the new transcriptomes with a new morphological matrix (including fossils) and existing expressed sequence tag, mitochondrial genome, nuclear genome, and ribosomal DNA data. Our analyses lead to new insights into ostracod and pancrustacean phylogeny. We obtained support for three epic pancrustacean clades that likely originated in the Cambrian: Oligostraca (Ostracoda, Mystacocarida, Branchiura, and Pentastomida); Multicrustacea (Copepoda, Malacostraca, and Thecostraca); and a clade we refer to as Allotriocarida (Hexapoda, Remipedia, Cephalocarida, and Branchiopoda). Within the Oligostraca clade, our results support the unresolved question of ostracod monophyly. Within Multicrustacea, we find support for Thecostraca plus Copepoda, for which we suggest the name Hexanauplia. Within Allotriocarida, some analyses support the hypothesis that Remipedia is the sister taxon to Hexapoda, but others support Branchiopoda + Cephalocarida as the sister group of hexapods. In multiple different analyses, we see better support for equivocal nodes using slow-evolving genes or when excluding distant outgroups, highlighting the increased importance of conditional data combination in this age of abundant, often anonymous data. However, when we analyze the same set of species and ignore rate of gene evolution, we find higher support when including all data, more in line with a “total evidence” philosophy. By concatenating molecular and morphological data, we place pancrustacean fossils in the phylogeny, which can be used for studies of divergence times in Pancrustacea, Arthropoda, or Metazoa. Our results and new data will allow for attributes of Ostracoda, such as its amazing fossil record and diverse biology, to be leveraged in broader scale comparative studies. Further, we illustrate how adding extensive next-generation sequence data from understudied groups can yield important new phylo- genetic insights into long-standing questions, especially when carefully analyzed in combination with other data

    Using legume-based mixtures to enhance the nitrogen use efficiency and economic viability of cropping systems - Final report (LK09106/HGCA3447)

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    As costs for mineral fertilisers rise, legume-based leys are recognised as a potential alternative nitrogen source for crops. Here we demonstrate that including species-rich legume-based leys in rotations helps to maximise synergies between agricultural productivity and other ecosystem services. By using functionally diverse plant species mixtures, these services can be optimised and fine-tuned to regional and farm-specific needs. Replicated field experiments were conducted over three years at multiple locations, testing the performance of 12 legume species and 4 grass species sown in monocultures, as well as in a mixture of 10 of the legumes and all 4 grasses (called the All Species Mix, ASM). In addition, we compared this complex mixture to farmer-chosen ley mixtures on 34 sites across the UK. The trials showed that there is a large degree of functional complementarity among the legume species. No single species scored high on all evaluation criteria. In particular, the currently most frequently used species, white clover, is outscored by other legume species on a number of parameters such as early development and resistance to decomposition. Further complementarity emerged from the different responses of legume species to environmental variables, with soil pH and grazing or cutting regime being among the more important factors. For example, while large birdsfoot trefoil showed better performance on more acidic soils, the opposite was true for sainfoin, lucerne and black medic. In comparison with the monocultures, the ASM showed increased ground cover, increased above-ground biomass and reduced weed biomass. Benefits of mixing species with regard to productivity increased over time. In addition, the stability of biomass production across sites was greater in the ASM than in the legume monocultures. Within the on-farm trials, we further found that on soils low in organic matter the biomass advantage of the ASM over the Control ley was more marked than on the soils with higher organic matter content. Ecological modelling revealed that the three best multifunctional mixtures all contained black medic, lucerne and red clover. Within the long term New Farming Systems (NFS) rotational study, the use of a clover bi-crop showed improvement to soil characteristics compared to current practice (e.g. bulk density and water infiltration rate). Improvements in wheat yield were also noted with respect to the inclusion of a clover bi-crop in 2010, but there was evidence of a decline in response as the N dose was increased. Cumulatively, over both the wheat crop and the spring oilseed rape crop, the clover bi-crop improved margin over N. The highest average yield response (~9%) was associated with the ASM legume species mix cover cropping approach

    Dynamics of the spontaneous breakdown of superhydrophobicity

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    Drops deposited on rough and hydrophobic surfaces can stay suspended with gas pockets underneath the liquid, then showing very low hydrodynamic resistance. When this superhydrophobic state breaks down, the subsequent wetting process can show different dynamical properties. A suitable choice of the geometry can make the wetting front propagate in a stepwise manner leading to {\it square-shaped} wetted area: the front propagation is slow and the patterned surface fills by rows through a {\it zipping} mechanism. The multiple time scale scenario of this wetting process is experimentally characterized and compared to numerical simulations.Comment: 7 pages, 5 figure
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