242 research outputs found
Genome-enabled phylogeographic investigation of the quarantine pathogen Ralstonia solanacearum race 3 biovar 2 and screening for sources of resistance against its core effectors.
Phylogeographic studies inform about routes of pathogen dissemination and are instrumental for improving import/export controls. Genomes of seventeen isolates of the bacterial wilt and potato brown rot pathogen Ralstonia solanacearum race 3 biovar 2 (R3bv2), a select agent in the USA, were thus analyzed to get insight into the phylogeography of this pathogen. Thirteen of fourteen isolates from Europe, Africa, and Asia were found to belong to a single clonal lineage while isolates from South America were genetically diverse and carried ancestral alleles at the analyzed genomic loci consistent with a South American origin of R3bv2. The R3bv2 isolates share a core repertoire of thirty-one type III-secreted effector genes representing excellent candidates to be targeted with resistance genes in breeding programs to develop durable disease resistance. Towards this goal, 27 R3bv2 effectors were tested in eggplant, tomato, pepper, tobacco, and lettuce for induction of a hypersensitive-like response indicative of recognition by cognate resistance receptors. Fifteen effectors, eight of them core effectors, triggered a response in one or more plant species. These genotypes may harbor resistance genes that could be identified and mapped, cloned and expressed in tomato or potato, for which sources of genetic resistance to R3bv2 are extremely limited.National Science Foundatio
Shift invariant preduals of ℓ<sub>1</sub>(ℤ)
The Banach space ℓ<sub>1</sub>(ℤ) admits many non-isomorphic preduals, for
example, C(K) for any compact countable space K, along with many more
exotic Banach spaces. In this paper, we impose an extra condition: the predual
must make the bilateral shift on ℓ<sub>1</sub>(ℤ) weak<sup>*</sup>-continuous. This is
equivalent to making the natural convolution multiplication on ℓ<sub>1</sub>(ℤ)
separately weak*-continuous and so turning ℓ<sub>1</sub>(ℤ) into a dual Banach
algebra. We call such preduals <i>shift-invariant</i>. It is known that the
only shift-invariant predual arising from the standard duality between C<sub>0</sub>(K)
(for countable locally compact K) and ℓ<sub>1</sub>(ℤ) is c<sub>0</sub>(ℤ). We provide
an explicit construction of an uncountable family of distinct preduals which do
make the bilateral shift weak<sup>*</sup>-continuous. Using Szlenk index arguments, we
show that merely as Banach spaces, these are all isomorphic to c<sub>0</sub>. We then
build some theory to study such preduals, showing that they arise from certain
semigroup compactifications of ℤ. This allows us to produce a large number
of other examples, including non-isometric preduals, and preduals which are not
Banach space isomorphic to c<sub>0</sub>
Fabrication of a scaled MgB2 racetrack demonstrator pole for a 10 MW direct drive wind turbine generator
Field windings made of MgB2 wires or tapes are considered for their potential to reduce volume, weight and cost of large offshore wind turbine generators. To gain experience of how to use this relatively new material in full-scale generators, tests of different winding methodologies and techniques are needed. In this paper, we describe in detail the steps used to wind a racetrack coil with a length of 1 m and a width of 0.5 m out of 4.5 km of MgB2 superconducting tape. The width corresponds to a full-scale pole of a 10 MW generator, whereas the length of the straight section is shorter than the corresponding full-scale pole. The coil was built up of 10 double pancake coils. Each double pancake coil was wet-wound using a semi-automatic winding process, where Stycast 2850 was applied directly to the MgB2 tape without any other dedicated electrical insulation. The strengths and weaknesses of the winding process are discussed and compared to the dry-winding method.acceptedVersio
Fabrication of a scaled MgB2 racetrack demonstrator pole for a 10 MW direct drive wind turbine generator
Field windings made of MgB2 wires or tapes are considered for their potential to reduce volume, weight and cost of large offshore wind turbine generators. To gain experience of how to use this relatively new material in full-scale generators, tests of different winding methodologies and techniques are needed. In this paper, we describe in detail the steps used to wind a racetrack coil with a length of 1 m and a width of 0.5 m out of 4.5 km of MgB2 superconducting tape. The width corresponds to a full-scale pole of a 10 MW generator, whereas the length of the straight section is shorter than the corresponding full-scale pole. The coil was built up of 10 double pancake coils. Each double pancake coil was wet-wound using a semi-automatic winding process, where Stycast 2850 was applied directly to the MgB2 tape without any other dedicated electrical insulation. The strengths and weaknesses of the winding process are discussed and compared to the dry-winding method.acceptedVersio
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Structural trends and bonding of the 5Æ’-elements (U-Am) with the oxoligand I03-.
The solid state chemistry of transuranium compounds has received considerably less attention than their uranium analogs owing to decreased availability and the highly specialized facilities needed to safely study long-lived {alpha}-emitters. However, understanding the behavior of the early transuranium elements is critical for assessing their environmental impact as long-term contributors to radioactive dose in nuclear waste repositories. Of particular interest is how these elements might react with fission product radionuclides such as 129I, or their derivatives. In fact, iodine can exist in solution in both oxidized and reduced forms, i .e. as I03 and F, and studies on the nature of129I in nuclear waste suggested the existence of iodate, 103.
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Does the Millennium Challenge Corporation reinforce capitalist power structures or empower citizens?
In development practice, how does ‘mutual benefit’ accrue, and to whom? China criticises America for perpetuating capitalist power relations and claims it can seek a new geo-political order based on South-South cooperation. Meanwhile, there has been an extraordinary shift of emphasis toward the private sector as a driver of development, but this shift is attracting increasing criticism. The Millennium Challenge Corporation (MCC) - the only development agency to grow in influence under the Trump administration - is evaluated in the light of these two key themes. Neither China nor the private sector are successful in achieving ‘mutual benefit’ for ordinary citizens – both replicate existing power inequalities. As with the rise of both China and the private sector, the MCC also enmeshes developing countries further into the existing neoliberal capitalist structures. However, the advantages of the agency should not be dismissed outright, as its Ruling Justly and Investing in People indicators can enhance the capacity of citizens to challenge these power structures themselves
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