856 research outputs found

    Projection of Markov measures may be Gibbsian

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    We study the induced measure obtained from a 1-step Markov measure, supported by a topological Markov chain, after the mapping of the original alphabet onto another one. We give sufficient conditions for the induced measure to be a Gibbs measure (in the sense of Bowen) when the factor system is again a topological Markov chain. This amounts to constructing, when it does exist, the induced potential and proving its Holder continuity. This is achieved through a matrix method. We provide examples and counterexamples to illustrate our results.Comment: 4 latex figure

    Cooling is hotting up in the UK

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    The cooling of buildings is currently responsible for about 20% of total electricity use worldwide. It is estimated that the electricity needed for cooling will more than triple by 2050. Despite this concerning outlook, little attention has been paid to cooling demand in policy and research in the United Kingdom (UK). The demand for space cooling in the UK’s domestic and non-domestic buildings is currently small—about 10% of total electricity use. However, this has the potential to increase as the climate warms and expectations of comfort grow. This paper reviews UK cooling demand and how this has been considered in energy policy. Following a thorough review of the existing literature using a cooling decarbonisation framework (Avoid, Improve and Shift), it is clear there is a limited understanding of the future UK cooling demand for domestic buildings in a warmer future as well as how policy makers and households should act. More importantly, this sector appears under-represented in the UK research and policy landscape compared to heating despite obvious technological crossovers associated with electrification. Several policy and research recommendations have been made based on these findings

    Delivery of a Salmonella Typhi Exotoxin from a Host Intracellular Compartment

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    SummarySalmonella Typhi, an exclusive human pathogen and the cause of typhoid fever, expresses a functional cytolethal distending toxin for which only the active subunit, CdtB, has been identified. Here, we show that PltA and PltB, which are encoded in the same pathogenicity islet as cdtB, associate with CdtB to form a multipartite toxin. PltA and PltB are homologs of components of the pertussis toxin, including its ADP-ribosyl transferase subunit. We also show that PltA and PltB are required for the delivery of CdtB from an intracellular compartment to target cells via autocrine and paracrine pathways. We hypothesize that this toxin, which we have named “typhoid toxin,” and its delivery mechanism may contribute to S. Typhi's unique virulence properties

    A contour integral approach to the computation of invariant pairs

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    We study some aspects of the invariant pair problem for matrix polynomials, as introduced by Betcke and Kressner [3] and by Beyn and Thümmler [6]. Invariant pairs extend the notion of eigenvalue–eigenvector pairs, providing a counterpart of invariant subspaces for the nonlinear case. We compute formulations for the condition numbers and the backward error for invariant pairs and solvents. We then adapt the Sakurai–Sugiura moment method [1] to the computation of invariant pairs, including some classes of problems that have multiple eigenvalues. Numerical refinement via a variant of Newton's method is also studied. Furthermore, we investigate the relation between the matrix solvent problem and the triangularization of matrix polynomials
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