2,714 research outputs found

    With Brexit, inward investment will fall in the UK

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    Supply chains cross borders many times before components go into a final product in any EU country, write David Bailey, Nigel Driffield and Michail Karoglo

    Brexit means inward investment to the UK will fall

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    Supply chains cross borders many times before components go into a final product in any EU country, write David Bailey, Nigel Driffield and Michail Karoglou. When the UK leaves the Single Market, it will be a less attractive destination for firms wanting to coordinate their resources. The devaluation of sterling also lowers the expected returns from UK investment when translated into the home country’s currency

    Stabilizer Reduction for Derived Stacks and Applications to Sheaf-Theoretic Invariants

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    We construct a canonical stabilizer reduction X~\widetilde{X} for any derived 11-algebraic stack XX over C\mathbb{C} as a sequence of derived Kirwan blow-ups, under mild natural conditions that include the existence of a good moduli space for the classical truncation XclX_{\mathrm{cl}}. Our construction naturally generalizes Kirwan's classical partial desingularization algorithm to the context of derived algebraic geometry. We prove that X~\widetilde{X} is a natural derived enhancement of the intrinsic stabilizer reduction constructed by Kiem, Li and the third author. Moreover, if XX is (1)(-1)-shifted symplectic, we show that the semi-perfect and almost perfect obstruction theory and their induced virtual fundamental cycle and virtual structure sheaf of X~cl\widetilde{X}_{\mathrm{cl}}, constructed by the same authors, are naturally induced by X~\widetilde{X} and its derived tangent complex. As a corollary, we give a fully derived perspective on generalized Donaldson-Thomas invariants of Calabi-Yau threefolds and define new generalized Vafa-Witten invariants for surfaces via Kirwan blow-ups.Comment: 68 pages. Comments welcome

    Meron configurations in easy-plane chiral magnets

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    We demonstrate the existence and study in detail the features of chiral bimerons which are static solutions in an easy-plane magnet with the Dzyaloshinskii-Moriya (DM) interaction. These are skyrmionic textures with an integer topological charge and they present essential analogies to the meron configurations introduced in the context of quark confinement in the O(3) nonlinear sigma-model. We employ a Moebius transformation to show that, for weak chirality, bimeron configurations approach Belavin-Polyakov (BP) solutions characterized by tightly bound vortex and antivortex parts of the same size. Stronger chirality induces different vortex and antivortex sizes and also a detachment of merons, suggesting the possibility for a topological phase transition. Exploiting the fact that bimerons of opposite topological charges may exist in the same material, we demonstrate numerically a mechanism to generate meron pairs

    Exact size counting in uniform population protocols in nearly logarithmic time

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    We study population protocols: networks of anonymous agents that interact under a scheduler that picks pairs of agents uniformly at random. The _size counting problem_ is that of calculating the exact number nn of agents in the population, assuming no leader (each agent starts in the same state). We give the first protocol that solves this problem in sublinear time. The protocol converges in O(lognloglogn)O(\log n \log \log n) time and uses O(n60)O(n^{60}) states (O(1)+60lognO(1) + 60 \log n bits of memory per agent) with probability 1O(loglognn)1-O(\frac{\log \log n}{n}). The time complexity is also O(lognloglogn)O(\log n \log \log n) in expectation. The time to converge is also O(lognloglogn)O(\log n \log \log n) in expectation. Crucially, unlike most published protocols with ω(1)\omega(1) states, our protocol is _uniform_: it uses the same transition algorithm for any population size, so does not need an estimate of the population size to be embedded into the algorithm. A sub-protocol is the first uniform sublinear-time leader election population protocol, taking O(lognloglogn)O(\log n \log \log n) time and O(n18)O(n^{18}) states. The state complexity of both the counting and leader election protocols can be reduced to O(n30)O(n^{30}) and O(n9)O(n^{9}) respectively, while increasing the time to O(log2n)O(\log^2 n)

    Eccentric exercise‑induced delayed onset trunk muscle soreness alters high‑density surface EMG‑torque relationships and lumbar kinematics

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    We aimed to assess high-density surface electromyography (HDsEMG)-torque relationships in the presence of delayed onset trunk muscle soreness (DOMS) and the effect of these relationships on torque steadiness (TS) and lumbar movement during concentric/eccentric submaximal trunk extension contractions. Twenty healthy individuals attended three laboratory sessions (24 h apart). HDsEMG signals were recorded unilaterally from the thoracolumbar erector spinae with two 64-electrode grids. HDsEMG-torque signal relationships were explored via coherence (0–5 Hz) and cross-correlation analyses. Principal component analysis was used for HDsEMG-data dimensionality reduction and improvement of HDsEMG-torque-based estimations. DOMS did not reduce either concentric or eccentric trunk extensor muscle strength. However, in the presence of DOMS, improved TS, alongside an altered HDsEMG-torque relationship and kinematic changes were observed, in a contraction dependent manner. For eccentric trunk extension, improved TS was observed, with greater lumbar flexion movement and a reduction in δ-band HDsEMG-torque coherence and cross-correlation. For concentric trunk extensions, TS improvements were observed alongside reduced thoracolumbar sagittal movement. DOMS does not seem to impair the ability to control trunk muscle force, however, perceived soreness induced changes in lumbar movement and muscle recruitment strategies, which could alter motor performance if the exposure to pain is maintained in the long term
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