4,564 research outputs found

    Secure Sparse Gradient Aggregation in Distributed Architectures

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    Federated Learning allows multiple parties to train a model collaboratively while keeping data locally. Two main concerns when using Federated Learning are communication costs and privacy. A technique proposed to significantly reduce communication costs and increase privacy is Partial Weight Sharing (PWS). However, this method is insecure due to the possibility to reconstruct the original data from the partial gradients, called inversion attacks. In this paper, we propose a novel method to successfully combine these PWS and Secure Multi-Party Computation, a method for increasing privacy. This is done by making clients share the same part of their gradient, and adding noise to those entries, which are canceled on aggregation. We show that this method does not decrease the accuracy compared to existing methods while preserving privacy

    Non-exponential one-body loss in a Bose-Einstein condensate

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    We have studied the decay of a Bose-Einstein condensate of metastable helium atoms in an optical dipole trap. In the regime where two- and three-body losses can be neglected we show that the Bose-Einstein condensate and the thermal cloud show fundamentally different decay characteristics. The total number of atoms decays exponentially with time constant tau; however, the thermal cloud decays exponentially with time constant (4/3)tau and the condensate decays much faster, and non-exponentially. We show that this behaviour, which should be present for all BECs in thermal equilibrium with a considerable thermal fraction, is due to a transfer of atoms from the condensate to the thermal cloud during its decay.Comment: The intuitive explanation of the atomic transfer effect has been correcte

    Naar klimaatbestendige Natuur en Water in Groningen: Hotspot Klimaatbestendig Omgevingsplan Groningen

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    De effecten van klimaatverandering op natuur zijn op veel plekken in de wereld al duidelijk merkbaar. Zo wordt verwacht dat de boomgrens in Noord-Amerika door de opwarming van de aarde deze eeuw honderd kilometer naar het noorden zal opschuiven. Bij regionale adaptatie hebben we te maken met afgegrensde gebieden, zoals bijv. de provincie Groningen. We maken dan onderscheid tussen soorten die afnemen of toenemen in het gebied, afhankelijk van of hun omstandigheden zullen verslechteren of verbeteren. Een ander aspect van een veranderend klimaat is het optreden van meer weersextremen, met grotere aantalsfluctuaties als gevolg

    Transient but not genetic loss of miR-451 attenuates the development of pulmonary arterial hypertension

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    <b>Rationale:</b> MicroRNAs are small non-coding RNAs involved in the regulation of gene expression and have recently been implicated in the development of pulmonary arterial hypertension (PAH). Previous work established that miR-451 is up-regulated in rodent models of PAH.<p></p> <b>Objectives:</b> The role of miR-451 in the pulmonary circulation is unknown. We therefore sought to assess the involvement of miR-451 in the development of pulmonary arterial hypertension.<p></p> <b>Methods:</b> Silencing of miR-451 was performed in vivo using miR-451 knockout mice and an antimiR targeting mature miR-451 in rats. Coupled with exposure to hypoxia, indices of pulmonary arterial hypertension were assessed. The effect of modulating miR-451 on human pulmonary artery smooth muscle cell proliferation and migration was analysed.<p></p> <b>Measurements and Main Results:</b> We observed a reduction in systolic right ventricular pressure in hypoxic rats pre-treated with antimiR-451 compared to hypoxia alone (47.7 ± 1.36mmHg and 56.0 ± 2.03mmHg respectively, p<0.01). In miR-451 knockout mice following exposure to chronic hypoxia, no significant differences were observed compared to wild type hypoxic mice. In vitro analysis demonstrated that over-expression of miR-451 in human pulmonary artery smooth muscle cells promoted migration under serum-free conditions. No effect on cellular proliferation was observed.<p></p> <b>Conclusions:</b> Transient inhibition of miR-451 attenuated the development of pulmonary arterial hypertension in hypoxia exposed rats. Genetic deletion of miR-451 had no beneficial effect on indices of pulmonary arterial hypertension, potentially due to pathway redundancy compensating for the loss of miR-451.<p></p&gt

    Learning the Switching Rate by Discretising Bernoulli Sources Online

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    Magnetic-field dependent trap loss of ultracold metastable helium

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    We have experimentally studied the magnetic-field dependence of the decay of a Bose-Einstein condensate of metastable 4He atoms confined in an optical dipole trap, for atoms in the m=+1 and m=-1 magnetic substates, and up to 450 G. Our measurements confirm long-standing calculations of the two-body loss rate coefficient that show an increase above 50 G. We demonstrate that for m=-1 atoms, decay is due to three-body recombination only, with a three-body loss rate coefficient of 6.5(0.4)(0.6)10^(-27)cm^6s^(-1), which is interesting in the context of universal few-body theory. We have also searched for a recently-predicted d-wave Feshbach resonance, but did not observe it.Comment: 7 pages, 6 figure
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