4,669 research outputs found

    Over 130 years of survival by a small, isolated population of Favia gravida corals at Ascension Island (South Atlantic)

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    info:eu-repo/semantics/publishedVersio

    The structure of colloidosomes with tunable particle density: simulation vs experiment

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    Colloidosomes are created in the laboratory from a Pickering emulsion of water droplets in oil. The colloidosomes have approximately the same diameter and by choosing (hairy) particles of different diameters it is possible to control the particle density on the droplets. The experiment is performed at room temperature. The radial distribution function of the assembly of (primary) particles on the water droplet is measured in the laboratory and in a computer experiment of a fluid model of particles with pairwise interactions on the surface of a sphere.Comment: 16 pages, 2 tables, 7 figure

    Dynamic Steerable Blocks in Deep Residual Networks

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    Filters in convolutional networks are typically parameterized in a pixel basis, that does not take prior knowledge about the visual world into account. We investigate the generalized notion of frames designed with image properties in mind, as alternatives to this parametrization. We show that frame-based ResNets and Densenets can improve performance on Cifar-10+ consistently, while having additional pleasant properties like steerability. By exploiting these transformation properties explicitly, we arrive at dynamic steerable blocks. They are an extension of residual blocks, that are able to seamlessly transform filters under pre-defined transformations, conditioned on the input at training and inference time. Dynamic steerable blocks learn the degree of invariance from data and locally adapt filters, allowing them to apply a different geometrical variant of the same filter to each location of the feature map. When evaluated on the Berkeley Segmentation contour detection dataset, our approach outperforms all competing approaches that do not utilize pre-training. Our results highlight the benefits of image-based regularization to deep networks

    Heisenberg antiferromagnet with anisotropic exchange on the Kagome lattice: Description of the magnetic properties of volborthite

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    We study the properties of the Heisenberg antiferromagnet with spatially anisotropic nearest-neighbour exchange couplings on the kagome net, i.e. with coupling J in one lattice direction and couplings J' along the other two directions. For J/J' > 1, this model is believed to describe the magnetic properties of the mineral volborthite. In the classical limit, it exhibits two kinds of ground states: a ferrimagnetic state for J/J' < 1/2 and a large manifold of canted spin states for J/J' > 1/2. To include quantum effects self-consistently, we investigate the Sp(N) symmetric generalisation of the original SU(2) symmetric model in the large-N limit. In addition to the dependence on the anisotropy, the Sp(N) symmetric model depends on a parameter kappa that measures the importance of quantum effects. Our numerical calculations reveal that in the kappa-J/J' plane, the system shows a rich phase diagram containing a ferrimagnetic phase, an incommensurate phase, and a decoupled chain phase, the latter two with short- and long-range order. We corroborate these results by showing that the boundaries between the various phases and several other features of the Sp(N) phase diagram can be determined by analytical calculations. Finally, the application of a block-spin perturbation expansion to the trimerised version of the original spin-1/2 model leads us to suggest that in the limit of strong anisotropy, J/J' >> 1, the ground state of the original model is a collinearly ordered antiferromagnet, which is separated from the incommensurate state by a quantum phase transition.Comment: 21 pages, 22 figures. Final version, PRB in pres

    Centrifugal stresses in arbitrarily laminated, rectangular—anistropic circular discs

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    The problem is formulated as one in the linear theory of thin, laminated, anisotropic elastic plates. A direct force-and-moment formulation is used, simplifying approximation is introduced and a closed-form solution is obtained. This solution exhibits bending-stretching coupling if the plate is asymmetrically laminated with respect to mass or stiffness or both. Numerical results typical of certain composite materials of current interest are presented. Specific laminates considered as examples include (1) glass—epoxy/steel, (2) cross-ply graphite—epoxy, and (3) various quasi-isotropic layups of organic fibre—epoxy.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Issues in providing a reliable multicast facility

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    Issues involved in point-to-multipoint communication are presented and the literature for proposed solutions and approaches surveyed. Particular attention is focused on the ideas and implementations that align with the requirements of the environment of interest. The attributes of multicast receiver groups that might lead to useful classifications, what the functionality of a management scheme should be, and how the group management module can be implemented are examined. The services that multicasting facilities can offer are presented, followed by mechanisms within the communications protocol that implements these services. The metrics of interest when evaluating a reliable multicast facility are identified and applied to four transport layer protocols that incorporate reliable multicast

    Introduction to price and productivity measurement for housing

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    This paper provides a brief introduction to a proposed new opportunity cost treatment of owner-occupied housing in measures of inflation for the United States. In addition, the paper introduces, and provides links to, a collection of nine other papers that discuss various aspects of the treatment of owner-occupied housing in measures of inflation for a number of nations, including Canada, Germany, Iceland, and the United States.Durable goods, Consumer ; Consumer price indexes ; Cost of living adjustments ; Housing

    All-optical switching of magnetic domains in Co/Gd heterostructures with Dzyaloshinskii-Moriya Interaction

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    Given the development of hybrid spintronic-photonic devices and chiral magnetic structures, a combined interest in all-optical switching (AOS) of magnetization and current-induced domain wall motion in synthetic ferrimagnetic structures with strong Dzyaloshinskii-Moriya Interaction (DMI) is emerging. In this study, we report a study on single-pulse all-optical toggle switching and asymmetric bubble expansion in specially engineered Co/Gd-based multilayer structures. In the absence of any external magnetic fields, we look into the AOS properties and the potential role of the DMI on the AOS process as well as the stability of optically written micro-magnetic domains. Particularly, interesting dynamics are observed in moon-shaped structures written by two successive laser pulses. The stability of domains resulting from an interplay of the dipolar interaction and domain-wall energy are compared to simple analytical models and micromagnetic simulations
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