9,619 research outputs found

    “Canada’s Roll of Honour”: Controversy over Casualty Notification and Publication During the Second World War

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    During the Second World War, the Canadian Army’s announcement of casualties to next–of–kin and the press often caused controversy. Even though the army tried to notify the family and public as quickly as possible, it could not always do so. Unofficial communications with the family, procedural failures, and more frequently press and censorship errors, cause occasional mistakes in casualty reporting. Moreover, the interests of Canada’s allies often prevented the timely publication of casualty names and figures, as in the aftermath of the Dieppe Raid, Sicily campaign and Normandy landings. These delays were often for alleged security reasons, sometimes with questionable justification. This led to widespread, albeit inaccurate, suspicion of political manipulation of this process by the Canadian Army and federal government

    Field-assisted doublon manipulation in the Hubbard model. A quantum doublon ratchet

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    For the fermionic Hubbard model at strong coupling, we demonstrate that directional transport of localized doublons (repulsively bound pairs of two particles occupying the same site of the crystal lattice) can be achieved by applying an unbiased ac field of time-asymmetric (sawtooth-like) shape. The mechanism involves a transition to intermediate states of virtually zero double occupation which are reached by splitting the doublon by fields of the order of the Hubbard interaction. The process is discussed on the basis of numerically exact calculations for small clusters, and we apply it to more complex states to manipulate the charge order pattern of one-dimensional systems.Comment: 6 pages, 6 figure

    Second-order Shape Optimization for Geometric Inverse Problems in Vision

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    We develop a method for optimization in shape spaces, i.e., sets of surfaces modulo re-parametrization. Unlike previously proposed gradient flows, we achieve superlinear convergence rates through a subtle approximation of the shape Hessian, which is generally hard to compute and suffers from a series of degeneracies. Our analysis highlights the role of mean curvature motion in comparison with first-order schemes: instead of surface area, our approach penalizes deformation, either by its Dirichlet energy or total variation. Latter regularizer sparks the development of an alternating direction method of multipliers on triangular meshes. Therein, a conjugate-gradients solver enables us to bypass formation of the Gaussian normal equations appearing in the course of the overall optimization. We combine all of the aforementioned ideas in a versatile geometric variation-regularized Levenberg-Marquardt-type method applicable to a variety of shape functionals, depending on intrinsic properties of the surface such as normal field and curvature as well as its embedding into space. Promising experimental results are reported

    Turmoil in Russia's Mini-Empire

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    A Social Process in Science and its Content in a Simulation Program

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    We lay open a position concerning the difference between scientific processes and processes in science. Not all processes in science are scientific. This leads into the center of social simulation. More scientific theories should be incorporated in social simulations, and this should lead to more united structural approaches.Social Simulation, Process, Science, Theory, Social Science, Philosophy of Science
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