25,996 research outputs found

    Standardized field testing of assistant robots in a Mars-like environment

    Get PDF
    Controlled testing on standard tasks and within standard environments can provide meaningful performance comparisons between robots of heterogeneous design. But because they must perform practical tasks in unstructured, and therefore non-standard, environments, the benefits of this approach have barely begun to accrue for field robots. This work describes a desert trial of six student prototypes of astronaut-support robots using a set of standardized engineering tests developed by the US National Institute of Standards and Technology (NIST), along with three operational tests in natural Mars-like terrain. The results suggest that standards developed for emergency response robots are also applicable to the astronaut support domain, yielding useful insights into the differences in capabilities between robots and real design improvements. The exercise shows the value of combining repeatable engineering tests with task-specific application-testing in the field

    Trends in fatal car-occupant accidents

    Get PDF

    Spin resonance in the superconducting state of Li1x_{1-x}Fex_{x}ODFe1y_{1-y}Se observed by neutron spectroscopy

    Full text link
    We have performed inelastic neutron scattering measurements on a powder sample of the superconductor lithium iron selenide hydroxide Li1x_{1-x}Fex_{x}ODFe1y_{1-y}Se (x0.16,y0.02x \simeq 0.16, y \simeq 0.02, Tc=41T_{\rm c} = 41\,K). The spectrum shows an enhanced intensity below TcT_{\rm c} over an energy range 0.64×2Δ<E<2Δ0.64\times2\Delta < E < 2\Delta, where Δ\Delta is the superconducting gap, with maxima at the wave vectors Q11.46Q_1 \simeq 1.46\,\AA1^{-1} and Q21.97Q_2 \simeq 1.97\,\AA1^{-1}. The behavior of this feature is consistent with the spin resonance mode found in other unconventional superconductors, and strongly resembles the spin resonance observed in the spectrum of the molecular-intercalated iron selenide, Li0.6_{0.6}(ND2_{2})0.2_{0.2}(ND3_{3})0.8_{0.8}Fe2_{2}Se2_{2}. The signal can be described with a characteristic two-dimensional wave vector (π,0.67π)(\pi, 0.67\pi) in the Brillouin zone of the iron square lattice, consistent with the nesting vector between electron Fermi sheets

    Follow-up after treatment for head and neck cancer: United Kingdom National Multidisciplinary Guidelines

    Get PDF
    This is the official guideline endorsed by the specialty associations involved in the care of head and neck cancer patients in the UK. In the absence of high-level evidence base for follow-up practices, the duration and frequency are often at the discretion of local centres. By reviewing the existing literature and collating experience from varying practices across the UK, this paper provides recommendations on the work up and management of lateral skull base cancer based on the existing evidence base for this rare condition

    Oceanic flow over varying bottom topography

    Get PDF
    A study has been made of steady barotropic flows on the β plane over a bottom topography that varies in a direction inclined to the circles of latitude. The solutions obtained, starting with both the Eulerian and the Lagrangian systems of equations, are shown to be identical in the case of flow over a single-depth discontinuity...

    Transform-limited X-ray pulse generation from a high-brightness self-amplified spontaneous-emission free-electron laser

    Get PDF
    A method to achieve high-brightness self-amplified spontaneous emission (HB-SASE) in the free-electron laser (FEL) is described. The method uses repeated nonequal electron beam delays to delocalize the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated, using linear theory and numerical simulations, that the radiation coherence length can be increased by approximately 2 orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft x-ray and near transform-limited pulses in the hard x-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research

    Control Plane Compression

    Full text link
    We develop an algorithm capable of compressing large networks into a smaller ones with similar control plane behavior: For every stable routing solution in the large, original network, there exists a corresponding solution in the compressed network, and vice versa. Our compression algorithm preserves a wide variety of network properties including reachability, loop freedom, and path length. Consequently, operators may speed up network analysis, based on simulation, emulation, or verification, by analyzing only the compressed network. Our approach is based on a new theory of control plane equivalence. We implement these ideas in a tool called Bonsai and apply it to real and synthetic networks. Bonsai can shrink real networks by over a factor of 5 and speed up analysis by several orders of magnitude.Comment: Extended version of the paper appearing in ACM SIGCOMM 201

    Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems

    Full text link
    A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon system with spherical symmetry is presented. Initial data are specified on the union of a space-like and null hypersurface. The development of the data is obtained with the combination of a constrained Cauchy evolution in the interior domain and a characteristic evolution in the exterior, asymptotically flat region. The matching interface between the space-like and characteristic foliations is constructed by imposing continuity conditions on metric, extrinsic curvature and scalar field variables, ensuring smoothness across the matching surface. The accuracy of the method is established for all ranges of M/RM/R, most notably, with a detailed comparison of invariant observables against reference solutions obtained with a calibrated, global, null algorithm.Comment: Submitted to Phys. Rev. D, 16 pages, revtex, 7 figures available at http://nr.astro.psu.edu:8080/preprints.htm

    Creating citizen-consumers? Public service reform and (un)willing selves

    No full text
    About the book: Postmodern theories heralded the "death of the subject", and thereby deeply contested our intuition that we are free and willing selves. In recent times, the (free) will has come under attack yet again. Findings from the neuro- and cognitive sciences claim the concept of will to be scientifically untenable, specifying that it is our brain rather than our 'self' which decides what we want to do. In spite of these challenges however, the willing self has come to take centre stage in our society: juridical and moral practices ascribing guilt, or the organization of everyday life attributing responsibilities, for instance, can hardly be understood without taking recourse to the willing subject. In this vein, the authors address topics such as the genealogy of the concept of willing selves, the discourse on agency in neuroscience and sociology, the political debate on volition within neoliberal and neoconservative regimes, approaches toward novel forms of relational responsibility as well as moral evaluations in conceptualizing autonomy
    corecore