4,532 research outputs found

    Mendocino power plant site ecological study final report

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    A preoperational ecological study of a proposed nuclear power plant site on the Mendocino County coast was initiated in September 1971. The study resulted from an agreement between the Pacific Gas and Electric Company and the California Department of Fish and Game signed in July 1971. In the agreement, Pacific Gas and Electric Company provided funds for the Department's studies of the site. Studies of the subtidal animal and plant communities were conducted by divers from September 1971 through March 1973; intertidal animal and plant populations were surveyed from November 1971 through February 1973. Sportfisheries for abalone and finfish were surveyed during 1972 and Spring of 1973. Stomach contents of many of the more abundant subtidal and intertidal fishes were examined. All of these studies were designed to determine the dominant species of plants, invertebrates and fishes in the various communities, their relative abundance, and where applicable, size composition, predators and competitors. The parameters developed from these studies would be used for comparison with similar studies conducted after the proposed plant went into operation to determine what effect construction and operation of the plant might have on the various plants and animals studied. (291pp.

    Long-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot

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    The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large inter-pulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance for this system in the relevant parameter range. In situations where the initial electron state is known, protocols able to completely freeze decoherence at long times are constructed and characterized. The impact of system and control non-idealities is also assessed, including the effect of intra-bath dipolar interaction, magnetic field bias and bath polarization, as well as systematic pulse imperfections. While small bias field and small bath polarization degrade the decoupling fidelity, enhanced performance and temporal modulation result from strong applied fields and high polarizations. Overall, we find that if the relative errors of the control parameters do not exceed 5%, decoupling protocols can still prolong the coherence time by up to two orders of magnitude.Comment: 16 pages, 10 figures, submitted to Phys. Rev.

    Establishment of Requirements and Methodology for the Development and Implementation of GreyMatters, a Memory Clinic Information System

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    INTRODUCTION: The aim of the paper is to establish the requirements and methodology for the development process of GreyMatters, a memory clinic system, outlining the conceptual, practical, technical and ethical challenges, and the experiences of capturing clinical and research oriented data along with the implementation of the system. METHODS: The methodology for development of the information system involved phases of requirements gathering, modeling and prototype creation, and 'bench testing' the prototype with experts. The standard Institute of Electrical and Electronics Engineers (IEEE) recommended approach for the specifications of software requirements was adopted. An electronic health record (EHR) standard, EN13606 was used, and clinical modelling was done through archetypes and the project complied with data protection and privacy legislation. RESULTS: The requirements for GreyMatters were established. Though the initial development was complex, the requirements, methodology and standards adopted made the construction, deployment, adoption and population of a memory clinic and research database feasible. The electronic patient data including the assessment scales provides a rich source of objective data for audits and research and to establish study feasibility and identify potential participants for the clinical trials. CONCLUSION: The establishment of requirements and methodology, addressing issues of data security and confidentiality, future data compatibility and interoperability and medico-legal aspects such as access controls and audit trails, led to a robust and useful system. The evaluation supports that the system is an acceptable tool for clinical, administrative, and research use and forms a useful part of the wider information architecture

    Supervision and Scholarly Writing: Writing to Learn - Learning to Write

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    This paper describes an action research project on postgraduate students’ scholarly writing in which I employed reflective approaches to examine and enhance my postgraduate supervisory practice. My reflections on three distinct cycles of supervision illustrate a shift in thinking about scholarly writing and an evolving understanding of how to support postgraduate students’ writing. These understandings provide the foundation for a future-oriented fourth cycle of supervisory practice, which is characterised by three principles, namely the empowerment of students as writers, the technological context of contemporary writing, and ethical issues in writing

    Magneto-shear modes and a.c. dissipation in a two-dimensional Wigner crystal

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    The a.c. response of an unpinned and finite 2D Wigner crystal to electric fields at an angular frequency ω\omega has been calculated in the dissipative limit, ωτ≪1\omega \tau \ll 1, where τ−1\tau ^{-1} is the scattering rate. For electrons screened by parallel electrodes, in zero magnetic field the long-wavelength excitations are a diffusive longitudinal transmission line mode and a diffusive shear mode. A magnetic field couples these modes together to form two new magneto-shear modes. The dimensionless coupling parameter β=2(ct/cl)∣σxy/σxx∣\beta =2(c_{t}/c_{l})|\sigma_{xy}/\sigma_{xx}| where ctc_{t} and clc_{l} are the speeds of transverse and longitudinal sound in the collisionless limit and σxy\sigma_{xy} and σxx\sigma_{xx} are the tensor components of the magnetoconductivity. For β⩾1\beta \geqslant 1, both the coupled modes contribute to the response of 2D electrons in a Corbino disk measurement of magnetoconductivity. For β≫1\beta \gg 1, the electron crystal rotates rigidly in a magnetic field. In general, both the amplitude and phase of the measured a.c. currents are changed by the shear modulus. In principle, both the magnetoconductivity and the shear modulus can be measured simultaneously.Comment: REVTeX, 7 pp., 4 eps figure

    Deep Reinforcement Learning for Surgical Gesture Segmentation and Classification

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    Recognition of surgical gesture is crucial for surgical skill assessment and efficient surgery training. Prior works on this task are based on either variant graphical models such as HMMs and CRFs, or deep learning models such as Recurrent Neural Networks and Temporal Convolutional Networks. Most of the current approaches usually suffer from over-segmentation and therefore low segment-level edit scores. In contrast, we present an essentially different methodology by modeling the task as a sequential decision-making process. An intelligent agent is trained using reinforcement learning with hierarchical features from a deep model. Temporal consistency is integrated into our action design and reward mechanism to reduce over-segmentation errors. Experiments on JIGSAWS dataset demonstrate that the proposed method performs better than state-of-the-art methods in terms of the edit score and on par in frame-wise accuracy. Our code will be released later.Comment: 8 pages, 2 figures, accepted for MICCAI 201

    Retreating to nature : rethinking 'therapeutic landscapes'

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    There is a long history of removing oneself from ‘society’ in order to recuperate or repair. This paper considers a yoga and massage retreat in Southern Spain, and what opportunities this retreat experience might offer for recuperation and the creation of healthy bodies. The paper positions ‘nature’ as an active participant, and as ‘enrolled’ in the experiences of the retreat as a ‘therapeutic landscape’, and questions how and what particular aspects of yoga practice (in intimate relation with place) give rise to therapeutic experiences

    Working with simple machines

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    A set of examples is provided that illustrate the use of work as applied to simple machines. The ramp, pulley, lever and hydraulic press are common experiences in the life of a student and their theoretical analysis therefore makes the abstract concept of work more real. The mechanical advantage of each of these systems is also discussed so that students can evaluate their usefulness as machines.Comment: 9 pages, 4 figure

    Superconductivity and the high field ordered phase in the heavy fermion compound PrOs4_4Sb12_{12}

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    Superconductivity is observed in the filled skutterudite compound \PrOsSb{} below a critical temperature temperature Tc=1.85T_\mathrm{c} = 1.85 K and appears to develop out of a nonmagnetic heavy Fermi liquid with an effective mass m∗≈50mem^{*} \approx 50 m_\mathrm{e}, where mem_\mathrm{e} is the free electron mass. Features associated with a cubic crystalline electric field are present in magnetic susceptibility, specific heat, electrical resistivity, and inelastic neutron scattering measurements, yielding a Pr3+^{3+} energy level scheme consisting of a Γ3\Gamma_{3} nonmagnetic doublet ground state, a low lying Γ5\Gamma_{5} triplet excitied state at ∼10\sim 10 K, and much higher temperature Γ4\Gamma_{4} triplet and Γ1\Gamma_{1} singlet excited states. Measurements also indicate that the superconducting state is unconventional and consists of two distinct superconducting phases. At high fields and low temperatures, an ordered phase of magnetic or quadrupolar origin is observed, suggesting that the superconductivity may occur in the vicinity of a magnetic or quadrupolar quantum critical point.Comment: 11 pages, 4 figures, presented at the 3rd international symposium on Advance Science Research (ASR 2002), JAERI Tokai, Ibaraki, Japa
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