16,793 research outputs found

    Design of Marine Protected Areas on high seas and territorial waters of rockall bank

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    Fisheries closures are rapidly being developed to protect vulnerable marine ecosystems worldwide. Satellite monitoring of fishing vessel activity indicates that these closures can work effectively with good compliance by international fleets even in remote areas. Here we summarise how remote fisheries closures were designed to protect Lophelia pertusa habitat in a region of the NE Atlantic that straddles the EU fishing zone and the high seas. We show how scientific records, fishers' knowledge and surveillance data on fishing activity can be combined to provide a powerful tool for the design of Marine Protected Areas. © Inter-Research 2009

    The effect of quantization on the FCIQMC sign problem

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    The sign problem in Full Configuration Interaction Quantum Monte Carlo (FCIQMC) without annihilation can be understood as an instability of the psi-particle population to the ground state of the matrix obtained by making all off-diagonal elements of the Hamiltonian negative. Such a matrix, and hence the sign problem, is basis dependent. In this paper we discuss the properties of a physically important basis choice: first versus second quantization. For a given choice of single-particle orbitals, we identify the conditions under which the fermion sign problem in the second quantized basis of antisymmetric Slater determinants is identical to the sign problem in the first quantized basis of unsymmetrized Hartree products. We also show that, when the two differ, the fermion sign problem is always less severe in the second quantized basis. This supports the idea that FCIQMC, even in the absence of annihilation, improves the sign problem relative to first quantized methods. Finally, we point out some theoretically interesting classes of Hamiltonians where first and second quantized sign problems differ, and others where they do not.Comment: 4 pages w/ 2 page appendix, 2 figures, 1 tabl

    Video Self-reflection and Coach Development in New Zealand

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    Drawing on data from semi-structured interviews with New Zealand coaches (N = 6), this study examined how video self-reflection (VSR) was perceived as a tool for learning within ‘on-going’ coach development. This study also looked to determine the potential barriers experienced by coaches before engaging in VSR. Each participant was a performance coach (as identified by the NZ coach development framework (CDF)) with 5+ years coaching experience and had recently (in the previous 12 months) participated in a coach development program that aligned with Sport NZ’s CDF. Five main themes emerged from the data; coaches had a positive perception of the benefits of VSR, a desire to engage in VSR but did not prioritise the time, logistical concerns, a fear of self-confrontation and evidence of knowledge for ‘modern’ coaching development. Findings indicated that coaches valued VSR as a tool for learning; however, the lack of exposure and experience in the process meant coaches did not value the practise enough to dedicate specific time towards it. This study provides an evidence-base that can be used to support National Governing Bodies coach development frameworks, and the modification of content to encourage the use of VSR as a tool for learning

    Costs of State Vehicle and Driver Licensing in Indiana: A Comparison with Other States

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    Spencer and Main\u27s contribution to Indiana Academy of the Social Sciences Proceedings, 1985

    Delivering speech and language therapy services to young people in custody

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    Introduction: When a caregiver is fully present with a person with intellectual disability, it leads to a rich relationship of greater understanding. The purpose of this research was to gain a better understanding of Presence through an exposure experience. Methods: The researcher engaged in an exposure experience of 1 month at a centre for adults with intellectual disability to experience the interaction between caregivers (n = 4) and residents (n = 10) and have reflective conversations with caregivers regarding their experience of providing care. She also kept a reflective journal and had several reflective conversations with a mentor, an expert in Presence. Thematic data analysis was employed. Results: Two main themes emerged, namely, ‘engaging in an exposure’ and ‘insights on Presence’. An exposure is a meaningful process of becoming aware. Presence is about recognising, awareness, perspective, connecting and attuning. Presence leads to good care but requires readiness in the caregiver. Management through relationship is important. Implications: The understanding gained from this research can be used to further refine the concept Presence, as experienced in the context of care for adults with intellectual disability. An in‐service training programme is offered for the caregivers at the centre regarding being present for one another and for the resident

    Accurate exchange-correlation energies for the warm dense electron gas

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    Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average NN-body density matrices for uniform electron gas systems of up to 10124^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the kk-space configuration path-integral formalism disagree by up to ∌\sim1010\% at certain reduced temperatures T/TF≀0.5T/T_F \le 0.5 and densities rs≀1r_s \le 1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that DMQMC can calculate free energies directly and present exact free energies for T/TF≄1T/T_F \ge 1 and rs≀2r_s \le 2.Comment: Accepted version: added free energy data and restructured text. Now includes supplementary materia

    Radio Observations of the Black Hole Candidate GX 339-4

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    The black hole candidate GX 339-4 was first detected as a variable radio source by Sood & Campbell-Wilson in May 1994 with the Molonglo Observatory Synthesis Telescope (MOST). Since then, several observations have been obtained with the Australian Telescope Compact Array (ATCA) in order to study the radio behavior of this source in relation to its soft and hard X-ray activity. We present new results of high resolution radio observations performed with the ATCA in order to study the jet-like feature observed in GX 339-4 by Fender et al (1997). From the ATCA lightcurve at 8640 MHz, we find evidence of quenched radio emission from GX 339-4.Comment: To appear in Proc. 4th Compton Symposium, AIP pres

    A Matrix Hyperbolic Cosine Algorithm and Applications

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    In this paper, we generalize Spencer's hyperbolic cosine algorithm to the matrix-valued setting. We apply the proposed algorithm to several problems by analyzing its computational efficiency under two special cases of matrices; one in which the matrices have a group structure and an other in which they have rank-one. As an application of the former case, we present a deterministic algorithm that, given the multiplication table of a finite group of size nn, it constructs an expanding Cayley graph of logarithmic degree in near-optimal O(n^2 log^3 n) time. For the latter case, we present a fast deterministic algorithm for spectral sparsification of positive semi-definite matrices, which implies an improved deterministic algorithm for spectral graph sparsification of dense graphs. In addition, we give an elementary connection between spectral sparsification of positive semi-definite matrices and element-wise matrix sparsification. As a consequence, we obtain improved element-wise sparsification algorithms for diagonally dominant-like matrices.Comment: 16 pages, simplified proof and corrected acknowledging of prior work in (current) Section

    Cold atom confinement in an all-optical dark ring trap

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    We demonstrate confinement of 85^{85}Rb atoms in a dark, toroidal optical trap. We use a spatial light modulator to convert a single blue-detuned Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a ring-shaped intensity null bounded harmonically in all directions. We measure a 1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For smaller detunings, a time-dependent relaxation rate is observed. We use these relaxation rate measurements and imaging diagnostics to optimize trap alignment in a programmable manner with the modulator. The results are compared with numerical simulations.Comment: 5 pages, 4 figure
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