16,793 research outputs found
Design of Marine Protected Areas on high seas and territorial waters of rockall bank
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
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
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 âon-goingâ 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 NZâs 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 âmodernâ 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
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
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, âengaging in an exposureâ and âinsights on Presenceâ. 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 inâservice 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
Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average
-body density matrices for uniform electron gas systems of up to 10
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 -space configuration path-integral formalism disagree by up to
\% at certain reduced temperatures and densities . 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 and .Comment: Accepted version: added free energy data and restructured text. Now
includes supplementary materia
Radio Observations of the Black Hole Candidate GX 339-4
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
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 ,
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
We demonstrate confinement of 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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