1,480 research outputs found
Spectral Analysis of a Four Mode Cluster State
We theoretically evaluate the squeezed joint operators produced in a single
optical parametric oscillator which generates quadripartite entangled outputs,
as demonstrated experimentally by Pysher et al. \cite{pysher}[Phys. Rev. Lett.
107, 030505 (2011)]. Using a linearized fluctuation analysis we calculate the
squeezing of the joint quadrature operators below threshold for a range of
local oscillator phases and frequencies. These results add to the existing
theoretical understanding of this potentially important system.Comment: 4 pages, 6 figure
Formative versus reflective measurement models: Two applications of formative measurement
This paper presents a framework that helps researchers to design and validate both formative and reflective measurement models. The framework draws from the existing literature and includes both theoretical and empirical considerations. Two important examples, one from international business and one from marketing, illustrate the use of the framework. Both examples concern constructs that are fundamental to theory-building in these disciplines, and constructs that most scholars measure reflectively. In contrast, applying the framework suggests that a formative measurement model may be more appropriate. These results reinforce the need for all researchers to justify, both theoretically and empirically, their choice of measurement model. Use of an incorrect measurement model undermines the content validity of constructs, misrepresents the structural relationships between them, and ultimately lowers the usefulness of management theories for business researchers and practitioners. The main contribution of this paper is to question the unthinking assumption of reflective measurement seen in much of the business literature
Quadripartite continuous-variable entanglement via quadruply concurrent downconversion
We investigate an intra-cavity coupled down-conversion scheme to generate
quadripartite entanglement using concurrently resonant nonlinearities. We
verify that quadripartite entanglement is present in this system by calculating
the output fluctuation spectra and then considering violations of optimized
inequalities of the van Loock-Furusawa type. The entanglement characteristics
both above and below the oscillation threshold are considered. We also present
analytic solutions for the quadrature operators and the van Loock-Furusawa
correlations in the undepleted pump approximation.Comment: 9 pages, 5 figure
A comparative study of dynamical simulation methods for the dissociation of molecular Bose-Einstein condensates
We describe a pairing mean-field theory related to the
Hartree-Fock-Bogoliubov approach, and apply it to the dynamics of dissociation
of a molecular Bose-Einstein condensate (BEC) into correlated bosonic atom
pairs. We also perform the same simulation using two stochastic phase-space
techniques for quantum dynamics -- the positive P-representation method and the
truncated Wigner method. By comparing the results of our calculations we are
able to assess the relative strength of these theoretical techniques in
describing molecular dissociation in one spatial dimension. An important aspect
of our analysis is the inclusion of atom-atom interactions which can be
problematic for the positive-P method. We find that the truncated Wigner method
mostly agrees with the positive-P simulations, but can be simulated for
significantly longer times. The pairing mean-field theory results diverge from
the quantum dynamical methods after relatively short times.Comment: 11 pages, 7 figures, corrected typos, minor content change
Analysis of a continuous-variable quadripartite cluster state from a single optical parametric oscillator
We examine the feasibility of generating continuous-variable multipartite
entanglement in an intra-cavity quadruply concurrent downconversion scheme that
has been proposed for the generation of cluster states by Menicucci \textit{et
al.} [Physical Review Letters \textbf{101}, 130501 (2008)]. By calculating
optimized versions of the van Loock-Furusawa correlations we demonstrate
genuine quadripartite entanglement and investigate the degree of entanglement
present. Above the oscillation threshold the basic cluster state geometry under
consideration suffers from phase diffusion. We alleviate this problem by
incorporating a small injected signal into our analysis. Finally, we
investigate squeezed joint operators. While the squeezed joint operators
approach zero in the undepleted regime, we find that this is not the case when
we consider the full interaction Hamiltonian and the presence of a cavity. In
fact, we find that the decay of these operators is minimal in a cavity, and
even depletion alone inhibits cluster state formation.Comment: 26 pages, 12 figure
Improving estimates of growth for pearl perch (Glaucosoma scapulare) in Queensland, Australia
The pearl perch (Glaucosoma scapulare) is endemic to the east coast of Australia in depths to 150 m. The species has a long history of exploitation, and the stock is currently depleted. Previous research indicated the species is long lived and slow growing based on fishery-dependent sampling undertaken in the late 1990s and early 2000s on traditional fishing grounds at the southern end of the species’ range. Increasing fishing power has facilitated the expansion of the fishery to areas to the north and east of traditional grounds, which has resulted in the appearance of older fish (>10 yr) in fishery-dependent samples not previously observed. The current study estimated the growth parameters using 1153 length-at-age observations from fish collected in Queensland between January 2020 and December 2021. The lack of significant numbers of individuals at either end of the age frequency distribution necessitated the estimation of growth in a Bayesian framework with informative priors for length-at-age-zero and maximum length using a multi-model approach. The von Bertalanffy growth function (VBGF) was found to best fit the observed length-at-age data and the estimated VBGF parameters were L∞ = 562 mm FL, L0 = 2.02 mm FL and k = 0.295 yr−1. The high proportion of older fish in samples, combined with prior information on relevant parameters, improves growth parameter estimation by reducing bias and facilitating improved model fits to observed length-at-age data
Improving estimates of growth for pearl perch (Glaucosoma scapulare) in Queensland, Australia
Abstract The pearl perch (Glaucosoma scapulare) is endemic to the east coast of Australia in depths to 150 m. The species has a long history of exploitation, and the stock is currently depleted. Previous research indicated the species is long lived and slow growing based on fishery-dependent sampling undertaken in the late 1990s and early 2000s on traditional fishing grounds at the southern end of the species’ range. Increasing fishing power has facilitated the expansion of the fishery to areas to the north and east of traditional grounds, which has resulted in the appearance of older fish (>10 yr) in fishery-dependent samples not previously observed. The current study estimated the growth parameters using 1153 length-at-age observations from fish collected in Queensland between January 2020 and December 2021. The lack of significant numbers of individuals at either end of the age frequency distribution necessitated the estimation of growth in a Bayesian framework with informative priors for length-at-age-zero and maximum length using a multi-model approach. The von Bertalanffy growth function (VBGF) was found to best fit the observed length-at-age data and the estimated VBGF parameters were L∞ = 562 mm FL, L0 = 2.02 mm FL and k = 0.295 yr−1. The high proportion of older fish in samples, combined with prior information on relevant parameters, improves growth parameter estimation by reducing bias and facilitating improved model fits to observed length-at-age data
Managerial beliefs, market contestability and dominant strategic orientation in the eclectic paradigm
Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation: Special Report of the Intergovernmental Panel on Climate Change
This Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) has been jointly coordinated by Working Groups I (WGI) and II (WGII) of the Intergovernmental Panel on Climate Change (IPCC). The report focuses on the relationship between climate change and extreme weather and climate events, the impacts of such events, and the strategies to manage the associated risks. The IPCC was jointly established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), in particular to assess in a comprehensive, objective, and transparent manner all the relevant scientific, technical, and socioeconomic information to contribute in understanding the scientific basis of risk of human-induced climate change, the potential impacts, and the adaptation and mitigation options. Beginning in 1990, the IPCC has produced a series of Assessment Reports, Special Reports, Technical Papers, methodologies, and other key documents which have since become the standard references for policymakers and scientists.This Special Report, in particular, contributes to frame the challenge of dealing with extreme weather and climate events as an issue in decisionmaking under uncertainty, analyzing response in the context of risk management. The report consists of nine chapters, covering risk management; observed and projected changes in extreme weather and climate events; exposure and vulnerability to as well as losses resulting from such events; adaptation options from the local to the international scale; the role of sustainable development in modulating risks; and insights from specific case studies
Draft Genome Sequence Of The Biosurfactant-producing Bacterium Gordonia Amicalis Strain Ccma-559, Isolated From Petroleum-impacted Sediment.
Gordonia amicalis strain CCMA-559 was isolated from an oil-contaminated mangrove swamp and shown to produce biosurfactants. This strain is a strict aerobe that readily degrades an array of carbon sources, including N-acetylglucosamine, cellobiose, Tween 80, and 4-hydroxybenzoic acid, and, like other G. amicalis strains, likely desulfurizes dibenzothiophene.
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