578 research outputs found
Nonlinear deformed su(2) algebras involving two deforming functions
The most common nonlinear deformations of the su(2) Lie algebra, introduced
by Polychronakos and Ro\v cek, involve a single arbitrary function of J_0 and
include the quantum algebra su_q(2) as a special case. In the present
contribution, less common nonlinear deformations of su(2), introduced by
Delbecq and Quesne and involving two deforming functions of J_0, are reviewed.
Such algebras include Witten's quadratic deformation of su(2) as a special
case. Contrary to the former deformations, for which the spectrum of J_0 is
linear as for su(2), the latter give rise to exponential spectra, a property
that has aroused much interest in connection with some physical problems.
Another interesting algebra of this type, denoted by , has two
series of (N+1)-dimensional unitary irreducible representations, where N=0, 1,
2, .... To allow the coupling of any two such representations, a generalization
of the standard Hopf axioms is proposed. The resulting algebraic structure,
referred to as a two-colour quasitriangular Hopf algebra, is described.Comment: 8 pages, LaTeX, no figures, submitted to Proc. 5th Int. Coll.
``Quantum Groups and Integrable Systems'', Prague, 20-22 June 1996 (to be
published in Czech. J. Phys.
Expression, Purification, and Analysis of Unknown Translation Factors from Escherichia coli: A Synthesis Approach
New approaches are currently being developed to expose biochemistry and molecular biology undergraduates to a more interactive learning environment. Here, we propose a unique project-based laboratory module, which incorporates exposure to biophysical chemistry approaches to address problems in protein chemistry. Each of the experiments described herein contributes to the stepwise process of isolating, identifying, and analyzing a protein involved in a central biological process, prokaryotic translation. Students are provided with expression plasmids that harbor an unknown translation factor, and it is their charge to complete a series of experiments that will allow them to develop hypotheses for discovering the identity of their unknown (from a list of potential candidates). Subsequent to the identification of their unknown translation factor, a series of protein unfolding exercises are performed employing circular dichroism and fluorescence spectroscopies, allowing students to directly calculate thermodynamic parameters centered around determining the equilibrium constant for unfolding as a function of denaturant (temperature or chemical). The conclusion of this multi-part laboratory exercise consists of both oral and written presentations, emphasizing synthesis of the roles of each translation factor during the stepwise process of translation
Mapping the contribution of Allied Health Professions to the wider public health workforce : a rapid review of evidence-based interventions
Objectives: The objective was to identify a selection of the best examples of the public health contributions by Allied Health Professionals (AHPs) in order to encourage a wider awareness and participation from that workforce to public health practice.
Study design: A mapping exercise was used to identify evidence-based interventions that could lead to health improvements across a population.
Methods: A rapid review was undertaken to identify evidence, followed by a survey of Allied Health Profession (AHP) practitioners and an expert panel consensus method to select the examples of AHP public health interventions.
Results: Nine evidence-based interventions are identified and selected as examples of current AHP good practice. These examples represent a contribution to public health and include screening interventions, secondary prevention and risk management.
Conclusions: This study contributes to a strategy for AHPs in public health by appraising the effectiveness and impact of some exemplar AHP practices that contribute to health improvement. There is a need for AHPs to measure the impact of their interventions and to demonstrate evidence of outcomes at population level.
Keywords: allied health professions; Applied Health Professionals; evidence-based practice; health improvement; public health; rapid revie
A fast quantum interface between different spin qubit encodings
Single-spin qubits in semiconductor quantum dots proposed by Loss and
DiVincenzo (LD qubits) hold promise for universal quantum computation with
demonstrations of a high single-qubit gate fidelity above 99.9 % and two-qubit
gates in conjunction with a long coherence time. However, initialization and
readout of a qubit is orders of magnitude slower than control, which is
detrimental for implementing measurement-based protocols such as
error-correcting codes. In contrast, a singlet-triplet (ST) qubit, encoded in a
two-spin subspace, has the virtue of fast readout with high fidelity and
tunable coupling to the electric field. Here, we present a hybrid system which
benefits from the different advantages of these two distinct spin-qubit
implementations. A quantum interface between the two codes is realized by
electrically tunable inter-qubit exchange coupling. We demonstrate a
controlled-phase (CPHASE) gate that acts within 5.5 ns, much faster than the
measured dephasing time of 211 ns. The presented hybrid architecture will be
useful to settle remaining key problems with building scalable spin-based
quantum computers
Dynamically enhancing qubit-oscillator interactions with anti-squeezing
The interaction strength of an oscillator to a qubit grows with the
oscillator's vacuum field fluctuations. The well known degenerate parametric
oscillator has revived interest in the regime of strongly detuned squeezing,
where its eigenstates are squeezed Fock states. Owing to these amplified field
fluctuations, it was recently proposed that squeezing this oscillator would
dynamically boost its coupling to a qubit. In a superconducting circuit
experiment, we observe a two-fold increase in the dispersive interaction
between a qubit and an oscillator at 5.5 dB of squeezing, demonstrating in-situ
dynamical control of qubit-oscillator interactions. This work initiates the
experimental coupling of oscillators of squeezed photons to qubits, and
cautiously motivates their dissemination in experimental platforms seeking
enhanced interactions.Comment: 21 pages, 15 figure
A report on the nonlinear squeezed states and their non-classical properties of a generalized isotonic oscillator
We construct nonlinear squeezed states of a generalized isotonic oscillator
potential. We demonstrate the non-existence of dual counterpart of nonlinear
squeezed states in this system. We investigate statistical properties exhibited
by the squeezed states, in particular Mandel's parameter, second-order
correlation function, photon number distributions and parameter in
detail. We also examine the quadrature and amplitude-squared squeezing effects.
Finally, we derive expression for the -parameterized quasi-probability
distribution function of these states. All these information about the system
are new to the literature.Comment: Accepted for publication in J. Phys. A: Math. Theo
Long-Term Functionality of Rural Water Services in Developing Countries: A System Dynamics Approach to Understanding the Dynamic Interaction of Causal Factors
Research has shown that sustainability of rural water infrastructure in developing countries is largely affected by the dynamic and systemic interactions of technical, social, financial, institutional, and environmental factors that can lead to premature water system failure. This research employs systems dynamic modeling, which uses feedback mechanisms to understand how these factors interact dynamically to influence long-term rural water system functionality. To do this, the research first identified and aggregated key factors from literature, then asked water sector experts to indicate the polarity and strength between factors through Delphi and cross impact survey questionnaires, and finally used system dynamics modeling to identify and prioritize feedback mechanisms. The resulting model identified 101 feedback mechanisms that were dominated primarily by three and four-factor loops that contained some combination of the factors: Water System Functionality, Community, Financial, Government, Management, and Technology. These feedback mechanisms were then scored and prioritized, with the most dominant feedback mechanism identified as Water System Functionality – Community – Finance – Management. This research offers insight into the dynamic interaction of factors impacting sustainability of rural water infrastructure through the identification of these feedback mechanisms and makes a compelling case for future research to longitudinally investigate the interaction of these factors in various contexts
Refined Element Discontinuous Numerical Analysis of Dry-Contact Masonry Arches
The behavior of buried masonry arches is studied in this article using the Discontinuous Deformation Analysis (DDA), a numerical method that allows for the physical simulation of the intrinsic structure dis- continuities since it is based on contact and friction among pseudo-rigid blocks. Two types of arches (or vaults) are studied with a specially developed computer program, one of semicircular and another of ovoidal shape. The loads are self-weight, lateral filling, embankment thrusts and concentrated (through a short distribution) forces close to the peak. These loads are transformed into point forces applied to the center of gravity of each block with simple formulae from classical mechanics. Equilibrium is reached in the whole structure through contact forces calculated with a standard contact algorithm: penalty plus Coulomb friction.
DDA-macroblocks composed of linked (through penalty contact springs) pseudo-rigid blocks are for- mulated. This linkage allows for the simulation of collapse by instability or by stress compressive failure more accurately than traditional DDA analyses, for instance funicular polygons.
The numerical results are compared with those of the experiments taken from the literature with, for most cases, very good agreement given the uncertainties on geometry and material properties and given the intrinsic quality dispersion of masonry structures. Collapse loads as function of number of joints, safety factors and limit point forces from the numerical and experimental results are compared. The hinges that appear prior to collapse are also compared, obtaining again for most cases very good agreement.J.L. Perez-Aparicio, R. Bravo were partially supported by the MFOM I+D (2004/38), all authors by MICIIN #BIA-2008-00522 and the first also by Polytechnic University of Valencia under Grant PAID 05-10-2674.Pérez-Aparicio, JL.; Bravo, R.; Ortiz Rossini, P. (2013). Refined Element Discontinuous Numerical Analysis of Dry-Contact Masonry Arches. Engineering Structures. 48:578-587. https://doi.org/10.1016/j.engstruct.2012.09.027S5785874
Revans reversed: focusing on the positive for a change
The classical principles of action learning, based on the work of Revans, usually include working with problems as the core. This article aims, by contrast, to show how a recent project of change has incorporated principles of appreciative inquiry (AI) based on social constructionism and positive psychology into an action learning process involving a wide range of participants. The concern for problems is considered showing that the process of diagnosing a problem can reinforce a deficit orientation. The key ideas of AI are presented, highlighting the purpose of finding out what is going on in terms of what is working well, and in doing so, it becomes possible to build a picture of the strengths and virtues of what is happening at work. Based on findings from a recent project of culture shift in a design and production company, a process of positive action learning is considered
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