3,382 research outputs found
Quantum Liouville Theory from a Diffeomorphism Chern-Simons Action
A Chern-Simons action written with Christoffel Symbols has a natural gauge
symmetry of diffeomorphisms. This Chern-Simons action will induce a
Wess-Zumio-Witten model on the boundary of the manifold. If we restrict the
diffeomorphisms to chiral diffeomorphism, the Wess-Zumio-Witten model is
equivalent to a quantum Liouville action.Comment: Minor typo correcte
Coherent State Approach to Quantum Clocks
The ``problem of time'' has been a pressing issue in quantum gravity for some
time. To help understand this problem, Rovelli proposed a model of a two
harmonic oscillators system where one of the oscillators can be thought of as a
``clock'' for the other oscillator thus giving a natural time reference frame
for the system. Recently, the author has constructed an explicit form for the
coherent states on the reduced phase space of this system in terms of Klauder's
projection operator approach. In this paper, by using coherent state
representations and other tools from coherent state quantization, I investigate
the construction of gauge invariant operators on this reduced phase space, and
the ability to use a quantum oscillator as a ``clock.''Comment: 13 pages, Late
Development of Tollmien-Schlichting disturbances in the presence of laminar separation bubbles on an unswept infinite wavy wing
The effect of long-wavelength sinusoidal surface waviness on the development of Tollmien-Schlichting (TS) wave instabilities is investigated. The analysis is based on the compressible flow that forms over an unswept infinite wavy wing with surface variations of variable amplitude, wavelength, and phase. Boundary layer profiles are extracted directly from solutions of a Navier-Stokes solver, which allows a thorough parametric analysis to be undertaken. Many wavy surface configurations are examined that can be sufficient to establish localized pockets of separated flow. Linear stability analysis is undertaken using parabolized stability equations (PSE) and linearized Navier-Stokes (LNS) methods, and surface waviness is generally found to enhance unstable behavior. Results of the two schemes are compared and criteria for PSE to establish accurate solutions in separated flows are determined, which are based on the number of TS waves per wavelength of the surface deformation. Relationships are formulated, relating the instability variations to the surface parameters, which are consistent with previous observations regarding the growth of TS waves on a flat plate. Additionally, some long-wavelength surface deformations are found to stabilize TS disturbances
Noether Currents of Charged Spherical Black Holes
We calculate the Noether currents and charges for Einstein-Maxwell theory
using a version of the Wald approach. In spherical symmetry, the choice of time
can be taken as the Kodama vector. For the static case, the resulting combined
Einstein-Maxwell charge is just the mass of the black hole. Using either a
classically defined entropy or the Iyer-Wald selection rules, the entropy is
found to be just a quarter of the area of the trapping horizon. We propose
identifying the combined Noether charge as an energy associated with the Kodama
time. For the extremal black hole case, we discuss the problem of Wald's
rescaling of the surface gravity to define the entropy.Comment: 4 page
Enhancing the patient involvement in outcomes: a study protocol of personalised outcome measurement in the treatment of substance misuse
Involving patients in treatment is becoming increasingly popular in mental health [Sales & Alves:
Personalized evaluation of psychological treatments: A review of tools and research designs, submitted]. However,
in substance misuse treatment settings, the patient perspective about treatment tends to be overlooked. This has
been cited as a key priority by Orford et al. [Addiction, 103: 875-885, 2008] who included patient feedback about
treatment as one of ten areas requiring an urgent paradigm shift in addiction research and practice.
This project will apply an innovative method to involve substance misuse patients in psychological therapies, by
asking them to suggest topics to evaluate their treatment. These topics suggested by patients can be written as a
list of personalised items, so-called as patient-generated outcome measures (PGOM). Despite its patient-friendly
features, PGOM’s have never been used in this population, which is what this project aims to overcome
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