1,549 research outputs found
Inequivalent Quantizations of Gauge Theories
It is known that the quantization of a system defined on a topologically
non-trivial configuration space is ambiguous in that many inequivalent quantum
systems are possible. This is the case for multiply connected spaces as well as
for coset spaces. Recently, a new framework for these inequivalent
quantizations approach has been proposed by McMullan and Tsutsui, which is
based on a generalized Dirac approach. We employ this framework for the
quantization of the Yang-Mills theory in the simplest fashion. The resulting
inequivalent quantum sectors are labelled by quantized non-dynamical
topological charges.Comment: 24 pages, LaTeX, to be publ. in Int.J.Mod.Phys.
Reformulation of Boundary String Field Theory in terms of Boundary State
We reformulate bosonic boundary string field theory in terms of boundary
state. In our formulation, we can formally perform the integration of target
space equations of motion for arbitrary field configurations without assuming
decoupling of matter and ghost. Thus, we obtain the general form of the action
of bosonic boundary string field theory. This formulation may help us to
understand possible interactions between boundary string field theory and the
closed string sector.Comment: 13 page
Modelling Winter Grass Growth and Senescence
In temperate climates, because net grass growth in winter is low, most grass growth models deal with the main growing season (Mar-Oct in the N Hemisphere), with little emphasis on grass growth in winter (Nov-Feb). However, grass tissue turns over continuously (Hennessy et al., 2004) and the fate of herbage entering the winter is important in extended grazing season systems. This study aimed to model winter grass growth for the period 15 Oct 2001 to 28 Jan 2002 for a range of autumn closing dates (1 Sep, 20 Sep and 10 Oct) by modifying an existing model, so that the amount of green leaf could be predicted at intervals over the winter
An Analysis of the Representations of the Mapping Class Group of a Multi-Geon Three-Manifold
It is well known that the inequivalent unitary irreducible representations
(UIR's) of the mapping class group of a 3-manifold give rise to ``theta
sectors'' in theories of quantum gravity with fixed spatial topology. In this
paper, we study several families of UIR's of and attempt to understand the
physical implications of the resulting quantum sectors. The mapping class group
of a three-manifold which is the connected sum of with a finite number
of identical irreducible primes is a semi-direct product group. Following
Mackey's theory of induced representations, we provide an analysis of the
structure of the general finite dimensional UIR of such a group. In the picture
of quantized primes as particles (topological geons), this general
group-theoretic analysis enables one to draw several interesting qualitative
conclusions about the geons' behavior in different quantum sectors, without
requiring an explicit knowledge of the UIR's corresponding to the individual
primes.Comment: 52 pages, harvmac, 2 postscript figures, epsf required. Added an
appendix proving the semi-direct product structure of the MCG, corrected an
error in the characterization of the slide subgroup, reworded extensively.
All our analysis and conclusions remain as befor
Path Integrals on Riemannian Manifolds with Symmetry and Induced Gauge Structure
We formulate path integrals on any Riemannian manifold which admits the
action of a compact Lie group by isometric transformations. We consider a path
integral on a Riemannian manifold M on which a Lie group G acts isometrically.
Then we show that the path integral on M is reduced to a family of path
integrals on a quotient space Q=M/G and that the reduced path integrals are
completely classified by irreducible unitary representations of G. It is not
necessary to assume that the action of G on M is either free or transitive.
Hence our formulation is applicable to a wide class of manifolds, which
includes inhomogeneous spaces, and it covers all the inequivalent
quantizations. To describe the path integral on inhomogeneous space,
stratification geometry, which is a generalization of the concept of principal
fiber bundle, is necessarily introduced. Using it we show that the path
integral is expressed as a product of three factors; the rotational energy
amplitude, the vibrational energy amplitude, and the holonomy factor. When a
singular point arises in , we determine the boundary condition of the path
integral kernel for a path which runs through the singularity.Comment: 20 pages, no figur
National survey of clinical communication assessment in medical education in the United Kingdom (UK)
Background All medical schools in the UK are required to be able to provide evidence of competence in clinical communication in their graduates. This is usually provided by summative assessment of clinical communication, but there is considerable variation in how this is carried out. This study aimed to gain insight into the current assessment of clinical communication in UK medical schools. Methods The survey was sent via e-mail to communication leads who then were asked to consult with all staff within their medical school involved in the assessment of communication. Results Results were obtained from 27 out of 33 schools (response rate 82%) and a total of 34 courses. The average number of assessments per year was 2.4 (minimum 0, maximum 10). The Objective Structured Clinical Exam (OSCE) was the most commonly used method of assessment (53%). Other assessments included MCQ and workplace based assessments. Only nine courses used a single method of assessment. Issues raised included, logistics and costs of assessing mainly by OSCE, the robustness and reliability of such exams and integration with other clinical skills. Conclusions It is encouraging that a variety of assessment methods are being used within UK medical schools and that these methods target different components of clinical communication skills acquisition.Publisher PDFPeer reviewe
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