191 research outputs found
A Relation Between Approaches to Integrability in Superconformal Yang-Mills Theory
We make contact between the infinite-dimensional non-local symmetry of the
typeIIB superstring on AdS5xS5 worldsheet theory and a non-abelian
infinite-dimensional symmetry algebra for the weakly coupled superconformal
gauge theory. We explain why the planar limit of the one-loop dilatation
operator is the Hamiltonian of a spin chain, and show that it commutes with the
g*2 N = 0 limit of the non-abelian charges.Comment: 19 pages, harvma
Noncommutative vector bundles over fuzzy CP^N and their covariant derivatives
We generalise the construction of fuzzy CP^N in a manner that allows us to
access all noncommutative equivariant complex vector bundles over this space.
We give a simplified construction of polarization tensors on S^2 that
generalizes to complex projective space, identify Laplacians and natural
noncommutative covariant derivative operators that map between the modules that
describe noncommuative sections. In the process we find a natural
generalization of the Schwinger-Jordan construction to su(n) and identify
composite oscillators that obey a Heisenberg algebra on an appropriate Fock
space.Comment: 34 pages, v2 contains minor corrections to the published versio
The use of multi-criteria decision methods in health care:Which method is most suitable for healthy and cognitively impaired population?
OBJECTIVES: To select the best multi-criteria decision making method for use with cognitively impaired patients. Population. A convenience sample of 28 subjects, 12 healthy and 16 cognitively impaired. METHODS: Based on a literature review, 5 multicriteria methods were chosen for comparison including: Kepner-tregoe analysis (KTA), simple multi attribute rating technique (SMART), SMART using swing weights (SWING), Analytic Hierarchy Process (AHP) and Conjoint Analysis (CA). Four attributes of treatment were identified (impact, duration, and end-result of treatment and associated risks). Subjects were asked to both rank and rate the importance of these attributes. After using the methods to establish preferences for treatment, subjects were asked to judge the overall difficulty of the techniques on 1–10 score, and answer questions regarding clarity of explanation of method, difficulty in answering questions, understanding method in relation to goal, and use of the method in health care situations. Subjects were interviewed either once (n = 14) or twice (n = 14) (Only the results of the first measurement are presented) RESULTS: In the overall rating of methods CA scored best (mean score 3.65), followed by SMART (3.70), AHP (4.00), SWING (4.40) and KTA (4.67). CA also scored best on verbal/written explanation, understanding of method in relation to goal second and usefulness in health care situations, and scored second place on difficulty in answering questions. In the impaired population, AHP was rated best on the overall difficulty score. CONCLUSIONS: In this pilot study, conjoint analysis was the most preferred method of preference elicitation. Our main concern regarding CA is the time it takes to fill out a CA questionnaire and the fact that data analysis is most complicated of all methods included. Another concern regarding the use of multicriteria methods needing further study is the rate of rank-reversal between methods in the cognitively impaired population
Scalar Field Theory on Fuzzy S^4
Scalar fields are studied on fuzzy and a solution is found for the
elimination of the unwanted degrees of freedom that occur in the model. The
resulting theory can be interpreted as a Kaluza-Klein reduction of CP^3 to S^4
in the fuzzy context.Comment: 16 pages, LaTe
SU(2) Flux Distributions on Finite Lattices
We studied SU(2) flux distributions on four dimensional euclidean lattices
with one dimension very large. By choosing the time direction appropriately we
can study physics in two cases: one is finite volume in the zero temperature
limit, another is finite temperature in the the intermediate to large volume
limit. We found that for cases of beta > beta crit there is no intrinsic string
formation. Our lattices with beta > beta crit belong to intermediate volume
region, and the string tension in this region is due to finite volume effects.
In large volumes we found evidence for intrinsic string formation.Comment: 21 pages text, 12 pages of postscript figure
Comparison of Coulomb Blockade Thermometers with the International Temperature Scale PLTS-2000
The operation of the primary Coulomb blockade thermometer (CBT) is based on a
measurement of bias voltage dependent conductance of arrays of tunnel junctions
between normal metal electrodes. Here we report on a comparison of a CBT with a
high accuracy realization of the PLTS-2000 temperature scale in the range from
0.008 K to 0.65 K. An overall agreement of about 1% was found for temperatures
above 0.25 K. For lower temperatures increasing differences are caused by
thermalization problems which are accounted for by numerical calculations based
on electron-phonon decoupling.Comment: 6 pages, 5 figure
Superparticle and superstring in AdS_3 x S^3 Ramond-Ramond background in light-cone gauge
We discuss superparticle and superstring dynamics in AdS_3 x S^3 supported by
R-R 3-form background using light-cone gauge approach. Starting with the
superalgebra psu(1,1|2) + psu(1,1|2) representing the basic symmetry of this
background we find the light-cone superparticle Hamiltonian. We determine the
harmonic decomposition of light-cone superfield describing fluctuations of type
IIB supergravity fields expanded near AdS_3 x S^3 background and compute the
corresponding Kaluza-Klein spectrum. We fix the fermionic and bosonic
light-cone gauges in the covariant Green-Schwarz AdS_3 x S^3 superstring action
and find the light-cone string Hamiltonian. We also obtain a realization of the
generators of psu(1,1|2) + psu(1,1|2) in terms of the superstring 2-d fields in
the light-cone gauge.Comment: 32 pages, late
Lesbian and bisexual women's human rights, sexual rights and sexual citizenship: negotiating sexual health in England.
Lesbian and bisexual women's sexual health is neglected in much Government policy and practice in England and Wales. This paper examines lesbian and bisexual women's negotiation of sexual health, drawing on findings from a small research project. Themes explored include invisibility and lack of information, influences on decision-making and sexual activities and experiences of services and barriers to sexual healthcare. Key issues of importance in this respect are homophobic and heterosexist social contexts. Drawing on understandings of lesbian, gay and bisexual human rights, sexual rights and sexual citizenship, it is argued that these are useful lenses through which to examine and address lesbian and bisexual women's sexual health and related inequalities
Non-Abelian Vortices, Super-Yang-Mills Theory and Spin(7)-Instantons
We consider a complex vector bundle E endowed with a connection A over the
eight-dimensional manifold R^2 x G/H, where G/H = SU(3)/U(1)xU(1) is a
homogeneous space provided with a never integrable almost complex structure and
a family of SU(3)-structures. We establish an equivalence between G-invariant
solutions A of the Spin(7)-instanton equations on R^2 x G/H and general
solutions of non-Abelian coupled vortex equations on R^2. These vortices are
BPS solitons in a d=4 gauge theory obtained from N=1 supersymmetric Yang-Mills
theory in ten dimensions compactified on the coset space G/H with an
SU(3)-structure. The novelty of the obtained vortex equations lies in the fact
that Higgs fields, defining morphisms of vector bundles over R^2, are not
holomorphic in the generic case. Finally, we introduce BPS vortex equations in
N=4 super Yang-Mills theory and show that they have the same feature.Comment: 14 pages; v2: typos fixed, published versio
Ice sheet model dependency of the simulated Greenland Ice Sheet in the mid-Pliocene
The understanding of the nature and behavior of ice sheets in past warm periods is important for constraining the potential impacts of future climate change. The Pliocene warm period (between 3.264 and 3.025 Ma) saw global temperatures similar to those projected for future climates; nevertheless, Pliocene ice locations and extents are still poorly constrained. We present results from the efforts to simulate mid-Pliocene Greenland Ice Sheets by means of the international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP). We compare the performance of existing numerical ice sheet models in simulating modern control and mid-Pliocene ice sheets with a suite of sensitivity experiments guided by available proxy records. We quantify equilibrated ice sheet volume on Greenland, identifying a potential range in sea level contributions from warm Pliocene scenarios. A series of statistical measures are performed to quantify the confidence of simulations with focus on inter-model and inter-scenario differences. We find that Pliocene Greenland Ice Sheets are less sensitive to differences in ice sheet model configurations and internal physical quantities than to changes in imposed climate forcing. We conclude that Pliocene ice was most likely to be limited to the highest elevations in eastern and southern Greenland as simulated with the highest confidence and by synthesizing available regional proxies; however, the extent of those ice caps needs to be further constrained by using a range of general circulation model (GCM) climate forcings
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