1,033 research outputs found
The symmetric orbifold of N=2 minimal models
The large level limit of the N=2 minimal models that appear in the duality
with the N=2 supersymmetric higher spin theory on AdS_3 is shown to be a
natural subsector of a certain symmetric orbifold theory. We study the relevant
decompositions in both the untwisted and the twisted sector, and analyse the
structure of the higher spin representations in the twisted sector in some
detail. These results should help to identify the string background of which
the higher spin theory is expected to describe the leading Regge trajectory in
the tensionless limit.Comment: 32 page
The Continuous Orbifold of N=2 Minimal Model Holography
For the N=2 Kazama-Suzuki models that appear in the duality with a higher
spin theory on AdS_3 it is shown that the large level limit can be interpreted
as a continuous orbifold of 2N free bosons and fermions by the group U(N). In
particular, we show that the subset of coset representations that correspond to
the perturbative higher spin degrees of freedom are precisely described by the
untwisted sector of this U(N) orbifold. We furthermore identify the twisted
sector ground states of the orbifold with specific coset representations, and
give various pieces of evidence in favour of this identification.Comment: 24 pages, v2: minor correction
Dynamics of a flexible rotor in magnetic bearings
Discussed is a magnetic bearing which was designed and tested in a flexible rotor both as support bearings and as a vibration controller. The design of the bearing is described and the effect of control circuit bandwidth determined. Both stiffness and damping coefficients were measured and calculated for the bearing with good agreement. The bearings were then placed in a single mass rotor as support bearings and the machine run through two critical speeds. Measurements were made of the vibration response in plain bushings and magnetic bearings. Comparisons were also made of the theoretical calculations with the measured peak unbalance response speeds. Finally, runs were made with the magnetic bearing used as a vibration controller
Even spin minimal model holography
The even spin W^e_\infty algebra that is generated by the stress energy
tensor together with one Virasoro primary field for every even spin s \geq 4 is
analysed systematically by studying the constraints coming from the Jacobi
identities. It is found that the algebra is characterised, in addition to the
central charge, by one free parameter that can be identified with the
self-coupling constant of the spin 4 field. We show that W^e_\infty can be
thought of as the quantisation of the asymptotic symmetry algebra of the even
higher spin theory on AdS_3. On the other hand, W^e_\infty is also quantum
equivalent to the so(N) coset algebras, and thus our result establishes an
important aspect of the even spin minimal model holography conjecture. The
quantum equivalence holds actually at finite central charge, and hence opens
the way towards understanding the duality beyond the leading 't Hooft limit.Comment: 32 pages, v2: reference added, minor changes in tex
Using Online Photography Portfolios to Enhance Cross-Cultural Awareness
There are two major challenges that we face when teaching and training about cross-cultural communication. The first is to develop the ability to observe and notice cross-cultural patterns that differ from our own. The second is that these observations become more significant when linked to some kind of context, model, theory or application. With this, the observations, if made at all, simply remain random thoughts and opinions.
The object of this paper is to describe our experience in providing cross-cultural training that addresses these two challenges. Specifically, we share a methodology where learners build online electronic portfolios (using e.g., pathbrite.com) to display original photographs that demonstrate cultural differences. Participants learn David Victor’s LESCANT Approach for Inter-Cultural Communication to provide a context for these photographic examples. That is to say, participants take original photographs to show different aspects of cross-cultural perspectives that they have observed, and then they describe those instances within the context of the LESCANT Approach categories: Language, Environment, Social Organization, Context, Authority, Non-Verbal, Time
Test results and facility description for a 40-kilowatt stirling engine
A 40 kilowatt Stirling engine, its test support facilities, and the experimental procedures used for these tests are described. Operating experience with the engine is discussed, and some initial test results are presente
Flow modifying device
A swirler for a gas turbine engine combustor is disclosed for simultaneously controlling combustor flow rate, swirl angle, residence time and fuel-air ratio to provide three regimes of operation. A first regime is provided in which fuel-air ratio is less than stoichiometric, NOx is produced at one level, and combustor flow rate is high. In a second regime, fuel-air ratio is nearly stoichiometric, NOx production is less than that of the first regime, and combustor flow rate is low. In a third regime, used for example at highoff, fuel-air ratio is greater than stoichiometric and the combustor flow rate is less than in either of the other regimes
Optical properties of the NGC 5328 group of galaxies
We present the results of a photometric and spectroscopic study of seven
members of the NGC 5328 group of galaxies, a chain of galaxies spanning over
200 kpc (H_0 = 70 km/s/Mpc). We analyze the galaxy structure and study the
emission line properties of the group members looking for signatures of star
formation and AGN activity. We finally attempt to infer, from the modeling of
line-strength indices, the stellar population ages of the early-type members.
We investigate also the presence of a dwarf galaxy population associated with
the bright members.
The group is composed of a large fraction of early-type galaxies including
NGC 5328 and NGC 5330, two bona fide ellipticals at the center of the group. In
both galaxies no recent star formation episodes are detected by the H_beta vs.
MgFe indices of these galaxies. 2MASX J13524838-2829584 has extremely boxy
isophotes which are believed to be connected to a merging event: line strength
indices suggest that this object probably had a recent star formation episode.
A warped disc component emerges from the model subtracted image of 2MASX
J13530016-2827061 which is interpreted as a signature of an ongoing interaction
with the rest of the group.
Ongoing star formation and nuclear activity is present in the projected
outskirts of the group. The two early-type galaxies 2MASX J13523852-2830444 and
2MASX J13525393-2831421 show spectral signatures of star formation, while a
Seyfert 2 type nuclear activity is detected in MCG -5-33-29.Comment: 18 pages, 12 figures, accepted for publication in MNRA
- …