11,855 research outputs found
Twisted Quantum Affine Superalgebra and New Invariant R-matrices
The minimal irreducible representations of , i.e. those
irreducible representations that are also irreducible under are
investigated and shown to be affinizable to give irreducible representations of
the twisted quantum affine superalgebra . The
invariant R-matrices corresponding to the tensor product of any
two minimal representations are constructed, thus extending our twisted tensor
product graph method to the supersymmetric case. These give new solutions to
the spectral-dependent graded Yang-Baxter equation arising from
, which exhibit novel features not previously seen in the
untwisted or non-super cases.Comment: 19 pages, Latex fil
A Natural Formalism for Microlensing
If the standard microlensing geometry is inverted so that the Einstein ring
is projected onto the observer plane rather than the source plane, then the
relations between the observables (\theta_E,\tilde r_E) and the underlying
physical quantities (M,\pi_rel) become immediately obvious. Here \theta_E and
\tilde r_E are the angular and projected Einstein radii, M is the mass of the
lens, and \pi_rel is the lens-source relative parallax. I recast the basic
formalism of microlensing in light of this more natural geometry and in terms
of observables. I then find that the relations between observable and physical
quantities assume an exceptionally simple form. In an appendix, I propose a set
of notational conventions for microlensing.Comment: 8 pages, 1 figure tells all. Interested parties are requested to vote
on a proposed standard for microlensing notation given in the appendix.
Submitted to Ap
Near mean-field behavior in the generalized Burridge-Knopoff earthquake model with variable range stress transfer
Simple models of earthquake faults are important for understanding the
mechanisms for their observed behavior in nature, such as Gutenberg-Richter
scaling. Because of the importance of long-range interactions in an elastic
medium, we generalize the Burridge-Knopoff slider-block model to include
variable range stress transfer. We find that the Burridge-Knopoff model with
long-range stress transfer exhibits qualitatively different behavior than the
corresponding long-range cellular automata models and the usual
Burridge-Knopoff model with nearest-neighbor stress transfer, depending on how
quickly the friction force weakens with increasing velocity. Extensive
simulations of quasiperiodic characteristic events, mode-switching phenomena,
ergodicity, and waiting-time distributions are also discussed. Our results are
consistent with the existence of a mean-field critical point and have important
implications for our understanding of earthquakes and other driven dissipative
systems.Comment: 24 pages 12 figures, revised version for Phys. Rev.
EmoçÔes, âstressâ, ansiedade e âcoping": estudo qualitativo com treinadores de nĂvel internacional
A influĂȘncia dos fatores e processos psicolĂłgicos no desempenho desportivo dos atletas estĂĄ, de uma forma geral, amplamente demonstrada; todavia, poucas investigaçÔes procuraram estudar esta relação nos treinadores. Neste sentido, empregando uma entrevista semi-estruturada, a presente investigação procurou, junto de seis treinadores de elite com idades compreendidas entre os 55 e os 63 anos (M = 59 ± 3,03) de diversas modalidades, identificar as caracterĂsticas/competĂȘncias psicolĂłgicas mais importantes para o sucesso desportivo, as principais fontes de âstressâ e ansiedade experienciadas e as estratĂ©gias de âcopingâ a que recorriam em situaçÔes estressantes e/ou problemĂĄticas, adicionalmente, pretendeu explorar o papel de outras emoçÔes no seu desempenho. Os resultados revelaram que: 1) a motivação era uma das competĂȘncias/caracterĂsticas psicolĂłgicas percepcionadas pelos treinadores como mais importantes para o sucesso; 2) as principais fontes de âstressâ estavam relacionadas com preocupaçÔes com o desempenho dos atletas, sendo comuns a diferentes modalidades; 3) os treinadores recorriam a diversas estratĂ©gias de âcopingâ em simultĂąneo, geralmente adaptativas; e 4) para alĂ©m da ansiedade, outras emoçÔes, positivas e negativas, pareciam influenciar o desempenho dos treinadores.Fundação para a CiĂȘncia e Tecnologia (FCT
Improved Astrometry and Photometry for the Luyten Catalog. I. Bright Stars
We outline the construction of an updated version of the New Luyten
Two-Tenths (NLTT) catalog of high proper motion stars, which will contain
improved astrometry and photometry for the vast majority of the ~59,000 stars
in NLTT. The bright end is constructed by matching NLTT stars to Hipparcos,
Tycho-2, and Starnet; the faint end by matching to USNO-A and 2MASS. In this
first paper, we detail the bright-end matching procedure. We show that for the
majority of stars in his catalog, Luyten measured positions accurate to 1" even
though he recorded his results much more coarsely. However, there is a long
tail of position errors, with one error as large as 11 deg. Proper-motion
errors for the stars with small position errors are 24 mas/yr (1 sigma) but
deteriorate to 34 mas/yr for stars with inferior positions. NLTT is virtually
100% complete for V15 deg, but completeness in this magnitude
range falls to about 75% at the Galactic plane. Incompleteness near the plane
is not uniform, but is rather concentrated in the interval -80<l<20, where the
Milky Way is brightest.Comment: Submitted to ApJ, 28 pages including 7 figure
Nearby Microlensing Events - Identification of the Candidates for the SIM
The Space Interferometry Mission (SIM) is the instrument of choice when it
comes to observing astrometric microlensing events where nearby, usually
high-proper-motion stars (``lenses''), pass in front of more distant stars
(``sources''). Each such encounter produces a deflection in the source's
apparent position that when observed by SIM can lead to a precise mass
determination of the nearby lens star. We search for lens-source encounters
during the 2005-2015 period using Hipparcos, ACT and NLTT to select lenses, and
USNO-A2.0 to search for the corresponding sources, and rank these by the SIM
time required for a 1% mass measurement.
For Hipparcos and ACT lenses, the lens distance and lens-source impact
parameter are precisely determined so the events are well characterized. We
present 32 candidates beginning with a 61 Cyg A event in 2012 that requires
only a few minutes of SIM time. Proxima Centauri and Barnard's star each
generate several events. For NLTT lenses, the distance is known only to a
factor of 3, and the impact parameter only to 1''. Together, these produce
uncertainties of a factor ~10 in the amount of SIM time required. We present a
list of 146 NLTT candidates and show how single-epoch CCD photometry of the
candidates could reduce the uncertainty in SIM time to a factor of ~1.5.Comment: ApJ accepted, 31 pages (inc. 5 tables), 5 figures. t SIM refine
SurF: an innovative framework in biosecurity and animal health surveillance evaluation
Surveillance for biosecurity hazards is being conducted by the New Zealand Competent Authority, the Ministry for Primary Industries (MPI) to support New Zealand's biosecurity system. Surveillance evaluation should be an integral part of the surveillance life cycle, as it provides a means to identify and correct problems and to sustain and enhance the existing strengths of a surveillance system. The surveillance evaluation Framework (SurF) presented here was developed to provide a generic framework within which the MPI biosecurity surveillance portfolio, and all of its components, can be consistently assessed. SurF is an innovative, crossâsectoral effort that aims to provide a common umbrella for surveillance evaluation in the animal, plant, environment and aquatic sectors. It supports the conduct of the following four distinct components of an evaluation project: (i) motivation for the evaluation, (ii) scope of the evaluation, (iii) evaluation design and implementation and (iv) reporting and communication of evaluation outputs. Case studies, prepared by MPI subject matter experts, are included in the framework to guide users in their assessment. Three case studies were used in the development of SurF in order to assure practical utility and to confirm usability of SurF across all included sectors. It is anticipated that the structured approach and information provided by SurF will not only be of benefit to MPI but also to other New Zealand stakeholders. Although SurF was developed for internal use by MPI, it could be applied to any surveillance system in New Zealand or elsewhere
Forecasting Time-Series with Correlated Seasonality
A new approach is proposed for forecasting a time series with multiple seasonal patterns. A state space model is developed for the series using the single source of error approach which enables us to develop explicit models for both additive and multiplicative seasonality. Parameter estimates may be obtained using methods adapted from general exponential smoothing, although the Kalman filter may also be used. The proposed model is used to examine hourly and daily patterns in hourly data for both utility loads and traffic flows. Our formulation provides a model for several existing seasonal methods and also provides new options, which result in superior forecasting performance over a range of prediction horizons. The approach is likely to be useful in a wide range of applications involving both high and low frequency data, and it handles missing values in a straightforward manner.Exponential smoothing; Holt-Winters; Seasonality; Structural time series model
The Quantum Super Yangian and Casimir Operators of
The quantum super Yangian associated with the Perk - Schultz
solution of the Yang - Baxter equation is introduced. Its structural properties
are investigated, in particular, an extensive study of its central algebra is
carried out. A graded associative algebra epimorphism is established and constructed explicitly. Images of the central
elements of the quantum super Yangian under this epimorphism yield the Casimir
operators of the quantum supergroup constructed in an earlier
publication.Comment: 10 pages in plain LaTe
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