10 research outputs found
The Weak Coupling Spectrum around Isolated Vacua in N=4 Super Yang-Mills on T^3 with any Gauge Group
The moduli space of flat connections for maximally supersymmetric Yang-Mills
theories, in a space-time of the form T^3xR, contains isolated points,
corresponding to normalizable zero energy states, for certain simple gauge
groups G. We consider the low energy effective field theories in the weak
coupling limit supported on such isolated points and find that when quantized
they consist of an infinite set of harmonic oscillators whose angular
frequencies are completely determined by the Lie algebra of G. We then proceed
to find the isolated flat connections for all simple G and subsequently specify
the corresponding effective field theories.Comment: 32 pages, 11 figures, v4 Added chapter, Published versio
Extremal limits of the Cvetic-Youm black hole and nilpotent orbits of G2(2)
We study extremal cohomogeneity one five-dimensional asymptotically flat
black holes of minimal supergravity in terms of the geodesics generated by
nilpotent elements of the Lie algebra g2(2) on the coset manifold
G2(2)/SO(2,2). There are two branches of regular extremal black holes with
these properties: (i) the supersymmetric BMPV branch, and (ii) the
non-supersymmetric extremal branch. We show that both of these branches are
reproduced by nilpotent SO(2,2)-orbits. Furthermore, we show that the partial
ordering of nilpotent orbits of G2(2) is in one-to-one correspondence with the
phase diagram of these extremal black holes.Comment: 17 pages, 2 figures; v2 two minus sign typos in appendix A equation
(A.3) corrected, no other change
Extremal solutions of the S3 model and nilpotent orbits of G2(2)
We study extremal black hole solutions of the S3 model (obtained by setting
S=T=U in the STU model) using group theoretical methods. Upon dimensional
reduction over time, the S3 model exhibits the pseudo-Riemannian coset
structure G/K with G=G2(2) and K=SO(2,2). We study nilpotent K-orbits of G2(2)
corresponding to non-rotating single-center extremal solutions. We find six
such distinct K-orbits. Three of these orbits are supersymmetric, one is
non-supersymmetric, and two are unphysical. We write general solutions and
discuss examples in all four physical orbits. We show that all solutions in
supersymmetric orbits when uplifted to five-dimensional minimal supergravity
have single-center Gibbons-Hawking space as their four-dimensional Euclidean
hyper-K\"ahler base space. We construct hitherto unknown extremal
(supersymmetric as well as non-supersymmetric) pressureless black strings of
minimal five-dimensional supergravity and briefly discuss their relation to
black rings.Comment: 45 pages, 2 figures. v2: minor changes. Published versio
An M-theory solution from null roots in E11
We find a purely gravitational classical solution of
M-theory/eleven-dimensional supergravity which corresponds to a solution of the
E10 brane sigma-model involving a null root. This solution is not
supersymmetric and is regularly embedded into E11.Comment: 10 page
Finite and infinite-dimensional symmetries of pure N=2 supergravity in D=4
We study the symmetries of pure N=2 supergravity in D=4. As is known, this
theory reduced on one Killing vector is characterised by a non-linearly
realised symmetry SU(2,1) which is a non-split real form of SL(3,C). We
consider the BPS brane solutions of the theory preserving half of the
supersymmetry and the action of SU(2,1) on them. Furthermore we provide
evidence that the theory exhibits an underlying algebraic structure described
by the Lorentzian Kac-Moody group SU(2,1)^{+++}. This evidence arises both from
the correspondence between the bosonic space-time fields of N=2 supergravity in
D=4 and a one-parameter sigma-model based on the hyperbolic group SU(2,1)^{++},
as well as from the fact that the structure of BPS brane solutions is neatly
encoded in SU(2,1)^{+++}. As a nice by-product of our analysis, we obtain a
regular embedding of the Kac-Moody algebra su(2,1)^{+++} in e_{11} based on
brane physics.Comment: 70 pages, final version published in JHE
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An artificial intelligence-based model for prediction of atrial fibrillation from single-lead sinus rhythm electrocardiograms facilitating screening.
AIMS: Screening for atrial fibrillation (AF) is recommended in the European Society of Cardiology guidelines. Yields of detection can be low due to the paroxysmal nature of the disease. Prolonged heart rhythm monitoring might be needed to increase yield but can be cumbersome and expensive. The aim of this study was to observe the accuracy of an artificial intelligence (AI)-based network to predict paroxysmal AF from a normal sinus rhythm single-lead ECG. METHODS AND RESULTS: A convolutional neural network model was trained and evaluated using data from three AF screening studies. A total of 478 963 single-lead ECGs from 14 831 patients aged ≥65 years were included in the analysis. The training set included ECGs from 80% of participants in SAFER and STROKESTOP II. The remaining ECGs from 20% of participants in SAFER and STROKESTOP II together with all participants in STROKESTOP I were included in the test set. The accuracy was estimated using the area under the receiver operating characteristic curve (AUC). From a single timepoint ECG, the artificial intelligence-based algorithm predicted paroxysmal AF in the SAFER study with an AUC of 0.80 [confidence interval (CI) 0.78-0.83], which had a wide age range of 65-90+ years. Performance was lower in the age-homogenous groups in STROKESTOP I and STROKESTOP II (age range: 75-76 years), with AUCs of 0.62 (CI 0.61-0.64) and 0.62 (CI 0.58-0.65), respectively. CONCLUSION: An artificial intelligence-enabled network has the ability to predict AF from a sinus rhythm single-lead ECG. Performance improves with a wider age distribution.The project was funded by Vinnova, Sweden’s innovation agency (grant to Zenicor Medical Systems AB). In addition, the project received funding by The Swedish Heart-Lung Foundation and CIMED. The study also received a research grant from The Swedish Research Council, Dnr 2022-01466. Emma Svennberg is supported by the Stockholm County Council (Clinical researcher appointment). The SAFER Study was funded by the National Institute for Health Research (NIHR), grant number RP-PG- 0217-20007 and by the NIHR School for Primary Care Research