6,574 research outputs found
Note on SLE and logarithmic CFT
It is discussed how stochastic evolutions may be linked to logarithmic
conformal field theory. This introduces an extension of the stochastic Loewner
evolutions. Based on the existence of a logarithmic null vector in an
indecomposable highest-weight module of the Virasoro algebra, the
representation theory of the logarithmic conformal field theory is related to
entities conserved in mean under the stochastic process.Comment: 10 pages, LaTeX, v2: version to be publishe
A warped kernel improving robustness in Bayesian optimization via random embeddings
This works extends the Random Embedding Bayesian Optimization approach by
integrating a warping of the high dimensional subspace within the covariance
kernel. The proposed warping, that relies on elementary geometric
considerations, allows mitigating the drawbacks of the high extrinsic
dimensionality while avoiding the algorithm to evaluate points giving redundant
information. It also alleviates constraints on bound selection for the embedded
domain, thus improving the robustness, as illustrated with a test case with 25
variables and intrinsic dimension 6
Intrinsic localized modes in the charge-transfer solid PtCl
We report a theoretical analysis of intrinsic localized modes in a
quasi-one-dimensional charge-transfer-solid (PtCl). We discuss strongly nonlinear features of resonant Raman
overtone scattering measurements on PtCl, arising from quantum intrinsic
localized (multiphonon) modes (ILMs) and ILM-plus-phonon states. We show, that
Raman scattering data displays clear signs of a non-thermalization of lattice
degrees-of-freedom, manifested in a nonequilibrium density of intrinsic
localized modes.Comment: 4 pages, 4 figures, REVTE
Fatal Complications during Anaesthesia in Moebius Syndrome: A Case Report and Brief Discussion of Relevant Precautions and Preoperative Assessments
We present a case of a 23-year-old male with Moebius syndrome admitted with sigmoid volvulus. Moebius Syndrome is a very rare complex congenital disorder characterised by uni- or bilateral facial paralysis resulting in orofacial abnormalities that in some individuals make tracheal intubation very difficult. In the present case, complications during the anaesthetic procedure caused a fatal outcome for the patient, as difficulties intubating was followed by an unexpected circulatory collapse, which could not be counteracted in the current setting.
The case emphasises the importance of handling patients with Moebius Syndrome and other patients with a difficult airway with utmost caution during anaesthetic care, particularly in the emergent setting where other complications might be present. A thorough preanaesthetic evaluation with specific attention to airway management and circulatory status is mandatory
and all measures must be taken to optimise patient safety
Workshop on Drought Forecasting for Northeast Brazil
Precipitation forecasting parameters for northeast Brazil were developed. Hydrological, sociological, and economic aspects were examined. A drought forecasting model is presented
Shear Flow Generation and Energetics in Electromagnetic Turbulence
Zonal flows are recognised to play a crucial role for magnetised plasma
confinement. The genesis of these flows out of turbulent fluctuations is
therefore of significant interest. We investigate the relative importance of
zonal flow generation mechanisms via the Reynolds stress, Maxwell stress, and
geodesic acoustic mode (GAM) transfer in drift-Alfv\'en turbulence. By means of
numerical computations we quantify the energy transfer into zonal flows owing
to each of these effects. The importance of the three driving ingredients in
electrostatic and electromagnetic turbulence for conditions relevant to the
edge of fusion devices is revealed for a broad range of parameters. The
Reynolds stress is found to provide a flow drive, while the electromagnetic
Maxwell stress is in the cases considered a sink for the flow energy. In the
limit of high plasma beta, where electromagnetic effects and Alfv\'en dynamics
are important, the Maxwell stress is found to cancel the Reynolds stress to a
high degree. The geodesic oscillations, related to equilibrium pressure profile
modifications due to poloidally asymmetric transport, can act as both sinks as
drive terms, depending on the parameter regime. For high beta cases the GAMs
are the main drive of the flow. This is also reflected in the frequency
dependence of the flow, showing a distinct peak at the GAM frequency in that
regime.Comment: 16 pages, 12 Figure
SLE-type growth processes and the Yang-Lee singularity
The recently introduced SLE growth processes are based on conformal maps from
an open and simply-connected subset of the upper half-plane to the half-plane
itself. We generalize this by considering a hierarchy of stochastic evolutions
mapping open and simply-connected subsets of smaller and smaller fractions of
the upper half-plane to these fractions themselves. The evolutions are all
driven by one-dimensional Brownian motion. Ordinary SLE appears at grade one in
the hierarchy. At grade two we find a direct correspondence to conformal field
theory through the explicit construction of a level-four null vector in a
highest-weight module of the Virasoro algebra. This conformal field theory has
central charge c=-22/5 and is associated to the Yang-Lee singularity. Our
construction may thus offer a novel description of this statistical model.Comment: 12 pages, LaTeX, v2: thorough revision with corrections, v3: version
to be publishe
A note on Kerr/CFT and free fields
The near-horizon geometry of the extremal four-dimensional Kerr black hole
and certain generalizations thereof has an SL(2,R) x U(1) isometry group.
Excitations around this geometry can be controlled by imposing appropriate
boundary conditions. For certain boundary conditions, the U(1) isometry is
enhanced to a Virasoro algebra. Here, we propose a free-field construction of
this Virasoro algebra.Comment: 10 pages, v2: comments and references adde
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