483 research outputs found
Novel electrocardiographic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy
Aims: In order to improve the electrocardiographic (ECG) diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC), we evaluated novel quantitative parameters of the QRS complex and the value of bipolar chest leads (CF leads) computed from the standard 12 leads.
Methods and results: We analysed digital 12-lead ECGs in 44 patients with ARVC, 276 healthy subjects including 44 age and sex-matched with the patients and 36 genotyped members of ARVC families. The length and area of the terminal S wave in V1 to V3 were measured automatically using a common for all 12 leads QRS end. T wave negativity was assessed in V1 to V6 and in the bipolar CF leads computed from the standard 12 leads. The length and area of the terminal S wave were significantly shorter, whereas the S wave duration was significantly longer in ARVC patients compared with matched controls. Among members of ARVC families, those with mutations (n = 15) had shorter QRS length in V2 and V3 and smaller QRS area in lead V2 compared with those without mutations (n = 20). In ARVC patients, the CF leads were diagnostically superior to the standard unipolar precordial leads. Terminal S wave duration in V1 >48 ms or major T wave negativity in CF leads separated ARVC patients from matched controls with 90% sensitivity and 86% specificity.
Conclusion: The terminal S wave length and area in the right precordial leads are diagnostically useful and suitable for automatic analysis in ARVC. The CF leads are diagnostically superior to the unipolar precordial leads
Classical and quantum q-deformed physical systems
On the basis of the non-commutative q-calculus, we investigate a
q-deformation of the classical Poisson bracket in order to formulate a
generalized q-deformed dynamics in the classical regime. The obtained
q-deformed Poisson bracket appears invariant under the action of the
q-symplectic group of transformations. In this framework we introduce the
q-deformed Hamilton's equations and we derive the evolution equation for some
simple q-deformed mechanical systems governed by a scalar potential dependent
only on the coordinate variable. It appears that the q-deformed Hamiltonian,
which is the generator of the equation of motion, is generally not conserved in
time but, in correspondence, a new constant of motion is generated. Finally, by
following the standard canonical quantization rule, we compare the well known
q-deformed Heisenberg algebra with the algebra generated by the q-deformed
Poisson bracket.Comment: 9 pages, accepted for publication in "The European Physical Journal
C
Quantum algebras in phenomenological description of particle properties
Quantum and q-deformed algebras find their application not only in
mathematical physics and field theoretical context, but also in phenomenology
of particle properties. We describe (i) the use of quantum algebras U_q(su_n)
corresponding to Lie algebras of the groups SU(n), taken for flavor symmetries
of hadrons, in deriving new high-accuracy hadron mass sum rules, and (ii) the
use of (multimode) q-oscillator algebras along with q-Bose gas picture in
modelling the properties of the intercept \lambda of two-pion (two-kaon)
correlations in heavy-ion collisions, as \lambda shows sizable observed
deviation from the expected Bose-Einstein type behavior. The deformation
parameter q is in case (i) argued and in case (ii) conjectured to be connected
with the Cabibbo angle \theta_C.Comment: Latex, espcrc2.sty, 8 pages, 1 figure; v4: eq.(19) corrected. Based
on talk given at the D.V.Volkov Memorial Conference (25-29 July, 2000,
Kharkov, Ukraine
New Eaxactly Solvable Hamiltonians: Shape Invariance and Self-Similarity
We discuss in some detail the self-similar potentials of Shabat and
Spiridonov which are reflectionless and have an infinite number of bound
states. We demonstrate that these self-similar potentials are in fact shape
invariant potentials within the formalism of supersymmetric quantum mechanics.
In particular, using a scaling ansatz for the change of parameters, we obtain a
large class of new, reflectionless, shape invariant potentials of which the
Shabat-Spiridonov ones are a special case. These new potentials can be viewed
as q-deformations of the single soliton solution corresponding to the
Rosen-Morse potential. Explicit expressions for the energy eigenvalues,
eigenfunctions and transmission coefficients for these potentials are obtained.
We show that these potentials can also be obtained numerically. Included as an
intriguing case is a shape invariant double well potential whose supersymmetric
partner potential is only a single well. Our class of exactly solvable
Hamiltonians is further enlarged by examining two new directions: (i) changes
of parameters which are different from the previously studied cases of
translation and scaling; (ii) extending the usual concept of shape invariance
in one step to a multi-step situation. These extensions can be viewed as
q-deformations of the harmonic oscillator or multi-soliton solutions
corresponding to the Rosen-Morse potential.Comment: 26 pages, plain tex, request figures by e-mai
Noncommutative Geometry, Extended W(infty) Algebra and Grassmannian Solitons in Multicomponent Quantum Hall Systems
Noncommutative geometry governs the physics of quantum Hall (QH) effects. We
introduce the Weyl ordering of the second quantized density operator to explore
the dynamics of electrons in the lowest Landau level. We analyze QH systems
made of -component electrons at the integer filling factor .
The basic algebra is the SU(N)-extended W. A specific feature is
that noncommutative geometry leads to a spontaneous development of SU(N)
quantum coherence by generating the exchange Coulomb interaction. The effective
Hamiltonian is the Grassmannian sigma model, and the dynamical field
is the Grassmannian field, describing complex Goldstone
modes and one kind of topological solitons (Grassmannian solitons).Comment: 15 pages (no figures
Spinless impurities and Kondo-like behavior in strongly correlated electron systems
We investigate magnetic properties induced by a spinless impurity in strongly
correlated electron systems, i.e. the Hubbard model in the spatial dimension
and 3. For the 1D system exploiting the Bethe ansatz exact solution we
find that the spin susceptibility and the local density of states in the
vicinity of a spinless impurity show divergent behaviors. The results imply
that the induced local moment is not completely quenched at any finite
temperatures. On the other hand, the spin lattice relaxation rate obtained by
bosonization and boundary conformal field theory satisfies a relation analogous
to the Korringa law, . In the 2D and 3D systems, the
analysis based upon the antiferromagnetically correlated Fermi liquid theory
reveals that the antiferromagnetic spin fluctuation developed in the bulk is
much suppressed in the vicinity of a spinless impurity, and thus magnetic
properties are governed by the induced local moment, which leads to the
Korringa law of .Comment: 9pages,1figure, final version accepted for publication in
Phys.Rev.B(Jan2001
Solitons in a Grassmannian sigma-model Coupled to Chern-Simons Term
We propose an exactly solvable Grassmannian sigma-model coupled to the
Chern-Simons theory. In the presence of a novel topological term our model
admits exact self-dual vortex solutions which are identical to those of pure
Grassmannian model, but the topological charge has a physical meaning as a
magnetic flux since the gauge field is no longer auxiliary. We also extend the
theory to a noncommutative plane and analyze the BPS solutions.Comment: 10+1 pages, No figure, LaTeX; Reference added, Minor changes, to
appear in Phys. Rev.
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
A comparative study on q-deformed fermion oscillators
In this paper, the algebras, representations, and thermostatistics of four
types of fermionic q-oscillator models, called fermionic Newton (FN),
Chaichian-Kulish-Ng (CKN), Parthasarathy-Viswanathan-Chaichian (PVC),
Viswanathan-Parthasarathy-Jagannathan-Chaichian (VPJC), are discussed.
Similarities and differences among the properties of these models are revealed.
Particular emphasis is given to the VPJC-oscillators model so that its Fock
space representation is analyzed in detail. Possible physical applications of
these models are concisely pointed out.Comment: 32 pages, 2 figures, to appear in Int. J. Theor. Phys. (IJTP
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