1,974 research outputs found
Comment on ``Intermittent Synchronization in a Pair of Coupled Chaotic Pendula"
The main aim of this comment is to emphasize that the conditional Lyapunov
exponents play an important role in distinguishing between intermittent and
persistent synchronization, when the analytic criteria for asymptotic stability
are not uniformly obeyed.Comment: 2 pages, RevTeX 4, 1 EPS figur
Transformations of q-boson and q-fermion algebras
We investigate the algebras satisfied by q-deformed boson and fermion
oscillators, in particular the transformations of the algebra from one form to
another. Based on a specific algebra proposed in recent literature, we show
that the algebra of deformed fermions can be transformed to that of undeformed
standard fermions. Furthermore we also show that the algebra of q-deformed
fermions can be transformed to that of undeformed standard bosons.Comment: 7 pages, RevTe
Preservation of Woollens Against Clothes Moths & Carpet Beetles
Physico-chemical protective measures employed in various countries all over the World for the preservation of woolens clothes moths & carpet beetles are reviewed
Vafa-Witten Estimates for Compact Symmetric Spaces
We give an optimal upper bound for the first eigenvalue of the untwisted
Dirac operator on a compact symmetric space G/H with rk G-rk H\le 1 with
respect to arbitrary Riemannian metrics. We also prove a rigidity statement.Comment: LaTeX, 11 pages. V2: Rigidity statement added, minor changes. To
appea
Stability, Gain, and Robustness in Quantum Feedback Networks
This paper concerns the problem of stability for quantum feedback networks.
We demonstrate in the context of quantum optics how stability of quantum
feedback networks can be guaranteed using only simple gain inequalities for
network components and algebraic relationships determined by the network.
Quantum feedback networks are shown to be stable if the loop gain is less than
one-this is an extension of the famous small gain theorem of classical control
theory. We illustrate the simplicity and power of the small gain approach with
applications to important problems of robust stability and robust
stabilization.Comment: 16 page
A New Deformed Supersymmetric Oscillator
We construct and discuss the Fock-space representation for a deformed
oscillator with "peculiar" statistics. We show that corresponding algebra
represents deformed supersymmetric oscillator.Comment: LATEX, 10 pages, no figures, to appear in Europhys.Let
Phases of bosonic strings and two dimensional gauge theories
We suggest that the extrinsic curvature and torsion of a bosonic string can
be employed as variables in a two dimensional Landau-Ginzburg gauge field
theory. Their interpretation in terms of the abelian Higgs multiplet leads to
two different phases. In the phase with unbroken gauge symmetry the ground
state describes open strings while in the phase with broken gauge symmetry the
ground state involves closed strings. When we allow for an additional abelian
gauge structure along the string, we arrive at an interpretation in terms of
the two dimensional SU(2) Yang-Mills theory.Comment: 8 page
Towards the solution of the anomaly in shell-model calculations of muon capture
Recently many authors have performed shell-model calculations of nuclear
matrix elements determining the rates of the ordinary muon capture in light
nuclei. These calculations have employed well-tested effective interactions in
large scale shell-model studies. For one of the nuclei of interest, namely
Si, there exists recent experimental data which can be used to deduce
the value of the ratio by using the calculated matrix elements.
Surprisingly enough, all the abovementioned shell-model results suggest a very
small value () for , quite far from the PCAC prediction
and recent data on muon capture in hydrogen. We show that this rather
disturbing anomaly is solved by employing effective transition operators. This
finding is also very important in studies of the scalar coupling of the weak
charged current of leptons and hadrons.Comment: Revtex, 6 pages, 2 figs include
The dust envelope of the pre-planetary nebula IRAS19475+3119
We present the spectral energy distribution (SED) of the pre-planetary
nebula, IRAS 19475+3119 (I19475), from the optical to the far-infrared. We
identify emission features due to crystalline silicates in the ISO SWS spectra
of the star. We have fitted the SED of I19475 using a 1-D radiative transfer
code, and find that a shell with inner and outer radii of 8.8X10^{16} and
4.4X10^{17}cm, and dust temperatures ranging from about 94K to 46K provide the
best fit. The mass of this shell is greater than/equal to
1[34cm^{2}g^{-1}/kappa(100micron)][delta/200]M_Sun, where kappa(100micron) is
the 100micron dust mass absorption coefficient (per unit dust mass), and delta
is the gas-to-dust ratio. In agreement with results from optical imaging and
millimeter-wave observations of CO emission of I19475, our model fits support
an r^{-3} density law for its dust shell, with important implications for the
interaction process between the fast collimated post-AGB winds and the dense
AGB envelopes which results in the observed shapes of PPNs and PNs. We find
that the observed JCMT flux at sub-millimeter wavelengths (850micron) is a
factor ~ 2 larger than our model flux, suggesting the presence of large dust
grains in the dust shell of I19475 which are not accounted for by our adopted
standard MRN grain size distribution.Comment: 38 pages, 8 figures. Accepted for publication in Ap
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