5,425 research outputs found
A note on the extension of the polar decomposition for the multidimensional Burgers equation
It is shown that the generalizations to more than one space dimension of the
pole decomposition for the Burgers equation with finite viscosity and no force
are of the form u = -2 viscosity grad log P, where the P's are explicitly known
algebraic (or trigonometric) polynomials in the space variables with polynomial
(or exponential) dependence on time. Such solutions have polar singularities on
complex algebraic varieties.Comment: 3 pages; minor formatting and typos corrected. Submitted to Phys.
Rev. E (Rapid Comm.
Fractalization of Torus Revisited as a Strange Nonchaotic Attractor
Fractalization of torus and its transition to chaos in a quasi-periodically
forced logistic map is re-investigated in relation with a strange nonchaotic
attractor, with the aid of functional equation for the invariant curve.
Existence of fractal torus in an interval in parameter space is confirmed by
the length and the number of extrema of the torus attractor, as well as the
Fourier mode analysis. Mechanisms of the onset of fractal torus and the
transition to chaos are studied in connection with the intermittency.Comment: Latex file ( figures will be sent electronically upon
request):submitted to Phys.Rev. E (1996
The OPERA experiment Target Tracker
The main task of the Target Tracker detector of the long baseline neutrino
oscillation OPERA experiment is to locate in which of the target elementary
constituents, the lead/emulsion bricks, the neutrino interactions have occurred
and also to give calorimetric information about each event. The technology used
consists in walls of two planes of plastic scintillator strips, one per
transverse direction. Wavelength shifting fibres collect the light signal
emitted by the scintillator strips and guide it to both ends where it is read
by multi-anode photomultiplier tubes. All the elements used in the construction
of this detector and its main characteristics are described.Comment: 25 pages, submitted to Nuclear Instrument and Method
Mixmaster universe in Horava-Lifshitz gravity
We consider spatially homogeneous (but generally non-isotropic) cosmologies
in the recently proposed Horava-Lifshitz gravity and compare them to those of
general relativity using Hamiltonian methods. In all cases, the problem is
described by an effective point particle moving in a potential well with
exponentially steep walls. Focusing on the closed-space cosmological model
(Bianchi type IX), the mixmaster dynamics is now completely dominated by the
quadratic Cotton tensor potential term for very small volume of the universe.
Unlike general relativity, where the evolution towards the initial singularity
always exhibits chaotic behavior with alternating Kasner epochs, the
anisotropic universe in Horava-Lifshitz gravity (with parameter lambda > 1/3)
is described by a particle moving in a frozen potential well with fixed (but
arbitrary) energy E. Alternating Kasner epochs still provide a good description
of the early universe for very large E, but the evolution appears to be
non-ergodic. For very small E there are harmonic oscillations around the fully
isotropic model. The question of chaos remains open for intermediate energy
levels.Comment: 1+35 pages, 4 figure
Energy- and flux-budget (EFB) turbulence closure model for the stably stratified flows. Part I: Steady-state, homogeneous regimes
We propose a new turbulence closure model based on the budget equations for
the key second moments: turbulent kinetic and potential energies: TKE and TPE
(comprising the turbulent total energy: TTE = TKE + TPE) and vertical turbulent
fluxes of momentum and buoyancy (proportional to potential temperature).
Besides the concept of TTE, we take into account the non-gradient correction to
the traditional buoyancy flux formulation. The proposed model grants the
existence of turbulence at any gradient Richardson number, Ri. Instead of its
critical value separating - as usually assumed - the turbulent and the laminar
regimes, it reveals a transition interval, 0.1< Ri <1, which separates two
regimes of essentially different nature but both turbulent: strong turbulence
at Ri<<1; and weak turbulence, capable of transporting momentum but much less
efficient in transporting heat, at Ri>1. Predictions from this model are
consistent with available data from atmospheric and lab experiments, direct
numerical simulation (DNS) and large-eddy simulation (LES).Comment: 40 pages, 6 figures, Boundary-layer Meteorology, resubmitted, revised
versio
Near-Infrared Photometric Survey of Proto-Planetary Nebula Candidates
We present JHK' photometric measurements of 78 objects mostly consisting of
proto-planetary nebula candidates. Photometric magnitudes are determined by
means of imaging and aperture photometry. Unlike the observations with a
photometer with a fixed-sized beam, the method of imaging photometry permits
accurate derivation of photometric values because the target sources can be
correctly identified and confusion with neighboring sources can be easily
avoided. Of the 78 sources observed, we report 10 cases in which the source
seems to have been misidentified or confused by nearby bright sources. We also
present nearly two dozen cases in which the source seems to have indicated a
variability which prompts a follow-up monitoring. There are also a few sources
that show previously unreported extendedness. In addition, we present H band
finding charts of the target sources.Comment: 3 tables, 1 figur
Larval control of Anopheles (Nyssorhinchus) darlingiusing granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon Rainforest
Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other B^0 decay modes with a four-pion final state
We present a study of the branching fraction of the decay B^0->rho0rho0 and
the fraction of longitudinally polarized rho0 mesons in this decay. The results
are obtained from the final data sample containing 772 million BBbar pairs
collected at the Y(4S) resonance with the Belle detector at the KEKB
asymmetric-energy e+e- collider. We find 166 +- 59 B^0 -> rho0 rho0 events
(including systematic uncertainties), corresponding to a branching fraction of
B(B^0->rho0rho0) = (1.02 +- 0.30 (stat) +- 0.15 (syst)) x 10^{-6} with a
significance of 3.4 standard deviations and a longitudinal polarization
fraction fL = 0.21^{+0.18}_{-0.22} (stat) +- 0.15 (syst). We use the
longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa
matrix angle phi_2 = (84.9 +- 13.5) degrees through an isospin analysis in the
B->rhorho system. We furthermore find 149 +- 49 B^0->f0rho0 events,
corresponding to B(B^0->f0rho0) x B(f0->pi+pi-) = (0.78 +- 0.22 (stat) +- 0.11
(syst)) x 10^{-6}, with a significance of 3.1 standard deviations. We find no
other significant contribution with the same final state, and set upper limits
at 90% confidence level on the (product) branching fractions,
B(B^0->pi+pi-pi+pi-)rho0pi+pi-)<12.0 x 10^{-6},
B(B^0->f0pi+pi-) x B(f0->pi+pi-) f0f0) x
B(f0->pi+pi-)^{2} < 0.2 x 10^{-6}.Comment: 21 pages, 20 figures, conference paper for the 2012th CKM workshop,
submitted to PR
Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays
We present a measurement of the time-dependent charge-parity (CP) violation
parameters in B0 -> pi+ pi- decays. The results are obtained from the final
data sample containing 772 million BBbar pairs collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
We obtain the CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03
(syst) and Scp = -0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp
represent the direct and mixing-induced CP asymmetry, respectively. Using an
isospin analysis including results from other Belle measurements, we find 23.8
< phi2 < 66.8 degrees is disfavored at the 1 sigma level, where phi2 is one of
the three interior angles of the CKM unitarity triangle related to B_{u,d}
decays.Comment: 16 pages, 5 figures, CKM2012 conference paper, Submitted to PR
Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts
We have thoroughly characterized the surfaces of the organic charge-transfer
salts TTF-TCNQ and (TMTSF)2PF6 which are generally acknowledged as prototypical
examples of one-dimensional conductors. In particular x-ray induced
photoemission spectroscopy turns out to be a valuable non-destructive
diagnostic tool. We show that the observation of generic one-dimensional
signatures in photoemission spectra of the valence band close to the Fermi
level can be strongly affected by surface effects. Especially, great care must
be exercised taking evidence for an unusual one-dimensional many-body state
exclusively from the observation of a pseudogap.Comment: 11 pages, 12 figures, v2: minor changes in text and figure labellin
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