806 research outputs found
Endoscopically Based Endonasal and Transnasal Lasersurgery
The endoscopically based endonasal and transnasal laser surgery is
a surgical procedure, which offers the ENT-specialist a safe and
effective method to cure or to improve a number of diseases of the
upper and middle airways. Coagulative lasers are used in contact
and noncontact mode. Their light is mainly absorbed by hemoglobin
but rarely by water. The laser–tissue interaction is performed via
flexible glass fibers. For the delivery of the laser beam we use
specially designed applicator sheaths, which incorporate the
endoscope, the laser fiber and the suction channel. The procedure
is controlled online via the endoscopic image on the monitor
(“video-endoscopy”). The patient suffers less trauma
using this treatment compared to the standard endoscopic surgery
and the procedure is much quicker. Pre- and post-operative
rhinomanometric and rhinoresistometric measurements reveal that
the air flow rate of the nose can be improved effectively
Chemical sputtering of carbon films by simultaneous irradiation with argon ions and molecular oxygen
Exact Equal Time Statistics of Orszag-McLaughlin Dynamics By The Hopf Characteristic Functional Approach
By employing Hopf's functional method, we find the exact characteristic
functional for a simple nonlinear dynamical system introduced by Orszag.
Steady-state equal-time statistics thus obtained are compared to direct
numerical simulation. The solution is both non-trivial and strongly
non-Gaussian.Comment: 6 pages and 2 figure
Exact Statistics of Chaotic Dynamical Systems
We present an inverse method to construct large classes of chaotic invariant
sets together with their exact statistics. The associated dynamical systems are
characterized by a probability distribution and a two-form. While our emphasis
is on classical systems, we briefly speculate about possible applications to
quantum field theory, in the context of generalizations of stochastic
quantization.Comment: 18 pages, 5 figure
Singularities and the distribution of density in the Burgers/adhesion model
We are interested in the tail behavior of the pdf of mass density within the
one and -dimensional Burgers/adhesion model used, e.g., to model the
formation of large-scale structures in the Universe after baryon-photon
decoupling. We show that large densities are localized near ``kurtoparabolic''
singularities residing on space-time manifolds of codimension two ()
or higher (). For smooth initial conditions, such singularities are
obtained from the convex hull of the Lagrangian potential (the initial velocity
potential minus a parabolic term). The singularities contribute {\em
\hbox{universal} power-law tails} to the density pdf when the initial
conditions are random. In one dimension the singularities are preshocks
(nascent shocks), whereas in two and three dimensions they persist in time and
correspond to boundaries of shocks; in all cases the corresponding density pdf
has the exponent -7/2, originally proposed by E, Khanin, Mazel and Sinai (1997
Phys. Rev. Lett. 78, 1904) for the pdf of velocity gradients in one-dimensional
forced Burgers turbulence. We also briefly consider models permitting particle
crossings and thus multi-stream solutions, such as the Zel'dovich approximation
and the (Jeans)--Vlasov--Poisson equation with single-stream initial data: they
have singularities of codimension one, yielding power-law tails with exponent
-3.Comment: LATEX 11 pages, 6 figures, revised; Physica D, in pres
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.
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