3,641 research outputs found
Overview of the BlockNormal Event Trigger Generator
In the search for unmodeled gravitational wave bursts, there are a variety of
methods that have been proposed to generate candidate events from time series
data. Block Normal is a method of identifying candidate events by searching for
places in the data stream where the characteristic statistics of the data
change. These change-points divide the data into blocks in which the
characteristics of the block are stationary. Blocks in which these
characteristics are inconsistent with the long term characteristic statistics
are marked as Event-Triggers which can then be investigated by a more
computationally demanding multi-detector analysis.Comment: GWDAW-8 proceedings, 6 pages, 2 figure
Power-Law Behavior of Power Spectra in Low Prandtl Number Rayleigh-Benard Convection
The origin of the power-law decay measured in the power spectra of low
Prandtl number Rayleigh-Benard convection near the onset of chaos is addressed
using long time numerical simulations of the three-dimensional Boussinesq
equations in cylindrical domains. The power-law is found to arise from
quasi-discontinuous changes in the slope of the time series of the heat
transport associated with the nucleation of dislocation pairs and roll
pinch-off events. For larger frequencies, the power spectra decay exponentially
as expected for time continuous deterministic dynamics.Comment: (10 pages, 6 figures
A pseudo-spectral approach to inverse problems in interface dynamics
An improved scheme for computing coupling parameters of the
Kardar-Parisi-Zhang equation from a collection of successive interface
profiles, is presented. The approach hinges on a spectral representation of
this equation. An appropriate discretization based on a Fourier representation,
is discussed as a by-product of the above scheme. Our method is first tested on
profiles generated by a one-dimensional Kardar-Parisi-Zhang equation where it
is shown to reproduce the input parameters very accurately. When applied to
microscopic models of growth, it provides the values of the coupling parameters
associated with the corresponding continuum equations. This technique favorably
compares with previous methods based on real space schemes.Comment: 12 pages, 9 figures, revtex 3.0 with epsf style, to appear in Phys.
Rev.
Does intraoperative neuromonitoring of recurrent nerves have an impact on the postoperative palsy rate? Results of a prospective multicenter study
BACKGROUND: The impact of intraoperative neuromonitoring on recurrent laryngeal nerve palsy remains debated. Our aim was to evaluate the potential protective effect of intraoperative neuromonitoring on recurrent laryngeal nerve during total thyroidectomy.
METHODS: This was a prospective, multicenter French national study. The use of intraoperative neuromonitoring was left at the surgeons\u27 choice. Postoperative laryngoscopy was performed systematically at day 1 to 2 after operation and at 6 months in case of postoperative recurrent laryngeal nerve palsy. Univariate and multivariate analyses and propensity score (sensitivity analysis) were performed to compare recurrent laryngeal nerve palsy rates between patients operated with or without intraoperative neuromonitoring.
RESULTS: Among 1,328 patients included (females 79.9%, median age 51.2 years, median body mass index 25.6 kg/m), 807 (60.8%) underwent intraoperative neuromonitoring. Postoperative abnormal vocal cord mobility was diagnosed in 131 patients (9.92%), including 69 (8.6%) and 62 (12.1%) in the intraoperative neuromonitoring and nonintraoperative neuromonitoring groups, respectively. Intraoperative neuromonitoring was associated with a lesser rate of recurrent laryngeal nerve palsy in univariate analysis (odds ratio = 0.68, 95% confidence interval, 0.47; 0.98, P = .04) but not in multivariate analysis (oddsratio = 0.74, 95% confidence interval, 0.47; 1.17, P = .19), or when using a propensity score (odds ratio = 0.76, 95% confidence interval, 0.53; 1.07, P = .11). There was no difference in the rates of definitive recurrent laryngeal nerve palsy (0.8% and 1.3% in intraoperative neuromonitoring and non-intraoperative neuromonitoring groups respectively, P = .39). The sensitivity, specificity, and positive and negative predictive values of intraoperative neuromonitoring for detecting abnormal postoperative vocal cord mobility were 29%, 98%, 61%, and 94%, respectively.
CONCLUSION: The use of intraoperative neuromonitoring does not decrease postoperative recurrent laryngeal nerve palsy rate. Due to its high specificity, however, intraoperative neuromonitoring is useful to predict normal vocal cord mobility. From the CHU de Nantes, Clinique de Chirurgie Digestive et Endocrinienne, Nantes, France; CHU Lille, Université de Lille, Chirurgie Générale et Endocrinienne, Lille, France; CHU Nancy-Hôpital de Brabois, Service de Chirurgie Digestive, Hépato-Biliaire, et Endocrinienne, Nancy, France; CHU Angers, Chirurgie Digestive et Endocrinienne, Angers, France; CHU de Toulouse-Hôpital Larrey, Chirurgie Thoracique, Pôle Voies Respiratoires, Toulouse; CHU Saint-Etienne-Hôpital Nord, ORL et Chirurgie Cervico-Faciale et Plastique, Saint-Etienne, France; CHU de Limoges-Hôpital Dupuytren, Chirurgie Digestive, Générale et Endocrinienne, Limoges, France; CHU de Besançon-Hôpital Jean Minjoz, Chirurgie Digestive, Besançon, France; Centre Hospitalier du Mans, Service ORL et Chirurgie Cervico-Faciale, Le Mans, France; Centre Hospitalier Lyon-Sud, Chirurgie Générale, Endocrinienne, Digestive et Thoracique, Pierre Bénite, France; AP-HM-Hôpital de La Conception, Chirurgie Générale, Marseille, France; CHU de Rennes-Hôpital Pontchaillou, Service ORL et Chirurgie Maxillo-Faciale, Rennes, France; CHU de Caen, ORL et Chirurgie Cervico-Faciale, Caen, France; CHU d\u27Angers, ORL et Chirurgie Cervico-Faciale, Angers, France; CHU de Nantes, Service ORL, Nantes, France; AP HP URCEco île-de-France, hôpital de l\u27Hôtel-Dieu, Paris, France; DRCI, département Promotion, Nantes, France
Noisy Kuramoto-Sivashinsky equation for an erosion model
We derive the continuum equation for a discrete model for ion sputtering. We
follow an approach based on the master equation, and discuss how it can be
truncated to a Fokker-Planck equation and mapped to a discrete Langevin
equation. By taking the continuum limit, we arrive at the Kuramoto-Sivashinsky
equation with a stochastic noise term.Comment: latex (w/ multicol.sty), 4 pages; to appear in Physical Review E (Oct
1996
Phase Diffusion in Localized Spatio-Temporal Amplitude Chaos
We present numerical simulations of coupled Ginzburg-Landau equations
describing parametrically excited waves which reveal persistent dynamics due to
the occurrence of phase slips in sequential pairs, with the second phase slip
quickly following and negating the first. Of particular interest are solutions
where these double phase slips occur irregularly in space and time within a
spatially localized region. An effective phase diffusion equation utilizing the
long term phase conservation of the solution explains the localization of this
new form of amplitude chaos.Comment: 4 pages incl. 5 figures uucompresse
Renormalization Group Analysis of a Noisy Kuramoto-Sivashinsky Equation
We have analyzed the Kuramoto-Sivashinsky equation with a stochastic noise
term through a dynamic renormalization group calculation. For a system in which
the lattice spacing is smaller than the typical wavelength of the linear
instability occurring in the system, the large-distance and long-time behavior
of this equation is the same as for the Kardar-Parisi-Zhang equation in one and
two spatial dimensions. For the case the agreement is only qualitative.
On the other hand, when coarse-graining on larger scales the asymptotic flow
depends on the initial values of the parameters.Comment: 8 pages, 5 figures, revte
A pseudo-spectral method for the Kardar-Parisi-Zhang equation
We discuss a numerical scheme to solve the continuum Kardar-Parisi-Zhang
equation in generic spatial dimensions. It is based on a momentum-space
discretization of the continuum equation and on a pseudo-spectral approximation
of the non-linear term. The method is tested in (1+1)- and (2+1)- dimensions,
where it is shown to reproduce the current most reliable estimates of the
critical exponents based on Restricted Solid-on-Solid simulations. In
particular it allows the computations of various correlation and structure
functions with high degree of numerical accuracy. Some deficiencies which are
common to all previously used finite-difference schemes are pointed out and the
usefulness of the present approach in this respect is discussed.Comment: 12 pages, 13 .eps figures, revetx4. A few equations have been
corrected. Erratum sent to Phys. Rev.
Dynamic Scaling of Ion-Sputtered Surfaces
We derive a stochastic nonlinear equation to describe the evolution and
scaling properties of surfaces eroded by ion bombardment. The coefficients
appearing in the equation can be calculated explicitly in terms of the physical
parameters characterizing the sputtering process. We find that transitions may
take place between various scaling behaviors when experimental parameters such
as the angle of incidence of the incoming ions or their average penetration
depth, are varied.Comment: 13 pages, Revtex, 2 figure
Charge Imbalance Effects on Interlayer Hopping and Fermi Surfaces in Multilayered High-T_c Cuprates
We study doping dependence of interlayer hoppings, t_\perp, in multilayered
cuprates with four or more CuO_2 planes in a unit cell. When the double
occupancy is forbidden in the plane, an effective amplitude of t_\perp in the
Gutzwiller approximation is shown to be proportional to the square root of the
product of doping rates in adjacent two planes, i.e., t^eff_\perp \propto
t_\perp \sqrt{\delta_1\delta_2}, where \delta_1 and \delta_2 represent the
doping rates of the two planes. More than three-layered cuprates have two kinds
of \cuo planes, i.e., inner- and outer planes (IP and OP), resulting in two
different values of t^eff_{\perp}, i.e., t^eff_\perp 1 \propto t_\perp
\sqrt{\delta_IP \delta_IP} between IP's, and t^eff_\perp 2 \propto t_\perp
\sqrt{\delta_IP \delta_OP} between IP and OP. Fermi surfaces are calculated in
the four-layered t-t'-t''-J model by the mean-field theory. The order
parameters, the renormalization factor of t_\perp, and the site-potential
making the charge imbalance between IP and OP are self-consistently determined
for several doping rates. We show the interlayer splitting of the Fermi
surfaces, which may be observed in the angle resolved photoemission
spectroscopy measurement.Comment: Some typographical errors are revised. Journal of Physical Society of
Japan, Vol.75, No.3, in pres
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