12,613 research outputs found
A systematic review and meta-analysis on acoustic voice parameters after uncomplicated thyroidectomy
BACKGROUND: Postthyroidectomy voice changes are common even without apparent laryngeal nerve injury. Our study evaluated the impact of open cervical thyroidectomy on five acoustic voice parameters in the early (< 3 months) and late (≥ 3 months) postoperative periods. METHODS: A systematic review was performed to identify studies that quantitatively assessed voice quality by acoustic voice analysis before and after thyroidectomy. Parameters included average fundamental frequency (F0 , Hz), jitter (%), shimmer (%), noise-to-harmonic ratio (NHR), and maximum phonation time (MPT) (in secs). Meta-analysis was performed using both fixed- and random-effects models. RESULTS: A total of 896 patients were analyzed. Relative to baseline, F0 significantly worsened in the early period (from 194.9 ± 34.9 Hz to 188.0 ± 34.0 Hz, P = 0.001). This was equivalent to a quarter-tone loss (P = 0.004). Shimmer (from 3.15 ± 1.59% to 3.19 ± 1.70%, P = 0.040) and MPT (from 17.9 secs to 16.7 secs, P = 0.046) also worsened in the early period, whereas jitter and NHR remained unchanged in the early and late periods. Males suffered greater deterioration in F0 (from 120.6 ± 18.8 Hz to 111.0 ± 18.5 Hz, P = 0.048) and in NHR (from 0.12 ± 0.02 to 0.16 ± 0.03, P = 0.019) than females in the early period. Four of the five acoustic parameters (F0 , jitter, shimmer, and NHR) significantly worsened after total thyroidectomy (TT) and not after lesser resection. CONCLUSION: F0 , shimmer, and MPT significantly worsened in the early and not in the late postoperative period. F0 impairment was perceptually significant. Males and those undergoing TT suffered greater voice impairment than their counterparts during the early period.postprin
Recombination Induced Softening and Reheating of the Cosmic Plasma
The atomic recombination process leads to a softening of the matter equation
of state as reflected by a reduced generalized adiabatic index, with
accompanying heat release. We study the effects of this recombination softening
and reheating of the cosmic plasma on the ionization history, visibility
function, Cold Dark Matter (CDM) transfer function, and the Cosmic Microwave
Background (CMB) spectra. The resulting modifications of the CMB spectrm is
1/10 of WMAP's current error and is comparable to PLANCK's error. Therefore,
this effect should be considered when data with higher accuracy are analysed.Comment: 11 pages, 6 figures, Accepted for publication in Monthly Notices of
the Royal Astronomical Society; as advised by referee, omit high-baryon mode
Higher Spin Gravity with Matter in AdS_3 and Its CFT Dual
We study Vasiliev's system of higher spin gauge fields coupled to massive
scalars in AdS_3, and compute the tree level two and three point functions.
These are compared to the large N limit of the W_N minimal model, and
nontrivial agreements are found. We propose a modified version of the
conjecture of Gaberdiel and Gopakumar, under which the bulk theory is
perturbatively dual to a subsector of the CFT that closes on the sphere.Comment: 58 pages; typos corrected, references adde
Comparing lattice Dirac operators with Random Matrix Theory
We study the eigenvalue spectrum of different lattice Dirac operators
(staggered, fixed point, overlap) and discuss their dependence on the
topological sectors. Although the model is 2D (the Schwinger model with
massless fermions) our observations indicate possible problems in 4D
applications. In particular misidentification of the smallest eigenvalues due
to non-identification of the topological sector may hinder successful
comparison with Random Matrix Theory (RMT).Comment: LATTICE99(topology and confinement), Latex2e using espcrc2.sty, 3
pages, 3 figure
Higher Spin Gauge Theory and Holography: The Three-Point Functions
In this paper we calculate the tree level three-point functions of Vasiliev's
higher spin gauge theory in AdS4 and find agreement with the correlators of the
free field theory of N massless scalars in three dimensions in the O(N) singlet
sector. This provides substantial evidence that Vasiliev theory is dual to the
free field theory, thus verifying a conjecture of Klebanov and Polyakov. We
also find agreement with the critical O(N) vector model, when the bulk scalar
field is subject to the alternative boundary condition such that its dual
operator has classical dimension 2.Comment: 90 pages, 5 figures; v4, minor changes in the introductio
Diffusion approximation for equilibrium Kawasaki dynamics in continuum
A Kawasaki dynamics in continuum is a dynamics of an infinite system of
interacting particles in which randomly hop over the space. In
this paper, we deal with an equilibrium Kawasaki dynamics which has a Gibbs
measure as invariant measure. We study a diffusive limit of such a
dynamics, derived through a scaling of both the jump rate and time. Under weak
assumptions on the potential of pair interaction, , (in particular,
admitting a singularity of at zero), we prove that, on a set of smooth
local functions, the generator of the scaled dynamics converges to the
generator of the gradient stochastic dynamics. If the set on which the
generators converge is a core for the diffusion generator, the latter result
implies the weak convergence of finite-dimensional distributions of the
corresponding equilibrium processes. In particular, if the potential is
from and sufficiently quickly converges to zero
at infinity, we conclude the convergence of the processes from a result in
[Choi {\it et al.}, J. Math. Phys. 39 (1998) 6509--6536]
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