294 research outputs found
The Cole-Cole Law for Critical Dynamics in Glass-Forming Liquids
Within the mode-coupling theory (MCT) for glassy dynamics, the asymptotic
low-frequency expansions for the dynamical susceptibilities at critical points
are compared to the expansions for the dynamic moduli; this shows that the
convergence properties of the two expansions can be quite different. In some
parameter regions, the leading-order expansion formula for the modulus
describes the solutions of the MCT equations of motion outside the transient
regime successfully; at the same time, the leading- and next-to-leading order
expansion formulas for the susceptibility fail. In these cases, one can derive
a Cole-Cole law for the susceptibilities; and this law accounts for the
dynamics for frequencies below the band of microscopic excitations and above
the high-frequency part of the alpha-peak. It is shown that this scenario
explains the optical-Kerr-effect data measured for salol and benzophenone
(BZP). For BZP it is inferred that the depolarized light-scattering spectra
exhibit a wing for the alpha-peak within the Gigahertz band. This wing results
from the crossover of the von Schweidler-law part of the alpha-peak to the
high-frequency part of the Cole-Cole peak; and this crossover can be described
quantitatively by the leading-order formulas of MCT for the modulus.Comment: 15 pages, 9 figure
Critical Decay at Higher-Order Glass-Transition Singularities
Within the mode-coupling theory for the evolution of structural relaxation in
glass-forming systems, it is shown that the correlation functions for density
fluctuations for states at A_3- and A_4-glass-transition singularities can be
presented as an asymptotic series in increasing inverse powers of the logarithm
of the time t: , where
with p_n denoting some polynomial and x=ln (t/t_0). The results are
demonstrated for schematic models describing the system by solely one or two
correlators and also for a colloid model with a square-well-interaction
potential.Comment: 26 pages, 7 figures, Proceedings of "Structural Arrest Transitions in
Colloidal Systems with Short-Range Attractions", Messina, Italy, December
2003 (submitted
Customized Feedback to Patients and Providers Failed to Improve Safety or Quality of Diabetes Care: A randomized trial
Dynamics in Colloidal Liquids near a Crossing of Glass- and Gel-Transition Lines
Within the mode-coupling theory for ideal glass-transitions, the mean-squared
displacement and the correlation function for density fluctuations are
evaluated for a colloidal liquid of particles interacting with a square-well
potential for states near the crossing of the line for transitions to a gel
with the line for transitions to a glass. It is demonstrated how the dynamics
is ruled by the interplay of the mechanisms of arrest due to hard-core
repulsion and due to attraction-induced bond formation as well as by a nearby
higher-order glass-transition singularity. Application of the universal
relaxation laws for the slow dynamics near glass-transition singularities
explains the qualitative features of the calculated time dependence of the
mean-squared displacement, which are in accord with the findings obtained in
molecular-dynamics simulation studies by Zaccarelli et. al [Phys. Rev. E 66,
041402 (2002)]. Correlation functions found by photon-correlation spectroscopy
in a micellar system by Mallamace et. al [Phys. Rev. Lett. 84, 5431 2000)] can
be interpreted qualitatively as a crossover from gel to glass dynamics.Comment: 13 pages, 12 figure
Immundefekte bei chronischer Rhinosinusitis : eine bedeutende und oft unterschÀtzte Ursache
Background Chronic rhinosinusitis (CRS) is one of the most frequent chronic diseases. Among these patients the prevalence of immune defects is higher than in the healthy general population. Methods A selective review of the literature was carried out in PubMed and Medline covering the period between 2008 and 2019. Additionally, recent German publications in journals not listed in the abovementioned databases were analyzed. Results The diagnostic workflow with respect to the immunodeficiency consists of a detailed anamnesis and physical examination, laboratory tests and the antibody reaction to polysaccharide vaccines and antigens. Beside antibiotic treatment, vaccinations and immunoglobulin replacement are available. Notwithstanding the above, functional endoscopic surgery of the paranasal sinuses should be performed according to guideline recommendations. Conclusion Patients with CRS who do not sufficiently respond to conservative and surgical treatment should be checked for underlying immunodeficiencies
Higher-order glass-transition singularities in systems with short-ranged attractive potentials
Within the mode-coupling theory for the evolution of structural relaxation,
the A_4 glass-transition singularities are identified for systems of particles
interacting with a hard-sphere repulsion complemented by different short-ranged
potentials: Baxter's singular potential regularized by a large-wave-vector
cutoff, a model for the Asakura-Oosawa depletion attraction, a triangular
potential, a Yukawa attraction, and a square-well potential. The regular
potentials yield critical packing fractions, critical Debye-Waller factors and
critical amplitudes very close to each other. The elastic moduli and the
particle's localization lengths for corresponding states of the Yukawa system
and the square-well system may differ by up to 20% and 10%, respectively.Comment: 12 pages, 5 figures, J. Phys. Cond. Matt. to be publishe
Diabetes Quality of Care and Outpatient Utilization Associated With Electronic Patient-Provider Messaging: A Cross-Sectional Analysis
An asteroseismic test of diffusion theory in white dwarfs
The helium-atmosphere (DB) white dwarfs are commonly thought to be the
descendants of the hotter PG1159 stars, which initially have uniform He/C/O
atmospheres. In this evolutionary scenario, diffusion builds a pure He surface
layer which gradually thickens as the star cools. In the temperature range of
the pulsating DB white dwarfs (T_eff ~ 25,000 K) this transformation is still
taking place, allowing asteroseismic tests of the theory. We have obtained
dual-site observations of the pulsating DB star CBS114, to complement existing
observations of the slightly cooler star GD358. We recover the 7 independent
pulsation modes that were previously known, and we discover 4 new ones to
provide additional constraints on the models. We perform objective global
fitting of our updated double-layered envelope models to both sets of
observations, leading to determinations of the envelope masses and pure He
surface layers that qualitatively agree with the expectations of diffusion
theory. These results provide new asteroseismic evidence supporting one of the
central assumptions of spectral evolution theory, linking the DB white dwarfs
to PG1159 stars.Comment: 7 pages, 3 figures, 3 tables, accepted for publication in A&
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