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

Hopelessness the ‘active ingredient’? : associations of hopelessness and depressive symptoms with Interleukin-6.

Objective: Previous research has revealed a relationship of depressive symptoms and hopelessness with cardiovascular diseases (CVDs) which are associated with elevated levels of interleukin-6 (IL-6). The objective of this study was to explore whether depressive symptoms and hopelessness are independent predictors of IL-6 levels. Method: Hopelessness, depressive symptoms, and IL-6 were measured in 45 Swedish adults (26 women and 19 men; age range: 31-65 years). Two separated linear regressions were conducted with hopelessness and depressive symptoms serving as individual predictors of IL-6. Another regression analysis examined whether the two predictors predict IL-6 when controlling for each other. The regression coefficients of the models with one predictor and with both predictors were compared. Results: As predicted, after adjusting for age, BMI, illness, smoking, and gender, more depressive symptoms and more hopelessness predicted higher IL-6 levels in independent regressions. When controlling for each other, hopelessness, but not depressive symptoms, predicted IL-6 levels. Finally, when controlling for hopelessness, the regression between depressive symptoms and IL-6 level was significantly reduced; however, there was no significant change in the regression between hopelessness and IL-6 level when controlling for depressive symptoms. Conclusions: Thus, these results suggest that depressive symptoms and hopelessness are not independent predictors of IL-6 levels. Future research should explore the interplay of hopelessness and depressive symptoms on other risk factors of CVDs

Sexual Function in Women Suffering from Aortoiliac Occlusive Disease

AbstractObjective:to describe the sexual function in women suffering aortoiliac occlusive disease (AIOD) and in an age-matched reference group.Patients and methods:thirty-six women suffering from AIOD were included. Twenty were investigated before vascular intervention (untreated) and 16 different women after treatment (treated). Eighteen age-matched women served as areferencegroup. The patients answered a questionnaire including sexual, social and medical questions and a gynaecological examination was performed.Results:untreated patients with AIOD have a significantly impaired physical well-being compared to the other groups (p<0.001). A negative effect of the vascular disease and its treatment on sexual life was experienced by 69% oftreatedcompared to 40% affected amonguntreated(p=0.05). Vulval sensibility was impaired in 44% oftreated, 11% ofuntreatedand 22% ofreferencepatients. Defective anal sphincter function was found in 33% oftreated, 17% ofuntreatedand 6% in thereferencegroup. Those differences were not statistically significant.Conclusions:symptomatic AIOD in women is associated with a significantly impaired physical and sexual well-being. Though limited by size and methodology, the results indicate the possibility of iatrogenic nerve damage

Density fluctuations and single-particle dynamics in liquid lithium

The single-particle and collective dynamical properties of liquid lithium have been evaluated at several thermodynamic states near the triple point. This is performed within the framework of mode-coupling theory, using a self-consistent scheme which, starting from the known static structure of the liquid, allows the theoretical calculation of several dynamical properties. Special attention is devoted to several aspects of the single-particle dynamics, which are discussed as a function of the thermodynamic state. The results are compared with those of Molecular Dynamics simulations and other theoretical approaches.Comment: 31 pages (in preprint format), 14 figures. Submitted to Phys. Rev.

Derivation of the nonlinear fluctuating hydrodynamic equation from underdamped Langevin equation

We derive the fluctuating hydrodynamic equation for the number and momentum densities exactly from the underdamped Langevin equation. This derivation is an extension of the Kawasaki-Dean formula in underdamped case. The steady state probability distribution of the number and momentum densities field can be expressed by the kinetic and potential energies. In the massless limit, the obtained fluctuating hydrodynamic equation reduces to the Kawasaki-Dean equation. Moreover, the derived equation corresponds to the field equation derived from the canonical equation when the friction coefficient is zero.Comment: 16 page

Pressure induced structural and dynamical changes in liquid Si. An ab-initio study

The static and dynamic properties of liquid Si at high-pressure have been studied using the orbital free ab-initio molecular dynamics method. Four thermodynamic states at pressures 4, 8, 14 and 23 GPa are considered. The calculated static structure shows qualitative agreement with the available experimental data. We analize the remarkable structural changes occurring between 8 and 14 GPa along with its effect on several dynamic properties.Comment: 10 pages, 11 figures. Accepted for publication in Journal of Physics: Condensed Matte

The evolution of vibrational excitations in glassy systems

The equations of the mode-coupling theory (MCT) for ideal liquid-glass transitions are used for a discussion of the evolution of the density-fluctuation spectra of glass-forming systems for frequencies within the dynamical window between the band of high-frequency motion and the band of low-frequency-structural-relaxation processes. It is shown that the strong interaction between density fluctuations with microscopic wave length and the arrested glass structure causes an anomalous-oscillation peak, which exhibits the properties of the so-called boson peak. It produces an elastic modulus which governs the hybridization of density fluctuations of mesoscopic wave length with the boson-peak oscillations. This leads to the existence of high-frequency sound with properties as found by X-ray-scattering spectroscopy of glasses and glassy liquids. The results of the theory are demonstrated for a model of the hard-sphere system. It is also derived that certain schematic MCT models, whose spectra for the stiff-glass states can be expressed by elementary formulas, provide reasonable approximations for the solutions of the general MCT equations.Comment: 50 pages, 17 postscript files including 18 figures, to be published in Phys. Rev.