Slowed Relaxational Dynamics Beyond the Fluctuation-Dissipation Theorem

To describe the slow dynamics of a system out of equilibrium, but close to a dynamical arrest, we generalize the ideas of previous work to the case where time-translational invariance is broken. We introduce a model of the dynamics that is reasonably general, and show how all of the unknown parameters of this model may be related to the observables or to averages of the noise. One result is a generalisation of the Fluctuation Dissipation Theorem of type two (FDT2), and the method is thereby freed from this constraint. Significantly, a systematic means of implementing the theory to higher order is outlined. We propose the simplest possible closure of these generalized equations, following the same type of approximations that have been long known for the equilibrium case of Mode Coupling Theory (MCT). Naturally, equilibrium MCT equations are found as a limit of this generalized formalism. %We indicate that, within the same general %framework, it should be possible to make higher level approximations, %leading to more general applicability.Comment: 14 pages, Physica A (in press

Arrest of flow and emergence of activated processes at the glass transition of a suspension of particles with hard sphere-like interactions

By combining aspects of the coherent and self intermediate scattering functions, measured by dynamical light scattering on a suspension of hard sphere-like particles, we show that the arrest of particle number density fluctuations spreads from the position of the main structure factor peak. Taking the velocity auto-correlation function into account we propose that as density fluctuations are arrested the system's ability to respond to diffusing momentum currents is impaired and, accordingly, the viscosity increases. From the stretching of the coherent intermediate scattering function we read a quantitative manifestation of the undissipated thermal energy, the source of those, ergodicity restoring, processes that short-circuit the sharp transition to a perfect glass.Comment: 9 pages, 4 figure

Asymptotic laws for tagged-particle motion in glassy systems

Within the mode-coupling theory for structural relaxation in simple systems the asymptotic laws and their leading-asymptotic correction formulas are derived for the motion of a tagged particle near a glass-transition singularity. These analytic results are compared with numerical ones of the equations of motion evaluated for a tagged hard sphere moving in a hard-sphere system. It is found that the long-time part of the two-step relaxation process for the mean-squared displacement can be characterized by the $\alpha$-relaxation-scaling law and von Schweidler's power-law decay while the critical-decay regime is dominated by the corrections to the leading power-law behavior. For parameters of interest for the interpretations of experimental data, the corrections to the leading asymptotic laws for the non-Gaussian parameter are found to be so large that the leading asymptotic results are altered qualitatively by the corrections. Results for the non-Gaussian parameter are shown to follow qualitatively the findings reported in the molecular-dynamics-simulations work by Kob and Andersen [Phys. Rev. E 51, 4626 (1995)]

On Properness and Protectiveness in Two Person Multicriteria Games

This paper extends the concepts of proper equilibria, protective behaviour and prudent behaviour to multicriteria games.Three types of proper equilibria based on different types of domination are introduced.It is shown that protective behaviour coincides with prudent behaviour.Possible relations and existence are analyzed.Multicriteria games;proper;protective;prudent

Order Based Cost Allocation Rules

Cooperative aspects of multiple criteria decision making with respect to cost allocation in a network will be studied.The vector valued costs of a graph that connects a group of geographically scattered users to a common source have to be distributed among the users.Here a specific class of cost allocation rules , the so-called Bird rules, are studied.Bird allocations can be determined by means of a greedy algorithm.This algorithm is based on an order on the edge set. Three different orders and their Bird rules are studied.Two of the three associated Bird allocation rules will be characterized.Those two constitute a refinement of the set of stable cost allocations of the multiple criteria minimum cost spanning tree problem.

Differential Cyclic Voltammetry - a Novel Technique for Selective and Simultaneous Detection using Redox Cycling Based Sensors

Redox cycling (RC) is an effect that is used to amplify electrochemical signals. However, traditional techniques such as cyclic voltammetry (CV) do not provide clear insight for a mixture of multiple redox couples while RC is applied. Thus, we have developed a new measurement technique which delivers electrochemical spectra of all reversible redox couples present based on concentrations and standard potentials. This technique has been named differential cyclic voltammetry (DCV). We have fabricated micrometer-sized interdigitated electrode (IDE) sensors to conduct DCV measurements in mixtures of 1mM catechol and 4mM [Ru(NH3)6]Cl3. To simulate the electrochemical behavior of these sensors we have also developed a finite element model (FEM) in Comsol®. The\ud experimental data corresponds to the calculated spectra obtained from simulations. Additionally, the measured spectra can be used to easily derive standard potentials and concentrations simultaneously and selectively.\u

A quantitative test of the mode-coupling theory of the ideal glass transition for a binary Lennard-Jones system

Using a molecular dynamics computer simulation we determine the temperature dependence of the partial structure factors for a binary Lennard-Jones system. These structure factors are used as input data to solve numerically the wave-vector dependent mode-coupling equations in the long time limit. Using the so determined solutions, we compare the predictions of mode-coupling theory (MCT) with the results of a previously done molecular dynamics computer simulation [Phys. Rev. E 51, 4626 (1995), ibid. 52, 4134 (1995)]. From this comparison we conclude that MCT gives a fair estimate of the critical coupling constant, a good estimate of the exponent parameter, predicts the wave-vector dependence of the various nonergodicity parameters very well, except for very large wave-vectors, and gives also a very good description of the space dependence of the various critical amplitudes. In an attempt to correct for some of the remaining discrepancies between the theory and the results of the simulation, we investigate two small (ad hoc) modifications of the theory. We find that one modification gives a worse agreement between theory and simulation, whereas the second one leads to an improved agreement.Comment: Figures available from W. Ko

The nutritive status in two different socio-economic groups in Hanang and Mbulu district and introduction of dairy products from goats as a food source in Tanzania

This study has been designed to investigate whether there is a difference in nutrition and livelihood in two socioeconomic groups in Hanang and Mbulu district, Tanzania. The two groups consist of modern people working as nurses at Haydom Lutheran Hospital, and traditional people with foremost farming as occupation and income. The focus in this survey is on children and youth, since they need nutritious food to develop well. The other aim of the study is to look at the interest in using goat milk yoghurt among adults in Hanang and Mbulu district. The analysis in this study is based on data collected trough two questionnaire surveys. The data collected trough the nutrition survey was used to identify the households, collect information about nutrition and livelihood status and the use of milk and milk products in the two groups. The data from the yoghurt survey was used to look at the marked possibilities for goat milk yoghurt at Haydom and Mulbadaw area. Every household in the nutrition survey was asked for daily, weekly and monthly choice of foodstuffs to get a view of what people were eating in this area. The food intake for an average child was recorded and results were used to look at the amount of calories consumed. Questions about the use of milk and milk products were asked to get a picture of the importance of milk. For the marketing test of yoghurt every respondent was asked to taste three types of goat milk yoghurt and answer questions concerning the survey. The results of the nutrition survey show that there is a slightly better livelihood and nutrition for people defined as modern compared to the traditional group in this study. The results of the marketing test of goat milk yoghurt show that there is a huge potential in selling the product in this area