Fluctuation-stabilized marginal networks and anomalous entropic elasticity

We study the elastic properties of thermal networks of Hookean springs. In the purely mechanical limit, such systems are known to have vanishing rigidity when their connectivity falls below a critical, isostatic value. In this work we show that thermal networks exhibit a non-zero shear modulus $G$ well below the isostatic point, and that this modulus exhibits an anomalous, sublinear dependence on temperature $T$. At the isostatic point, $G$ increases as the square-root of $T$, while we find $G \propto T^{\alpha}$ below the isostatic point, where ${\alpha} \simeq 0.8$. We show that this anomalous $T$ dependence is entropic in origin.Comment: 9 pages, 7 figure

Three-dimensional waves of excitation during Dictyostelium morphogenesis

Cells in Dictyostelium slugs follow well-defined patterns of motion. We found that the chemotactic cell response is controlled by a scroll wave of messenger concentration in the highly excitable prestalk zone of the slug that decays in the less-excitable prespore region into planar wave fronts. This phenomenon is investigated by numerical solutions of partial differential equations that couple local nonlinear kinetics and diffusive transport of the chemotactic signal. In the interface of both regions a complex twisted scroll wave is formed that reduces the wave frequency in the prespore zone. The spatio-temporal dynamics of waves and filaments are followed over 33 periods of rotation. These results yield an explanation of collective self-organized cell motion in a multicellular organism

Control Function Assisted IPW Estimation with a Secondary Outcome in Case-Control Studies

Case-control studies are designed towards studying associations between risk factors and a single, primary outcome. Information about additional, secondary outcomes is also collected, but association studies targeting such secondary outcomes should account for the case-control sampling scheme, or otherwise results may be biased. Often, one uses inverse probability weighted (IPW) estimators to estimate population effects in such studies. However, these estimators are inefficient relative to estimators that make additional assumptions about the data generating mechanism. We propose a class of estimators for the effect of risk factors on a secondary outcome in case-control studies, when the mean is modeled using either the identity or the log link. The proposed estimator combines IPW with a mean zero control function that depends explicitly on a model for the primary disease outcome. The efficient estimator in our class of estimators reduces to standard IPW when the model for the primary disease outcome is unrestricted, and is more efficient than standard IPW when the model is either parametric or semiparametric

Measuring Cardiac Output in the Critically Ill

__Abstract__ Haemodynamic monitoring plays an essential part on the care of the critically ill patient. Monitoring has two goals; the first goal is a signalling function if the patients clinical condition improves or deteriorates adequate measures can be taken. Maintaining the adequacy of the circulation reduces the chance of inadequate oxygen transport to the tissues preventing organ ischemia. The second goal is using the monitoring as a decision making tool. Historically, arterial pressures were measured because they were easier to measure than bloodflow. But the introduction of the pulmonary artery catheter (PAC) in 1970 allowed the regular measurement of cardiac output (CO) at the beside. Beside CO a new array of variables could be monitored. Measuring more variables did not automatically relate to better outcomes

Framework for state and unknown input estimation of linear time-varying systems

The design of unknown-input decoupled observers and filters requires the assumption of an existence condition in the literature. This paper addresses an unknown input filtering problem where the existence condition is not satisfied. Instead of designing a traditional unknown input decoupled filter, a Double-Model Adaptive Estimation approach is extended to solve the unknown input filtering problem. It is proved that the state and the unknown inputs can be estimated and decoupled using the extended Double-Model Adaptive Estimation approach without satisfying the existence condition. Numerical examples are presented in which the performance of the proposed approach is compared to methods from literature.Comment: This paper has been accepted by Automatica. It considers unknown input estimation or fault and disturbances estimation. Existing approaches considers the case where the effects of fault and disturbance can be decoupled. In our paper, we consider the case where the effects of fault and disturbance are coupled. This approach can be easily extended to nonlinear system

Ordered Weighted Average Based Fuzzy Rough Sets

Traditionally, membership to the fuzzy-rough lower, resp. upper approximation is determined by looking only at the worst, resp. best performing object. Consequently, when applied to data analysis problems, these approximations are sensitive to noisy and/or outlying samples. In this paper, we advocate a mitigated approach, in which membership to the lower and upper approximation is determined by means of an aggregation process using ordered weighted average operators. In comparison to the previously introduced vaguely quantified rough set model, which is based on a similar rationale, our proposal has the advantage that the approximations are monotonous w.r.t. the used fuzzy indiscernibility relation. Initial experiments involving a feature selection application confirm the potential of the OWA-based model

From Populism to Democratic Polity; Problems and Challenges on Surakarta, Indonesia

The paper discusses democratisation practiced in Surakarta, Indonesia, which has been claimed by many experts as a municipality with “best practices” of democratic local governance in Indonesia. Their analyses focus on the actors and claim that participation is a possible way of crafting stable democracy. This participation in turn, they suggest, is a result of decentralisation which thus strengthen local democracy. Presenting the civil society participation and the decentralisation in the city of Surakarta, this paper shows that what actually happens is otherwise. It argues that the rise of popular participation was rooted in contentious local politics. Besides, the constitution of the new forms of popular representation are not supported by, and produced within, a clear ideological framework from the people in Surakarta