Distributed reconstruction of time-varying graph signals via a modified Newton’s method

This paper develops a distributed reconstruction algorithm, that can be implemented efficiently, for time-varying graph signals. The reconstruction problem is formulated as an unconstrained optimization problem that minimizes the weighted sum of the data fidelity term and the regularization term. The regularizer used is the nonsmoothness measure of the temporal difference signal. The classical Newton’s method can be used to solve the optimization problem. However, computation of the Hessian matrix inverse is required, and this does not scale well with the graph size. Furthermore, a distributed implementation is not possible. An approximation to the inverse Hessian, that exploits the graph topology, is developed here. The resulting iterative algorithm can be implemented in a distributed manner, and scales well with the graph size. Convergence analysis of the algorithm is presented, which shows convergence to the global optimum. Numerical results, using both synthetic and real world datasets, will demonstrate the superiority of the proposed reconstruction algorithm over existing methods.     

On Floridi’s metaphysical foundation of information ecology

The paper presents a critical appraisal of Floridi’s metaphysical foundation of information ecology. It highlights some of the issues raised by Floridi with regard to the axiological status of the objects in the “infosphere,” the moral status of artificial agents, and Floridi’s foundation of information ethics as information ecology. I further criticise the ontological conception of value as a first order category. I suggest that a weakening of Floridi’s demiurgic information ecology is needed in order not to forget the limitations of human actors and/or of their surrogates, digital agents. I plea for a rational theoretical and practical view of such agents beyond utopian reasoning with regard to their potential moral status.     

Modification of Jaffe’s kinetic method decreases bilirubin interference: A preliminary report

The negative interference of bilirubin on serum creatinine determined by the kinetic alkaline picrate (Jaffe) reaction is the unresolved problem. Though high performance liquid chromatography and gas chromatography with mass spectroscopy have been proposed to be gold standards for creatinine estimation but they are not readily available in most of the clinical chemistry laboratories due to economic and technical constraints. Most of the present day analyzers use Jaffe’s kinetic method without deproteinization. Though enzymatic methods are now routinely used as most accurate method but they are not acceptable due to cost constraints. Hence this study was planned to find out a possible solution to the problem of bilirubin interference by a minor modification in the commonly used Jaffe method so that it is amenable for use on the currently used analyzers.