Electron microscopical findings in the sural nerve of twins with metachromatic leukodystrophy. An attempt to classify the findings according to distinctive phases of the disease (author's transl)

Sural nerve biopsies taken from a pair of twins with metachromatic leukodystrophy were investigated by electron microscopy. The morphological findings showed distinct alterations. In the first twin the particularity was a large number of granules containing sulfatides. In the second twin, however, the main finding was a damage of myelin sheaths evidently caused by an excessive and morphologically as well as chemically defective myelin formation. According to the grading given by Ulrich the first case corresponds to the stadium one, in which a storage of sulfatides dominates, whereas case two showing a severe damage of myelin sheaths is characteristic of the second stadium of metachromatic leukodystrophy.     

Electro-bioreclamation: A combination of in situ remediation techniques proves successful at a site in Zeist, the Netherlands

The site of a former silver factory that has been severely polluted with chlorinated solvents was treated by excavating the polluted soil and installing a pump and treat system. After an initial fall in contaminant concentrations, no further progress was observed over a number of years. The Province of Utrecht tried to solve the problem by requesting remediation contractors to propose a solution at a fixed price. The winning solution was electro-bioreclamation, a combination of in situ techniques: heating soil and groundwater in the source areas, combined with soil vapour extraction and low-yield groundwater pumping, and enhancing biodegradation in the groundwater plume area. Two years of heating and 2.5 years of biodegradation has been resulted in near-complete removal of the contaminants.     

Gradient-Like Observers for Invariant Dynamics on a Lie Group

This paper proposes a design methodology for non-linear state observers for invariant kinematic systems posed on finite dimensional connected Lie groups, and studies the associated fundamental system structure. The concept of synchrony of two dynamical systems is specialized to systems on Lie groups. For invariant systems this leads to a general factorization theorem of a nonlinear observer into a synchronous (internal model) term and an innovation term. The synchronous term is fully specified by the system model. We propose a design methodology for the innovation term based on gradient-like terms derived from invariant or non-invariant cost functions. The resulting nonlinear observers have strong (almost) global convergence properties and examples are used to demonstrate the relevance of the proposed approach.      

Counting critical formations on the circle: algebraic–geometric and Morse-theoretic bounds

In this work, we analyze the critical points of potential functions on the torus arising in decentralized formation shape control of multiagent systems on the unit circle. A rotation symmetry of the potential function allows to reduce the analysis to a reduced function on a lower-dimensional torus. We show that these reduced potential functions are generically Morse functions. Lower bounds on the number of critical points of the reduced potential are obtained by Morse-theoretic arguments. For trees, precise information on the number of critical points is obtained. We use algebraic–geometric methods to determine upper bounds on the number of critical points of the reduced potentials. Our approach is applicable both to standard formation control potential functions and potential functions arising from the Kuramoto model of coupled oscillators with identical natural frequencies.