Matthias Walter

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The unavailability of adequate HVDC circuit breakers is often named as one of the key inhibitors for building HVDC multi-terminal networks. Instead of only discussing what needs to be done with respect to improving CB technology, we discuss what other options in principle exist. None of the options is optimum in itself, thus the discussion must be mainly(More)
Recognizing the growing importance of scientific benchmarking in water distribution, we provide a comprehensive survey of the available literature. We begin with a discussion about the (limited) use of benchmarking in the regulation of UK water utilities, and then extend the analysis to regulated water sectors in other countries. We find no clear impact of(More)
Given an undirected graph, the non-empty subgraph polytope is the convex hull of the characteristic vectors of pairs (F, S) where S is a nonempty subset of nodes and F is a subset of the edges with both endnodes in S. We obtain a strong relationship between the non-empty subgraph polytope and the spanning forest polytope. We further show that these(More)
Effects of dietary vitamin A deficiency and excess on Golgi apparatus architecture were determined for livers of male CDF rats. In deficient animals, Golgi apparatus stacks were reduced in diameter and characterized by small, often highly fenestrated, saccules. Total membrane surface occupied by Golgi apparatus membranes also was less. Golgi apparatus of(More)
Nonlinear laser scanning microscopy is widely used for noninvasive imaging in cell biology and tissue physiology. However, multiphoton fluorescence imaging of dense, transparent connective tissue (e.g., cornea) is challenging since sophisticated labeling or slicing is necessary. High-resolution, high-contrast second harmonic generation (SHG) imaging of(More)
OBJECTIVE To investigate clinical efficacy and incidence of complications regarding intrathecal baclofen (ITB) therapy in children. METHODS Retrospective medical chart review of 15 paediatric patients with congenital brain injuries who underwent ITB implantation for treatment of severe spasticity between 2003 and 2009. RESULTS Compared to the(More)
BACKGROUND The control of the lower urinary tract is a complex, multilevel process involving both the peripheral and central nervous system. Due to lesions of the neuraxis, most spinal cord injury patients suffer from neurogenic lower urinary tract dysfunction, which may jeopardise upper urinary tract function and has a negative impact on health-related(More)
Preface During my internship at the IBM T.J. Watson Research Center in fall 2010 I studied recent papers that may be suitable for an implementation for CPLEX, one of the state-of-the-art optimization suites. The main topic was cutting planes because an implementation was relatively easy to create without requiring specific (and secret) internal information.(More)