Markus Blumenstock

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We present new exact and heuristic algorithms for the prizecollecting Steiner tree problem. The exact algorithm rst reduces the size of the input graph while preserving equivalence of the optimal solutions and then uses mixed integer linear programming to solve the resulting instance. For our heuristic, we reduce the size of the instance graph further, but(More)
We have examined the expression of the epidermal growth factor receptor (EGFr) gene and 14 other oncogenes in several human gliomas. EGFr overexpression was apparent in 17 of 18 tumors. Nevertheless, remarkable amounts of aberrantly-sized EGFr mRNAs were not found in the 11 tumors examined. Among the 14 other oncogene probes employed, only the H-ras probe(More)
A combined cytogenetic and molecular genetic study was performed to analyze seven primary brain tumors: one oligoastrocytoma WHO-grade II, one anaplastic astrocytoma grade III, one anaplastic astrocytoma grade III/IV and four glioblastomas by G-banding and RNA dot blotting. A normal karyotype was found in the oligoastrocytoma. One of the two anaplastic(More)
Finding differentially regulated subgraphs in a biochemical network is an important problem in bioinformatics. We present a new model for finding such subgraphs which takes the polarity of the edges (activating or inhibiting) into account, leading to the problem of finding a connected subgraph induced by k vertices with maximum weight. We present several(More)
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