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Finite precision decorrelating receivers for multiuser CDMAcommunication systems

The design of single-user decorrelating receivers employing finite-precision sequences for despreading is considered. The problem is formulated as a nonlinear bounded integer optimization problem which is shown to be network performance (NP)-hard. A branch-and-bound algorithm for finding the best finite-precision decorrelating sequence is described. Numerical examples demonstrate that the loss in performance between the optimum, infinite-precision, and the best finite-precision decorrelator is small even for large channel occupancies. Some suboptimum algorithms are investigated which greatly reduce the computational complexity associated with finding good finite precision decorrelator sequences     

Geomagnetic effects modelling for the PJM interconnection system.I. Earth surface potentials computation

The authors describe an ionospheric source current model and the development of an Earth resistivity model used to calculate geomagnetic induced currents (GIC) on the Pennsylvania-New Jersey-Maryland interconnection (PJM). The ionospheric current was modeled as a Gaussian distributed current sheet above the Earth. Geological details are included by dividing the PJM service area into 11 different Earth resistivity regions. The resulting Earth surface potential (ESP) at each power system substation was then calculated     

Gross deletions of the neurofibromatosis type 1 (NF1) gene are predominantly of maternal origin and commonly associated with a learning disability, dysmorphic features and developmental delay

The adherence of either cholera toxin or the heat-labile enterotoxin of Escherichia coli to monosialoganglioside gal(beta1-3)galNAc(beta1-4)[sialic acid (alpha2-3)]gal(beta1-4)glc(beta)1-ceramide (GM1) present on the surface of epithelial cells lining the intestine is the first step of a series that results in the induction of a watery diarrhea. While cholera is more severe, both can lead to death as a result of dehydration. To determine the potential of defined multivalent oligosaccharides, synthesized by the covalent attachment of multiple phenylisothiocyanate (PITC) derivatives of gal(beta1-3)galNAc(beta1-4)[sialic acid(alpha2-3)]gal(beta1-4)glc (oligo-GM1) to the arms of a poly(propylene imine) dendrimer, as therapeutic agents for these diseases, their ability to inhibit adherence of the toxins to cell surface-associated GM1 was determined. They not only inhibited choleragenoid (binding subunit of cholera toxin) binding to GM1-treated NCTC-2071 cells (chemically transformed murine fibroblasts) at 5 degrees, but also inhibited adherence of the choleragenoid, cholera toxin, and heat-labile enterotoxin of E. coli to GM1-treated NCTC-2071 cells at 37 degrees. Inhibition was observed whether the toxin was preincubated with the oligo-GM1-PITC-derivatized dendrimer prior to addition to cells or given just after the addition of the derivatized dendrimer to cells. The derivatized dendrimer had no effect on cell viability, as monitored by trypan blue exclusion. Blue-shifts in tryptophan fluorescence emission spectra maxima induced by adherence of either choleragenoid, cholera holotoxin, or the heat-labile enterotoxin of E. coli to oligo-GM1-PITC-derivatized dendrimers were similar to those induced by adherence to GM1 or oligo-GM1. Comparable shifts were not observed when the toxins were incubated with gangliosides that fail to function as receptors.