Detecting evoked potentials with SVD- and ICA-based statistical models.

In the functional diagnostics of human sensor systems, the analysis of stimulus responses embedded in an electroencephalogram (EEG), e.g. evoked potentials (EPs), is of high relevance for an objective electrophysiological assessment. The aim of this work is to detect weak EPs from highly contaminated signal traces. In principle this can be done using methods of spatiotemporal signal processing, which simultaneously increase the weak SNR (signal-to-noise ratio). However, methods based on any a priori knowledge of spatial or temporal properties as well as the propagation speed and direction are not applicable. Models with adjustable signal properties similar to real cortical activity are necessary for the development and evaluation of new methods of spatiotemporal signal processing. A model is needed which can be used in forward- and inverse-projection calculations. This study aims to develop a signal generator of the background EEG activity with embedded EPs of fully adjustable signal parameters. The study also compares the results of modeled signal analysis by known methods for signal decomposition, SVD (singular value decomposition) and ICA (independent component analysis).     

Numerical investigations on premixed spherical flames for Lewis numbers larger than unity

We present numerical simulations of premixed spherical flames under μg conditions using the thermo-diffusive approximation. The employed numerical method is based on a finite volume discretization with explicit Runge-Kutta time integration, both of second order. A multiresolution technique is used to represent the solution on an adaptive, locally refined grid, which allows efficient and accurate computations at a reduced computational cost. We study the ignition limit, i.e. the critical radius for which the flame extinguishes, for varying Lewis numbers larger than unity. We also present fully three-dimensional simulations of initially stretched spherical flames and show their relaxation towards spherical flames, which justifies the one-dimensional spherically symmetric simulations.     

Green fluorescent protein tag for studies of drug-induced translocation of nucleolar protein RH-II/Gu

We have constructed a human osteogenic sarcoma cell line, U-2 OS/GFP-Gu, that expresses nucleolar RNA helicase RH-II/Gu tagged with green fluorescent protein (GFP). The presence of a GFP tag does not inhibit RNA helicase, RNA folding and ATPase activities of RH-II/Gu protein. The derived cell line responds to cytotoxic agents like the parental cell line U-2 OS. In the presence of either actinomycin D or toyocamycin, the GFP-RH-II/Gu fusion protein translocates from the nucleolus to the nucleoplasm in the same way as the translocation of endogenous RH-II/Gu. The drug-induced translocation of GFP-RH-II/Gu is easily monitored by direct observation of live cells in vivo. This cell line can be used to screen cytotoxic drugs and to study the mechanisms of drug-induced translocation of RH-II/Gu. The cellular localization of RH-II/Gu during the cell cycle-dependent formation of the nucleolus is readily monitored. Real-time results are obtained more quickly without the disadvantages associated with cell fixation and immunofluorescence-based staining.     

A periodogram-based method for the detection of steady-statevisually evoked potentials

The task of objective perimetry is to scan the visual field and find an answer about the function of the visual system. Flicker-burst stimulation-a physiological sensible combination of transient and steady-state stimulation-is used to generate deterministic sinusoidal responses or visually evoked potentials (VEPs) at the visual cortex, which are derived from the electroencephalogram by a suitable electrode array. Here, the authors develop a new method for the detection of VEPs. Based on the periodogram of a time-series, they test the data for the presence of hidden periodic components, which correspond to steady-state VEPs. The method is applied successfully to real data     

Low loss mirrors for InP/InGaAsP waveguides

The loss associated with a mirror in an InP-based waveguide has been investigated. Mirror roughness and non-verticality were both significant sources of loss. Mirrors with only 1 dB loss have been produced through novel fabrication techniques.<>     

Efficient water market mechanisms to cope with water scarcity

Water markets are increasingly being relied upon as an instrument to reallocate water between competing users under conditions of water scarcity, and within an environment of fully committed water resources. Without such a reallocation new irrigation developments cannot take place and economic developments will be forgone to the detriment of rural communities. There is therefore a need for continued development of a water market mechanism to ensure that this reallocation process can take place as efficiently as possible, and to alleviate the socio-economic impact of water scarcity. Since markets are still emerging around the world it is important to learn from operating markets. This paper discusses the operational mechanism of a water exchange in Victoria, Australia, and analyses the outcome of the first five years of operation.     

Datensicherheit bei der elektronischen Auftragsvergabe

Die Richtlinien 2004/17/EG und 2004/87/EG sollen erstmals einen geschlossenen Rechtsrahmen für die elektronische Vergabe ?ffentlicher Auftr?ge bieten. Zahlreiche Lücken der Regelungen erschweren jedoch ihre Umsetzung in deutsches Recht. Der Beitrag stellt die wesentlichen technischen Rahmenbedingungen der elektronischen Auftragsvergabe dar und liefert Anhaltspunkte, wie die Vorgaben des Gemeinschaftsrechts sinnvoll umgesetzt werden k?nnen.     

Reaction between peroxidized phospholipid and protein: II. Molecular weight and phosphorus content of albumin after reaction with peroxidized cardiolipin

Peroxidized cardiolipin (diphosphatidylglycerol) reacts covalently with albumin. Incubation of albumin with increasing amounts of peroxidized cardiolipin produces a gradual increase in molecular size. Incubation with a small amount of peroxidized cardiolipin (molar ratio of cardiolipin/albumin 21) produces a mixture of complexes that differs considerably with respect to the number of cardiolipin molecules bound per molecule of albumin. With larger amounts of peroxidized cardiolipin (molar ratios of cardiolipin/albumin 54 and 114), the complexes formed seem to be of a more uniform type since the numbers of cardiolipin molecules bound per molecule of albumin are similar. No polymerization occurs for reactions in which up to at least 15 moles of cardiolipin have become bound per mole of albumin, and 20–25 moles may be bound with only very little polymerization. Only when the ratio of peroxidized cardiolipin to albumin was increased to a high value of 314 did polymerization occur. The present findings show that extensive covalent binding of peroxidized cardiolipin to albumin can occur without intermolecular crosslinking of the protein.     

Real-time measurements of semiconductor laser spectra

A technique for measuring the instantaneous spectrum of a semiconductor laser is described. Spectral fluctuations of several different devices, including three different length channel-substrate buried-crescent lasers emitting at 1.52 μm were examined. The shortest (100-μm) device showed a trend towaxds single-mode operation, and it is believed that devices of up to 70-μm length should emit predominantly in one longitudinal mode. Mode selection effects, thought to be due to reflections from the monitor diode, were observed in a 1.3-μm packaged laster. The technique has also been used to measure correlations between successive pulses, and between spectral width and mean position.