Clonal expansion of hypermutated measles virus in a SSPE brain

Nucleotide sequence analysis was carried out to study genes encoding the matrix (M) protein of measles virus (MV) from several regions of the brain of a case of subacute sclerosing panencephalitis. This analysis revealed the presence of MV with "wild-type" sequences as well as variants which had undergone at least five biased hypermutation events (U to C and A to G in the positive strand sequences). Despite the presence of MV variants with genes encoding the intact matrix protein open reading frame, M protein could not be detected in any of the brain regions. The distribution of virus variants was studied by cDNA cloning and sequence analysis and by in situ hybridization. The hypermutated viruses appeared to expand clonally throughout the brain of patient B.     

Widely tunable 10 Gbit/s separate absorption and modulation Mach-Zehnder wavelength converter

A fully monolithic separate absorption and modulation region wavelength converter requiring no bias tees has been fabricated. The device consists of a transmitter comprising a sampled-grating DBR laser and series-push-pull Mach-Zehnder modulator, and a receiver composed of a linear semiconductor optical amplifier and a quantum well pin photodetector. The wavelength converter has a 13 GHz bandwidth and demonstrates error-free operation at 10 Gbit/s with unity gain     

Global optimization of linear hybrid systems with explicit transitions

The global optimization of hybrid systems described by linear time-varying ordinary differential equations is examined. A method to construct convex relaxations of general, nonlinear Bolza-type objective functions or constraints subject to an embedded hybrid system with explicit transitions is presented. The optimization problem can be solved using gradient-based algorithms in a branch and bound framework that is shown to be infinitely convergent when the implied state bounds are employed.     

Conductivity, optical absorption, photoluminescence, and X-band optically detected magnetic resonance of novel poly(2,5-dibutoxyparaphenyleneacetylene) (PDBOPA)

The optical properties of novel PDBOPA (average molecular weight ≈ 48 000) are described and discussed. Exposure to I₂ vapor at ≈80 °C increases the conductivity to ≈5 × 10⁻³ S/cm, but the I₂ rapidly evolves from the film at room temperature. The absorption onsets at 2.53 eV and peaks at 2.81 eV. The 2.71 eV-excited photoluminescence (PL) peaks at ≈2.0 eV in films and solutions. In all cases, it is very intense and largely structureless. This contrasts with the clear vibronic structure of the PL of poly(3-alkylthiophene) (P3AT) and poly(2,5-dialkoxyparaphenylenevinylene) (PDOPV) films and blends. As in P3AT and PDOPV, three PL-enhancing optically detected magnetic resonance (ODMR) features are observed: (i) a strong narrow (≈15 G wide) resonance at g = 2.0025, attributed to intrachain polaron recombination; (ii) a ≈1.0 kG wide triplet powder pattern around g 2, and (iii) the Δm_s = 2 transitions of these excitons at g4.07. The results are discussed in relation to conformational defects resulting from the near cylindrical symmetry of the backbone acetylene units.     

Secondary structure prediction for modelling by homology

An improved method of secondary structure prediction has beendeveloped to aid the modelling of proteins by homology. Selecteddata from four published algorithms are scaled and combinedas a weighted mean to produce consensus algorithms. Each consensusalgorithm is used to predict the secondary structure of a proteinhomologous to the target protein and of known structure. Bycomparison of the predictions to the known structure, accuracyvalues are calculated and a consensus algorithm chosen as theoptimum combination of the composite data for prediction ofthe homologous protein. This customized algorithm is then usedto predict the secondary structure of the unknown protein. Inthis manner the secondary structure prediction is initiallytuned to the required protein family before prediction of thetarget protein. The method improves statistical secondary structureprediction and can be incorporated into more comprehensive systemssuch as those involving consensus prediction from multiple sequencealignments. Thirty one proteins from five families were usedto compare the new method to that of Garnier, Osguthorpe andRobson (GOR) and sequence alignment. The improvement over GORis naturally dependent on the similarity of the homologous protein,varying from a mean of 3% to 7% with increasing alignment significancescore.     

The 3-D-3 Rangefinder and Depth of Field Indicator

A wander mark stereoscopic rangefinder using the normal eye separation as Its base length is described. It has two main controls: one carries a scale of ranges and could be coupled to the focusing mechanism of a camera lens; the other carries a scale af lens apertures and could be coupled to the stop setting mechanism of the lens. Three indicating marks appear In space at variable distances from the observer, to show the range and depth of field limits set by the controls. The optical system consists of an illuminated diapositlve, a collimating lens and three partially reflecting mirrors. It gives autamatic campensation for varying eye separations of different observers, is accurate and easy to use, even by spectacle wearers. The rangefinder affers advantages aver established methods of setting focus In both still and cine photography, particularly in low light and on moving subjects. Under these conditions the depth of field indication is a valuable asset.     

Iterative learning control — 2D control systems from theory to application

It has long been recognized that iterative learning control is a 2D system, i.e. information propagation occurs in two independent directions. In this paper, the application of so-called norm optimal iterative learning control, which has its origins in the theory of the class of 2D systems known as linear repetitive processes to an experimental testbed in the form of a chain conveyor system is reported. This includes the motivation for applying iterative learning control to such systems, the design and construction of the testbed, and its use to demonstrate that norm optimal iterative learning control gives superior performance over alternatives. As such, it provides an application for 2D systems theory where distinct advantages arise from using such a setting for modelling and control.     

Tidal streams observed with sequential AVHRR images

Ten consecutive Advanced Very High Resolution Radiometer (AVHRR) infrared images off the north-west coast of Australia were analysed to detect tidal motions by tracking surface features using the maximum cross-correlation (MCC) method. The study area contains a broad continental shelf with the 200?m isobath situated approximately 200?km offshore. Tidal height variations at the coast are in excess of 8?m. The results not only demonstrate the potential of the MCC method in defining surface displacements in coastal regions but also provide a warning to MCC users that tidal effects must be taken into account when deriving mesoscale ocean currents from satellite sensor imagery.     

Upper bound risk estimates for mixtures of carcinogens

The excess cancer risk that might result from exposure to a mixture of chemical carcinogens usually is estimated with data from experiments conducted on individual chemicals. An upper bound on the total excess risk is estimated commonly by summing individual upper bound risk estimates. The degree to which this approach might overstate the true risk associated with the mixture has not been evaluated previously. This paper reports the results of a Monte Carlo simulation study on the degree of reduction in conservation that might be achieved using alternative methods for calculating mixture upper bounds. An unexpected finding is that for chemicals that exhibit strongly linear dose-response relationships, the summing of multistage-model-based upper bounds on excess risk can be anti-conservative, that is, it can provide less than the nominal 100(1-alpha)% coverage.