Laguerre-model blind system identification: cardiovascular dynamics estimated from multiple peripheral circulatory signals

This paper presents a method for comparing multiple circulatory waveforms measured at different locations to improve cardiovascular parameter estimation from these signals. The method identifies the distinct vascular dynamics that shape each waveform signal, and estimates the common cardiac flow input shared by them. This signal-processing algorithm uses the Laguerre function series expansion for modeling the hemodynamics of each arterial branch, and identifies unknown parameters in these models from peripheral waveforms using multichannel blind system identification. An effective technique for determining the Laguerre base pole is developed, so that the Laguerre expansion captures and quickly converges to the intrinsic arterial dynamics observed in the two circulatory signals. Furthermore, a novel deconvolution method is developed in order to stably invert the identified dynamic models for estimating the cardiac output (CO) waveform from peripheral pressure waveforms. The method is applied to experimental swine data. A mean error of less than 5% with the measured peripheral pressure waveforms has been achieved using the models and excellent agreement between the estimated CO waveforms and the gold standard measurements have been obtained.     

Calcium apatite prepared from calcium hydroxide and orthophosphoric acid

Calcium hydroxyapatite has been prepared due to a direct precipitation reaction between 0.3m orthophosphoric acid solution and 0.1 mol calcium hydroxide dispersed in 200 ml water. The effect of the addition rate of the acid solution, reaction temperature and mixing molar Ca/P ratio is examined on the thermal stability and stoichiometry of the precipitates. Optimum conditions for HAp suitable for dense ceramics are derived from the results. The non-stoichiometry is interpreted in terms of the pH profile in the vicinity of the hydroxide particles and the state of the orthophosphate ions.     

Two-dimensional numerical analysis of lasing characteristics forself-aligned structure semiconductor lasers

Lasing characteristics in 0.78 μm AlGaAs-GaAs self-aligned structure (SAS) lasers are calculated on the basis of a newly developed two-dimensional analytical method. The calculated results are compared in detail with experimental results for MOVPE (metalorganic vapor phase epitaxial) grown SAS lasers. It is shown that calculated results agree well with experimental results, and that the newly developed two-dimensional simulator is very effective in calculating actual lasing characteristics accurately. The optimum design conditions for AlGaAs-GaAs SAS lasers obtained from experimental and calculated results are discussed     

Dielectric loss behavior of liquid nitrogen in uniform fields:Millimeter gap

Liquid nitrogen is a simple molecular liquid having no internal dipole moment. Thus it is not expected to show any dielectric loss below microwave frequencies. However, measurements carried out on liquid nitrogen at uniform fields in millimeter gap show that it exhibits measurable loss even at power frequency. Interestingly, this loss shows a tendency to decrease with increasing electric stress over a certain range, the so-called Garton effect. Data on dielectric loss of liquid nitrogen in uniform electric field and millimeter gap, both as a function of stress as well as pressure, are presented and the origin of this loss discussed     

Wide-Range Varactor-Tuned Terahertz Oscillator Using Resonant Tunneling Diode

We propose a wide-range varactor-tuned terahertz oscillator using a resonant tunneling diode (RTD) and estimate the tuning range. In a slot antenna, a varactor diode is placed in parallel with an RTD and can be operated with different bias voltages. Frequency tuning is possible by changing the varactor-diode capacitance with the bias voltage. A wide frequency tuning range >200 GHz (500 to 740 GHz) is obtained with an oscillator with a 20-μm-long antenna, 1.3-μm² RTD mesa, and 16-μm² varactor-diode mesa by electromagnetic-field analysis including a varactor-diode model.     

Magnetic properties of sputtered Co-Ir thin films

The magnetic properties of sputtered Co-Ir thin films and the relation between the properties and the film microstructure were studied. Thin films obtained by sputtering a Co-Ir alloy containing 10–20 at.% Ir exhibited high coercivity. The maximum coercivity was obtained for a composition of Co-15at.%Ir. The film remanence decreased with increasing iridium concentration. The film coercivity also increased with an increase in the average grain diameter of the films.     

Carrier capture time and its effect on the efficiency ofquantum-well lasers

Carrier capture time of the quantum well, which is an important parameter in the laser operation, was estimated for separate-confinement-heterostructure single-quantum-well (SCH-SQW) lasers by measuring the spontaneous emission from the optical confinement layers, which increases with current even above the laser threshold due to finite capture time. By fitting theoretical analysis to the measurement, hole capture time was found to be the dominant factor for the spontaneous emission increase, and was estimated to be 0.2-0.3 ps for GaInAs/GaInAsP/InP step- and graded-refractive-index-(GRIN-) SCH-SQW lasers, independent of the optical confinement structures. The same measurement was done for multiquantum-well lasers, and it was found that transport across the barrier was also responsible for the spontaneous emission increase and inhomogeneous injection into each well. The effect of the hole capture time and the transport time on the threshold current and the quantum efficiency was analyzed for high-power operation, considering the absorption loss by the carriers in the optical confinement layers. GRIN-SCH structure is shown to keep high differential efficiency in high-power operation in comparison with step-SCH structures, because the carrier density in the confinement layer is small and increases very little above threshold     

Hydrogen production as a novel process of wastewater treatment—studies on tofu wastewater with entrapped R. sphaeroides and mutagenesis

Attention is focusing on hydrogen production from wastewater, not only because hydrogen is a clean energy but also because it can be a process for wastewater treatment. In this paper, the characteristics of biological hydrogen production as a process of wastewater treatment is discussed by a comparison with methane production. The hydrogen production from tofu wastewater by anoxygenic phototrophic bacteria and its potential for wastewater treatment are reported. The possibility of co-cultivation with heterotrophic anaerobic bacteria was also investigated. As a solution to overcome the repressive effect of NH₄⁺ on hydrogen production by anoxygenic phototrophic bacteria, a study was done using glutamine auxotroph which was obtained by chemical mutagenesis. To confirm that the mutation had occurred in DNA molecular level, the glutamine synthetase gene was cloned and sequenced.