Efficient method of adaptive sign detection for 4×4 determinants using a standard arithmetic processing unit

We propose an efficient and exact method for the adaptive sign detection of 4×4 determinants using a standard arithmetic unit. The entities of determinants are variable length integers (integers of arbitrary bit length). The integers are expressed in 16-bit data units, and the sign detection is reduced to the computation of 4×4 determinants of 16-bit integers. To accelerate the computation, the calculation is performed by using a standard arithmetic unit. We have implemented our method and confirmed that it significantly improves the computation time of 4×4 determinants. The method can be applicable to many geometric algorithms that need the exact sign evaluation of 4×4 determinants, especially to construct robust geometric algorithms.     

Design considerations on surface acoustic wave resonators with significant internal reflection in interdigital transducers

This paper discusses, both qualitatively and quantitatively, the operation and the design principle of current surface acoustic wave (SAW) resonators in which the internal reflection within interdigital transducers (IDTs) is not negligible and lower capacitance ratio is necessary. For the purpose, the p-matrix expression is used with the help of the coupling-of-modes theory. The internal reflection causes: deformation of the IDT passband shape, frequency dependence of the effective SAW velocity within IDTs, and suppression of higher-order resonances. It is shown that these features can be effectively used to enhance performances of both one-port SAW resonators and two-port double-mode SAW (DMS) filters. In addition, under proper designs accounting for the internal reflection, most of all structural discontinuities can be removed, and is most preferable for the reduced scattering loss at the discontinuity. Design criteria also are presented for DMS filters of wide bandwidth, and it is demonstrated how device performances are improved by proper design accounting for the criteria.     

Characteristics of alpha-glucosidase production from recombinant Aspergillus oryzae by membrane-surface liquid culture in comparison with various cultivation methods

alpha-Glucosidase was produced using recombinant Aspergillus oryzae by membrane-surface liquid culture (MSLC), a method previously developed by the authors and the results compared with other methods, including shaking flask culture (SFC), agar-plate culture (APC), culture on urethane sponge supports (USC), and liquid surface culture (LSC) to determine possible reasons for the advantageous features of MSLC. When yeast extract was used as a nitrogen source, the amount of enzyme produced by MSLC was 5 or more times higher than those for SFC and LSC, but similar to that using APC. Enzyme production in USC was slightly lower than in MSLC and APC. Cell growth was similar irrespective of the cultivation method used. When NaNO3, a typical inorganic nitrogen source was used, enzyme production in all the cultures was lower than that using yeast extract. However, even using NaNO3, the amount of the enzyme produced by MSLC was 8 to 20 times higher than those by SFC, APC, USC, and LSC. Although cell growth using NaNO3 was similar to that for yeast extract in MSLC, it was markedly decreased in SFC, APC, and LSC. The reason for the difference in enzyme productivity for various cultivation methods using yeast extract and NaNO3 as a nitrogen source is discussed, on the basis of the experimental findings. The role of the oxygen transfer effect and gene expression levels in enzyme production were also examined.     

Microbial-ecological significance of sulfide precipitation within anaerobic granular sludge revealed by micro-electrodes study

Micro-electrodes were applied to anaerobic granular sludge, which was developed in a UASB reactor, to examine intra-granule profiles with respect to pH, glucose and sulfide. When glucose was employed as a bulk liquid substrate, the micro-electrodes study demonstrated the pH behavior along granule depth: pH decrement at the granule exterior portion due to acid formation (buildup of acidity), and subsequent pH increment at the granule inner portion due to the consumption of acid (buildup of alkalinity). Sulfide micro-electrode proved sulfate reduction that mostly occurred at the granule exterior portion. Chemical equilibrium consideration evidently explained the occurrence of ferric sulfide predominantly in the interior portion, which accounts well for the morphology of a representative double-layered structure of granules grown on a low level of sulfite. Inorganic elements distribution within anaerobic granule was examined by electron probe X-ray micro analysis (EPMA) and ICP methods. The presence of crystalline calcium carbonate (calcite) was identified by X-ray diffraction analysis.     

Differential dosimetry in a neutron-proton mixed field with low-pressure proportional counters

For a mixed radiation field of neutrons and protons, radiation events were discriminated between photons, neutrons, and protons using a thin plastic scintillator. Distributions of lineal energy were measured with low-pressure proportional counters (LPPCs). To estimate the distribution of lineal energy for ICRU muscle, measurements were carried out using A-150-walled, graphite-walled, ZrO2-walled, and Zr-walled counters. Data were corrected for different atomic compositions between the A-150 plastic and ICRU muscle.     

Effects of bulk wave radiation on IDT admittance on 42 degrees YX-LiTaO3

This paper investigates the effects of bulk acoustic wave (BAW) radiation on the admittance of interdigital transducers (IDTs) with significant internal reflections of shear horizontal (SH) type leaky surface acoustic waves (SAWs) on 42°YX-LiTaO₃(42-LT). Theoretical analysis is made by using the discrete Green function theory, and synchronous one-port resonators are analyzed. It is shown that the BAW radiation significantly affects the IDT characteristics even for resonators; under certain circumstances, BAWs launched from an IDT are converted into SH-type SAWs by the strong internal reflections, and they interact with the BAWs radiated by the IDT. Then, the net amount of the radiated BAW power is highly dependent upon the number of IDT finger pairs. For the precise simulation of devices based on the SH-type SAWs with strong internal reflections, the BAW radiation should carefully be taken into consideration. If the BAW radiation is ignored, the radiated power of the SH-type SAWs may seem to be negative above the BAW cut-off frequency     

Anomalous Magnetic-Field-Hysteresis of Quantum Oscillations in κ-(BETS)2FeBr4

Shubnikov-de Haas (SdH) oscillations are measured in the organic conductor, κ-(BETS)₂FeBr₄. In the canted antiferromagnetic (CAF) phase (μ₀ H < μ₀ H _c =5.2 T), hysteresis is clearly observed in both the background resistance and oscillation amplitude. The analyses of the Dingle temperatures in the CAF phase show that some disorder is induced in the down sweep from the field above H _c . A possible origin of the excess scattering is discussed.     

Device linearity comparison of uniformly doped and /spl delta/-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.6/Ga/sub 0.4/As metamorphic HEMTs

The uniformly doped and the /spl delta/-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.6/Ga/sub 0.4/As metamorphic high-electron mobility transistors (MHEMTs) were fabricated, and the dc characteristics and the third-order intercept point (IP3) of these devices were measured and compared. Due to more uniform electron distribution in the quantum-well region, the uniformly doped MHEMT exhibits a flatter transconductance (G/sub m/) versus drain-to-source current (I/sub DS/) curve and much better linearity with higher IP3 and higher IP3-to-P/sub dc/ ratio as compared to the /spl delta/-doped MHEMT, even though the /spl delta/-doped device exhibits higher peak transconductance. As a result, the uniformly doped MHEMT is more suitable for communication systems that require high linearity operation.