Numerical analysis of plasmon-resonance absorption in bisinusoidal metal gratings

We numerically investigate plasmon-resonance absorption of incident light energy by a bisinusoidal metal grating, i.e., one whose surface profile is sinusoidally corrugated in two orthogonal directions with a common period. Employing Yasuura's modal expansion method, we solve the problem of plane-wave diffraction by the grating and evaluate the absorption, which is observed as dips in diffraction efficiency curves. We examine the field distribution and energy flow in detail at the angles of incidence at which the absorption occurs. We show that the absorption is caused by coupling of the TM component of an evanescent order with surface plasmons. A phase-matching condition is used in the prediction of the incident angle at which the absorption occurs. This, together with the field profile in the presence of the resonance absorption, explains the mechanism of the absorption. We then illustrate interesting features of the absorption: enhancement of polarization conversion between the incident light and the reflected light and simultaneous excitation of two plasmon waves in directions that are symmetric with respect to the plane of incidence.     

Design Of Anti‐Slip Controller For An Electric Vehicle With An Adhesion Status Analyzer Based On The Ev Simulator

The In this paper, a simulator of a one‐wheel Electric Vehicle system is designed for testing an anti‐slip controller using the Motor‐Generator system. The drive motor of the M‐G system is used to simulate the drive wheel of the Electric Vehicle, and the load motor is used to simulate the load force of the chassis. In the driving process, the torque of the load motor is changed according to the drive force of the chassis that is calculated by the program. So it can simulate the dynamic process of the tire‐road system. Based on this simulator system, an anti‐slip controller based on an Adhesion Status Analyzer is proposed. Information about the wheel speed is acquired by using a Back EMF Observer. A load torque disturbance observer is designed to stabilize the acceleration of the wheels. The Adhesion Status Analyzer is used to generate safe acceleration commands for the anti‐slip controller. When a slip occurs, the anti‐slip controller will decrease the torque quickly, and at the same time, by estimating the dynamic status of adhesion, the Adhesion Status Analyzer will restrain the acceleration command within a safe area. The effectiveness of the proposed approach is verified by using the EV slip simulator.     

Acrobot control by learning the switching of multiple controllers

Reinforcement learning (RL) has been applied to constructing controllers for nonlinear systems in recent years. Since RL methods do not require an exact dynamics model of the controlled object, they have a higher flexibility and potential for adaptation to uncertain or nonstationary environments than methods based on traditional control theory. If the target system has a continuous state space whose dynamic characteristics are nonlinear, however, RL methods often suffer from unstable learning processes. For this reason, it is difficult to apply RL methods to control tasks in the real world. In order to overcome the disadvantage of RL methods, we propose an RL scheme combining multiple controllers, each of which is constructed based on traditional control theory. We then apply it to a swinging-up and stabilizing task of an acrobot with a limited torque, which is a typical but difficult task in the field of nonlinear control theory. Our simulation result showed that our method was able to realize stable learning and to achieve fairly good control.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

Impurity scattering effect on the anisotropic resistivity for La2−x Sr x CuO4−δ with a wide range of x

We have investigated the effect of the impurity scattering due to a small amount of oxygen defect, ( < 0.01) on the anisotropic resistivity of La _2–x Sr _x CuO _4– in a wide x range up to x = 0.26. In the superconducting region with 0.06 x 0.22, we found that impurity scattering by the oxygen defect remarkably decreases the c-axis resistivity c over the whole temperature range. The finding is interpreted in terms of the nonmetallic conduction along the c axis which is enhanced by scattering the confined carriers in the CuO ₂ plane. On the other hand, the enhancement of the c-axis conduction diminishes in the nonsuperconducting region. This is consistent with the two-dimensional nature of the electronic state which stabilizes the superconducting ground state in the cuprates.     

Collagen and elastin synthesis by desmoid tumor in vitro

In order to characterize human desmoid tumors in vitro, the production of collagen and elastin and the expression of collagen types alpha1(I), alpha1(III) and transforming growth factor (TGF)-beta1 mRNA were investigated in six desmoid tumors; five derived from familial adenomatous polyposis patients and one from a sporadic case. The proportion of collagen production to total protein production was determined by 3H-imino acid incorporation, an indicator of collagen synthesis, using high-performance liquid chromatography (HPLC). The proportion of collagen production to total protein production was much higher in all six desmoid tumors compared with human skin fibroblasts (HSF). Quantitatively, the rate of elastin synthesis in desmoid tumor cells monitored by valine-proline peptide was also significantly higher than in HSF. Pro-alpha1(I) collagen mRNA was highly expressed in both desmoid tumors and HSF at approximately the same level, whereas pro-alpha1(III) collagen mRNA was more abundant in some of the desmoid tumors than the normal skin fibroblastic cell lines. Tumor growth factor-beta1 mRNA, which is believed to stimulate collagen synthesis, was expressed in both desmoid tumors and HSF to the same extent. These results demonstrate the increased formation of collagen and elastin in desmoid tumors in vitro and suggest that the increased synthesis of elastin rather than of collagen and TGF-beta1 may be involved in increased fibrogenesis by desmoid tumors.     

Structures of new acylated oleanene-type triterpene oligoglycosides, theasaponins E1 and E2, from the seeds of tea plant, Camellia sinensis (L.) O. Kuntze

Friedreich's ataxia is the first known autosomal recessive disease caused by an unstable trinucleotide expansion mutation. The most frequent mutation is expansion of a GAA repeat in the first intron of gene X25. We studied transmission of the expanded GAA repeat in 37 Friedreich's ataxia pedigrees and analysed blood and sperm alleles in eight patients. We showed intergenerational instability in 84% of the alleles with an overall excess of contractions. Both contractions and expansions of the GAA repeat occurred in maternal transmission with a stronger tendency to expand for smaller repeats and to contract for longer repeats. Paternally transmitted alleles contracted only. Parental age and the intergenerational change in expansion size were directly correlated in maternal transmission and inversely in paternal transmission. The size of the GAA expansion was slightly lower in patients than heterozygous carriers. Sperm analysis confirmed the tendency to contract of paternal alleles, which was more marked with ageing. The degree of contraction of the GAA repeat in sperm was much higher than that found in intergenerational transmission and was directly related to the repeat size. A blood expanded allele reverted to normal size in the sperm of one patient. This study suggests the existence of different mutational mechanisms in Friedreich's ataxia alleles, which occur both pre- and post-zygotically.     

Caenorhabditis elegans has two isozymic forms, CE-1 and CE-2, of fructose-1,6-bisphosphate aldolase which are encoded by different genes

Two distinct types of cDNAs for fructose-1,6-bisphosphate (FBP) aldolase, Ce-1 and Ce-2, have been isolated from nematode Caenorhabditis elegans, and the respective recombinant aldolase isozymes, CE-1 and CE-2, have been purified and characterized. The Ce-1 and Ce-2 are 1282 and 1248 bp in total length, respectively, and both have an open reading frame of 1098 bp, which encodes 366 amino acid residues. The entire amino acid sequences deduced from Ce-1 and Ce-2 show a high degree of identity to one another and to those of vertebrate and invertebrate aldolases. The highest sequence diversity was found in the carboxyl-terminal region that corresponds to one of the isozyme group-specific sequences of vertebrate aldolase isozymes that play a role in determining isozyme-specific functions. Southern blot analysis suggests that CE-1 and CE-2 are encoded by different genes. Concerning general or kinetic properties, CE-2 is quite different from CE-1. CE-1 exhibits unique characteristics which are not identical to any aldolase isozymes previously reported, whereas CE-2 is similar to vertebrate aldolase C. These results suggest that CE-2 might preserve the properties of a progenitor aldolase with a moderate preference for FBP over fructose 1-phosphate (F1P) as a substrate, whereas CE-1 evolved to act as an intrinsic enzyme that exhibits a much broader substrate specificity than dose CE-2.     

Real-time output voltage control method of quasi-ZCS seriesresonant HF-linked DC-AC converter

This paper proposes a real-time control method of a series resonant high-frequency linked DC-AC converter employing quasi-zero current switching (quasi-ZCS) and a feedback control method for sinusoidal output voltage. An approximate analysis of the converter is performed, and then simplified equations and an equivalent circuit similar to the conventional PWM inverters/inverters are obtained. A real-time feedback control of the converter is realized using the equivalent circuit without detecting HF link current. The usefulness of the proposed control algorithm is confirmed by experimental results     

Generation of single-walled carbon nanotubes from alcohol and generation mechanism by molecular dynamics simulations

Recent advances in high-purity and high-yield catalytic chemical vapor deposition (CVD) generation of single-walled carbon nanotubes (SWNTs) from alcohol are comprehensively presented and discussed on the basis of results obtained from both experimental and numerical investigations. We have uniquely adopted alcohol as a carbon feedstock, and this has resulted in high-quality, low-temperature synthesis of SWNTs. This technique can produce SWNTs even at a very low temperature of 550 degrees C, which is about 300 degrees C lower than the conventional CVD methods in which methane or acetylene is typically used. We demonstrate the excellence of the proposed alcohol catalytic CVD method for high-yield production of SWNTs when Fe-Co on USY-zeolite powder was used as a catalyst. At optimum CVD conditions, a SWNT yield of more than 40 wt % was achieved over the weight of the catalytic powder within the reaction time of 120 min. In addition to the advantages for mass production, this method is also suitable for the direct synthesis of high-quality SWNTs on Si and quartz substrates when combined with the newly developed liquid-based "dip-coat" technique to mount catalytic metals on the surface of substrates. This method allows easy and costless loading of catalytic metals without the need for any support or underlayer materials that were usually required in previous studies for the generation of a sufficient quantity of SWNTs on an Si surface. Finally, the result of molecular dynamics simulation for the SWNT growth process is presented to obtain a fundamental insight into the initial growth mechanism on the catalytic particles.     

Highly specific enzyme immunoassay for human chorionic gonadotropin

A highly specific enzyme immunoassay for determining hCG was established by using beta-D-galactosidase as label. In order to increase the specificity of the assay, an antiserum against whole hCG was purified on a column of hCG beta carboxyl-terminal peptide (residues 123-145) covalently linked to Sepharose 4B. The antibody (N101S) thus prepared showed a weak cross-reactivity with human LH in an assay using hCG-enzyme conjugate, but the slight cross-reactivity was virtually avoided when an hCG beta carboxyl-terminal peptide was used as a peptide in the enzyme conjugate. N101S antibody was compared with antiserum (B1B) directed against a carboxyl-terminal peptide (123-145). In hCG measurement N101S gave about 30 times higher sensitivity than B1B, although the former antibody was less sensitive to carboxyl-terminal peptides of hCG beta. The enzyme immunoassay using a combination of N101S antibody and a carboxyl-terminal peptide (130-145)-enzyme conjugate was able to detect as little as 0.25 mIU of hCG without the interference of LH. The performance and validity of this assay were comparable to those of conventional radioimmunoassay.