Bidirectional finite-element method-of-line beam propagation method(FE-MoL-BPM) for analyzing optical waveguides with discontinuities

A bidirectional finite-element method-of-line beam propagation method (FE-MoL-BPM) is newly proposed for analyzing optical waveguides with discontinuities including transmissions, reflections and radiations. In this approach, the finite-element method (FEM) is introduced to discretize the derivatives of the variable perpendicular to the propagation direction. Since the proposed method is accurate and stable, only a small number of nodal points are required     

Large aperture superconducting magnet (benkei)

Benkei, which was a large window frame conventional magnet at KEK has been converted to a superconducting magnet. In the conversion, the pole gap has been doubled from 0.5 m to 1.0 m retaining an analysing power at 2 T m. Several new techniques were applied to coil windings and cryostat fabrication. The superconducting Benkei has shown satisfactory performances for long term operation.     

Sequential hemodynamic activation of motor areas and the draining veins during finger movements revealed by cross-correlation between signals from fMRI

Activity in the human supplementary motor area (SMA), primary motor cortex (M1), and the draining vein of the motor cortex during a visually triggered finger opposition task was measured by functional magnetic resonance imaging with a repetition time of 1 s. Sequential hemodynamic activation in these areas was revealed by cross-correlating a signal sequence in M1 directly with signal sequences from SMA and the draining vein, and applying polynomial fitting with the aid of Akaike's information criterion. We succeeded in detecting a time delay of approximately 0.5 s between the activations of SMA and M1, and a delay of nearly 1.3 s between the activations of M1 and its draining vein. The new combination of fMRI and data analysis techniques has attained a time resolution comparable to those in preceding studies that used shorter fMRI repetition times of 100-200 ms.     

Para-aortic lymph node metastasis in carcinoma of the distal bile duct

BACKGROUND/AIMS: Lymph node dissection plays an important role in radical surgery for pancreaticoduodenal carcinomas. The aim of this study was to identify the critical areas of lymph node dissection in carcinoma of the distal bile duct. METHODOLOGY: Between January 1995 and December 1996, 20 consecutive patients with distal bile duct cancer underwent pancreaticoduodenectomy with extended lymph node dissection (including the para-aortic nodes). Histopathologic findings were examined with special reference to lymph node metastasis. RESULTS: Histological evidence of lymph node metastasis was found in 11 patients (55%). The areas with frequent metastases were the posterior pancreaticoduodenal lymph nodes (35%), and the nodes around the hepatoduodenal ligament (35%) and around the common hepatic artery (30%). Para-aortic lymph node involvement was identified in 5 patients (25%). Most of these existed in the inter-aorticocaval space. Pancreatic parenchymal invasion was present in 10 patients. Half of the patients with pancreatic invasion had para-aortic nodal involvement. Para-aortic lymph node metastasis was significantly associated with pancreatic parenchymal invasion (p<0.05). CONCLUSIONS: In carcinoma of the distal bile duct with pancreatic parenchymal invasion, extended lymph node dissection (including para-aortic nodes) should be undertaken because of the relatively high incidence of metastasis.     

0.81 ?m band AlGaAs/GaAs double-channel planar buried-heterostructure laser with large optical cavity

0.81 ?m-band AlGaAs/GaAs double-channel planar buried-heterostructure laser diodes with large optical cavity have been developed as light sources for use in analogue optical fibre communication systems. Linear light-output/current characteristics and a single-longitudinal-mode spectrum at a modulation frequency f = 100 MHz with modulation index m = 0.9 have been attained.     

Lubricity of volatile lubricants in sheet metal rolling

A series of experiments is carried out by using a rolling type tribometer to investigate the lubricity of the volatile lubricants at high speed forming. The roll material is the die steel alloy SKD11, and the workpiece material is the mild steel SPCE with a rough surface and the aluminum alloy A3004 with a smooth surface. Experimental results show that the friction coefficient decreases with increasing working velocity for both SPCE and A3004, in any lubricant. With an increase of reduction in thickness, the friction coefficient decreases for SPCE, but increases for A3004. Some volatile lubricants have the same lubricity as the generally used mineral oil with low-viscosity by judging from the value of friction coefficient, the surface appearance of rolled workpiece and the roll surface damage.     

Site-directed mutagenesis study of the antibody 2D7 which catalyzes a reaction for insertion of Cu2+ into mesoporphyrin

Monoclonal antibody 2D7 generated against a transition-state analog N-methyl mesoporphyrin catalyzes a reaction for insertion of a cupric ion into mesoporphyrin. To investigate amino acid residues responsible for the catalytic activity, site-directed mutagenesis of the amino acid residues in the third complementarity determining region of the heavy chain (CDRH3) was performed on the antigen-binding fragment (Fab) of the antibody. Recombinant Fab mutants, in which Arg95 is replaced with Ala (R95A), Asp96 with Asn (D96N) and Met97 with Gly (M97G), were examined in terms of the catalytic efficiency of the reaction (k/K(S)) and the dissociation constant for N-methyl mesoporphyrin binding (K(d)) and these values were compared with those of the wild type. The k/K(S) values of the R95A and D96N mutants were 0.96% and 1.0% of that of the wild type, respectively, whereas the M97G mutant had no detectable catalytic activity. The K(d) values of the R95A and D96N mutants were 165 and 69 times that of the wild type, respectively, while that of the M97G mutant was similar to that of the wild type. The relationship between the k/K(S) and 1/K(d) values in the wild type and the R95A and D96N mutants suggests that Arg95 and Asp96 are responsible for stabilizing the transition-state in the catalytic reaction. The results of the M97G mutant allow us to propose that Met97 plays an important role in the catalytic activity probably due to a subtle and specific conformation of the antibody.