山口 匡

Development of coastal acoustic tomography is carried out as a long term measurement technique to get shallow water information. Since sound is propagated with reflection at sea bed and sea surface, it is important to estimate characteristics of sound propagation in shallow water. In this paper, we investigated the characteristic of the propagating sound wave using data of a reciprocal acoustic transmission experiment in Uchiura Bay. Direct wave was used to estimate travel time and amplitude variation. We estimated water temperature with high accuracy and observed that an amplitude fluctuation happened with a rapid change of travel time. We got basic acoustic characteristics of reciprocal transmission signals that are useful for temperature and current measurements in shallow water.

沿岸域や湾のような浅海域の海洋情報は環境保全, 漁業などの面で需要が多く, 温度, 流速場の3次元構造を長期連続的に観測する浅海域海洋音響トモグラフィーの開発が行われている。浅海域における広域音響計測では, 深海域と異なり海底や海面で反射するなど, 浅海域特有の音波伝搬特性を把握することが重要である。本報告では, 静岡県三津湾沿岸での双方向音波伝搬実験で得られた信号から双方向の伝搬音波の伝搬時間差を高精度で評価した結果について述べる。広域での水温変化が検出され, さらに位相を用いた高精度な伝搬時間差評価より, 非常に小さな流速成分を安定に求めることができた

現在, 医療現場では超音波診断装置の利点(非観血, 低侵襲, リアルタイム性)を活かした, びまん性肝疾患の定量診断法を実現することが強く望まれている.我々はこれまでに, 肝組織から得られるエコー信号の振幅分布特性に着目し, 統計的な信号処理を用いることで肝臓のRFエコー信号から特異な信号成分を抽出する手法を提案し, 病変組織と思われる情報を抽出してきたが, 抽出情報の物理的意味が明らかではなかった.そこで本研究では, 剖検肝試料を用いてin vitro実験を行い, 肝臓の病変組織とエコー信号からの抽出結果との関係について検証した.スライス方向に高密度でエコー信号を収集し, 同一の試料から複数毎の病理組織標本を作成し, エコー画像と病理組織画像からそれぞれ病変組織情報を抽出し, 両抽出結果から3次元像を構築した.両3次元像を用いて病変組織の抽出率及び構造の2つの観点から比較を行ったところ, 両者ともに高い相関が見られ, 提案手法の有効性を確認できた.

It is very important to diagnose liver cirrhosis noninvasively and correctly. In our previous studies, we proposed a processing technique to detect changes in liver tissue in vivo. In this paper, we propose the evaluation of the relationship between liver disease and echo information using autopsy specimens of a human liver in vitro. It is possible to verify the function of a processing parameter clearly and to compare the processing result and the actual human liver tissue structure by in vitro experiment. In the results of our processing technique, information that did not obey a Rayleigh distribution from the echo signal of the autopsy liver specimens was extracted depending on changes in a particular processing parameter. The fiber tissue structure of the same specimen was extracted from a number of histological images of stained tissue. We constructed 3D structures using the information extracted from the echo signal and the fiber structure of the stained tissue and compared the two. By comparing the 3D structures, it is possible to evaluate the relationship between the information that does not obey a Rayleigh distribution of the echo signal and the fibrosis structure.

It is very important to diagnose liver cirrhosis noninvasively and correctly. In our previous studies, we proposed a processing technique to detect changes in liver tissue in vivo. In this paper, we propose the evaluation of the relationship between liver disease and echo information using autopsy specimens of a human liver in vitro. It is possible to verify the function of a processing parameter clearly and to compare the processing result and the actual human liver tissue structure by in vitro experiment. In the results of our processing technique, information that did not obey a Rayleigh distribution from the echo signal of the autopsy liver specimens was extracted depending on changes in a particular processing parameter. The fiber tissue structure of the same specimen was extracted from a number of histological images of stained tissue. We constructed 3D structures using the information extracted from the echo signal and the fiber structure of the stained tissue and compared the two. By comparing the 3D structures, it is possible to evaluate the relationship between the information that does not obey a Rayleigh distribution of the echo signal and the fibrosis structure.

人工膝関節置換術後の重大な合併症として下肢深部静脈血栓症及びこれに伴う肺血栓塞栓症がある.これらは施術中に発生する血栓などの塞栓子が引き起こす疾患であるため, 塞栓子の流量や流れの様子を知ることが, 治療及び予防において重要とされている.そこで本研究では, 人工膝関節置換術直後に取得した経食道心エコー画像に対してFSET(Fiber Structure Extraction Technique)処理を適用することにより, 画像中から心腔を流れる塞栓子情報の抽出を行い, その経時変化を観察した.

A systematic experimental and modeling study is reported. which characterizes the low-frequency noise spectrum of 100 nm-MOSFETs accurately. Two kinds of measured spectra are observed: 1/f and non-1/f spectra. The non-1/f spectrum is analysed by forward and backward measurements with exchanged source and drain, and shown to be due to a randomly distributed inhomogeneity of the trap density along the channel and within the gate oxide. By averaging the spectra of identical MOSFETs on a wafer the measured non-1/f noise spectra reduce to a 1/f characteristics. On the basis of these measurement data a noise model for circuit simulation is developed. which reproduces the low-frequency noise spectrum with a single model parameter for all gate lengths and under any bias conditions.

Equine herpesvirus 1 (EHV-1) is a pathogen causing rhinopneumonia in young horses, abortion in mares, and myeloencephalitis in adult horses. Two types, EHV-1 P and EHV-1 B, have recently been dominant among 16 electropherotypes. EHV-1 P and EHV-1 B viruses were compared by long and accurate polymerase chain reaction (LA-PCR) and restriction fragment length polymorphism (RFLP) analysis. Differences in restriction sites were found to be focused in ORF64, which encodes the infected cell protein 4 (ICP4), and downstream of the ICP4 gene. The 3'-end and downstream of ICP4 gene of EHV-1 B were found to be replaced by the corresponding region of EHV-4, indicating that EHV-1 B is a naturally occurring recombinant virus between progenitors of EHV-1 P and EHV-4. This is the first report showing a natural interspecies recombinant in alphaherpesviruses.

Two common viral diseases in psittacine birds including budgerigar fledgling disease (BFD), generally called avian polyomavirus (APV) infection, and psittacine beak and feather disease (PBFD) have similar clinical manifestations characterized by feather disorders. A duplex shuttle PCR was developed for detection of APV and PBFD virus (PBFDV). Two pairs of oligonucleotide primers were designed to amplify a 298-bp fragment of the t/T antigen region of APV genome and a 495-bp fragment of the capsid protein region encoded by open reading frame (ORF) C1 of PBFDV genome, respectively. In the present study, APV and PBFDV were detected simultaneously in one tube by duplex shuttle PCR using these two pairs of primers. The detection limits were 2 viral copies of APV and 3 viral copies of PBFDV. In the clinical application, we detected 16 APV-positive, 15 PBFDV-positive, and 3 mixed infected samples in 39 samples examined. Sequences of the amplified products were read. The t/T antigen region was conserved in the APV-positive samples as expected. ORF C1 of PBFDV genome showed diversity. Phylogenic analysis indicated that PBFDV ORF C1 consisted of 6 clusters which were related to subfamilies of psittacine birds. Our duplex shuttle PCR could be a useful method for differential diagnosis and molecular epidemiology of BFD and PBFD.

Adaptive equalization is essential in achieving wider system margins, such as tilt margin and defocus margin, in optical disk systems using partial response maximum likelihood (PRML) detection method. The most conventional method is the combination of the use of the least-mean-squares (LMS) algorithm and partial response (PR) equalization, but it does not optimize the characteristics of equalizers in terms of bit error rate (BER) performance. Integrating the concept of sequenced amplitude margin (SAM) with LMS, we developed a new adaptive equalization method, called least-mean-squared SAM error (LMSAM), which can minimize BER. After explaining the basic idea of LMSAM, we theoretically derived its implementable algorithm. We also reported favorable experimental results on the remarkable improvement of the tangential tilt margin and defocus margin with LMSAM. Furthermore, we analyzed the result from the viewpoint of frequency response and clarified why LMSAM can improve tilt margin.

我々はこれまでに,超音波エコーを用いて,慢性肝炎・肝硬変などのびまん性肝疾患を対象とした定量的な評価法の検討を試みてきた.その手法はエコー信号の振幅特性に着目したもので,振幅分布特性解析および非正常組織情報の抽出の2つの解析処理を用いている.本報告では,これらの解析処理をシミュレーションデータおよび臨床データに対して行うことで,用いた解析処理の有効性・妥当性について検討した。また,用いた指標の相関性を検討したところ,両者にはよい相関があるが,正常肝臓に対して異なる特性があることがわかった。さらに,病変進行に伴う組織構造の変化に処理結果がどのように反応しているのか,ROI中のエコー情報にどの程度の組織性状・構造が反映されているかを,総計情報の2次元分布を求めることで検討し,臨床データで安定な結果を得るための知見を得た.

The medical diagnosis using the ultrasonic cross section image has made remarkable result, and the ultrasonic diagnostic equipment is widely used. However, experience and skill of the doctor are required for the diagnosis using the ultrasonic image. We have been developing quantitative diagnostic techniques of liver diseases which can be applied to the clinical field. In this paper, we present the quantitative estimation results of diffused liver diseases. In the normal liver, many scatterers are distributed randomly, and the cross-section image obtained using an ultrasonic imaging system has many granular patterns referred to as a speckle pattern. The probability density function of the echo amplitude from the normal livers agrees well with the Rayleigh distribution function. The cirrhotic liver has many fibrotic tissue structures known as nodule structures. This echographic pattern changes with the progression of a disease such as cirrhosis. Using the processing technique that can suppress the signals from the randomly distributed scatterers which correspond to the normal liver, we extracted the quantitative information of the diseased tissue from RF echo signal of liver cirrhosis and chronic hepatitis.

Coxiella burnetti is the agent of the worldwide zoonosis, Q fever. The in vitro susceptibility to tetracycline and fluoroquinolones of Japanese isolates of C burnetii was evaluated for the first time. The MICs against Japanese isolates were almost the same as the MICs against the foreign reference isolates. The results suggest that the common antibiotics therapy for Q fever used in other countries is also effective for Japanese Q fever patients.

Nucleotide sequences of the intergenic region between ORF 62 and ORF 63 of equine herpesvirus 1 (EHV-1) isolates were analyzed. The sequences of this region consisted of variable and conserved domains among EHV-1 isolates. An EHV-1 mutant, Ab4-GFP, was constructed by inserting a green fluorescent protein (GFP) expression cassette flanked by loxP at both ends into the intergenic region between ORF 62 and ORF 63. Another mutant, Ab4-loxP, which contains one loxP site, was constructed by excision of the GFP cassette from the Ab4-GFP virus genome by cre enzyme. The recombinant Ab4-GFP formed smaller plaques than the wild type in MDBK cells. Virus production also decreased for Ab4-GFP in multistep growth analyses. Virulence of Ab4-GFP in both mice and hamsters was weaker than that of the wild type. Ab4-loxP exhibited properties similar to those of the wild type. These results suggest that the intergenic region between ORF 62 and ORF 63 plays various roles in the virus growth.

The genetic variation of Japanese isolates of Coxiella burnetii, the agent of Q fever, was found for the first time. Forty-nine out of 72 isolates had the chronic pattern of the isocitrate hydrogenase gene. Sequence analysis revealed that the isolates have a specific nucleotide sequence. The putative amino acid sequence was the same as that of chronic reference strains. These results suggest the variation of C. burnetii isolates in Japan.

本研究では,エコー信号の振幅特性を用いた組織性状診断法を確立するために,生体組織の音響特性と組織の物理的・化学的構造変化の関係を考慮し,複数のアプローチで検証を行っている。生体から摘出した6例の硬変肝剖検試料を対象とし,水槽実験において収集した200枚のエコー信号において非レイリー分布となる情報のみを抽出し,3次元構造を構築した結果,複数の線状の構造物が確認された。また,エコー信号を収集後に組織切片を作成し,超音波顕微鏡を用いて生体音響特性(音速・減衰)を計測した結果,正常肝及び結節組織に比較して線描組織では分散が大きいことが確認された。生体組織構造を詳細に把握するために,剖検試料から複数の病理組織写真を作成し,染色情報を元に線維組織構造を3次元で再構築し,エコー信号の処理結果及び生体音響特性の計測結果と比較したところ,エコー信号から得られた線状の構造物及び減衰が大きい部位が繊維部であることが確認された。

A novel method of electron-beam (EB) writing to reduce line-edge roughness (LER) called edge-enhancement writing (EEW) is described. EEW involves writing a fine line along a pattern edge at a high dose. This provides a steep profile of the energy deposited at the edge. The high exposure dose breaks up aggregates of resist polymer at the edge, which cause LER. Moreover, in EEW the background energy in unexposed regions due to proximity effects is also reduced by control of the dose. This increases the energy contrast at the edge, thereby preventing the appearance of aggregates on the sidewall due to undesired dissolution of the edge region. The resulting energy profile is quite different from that obtained with conventional proximity effect corrections. Experimental results and simulations of the deposited energy profile have demonstrated the effectiveness of EEW.

Ultrasonic B-mode images are affected by changes in scatterer distribution. It is hard to estimate the relationship between the ultrasonic image and the tissue structure quantitatively because we cannot observe the continuous stages of liver cirrhosis tissue clinically, particularly the beginning stage. In this paper, we propose a three-dimensional modeling method of scatterer distribution for normal and cirrhotic livers to confirm the influence of the change in the form of scatterer distribution on echo information. The algorithm of the method includes parameters which determine the expansion of nodules and fibers. Using the B-mode images which are obtained from these scatterer distributions, we analyze the relationship between the changes in the form of biological tissue and the changes in the B-mode images during progressive liver cirrhosis.

Ultrasonic B-mode images are affected by changes in scatterer distribution. It is hard to estimate the relationship between the ultrasonic image and the tissue structure quantitatively because we cannot observe the continuous stages of liver cirrhosis tissue clinically, particularly the beginning stage. In this paper, we propose a three-dimensional modeling method of scatterer distribution for normal and cirrhotic livers to confirm the influence of the change in the form of scatterer distribution on echo information. The algorithm of the method includes parameters which determine the expansion of nodules and fibers. Using the B-mode images which are obtained from these scatterer distributions, we analyze the relationship between the changes in the form of biological tissue and the changes in the B-mode images during progressive liver cirrhosis.

Small-size MOSFETs are becoming core devices in RF applications because of improved high frequency characteristics. For reliable design of RF integrated circuits operating at the GHz range, accurate modeling of small-size MOSFET characteristics is indispensable. In MOSFETs with reduced gate length (L.), the lateral field along the MOSFET channel is becoming more pronounced, causing short-channel effects. These effects should be included in the device modeling used for circuit simulation. In this work, we investigated the effects of the field gradient in the gate-drain capacitance (C-gd). 2-Dimensional (2D) simulations done with MEDICI show that the field gradient, as it influences the channel condition, induces a capacitance which is visible in the MOSFET saturation operation. Changes in Cgd is incorporated in the modeling by an induced capacitance approach. The new approach has been successfully implemented in the surface-potential based model HiSIM Hiroshirna-university STARC (GFET Model) and is capable of reproducing accurately the measured C-gd-L-g characteristics, which are particularly significant for pocket-implant technology. Results show that pocket-implantation introduces a steep potential increase near the drain region, which results to a shift of the C-gd transition region (from linear to saturation) to lower bias voltages. C-gd at saturation decreases with L-g due to steeper surface potential and increased impurity concentration effects at reduced L-g.