Theory of transport coefficients. I. General theory and electrical conductivity of electron-phonon system

A general method is presented for the calculation of static transport coefficients based on Kubo's formulas. Techniques of perturbation expansion, diagram representation, and linked-cluster expansion are used. As an example, the electrical conductivity of an electron-phonon system is calculated with the natural introduction of irreversibility, following the ideas of Van Hove, and Prigogine and his collaborators. Under certain conditions the present method is shown to be equivalent to the conventional method by means of the Boltzmann equation. These conditions are examined and the improvement of the approximation is discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Assessment Report of Doctoral Theses

圧流動床複合発電システムにおける排ガス成分の生成メカニズムと濃度予測手法の確立[阿部

A Digital Hysteresis Current Control for Half-Bridge Inverters with Constrained Switching Frequency

This paper proposes a new robustly adaptive hysteresis current digital control algorithm for half-bridge inverters, which plays an important role in electric power, and in various applications in electronic systems. The proposed control algorithm is assumed to be implemented on a high-speed Field Programmable Gate Array (FPGA) circuit, using measured data with high sampling frequency. The hysteresis current band is computed in each switching modulation period based on both the current error and the negative half switching period during the previous modulation period, in addition to the conventionally used voltages measured at computation instants. The proposed control algorithm is derived by solving the optimization problem—where the switching frequency is always constrained at below the desired constant frequency—which is not guaranteed by the conventional method. The optimization problem also keeps the output current stable around the reference, and minimizes power loss. Simulation results show good performances of the proposed algorithm compared with the conventional one

MPPT and SPPT Control for PV-Connected Inverters Using Digital Adaptive Hysteresis Current Control

Most PV systems are usually controlled by a Maximum Power Point Tracking (MPPT) algorithm to maximize the generated electrical power. However, the maximum power is often unstable and depends on the solar irradiance and temperature. This makes it difficult to control the power grid supply-demand balance due to fluctuations caused by the increase of renewable and variable PV systems. This paper proposes a new control algorithm for a PV-connected inverter called Specified Power Point Tracking (SPPT) control in addition to the conventional Maximum Power Point Tracking (MPPT) control. The PV system is controlled to generate the maximum power or a specified power depending on the electricity transactions comes from the electricity trading system. A high-speed FPGA-based digital adaptive hysteresis current control method, which has fast and stable response and simple structure comparing with the popular Sine-triangle Pulse Width Modulation (SPWM) method, is proposed to implement the MPPT and SPPT control. The adaptive hysteresis current band is calculated adaptively to improve a disadvantage of the classical fixed band hysteresis current control on the varying switching frequency. A reference current used in the adaptive hysteresis current control is calculated such that the output power of the PV-connected inverter is maximized in the MPPT control or is maintained at a given value in the SPPT control. The experimental and simulation results show that the PV-connected inverter under the proposed control algorithm generates the desired power almost exactly and yields stable and fast response despite the varying irradiance

Novel laminin-based microsystem for quantitative analysis of axonal haptotaxis

We present a novel microsystem in which micro-scale patterns of laminin, a major component of the extracellular matrix, are fabricated on glass substrate. The laminin micro-patterns work as a substrate-bound regulator to modulate the directional migration of axonal growth cones in neurons, allowing the quantitative analysis of axonal haptotaxis in vitro. Moreover, the novel microsystem succeeded to visualize the movement of the L1 cell adhesion molecule (L1-CAM) on the axonal growth cone; this will contribute to understand the molecular mechanics underlying laminin-mediated axonal haptotaxis. Cell migrations mediated by L1-CAM is a key process involved in multiple diseases including brain malformation and cancer metastasis. Therefore, this novel microsystem will pave the way for innovative analytical and medical applications

学位論文審査報告

圧流動床複合発電システムにおける排ガス成分の生成メカニズムと濃度予測手法の確立[阿部

Grip and slip of L1-CAM on adhesive substrates direct growth cone haptotaxis

Chemical cues presented on the adhesive substrate direct cell migration, a process termed haptotaxis. To migrate, cells must generate traction forces upon the substrate. However, how cells probe substrate-bound cues and generate directional forces for migration remains unclear. Here, we show that the cell adhesion molecule (CAM) L1-CAM is involved in laminin-induced haptotaxis of axonal growth cones. L1-CAM underwent grip and slip on the substrate. The ratio of the grip state was higher on laminin than on the control substrate polylysine; this was accompanied by an increase in the traction force upon laminin. Our data suggest that the directional force for laminin-induced growth cone haptotaxis is generated by the grip and slip of L1-CAM on the substrates, which occur asymmetrically under the growth cone. This mechanism is distinct from the conventional cell signaling models for directional cell migration. We further show that this mechanism is disrupted in a human patient with L1-CAM syndrome, suffering corpus callosum agenesis and corticospinal tract hypoplasia

Early results of urethral dose reduction and small safety margin in intensity-modulated radiation therapy (IMRT) for localized prostate cancer using a real-time tumor-tracking radiotherapy (RTRT) system

Background: We prospectively assessed the utility of intensity-modulated radiation therapy (IMRT) with urethral dose reduction and a small margin between the clinical target volume (CTV) and the planning target volume (PTV) for patients with localized prostate cancer. Methods: The study population was 110 patients in low- (14.5%), intermediate- (41.8%), and high-risk (43.6%) categories. Three gold fiducial markers were inserted into the prostate. A soft guide-wire was used to identify the urethra when computed tomography (CT) scan for treatment planning was performed. A dose constraint of V70 < 10% was applied to the urethral region. Margins between the CTV-PTV were set at 3 mm in all directions. Patients were treated with 70 Gy IMRT in 30 fractions (D95 of PTV) over 7.5 weeks. The patient couch was adjusted to keep the gold markers within 2.0 mm from their planned positions with the use of frequent on-line verification. Results: The median follow-up period was 31.3 (3.2 to 82.1) months. The biochemical relapse-free survival (bRFS) rates at 3 years were 100%, 93.8% and 89.5% for the low-, intermediate-, and high-risk patients, respectively. The incidences of acute adverse events (AEs) were 45.5% and 0.9% for grades 1 and 2, respectively. The late AEs were grade 1 cystitis in 10.0% of the patients, rectal bleeding in 7.3%, and urinary urgency in 6.4%. Only three patients (2.7%) developed grade 2 late AEs. Conclusions: On-line image guidance with precise correction of the table position during radiotherapy achieved one of the lowest AEs rates with a bRFS equal to the highest in the literature