Mariko Ogawa

In vitro characterization of the RS motif in N-terminal head domain of goldfish germinal vesicle lamin B3 necessary for phosphorylation of the p34cdc2 target serine by SRPK1

The nuclear envelopes surrounding the oocyte germinal vesicles of lower vertebrates (fish and frog) are supported by the lamina, which consists of the protein lamin B3 encoded by a gene found also in birds but lost in the lineage leading to mammals. Like other members of the lamin family, goldfish lamin B3 (gfLB3) contains two putative consensus phosphoacceptor p34cdc2 sites (Ser‐28 and Ser‐398) for the M‐phase kinase to regulate lamin polymerization on the N‐ and C‐terminal regions flanking a central rod domain. Partial phosphorylation of gfLB3 occurs on Ser‐28 in the N‐terminal head domain in immature oocytes prior to germinal vesicle breakdown, which suggests continual rearrangement of lamins by a novel lamin kinase in fish oocytes. We applied the expression‐screening method to isolate lamin kinases by using phosphorylation site Ser‐28‐specific monoclonal antibody and a vector encoding substrate peptides from a goldfish ovarian cDNA library. As a result, SRPK1 was screened as a prominent lamin kinase candidate. The gfLB3 has a short stretch of the RS repeats (9‐SRASTVRSSRRS‐20) upstream of the Ser‐28, within the N‐terminal head. This stretch of repeats is conserved among fish lamin B3 but is not found in other lamins. In vitro phosphorylation studies and GST‐pull down assay revealed that SRPK1 bound to the region of sequential RS repeats (9–20) with affinity and recruited serine into the active site by a grab‐and‐pull manner. These results indicate SRPK1 may phosphorylate the p34cdc2 site in the N‐terminal head of GV‐lamin B3 at the RS motifs, which have the general property of aggregation.

Power-stage frequency response cancellation of DC-DC converter with digital control

Recently, the performance of the DSP and FPGA is developed remarkably. So, fully digital control is enabled in switch mode power supplies. However, in many cases, the control system is built by very complicatedly and very difficult theories such as the adaptive control. Furthermore, in most popular PID control, its design method of the parameters is not clear, so derivation of the optimal parameters is very difficult. This paper proposes the interesting control technique which is cancelled the transfer function of the converter by using pole-zero-cancellation method. This technique is very simple and easy to stability design.

Consideration for the malfunction of semiconductor circuit breaker in high voltage DC power supply system

This paper considers the malfunction mechanism of semiconductor circuit breaker in high voltage DC power supply system (HVDC). In HVDC system, the fast response breaker is required. Semiconductor circuit breaker is paid attention as one of the key technology in HVDC. However, in some condition, the semiconductor circuit is malfunctioned. When malfunction is happened, unexpected large current is flown to the other normal line. In this paper, the generation mechanism of unexpected-current is described.

Dynamic characteristics improvement of digital controlled DC-DC converter by means of PZC control

Recently, the performance of the DSP and FPGA is developed remarkably. So, fully digital control is enabled in switch mode power supplies. However, in many cases, the control system is built by very complicatedly and very difficult theories such as the adaptive control, predictive control, and so on. Furthermore, in most popular PID control, its design method of the parameters is not clear, so derivation of the optimal parameters is very difficult. This paper proposes revolutionary control technique which is cancelled the transfer function of the converter completely by using pole-zero-cancellation method. This technique is very simple and easy to stability design.

Dynamic characteristics of digitally controled conveter with pole-zero-cancellation techique

Recently, the performance of the DSP and FPGA is developed remarkably. So, fully digital control is enabled in switch mode power supplies. However, in many cases, the control system is built by very complicatedly and very difficult theories such as the adaptive control. Furthermore, in most popular PID control, its design method of the parameters is not clear, so derivation of the optimal parameters is very difficult. This paper proposes the interesting control technique which is cancelled the transfer function of the converter by using pole-zero-cancellation method. This technique is very simple and easy to stability design.

Malfunction suppression of semiconductor circuit breaker in high voltage DC power supply system

In high voltage DC power supply system (HVDC) system, the fast response breaker is required. Semiconductor circuit breaker is paid attention as one of the key technology in HVDC. However, in some condition, the semiconductor circuit is malfunctioned. When malfunction occurs, unexpected large current is flown to the other normal line. In this paper, the malfunction suppression of semiconductor circuit breaker is described. It demonstrated by using MATLAB/Simulink Moreover, the demonstrated results are confirmed by experimentally.

Malfunction mechanism of semiconductor circuit breaker in HVDC power supply system

This paper considers the malfunction mechanism of semiconductor circuit breaker in high voltage DC power supply system (HVDC). In HVDC system, the fast response breaker is required. Semiconductor circuit breaker is paid attention as one of the key technology in HVDC. However, in some condition, the semiconductor circuit is malfunctioned. When malfunction is happened, unexpected large current is flown to the other normal line. In this paper, the malfunction mechanism of semiconductor circuit breaker is considered. It demonstrated by using MATLAB/Simulink. Moreover, the demonstrated results are confirmed by experimentally.

Investigation of parameter tolerance on digitally controlled DC-DC converter with pole-zero-cancellation technique

This paper proposes an interesting control technique which cancels the transfer function of the converter by using pole-zero-cancellation method. The system stabilization design is easy to be realized by applying this technique. The impaired system stability caused by parameter variation is investigated, especially the influence of the output capacitance variation. Moreover, a parameter tracking method is included to solve the stability problem.

Frequency response improvement of DSP controlled DC-DC converter with pole-zero cancellation technique

Reentry, the performance of the DSP and FPGA is developed remarkably. So, fully digital control is enabled in switch mode power supplies. However, in many cases, the control system is built by very complicatedly and very difficult theories such as the adaptive control. Furthermore, in most popular PID control, its design method of the parameters is not clear, so derivation of the optimal parameters is very difficult. This paper proposes revolutionary control technique which is cancelled the transfer function of the converter by using pole-zero-cancellation method. This technique is very simple and easy to stability design.

Transient current circuit for switching loss reduction in buck converters

In this paper, a transient current circuit is introduced. The circuit evidently reduces switching loss of buck converter main switch dramatically. This topology enables to operate high-frequency. The validity of the transient current circuit is verified through simulations and experiments.