Behaviors of a Soliton in Nonlinear L-C Lines with Abrupt Parameter Change

Some behaviors of a lattice soliton in nonlinear L-C ladder lines with abrupt parameter change are investigated. The results of computer and circuit experiments show that in the case of a soliton incident upon the line of larger characteristic impedance and of higher phase velocity in linearized-line-limit, the transmitted wave evolves into larger number of solitons. The experimental results can be well explained by use of both linearization approximation for the line near the junction and the theory by Gardner, Greene, Kruskal and Miura

On the Phase Adjusting of a Magic T-Coupled Oscillators System

A magic T-coupled two oscillators system having arbitrary amount of phase adjusting errors is studied both theoretically and experimentally. Denoting two independent phase parameters of the system measured from their optimum values as Δφ and Δψ, it is derived analytically that the optimum operation is possible in principle in a definite region of Δφ - Δψ plane, so we have a considerable amount of margin for phase adjusting error. Experimental result also confirms the existence of some phase error margin, though the measured magnitude of margin is smaller to some extent than the theoretical prediction

A Theoretical Treatment of the Frequency Entrainment of a Reflex Klystron

The frequency entrainment of a reflex klystron is studied in a fundamental way by setting up the differential equation which describes the oscillation of the klystron cavity under application of an external signal. Under such a condition that the oscillator runs at its normal operation with no electronic susceptance and with matched loading, the problem is shown to be essentially analogous to the simmilar one in an ordinary vacuum-tube oscillator of lower frequency range. Within this limitation on the operation condition the bandwidth of frequency entrainment is estimated in relation to the power ratio of the externally applied signal and the output of the normally operating klystron oscillator. Phase retardation of the cavity oscillation in the entrained klystron from the phase of the externally applied signal is investigated. In connection with this subject, the self-excited oscillation of the reflex klystron is also introductively treated from the standpoint of the theory of nonlinear oscillation

Measurements on the Frequency Entrainment of a Reflex Klystron

The bandwidth of frequency entrainment of a reflex klystron was measured in relation to the power ratio of an applied external signal and the output of of the klystron at its normal operation. Measurements were also carried out on the output power of a frequency-entrained reflex klystron both for the various frequency deviations of signal frequency from that of the klystron at its normal operation and for the various power ratios. As a supplement to the theory previously reported by the authors, an analysis is given for the case when the klystron does not operate at the center of an electronic mode in the absence of an external signal. It is shown that the theory is in rather good agreement with the experimental results

A waveguide type power divider/combiner of double-ladder multiple-port structure

We propose a waveguide type microwave power divider/combiner of double ladder multiport structure which is advantageous for its very low insertion loss and high power capability. Analysis based on equivalent circuits give the design formula for perfect power dividing/combining. Numerical analysis gives optimal design parameters for broadband characteristics both of the divider and of the combiner. Analyses of power flows in the divider structure and isolation characteristic are given. Operation characteristics of divider-combiner system and the effect of phase deviation in combiner input signals on the combining efficiency are also discussed. Experiments showed good performances in accordance with the theory: the -0.5 dB relative bandwidths of four-, eight-, and twelve-way deciders were as large as 0.5, 0.38, and 0.38 respectively. For four- and eight-way divider-combiner systems, relative bandwidths were 0.22 and 0.13, respectively both with insertion loss of less than 0.1 d

A Wideband Microwave Power Divider/Combiner with Multiple-Port Double-Ladder Structure

We propose a new microwave power divider/combiner with multiple-port doubleladder structure for use in high power solid-state power amplifiers. Numerical and experimental analysis were carried out at X-band, and the results of the divider/combiner indicated low insertion loss and wide band characteristics in good accordance with the theory

A ternary complex model of Sirtuin4-NAD+-Glutamate dehydrogenase

Sirtuin4 (Sirt4) is one of the mammalian homologues of Silent information regulator 2 (Sir2), which promotes the longevity of yeast, C. elegans, fruit flies and mice. Sirt4 is localized in the mitochondria, where it contributes to preventing the development of cancers and ischemic heart disease through regulating energy metabolism. The ADP-ribosylation of glutamate dehydrogenase (GDH), which is catalyzed by Sirt4, downregulates the TCA cycle. However, this reaction mechanism is obscure, because the structure of Sirt4 is unknown. We here constructed structural models of Sirt4 by homology modeling and threading, and docked nicotinamide adenine dinucleotide+ (NAD+) to Sirt4. In addition, a partial GDH structure was docked to the Sirt4-NAD+ complex model. In the ternary complex model of Sirt4-NAD+-GDH, the acetylated lysine 171 of GDH is located close to NAD+. This suggests a possible mechanism underlying the ADP-ribosylation at cysteine 172, which may occur through a transient intermediate with ADP-ribosylation at the acetylated lysine 171. These results may be useful in designing drugs for the treatment of cancers and ischemic heart disease

Traveling-wave microwave power divider composed of reflectionless dividing units

We propose a new waveguide type traveling-wave microwave power divider that is adequate for high power applications. The divider is composed of multiple stages of reflectionless dividing units, each having two output ports. Design formulas for reflectionless equal-power dividing are first derived. Structural parameters for wideband design of two- to six-stage dividers are then obtained by means of numerical analyses based on an equivalent circuit. Comparison of experiments at X-band shows good qualitative agreement with the analyses. Typical measured bandwidth for relative divided powers deviation of less than ±0.5 dB was 2.7 GHz, and that for -20 dB return loss was more than 3.2 GHz for the four-stage (eight-way) divider. The divider presented here has excellent features; the bandwidth for equal-power dividing decreases very little and the bandwidth for low return loss increases with increasing number of the dividing stages. It also has advantages of low insertion loss and flexibility over the number of the dividing stage

Effect of site-specific mutagenesis of tyrosine-55, methionine-110 and histidine-217 in porcine kidney D-amino acid oxidase on its catalytic function

AbstractTo assess the contributions of Tyr-55, Met-110 and His-217 in porcine kidney D-amino acid oxidase (EC 1.4.3.3, DAO) to its catalytic function, we constructed three mutant cDNAs coding for the enzymes possessing Phe-55, Leu-110 and Leu-217 by site-specific mutagenesis. The mutant and wild type cDNAs could be expressed in vitro with similar efficiency. The three mutant enzymes thus synthesized showed catalytic activities comparable to that of the wild type oxidase. It is concluded that Tyr-55, Met-110 and His-217 are not directly involved in the catalytic function