A method was investigated to reduce the insertion loss and response time in the phase shift in a microwave variable delay line using liquid crystal (LC). In variable delay lines using conventional ...nematic LC, reducing the insertion loss conflicts with reducing the phase-shift response-time dependence on the thickness of the LC layer; thus, it is very difficult to simultaneously satisfy both requirements. Here, the use of dual-frequency switching-mode liquid crystal (DFSM LC) for the variable delay line is demonstrated as one approach to solving this problem. By using the characteristics of DFSM LC, in that the alignment of the LC can be controlled with a control voltage and its frequency, it becomes possible to control the LC alignment to be in an always electrically driven condition by applying a combination of control voltages of dc and several kilohertz. Experimental results of a microwave variable delay line using DFSM LC show that it is possible to reduce both the phase-shift response time and insertion loss.
A large electronically reconfigurable reflectarray antenna that has 160 × 160 reflecting elements was designed, fabricated, and evaluated so that it could be applied to a millimeter-wave imaging ...system operating in the 60-GHz band. To make it feasible to construct such a large reflectarray, the reflecting element structure had to be simple and easily controlled; therefore, a reflecting element consisting of a microstrip patch and a single-bit digital phase shifter using a p-i-n diode was employed. A large reflectarray antenna was fabricated using the reflecting elements. The measured radiation patterns and antenna gain were in good agreement with those that were calculated. Furthermore, the near-field beam focusing capabilities, which was required to image near-field objects, were also verified through an experiment. Finally, the response time for beamforming was measured, which was far less than the system requirements.
A microwave variable delay line using a membrane impregnated with liquid crystal was newly fabricated. By employing this device configuration, the phase-shift response becomes fast independently of ...the liquid crystal thickness. Experimental results show that the phase-shift response time of 33 ms is obtained, which is two orders of magnitude faster than that of a conventional delay line. The new delay line also exhibits a 270-degree phase-shift and non-dispersive delay characteristics over a wide microwave-frequency range. Moreover, it is clarified that the phase-shift characteristics to a control voltage depend on the pore size of the membrane.
We have developed a Si opt-neural probe with multiple waveguides and metal cover for highly accurate optical stimulation. This neural probe had 16 recording sites, three optical waveguides, and metal ...cover for suppressing light leakage. We evaluated electrochemical properties of the recording sites, and confirmed that the neural probe had suitable characteristics for neural recording. We also demonstrated the optical stimulation to the neurons expressing ChR2 using our probe. As a result, we succeeded multisite optical stimulation, and observed that no light leakage from the optical waveguides because of the metal cover. From in vivo experiments, we successfully recorded optically modulated local field potential using the fabricated Si neural probe with optical waveguides. Moreover, we applied current source density analysis to the recorded LFPs. As a result, we confirmed that light induced membrane current sink in locally stimulated area. Our Si opto-neural probe with multiple optical waveguides and metal-cover is one of the most versatile tools for optogenetics.
A 60-GHz band electrically reconfigurable reflectarray has been investigated. Each reflecting element is printed on a dielectric substrate and has a rectangular microstrip patch and a stub loaded ...with a single p-i-n diode. The reflection phase is changed by 180deg in accordance with the on/off state of the p-i-n diode; namely, the stub works as a single-bit phase shifter. A prototype consisting of 40 times 40 elements spaced at 0.7lambda was fabricated, and the reflection coefficients of the elements and the radiation patterns while the beam steering was performed were measured. Good agreement was observed between the results of the simulations and experiments.
We fabricated and evaluated a prototype imaging system using the Simultaneous Frequency-Encoding technique, which is an active imaging technique that is potentially capable of fast frame-frequency ...imaging using a frequency-scanning antenna with only a single transceiver. The prototype performed simultaneous acquisition of pixels in elevation using Simultaneous Frequency-Encoding and performed a mechanical scan in azimuth. We also studied a ranging technique and incorporated it into the prototype. The ranging technique for Simultaneous Frequency-Encoding must take into account the characteristics of the frequency-scanning antenna, which are fundamental to Simultaneous Frequency-Encoding. We verified that ordinary range processing can be performed before frequency analysis with Simultaneous Frequency-Encoding, giving both range and angular profiles. The prototype was evaluated based on the radiation patterns of a receiver antenna comprising the frequency-scanning antenna and a reflector, on which both the image quality and ranging performance depend. Finally we conducted actual imaging tests and confirmed the capability of through-obstacle imaging. The frame frequency was only 0.1Hz, which was due to the use of a slow mechanical scan in azimuth. However, assuming electronic beam forming is used instead of the mechanical scan, the frame frequency can be improved to several Hertz.
Abstract. Serum dehydroepiandrosterone sulfate (DHEA-S) levels reflect the state of adrenocorticotropic hormone (ACTH) secretion. However, it is difficult to use serum DHEA-S to diagnose ...hypothalamic-pituitary-adrenal (HPA) axis insufficiency due to its non-normal and highly skewed distribution. In this study, we focused on HPA insufficiency caused by hypothalamic and/or pituitary dysfunction and evaluated the usefulness of the standard deviation score of log-transformed DHEA-S (ln DHEA-S SD score), which was calculated from the established age- and sex-specific reference values. We retrospectively reviewed the medical records of 94 patients suspected of having HPA insufficiency, in whom serum DHEA-S measurement and the rapid ACTH stimulation test were performed, and included 65 patients who met our criteria in this study. The ln DHEA-S SD scores were distributed more normally than measured DHEA-S levels and were significantly higher in patients with a peak cortisol level >=18 μg/dL than in those below this value, suggesting that this score is a legitimate and strong indicator of adrenocortical function. The optimal cut-off value for impaired HPA function was -0.853, with a sensitivity of 70.3% and a specificity of 100%. Among the 37 patients whose peak cortisol levels were below 18 μg/dL, 11 patients with ln DHEA-S scores >=-0.853 exhibited significantly higher basal ACTH and basal and peak cortisol levels than the 26 patients with scores <-0.853. Thus, this score plays a supportive role in evaluating HPA axis function, particularly in patients with borderline cortisol responses to ACTH.
We introduce a micro-machined cantilever type probe card with a special tip shape made of single crystal silicon. A novel process for the micro-machined probe card with a sharp tip formation was ...developed and micro probe arrays of 40
μm in pitch were also realized. Probe cantilevers including the sharp tip were formed with anisotropic KOH etching and LOCOS, and thermally deposited with chrome (Cr) and gold (Au). In the final post-process, the tip area of the realized probes was covered with hard material like tungsten (W) using a micro-machined shadow mask. This probe could endure considerable force because both the tip and cantilever were entirely fabricated from single crystal silicon, and the shape of the sharp probe tip was specifically fabricated to break the oxidized surface of the IC chip with ease. This probe is also expected to have a long life-time and sufficient tip hardness since the end of the tip is coated with hard metal.
2-Deoxy-scyllo-inosose (DOI) synthase is the enzyme participating in biosynthesis of 2-deoxystreptamine (DOS)-containing aminoglycoside antibiotics. The gene which encodes the enzyme can be a marker ...for screening of DOS-containing aminoglycoside-producer and exploration of its biosynthetic gene. Further, this enzyme is expected to be of use in industry, because it converts sugar into 6-membered carbocycle. In the present study, we identified 21 clones encoding DOI synthase from environmental DNA by degenerate PCR. They were clearly divided into two groups. One appeared to derive from actinomycetes, and the other from non-actinomycetes. The latter group was larger (17 clones) than the former (four clones) despite the fact that only one strain of non-actinomycete was identified for DOS-containing aminoglycoside production. This result indicates that there are still many unidentified non-actinomycetes for DOS-containing aminoglycoside biosynthesis. We showed the possibility of identification of novel aminoglycoside-producing non-actinomycete from soil, and for development of more efficient enzymes for industrial use.
We have developed a reflection type of signal-to-noise enhancer operating in the 400-MHz band, which can easily be inserted into the second IF stage used in current DBS receivers. The new enhancer ...consists of a microstrip line using a ceramic substrate with a high dielectric constant and a LaGa-YIG film with low saturation magnetization. Enhancement of 8 dB was achieved in the 40-MHz bandwidth. We evaluated the effect of the new enhancer on noise reduction in DBS reception and found that the signal-to-noise enhancer achieved 2 to 3-dB noise reduction.< >
PDF