Millimeter-Wave Beam Multiplexing Method Using Subarray Type Hybrid Beamforming of Interleaved Configuration with Inter-subarray Coding

A millimeter-wave beam multiplexing method using a subarray type interleaved configuration hybrid beamforming with inter-subarray coding is proposed. By multiplexing of adequate directional beams, the proposed method can reduce inter-beam interference and create multiple beams of a theoretical maximum gain that an array antenna can generate. As results of performance comparison in subarray type beamforming with the feasibility, it is shown that channel capacity of the interleaved configuration with inter-subarray coding is larger than that of the localized configuration. Particularly, in user dense environments, the interleaved configuration is effective. Therefore, we think that the interleaved configuration is suitable for millimeter-wave beam multiplexing.     

Channel Models for Medical Implant Communication

Information regarding the propagation media is typically gathered by conducting physical experiments, measuring and processing the corresponding data to obtain channel characteristics. When this propagation media is human body, for example in case of medical implants, then this approach might not be practical. In this paper, an immersive visualization environment is presented, which is used as a scientific instrument that gives us the ability to observe RF propagation from medical implants inside a human body. This virtual environment allows for more natural interaction between experts with different backgrounds, such as engineering and medical sciences. Here, we show how this platform has been used to determine channel models for medical implant communication systems.     

Symbol rate and modulation level-controlled adaptivemodulation/TDMA/TDD system for high-bit-rate wireless data transmission

This paper proposes a time-division multiple-access/time-division duplex (TDMA/TDD)-based symbol rate and modulation level-controlled adaptive modulation system for high-bit-rate data transmission. The proposed system controls both the symbol rate and modulation level for the next transmission time slot according to the estimated carrier power to noise spectral density ratio (C/N₀) and delay spread for the time slot to achieve higher bit rate and higher transmission quality as well as higher delay-spread immunity. It is demonstrated by computer simulation and laboratory experiments that the proposed system can achieve a higher average bit rate with higher transmission quality in comparison with the fixed-rate quaternary phase-shift keying (QPSK) system and modulation level-controlled adaptive modulation system in both flat Rayleigh and frequency-selective fading environments. The simulated and experimental results also show that the proposed adaptive modulation techniques can be applied to 1-2-Mb/s indoor and outdoor microcellular systems with its delay spread of up to 250 ns and its terminal mobility of up to pedestrian speed without employing any special antifrequency-selective fading techniques, such as the adaptive equalizer and space diversity     

Durable Ultraflexible Organic Photovoltaics with Novel Metal‐Oxide‐Free Cathode

Flexible and stretchable organic photovoltaics (OPVs) are promising as a power source for wearable devices with multifunctions ranging from sensing to locomotion. Achieving mechanical robustness and high power conversion efficiency for ultraflexible OPVs is essential for their successful application. However, it is challenging to simultaneously achieve these features by the difficulty to maintain stable performance under a microscale bending radius. Ultraflexible OPVs are proposed by employing a novel metal‐oxide‐free cathode that consists of a printed ultrathin metallic transparent electrode and an organic electron transport layer to achieve high electron‐collecting capabilities and mechanical robustness. In fact, the proposed ultraflexible OPV achieves a power conversion efficiency of 9.7% and durability with 74% efficiency retention after 500 cycles of deformation at 37% compression through buckling. The proposed approach can be applied to active layers with different morphologies, thus suggesting its universality and potential for high‐performance ultraflexible OPV devices.     

Development of an active targeting liposome encapsulated with high-density colloidal gold for transmission electron microscopy

Active targeting of the liposome is an attractive strategy for drug delivery and in vivo bio-imaging. We previously reported the specific accumulation of Sialyl Lewis X (SLX) liposome to inflamed tissue in arthritic model mice or tumor-bearing mice. SLX-liposome encapsulation with fluorescent substances allows for the visualization of these liposomes by the time-dependent transvascular accumulation of fluorescent signals in the histological sections. In the present study, we developed a new SLX-liposome encapsulated with colloidal gold for transmission electron microscopic observation. We herein describe the characterization of the colloidal gold-loaded SLX-liposomes and demonstrate its specific targeting to the endothelial cells of tumor blood vessels in tumor-bearing mice.     

Efficient Excitation of Hybrid Modes in a THz Clinotron

Journal of Infrared, Millimeter, and Terahertz Waves - Various regimes of hybrid, bulk-surface, modes being excited in the clinotron oscillator with a sheet electron beam and nonuniform grating...     

Detection and Quantitation of Left-to-Right Shunts from Radionuclide Angiocardiography Using the Homomorphic Deconvolution Technique

The homomorphic filtering method is described for the detection and quantitation of left-to-right shunts from radionuclide angiocardiography. First, the method is investigated theoreticatly and numerically using a realistic model with systemic recirculation. It is demonstrated that even in a noisy situation the shunt flow fraction can be relatively well estimated, if only the characteristics of the fiters used are suitable. Second, the method is applied to real data, i.e., the pulmonary time-activity curves from radionucUde anglocardiography. The presence or absence of a left-to-right shunt is determined using the ratio AT/MTT. The pulmonary-to-systemic flow ratios calculated from the areas of the two decomposed curves are compared with those from oximetry at cardiac catheterization. Good agreement between the Qp/Qs ratios calculated by oximetry and radionucUide angiocardiography is obtained.     

A Quantitative Approach for Correction of Background Counts: Determination of Left Ventricular Ejection Fraction by Radionuclide Angiocardiography

A quantitative approach for correction of background counts is described for determination of the left ventricular ejection fraction from first-pass radionuclide angiocardiography. First, the method is investigated theoretically and numerically using a mathematical model. It is demonstrated that the ejection fraction can be estimated relatively well, even in a noisy situation. Second, the method is applied to the left ventricular time-activity curves from two different regions of interest, the carefully selected and the laxly selected, and these are compared to each other. Good agreement (correlation coefficient = 0.96) for 20 patients was obtained between the ejection fractions from the carefully selected region of interest and those from the laxly selected one.     

Ceramic Dental Molds for the Precision Casting of Titanium and Titanium Alloys: I, Relationship between Particle-Size Distribution of Aggregates and Mold Expansion

A new ceramic dental mold can cast excellent Ti restoratives by controlling expansion due to the oxidation of additive metal particles. The packing structure of the metal and aggregate particles in the mold can be considered a function of the size distribution of the aggregate grains. An investigation of the expansion mechanism reveals three different relationships of void fraction versus linear thermal expansion for the molds at the high temperature under which oxidation of the metal particles occurs. Room-temperature casting, favorable for making high-quality Ti restoratives, can also be achieved by precisely controlling both the amount of additive metal powder and the compositional distribution of aggregate grain sizes in the mold.