Capacity design and performance of call admission control incellular CDMA systems

Since code-division multiple-access (CDMA) capacity is interference limited, call admission control (CAC) must guarantee both a grade of service (GoS), i.e., the blocking rate, and a quality of service (QoS), i.e., the loss probability of communication quality. This paper describes the development of a new capacity design method based on these two concepts. Theoretical expressions for GoS and QoS as functions of traffic intensity and CAC thresholds are first derived from the traffic theory viewpoint, and then a design method using these expressions is presented. At that time, two strategies for CAC are assumed. One is based on the number of users, and the other is based on the interference level. Computer simulation results are presented that strongly support the proposed design method. Furthermore, numerical examples and a performance comparison of the two strategies considering various propagation parameters, nonuniform traffic distributions, and various transmission rates are shown     

Multiple penetrating colonic ulcers in secondary amyloidosis caused by rheumatoid arthritis

An autopsy case of multiple penetrated colonic ulcers with secondary amyloidosis caused by rheumatoid arthritis in a 61 year old woman is reported. Amyloid deposition was conspicuous in the transverse colon with numerous penetrating ulcers that were circumferentially scattered. Deposition was mainly in the small vessel walls of the submucosal layers. In the quantitative comparison of the histological components between the colonic segments affected by severe and mild ulcer formation, occlusive vascular amyloid deposition was revealed more frequently in the severe involved portion than in the mild involved portion. In addition, submucosal fibrosis that tended to appear around ulcers was more extensive and thicker in the former than in the latter. The complete vascular occlusion caused by amyloid deposition was particularly concentrated in the submucosal layer adjacent to the ulcer. These findings indicate that peripheral circulatory disturbance by amyloid deposition in the small vascular walls leads to ulcer formation in the colon.     

Fundamental study on the NOx direct decomposition catalysts

We are developing direct decomposition catalysts to decompose the NO_x involved in high temperature exhaust gases to N₂ and O₂ without any reductants such as urea and plan to bring this technology into practice in the 21st century. We expect to create very simple deNO_x systems using direct decomposition catalysts applicable to a wide range of fields (co-generation, boilers, automobiles and so on) after overcoming the technical difficulties. Perovskite catalyst and zeolite catalyst are the most promising materials for direct decomposition catalysts. This study focuses on seeking and designing novel NO_x direct decomposition catalysts having high activities through theoretical studies using computational chemistry and experimental studies using surface-science techniques.     

Gas dwell time control for rapid and long lifetime growth of single-walled carbon nanotube forests

The heat history (i.e., "dwell time") of the carbon source gas was demonstrated as a vital parameter for very rapid single-walled carbon nanotube (SWNT) forest growth with long lifetime. When the dwell time was raised to 7 s from the 4 s used for standard growth, the growth rate increased to 620 μm/min: a benchmark for SWNT forest growth on substrates. Importantly, the increase in growth rate was achieved without decreasing either the growth lifetime or the quality of the SWNTs. We interpret that the conversion rate of the carbon feedstock into CNTs was selectively increased (versus catalyst deactivation) by delivering a thermally decomposed carbon source with the optimum thermal history to the catalyst site.     

Acoustic Resonance of Superfluid 3He in Parallel Plates

We performed an acoustic resonance experiment of superfluid ³He confined in a stack of parallel plates, and found the fourth sound resonance. From its velocity, the superfluid density fraction was calculated. No size effect was found because the gap between parallel plates were much larger than the superfluid coherence length. The energy loss of the resonance was also measured. We found that the hydrodynamic theory qualitatively described its temperature dependence, but it could not describe the gap width dependence. Possible explanations is discussed in the text. More over, we found the unidentified resonance that cannot be explained by conventional sound modes.     

Thin-film field-effect transistors of copper phthalocyanine on a rubbed polyethersulfone

We fabricated copper phthalocyanine (CuPc) thin-film field-effect transistors (FETs) on a rubbed flexible polyethersulfone (PES) substrate. Rubbing the PES film induced a unidirectional orientation of CuPc crystallites, which were oriented perpendicular to the rubbing direction. Favorable conditions for fabricating a CuPc FET were determined after fabricating CuPc FETs of two different types and evaluating their output performance. Well-aligned CuPc crystallites along the direction connecting source and drain electrodes can play an important role in improving the output performance of the fabricated FETs.     

Effect of radon measurement methods on dose estimation

Different radon measurement methods were applied in the old and new buildings of the Turkish bath of Eger, Hungary, in order to elaborate a radon measurement protocol. Besides, measurements were also made concerning the radon and thoron short-lived decay products, gamma dose from external sources and water radon. The most accurate results for dose estimation were provided by the application of personal radon meters. Estimated annual effective doses from radon and its short-lived decay products in the old and new buildings, using 0.2 and 0.1 measured equilibrium factors, were 0.83 and 0.17 mSv, respectively. The effective dose from thoron short-lived decay products was only 5 % of these values. The respective external gamma radiation effective doses were 0.19 and 0.12 mSv y(-1). Effective dose from the consumption of tap water containing radon was 0.05 mSv y(-1), while in the case of spring water, it was 0.14 mSv y(-1).