Study of LEO-SAT microwave link for broad-band mobile satellite communication system

In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented

Malignant Potential in the Analysis of DNA Ploidy Pattern in Patients with Colorectal Cancer

Recently the measurement of cellular DNA content has been focused on knowing the extent of cancer extension and biological behaviour of the tumor cells as well as on producting occurrence of recurrence and the survival time in patients with carcinomas of various organs. And also it is well known that tumor markers such as CEA, CA19-9 and CA72-2 are of great value in predicting recurrence in the follow-up study. It is common that colorectal cancers show well differentiated carcinoma which demonstrates relatively fair prognosis. However, some revealed aggressive and rapid extension of carcinoma, indicating a poor prognosis. The purpose of this study is to certify the significance of the measurement of cellular DNA content for assessing biologic behavior of colorectal cancer in comparison with clinicopathologic factors which have been used for assessment of their prognosis. Development of flow cytometer enabled us to measure the nuclear DNA content with ease, speed and producibility. Furthermore, prevalence of flow cytometric technique makes it possible to know more accurate outcome. When assessed biologically aggressive behavior of tumor cells, potent chemotherapy and extensive surgery are mandatory for improvement of the outcome. It is necessary to search for the method of the accurate assessment of the outcome for patients with carcinomas. The purpose of this study is to clarify the validity of nuclear DNA measurement for assessment of the prognosis in patients with colorectal cancer in comparison with clinicopathologic factors

Surgery for Gastric Cancer in Younger Patients

Twenty-five patients with gastric cancer were clinically evaluated in terms of a clinicopathological pattern in younger patients. 1) Female was more predominant than male. 2) The main tumor location was the cardia and the gross appearance was Borrmann IV of undifferentiated carcinoma in the majority. 3) Less hepatic metastases were seen in younger patients, whereas, the common extension in younger patients was peritoneal dissemination and serosal invasion. 4) The surgical outcome was satisfactory as far as a curative operation be performed. On the contrary, the result of non-curative operation was extremely pessimistic. Recently great strides in the surgical outcome of gastric cancer have been achieved in combination with adjuvant therapy of immunochemotherapy. Improvement of surgical outcome is attributable to the standarized operative procedure with reasonable node dissection. It is common that carcinomas in various organs affect older patients, not usually younger ones. The purpose of this study is to clarify the clinicopathologic features of gastric cancer in younger patients on the basis of our result of clinical experience