Satellite Constellation Pattern Optimization for Complex Regional Coverage

The use of regional coverage satellite constellations is on the rise, urging the need for an optimal constellation design method for complex regional coverage. Traditional constellations are often designed for continuous global coverage, and the few existing regional constellation design methods lead to suboptimal solutions for periodically time-varying or spatially-varying regional coverage requirements. This paper introduces a new general approach to design an optimal constellation pattern that satisfies such complex regional coverage requirements. To this end, the circular convolution nature of the repeating ground track orbit and common ground track constellation is formalized. This formulation enables a scalable constellation pattern analysis for multiple target areas and with multiple sub-constellations. The formalized circular convolution relationship is first used to derive a baseline constellation pattern design method with the conventional assumption of symmetry. Next, a novel method based on binary integer linear programming is developed, which aims to optimally design a constellation pattern with the minimum number of satellites. This binary integer linear programming method is shown to achieve optimal constellation patterns for general problem settings that the baseline method cannot achieve. Five illustrative examples are analyzed to demonstrate the value of the proposed new approach.Comment: 47 pages, 23 figures, Journal of Spacecraft and Rockets (Published

Structure Effect on Antioxidant Activity of Catecholamines toward Singlet Oxygen and Other Reactive Oxygen Species in vitro

The reactivity of catecholamine neurotransmitters and the related metabolites were precisely investigated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and reactive oxygen species. Catecholamines reacted immediately with DPPH radicals, their reactivity being stronger than that of ascorbic acid as a reference. Superoxide scavenging activities of catecholamines determined by WST-1 and electron spin resonance (ESR) spin trapping methods were also high. Whereas tyrosine, the dopamine precursor showed no reactivity toward superoxide. The reactivity toward singlet oxygen was evaluated by observing specific photon emission from singlet oxygen. The results revealed that reactivity of catecholamines was markedly higher than that of sodium azide, and catechin as catechol reference. The reaction of catecholamines and singlet oxygen was further studied by ESR using 55-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping reagent and rose bengal as photosensitizer. DMPO-OH signal of epinephrine was significantly small compared to other catecholamines, catechin, and 4-methylcatechol as a reference compound and was as small as that of tyrosine. The signal formation was totally dependent on singlet oxygen, and the presence of catechol compounds. These results indicated that epinephrine is the most potent singlet oxygen quencher than other catecholamines, and the secondary amino group in its alkyl side chain could play a role in unique singlet oxygen quenching property of epinephrine

Primary Thymic Mucosa-Associated Lymphoid Tissue Lymphoma: Diagnostic Tips

AbstractMucosa-associated lymphoid tissue (MALT) lymphoma arising in the thymus is extremely rare and little is known regarding its clinicopathological features. This study examined the clinicopathological features of nine cases of thymic MALT lymphoma. Most patients had autoimmune disease or hyperglobulinemia, and they also had cysts in the tumors. Both increased serum autoantibody levels and polyclonal serum immunoglobulin levels remained essentially unchanged after total thymectomy in all patients. Thymic MALT lymphoma needs to be included in the differential diagnosis in Asian patients with a cystic thymic mass accompanied by autoimmune disease or hyperglobulinemia

Five-antituberculosis Drug-resistance Genes Detection Using Array System

Detection of resistance to drugs for Mycobacterium tuberculosis takes about two months from the sample collection using culture-based methods. To test a rapid method for detection of resistance for five antituberculosis drugs using DNA microarray and to examine its potential for clinical use, we employed a DNA microarray for detection of seven mutations genes related to resistance of five kinds of antituberculous drugs using Mycobacterium tuberculosis DNA isolated from sputum. The results of microarray analysis were compared with the results of a standard culture method of Lowenstein-jensen drug sensitivity testing system. DNA microarray analysis showed a high sensitivity (>90%) for all five drugs. Specificity of rifampicin and ethambutol were nearly 90%, however specificity of isoniazid (60%) and kanamycin (67%) were not enough. The amount of Mycobacterium tuberculosis DNA required for microarray analysis corresponded to at least 1–9 Acid-Fast Bacilli per 10 fields by carbolfuchsin staining. DNA microarray analysis appears to be useful for estimation of drug resistances, nevertheless its limitations. To minimize misunderstanding, it is necessary to confirm the number of bacilli in the sputum, and culture method is needed for comparison when use the PCR-based array system

Evaluation of CNT toxicity by comparison to tattoo ink

ArticleMaterials Today. 14(9): 434-440 (2011)journal articl

Biocompatibility and bone tissue compatibility of alumina ceramics reinforced with carbon nanotubes

信州大学博士（医学）・学位論文・平成23年3月31日授与（甲第906号)・荻原伸英The addition of carbon nanotubes (CNTs) remarkably improves the mechanical characteristics of base materials. CNT/alumina ceramic composites are expected to be highly functional biomaterials useful in a variety of medical fields. Biocompatibility and bone tissue compatibility were studied for the application of CNT/alumina composites as biomaterials. Methods & results: Inflammation reactions in response to the composite were as mild as those of alumina ceramic alone in a subcutaneous implantation study. In bone implantation testing, the composite showed good bone tissue compatibility and connected directly to new bone. An in vitro cell attachment test was performed for osteoblasts, chondrocytes, fibroblasts and smooth muscle cells, and CNT/alumina composite showed cell attachment similar to that of alumina ceramic. Discussion & conclusion: Owing to proven good biocompatibility and bone tissue compatibility, the application of CNT/alumina composites as biomaterials that contact bone, such as prostheses in arthroplasty and devices for bone repair, are expected.ArticleNANOMEDICINE. 7(7):981-993 (2012)journal articl

Role of PERK in mitochondrial function

Mitochondria play a central role in the function of brown adipocytes (BAs). Although mitochondrial biogenesis, which is indispensable for thermogenesis, is regulated by coordination between nuclear DNA transcription and mitochondrial DNA transcription, the molecular mechanisms of mitochondrial development during BA differentiation are largely unknown. Here, we show the importance of the ER-resident sensor PKR-like ER kinase (PERK) in the mitochondrial thermogenesis of brown adipose tissue. During BA differentiation, PERK is physiologically phosphorylated independently of the ER stress. This PERK phosphorylation induces transcriptional activation by GA-binding protein transcription factor α subunit (GABPα), which is required for mitochondrial inner membrane protein biogenesis, and this novel role of PERK is involved in maintaining the body temperatures of mice during cold exposure. Our findings demonstrate that mitochondrial development regulated by the PERK–GABPα axis is indispensable for thermogenesis in brown adipose tissue