University of Tsukuba

About: University of Tsukuba is a education organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Population & Gene. The organization has 36352 authors who have published 79483 publications receiving 1934752 citations. The organization is also known as: Tsukuba daigaku & Tsukuba University.

Volcanism in Response to Plate Flexure

Abstract: Volcanism on Earth is known to occur in three tectonic settings: divergent plate boundaries (such as mid-ocean ridges), convergent plate boundaries (such as island arcs), and hot spots. We report volcanism on the 135 million-year-old Pacific Plate not belonging to any of these categories. Small alkalic volcanoes form from small percent melts and originate in the asthenosphere, as implied by their trace element geochemistry and noble gas isotopic compositions. We propose that these small volcanoes erupt along lithospheric fractures in response to plate flexure during subduction. Minor extents of asthenospheric melting and the volcanoes' tectonic alignment and age progression in the direction opposite to that of plate motion provide evidence for the presence of a small percent melt in the asthenosphere.

Analysis of land use/cover changes and urban expansion of Nairobi city using remote sensing and GIS

Abstract: We used three Landsat images together with socio‐economic data in a post‐classification analysis to map the spatial dynamics of land use/cover changes and identify the urbanization process in Nairobi city. Land use/cover statistics, extracted from Landsat Multi‐spectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper plus (ETM+) images for 1976, 1988 and 2000 respectively, revealed that the built‐up area has expanded by about 47 km2. The road network has influenced the spatial patterns and structure of urban development, so that the expansion of the built‐up areas has assumed an accretive as well as linear growth along the major roads. The urban expansion has been accompanied by loss of forests and urban sprawl. Integration of demographic and socio‐economic data with land use/cover change revealed that economic growth and proximity to transportation routes have been the major factors promoting urban expansion. Topography, geology and soils were also analysed as possible factors influencin...

Slower decline of glomerular filtration rate in the Japanese general population: a longitudinal 10-year follow-up study.

Abstract: The prevalence of stage 3 to 5 chronic kidney disease (CKD) in Japan (18.7%) is considerably higher than that in the United States (4.5%). This study investigated in the Japanese general population whether this higher prevalence of CKD might reflect to a progressive decline of renal function, and in turn to the increased risk of end-stage renal disease. A decline in renal function over 10 years was examined in 120,727 individuals aged 40 years or older who participated in the annual health examination program of the two periods over 10 years, 1988-1993 and 1998-2003. Renal function was assessed with estimated glomerular filtration rate (GFR) using the abbreviated Modification of Diet in Renal Disease (MDRD) Study equation modified by a Japanese coefficient. The rate of GFR decline in the participants was 0.36 mL/min/1.73 m2/year on average. In the male population aged 50-79, the mean rate of GFR decline was significantly higher in the presence of hypertension than in its absence. The rate of GFR decline was more than two times higher in participants with proteinuria than in those without proteinuria in both sexes. The rate was significantly higher in participants with an initial GFR<50 mL/min/1.73 m2 among the groups younger than age 70 and in participants with an initial GFR<40 mL/min/1.73 m2 in the group with age 70-79. Based on the slow rate of GFR decline, we concluded that the decline in renal function progresses slowly in the Japanese general population. Hypertension, proteinuria and lower GFR were found to be significant risk factors for a faster decline of GFR.

Complete genomic structure of the bloom-forming toxic cyanobacterium Microcystis aeruginosa NIES-843.

Abstract: The nucleotide sequence of the complete genome of a cyanobacterium, Microcystis aeruginosa NIES-843, was determined. The genome of M. aeruginosa is a single, circular chromosome of 5 842 795 base pairs (bp) in length, with an average GC content of 42.3%. The chromosome comprises 6312 putative protein-encoding genes, two sets of rRNA genes, 42 tRNA genes representing 41 tRNA species, and genes for tmRNA, the B subunit of RNase P, SRP RNA, and 6Sa RNA. Forty-five percent of the putative protein-encoding sequences showed sequence similarity to genes of known function, 32% were similar to hypothetical genes, and the remaining 23% had no apparent similarity to reported genes. A total of 688 kb of the genome, equivalent to 11.8% of the entire genome, were composed of both insertion sequences and miniature inverted-repeat transposable elements. This is indicative of a plasticity of the M. aeruginosa genome, through a mechanism that involves homologous recombination mediated by repetitive DNA elements. In addition to known gene clusters related to the synthesis of microcystin and cyanopeptolin, novel gene clusters that may be involved in the synthesis and modification of toxic small polypeptides were identified. Compared with other cyanobacteria, a relatively small number of genes for two component systems and a large number of genes for restrictionmodification systems were notable characteristics of the M. aeruginosa genome.

Shape memory materials and hybrid composites for smart systems. Part II shape-memory hybrid composites

Abstract: By hybridizing or incorporating shape-memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of shape-memory hybrid composites have been designed and manufactured, with shape-memory elements being either the matrix or the reinforcement. The hybrid composites provide tremendous potential for creating new paradigms for material–structural interactions and demonstrate varying success in many engineering applications. This review, from the standpoint of materials science, will give a state-of-the-art survey on the various shape-memory hybrid smart composites developed during the last decade. Emphasis is placed on the design, fabrication, characterization and performance of fibre-reinforced, particle-reinforced and multi-layered thin-film shape-memory composites.