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ON THE GALERKIN-WAVELET METHOD FOR HIGHER ORDER DIFFERENTIAL EQUATIONS
Fukuda, Naohiro,Kinoshita, Tamotu,Kubo, Takayuki Korean Mathematical Society 2013 대한수학회보 Vol.50 No.3
The Galerkin method has been developed mainly for 2nd order differential equations. To get numerical solutions, there are some choices of Riesz bases for the approximation subspace $V_j{\subset}L^2$. In this paper we shall propose a uniform approach to find suitable Riesz bases for higher order differential equations. Especially for the beam equation (4-th order equation), we also report numerical results.
Mechanisms and Physiological Roles of Mitophagy in Yeast
Fukuda, Tomoyuki,Kanki, Tomotake Korean Society for Molecular and Cellular Biology 2018 Molecules and cells Vol.41 No.1
Mitochondria are responsible for supplying of most of the cell's energy via oxidative phosphorylation. However, mitochondria also can be deleterious for a cell because they are the primary source of reactive oxygen species, which are generated as a byproduct of respiration. Accumulation of mitochondrial and cellular oxidative damage leads to diverse pathologies. Thus, it is important to maintain a population of healthy and functional mitochondria for normal cellular metabolism. Eukaryotes have developed defense mechanisms to cope with aberrant mitochondria. Mitochondria autophagy (known as mitophagy) is thought to be one such process that selectively sequesters dysfunctional or excess mitochondria within double-membrane autophagosomes and carries them into lysosomes/vacuoles for degradation. The power of genetics and conservation of fundamental cellular processes among eukaryotes make yeast an excellent model for understanding the general mechanisms, regulation, and function of mitophagy. In budding yeast, a mitochondrial surface protein, Atg32, serves as a mitochondrial receptor for selective autophagy that interacts with Atg11, an adaptor protein for selective types of autophagy, and Atg8, a ubiquitin-like protein localized to the isolation membrane. Atg32 is regulated transcriptionally and post-translationally to control mitophagy. Moreover, because Atg32 is a mitophagy-specific protein, analysis of its deficient mutant enables investigation of the physiological roles of mitophagy. Here, we review recent progress in the understanding of the molecular mechanisms and functional importance of mitophagy in yeast at multiple levels.
Algebraic Fiber Space Whose Generic Fiber and Base Space Are of Almost General Type
Fukuda, Shigetaka Department of Mathematics 2014 Kyungpook mathematical journal Vol.54 No.2
We assume that the existence and termination conjecture for flips holds. A complex projective manifold is said to be of almost general type if the intersection number of the canonical divisor with every very general curve is strictly positive. Let f be an algebraic fiber space from X to Y. Then the manifold X is of almost general type if every very general fiber F and the base space Y of f are of almost general type.
ON THE PROJECTIVE FOURFOLDS WITH ALMOST NUMERICALLY POSITIVE CANONICAL DIVISORS
Fukuda, Shigetaka Korean Mathematical Society 2006 대한수학회보 Vol.43 No.4
Let X be a four-dimensional projective variety defined over the field of complex numbers with only terminal singularities. We prove that if the intersection number of the canonical divisor K with every very general curve is positive (K is almost numerically positive) then every very general proper subvariety of X is of general type in ';he viewpoint of geometric Kodaira dimension. We note that the converse does not hold for simple abelian varieties.
Fukuda, Masakazu,Takahashi, Shuji,Haramoto, Yoshikazu,Onuma, Yasuko,Kim, Yeon-Jin,Yeo, Chang-Yeol,Ishiura, Shoichi,Asashima, Makoto UPV/EHU Press 2010 The International journal of developmental biology Vol.54 No.1
<P>The T-box gene VegT plays a crucial role during mesendoderm specification of the amphibian embryo. While the function of maternal VegT (mVegT) has been extensively investigated, little is known about the function and transcriptional regulation of zygotic VegT (zVegT). In the present study, we used comparative genomics and a knockdown experiment to demonstrate that zVegT is the orthologous gene of zebrafish Spadetail/Tbx16 and chick Tbx6L/Tbx6, and has an essential role in paraxial mesodermal formation. zVegT knockdown embryos show several defects in the patterning of trunk mesoderm, such as abnormal segmentation of somites, a reduction in muscle, and the formation of an abnormal mass of cells at the tail tip. We also identified the cis-regulatory elements of zVegT that are necessary and sufficient for mesoderm-specific expression. These cis-regulatory elements are located in two separate upstream regions of zVegT, corresponding to the first intron of mVegT. The results of in vitro binding and functional assays indicate that Forkhead box H1 (FoxH1) and Eomesodermin (Eomes) are the trans-acting factors required for zVegT expression. Our results highlight the essential role of zVegT in organization of paraxial mesoderm, and reveal that zVegT is regulated by a coherent feedforward loop of Nodal signaling via Eomes.</P>
Fukuda, Takehito,Kosaka, Tatsuro,Osaka, Katsuhiko The Korean Society for Composite Materials 2001 Composites research Vol.14 No.6
This paper describes applications of cure monitoring techniques by using embedded fiber optic strain sensors, which are extrinsic Fabry-Perot interoferometric (EFPI) and/or fiber Bra99 grating (FBG) sensors, to three kinds of molding methods of autoclave, FW and RTM molding methods. In these applications, internal strain of high-temperature curing resin was monitored by EFPI sensors. From theme experimental results, it was shown that strain caused by thermal shrink at cooling stage could be measured well. In addition, several specific matters to these molding methods were considered. As thor an autoclave molding of unidirectional FRP laminates, it was confirmed that off-axis strain of unidirectional FRP could be monitored by EFPI sensors. As for FW molding using room-temperature (RT) cured resin, it was found that the strain outputs from EFPI sensors represented curing shrinkage as well as thermal strain and the convergence meant finish of cure reaction. It was also shown that this curing shrinkage should be evaluated with consideration on logarithmic change in stiffness of matrix resin. As for a RTM melding, both EFPI and FBC sensors were employed to measure strain. The results showed that FBG sensors hale also good potential for strain monitoring at cooling stage, while the non-uniform thermal residual strain of textile affected the FBG spectrum after molding. This study has proven that embedded fiber optic strain sensors hale practical ability of cure monitoring of FRP. However, development of automatic installation methods of sensors remains as a problem to be solved for applications to practical products.
Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography
Fukuda, Yohta,Tse, Ka Man,Nakane, Takanori,Nakatsu, Toru,Suzuki, Mamoru,Sugahara, Michihiro,Inoue, Shigeyuki,Masuda, Tetsuya,Yumoto, Fumiaki,Matsugaki, Naohiro,Nango, Eriko,Tono, Kensuke,Joti, Yasumas National Academy of Sciences 2016 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.113 No.11
<P>Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme-substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-angstrom resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-angstrom resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes.</P>