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Search Results: 1 - 10 of 426 matches for " Yui Kawashima "
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Theoretical Emission Spectra of Atmospheres of Hot Rocky Super-Earths
Yuichi Ito,Masahiro Ikoma,Hajime Kawahara,Hiroko Nagahara,Yui Kawashima,Taishi Nakamoto
Physics , 2015, DOI: 10.1088/0004-637X/801/2/144
Abstract: Motivated by recent detection of transiting high-density super-Earths, we explore the detectability of hot rocky super-Earths orbiting very close to their host stars. In the environment hot enough for their rocky surfaces to be molten, they would have the atmosphere composed of gas species from the magma oceans. In this study, we investigate the radiative properties of the atmosphere that is in the gas/melt equilibrium with the underlying magma ocean. Our equilibrium calculations yield Na, K, Fe, Si, SiO, O, and O$_2$ as the major atmospheric species. We compile the radiative-absorption line data of those species available in literature, and calculate their absorption opacities in the wavelength region of 0.1--100~$\mathrm{\mu m}$. Using them, we integrate the thermal structure of the atmosphere. Then, we find that thermal inversion occurs in the atmosphere because of the UV absorption by SiO. In addition, we calculate the ratio of the planetary to stellar emission fluxes during secondary eclipse, and find prominent emission features induced by SiO at 4~$\mathrm{\mu m}$ detectable by Spitzer, and those at 10 and 100~$\mathrm{\mu m}$ detectable by near-future space telescopes.
Demonstrating High-precision, Multi-band Transit Photometry with MuSCAT: A Case for HAT-P-14b
Akihiko Fukui,Norio Narita,Yui Kawashima,Nobuhiko Kusakabe,Masahiro Onitsuka,Tsuguru Ryu,Masahiro Ikoma,Kenshi Yanagisawa,Hideyuki Izumiura
Physics , 2015,
Abstract: The Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT) is an optical three-band (g'_2-, r'_2-, and z_{s,2}-band) imager, recently developed for the 188cm telescope at Okayama Astrophysical Observatory with the aim of validating and characterizing transiting planets. In a pilot observation with MuSCAT, we observed a primary transit of HAT-P-14b, a high-surface gravity (g_p=38 ms^{-2}) hot Jupiter around a bright (V=10) F-type star. From a 2.9-hour observation, we achieve the 5-min binned photometric precisions of 0.028%, 0.022%, and 0.024% in the g'_2, r'_2, and z_{s,2} bands, respectively, providing the highest-quality photometric data for this planet. Combining these results with those of previous observations, we search for variations of transit timing and duration over five years, as well as variations of planet-star radius ratio (R_p/R_s) with wavelength, but find no considerable variation in any parameters. On the other hand, using the transit-subtracted light curves, we simulate achievable measurement error of R_p/R_s with MuSCAT for various planetary sizes, assuming three types of host stars, namely, HAT-P-14, the nearby K dwarf HAT-P-11, and the nearby M dwarf GJ1214. Comparing our results with the expected atmospheric scale heights of planets with the lowest surface gravity, we find that MuSCAT is capable of probing the atmospheres of planets as small as a sub-Jupiter (R_p ~6 R_Earth) around HAT-P-14 in all bands, a Neptune (~4R_Earth) around HAT-P-11 in all bands, and a super-Earth (~2.5R_Earth) around GJ1214 in r'_2 and z_{s,2} bands. These results promise that MuSCAT will produce fruitful scientific outcomes in the K2 and TESS era.
Donepezil rescues the medial septum cholinergic neurons via nicotinic ACh receptor stimulation in olfactory bulbectomized mice  [PDF]
Yui Yamamoto, Kohji Fukunaga
Advances in Alzheimer's Disease (AAD) , 2013, DOI: 10.4236/aad.2013.24021
Abstract: Olfactory bulbectomy (OBX) causes cognitive dysfunction by degeneration of cholinergic neurons in the medial septum. Here, we define an involvement of nicotinic acetylcholine receptor (nAChR) in neuroprotective effect of donepezil in the septum neurons of OBX mice. Neuroprotective effects on the medial septal cholinergic neurons were assessed after chronic donepezil administration in OBX mice. We also measured Akt and ERK phosphorylation to define the neuroprotective mechanism of donepezil. We found that treatment with donepezil (1 - 3 mg/kg) for 15 consecutive days completely rescued cholinergic neurons in the OBX mice with concomitant improved memory. Reduction of both protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) phosphorylation were restored by chronic donepezil administration (1 - 3 mg/kg) in OBX mouse medial septum. Both phosphorylated Akt and ERK immunoreactivities were localized in cell bodies of choline acetyltransferase (ChAT)-positive cholinergic cells in the medial septum. Enhancement of Akt and ERK phosphorylation seen following donepezil administration was totally blocked by pre-administration of mecamylamine (10 μM), a nicotinic acetylcholine receptor antagonist. Donepezil increases phosphorylation of Akt and ERK via nAChR stimulation in the medial septum cholinergic neurons. The Akt and ERK stimulation by donepezil is associated with its ability of neuroprotection in the medial septum and memory improvement.
The S100A8/A9 heterodimer amplifies proinflammatory cytokine production by macrophages via activation of nuclear factor kappa B and p38 mitogen-activated protein kinase in rheumatoid arthritis
Katsue Sunahori, Masahiro Yamamura, Jiro Yamana, Kouji Takasugi, Masanori Kawashima, Hiroshi Yamamoto, Walter J Chazin, Yuichi Nakatani, Satoru Yui, Hirofumi Makino
Arthritis Research & Therapy , 2006, DOI: 10.1186/ar1939
Abstract: S100A8 and S100A9 are two members of the S100 protein family that are characterized by the presence of two Ca2+-binding sites of the EF-hand type. These proteins are also designated as migration inhibitory factor- or myeloid-related protein-8 (MRP8) and MRP14, or calgranulin A and B, respectively [1-3]. Most members of the S100 family exist in the form of homodimers or heterodimers within cells and interact with several effector proteins mostly in a Ca2+-dependent manner, thereby regulating enzyme activities, the dynamics of cytoskeleton constituents, cell growth and differentiation, and Ca2+ homeostasis [1]. S100A8 and S100A9 are predominantly expressed in cells of the myelomonocytic lineage; both proteins are present at high concentrations in the cytoplasm of neutrophils and monocytes, and the S100A8/A9 heterodimer is translocated to membrane and cytoskeletal structures upon activation [4-6]. Intracellular S100A8/A9 complexes play an important role in myeloid cell maturation, cell trafficking, and arachidonic acid (AA) metabolism [2].S100A8 and S100A9 are secreted as complexes from neutrophils and monocytes after activation of protein kinase C in a novel pathway requiring an intact microtubule network [7]. High levels of the proteins have been found in the extracellular milieu during inflammatory conditions such as rheumatoid arthritis (RA) [2,3]. The S100A8/A9 heterodimer, originally identified as an antimicrobial protein, exhibits cytokine-like functions in the local environment, most notably enhancing leukocyte recruitment to inflammatory sites and AA transportation to its target cells [8-10]. However, the nature of surface receptors for S100A8/A9 and its signaling pathways has not yet been fully elucidated. The soluble S100A8/A9 complex binds to the cell surface of endothelial cells by interacting with specific binding sites such as heparin sulfate proteoglycans and novel carboxylated glycans [11,12]. In addition, CD36 and the receptor for advanced glycation e
Use of Lexical Stress during Oral Reading among Japanese EFL Learners  [PDF]
Lisa Yoshikawa, Chi Yui Leung
Open Journal of Modern Linguistics (OJML) , 2014, DOI: 10.4236/ojml.2014.45050
Abstract: The purpose of the present study is to examine second language (L2) oral reading with a focus on lexical stress. We conducted oral reading tasks to investigate whether 14 Japanese learners of English as a foreign language (EFL) read words aloud with different lexical stress (one- or two- stress words) with appropriate stress assignment, similar to a comparison group of 14 native English speakers, in order to see whether EFL learners, who have fewer verbal input and output opportunities, assign the proper stress(es) in oral reading contexts. The participants read 18 pairs of four-syllable one- and two-stress words both in isolation and in sentence context conditions, and the whole word duration, syllable duration, and syllable intensity were analyzed. The results showed that both groups of readers (1) read two-stress words longer than one-stress words and (2) read stressed syllables longer than unstressed syllables with appropriate stress assignment. Our findings suggest that intermediate EFL learners can recognize and manipulate L2 prosodic information, even though their L1 does not possess the property. Future directions for L2 oral reading research development are discussed.
Preparation and Properties of Polyaniline in the Presence of Trehalose  [PDF]
Hirotsugu Kawashima, Hiromasa Goto
Soft Nanoscience Letters (SNL) , 2011, DOI: 10.4236/snl.2011.13013
Abstract: Oxidative polymerization of aniline in aqueous solution in the presence of trehalose was conducted. Fourier transform infrared spectroscopy confirmed successful preparation of polyaniline containing a trace amount of trehalose. Electron spin resonance spectroscopy revealed that electron spin concentration of the polyaniline increases with aniline/trehalose ratio in the polymerization. Scanning electron microscopy revealed that the polyaniline shows granular and porous morphology. Electrical conductivity of these polyanilines was in the order of 10-4 S/cm.
Effects of Terrain-Induced Turbulence on Wind Turbine Blade Fatigue Loads  [PDF]
Yasushi Kawashima, Takanori Uchida
Energy and Power Engineering (EPE) , 2017, DOI: 10.4236/epe.2017.913053
Abstract: Recently, the issue has surfaced that the availability factors for wind farms built on complex terrain are lower than the originally projected values. In other words, problems have occurred such as extreme decreases in generation output, failures of components inside and outside wind turbines including yaw motors and yaw gears, and cracking on wind turbine blades. As one of the causes of such issues, the effects of wind turbulence (terrain-induced turbulence) have been pointed out. In this study, we investigated the effects of terrain-induced turbulence on the structural strength of wind turbines through the measurement of strains in wind turbine blades and the analysis of wind data in order to establish a method for optimal wind turbine deployment that uses numerically simulated wind data and takes the structural strength of wind turbines into consideration. The investigation was conducted on Wind Turbine #10 of the Kushikino Reimei Wind Farm (in operation since Nov. 2012) in cooperation with Kyudenko New Energy Co., Ltd. Subsequently, we conducted numerical wind simulations (diagnoses of terrain-induced turbulence) to study the effects of the properties of airflow on the structural strength of wind turbines. For these simulations, the natural terrain version of the RIAM-COMPACT software package, which is based on large eddy simulation (LES), was used. The numerical simulations successfully reproduced the characteristics of the wind conditions and the structure of the three-dimensional airflow. These results enabled us to determine the threshold value for a turbulence index to be used for optimal wind turbine deployment planning that utilizes quantitative data from simulations with the natural terrain version of the RIAM-COMPACT software package.
Modularity of Calabi--Yau varieties: 2011 and beyond
Noriko Yui
Mathematics , 2012,
Abstract: This paper presents the current status on modularity of Calabi-Yau varieties since the last update in 2003. We will focus on Calabi-Yau varieties of dimension at most three. Here modularity refers to at least two different types: arithmetic modularity and geometric modularity. These will include: (1) the modularity (automorphy) of Galois representations of Calabi-Yau varieties (or motives) defined over Q or number fields, (2) the modularity of solutions of Picard--Fuchs differential equations of families of Calabi-Yau varieties, and mirror maps (mirror moonshine), (3) the modularity of generating functions of invariants counting certain quantities on Calabi-Yau varieties, and (4) the modularity of moduli for families of Calabi-Yau varieties.
Construction of the least informative observable conserved by a given quantum instrument
Yui Kuramochi
Mathematics , 2015, DOI: 10.1063/1.4931625
Abstract: For a quantum measurement process described by a quantum instrument $\mathcal{I}$ and a system observable corresponding to a positive-operator valued measure (POVM) $E ,$ $\mathcal{I}$ is said to conserve the information of $E$ if the joint successive measurement of $\mathcal{I}$ followed by $E$ is equivalent to a single measurement of $E .$ We show that for any quantum instrument $\mathcal{I}$ we can construct a POVM conserved by $\mathcal{I}$. Intuitively the construction gives the infinite joint successive measurement of $\mathcal{I}.$ We also show that the constructed POVM is the least informative observable among POVMs conserved by $\mathcal{I}$, i.e. the constructed POVM can be realized by a classical post-processing of any POVM conserved by $\mathcal{I} .$ As typical examples of quantum instruments, we explicitly evaluate POVMs of infinite successive measurements for photon counting and quantum counter instruments.
Minimal sufficient positive-operator valued measure on a separable Hilbert space
Yui Kuramochi
Mathematics , 2015, DOI: 10.1063/1.4934235
Abstract: We introduce a concept of a minimal sufficient positive-operator valued measure (POVM), which is the least redundant POVM among the POVMs that have the equivalent information about the measured quantum system. Assuming the system Hilbert space to be separable, we show that for a given POVM a sufficient statistic called a Lehmann-Scheff\'{e}-Bahadur statistic induces a minimal sufficient POVM. We also show that every POVM has an equivalent minimal sufficient POVM and that such a minimal sufficient POVM is unique up to relabeling neglecting null sets. We apply these results to discrete POVMs and information conservation conditions proposed by the author.
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