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The University of Tokyo , abbreviated as Todai , is a research university located in Bunkyo, Tokyo, Japan. The University has 10 faculties with a total of around 30,000 students, 2,100 of whom are foreign. Its five campuses are in Hongō, Komaba, Kashiwa, Shirokane and Nakano. It is the first of Japan's National Seven Universities, and is considered the most prestigious university in Japan. It ranks as the highest in Asia and 21st in the world according to the Academic Ranking of World Universities 2014. Wikipedia.

Aoki Y.,University of Tokyo
Translational psychiatry | Year: 2012

Atypical trajectory of brain growth in autism spectrum disorders (ASDs) has been recognized as a potential etiology of an atypical course of behavioral development. Numerous neuroimaging studies have focused on childhood to investigate atypical age-related change of brain structure and function, because it is a period of neuron and synapse maturation. Recent studies, however, have shown that the atypical age-related structural change of autistic brain expands beyond childhood and constitutes neural underpinnings for lifelong difficulty to behavioral adaptation. Thus, we examined effects of aging on neurochemical aspects of brain maturation using 3-T proton magnetic resonance spectroscopy ((1)H-MRS) with single voxel in the medial prefrontal cortex (PFC) in 24 adult men with non-medicated high-functioning ASDs and 25 age-, IQ- and parental-socioeconomic-background-matched men with typical development (TD). Multivariate analyses of covariance demonstrated significantly high N-acetylaspartate (NAA) level in the ASD subjects compared with the TD subjects (F=4.83, P=0.033). The low NAA level showed a significant positive correlation with advanced age in the TD group (r=-0.618, P=0.001), but was not evident among the ASD individuals (r=0.258, P=0.223). Fisher's r-to-z transformation showed a significant difference in the correlations between the ASD and TD groups (Z=-3.23, P=0.001), which indicated that the age-NAA relationship was significantly specific to people with TD. The current (1)H-MRS study provided new evidence that atypical age-related change of neurochemical aspects of brain maturation in ASD individuals expands beyond childhood and persists during adulthood.

Kawakatsu H.,University of Tokyo | Yoshioka S.,Kobe University
Earth and Planetary Science Letters | Year: 2011

Oceanic plates subducted at trenches penetrate into the deep mantle, and encounter a structural boundary at a depth of 410km where olivine, the dominant element of mantle rocks, transforms into a higher density form wadsleyite. This transformation may be delayed within the coldest core of subducting plates (slabs) due to kinetic effects, and it has been suggested that metastable olivine may persist deeper than 410km. Using high density seismic array data in Japan, we show the direct image of the structure corresponding to this metastable olivine wedge (MOW) beneath southwest Japan. Numerical simulation of a subducting slab, including the kinetic effect of water (H2O) on the olivine-wadsleyite transformation, indicates that the presence of the imaged MOW requires an insignificant amount of water (less than 100wt. ppm) be present in the slab mantle, thus a deep dry cold slab. We infer that the transportation of water into the deep mantle occurs along the top surface of the subducting slab, but no significant amount within the slab itself. We also demonstrate that a numerical simulation including the kinetics of 660-km phase transformation can reconcile the observed deep depression of the 660-km discontinuity with a gentle Clapeyron slope. © 2011 Elsevier B.V.

Lee S.,Dongguk University | Lee Y.,Dongguk University | Song E.B.,University of California at Los Angeles | Hiramoto T.,University of Tokyo
Nano Letters | Year: 2014

Single electron transport through multiple quantum levels is realized in a Si quantum-dot device at room-temperature conditions. The energy spacing of more than triple the omnipresent thermal energy is obtained from an extremely small ellipsoidal Si quantum dot, and high charge stability is attained through a construction of the gate-all-around structure. These properties may move us a step closer to practical applications of quantum devices at elevated temperatures. An in-depth analysis on the transport behavior and quantum structure is presented. © 2013 American Chemical Society.

A standard nominally third-order upwind-biased spatial discretization of the flux-divergence operator was extended to a spherical icosahedral grid. The method can be used with multistage time-stepping schemes such as the Runge-Kutta method to compute the transport of variables on both hexagonal-pentagonal and triangular meshes. Two algorithms can be used to determine mesh cell face values: 1) interpolation using a quadratic function reconstructed subject to an integral constraint, or 2) calculation of the weighted mean of two linearly interpolated and extrapolated values. The first approach was adopted for a triangular mesh because the second approach depends on the mesh having a hexagonal or pentagonal shape. Both approaches were tested on the hexagonal-pentagonal mesh. These schemes were subjected to standard transport tests on a spherical icosahedral grid. A three-stage Runge-Kutta time stepping method was used, and if necessary a flux limiter was applied to maintain monotonicity. The two different methods produced very similar solutions on a hexagonal-pentagonal mesh. Their accuracy was very close to the accuracy of a preexisting method designed for a Voronoi mesh only. When compared to another method that uses a quadratic polynomial interpolation, the phase error of the solutions was reduced, and their accuracy was much improved. The accuracies of the solutions were comparable on triangular and hexagonal-pentagonal meshes. © 2013 American Meteorological Society.

Maeda T.,University of Tokyo
FEBS Journal | Year: 2012

The four protein complexes termed endosomal sorting complexes required for transport (ESCRT) are key mediators of multivesicular body sorting/formation, retroviral budding and cell abscission, which share a membrane deformation process with the same topological change: vesicles budding away from the cytoplasm. Independent studies of the signal transduction pathways that mediate ambient pH sensing and adaptation in yeast and fungi revealed that these pathways share a conserved signaling mechanism that utilizes ESCRT complexes for its activation. This pathway in Saccharomyces cerevisiae, termed the Rim101 pathway, consists of both a sensing complex, which senses ambient alkaline pH, and a proteolytic complex, which proteolyzes and thereby activates the key transcription factor Rim101. Since the proteolytic complex is thought to be formed and activated on a platform of a multimerized ESCRT-III component Snf7, the organization, regulation and function of this pathway are dependent on the function of ESCRT complexes. © 2012 The Author Journal compilation © 2012 FEBS.

Nishitoh H.,University of Tokyo
Journal of Biochemistry | Year: 2012

The accumulation of unfolded proteins in the endoplasmic reticulum (ER) induces ER stress. To restore ER homeostasis, cells possess a highly specific ER quality-control system called the unfold protein response (UPR). In the case of prolonged ER stress or UPR malfunction, apoptosis signalling is activated. This ER stress-induced apoptosis has been implicated in the pathogenesis of several conformational diseases. CCAAT-enhancer-binding protein homologous protein (CHOP) is induced by ER stress and mediates apoptosis. Recent studies by the Gotoh group have shown that the CHOP pathway is also involved in ER stress-induced cytokine production in macrophages. The multifunctional roles of CHOP in the ER stress response are discussed below. © 2011 The Authors.

SUMMARY: Supplemental damping is known as an efficient and practical means to improve seismic response of building structures. Presented in this paper is a mixed-integer programming approach to find the optimal placement of supplemental dampers in a given shear building model. The damping coefficients of dampers are treated as discrete design variables. It is shown that a minimization problem of the sum of the transfer function amplitudes of the interstory drifts can be formulated as a mixed-integer second-order cone programming problem. The global optimal solution of the optimization problem is then found by using a solver based on a branch-and-cut algorithm. Two numerical examples in literature are solved with discrete design variables. In one of these examples, the proposed method finds a better solution than an existing method in literature developed for the continuous optimal damper placement problem. © 2013 John Wiley & Sons, Ltd.

Honda S.,University of Tokyo
Geochemistry, Geophysics, Geosystems | Year: 2011

We have proposed an existence of small-scale convection in the mantle wedge in order to explain the alignment of group of volcanoes in the NE Honshu subduction zone, Japan. The roll type thermal convection whose axis is normal to the plate boundaries and "flip-flopping" of rolls (warmer and colder parts exchange their positions, as time passes) are reported. However, the subsequent study shows an existence of non-flip-flopping rolls, also. Thus, in this study, I investigate the possible causes of these differences systematically. I found that along-arc wavelength of small-scale convection is controlled by two length scales which may be associated with the inclined nature of the bottom of the low viscosity mantle wedge where the small-scale convection emerges. When the convection is in early stage of evolvement or the speed of subducting slab is small, the long-wavelength rolls become prominent. As the convection evolves or the speed of subduction increases, short-wavelength rolls tend to take over the long-wavelength rolls. The transition from the long-wavelength to the short-wavelength rolls occurs in a several way. It may occur through the splitting of rolls, adjustment of roll patterns and flip-flopping. If the pattern becomes short-wavelength roll, it becomes stable. The range of existence of flip-flopping is limited and the existence of viscosity jump in the top thermal boundary layer may be required. Copyright 2011 by the American Geophysical Union.

Hirose S.,University of Tokyo
Cerebral cortex (New York, N.Y. : 1991) | Year: 2013

Recent advancement of resting-state functional connectivity magnetic resonance imaging (MRI) has provided a method for drawing boundaries of brain areas. However, it remains to be elucidated how the parcellated areas in the association cortex relate to the spatial extent of the brain activation which ought to reflect a functional unit in the neural network supporting that particular function. To address this issue, in the present study, we first mapped boundaries and 2 adjacent activations in the human inferior frontal cortex, and then examined the spatial relationship between the boundaries and the 2 activations. The boundaries mapped with high-resolution functional magnetic resonance imaging revealed a collection of micromodules, the size of which was approximately only 12 mm on average, much smaller than the Brodmann areas. Each of the 2 activations associated with 2 functions, response inhibition and feedback processing, was smaller in size than the micromodules. By comparing the spatial patterns between the boundaries and the 2 activations, it was revealed that the brain activations were less likely to be located on the boundaries. These results suggest the functional relevance of the areas in the association cortex delineated by the boundary mapping method based on resting-state functional connectivity MRI.

Doi M.,University of Tokyo
Journal of Physics Condensed Matter | Year: 2011

In the celebrated paper on the reciprocal relation for the kinetic coefficients in irreversible processes, Onsager (1931 Phys.Rev.37 405) extended Rayleigh's principle of the least energy dissipation to general irreversible processes. In this paper, I shall show that this variational principle gives us a very convenient framework for deriving many established equations which describe the nonlinear and non-equilibrium phenomena in soft matter, such as phase separation kinetics in solutions, gel dynamics, molecular modeling for viscoelasticity nemato-hydrodynamics, etc. Onsager's variational principle can therefore be regarded as a solid general basis for soft matter physics. © 2011 IOP Publishing Ltd.

Tanaka H.,University of Tokyo
Journal of Physics Condensed Matter | Year: 2011

It is widely believed that crystallization in three dimensions is primarily controlled by positional ordering, and not by bond orientational ordering. In other words, bond orientational ordering is usually considered to be merely a consequence of positional ordering and thus has often been ignored. This one-order-parameter (density) description may be reasonable when we consider an equilibrium liquid-solid transition, but may not be enough to describe a metastable state and the kinetics of the transition. Here we propose that bond orientational ordering can play a key role in (i)crystallization, (ii)the ordering to quasi-crystal and (iii)vitrification, which occurs under rather weak frustration against crystallization. In a metastable supercooled state before crystallization, a system generally tends to have bond orientational order at least locally as a result of a constraint of dense packing. For a system interacting with hard-core repulsions, the constraint is intrinsically of geometrical origin and thus the basic physics is the same as nematic ordering of rod-like particles upon densification. Furthermore, positional ordering is easily destroyed even by weak frustration such as polydispersity and anisotropic interactions which favour a symmetry not consistent with that of the equilibrium crystal. Thus we may say that vitrification can be achieved by disturbing and prohibiting long-range positional ordering. Even in such a situation, bond orientational ordering still survives, accompanying its critical-like fluctuations, which are the origin of dynamic heterogeneity for this case. This scenario naturally explains both the absence of positional order and the development of bond orientational order upon cooling in a supercooled state. Although our argument is speculative in nature, we emphasize that this physical picture can coherently explain crystallization, vitrification, quasi-crystallization and their relationship in a natural manner. For a strongly frustrated system, even bond orientational order can be destroyed. Even in such a case there may still appear a structural signature of dense packing, which is linked to slow dynamics. © 2011 IOP Publishing Ltd.

Hotta D.,Japan Meteorological Agency | Nakamura H.,University of Tokyo
Journal of Climate | Year: 2011

The relative importance between the sensible heat supply from the ocean and latent heating is assessed for the maintenance of near-surface mean baroclinicity in the major storm-track regions, by analyzing steady linear responses of a planetary wave model to individual components of zonally asymmetric thermal forcing taken from a global reanalysis dataset. The model experiments carried out separately for the North Atlantic, North Pacific, and south Indian Oceans indicate that distinct local maxima of near-surface baroclinicity observed along the storm tracks can be reinforced most efficiently as a response to the near-surface sensible heating. The result suggests the particular importance of the differential sensible heat supply from the ocean across an oceanic frontal zone for the efficient restoration of surface baroclinicity, which acts against the relaxing effect by poleward eddy heat transport, setting up conditions favorable for the recurrent development of transient eddies to anchor a storm track. Unlike what has been suggested, the corresponding reinforcement of the near-surface baroclinicity along a storm track as the response to the latent heating due either to cumulus convection or large-scale condensation is found less efficient. As is well known, poleward eddy heat flux convergence acts as the primary contributor to the reinforcement of the surface westerlies, especially in the core of a storm track. In its exit region, a substantial contribution to the reinforcement arises also from a planetary wave response to the sensible heat supply from the ocean. In contrast, the surface wind acceleration as a planetary wave response to the latent heating is found to contribute negatively to the maintenance of the surface westerlies along any of the major storm tracks. © 2011 American Meteorological Society.

Katagiri K.,University of Tokyo
Methods in enzymology | Year: 2010

Apoptosis signal-regulating kinase 1 (ASK1) is a member of the mitogen-activated protein kinase (MAPK) kinase kinase family and elicits a wide variety of cellular responses to various types of stress through activation of the JNK and p38 MAPK pathways. ASK1 is preferentially activated in response to oxidative stress, but this regulatory mechanism is still not completely understood. In our previous report, thioredoxin (Trx), which is an antioxidant protein and plays pivotal roles in maintaining intracellular redox balance, inhibited ASK1 kinase activity by direct binding to ASK1 under normal conditions. Under oxidative conditions, ASK1 is dissociated from Trx and therefore fully activated. The active site of Trx contains two cysteine residues that undergo reversible oxidation to form a disulfide bond with each other, so that the conformation of Trx is changed by intracellular redox conditions. Thus, the oxidative stress-induced conformational change of Trx is particularly important for interaction with and regulation of ASK1, and elucidation of the regulatory mechanisms of ASK1 by Trx is critical to understanding the intracellular redox signaling. In this chapter, we review the regulatory mechanisms of ASK1 activity by Trx, and describe a method for monitoring in vitro binding between Trx and ASK1 under various redox conditions. In addition, we present methods to detect the oxidative stress-induced activation of ASK1 in the cells by Western blot analysis and in vitro kinase assay. The techniques presented in this chapter will be useful for a range of investigations into intracellular redox signaling. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Nojiri H.,University of Tokyo
Current Opinion in Biotechnology | Year: 2013

It is difficult to know the exact extent to which catabolic plasmids influence the metabolism of different hosts, but this information is crucial for improving the use of xenobiotic degraders possessing conjugative catabolic plasmids. To determine the molecular mechanisms by which catabolic plasmids affect host-cell physiology and host responses, comprehensive molecular surveys have examined host responses to plasmid carriage. These studies have clarified the various interactions between catabolic plasmids and host cells and the importance of the effects on host-cell physiology and metabolic pathways. It has been suggested that catabolic plasmid-borne nucleoid-associated proteins play key roles in the adaptation of catabolic plasmids to the host-cell regulatory network. © 2013 Elsevier Ltd.

Yoshida S.,University of Tokyo
Monthly Notices of the Royal Astronomical Society | Year: 2013

A deformation of a neutron star due to its own magnetic field is an important issue in gravitational wave astronomy, since a misaligned rotator with small ellipticity may emit continuous gravitational wave that may be observed by ground-based detectors. Recently, Mastrano et al. evaluated deformations induced by both poloidal and toroidal magnetic field in non-barotropic model stars by neglecting the gravitational field perturbation (Cowling approximation). Following their treatment in non-barotropic fluid and magnetic configurations, we here assess the effect of gravitational perturbation that they neglected. We show that the ellipticity computed with gravitational perturbation is roughly twice as large as that obtained by Cowling approximation. We should allow this amount of error in using the neat analytic treatment proposed by them. © 2013 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

Phymatoderma is a branching burrow system consisting of tunnels filled with faecal pellets, and it has been interpreted as a product of a surface deposit-feeding animal. Elemental analyses of Phymatoderma were conducted to reveal the specific feeding mode of its tracemaker, using samples from the Lower Jurassic epicontinental shelf deposits in the Dotternhausen section, southern Germany and from the Upper Pliocene continental slope deposits in the Shioura section, central Japan. Elemental compositions of the pelletal infill of Phymatoderma and its overlying mudstone from the Dotternhausen section show no significant difference, suggesting that the tracemaker was a non-selective deposit feeder. In contrast, elemental compositions of the tuffaceous pellets of Phymatoderma from the Shioura section and its overlying volcanic ash show a difference in trends: CaO is significantly concentrated in the pellets. Because microfossils such as foraminifera and coccoliths are occasionally found in the tuffaceous pellets, CaO accumulation in the pelletal infill indicates the Phymatoderma-producer that lived in the Pliocene slope setting selectively ingested particles with higher biomass of such microorganisms (or ingested microorganisms themselves) when feeding the surface sediments. Although two types of feeding modes of the tracemaker were recognized in Phymatoderma between different bathymetrical settings, each feeding mode seems to be an effective strategy to intake nutrients from the surface sediments and to reflect an adaptation of the tracemaker to the food contents in the surrounding substrate. This study suggests that geochemical composition of faecal pellets of trace fossils can be a useful indicator of grain-selective/non-selective deposit-feeding strategies of ancient animals. © 2013 The Lethaia Foundation.

Liu M.,RIKEN | Ishida Y.,RIKEN | Ebina Y.,Japan International Center for Materials Nanoarchitectonics | Sasaki T.,Japan International Center for Materials Nanoarchitectonics | And 4 more authors.
Nature | Year: 2015

Machine technology frequently putsmagnetic or electrostatic repulsive forces to practical use, as inmaglev trains, vehicle suspensions or non-contact bearings1,2. Incontrast, materials designoverwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix toimprovemechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression3,4. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanatenanosheets5 embedded within it.Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion6 andthereby induces a quasi-crystalline structural ordering7,8 overmacroscopic length scales and with uniformly large face-to-face nanosheet separation.We fix this transiently induced structural order by transforming the dispersion into a hydrogel9,10 using light-triggered in situ vinyl polymerization11. The resultant hydrogel, containing charged inorganic structures that align cofacially in amagnetic flux12-19, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions. © 2015 Macmillan Publishers Limited.

Nagata Y.,University of Tokyo
Cell structure and function | Year: 2010

Satellite cells are muscle-resident stem cells, which are located beneath the basement membrane of myofibers. Because the number of satellite cells is normally constant, there must be a tight regulation of satellite cell activation and self-renewal. However, the molecular mechanisms involved in satellite cell maintenance are largely unknown, and thus have become the subject of extensive study these days. Although RNA interference with a small interfering RNA has been widely used to investigate the role of specific gene products, inefficient knockdown of Grb2 expression occurred in quiescent reserve cells, a model for quiescent satellite cells, by ordinary transfection protocol. In this study we report that pretreatment with trypsin greatly enhanced siRNA delivery into quiescent reserve cells, resulting in efficient silencing of Grb2 expression. By applying a combination of Grb2-silencing and protein kinase C inhibitors, we demonstrated that extracellular signal-regulated kinase (ERK) phosphorylation induced with fibroblast growth factor 2 (FGF2) was dependent on both Grb2 and protein kinase C (PKC) with different kinetics. We concluded that the PKC-mediated pathway contributes to rapid initiation and termination of ERK phosphorylation, while the Grb2-mediated pathway contributes to delayed and sustained ERK phosphorylation.

Nishida K.,University of Tokyo
Geophysical Research Letters | Year: 2013

Seismic interferometry has now been applied to the exploration of the Earth's interior at scales ranging from local to global. Most studies have used surface-wave propagation. Recently, some studies have focused on body wave propagation on local and regional scales but not on a global scale. In this study, we succeed in extracting global body wave propagation(of P, PP, PKP, S, SS, ScS, P′P′, etc. waves) using seismic hum with frequency-wave number filtering in the range of 5 to 40 mHz. Although the observed body wave propagation is similar to that of the corresponding components of Green's functions, there are two differences between them: the lack of reflection phases in the observation and the dominance of shear-coupled PL waves in the observation. These differences originate from the dominance of shear-traction sources on the Earth's surface, which causes the breakdown of equipartition among modes with different radial orders. For further studies of body wave exploration by seismic interferometry, these differences should be considered. Key Points We succeed in extracting global body-wave propagation using seismic hum.SPL waves in the observation are more dominant than those in Green's functions.The dominance originates from their shear-traction sources on the seafloor. ©2013. American Geophysical Union. All Rights Reserved.

Koseki J.,University of Tokyo
Geotextiles and Geomembranes | Year: 2012

After reviewing seismic performance of earth structures based on case histories in Japan and relevant model test results, advantages of using geosynthetics in improving their seismic performance are demonstrated. As one of the successful applications, geosynthetic-reinforced soil retaining walls are highlighted, focusing on several influential factors such as facing rigidity, arrangement and properties of reinforcements, and backfill and subsoil conditions. In addition, further applications of the reinforcement method using geosynthetics are introduced, which include combination with other reinforcement methods, application to bridge abutments and piers, and application to ballasted railway tracks. © 2012 Elsevier Ltd.

Understanding the key factors influencing the global oceanic redox system is crucial to fully explaining the variations in oceanic chemical dynamics that have occurred throughout the Earth's history. In order to elucidate the mechanisms behind these variations on geological timescales, numerical sensitivity experiments were conducted with respect to the partial pressure of atmospheric molecular oxygen (pO2), the continental shelf area (Acs), and the riverine input rate of reactive phosphorus to the oceans (RP). The sensitivity experiment for atmospheric pO2 indicates that pervasive oceanic anoxia and euxinia appear when pO2<0.145atm and <0.125atm, respectively. These critical values of pO2 are higher than a previous estimate of ~50% PAL (present atmospheric level) due to redox-dependent phosphorus cycling. The sensitivity experiment regarding the shelf area demonstrates that changes in the shelf area during the Phanerozoic significantly affected oceanic oxygenation states by changing marine biogeochemical cycling; a large continental shelf acts as an efficient buffer against oceanic eutrophication and prevents the appearance of ocean anoxia/euxinia. We also found that an enhanced RP is an important mechanism for generation of widespread anoxia/euxinia via expansion of both the oxygen minimum zone and coastal deoxygenation, although the critical RP value depends significantly on pO2, Acs, and the redox-dependent burial efficiency of phosphorus at the sediment--water interface. Our systematic examination of the oceanic redox state under Cretaceous greenhouse climatic conditions also supports the above results. © 2013 Elsevier B.V.

Song T.-R.A.,Japan Agency for Marine - Earth Science and Technology | Kawakatsu H.,University of Tokyo
Geophysical Research Letters | Year: 2012

The oceanic asthenosphere is characterized as a low viscosity channel down to 200-300 km depth separating the cold lithosphere from above, and it is intimately linked to a layer of low seismic velocity and prominent seismic anisotropy observed globally beneath ocean basins. While subduction of tectonic plates in convergent margins is well recognized, the fate of oceanic asthenosphere remains enigmatic. We demonstrate that subduction of the oceanic asthenosphere characterized by weak azimuthal anisotropy and strong radial anisotropy explains the essence of sub-slab shear-wave splitting patterns, where the fast splitting direction changes from predominantly trench-parallel (or sub-parallel) under relatively steep subduction zones to frequently trench-normal under shallow subduction zones. To explain the observed splitting time, the thickness of the subducted asthenosphere is estimated to be 100 ± 50 km. © 2012. American Geophysical Union. All Rights Reserved.

Polyion complex (PIC) formation is one of the most powerful techniques for obtaining molecular self-assemblies in aqueous media. The simple preparation process based on multiple electrostatic interactions is quite attractive for material syntheses, as well as biomedical applications. Therefore, it is desirable to control PIC architectures at the nanoscale in order to expand the scope of PIC materials. In this review article, recent progress on PIC vesicles (PICsomes) is summarized. PICsomes were first developed by my research group, and we recently succeeded in controlling the sizes and structural uniformity of the vesicles. Furthermore, the characteristic dynamic nature of PICs was revealed: PICs were found to exhibit reversible association/dissociation and structural transformation. We demonstrated that crosslinking the PIC layers of PICsomes is a powerful method for tuning properties such as stability and permeability. Finally, the potential utility of PICsomes for drug delivery nanocarriers was examined, and their future biomedical application is discussed. © 2013 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Isogai A.,University of Tokyo
Journal of Wood Science | Year: 2013

Nanocelluloses, which include nanofibrillated celluloses (NFCs) and cellulose nanocrystals (CNCs) with high and low aspect ratios, respectively, are promising new bio-based nanomaterials, prepared from wood and other plant celluloses by mechanical shearing in water with or without pretreatments. Low degrees of enzymatic hydrolysis, carboxymethylation, acetylation, oxidation, and other position-selective modifications on cellulose microfibril surfaces have been applied as pretreatments to wood celluloses to reduce energy consumption in the mechanical shearing process and to improve the nanofibrillation level of the obtained NFCs. NFCs are convertible to nanocellulose sheets, films, hydrogels, foams, and aerogels with fibril network structures or close-packing structures using coating on base films or filtration process like papermaking, which is advantageous for efficient removal of water predominantly present in the NFC/water dispersions. NFC-containing self-standing films, coated films, and NFC/matrix nanocomposites in most cases show explicitly high mechanical strength and ductility despite being lightweight and having optical transparency, thermal stability, and gas-barrier properties. Because NFCs have aspect ratios and molecular weights higher than those of CNCs, the most promising and challenging end products are NFC-containing nanocomposite materials having higher functionalities than those of the conventional fiber-reinforced composite materials. © 2013 The Japan Wood Research Society.

Takei Y.,University of Tokyo
Proceedings. Biological sciences / The Royal Society | Year: 2012

Like many desert animals, the spinifex hopping mouse, Notomys alexis, can maintain water balance without drinking water. The role of the kidney in producing a small volume of highly concentrated urine has been well-documented, but little is known about the physiological mechanisms underpinning the metabolic production of water to offset obligatory water loss. In Notomys, we found that water deprivation (WD) induced a sustained high food intake that exceeded the pre-deprivation level, which was driven by parallel changes in plasma leptin and ghrelin and the expression of orexigenic and anorectic neuropeptide genes in the hypothalamus; these changed in a direction that would stimulate appetite. As the period of WD was prolonged, body fat disappeared but body mass increased gradually, which was attributed to hepatic glycogen storage. Switching metabolic strategy from lipids to carbohydrates would enhance metabolic water production per oxygen molecule, thus providing a mechanism to minimize respiratory water loss. The changes observed in appetite control and metabolic strategy in Notomys were absent or less prominent in laboratory mice. This study reveals novel mechanisms for appetite regulation and energy metabolism that could be essential for desert rodents to survive in xeric environments.

Outgassing, which changes the distribution of volcanic gases in magmas, is one of the most important processes to determine the eruption styles. Shear deformation of ascending bubbly magmas at the vicinity of the volcanic conduit wall has been considered as an efficient mechanism of outgassing. On the other hand, seismological observations of volcanic eruptions reveal the gas bursting associated with long-period (LP) earthquakes and tremors, suggesting the existence of a large void space in the conduit. However both, the quantitative features of shear-induced outgassing and a mechanism to make a large void space, have still remain unknown. Here I perform a series of model experiments in which shear localization of syrup foam causes outgassing by making large bubbles or a crack-like void space, likely a gas bursting source. There is a critical strain, γ, above which outgassing occurs depending on the Capillary number, Ca, γ>1 for Ca<1 and γ>Ca -1 for Ca≥1. The width of the region in which outgassing occurs is described as a function of γ 0.48Ca 0.24. Outgassing occurs efficiently at the very beginning of the deformation, suggesting that intermittent magma ascent causes effective outgassing such that the eruption style becomes effusive. This hypothesis is consistent with the fact that cyclic activity has been observed during effusive dome eruptions. © 2012 Elsevier B.V.

Fujiwara S.,University of Tokyo
Proceedings. Biological sciences / The Royal Society | Year: 2012

Forelimb posture has been a controversial aspect of reconstructing locomotor behaviour in extinct quadrupedal tetrapods. This is partly owing to the qualitative and subjective nature of typical methods, which focus on bony articulations that are often ambiguous and unvalidated postural indicators. Here we outline a new, quantitatively based forelimb posture index that is applicable to a majority of extant tetrapods. By determining the degree of elbow joint adduction/abduction mobility in several tetrapods, the carpal flexor muscles were determined to also play a role as elbow adductors. Such adduction may play a major role during the stance phase in sprawling postures. This role is different from those of upright/sagittal and sloth-like creeping postures, which, respectively, depend more on elbow extensors and flexors. Our measurements of elbow muscle moment arms in 318 extant tetrapod skeletons (Lissamphibia, Synapsida and Reptilia: 33 major clades and 263 genera) revealed that sprawling, sagittal and creeping tetrapods, respectively, emphasize elbow adductor, extensor and flexor muscles. Furthermore, scansorial and non-scansorial taxa, respectively, emphasize flexors and extensors. Thus, forelimb postures of extinct tetrapods can be qualitatively classified based on our quantitative index. Using this method, we find that Triceratops (Ceratopsidae), Anhanguera (Pterosauria) and desmostylian mammals are categorized as upright/sagittally locomoting taxa.

Nitrate reductase is a key enzyme in nitrogen assimilation, and it catalyzes the nitrate-to-nitrite reduction process in plants. A variety of factors, including nitrate, light, metabolites, phytohormones, low temperature, and drought, modulate the expression levels of nitrate reductase genes as well as nitrate reductase activity, which is consistent with its physiological role. Recently, several transcription factors involved in controlling the expression of nitrate reductase genes have been identified in Arabidopsis. NODULE-INCEPTION-like proteins (NLPs) are transcription factors responsible for nitrate-inducible expression of nitrate reductase genes. Since NLPs also control nitrate-inducible expression of genes encoding nitrate transporter, nitrite transporter, and nitrite reductase, the expression levels of nitrate reduction pathway-associated genes are coordinately modulated by NLPs in response to nitrate. LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors (LBD37-LBD39) are strong candidates for transcription factors mediating negative feedback regulation in response to increases in the contents of nitrogen-containing metabolites, whereas LONG HYPOCOTYL 5 (HY5) that promotes photomorphogenesis in light may be a transcription factor involved in light-induced expression of a nitrate reductase gene. Furthermore, unidentified transcription factors likely mediate other signals and regulate the expression of nitrate reductase genes. This review presents a summary of our current knowledge of such transcription factors. © 2014 Elsevier Ireland Ltd.

Shibahashi H.,University of Tokyo | Kurtz D.W.,University of Central Lancashire
Monthly Notices of the Royal Astronomical Society | Year: 2012

Some pulsating stars are good clocks. When they are found in binary stars, the frequencies of their luminosity variations are modulated by the Doppler effect caused by orbital motion. For each pulsation frequency this manifests itself as a multiplet separated by the orbital frequency in the Fourier transform of the light curve of the star. We derive the theoretical relations to exploit data from the Fourier transform to derive all the parameters of a binary system traditionally extracted from spectroscopic radial velocities, including the mass function which is easily derived from the amplitude ratio of the first orbital sidelobes to the central frequency for each pulsation frequency. This is a new technique that yields radial velocities from the Doppler shift of a pulsation frequency, thus eliminates the need to obtain spectra. For binary stars with pulsating components, an orbital solution can be obtained from the light curve alone. We give a complete derivation of this and demonstrate it both with artificial data, and with a case of a hierarchical eclipsing binary with Kepler mission data, KIC4150611 (HD181469). We show that it is possible to detect Jupiter-mass planets orbiting δSct and other pulsating stars with our technique. We also show how to distinguish orbital frequency multiplets from potentially similar non-radial m-mode multiplets and from oblique pulsation multiplets. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Matsuo Y.,University of Tokyo
Pure and Applied Chemistry | Year: 2012

This article describes a concept for designing fullerene-based electron-accepting materials to obtain high open-circuit voltage (V OC) in organic thin-film photovoltaic devices without an accompanying decrease in short-circuit current density. The keys to this concept are (1) reducing the size of the fullerene L{cyrillic}-conjugated system to realize high V OC and (2) shortening the inter-fullerene distance in the solid-state packing structure to achieve high short-circuit current density (J SC), which is made possible by well-designed supramolecular organization or a small organic addend. In this article, two representative examples are discussed. One is 1,4-bis(silylmethyl)[60]fullerene (SIMEF), which forms a columnar fullerene-core array for high electron mobility and undergoes thermal crystallization for good phase separation with the electron-donating material. The other is a 56Lπ-electron fullerene derivative bearing a dihydromethano group, the smallest carbon addend, which does not disrupt fullerene-fullerene contact in the solid state. © 2012 IUPAC.

Estrada E.,University of Strathclyde | Hatano N.,University of Tokyo | Benzi M.,Emory University
Physics Reports | Year: 2012

A fundamental problem in the study of complex networks is to provide quantitative measures of correlation and information flow between different parts of a system. To this end, several notions of communicability have been introduced and applied to a wide variety of real-world networks in recent years. Several such communicability functions are reviewed in this paper. It is emphasized that communication and correlation in networks can take place through many more routes than the shortest paths, a fact that may not have been sufficiently appreciated in previously proposed correlation measures. In contrast to these, the communicability measures reviewed in this paper are defined by taking into account all possible routes between two nodes, assigning smaller weights to longer ones. This point of view naturally leads to the definition of communicability in terms of matrix functions, such as the exponential, resolvent, and hyperbolic functions, in which the matrix argument is either the adjacency matrix or the graph Laplacian associated with the network.Considerable insight on communicability can be gained by modeling a network as a system of oscillators and deriving physical interpretations, both classical and quantum-mechanical, of various communicability functions. Applications of communicability measures to the analysis of complex systems are illustrated on a variety of biological, physical and social networks. The last part of the paper is devoted to a review of the notion of locality in complex networks and to computational aspects that by exploiting sparsity can greatly reduce the computational efforts for the calculation of communicability functions for large networks. © 2012 Elsevier B.V.

Tsubouchi K.,University of Tokyo
Astrophysical Journal | Year: 2011

One-dimensional hybrid simulations are used to investigate the particle energization process during the nonstationary evolution of corotating interaction regions (CIRs) in the heliosphere. The simulation model, where fast and slow solar wind streams interact with each other, allows the formation of a pair (forward/reverse) of shocks at the CIR boundaries and the stream interface interior, which prevents the interchange of both streams. While both shocks are quasi-perpendicular and are not capable of accelerating thermal particles (hundreds of eV) up to a suprathermal energy (tens to hundreds ofkeV) in the early phase of their development, the reverse shock in the fast wind experiences a transition to a quasi-parallel regime in the later phase. The quasi-parallel reverse shock can efficiently accelerate particles to the suprathermal range. The different timescale of the adiabatic expansion between the fast and slow wind leads to a transition of the shock geometry that can take place more easily in the reverse shock than in the forward shock, where the magnetic field in the fast wind remains more radial to the propagation direction than in the slow wind. The difference in the acceleration efficiency between these shocks follows a well-known observed asymmetry in the profile of the energetic particle fluxes, where the larger intensity increases more in the reverse shock than in the forward shock. The present results suggest that the solar wind thermal plasma, as well as interstellar pickup ions, can contribute to the composition of energetic particles associated with the CIRs. © 2011. The American Astronomical Society. All rights reserved.

Masuda N.,University of Tokyo | Klemm K.,University of Leipzig | Eguiluz V.M.,Institute Fisica Interdisciplinar y Sistemas Complejos IFISC CSIC UIB
Physical Review Letters | Year: 2013

Interactions among units in complex systems occur in a specific sequential order, thus affecting the flow of information, the propagation of diseases, and general dynamical processes. We investigate the Laplacian spectrum of temporal networks and compare it with that of the corresponding aggregate network. First, we show that the spectrum of the ensemble average of a temporal network has identical eigenmodes but smaller eigenvalues than the aggregate networks. In large networks without edge condensation, the expected temporal dynamics is a time-rescaled version of the aggregate dynamics. Even for single sequential realizations, diffusive dynamics is slower in temporal networks. These discrepancies are due to the noncommutability of interactions. We illustrate our analytical findings using a simple temporal motif, larger network models, and real temporal networks. Published by American Physical Society.

Ezawa M.,University of Tokyo
Physical Review Letters | Year: 2016

A honeycomb structure has a natural extension to three dimensions. Simple examples are hyperhoneycomb and stripy-honeycomb lattices, which are realized in β-Li2IrO3 and γ-Li2IrO3, respectively. We propose a wide class of three-dimensional (3D) honeycomb lattices which are loop-nodal semimetals. Their edge states have intriguing properties similar to the two-dimensional honeycomb lattice in spite of a dimensional difference. Partial flat bands emerge at the zigzag or bearded edge of the 3D honeycomb lattice, whose boundary is given by the Fermi loop in the bulk spectrum. On the other hand, perfect flat bands emerge in the zigzag-bearded edge or when the anisotropy is large. The loop-nodal structure is destroyed once staggered potential or antiferromagnetic order is introduced. All these 3D honeycomb lattices become strong topological insulators with the inclusion of the spin-orbit interaction (SOI). Furthermore, point-nodal semimetals may be realized in the presence of both antiferromagnetic order and the SOI. We construct the effective four-band theory with the SOI to understand the physics near the Fermi level, based upon which the density of states and the dc conductivity are calculated. © 2016 American Physical Society.

Steinhardt C.L.,University of Tokyo
Astrophysical Journal | Year: 2011

Recent work using virial mass estimates and the quasar mass-luminosity plane has yielded several new puzzles regarding quasar accretion, including a sub-Eddington boundary (SEB) on most quasar accretion, near-independence of the accretion rate from properties of the host galaxy, and a cosmic synchronization of accretion among black holes of a common mass. We consider how these puzzles might change if virial mass estimation turns out to have a systematic bias. As examples, we consider two recent claims of mass-dependent biases in Mg II masses. Under any such correction, the surprising cosmic synchronization of quasar accretion rates and independence from the host galaxy remain. The slope and location of the SEB are very sensitive to biases in virial mass estimation, and various mass calibrations appear to favor different possible physical explanations for feedback between the central black hole and its environment. The alternative mass estimators considered do not simply remove puzzling quasar behavior, but rather replace it with new puzzles that may be more difficult to solve than those using current virial mass estimators and the Shen etal. catalog. © 2011. The American Astronomical Society. All rights reserved.

Higaki T.,Keio University | Jeong K.S.,Pusan National University | Kitajima N.,Asia Pacific Center for Theoretical Physics | Takahashi F.,Tohoku University | Takahashi F.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We argue that the QCD axion can arise from many aligned axions with decay constants much smaller than the conventional axion window. If the typical decay constant is of O(100) GeV to 1 TeV, one or more of the axions or saxions may account for the recently found diphoton excess at ~750 GeV. Our scenario predicts many axions and saxions coupled to gluons with decay constants of order the weak scale, and therefore many collider signatures by heavy axions and saxions will show up at different energy scales. In particular, if the inferred broad decay width is due to multiple axions or saxions, a non-trivial peak structure may become evident when more data is collected. We also discuss cosmological implications of the aligned QCD axion scenario. In the Appendix we give a possible UV completion and argue that the high quality of the Peccei-Quinn symmetry is naturally explained in our scenario. © 2016 Published by Elsevier B.V.

Nakayama Y.,University of Tokyo
Physical Review Letters | Year: 2016

Given conformal data on a flat Euclidean space, we use crosscap conformal bootstrap equations to numerically solve the Lee-Yang model as well as the critical Ising model on a three dimensional real projective space. We check the rapid convergence of our bootstrap program in two dimensions from the exact solutions available. Based on the comparison, we estimate that our systematic error on the numerically solved one-point functions of the critical Ising model on a three dimensional real projective space is less than 1%. Our method opens up a novel way to solve conformal field theories on nontrivial geometries. © 2016 American Physical Society.

Han C.,University of Tokyo | Lee H.M.,Chung - Ang University | Park M.,Korea Basic Science Institute | Sanz V.,University of Sussex
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We consider the possibility of interpreting the recently reported diphoton excess at 750 GeV as a spin-two massive particle (such as a Kaluza-Klein graviton in warped extra-dimensions) which serves as a mediator to Dark Matter via its gravitational couplings to the dark sector and to the Standard Model (SM). We model non-universal couplings of the resonance to gauge bosons in the SM and to Dark Matter as a function on their localization in the extra dimension. We find that scalar, fermion or vector dark matter can saturate the dark matter relic density by the annihilation of dark matter into a pair of the SM particles or heavy resonances, in agreement with the diphoton resonance signal strength. We check the compatibility of our hypothesis with other searches for the KK graviton. We show that the invisible decay rate of the resonance into a pair of dark matter is subdominant in the region of the correct relic density, hence leading to no constraints from the mono-jet bound at 8 TeV via the gluon coupling. We also discuss the kinematic features of the decay products of a KK graviton to distinguish the KK graviton from the SM backgrounds or a scalar particle interpretation of the diphoton resonance. © 2016 The Authors.

We examined nitrification in the euphotic zone, its impact on the nitrogen cycles, and the controlling factors along a 7500 km transect from the equatorial Pacific Ocean to the Arctic Ocean. Ammonia oxidation occurred in the euphotic zone at most of the stations. The gene and transcript abundances for ammonia oxidation indicated that the shallow clade archaea were the major ammonia oxidizers throughout the study regions. Ammonia oxidation accounted for up to 87.4% (average 55.6%) of the rate of nitrate assimilation in the subtropical oligotrophic region. However, in the shallow Bering and Chukchi sea shelves (bottom ⩽67 m), the percentage was small (0–4.74%) because ammonia oxidation and the abundance of ammonia oxidizers were low, the light environment being one possible explanation for the low activity. With the exception of the shallow bottom stations, depth-integrated ammonia oxidation was positively correlated with depth-integrated primary production. Ammonia oxidation was low in the high-nutrient low-chlorophyll subarctic region and high in the Bering Sea Green Belt, and primary production in both was influenced by micronutrient supply. An ammonium kinetics experiment demonstrated that ammonia oxidation did not increase significantly with the addition of 31–1560 nm ammonium at most stations except in the Bering Sea Green Belt. Thus, the relationship between ammonia oxidation and primary production does not simply indicate that ammonia oxidation increased with ammonium supply through decomposition of organic matter produced by primary production but that ammonia oxidation might also be controlled by micronutrient availability as with primary production.The ISME Journal advance online publication, 26 February 2016; doi:10.1038/ismej.2016.18. © 2016 International Society for Microbial Ecology

Suetsugu S.,University of Tokyo | Gautreau A.,French National Center for Scientific Research
Trends in Cell Biology | Year: 2012

Cell and organelle shape can profoundly influence proper cellular function. In recent years, two machineries have emerged as major regulators of membrane shape: Bin-Amphiphysin-Rvs161/167 (BAR) domain-containing proteins, which induce membrane invaginations or protrusions, and nucleation promoting factors (NPFs), which activate the Arp2/3 complex and are thus responsible for the generation of branched actin networks that push on membranes. Several BAR-NPF interactions have been shown to induce various types of protrusions, such as lamellipodia or filopodia, or invaginations, including trafficking organelles such as caveolae, endosomes and clathrin-coated pits (CCPs). This review focuses on how collaboration between these two interacting machineries, which emerges as a unified mechanism of membrane remodeling, accounts for such a variety of membrane shapes. © 2012 Elsevier Ltd.

The vertebrate gonadotrophin-releasing hormone (GnRH) neurones are considered to consist of one group of hypothalamic neuroendocrine and two groups of extrahypothalamic neuromodulatory GnRH neurones, and each group of neurones expresses different molecular species of GnRH peptide. Different GnRH peptides are produced by one of the three paralogous GnRH genes, gnrh1, gnrh2 and gnrh3, which are considered to have originated from gene duplications. All three GnRH systems are well developed in teleost brains. By taking advantage of this, and especially the use of GnRH-green fluoresecent protein transgenic fish, the anatomical and electrophysiological properties of all three types of GnRH neurones can now be studied. The hypophysiotropic GnRH1 neurones in the preoptic area show episodic spontaneous electrical activities, whereas the extrahypothalamic GnRH2 neurones in the midbrain and GnRH3 neurones in the terminal nerve show regular intrinsic pacemaker activities. It is suggested that these different electrophysiological properties are related to their different functions (i.e. GnRH1 neurones act as hypophysiotropic neuroendocrine regulators and GnRH2 and GnRH3 neurones act as neuromodulators). The present review focuses on recent electrophysiological analyses of GnRH3 neurones, which have revealed the excitatory GABAergic and the inhibitory FMRFamide-like peptidergic regulations acting upon them, as well as gap junctional electrotonic coupling. © 2010 The Author. Journal Compilation © 2010 Blackwell Publishing Ltd.

Yoshizaki A.,University of Tokyo
Journal of Dermatology | Year: 2016

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive extracellular matrix deposition in the skin and visceral organs with an autoimmune background. Although the pathogenic relationship between systemic autoimmunity and the clinical manifestations remains unknown, SSc patients have immunological abnormalities including the production of disease-specific autoantibodies. Recent studies have demonstrated that B cells play a crucial role in systemic autoimmunity and disease expression via various functions in addition to autoantibody production. Recent studies show that B cells from SSc patients demonstrate an upregulated CD19 signaling pathway, which is a crucial regulator of B-cell activation, that induces SSc-specific autoantibody production in SSc. In addition, B cells from SSc patients exhibit an overexpression of CD19. Consistently, in CD19 transgenic mice, CD19 overexpression induces SSc-specific autoantibody production. SSc patients have also intrinsic B-cell abnormalities characterized by chronic hyperreactivity of memory B cells, possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a genetic model of SSc, show augmented CD19 signaling and chronic hyperreactivity. Furthermore, in bleomycin-induced SSc model mice, endogenous ligands for Toll-like receptors, induced by bleomycin treatment, stimulate B cells to produce various fibrogenic cytokines and autoantibodies. Remarkably, CD19 loss results in inhibition of B-cell hyperreactivity and elimination of autoantibody production, which is associated with improvement of fibrosis. Taken together, altered B-cell function may result in tissue fibrosis, as well as autoimmunity, in SSc. Although further studies and greater understanding are needed, B cells are potential therapeutic target in SSc. © 2016 Japanese Dermatological Association.

Background Lysophosphatidylcholine (LPC) has been implicated in the onset of transfusion-related acute lung injury (TRALI). In plasma, LPC is converted to lysophosphatidic acid (LPA) by autotaxin (ATX). The effect of leukoreduction in the accumulation of these bioactive lipids and ATX in human autologous blood has not been fully investigated. Study Design and Methods The accumulation of choline-containing phospholipids (LPC, sphingomyelin [SM], and phosphatidylcholine [PC]), LPA, and ATX during the storage of autologous blood and the changes caused by leukoreduction were investigated. A total of 26 orthopedic patients were enrolled. Autologous blood was collected as whole blood and, after leukoreduction, preserved refrigerated until use. Prestorage leukoreduced (LR) and non-LR autologous blood samples were analyzed. The time-dependent changes and the effect of the filtration were compared. Results A time-dependent and significant increase in the levels of LPA was observed in both non-LR and LR samples. The concentration of LPA was significantly reduced in LR compared to non-LR samples. The concentration of LPC was higher in LR compared to non-LR samples. The levels of PC, SM, and ATX were not affected by either the storage period or the leukoreduction. Conclusions Leukoreduction of autologous whole blood effectively reduced the accumulation of LPA. On the other hand, prestorage leukoreduction resulted in an increased concentration of LPC, without significantly affecting ATX. Further studies are necessary to confirm the role of LPA in the pathogenesis of adverse effects of blood transfusion, especially TRALI. © 2013 American Association of Blood Banks.

Hotate K.,University of Tokyo
Optical Fiber Technology | Year: 2013

Fiber distributed Brillouin sensing is discussed, focusing mainly on optical correlation domain techniques. By synthesizing a delta-function like optical coherence function between pump and probe lightwave traveling along an optical fiber in opposite directions, which is realized by modulating laser source frequency by an appropriate waveform, stimulated Brillouin scattering can be selectively excited at one specific position along the fiber. The selected position can easily be swept by changing the modulation frequency, so the distributed measurement can be achieved. In the system, Brillouin Optical Correlation Domain Analysis (BOCDA), the position to be measured can be selected randomly along the fiber, which is a special feature of the system. Spatial resolution of 1.6 mm and measurement speed of 1000 samples/s have already been demonstrated. With a similar way, distribution of spontaneous Brillouin scattering can also be measured along the fiber. Spatial resolution of 10 mm and measurement speed of 50 samples/s have already been demonstrated in the system, Brillouin Optical Correlation Domain Reflectometry (BOCDR). Brillouin dynamic grating (BDG), which is acoustic-wave generated refractive-index grating caused in the stimulated Brillouin scattering process, was found to cause a Bragg reflection for the orthogonally polarized lightwave in an polarization maintaining fiber. By measuring both the BDG and the Brillouin scattering, discriminative distributed measurement of strain and temperature has been realized by the BOCDA scheme with a 10 mm spatial resolution. © 2013 Elsevier Inc. All rights reserved.

The overwhelming amount of network data in functional genomics is making its visualization cluttered with jumbling nodes and edges. Such cluttered network visualization, which is known as "hair-balls", is significantly hindering data interpretation and analysis of researchers. Effective navigation approaches that can always abstract network data properly and present them insightfully are hence required, to help researchers interpret the data and acquire knowledge efficiently. Cytoscape is a de facto standard platform for network visualization and analysis, which has many users around the world. Apart from its core sophisticated features, it easily allows for extension of the functionalities by loading extra plug-ins. We developed NaviClusterCS, which enables researchers to interactively navigate large biological networks of ~100,000 nodes in a "Google Maps-like" manner in the Cytoscape environment. NaviClusterCS rapidly and automatically identifies biologically meaningful clusters in large networks, e.g., proteins sharing similar biological functions in protein-protein interaction networks. Then, it displays not all nodes but only preferable numbers of those clusters at any magnification to avoid creating the cluttered network visualization, while its zooming and re-centering functions still enable researchers to interactively analyze the networks in detail. Its application to a real Arabidopsis co-expression network dataset illustrated a practical use of the tool for suggesting knowledge that is hidden in large biological networks and difficult to be obtained using other visualization methods. NaviClusterCS provides interactive and multi-scale network navigation to a wide range of biologists in the big data era, via the de facto standard platform for network visualization. It can be freely downloaded at http://navicluster.cb.k.u-tokyo.ac.jp/cs/ and installed as a plug-in of Cytoscape.

Okabe S.,University of Tokyo
Advances in Experimental Medicine and Biology | Year: 2012

Molecular dynamics of synapses are one of the most important factors that control the remodeling of synaptic connection and efficacy of transmission. This chapter focuses on the dynamics of postsynaptic molecular machinery and describes the imaging technologies important for quantitative analyses of synapses, their application to the postsynaptic molecules, and the insights obtained from these analyses. New visualization techniques, such as super-resolution microscopy, will become an indispensable approach to reveal submicron changes of synaptic molecules. New methods of monitoring protein interactions will also be integrated with experimental paradigms of synaptic plasticity. Cell biological analyses, together with cutting-edge imaging technologies, have been applied to the studies of nascent synapse formation, synapse maintenance, and activity-dependent synapse remodeling. From these studies, a variety of new concepts emerged, such as local assembly of postsynaptic scaffolds, presence of "transport packets" of postsynaptic receptors, heterogeneity of actin movement within spines, and activity-free fluctuation of PSD/spine sizes. These new concepts are useful in understanding specific properties of postsynaptic functions and should be integrated in future to build a realistic model of the postsynaptic organization that can explain its remarkable stability and tunability. © 2012 Springer-Verlag/WIen.

Okayama H.,University of Tokyo
Cellular Signalling | Year: 2012

Virtually all the cells constituting solid organs in adult animals require anchorage to the extracellular matrix for their proliferation and survival. When deprived of anchorage, those cells arrest in G1 phase of the cell cycle and die of apoptosis known as anoikis. However, if malignantly transformed, cells no longer require such an anchorage to proliferate and survive, and it is generally thought that the acquirement of this ability underlies the tumorigenic and metastatic capability of malignant cells. Therefore, for the past two decades, great efforts have been devoted to uncovering the nature of the anchorage signal and the mechanism by which this signal controls the G1-S transition in the cell cycle with little progress. However, several critical findings were recently made on anchorage signaling and the control of the cell cycle and cell death by this signaling. This review focuses on the newly emerging understanding and perspective of this highly important cell cycle and cell death regulation. © 2012 Elsevier Inc.

Watada S.,University of Tokyo
Geophysical Research Letters | Year: 2013

Tsunami speed variations in the deep ocean caused by seawater density stratification is investigated using a newly developed propagator matrix method that is applicable to seawater with depth-variable sound speeds and density gradients. For a 4 km deep ocean, the total tsunami speed reduction is 0.44% compared with incompressible homogeneous seawater; two thirds of the reduction is due to elastic energy stored in the water and one third is due to water density stratification mainly by hydrostatic compression. Tsunami speeds are computed for global ocean density and sound speed profiles, and characteristic structures are discussed. Tsunami speed reductions are proportional to ocean depth with small variations, except in warm Mediterranean seas. The impacts of seawater compressibility and the elasticity effect of the solid earth on tsunami traveltime should be included for precise modeling of transoceanic tsunamis. © 2013. American Geophysical Union. All Rights Reserved.

De Felice A.,Kyoto University | Mukohyama S.,Kyoto University | Mukohyama S.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We propose a new theory of massive gravity with only two propagating degrees of freedom. While the homogeneous and isotropic background cosmology and the tensor linear perturbations around it are described by exactly the same equations as those in the de Rham-Gabadadze-Tolley (dRGT) massive gravity, the scalar and vector gravitational degrees of freedom are absent in the new theory at the fully nonlinear level. Hence the new theory provides a stable nonlinear completion of the self-accelerating cosmological solution that was originally found in the dRGT theory. The cosmological solution in the other branch, often called the normal branch, is also rendered stable in the new theory and, for the first time, makes it possible to realize an effective equation-of-state parameter different from (either larger or smaller than) -1 without introducing any extra degrees of freedom. © 2015 The Authors.

Cato S.,University of Tokyo
Environmental and Resource Economics | Year: 2010

The purpose of this paper is to investigate optimal schemes for refunding the emission tax in a free-entry market where the production process generates emissions. We consider the regulation by a three-part tax policy: the government sets an emission tax, a refunding scheme, and an entry-license tax. In contrast to the case of the two-part tax-refund policy under no entry, we show that even if it is impossible to obtain subsidies from outside, the first-best outcome is always attained. Further, the government's budget constraint is binding under the optimal schemes. Our result implies that the tax-refund system works effectively in a market with endogenous entry. © 2010 Springer Science+Business Media B.V.

Ieki K.,University of Tokyo
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2016

The MEG experiment searches for the muon lepton flavor violating decay, μ+→e+γ. An upgrade of the experiment is ongoing, aiming at reaching a sensitivity of Br(μ+→e+γ)=4×10-14, an order of magnitude better than the sensitivity of the current MEG. To achieve this goal, all of the detectors are being upgraded. In MEG, the energy, position and timing of the gamma ray were measured by a liquid Xe calorimeter, which consists of 900 l of liquid Xe and 846 2-in. round-shaped photo-multiplier tubes (PMTs). In the upgrade, the granularity at the gamma ray incident face will be improved by replacing 216 PMTs with 4092 SiPMs (MPPCs) with an active area of 12×12 mm2 each. The energy resolution for the gamma ray is expected to improve by a factor of 2, because the efficiency to collect scintillation light will become more uniform. The position resolution is also expected to improve by a factor of 2. In collaboration with Hamamatsu Photonics K.K., we have successfully developed a high performance MPPC for our detector. It has excellent photon detection efficiency for the liquid xenon scintillation light in VUV range. The size of the chips is large so that it can cover large area with a manageable number of readout channels. The characteristics of the MPPCs are being tested in liquid Xe, and also at the room temperature. The results of the tests will be presented, together with the expected performance of the upgraded detector. © 2015 Elsevier B.V. All rights reserved.

Nagase M.,University of Tokyo
Clinical and Experimental Nephrology | Year: 2010

Recent clinical and experimental studies have shown that aldosterone is a potent inducer of proteinuria and that mineralocorticoid receptor (MR) antagonists confer efficient antiproteinuric effects. We identified glomerular epithelial cells (podocytes) as novel targets of aldosterone; activation of MR injures podocytes possibly via oxidative stress, resulting in disruption of glomerular filtration barrier, proteinuria, and progression of chronic kidney disease. We also demonstrated that SHR/cp, a rat model of metabolic syndrome, was susceptible to podocyte injury and proteinuria. Aldosterone excess caused by adipocyte-derived aldosterone-releasing factors was suggested to underlie the nephropathy. High salt intake augmented MR activation in the kidney and exacerbated the nephropathy. Furthermore, we identified an alternative pathway of MR activation by small GTPase Rac1. Rho- GDIa knockout mice, a model with Rac1 activation in the kidney, showed albuminuria, podocyte injury, and glomerulosclerosis. Renal injury in the knockout mice was accompanied by enhanced MR signaling in the kidney despite normoaldosteronemia, and was ameliorated by an MR antagonist, eplerenone. Moreover, Rac-specific inhibitor significantly reduced the nephropathy, concomitantly with repression of MR activation. In vitro transfection studies provided direct evidence of Rac1-mediated MR activation. In conclusion, our findings suggest that MR activation plays a pivotal role in the pathogenesis of chronic kidney disease in metabolic syndrome, and that MR may be activated both aldosterone dependently (via aldosterone-releasing factors) and independently (via Rac1). MR antagonists are promising antiproteinuric drugs in metabolic syndrome, although long-term effects on renal outcomes, mortality, and safety need to be established. © Japanese Society of Nephrology 2010.

Nakano A.,University of Tokyo | Nakano A.,RIKEN | Luini A.,Telethon Institute of Genetics and Medicine
Current Opinion in Cell Biology | Year: 2010

There are, in theory, several ways in which proteins may pass through the Golgi apparatus. Among these, the cisternal progression-maturation mode has gained broad consensus. However, there remain questions regarding the molecular mechanisms by which resident proteins are sorted from cargo and move backward to the proximal cisterna in synchrony with cisternal progression. In this short review, we discuss current questions about the organisation of trafficking to, through, and out of the Golgi apparatus, as well as the main approaches being developed to address such questions in model organisms including yeast, mammals and plants. © 2010 Elsevier Ltd.

The ichnogenus Phymatoderma is a subhorizontal branching burrow system consisting of radiating tunnels filled with fecal pellets. This ichnogenus has been interpreted as a product of a deposit-feeding animal, but the question of whether the Phymatoderma-producer was a subsurface deposit feeder or a surface deposit feeder is still a topic of controversy. Herein I present evidence, based on carbon-isotope analyses, for the formation of the trace fossil Phymatoderma granulata occurring in the lower Toarcian black shale in southern Germany. Carbon-isotope ratios of organic carbon (δ 13C org) in the pelletal infill of P. granulata, the surrounding black shale, and the overlying gray mudstone are -26.64±0.42 (2σ) ‰, -28.49±0.44 (2σ) ‰, and -26.27±0.13 (2σ) ‰, respectively. The difference between the pelletal infill and overlying mudstone in terms of δ 13C org is much smaller than that between the fillings and black shale; therefore, these data clearly indicate that the Phymatoderma-producer ingested the surface sediments and subsequently excreted fecal pellets into the subsurface sediments. Such a surface deposit-feeding style would be an especially effective means of absorbing nutrients, because surface sediments contain much fresh organic material, whereas organic matter in subsurface deposits consists mostly of refractory material that is poorly utilized by most marine benthos. © 2012 Elsevier B.V.

Ide S.,University of Tokyo
Nature Geoscience | Year: 2013

Maximum earthquake magnitude and the rate of seismic activity apparently differ among subduction zones. This variation is attributed to factors such as subduction zone temperature and stress, and the type of material being subducted. The relative velocity between the downgoing and overriding plates controls their tectonic deformation. It is also thought to correlate with seismicity. Here I use the epidemic type aftershock sequence model to calculate the background seismicity rate-the frequency of seismic events above magnitude 4.5-for 117 sections of subduction zones worldwide, during the past century. I demonstrate a proportionality relationship whereby relative plate velocity correlates positively with seismicity rate. This relationship is prominent in the southwestern Pacific Ocean. However, although seismically active, this region has not experienced a magnitude 9 earthquake since 1900. In contrast, the Cascadia, Nankai, southern Chilean and Alaskan subduction zones exhibit low background seismicity rates, yet have experienced magnitude 9 earthquakes in the past century. Slow slip occurs in many of these regions, implying that slow deformation may aid nucleation of very large earthquakes. The proportionality relationship could be used to assess the seismic risk between two endmembers: active subduction zones that generate moderate earthquakes and quiet subduction zones that generate extremely large earthquakes. © 2013 Macmillan Publishers Limited. All rights reserved.

Watanabe H.,University of California at Berkeley | Oshikawa M.,University of Tokyo
Physical Review Letters | Year: 2015

In analogy with crystalline solids around us, Wilczek recently proposed the idea of "time crystals" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state or in the canonical ensemble of a general Hamiltonian, which consists of not-too-long-range interactions. © 2015 American Physical Society.

Spannowsky M.,Durham University | Stoll M.,University of Tokyo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Heavy resonances are an integral part of many extensions of the standard model. The discovery of such heavy resonances are a primary goal at the LHC and future hadron colliders. When a particle with TeV-scale mass decays into electroweak-scale objects, these objects are highly boosted and their decay products are then strongly collimated, possibly to an extent that they cannot be resolved in the calorimeters of the detectors any more. We develop taggers for electroweak-scale resonances by combining the good energy resolution of the hadronic calorimeter with the superior spatial resolution of the tracking detector. Using track-based techniques we reconstruct heavy W′ and Z′ bosons and constrain the branching ratio of the rare Higgs boson decay H→ZA→l+l- jets. The taggers show a good momentum-independent performance up to very large boosts. Using the proposed techniques will allow experiments at the LHC and a future hadron collider to significantly extend its reach in searches for heavy resonances. © 2015 American Physical Society. © 2015 American Physical Society.

Kato Y.,RIKEN | Kato Y.,University of Tokyo | Onoda S.,RIKEN
Physical Review Letters | Year: 2015

Unbiased quantum Monte Carlo simulations are performed on the nearest-neighbor spin-12 pyrochlore XXZ model with an antiferromagnetic longitudinal and the weak ferromagnetic transverse exchange couplings, J and J. The specific heat exhibits a broad peak at TCSI∼0.2J associated with a crossover to a classical Coulomb liquid regime showing a suppressed spin-ice monopole density, a broadened pinch-point singularity, and the Pauling entropy for |J|J, as in classical spin ice. On further cooling, the entropy restarts decaying for J>Jc∼-0.104J, producing another broad specific heat peak for a crossover to a bosonic quantum Coulomb liquid, where the spin correlation contains both photon and quantum spin-ice monopole contributions. With negatively increasing J across Jc, a first-order thermal phase transition occurs from the quantum Coulomb liquid to an XY ferromagnet. Relevance to magnetic rare-earth pyrochlore oxides is discussed. © 2015 American Physical Society.

Fukushima K.,University of Tokyo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

To address a question of whether the chiral magnetic current is a static polarization or a genuine flow of charged particles, we elucidate the numerical formulation to simulate the net production of right-handed particles and anomalous currents with CP-breaking background fields which cause an imbalance between particles and antiparticles. For a concrete demonstration we numerically impose pulsed electric and magnetic fields to confirm our answer to the question that the produced net particles flow in the dynamical chiral magnetic effect. The rate for the particle production and the chiral magnetic current generation is quantitatively consistent with the axial anomaly, while they appear with a finite response time. We emphasize the importance to quantify the response time that would suppress observable effects of the anomalous current. © 2015 American Physical Society.

Ezawa M.,University of Tokyo
Physical Review Letters | Year: 2015

We investigate the realization of a topological superconductor in a generic bucked honeycomb system equipped with four types of mass-generating terms, where the superconductor gap is introduced by attaching the honeycomb system to an s-wave superconductor. Constructing the topological phase diagram, we show that Majorana modes are formed in the phase boundary. In particular, we analyze the honeycomb system with antiferromagnetic order in the presence of perpendicular electric field Ez. It becomes topological for |Ez|>Ezcr and trivial for |Ez|

Ikeda H.,Kyoto University | Suzuki M.-T.,Japan Atomic Energy Agency | Arita R.,University of Tokyo | Takimoto T.,Pohang University of Science and Technology | And 2 more authors.
Nature Physics | Year: 2012

Exotic electronic states resulting from entangled spin and orbital degrees of freedom are hallmarks of strongly correlated f-electron systems. A spectacular example is the so-called hidden-order (HO) phase transition in the heavy-electron metal URu 2Si 2, which is characterized by the huge amount of entropy lost at T HO =17.5K (refs 2,3). However, no evidence of magnetic/structural phase transition has been found below T HO so far. The origin of the HO phase transition has been a long-standing mystery in condensed-matter physics. Here, on the basis of a first-principles theoretical approach, we examine the complete set of multipole correlations allowed in this material. The results uncover that the HO parameter is a rank-5 multipole (dotriacontapole) order with nematic E - symmetry, which exhibits staggered pseudospin moments along the [110] direction. This naturally provides comprehensive explanations of all key features in the HO phase including anisotropic magnetic excitations, the nearly degenerate antiferromagnetic-ordered state and spontaneous rotational-symmetry breaking. © 2012 Macmillan Publishers Limited. All rights reserved.

Ezawa M.,University of Tokyo
New Journal of Physics | Year: 2012

Silicene is a monolayer of silicon atoms forming a two-dimensional (2D) honeycomb lattice and shares almost all the remarkable properties of graphene. The low-energy structure of silicene is described by Dirac electrons with relatively large spin-orbit interactions owing to its buckled structure. A key observation is that the band structure can be controlled by applying an electric field to a silicene sheet. In particular, the gap closes at a certain critical electric field. Examining the band structure of a silicene nanoribbon, we show that a topological phase transition occurs from a topological insulator to a band insulator with an increase of electric field. We also show that it is possible to generate helical zero modes anywhere in a silicene sheet by adjusting the electric field locally to this critical value. The region may act as a quantum wire or a quantum dot surrounded by topological and/or band insulators. We explicitly construct the wave functions for some simple geometries based on the lowenergy effective Dirac theory. These results are also applicable to germanene, which is a 2D honeycomb structure of germanium. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Nakayama Y.,University of Tokyo
Nuclear Physics B | Year: 2012

It is logically possible that the trace anomaly in four dimensions includes the Hirzebruch-Pontryagin density in CP-violating theories. Although the term vanishes at free conformal fixed points, we realize such a possibility in the holographic renormalization group and show that it is indeed possible. The Hirzebruch-Pontryagin term in the trace anomaly may serve as a barometer to understand how much CP is violated in conformal field theories. © 2012 Elsevier B.V.

Sugimoto S.,University of Tokyo
Progress of Theoretical Physics | Year: 2012

We discuss an attempt to understand confinement and dynamical symmetry breaking in a 4-dimensional non-supersymmetric gauge theory using S-duality in type IIB string theory. The electric theory is a USp(2n) gauge theory and its magnetic dual is argued to be an SO(2n) or SO(2n-1) gauge theory. These theories are obtained as the low-energy effective theory of O3-D3̄ systems in type IIB string theory, which are related by S-duality. Confinement and dynamical symmetry breaking in the USp(2n) gauge theory are caused by the condensation of scalar fields in the magnetic dual description, which is consistent with the scenario of the dual Meissner mechanism for the confinement. Copyright © Progress of Theoretical Physics 2012.

Nakayama Y.,University of Tokyo
General Relativity and Gravitation | Year: 2012

From the holographic renormalization group viewpoint, while the scale transformation plays a primary role in holographic dualities by providing the extra dimension, the special conformal transformation seems to only play a secondary role. We, however, claim that the space-time diffeomorphism is crucially related to the latter. For its demonstration, we study the holographic renormalization group flow of a foliation preserving diffeomorphic theory of gravity (a. k. a. space-time flipped Horava gravity). We find that the dual field theory, if any, is only scale invariant but not conformal invariant. In particular, we show that the holographic trace anomaly in four dimension predicts the Ricci scalar squared term that would be incompatible with the Wess-Zumino consistency condition if it were conformal. This illustrates how the foliation preserving diffeomorphic theory of gravity could be in conflict with a theorem of the dual unitary quantum field theory. © 2012 Springer Science+Business Media, LLC.

Ogawa S.,University of Tokyo
International Journal of Hematology | Year: 2012

Myelodysplastic syndromes (MDS) and related myeloid neoplasms are a heterogeneous group of myeloid neoplasms, which frequently terminate in acute myeloid leukemia (AML). During the past decade, a number of gene mutations have been identified in MDS. However, the spectrum of these mutations overlaps largely with that in AML, complicating the understanding of MDS-specific pathogenesis that discriminates MDS from AML. Recently, several groups reported frequent mutations of multiple components of the RNA splicing machinery in MDS and related disorders. Largely specific to myelodysplastic phenotypes, these splicing factor mutations provide a potential clue to better understanding of the pathogenesis of MDS. © The Japanese Society of Hematology 2012.

Sasaki T.,University of Tokyo
Nature protocols | Year: 2012

Understanding the physiology of axons in the central nervous system requires experimental access to intact axons. This protocol describes how to perform cell-attached recordings from narrow axon fibers (φ <1 μm) in acute and cultured brain slice preparations (with a success rate of ∼50%). By using fluorophore-coated glass pipettes and Nipkow disk confocal microscopy, fluorescently labeled axons can be visually targeted under online optical control. In the cell-attached configuration, axonal action potentials are extracellularly recorded as unit-like, sharp negative currents. The axon morphology labeling and cell-attached recordings of axons can be completed within 1-2 h. The recordings are stable for at least 30 min.

Hato E.,University of Tokyo
Transportation Research Part C: Emerging Technologies | Year: 2010

This study attempts to develop a small, portable travel-activity measuring instrument that requires no entry from respondents. Conventional surveys have collected identification information such as facility type, transport mode, and activity content through the operation of instruments, questionnaires, etc. However, these complicated surveys burden the respondents and rely on their memory, often leading to recording omissions or incorrect records. We propose a method for estimating behavioral contexts using BCALs (Behavioral Context Addressable Loggers in the Shell), a wearable, behavioral context information-measuring instrument, for re-estimating label information such as facility type and transport mode from ecological and environmental sensors based on learning models. The numerical values observed by these sensors differed greatly among locations or means of transportation, revealing the high possibility of automatic identification of locations and means of transportation using BCALs. © 2009 Elsevier Ltd. All rights reserved.

Tanaka H.,University of Tokyo
Faraday Discussions | Year: 2012

Phase separation is a fundamental phenomenon that produces spatially heterogeneous patterns in soft matter and foods. We argue that phase separation in these materials generally belongs to "viscoelastic phase separation", where the morphology is determined by the mechanical balance of not only the thermodynamic force (interface tension) but also the viscoelastic force. The origin of the viscoelastic force is dynamic asymmetry between the components of a mixture, which can be caused by either a size disparity or a difference in the glass transition temperature between the components. Such dynamic asymmetry quite often exists in foods, which are typically mixtures of big molecules (polymers, proteins, etc.) and liquids (water, oil, etc.). We show examples of mechanically driven pattern formation in foods, in which dynamic asymmetry plays crucial roles, including the formation of network and cellular patterns in foods (e.g., breads, sponge cakes, butter, chocolates, etc.) and crack pattern formation (dried foods, cooked meat, etc.). Collapsing of these structures upon heating or moisture uptake is also discussed. We also argue that heterogeneous gels are in general formed as a consequence of dynamical arrest of the viscoelastic phase separation. Finally we mention an intimate link of viscoelastic phase separation, where deformation fields are spontaneously generated by phase separation itself, to mechanical instability and fracture induced by externally imposed strain fields. Such mechanical instability and nonlinear rheology may be relevant to food processing and also to separation and fracture of foods. We propose that all these phenomena can be understood as mechanically driven inhomogeneization with the concept of dynamic asymmetry in a unified manner. © 2012 The Royal Society of Chemistry.

The Golgi apparatus forms stacks of cisternae in many eukaryotic cells. However, little is known about how such a stacked structure is formed and maintained. To address this question, plant cells provide a system suitable for live-imaging approaches because individual Golgi stacks are well separated in the cytoplasm. We established tobacco BY-2 cell lines expressing multiple Golgi markers tagged by different fluorescent proteins and observed their responses to brefeldin A (BFA) treatment and BFA removal. BFA treatment disrupted cis, medial, and trans cisternae but caused distinct relocalization patterns depending on the proteins examined. Medial- and trans-Golgi proteins, as well as one cis-Golgi protein, were absorbed into the endoplasmic reticulum (ER), but two other cis-Golgi proteins formed small punctate structures. After BFA removal, these puncta coalesced first, and then the Golgi stacks regenerated from them in the cis-to-trans order. We suggest that these structures have a property similar to the ER-Golgi intermediate compartment and function as the scaffold of Golgi regeneration.

Koike K.,University of Tokyo
Recent Results in Cancer Research | Year: 2014

Persistent infection with hepatitis C virus (HCV) is a major risk toward development of hepatocellular carcinoma (HCC). However, it remains controversial in the pathogenesis of HCC associated with HCV whether the virus plays a direct or an indirect role. The observation that chronic hepatitis C patients with sustained high levels of serum alanine aminotransferase are prone to develop HCC suggests the significance of inflammation in hepatocarcinogenesis in hepatitis C. However, the rare development of HCC in patients with autoimmune hepatitis, which is accompanied by robust inflammation, even after the progress into cirrhosis, implies a possibility of the direct role of HCV in HCC development. What is the role of HCV, a simple plus-stranded RNA virus, whose genome is never integrated into the host genome, in hepatocarcinogenesis? The studies using transgenic mouse and cultured cell models, in which the HCV proteins are expressed, indicate the direct pathogenicity of HCV, including oncogenic activities. In particular, the core protein of HCV induces overproduction of oxidative stress by impairing the mitochondrial electron transfer system, through insulting the function of molecular chaperon, prohibitin. HCV also modulates the intracellular signaling pathways including mitogen-activated protein kinase, leading to the acquisition of growth advantage by hepatocytes. In addition, HCV induces disorders in lipid and glucose metabolisms, thereby accelerating the progression of liver fibrosis and HCC development. These results would provide a clue for further understanding of the role of HCV in pathogenesis of persistent HCV infection including hepatocarcinogenesis. © 2014 Springer-Verlag Berlin Heidelberg.

Beroza G.C.,Stanford University | Ide S.,University of Tokyo
Annual Review of Earth and Planetary Sciences | Year: 2011

Nonvolcanic tremor is observed in close association with geodetically observed slow-slip events in subduction zones. Accumulating evidence points to these events as members of a family of slow earthquakes that occur as shear slip on the downdip extensions of fault zones in a regime that is transitional between a frictionally locked region above and a freely slipping region below. By virtue of their locations and their properties, slow earthquakes are certain to provide new insights into the behavior of earthquakes and faulting and into the hazard they embody. Copyright © 2011 by Annual Reviews. All rights reserved.

Oka A.,University of Tokyo
Nature communications | Year: 2013

Vertical mixing in the ocean is a key driver of the global ocean thermohaline circulation, one of the most important factors controlling past and future climate change. Prior observational and theoretical studies have focused on intense tidal mixing near the sea bottom (near-field mixing). However, ocean general circulation models that employ a parameterization of near-field mixing significantly underestimate the strength of the Pacific thermohaline circulation. Here we demonstrate that tidally induced mixing away from the sea bottom (far-field mixing) is essential in controlling the Pacific thermohaline circulation. Via the addition of far-field mixing to a widely used tidal parameterization, we successfully simulate the Pacific thermohaline circulation. We also propose that far-field mixing is indispensable for explaining the presence of the world ocean's oldest water in the eastern North Pacific Ocean. Our findings suggest that far-field mixing controls ventilation of the deep Pacific Ocean, a process important for ocean carbon and biogeochemical cycles.

Wariki W.M.,University of Tokyo
Cochrane database of systematic reviews (Online) | Year: 2012

Various interventions have been adopted to reduce HIV transmission among sex workers and their clients but the effectiveness of these strategies has yet to be investigated using meta-analytic techniques. To evaluate the effectiveness of behavioral interventions to reduce the transmission of HIV infection among sex workers and their clients in low- and middle-income countries. The Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane HIV/AIDS group specialized register, the Cochrane Database of Systematic Reviews, MEDLINE, PsycINFO, Sociological Abstracts, CINAHL, Dissertation Abstract International (DAI), EMBASE, LILACS, BIOSIS, SciSearch, INDMED, Proquest, and various South Asian abstracting databases were included in the database list. The publication sites of the World Health Organization, the US Centers for Disease Control and Prevention, and other international research and non-governmental organizations also appeared in the database list. Randomized controlled trials (RCTs) and quasi-RCTs examining the effects on HIV transmission risk of different behavioral interventions or comparing behavioral interventions with no intervention, where described any one of the outcome measures, such as HIV incidence and prevalence, STI incidence and prevalence, change in self-reported of condom use, and other HIV-related outcome. Two authors independently assessed trials, extracted data and assessed the risk bias. Heterogeneity amongst trials was also tested. A total of 13 trials with 8,698 participants were included. Primary outcomes (HIV and STI prevalence and incidence) were reported in seven trials. Of these, HIV incidence was reported in only three trials. After a 6-month follow-up assessment, there was no evidence that social cognitive behavioral intervention was effective in reducing HIV incidence (RR 0.12, 95% CI 0.01 to 2.22). However, there was a reduction in HIV incidence at 3-month follow-up assessment of promotion of female and male condom (RR 0.07, 95% CI 0.00 to 1.38). Social cognitive interventions and promotion of female and male condom use were significantly reduced STIs incidence (RR 0.57, 95% CI 0.34 to 0.96) and (RR 0.63, 95% CI 0.45 to 0.88), respectively. Secondary outcomes were identified in 13 trials. Meta-analyses showed evidence that interventions to promote the use of female and male condoms do reduce non-condom use (RR 0.83, 95% CI 0.65 to 1.05) compared to promotion of male condoms alone, and that social cognitive interventions reduced drug use among sex workers (RR 0.65, 95% CI 0.36 to 1.16) compared to standard care. Available evidence nevertheless suggests that compared with standard care or no intervention, behavioral interventions are effective in reducing HIV and the incidence of STIs amongst female sex workers (FSWs). Given the benefits of social cognitive theory and the promotion of condom use in reducing HIV/STI and the public health need to control transmission amongst FSWs, there is a clear finding in favour of behavioral interventions. However, it should be recognized that there is a lack of information about most other outcomes and target populations, and that all of the trials were conducted in low- and middle-income countries.

Suzuki Y.,University of Tokyo
IEEJ Transactions on Electrical and Electronic Engineering | Year: 2011

Energy harvesting is a method by which energy naturally present in the environment is captured and then converted into electricity for use in low-power electronics. Among the various energy sources, structural vibration is believed to be useful for powering wireless sensors in various applications such as sensor network and structural health monitoring. In the present paper, after a brief introduction to electret materials and charging technologies, recent progress in microelectromechanical systems (MEMS) electret generators is reviewed. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Nasu J.,Tokyo Institute of Technology | Motome Y.,University of Tokyo
Physical Review Letters | Year: 2015

Thermodynamic properties of chiral spin liquids are investigated for a variant of the Kitaev model defined on a decorated honeycomb lattice. Using the quantum Monte Carlo simulation, we find that the model exhibits a finite-temperature phase transition associated with the time reversal symmetry breaking, in both topologically trivial and nontrivial regions. Numerical results for the Chern number and the thermal Hall conductivity indicate that the phase transition changes from a continuous to a discontinuous transition as we vary the coupling constants to reach the non-Abelian phase coming from the Abelian phase of the model. In addition, we find as a diagnostic of the chiral spin liquids, successive crossovers with multistage entropy release above the critical temperature, which indicates that the hierarchical fractionalization of a quantum spin occurs differently between the two regions. © 2015 American Physical Society. © 2015 American Physical Society.

Ezawa M.,University of Tokyo
Journal of the Physical Society of Japan | Year: 2015

We report the recent progress on the theoretical aspects of monolayer topological insulators including silicene, germanene and stanene, which are monolayer honeycomb structures of silicon, germanium and tin, respectively. They show quantum spin Hall effects in nature due to the spin-orbit interaction. The band gap can be tuned by applying perpendicular electric field, which induces a topological phase transition. We also analyze the topological properties of generic honeycomb systems together with the classification of topological insulators. Phase diagrams of topological insulators and superconductors in honeycomb systems are explicitly determined. We also investigate topological electronics including a topological field-effect transistor, the topological Kirchhoff's law and the topological spin-valleytronics. © 2015 The Physical Society of Japan.

Inflammation is induced in the heart during the development of cardiac hypertrophy. The initiating mechanisms and the role of inflammation in cardiac hypertrophy, however, remain unclear. Toll-like receptor-2 (TLR2) recognizes endogenous molecules that induce noninfectious inflammation. Here, we examined the role of TLR2-mediated inflammation in cardiac hypertrophy. At 2 weeks after transverse aortic constriction, Tlr2(-/-) mice showed reduced cardiac hypertrophy and fibrosis with greater left ventricular dilatation and impaired systolic function compared with wild-type mice, which indicated impaired cardiac adaptation in Tlr2(-/-) mice. Bone marrow transplantation experiment revealed that TLR2 expressed in the heart, but not in bone marrow-derived cells, is important for cardiac adaptive response to pressure overload. In vitro experiments demonstrated that TLR2 signaling can induce cardiomyocyte hypertrophy and fibroblast and vascular endothelial cell proliferation through nuclear factor-κB activation and interleukin-1β upregulation. Systemic administration of a nuclear factor-κB inhibitor or anti-interleukin-1β antibodies to wild-type mice resulted in impaired adaptive cardiac hypertrophy after transverse aortic constriction. We also found that heat shock protein 70, which was increased in murine plasma after transverse aortic constriction, can activate TLR2 signaling in vitro and in vivo. Systemic administration of anti-heat shock protein 70 antibodies to wild-type mice impaired adaptive cardiac hypertrophy after transverse aortic constriction. Our results demonstrate that TLR2-mediated inflammation induced by extracellularly released heat shock protein 70 is essential for adaptive cardiac hypertrophy in response to pressure overload. Thus, modulation of TLR2 signaling in the heart may provide a novel strategy for treating heart failure due to inadequate adaptation to hemodynamic stress.

Angular momentum transport and particle acceleration during the magnetorotational instability (MRI) in a collisionless accretion disk are investigated using three-dimensional particle-in-cell simulation. We show that the kinetic MRI can provide not only high-energy particle acceleration but also enhancement of angular momentum transport. We find that the plasma pressure anisotropy inside the channel flow with p?>p? induced by active magnetic reconnection suppresses the onset of subsequent reconnection, which, in turn, leads to high-magnetic-field saturation and enhancement of the Maxwell stress tensor of angular momentum transport. Meanwhile, during the quiescent stage of reconnection, the plasma isotropization progresses in the channel flow and the anisotropic plasma with p?>p? due to the dynamo action of MRI outside the channel flow contribute to rapid reconnection and strong particle acceleration. This efficient particle acceleration and enhanced angular momentum transport in a collisionless accretion disk may explain the origin of high-energy particles observed around massive black holes. © 2015 American Physical Society.

Tanizaki Y.,University of Tokyo | Tanizaki Y.,RIKEN
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Zero-dimensional O(n)-symmetric sigma models are studied using the Picard-Lefschetz integration method in the presence of small symmetry-breaking perturbations. Because of approximate symmetry, downward flows turn out to show significant structures: They slowly travel along the set of pseudoclassical points, and branch into other directions so as to span middle-dimensional integration cycles. We propose an efficient way to find such slow motions for computing Lefschetz thimbles. In the limit of symmetry restoration, we figure out that only special combinations of Lefschetz thimbles can survive as convergent integration cycles: Other integrations become divergent due to noncompactness of the complexified group of symmetry. We also compute downward flows of O(2)-symmetric fermionic systems, and confirm that all of these properties are true also with fermions. © 2015 American Physical Society.

Matsumoto H.,University of Tokyo
BMC genomics | Year: 2013

Haplotype information is useful for various genetic analyses, including genome-wide association studies. Determining haplotypes experimentally is difficult and there are several computational approaches that infer haplotypes from genomic data. Among such approaches, single individual haplotyping or haplotype assembly, which infers two haplotypes of an individual from aligned sequence fragments, has been attracting considerable attention. To avoid incorrect results in downstream analyses, it is important not only to assemble haplotypes as long as possible but also to provide means to extract highly reliable haplotype regions. Although there are several efficient algorithms for solving haplotype assembly, there are no efficient method that allow for extracting the regions assembled with high confidence. We develop a probabilistic model, called MixSIH, for solving the haplotype assembly problem. The model has two mixture components representing two haplotypes. Based on the optimized model, a quality score is defined, which we call the 'minimum connectivity' (MC) score, for each segment in the haplotype assembly. Because existing accuracy measures for haplotype assembly are designed to compare the efficiency between the algorithms and are not suitable for evaluating the quality of the set of partially assembled haplotype segments, we develop an accuracy measure based on the pairwise consistency and evaluate the accuracy on the simulation and real data. By using the MC scores, our algorithm can extract highly accurate haplotype segments. We also show evidence that an existing experimental dataset contains chimeric read fragments derived from different haplotypes, which significantly degrade the quality of assembled haplotypes. We develop a novel method for solving the haplotype assembly problem. We also define the quality score which is based on our model and indicates the accuracy of the haplotypes segments. In our evaluation, MixSIH has successfully extracted reliable haplotype segments. The C++ source code of MixSIH is available at https://sites.google.com/site/hmatsu1226/software/mixsih.

Quach J.Q.,University of Tokyo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Goncalves et al. [Phys. Rev. D 75, 124023 (2007)] derived a nonrelativistic limit of the generalized Dirac Hamiltonian in the presence of a gravitational wave, using the exact Foldy-Wouthuysen transformation. This gave rise to the intriguing notion that spin precession may occur even in the absence of a magnetic field. We argue that this effect is not physical as it is the result of a gauge-variant term that was an artifact of a flawed application of the exact Foldy-Wouthuysen transformation. In this paper we derive the correct nonrelativistic limit of the generalized Dirac Hamiltonian in the presence of a gravitational wave, using both the exact and standard Foldy-Wouthuysen transformation. We show that both transformations consistently produce a Hamiltonian where all terms are gauge invariant. Unfortunately however, we also show that this means the novel spin-precession effect does not exist. © 2015 American Physical Society.

Kato T.,RIKEN | Iwamoto K.,University of Tokyo
Neuropharmacology | Year: 2014

Covalent modifications of nucleotides, such as methylation or hydroxymethylation of cytosine, regulate gene expression. Early environmental risk factors play a role in mental disorders in adulthood. This may be in part mediated by epigenetic DNA modifications. Methods for comprehensive analysis of DNA methylation and hydroxymethylation include DNA modification methods such as bisulfite sequencing, or collection of methylated, hydroxymethylated, or unmethylated DNA by specific binding proteins, antibodies, or restriction enzymes, followed by sequencing or microarray analysis. Results from these experiments should be interpreted with caution because each method gives different result. Cytosine hydroxymethylation has different effects on gene expression than cytosine methylation; methylation of CpG islands is associated with lower gene expression, whereas hydroxymethylation in intragenic regions is associated with higher gene expression. The role of hydroxymethylcytosine is of particular interest in mental disorders because the modification is enriched in the brain and synapse related genes, and it exhibits dynamic regulation during development. Many DNA methylation patterns are conserved across species, but there are also human specific signatures. Comprehensive analysis of DNA methylation shows characteristic changes associated with tissues, brain regions, cell types, and developmental states. Thus, differences in DNA methylation status between tissues, brain regions, cell types, and developmental stages should be considered when the role of DNA methylation in mental disorders is studied. Several disease-associated changes in methylation have been reported: hypermethylation of SOX10 in schizophrenia, hypomethylation of HCG9 (HLA complex group 9) in bipolar disorder, hypermethylation of PRIMA1, hypermethylation of SLC6A4 (serotonin transporter) in bipolar disorder, and hypomethylation of ST6GALNAC1 in bipolar disorder. These findings need to be replicated in different patient populations to be generalized. Further studies including animal experiments are necessary to understand the roles of DNA methylation in mental disorders. This article is part of the Special Issue entitled 'Neuroepigenetic Disorders'. © 2013 Elsevier Ltd. All rights reserved.

Otsuki K.,University of Tokyo
Environment and Planning D: Society and Space | Year: 2012

It is often argued that various forms of illegality persist in the Brazilian Amazon because of weak frontier governance. However, very little is understood about how this governance can be strengthened in the context of social and spatial change in a way that will counter illegality. Drawing on the concept of heterotopias, as discussed by Michel Foucault, and the life history of an illegal logger in an agrarian reform settlement project in the state of Pará, this paper approaches frontier governance by conceptualising the 'settlement heterotopia' as a real, lived-in place in which the space that makes up various state and nonstate actors' sites of action interact and continually rearrange power relations. This rearrangement process may or may not work to legitimise illegality and, therefore, strengthening frontier governance involves a process by which collaborative power relations emerge and residents decide to work with the state instead of alongside illegality. © 2012 Pion and its Licensors.

Haga T.,University of Tokyo
Journal of biochemistry | Year: 2014

This article summarizes molecular properties of the high-affinity choline transporter (CHT1) with reference to the historical background focusing studies performed in laboratories of the author. CHT1 is present on the presynaptic terminal of cholinergic neurons, and takes up choline which is the precursor of acetylcholine. The Na(+)-dependent uptake of choline by CHT1 is the rate-limiting step for synthesis of acetylcholine. CHT1 is the integral membrane protein with 13 transmembrane segments, belongs to the Na(+)/glucose co-transporter family (SLC5), and has 20-25% homology with members of this family. A single nucleotide polymorphism (SNP) for human CHT1 has been identified, which has a replacement from isoleucine to valine in the third transmembrane segment and shows the choline uptake activity of 50-60% as much as that of wild-type CHT1. The proportion of this SNP is high among Asians. Possible importance of choline diet for those with this SNP was discussed. © The Authors 2014. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Obara K.,University of Tokyo
Geophysical Research Letters | Year: 2012

The transient stress change caused by the passage of surface waves resulting from the 26 December 2004 Sumatra-Andaman earthquake triggered seismic tremor in two regions in Hokkaido, in the northernmost part of the Japanese islands, where tectonic tremor associated with the subducting plate has not previously been detected. The amplitude pattern of the tremor envelope in both regions is characterized by a periodic enhancement at an interval of about 20s, which correlates with the surface wave. One tremor that was triggered in central Hokkaido at a depth of around 10-20km coincides with active seismicity linked to previously known, deep low-frequency microearthquakes related to volcanic activity. Another tremor occurred in northernmost Hokkaido, where there are no known active faults, volcanoes, or microearthquake seismicity. If the source of the northern tremor is located near the ground surface, it would be possible that the tremor is related to fluid pressure change, because the periodic enhancement of tremor amplitude is in phase with the largest compressional strain caused by surface waves. © 2012. American Geophysical Union. All Rights Reserved.

Valentine S.V.,University of Tokyo
Renewable and Sustainable Energy Reviews | Year: 2013

This paper aims to advance research into the effectiveness of policies for encouraging technological transition in the energy sector (in general) and wind power (in particular). It contends that the ineffectiveness of wind power development policy in most nations stems from a linear approach to policy design that is unsuited to complex adaptive markets. The paper argues that in complex adaptive markets, policies are required that foster competition on a level playing field. Insights are extracted from complexity theory to advance four principles for effective wind power policy in such markets. These principles include establishing policy initiatives to: encourage technological diversity, establish clear and progressive short to medium-term targets, enhance environmental monitoring systems and establish a malleable policy regime that directly resolves emergent challenges while simultaneously sustaining market momentum to ensure long-term targets are met. In order to demonstrate the applied relevance of these principles, the paper applies these concepts to a historical analysis of Denmark's wind power development policies. © 2012 Elsevier Ltd.

Sugawara-Narutaki A.,University of Tokyo
Polymer Journal | Year: 2013

It is increasingly important that we learn how to fabricate materials in environmentally friendly ways using common resources that are abundant in nature. Biomineralization, the process by which living organisms create a variety of sophisticated composites, such as bone and shell, is an ideal model for such fabrication. This article reviews recent progress toward the synthesis of polymer-inorganic composite materials inspired by biomineralization. In particular, three reaction systems are focused upon: (1) polymer-calcium carbonate thin film composites synthesized by interaction among insoluble polymer, soluble acidic polymer, and inorganic ions, (2) polymer nanogel-calcium phosphate composite nanoparticles synthesized on scaffolds of hydrogel nanoparticles and (3) colloidal silica nanoparticles made to self-assemble into anisotropic chain-like structures by interaction with block copolymers. All these reaction systems involve aqueous environments at ambient temperature and pressure. © 2013 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Tani H.,Japan National Institute of Advanced Industrial Science and Technology | Akimitsu N.,University of Tokyo
RNA Biology | Year: 2012

Changing the abundance of transcripts by regulated RNA degradation is a critical step in the control of various biological pathways. Recently, genome-wide inhibitor-free technologies for determining RNA stabilities in mammalian cells have been developed. In these methods, endogenous RNAs are pulse labeled by uridine analogs [e.g., 4-thiouridine (4sU), 5-etyniluridine (EU) and 5'-bromo-uridine (BrU)], followed by purification of labeled de novo RNAs. These technologies have revealed that the specific half-life of each mRNA is closely related to its physiological function. Genes with short-lived mRNAs are significantly enriched among regulatory genes, while genes with long-lived mRNAs are enriched among housekeeping genes. This review describes the recent progress of experimental procedures for measuring RNA stability. © 2012 Landes Bioscience.

Ikeda T.,University of Tokyo
Cell structure and function | Year: 2010

Nucleoside diphosphate (NDP) kinase is an enzyme that synthesizes the nucleoside triphosphates. In mammals, nine sequences (NDK1-NDK9) have been found with domain(s) homologous to the catalytic domain of NDP kinase, and some of them have been shown to associate with sperm flagella. The present study examines the localization of NDK7, for which little information has been available. Database analysis showed that the NDK7 gene is present in organisms with cilia and flagella. Western blotting analyses of various mouse tissues consistently indicated that NDK7 is preferentially expressed in tissues with motile cilia as well as in sperm. Immunofluorescence microscopy revealed that this protein is localized along the entire length of the TritonX-100-insoluble fraction of sperm flagella, possibly in the axonemes. Unexpectedly, however, NDK7 in tracheal epithelia was found in the cell body but not in cilia. Finally, in vitro co-sedimentation assays using recombinant proteins showed that both mouse and Chlamydomonas NDK7 directly bind to microtubules.

Yokoyama H.,University of Tokyo
Polymer Journal | Year: 2013

Recently, closed cellular and open porous structures on the nanometer scale have been attracting much attention. Our group has developed a novel method for producing such nanocellular and nanoporous structures using a block copolymer as a template and supercritical carbon dioxide. Small angle X-ray scattering (SAXS) has an important role in characterizing nanocells and nanopores. In particular, grazing incidence SAXS reveals embedded nanocellular and nanoporous structures in thin films. In addition, SAXS can be used for in situ measurements to study the process of nanocellular and nanoporous formation in supercritical carbon dioxide. In this focused review, our recent progress on nanocellular and nanoporous fabrication and the use of SAXS techniques to characterize such structures will be presented. © 2013 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Ohba M.,Japan Central Research Institute of Electric Power Industry | Watanabe M.,University of Tokyo
Journal of Climate | Year: 2012

Warm and cold phases of El Niño-Southern Oscillation (ENSO) exhibit a significant asymmetry in their transition/duration such that El Niño tends to shift rapidly to La Niña after the mature phase, whereas La Niña tends to persist for up to 2 yr. The possible role of sea surface temperature (SST) anomalies in the Indian Ocean (IO) in this ENSO asymmetry is investigated using a coupled general circulation model (CGCM). Decoupled-IO experiments are conducted to assess asymmetric IO feedbacks to the ongoingENSOevolution in the Pacific. Identical-twin forecast experiments show that a coupling of the IO extends the skillful prediction of the ENSO warm phase by about one year, which was about 8 months in the absence of the IO coupling, in which a significant drop of the prediction skill around the boreal spring (known as the spring prediction barrier) is found. The effect of IO coupling on the predictability of the Pacific SST is significantly weaker in the decay phase of La Niña. Warm IO SST anomalies associated with El Niño enhance surface easterlies over the equatorial western Pacific and hence facilitate the El Niño decay. However, this mechanism cannot be applied to cold IO SST anomalies during La Niña. The result of these CGCM experiments estimates that approximately one-half of theENSO asymmetry arises from the phase-dependent nature of the Indo-Pacific interbasin coupling. © 2012 American Meteorological Society.

It iswell known that the statistical probability of earthquake occurrence changes over the course of a day due to periodic variations in the tidal stress acting on faults. However, periodicity on a decadal scale has been studied by relatively few researchers. It has been reported that an approximately 10-yr periodicity is observed globally for the seismicity of M-8-class large earthquakes. However, the mechanism underlying this periodicity has not yet been revealed. In this study, the decadal-scale periodicity of earthquakes along the Japan Trench is investigated. A new finding is presented that in northeast Japan, the probability of the occurrence of historical earthquakes with an M ≥ 6 that have occurred during the past 1000 yr has increased approximately every 9 yr. Periodicity becomes even more apparent for large earthquakes with an M > 7.5 and approximately half the recorded events intensively occurred within two successive years on a cycle of approximately 9 yr. This implies the presence of a periodic stress disturbance at an appreciably regular interval. The past strain and tilt observations conducted in Japan during the 1950s through the 1970s indicate that, nationwide, gradual compression repeated every 8-10 yr in the direction of relative plate motion. These compression periods are in accordance with the periods of higher seismic activity discussed above. As a first step in investigating the origin of earthquake periodicity, periods associated with lunar motion are considered. It is shown that long-term motion primarily governed by the period of the lunar perigee is synchronized with the cyclic variation in seismicity and crustal deformation described above. Decadal changes in tidal stress, as calculated using an ordinary theory of solid Earth tides, are too small to cause periodic variations in seismicity. Therefore, the conditions by which tidal stress is sufficiently amplified to trigger an earthquake are investigated. The results show that, if one assumes that a tidal force acts on a spherically asymmetric blocklike upper mantle beneath the Pacific Plate, the computed phase and amplitude can explain the observations. Otherwise, it is difficult to consider direct tidal force alone as the main source of periodic variations in seismicity. Other possibilities should be considered, such as unknown interactions between the plate boundaries and the ocean/atmosphere with a period of approximately 9 yr or a resonance between the period of the tidal force and a recurrence period of slow slip events in the transition zone on the plate boundary. Apart from understanding the origin, the important fact confirmed in this study is that in some areas, the occurrence of large earthquakes, if considered as a group, appears to be strongly governed by a periodic stress disturbance rather than by completely random processes. Elucidating the wide-range approximately 9-yr mode helps us narrow a range in occurrence time in a probabilistic midterm prediction of large interplate earthquakes. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Takeuchi N.,University of Tokyo
Earth and Planetary Science Letters | Year: 2012

Waveform tomography is conducted for SH velocity structures of the entire mantle using approximately 3.5 times the data used for obtaining the previous model, SH18CE. The resultant new model, SH18CEX, exhibits a cluster of ridge-like low-velocity anomalies in the western part of the Pacific Large Low-Shear-Velocity Province (LLSVP). The location of the ridge-like anomalies is in good agreement with the location of the abrupt change in the topography of the D″ discontinuity. These results suggest that the LLSVP is associated with a cluster of ridge-like-piles, rather than a single large pile spread over the entire region. The piles probably consist of intrinsically dense material; however, either their volume or density contrast may not be sufficiently large to develop large-scale domes. © 2011 Elsevier B.V.

Hamba F.,University of Tokyo
Physics of Fluids | Year: 2011

Hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) is expected to accurately predict wall-bounded turbulent flows at high Reynolds numbers. It is known that extra terms due to the noncommutivity between the hybrid filter and the spatial derivative appear in the hybrid-filtered equations. In this paper the filtered Navier-Stokes equation is investigated using direct numerical simulation data of turbulent channel flow. In particular, the transport equations for the resolved and modeled energies are evaluated to examine the contribution of the extra terms. The RANS and LES regions are located by setting the width of the hybrid filter varying from the grid spacing to the channel half width. In the first case the RANS region is located near the wall for wall modeling in LES. In the second case the RANS and LES regions are located upstream and downstream, respectively. The extra terms in the Navier-Stokes and continuity equations show fairly large values in the RANS/LES interface region in both cases. The extra terms for the convection and the turbulent diffusion represent the energy transfer from the modeled part to the resolved part. This energy transfer suggests that conventional hybrid simulations neglecting the extra terms may underpredict velocity fluctuations in the interface region, causing an insufficient momentum transport and velocity mismatch in channel flow. These results show that the effect of the extra terms should be taken into account in the filtered Navier-Stokes equation as well as in the turbulent-energy equation in hybrid simulations. © 2011 American Institute of Physics.

Fukushima K.,Kyoto University | Hatsuda T.,University of Tokyo
Reports on Progress in Physics | Year: 2011

The current status of theoretical studies on the quantum chromodynamics (QCD) phase diagram at finite temperature and baryon chemical potential is reviewed with special emphasis on the origin of various phases and their symmetry breaking patterns. Topics include quark deconfinement, chiral symmetry restoration, order of the phase transitions, QCD critical point(s), colour superconductivity, various inhomogeneous states and implications from QCD-like theories. © 2011 IOP Publishing Ltd.

Chikazoe J.,University of Tokyo
Current Opinion in Psychiatry | Year: 2010

Purpose of review Response inhibition is an essential executive function implemented by the prefrontal cortex. Performance of go/no-go tasks, which are frequently used to investigate response inhibition, recruits a variety of cognitive components besides response inhibition. This article reviews recent findings on the functional localization associated with go/no-go tasks. Recent findings Recent neuropsychological and neuroimaging studies have shown that the presupplementary motor area and ventrolateral prefrontal cortex are crucial for response inhibition and that various subregions of the prefrontal cortex make different contributions leading to successful response inhibition. In particular, functional dissociation has been identified in the right ventrolateral prefrontal cortex, which consists of at least three subregions: the posterior part of the inferior frontal gyrus, inferior frontal junction and inferior frontal gyrus/insula. Summary Neuropsychological studies provide strong evidence that separate subregions of the prefrontal cortex make critical contributions to specific cognitive components involved in response inhibition, whereas neuroimaging studies cannot provide direct evidence regarding the causality, but provide insights into functional localization with high spatial resolution. These methods contribute significantly to our understanding of how executive functions are implemented and should continue to do so into the future. © 2010 Wolters Kluwer Health π Lippincott Williams & Wilkins 0951-7367.

Honda S.,University of Tokyo
Geochemistry, Geophysics, Geosystems | Year: 2014

I analyze the seismic tomography around the Japanese Islands to elucidate the present slab morphology. A simple conversion from the high speed to the temperature anomaly is done based on the recent study of the conversion coefficient from the velocity to the thermal anomaly and on the study of the relation between the seismicity and the temperature in the slab. I find recognizable amount of cold temperature anomalies under the subducting slab. This suggests a rather continuous slab throughout the mantle consistent with the results of many recent numerical models. However, there still is a gap in the slab or diluted slab under the transition zone. To understand this, I construct a simple half-kinematic model of subduction zone in which a Byerlee's type yield stress and the depth independent yield stress are assumed. Taking into account the geologic history around the Japanese Islands, I find that the slab morphology similar to the tomographic image is obtained when the yield stress is O(100 MPa). The present study shows that the detailed studies of seismic tomography and the tectonic history of the surveyed area can provide the constraints on the slab dynamics. © 2014. American Geophysical Union. All Rights Reserved.

An elevated intraocular pressure (IOP) is one of the most important risk factors for the development of glaucoma, which causes progressive optic neuropathy. Lowering IOP is currently the only therapeutic approach to the treatment of glaucoma. Tafluprost, a novel prostaglandin analogue, was recently launched onto the market as an ocular hypotensive agent. Tafluprost is potent in its affinity for the prostanoid FP receptor and in its intraocular lowering efficacy. Moreover, it enhances the ocular hemodynamics and has neuroprotective effects. Clinical studies have demonstrated its efficacy at decreasing intraocular pressure in patients with open-angle glaucoma or ocular hypertension. © 2010 Aihara, publisher and licensee Dove Medical Press Ltd.

Hellerman S.,University of Tokyo
Journal of High Energy Physics | Year: 2011

We prove that every unitary two-dimensional conformal field theory (with no extended chiral algebra, and with c, c̃ > 1) contains a primary operator with dimension δ 1 that satisfies 0 < δ 1 < c+c̃/12 + 0.473695. Translated into gravitational language using the AdS 3/CFT 2 dictionary, our result proves rigorously that the lightest massive excitation in any theory of 3D matter and gravity with cosmological constant Λ < 0 can be no heavier than 1/(4G N)+o(√Λ-). In the flat-space approximation, this limiting mass is twice that of the lightest BTZ black hole. The derivation applies at finite central charge for the boundary CFT, and does not rely on an asymptotic expansion at large central charge. Neither does our proof rely on any special property of the CFT such as supersymmetry or holomorphic factorization, nor on any bulk interpretation in terms of string theory or semiclassical gravity. Our only assumptions are unitarity and modular invariance of the dual CFT. Our proof demonstrates for the first time that there exists a universal centerof- mass energy beyond which a theory of "pure" quantum gravity can never consistently be extended. © 2011 SISSA.

Balogun O.O.,University of Tokyo
Cochrane database of systematic reviews (Online) | Year: 2013

Female genital cutting (FGC) refers to all procedures that involve the partial or total removal of the external female genitalia, or other injury to the female genital organs for cultural or other non-therapeutic reasons. There are no known medical benefits to FGC, and it can be potentially dangerous for the health and psychological well-being of women and girls who are subjected to the practice resulting in short- and long-term complications. Health problems of significance associated with FGC faced by most women are maternal and neonatal mortality and morbidity, the need for assisted delivery and psychological distress. Under good clinical guidelines for caring for women who have undergone genital cutting, interventions could provide holistic care that is culturally sensitive and non-judgemental to improve outcomes and overall quality of life of women. This review focuses on key interventions carried out to improve outcome and overall quality of life in pregnant women who have undergone FGC. To evaluate the impact of interventions to improve all outcomes in pregnant women or women planning a pregnancy who have undergone genital cutting. The comparison group consisted of those who have undergone FGC but have not received any intervention. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 December 2012) and organisations engaged in projects regarding FGC. Randomised controlled trials (RCTs), cluster-randomised trials or quasi-RCTs with reported data comparing intervention outcomes among pregnant women or women planning a pregnancy who have undergone genital cutting compared with those who did not receive any intervention. We did not identify any RCTs, cluster-randomised trials or quasi-RCTs. There are no included studies. FGC research has focused mainly on observational studies to describe the social and cultural context of the practice, and we found no intervention trials conducted to improve outcomes for pregnant women presenting with complications of FGC. While RCTs will provide the most reliable evidence on the effectiveness of interventions, there remains the issue of what is considered ethically appropriate and the willingness of women to undergo randomisation on an issue that is enmeshed in cultural traditions and beliefs. Consequently, conducting such a study might be difficult.

The incorporation of polar functional groups into polyolefins can significantly alter the adhesion, barrier and surface properties, dyeability, printability, and compatibility of the resulting "functional polyolefin". Thus, the development of methods for the controlled synthesis of functional polyolefins from industrially relevant monomers holds the potential to expand the range of applications available to this already ubiquitous class of materials. In this Perspective, recent advances in transition-metal-catalyzed functional polyolefin synthesis will be reviewed. A common thread among the innovations discussed here is the perturbation of catalyst function by tailored design of the chelating ancillary ligand, aided in many cases by improved mechanistic understanding. Specific topics discussed here include rare examples of catalyst control over the regio- and stereochemistry of polar monomer insertion by phosphine-sulfonato palladium complexes (Drent-type), rate acceleration of insertion polymerization by binuclear cooperativity using salicylaldiminato nickel complexes (Grubbs-type), and formation of linear copolymers of ethylene and polar vinyl monomers using a cationic palladium catalyst ligated by a bisphosphine monoxide (BPMO) that contrasts the typical polymer microstructures formed by other cationic group 10 catalysts ligated by an α-diimine (Brookhart-type). © 2014 American Chemical Society.

Ueda K.,University of Tokyo
Asian Economic Policy Review | Year: 2013

In this paper, I investigate the causes of the recent sharp response of the yen and Japanese stock prices to the discussion of, and the subsequent implementation of bold monetary easing by the Bank of Japan as demanded by Prime Minister Abe. I present statistical evidence that the response of the two asset prices have indeed been unusually large relative to the past experience with nonconventional monetary policy (NCM) even after allowance is given for the rise in global economic activity and asset prices. I also point out that the rally has been led by speculative trading by foreign investors, while domestic investors have largely stayed on the sidelines. I discuss possible reasons for such foreign investor behavior. Simply put, the unprecedented political pressure raised hopes of the adoption of bold measures by the Bank of Japan. I discuss, however, the possibility that the room for further action by the Bank is quite limited apart from what might be called a targeted helicopter drop of money. I also point out the possibility that investor behavior may have not been based on economic fundamentals. The asset price volatility since April 2013 is interpreted in the light of such discussions. © 2013 Japan Center for Economic Research.

Kato N.,University of Tokyo
Journal of Geophysical Research: Solid Earth | Year: 2012

Numerical simulations are conducted to investigate the dependence of the static stress drop of earthquakes on the critical slip-weakening distance. A fault model in a two-dimensional elastic medium is used, in which a locked zone (asperity) is assumed to exist between creeping zones. The presence of such a zone is commonly assumed for plate boundaries that have relatively low seismic coupling. Shear stress is concentrated at the edges of the locked zone and seismic rupture occurs when the strain energy release by rupture extension becomes sufficiently large to overcome the fracture energy. The static stress drop is calculated by taking the ratio of the average seismic slip to the length of seismic slip zone for the simulated earthquakes in the model, using various values for the normal stress applied to the fault and the characteristic slip distance of a rate- and state-dependent friction law. The simulation results indicate that the static stress drop is proportional to the square root of the product of the critical slip-weakening distance and the normal stress, when the seismic rupture starts near an edge of the locked zone. In contrast, when the seismic rupture starts near the center of the locked zone, the static stress drop increases linearly with normal stress and is independent of the critical slip-weakening distance. These simulation results may explain the relatively small depth dependence, as well as the large scatter, in observations of the static stress drop. Copyright 2011 by the American Geophysical Union.

Kato N.,University of Tokyo
Earth and Planetary Science Letters | Year: 2012

Numerical simulations of recurrence of interplate earthquakes in a subduction zone are conducted using a rate- and state-dependent friction law to estimate the fracture energies at the rupture nucleation points. During an interseismic period, shear stress is concentrated near the downdip of the locked portion of the plate boundary, and seismic rupture initiates when the energy release rate by rupture extension exceeds the fracture energy. The simulation results indicate that the fracture energy is proportional to the square of the amount of slip in the deep aseismic zone during the preceding interseismic period. This suggests that the fracture energy at the nucleation point can be estimated from the recurrence interval of earthquakes and the relative plate velocity. The fracture energies at the rupture nucleation points of great (M w>8) Nankai earthquakes in southwestern Japan are estimated to be 0.1-1MJ/m 2, and that of the 2011 M w9 Tohoku-oki earthquake to be of the order of 10MJ/m 2. The results suggest that fracture energy tends to increase with earthquake magnitude. © 2012 Elsevier B.V.

Yokozeki T.,University of Tokyo
Composites Part A: Applied Science and Manufacturing | Year: 2011

The crack kink angle and the steady state crack location of the core crack in sandwich beams are predicted by using the analytical formulation of energy release rates associated with core cracking in a double cantilever sandwich beam. The predicted analytical results are compared with experimental results available in the literature. It is demonstrated that the present analysis is in good agreement with overall crack kinking behavior in foam core sandwich beams. Finally, the effect of residual thermal stresses in sandwich beams on crack kinking is discussed using the present analytical method. © 2011 Elsevier Ltd. All rights reserved.

Unimolecular isomerization and decomposition reactions of alkylperoxy (RO2), hydroperoxyalkyl (QOOH), and hydroperoxyalkylperoxy (O 2QOOH) radicals play important roles in the low-temperature oxidation of hydrocarbons. In this study, these reactions have been investigated by the CBS-QB3 quantum chemical method, and the variation of the rate parameters by the structural change of alkyl groups has been studied systematically for the rule-based construction of the low-temperature oxidation mechanisms of arbitrary noncyclic alkanes. The results can be well-interpreted in terms of the group additivity and the ring-strain effect of the cyclic transition states. To extract the important processes needed for the chemical kinetic modeling, the competing reaction channels were compared in detail by steady-state analysis with the high-pressure limiting rate constants. The importance of some reactions of O2QOOH radicals, which have not been considered in the previous modeling studies, such as the hydrogen exchange reactions between -OOH and -OO• groups and hydrogen shift reactions from non-OOH sites, is suggested. © 2011 American Chemical Society.

Todo T.,University of Tokyo
Advances in Experimental Medicine and Biology | Year: 2012

Conditionally replicating herpes simplex viruses Type 1 (HSV-1) are promising therapeutic agents for glioma. They can replicate in situ, spread and exhibit oncolytic activity via a direct cytocidal effect. In addition, specific antitumor immunity is effectively induced in the course of oncolytic activities. G47Δ is a genetically engineered HSV-1 with triple mutations that realized augmented viral replication in tumor cells, strong induction of antitumor immunity and enhanced safety in normal tissues. A clinical trial of G47Δ in patients with recurrent glioblastoma has started in 2009. One of the advantages of HSV-1 is its capacity to incorporate large and/or multiple transgenes within the viral genome. In preclinical studies, "arming" of an oncolytic HSV-1 with transgenes encoding immunomodulatory molecules, such as interleukin 12, has been shown to greatly augment the efficacy of oncolytic HSV-1 therapy. Oncolytic virus therapy using HSV-1 may be a useful treatment for glioma that can also function as an efficient in situ tumor vaccination. © 2012 Landes Bioscience and Springer Science+Business Media.

Itakura E.,Tokyo Medical and Dental University | Itakura E.,University of Cambridge | Kishi-Itakura C.,Tokyo Medical and Dental University | Mizushima N.,Tokyo Medical and Dental University | Mizushima N.,University of Tokyo
Cell | Year: 2012

The lysosome is a degradative organelle, and its fusion with other organelles is strictly regulated. In contrast to fusion with the late endosome, the mechanisms underlying autophagosome-lysosome fusion remain unknown. Here, we identify syntaxin 17 (Stx17) as the autophagosomal SNARE required for fusion with the endosome/lysosome. Stx17 localizes to the outer membrane of completed autophagosomes but not to the isolation membrane (unclosed intermediate structures); for this reason, the lysosome does not fuse with the isolation membrane. Stx17 interacts with SNAP-29 and the endosomal/lysosomal SNARE VAMP8. Depletion of Stx17 causes accumulation of autophagosomes without degradation. Stx17 has a unique C-terminal hairpin structure mediated by two tandem transmembrane domains containing glycine zipper-like motifs, which is essential for its association with the autophagosomal membrane. These findings reveal a mechanism by which the SNARE protein is available to the completed autophagosome. © 2012 Elsevier Inc.

We previously demonstrated that an alarm pheromone released from male donor Wistar rats evoked several physiological and behavioral responses in recipient rats. However, the pheromone effects on social behavior were not analyzed. In the present study, we examined whether the alarm pheromone affects sexual behavior in male or female rats. When a pair of male and female subjects was exposed to the alarm pheromone during sexual behavior, the ejaculation latency was elongated, the number of mounts was increased, and the hit rate (number of intromissions/number of mounts and intromissions) was decreased in the male subject. In contrast, female sexual behavior was not affected by the alarm pheromone. When we exposed only the male or female subject of the pair to the pheromone just before sexual behavior, the results were similar: the pheromone effects were evident in male, but not in female, subjects. In addition, when we pretreated with corticotropin-releasing factor (CRF) antagonist (CP-154526) before exposing the male subject to the alarm pheromone, the pheromone effects were attenuated in a dose-dependent manner. These results indicate that the alarm pheromone modifies male, but not female, components of sexual behavior and that CRF participates in the effects.

Inoue M.,University of Tokyo
Chemical Record | Year: 2011

Antillatoxin and polytheonamide B are cytotoxic non-ribosomal peptides, both isolated from marine sources. These molecules possess unique biological activities that relate to ion channel proteins. Antillatoxin binds and activates voltage-gated sodium channels, while polytheonamide mimics functions of an ion channel protein. The goal of this research program is to control the function and behavior of ion channels in a desired fashion by exploiting structural motifs of these natural products. In the opening phase of this program, we first developed general and efficient synthetic routes to antillatoxin and polytheonamide B. The strategies for the total syntheses were then applied to the preparation of structurally varied derivatives for studies of structure-function relationships, which resulted in deciphering important structural elements for the potent biological activities of these natural products. © 2011 The Chemical Society of Japan and Wiley-VCH, Weinheim.

Nonaka M.,University of Tokyo
Sub-Cellular Biochemistry | Year: 2014

The mammalian complement system constitutes a highly sophisticated body defense machinery comprising more than 30 components. Research into the evolutionary origin of the complement system has identified a primitive version composed of the central component C3 and two activation proteases Bf and MASP in cnidaria. This suggests that the complement system was established in the common ancestor of eumetazoa more than 500 million years ago. The original activation mechanism of the original complement system is believed to be close to the mammalian lectin and alternative activation pathways, and its main role seems to be opsonization and induction of inflammation. This primitive complement system has been retained by most deuterostomes without major change until the appearance of jawed vertebrates. At this stage, duplication of the C3, Bf and MASP genes as well as recruitment of membrane attack components added the classical and lytic pathways to the primitive complement system, converting it to the modern complement system. In contrast, the complement system was lost multiple times independently in the protostome lineage. © Springer Science+Business Media Dordrecht 2014.

Tachikawa Y.,University of Tokyo
Journal of High Energy Physics | Year: 2011

We study a duality of 5d maximally supersymmetric Yang-Mills on S 1, which exchanges the tower of Kaluza-Klein W-bosons and the tower of instantonic monopoles. This duality maps a non-simply-laced gauge theory to a simply-laced gauge theory twisted by an outer automorphism around S 1, and is closely related to the Langlands dual of affine Lie algebras. We also discuss how this S-duality is implemented in terms of 6d N = (2,0) theory. This is straightforward except for the 6d theory of type SU(2n + 1) with Z2 outerautomorphism twist, for which a few new properties are deduced. For example, this 6d theory, when reduced on an S1 with Z2 twist, gives 5d USp(2n) theory with nontrivial discrete 5d theta angle. © SISSA 2011.

Due to effective enhancement of the Coulomb coupling strength in the vacuum-suspended graphene, the system may turn from a semimetal into an insulator by the formation of a gap in the fermionic spectrum. This phenomenon is analogous to the spontaneous breaking of chiral symmetry in the strong-coupling relativistic field theories. We study this " chiral symmetry breaking" and associated collective excitations on graphene in the strong coupling regime by taking U(1) lattice gauge theory as an effective model for graphene. Both compact and non-compact formulations of the U(1) gauge action show chiral symmetry breaking with equal magnitude of the chiral condensate (exciton condensate) in the strong coupling limit, while they start to deviate from the next-to-leading order in the strong coupling expansion. Phase and amplitude fluctuations of the order parameter are also investigated: in particular, a mass formula for the pseudo-Nambu-Goldstone mode (π-exciton), which is analogous to Gell-Mann-Oakes-Renner relation for the pion in quantum chromodynamics (QCD), is derived from the axial Ward-Takahashi identity. To check the applicability of the effective field theory description, typical energy scales of fermionic and bosonic excitations are estimated by identifying the lattice spacing of the U(1) gauge theory with that of the original honeycomb lattice of graphene. © 2011 Elsevier Inc.

Tachikawa Y.,University of Tokyo
Journal of High Energy Physics | Year: 2011

We consider 6d N = (2, 0) theory on N M5-branes, together with a 4d defect labeled by a Young diagram Y specifying its global symmetry GY . A recent conjecture states that a compactification of this system leads to a 2d theory with W-algebra symmetry depending on Y . We provide a check of the conjecture by reproducing the level of the current subalgebra ĜY of this W-algebra from the property of the 4d defect. © SISSA 2011.

Takahashi R.,University of Tokyo
Plant signaling & behavior | Year: 2012

The P(1B)-type heavy metal ATPases (HMAs) are diverse in terms of tissue distribution, subcellular localization, and metal specificity. Functional studies of HMAs have shown that these transporters can be divided into two subgroups based on their metal-substrate specificity: a copper (Cu)/silver (Ag) group and a zinc (Zn)/cobalt (Co)/cadmium (Cd)/lead (Pb) group. Studies on Arabidopsis thaliana and metal hyperaccumulator plants indicate that HMAs play an important role in the translocation or detoxification of Zn and Cd in plants. Rice possesses nine HMA genes, of which OsHMA1-OsHMA3 belong to the Zn/Co/Cd/Pb subgroup. OsHMA2 plays an important role in root-to-shoot translocation of Zn and Cd, and participates in Zn and Cd transport to developing seeds in rice. OsHMA3 transports Cd and plays a role in the sequestration of Cd into vacuoles in root cells. Modification of the expression of these genes might be an effective approach for reducing the Cd concentration in rice grains.

The importance of the damage effect on dynamic earthquake slip behavior is clarified using the damage tensor variable. Dynamic mode II faults that are embedded in damage-inducing media are assumed to relate to damage effects. This study confirms that the rupture velocity for spontaneous fault tip growth in the damage medium is reduced, being slightly smaller than rupture velocities observed for classical elastic material. Inelastic energy loss resulting in damage is relatively small but nonnegligible to the accumulated fracture energy. Two framework parameters employed in this study determine microcrack orientations and modes of microcracks and provide information on deviations in microcrack distribution between isotropic and nonisotropic ones. Spatial microcrack distribution patterns in isotropic and homogeneous systems are strongly dependent on a parameter related to the damage creation criterion. When considering secondary faulting, two apparently different behaviors, pulverization and branch development, are understood in a single framework, which gives a new insight into fault zone formation. The present results show that damage effect must be treated as a tensor variable rather than a scalar one as employed in many previous studies. Copyright 2012 by the American Geophysical Union.

Yamada A.,University of Tokyo
MRS Bulletin | Year: 2014

Abundance is an important keyword in materials development. This is particularly the case for the energy storage sector, where materials themselves function as a storage host. The amount of materials is directly linked to the amount of energy stored in the device. In lithium (Li)-ion batteries, transition metal elements are necessary to accommodate a large number of electrons/holes in a reversible redox reaction. Iron, as the fourth most abundant element in the earth's crust, is an ideal redox center, but practical storage electrodes with Fe redox have long been the holy grail of the Li-ion battery since its commercialization in 1991. In this article, the history of replacing Co with Fe in Li-battery electrodes is briefly reviewed followed by recent technical achievements toward more sustainable batteries using Na+ as a guest ion, where the goal would be to discover a high voltage electrode material composed of Na and Fe without compromising the energy density. © 2014 Materials Research Society.

Maeda K.,University of Tokyo
Annals of Physics | Year: 2011

We study a many-body mixture of an equal number of bosons and two-component fermions with a strong contact attraction. In this system bosons and fermions can be paired into composite fermions. We construct a large N extension where both bosons and fermions have the extra large N degrees of freedom and the boson-fermion interaction is extended to a four-point contact interaction which is invariant under the O(N) group transformation, so that the composite fermions become singlet in terms of the O(N) group. It is shown that such O(N) singlet fields have controllable quantum fluctuations suppressed by 1/. N factors and yield a systematic 1/. N-expansion in terms of composite fermions. We derive an effective action described by composite fermions up to the next-to-leading-order terms in the large N expansion, and show that there can be the BCS superfluidity of composite fermions at sufficiently low temperatures. © 2010 Elsevier Inc.

Bambi C.,University of Tokyo
Journal of Cosmology and Astroparticle Physics | Year: 2011

There is robust observational evidence supporting the existence of 5-20 M⊙ compact bodies in X-ray binary systems and of 10 5-109 M⊙ bodies at the center of many galaxies. All these objects are commonly interpreted as black holes, even is there is no direct evidence that they have an event horizon. A fundamental limit for a black hole in 4-dimensional general relativity is the Kerr bound |a *| 1, where a* is the spin parameter. This is just the condition for the existence of the event horizon. The accretion process can spin a black hole up to a* 0.998 and some super-massive objects in galactic nuclei could be rapidly rotating black holes with spin parameter close to this limit. However, if these super-massive objects are not black holes, the Kerr bound does not hold and the accretion process can spin them up to a* > 1. In this paper, I consider compact bodies with non-Kerr quadrupole moment. I study the evolution of the spin parameter due to accretion and I find its equilibrium value. Future experiments like the gravitational wave detector LISA will be able to test if the super-massive objects at the center of galaxies are the black holes predicted by general relativity. If they are not black holes, some of them may be super-spinning objects with a* > 1. © 2011 IOP Publishing Ltd and SISSA.

Kuroda K.,University of Tokyo
International Journal of Modern Physics D | Year: 2011

LCGT is the large scale cryogenic gravitational wave telescope project in Japan in order to firstly detect gravitational waves. After the detection, the detector will be served as an astronomical tool to observe the Universe in collaborative observation with Advanced LIGO, GEO HF, Advanced Virgo and AIGO detectors. LCGT will contribute both the enterprise of detecting the gravitational wave events and the worldwide network for gravitational wave astronomy. This paper summarizes the status of LCGT. © 2011 World Scientific Publishing Company.

Kamal C.,Raja Ramanna Center for Advanced Technology | Ezawa M.,University of Tokyo
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

Recently, phosphorene, a monolayer honeycomb structure of black phosphorus, was experimentally manufactured and has attracted rapidly growing interest. Motivated by phosphorene, here we investigate the stability and electronic properties of the honeycomb structure of the arsenic system based on first-principles calculations. Two types of honeycomb structures, buckled and puckered, are found to be stable. We call them arsenenes, as in the case of phosphorene. We find that both buckled and puckered arsenenes possess indirect gaps. We show that the band gap of puckered and buckled arsenenes can be tuned by applying strain. The gap closing occurs at 6% strain for puckered arsenene, where the bond angles between the nearest neighbors become nearly equal. An indirect-to-direct gap transition occurs by applying strain. Specifically, 1% strain is enough to transform puckered arsenene into a direct-gap semiconductor. We note that a bulk form of arsenic called gray arsenic exists which can be used as a precursor for buckled arsenene. Our results will pave the way for applications to light-emitting diodes and solar cells. © 2015 American Physical Society.

Tsuji S.,University of Tokyo
Human Molecular Genetics | Year: 2010

During the past three decades, we have witnessed remarkable advances in our understanding of the molecular etiologies of hereditary neurodegenerative diseases, which have been accomplished by 'positional cloning' strategies. The discoveries of the causative genes for hereditary neurodegenerative diseases accelerated not only the studies on the pathophysiologic mechanisms of diseases, but also the studies for the development of disease-modifying therapies. Genome-wide association studies (GWAS) based on the 'common disease-common variants hypothesis' are currently undertaken to elucidate disease-relevant alleles. Although GWAS have successfully revealed numerous susceptibility genes for neurodegenerative diseases, odds ratios associated with risk alleles are generally low and account for only a small proportion of estimated heritability. Recent studies have revealed that the effect sizes of the disease-relevant alleles that are identified based on comprehensive resequencing of large data sets of Parkinson disease are substantially larger than those identified by GWAS. These findings strongly argue for the role of the 'common disease-multiple rare variants hypothesis' in sporadic neurodegenerative diseases. Given the rapidly improving technologies of next-generation sequencing next-generation sequencing (NGS), we expect that NGS will eventually enable us to identify all the variants in an individual's personal genome, in particular, clinically relevant alleles. Beyond this, whole genome resequencing is expected to bring a paradigm shift in clinical practice, where clinical practice including diagnosis and decision-making for appropriate therapeutic procedures is based on the 'personal genome'. The personal genome era is expected to be realized in the near future, and society needs to prepare for this new era. © The Author 2010. Published by Oxford University Press.

Takahashi F.,Tohoku University | Takahashi F.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We revisit a single-field new inflation model based on a discrete R symmetry. Interestingly, the inflaton dynamics naturally leads to a heavy gravitino of mass m3/2=O(1-100)TeV, which is consistent with the standard-model like Higgs boson of mass mh≃126GeV. However, the predicted spectral index ns≈0.94 is in tension with the Planck result, ns=0.9603±0.073. We show that the spectral index can be increased by allowing a small constant term in the superpotential during inflation. The required size of the constant is close to the largest allowed value for successful inflation, and it may be a result of a pressure toward larger values in the landscape. Alternatively, such constant term may arise in association with supersymmetry breaking required to cancel the negative cosmological constant from the inflaton sector. © 2013 Elsevier B.V.

Lin C.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

In this Letter, we propose a massive gravity theory with 5 degrees of freedom. The mass term is constructed by 3 Stückelberg scalar fields, which respects SO(3) symmetry in the fields' configuration. By the analysis on the linear cosmological perturbations, we found that such 5 d.o.f. are free from ghost instability, gradient instability, and tachyonic instability. © 2013 Elsevier B.V.

Kobayashi M.,University of Tokyo | Nitta M.,Keio University
Nuclear Physics B | Year: 2013

We study Hopfions in the Faddeev-Skyrme model with potential terms on R2×S1. Apart from the conventional Hopfions, there exist winding Hopfions, that is, the lump (baby Skyrmion) strings with the lump charge Q with the U(1) modulus twisted P times along S1, having the Hopf charge PQ. We consider two kinds of potential terms, that is, the potential linear in the field and the ferromagnetic potential with two easy axes, and present stable solutions numerically. We also point out that a Q-lump carries the unit Hopf charge per the period in d=2+1. © 2013 Elsevier B.V.

In Asia, evidence-based guidelines for the management of hepatocellular carcinoma (HCC) have evolved, including the option of liver transplantation. Because of the continuing serious organ shortage, however, living donor liver transplantation (LDLT) remains the mainstream in Japan. Unlike deceased donor transplantation, living donor transplantation is not always limited by the restrictions imposed by the nationwide organ allocation system. The decision for transplantation may depend on institutional or case-by-case considerations, balancing the will of the donor, the operative risk, and the overall survival benefit. Cumulative data from the Japanese national multicenter registry analysis as well as individual center experiences suggest further expanding the criteria for LDLT for HCC from the Milan criteria is feasible with acceptable outcomes.

Hori K.,University of Tokyo
Journal of High Energy Physics | Year: 2013

We study the low energy behaviour of N = (2, 2) supersymmetric gauge theories in 1 + 1 dimensions, with orthogonal and symplectic gauge groups and matters in the fundamental representation. We observe supersymmetry breaking in super-Yang-Mills theory and in theories with small numbers of flavors. For larger numbers of flavors, we discover duality between regular theories with different gauge groups and matter contents, where regularity refers to absence of quantum Coulomb branch. The result is applied to study families of superconformal field theories that can be used for superstring compactifications, with corners corresponding to three-dimensional Calabi-Yau manifolds. This work is motivated by recent development in mathematics concerning equivalences of derived categories. © SISSA 2013.

Aims: To assess the efficacy and safety of teneligliptin in combination with glimepiride in Japanese patients with type 2 diabetes mellitus (T2DM) inadequately controlled with glimepiride monotherapy. Methods: In the initial 12-week, double-blind, placebo-controlled, parallel-group period, 194 patients [haemoglobin A1c (HbA1c): 8.4±0.8%; fasting plasma glucose (FPG): 164.2±28.1mg/dl] were randomized to either teneligliptin 20mg or placebo once daily while continuing stable glimepiride therapy. This randomized period was then followed by a 40-week, open-label period, where all patients received teneligliptin once daily. The primary endpoint was the change in HbA1c from baseline to week 12. Results: Teneligliptin reduced HbA1c significantly compared with placebo at week 12. The placebo-subtracted change in HbA1c was -1.0±0.1% [least-squares (LS) mean±s.e., p<0.001]. Teneligliptin also significantly reduced FPG and 2-h postprandial glucose (PPG) as compared with placebo at week 12; the placebo-subtracted changes were -27.1±3.2 and -49.1±6.2mg/dl (LS mean±s.e., both p<0.001), respectively. The blood glucose-lowering effects were sustained throughout the 40-week open-label period. The incidence rates of adverse events and adverse drug reactions, including hypoglycaemia, during the double-blind randomized period were similar in both groups. Therefore, teneligliptin was generally well tolerated when used in combination with glimepiride. Conclusions: The addition of teneligliptin was effective and generally well tolerated in Japanese patients with T2DM inadequately controlled with glimepiride monotherapy. The improvements in glycaemic control were maintained for up to 52weeks. © 2013 John Wiley & Sons Ltd.

Nakayama Y.,University of Tokyo
International Journal of Modern Physics A | Year: 2013

We propose various properties of renormalization group beta functions for vector operators in relativistic quantum field theories. We argue that they must satisfy compensated gauge invariance, orthogonality with respect to scalar beta functions, Higgs-like relation among anomalous dimensions and a gradient property. We further conjecture that nonrenormalization holds if and only if the vector operator is conserved. The local renormalization group analysis guarantees the first three within power counting renormalization. We verify all the conjectures in conformal perturbation theories and holography in the weakly coupled gravity regime. © 2013 World Scientific Publishing Company.

Yoshikai N.,Nanyang Technological University | Nakamura E.,University of Tokyo
Chemical Reviews | Year: 2012

A study was conducted to demonstrate mechanisms of nucleophilic organocopper(I) reactions. A comprehensive mechanistic picture of representative organocopper(I)-mediated C C bond-forming reactions was demonstrated. The structures of organocopper compounds, organocopper(I) ate complexes, and organocopper(III) complexes were described. The electronic structure of organocuprate(I) complexes and theirmolecular orbital interactions with electrophiles were discussed to gather information about the oxidative addition process of the organocuprate reactions. This demonstrated the way Lewis acidic countercations affected the organocuprate reaction and how organocopper(III) intermediates produced the C C coupling products. Organocopper reagents were also compared with organosilver and -gold analogues.

Shimoyama J.-I.,University of Tokyo
Superconductor Science and Technology | Year: 2014

Since the discovery of high-Tc superconductivity in the REFeAs(O, F) system in 2008, studies on the development of superconducting materials using iron-based superconductors has been undertaken because of their high Hc2 and relatively high Tc. Although the cuprate superconductors exhibit much higher Tc and similar high H c2, the small degree of electromagnetic anisotropy between the c-axis and ab-plane directions confirmed in 11, 122 and 1111 systems encouraged us to develop more versatile conductors. Single crystals and thin films deposited on single-crystalline and metal substrates have proved that the potentials of the iron-based superconductors are high enough for designing superconducting materials for high field generation. In addition, critical current properties of powder-in-tube processed tapes have been greatly improved in the past two years and are reaching the application level at 4.2 K in high magnetic field. However, the pinning mechanism and determining factors of the critical current properties of the iron-based superconductors have not been well understood. Characteristics and potentials of iron-based superconductors are discussed from various viewpoints in this paper in an effort to understand the current status and future prospects. © 2014 IOP Publishing Ltd.

Ho K.,University of Tokyo
Acta Astronautica | Year: 2012

This paper aims to present a set of lost-in-space star identification algorithms that works effectively for small satellites. Several algorithms are investigated for both phases of star identification: feature extraction and catalogue search. For feature extraction, it is shown that an algorithm using extended images with combined images works best, and for catalogue search, the Group Catalogue is shown to be most efficient. Therefore, this paper proposes an algorithm combining these three. Simulation results show the effectiveness of this algorithm for its robustness to various errors, and an application of this algorithm, unequal star trackers, is introduced. © 2011 Elsevier Ltd All rights reserved.

Abe I.,University of Tokyo
Current Opinion in Chemical Biology | Year: 2012

The structurally and mechanistically simple type III polyketide synthases (PKSs) catalyze iterative condensations of CoA thioesters to produce a variety of polyketide scaffolds with remarkably diverse structures and biological activities. By exploiting the enzymes, we combined precursor-directed biosynthesis with nitrogen-containing substrates and structure-based enzyme engineering and generated unnatural, novel polyketide-alkaloid scaffolds with promising biological activities. The nucleophilic nitrogen atom and the engineered enzymes thus facilitated the formation of additional C. C and C. N bonds during the enzymatic transformations. The methodology will contribute to the further production of chemically and structurally divergent, unnatural natural products, as well as the rational design of novel biocatalysts with unprecedented catalytic functions. © 2011 Elsevier Ltd.

Two theoretical methods of finding resonant states in open quantum systems, namely the approach of the Siegert boundary condition and the Feshbach formalism, are reviewed and shown to be algebraically equivalent to each other for a simple model of the T-type quantum dot. It is stressed that the seemingly Hermitian Hamiltonian of an open quantum system is implicitly non-Hermitian outside the Hilbert space. The two theoretical approaches extract an explicitly non-Hermitian effective Hamiltonian in a contracted space out of the seemingly Hermitian (but implicitly non-Hermitian) full Hamiltonian in the infinite-dimensional state space of an open quantum system. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Miura M.,University of Tokyo
Cold Spring Harbor Perspectives in Biology | Year: 2012

A developing animal is exposed to both intrinsic and extrinsic stresses. One stress response is caspase activation. Caspase activation not only controls apoptosis but also proliferation, differentiation, cell shape, and cell migration. Caspase activation drives development by executing cell death or nonapoptotic functions in a cell-autonomous manner, and by secreting signaling molecules or generating mechanical forces, in a noncell autonomous manner. © 2012 Cold Spring Harbor Laboratory Press.

Fukumoto S.,University of Tokyo
Current Opinion in Nephrology and Hypertension | Year: 2014

The review is intended to provide an update on the expanding knowledge regarding diseases caused by the excess actions of fibroblast growth factor 23 (FGF23) and also on the new therapeutic measures for these diseases, with an emphasis on the anti-FGF23 antibody. RECENT FINDINGS: FGF23 decreases serum phosphate and 1,25-dihydroxyvitamin D levels. After the cloning of FGF23, several hypophosphatemic diseases, including tumor-induced osteomalacia and X-linked hypophosphatemic rickets (XLHR), were shown to be caused by excess actions of FGF23. In addition, recent studies indicated that mutations in the family with sequence similarity 20, member C (FAM20C), HRAS and NRAS genes, also caused FGF23-related hypophosphatemic diseases. The inhibition of FGF23 production or activity is, theoretically, an ideal treatment for these hypophosphatemic diseases. The C-Terminal fragment of FGF23, inhibitors of FGF receptor and extracellular signal-regulated kinase, and anti-FGF23 antibody were shown to inhibit FGF23 actions both in vitro and in vivo. A phase I clinical trial of anti-FGF23 antibody has shown that this antibody increases serum phosphate in patients with XLHR. SUMMARY: These recent findings confirm that FGF23 has a pivotal role in phosphate metabolism. The inhibition of FGF23 production or activity is promising as a new therapy for FGF23-related hypophosphatemic diseases. Further studies are clearly necessary to establish the clinical utility and long-Term safety of these measures. © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Jeppsson K.,Karolinska Institutet | Kanno T.,Karolinska Institutet | Shirahige K.,University of Tokyo | Sjogren C.,Karolinska Institutet
Nature Reviews Molecular Cell Biology | Year: 2014

Structural maintenance of chromosomes (SMC) complexes, which in eukaryotic cells include cohesin, condensin and the Smc5/6 complex, are central regulators of chromosome dynamics and control sister chromatid cohesion, chromosome condensation, DNA replication, DNA repair and transcription. Even though the molecular mechanisms that lead to this large range of functions are still unclear, it has been established that the complexes execute their functions through their association with chromosomal DNA. A large set of data also indicates that SMC complexes work as intermolecular and intramolecular linkers of DNA. When combining these insights with results from ongoing analyses of their chromosomal binding, and how this interaction influences the structure and dynamics of chromosomes, a picture of how SMC complexes carry out their many functions starts to emerge. © 2014 Macmillan Publishers Limited.

Liew S.P.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We study radiative decay of gravitino dark matter with trilinear R-parity violations. We show that the branching ratio of the decay of gravitino into monochromatic photon can be large enough to explain the observed gamma-ray line from the Galactic centre in the Fermi-LAT data without producing too much continuum gamma-ray and anti-proton flux. This scenario is realized when the mass of sfermions and the trilinear R-parity violating coupling are O(1-10) TeV and O(10-7-10-6) respectively. © 2013 Elsevier B.V.

Inagi R.,University of Tokyo
Biochemical Society Transactions | Year: 2014

Glycation is one of the important reactions regulating physiological state, and glycative stress, namely an overwhelming and unfavourable glycation state, is established as a pathological factor. Glycative stress is closely associated with not only various kidney diseases, but also kidney aging. Accumulating evidence, including studies in my laboratory, demonstrates that progression of renal tubular damage and its aging is correlated with the decrease in the activity of anti-glycative stress enzyme Glo1 (glyoxalase I) in the kidney. The reduction of glycative and oxidative stresses by Glo1 overexpression is beneficial for prevention of kidney disease and treatment, suggesting the novel therapeutic approaches targeting Glo1. The present review is focused on the impact of glycative stress and Glo1 on protein homoeostasis and discusses further the cross-talk between glycative stress and UPR (unfolded protein response), which controls the protein homoeostasis state. ©The Authors Journal compilation ©2014 Biochemical Society.

Kadowaki T.,University of Tokyo | Kondo K.,Mitsubishi Group
Diabetes, Obesity and Metabolism | Year: 2013

Aim: To assess the efficacy, safety and dose-response relationship of once-daily teneligliptin, a novel dipeptidyl peptidase-4 inhibitor, in Japanese patients with type 2 diabetes mellitus (T2DM) inadequately controlled with diet and exercise. Methods: In this randomized, double-blind, placebo-controlled, parallel-group study, patients (n=324) were randomized to receive teneligliptin 10, 20 or 40mg, or placebo, once daily before breakfast for 12weeks. The primary endpoint was the change in haemoglobin (Hb)A1c from baseline to week 12. Results: All teneligliptin-treated groups showed significantly greater reductions in HbA1c and fasting plasma glucose (FPG) than did the placebo group. The differences between the teneligliptin 10, 20 or 40mg groups and the placebo group for the change in HbA1c were -0.9 [least-squares (LS) mean; 95% confidence interval: -1.0, -0.7], -0.9 (-1.1, -0.7) and -1.0 (-1.2, -0.9)%, respectively (all, p<0.001). The respective LS means for FPG were -17.8 (-23.4, -12.1), -16.9 (-22.6, -11.2) and -20.0 (-25.7, -14.3) mg/dl (all, p<0.001). There were no significant differences in HbA1c among the three doses of teneligliptin. The incidence of adverse events and adverse drug reactions was similar in each group. The incidence of hypoglycaemia was not significantly different among the four groups. Conclusions: Treatment with teneligliptin for 12weeks provided significant and clinically meaningful reductions in HbA1c and FPG across the dose range studied and was generally well tolerated in Japanese patients with T2DM. © 2013 Blackwell Publishing Ltd.

Ip I.C.-H.,University of Tokyo
Selecta Mathematica, New Series | Year: 2013

We give complete detail of the description of the GNS representation of the quantum plane A and its dual  as a von Neumann algebra. In particular, we obtain a rather surprising result that the multiplicative unitary W is manageable in this quantum semigroup context. We study the quantum double group construction introduced by Woronowicz, and using Baaj and Vaes' construction of the multiplicative unitary Wm, we give the GNS description of the quantum double D(A) which is equivalent to GLq +(2, ℝ). Furthermore, we study the fundamental corepresentation Tλ, t and its matrix coefficients, and show that it can be expressed by the b-hypergeometric function. We also study the regular corepresentation and representation induced by Wm and prove that the space of L2 functions on the quantum double decomposes into the continuous series representation of Uqq̃(gl(2, ℝ)) with the quantum dilogarithm {pipe}Sb(Q+2iα){pipe}2 as the Plancherel measure. Finally, we describe certain representation theoretic meaning of integral transforms involving the quantum dilogarithm function. © 2012 Springer Basel.

Mixed harmonic charge dependent azimuthal correlations at mid-rapidity in Pb-Pb collisions at sNN=2.76TeV were measured with the ALICE detector at the LHC. A clear charge dependence for a series of correlations is observed both via the multi-particle cumulant and the event plane methods. Implications from these measurements for the possible effects of the local parity violation in QCD and for models which incorporate the azimuthal anisotropic flow and the local charge conservation on the kinetic freeze-out surface are discussed. © 2013 CERN.

Ootani W.,University of Tokyo
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

The MEG experiment in search for the lepton flavor decay μ+→e+γ is planned to be upgraded to reach the branching ratio sensitivity down to 5×10-14, which is one order of magnitude higher than that of the current phase of the experiment. A pixelated scintillation detector with an ultimate time resolution is under development for the positron time measurement in the upgraded experiment. Single pixel time resolutions better than 50 ps (rms) are achieved with prototype counters and an excellent overall time resolution at a level of 30-35 ps (rms) is found to be achievable in the full-scale detector by averaging the positron impact times over multiple hit counters. © 2013 Elsevier B.V. © 2013 Elsevier Ltd. All rights reserved.

Hatakeyama M.,University of Tokyo
Cell Host and Microbe | Year: 2014

Helicobacter pylori is a gastric bacterial pathogen that is etiologically linked to human gastric cancer. The cytotoxin-associated gene A (CagA) protein of H. pylori, which is delivered into gastric epithelial cells via bacterial type IV secretion, is an oncoprotein that can induce malignant neoplasms in mammals. Upon delivery, CagA perturbs multiple host signaling pathways by acting as an extrinsic scaffold or hub protein. On one hand, signals aberrantly raised by CagA are integrated into a direct oncogenic insult, whereas on the other hand, they engender genetic instability. Despite its decisive role in the development of gastric cancer, CagA is not required for the maintenance of a neoplastic phenotype in established cancer cells. Therefore, CagA-conducted gastric carcinogenesis progresses through a hit-and-run mechanism in which pro-oncogenic actions of CagA are successively taken over by a series of genetic and/or epigenetic alterations compiled in cancer-predisposing cells during long-standing infection with cagA-positive H. pylori. ©2014 Elsevier Inc.

Shen H.-M.,National University of Singapore | Mizushima N.,University of Tokyo
Trends in Biochemical Sciences | Year: 2014

In the past decade, autophagy studies have largely focused on the early stage of autophagy: the molecular mechanisms leading to autophagosome formation. Recently, however, we have observed significant progress in understanding the role of lysosomes, the specific cellular organelle that degrades cellular components delivered via autophagy. The discoveries include connections between autophagy and lysosomal biogenesis, activation, reformation, and turnover, as well as the identification of an autophagosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein in control of autophagosome-lysosome fusion. We illustrate these findings in the context of the underlying molecular mechanisms and the relevance to human health and disease. © 2013 Elsevier Ltd.

Minami T.,University of Tokyo
Journal of Biochemistry | Year: 2014

Calcineurin-nuclear factor of activated T cells (NFAT) signalling plays a critical role not only in the immune and nervous systems, but also in cardiovascular development and pathological endothelial cell activation during angiogenesis or inflammation. Studies in NFAT-null mice demonstrated that there is high redundancy between functions of the different NFAT family members. Deletion of only one NFAT causes mild phenotypes, but compound deletions of multiple NFAT family members leads to severe abnormalities in multiple organ systems. Genome-wide transcription analysis revealed that many NFAT target genes are related to cell growth and inflammation, whereas the gene most strongly induced by NFAT in endothelial cells is an auto-inhibitory molecule, Down syndrome critical region (DSCR)-1. The NFAT-DSCR-1 signalling axis may vary depending on the cell-type or signal dosage level under the microenvironment. In the endothelium, stable expression of the DSCR-1 short isoform attenuates septic inflammatory shock, tumour growth and tumour metastasis to lung. Moreover, dysfunction of DSCR-1 and the NFAT priming kinase, DYRK1A, prevents NFAT nuclear occupancy. This change in NFAT nuclear localization is responsible for many of the features of Down syndrome. Thus, fine-tuning of the NFAT-DSCR-1 negative feedback loop may enable therapeutic manipulation in vasculopathic diseases. © 2014 The Authors 2014. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Stamper-Kurn D.M.,University of California at Berkeley | Stamper-Kurn D.M.,Lawrence Berkeley National Laboratory | Ueda M.,University of Tokyo | Ueda M.,Lawrence Berkeley National Laboratory
Reviews of Modern Physics | Year: 2013

Spinor Bose gases form a family of quantum fluids manifesting both magnetic order and superfluidity. This article reviews experimental and theoretical progress in understanding the static and dynamic properties of these fluids. The connection between system properties and the rotational symmetry properties of the atomic states and their interactions are investigated. Following a review of the experimental techniques used for characterizing spinor gases, their mean-field and many-body ground states, both in isolation and under the application of symmetry-breaking external fields, are discussed. These states serve as the starting point for understanding low-energy dynamics, spin textures, and topological defects, effects of magnetic-dipole interactions, and various nonequilibrium collective spin-mixing phenomena. The paper aims to form connections and establish coherence among the vast range of works on spinor Bose gases, so as to point to open questions and future research opportunities. © 2013 American Physical Society.

Kaneko D.,University of Tokyo
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

The MEG experiment is searching for the lepton flavor violating decay, μ+→e++γ, with the highest sensitivity. A major upgrade of the experiment is planned where the performance of the liquid xenon (LXe) γ-ray detector is expected to be significantly improved. The current 2-in. photomultiplier tubes (PMT) on the γ-ray incident face will be replaced with smaller photo-sensors such as multi-pixel photon counters (MPPC) in order to improve the resolutions and the efficiency. A UV-sensitive MPPC operational in LXe is under development in collaboration with Hamamatsu Photonics. A high photon detection efficiency (PDE) of 17% to LXe scintillation light is achieved with a prototype with an active area of 12×12 mm 2 and a single-photoelectron peak is clearly observed. The engineering design of the detector and the development of the related technologies such as the signal transmission and assembly are also steadily in progress. © 2013 Elsevier B.V.

Sakai K.,University of Tokyo
Nuclear Physics B | Year: 2013

We provide multiple Schramm-Loewner evolutions (SLEs) to describe the scaling limit of multiple interfaces in critical lattice models possessing Lie algebra symmetries. The critical behavior of the models is described by Wess-Zumino-Witten (WZW) models. Introducing a multiple Brownian motion on a Lie group as well as that on the real line, we construct the multiple SLE with additional Lie algebra symmetries. The connection between the resultant SLE and the WZW model can be understood via SLE martingales satisfied by the correlation functions in the WZW model. Due to interactions among SLE traces, these Brownian motions have drift terms which are determined by partition functions for the corresponding WZW model. As a concrete example, we apply the formula to the sû (2)k-WZW model. Utilizing the fusion rules in the model, we conjecture that there exists a one-to-one correspondence between the partition functions and the topologically inequivalent configurations of the SLE traces. Furthermore, solving the Knizhnik-Zamolodchikov equation, we exactly compute the probabilities of occurrence for certain configurations (i.e. crossing probabilities) of traces for the triple SLE. © 2012 Elsevier B.V.

Tajima H.,University of Tokyo
Annals of Physics | Year: 2013

A necessary and sufficient condition of the possibility of a deterministic local operations and classical communication (LOCC) transformation of three-qubit pure states is given. The condition shows that the three-qubit pure states are a partially ordered set parametrized by five well-known entanglement parameters and a novel parameter; the five are the concurrences C A B, C A C, C B C, the tangle τA B C and the fifth parameter J5 of Acín etal. (2000) Ref. [19], while the other new one is the entanglement charge Qe. The order of the partially ordered set is defined by the possibility of a deterministic LOCC transformation from a state to another state. In this sense, the present condition is an extension of Nielsen's work (Nielsen (1999) [14]) to three-qubit pure states. We also clarify the rules of transfer and dissipation of the entanglement which is caused by deterministic LOCC transformations. Moreover, the minimum number of times of measurements to reproduce an arbitrary deterministic LOCC transformation between three-qubit pure states is given. © 2012 Elsevier Inc.

Andersen U.L.,Technical University of Denmark | Neergaard-Nielsen J.S.,Technical University of Denmark | Van Loock P.,Johannes Gutenberg University Mainz | Furusawa A.,University of Tokyo
Nature Physics | Year: 2015

Research in quantum information processing has followed two different directions: the use of discrete variables (qubits) and that of high-dimensional, continuous-variable Gaussian states (coherent and squeezed states). Recently, these two approaches have been converging in potentially more powerful hybrid protocols. © 2015 Macmillan Publishers Limited. All rights reserved.

Photocatalytic water splitting using particulate semiconductors is a potentially scalable and economically feasible technology for converting solar energy into hydrogen. Z-scheme systems based on two-step photoexcitation of a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) are suited to harvesting of sunlight because semiconductors with either water reduction or oxidation activity can be applied to the water splitting reaction. However, it is challenging to achieve efficient transfer of electrons between HEP and OEP particles. Here, we present photocatalyst sheets based on La- and Rh-codoped SrTiO3 (SrTiO3:La, Rh; ref. ) and Mo-doped BiVO4 (BiVO4:Mo) powders embedded into a gold (Au) layer. Enhancement of the electron relay by annealing and suppression of undesirable reactions through surface modification allow pure water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm. The photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors. © 2016 Nature Publishing Group

Iino M.,University of Tokyo
Proceedings of the Japan Academy Series B: Physical and Biological Sciences | Year: 2010

Changes in the intracellular Ca2+ concentration regulate numerous cell functions and display diverse spatiotemporal dynamics, which underlie the versatility of Ca2+ in cell signaling. In many cell types, an increase in the intracellular Ca2+ concentration starts locally, propagates within the cell (Ca2+ wave) and makes oscillatory changes (Ca2+ oscillation). Studies of the intracellular Ca2+ release mechanism from the endoplasmic reticulum (ER) showed that the Ca2+ release mechanism has inherent regenerative properties, which is essential for the generation of Ca2+ waves and oscillations. Ca2+ may shuttle between the ER and mitochondria, and this appears to be important for pacemaking of Ca2+ oscillations. Importantly, Ca2+ oscillations are an efficient mechanism in regulating cell functions, having effects supra-proportional to the sum of duration of Ca2+ increase. Furthermore, Ca2+ signaling mechanism studies have led to the development of a method for specific inhibition of Ca2+ signaling, which has been used to identify hitherto unrecognized functions of Ca2+ signals. © 2010 The Japan Academy.

Polystyrene (PS) composites reinforced with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) with various weight ratios were fabricated by casting and vacuum-drying mixtures of PS/N,N-dimethylformamide (DMF) solution and TOCN/DMF dispersion. TOCNs of 3 to 4 nm width were dispersed homogeneously at the individual nanofibril level in the PS matrix, such that the TOCN/PS nanocomposite films exhibited high optical transparencies and their tensile strengths, elastic moduli, and thermal dimensional stabilities increased with increasing TOCN content. Dynamic mechanical analysis showed that the storage modulus of the TOCN/PS films increased significantly with TOCN content above the glass-transition temperature of PS by the formation of an interfibrillar network structure of TOCNs in the PS matrix, based on percolation theory. The outstanding and effective polymer reinforcement by TOCNs results from their high aspect ratio, high crystallinity, and nanodispersibility in the PS matrix.

Shiohara H.,University of Tokyo
ACI Structural Journal | Year: 2012

This paper proposes a new set of general and rational concepts useful in identifying and defining the ultimate behavior of two-dimensional reinforced concrete beam-column joints subjected to lateral load. It is based on a model that reflects observations of the crack pattern at failure and its compatible kinematic field overlooked in previous research. The kinematic model, called a nine-parameter model, is combined with nonlinear constitutive relations for concrete and steel. New concepts of ultimate moment capacity and moment at balanced failure of beam-column joints are defined. The upper bound value of reinforcement precluding joint failure before yielding of longitudinal reinforcement is also defined. In addition, this paper demonstrates how the concepts are used to derive a set of simple algebraic expressions that can be applied to design, taking as an example the simplified case of a symmetric interior beam-column joint subjected to symmetric couples transmitted through the four connected members without joint shear reinforcement or mid-layer longitudinal reinforcement in the column. The factors affecting the moment capacity and the upper bound value of reinforcement are identified by comparing the mathematical prediction to the results of the example. Copyright © 2012, American Concrete Institute.

The revised Organ Transplant Law in Japan that took effect in July 2010 allows organ procurement from brain-dead individuals, including children, only with family consent. The amended law also allows individuals to prioritize family members to receive their donated organs after death. This policy differs from the prioritization policy in Israel, which provides incentives to individuals who agree to help each other in society and rectifies the problem of free riders, individuals who are willing to accept an organ but refuse to donate. Despite these differences, however, the Japanese and Israeli policies have revealed new ethical dilemmas, including the fear of compromising fairness in organ allocation. © 2011 by Lippincott Williams & Wilkins.

Ueda M.,University of Tokyo
Annual Review of Condensed Matter Physics | Year: 2012

Gaseous Bose-Einstein condensates with nonzero spin feature multicomponent order parameters that reflect the internal degrees of freedom. They exhibit a rich variety of superfluid and magnetic phenomena similar or complementary to those of superfluid helium-3. The unprecedented degree of manipulability of atomic gases makes spinor condensates a unique playground for exploring symmetry breaking, topological excitations, and the interplay between superfluidity and magnetism. An overview of these subjects is provided. Copyright © 2012 by Annual Reviews. All rights reserved.

Nojiri H.,University of Tokyo
Bioscience, Biotechnology and Biochemistry | Year: 2012

Carbazole degradation by several bacterial strains, including Pseudomonas resinovorans CA10, has been investigated over the last two decades. As the initial reaction in degradation pathways, carbazole is commonly oxygenated at angular (C9a) and adjacent (C1) carbons as two hydroxyl groups in a cis configuration. This type of dioxygenation is termed "angular dioxygenation," and is catalyzed by carbazole 1,9a-dioxygenase (CARDO), consisting of terminal oxygenase, ferredoxin, and ferredoxin reductase components. The crystal structures of all components and the electron transfer complex between terminal oxygenase and ferredoxin indicate substrate recognition mechanisms suitable for angular dioxygenation and specific electron transfer among the three components. In contrast, the carbazole degradative car operon of CA10 is located on IncP-7 conjugative plasmid pCAR1. Together with conventional molecular genetic and biochemical investigations, recent genome sequencing and RNA mapping studies have clarified that transcriptional cross-regulation via nucleoid-associated proteins is established between pCAR1 and the host chromosome.

Recent advances in the transition-metal-catalyzed enantioselective propargylic substitution reactions of propargylic alcohol derivatives with nucleophiles are reviewed in this article. After the disclosure of the first example of a ruthenium-catalyzed propargylic alkylation, various types of enantioselective propargylic substitution reactions, including enantioselective propargylation of aromatic compounds, have been reported in the last eight years. In addition, a variety of enantioselective propargylic alkylations use two distinct catalysts, where the two catalysts work cooperatively to promote the asymmetric reactions. 1 Introduction 2 Ruthenium-Catalyzed Enantioselective Propargylic Substitution Reactions 2.1 Propargylic Alkylation 2.2 Propargylation of Aromatic Compounds with Propargylic Alcohols 2.3 Propargylic Substitution Reactions of Propargylic Alcohols with Alkenes 2.4 Cycloadditions between Propargylic Alcohols and 2-Naphthols 3 Copper-Catalyzed Enantioselective Propargylic Substitution Reactions 3.1 Propargylic Amination 3.2 Ring-Opening Reactions of Ethynyl Epoxides 3.3 Propargylic Alkylation 3.4 Propargylation of Indoles 4 Cooperative Enantioselective Propargylic Alkylations -Using Transition-Metal Catalysts and Organocatalysts 4.1 With Ruthenium Catalysts 4.2 With Copper Catalysts 4.3 With Lewis Acid Catalysts 5 Cooperative Reactions Using Distinct Transition-Metal Catalysts 6 Miscellaneous Reactions 7 Conclusion. © Georg Thieme Verlag Stuttgart · New York.

Ishii K.,University of Tokyo
Coordination Chemistry Reviews | Year: 2012

This review summarizes recent studies on functional singlet oxygen ( 1Δ g) generators based on phthalocyanines (Pcs). Singlet oxygen ( 1Δ g) is useful for application in photodynamic cancer therapy (PDT), photooxidation of toxic molecules, and photoproduction of important intermediates for various chemicals owing to its high oxidation ability. Pc derivatives have been investigated as photosensitizers for singlet oxygen ( 1Δ g) generation because of their intense absorption bands at longer wavelengths, at which light can penetrate numerous chemical species and biological tissues such as skin. Thus, I have concentrated on the singlet oxygen ( 1Δ g) generators with characteristic photophysical and photochemical properties as follows. Firstly, efficient singlet oxygen generation without the heavy-atom effects is discussed in terms of both nitroxide radicals and lowering of the symmetry of π-conjugated systems. This methodology enhances flexibility in molecular designs. Next, control of photobleaching in PDT is described. On the basis of this control, additional absorption of photosensitizers inducing considerable opacity can be arbitrarily removed by the use of stepwise two-photon excitation. From the viewpoint of the photo-oxidizing agents, the singlet oxygen ( 1Δ g) generators based on hybridization between Pcs and various solid materials are also summarized in order to avoid aggregation behavior and impart novel functions. © 2012 Elsevier B.V.

Mori K.,University of Tokyo | Christodoulou A.,University College London
Environmental Impact Assessment Review | Year: 2012

The purpose of this paper is to discuss conceptual requirements for a City Sustainability Index (CSI) and to review existing major sustainability indices/indicators in terms of the requirements. The following indices are reviewed: Ecological Footprint (EF), Environmental Sustainability Index (ESI), Dashboard of Sustainability (DS), Welfare Index, Genuine Progress Indicator (GPI), Index of Sustainable Economic Welfare, City Development Index, emergy/exergy, Human Development Index (HDI), Environmental Vulnerability Index (EVI), Environmental Policy Index (EPI), Living Planet Index (LPI), Environmentally-adjusted Domestic Product (EDP), Genuine Saving (GS), and some applications of composite indices or/and multivariate indicators to local or regional context as case studies. The key conceptual requirements for an adequate CSI are: (i) to consider environmental, economic and social aspects (the triple bottom line of sustainability) from the viewpoint of strong sustainability; (ii) to capture external impacts (leakage effects) of city on other areas beyond the city boundaries particularly in terms of environmental aspects; (iii) to create indices/indicators originally for the purpose of assessing city sustainability; and (iv) to be able to assess world cities in both developed and developing countries using common axes of evaluation. Based on the review, we conclude that it is necessary to create a new CSI that enables us to assess and compare cities' sustainability performance in order to understand the global impact of cities on the environment and human life as compared with their economic contribution. In the future, the CSI will be able to provide local authorities with guidance toward sustainable paths. © 2011 Elsevier Inc.

Ito K.,University of Tokyo
Polymer Journal | Year: 2012

We have recently developed a slide-ring gel that is different from physical and chemical gels by crosslinking polyrotaxane, a necklace-like supramolecule. Slide-ring gel, consisting of movable crosslinks and free uncrosslinked cyclic molecules, shows peculiar mechanical properties, different from conventional chemical gels. For instance, slide-ring gel shows quite a low Young's modulus, which is not proportional to crosslinking density and is much lower than that of chemical gels with the same density. This low modulus arises from differences in the molecular mechanism of entropic elasticity; whereas conformational entropy is mainly responsible for elasticity in typical chemical gels and rubbers, the mechanical properties of slide-ring gel are inherently governed by the arrangement entropy of free cyclic molecules in polyrotaxane, as well as the conformational entropy of the axis polymer. This means that the softness of slide-ring gel is due to novel entropic elasticity, which is also expected to provide a sliding state and a sliding transition. © The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Fushinobu S.,University of Tokyo
Bioscience, Biotechnology and Biochemistry | Year: 2010

Bifidobacteria have many beneficial effects for human health. The gastrointestinal tract, where natural colonization of bifidobacteria occurs, is an environment poor in nutrition and oxygen. Therefore, bifidobacteria have many unique glycosidases, transporters, and metabolic enzymes for sugar fermentation to utilize diverse carbohydrates that are not absorbed by host humans and animals. They have a unique, effective central fermentative pathway called bifid shunt. Recently, a novel metabolic pathway that utilizes both human milk oligosaccharides and host glycoconjugates was found. The galacto-N-biose/lacto- N-biose I metabolic pathway plays a key role in colonization in the infant gastrointestinal tract. These pathways involve many unique enzymes and proteins. This review focuses on their molecular mechanisms, as revealed by biochemical and crystallographic studies.

Komiyama S.,University of Tokyo
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2011

Semiconductor quantum dot detectors as well as semiconductor charge-sensitive infrared phototransistors are described. They are the only detectors that can count single photons in the terahertz region at present. In terms of the noise equivalent power (NEP), the detectors realize experimental values on the order of 10 -21W/Hz 1/2, while theoretically expected values are even much lower, on the order of 10 -24W/Hz 1/2. These NEP values are by several orders of magnitude lower than any other state-of-the-art highly sensitive detectors. In addition to the outstanding sensitivity, the detectors are featured by strong advantage of huge current responsivity (10 6-10 10A/W) and extremely large dynamic range of response (10 6 - 10 8). The mechanism of detection as well as application of the detectors is discussed. © 2010 IEEE.

Shibayama M.,University of Tokyo
Soft Matter | Year: 2012

Recent developments of tough hydrogels have changed the concept of hydrogels. These gels have an extraordinarily high modulus, high tenacity, and high deformability. In this review, it is demonstrated that structural analyses with small-angle neutron scattering (SANS) have elucidated the origin of the toughness and the mechanisms of deformation of tough hydrogels. Particularly, we focus on Tetra-PEG gels because of their simple and uniform architecture, i.e., unimodal network free from trapped entanglements and with negligible network defects, and investigate the structure-mechanical property relationship. This journal is © 2012 The Royal Society of Chemistry.

PsbP is a thylakoid lumen protein involved in oxygen evolution in photosystem II (PSII) in green plants. Genomic analysis identified a number of PsbP homologs in plants, algae, and cyanobacteria. To analyze the transition of cyanobacterial PsbO/U/V complex to PsbO/P/Q complex in green plants, the evolutionary history of the PsbP superfamily was reconstructed. Phylogenetic analyses suggested that PsbP homologs be classified into eight major families (A-H), which were also characterized by specific insertion/deletion of short segments, as found by sequence alignment and homology modeling. Family A represented authentic PsbP proteins involved in oxygen evolution. The cyanobacterial PsbP and plant/algal PPL (Family H), having the simplest structure, should be considered as the root of all other families of PsbP, which subsequently gained various short, family-specific structural motifs during diversification of PsbP families. Interestingly, segments specific to Family A proteins were found arranged as a ring surrounding the modeled Arabidopsis PsbP protein. These results suggest that Family A-specific additions of short segments played a decisive role in the transition of PsbO/U/V to PsbO/P/Q complex in green plants. © 2009 Elsevier Inc. All rights reserved.

Nagano T.,University of Tokyo
Proceedings of the Japan Academy Series B: Physical and Biological Sciences | Year: 2010

Fluorescent probes, which allow visualization of cations such as Ca 2+, Zn 2+ etc., small biomolecules such as nitric oxide (NO) or enzyme activities in living cells by means of fluorescence microscopy, have become indispensable tools for clarifying functions in biological systems. This review deals with the general principles for the design of bioimaging fluorescent probes by modulating the fluorescence properties of fluorophores, employing mechanisms such as acceptor-excited Photoinduced electron Transfer (a-PeT), donor-excited Photoinduced electron Transfer (d-PeT), and spirocyclization, which have been established by our group. The a-PeT and d-PeT mechanisms are widely applicable for the design of bioimaging probes based on many fluorophores and the spirocyclization process is also expected to be useful as a fluorescence off/on switching mechanism. Fluorescence modulation mechanisms are essential for the rational design of novel fluorescence probes for target molecules. Based on these mechanisms, we have developed more than fifty bioimaging probes, of which fourteen are commercially available. The review also describes some applications of the probes developed by our group to in vitro and in vivo systems. © 2010 The Japan Academy.

Kobayashi H.,U.S. National Institutes of Health | Ogawa M.,U.S. National Institutes of Health | Alford R.,U.S. National Institutes of Health | Choyke P.L.,U.S. National Institutes of Health | Urano Y.,University of Tokyo
Chemical Reviews | Year: 2010

New strategies for fluorescent probe design in medical diagnostic imaging have been reported. Molecular imaging has been defined as the in vivo characterization and measurement of biological processes at the cellular and molecular level, or more broadly as a technique to directly or indirectly monitor and record the spatiotemporal distribution of molecular or cellular processes for biochemical, biological, diagnostic, or therapeutic application. The stability of a fluorophore in vivo is another important consideration. Genetically encoded fluorescent proteins come from a wide range of animals found in nature. Artificial, endogenous proteins have also been generated with emission wavelengths not found in nature, including infrared. Fluorescence lifetime imaging is the production of spatially resolved images which reflect the time required for an excited fluorophore to transition to its ground state.

Abe E.,University of Tokyo
Chemical Society Reviews | Year: 2012

Quasicrystals represent aperiodically ordered form of solids with symmetries long thought forbidden in nature. Since their discovery, the fundamental key question has been "where are the atoms?" in these novel aperiodic solids, and electron microscopy has indeed provided images of real atomic arrangements in quasicrystals. In this tutorial review, we describe the microscopic view of quasicrystals using state-of-the-art scanning transmission electron microscopy, providing intriguing details that had never been unveiled by the early diffraction-based structural analyses. © 2012 The Royal Society of Chemistry.

Nishibayashi Y.,University of Tokyo
Dalton Transactions | Year: 2012

Quite recently we have found two nitrogen fixation systems catalyzed by molybdenum-dinitrogen complexes under mild reaction conditions; one is the transformation of molecular dinitrogen into its synthetic equivalent of ammonia and the other is that into ammonia. A molybdenum-dinitrogen complex bearing two ferrocenyl diphosphines works as a good catalyst in the transformation of molecular dinitrogen into silylamine, where up to 226 equiv are produced based on the catalyst. A dinitrogen-bridged dimolybdenum complex bearing a PNP-type pincer ligand works as a good catalyst in the direct transformation of molecular dinitrogen into ammonia, where up to 23 equiv are produced based on the catalyst. We believe that both systems provide a new aspect in the development of novel nitrogen fixation. © 2012 The Royal Society of Chemistry.

Kobayashi T.,Ishikawa Prefectural University | Nishizawa N.K.,Ishikawa Prefectural University | Nishizawa N.K.,University of Tokyo
Annual Review of Plant Biology | Year: 2012

Iron is essential for the survival and proliferation of all plants. Higher plants have developed two distinct strategies to acquire iron, which is only slightly soluble, from the rhizosphere: the reduction strategy of nongraminaceous plants and the chelation strategy of graminaceous plants. Key molecular components-including transporters, enzymes, and chelators-have been clarified for both strategies, and many of these components are now thought to also function inside the plant to facilitate internal iron transport. Transporters for intracellular iron trafficking are also being clarified. A majority of genes encoding these components are transcriptionally regulated in response to iron availability. Recent research has uncovered central transcription factors, cis-acting elements, and molecular mechanisms regulating these genes. Manipulation of these molecular components has produced transgenic crops with enhanced tolerance to iron deficiency or with increased iron content in the edible parts. © 2012 by Annual Reviews. All rights reserved.

Matsuo Y.,University of Tokyo
Chemistry Letters | Year: 2012

This review article describes design concept, synthesis, and features of fullerene derivatives having high lowest unoccupied molecular orbital (LUMO) levels to achieve high open-circuit voltage in organic thin-film photovoltaic devices. Installation of organic electron-donating groups onto fullerene and decrease of the size of the fullerene π-electron-conjugated system raise the LUMO levels, affording high-performance organic solar cells. Addition of the methano group as the smallest carbon addend to fullerene to obtain 56π-electron fullerene derivatives is likely a promising strategy for this purpose. © 2012 The Chemical Society of Japan.

Nitrogen inputs into stream and river ecosystems, and the factors influencing those inputs, are important for various ecological and environmental concerns. Reliable information on where and how nitrogen compounds flow into aquatic ecosystems is indispensable to understanding the nutrient status of these ecosystems. Such information should include the biogeochemical mechanisms and hydrological controls of nutrient leaching into rivers from terrestrial systems such as forests, agricultural fields, and urbanized areas. Advancements in stable isotopomer measurements over the past two decades have expanded the variety of target substances and the precision with which they can be investigated. The high-throughput microbial denitrifier method allows for simultaneous measurement of nitrogen and oxygen isotope ratios and can provide high-resolution spatiotemporal information on both nitrate sources and biogeochemical processes. Although advanced techniques of stable isotope analysis have been used extensively to detect sources and estimate the relative contributions of multi-source systems in various rivers, there are still new horizons in investigating nitrogen transformations. For example, stable isotopes of oxygen (18O and 17O) occurring in nitrate due to atmospheric deposition can be used as natural tracers for evaluating internal nitrogen cycling; these isotopes are distinct from the oxygen within microbially generated nitrate in soils and water bodies. Another future challenge is improved use of nitrous oxide isotopomers in evaluating the relative contributions of nitrification and denitrification. Such analysis could provide insight into the nitrogen transformation that occurs under redox conditions at the boundary between terrestrial and aquatic systems, where nitrification and denitrification often occur simultaneously in soil and aquatic environments. © 2012 The Ecological Society of Japan.

Le Gall F.,University of Tokyo
Proceedings - Annual IEEE Symposium on Foundations of Computer Science, FOCS | Year: 2012

Let α be the maximal value such that the product of an n x n α matrix by an nα x n matrix can be computed with n2+o(1) arithmetic operations. In this paper we show that α > 0.30298, which improves the previous record α > 0.29462 by Coppersmith (Journal of Complexity, 1997). More generally, we construct a new algorithm for multiplying an n x nk matrix by an nk x n matrix, for any value k ≠ 1. The complexity of this algorithm is better than all known algorithms for rectangular matrix multiplication. In the case of square matrix multiplication (i.e., for k=1), we recover exactly the complexity of the algorithm by Coppersmith and Wino grad (Journal of Symbolic Computation, 1990). These new upper bounds can be used to improve the time complexity of several known algorithms that rely on rectangular matrix multiplication. For example, we directly obtain a O(n2.5302)-time algorithm for the all-pairs shortest paths problem over directed graphs with small integer weights, where n denotes the number of vertices, and also improve the time complexity of sparse square matrix multiplication. © 2012 IEEE.

Narushima M.,University of Tokyo
Plastic and Reconstructive Surgery | Year: 2010

Background: In secondary extremity lymphedema, normal antegrade lymphatic flow is disrupted by the disease state. Attempts to capture aberrant retrograde lymphatic flow by means of microsurgical lymphaticovenous anastomoses have been hindered because of technical limitations. The authors applied the intravascular stenting method to the surgical correction of extremity lymphedema to generate multiconfiguration lymphaticovenous anastomoses capable of decompressing both proximal and distal lymphatic flow. Methods: Lymphatic channels were detected using indocyanine green injection and infrared scope imaging. Sites felt to be adequate for lymphaticovenous anastomosis were accessed through 2-cm skin incisions under local anesthesia. Using the intravascular stenting method, the authors performed a total of 39 lymphaticovenous anastomoses (15 flow-through, 11 end-to-end, eight end-to-side, two double end-to-end, two end-to-end/end-to-side, and one π-type) on both the proximal and distal ends of lymphatic channels in 14 female patients with upper (n = 2) and lower (n = 12) extremity lymphedema. Results: At an average follow-up of 8.9 months, average limb girth decreased 3.6 cm (range, 1.5 to 7 cm) or 11.3 percent (range, 4 to 33 percent). There was a greater reduction in cross-sectional area with increasing number of lymphaticovenous anastomoses per limb. Conclusions: The intravascular stenting method facilitated multiconfiguration lymphaticovenous anastomoses capable of decompressing both antegrade and retrograde lymphatic flow. This approach resulted in durable reduction of both upper and lower extremity lymphedema. As multiconfiguration lymphaticovenous anastomoses are now technically feasible, the influence of the number of lymphaticovenous anastomoses and the effectiveness of specific lymphaticovenous anastomosis configurations for the treatment of lymphedema deserves further study. Copyright © 2010 by the American Society of Plastic Surgeons.

Saito M.,Hiroshima University | Matsumoto M.,University of Tokyo
ACM Transactions on Mathematical Software | Year: 2013

This article proposes a type of pseudorandom number generator, Mersenne Twister for Graphic Processor (MTGP), for efficient generation on graphic processessing units (GPUs). MTGP supports large state sizes such as 11213 bits, and uses the high parallelism of GPUs in computing many steps of the recursion in parallel. The second proposal is a parameter-set generator for MTGP, named MTGP Dynamic Creator (MTGPDC). MTGPDC creates up to 232 distinct parameter sets which generate sequences with high-dimensional uniformity. This facility is suitable for a large grid of GPUs where each GPU requires separate random number streams. MTGP is based on linear recursion over the two-element field, and has better high-dimensional equidistribution than the Mersenne Twister pseudorandom number generator. © 2013 ACM.

Nakai Y.,University of Tokyo
Digestive endoscopy : official journal of the Japan Gastroenterological Endoscopy Society | Year: 2014

Confocal laser endomicroscopy (CLE) is an emerging diagnostic procedure that enables in vivo pathological evaluation during ongoing endoscopy. There are two types of CLE: endoscope-based CLE (eCLE), which is integrated in the tip of the endoscope, and probe-based CLE (pCLE), which goes through the accessory channel of the endoscope. Clinical data of CLE have been reported mainly in gastrointestinal (GI) diseases including Barrett's esophagus, gastric neoplasms, and colon polyps, but, recently, a smaller pCLE, which goes through a catheter or a fine-needle aspiration needle, was developed and clinical data in the diagnosis of biliary stricture or pancreatic cysts have been increasingly reported. The future application of this novel technique expands beyond the pathological diagnosis to functional or molecular imaging. Despite these promising data, the generalizability of the procedure should be confirmed especially in Japan and other Asian countries, where the current diagnostic yield for GI luminal diseases is high. Given the high cost of CLE devices, cost-benefit analysis should also be considered. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

Bolhuis J.J.,University Utrecht | Okanoya K.,RIKEN | Okanoya K.,University of Tokyo | Scharff C.,Free University of Berlin
Nature Reviews Neuroscience | Year: 2010

Vocal imitation in human infants and in some orders of birds relies on auditory-guided motor learning during a sensitive period of development. It proceeds from 'babbling' (in humans) and 'subsong' (in birds) through distinct phases towards the full-fledged communication system. Language development and birdsong learning have parallels at the behavioural, neural and genetic levels. Different orders of birds have evolved networks of brain regions for song learning and production that have a surprisingly similar gross anatomy, with analogies to human cortical regions and basal ganglia. Comparisons between different songbird species and humans point towards both general and species-specific principles of vocal learning and have identified common neural and molecular substrates, including the forkhead box P2 (FOXP2) gene. © 2010 Macmillan Publishers Limited. All rights reserved.

Tanaka K.,University of Tokyo
Expert Systems with Applications | Year: 2010

This paper proposes a sales forecasting model for new-released products with a knowledge-based database. Though forecasting future demand is an essential part of business planning and operation, most major forecasting methods are applied only to regular consuming items, showing gradual sales trend caused by seasonal cycles. Most retail products are, however, irregular consuming products characterized by fluctuated and nonlinear sales trends. In this study, using high correlations between short- and long-term accumulated sales within similar products groups, a new forecasting model is presented. Based on the correlation database of short- and long-term accumulations, the model provides a prediction of long-term forecast using the sales result of the product's very early release. For practical use, the model is designed to deal with the following three points: accuracy; timing of forecast release; and the broad coverage of items. As a case study, we applied the model to books and consumer electronics sold in Japan. The model enables us to obtain a practical sales forecast throughout the lifecycle of the item one or two week after its release, and furthermore provides valuable information on reprint decision-making. This experiment will prove the reliability in accuracy and efficiency of the proposed method in comparison with existing established ones. © 2010 Elsevier Ltd. All rights reserved.

Kato T.,University of Tokyo
Angewandte Chemie - International Edition | Year: 2010

Self-organized channels: Molecular assembly of ionic liquid crystals has led to the formation of self-organized 1D, 2D, and 3D ionic channels. Liquid-crystal-based, mechanically stable electrolyte films have been obtained by the formation of a covalent bond network by in situ cross-linking of polymerizable nanostructured ionic liquid crystals (see picture). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Watanabe T.,University of Tokyo
Physica A: Statistical Mechanics and its Applications | Year: 2013

As exemplified by power grids and large-scale brain networks, some functions of networks consisting of phase oscillators rely on not only frequency synchronization, but also phase synchronization among the oscillators. Nevertheless, even after the oscillators reach frequency-synchronized status, the phase synchronization is not always accomplished because the phase difference among the oscillators is often trapped at non-zero constant values. Such phase difference potentially results in inefficient transfer of power or information among the oscillators, and avoids proper and efficient functioning of the networks. In the present study, we newly define synchronization cost by using the phase difference among the frequency-synchronized oscillators, and investigate the optimal network structure with the minimum synchronization cost through rewiring-based optimization. By using the Kuramoto model, we demonstrate that the cost is minimized in a network with a rich-club topology, which comprises the densely-connected center nodes and low-degree peripheral nodes connecting with the center module. We also show that the network topology is characterized by its bimodal degree distribution, which is quantified by Wolfson's polarization index. © 2012 Elsevier B.V. All rights reserved.

Kawamoto T.,University of Tokyo
Physica A: Statistical Mechanics and its Applications | Year: 2013

We introduce a stochastic model which describes the information diffusion on the network of a popular web service, Twitter. Restricting our attention to the daily diffusion from a popular account, we model the information diffusion as a random multiplicative process. We justify our model by directly observing the statistics of the multiplicative factors in the Twitter data. © 2013 Elsevier B.V. All rights reserved.

Takahashi F.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

We propose a new class of inflation models in which the coefficient of the inflaton kinetic term rapidly changes with energy scale. This naturally occurs especially if the inflaton moves over a long distance during inflation as in the case of large-scale inflation. The peculiar behavior of the kinetic term opens up a new way to construct an inflation model. As a concrete example we construct a linear inflation model in supergravity. It is straightforward to build a chaotic inflation model with a fractional power along the same line. Interestingly, the potential takes a different form after inflation because of the running kinetic term. © 2010 Elsevier B.V.

Tanji N.,University of Tokyo
Annals of Physics | Year: 2010

The time evolution of a system where a uniform and classical SU(3) color electric field and quantum fields of quarks interact with each other is studied focusing on non-perturbative pair creation and its back reaction. We characterize a color direction of an electric field in a gauge invariant way, and investigate its dependence. Momentum distributions of created quarks show plasma oscillation as well as quantum effects such as the Pauli blocking and interference. Pressure of the system is also calculated, and we show that pair creation moderates degree of anisotropy of pressure. Furthermore, enhancement of pair creation and induction of chiral charge under a color magnetic field which is parallel to an electric field are discussed. © 2010 Elsevier Inc.

Takei Y.,University of Tokyo
Journal of Geophysical Research: Solid Earth | Year: 2010

Two quasi-static loading tests one with and one without repeated changes in the principal stress directions were performed on a partially molten rock analogue. In both runs, development of stress-induced anisotropy was observed through a continuous, nondestructive monitoring of the sample microstructure using ultrasonic shear waves. The direction of the shear wave anisotropy showed that the area of the grain-to-grain contact faces whose normals are nearly parallel to the σ3 direction decreased, while the area of the other contact faces remained almost unchanged. Large viscous anisotropy caused by this microstructural anisotropy could be detected through the strong coupling between shear and isotropic stress components. The large amplitude of viscous anisotropy relative to the small amplitude of shear wave (elastic) anisotropy is consistent with the prediction from theoretical models. Amplitude and direction of this anisotropy almost synchronized with those of shear stress, indicating the existence of steady state microstructure under a given shear stress. A small hysteresis, however, was also observed, which led to a significant grain boundary wetting due to the repeated changes in the shear direction. The present results show the validity of the theoretical models for elasticity and viscosity. The coupling between shear and isotropic components produced by viscous anisotropy significantly affects the dynamics of partially molten mantle, because it enhances shear-induced melt segregation. © Copyright 2010 by the American Geophysical Union.

Obara K.,Japan National Research Institute for Earth Science and Disaster Prevention | Obara K.,University of Tokyo
Journal of Geophysical Research: Solid Earth | Year: 2010

The phenomenology of deep slow earthquakes, including low-frequency tremors, very low frequency earthquakes, and short-term slow slip events, on the subducting plate interface in southwest Japan is investigated on the basis of their spatiotemporal characteristics. The belt-like distribution of tremors is divided into segments bounded by gaps. The repetition of tremor episode depends on the magnitude of the episode, which is defined by the number of detected tremors within each episode. Major tremor episodes with a large number of detected tremors recur at an interval of approximately 6 months, accompanying the short-term slow slip events in large segments. In small segments, tremor episodes with small numbers of tremors have recurrence intervals of a few months. Some of them occasionally accompany the slight ground tilting caused by a small-size slow slip event. Even in the same segment, there exist different recurrence intervals according to the magnitude of the tremor episode. The migration pattern varies greatly in initiation, termination, direction, and speed; however, the migration direction has a general tendency for each segment. On both sides of the gap, the tremor starts next to the gap and propagates to the other side. Assuming all tremor episodes are caused by slow slip events, the equivalent moment and slip are estimated from the number of detected tremor counts and the area of each tremor episode. The equivalent slip history estimated from all tremor episodes is almost constant in each segment. This indicates that tremor activity is a good proxy for slow slips. Copyright 2010 by the American Geophysical Union.

Hepatitis C virus (HCV) infection is a major cause of liver disease. Ten to twenty percent of chronic hepatitis C will develop complications of chronic liver diseases such as liver cirrhosis and hepatocellular carcinoma. The culture system of HCV is established by the specific combination between HCV strain and a host cell. Some chimeras substituting core to NS2 into the analogous region of JFH1 strain fail to effectively replicate. Core to NS2 of HCV gene mainly encodes the structural protein of HCV virion and contributes to the virion assembly, while other regions mainly contribute to the genome replication. The balance between the virion assembly and the genome replication of chimera may differ from that of reference strain. We construct a mathematical model of the whole replication process of HCV in single infected cell. It is revealed by this model that there are two replication patterns of HCV, explosive and arrested replication. In the explosive replication, HCV can continue to exponentially reproduce its progeny. The explosive replication is caused by the effect of the positive feedback in the replication cycle. On the other hand, in the arrested replication, the replication is stalled after sufficiently long time has passed from the infection because of the depletion of the genome RNA of HCV. To avoid the arrest of replication, HCV RNA must be appropriately distributed to three distinct functions as a template for the genome replication, as a template for the translation of viral proteins and as a component of the viral particle. When the genome replication and the translation of viral proteins precede to the virion assembly, HCV can effectively replicate by explosive replication. It is suggested that some chimeras of HCV fail to effectively replicate because of the inappropriate distribution of HCV RNA to these functions. © 2012 Elsevier Ltd.

Ide S.,University of Tokyo
Journal of Geophysical Research: Solid Earth | Year: 2010

Nonvolcanic tremor is the seismically observable component of slow earthquakes, which have been recently discovered in subduction zones around the world, including major study areas at the Nankai and Cascadia subduction zones. Although tremor appears to occur randomly in both areas, Cascadia tremor has a longer duration than Nankai tremor. In the present study, this difference in tremor duration is quantified using a Brownian slow earthquake model that explains several features of tremor and slow earthquakes. A previous Brownian model is improved and applied to explain the cumulative distribution function of tremor amplitude, which is approximated by a λ2 distribution. The model also shows that the power spectrum of tremor amplitude has a simple analytic formula, including a characteristic time. An inversion method is developed to measure the characteristic time from the tremor spectrum in the presence of non-Gaussian background noise. The method is applied to several tremor sequences in the Nankai and Cascadia subduction zones to quantitatively confirm the apparent differences in tremor behavior between the two areas. The constants for Cascadia and Nankai tremor are 1000-3000 s and 100-1000 s, respectively, with temporal increases in these values observed over the course of 1-day records of activity. The difference in characteristic time between the two areas may reflect geometric constraints such as the width of the tremor region. Copyright 2010 by the American Geophysical Union.

The following four major questions were raised about my recent proposal for the possible link between the end-Guadalupian extinction and a unique geomagnetic event called the Illawarra Reversal (Isozaki, 2009a); 1) timings of extinction, cooling, and the Illawarra Reversal (end of the Kiaman Superchron), 2) geomagnetic intensity during superchrons, 3) ascent rate of mantle plume, and 4) age constraints of LIP volcanism in east Pangea. The latest research results on the Permian biodiversity change, numerical modeling of plume, and single-crystal measurement of geomagnetism support that the timings of extinction and the Illawarra Reversal, high field intensity during the Kiaman superchron, and ascent rate of plume are reasonably explained in accordance with the integrated "plume winter" scenario (Isozaki, 2009b). The onset ages of LIP volcanism need further refinement for identifying the impingement of a plume head. © 2009 International Association for Gondwana Research.

Passive feeding flows of two Devonian spiriferide brachiopods, Paraspirifer bownockeri and Cyrtospirifer sp., were examined experimentally using transparent hollow models and a flowing water tank. The models were constructed with polycarbonate plates using a vacuum heat press method. Another model of Paraspirifer with a spiral brachidium was constructed for the visualization of passive flow. The results of the ventral and dorsal directions of the hollow models suggest that outflow was generated through lateral gapes in the shell, while intake may have occurred through a sulcus gape. The passive internal flow inside the models invariably exhibited gyrating behaviour, and the axis of the rotation was similar to that of the spiral lophophore in spiriferides. Comparing the results using the hollow and backbone models indicates that the internal structures, which consisted mostly of the spiral brachidium, aided in adjusting the gyrating flows around the brachidium, even when the lateral region of the shell faced upstream. Extant terebratulides are known to generate gyrating flows around the median coils of the major feeding area, and this model best fits the relationship between the passive internal flows and the form of the lophophore. As a consequence, the shell forms of spiriferides could generate passive feeding flows from the gyrating movement surrounding the lophophore that are effective for feeding by the spiral lophophore. □. Brachiopoda, flume experiment, functional morphology, impingement feeder, physiology, suspension feeder. © 2009 The Author, Journal compilation © 2009 The Lethaia Foundation.

Yamashita M.,University of Tokyo
Angewandte Chemie - International Edition | Year: 2010

(Chemical Equation Presented) A piece of the π: A nucleophilic carbenestabilized boryl anion has been prepared by reduction (see scheme). Reactions of this boracycle indicated its nucleophilicity on a π orbital of the central boron atom. The significance of this work is presented along with a background on nucleophilic boron reagents and boracycles. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Yamamoto T.,Yokkaichi Social Insurance Hospital | Watanabe T.,University of Tokyo
World Journal of Gastroenterology | Year: 2014

Many patients with Crohn's disease (CD) require surgery. Indications for surgery include failure of medical treatment, bowel obstruction, fistula or abscess formation. The most common surgical procedure is resection. In jejunoileal CD, strictureplasty is an accepted surgical technique that relieves the obstructive symptoms, while preserving intestinal length and avoiding the development of short bowel syndrome. However, the role of strictureplasty in duodenal and colonic diseases remains controversial. In extensive colitis, after total colectomy with ileorectal anastomosis (IRA), the recurrence rates and functional outcomes are reasonable. For patients with extensive colitis and rectal involvement, total colectomy and endileostomy is safe and effective; however, a few patients can have subsequent IRA, and half of the patients will require proctectomy later. Proctocolectomy is associated with a high incidence of delayed perineal wound healing, but it carries a low recurrence rate. Patients undergoing proctocolectomy with ileal pouchanal anastomosis had poor functional outcomes and high failure rates. Laparoscopic surgery has been introduced as a minimal invasive procedure. Patients who undergo laparoscopic surgery have a more rapid recovery of bowel function and a shorter hospital stay. The morbidity also is lower, and the rate of disease recurrence is similar compared with open procedures. © 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

Mori T.,University of Tokyo
Physical Review Letters | Year: 2013

It is argued that a certain kind of short-range interacting system exhibits nonadditivity when several time scales are well separated. Under the condition of separated time scales, the system is described by the elastic spin model. We find that it is extensive but nonadditive, which is directly confirmed by the work measurement and also indicated by ensemble inequivalence. Further, we estimate the effective Hamiltonian for the spin variables, and it is clarified that the effective interaction is long ranged. Remarkably, the so-called Kac prescription, which is usually regarded as a mathematical operation to make the system extensive, naturally holds. © 2013 American Physical Society.

Saito K.,Keio University | Kato T.,University of Tokyo
Physical Review Letters | Year: 2013

We study the Kondo effect in heat transport via a local two-state system. This system is described by the spin-boson Hamiltonian with Ohmic dissipation, which can be mapped onto the Kondo model with anisotropic exchange coupling. We calculate thermal conductance by the Monte Carlo method based on the exact formula. Thermal conductance has a scaling form κ=(kB2T K/â.,?)f(α,T/TK), where TK and α indicate the Kondo temperature and dimensionless coupling strength, respectively. Temperature dependence of conductance is classified by the Kondo temperature as κâ̂?(T/TK)3 for T≠TK and κâ̂?(kBT/â.,? ωc)2α-1 for Tâ‰TK. Similarities to the Kondo signature in electric transport are discussed. © 2013 American Physical Society.

Iwatsubo T.,University of Tokyo
Alzheimer's and Dementia | Year: 2010

Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI) was launched in 2008, aiming at conducting a longitudinal workup of a standardized neuroimaging, biomarker and clinico-psychological surveys. The research protocol was designed to maximize compatibility with that of US-ADNI, including structural magnetic resonance imaging analysis for the evaluation of brain atrophy, fluorodeoxyglucose and amyloid positron emission tomography, cerebrospinal fluid sampling, APOE genotyping, together with a set of clinical and psychometric tests that were prepared to achieve the highest compatibility to those used in the United States. Japanese ADNI has recruited ∼357 participants (142 amnestic mild cognitive impairment, ∼134 normal aged and 72 mild Alzheimer's disease (AD), as of April 15, 2010). World-wide ADNI activities will establish the rigorous quantitative descriptions of the natural course of AD in its very early stages. The data, as well as the methodologies and infrastructures, will facilitate the clinical trials of disease-modifying therapies for AD using surrogate biomarkers. © 2010 The Alzheimer's Association. All rights reserved.

Noguchi H.,University of Tokyo
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

The dynamics of microcapsules in steady shear flow were studied using a theoretical approach based on three variables: the Taylor deformation parameter αD, the inclination angle θ, and the phase angle φ of the membrane rotation. It is found that the dynamic phase diagram shows a remarkable change with an increase in the ratio of the membrane shear and bending elasticities. A fluid vesicle (no shear elasticity) exhibits three dynamic modes: (i) tank treading at low viscosity ηin of internal fluid (αD and θ relaxes to constant values), (ii) tumbling (TB) at high ηin (θ rotates), and (iii) swinging (SW) at middle ηin and high shear rates γ (θ oscillates). All of three modes are accompanied by a membrane (φ) rotation. For microcapsules with low shear elasticity, the TB phase with no φ rotation and the coexistence phase of SW and TB motions are induced by the energy barrier of φ rotation. Synchronization of φ rotation with TB rotation or SW oscillation occurs with integer ratios of rotational frequencies. At high shear elasticity, where a saddle point in the energy potential disappears, intermediate phases vanish and either φ or θ rotation occurs. This phase behavior agrees with recent simulation results of microcapsules with low bending elasticity. © 2010 The American Physical Society.

Ezawa M.,University of Tokyo
Applied Physics Letters | Year: 2013

Silicene is a quantum spin-Hall insulator, which undergoes a topological phase transition into other insulators by applying external fields. We investigate transport properties of silicene nanoribbons based on the Landauer formalism. We propose to determine topological phase transitions by measuring the density of states and conductance. The conductance is quantized and changes its value when the system transforms into different phases. We show that a silicene nanoribbon near the zero energy acts as a field-effect transistor. This transistor is robust since the zero-energy edge states are topologically protected. Our findings open a way to future topological quantum devices. © 2013 AIP Publishing LLC.

The corticostriatal system is considered to be crucially involved in learning and action selection. Anatomical studies have shown that two types of corticostriatal neurons, intratelencephalic (IT) and pyramidal tract (PT) cells, preferentially project to dopamine D1 or D2 receptor-expressing striatal projection neurons, respectively. In contrast, an optogenetic study has shown that stimulation of IT axons evokes comparable responses in D1 and D2 cells and that stimulation of PT axons evokes larger responses in D1 cells. Since the optogenetic study applied brief stimulation only, however, the overall impacts of repetitive inputs remain unclear. Moreover, the apparent contradiction between the anatomical and optogenetic results remains to be resolved. I addressed these issues by using a computational approach. Specifically, I constructed a model of striatal response to cortical inputs, with parameters regarding short-term synaptic plasticity and anatomical connection strength for each connection type. Under the constraint of the optogenetic results, I then explored the parameters that best explain the previously reported paired-pulse ratio of response in D1 and D2 cells to cortical and intrastriatal stimulations, which presumably recruit different compositions of IT and PT fibers. The results indicate that 1) IT→D1 and PT→D2 connections are anatomically stronger than IT→D2 and PT→D1 connections, respectively, consistent with the previous findings, and that 2) IT→D1 and PT→D2 synapses entail short-term facilitation, whereas IT→D2 and PT→D1 synapses would basically show depression, and thereby 3) repetitive IT or PT inputs have larger overall impacts on D1 or D2 cells, respectively, supporting a recently proposed hypothesis on the roles of corticostriatal circuits in reinforcement learning. © 2014 the American Physiological Society.

Purpose:To measure progression of the visual field (VF) mean deviation (MD) index in longitudinal 10-2 VFs more accurately, by adding information from 24-2 VFs using Lasso regression.Methods:A training dataset consisted of 138 eyes from 97 patients with glaucoma or ocular hypertension and a testing dataset consisted of 40 eyes from 34 patients with glaucoma or ocular hypertension. The Lasso method was used to predict total deviation (TD) values in training patients' 10-2 VFs based on information from their 24-2 VFs (52 TD values, foveal sensitivity and mean deviation MD). Then, the MD of each patient's 10-2 VF was estimated as the average of these Lasso-predicted TD values (10-2 VF 'Lasso MD'; LMD). Finally, linear regression was applied to each testing patient's series of longitudinal 10-2 VF MDs with and without additional Lasso-derived LMDs in order to predict future MDs not included in the regression analysis. Absolute prediction errors were compared when only actual 10-2 MDs were regressed against when a combination of actual 10-2 MDs and LMDs were regressed.Results:The average absolute prediction error was significantly smaller for the novel method incorporating LMDs (range: 1.6 to 1.8 dB) compared with the standard approach (range: 1.7 to 3.4 dB) (p<0.05, ANOVA test).Conclusions:Deriving 10-2 VF MD values from 24-2 VFs improves the prediction accuracy of progression. This approach will help clinicians to predict patients' visual function in the parafoveal area. © 2013 Ryo Asaoka.

Takeuchi K.A.,University of Tokyo
Physical Review Letters | Year: 2013

This Letter reports on how the interfaces in the (1+1)-dimensional Kardar-Parisi-Zhang (KPZ) class undergo, in the course of time, a transition from the flat, growing regime to the stationary one. Simulations of the polynuclear growth model and experiments on turbulent liquid crystal reveal universal functions of the KPZ class governing this transition, which connect the distribution and correlation functions for the growing and stationary regimes. This in particular shows how interfaces realized in experiments and simulations actually approach the stationary regime, which is never attained unless a stationary interface is artificially given as an initial condition. © 2013 American Physical Society.

Ezawa M.,University of Tokyo
Physical Review Letters | Year: 2013

Silicene (a monolayer of silicon atoms) is a two-dimensional topological insulator (TI) that undergoes a topological phase transition to a band insulator under external electric field Ez. We investigate a photoinduced topological phase transition from a TI to another TI by changing its topological class by irradiating circular polarized light at fixed Ez. The band structure is modified by photon dressing with a new dispersion, where the topological property is altered. By increasing the intensity of light at E z=0, a photoinduced quantum Hall insulator is realized. Its edge modes are anisotropic chiral, in which the velocities of up and down spins are different. At Ez>Ecr with a certain critical field Ecr, a photoinduced spin-polarized quantum Hall insulator emerges. This is a new state of matter, possessing one Chern number and one-half spin-Chern numbers. We newly discover a single Dirac-cone state along a phase boundary. A distinctive hallmark of the state is that one of the two Dirac valleys is closed and the other open. © 2013 American Physical Society.

Kobayashi M.,University of Tokyo | Nitta M.,Keio University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We construct a stable domain wall ring with lump beads on it in a baby Skyrme model with a potential consisting of two terms linear and quadratic in fields. © 2013 American Physical Society.

Kato K.,University of Tokyo
Nature Structural and Molecular Biology | Year: 2016

ATX is a plasma lysophospholipase D that hydrolyzes lysophosphatidylcholine (LPC) and produces lysophosphatidic acid. To date, no ATX-inhibition-mediated treatment strategies for human diseases have been established. Here, we report anti-ATX DNA aptamers that inhibit ATX with high specificity and efficacy. We solved the crystal structure of ATX in complex with the anti-ATX aptamer RB011, at 2.0-Å resolution. RB011 binds in the vicinity of the active site through base-specific interactions, thus preventing the access of the choline moiety of LPC substrates. Using the structural information, we developed the modified anti-ATX DNA aptamer RB014, which exhibited in vivo efficacy in a bleomycin-induced pulmonary fibrosis mouse model. Our findings reveal the structural basis for the specific inhibition of ATX by the anti-ATX aptamer and highlight the therapeutic potential of anti-ATX aptamers for the treatment of human diseases, such as pulmonary fibrosis. © 2016 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.

Tanaka S.,University of Tokyo
Advances in Experimental Medicine and Biology | Year: 2010

Apopotosis of osteoclasts is regulated by the Bcl-2 family protein Bim. Bim is degraded in the course of osteoclast apoptosis, which is regulated by Caspase-3. Osteoclasts generated from caspase-3 -/- mice exhibited a shorter life span and a higher bone-resorbing activity than those generated from normal littermates. These results suggest the important role of Caspase-3-Bim axis in regulating both apoptosis and activation of osteoclasts. © Springer Science+Business Media, LLC 2010.

Mukohyama S.,University of Tokyo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We suggest a new scenario of gravitation in which gravity at the fundamental level is described by a Riemannian (i.e., locally Euclidean) theory without the notion of time. The Lorentzian metric structure and the notion of time emerge as effective properties at long distances. On the other hand, at short distances, higher derivative terms compatible with the Riemannian diffeomorphism become important and the system is described by a power-counting renormalizable Riemannian theory. © 2013 American Physical Society.

Kanai M.,University of Tokyo
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

We propose a stochastic cellular-automaton model for two-lane traffic flow based on the misanthrope process in one dimension. The misanthrope process is a stochastic process allowing for an exact steady-state solution; hence, we have an exact flow-density diagram for two-lane traffic. In addition, we introduce two parameters that indicate, respectively, driver's driving-lane preference and passing-lane priority. Due to the additional parameters, the model shows a deviation of the density ratio for driving-lane use and a biased lane efficiency in flow. Then, a mean-field approach explicitly describes the asymmetric flow by the hop rates, the driving-lane preference, and the passing-lane priority. Meanwhile, the simulation results are in good agreement with an observational data, and we thus estimate these parameters. We conclude that the proposed model successfully produces two-lane traffic flow particularly with the driving-lane preference and the passing-lane priority. © 2010 The American Physical Society.

Nakayama Y.,University of Tokyo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Supersymmetric field theories possess a rich structure in their supercurrent supermultiplets. Some symmetries are manifest in one supercurrent supermultiplet but not in the others; for instance, R symmetry is manifest in the R multiplet but not in the Ferrara-Zumino multiplet. Similarly, we argue that dilatation symmetry is manifest in the virial multiplet (also known as a variant minimal supercurrent supermultiplet in the literature). It reveals that R symmetry and dilatation symmetry are conceptually independent without further assumptions even though the superconformal symmetry connects the two. We show the structure of the virial multiplet for general renormalizable supersymmetric field theories in (1+3) dimensions to all orders in perturbation theory, and discuss the condition for the dilatation invariance (but not necessarily R symmetric nor superconformal). We present novel scale invariant trajectories with a nilpotent structure in coupling constants for nonunitary Wess-Zumino models with nonvanishing beta functions, which are, therefore, not superconformal. © 2013 American Physical Society.

Contemporary continuous-flow ventricular assist devices (CFVADs) have greatly improved patient survival for indications of bridge to transplantation (BTT) and destination therapy. In Japan, CFVAD is limited for BTT use. The waiting period for heart transplantation (HT) is long owing to donor shortage. We examined the results of CFVAD for BTT indication. Eighty-nine VAD treatments were performed among subjects whose preimplantation condition was profile 1 (n = 49) or profile 2 or 3 (n = 40). The device was the paracorporeal pulsatile Nipro VAD (n = 67) or CFVAD (n = 22). All CFVAD patients were profile 2 or 3. The median assist period was 529 days (Nipro VAD, 530; CFVAD, 528). Twenty-six patients were on the device for >2 years. Actuarial survival was 81.6%, 69.5%, and 61.1% at 1, 3, and 5 years. Survival in profile 1 was significantly worse than in profile 2 or 3. Survival of CFVAD patients was superior to that of paracorporeal VAD. Six-month mortality rate of 20% in cases before 2009 (n = 60) was dramatically improved to 3% among those after 2010 (n = 29). All patients with CFVAD were alive and discharged home. 26 patients were transplanted, 7 had been weaned from VAD and 27 were on a device. The rate of events requiring hospital admission was 0.98 per patient-year in CFVAD patients. Contemporary CFVADs have enabled advanced heart failure patients to await HT safely with an improved quality of life. The advent of CFVAD has also shifted their preimplantation condition to a less sick status. CFVADs were the safest, most reliable circulatory support devices for long-term waiting periods for the BTT indications. Copyright © 2013 Elsevier Inc. All rights reserved.

Yoshida H.,Japan National Agriculture and Food Research Organization | Nagato Y.,University of Tokyo
Journal of Experimental Botany | Year: 2011

The flower of rice diverged from those of model eudicot species such as Arabidopsis, Antirrhinum, or Petunia, and is thus of great interest in developmental and evolutionary biology. Specific to grass species, including rice, are the structural units of the inflorescence called the spikelet and floret, which comprise grass-specific peripheral organs and conserved sexual organs. Recent advances in molecular genetic studies have provided an understanding of the functions of rapidly increasing numbers of genes involved in rice flower development. The genetic framework of rice flower development is in part similar to that of model eudicots. However, rice also probably recruits specific genetic mechanisms, which probably contribute to the establishment of the specific floral architecture of rice. In this review, the molecular genetic mechanisms of rice flowering are outlined, focusing on recent information and in comparison with those of model eudicots. © 2011 The Author.

Takeshita T.,University of Tokyo
Applied Energy | Year: 2012

This paper quantitatively assesses the co-benefits of atmospheric CO2 stabilization at 400ppmv by 2100 on air pollutants emissions from road vehicles using a global energy system model treating the road transport sector in detail. It is estimated that the reduction rate of global cumulative emissions of SO2, NOx, and PM from road vehicles during the period 2020-2100 in the 400ppmv CO2 stabilization scenario compared to the no CO2 constraint scenario is 22.1%, 10.8%, and 14.4%, respectively. Such co-benefits are the largest for SO2 because biomass-derived Fischer-Tropsch products are chosen as a major alternative fuel for road transport in the former scenario and because their SO2 emission factor is zero, whereas their NOx and PM emission factors are lower than those for petroleum products only by 27% and 21%, respectively. This implies that introducing liquid biofuels would not lead to a noticeable reduction in NOx and PM emissions. Such co-benefits are the smallest for NOx. The first reason is that, except for 2100 in the no CO2 constraint scenario, heavy-duty trucks account for the largest share of global road vehicles' NOx emissions in the two scenarios throughout the time horizon. The second reason is that in each time period, heavy-duty trucks emit almost the same amount of SO2, NOx, and PM between the scenarios because of almost the same technology and fuel choices in this sector. This implies the necessity of promoting R&D for developing cost-effective low-carbon alternatives to diesel heavy-duty trucks to achieve a further reduction in global air pollutants emissions from road vehicles. © 2011 Elsevier Ltd.

Fujita T.,University of Tokyo
Hypertension | Year: 2010

Obese persons with metabolic syndrome often have associated with salt-sensitive hypertension, microalbuminuria, and cardiac dysfunction, and the plasma aldosterone level in one-third of metabolic syndrome patients is clearly elevated. Hyperaldosteronism, which may be caused at least partially by certain adipocyte-derived factors, contributes to the development of proteinuria in obese hypertensive rats, and salt loading aggravates the proteinuria and induces cardiac diastolic dysfunction because of inadequate suppression of plasma aldosterone level. However, mineralocorticoid receptor (MR) antagonists prevent salt-induced renal and cardiac damage, suggesting that aldosterone excess and a high-salt diet exert an unfavorable synergistic action on the kidney and heart. In Dahl salt-sensitive rats, however, despite appropriate suppression of plasma aldosterone with a high-salt diet, salt loading paradoxically activated renal MR signaling, and the renal injury was markedly prevented by MR antagonists. Accordingly, we discovered an alternative pathway of MR activation in which Rac1, a small GTP-binding protein, activates MRs. Salt loading activates renal Rac1 in Dahl salt-sensitive rats, and Rac1 in turn induces MR activation, which results in renal injury, and the renal injury has been found to be prevented by Rac1 inhibitors. Moreover, several metabolic syndrome-related factors induce Rac1 activation, and one of them, hyperglycemia, activates MRs via Rac1 activation. Consistent with this, Rac1 inhibitors attenuated the proteinuria and renal injury in obese hypertensive animals. Thus, both salt and obesity activate Rac1 and cause MR activation. Abnormal activation of the aldosterone/MR pathway plays a key role in the development of salt-sensitive hypertension and renal injury in metabolic syndrome. © 2010 American Heart Association, Inc.

Homma Y.,University of Tokyo
International Journal of Urology | Year: 2014

Taxonomy or nomenclature concerning interstitial cystitis and its related symptom syndromes is in a state of confusion. After analyzing the reasons for confusion in regard to three components (disease name, symptoms, Hunner's lesion), I would like to propose a new term, "hypersensitive bladder", taking after overactive bladder, as a solution. Hypersensitive bladder symptoms are defined as "increased bladder sensation, usually associated with urinary frequency and nocturia, with or without bladder pain." The proposal of hypersensitive bladder is based on: (i) it does not appear a symptom syndrome, but a disease by ending with an organ name, "bladder" (ii) it does not contain confusable symptom terms (pain and urgency), but indicates irritative symptoms including pain and urgency; and (iii) it suggests pathophysiological hyperactivity of sensory nerves. Interstitial cystitis is defined by three requirements: (i) hypersensitive bladder symptoms; (ii) bladder pathology; and (iii) no other diseases, where bladder pathology should be clearly stated either as Hunner's lesion or glomerulations after hydrodistention. Hypersensitive bladder can be used for the condition with hypersensitive bladder symptoms, but no obvious disease explaining hypersensitive bladder symptoms identified. Interstitial cystitis is a representative disease causing hypersensitive bladder symptoms, most typically with pain, but might be painless and indistinguishable from overactive bladder. Introducing hypersensitive bladder as a counter concept of overactive bladder into bladder dysfunction taxonomy will facilitate clinical practice and research progress, and attract considerable attention from the medical world. © 2014 The Japanese Urological Association.

Peritoneal carcinomatosis (PC), caused by advanced abdominal malignancies, such as those of the ovarian and gastrointestinal tracts, has an extremely poor prognosis. Intraperitoneal (IP) chemotherapy has been clinically applied for several decades, but its clinical efficacy has not been fully determined. An accumulating body of evidence suggests that cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) is the optimal treatment for selected patients with ovarian and colorectal cancers with PC. Recent studies suggest that IP administration of taxane with systemic chemotherapy in a neoadjuvant setting improves patient survival in gastric cancer with PC. The pharmacokinetics of IP-administered drugs should be primarily considered in order to optimize IP chemotherapy. Therefore, the development of specific IP drugs using newly emerging molecular targeted reagents or new drug delivery systems, such as nanomedicine or controlled absorption/release methods, is essential to improve the efficacy of IP chemotherapy. © 2014 Elsevier Ltd. All rights reserved.

Takakusaki K.,Asahikawa University | Takakusaki K.,University of Tokyo
Movement Disorders | Year: 2013

Locomotion is a purposeful, goal-directed behavior initiated by signals arising from either volitional processing in the cerebral cortex or emotional processing in the limbic system. Regardless of whether the locomotion initiation is volitional or emotional, locomotion is accompanied by automatic controlled movement processes, such as the adjustment of postural muscle tone and rhythmic limb movements. Sensori-motor integration in the brainstem and the spinal cord plays crucial roles in this process. The basic locomotor motor pattern is generated by spinal interneuronal networks, termed central pattern generators (CPGs). Responding to signals in proprioceptive and skin afferents, the spinal interneuronal networks modify the locomotor pattern in cooperation with descending signals from the brainstem structures and the cerebral cortex. Information processing between the basal ganglia, the cerebellum, and the brainstem may enable automatic regulation of muscle tone and rhythmic limb movements in the absence of conscious awareness. However, when a locomoting subject encounters obstacles, the subject has to intentionally adjust bodily alignment to guide limb movements. Such an intentional gait modification requires motor programming in the premotor cortices. The motor programs utilize one's bodily information, such as the body schema, which is preserved and updated in the temporoparietal cortex. The motor programs are transmitted to the brainstem by the corticoreticulospinal system, so that one's posture is anticipatorily controlled. These processes enable the corticospinal system to generate limb trajectory and achieve accurate foot placement. Loops from the motor cortical areas to the basal ganglia and the cerebellum can serve this purpose. © 2013 Movement Disorder Society.

Czerny M.,Tohoku University | Takahashi F.,Tohoku University | Takahashi F.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We propose a multi-natural inflation model in which the single-field inflaton potential consists of two or more sinusoidal potentials that are comparable in size but have different periodicity with a possible non-zero relative phase. The model is versatile enough to realize both large-field and small-field inflation. We show that, in a model with two sinusoidal potentials, the predicted values of the spectral index and tensor-to-scalar ratio lie within the 1. σ region of the Planck data. In particular, there is no lower bound on the decay constants in contrast to the original natural inflation. We also show that, in a certain limit, multi-natural inflation can be approximated by a hilltop quartic inflation model. © 2014 The Authors.

Lin C.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In this paper, we consider the spatial gauge symmetries spontaneously breaking down in GR, and graviton becoming massive on this spatial condensate background. Such a model can be considered as a simplest example of massive gravity. We then apply our massive gravity theory to inflation, and find that the graviton mass removes the IR divergence of the inflationary loop diagram. © 2014 .

Kuroda K.,University of Tokyo
Classical and Quantum Gravity | Year: 2010

LCGT shall be planned to be the first-generation detector with an advanced technique for employing a cryogenic mirror in order to firstly detect a gravitational wave, and after detection, the detector will serve as an astronomical tool to observe the Universe through gravitational wave radiation. In collaborative observation with the LIGO, GEO and Virgo projects, LCGT desires to contribute to the enterprise of detecting gravitational wave events by earlier funding. This paper summarizes the LCGT project. © 2010 IOP Publishing Ltd.

Hasegawa Y.,University of Tokyo
Nature Physics | Year: 2010

How thin can superconducting materials be and still retain their superconductivity? A recent study of thin films grown on silicon substrates reveals that one atomic layer is the limit. © 2010 Macmillan Publishers Limited. All rights reserved.

Nagaosa N.,University of Tokyo | Nagaosa N.,RIKEN | Sinova J.,Texas A&M University | Sinova J.,ASCR Institute of Physics Prague | And 3 more authors.
Reviews of Modern Physics | Year: 2010

The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a tentative global view of the AHE is proposed which summarizes the roles played by intrinsic and extrinsic contributions in the disorder strength versus temperature plane. Finally outstanding issues and avenues for future investigation are discussed. © 2010 The American Physical Society.

Ogawa S.,University of Tokyo
Geriatrics and Gerontology International | Year: 2014

Age-related cognitive decline is a main predictor of disability among elderly people, and with the continued expansion of the aging population and the increase in life expectancy, the prevalence of mild cognitive impairment and dementia represented by Alzheimer's disease (AD), which is a multifactorial neurodegenerative disorder of older adults, have increased. Recent epidemiological and observational studies suggest a relationship exists between lifestyle factors, including nutrition and diet, and cognitive function in aging adults. It is also suggested that malnutrition and nutrient deficiencies are associated with cognitive decline in patients with dementia. There are a variety of nutritional factors, including nutritional status and dietary patterns, that might be associated with cognitive function, and specific micronutrients and dietary components have been suggested to have an association with cognitive function as well. Based on these findings and evidence, evaluation of nutritional state, as well as nutritional intervention, might be able to play a role in the management and prevention of dementia. © 2014 Japan Geriatrics Society.

Hayata T.,University of Tokyo | Hayata T.,RIKEN | Hidaka Y.,RIKEN
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We discuss spontaneous breaking of continuum symmetries, whose generators do explicitly depend on the spacetime coordinates. We clarify the relation between broken symmetries and elastic variables at both zero and finite temperatures, and/or finite densities, and show the general counting rule that is model-independently determined by the symmetry breaking pattern. We apply it to three intriguing examples: rotational, conformal, and gauge symmetries. © 2014 Elsevier B.V.

Furrer F.,University of Tokyo
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

A big challenge in continuous-variable quantum key distribution is to prove security against arbitrary coherent attacks including realistic assumptions such as finite-size effects. Recently, such a proof has been presented in [Phys. Rev. Lett. 109, 100502 (2012)PRLTAO0031-900710.1103/PhysRevLett.109.100502] for a two-mode squeezed state protocol based on a novel uncertainty relation with quantum memories. But the transmission distances were fairly limited due to a direct reconciliation protocol. We prove here security against coherent attacks of a reverse-reconciliation protocol under similar assumptions but allowing distances of over 16 km for experimentally feasible parameters. We further clarify the limitations when using the uncertainty relation with quantum memories in security proofs of continuous-variable quantum key distribution. © 2014 American Physical Society.

Flachi A.,University of Lisbon | Fukushima K.,University of Tokyo
Physical Review Letters | Year: 2014

We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum, a mass-gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass-gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition. © 2014 American Physical Society.

Hoshino S.,University of Tokyo | Kuramoto Y.,Tohoku University
Physical Review Letters | Year: 2014

Emergence of odd-frequency s-wave superconductivity is demonstrated in the two-channel Kondo lattice by means of the dynamical mean-field theory combined with the continuous-time quantum Monte Carlo method. Around half filling of the conduction bands, divergence of an odd-frequency pairing susceptibility is found, which signals instability toward the superconductivity. The corresponding order parameter is equivalent to a staggered composite-pair amplitude with even frequencies, which involves both localized spins and conduction electrons. A model wave function is constructed for the composite order with the use of symmetry operations such as charge conjugation and channel rotations. Given a certain asymmetry of the conduction bands, another s-wave superconductivity is found that has a uniform order parameter. The Kondo effect in the presence of two channels is essential for both types of unconventional superconductivity. © 2014 American Physical Society.

Yang B.-J.,RIKEN | Nagaosa N.,RIKEN | Nagaosa N.,University of Tokyo
Physical Review Letters | Year: 2014

Because of the recent development of thin film and artificial superstructure growth techniques, it is possible to control the dimensionality of the system, smoothly between two and three dimensions. In this Letter we unveil the dimensional crossover of emergent topological phenomena in correlated topological materials. In particular, by focusing on the thin film of pyrochlore iridate antiferromagnets grown along the [111] direction, we demonstrate that the thin film can have a giant anomalous Hall conductance, proportional to the thickness of the film, even though there is no Hall effect in 3D bulk material. Moreover, in the case of ultrathin films, a quantized anomalous Hall conductance can be observed, despite the fact that the system is an antiferromagnet. In addition, we uncover the emergence of a new topological phase, the nontrivial topological properties of which are hidden in the bulk insulator and manifest only in thin films. This shows that the thin film of correlated topological materials is a new platform to search for unexplored novel topological phenomena. © 2014 American Physical Society.

Matsumoto K.,University of Minnesota | Yokoyama Y.,University of Tokyo
Global Biogeochemical Cycles | Year: 2013

A rapid reduction in the Atlantic meridional overturning circulation (AMOC) can significantly disrupt the global heat transport and likely triggered abrupt climate change during the last glacial cycle. A slowdown in AMOC has long been assumed to inhibit the exchange of carbon between the atmosphere and the deep ocean and thus cause radiocarbon (14C), which is produced in the atmosphere, to accumulate in the atmosphere. Indeed previous model studies have demonstrated that a reduction in AMOC leads to higher atmospheric 14C abundance (Δ14C). However, this seems inconsistent with the observed rise in atmospheric pCO2 during Heinrich 1 and the Younger Dryas stadial events and the emerging view that this CO2 rise resulted from the deep ocean venting "old" carbon. Using an Earth system model, we offer an alternative scenario that AMOC slowdown and an accompanying dynamical response in the south (i.e., the bipolar seesaw) can in fact lead to a decline in atmospheric Δ14C. This decline is realized in the model when the bipolar seesaw and thus the flux of old carbon from the Southern Ocean are sufficiently large so as to overcome the accumulation of 14C in the atmosphere as AMOC is reduced. The bipolar seesaw we describe invokes an oceanic teleconnection, whereby a freshwater perturbation in the North Atlantic drives a southern Δ14C response, but this does not necessarily preclude an atmospheric teleconnection. ©2013. American Geophysical Union. All Rights Reserved.

Akita K.,University of Tokyo
PloS one | Year: 2013

The spatial distribution of plant stomata is a model system to study epidermal cell pattern formation. Molecular genetic approaches have identified several key genes required for stomatal distribution patterning, but environmental conditions that perturb the stomatal spacing distribution have not yet been identified. We found that immersing hydroponic cultures in 1-5% sucrose solution induced abnormally clustered stomata in the cotyledons of Arabidopsis seedlings. Clustered stomata were also induced by treatment with glucose or fructose solution but not by mannitol solution, suggesting that osmotic stress was not a cause of the disturbed stomatal patterns. Stomatal lineage cell-specific enhancer trap lines revealed that the sugar solution treatment led to ectopic expression of stomatal lineage cell-specific genes in non-stomatal lineage cells. Aniline blue staining also showed that there was reduced deposition of callose, a plant cell wall component, in new cell walls during formation of stomatal precursor cells (meristemoids). These results suggested that the immersion treatment with sugar solution permitted ectopic guard cell differentiation through dysfunction of the cell wall dividing stomatal- and non-stomatal lineage cells. Our simple induction system for clustered stomata provides a suitable tool for further studies to investigate the one-cell-spacing rule during plant stomatal development.

To degrade the polysaccharides, wood-decay fungi secrete a variety of glycoside hydrolases (GHs) and carbohydrate esterases (CEs) classified into various sequence-based families of carbohydrate-active enzymes (CAZys) and their appended carbohydrate-binding modules (CBM). Oxidative enzymes, such as cellobiose dehydrogenase (CDH) and lytic polysaccharide monooxygenase (LPMO, formerly GH61), also have been implicated in cellulose degradation. To examine polysaccharide-degrading potential between white- and brown-rot fungi, we performed genomewide analysis of CAZys and these oxidative enzymes in 11 Polyporales, including recently sequenced monokaryotic strains of Bjerkandera adusta, Ganoderma sp. and Phlebia brevispora. Furthermore, we conducted comparative secretome analysis of seven Polyporales grown on wood culture. As a result, it was found that genes encoding cellulases belonging to families GH6, GH7, GH9 and carbohydrate-binding module family CBM1 are lacking in genomes of brown-rot polyporales. In addition, the presence of CDH and the expansion of LPMO were observed only in white-rot genomes. Indeed, GH6, GH7, CDH and LPMO peptides were identified only in white-rot polypores. Genes encoding aldose 1-epimerase (ALE), previously detected with CDH and cellulases in the culture filtrates, also were identified in white-rot genomes, suggesting a physiological connection between ALE, CDH, cellulase and possibly LPMO. For hemicellulose degradation, genes and peptides corresponding to GH74 xyloglucanase, GH10 endo-xylanase, GH79 β-glucuronidase, CE1 acetyl xylan esterase and CE15 glucuronoyl methylesterase were significantly increased in white-rot genomes compared to brown-rot genomes. Overall, relative to brown-rot Polyporales, white-rot Polyporales maintain greater enzymatic diversity supporting lignocellulose attack.

Maeda K.,Tokyo Institute of Technology | Maeda K.,Japan Science and Technology Agency | Domen K.,University of Tokyo
Angewandte Chemie - International Edition | Year: 2012

Tripping the light fantastic: Despite small band gap energies (1.7-1.8 eV), BaZrO3-BaTaO2N solid solutions (Zr/Ta<0.1) are capable of photocatalyzing both water oxidation and reduction even under irradiation above 660 nm. Solar water splitting to form H2 and O2 was also demonstrated using a photoelectrochemical cell consisting of a BaZrO 2N solid solution as an anode and a Pt wire cathode. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Masuda K.,University of Tokyo
Astrophysical Journal | Year: 2015

Analysis of the transit light curve deformed by the stellar gravity darkening allows us to photometrically measure both components of the spin-orbit angle ψ, its sky projection λ and inclination of the stellar spin axis i∗. In this paper, we apply the method to two transiting hot Jupiter systems monitored with the Kepler spacecraft, Kepler-13A and HAT-P-7. For Kepler-13A, we find i∗ = 81° ± 5° and ψ = 60° ± 2° adopting the spectroscopic constraint λ = 58°.6 ± 2°.0 by Johnson et al. In our solution, the discrepancy between the above λ and that previously reported by Barnes et al. is solved by fitting both of the parameters in the quadratic limb-darkening law. We also report the temporal variation in the orbital inclination of Kepler-13Ab, d|cos iorb|/dt=(-7.0 ± 0.4) × 10-6 days-1, providing further evidence for the spin-orbit precession in this system. By fitting the precession model to the time series of iorb, λ, and i∗ obtained with the gravity-darkened model, we constrain the stellar quadrupole moment J2 = (6.1 ± 0.3) × 10-5 for our new solution, which is several times smaller than J2 = (1.66 ± 0.08) × 10-4 obtained for the previous one. We show that the difference can be observable in the future evolution of λ, thus providing a possibility to test our solution with follow-up observations. The second target, HAT-P-7, is the first F-dwarf star analyzed with the gravity-darkening method. Our analysis points to a nearly pole-on configuration with ψ = 101° ± 2° or 87° ± 2° and the gravity-darkening exponent β consistent with 0.25. Such an observational constraint on β can be useful for testing the theory of gravity darkening. © 2015. The American Astronomical Society. All rights reserved.

Shirasaki M.,University of Tokyo
Astrophysical Journal | Year: 2015

We propose a novel method to select satellite galaxies in outer regions of galaxy groups or clusters using weak gravitational lensing. The method is based on the theoretical expectation that the tangential shear pattern around satellite galaxies would appear with negative values at an offset distance from the center of the main halo. We can thus locate the satellite galaxies statistically with an offset distance of several lensing smoothing scales by using the standard reconstruction of surface mass density maps from weak lensing observation. We test the idea using high-resolution cosmological simulations. We show that subhalos separated from the center of the host halo are successfully located even without assuming the position of the center. For a number of such subhalos, the characteristic mass and offset length can be also estimated on a statistical basis. We perform a Fisher analysis to show how well upcoming weak lensing surveys can constrain the mass density profile of satellite galaxies. In the case of the Large Synoptic Survey Telescope with a sky coverage of 20,000 deg2, the mass of the member galaxies in the outer region of galaxy clusters can be constrained with an accuracy of ∼0.1 dex for galaxy clusters with mass 1014 h-1 M⊙ at z = 0.15. Finally we explore the detectability of tidal stripping features for subhalos having a wide range of masses of 1011-1013 h-1 M⊙. © 2015. The American Astronomical Society. All rights reserved.

Nose A.,University of Tokyo
Frontiers in Molecular Neuroscience | Year: 2012

The Drosophila larval neuromuscular system is one of the best-characterized model systems for axon targeting. In each abdominal hemisegment, only 36 identified motor neurons form synaptic connections with just 30 target muscles in a highly specific and stereotypic manner. Studies in the 1990s identified several cell-surface and secreted proteins that are expressed in specific muscles and contribute to target specificity. Emerging evidence suggests that target selection is determined not only by attraction to the target cells but also by exclusion from non-target cells. Proteins with leucine-rich repeats (LRR proteins) appear to be a major molecular family of proteins responsible for the targeting. While the demonstrated roles of the target-derived cues point to active recognition by presynaptic motor neurons, postsynaptic muscles also reach out and recognize specific motor neurons by sending out cellular protrusions called myopodia. Simultaneous live imaging of myopodia and growth cones has revealed that local and mutual recognition at the tip of myopodia is critical for selective synapse formation. A large number of candidate target cues have been identified on a single muscle, suggesting that target specificity is determined by the partially redundant and combinatorial function of multiple cues. Analyses of the seemingly simple neuromuscular system in Drosophila have revealed an unexpected complexity in the mechanisms of axon targeting. © 2012 Nose.

Bambi C.,Ludwig Maximilians University of Munich | Bambi C.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

In 4-dimensional General Relativity, black holes are described by the Kerr solution and are subject to the bound |a*|≤1, where a* is the black hole spin parameter. If current black hole candidates are not the black holes predicted in General Relativity, this bound does not hold and a* might exceed 1. In this Letter, I relax the Kerr black hole hypothesis and I find that the value of the spin parameter of the super-massive black hole candidates in galactic nuclei cannot be higher than about 1.2. A higher spin parameter would not be consistent with a radiative efficiency η>0.15, as observed at least for the most luminous AGN. While a rigorous proof is lacking, I conjecture that the bound |a*|≲1.2 is independent of the exact nature of these objects. © 2011 Elsevier B.V.

Okada N.,University of Tokyo
Molecular Psychiatry | Year: 2016

Subcortical structures, which include the basal ganglia and parts of the limbic system, have key roles in learning, motor control and emotion, but also contribute to higher-order executive functions. Prior studies have reported volumetric alterations in subcortical regions in schizophrenia. Reported results have sometimes been heterogeneous, and few large-scale investigations have been conducted. Moreover, few large-scale studies have assessed asymmetries of subcortical volumes in schizophrenia. Here, as a work completely independent of a study performed by the ENIGMA consortium, we conducted a large-scale multisite study of subcortical volumetric differences between patients with schizophrenia and controls. We also explored the laterality of subcortical regions to identify characteristic similarities and differences between them. T1-weighted images from 1680 healthy individuals and 884 patients with schizophrenia, obtained with 15 imaging protocols at 11 sites, were processed with FreeSurfer. Group differences were calculated for each protocol and meta-analyzed. Compared with controls, patients with schizophrenia demonstrated smaller bilateral hippocampus, amygdala, thalamus and accumbens volumes as well as intracranial volume, but larger bilateral caudate, putamen, pallidum and lateral ventricle volumes. We replicated the rank order of effect sizes for subcortical volumetric changes in schizophrenia reported by the ENIGMA consortium. Further, we revealed leftward asymmetry for thalamus, lateral ventricle, caudate and putamen volumes, and rightward asymmetry for amygdala and hippocampal volumes in both controls and patients with schizophrenia. Also, we demonstrated a schizophrenia-specific leftward asymmetry for pallidum volume. These findings suggest the possibility of aberrant laterality in neural pathways and connectivity patterns related to the pallidum in schizophrenia.Molecular Psychiatry advance online publication, 19 January 2016; doi:10.1038/mp.2015.209. © 2016 Macmillan Publishers Limited

Nozaki M.,Kyoto University | Numasawa T.,Kyoto University | Takayanagi T.,Kyoto University | Takayanagi T.,University of Tokyo
Physical Review Letters | Year: 2014

We introduce a series of quantities which characterize a given local operator in any conformal field theory from the viewpoint of quantum entanglement. It is defined by the increased amount of (Rényi) entanglement entropy at late time for an excited state defined by acting the local operator on the vacuum. We consider a conformal field theory on an infinite space and take the subsystem in the definition of the entanglement entropy to be its half. We calculate these quantities for a free massless scalar field theory in two, four and six dimensions. We find that these results are interpreted in terms of quantum entanglement of a finite number of states, including Einstein-Podolsky-Rosen states. They agree with a heuristic picture of propagations of entangled particles. © 2014 American Physical Society.

Kawaguchi Y.,University of Tokyo
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We apply the number-conserving Bogoliubov theory to spinor Bose-Einstein condensates and show that the Goldstone magnon causes instability leading to fragmentation. Unlike the dynamical instability, where modes with complex eigenfrequencies grow exponentially, here the zero-energy mode exhibits algebraic growth. We also point out that a small fraction of thermally excited atoms enhances the fragmentation dynamics. © 2014 American Physical Society.

de Felice A.,Naresuan University | Mukohyama S.,University of Tokyo
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We present the first example of a unitary theory of Lorentz-invariant massive gravity, with all degrees of freedom propagating on a strictly homogeneous and isotropic, self-accelerating de Sitter background. The theory is a simple extension of the quasidilaton theory, respecting the symmetry of the original theory but allowing for a new type of coupling between the massive graviton and the quasidilaton scalar. © 2013 The Authors. Published by Elsevier B.V.

Intracellular configuration is an important feature of cell status. Recent advances in microscopic imaging techniques allow us to easily obtain a large number of microscopic images of intracellular structures. In this circumstance, automated microscopic image recognition techniques are of extreme importance to future phenomics/visible screening approaches. However, there was no benchmark microscopic image dataset for intracellular organelles in a specified plant cell type. We previously established the Live Images of Plant Stomata (LIPS) database, a publicly available collection of optical-section images of various intracellular structures of plant guard cells, as a model system of environmental signal perception and transduction. Here we report recent updates to the LIPS database and the establishment of a database table, LIPService. We updated the LIPS dataset and established a new interface named LIPService to promote efficient inspection of intracellular structure configurations. Cell nuclei, microtubules, actin microfilaments, mitochondria, chloroplasts, endoplasmic reticulum, peroxisomes, endosomes, Golgi bodies, and vacuoles can be filtered using probe names or morphometric parameters such as stomatal aperture. In addition to the serial optical sectional images of the original LIPS database, new volume-rendering data for easy web browsing of three-dimensional intracellular structures have been released to allow easy inspection of their configurations or relationships with cell status/morphology. We also demonstrated the utility of the new LIPS image database for automated organelle recognition of images from another plant cell image database with image clustering analyses. The updated LIPS database provides a benchmark image dataset for representative intracellular structures in Arabidopsis guard cells. The newly released LIPService allows users to inspect the relationship between organellar three-dimensional configurations and morphometrical parameters.

Gamo T.,University of Tokyo
TrAC - Trends in Analytical Chemistry | Year: 2011

The Sea of Japan, a semi-closed marginal sea (greatest depth ~3700m) in the northwestern-most Pacific Ocean, has an independent, deep convection system, which is driven by the formation and the sinking of cool, saline surface water towards the bottom in severe winters. Continuous measurement of dissolved oxygen using highly precise versions of the Winkler titration method has revealed 8-10% decreases in the bottom concentration of oxygen (O2) over the past 30years. The temporal decrease in O2 means an imbalance between the supply of O2 from the surface and the in situ consumption of O2 in decomposing organic matter, suggesting that the change in the deep convection pattern of the Sea of Japan is probably caused by global climate change to reduce winter cooling of surface seawater. © 2011 Elsevier Ltd.

Satake K.,University of Tokyo
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2015

Great (M∼8) earthquakes repeatedly occur along the subduction zones around Japan and cause fault slip of a few to several metres releasing strains accumulated from decades to centuries of plate motions. Assuming a simple 'characteristic earthquake'model that similar earthquakes repeat at regular intervals, probabilities of future earthquake occurrence have been calculated by a government committee. However, recent studies on past earthquakes including geological traces from giant (M∼9) earthquakes indicate a variety of size and recurrence interval of interplate earthquakes. Along the Kuril Trench off Hokkaido, limited historical records indicate that average recurrence interval of great earthquakes is approximately 100 years, but the tsunami deposits show that giant earthquakes occurred at a much longer interval of approximately 400 years. Along the Japan Trench off northern Honshu, recurrence of giant earthquakes similar to the 2011 Tohoku earthquake with an interval of approximately 600 years is inferred from historical records and tsunami deposits. Along the Sagami Trough near Tokyo, two types of Kanto earthquakes with recurrence interval of a few hundred years and a few thousand years had been recognized, but studies show that the recent three Kanto earthquakes had different source extents. Along the Nankai Trough off western Japan, recurrence of great earthquakes with an interval of approximately 100 years has been identified from historical literature, but tsunami deposits indicate that the sizes of the recurrent earthquakes are variable. Such variability makes it difficult to apply a simple 'characteristic earthquake' model for the long-term forecast, and several attempts such as use of geological data for the evaluation of future earthquake probabilities or the estimation of maximum earthquake size in each subduction zone are being conducted by government committees. Copyright © 2015 The Author(s) Published by the Royal Society.

Asano K.,University of Tokyo | Meszaros P.,Pennsylvania State University
Astrophysical Journal | Year: 2014

We revisit the neutrino and ultra-high-energy cosmic-ray (UHECR) production from gamma-ray bursts (GRBs) with time-dependent simulations for the proton-induced cascades. This method can generate self-consistent photon, neutrino, and escaped neutron spectra. To obtain the integrated background spectra, we take into account the distributions of the burst luminosity and pulse duration timescale. A benchmark case with standard GRB luminosity function, a bulk Lorentz factor Γ = 300, and a proton to gamma-ray luminosity fraction fp = 10 is consistent with both the neutrino upper limits and the observed UHECR intensity at 1020 eV, while requiring a different type of UHECR source at the ankle. For the benchmark case, the GRBs in the bright end of the luminosity function, which contribute most of the neutrinos, have their photon spectrum substantially distorted by secondary photons. Such bright GRBs are few in number, and reducing their fp eliminates the distortion and reduces the neutrino production. Even if we neglect the contribution of the brightest GRBs, the UHECR production rate at energies corresponding to the Greisen-Zatsepin-Kuzmin limit is almost unchanged. These nominal GRB models, especially with L iso ≲ 1053 erg s -1, appear to meet the current constraints as far as being candidate UHECR sources above the ankle energy. © 2014. The American Astronomical Society. All rights reserved..

Recent developments in small-angle neutron scattering (SANS) investigations on polymer gels are reviewed by encompassing (i) volume phase transition and microphase separation, (ii) inhomogeneities in polymer gels, (iii) pressure dependence of hydrophobic interaction and (iv) structural characterization of super-tough gels. These developments owe much to the understanding of gel inhomogeneities and advances in the precision analyses of SANS, such as the contrast variation method coupled with singular value decomposition and the accurate evaluation of incoherent scattering intensity. As one of the fruitful outcomes, deformation mechanisms in various types of super-tough gels are elucidated. © The Society of Polymer Science, Japan (SPSJ). All rights reserved.

Kikuchi K.,University of Tokyo
IEICE Electronics Express | Year: 2011

The recently-developed digital coherent receiver enables us to employ a variety of spectrally-efficient modulation formats such as M-ary phase-shift keying (PSK) and quadrature-amplitude modulation (QAM). Moreover, in the digital domain, we can equalize linear transmission impairments, which may stem from group-velocity dispersion (GVD) and polarization-mode dispersion (PMD) of fibers for transmission, because the phase information is preserved after coherent detection. This paper reviews the history of coherent optical communications, the principle of coherent detection, and the concept of the digital coherent receiver. After that, we discuss digital signal processing (DSP) for mitigating transmission impairments, coherent transmission characteristics of multi-level optical signals, and future prospects of coherent optical communications. © IEICE 2011.

Furusawa C.,RIKEN | Kaneko K.,University of Tokyo
Physical Review Letters | Year: 2012

A simple cell model consisting of a catalytic reaction network is studied to show that cellular states are self-organized in a critical state for achieving optimal growth; we consider the catalytic network dynamics over a wide range of environmental conditions, through the spontaneous regulation of nutrient transport into the cell. Furthermore, we find that the adaptability of cellular growth to reach a critical state depends only on the extent of environmental changes, while all chemical species in the cell exhibit correlated partial adaptation. These results are in remarkable agreement with the recent experimental observations of the present cells. © 2012 American Physical Society.

Herry C.,French Institute of Health and Medical Research | Johansen J.P.,RIKEN | Johansen J.P.,University of Tokyo
Nature Neuroscience | Year: 2014

How sensory information is transformed by learning into adaptive behaviors is a fundamental question in neuroscience. Studies of auditory fear conditioning have revealed much about the formation and expression of emotional memories and have provided important insights into this question. Classical work focused on the amygdala as a central structure for fear conditioning. Recent advances, however, have identified new circuits and neural coding strategies mediating fear learning and the expression of fear behaviors. One area of research has identified key brain regions and neuronal coding mechanisms that regulate the formation, specificity and strength of fear memories. Other work has discovered critical circuits and neuronal dynamics by which fear memories are expressed through a medial prefrontal cortex pathway and coordinated activity across interconnected brain regions. Here we review these recent advances alongside prior work to provide a working model of the extended circuits and neuronal coding mechanisms mediating fear learning and memory. © 2014 Nature America, Inc. All rights reserved.

We discuss two anomalous features of interlayer magnetotransport observed in α-(BEDT-TTF) 2I 3 in terms of massless Dirac fermions: the interlayer Hall effect and high-field interlayer magnetoresistance (MR). The former is the anomalous Hall effect, which does not depend on magnetic field strength. It depends only on field orientation showing cotθ-type angle dependence. We have derived the lowest order contribution of interlayer coupling to conductivity and successfully reproduced the interlayer Hall effect as a transport phenomenon in the massless Dirac fermion system at the quantum limit. The latter is an exponential increase of interlayer MR and its follow-on saturation in higher magnetic fields. The exponential increase is evidence of the existence of a mobility gap at the Fermi level. It strongly suggests that the ν=0 quantum Hall state is realized by spin splitting. In this case, two edge states with opposite spin and chirality are formed on the edge surface. The surface transport via edge states becomes dominant in interlayer transport in high enough fields, where bulk transport becomes exponentially small. The observed saturation of interlayer MR is well explained with this scenario. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shibata K.,University of Tokyo
Nature Nanotechnology | Year: 2015

Mechanical control of magnetism is an important and promising approach in spintronics. To date, strain control has mostly been demonstrated in ferromagnetic structures by exploiting a change in magnetocrystalline anisotropy. It would be desirable to achieve large strain effects on magnetic nanostructures. Here, using in situ Lorentz transmission electron microscopy, we demonstrate that anisotropic strain as small as 0.3% in a chiral magnet of FeGe induces very large deformations in magnetic skyrmions, as well as distortions of the skyrmion crystal lattice on the order of 20%. Skyrmions are stabilized by the Dzyaloshinskii–Moriya interaction, originating from a chiral crystal structure. Our results show that the change in the modulation of the strength of this interaction is amplified by two orders of magnitude with respect to changes in the crystal lattice due to an applied strain. Our findings may provide a mechanism to achieve strain control of topological magnetic structures based on the Dzyaloshinskii–Moriya interaction. © 2015 Nature Publishing Group

Sasa S.-I.,University of Tokyo
Physical Review Letters | Year: 2012

Pure glass is defined as a thermodynamic phase in which typical equilibrium particle configurations have macroscopic overlaps with one of some special irregular configurations. By employing 128 types of artificial molecules, a pure glass model is constructed in the cubic lattice. © 2012 American Physical Society.