Ohshima H.,Tokyo University of Science
Current Opinion in Colloid and Interface Science | Year: 2013
A review is given on the recent developments of theories of electrokinetics of soft particles (i.e., hard particles covered with an ion-penetrable surface layer of polyelectrolytes) with particular emphasis on the electrophoretic relaxation effects for highly charged soft particles and the effects of inhomogeneous distribution of polymer segments in the surface layer. The electrostatic interaction between soft particles is also discussed. Not only the interaction before contact of the surface layers of the interacting particles but also the interaction after their contact is considered. © 2013 Elsevier Ltd.
Tsujikawa S.,Tokyo University of Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
We study the possibility of realizing a growth rate of matter density perturbations lower than that in general relativity. Using the approach of the effective field theory of modified gravity encompassing theories beyond Horndeski, we derive the effective gravitational coupling Geff and the gravitational slip parameter η for perturbations deep inside the Hubble radius. In Horndeski theories we derive a necessary condition for achieving weak gravity associated with tensor perturbations, but this is not a sufficient condition due to the presence of a scalar-matter interaction that always enhances Geff. Beyond the Horndeski domain it is possible to realize Geff smaller than Newton's gravitational constant G, while the scalar and tensor perturbations satisfy no-ghost and stability conditions. We present a concrete dark energy scenario with varying ct and numerically study the evolution of perturbations to confront the model with the observations of redshift-space distortions and weak lensing. © 2015 American Physical Society.
Kneller R.,Tokyo University of Science
Nature Reviews Drug Discovery | Year: 2010
Understanding the factors that promote drug innovation is important both for improvements in health care and for the future of organizations engaged in drug discovery research and development. By identifying the inventors of 252 new drugs approved by the US Food and Drug Administration from 1998 to 2007 and their places of work, and also classifying these drugs according to innovativeness, this study investigates the contribution of different types of organizations and regions to drug innovation during this period. The data indicate that drugs initially discovered in biotechnology companies or universities accounted for approximately half of the scientifically innovative drugs approved, as well as half of those that responded to unmet medical needs, although their contribution to the total number of new drugs was proportionately lower. The biotechnology companies were located mainly in the United States. This article presents a comprehensive analysis of these data and discusses potential contributing factors to the trends observed, with the aim of aiding efforts to promote drug innovation. © 2010 Macmillan Publishers Limited. All rights reserved.
Abuki H.,Tokyo University of Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014
We investigate the influence of the isospin asymmetry on the phase structure of quark matter near the chiral critical point systematically using a generalized version of Ginzburg-Landau approach. The effect has proven to be so profound that it brings about not only a shift of the critical point but also a rich variety of phases in its neighborhood. In particular, there shows up a phase with spatially varying charged pion condensate which we name the "solitonic pion condensate" in addition to the "chiral defect lattice" where the chiral condensate is partially destructed by periodic placements of two-dimensional wall-like defects. Our results suggest that there may be an island of solitonic pion condensate in the low temperature and high density side of QCD phase diagram. © 2013 The Author.
Tsujikawa S.,Tokyo University of Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
A field kinetic coupling with the Einstein tensor leads to a gravitationally enhanced friction during inflation, by which even steep potentials with theoretically natural model parameters can drive cosmic acceleration. In the presence of this nonminimal derivative coupling, we place observational constraints on a number of representative inflationary models such as chaotic inflation, inflation with exponential potentials, natural inflation, and hybrid inflation. We show that most of the models can be made compatible with the current observational data mainly due to the suppressed tensor-to-scalar ratio. © 2012 American Physical Society.