Ramond-Ramond couplings of D-branes

Applying supersymmetric localization for superstring worldsheet theory with N=(1,1) supersymmetries on a cylinder and with arbitrary boundary interactions, we find the most general formula for the Ramond-Ramond (RR) coupling of D-branes. We allow all massive excitations of open superstrings, and find that only a finite number of them can contribute to the formula. The formula is written by Quillen's superconnection which includes higher form gauge fields, and the resultant general Chern-Simons terms are consistent with RR charge quantization. Applying the formula to boundary string field theory of a BPS D9-brane or a D9-antiD9 brane system, we find that any D9-brane creation via massive mode condensation is impossible.Comment: 24 pages, 1 figur

Impact of prenatal environmental stress on cortical development

Prenatal exposure of the developing brain to various types of environmental stress increases susceptibility to neuropsychiatric disorders such as autism, attention deficit hyperactivity disorder and schizophrenia. Given that even subtle perturbations by prenatal environmental stress in the cerebral cortex impair the cognitive and memory functions, this review focuses on underlying molecular mechanisms of pathological cortical development. We especially highlight recent works that utilized animal exposure models, human specimens or/and induced Pluripotent Stem (iPS) cells to demonstrate: 1. molecular mechanisms shared by various types of environmental stressors, 2. the mechanisms by which the affected extracortical tissues indirectly impact the cortical development and function, and 3. interaction between prenatal environmental stress and the genetic predisposition of neuropsychiatric disorders. Finally, we discuss current challenges for achieving a comprehensive understanding of the role of environmentally disturbed molecular expressions in cortical maldevelopment, knowledge of which may eventually facilitate discovery of interventions for prenatal environment-linked neuropsychiatric disorders

The Cultivation of Taro on Hawaiian Islands : from the Viewpoint of Agricultural Civilization

It was confirmed, from the archaeological viewpoint and by examining the myths and folklores, that a considerably advanced stage of Polynesian farming system was the base of the culture on the Hawaiian Islands located on the margin of the cultural region of root crop cultivation. And the development of the labor-intensive paddy field farming and the intensive dryland cultivation system of mainly taro led to the rapid increase of population and the establishment of social classes, and produced the political systems with chieftainship. As for the agricultural methods, the common characteristics with those in various parts of Oceania were pointed out. It is a proof that the Hawaiians are the rightful successors of the root crop fanning with paddy field systems. But the operations of sugarcane plantations by the Caucasians and the exploitation of land and water by Asian immigrants by introducing the rice farming gave a fatal damage to the cultivation of taro. But it is important that there are any number of cultivated species still somehow maintained, and the diversity of cultivation patterns is kept to some extent The above is discussed in the paper, and it is pointed out that more attention should be given to the trend of reevaluation of the taro cultivation and the cultures based on it, in relation to the recent movement of restoration of the Hawaiian culture

Numerical Simulation of Quantum Systems -Dynamics of Electrons in Microstructures-

Difficulties in simulating systems composed of classical and quantum particles lie in the treatment of the many-body interactions between quantum particles and the geometrical variety of configurations of classical particles. In order to overcome these difficulties, we have developed some numerical methods and applied them to simple cases. As for stationary states, the finite element method provides us with sufficient geometrical freedom. Combined with the Kohn-Sham equation based on the density functional theory, this method virtually satisfies our requirement. In order to investigate time-dependent phenomena, we apply the time-dependent Kohn-Sham equation. Adopting the finite difference method, we are able to follow the development of quantum many-body system. As an example, we estimate the effects of the potential height, the electric field, and many-body interactions in some transition processes in quantum wells coupled by a tunneling barrier. This example is important in itself in relation to semiconductor superlattices and also serves as a benchmark for quantum simulations, variety of geometry corresponding to that of classical particles

Instantons in the U(1) Born-Infeld Theory and Noncommutative Gauge Theory

We derive a BPS-type bound for four-dimensional Born-Infeld action with constant B field background. The supersymmetric configuration saturates this bound and is regarded as an analog of instanton in U(1) gauge theory. Furthermore, we find the explicit solutions of this BPS condition. These solutions have a finite action proportional to the instanton number and represent D(p-4)-branes within a Dp-brane although they have a singularity at the origin. Some relations to the noncommutative U(1) instanton are discussed.Comment: 11 pages, LaTeX, no figures, one reference added, Title slightly changed, version to appear in Physics Letters

Intrinsic Bistability of Coupled Quantum Wires: Localization due to Many-Body Effects

The ground state of a system of electrons accumulated in a pair of coupled symmetric quantum wires is analyzed on the basis of density functional theory. It is shown that, in a domain of physical parameters, electrons are localized in either of wires. The main contribution to the total energy of this system comes from the Hartree energy, or the electrostatic energy, and the exchange-correlation energy between electrons. The ground state is determined by a competition between these contributions: We have symmetric electron distributions when the Hartree energy dominates and asymmetric (localized) states are realized in the opposite case. This kind of simple system with bistable electronic states may be applied to semiconductor memory devices