Slow Coarsening in an Ising Chain with Competing Interactions

We investigate the zero-temperature coarsening dynamics of a chain of Ising spins with a nearest-neighbor ferromagnetic and an nth-neighbor antiferromagnetic interactions. For sufficiently large antiferromagnetic interaction, the ground state consists of $n$ consecutive up spins followed by n down spins, etc. We show that the asymptotic coarsening into this ground state is governed by a multispecies reactive gas of elementary excitations. The basic elementary excitations are identified and each decays at a different power-law rate in time. The dominant excitations are domains of n+1 spins which diffuse freely and disappear through processes which are effectively governed by (n+1)-particle annihilation. This implies that the ground state is approached slowly with time, as t^{-1/n}.Comment: 7 pages, 2 figures, revtex 2-column format, submitted to J. Phys.

享保・元文期の「諸国産物帳」にみる香り米

江戸中期の享保・元文期(1735-1738年)に幕府によってまとめられた『諸国産物帳』に記載された"香り米"を選び出し，全国の"香り米"の作付け状況を考察した。当時北は陸奥国から南は肥後国にいたるまで"香り米"が栽培され，それらは品種名からⅠ.かおり・におい系，Ⅱ.じゃこう系，Ⅲ.かばしこ系，Ⅳ.かうはし系，Ⅴ.ねずみ系，Ⅵ.かまり系などに大別された

Flashback

This paper is concerned with an approach to discourse processing via a new more general interpretation of Tree Adjoining Grammars (TAG) proposed by Vijay-Shanker (1992). This formalism is based on so-called Description trees (D-trees) (Marcus et al. 1983, Backofen 1995). I will discuss a discourse phenomenon commonly used as a stylistic device, namely flashback sequences. These sequences are particularly interesting, since they contradict the naively assumed presupposition that everything has to be described in the order in which it happened. My approach is based on a Tree Description Grammar (TDG) using D-trees for the rhetorical relations (e.g. narration, elaboration and flashback) which hold between the discourse segments. This TDG allows us to model a flexible discourse structure which can account for a wide range of difficult to explain discourse effects including flashback sequences. This discourse grammar allows the discourse structure to be refined simply by adding further in..

Consistent relativistic Quantum Theory for

A causal, non-Hermitian, renormalizable, local, unitary and Lorentz convariant formulation of Quantum Theory (QT) (= Quantum Mechanics (QM) and Quantum Field Theory (QFT)) is developed which is free of formalistic problems we face in the commonly used Hermitian formulation of QT. Side effects of the new formulation of QT are the derivation of a consistent (anti)causal neutrino Lagrangian, the enrichment of chiral symmetries, the removal of the Dirac sea, the separation of positive and negative energy states including a reformulation of the anti-particle concept and a critical analysis of the concept of probability currents. In a first step we apply the new formulation of QT to establish a relation between perturbative Quantum Chromodynamics (QCD) and the (axial)vector meson extended Quark-Level Linear Sigma Model (QLLSM) at high energies

1340 PERSPECTIVES CELL BIOLOGY I n Shrinking Gels Pull Cells

“pleasing and nimble ” motions of extending and contracting “living atoms.” He was, of course, observing motile cells migrating across his microscope slide. Cell migration, we now know, is essential during embryogenesis and wound healing (1). Our current understanding of how cells crawl on solid surfaces began in the 1970s when Abercrombie Enhanced online at discovered that mi-www.sciencemag.org/cgi / gration can be dis-content/full/302/5649/1340 sected into three distinct stages. First, the cell develops a protrusion at the leading edge; then it strengthens its adhesions at the leading edge and weakens them at the trailing edge; finally, it develops contractile forces that pull the rear of the cell forward (2). Of these three stages, the last, called retraction, is the least well understood, both mechanically and at the molecular level (2). On page 1405 of this issue, Miao and colleagues (3) advance our knowledge of retraction by reconstituting the phenomenon in vitro for the first time. Most eukaryotic cells commence the crawling cycle by extending lamellipodia at their leading edge. These are broad, thin protrusions in front of the cell body that contain a dynamic, polarized network of actin filaments that grow at the leading edge and disassemble at the rear (1, 2, 4). The force driving protrusion is generated at points where the growing barbed ends of actin filaments abut the cell membrane, most likely by a ratchet mechanism generated as actin monomers are added to the growing filaments (4, 5). According to this model, the bending of filaments due to thermal fluctuations makes room for actin monomers to polymerize onto their barbed ends. This allows the elongated filaments to recoil and exert an elastic pushing force on the membrane. The nature of the contractile force at the rear pulling on the cell body is more mys