The nature of the long time decay at a second order transition point

We show that at a second order phase transition, of \phi^4 like system, a necessary condition for streched exponential decay of the time structure factor is obeyed. Using the ideas presented in this proof a crude estimate of the decay of the structure factor is obtained and shown to yield stretched exponential decay under very reasonable conditions.Comment: 7 page

The Induced Magnetic Field of the Moon: Conductivity Profiles and Inferred Temperature

Electromagnetic induction in the moon driven by fluctuations of the interplanetary magnetic field is used to determine the lunar bulk electrical conductivity. The present data clearly show the north-south and east-west transfer function difference as well as high frequency rollover. The difference is shown to be compatible over the mid-frequency range with a noise source associated with the compression of the local remanent field by solar wind dynamic pressure fluctuations. Models for two, three, and four layer; current layer, double current layer, and core plus current layer moons are generated by inversion of the data using a theory which incorporates higher order multipoles. Core radii conductivities generally are in the range 1200 to 1300 km and 0.001 to 0.003 mhos/m; and for the conducting shell 1500 to 1700 km with 0.0001 to 0.0007 mhos/m with an outer layer taken as nonconducting. Core temperature based on available olivine data is 700 to 1000 C

A volumetric Penrose inequality for conformally flat manifolds

We consider asymptotically flat Riemannian manifolds with nonnegative scalar curvature that are conformal to $\R^{n}\setminus \Omega, n\ge 3$, and so that their boundary is a minimal hypersurface. (Here, $\Omega\subset \R^{n}$ is open bounded with smooth mean-convex boundary.) We prove that the ADM mass of any such manifold is bounded below by $(V/\beta_{n})^{(n-2)/n}$, where $V$ is the Euclidean volume of $\Omega$ and $\beta_{n}$ is the volume of the Euclidean unit $n$-ball. This gives a partial proof to a conjecture of Bray and Iga \cite{brayiga}. Surprisingly, we do not require the boundary to be outermost.Comment: 7 page

Riqueza de espécies, estrutura e composição florística de uma floresta secundária de 40 anos no leste da Amazônia.

A perda de florestas naturais devido a pressões antrópicas levou as florestas secundárias a ocupar uma grande proporção de áreas no leste da Amazônia. Com o objetivo de conhecer as características de uma comunidade arbórea e a estrutura populacional das espécies mais representativas, foram investigadas a riqueza de espécies, a estrutura e a composição florística de uma floresta secundária de 40 anos no município de Bragança (01°11'S e 46°40'W), Estado do Pará, Brasil. A amostragem contou com todos os indivíduos de espécies arbóreas (exceto Arecaceae) com DAP > 5 cm em 150 quadrados de 10×10 m. Foram registrados 2.934 indivíduos em 154 espécies, 101 gêneros e 40 famílias. A densidade foi de 1.956,00 ± 643,45 ind ha-1 e a área basal de 17,358 ± 7,952 m2 ha-1 com um índice de diversidade de Shannon de 4,030 nats. ind.-1. As espécies com a maior abundância de indivíduos foram Myrcia bracteata, Casearia arborea e Maprounea guianensis. As com maior área basal foram Tapirira guianensis, Croton matourensis e Maprounea guianensis. A riqueza de espécies adaptou-se ao modelo de distribuição lognormal apenas para área basal e não para número de indivíduos. Em 40 anos de sucessão, esta floresta mostra uma grande diversidade de espécies e baixa área basal

Hybrid simulations of lateral diffusion in fluctuating membranes

In this paper we introduce a novel method to simulate lateral diffusion of inclusions in a fluctuating membrane. The regarded systems are governed by two dynamic processes: the height fluctuations of the membrane and the diffusion of the inclusion along the membrane. While membrane fluctuations can be expressed in terms of a dynamic equation which follows from the Helfrich Hamiltonian, the dynamics of the diffusing particle is described by a Langevin or Smoluchowski equation. In the latter equations, the curvature of the surface needs to be accounted for, which makes particle diffusion a function of membrane fluctuations. In our scheme these coupled dynamic equations, the membrane equation and the Langevin equation for the particle, are numerically integrated to simulate diffusion in a membrane. The simulations are used to study the ratio of the diffusion coefficient projected on a flat plane and the intramembrane diffusion coefficient for the case of free diffusion. We compare our results with recent analytical results that employ a preaveraging approximation and analyze the validity of this approximation. A detailed simulation study of the relevant correlation functions reveals a surprisingly large range where the approximation is applicable.Comment: 12 pages, 9 figures, accepted for publication in Phys. Rev.

The Epstein-Glaser approach to pQFT: graphs and Hopf algebras

The paper aims at investigating perturbative quantum field theory (pQFT) in the approach of Epstein and Glaser (EG) and, in particular, its formulation in the language of graphs and Hopf algebras (HAs). Various HAs are encountered, each one associated with a special combination of physical concepts such as normalization, localization, pseudo-unitarity, causality and an associated regularization, and renormalization. The algebraic structures, representing the perturbative expansion of the S-matrix, are imposed on the operator-valued distributions which are equipped with appropriate graph indices. Translation invariance ensures the algebras to be analytically well-defined and graded total symmetry allows to formulate bialgebras. The algebraic results are given embedded in the physical framework, which covers the two recent EG versions by Fredenhagen and Scharf that differ with respect to the concrete recursive implementation of causality. Besides, the ultraviolet divergences occuring in Feynman's representation are mathematically reasoned. As a final result, the change of the renormalization scheme in the EG framework is modeled via a HA which can be seen as the EG-analog of Kreimer's HA.Comment: 52 pages, 5 figure

Critical strength of attractive central potentials

We obtain several sequences of necessary and sufficient conditions for the existence of bound states applicable to attractive (purely negative) central potentials. These conditions yields several sequences of upper and lower limits on the critical value, $g_{\rm{c}}^{(\ell)}$, of the coupling constant (strength), $g$, of the potential, $V(r)=-g v(r)$, for which a first $\ell$-wave bound state appears, which converges to the exact critical value.Comment: 18 page

Adaptive Networks as a Model for Human Speech Development-Cluster Plots

This Technical Report contains all the cluster plots generated for the cluster analyses described in §9.7 of [1]. The Lance and William General Algorithm with complete linkages for hierarchical clustering analysis [2] is used. A brief description of the algorithm may be found in §9.7.1 of [1]. In the cluster plots the symbol -\u3e designates a letter-to-phoneme mapping. For example, c-\u3ek means the letter in the center of the window is c and is being mapped by the network into the phoneme /k/. Definitions of the phoneme symbols may be found on pp. 22-23 of [I]. A horizontal line designates a cluster. The length of a horizontal line has no significance. A vertical line designates the distance between the two clusters joining the top and bottom ends of the vertical line. The distance scale may be found at the beginning and the end of each plot. All plots have the same relative distance scale. Cluster analyses are performed after the 5th, 10th, 15th, 20th, and 25th passes through the English training database, and after the 2nd, 4th, 6th, 8th, and 10th passes through the Spanish training database. Cluster analyses for the second language trainings are performed similarly. Observations may be found in §9.7.2-§9.7.7 of [1

Variable cavity volume tooling for high-performance resin infusion moulding

This article describes the research carried out by Warwick under the BAE Systems/EPSRC programme ‘Flapless Aerial Vehicles Integrated Interdisciplinary Research – FLAVIIR’. Warwick's aim in FLAVIIR was to develop low-cost innovative tooling technologies to enable the affordable manufacture of complex composite aerospace structures and to help realize the aim of the Grand Challenge of maintenance-free, low-cost unmanned aerial vehicle manufacture. This article focuses on the evaluation of a novel tooling process (variable cavity tooling) to enable the complete infusion of resin throughout non-crimp fabric within a mould cavity under low (0.1 MPa) injection pressure. The contribution of the primary processing parameters to the mechanical properties of a carbon composite component (bulk-head lug section), and the interactions between parameters, was determined. The initial mould gap (di) was identified as having the most significant effect on all measured mechanical properties, but complex interactions between di, n (number of fabric layers), and vc (mould closure rate) were observed. The process capability was low due to the manual processing, but was improved through process optimization, and delivered properties comparable to high-pressure resin transfer moulding