Monte Carlo Study of a U(1)×U(1)U(1)\times U(1) Loop Model with Modular Invariance

We study a $U(1)\times U(1)$ system in (2+1)-dimensions with long-range interactions and mutual statistics. The model has the same form after the application of operations from the modular group, a property which we call modular invariance. Using the modular invariance of the model, we propose a possible phase diagram. We obtain a sign-free reformulation of the model and study it in Monte Carlo. This study confirms our proposed phase diagram. We use the modular invariance to analytically determine the current-current correlation functions and conductivities in all the phases in the diagram, as well as at special "fixed" points which are unchanged by an operation from the modular group. We numerically determine the order of the phase transitions, and find segments of second-order transitions. For the statistical interaction parameter $\theta=\pi$, these second-order transitions are evidence of a critical loop phase obtained when both loops are trying to condense simulataneously. We also measure the critical exponents of the second-order transitions.Comment: 14 pages, 13 figure

The Advantages of Odd Exclusions

Every novel constitutes an interestingly complex set of linguistic experiments demonstrating some of the possibilities of its language to and by the exclusion of all the rest. Extreme cases may demonstrate these possibilities more clearly, and at least in English, no novel seems more arbitrarily extreme than Gadsby, which Ernest Vincent Wright apparently wrote in 1936-1937, with the E typebar of his typewriter tied down with string because, he said in his introduction, someone had told him he could not write coherent grammatical English without using its most common letter

The influence of toughening-particles in CFRPs on low velocity impact damage resistance performance

The role of particle-toughening for increasing impact damage resistance in carbon fibre reinforced polymer (CFRP) composites was investigated. Five carbon fibre reinforced systems consisting of four particle-toughened matrices and one system containing no toughening particles were subjected to low velocity impacts ranging from 25 J to 50 J to establish the impact damage resistance of each material system. Synchrotron radiation computed tomography (SRCT) enabled a novel approach for damage assessment and quantification. Toughening mechanisms were detected in the particle-toughened systems consisting of particle–resin debonding, crack-deflection and crack-bridging. Quantification of the bridging behaviour, increase in crack path length and roughness was undertaken. Out of the three toughening mechanisms measured, particle systems exhibited a larger extent of bridging suggesting a significant contribution of this toughening mechanism compared to the system with no particle

A Symbiotic View Of Life: We Have Never Been Individuals

The notion of the biological individual is crucial to studies of genetics, immunology, evolution, development, anatomy, and physiology. Each of these biological subdisciplines has a specific conception of individuality, which has historically provided conceptual contexts for integrating newly acquired data. During the past decade, nucleic acid analysis, especially genomic sequencing and high-throughput RNA techniques, has challenged each of these disciplinary definitions by finding significant interactions of animals and plants with symbiotic microorganisms that disrupt the boundaries that heretofore had characterized the biological individual. Animals cannot be considered individuals by anatomical or physiological criteria because a diversity of symbionts are both present and functional in completing metabolic pathways and serving other physiological functions. Similarly, these new studies have shown that animal development is incomplete without symbionts. Symbionts also constitute a second mode of genetic inheritance, providing selectable genetic variation for natural selection. The immune system also develops, in part, in dialogue with symbionts and thereby functions as a mechanism for integrating microbes into the animal-cell community. Recognizing the holobiont -the multicellular eukaryote plus its colonies of persistent symbionts-as a critically important unit of anatomy, development, physiology, immunology, and evolution opens up new investigative avenues and conceptually challenges the ways in which the biological subdisciplines have heretofore characterized living entities

Food Insecurity/Food Insufficiency: An Empirical Examination of Alternative Measures of Food Problems in Impoverished U.S. Households

This report analyzes different approaches to measuring food problems among impoverished households. Researchers investigating what public policy analysts refer to as hunger have sketched out alternative conceptual spaces within which these food problems can be measured. The narrower conceptual space may be termed food insufficiency and is distinguished by restricted household food stores, too little food intake among adults or children in the household, and direct reports or perceptions of hunger among household members. The broader conceptual space may be termed food insecurity. This term subsumes food insufficiency and extends to include resource insufficiency, the inability to acquire enough nutritious food through culturally normalized means, and anxiety about this inability, along with various attempts to augment or stretch the food supply. Since the late 1980s these two definitions of food problems in impoverished households have been understood as hunger, insofar as hunger is a measurable phenomenon for policy purposes in an advanced industrial nation such as the United States. These definitions are now central in the development of survey research items used to estimate the population prevalence of hunger, along with its predisposing socioeconomic conditions and resultant health and developmental consequences. Drawing on a data set containing survey responses from more than 5200 low income households with children in 11 sites from around the nation, we conduct an empirical inquiry of questionnaire items tapping phenomena from each conception defined above. Specifically, the study examines 34 distinct questionnaire items, and it addresses four research questions: (1) To what aspect of food insecurity or food insufficiency does each indicator point? (2) Can particular combinations of items be scaled? (3) When scaled, do the items demonstrate content validity? (4) How do the alternative measures perform in an operationalized model of the antecedents and consequences of household food problems? We test models that include variables such as household income, household food and shelter expenditures, and bills in arrears, along with the health status of a randomly chosen child from each household.

Entangled granular media

We study the geometrically induced cohesion of ensembles of granular "u-particles" which mechanically entangle through particle interpenetration. We vary the length-to-width ratio $l/w$ of the u-particles and form them into free-standing vertical columns. In laboratory experiment we monitor the response of the columns to sinusoidal vibration (frequency $f$, peak acceleration $\Gamma$). Column collapse occurs in a characteristic time, $\tau$, which follows the relation $\tau = f^{-1} \exp(\Delta / \Gamma)$. $\Delta$ resembles an activation energy and is maximal at intermediate $l/w$. Simulation reveals that optimal strength results from competition between packing and entanglement.Comment: 4 pages, 5 figure

Energetic Consistency and Momentum Conservation in the Gyrokinetic Description of Tokamak Plasmas

Gyrokinetic field theory is addressed in the context of a general Hamiltonian. The background magnetic geometry is static and axisymmetric, and all dependence of the Lagrangian upon dynamical variables is in the Hamiltonian or in free field terms. Equations for the fields are given by functional derivatives. The symmetry through the Hamiltonian with time and toroidal angle invariance of the geometry lead to energy and toroidal momentum conservation. In various levels of ordering against fluctuation amplitude, energetic consistency is exact. The role of this in underpinning of conservation laws is emphasised. Local transport equations for the vorticity, toroidal momentum, and energy are derived. In particular, the momentum equation is shown for any form of Hamiltonian to be well behaved and to relax to its magnetohydrodynamic (MHD) form when long wavelength approximations are taken in the Hamiltonian. Several currently used forms, those which form the basis of most global simulations, are shown to be well defined within the gyrokinetic field theory and energetic consistency.Comment: RevTeX 4, 47 pages, no figures, revised version updated following referee comments (discussion more strictly correct/consistent, 4 references added, results unchanged as they depend on consistency of the theory), resubmitted to Physics of Plasma