986 research outputs found
Numerical Study of the Two Color Attoworld
We consider QCD at very low temperatures and non-zero quark chemical
potential from lattice Monte Carlo simulations of the two-color theory in a
very small spatial volume (the attoscale). In this regime the quark number
rises in discrete levels in qualitative agreement with what is found
analytically at one loop on S3xS1 with radius R_S3 << 1/{\Lambda}_QCD. The
detailed level degeneracy, however, cannot be accounted for using weak coupling
arguments. At each rise in the quark number there is a corresponding spike in
the Polyakov line, also in agreement with the perturbative results. In addition
the quark number susceptibility shows a similar behaviour to the Polyakov line
and appears to be a good indicator of a confinement-deconfinement type of
transition.Comment: 18 pages, 10 figure
Understanding the assembly of Kepler's compact planetary systems
The Kepler mission has recently discovered a number of exoplanetary systems,
such as Kepler-11 and Kepler-32, in which ensembles of several planets are
found in very closely packed orbits (often within a few percent of an AU of one
another). These compact configurations present a challenge for traditional
planet formation and migration scenarios. We present a dynamical study of the
assembly of these systems, using an N-body method which incorporates a
parametrized model of planet migration in a turbulent protoplanetary disc. We
explore a wide parameter space, and find that under suitable conditions it is
possible to form compact, close-packed planetary systems via traditional
disc-driven migration. We find that simultaneous migration of multiple planets
is a viable mechanism for the assembly of tightly-packed planetary systems, as
long as the disc provides significant eccentricity damping and the level of
turbulence in the disc is modest. We discuss the implications of our preferred
parameters for the protoplanetary discs in which these systems formed, and
comment on the occurrence and significance of mean-motion resonances in our
simulations.Comment: 12 pages, 4 figures, 2 tables. Accepted for publication in Monthly
Notices of the Royal Astronomical Societ
Philosophy and Economics
\u27Much has changed in the latest incarnation of this dictionary...More than 1,500 economists contributed almost 1,900 signed entries; more than 1,000 of the entries are new or \u27heavily revised\u27 and expanded. Along with the descriptions of economic method from earlier editions, this edition includes much information on \u27what those methods have found.\u27 It also offers new emphasis on advances that have occurred in microeconomics, Bayesian theory, game theory, and behavioral, international, and experimental economics...A regularly updated online version of the dictionary is available www.dictionaryofeconomics.com, with site license pricing based on institution type and FTE. Summing Up: Highly recommended.\u27 - Choice Winner of the 2008 Prose award for the Best Multi-Volume Reference Work in the Humanities and Social Sciences. The Dictionary was also a finalist and received an honourable mention in the Best eProduct category. Reviews of the 1987 edition: \u27The New Palgrave is in a class of its own...The dictionary does everything which one would hope of a successor to the original Palgrave dictionary. There will be no competitor for many decades.\u27 - The Guardian \u27This will be the standard reference work on economics until well into the next century.\u27 - The World Economy \u27The list of contributors reads like a who\u27s who in economics. The range of topics is breathtaking. The choice of topics is excellent...It is overwhelmingly impressive...a very high quality product that is also unique.\u27 - Martin L. Weitzman, Massachusetts Institute of Technology \u27To attempt such an undertaking was audacious, to have carried it out is astonishing, and to have done so with so remarkable a list of authors is a tribute to the intelligence and diligence of the editors.\u27 - Alan S. Blinder, Princeton University \u27The New Palgrave will be an indispensable reference tool for both junior and senior scholars in economics and perhaps even more for the journalist or business executive. The topics are exhaustive.\u27 - Kenneth J. Arrow, Nobel Prize Winner in Economic
Mark Blaug on the Normativity of Welfare Economics
Abstract: This paper examines Mark Blaug's position on the normative character of Paretian welfare economics: in general, and specifically with respect to his debate with Pieter Hennipman over this question during the 1990s. The paper also clarifies some of the confusions that emerged within the context of this debate, and closes by providing some additional arguments supporting Blaug's position that he himself did not provide
Public understanding of chemistry research in print news
Despite numerous calls for improving scientific literacy, many American adults show a lack of understanding of experiments, scientific study, and scientific inquiry. News media is one important avenue for science learning, but previous research investigating health and/or environmental science news has shown that it is inconsistent in the presentation of scientific research limitations, potentially impacting reader understanding. In the first phase of this dissertation, seventeen news articles reporting on a single chemistry research article, along with associated press releases and research articles, were analyzed using move analysis to determine the structure of each type of text. It was found that the overall structure of each text genre was similar, with the main difference being that research articles start by presenting background information, while the others lead with highlighting overall research outcomes. Analysis of the steps revealed that, as seen for health and environmental science news articles, descriptions of the study limitations and methods were generally omitted in the news articles. Using these findings, a pilot study was conducted where study limitations were added to a chemistry research news article and the effect of its presence on staff members employed at a large Midwestern university (n=12) and science faculty employed at the same institution (n=6) was explored. Interviews with the participants revealed that including limitations enhanced readers\u27 ability to identify conclusions and evaluate claims, but decreased their trust in the information. In the final part of this study, the trends seen in the previous phase were explored to determine their generalizability. Members of the public (n=232) and science faculty (n=191) read a randomly assigned news article either presenting or omitting the study limitations and research methods. Participants reading articles presenting limitations were able to evaluate the reasonableness of claims based on the article better than those who read the article omitting limitations when accounting for their views on the tentativeness of science (ToS). Presenting limitations was important in identifying unreasonable claims for both public and science faculty, while ToS views predicted ability to identify reasonable claims for the public. Including limitations also decreased readers\u27 trust in the conclusions of the research. However, it did not impact their ability to determine the conclusions of the research and including methods did not have any effect on the measured outcomes
2006 HES Presidential Address: A Tale of Two Mainstreams: Economics and Philosophy of Natural Science in the mid-Twentieth Century
Abstract: The paper argues that mainstream economics and mainstream philosophy of natural science had much in common during the period 1945-1965. It examines seven common features of the two fields and suggests a number of historical developments that might help explain these similarities. The historical developments include: the Vienna Circle connection, the Samuelson-Harvard-Foundations connection, and the Cold War operations research connection
Magnetic Monopoles as Agents of Chiral Symmetry Breaking in U(1) Lattice Gauge Theory
We present results suggesting that magnetic monopoles can account for chiral
symmetry breaking in abelian gauge theory. Full U(1) configurations from a
lattice simulation are factorized into magnetic monopole and photon
contributions. The expectation is computed using the monopole
configurations and compared to results for the full U(1) configurations. It is
shown that excellent agreement between the two values of is
obtained if the effect of photons, which "dress" the composite operator
psibarpsi, is included. This can be estimated independently by measurements of
the physical fermion mass in the photon background.Comment: 14 pages REVTeX, including 5 figure
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