720 research outputs found
Three Able Addresses Delivered Before the State Board of Trade at Bangor, Maine, March 25, 1902
The text of three addresses: Maine canning industry / B.M. Fernald -- Maine as a vacation state / Leroy T. Carleton -- Maine primitive and modern industry / J.W. Penney
Scaling and Eigenmode Tests of the Improved Fat Clover Action
We test a recently proposed improved lattice-fermion action, the fat link
clover action, examining indicators of pathological small-quark-mass lattice
artifacts ("exceptional configurations") on quenched lattices of spacing 0.12
fm and studying scaling properties of the light hadron spectrum for lattice
spacing a=0.09 and 0.16 fm. We show that the action apparently has fewer
problems with pathological lattice artifacts than the conventional
nonperturbatively improved clover action and its spectrum scales just as well.Comment: 15 pp RevTeX, 5 Postscript figures, submitted to Phys. Rev.
Rearranged section order and added an analysis of fluctuations of the pion
correlato
Potts Flux Tube Model at Nonzero Chemical Potential
We model the deconfinement phase transition in quantum chromodynamics at
nonzero baryon number density and large quark mass by extending the flux tube
model (three-state, three-dimensional Potts model) to nonzero chemical
potential. In a direct numerical simulation we confirm mean-field-theory
predictions that the deconfinement transition does not occur in a baryon-rich
environment.Comment: 14 pp RevTeX, 10 Postscript figures, submitted to Phys. Rev D.
(Corrected some typographical errors.
String Breaking in Lattice Quantum Chromodynamics
The separation of a heavy quark and antiquark pair leads to the formation of
a tube of flux, or string, which should break in the presence of light
quark-antiquark pairs. This expected zero temperature phenomenon has proven
elusive in simulations of lattice QCD. We present simulation results that show
that the string does break in the confining phase at nonzero temperature.Comment: 11 pages RevTeX, including 4 encapsulated Postscript figures.
version2: minor corrections to reference
NEXUS/Physics: An interdisciplinary repurposing of physics for biologists
In response to increasing calls for the reform of the undergraduate science
curriculum for life science majors and pre-medical students (Bio2010,
Scientific Foundations for Future Physicians, Vision & Change), an
interdisciplinary team has created NEXUS/Physics: a repurposing of an
introductory physics curriculum for the life sciences. The curriculum interacts
strongly and supportively with introductory biology and chemistry courses taken
by life sciences students, with the goal of helping students build general,
multi-discipline scientific competencies. In order to do this, our two-semester
NEXUS/Physics course sequence is positioned as a second year course so students
will have had some exposure to basic concepts in biology and chemistry.
NEXUS/Physics stresses interdisciplinary examples and the content differs
markedly from traditional introductory physics to facilitate this. It extends
the discussion of energy to include interatomic potentials and chemical
reactions, the discussion of thermodynamics to include enthalpy and Gibbs free
energy, and includes a serious discussion of random vs. coherent motion
including diffusion. The development of instructional materials is coordinated
with careful education research. Both the new content and the results of the
research are described in a series of papers for which this paper serves as an
overview and context.Comment: 12 page
Physical Orbit for Lambda Virginis and a Test of Stellar Evolution Models
Lambda Virginis (LamVir) is a well-known double-lined spectroscopic Am binary
with the interesting property that both stars are very similar in abundance but
one is sharp-lined and the other is broad-lined. We present combined
interferometric and spectroscopic studies of LamVir. The small scale of the
LamVir orbit (~20 mas) is well resolved by the Infrared Optical Telescope Array
(IOTA), allowing us to determine its elements as well as the physical
properties of the components to high accuracy. The masses of the two stars are
determined to be 1.897 Msun and 1.721 Msun, with 0.7% and 1.5% errors
respectively, and the two stars are found to have the same temperature of 8280
+/- 200 K. The accurately determined properties of LamVir allow comparisons
between observations and current stellar evolution models, and reasonable
matches are found. The best-fit stellar model gives LamVir a subsolar
metallicity of Z=0.0097, and an age of 935 Myr. The orbital and physical
parameters of LamVir also allow us to study its tidal evolution time scales and
status. Although currently atomic diffusion is considered to be the most
plausible cause of the Am phenomenon, the issue is still being actively debated
in the literature. With the present study of the properties and evolutionary
status of LamVir, this system is an ideal candidate for further detailed
abundance analyses that might shed more light on the source of the chemical
anomalies in these A stars.Comment: 43 Pages, 13 figures. Accepted for publication in Ap
Quenched hadron spectroscopy with improved staggered quark action
We investigate light hadron spectroscopy with an improved quenched staggered
quark action. We compare the results obtained with an improved gauge plus an
improved quark action, an improved gauge plus standard quark action, and the
standard gauge plus standard quark action. Most of the improvement in the
spectroscopy results is due to the improved gauge sector. However, the improved
quark action substantially reduces violations of Lorentz invariance, as
evidenced by the meson dispersion relations.Comment: New references adde
Two-Flavor Staggered Fermion Thermodynamics at N_t = 12
We present results of an ongoing study of the nature of the high temperature
crossover in QCD with two light fermion flavors. These results are obtained
with the conventional staggered fermion action at the smallest lattice spacing
to date---approximately 0.1 fm. Of particular interest are a study of the
temperature of the crossover a determination of the induced baryon charge and
baryon susceptibility, the scalar susceptibility, and the chiral order
parameter, used to test models of critical behavior associated with chiral
symmetry restoration. From our new data and published results for N_t = 4, 6,
and 8, we determine the QCD magnetic equation of state from the chiral order
parameter using O(4) and mean field critical exponents and compare it with the
corresponding equation of state obtained from an O(4) spin model and mean field
theory. We also present a scaling analysis of the Polyakov loop, suggesting a
temperature dependent ``constituent quark free energy.''Comment: LaTeX 25 pages, 15 Postscript figure
Recommended from our members
What do I do now? Intolerance of uncertainty is associated with discrete patterns of anticipatory physiological responding to different contexts
Heightened physiological responses to uncertainty are a common hallmark of anxiety disorders. Many separate studies have examined the relationship between individual differences in intolerance of uncertainty (IU) and physiological responses to uncertainty during different contexts. Despite this there is a scarcity of research examining the extent to which individual differences in IU are related to shared or discrete patterns of anticipatory physiological responding across different contexts. Anticipatory physiological responses to uncertainty were assessed in three different contexts (associative threat learning and extinction, threat uncertainty, decision-making) within the same sample (n = 45). During these tasks, behavioural responses (i.e. reaction times, choices), skin conductance and corrugator supercilli activity were recorded. In addition, self-reported IU and trait anxiety were measured. IU was related to both skin conductance and corrugator supercilii activity for the associative threat learning and extinction context, and decision-making context. However, trait anxiety was related to corrugator supercilii activity during the threat uncertainty context. Ultimately, this research helps us further tease apart the role of IU on different aspects of anticipation (i.e. valence and arousal) across contexts, which will be relevant for future IU-related models of psychopathology
Baryon Density Correlations in High Temperature Hadronic Matter
As part of an ongoing effort to characterize the high temperature phase of
QCD, in a numerical simulation using the staggered fermion scheme, we measure
the quark baryon density in the vicinity of a fixed test quark at high
temperature and compare it with similar measurements at low temperature and at
the crossover temperature. We find an extremely weak correlation at high
temperature, suggesting that small color singlet clusters are unimportant in
the thermal ensemble. We also find that at the total induced
quark number shows a surprisingly large component attributable to baryonic
screening. A companion simulation of a simple flux tube model produces similar
results and also suggests a plausible phenomenological scenario: As the
crossover temperature is approached from below, baryonic states proliferate.
Above the crossover temperature the mean size of color singlet clusters grows
explosively, resulting in an effective electrostatic deconfinement.Comment: 26 pp, RevTeX, 12 postscript figures, combined in a single shell
archive file. (Also available in 13 postscript files by anonymous ftp from
einstein.physics.utah.edu, /pub/milc/paper.sh.Z.
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