81 research outputs found
Thermodynamics with 3 and 2+1 Flavors of Improved Staggered Quarks
We present preliminary results from exploring the phase diagram of finite
temperature QCD with three degenerate flavors and with two light flavors and
the mass of the third held approximately at the strange quark mass. We use an
order Symanzik improved gauge action and an order
improved staggered quark action. The improved staggered
action leads to a dispersion relation with diminished lattice artifacts, and
hence better thermodynamic properties. It decreases the flavor symmetry
breaking of staggered quarks substantially, and we estimate that at the
transition temperature for an to lattice {\em all} pions will
be lighter than the lightest kaon. Preliminary results on lattices with
, 6 and 8 are presented.Comment: 3 pages, 6 figures, contribution to Lattice2001(hightemp) August
19--24, 2001, Berlin, German
Recent MILC spectrum results
We report on results from three spectrum calculations with staggered quarks:
1) a quenched calculation with the standard action for the gluons and quarks;
2) a quenched calculation with improved actions for both the gluons and quarks;
and 3) a calculation with two flavors of dynamical quarks using the standard
actions for the gluons and quarks.Comment: Poster presented at LATTICE96(spectrum);4 pages of LaTeX, uses
espcrc2 and epsf, six postscript figures include
Quark Loop Effects with an Improved Staggered Action
We have been studying effects of dynamical quarks on various hadronic
observables, using our recently formulated improvement for staggered fermions.
To illustrate improvement, we show that the light hadron spectrum in the
quenched approximation gives remarkably good scaling. We highlight three new
results: (1) We find no apparent quark loop effects in the Edinburgh plot with
2+1 flavors of dynamical quarks at a = 0.14 fm. (2) We show that dynamical
quarks modify the shape of the heavy quark potential. (3) We present results
hinting at meson decay effects in light hadron spectroscopy.Comment: 5 pages, 7 figures, Lattice 2000 (Spectrum
Quantum walks: a comprehensive review
Quantum walks, the quantum mechanical counterpart of classical random walks,
is an advanced tool for building quantum algorithms that has been recently
shown to constitute a universal model of quantum computation. Quantum walks is
now a solid field of research of quantum computation full of exciting open
problems for physicists, computer scientists, mathematicians and engineers.
In this paper we review theoretical advances on the foundations of both
discrete- and continuous-time quantum walks, together with the role that
randomness plays in quantum walks, the connections between the mathematical
models of coined discrete quantum walks and continuous quantum walks, the
quantumness of quantum walks, a summary of papers published on discrete quantum
walks and entanglement as well as a succinct review of experimental proposals
and realizations of discrete-time quantum walks. Furthermore, we have reviewed
several algorithms based on both discrete- and continuous-time quantum walks as
well as a most important result: the computational universality of both
continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing
Journa
Multiethnic Meta-Analysis Identifies RAI1 as a Possible Obstructive Sleep Apnea-related Quantitative Trait Locus in Men.
Obstructive sleep apnea (OSA) is a common heritable disorder displaying marked sexual dimorphism in disease prevalence and progression. Previous genetic association studies have identified a few genetic loci associated with OSA and related quantitative traits, but they have only focused on single ethnic groups, and a large proportion of the heritability remains unexplained. The apnea-hypopnea index (AHI) is a commonly used quantitative measure characterizing OSA severity. Because OSA differs by sex, and the pathophysiology of obstructive events differ in rapid eye movement (REM) and non-REM (NREM) sleep, we hypothesized that additional genetic association signals would be identified by analyzing the NREM/REM-specific AHI and by conducting sex-specific analyses in multiethnic samples. We performed genome-wide association tests for up to 19,733 participants of African, Asian, European, and Hispanic/Latino American ancestry in 7 studies. We identified rs12936587 on chromosome 17 as a possible quantitative trait locus for NREM AHI in men (N = 6,737; P = 1.7 × 10 <sup>-8</sup> ) but not in women (P = 0.77). The association with NREM AHI was replicated in a physiological research study (N = 67; P = 0.047). This locus overlapping the RAI1 gene and encompassing genes PEMT1, SREBF1, and RASD1 was previously reported to be associated with coronary artery disease, lipid metabolism, and implicated in Potocki-Lupski syndrome and Smith-Magenis syndrome, which are characterized by abnormal sleep phenotypes. We also identified gene-by-sex interactions in suggestive association regions, suggesting that genetic variants for AHI appear to vary by sex, consistent with the clinical observations of strong sexual dimorphism
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