19 research outputs found
A Study of the Nambu--Jona-Lasinio Model on the Lattice
We present our full analysis of the two flavor Nambu--Jona-Lasinio model with
chiral symmetry on the four--dimensional hypercubic
lattice with naive and Wilson fermions. We find that this model is an excellent
toy field theory to investigate issues related to lattice QCD. We use the large
approximation to leading order in to obtain non perturbative
analytical results over almost the whole parameter range. By using numerical
simulations we estimate that the size of the corrections for most of the
quantities we consider are small and in this way we strengthen the validity of
the leading order large calculations. We obtain results regarding the
approach to the continuum chiral limit, the effects of the zero momentum
fermionic modes on finite lattices and the scalar and pseudoscalar spectrum.
Note: The full ps file of this preprint is also available via anonymous ftp to
ftp.scri.fsu.edu. To get the ps file, ftp to this address and use for username
"anonymous" and for password your complete E-mail address. The file is in the
directory pub/vranas (to go to that directory type: cd pub/vranas) and is
called NJL_long.ps (to get it type: get NJL_long.ps)Comment: 35 pages, LaTex file. (Added section with title: "The zero pion mass
line on a finite lattice at large ".
Transport Properties of the Quark-Gluon Plasma -- A Lattice QCD Perspective
Transport properties of a thermal medium determine how its conserved charge
densities (for instance the electric charge, energy or momentum) evolve as a
function of time and eventually relax back to their equilibrium values. Here
the transport properties of the quark-gluon plasma are reviewed from a
theoretical perspective. The latter play a key role in the description of
heavy-ion collisions, and are an important ingredient in constraining particle
production processes in the early universe. We place particular emphasis on
lattice QCD calculations of conserved current correlators. These Euclidean
correlators are related by an integral transform to spectral functions, whose
small-frequency form determines the transport properties via Kubo formulae. The
universal hydrodynamic predictions for the small-frequency pole structure of
spectral functions are summarized. The viability of a quasiparticle description
implies the presence of additional characteristic features in the spectral
functions. These features are in stark contrast with the functional form that
is found in strongly coupled plasmas via the gauge/gravity duality. A central
goal is therefore to determine which of these dynamical regimes the quark-gluon
plasma is qualitatively closer to as a function of temperature. We review the
analysis of lattice correlators in relation to transport properties, and
tentatively estimate what computational effort is required to make decisive
progress in this field.Comment: 54 pages, 37 figures, review written for EPJA and APPN; one parag.
added end of section 3.4, and one at the end of section 3.2.2; some Refs.
added, and some other minor change
Cardiovascular disease incidence after internal mammary chain irradiation and anthracycline-based chemotherapy for breast cancer
Background: Improved breast cancer (BC) survival and evidence showing beneficial effects of internal mammary chain (IMC) irradiation underscore the importance of studying late cardiovascular effects of BC treatment. Methods: We assessed cardiovascular disease (CVD) incidence in 14,645 Dutch BC patients aged <62 years, treated during 1970â2009. Analyses included proportional hazards models and general population comparisons. Results: CVD rate-ratio for left-versus-right breast irradiation without IMC was 1.11 (95% CI 0.93â1.32). Compared to right-sided breast irradiation only, IMC irradiation (interquartile range mean heart doses 9â17 Gy) was associated with increases in CVD rate overall, ischaemic heart disease (IHD), heart failure (HF) and valvular heart disease (hazard ratios (HRs): 1.6â2.4). IHD risk remained increased until at least 20 years after treatment. Anthracycline-based chemotherapy was associated with an increased HF rate (HR = 4.18, 95% CI 3.07â5.69), emerging <5 years and remaining increased at least 10â15 years after treatment. IMC irradiation combined with anthracycline-based chemotherapy was associated with substantially increased HF rate (HR = 9.23 95% CI 6.01â14.18), compared to neither IMC irradiation nor anthracycline-based chemotherapy. Conclusions: Women treated with anthracycline-based chemotherapy and IMC irradiation (in an older era) with considerable mean heart dose exposure have substantially increased incidence of several CVDs. Screening may be appropriate for some BC patient groups
A multi-model ensemble method that combines imperfect models through learning.
Contains fulltext :
95574.pdf (publisher's version ) (Open Access)17 p
Data Assimilation as Artificial Perception and Supermodeling as Artificial Consciousness
Dynamically combining climate models to "supermodel" the tropical Pacific
Contains fulltext :
156947.pdf (publisher's version ) (Open Access