3,981 research outputs found
An Analytic Equation of State for Ising-like Models
Using an Environmentally Friendly Renormalization we derive, from an
underlying field theory representation, a formal expression for the equation of
state, , that exhibits all desired asymptotic and analyticity
properties in the three limits , and . The only
necessary inputs are the Wilson functions , and
, associated with a renormalization of the transverse vertex
functions. These Wilson functions exhibit a crossover between the Wilson-Fisher
fixed point and the fixed point that controls the coexistence curve.
Restricting to the case N=1, we derive a one-loop equation of state for naturally parameterized by a ratio of non-linear scaling fields. For
we show that a non-parameterized analytic form can be deduced. Various
asymptotic amplitudes are calculated directly from the equation of state in all
three asymptotic limits of interest and comparison made with known results. By
positing a scaling form for the equation of state inspired by the one-loop
result, but adjusted to fit the known values of the critical exponents, we
obtain better agreement with known asymptotic amplitudes.Comment: 10 pages, 2 figure
Umbilical cord blood banking: Beyond the public-private divide
Umbilical cord blood is a source of haematopoietic progenitor cells, which are used to treat a range of malignant, genetic, metabolic and immune disorders. Until recently, cord blood was either collected through donations to publicly funded cord blood banks for use in allogeneic transplantation, or stored in commercial cord blood banks for use in autologous transplantation. The line between public and private cord blood banking is being blurred by the emergence of "hybrid" models that combine aspects of both the public and private systems. The authors describe these hybrid models and argue that their emergence is explained by both market forces and public sector policy They propose that the future of the sector will depend heavily on several key developments that will differentially affect public, private and hybrid banking models
Dynamics and Gravitational Wave Signature of Collapsar Formation
We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early hyperaccretion phase. We extract gravitational waves from the spacetime curvature and identify a unique gravitational wave signature associated with the early phase of collapsar formation
The Specific Heat of a Ferromagnetic Film.
We analyze the specific heat for the vector model on a -dimensional
film geometry of thickness using ``environmentally friendly''
renormalization. We consider periodic, Dirichlet and antiperiodic boundary
conditions, deriving expressions for the specific heat and an effective
specific heat exponent, \alpha\ef. In the case of , for , by
matching to the exact exponent of the two dimensional Ising model we capture
the crossover for \xi_L\ra\infty between power law behaviour in the limit
{L\over\xi_L}\ra\infty and logarithmic behaviour in the limit
{L\over\xi_L}\ra0 for fixed , where is the correlation length in
the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from
[email protected]
An ab initio Calculation of the Universal Equation of State for the O(N) Model
Using an Environmentally Friendly Renormalization Group we derive an ab
initio universal scaling form for the equation of state for the O(N) model,
y=f(x), that exhibits all required analyticity properties in the limits , and . Unlike current methodologies based on a
phenomenological scaling ansatz the scaling function is derived solely from the
underlying Landau-Ginzburg-Wilson Hamiltonian and depends only on the three
Wilson functions , and which
exhibit a non-trivial crossover between the Wilson-Fisher fixed point and the
strong coupling fixed point associated with the Goldstone modes on the
coexistence curve. We give explicit results for N=2, 3 and 4 to one-loop order
and compare with known results.Comment: 12 pages, to appear in Journal of Physics
Dynamics and gravitational wave signature of collapsar formation
We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early hyperaccretion phase. We extract gravitational waves from the spacetime curvature and identify a unique gravitational wave signature associated with the early phase of collapsar formatio
Explanation and Elaboration Document for the STROBE-Vet Statement: Strengthening the Reporting of Observational Studies in EpidemiologyâVeterinary Extension
The STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement was first published in 2007 and again in 2014. The purpose of the original STROBE was to provide guidance for authors, reviewers and editors to improve the comprehensiveness of reporting; however, STROBE has a unique focus on observational studies. Although much of the guidance provided by the original STROBE document is directly applicable, it was deemed useful to map those statements to veterinary concepts, provide veterinary examples and highlight unique aspects of reporting in veterinary observational studies. Here, we present the examples and explanations for the checklist items included in the STROBE-Vet Statement. Thus, this is a companion document to the STROBE-Vet Statement Methods and process document, which describes the checklist and how it was developed
Modular Invariance of Finite Size Corrections and a Vortex Critical Phase
We analyze a continuous spin Gaussian model on a toroidal triangular lattice
with periods and where the spins carry a representation of the
fundamental group of the torus labeled by phases and . We find the
{\it exact finite size and lattice corrections}, to the partition function ,
for arbitrary mass and phases . Summing over phases gives
the corresponding result for the Ising model. The limits and
do not commute. With the model exhibits a {\it vortex
critical phase} when at least one of the is non-zero. In the continuum or
scaling limit, for arbitrary , the finite size corrections to are
{\it modular invariant} and for the critical phase are given by elliptic theta
functions. In the cylinder limit the ``cylinder charge''
is a non-monotonic function of that ranges from
for to zero for .Comment: 12 pages of Plain TeX with two postscript figure insertions called
torusfg1.ps and torusfg2.ps which can be obtained upon request from
[email protected]
Relaxation and Localization in Interacting Quantum Maps
We quantise and study several versions of finite multibaker maps. Classically
these are exactly solvable K-systems with known exponential decay to global
equilibrium. This is an attempt to construct simple models of relaxation in
quantum systems. The effect of symmetries and localization on quantum transport
is discussed.Comment: 32 pages. LaTex file. 9 figures, not included. For figures send mail
to first author at '[email protected]
- âŠ