520 research outputs found
Gaussian Wavefunctional Approach in Thermofield Dynamics
The Gaussian wavefunctional approach is developed in thermofield dynamics. We
manufacture thermal vacuum wavefunctional, its creation as well as annihilation
operators,and accordingly thermo-particle excited states. For a
(D+1)-dimensional scalar field system with an arbitrary potential whose Fourier
representation exists in a sense of tempered distributions, we calculate the
finite temperature Gaussian effective potential (FTGEP), one- and
two-thermo-particle-state energies. The zero-temperature limit of each of them
is just the corresponding result in quantum field theory, and the FTGEP can
lead to the same one of each of some concrete models as calculated by the
imaginary time Green function.Comment: the revised version of hep-th/9807025, with one equation being added,
a few sentences rewritten, and some spelling mistakes corrected. 7 page,
Revtex, no figur
Development of a two day wellbeing course for supporters of teenagers and young adults (TYA) with cancer
Lifshitz transition and van Hove singularity in a Topological Dirac Semimetal
A topological Dirac semimetal is a novel state of quantum matter which has
recently attracted much attention as an apparent 3D version of graphene. In
this paper, we report critically important results on the electronic structure
of the 3D Dirac semimetal Na3Bi at a surface that reveals its nontrivial
groundstate. Our studies, for the first time, reveal that the two 3D Dirac
cones go through a topological change in the constant energy contour as a
function of the binding energy, featuring a Lifshitz point, which is missing in
a strict 3D analog of graphene (in other words Na3Bi is not a true 3D analog of
graphene). Our results identify the first example of a band saddle point
singularity in 3D Dirac materials. This is in contrast to its 2D analogs such
as graphene and the helical Dirac surface states of a topological insulator.
The observation of multiple Dirac nodes in Na3Bi connecting via a Lifshitz
point along its crystalline rotational axis away from the Kramers point serves
as a decisive signature for the symmetry-protected nature of the Dirac
semimetal's topological groundstate.Comment: 5 pages, 4 Figures, Related papers on topological Fermi arcs and Weyl
Semimetals (WSMs) are at
http://physics.princeton.edu/zahidhasangroup/index.htm
Perturbative Expansion around the Gaussian Effective Potential of the Fermion Field Theory
We have extended the perturbative expansion method around the Gaussian
effective action to the fermionic field theory, by taking the 2-dimensional
Gross-Neveu model as an example. We have computed both the zero temperature and
the finite temperature effective potentials of the Gross-Neveu model up to the
first perturbative correction terms, and have found that the critical
temperature, at which dynamically broken symmetry is restored, is significantly
improved for small value of the flavour number.Comment: 14pages, no figures, other comments Typographical errors are
corrected and new references are adde
Connected Green function approach to ground state symmetry breaking in -theory
Using the cluster expansions for n-point Green functions we derive a closed
set of dynamical equations of motion for connected equal-time Green functions
by neglecting all connected functions higher than order for the
-theory in dimensions. We apply the equations to the
investigation of spontaneous ground state symmetry breaking, i.e. to the
evaluation of the effective potential at temperature . Within our momentum
space discretization we obtain a second order phase transition (in agreement
with the Simon-Griffith theorem) and a critical coupling of
as compared to a first order phase transition and
from the Gaussian effective potential approach.Comment: 25 Revtex pages, 5 figures available via fpt from the directory
ugi-94-11 of [email protected] as one postscript file (there
was a bug in our calculations, all numerical results and figures have changed
significantly), ugi-94-1
Probability amplitude in quantum like games
Examples of games between two partners with mixed strategies, calculated by
the use of the probability amplitude are given. The first game is described by
the quantum formalism of spin one half system for which two noncommuting
observables are measured.
The second game corresponds to the spin one case.
Quantum logical orthocomplemented nondistributive lattices for these two
games are presented. Interference terms for the probability amplitudes are
analyzed by using so called contextual approach to probability (in the von
Mises frequency approach). We underline that our games are not based on using
of some microscopic systems. The whole scenario is macroscopic.Comment: Quantum-like model
London relation and fluxoid quantization for monopole currents in U(1) lattice gauge theory
We explore the analogy between quark confinement and the Meissner effect in
superconductors. We measure the response of color-magnetic "supercurrents" from
Dirac magnetic monopoles to the presence of a static quark-antiquark pair in
four dimensional U(1) lattice gauge theory. Our results indicate that in the
confined phase these currents screen the color-electric flux due to the quarks
in an electric analogy of the Meisner effect. We show that U(1) lattice guage
theory obeys both a dual London equation and an electric fluxoid quantization
condition.Comment: LSUHEP-1-92 May 1992, 13 page
Transcriptome analysis of peripheral blood mononuclear cells in human subjects following a 36 h fast provides evidence of effects on genes regulating inflammation, apoptosis and energy metabolism
There is growing interest in the potential health benefits of diets that involve regular periods of fasting. While animal studies have provided compelling evidence that feeding patterns such as alternate-day fasting can increase longevity and reduce incidence of many chronic diseases, the evidence from human studies is much more limited and equivocal. Additionally, although several candidate processes have been proposed to contribute to the health benefits observed in animals, the precise molecular mechanisms responsible remain to be elucidated. The study described here examined the effects of an extended fast on gene transcript profiles in peripheral blood mononuclear cells from ten apparently healthy subjects, comparing transcript profiles after an overnight fast, sampled on four occasions at weekly intervals, with those observed on a single occasion after a further 24 h of fasting. Analysis of the overnight fasted data revealed marked inter-individual differences, some of which were associated with parameters such as gender and subject body mass. For example, a striking positive association between body mass index and the expression of genes regulated by type 1 interferon was observed. Relatively subtle changes were observed following the extended fast. Nonetheless, the pattern of changes was consistent with stimulation of fatty acid oxidation, alterations in cell cycling and apoptosis and decreased expression of key pro-inflammatory genes. Stimulation of fatty acid oxidation is an expected response, most likely in all tissues, to fasting. The other processes highlighted provide indications of potential mechanisms that could contribute to the putative beneficial effects of intermittent fasting in humans
Transcriptome analysis of peripheral blood mononuclear cells in human subjects following a 36 h fast provides evidence of effects on genes regulating inflammation, apoptosis and energy metabolism.
There is growing interest in the potential health benefits of diets that involve regular periods of fasting. While animal studies have provided compelling evidence that feeding patterns such as alternate-day fasting can increase longevity and reduce incidence of many chronic diseases, the evidence from human studies is much more limited and equivocal. Additionally, although several candidate processes have been proposed to contribute to the health benefits observed in animals, the precise molecular mechanisms responsible remain to be elucidated. The study described here examined the effects of an extended fast on gene transcript profiles in peripheral blood mononuclear cells from ten apparently healthy subjects, comparing transcript profiles after an overnight fast, sampled on four occasions at weekly intervals, with those observed on a single occasion after a further 24 h of fasting. Analysis of the overnight fasted data revealed marked inter-individual differences, some of which were associated with parameters such as gender and subject body mass. For example, a striking positive association between body mass index and the expression of genes regulated by type 1 interferon was observed. Relatively subtle changes were observed following the extended fast. Nonetheless, the pattern of changes was consistent with stimulation of fatty acid oxidation, alterations in cell cycling and apoptosis and decreased expression of key pro-inflammatory genes. Stimulation of fatty acid oxidation is an expected response, most likely in all tissues, to fasting. The other processes highlighted provide indications of potential mechanisms that could contribute to the putative beneficial effects of intermittent fasting in humans
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