109 research outputs found
Functional renormalization group approach to the Yang-Lee edge singularity
We determine the scaling properties of the Yang-Lee edge singularity as
described by a one-component scalar field theory with imaginary cubic coupling,
using the nonperturbative functional renormalization group in
Euclidean dimensions. We find very good agreement with high-temperature series
data in dimensions and compare our results to recent estimates of
critical exponents obtained with the four-loop expansion and
the conformal bootstrap. The relevance of operator insertions at the
corresponding fixed point of the RG functions is discussed and we
estimate the error associated with truncations of the
scale-dependent effective action.Comment: 10 pages, 4 figures, updated reference to supplementary materia
On spinodal points and Lee-Yang edge singularities
We address a number of outstanding questions associated with the analytic
properties of the universal equation of state of the theory, which
describes the critical behavior of the Ising model and ubiquitous critical
points of the liquid-gas type. We focus on the relation between spinodal points
that limit the domain of metastability for temperatures below the critical
temperature, i.e., , and Lee-Yang edge singularities that
restrict the domain of analyticity around the point of zero magnetic field
for . The extended analyticity conjecture (due to Fonseca and
Zamolodchikov) posits that, for , the Lee-Yang edge
singularities are the closest singularities to the real axis. This has
interesting implications, in particular, that the spinodal singularities must
lie off the real axis for , in contrast to the commonly known result
of the mean-field approximation. We find that the parametric representation of
the Ising equation of state obtained in the expansion, as
well as the equation of state of the -symmetric theory at
large , are both nontrivially consistent with the conjecture. We analyze the
reason for the difficulty of addressing this issue using the
expansion. It is related to the long-standing paradox associated with the fact
that the vicinity of the Lee-Yang edge singularity is described by Fisher's
theory, which remains nonperturbative even for , where the
equation of state of the theory is expected to approach the mean-field
result. We resolve this paradox by deriving the Ginzburg criterion that
determines the size of the region around the Lee-Yang edge singularity where
mean-field theory no longer applies.Comment: 26 pages, 8 figures; v2: shortened Sec. 4.1 and streamlined
arguments/notation in Sec. 4.2, details moved to appendix, added reference 1
From quantum to classical dynamics: The relativistic model in the framework of the real-time functional renormalization group
We investigate the transition from unitary to dissipative dynamics in the
relativistic vector model with the
interaction using the nonperturbative functional renormalization group in the
real-time formalism. In thermal equilibrium, the theory is characterized by two
scales, the interaction range for coherent scattering of particles and the mean
free path determined by the rate of incoherent collisions with excitations in
the thermal medium. Their competition determines the renormalization group flow
and the effective dynamics of the model. Here we quantify the dynamic
properties of the model in terms of the scale-dependent dynamic critical
exponent in the limit of large temperatures and in
spatial dimensions. We contrast our results to the behavior expected at
vanishing temperature and address the question of the appropriate dynamic
universality class for the given microscopic theory.Comment: 32 pages, 12 captioned figures; revised and extended version accepted
for publication in PR
Mycotoxin contamination of maize (Zea mays L.) samples in Hungary, 2012–2017
Mycotoxin contamination of maize often raises risks for human and animal health. The most frequently detected mycotoxins in maize are trichothecenes, fumonisins, and aflatoxin. A total number of 17,011 maize samples were tested by SGS for their mycotoxin content between 2012 and 2017. The toxin results clearly show that the southern areas of the country had higher levels of toxin contamination than the average. According to the dataset, aflatoxin contamination has become regular but the appearance of fumonisins was also more frequent. Deoxynivalenol toxin accumulation in crops can also reach dangerous levels under favorable ecological conditions. The fluctuation between years and regisons is decisively shaped by the weather conditions. However, the two pathogens with less virulence (Fusarium verticillioides and Aspergillus flavus) must be taken into account and the contribution of insect pests. 72.63% of the total fumonisin concentration was defined as fumonisin B1, 20.34% as fumonisin B2, and 7.03% as fumonisin B3. The correlations between the three fumonisins analogs were higly significant (P = 0.001), and correlation coefficient varied between 0.961 and 0.998 across the six years of evaluation. This is the first complex evaluation of deoxynivalenol, fumonisin, and aflatoxin contamination of maize samples in Hungary
First molecular phylogenetic insights into the evolution of Eriocaulon (Eriocaulaceae, Poales)
Eriocaulon is a genus of c. 470 aquatic and wetland species of the monocot plant family Eriocaulaceae. It is widely distributed in Africa, Asia and America, with centres of species richness in the tropics. Most species of Eriocaulon grow in wetlands although some inhabit shallow rivers and streams with an apparent adaptive morphology of elongated submerged stems. In a previous molecular phylogenetic hypothesis, Eriocaulon was recovered as sister of the African endemic genus Mesanthemum. Several regional infrageneric classifications have been proposed for Eriocaulon. This study aims to critically assess the existing infrageneric classifications through phylogenetic reconstruction of infrageneric relationships, based on DNA sequence data of four chloroplast markers and one nuclear marker. There is little congruence between our molecular results and previous morphology-based infrageneric classifications. However, some similarities can be found, including Fyson’s sect. Leucantherae and Zhang’s sect. Apoda. Further phylogenetic studies, particularly focusing on less well sampled regions such as the Neotropics, will help provide a more global overview of the relationships in Eriocaulon and may enable suggesting the first global infrageneric classification
Vegetation-based landscape regions of Hungary.
he first version of the map of the Hungarian vegetation-based landscape regions were prepared
at the scale of 1 : 200,000 (1 km or higher resolution). The primary goal of the map was
to provide an exact background for the presentation and evaluation of the data of theMÉTA
database. Secondly, we intended to give an up-to-date and detailed vegetation-based division
of Hungary with a comprehensive nomenclature of the regions. Regions were primarily defined on the basis of their present zonal vegetation, or their dominant extrazonal or
edaphic vegetation. Where this was not possible, abiotic factors that influence the potential
vegetation, the flora were taken into consideration, thus, political and economical factors
were ignored. All region borders were defined by local expert botanists, mainly based on
their field knowledge. The map differs in many features from the currently used, country-
wide, flora- or geography-based divisions in many features. We consider our map to be
temporary (i.e. a work map), and we plan to refine and improve it after 5 years of testing
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