314 research outputs found
The ALF (Algorithms for Lattice Fermions) project release 2.0. Documentation for the auxiliary-field quantum Monte Carlo code
The Algorithms for Lattice Fermions package provides a general code for the
finite-temperature and projective auxiliary-field quantum Monte Carlo
algorithm. The code is engineered to be able to simulate any model that can be
written in terms of sums of single-body operators, of squares of single-body
operators and single-body operators coupled to a bosonic field with given
dynamics. The package includes five pre-defined model classes: SU(N) Kondo,
SU(N) Hubbard, SU(N) t-V and SU(N) models with long range Coulomb repulsion on
honeycomb, square and N-leg lattices, as well as unconstrained lattice
gauge theories coupled to fermionic and matter. An implementation of the
stochastic Maximum Entropy method is also provided. One can download the code
from our Git instance at
https://git.physik.uni-wuerzburg.de/ALF/ALF/-/tree/ALF-2.0 and sign in to file
issues.Comment: 121 pages, 11 figures. v3: quick tutorial section added, typos
corrected, etc. Submission to SciPost. arXiv admin note: text overlap with
arXiv:1704.0013
Calibration of the response function of CsI(Tl) scintillators to intermediate-energy heavy ions
Abstract The response function of 2-cm-thick CsI(Tl) scintillators with photodiode readouts were studied by directly exposing the detectors to beams of heavy ions (2≤Z≤36) with energy up to 25 MeV/u. The dependence of the light output on the energy (E) as well as on the atomic number and the mass of the ion is analyzed and discussed, and a parameterization of the light output as a function of Z and E is proposed
Molecular and cellular mechanisms in nervous system-specific carcinogenesis by N-ethyl-N-nitrosourea
A single pulse of N-ethyl-N-nitrosourea (ENU), applied to BDIX rats during the perinatal age, specifically results in a high incidence of neuroectodermal neoplasms in the central and peripheral nervous system (NS). The pronounced sensitivity of the developing NS suggests a dependence of the carcinogenic effect on the proliferative and/or differentiative state of the target cells at the time of the ENU pulse. The specificity of ENU for the NS cannot be due to tissue variations in the degree of carcinogen-cell interactions, since the reactive, electrophilic ethyl cation is produced by rapid, nonenzymatic decomposition of ENU indiscriminately in all tissues. Correspondingly, the initial molar fractions of ethylated purine bases are similar in the DNA of "high-risk" (perinatal brain) and "low-risk" tissues (e.g., liver; adult brain). However, while the respective half lives in DNA of N7-ethylguanine and N3-ethyladenine show only minor differences for both types of tissues, the mutagenic ethylation product 06-ethylguanine is removed from brain DNA very much more slowly than from the DNA of other tissues. Together with their high rate of DNA replication during the perinatal age, the incapacity of rat brain cells for enzymatic elimination of 06-alkylguanine from their DNA could account for an increased probability of neoplastic conversion, and hence for the NS specificity of ENU in the rat
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