6,606 research outputs found
Deuteron Magnetic Quadrupole Moment From Chiral Effective Field Theory
We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading
order in the systematic expansion provided by chiral effective field theory. We
take into account parity and time-reversal violation which, at the quark-gluon
level, results from the QCD vacuum angle and dimension-six operators that
originate from physics beyond the Standard Model. We show that the deuteron MQM
can be expressed in terms of five low-energy constants that appear in the
parity- and time-reversal-violating nuclear potential and electromagnetic
current, four of which also contribute to the electric dipole moments of light
nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the
QCD vacuum angle and that its measurement would be complementary to the
proposed measurements of light-nuclear EDMs
Fusarium species and mycotoxin profiles on commercial maize hybrids in Germany
Abstract High year-to-year variability in the incidence of Fusarium spp. and mycotoxin contamination was observed in a two-year survey investigating the impact of maize ear rot in 84 field samples from Germany. Fusarium verticillioides, F. graminearum, and F. proliferatum were the predominant species infecting maize kernels in 2006, whereas in 2007 the most frequently isolated species were F. graminearum, F. cerealis and F. subglutinans. Fourteen Fusariumrelated mycotoxins were detected as contaminants of maize kernels analyzed by a multi-mycotoxin determination method. In 2006, a growth season characterized by high temperature and low rainfall during anthesis and early grain filling, 75% of the maize samples were contaminated with deoxynivalenol, 34% with fumonisins and 27% with zearalenone. In 2007, characterized by moderate temperatures and frequent rainfall during the entire growth season, none of the 40 maize samples had quantifiable levels of fumonisins while deoxynivalenol and zearalenone were detected in 90% and 93% of the fields, respectively. In addition, 3-acetyldeoxynivalenol, 15-acetyldeoxnivalenol, moniliformin, beauvericin, nivalenol and enniatin B were detected as common contaminants produced in both growing seasons. The results demonstrate a significant mycotoxin contamination associated with maize ear rots in Germany and indicate, with regard to anticipated climate change, that fumonisins-producing species already present in German maize production may become more important. Keywords Deoxynivalenol . Ear rot . F. verticillioides . F. graminearum . Fumonisin . Zearalenon
The Dynamical Cluster Approximation: Non-Local Dynamics of Correlated Electron Systems
We recently introduced the dynamical cluster approximation(DCA), a new
technique that includes short-ranged dynamical correlations in addition to the
local dynamics of the dynamical mean field approximation while preserving
causality. The technique is based on an iterative self-consistency scheme on a
finite size periodic cluster. The dynamical mean field approximation (exact
result) is obtained by taking the cluster to a single site (the thermodynamic
limit). Here, we provide details of our method, explicitly show that it is
causal, systematic, -derivable, and that it becomes conserving as the
cluster size increases. We demonstrate the DCA by applying it to a Quantum
Monte Carlo and Exact Enumeration study of the two-dimensional Falicov-Kimball
model. The resulting spectral functions preserve causality, and the spectra and
the CDW transition temperature converge quickly and systematically to the
thermodynamic limit as the cluster size increases.Comment: 19 pages, 13 postscript figures, revte
Electric Dipole Moments of Light Nuclei From Chiral Effective Field Theory
We set up the framework for the calculation of electric dipole moments (EDMs)
of light nuclei using the systematic expansion provided by chiral effective
field theory (EFT). We take into account parity (P) and time-reversal (T)
violation which, at the quark-gluon level, originates from the QCD vacuum angle
and dimension-six operators capturing physics beyond the Standard Model. We
argue that EDMs of light nuclei can be expressed in terms of six low-energy
constants that appear in the P- and T-violating nuclear potential and electric
current. As examples, we calculate the EDMs of the deuteron, the triton, and
3He in leading order in the EFT expansion
Self-report Versus Measured Physical Activity Levels During Outpatient Cardiac Rehabilitation
Purpose: Many patients with coronary artery disease (CAD) do not achieve the recommended physical activity (PA) levels during and after cardiac rehabilitation (CR). The aim of this study was to analyze moderate to vigorous physical activity (MVPA) levels and the differences between perceived (self-reported) and measured (activity monitor) MVPA in CAD patients during CR. The second aim was to analyze which patient characteristics were associated with this difference. Methods: A two-center observational-sectional study was conducted within the Department of Rehabilitation Medicine of the University Medical Center Groningen between January and April 2018. Adults with CAD, following an outpatient CR program, were included. Perceived MVPA was assessed with the Short Questionnaire to Assess Health-enhancing Physical Activity and compared with ActivPAL3 activity monitor outcomes over a period of 7 d. Results: Fifty-one patients with CAD (age 59.4 ± 7.1 yr, eight females) were recruited. Four patients (8%) did not achieve the recommended guideline level of ≥150 min/wk of MVPA. Patients spent ≥80% of the week in sedentary activities. Patients overestimated MVPA with a median of 805 (218, 1363) min/wk (P < .001). The selected patient characteristics (age, body mass index, type of CAD, type of CR, social support, and self-efficacy) were not associated with this overestimation. Conclusions: Most patients with CAD, participating in an outpatient CR program, do achieve MVPA exercise recommendations but spend simultaneously too much time in sedentary activities
Parity- and Time-Reversal-Violating Form Factors of the Deuteron
We calculate the electric-dipole and magnetic-quadrupole form factors of the
deuteron that arise as a low-energy manifestation of parity and time-reversal
violation in quark-gluon interactions of effective dimension four and six: the
QCD vacuum angle, the quark electric and chromo-electric dipole moments, and
the gluon chromo-electric dipole moment. Within the framework of two-flavor
chiral perturbation theory, we show that the relative sizes of the
corresponding moments allow an identification of the symmetry-breaking source
First principles studies of modulated Co/Cu superlattices with strongly and weakly exchange biased Co-monolayers
First-principles calculations have been performed in order to determine
effective exchange integrals between {\it strongly} and {\it weakly}
exchange-coupled Co monolayers in certain modulated periodic
-type superlattices with three non-equivalent Co planes, which
have not yet been studied hitherto. For we find that the two
non-equivalent exchange integrals have opposite signs, i.e.~the strong coupling
is antiferromagnetic and the weak coupling ferromagnetic, and differ for from each other by one order of magnitude. It is shown that the results
depend on the system as a whole and could not be obtained from separate parts.
Finally we suggest that ''spin valve'' systems of such kind should be
considered when trying to obtain good magneto-resistance together with low
switching-fields.Comment: LaTex, 9 pages, including two .eps-figure
Insulator-to-metal crossover induced by local spin fluctuations in strongly correlated systems
We study the simplified Hubbard (SH) model in the presence of a transverse
field in the infinite dimension limit. The relevant one-particle Green's
functions of the model are obtained by means a perturbative treatment of the
hopping and of the transverse field around the atomic limit. We consider an
analytical solution for the impurity problem. It is shown that this solution is
very accurate in describing the spectral properties of the heavy-particles of
the SH for intermediate and strong values of the on-site Coulomb interaction
. We find that for large values of an insulator-metal transition takes
place as a function of the transverse field. We analyze the metallic phase
through the behavior of the density of states and of the optical conductivity
and static resistivity. Our results for the latter quantity agree with what is
observed in experiments on .Comment: 6 pages, 5 figures, to appear in Journal of Physics: Condensed Matte
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