6,707 research outputs found
Weighing the Neutrino
We investigate the potential of short-baseline experiments in order to
measure the dispersion relation of the (muon) neutrino, with a prospect of
eventually measuring the neutrino mass. As a byproduct, the experiment would
help to constrain parameters of Lorentz-violating effects in the neutrino
sector. The potential of a high-flux laser-accelerated proton beam (e.g., at
the upcoming ELI facility), incident on a thick target composed of a light
element to produce pions, with a subsequent decay to muons and muon-neutrinos,
is discussed. We find a possibility for a muon neutrino mass measurement of
unprecedented accuracy.Comment: 12 pages; RevTe
On the applicability of the layered sine-Gordon model for Josephson-coupled high-T_c layered superconductors
We find a mapping of the layered sine-Gordon model to an equivalent gas of
topological excitations and determine the long-range interaction potentials of
the topological defects. This enables us to make a detailed comparison to the
so-called layered vortex gas, which can be obtained from the layered
Ginzburg-Landau model. The layered sine-Gordon model has been proposed in the
literature as a candidate field-theoretical model for Josephson-coupled
high-T_c superconductors, and the implications of our analysis for the
applicability of the layered sine-Gordon model to high-T_c superconductors are
discussed. We are led to the conjecture that the layered sine--Gordon and the
layered vortex gas models belong to different universality classes. The
determination of the critical temperature of the layered sine-Gordon model is
based on a renormalization-group analysis.Comment: 7 pages, accepted for publication in J. Phys.: Condens. Matte
Interplay of fixed points in scalar models
We performed the renormalization group analysis of scalar models exhibiting
spontaneous symmetry breaking. It is shown that an infrared fixed point appears
in the broken symmetric phase of the models, which induces a dynamical scale,
that can be identified with the correlation length. This enables one to
identify the type of the phase transition which shows similarity to the one
appearing in the crossover scale. The critical exponent of the
correlation length also proved to be equal in the crossover and the infrared
scaling regimes.Comment: 11 pages, 4 figure
Including nonlocality in exchange-correlation kernel from time-dependent current density functional theory: Application to the stopping power of electron liquids
We develop a scheme for building the scalar exchange-correlation (xc) kernel
of time-dependent density functional theory (TDDFT) from the tensorial kernel
of time-dependent {\em current} density functional theory (TDCDFT) and the
Kohn-Sham current density response function. Resorting to the local
approximation to the kernel of TDCDFT results in a nonlocal approximation to
the kernel of TDDFT, which is free of the contradictions that plague the
standard local density approximation (LDA) to TDDFT. As an application of this
general scheme, we calculate the dynamical xc contribution to the stopping
power of electron liquids for slow ions to find that our results are in
considerably better agreement with experiment than those obtained using TDDFT
in the conventional LDA.Comment: 6 pages, 3 figures, accepted to Phys. Rev.
Midlatitude and highâlatitude electron density profiles in the ionosphere of Saturn obtained by Cassini radio occultation observations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95024/1/jgra19781.pd
Secondary metabolites from Stachys palustris L.
In this work we report the first total analysis of the secondary metabolites from a sample of Stachys palustris L., an herbaceous perennial plant belonging to Lamiaceae, collected in Hungary.
The phytochemical analysis, performed by means of classical column chromatography and NMR spectroscopy and Mass spectrometry (MS), allowed us to isolate and identify eight compounds such as verbascoside (1) [1], echinacoside (2) [1], two isoscutellarein derivatives (3, 4) [2,3], chlorogenic acid (5) [3], harpagide (6) [4], 8-O-acetyl-harpagide (7) [4] and monomelittoside (8) [4]. These compounds belong to four different classes of chemical compounds namely phenyl-ethanoid glycosides (PhGs) (compounds 1, 2), flavonoids (compounds 3,4), caffeoyl-quinic acids (compound 5) and iridoids (compounds 6,7 and 8).
From a chemosystematic point of view, these compounds are all important: compounds (6) and (7) are considered as the major chemotaxonomic markers of the genus; compound (1) and (8) resulted new constituents in this species and compound (2) is even new in the genus. In addition to this, the co-occurrence of iridoids and PhGs has a chemosystematic importance since it is widely demonstrated their presence in Asterids [1, 3]. Lastly, compounds (3) and (4) such as compounds (5),(6) and (7) have already been found in Stachys species, giving, this way, evidence of a phytochemical pattern perfectly in accordance with those reported in literature for other members of this genus. Nevertheless, itâs worth to underline the fact that compounds (3) and (4), like all isoscutellarein derivatives containing allose, seem to have a restricted distribution in only some genera of Lamiaceae
Secondary metabolites from Stachys palustris L.
In this work we report the first total analysis of the secondary metabolites from a sample of Stachys palustris L., an herbaceous perennial plant belonging to Lamiaceae, collected in Hungary.
The phytochemical analysis, performed by means of classical column chromatography and NMR spectroscopy and Mass spectrometry (MS), allowed us to isolate and identify eight compounds such as verbascoside (1) [1], echinacoside (2) [1], two isoscutellarein derivatives (3, 4) [2,3], chlorogenic acid (5) [3], harpagide (6) [4], 8-O-acetyl-harpagide (7) [4] and monomelittoside (8) [4]. These compounds belong to four different classes of chemical compounds namely phenyl-ethanoid glycosides (PhGs) (compounds 1, 2), flavonoids (compounds 3,4), caffeoyl-quinic acids (compound 5) and iridoids (compounds 6,7 and 8).
From a chemosystematic point of view, these compounds are all important: compounds (6) and (7) are considered as the major chemotaxonomic markers of the genus; compound (1) and (8) resulted new constituents in this species and compound (2) is even new in the genus. In addition to this, the co-occurrence of iridoids and PhGs has a chemosystematic importance since it is widely demonstrated their presence in Asterids [1, 3]. Lastly, compounds (3) and (4) such as compounds (5),(6) and (7) have already been found in Stachys species, giving, this way, evidence of a phytochemical pattern perfectly in accordance with those reported in literature for other members of this genus. Nevertheless, itâs worth to underline the fact that compounds (3) and (4), like all isoscutellarein derivatives containing allose, seem to have a restricted distribution in only some genera of Lamiaceae
Occurrence statistics of cold, streaming ions in the nearâEarth magnetotail: Survey of PolarâTIDE observations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95347/1/jgra17705.pd
Time-dependent density-functional theory approach to nonlinear particle-solid interactions in comparison with scattering theory
An explicit expression for the quadratic density-response function of a
many-electron system is obtained in the framework of the time-dependent
density-functional theory, in terms of the linear and quadratic
density-response functions of noninteracting Kohn-Sham electrons and functional
derivatives of the time-dependent exchange-correlation potential. This is used
to evaluate the quadratic stopping power of a homogeneous electron gas for slow
ions, which is demonstrated to be equivalent to that obtained up to second
order in the ion charge in the framework of a fully nonlinear scattering
approach. Numerical calculations are reported, thereby exploring the range of
validity of quadratic-response theory.Comment: 14 pages, 3 figures. To appear in Journal of Physics: Condensed
Matte
Hidden symmetries in the asymmetric exclusion process
We present a spectral study of the evolution matrix of the totally asymmetric
exclusion process on a ring at half filling. The natural symmetries
(translation, charge conjugation combined with reflection) predict only two
fold degeneracies. However, we have found that degeneracies of higher order
also exist and, as the system size increases, higher and higher orders appear.
These degeneracies become generic in the limit of very large systems. This
behaviour can be explained by the Bethe Ansatz and suggests the presence of
hidden symmetries in the model.
Keywords: ASEP, Markov matrix, symmetries, spectral degeneracies, Bethe
Ansatz.Comment: 16 page
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