418 research outputs found
Lobbies contra Agrarwende
Eine Agrarwende benötigt modifizierte politisch-rechtliche Rahmenbedingungen und ein offenes Beratungssystem, das sie flankiert und unterstützt. Eine aktuelle Studie der Lobbyverflechtungen in Deutschland zeigt, dass es vor allem an Letzterem noch hapert
The quest for the Cabibbo Kobayashi Maskawa Matrix
A piece of the Standard Model presently undergoing intense experimental
scrutiny is the Cabibbo Kobayashi Maskawa matrix. Several different
measurements are planned to enrich the spectrum of experimental constraints and
thus provide one of the most stringent tests of Standard Model validity. The
success of this program is closely related to theoretical progress in
evaluating QCD matrix elements in a non-perturbative regime, as we need to
extract fundamental quark properties from observations on decays involving
hadrons. This interplay between experimental and theoretical progress will be
illustrated in the context of the present knowledge of the magnitudes of the
quark mixing parameters and .Comment: 10 pages, 1 figure, contributed paper to BEAUTY 200
Three-Dimensional Light Bullets in Arrays of Waveguides
We report the first experimental observation of 3D-LBs, excited by
femtosecond pulses in a system featuring quasi-instantaneous cubic nonlinearity
and a periodic, transversally-modulated refractive index. Stringent evidence of
the excitation of LBs is based on time-gated images and spectra which perfectly
match our numerical simulations. Furthermore, we reveal a novel evolution
mechanism forcing the LBs to follow varying dispersion/diffraction conditions,
until they leave their existence range and decay.Comment: 4 pages, 5 figures - Published by the American Physical Societ
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Intra-cavity measurement concept of dispersion properties with a tunable fiber-integrated laser
The dispersion properties of fibers depict a key characteristic to model the propagation of ultra-short pulses in waveguides. In the following, a new method is presented to directly measure the dispersion properties of fibers and optical components in the time domain. The analysis is based on pulse shape variations along the tuning range of a theta cavity fiber laser (TCFL) depending on the adjusted repetition rate. The automated measurement procedure, evaluating pulse symmetry, achieves a temporal sensitivity below 5 ps surpassing the resolution of the acquisition electronics. Exemplarily, two samples of Nufern PM980-XP fiber are investigated with an Yb-doped tunable TCFL retrieving the mean dispersion parameter D? by comparative measurements. The obtained results are compared to a reference method based on spectral interferometry. With deviations in D? between either approach of 0.3% and 1.3%, respectively, the results agree well within the measurement errors of the TCFL, verifying the presented concept. Due to the pulse formation process extending over multiple round trips, this approach achieves an enhanced sensitivity compared to competing direct temporal methods. Together with an alignment free operation, the fiber-integrated TCFL depicts a simple and robust concept showing potential in specific measurement scenarios such as in quality management. © 2019 Astro Ltd
Third-generation leptoquark decays and collider searches
Collider searches for first-, second-, and third-generation scalar (S) or
vector (V) leptoquarks (LQs) focus on the quark-lepton decay modes S,V -> q l.
For SU(2)-doublet and -triplet leptoquarks with a sufficiently large splitting
between the components, decays involving real W-boson emission (such as
S_2^{(+5/3)} -> S_2^{(+2/3)} W^{+} and others) become possible and can change
the patterns of leptoquark decays. For third-generation leptoquarks, where
these mass splittings might be large, such modes could dominate certain
leptoquark decays as they are (if kinematically allowed) guaranteed to be of
order g^2 where g is the electroweak coupling. We calculate the decay rates for
all such processes involving SU(2)-doublet and triplet, scalar and vector
leptoquarks. Standard limits on mass splittings from precision electroweak
measurements imply that only such decays involving SU(2)-doublet scalar LQs are
likely kinematically possible.Comment: 13 pages, LaTeX, 2 separate postscript figure
CLEO Contributions to Tau Physics
We review many of the contributions of the CLEO experiment to tau physics.
Topics discussed are: branching fractions for major decay modes and tests of
lepton universality; rare decays; forbidden decays; Michel parameters and spin
physics; hadronic sub-structure and resonance parameters; the tau mass, tau
lifetime, and tau neutrino mass; searches for CP violation in tau decay; tau
pair production, dipole moments, and CP violating EDM; and tau physics at
CLEO-III and at CLEO-c.Comment: Invited talk at the Seventh International Workshop on Tau Lepton
Physics (TAU02), Santa Cruz, Ca, USA, Sept 2002, 14 pages, LaTeX, 21 eps
figure
Interfaces with a single growth inhomogeneity and anchored boundaries
The dynamics of a one dimensional growth model involving attachment and
detachment of particles is studied in the presence of a localized growth
inhomogeneity along with anchored boundary conditions. At large times, the
latter enforce an equilibrium stationary regime which allows for an exact
calculation of roughening exponents. The stochastic evolution is related to a
spin Hamiltonian whose spectrum gap embodies the dynamic scaling exponent of
late stages. For vanishing gaps the interface can exhibit a slow morphological
transition followed by a change of scaling regimes which are studied
numerically. Instead, a faceting dynamics arises for gapful situations.Comment: REVTeX, 11 pages, 9 Postscript figure
Mirabegron-induced brown fat activation does not exacerbate atherosclerosis in mice with a functional hepatic ApoE-LDLR pathway
Activation of brown adipose tissue (BAT) with the β3-adrenergic receptor agonist CL316,243 protects mice from atherosclerosis development, and the presence of metabolically active BAT is associated with cardiometabolic health in humans. In contrast, exposure to cold or treatment with the clinically used β3-adrenergic receptor agonist mirabegron to activate BAT exacerbates atherosclerosis in apolipoprotein E (ApoE)- and low-density lipoprotein receptor (LDLR)-deficient mice, both lacking a functional ApoE-LDLR pathway crucial for lipoprotein remnant clearance. We, therefore, investigated the effects of mirabegron treatment on dyslipidemia and atherosclerosis development in APOE*3-Leiden.CETP mice, a humanized lipoprotein metabolism model with a functional ApoE-LDLR clearance pathway. Mirabegron activated BAT and induced white adipose tissue (WAT) browning, accompanied by selectively increased fat oxidation and attenuated fat mass gain. Mirabegron increased the uptake of fatty acids derived from triglyceride (TG)-rich lipoproteins by BAT and WAT, which was coupled to increased hepatic uptake of the generated cholesterol-enriched core remnants. Mirabegron also promoted hepatic very low-density lipoprotein (VLDL) production, likely due to an increased flux of fatty acids from WAT to the liver, and resulted in transient elevation in plasma TG levels followed by a substantial decrease in plasma TGs. These effects led to a trend toward lower plasma cholesterol levels and reduced atherosclerosis. We conclude that BAT activation by mirabegron leads to substantial metabolic benefits in APOE*3-Leiden.CETP mice, and mirabegron treatment is certainly not atherogenic. These data underscore the importance of the choice of experimental models when investigating the effect of BAT activation on lipoprotein metabolism and atherosclerosis.</p
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