166 research outputs found
Surface wave non-reciprocity via time-modulated metamaterials
We investigate how Rayleigh waves interact with time-modulated resonators located on the free surface of a semi-infinite elastic medium. We begin by studying the dynamics of a single resonator with time-modulated stiffness, we evaluate the accuracy of an analytical approximation of the resonator response and identify the parameter ranges in which its behavior remains stable. Then, we develop an analytical model to describe the interaction between surface waves and an array of resonators with spatio-temporally modulated stiffness. By combining our analytical models with full-scale numerical simulations, we demonstrate that spatio-temporal stiffness modulation of this elastic metasurface leads to the emergence of non-reciprocal features in the Rayleigh wave spectrum. Specifically, we show how the frequency content of a propagating signal can be filtered and converted when traveling through the modulated medium, and illustrate how surface-to-bulk wave conversion plays a role in these phenomena. Throughout this article, we indicate bounds of modulation parameters for which our theory is reliable, thus providing guidelines for future experimental studies on the topic
Synthesis and biological evaluation of new natural phenolic (2E,4E,6E)-Octa-2,4,6-trienoic esters
In the present study the esterification of the OH groups of resveratrol, caffeic acid, ferulic acid, and -sitosterol with an antioxidant polyconjugated fatty acid, (2E,4E,6E)-octa-2,4,6-trienoic acid, was achieved. As the selective esterification of OH groups of natural compounds can affect their biological activity, a selective esterification of resveratrol and caffeic acid was performed by an enzymatic approach. The new resulting compounds were characterized spectroscopically (FT-IR, NMR mono, and bidimensional techniques); when necessary the experimental data were integrated by quantum chemical calculations. The antioxidant, anti-inflammatory and proliferative activity was evaluated. The good results encourage the use of these molecules as antioxidant and/or anti-inflammatory agents in dermocosmetic application
A New Selective PPARγ Modulator Inhibits Triglycerides Accumulation during Murine Adipocytes’ and Human Adipose-Derived Mesenchymal Stem Cells Differentiation
Understanding the molecular basis of adipogenesis is vital to identify new therapeutic targets to improve anti-obesity drugs. The adipogenic process could be a new target in the management of this disease. Our aim was to evaluate the effect of GMG-43AC, a selective peroxisome proliferator-activated receptor \u3b3 (PPAR\u3b3) modulator, during adipose differentiation of murine pre-adipocytes and human Adipose Derived Stem Cells (hADSCs). We differentiated 3T3-L1 cells and primary hADSCs in the presence of various doses of GMG-43AC and evaluated the differentiation efficiency measuring lipid accumulation, the expression of specific differentiation markers and the quantification of accumulated triglycerides. The treatment with GMG-43AC is not toxic as shown by cell viability assessments after the treatments. Our findings demonstrate the inhibition of lipid accumulation and the significant decrease in the expression of adipocyte-specific genes, such as PPAR\u3b3, FABP-4, and leptin. This effect was long lasting, as the removal of GMG-43AC from culture medium did not allow the restoration of adipogenic process. The above actions were confirmed in hADSCs exposed to adipogenic stimuli. Together, these results indicate that GMG-43AC efficiently inhibits adipocytes differentiation in murine and human cells, suggesting its possible function in the reversal of adipogenesis and modulation of lipolysis
The CCFM Monte Carlo generator CASCADE 2.2.0
CASCADE is a full hadron level Monte Carlo event generator for ep, \gamma p
and p\bar{p} and pp processes, which uses the CCFM evolution equation for the
initial state cascade in a backward evolution approach supplemented with off -
shell matrix elements for the hard scattering. A detailed program description
is given, with emphasis on parameters the user wants to change and variables
which completely specify the generated events
Non-global logarithms and jet algorithms in high-pT jet shapes
We consider jet-shape observables of the type proposed recently, where the
shapes of one or more high-pT jets, produced in a multi-jet event with definite
jet multiplicity, may be measured leaving other jets in the event unmeasured.
We point out the structure of the full next-to-leading logarithmic resummation
specifically including resummation of non-global logarithms in the leading-Nc
limit and emphasising their properties. We also point out differences between
jet algorithms in the context of soft gluon resummation for such observables.Comment: 22 pages, 4 figures. Title and a few words changed. Several typos
corrected. Version accepted by JHE
Jet vetoing at the LHC
We study the effect of a veto on additional jets in the rapidity region
between a pair of high transverse momentum jets at the LHC. We aim to sum the
most important logarithms in the ratio of the jet transverse momentum to the
veto scale and to that end we attempt to assess the significance of the
super-leading logarithms that appear at high orders in the perturbative
expansion. We also compare our results to those of HERWIG++, in an attempt to
ascertain the accuracy of the angular ordered parton shower. We find that there
are large corrections that arise for large enough jet transverse momenta as a
consequence of Coulomb gluon exchanges.Comment: 25 page
NLO QCD corrections to pseudoscalar Higgs production in the MSSM
We present a calculation of the two-loop quark-squark-gluino contributions to
pseudoscalar Higgs boson production via gluon fusion in the MSSM. We regularize
the loop integrals using the Pauli-Villars method, and obtain explicit and
compact analytic results based on an expansion in the heavy particle masses.
Our results - valid when the pseudoscalar Higgs boson is lighter than squarks
and gluinos - can be easily implemented in computer codes for an efficient and
accurate determination of the pseudoscalar production cross section.Comment: 26 pages, 4 figures. v2: comments added in section 3, version
published in JHE
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