4,667 research outputs found
Lepton-Flavor Violation with Non-universal Soft Terms
We study the lepton-flavor violation processes tau ->mu gamma and mu->e gamma
in two different examples of models with non-universal soft breaking terms
derived from strings. We show that the predictions are quite different from
those of universal scenarios. Non-universal A-terms provide an interesting
framework to enhance the supersymmetric contributions to CP violation effects.
We observe that in the case of the lepton-flavor violation we study, the
non-universality of the scalar masses enhances the branching ratios more
significantly than the non-universality of the A-terms. We find that the
current experimental bounds on these processes restrict both the parameter
space of the models and the texture of the Yukawa couplings which predicts the
lepton masses, providing at the same time an interesting experimental test for
physics beyond the Standard Model.Comment: 15 pages, 6 figures minor change
Simulations of the Kelvin-Helmholtz instability driven by coronal mass ejections in the turbulent corona
Recent high resolution AIA/SDO images show evidence of the development of the
Kelvin-Helmholtz instability, as coronal mass ejections (CMEs) expand in the
ambient corona. A large-scale magnetic field mostly tangential to the interface
is inferred, both on the CME and on the background sides. However, the magnetic
field component along the shear flow is not strong enough to quench the
instability. There is also observational evidence that the ambient corona is in
a turbulent regime, and therefore the criteria for the development of the
instability are a-priori expected to differ from the laminar case. To study the
evolution of the Kelvin-Helmholtz instability with a turbulent background, we
perform three-dimensional simulations of the incompressible magnetohydrodynamic
equations. The instability is driven by a velocity profile tangential to the
CME-corona interface, which we simulate through a hyperbolic tangent profile.
The turbulent background is generated by the application of a stationary
stirring force. We compute the instability growth-rate for different values of
the turbulence intensity, and find that the role of turbulence is to attenuate
the growth. The fact that the Kelvin-Helmholtz instability is observed, sets an
upper limit to the correlation length of the coronal background turbulence
Plasmonic edge states: an electrostatic eigenmode description
We consider periodic arrangements of metal nanostructures and study the
effect of periodicity on the localised surface plasmon resonance of the
structures within an electrostatic eigenmode approximation. We show that within
this limit, the collective surface plasmon resonances of the periodic
structures can be expressed in terms of superpositions of the eigenmodes of
uncoupled nanostructures that exhibit a standing--wave character delocalised
across the entire periodic structure. The formalism derived successfully
enables the design and accounts for the observation of plasmonic edge-states in
periodic structures
Direct frequency comb measurements of absolute optical frequencies and population transfer dynamics
A phase-stabilized femtosecond laser comb is directly used for
high-resolution spectroscopy and absolute optical frequency measurements of
one- and two-photon transitions in laser-cooled \rb atoms. Absolute atomic
transition frequencies, such as the 5S F=2 \ra 7S F"=2
two-photon resonance measured at 788 794 768 921(44) kHz, are determined
without \textit{a priori} knowledge about their values. Detailed dynamics of
population transfer driven by a sequence of pulses are uncovered and taken into
account for the measurement of the 5P states via resonantly enhanced two-photon
transitions.Comment: 5 pages, 4 figures, submitte
NGcGM3 Ganglioside: A Privileged Target for Cancer Vaccines
Active specific immunotherapy is a promising field in cancer research. N-glycolyl (NGc) gangliosides, and particularly NGcGM3, have received attention as a privileged target for cancer therapy. Many clinical trials have been performed with the anti-NGc-containing gangliosides anti-idiotype monoclonal antibody racotumomab (formerly known as 1E10) and the conjugated NGcGM3/VSSP vaccine for immunotherapy of melanoma, breast, and lung cancer. The present paper examines the role of NGc-gangliosides in tumor biology as well as the available preclinical and clinical data on these vaccine products. A brief discussion on the relevance of prioritization of cancer antigens in vaccine development is also included
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