Wave front reconstruction of Fresnel off-axis holograms with compensation of aberrations by means of phase-shifting digital holography

Off-axis holograms recorded with a CCD camera are numerically reconstructed in amplitude by calculating through the Fresnel–Kirchhoff integral. A phase-shifting Mach–Zehnder interferometer is used for recording four-quadrature phase-shifted off-axis holograms. The basic principle of this technique and its experimental verification are described. We show that the application of this algorithm allows for the suppression of the zero order of diffraction and of the twin image and that the contrast of the reconstructed images can be further enhanced by digital compensation of the aberrations introduced by the holographic recording system     

A counterexample to a lower bound for a class of pseudodifferential operators

We present a counterexample to a possible improvement of a lower bound for a class of pseudodifferential operators with symplectic characteristic manifold.

     

An eigenvalue Dirichlet problem involving the p-Laplacian with discontinuous nonlinearities

A multiplicity result for an eigenvalue Dirichlet problem involving the p-Laplacian with discontinuous nonlinearities is obtained. The proof is based on a three critical points theorem for nondifferentiable functionals.     

Flavour transitions of Dirac-Majorana neutrinos

From a phenomenological point of view, we study active-active and active-sterile flavour-changing (and flavour-conserving) oscillations of Dirac-Majorana neutrinos both in vacuum and in matter. The general expressions for the transition probabilities in vacuum are reported. We then investigate some interesting consequences following from particular simple forms of the neutrino mass matrices, and for the envisaged scenarios we discuss in detail neutrino propagation in matter. Special emphasis is given to the problem of occurrence of resonant enhancement of active-active and active-sterile neutrino oscillations in a medium. The peculiar novel features related to the Dirac-Majorana nature of neutrinos are particularly pointed out. Received: 20 February 1998 / Published online: 5 June 1998     

The Modulation of PCSK9 and LDLR by Supercritical CO2 Extracts of Mentha longifolia and Isolated Piperitone Oxide,an In Vitro Study

In the present study the ability of supercritical carbon dioxide (SCO₂) extracts of M. longifolia L. leaves to modulate low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression was evaluated in cultured human hepatoma cell lines Huh7 and HepG2. Two SCO₂ extracts, one oil (ML-SCO₂) and a semisolid (MW-SCO₂), were subjected to detailed chemical characterization by mono- and bidimensional nuclear magnetic resonance (1D, 2D-NMR), gas chromatography coupled with mass spectrometry (GC-MS) and liquid chromatography coupled with mass spectrometry (LC-MS). Chemical analysis revealed significant amounts of fatty acids, phytosterols and terpenoids. ML-SCO₂ was able to induce LDLR expression at a dose of 60 µg/mL in HuH7 and HepG2 cell lines. Furthermore, ML-SCO₂ reduced PCSK9 secretion in a concentration-dependent manner in both cell lines. Piperitone oxide, the most abundant compound of the volatile constituent of ML-SCO₂ (27% w/w), was isolated and tested for the same targets, showing a very effective reduction of PCSK9 expression. The overall results revealed the opportunity to obtain a new nutraceutical ingredient with a high amount of phytosterols and terpenoids using the SCO₂ extraction of M. longifolia L., a very well-known botanical species used as food. Furthermore, for the first time we report the high activity of piperitone oxide in the reduction of PCSK9 expression.     

Electrostatically-driven assembly of MWCNTs with a europium complex

Luminescent carbon-based materials have been prepared by electrostatic self-assembly of negatively-charged luminescent Eu(III)-complex with imidazolium-functionalized MWCNTs.