Filamentation processes and dynamical excitation of light condensates in optical media with competing nonlinearities

We analyze both theoretically and by means of numerical simulations the phenomena of filamentation and dynamical formation of self-guided nonlinear waves in media featuring competing cubic and quintic nonlinearities. We provide a theoretical description of recent experiments in terms of a linear stability analysis supported with simulations, showing the possibility of experimental observation of the modulational instability suppression of intense light pulses travelling across such nonlinear media. We also show a novel mechanism of indirect excitation of {\em light condensates} by means of coalescence processes of nonlinear coherent structures produced by managed filamentation of high power laser beams.Comment: 6 pages, 4 figure

Photons uncertainty solves Einstein-Podolsky-Rosen paradox

Einstein, Podolsky and Rosen (EPR) pointed out that the quantum-mechanical description of "physical reality" implied an unphysical, instantaneous action between distant measurements. To avoid such an action at a distance, EPR concluded that Quantum Mechanics had to be incomplete. However, its extensions involving additional "hidden variables", allowing for the recovery of determinism and locality, have been disproved experimentally (Bell's theorem). Here, I present an opposite solution of the paradox based on the greater indeterminism of the modern Quantum Field Theory (QFT) description of Particle Physics, that prevents the preparation of any state having a definite number of particles. The resulting uncertainty in photons radiation has interesting consequences in Quantum Information Theory (e.g. cryptography and teleportation). Moreover, since it allows for less elements of EPR physical reality than the old non-relativistic Quantum Mechanics, QFT satisfies the EPR condition of completeness without the need of hidden variables. The residual physical reality does never violate locality, thus the unique objective proof of "quantum nonlocality" is removed in an interpretation-independent way. On the other hand, the supposed nonlocality of the EPR correlations turns out to be a problem of the interpretation of the theory. If we do not rely on hidden variables or new physics beyond QFT, the unique viable interpretation is a minimal statistical one, that preserves locality and Lorentz symmetry.Comment: Published version, with updated referenc

Human Amniocytes Are Receptive to Chemically Induced Reprogramming to Pluripotency

Restoring pluripotency using chemical compounds alone would be a major step forward in developing clinical-grade pluripotent stem cells, but this has not yet been reported in human cells. We previously demonstrated that VPA_ AFS cells, human amniocytes cultivated with valproic acid (VPA) acquired functional pluripotency while remaining distinct from human embryonic stem cells (hESCs), questioning the relationship between the modulation of cell fate and molecular regulation of the pluripotency network. Here, we used single-cell analysis and functional assays to reveal that VPA treatment resulted in a homogeneous population of self-renewing non-transformed cells that fulfill the hallmarks of pluripotency, i.e., a short G1 phase, a dependence on glycolytic metabolism, expression of epigenetic modifications on histones 3 and 4, and reactivation of endogenous OCT4 and downstream targets at a lower level than that observed in hESCs. Mechanistic insights into the process of VPA-induced reprogramming revealed that it was dependent on OCT4 promoter activation, which was achieved independently of the PI3K (phosphatidylinositol 3-kinase)/ AKT/ mTOR (mammalian target of rapamycin) pathway or GSK3 beta inhibition but was concomitant with the presence of acetylated histones H3K9 and H3K56, which promote pluripotency. Our data identify, for the first time, the pluripotent transcriptional and molecular signature and metabolic status of human chemically induced pluripotent stem cells

Conceptual design of superferric magnets for PS2

We analyze feasibility and cost of a superferric magnet design for the PS2. Specifically, we provide the conceptual design of dipole and quadrupoles, including considerations on cryogenics and powering. The magnets have warm iron yoke, and cryostated superconducting coils embedded in the magnet, which reduces AC loss at cryogenic temperature. The superconductor has large Operating margin to endure beam loss and operating loads over a long period of time. Although conservative, and without any critical dependence on novel technology developments, this superconducting option appears to be attractive as a low-power alternative to the normal-conducting magnets that are the present baseline for the PS2 design. In addition it provides flexibility in the selection of flat-top duration at no additional cost. This study is the conclusion of the conceptual design work started within the scope of the CARE HHH-AMT activities, following inputs from the workshops ECOMAG and LUMI-06, and finally spurred by the recent discussions on the opportunity of an R&D for the PS2 magnets

Unusual disordering processes of oxygen overlayers on Rh(111): A combined diffraction study using thermal He atoms and low-energy electrons

The temperature-dependent behavior of the Rh(111)-(2X2)-1O phase was investigated by He-atom scattering (HAS) and low-energy electron diffraction. The adsorption system undergoes an order-disorder phase transition at Tc=280±5 K, with critical exponents found to be consistent with the four-state Potts model. Beyond the phase transition the HAS specular peak intensity exhibits a strong and reversible increase. This finding points toward a reduction of the surface charge-density corrugation induced by the phase transition itself. Around 160 K, hydrogen adsorbed on the Rh(111)-(2X2)-1O surface reacts with oxygen to form water, and drives the overlayer in an out-of-equilibrium condition which is characterized by a dramatic domain-wall proliferation

Fast cycled superconducting magnets for the upgrade of the LHC injector complex

An upgrade of the LHC injection chain, and especially the sequence of PS and SPS, up to an extraction energy of 1 TeV, is one of the steps considered to improve the performance of the whole LHC accelerator complex. The magnets for this upgrade require central magnetic field from 2 T (for a PS upgrade) to 4.5 T (for an SPS upgrade), and field ramp rate ranging from 1.5 to 2.5 T/s. In this paper we discuss under which conditions superconducting magnets are attractive in this range of operating field and field ramp-rate, and we list the outstanding issues to be adddressed by a dedicated R&D