Artificially induced positronium oscillations in a two-sheeted spacetime: consequences on the observed decay processes

Following recent theoretical results, it is suggested that positronium (Ps) might undergo spontaneous oscillations between two 4D spacetime sheets whenever subjected to constant irrotational magnetic vector potentials. We show that these oscillations that would come together with o-Ps/p-Ps oscillations should have important consequences on Ps decay rates. Experimental setup and conditions are also suggested for demonstrating in non accelerator experiments this new invisible decay mode.Comment: 9 pages, 2 figures. Minor form correction. Accepted for publication in Int. J. of Modern Physics

Matter localization and resonant deconfinement in a two-sheeted spacetime

In recent papers, a model of a two-sheeted spacetime M4XZ2 was introduced and the quantum dynamics of massive fermions was studied in this framework. In the present study, we show that the physical predictions of the model are perfectly consistent with observations and most important, it can solve the puzzling problem of the four-dimensional localization of the fermion species in multidimensional spacetimes. It is demonstrated that fermion localization on the sheets arises from the combination of the discrete bulk structure and environmental interactions. The mechanism described in this paper can be seen as an alternative to the domain wall localization arising in continuous five dimensional spacetimes. Although tightly constrained, motions between the sheets are, however, not completely prohibited. As an illustration, a resonant mechanism through which fermion oscillations between the sheets might occur is described.Comment: 9 pages, 1 figure. Published version. Accepted for publication in Int. J. of Modern Physics

Resonant control of spin dynamics in ultracold quantum gases by microwave dressing

We study experimentally interaction-driven spin oscillations in optical lattices in the presence of an off-resonant microwave field. We show that the energy shift induced by this microwave field can be used to control the spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations. Finally, we propose a scheme based on this technique to create a flat sample with either singly- or doubly-occupied sites, starting from an inhomogeneous Mott insulator, where singly- and doubly-occupied sites coexist.Comment: 4 pages, 5 figure

DLI-CVD of TiO2–Cu antibacterial thin films: Growth and characterization

TiO2–Cu nanocomposite films were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on stainless steel, silicon and glass substrates with the goal to produce bactericidal surfaces. Copper bis (2,2,6,6-tetramethyl-3,5-heptadionate), Cu(TMHD)2, and titanium tetra-iso-propoxide, TTIP, were used as metalorganic precursors. Liquid solutions of these compounds in xylene were injected in a flash vaporization chamber connected to a cold wall MOCVD reactor. The deposition temperature was typically 683 K and the total pressure was 800 Pa. The copper content of the layers was controlled by the mole fraction of Cu (TMHD)2 which was adjusted by the injection parameters (injection frequency and concentration of the starting solution). The chemical, structural and physical characteristics of the films were investigated by XRD, XPS, FEG-SEM and TEM. Copper is incorporated as metal particles with a relatively large size distribution ranging from 20 to 400 nm (with a large majority in 20–100 nm) depending on the copper content of the films. The influence of the growth conditions on the structural features and the antibacterial properties of the thin films are reported and discussed

A new, substituted palladacycle for ppm level Pd-catalyzed Suzuki-Miyaura cross couplings in water.

A newly engineered palladacycle that contains substituents on the biphenyl rings along with the ligand HandaPhos is especially well-matched to an aqueous micellar medium, enabling valued Suzuki-Miyaura couplings to be run not only in water under mild conditions, but at 300 ppm of Pd catalyst. This general methodology has been applied to several targets in the pharmaceutical area. Multiple recyclings of the aqueous reaction mixture involving both the same as well as different coupling partners is demonstrated. Low temperature microscopy (cryo-TEM) indicates the nature and size of the particles acting as nanoreactors. Importantly, given the low loadings of Pd invested per reaction, ICP-MS analyses of residual palladium in the products shows levels to be expected that are well within FDA allowable limits

ADS-B Benefits to General Aviation and Barriers to Implementation

Automatic Dependent Surveillance -­‐ Broadcast (ADS-­‐B) will be the basis of the future surveillance system in the US. To achieve benefit from ADS-­‐B, aircraft have to be equipped with ADS-­‐B avionics across all stakeholders. General Aviation (GA) comprises over 96% of the active aircraft fleet in the US but average yearly utilization for GA aircraft is 21 times lower than that of commercial aircraft. Since many benefits from ADS-­‐B depend on aircraft utilization, concern exists that ADS-­‐B does not provide enough user benefit to GA, possibly resulting in delayed acceptance and aircraft equipage with ADS-­‐B avionics. One way of providing user benefits and thus increasing incentives for GA users to equip with ADS-­‐B is to create and implement ADS-­‐B applications that are of high value to those operators. ADS-­‐B Surveillance in non-­‐RADAR airspace and ADS-­‐B based Traffic Situation Awareness (TSA) are identified as two applications that are expected to provide significant benefit to GA. Both applications are evaluated and possible barriers to the delivery of benefit are identified. In order to identify where TSA would be most beneficial, ten years’ worth of NTSB mid-­‐air collision reports were reviewed. Ten years of ASRS and NMACS near mid-­‐air collision (MAC) reports were also reviewed. The analysis revealed that aircraft are most likely to encounter each other in the airport vicinity – specifically in the pattern (59% of MACs). Current Traffic Awareness systems are not reliable in that environment due to insufficient surveillance data quality. Surveillance data from ADS-­‐B , however, has much higher resolution. Therefore, ADS-­‐B based traffic alerting systems are expected to be capable of providing reliable alerting in such environments and would thus pose a significant incentive for GA to equip with ADS-­‐B. An analysis of the current availability of low altitude surveillance over the continental United States was conducted in order to identify where ADS-­‐B Low Altitude Surveillance would be beneficial. Providing low altitude surveillance has the potential to improve efficiency during IFR conditions. 27 towered airports with RADAR floors of more than 500ft have been identified. ADS-­‐B surveillance in those locations would create a significant benefit locally. Non-­‐towered airports without low altitude surveillance are more common (806 total). ADS-­‐B surveillance to such airports has the potential to increase airport acceptance rates in Instrument Flight weather and thus providing benefit to GA. However, in addition to providing surveillance, additional ATC procedures need to be developed to take advantage of such ADS-­‐B surveillance. The new procedures would allow ATC to remain in radio communication with aircraft operating at non-­‐towered airports, preventing the application of inefficient procedural control.FAA’s Surveillance and Broadcast Services Program Office under contracts DTFA01-­‐01-­‐C-­‐00030 and DTFAWA-­‐10-­‐F-­‐0008

Mantle flow beneath La Réunion hotspot track from SKS splitting

International audienceIf upper mantle anisotropy beneath fast-moving oceanic plates is expected to align the fast azimuths close to the plate motion directions, the upper mantle flow pattern beneath slow-moving oceanic plates will reflect the relative motion between the moving plate and the underlying large-scale convecting mantle. In addition to the non-correlation of the fast azimuths with the plate motion direction, the flow and anisotropy pattern may be locally perturbed by other factors such as the upwelling and the sublithospheric spreading of mantle plumes. Investigating such plume–lithosphere interaction is strongly dependent on the available seismological data, which are generally sparse in oceanic environment. In this study, we take the opportunity of recent temporary deployments of 15 seismic stations and 5 permanent stations on the Piton de la Fournaise volcano, the active locus of La Ré union hotspot and of 6 permanent stations installed along or close to its fossil track of about 3700 km in length, to analyze azimuthal anisotropy detected by SKS wave splitting and to decipher the various possible origins of anisotropy beneath the Western Indian Ocean. From about 150 good and fair splitting measurements and more than 1000 null splitting measurements, we attempt to distinguish between the influence of a local plume signature and large-scale mantle flow. The large-scale anisotropy pattern obtained at the SW-Indian Ocean island stations is well explained by plate motion relative to the deep mantle circulation. By contrast, stations on La Ré union Island show a complex signature characterized by numerous ''nulls'' and by fast split shear wave polarizations trending normal to the plate motion direction and obtained within a small backazimuthal window, that cannot be explained by either a single or two anisotropic layers. Despite the sparse spatial coverage which precludes a unique answer, we show that such pattern may be compatible with a simple model of sublithospheric spreading of La Ré union plume characterized by a conduit located at 100–200 km north of La Ré union Island. Anisotropy beneath the new GEOSCOPE station in Rodrigues Island does not appear to be influenced by La Ré union plume-spreading signature but is fully compatible with either a model of large-scale deep mantle convection pattern and/or with a channeled asthenospheric flow beneath the Rodrigues ridge.

Clock spectroscopy of interacting bosons in deep optical lattices

We report on high-resolution optical spectroscopy of interacting bosonic $^{174}$Yb atoms in deep optical lattices with negligible tunneling. We prepare Mott insulator phases with singly- and doubly-occupied isolated sites and probe the atoms using an ultra-narrow "clock" transition. Atoms in singly-occupied sites undergo long-lived Rabi oscillations. Atoms in doubly-occupied sites are strongly affected by interatomic interactions, and we measure their inelastic decay rates and energy shifts. We deduce from these measurements all relevant collisional parameters involving both clock states, in particular the intra- and inter-state scattering lengths