Mach shocks induced by partonic jets in expanding quark-gluon plasma

We study Mach shocks generated by fast partonic jets propagating through a deconfined strongly-interacting matter. Our main goal is to take into account different types of collective motion during the formation and evolution of this matter. We predict a significant deformation of Mach shocks in central Au+Au collisions at RHIC and LHC energies as compared to the case of jet propagation in a static medium. The observed broadening of the near-side two-particle correlations in pseudorapidity space is explained by the Bjorken-like longitudinal expansion. Three-particle correlation measurements are proposed for a more detailed study of the Mach shock waves.Comment: 13 pages, 4 figure

Coupling of spin and vibrational degrees of freedom of adsorbates at metal surfaces probed by vibrational sum-frequency generation

Vibrational spectroscopy using sum-frequency generation has been used to investigate the coupling between a ferromagnetic thin film and adsorbed molecules, here CO on Ni/Cu(100). The CO stretching vibration exhibits a strong magnetic contrast with a pronounced temperature dependence, underlining the high sensitivity of this adsorbate-specific spectroscopy method. Our results indicate that the strong temperature dependence is caused by dynamical changes in the surface chemical bond when the CO stretch vibration is coupled to thermally excited external vibrational modes

Generalisation of the Picture Exchange Communication System (PECS) across transfer facilitated and non-facilitated settings.

The purpose of this study was to investigate the extent to which PECS would generalise from the training setting to other familiar settings as a function of properties of the settings. It was predicted that PECS would generalise better to the setting where PECS use facilitated was by having the same communicative partners and items available. Three preschool children all with a diagnosis of Autism Spectrum Disorder (ASD) were trained to use the Picture Exchange Communication System (PECS) to a minimum proficiency level of Phase 3. The experiment employed an ABA single case design with multiple target measures, replicated across participants, acknowledging that observations in the first baseline would be zero. Transfer of PECS across settings varied for each participant. One participant generalised PECS to the facilitated environment more than the non-facilitated environment as predicted. Another participant transferred PECS better to the non-facilitated environment compared to the facilitated environment contrary to the research prediction. The final participant did not generalise PECS to either environment, switching to functional verbal communication instead

Reduction of N₂O on MgO/Ag(100) via UV-Photoinduced Trapped Electrons

The photon-driven substrate-mediated dissociation of N2O on thin MgO films grown on an Ag(100) crystal has been investigated with postirradiation thermal desorption spectroscopy (TDS). After excitation with 248 nm photons, we observe the simultaneous formation of N2 and a high-temperature oxygen species, accompanied by a decrease in the parent N2O signal. On the basis of the generation and depletion of N2 and N2O as a function of the photon dose, we determine cross sections of about 10–18 and 10–19 cm2, respectively, whereas for the concurrent desorption of the N2 photoproduct a cross section of 10–20 cm2 is found. If the desorption of molecular oxygen is completed at 650 K, then the MgO film is virtually restored to its initial reactivity condition. However, only partial removal of the high-temperature oxygen results in the diminished formation of N2 in subsequent reduction cycles, which we explain by blocking the reactive sites through oxygen at annealing temperatures that are not high enough. Our findings can be rationalized in terms of the initial photogeneration of electron–hole pairs that then upon electron trapping lead to reactive sites that cause the dissociation of the parent N2O molecules