לוח שנה משולב

There is ample evidence that the most significant growth epoch of the majority of super-massive black holes (SMBHs) must have occurred at z>1-2.
I will present our team's efforts to measure black hole masses and accretion rates in several high-redshift samples of AGNs, based on extensive NIR spectroscopic campaigns. I will particularly focus on a large sample of z~5 AGNs, which were observed in a combined VLT-Gemini campaign. This sample probes the most massive BHs at this epoch, but shows lower masses and higher accretion rates than those of z~2-3.5 sources. When combining these samples together, a clear evolutionary sequence is evident: the z~5 BHs grow through Eddington-limited accretion from a broad range of seed masses; their subsequent growth, at duty cycles of ~10-20%, forms the most massive BHs observed at z~2. I will also mention a few follow-up campaigns which aim at understanding the co-evolution of these BHs with their host galaxies.

The (diamagnetic) response of an insulator is usually suppressed by the size of the gap to the lowest excitation. In my talk I'll report about a model with strong spin-orbit interactions where a macroscopic diamagnetic response is induced which is independent of the gap. I discuss the evolution of the response as a function of a tuning parameter which brings the system from a topologically trivial via a strong topological insulator to a weak topological insulator.

With quantum gases, one can explore magnetic ordering and dynamics in regimes inaccessible in solid-state systems. For example, in degenerate spinor Bose gases, magnetization of the atomic spin is established parasitically along with Bose-Einstein condensation, allowing minute spin-dependent energies to dictate the magnetic ordering of the gas. In addition, the extreme isolation of the atomic system allows for systems to created far out of equilibrium, allowing the dynamics of symmetry breaking to probed in real time. A second cold-atom "material," in which atoms are confined within the periodic potential of an optical lattice, bears a stronger resemblance to condensed-matter systems. I will present recent progress to explore the effects of geometric frustration with cold atoms that are confined in a two-dimensional kagome optical lattice.

Any physical device, including computers, when comparing A to B, must send the information to point C. Explanations of brain processing take such a convergence for granted thus generating models relying on increasingly converging hierarchical streams. Such models, however, consistently fail to explain many perceptual phenomena. To see whether the brain, at times, can compare (integrate, process) events that take place at different loci without sending the information to a common target, I performed experiments in three modalities, somato-sensory, auditory, and visual, where 2 different loci at the primary cortex were stimulated. Subjects were able to integrate inputs in time and space affecting small separate cortical loci. The ability to correlate activity between loci was independent of cortical distance up to 2-4 cm. Given the organization of sensory cortex where localized responses in primary cortex do not interact while convergence in downstream areas results in loss of individual stimulus identity and in decreasing selectivity to elementary stimuli, those results cannot be explained by conventional convergence models. We must thus assume a non-converging mechanism whereby two (or more) activated cortical loci can be integrated without sending information via axons into another downstream integrating site. Once we allow for such a non-converging mechanism, many perceptual phenomena can be viewed differently. Object recognition and representation is such a phenomenon that, I suggest, does not result from hierarchical convergence of cells with ever-increasing feature selectivity but rather from parallel interactions between various visual and non-visual areas. If my hypothesis of the brain ability to relate activity taking place at separate loci without using convergence-by-wires is correct, it implies that the brain can use heretofore unconsidered (unknown?) parallel processing and that conventional models, including computer programs, would not be able to capture many brain processes.