Planet formation in post-common-envelope binaries

To understand the evolution of planetary systems, it is important to investigate planets in highly evolved stellar systems, and to explore the implications of their observed properties with respect to potential formation scenarios. Observations suggest the presence of giant planets in post-common-envelope binaries (PCEBs). A particularly well-studied system with planetary masses of 1.7 M_J and 7.0 M_J is NN Ser. We show here that a pure first-generation scenario where the planets form before the common envelope (CE) phase and the orbits evolve due to the changes in the gravitational potential is inconsistent with the current data. We propose a second-generation scenario where the planets are formed from the material that is ejected during the CE, which may naturally explain the observed planetary masses. In addition, hybrid scenarios where the planets form before the CE and evolve due to the accretion of the ejected gas appear as a realistic possibility.Comment: 7 pages, 5 figures. Plenary talk given at the 2014 Fall Meeting of the Astronomische Gesellschaft (AG 2014) in Bamberg, submitted for the yearbook series "Reviews in Modern Astronomy", volume 27, of the Astronomische Gesellschaf

The excitation function for Li+HF-->LiF+H at collision energies below 80 meV

We have measured the dependence of the relative integral cross section of the reaction Li+HF-->LiF+H on the collision energy using crossed molecular beams. By varying the intersection angle of the beams from 37{\deg} to 90{\deg} we covered the energy range 25 meV < E_tr < 131 meV. We observe a monotonous rise of the cross section with decreasing energy over the entire energy range indicating that a possible translational energy threshold to the reaction is significantly smaller than 25 meV. The steep rise is quantitatively recovered by a Langevin-type excitation function based on a vanishing threshold and a mean interaction potential energy ~R^-2.5 where R is the distance between the reactants. To date all threshold energies deduced from ab-initio potentials and zero-point vibrational energies are at variance with our results, however, our findings support recent quantum scattering calculations that predict significant product formation at collision energies far below these theoretical thresholds.Comment: 8 pages, 7 figure

Sensory memory for odors is encoded in spontaneous correlated activity between olfactory glomeruli

Sensory memory is a short-lived persistence of a sensory stimulus in the nervous system, such as iconic memory in the visual system. However, little is known about the mechanisms underlying olfactory sensory memory. We have therefore analyzed the effect of odor stimuli on the first odor-processing network in the honeybee brain, the antennal lobe, which corresponds to the vertebrate olfactory bulb. We stained output neurons with a calcium-sensitive dye and measured across-glomerular patterns of spontaneous activity before and after a stimulus. Such a single-odor presentation changed the relative timing of spontaneous activity across glomeruli in accordance with Hebb's theory of learning. Moreover, during the first few minutes after odor presentation, correlations between the spontaneous activity fluctuations suffice to reconstruct the stimulus. As spontaneous activity is ubiquitous in the brain, modifiable fluctuations could provide an ideal substrate for Hebbian reverberations and sensory memory in other neural systems

Refining Industrial Scale Systems in Circus

Circus is a new notation that may be used to specify both data and behaviour aspects of a system, and has an associated refinement calculus. Although a few case studies are already available in the literature, the industrial fire control system presented in this paper is, as far as we know, the largest case study on the Circus refinement strategy. We describe the refinement and present some new laws that were needed. Our case study makes extensive use of mutual recursion; a simplified notation for specifying such systems and proving their refinements is proposed here

Thermal non-equilibrium effects in quantum reflection

We show that the quantum reflection coefficient of ultracold heavy atoms scattering off a dielectric surface can be tuned in a wide range by suitable choice of surface and environment temperatures. This effect results from a temperature dependent long-range repulsive part of the van der Waals-Casimir-Polder-Lifshitz atom-surface interaction potential

Experimental demonstration of composite stimulated Raman adiabatic passage

We experimentally demonstrate composite stimulated Raman adiabatic passage (CSTIRAP), which combines the concepts of composite pulse sequences and adiabatic passage. The technique is applied for population transfer in a rare-earth doped solid. We compare the performance of CSTIRAP with conventional single and repeated STIRAP, either in the resonant or the highly detuned regime. In the latter case, CSTIRAP improves the peak transfer efficiency and robustness, boosting the transfer efficiency substantially compared to repeated STIRAP. We also propose and demonstrate a universal version of CSTIRAP, which shows improved performance compared to the originally proposed composite version. Our findings pave the way towards new STIRAP applications, which require repeated excitation cycles, e.g., for momentum transfer in atom optics, or dynamical decoupling to invert arbitrary superposition states in quantum memories.Comment: 11 pages, 5 figure

Documentation of model components EXPAMOD and CAPRI

Agricultural and Food Policy, Environmental Economics and Policy, Land Economics/Use, Production Economics,