Institut de physique

2011, Saraceno, Clara Jody, Heckl, Oliver Hubert, Baer, Cyrill Roman Emmanuel, Golling, Matthias, Südmeyer, Thomas, Beil, Kolja, Kränkel, Christian, Petermann, Klaus, Huber, Günter, Keller, Ursula

2005, Gouinguene, Sandrine, Pickett, John A, Wadhams, Lester J., Birkett, Michael A, Turlings, Ted

Many parasitic wasps are attracted to volatiles that are released by plants when attacked by potential hosts. The attractiveness of these semiochernicals from damaged plants has been demonstrated in many tritrophic systems, but the physiological mechanisms underlying the insect responses are poorly understood. We recorded the antennal perception by three parasitoids (Cotesia marginiventris, Microplitis rufiventris, and Campoletis sonorensis) to volatiles emitted by maize, cowpea, and cotton plants after attack by the common caterpillar pest Spodoptera littoralis. Gas chromatography-electroantennography (GC-EAG) recordings showed that wasps responded to many, but not all, of the compounds present at the physiologically relevant levels tested. Interestingly, some minor compounds, still unidentified, elicited strong responses from the wasps. These results indicate that wasps are able to detect many odorant compounds released by the plants. It remains to be determined how this information is processed and leads to the specific behavior of the parasitoids.

2013, Sieber, Oliver D, Hoffmann, Martin, Wittwer, Valentin, Mangold, Mario, Golling, Matthias, Tilma, Bauke W, Südmeyer, Thomas, Keller, Ursula

2002, Joyet, Alain, Mileti, Gaetano, Thomann, Pierre, Dudle, G.

We describe a primary fountain frequency standard operating with a continuous beam of laser-cooled Cs atoms. In such a device, aliasing effects, which may degrade the short-term stability in pulsed fountains, are removed and atomic-noise limited stability can be achieved with a state-of-the art, but commercially available, local oscillator. The present experimental short-term stability is measured to be 2.5 · 10-13τ-1/2. Another feature of the continuous fountain is the reduced atomic density and higher beam temperature which reduces the collisional shift of the atomic frequency below the 10-15 level. The light-shift is an undesirable characteristic of the continuous operation. Without a light-trap, a light-shift of the order of 10-12 has been measured. The shift is stable enough not to affect the frequency stability to 104 seconds (2.5 · 10-15). A rotating light-trap has been constructed and tested to bring the light-shift and the corresponding uncertainty to a negligible level. Various contributions to the accuracy are studied.

1993, Meister, Gotz, Stoeckli-Evans, Helen, Süss-Fink, Georg

1994, Meister, Gotz, Rheinwald, Gerd, Stoeckli-Evans, Helen, Süss-Fink, Georg

2004, Innerhofer, Edith, Südmeyer, Thomas, Brunner, Felix, Paschotta, Rüdiger, Keller, Ursula

2008, Südmeyer, Thomas, Imai, Yutaka, Masuda, Hisashi, Eguchi, Naoya, Saito, Masaki, Kubota, Shigeo

2005-7-3, Kazakov, G., Matisov, B., Delporte, J., Mileti, Gaetano

A new method based on optical pumping is proposed for increasing the parameters of dark resonance excitation on D2 line in 87Rb vapor. The pumping is provided by linearly polarized two-frequency laser radiation propagating in the direction perpendicular to the probing field directed along the cell with atomic rubidium vapor. This method significantly improves the dark resonance parameters as compared to the case of pumping by a circularly polarized field. Qualitative considerations are confirmed by the results of numerical calculations.

2010, Thevenet, Damien, Neier, Reinhard, Sereda, Olha, Neels, Antonia, Stoeckli-Evans, Helen

The centrosymmetric title compound, C(18)H(28)I(2)O(2), crystallized in the monoclinic space group P2(1)/c with the alkyl chains having extended all-trans conformations, similar to those in the centrosymmetric bromo analogue [Li et al. (2008 (black right triangle)). Acta Cryst. E64, o1930] that crystallized in the triclinic space group P. The difference between the two structures lies in the orientation of the two alkyl chains with respect to the C(aromatic)-O bond. In the title compound, the O-C(alk-yl)-C(alk-yl)-C(alk-yl) torsion angle is 55.8 (5)°, while in the bromo analogue this angle is -179.1 (2)°. In the title compound, the C-atoms of the alkyl chain are almost coplanar [maximum deviation of 0.052 (5) Å] and this mean plane is inclined to the benzene ring by 50.3 (3)°. In the bromo-analogue, these two mean planes are almost coplanar, making a dihedral angle of 4.1 (2)°. Another difference between the crystal structures of the two compounds is that in the title compound there are no halide(midline ellipsis)halide inter-actions. Instead, symmetry-related mol-ecules are linked via C-H(midline ellipsis)? contacts, forming a two-dimensional network.