Asymmetric induction in simple [2 + 2] photoadditions

Photochemical cycloaddition of cyclopentene with enone esters $\text{1}$ containing different chiral auxiliaries yielded anti and syn adducts $\text{2}$ and $\text{3}$ in good yield and with moderate to high (79%) enantiomeric excesses.     

Transients in all-optical bistability using transverse optical pumping: Observation of critical slowing down

We report on the transient response of an all-optical bistable device to step-inputs of light. The nonlinear mechanism used for bistable switching relies on transverse optical pumping within the Zeeman sublevels of the sodium ground state. Our measurements demonstrate the crucial role of critical slowing down for switching time. We also find that time-dependent diffusion processes can strongly affect the dynamics of this bistable device. Numerical calculations are shown to yield results in satisfactory agreement with experimental data.     

The decay of93g Ru,93m Ru,91g Mo,91m Mo,91g Tc and91m Tc

Decay studies on a number of short-lived odd nuclei in theN=50 region are described. The 59.6-s ⁹³Ru ground state decay was studied in detail for the first time; in these experiments the 10.8-s activity^93m Ru was discovered. The⁹¹Tc activities were also observed for the first time. The ground state and an isomeric state of this nucleus decay with nearby equal half-lives (3.14 and 3.3-min). The activities^91g Mo (16.6-min) and^95m Mo (65.1-s) have been reinvestigated. A number ofγ-rays, previously erroneously assigned to the⁹¹Mo activities, could be eliminated. A strong similarity is noted for the decay schemes of theN=49 isotones^91m Mo and^93m Ru. The energy of the 1/2^? isomeric state in⁹³Ru and theB(M4)-value of the isomeric transition fit well into the systematics of the previously knownN=49 isotones.     

The decay of the Co isomers

The single and coincident γ-ray spectra following the decay of the ⁶²Co isomers were measured. New γ-transitions in the decay of the 13.5 min respectively 1.4 min isomer with energies: 0.7778, 0.8749, 1.1291, 1.7535, 2.3020 and 2.8826 MeV respectively 1.8863, 2.3458, 3.271 and 3.370 MeV have been observed. The intensity of the direct feeding from the 1.4 min isomer to the ground state of ⁶²Ni was determined to be < 0.5 %.     

On stable and uniform rank-2 vector bundles on P2 in characteristic p

The uniform rank-2 vector bundles on Pⁿ are determined and the behaviour of the stable rank-2 vector bundles on P² under restriction to a general line is studied, where Pⁿ denotes the n-dimensional projective space over an algebraically closed field of positive characteristic.