Observation of nonspreading wave packets in an imaginary potential.

We propose and experimentally demonstrate a method to prepare a nonspreading atomic wave packet. Our technique relies on a spatially modulated absorption constantly chiseling away from an initially broad de Broglie wave. The resulting contraction is balanced by dispersion due to Heisenberg's uncertainty principle. This quantum evolution results in the formation of a nonspreading wave packet of Gaussian form with a spatially quadratic phase. Experimentally, we confirm these predictions by observing the evolution of the momentum distribution. Moreover, by employing interferometric techniques, we measure the predicted quadratic phase across the wave packet. Nonspreading wave packets of this kind also exist in two space dimensions and we can control their amplitude and phase using optical elements.

Measurements in the raw gas of a full scale municipal waste incinerator using a wavelength resolved REMPI mass spectrometer.

A resonance enhanced multiphoton ionization (REMPI) mass spectrometer consisting of a tunable laser unit (Nd:YAG pump laser and OPO) and a reflectron mass spectrometer have been upgraded to cope with the difficult conditions such as vibrations, temperature fluctuations and dust, prevailing in an incinerator. On-line measurements of the raw gas have been carried out at the municipal waste incinerator in Stuttgart. Although this test series could not be completed the results are encouraging. They show that wavelength resolution can provide valuable information beyond the one obtainable by fixed frequency REMPI. Examples discussed include separation of interferants to the aniline signal and identification of phenantrene.

[Clomiphene resistant PCO syndrome: IVF treatment as an alternative in failed gonadotropin treatment]. / Clomiphen-resistentes PCO-Syndrom: Die IVF-Behandlung als Alternative bei Versagen der Gonadotropinbehandlung.

34 infertile patients with severe clomiphene-resistant polycystic ovary syndrome were treated with IVF/ET. Stimulation attempts with gonadotropins had resulted in multifollicular ovarian reactions, which did not allow standard ovulation induction using hCG due to the risk of multiple pregnancy. The resulting oocyte retrieval rates (87.4%/treatment cycle), embryo transfer rates (73.3%/oocyte retrieval) and pregnancy rates (24.2%/embryo transfer) approximately corresponded to the rates which are achieved in women with tubal failure using IVF/ET. Since strictly a maximum of 2 embryos was transferred, the occurrence of multiple pregnancies of higher degree could be avoided as opposed to standard gonadotropin therapy. The treatment so far only resulted in singleton pregnancies. The relatively high ovarian hyperstimulation rate (34.4%, primarily WHO stage I-II) could not be unequivocally lowered even by aspiration of all larger follicles.