The Use of Carousel Interferometer in Fourier-Transform Ultraviolet Spectroscopy

The carousel interferometer is a new type of an interferometer, which has been invented at the University of Turku. It consists of a beamsplitter and five plane mirrors. Four of the mirrors are mounted on a carousel, which rotates back and forth. We have modified the interferometer for use in the Fourier-transform ultraviolet (FT-UV) spectroscopy. Test measurement with plasma radiation gives favourable results. The most important property, which makes the carousel interferometer suitable for UV measurements, is its good stability in modulation.Presented at 1996 International Workshop on Interferometry (IWI ‘96), August 27–29, Saitama, Japan.     

Odd-isotope enrichment studies of Gd by double resonance laser-ionization for the production of burnable nuclear reactor poison

 Because of its large neutron capture cross-section, gadolinium (Gd) is widely used as burnable poison in nuclear reactors. Only two of its naturally occurring seven isotopes are strong neutron absorbers; hence, it would be desirable to enrich Gd in those isotopes. We demonstrate experimentally that significant enrichment can be achieved by two-step laser-ionization by relatively broad-band (bandwidth 1–2 GHz) lasers and by utilizing the isotope shifts only. Our results indicate that the content of the strong absorbers can be raised from the natural 30% to nearly 70%. We also compare the performance of this partially enriched Gd to natural Gd and to pure ¹⁵⁷Gd, the most strongly absorbing isotope, as burnable poison. Received: 3 April 1996/Revised version: 14 October 1996     

Synthèse du mèthyl-1 diformyl-2,3 pyrrole,de la méthyl-1 pyrrolo[2,3-d] pyridazine et de la méthyl-1 oxo-6 (6h)cycloheptatrieno[b] pyrrole

This communication describes the synthesis of l-methyl-2,3-diformylpyrrole. This new compound is used to prepare a new heterocycle, l-methylcyclohepta[b]pyrrol-6-one and thus allows a new synthesis of l-methylpyrrolo[2,3-d]pyridazine.     

Synthèse des pyrido[2,3-d] el [3,2-d] -s-triazolo[3,4-f] pyrimidines el de (pyrazolyl-1')-4 pyrido[2,3-d] et [3,2-d] pyrimidines

The synthesis of two new heterocycles is described: pyrido-[2,3-d]-.s-triazolo[ 3,4-f] pyrimidine and pyrido[3,2-d]-.s-triayzolo-[3,4-f] pyrimidine. 4-[I'-Pyrazolyl]pyrido[2,3-d]pyrimidines and 4-[1′-pyrazoly1] pyrido[ 3,2-d] pyrimidine are obtained by the action of 4-hydrazinopyrido[2,3-d]pyrimidine and 4-hydrazinopyrido-[3,2-d]pyrimidine with several β-diketones.     

The developmental pattern of stimulus and response interference in a color-object Stroop task: an ERP study

Background

Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.

Results

There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.

Conclusion

Although processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults.     

Effects of external noise on the circle map and the transition to chaos in Josephson junctions

We investigate the effects of external current noise on a microwave-driven Josephson junction. We show that the circle return map for the superconducting phase difference is stable with respect to the external noise and find that the effects of fluctuations on the route to chaos described with the circle map can be opposite to those for the Feigenbaum period-doubling cascade: increasing noise can here act as a control parameter triggering a periodically oscillating junction chaotic by generating an inflection point in the return (circle) map. This may prove important also for other physical systems, including charge density waves.     

Synthèse dc la pyrido[2,3-f] phtalazine et des diformyl-6,7; -4,6; -4,7; -2,4 quinoleines

This article describes the synthesis of a new heterocycle, pyrido[2,3,f]phtalazine and three new diformylquinolincs.     

Absorber-induced features in the ac response of a He-Ne laser

The theoretically predicted pronounced ac-response of the laser intensity to the excitation current modulation of an intracavity saturable absorber has been experimentally verified in a He-Ne laser with a Ne-absorber. Good qualitative agreement with the theory is obtained.     

Optimal multiqubit operations for Josephson charge qubits

We introduce a method for finding the required control parameters for a quantum computer that yields the desired quantum algorithm without invoking elementary gates. We concentrate on the Josephson charge-qubit model, but the scenario is readily extended to other physical realizations. Our strategy is to numerically find any desired double- or triple-qubit gate. The motivation is the need to significantly accelerate quantum algorithms in order to fight decoherence.