Model, software and database for line-mixing effects in the ν3 and ν4 bands of CH4 and tests using laboratory and planetary measurements—II: H2 (and He) broadening and the atmospheres of Jupiter and Saturn

The absorption shapes of the ν₂, ν₃ and ν₄ infrared bands of CH₄ perturbed by H₂ in large ranges of pressure and temperature have been measured in the laboratory. In order to model these spectra, the theoretical approach accounting for line-mixing effects proposed for CH₄-N₂ and CH₄-air and successfully tested in the companion paper (I), is used. As before, state-to-state rotational rates are used together with some empirical parameters that are deduced from a fit of a single room temperature spectrum of the ν₃ band at about 50 atm. The comparisons between measured and calculated spectra in the ν₃ and ν₄ regions under a vast variety of conditions (9-300 atm, 80-300 K) then demonstrate the quality and consistency of the proposed model. In the case of the ν₂ band, which is of E symmetry, specific parameters, different from those adapted to the ν₃ and ν₄ transitions of F₂ symmetry, are used for proper modeling of the spectral shape. Furthermore, as shown previously, a broad absorption feature grows underneath the ν₂ band with increasing H₂ density. The latter, for which an empirical model is proposed, is attributed to a collision-induced absorption (CIA) process in methane. From the developed models, a database and associated software are built for the updating of planetary atmospheres radiative transfer codes. The quality of these tools is then further demonstrated using emission measurements of the Jovian and Saturnian atmospheres in the ν₄ region (7-10 μm) recorded by the Short Wave Spectrometer of the Infrared Space Observatory and the Composite Infrared Spectrometer on-board Cassini. Comparisons between measured radiances and predictions confirm the failure of the purely Lorentzian approach and the quality of the proposed line-mixing model. Furthermore, it is shown that the methane CIA contribution has a significant influence on the planetary emission beyond 1400 cm⁻¹.     

Hydrogen/deuterium-mixtures as a laboratory for the study of the muonic cascade and muon-catalyzed fusion

We have performed an experiment to investigate various processes induced by muons in hydrogen-deuterium mixtures. Preliminary results are given for cascade X-ray yields, q_1s, relative yields of conversion muons and fusion γ-rays, molecular formation and hyperfine transition rates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Magnetic particle detection by frequency mixing for immunoassay applications

For magnetic immunoassay applications, a novel magnetic reader for quantification of magnetic particle concentrations has been developed. Upon magnetic excitation at two distinct frequencies incident on the sample, the response signal generated at a sum frequency is detected. The low-frequency field component periodically drives the magnetic particles into saturation, which is probed by the high-frequency field. The appearance of frequency mixing lines is highly specific to the nonlinearity of the superparamagnetic particles’ magnetization. The optimization of field coils, differential pickup coil, preamplifier, demodulators and filters are discussed. The output signal is linear for four orders of magnitude in iron concentration.     

Interpolation and harmonic majorants in big Hardy-Orlicz spaces

Free interpolation in Hardy spaces is characterized by the well-known Carleson condition. The result extends to Hardy-Orlicz spaces contained in the scale of classical Hardy spaces H ^p, p > 0. For the Smirnov and the Nevanlinna classes, interpolating sequences have been characterized in a recent paper in terms of the existence of harmonic majorants (quasi-bounded in the case of the Smirnov class). Since the Smirnov class can be regarded as the union over all Hardy-Orlicz spaces associated with a so-called strongly convex function, it is natural to ask how the condition changes from the Carleson condition in classical Hardy spaces to harmonic majorants in the Smirnov class. The aim of this paper is to narrow down this gap from the Smirnov class to “big” Hardy-Orlicz spaces. More precisely, we characterize interpolating sequences for a class of Hardy-Orlicz spaces that carry an algebraic structure and are strictly bigger than ⋃ _p>0 H ^p . It turns out that the interpolating sequences are again characterized by the existence of quasi-bounded majorants, but now the functions defining these quasi-bounded majorants have to be in suitable Orlicz spaces. The existence of harmonic majorants defined by functions in such Orlicz spaces is also discussed in the general situation. We finish the paper with a class of examples of separated Blaschke sequences which are interpolating for certain Hardy-Orlicz spaces without being interpolating for slightly smaller ones.     

Ferromagnetic erbium studied by μSR

The ferromagnetic cone phase of erbium has been studied with μSR. Two precessing muon signals were observed with nearly equal intensities at T\approx15\ K. At lower temperatures, one of the signals is gradually reduced and disappeared below 5 K. The two observed muon frequencies and their depolarisation behaviour show that the magnetic structure deduced from neutron and X‐ray scattering must be modified and that a “squaring up” of the structure is likely to occur as the temperature is lowered. This revised version was published online in July 2006 with corrections to the Cover Date.     

Und dann und wann ein Leitprogramm!

And now and then a leading programme. At ETH Zürich a relatively large project was recently devoted to the constructive of what is called “Leitprogramm” (leading programme). In this article we provide some information on the leading programme method and its theoretical background. Moreover we describe in some detail the four leading programmes which relate to mathematics and which are constructed for use at the gymnasium in the course of the project.     

New precision measurements of dµd fusion

A new experiment was started at PSI aiming for high-precision and complete studies of dµd fusion in D₂, HD and D₂/H₂ gas mixtures. A high-pressure ionization chamber surrounded by a set of neutron counters is used to observe dd-fusion at temperatures between 25 and 350 K. Here we report preliminary results from the first test run with pure D₂ filling.