The natural outcome of theoretical calculations of microwave background anisotropy is the angular power spectrum Cl as a function of multipole number l. Experimental Cl’s are needed for direct comparison. Estimation procedures using statistics linear in the pixel amplitudes as well as the conventional but less useful quadratic combinations are described. For most current experiments, a single b...

We briefly review the main features in the broad-band colour evolution of star clusters, over the complete age interval from 10 to 10 yr. The emphasis is in the problem of age-dating distant young clusters (∼< 2 Gyr) from their integrated colours. It is shown that U−B and B−V are less sensitive to metallicity than colours involving red passbands, like V −I, at least up to ages of some few Gyr. ...

Helix travelling-wave tubes (TWTs) are extensively employed as final power amplifiers in satellites. These applications demand low spectral noise and high efficiency across a broad band. Research has been carried out to achieve these criteria in a helix TWT design. A deeper understanding has been gained on how the basic parameters of a TWT affect its non-linear performance. By selecting and con...

Electroencephalographic and magnetoencephalographic potential generated by active brain reveals widespread coherent oscillations. The oscillations of multiple rhythms overlap in broad spectrum noise. Spectrum analysis of short segments reveals peaks in various frequency ranges. As the duration of segments chosen for analysis increases, the basic form to which spectra converge is the one of Brow...

We present a novel technique to measure high frequency electron spin resonance spectra in a broad frequency range (30-1440 GHz) with high sensitivity. We use a quasioptical setup with tunable frequency sources to induce magnetic resonance transitions. These transitions are detected by measuring the change in the magnetic torque signal by means of cantilever torque magnetometry. The setup allows...

In a self-organizing system, behavior emerges at the large scale from the collective interaction of simple rules that apply at the smaller scale. The behavior that emerges is not directly apparent from inspection of the local rules or processes operating at the lower level. Few problems in engineering have been addressed with the specific idea of designing simple rules that operate in an isolat...

The provision of broad-band services based on either the Internet or the asynchronous transfer mode (ATM) technique requires a new generation of access networks. In the short term, solutions such as x-digital subscriber line (DSL) and hybrid fiber coaxial (HFC), allowing the reuse of existing infrastructures, look very promising. For the longer term, new infrastructures based either on radio or...