The QUIJOTE (Q-U-I JOint Tenerife) CMB Experiment will operate at the Teide Observatory with the aim of characterizing the polarisation of the CMB and other processes of Galactic and extragalactic emission in the frequency range of 10-40 GHz and at large and medium angular scales. The first of the two QUIJOTE telescopes and the first multi-frequency (10-30 GHz) instrument are already built and have been tested in the laboratory. QUIJOTE-CMB will be a valuable complement at low frequencies for the Planck mission, and will have the required sensitivity to detect a primordial gravitational-wave component if the tensor-to-scalar ratio is larger than r = 0.05.

BACKGROUND Mitral valve repair in rheumatic disease is technically more difficult, and there is little information on the long-term stability of this technique. METHODS AND RESULTS From January 1975 to December 1990, 327 patients underwent mitral valve repair with the Duran flexible ring annuloplasty for rheumatic valve disease. Mean age was 45.4 +/- 12.6 years (range, 23 to 73 years). The techniques used for valve repair include a Duran flexible ring annuloplasty in all cases, commissurotomy in 272 (83.2%), papillary muscle splitting in 171 (52.3%), and subvalvular apparatus repair in 59 patients (18.0%). One hundred one patients required associated tricuspid valve surgery (30.8%). Hospital mortality was 3.36%, being lower for patients with isolated mitral valve repair (2.7%) than those with mitrotricuspid surgery (4.9%). Mean follow-up was 8.6 years (range, 1 to 17 years) and was 96.5% completed. Thirty-four patients required reoperation for severe mitral insufficiency in 12, mitral restenosis in 18, and aortic valve disease in 4. The actuarial curve free from reoperation for mitral cause at 16 years is 89.9 +/- 3.2%. Late mortality occurred in 42 patients (13.2%). Actuarial survival curve at 16 years is 84.0 +/- 3.2% for isolated mitral valve repair and 64.6 +/- 6.7% for mitrotricuspid patients. CONCLUSIONS Mitral valve reconstruction with Duran flexible ring annuloplasty in rheumatic valve disease entails a low hospital mortality with satisfactory long-term clinical results.

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This paper presents the analysis, design, and characterization of the thirty gigahertz instrument receiver developed for the Q-U-I Joint Tenerife experiment. The receiver is aimed to obtain polarization data of the cosmic microwave background radiation from the sky, obtaining the Q, U, and I Stokes parameters of the incoming signal simultaneously. A comprehensive analysis of the theory behind the proposed receiver is presented for a linearly polarized input signal, and the functionality tests have demonstrated adequate results in terms of Stokes parameters, which validate the concept of the receiver based on electronic phase switching.