A quartz amplifier for high-sensitivity Fourier-transform ion-cyclotron-resonance measurements with trapped ions.

Single-ion sensitivity is obtained in precision Penning-trap experiments devoted to light (anti)particles or ions with low mass-to-charge ratios, by adding an inductance coil to an amplifier connected to the trap, both operated at 4 K. However, single-ion sensitivity has not been reached on heavy singly or doubly charged ions. In this publication, we present a new system to reach this point, based on the use of a quartz crystal as an inductance, together with a newly developed broad-band (BB) amplifier. We detect the reduced-cyclotron frequency of 40Ca+ ions stored in a 7-tesla open-ring Penning trap. By comparing the detected electric signal obtained with the BB amplifier and the fluorescence signal obtained by collecting the photons emitted by a trapped ion cloud, we show a detection limit below 110 ions. Adding the crystal, the electrical signal increases by a factor of about 30 at room temperature, which combined with the measured equivalent resistance and voltage noise, proves the feasibility of the system to reach single-ion sensitivity at 4 K.

Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion.

A special ion trap was initially built up to perform ß-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single (40)Ca(+) ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on (40)Ca(+) ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

[Evaluation of compliance with antituberculous chemoprophylaxis among recluse population of the Jaen penitentiary center]. / Valoración del cumplimiento de la quimioprofilaxis antituberculosa por la población reclusa del centro penintenciario de Jaén.

BACKGROUND: This study highlights the importance of antitubercular chemoprophylaxis with isoniazid to control and prevent tuberculosis in prisons. The relationship between compliance with the chemoprophylaxis and study factors was evaluated and we examined whether health education given in our prison motivated the prisoners to comply with this treatment. METHODS: Compliance with chemoprophylaxis using isoniazid by 52 inmates of the Jaén Penal Institution was studied for the period February to May 1995. The dose of isoniazid taken was calculated by means of the spectrophotometric determination of isoniazid metabolites in urine using the Eidus Hamilton method. Likewise, the influence of variables such as sex, HIV infection, legal situation and cultural level on compliance was studied. RESULTS: Out of 52 inmates, 23 (44.23%) were taking a daily dose of isoniazid that was considered to be effective and 29 inmates (55.77%) were taking less than the effective isoniazid dose for the chemoprophylaxis. With regard to the variables studied, greater compliance with the chemoprophylaxis was recorded among men (sex variable) and those inmates with a higher educational level (cultural level) although no significant differences were found. CONCLUSIONS: Compliance with the chemoprophylaxis among our inmates is inadequate although it matches similar studies that have been carried out on the prison population. This is not the case for the community population where compliance with chemoprophylaxis is greater. This low compliance forces us to review our current health education programme and to take steps that might increase this degree of compliance such as direct observation of treatment, a system of intermittent treatment, etc.

Improved white noise method in the evaluation of linear hearing-aids characteristics.

In this paper an alternative method of determining the standardized electroacoustical parameters for hearing aids is discussed. This is done by using white noise as the input stimulus and a high resolution algorithm, Burg's method, to obtain the spectral estimation of the frequency response. Three types of hearing-aid are analyzed according to both the pure tonal and white noise method and their standardized computed electroacoustical characteristics are compared. The results show deep differences at the low frequency range and a close match at high frequencies (HFA-ref. test and SSPL-90 dBSPL).