Thermally resistant waveguides fabricated in Nd:YAG ceramics by crossing femtosecond damage filaments.

We report on femtosecond laser writing of channel waveguides in Nd(3+) ion doped YAG ceramics by multiple inscriptions of damage filaments. Waveguiding between filaments was found to resist annealing temperatures as high as 1500 degrees C. Microluminescence imaging experiments have been carried out to elucidate the potential application of the obtained waveguides as integrated laser sources as well as to elucidate the waveguiding mechanisms.

The effect of the ferroelectric domain walls in the scanning near field optical microscopy response of periodically poled Ba(2)NaNb(5)O(15) and LiNbO(3) crystals.

A study of Ba(2)NaNb(5)O(15) and LiNbO(3) crystals with periodic ferroelectric domain structures using the scanning near field optical microscopy technique is reported. Optical contrast is observed in the regions of ferroelectric domain boundaries and it is analysed using beam propagation method modelling. This reveals that the optical contrast, a consequence of changes in the refractive index, is not due to variation of the waveguide-coupling efficiency, and supports the hypothesis that it is associated with the domain array, which is related to the size of the domain.

field optical and micro-luminescence investigations of femtosecond laser micro-structured Nd:YAG crystals.

We report on the in-depth micro-modifications induced by femtosecond laser ablation in Nd:YAG crystals. Near Field Optical experiments have revealed that, below the ablated volume, a permanent change in the Nd:YAG reflectivity, extending parallel to the irradiation direction, has been induced. Micro-luminescence experiments have provided experimental evidence that these permanent changes in the surface reflectivity are accompanied by strong changes in the luminescence properties of Nd(3+) ions revealing relevant micro structural modifications in the Nd:YAG system.

Alexithymia: a relevant psychological variable in near-fatal asthma.

Alexithymia is a psychological trait characterised by difficulty in perceiving and expressing emotions and body sensations. Failure to perceive dyspnoea could lead alexithymic asthmatics to underestimate the severity of an asthma exacerbation, and thereby increase the risk of developing a fatal or near-fatal asthma (NFA) attack. The objective of the present study was to determine the prevalence of alexithymia in NFA patients and to analyse their clinical characteristics. Alexithymia was assessed using the Toronto Alexithymia Scale in this multicentric prospective observational study. From 33 Spanish hospitals, 179 NFA patients and 40 non-NFA patients, as a control group, were enrolled. There was a higher proportion of alexithymia in the NFA group than in the non-NFA group (36 versus 13%). Patients with NFA and alexithymia were older than the rest of the NFA group, and had a lower level of education, a higher level of psychiatric morbidity, a higher proportion of severe persistent asthma and a greater number of prior very severe asthma exacerbations (49 versus 27%). Alexithymia, severe persistent asthma and a low level of education were identified as independent variables related to repeated very severe asthma exacerbations. The results show that alexithymia is more frequent in near-fatal asthma patients compared to the rest of asthmatics and is associated with recurrent very severe asthma exacerbations.

Comparison of two techniques of sputum induction in the diagnosis of pulmonary tuberculosis.

SETTING: Specialised tuberculosis out-patient clinic covering a population of 350 885. OBJECTIVES: To compare two techniques, ultrasonic nebuliser (UN) and Venturi-type face mask nebuliser (VFMN), for obtaining sputum in patients suspected of having active pulmonary tuberculosis (PTB) and who cannot expectorate, and to analyse the usefulness and cost of sputum induction with UN in a specialised medical practice. DESIGN: Prospective study from October 1997 until March 2000. RESULTS: Of 94 subjects who completed all tests, at least one sample of sputum was obtained from 89 (95.6%). UN provided adequate samples in 86 (93.4%) and VFMN in 66 (71%), a significant difference (P < 0.001). Among 43 patients diagnosed with active PTB, the diagnosis was confirmed in 39 with the samples obtained by sputum induction. Direct acid-fast bacilli smear was positive in 8 (19%). Direct costs were low and the technique can be performed on the day the patient attends the outpatient clinic. CONCLUSION: Sputum induction with an ultrasonic nebuliser was well-tolerated, of low cost, allows adequate samples to be obtained in the majority of patients who cannot produce sputum, and was more effective than the Venturi-type face mask.

Effect of icodextrin peritoneal dialysis solution on cell proliferation in vitro.

Peritoneal dialysis solutions containing icodextrin are ideal for providing sustained ultrafiltration during long dwells, and they have replaced high glucose for long dwells in some patients. The biocompatibility of these solutions, especially in regard to glucose degradation products, has not been studied in depth. The object of this study was to compare the effects of commercially available dextrose-containing dialysis solutions to those of icodextrin-containing solutions on fibroblast proliferation in vitro. We measured the effect of solutions on cell growth by exposing murine fibroblasts to pH-adjusted test solutions mixed with culture medium, and by comparing cell growth to growth in culture medium only. No statistical difference was observed in the growth of cells exposed to heat-sterilized Extraneal [7.5% icodextrin (Baxter Healthcare, Deerfield, Illinois, U.S.A.)], heat-sterilized Dianeal [1.5% dextrose (Baxter Healthcare)], or filter-sterilized Dianeal [4.25% dextrose (Baxter Healthcare]. Also, no difference was observed in the growth of fibroblasts exposed to heat-sterilized Extraneal or to filter-sterilized Extraneal, but heat-sterilized Dianeal [4.25% dextrose (Baxter Healthcare)] caused a significant reduction in cell growth. Glucose degradation products (GDPs) are known to contribute to reduced cell growth in vitro. Extraneal had lower levels of the GDP acetaldehyde compared to Dianeal (2.5% or 4.25% dextrose). The results demonstrate enhanced in vitro biocompatibility characteristics for Extraneal, possibly related to low GDP levels in Extraneal.