Demonstration of an erbium-doped fiber with annular doping for low gain compression in cladding-pumped amplifiers.

We present the design and characterization of a cladding-pumped amplifier with erbium doping located in an annular region near the core. This erbium-doped fiber is proposed to reduce gain saturation, leading to smaller gain compression when compared to uniform core doping. Through numerical simulations, we first compare the performance of three fibers with different erbium doping profiles in the core or the cladding. When the doped fibers are operated at the optimum length, results show that the smaller overlap of the signal mode field with the annular erbium doping region leads to higher gain and lower saturation of the amplifier. A single-core erbium-doped fiber with an annular doping and a D-shaped cladding was fabricated. Measurements demonstrate less than 4 dB of gain compression over the C-band for input power ranging from -40 dBm to 3 dBm. Small gain compression EDFAs are of interest for applications that require input channel reconfiguration. Higher gain and saturation output power are also key issues in cladding-pumped multi-core amplifiers.

Mode-multiplexed transmission over conventional graded-index multimode fibers.

We present experimental results for combined mode-multiplexed and wavelength multiplexed transmission over conventional graded-index multimode fibers. We use mode-selective photonic lanterns as mode couplers to precisely excite a subset of the modes of the multimode fiber and additionally to compensate for the differential group delay between the excited modes. Spatial mode filters are added to suppress undesired higher order modes. We transmit 30-Gbaud QPSK signals over 60 WDM channels, 3 spatial modes, and 2 polarizations, reaching a distance of 310 km based on a 44.3 km long span. We also report about transmission experiments over 6 spatial modes for a 17-km single-span experiment. The results indicate that multimode fibers support scalable mode-division multiplexing approaches, where modes can be added over time if desired. Also the results indicate that mode-multiplexed transmission distance over 300 km are possible in conventional multimode fibers.

Wavelength-selective switch with direct few mode fiber integration.

The first realization of a wavelength-selective switch (WSS) with direct integration of few mode fibers (FMF) is fully described. The free-space optics FMF-WSS dynamically steers spectral information-bearing beams containing three spatial modes from an input port to one of nine output ports using a phase spatial light modulator. Sources of mode dependent losses (MDL) are identified, analytically analyzed and experimentally confirmed on account of different modal sensitivities to fiber coupling in imperfect imaging and at spectral channel edges due to mode clipping. These performance impacting effects can be reduced by adhering to provided design guidelines, which scale in support of higher spatial mode counts. The effect on data transmission of cascaded passband filtering and MDL build-up is experimentally investigated in detail.

Multi-channel nonlinearity compensation of PDM-QPSK signals in dispersion-managed transmission using dispersion-folded digital backward propagation.

We demonstrate nonlinearity compensation of 37.5-GHz-spaced 128-Gb/s PDM-QPSK signals using dispersion-folded digital-backward-propagation and a spectrally-sliced receiver that simultaneously receives three WDM signals, showing mitigation of intra-channel and inter-channel nonlinear effects in a 2560-km dispersion-managed TWRS-fiber link. Intra-channel and adjacent inter-channel nonlinear compensation gains when WDM channels are fully populated in the C-band are estimated based on the GN-model.

High-fidelity line-by-line optical waveform generation and complete characterization using FROG.

A stable optical frequency comb with 20-GHz spacing is shaped by a compact integrated silica arrayed waveguide grating (AWG) pair to produce optical waveforms with unprecedented fidelity. Complete characterization of both the intensity and phase of the crafted optical fields is accomplished with cross-correlation frequency resolved optical gating (XFROG) which has been optimized for periodic waveforms with resolvable modes. A new method is proposed to quantify, in a single number, the quality of the match in both the amplitude and phase between the measured optical waveform and the target waveform.

Diabetes Screening in Canada (DIASCAN) Study: prevalence of undiagnosed diabetes and glucose intolerance in family physician offices.

OBJECTIVE: To assess the prevalence of undiagnosed diabetes and glucose intolerance in individuals > or =40 years of age who contacted their family physician for routine care. RESEARCH DESIGN AND METHODS: The study used a stratified randomized selection of family physicians across Canada that was proportional to provincial and urban/rural populations based on Statistics Canada Census data (1996). Consecutive patients > or =40 years of age were screened for diabetes. If a casual fingerprick blood glucose was >5.5 mmol/l, the patient returned for a fasting venous blood glucose test. If the fasting blood glucose was 6.1-6.9 mmol/l, a 2-h 75-g post-glucose load venous blood glucose was obtained. Results of these tests were used to classify patients in diagnostic categories. RESULTS: Data were available for 9,042 patients. Previously undiagnosed diabetes was discovered in 2.2% of the patients, and new glucose intolerance was found in an additional 3.5% of patients. Overall, 16.4% of patients had previously known diabetes. The decrease in fasting plasma glucose criterion from 7.8 to 7.0 mmol/l resulted in a 2.2% versus a 1.6% prevalence of new diabetes. Several risk factors were reported in a significantly greater proportion of patients with new glucose intolerance and either new and known diabetes compared with the normal glucose tolerance group of patients. CONCLUSIONS: Routine screening for diabetes by family physicians is justified in patients > or =40 years of age, given the finding of previously undiagnosed diabetes in 2.2% of these patients and newly diagnosed glucose intolerance in an additional 3.5% of these patients. Another 16.4% of primary care patients > or =40 years of age have known diabetes. This has important implications regarding health resources and physician education.

The VF-14 index of functional visual impairment in candidates for a corneal graft.

PURPOSE: To validate the Visual Function-14 (VF-14) index of functional visual impairment in candidates for a corneal graft. METHODS: One hundred thirty-four patients who were candidates for a corneal graft participated in this study between August 1996 and February 1997. Demographic, ocular history, best-corrected visual acuity, and detailed ocular examination data were collected. Functional visual impairment information was obtained by telephone interviews using the following: VF-14, SF-36 (Short Form-36, a more generic measure of general health function), and Visual Symptom Score, and four questions measuring the overall amount of trouble with vision, dissatisfaction with vision, ocular pain, and discomfort. RESULTS: The average age of corneal graft candidates was 64 +/- 18 years (range, 18 to 90 years) and 60% were women. The most frequent corneal disease was pseudophakic bullous keratopathy (41%). Ocular comorbidities included glaucoma or ocular hypertension (30%) and cataract (19%). The mean best-corrected visual acuity of the eye scheduled for surgery was 1.33 +/- 0.56 logMAR whereas the best eye best-corrected visual acuity was 0.36 +/- 0.44 logMAR. The mean VF-14 score was 73% +/- 26%, and the internal consistency was high, with a Cronbach alpha value of 0.94. The VF-14 correlated strongly with the best eye best-corrected visual acuity. It also correlated strongly with the Visual Symptom Score, the global measures of trouble and dissatisfaction with vision. Candidates for a corneal graft had low scores for all eight general health concepts evaluated with the SF-36, and the VF-14 correlated with seven of the eight SF-36 subscales. CONCLUSION: The VF-14 is a valid measure of functional visual impairment in candidates for a corneal graft. The Visual Symptom Score and the SF-36 are also useful indices in such patients.

Contrast and glare testing in the assessment of visual performance of candidate eyes for penetrating keratoplasty.

PURPOSE: To determine whether visual acuity (VA) measurements performed at low levels of contrast and glare are a better diagnostic tool for determining whether corneal clouding warrants surgery. METHODS: Fifty-nine subjects were recruited from among the candidates for corneal graft. Monocular VA was measured with three Regan contrast VA charts: 96, 25, and 11%, with and without glare provided by the Brightness Acuity Tester (BAT). The discriminative ability of the tests was estimated using the area (AR) under receiver operating characteristic (ROC) curves. Associations between the different VA tests and the Visual Function Index (VF-14) score were studied, using Spearman coefficients. RESULTS: When comparing candidate eyes with contralateral eyes with corneal disease, lower contrasts VA tests provided greater discriminative power. VA measurements made with glare also tended to provide greater discrimination. In fact, discrimination was best with 11% contrast VA with glare, but "testability" was poor. The most practical test in a clinical setting, which retained high discriminative ability (0.798), was the 25% contrast VA with glare. The eye with the best VA correlated strongly with the VF-14, especially at 25% contrast without glare, resulting in an Rs of -0.729. CONCLUSION: Twenty-five percent contrast VA with BAT could help the practitioner to decide whether a corneal transplant is warranted when symptoms of reduced vision are more important than what high-contrast VA might indicate.

Anaesthetic management of caesarean section in a parturient with acute myelodysplastic syndrome.

A 34-year-old pregnant woman developed a myelodysplastic syndrome during pregnancy which resulted in a refractory anaemia and an extreme thrombocytopenia. The report describes the anaesthetic management of elective caesarean section and successful childbirth in this patient. Following replacement therapy with packed red cells and platelets, general anaesthesia was used for the procedure.

[Elsewhere and otherwise.]. / Ailleurs et autrement.

The network of mental health services is constantly in movement. From a relatively simple model it has become a complex service with a multiple ideology, its results are indetermined and have now to be revised. While commenting on the elaboration of a politic in mental health, the authors describe an experience where the mental health services in a Montreal region were diversified and reorganised in sub-regions. They then give an idea of the situation, the arms hoped for, the organisational mode, and the sub-regions; the main problems encountered are identified as well as the stakes and the areas of action. They uncover the particularities and the different realities that are the mainstay of the Greater Montreal.

BAHA implant: implantation technique and complications.

OBJECTIVES: BAHA implants have been shown to be effective in certain forms of conductive hearing loss, but the presence of the titanium abutment is responsible for sometimes severe skin reactions. The objective of this study was to compare two operative techniques: skin flap, and full-thickness skin graft. MATERIAL AND METHODS: Between January 2004 and January 2011, 72 patients were treated by BAHA implant and 32 of these patients (total of 41 implants) were included in the study. Two surgical techniques were used: full-thickness skin graft (n=21) and skin flap (n=20). RESULTS: Four types of skin complications were observed: necrosis, inflammation/infection, hypertrophic scar, and fixture loss due to inadequate osseointegration. Complications requiring surgical revision were observed in 20% of cases with the skin flap method and 38% of cases with the skin graft technique, with no significant difference between the two groups (P=0.31). CONCLUSION: The skin graft technique appears to be associated with a higher rate of major complications. The most common complication is hypertrophic scar. The apparently high complication rate in this series can be explained by a selection bias (exclusion of a large number of complication-free patients).

A case of spontaneous intracranial hypotension: from Ménière-like syndrome to cerebral involvement.

INTRODUCTION: Spontaneous intracranial hypotension (SIH) is a rare pathology caused by unexplained and variably localized leakage of cerebrospinal fluid (CSF). The prime symptom is orthostatic headache, although other less specific clinical signs may predominate, and mislead diagnosis. CASE REPORT: A 47-year-old man presented with Ménière-like symptoms of sudden onset. Secondary orthostatic headache led to the performance of cerebral MRI, which found signs suggestive of intracranial hypotension. A blood-patch was immediately carried out, and was followed by consciousness disorder associated with onset of bilateral subdural hematoma, which required iterative neurosurgical drainage. Myelo-CT confirmed CSF leakage facing the right 12th dorsal nerve root sheath. Radio-guided sealing with biologic glue provided complete regression of all symptoms. DISCUSSION/CONCLUSION: Auditory signs may predominate in the clinical presentation of SIH. Their orthostatic character is suggestive. The present case is of a rare severe form. The role of neurosurgery in such cases remains to be defined.

Rapid updating of optical arbitrary waveforms via time-domain multiplexing.

We demonstrate high-fidelity optical arbitrary waveform generation with 5 GHz waveform switching via time-domain multiplexing. Compact, integrated waveform shapers based on silica arrayed-waveguide grating pairs with 10 GHz channel spacing are used to shape (line-by-line) two different waveforms from the output of a 10-mode x 10 GHz optical frequency comb generator. Characterization of the time multiplexer's complex transfer function (amplitude and phase) by frequency-resolved optical gating permits compensation of its impact on the switched waveforms and matching of the measured and target waveforms to better than G'=5%.

32 Phase X 32 amplitude optical arbitrary waveform generation.

We describe the precise shaping and mode-resolved amplitude and phase characterization of optical arbitrary waveforms by using a 20 GHz optical frequency comb and integrated 64 x 20 GHz channel arrayed waveguide grating pair. Complex waveforms with large variations in phase and amplitude between adjacent modes were generated and characterized.

Advocacy in the mental health services field.

UNLABELLED: Advocacy in the mental health services field is gaining importance since the traditional role of mental health hospitals is changing, particularly in North America and in Western Europe. This review will define advocacy, its goals and fundamental principles. It will then delineate the skills and strategies needed for any intervention on behalf of a patient or a group of patients. It will also deal with the issues and approaches most frequently raised and used, and finally, with the limits of advocacy. METHOD: The method used for this review was mainly a recension of the literature concerning advocacy throughout North America and Europe, having in view to see emerging the principal stakes and concerns related to this process. RESULTS: Advocacy has a significant impact on patients' awareness of their rights and their capacity to exercise them. It also prevents potential abuse of patients. On the other hand, some patients have an increased opportunity to cease treatment, and this could lead to serious medical consequences. There is also the possibility of retaliation from staff, as a result of being involved with an advocate. The combination of high quality care and effective advocacy is the best guarantee that a mental health patient will get the care he wants and needs with human dignity.

Effects of vitamin D on calcium regulation in vitamin-D-deficient pigs given a phytate-phosphorus diet.

1. Vitamin-D-deficient pigs were fed on a phytate-phosphorus diet and treated with vitamin D3 (+D) to examine the time-course of adaptative changes in plasma minerals, vitamin D metabolites, parathyroid hormone (PTH) and calcium balance and intestinal Ca-binding protein (CaBP). 2. The 5-week vitamin D repletion (25 micrograms cholecalciferol/kg diet) regimen restored plasma Ca, P and alkaline phosphatase (EC 3.1.3.1) to normal, decreased PTH and markedly and rapidly increased plasma 25-hydroxycholecalciferol (25-OHD, sevenfold after 4 d) and 1,25-dihydroxycholecalciferol (1, 25(OH)2D3, 1.8-fold after 4 d). 3. CaBP concentrations were markedly elevated all along the digestive tract, especially in the distal regions. 4. Ca absorption and retention were enhanced (fourfold and sixfold respectively) by the +D diet. 5. The improved Ca absorption, coupled with increased CaBP and 1,25(OH)2D3 levels, suggest that vitamin D metabolism in phytate-P-fed pigs is sensitive to the depressed Ca availability due to phytate feeding. It also indicates that CaBP may play an important role in the adaptation of Ca absorption. 6. Persistent hypercalciuria indicates that mineral metabolism was still affected by the phytate nature of the dietary P in spite of the vitamin D treatment.

Importance of cereal phytase activity for phytate phosphorus utilization by growing pigs fed diets containing triticale or corn.

In contrast to corn, wheat and triticale exhibit high phytase activities. This enzyme enhances phytic phosphorus availability, as demonstrated in pigs given wheat diets. To study the utilization of triticale phosphorus in pigs, the importance of dietary phytase content and the mineral and bone disorders related to high phytate feeding, a nutritional experiment was carried out in 12 growing pigs fed either a corn- or a triticale-based diet for 6 wk. The diets were almost identical except for the cereal component; their phosphorus contents were low (0.4%) and mainly phytic. The following parameters were measured: calcium and phosphorus balances, bone and plasma contents of calcium and phosphorus, plasma vitamin D metabolites and parathyroid hormone (PTH), bone bending moments and intestinal phosphatase activities. Both diets provoked a phosphorus deficiency, but hypophosphatemia occurred less rapidly, hypercalciuria and hypophosphaturia were less marked and phosphorus availability was greater when the triticale diet was fed. This was attributed to the high phytase content of triticale because intestinal phytase and alkaline phosphatase activities were similar in pigs fed either diet. Calcium absorption was not modified by calcium retention was greater for pigs fed triticale and led to higher bone scores. In conclusion, the higher the phytase activity of the diet, the greater the phytate P availability and the lower the bone-mineral disorders.

Optical performance of aspheric concave ophthalmic lenses: the effect of vertex distance.

Variations of power errors in the periphery of concave aspheric lenses were assessed as a function of vertex distance. Comparisons were made between the performance of different types of spherical lenses and that of aspheric lenses (-6.00 and -8.00 D lenses were used). Off-axis measurements were made by means of a modified focimeter, which enabled rotation of the lens around the center of the vertex sphere. Reduction of the vertex sphere's radius from 27 to 23 mm simulated a 4-mm decrease in vertex distance. Results of the measurements are compared with a computed model. These results indicate that off-axis performance is more affected by a reduction of vertex distance in the case of aspheric lenses compared to spherical lenses. Resulting increases in oblique astigmatism (OA) and mean oblique error (MOE) are at the limit of clinical acceptance. The importance, for the practitioner, of respecting the vertex distance selected for a specific aspheric design when fitting this type of lens is emphasized.

[Selective determination of different types of gastrointestinal mucins:use of histochemical reagents]. / Mise au point d'un dosage sélectif des différents types de mucines gastro-intestinales: utilisation de réactifs histochimiques.

A method, transposed from the mucin histochemical stainings, was proposed to evaluate neutral, acidic and sulphated mucins by spectrocolorimetry. Stainings used were periodic acid/Schiff (PAS), Alcian blue (AB) pH 2.5, and Alcian blue (AB) pH 0.5. Mucin samples were extracted from mucosal scrapings, from intestinal contents of germ-free rats or from commercial pig gastric mucin. A mucin-enriched fraction was obtained and lyophilised and the protein content was determined. Each mucin type was spectrophotometrically analysed after staining and precipitation by slightly modified Carnoy fixative. The histochemical stainings used here, after modification by Carnoy fixative treatment, were, as shown by electrophoretic controls, specific for mucin types contained in these mucins without protein contaminant interference.