Tunable active chirped-corrugation waveguide filters

A novel tunable semiconductor waveguide reflection filter is proposed and analyzed. The filter is based on spatially selective gain pumping of a chirped-corrugation waveguide. This active chirped-corrugation waveguide filter (ACF) is considered for monolithic broadband tuning of semiconductor lasers

Pulse characteristics of passively mode-locked diode lasers

For the first time to our knowledge, asymmetric pulse shapes and the linear and nonlinear chirp from a passively mode-locked semiconductor laser are directly measured. For the laser tuned to various center wavelengths, fall-time-to-rise-time ratios of 2.0 to 2.5 are measured. With the laser tuned to the shorter-wavelength side of its tuning range, a significant quadratic chirp of -60 fs/nm^2 is measured, along with a linear chirp of -800 fs/nm. The nonlinear chirp is responsible for the asymmetrically shaped compressed pulses that produce long-tailed autocorrelations

Supermodes of high-repetition-rate passively mode-locked semiconductor lasers

We present a steady-state analysis of high-repetition-rate passively mode-locked semiconductor lasers. The analysis includes effects of amplitude-to-phase coupling in both gain and absorber sections. A many-mode eigenvalue approach is presented to obtain supermode solutions. Using a nearest-neighbor mode coupling approximation, chirp-free pulse generation and electrically chirp-controlled operation are explained for the first time. The presence of a nonzero alpha parameter is found to change the symmetry of the supermode and significantly reduce the mode-locking range over which the lowest order supermode remains the minimum gain solution. An increase in absorber strength tends to lead to downchirped pulses. The effects of individual laser parameters are considered, and agreement with recent experimental results is discussed

Broad-band wavelength tunable picosecond pulses from CW passively mode-locked two-section multiple quantum-well lasers

Wavelength tunable CW (continuous-wave) passive mode-locking of a two-section quantum-well laser coupled to an external cavity is demonstrated. A tuning range of 26 nm is achieved with typical autocorrelation full widths at half maximum of 4.5 ps

Wavelength tunable source of subpicosecond pulses from CW passively mode-locked two-section multiple-quantum-well laser

A wavelength-tunable passively-mode-locked semiconductor laser source of subpicosecond pulses is demonstrated. The system includes a two-section multiple-quantum-well laser which is coupled to an external grating for tuning and is followed by an external grating pair for pulse compression. A tuning range of 16 nm round 846 nm is obtained, resulting in compressed pulse widths as short as 260 fs and pulse widths shorter than 600 fs for all wavelength values within this tuning range. Time-bandwidth products are one to two times the transform limit

Exploring dementia management attitudes in primary care: a key informant survey to primary care physicians in 25 European countries

Background: Strategies for the involvement of primary care in the management of patients with presumed or diagnosed dementia are heterogeneous across Europe. We wanted to explore attitudes of primary care physicians (PCPs) when managing dementia: (i) the most popular cognitive tests, (ii) who had the right to initiate or continue cholinesterase inhibitor or memantine treatment, and (iii) the relationship between the permissiveness of these rules/guidelines and PCP's approach in the dementia investigations and assessment. Methods: Key informant survey. Setting: Primary care practices across 25 European countries. Subjects: Four hundred forty-five PCPs responded to a self-administered questionnaire. Two-step cluster analysis was performed using characteristics of the informants and the responses to the survey. Main outcome measures: Two by two contingency tables with odds ratios and 95 confidence intervals were used to assess the association between categorical variables. A multinomial logistic regression model was used to assess the association of multiple variables (age class, gender, and perceived prescription rules) with the PCPs' attitude of "trying to establish a diagnosis of dementia on their own". Results: Discrepancies between rules/guidelines and attitudes to dementia management was found in many countries. There was a strong association between the authorization to prescribe dementia drugs and pursuing dementia diagnostic work-up (odds ratio, 3.45; 95 CI 2.28-5.23). Conclusions: Differing regulations about who does what in dementia management seemed to affect PCP's engagement in dementia investigations and assessment. PCPs who were allowed to prescribe dementia drugs also claimed higher engagement in dementia work-up than PCPs who were not allowed to prescribe

Taking charge and letting go: exploring the ways a Transition to Adulthood project for teenagers with Duchenne muscular dystrophy has supported parents to prepare for the future

The new Special Educational Needs and Disability legislation in the Children and Families Act 2014 intends to raise the aspirations of young people with special educational needs and their families, and improve their life outcomes. But what do raised aspirations and better outcomes look like for young people who have a life-limiting impairment? This article draws on data from a parent evaluation of a lottery-funded Transition to Adulthood project for boys with Duchenne muscular dystrophy (DMD), called ‘Takin’ Charge’, focusing in particular on whether or not the project helped parents of boys with DMD prepare for the future. Key themes that emerged were the importance and novelty of older role models with DMD in the project who were able to share their journeys into adulthood, the support between families that the project enabled, the meaning of family resilience and aspirations for a normal life. The use of solution-focused questioning with families affected by a life-limiting impairment is also explored

Unburdening dementia a basic social process grounded theory – based on a primary care physician survey from 25 countries

OBJECTIVE: To explore dementia management from a primary care physician perspective.DESIGN: One-page seven-item multiple choice questionnaire; free text space for every item; final narrative question of a dementia case story. Inductive explorative grounded theory analysis. Derived results in cluster analyses. Appropriateness of dementia drugs assessed by tertiary care specialist.SETTING: Twenty-five European General Practice Research Network member countries.SUBJECTS: Four hundred and forty-five key informant primary care physician respondents of which 106 presented 155 case stories.MAIN OUTCOME MEASURES: Processes and typologies of dementia management. Proportion of case stories with drug treatment and treatment according to guidelines.RESULTS: Unburdening dementia - a basic social process - explained physicians' dementia management according to a grounded theory analysis using both qualitative and quantitative data. Unburdening starts with Recognizing the dementia burden by Burden Identification and Burden Assessment followed by Burden Relief. Drugs to relieve the dementia burden were reported for 130 of 155 patients; acetylcholinesterase inhibitors or memantine treatment in 89 of 155 patients - 60% appropriate according to guidelines and 40% outside of guidelines. More Central and Northern primary care physicians were allowed to prescribe, and more were engaged in dementia management than Eastern and Mediterranean physicians according to cluster analyses. Physicians typically identified and assessed the dementia burden and then tried to relieve it, commonly by drug prescriptions, but also by community health and home help services, mentioned in more than half of the case stories.CONCLUSIONS: Primary care physician dementia management was explained by an Unburdening process with the goal to relieve the dementia burden, mainly by drugs often prescribed outside of guideline indications. Implications: Unique data about dementia management by European primary care physicians to inform appropriate stakeholders. Key points Dementia as a syndrome of cognitive and functional decline and behavioural and psychological symptoms causes a tremendous burden on patients, their families, and society. •We found that a basic social process of Unburdening dementia explained dementia management according to case stories and survey comments from primary care physicians in 25 countries. •First, Burden Recognition by Identification and Assessment and then Burden Relief - often by drugs. •Prescribing physicians repeatedly broadened guideline indications for dementia drugs. The more physicians were allowed to prescribe dementia drugs, the more they were responsible for the dementia work-up. Our study provides unique data about dementia management in European primary care for the benefit of national and international stakeholders