Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum-optics in photonic band-gap crystals and for applications wherein directional emission and total emission power are controlled.Comment: 10 pages, 10 figures, corrected pdf, inserted new referenc

Angular redistribution of near-infrared emission from quantum dots in 3D photonic crystals

We study the angle-resolved spontaneous emission of near-infrared light sources in 3D photonic crystals over a wavelength range from 1200 to 1550 nm. To this end PbSe quantum dots are used as light sources inside titania inverse opal photonic crystals. Strong deviations from the Lambertian emission profile are observed. An attenuation of 60 % is observed in the angle dependent radiant flux emitted from the samples due to photonic stop bands. At angles that correspond to the edges of the stop band the emitted flux is increased by up to 34 %. This increase is explained by the redistribution of Bragg-diffracted light over the available escape angles. The results are quantitatively explained by an expanded escape-function model. This model is based on diffusion theory and adapted to photonic crystals using band structure calculations. Our results are the first angular redistributions and escape functions measured at near-infrared, including telecom, wavelengths. In addition, this is the first time for this model to be applied to describe emission from samples that are optically thick for the excitation light and relatively thin for the photoluminesence light.Comment: 24 pages, 8 figures (current format = single column, double spaced

How do patients with systemic sclerosis experience currently provided healthcare and how should we measure its quality?

OBJECTIVES: To gain insight into SSc patients' perspective on quality of care and to survey their preferred quality indicators. METHODS: An online questionnaire about healthcare setting, perceived quality of care (CQ index) and quality indicators, was sent to 2093 patients from 13 Dutch hospitals. RESULTS: Six hundred and fifty patients (mean age 59 years, 75% women, 32% limited cutaneous SSc, 20% diffuse cutaneous SSc) completed the questionnaire. Mean time to diagnosis was 4.3 years (s.d. 6.9) and was longer in women compared with men (4.8 (s.d. 7.3) vs 2.5 (s.d. 5.0) years). Treatment took place in a SSc expert centre for 58%, regional centre for 29% or in both for 39% of patients. Thirteen percent of patients was not aware of whether their hospital was specialized in SSc. The perceived quality of care was rated with a mean score of 3.2 (s.d. 0.5) (range 1.0-4.0). There were no relevant differences between expert and regional centres. The three prioritized process indicators were: good patient-physician interaction (80%), structural multidisciplinary collaboration (46%) and receiving treatment according to SSc guidelines (44%). Absence of disease progression (66%), organ involvement (33%) and digital ulcers (27%) were the three highest rated outcome indicators. CONCLUSION: The perceived quality of care evaluated in our study was fair to good. No differences between expert and regional centres were observed. Our prioritized process and outcome indicators can be added to indicators suggested by SSc experts in earlier studies and can be used to evaluate the quality of care in SSc

Whole exome sequencing coupled with unbiased functional analysis reveals new Hirschsprung disease genes

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