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

<i>ATP5PO </i>levels regulate enteric nervous system development in zebrafish, linking Hirschsprung disease to Down Syndrome

Hirschsprung disease (HSCR) is a complex genetic disorder characterized by the absence of enteric nervous system (ENS) in the distal region of the intestine. Down Syndrome (DS) patients have a &gt;50-fold higher risk of developing HSCR than the general population, suggesting that overexpression of human chromosome 21 (Hsa21) genes contribute to HSCR etiology. However, identification of responsible genes remains challenging. Here, we describe a genetic screening of potential candidate genes located on Hsa21, using the zebrafish. Candidate genes were located in the DS-HSCR susceptibility region, expressed in the human intestine, were known potential biomarkers for DS prenatal diagnosis, and were present in the zebrafish genome. With this approach, four genes were selected: RCAN1, ITSN1, ATP5PO and SUMO3. However, only overexpression of ATP5PO, coding for a component of the mitochondrial ATPase, led to significant reduction of ENS cells. Paradoxically, in vitro studies showed that overexpression of ATP5PO led to a reduction of ATP5PO protein levels. Impaired neuronal differentiation and reduced mitochondrial ATP production, were also detected in vitro, after overexpression of ATP5PO in a neuroblastoma cell line. Finally, epistasis was observed between ATP5PO and ret, the most important HSCR gene. Taken together, our results identify ATP5PO as the gene responsible for the increased risk of HSCR in DS patients in particular if RET variants are also present, and show that a balanced expression of ATP5PO is required for normal ENS development.</p

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

Requirements for systemic sclerosis expert centres in the Netherlands: a Delphi consensus study

Introduction: Systemic sclerosis is a rare and complex disease. Optimal management of patients requires knowledge and experience and, importantly, intensive collaboration between hospitals and multidisciplinary teams. Definition and recognition of expert centres in systemic sclerosis is currently lacking, which complicates collaboration between centres and leaves patients poorly informed. The aim of this study was to develop a set of requirements for two types of systemic sclerosis centres in order to establish a nationwide structure for an optimal and transparent organization of care. Methods: A three-round Delphi study was conducted among a panel of rheumatologists working at university or regional hospitals across the Netherlands. Prior to the final consensus round, a session with a patient panel (N = 22) was held. The results of this meeting were described in the last round for rheumatologists. Criteria were divided into five categories: (1) medical care, (2) case load, (3) collaboration, (4) research, (5) training of staff, and (6) other. In the first round, criteria derived from literature were proposed and participants could add criteria that were missing. For every item, participants could indicate if they thought the item should be included for two types of systemic sclerosis centres: (1) systemic sclerosis expert centre or (2) systemic sclerosis treatment centres. Consensus was reached when more than 85% of the panel agreed. Results: In total, 47 rheumatologists participated in Delphi round 1, 35 in round 2 and 43 in round 3. Additional suggestions were added by the patient panel (n = 22). Consensus was reached for the requirements of systemic sclerosis expert centres (45 items) and systemic sclerosis treatment centres (29 items) including minimal caseloads of annual suspected systemic sclerosis cases and total patients in care. Conclusion: Requirements of centres for systemic sclerosis care in the Netherlands were established in this study. Feasibility of certification should be evaluated next. Our proposed list can serve as a model for other countries.Pathophysiology and treatment of rheumatic disease

Localization of ultrasound in a three-dimensional elastic network

After exactly half a century of Anderson localization, the subject is more alive than ever. Direct observation of Anderson localization of electrons was always hampered by interactions and finite temperatures. Yet, many theoretical breakthroughs were made, highlighted by finite-size scaling, the self-consistent theory and the numerical solution of the Anderson tight-binding model. Theoretical understanding is based on simplified models or approximations and comparison with experiment is crucial. Despite a wealth of new experimental data, with microwaves, light, ultrasound and cold atoms, many questions remain, especially for three dimensions. Here we report the first observation of sound localization in a random three-dimensional elastic network. We study the time-dependent transmission below the mobility edge, and report ``transverse localization'' in three dimensions, which has never been observed previously with any wave. The data are well described by the self-consistent theory of localization. The transmission reveals non-Gaussian statistics, consistent with theoretical predictions.Comment: Final published version, 5 pages, 4 figure

Physical therapy in patients with systemic sclerosis: physical therapists’ perspectives on current delivery and educational needs

Objective: To assess the perspectives of physical therapists treating patients with systemic sclerosis (SSc) on their current practice and educational needs. Method: In July 2019, 405 SSc patients attending a multidisciplinary SSc programme received a survey on physical therapy. Patients who indicated having received physical therapy in the past 2 years were asked to invite their treating physical therapist to complete a questionnaire including sociodemographic characteristics, referral process, content of treatment, perceived knowledge and skills, and educational needs (mostly yes/no answers). Results: Forty-eight of 80 possibly eligible physical therapists treating SSc patients returned the questionnaire [median age 44 years (interquartile range 35–58); 52% female; median number of SSc patients currently treated: 1 (range 1–4)]. Eighty-one per cent (n = 39) of physical therapists had received a referral, with 69% (n = 27/39) judging its content as insufficient. The most often provided types of exercises were range of motion (96%), muscle-strengthening (85%), and aerobic (71%) exercises, followed by hand (42%) and mouth (10%) exercises. Concerning manual treatment, 65% performed either massage or passive mobilization. Regarding competences, 65% indicated feeling capable of treating SSc patients. Nevertheless, 85% expressed the need for an information website on physical therapy in SSc, and 77% for postgraduate education on SSc. Conclusion: Primary care physical therapists treating patients with SSc used a wide range of treatment modalities. Although most stated that they treated very few patients, the majority felt capable of treating SSc patients. Nevertheless, the large majority expressed a need for additional information and educational activities concerning SSc

Federating structural models and data:Outcomes from a workshop on archiving integrative structures

Structures of biomolecular systems are increasingly computed by integrative modeling. In this approach, a structural model is constructed by combining information from multiple sources, including varied experimental methods and prior models. In 2019, a Workshop was held as a Biophysical Society Satellite Meeting to assess progress and discuss further requirements for archiving integrative structures. The primary goal of the Workshop was to build consensus for addressing the challenges involved in creating common data standards, building methods for federated data exchange, and developing mechanisms for validating integrative structures. The summary of the Workshop and the recommendations that emerged are presented here