Lessons learnt from the COVID-19 pandemic in selected countries to inform strengthening of public health systems: a qualitative study.

INTRODUCTION: The COVID-19 pandemic has prompted governments internationally to consider strengthening their public health systems. To support the work of Ireland's Public Health Reform Expert Advisory Group, the Health Information and Quality Authority, an independent governmental agency, was asked to describe the lessons learnt regarding the public health response to COVID-19 internationally and the applicability of this response for future pandemic preparedness. METHODS: Semi-structured interviews with key public health representatives from nine countries were conducted. Interviews were conducted in March and April 2022 remotely via Zoom and were recorded. Notes were taken by two researchers, and a thematic analysis undertaken. RESULTS: Lessons learnt from the COVID-19 pandemic related to three main themes: 1) setting policy; 2) delivering public health interventions; and 3) providing effective communication. Real-time surveillance, evidence synthesis, and cross-sectoral collaboration were reported as essential for policy setting; it was noted that having these functions established prior to the pandemic would lead to a more efficient implementation in a health emergency. Delivering public health interventions such as testing, contact tracing, and vaccination were key to limiting and or mitigating the spread of the SARS-CoV-2 virus. However, a number of challenges were highlighted such as staff capacity and burnout, delays in vaccination procurement, and reduced delivery of regular healthcare services. Clear, consistent, and regular communication of the scientific evidence was key to engaging citizens with mitigation strategies. However, these communication strategies had to compete with an infodemic of information being circulated, particularly through social media. CONCLUSIONS: Overall, functions relating to policy setting, public health interventions, and communication are key to pandemic response. Ideally, these should be established in the preparedness phase so that they can be rapidly scaled-up during a pandemic.

Spontaneous Symmetry Breaking in a Coherently Driven Nanophotonic Bose-Hubbard Dimer.

We report on the first experimental observation of spontaneous mirror symmetry breaking (SSB) in coherently driven-dissipative coupled optical cavities. SSB is observed as the breaking of the spatial or mirror Z_{2} symmetry between two symmetrically pumped and evanescently coupled photonic crystal nanocavities, and manifests itself as random intensity localization in one of the two cavities. We show that, in a system featuring repulsive boson interactions (U>0), the observation of a pure pitchfork bifurcation requires negative photon hopping energies (J<0), which we have realized in our photonic crystal molecule. SSB is observed over a wide range of the two-dimensional parameter space of driving intensity and detuning, where we also find a region that exhibits bistable symmetric behavior. Our results pave the way for the experimental study of limit cycles and deterministic chaos arising from SSB, as well as the study of nonclassical photon correlations close to SSB transitions.

Should we call the neurologist? The value and cost of a growing neurology consultation service.

BACKGROUND: St Vincent's University Hospital has an established neurology consultation service. Referral volumes have been growing. The Department regularly reviews its service to monitor changes and seek improvements. AIMS: We sought to determine the impact of the growing service on patient care, on the department itself in delivering the service, and on inpatient admission trends. METHODS: We reviewed the electronic referral forms of all consults seen over a 9-week period in 2014 (n = 213). We recorded the source of each consult, demographic information, clinical presentation, time from referral to consult, and outcome. We compared the consult list to inpatient admissions list to determine the proportion admitted from consults. We compared our results to previous reviews by this and other neurology departments in Ireland. RESULTS: Three quarters of neurology consults relate to acute admissions. Patients are all seen within one working day of referral. A significant change in management (83.6 %) resulted from the majority of consults. Consultants see an average of 4.8 (range 0-10) consults per day, needing up to 7.5 h per day to deliver the service. One-third of the department's inpatients come from consults. CONCLUSIONS: The service significantly benefits patient care. The increasing number of consults will require increased resources and/or service reorganisation to maintain the current level of service.

What is the role of general practice in addressing youth mental health? A discussion paper.

BACKGROUND: Mental and substance use disorders are a leading cause of morbidity among young people. Policy and clinical services in Ireland are endeavouring to address these twin issues. AIMS: To review the emerging literature on the role of general practice in addressing youth mental health and to discuss the implications of this literature for further research, education and service delivery. METHODS: We conducted a review of 'PubMed' and a web search of relevant national/international primary/mental healthcare agencies and professional bodies. RESULTS: Although general practice has an important role in addressing youth mental health, there are challenges in how young people seek help. Specifically, young people do not engage with healthcare agencies and many factors which act as barriers and enablers in this regard have been identified. The detection and treatment of mental and substance use disorders by GPs can be improved and implementing interventions to improve screening and early intervention are likely to be valuable. CONCLUSIONS: General practice is a central agency in addressing youth mental health and complex multifaceted interventions (education, clinical guidelines, and promoting awareness) are likely to support its role. Further research exploring this issue is a priority.

Dating fractures in infants.

AIM: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. MATERIALS AND METHODS: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. RESULTS: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. CONCLUSION: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

Method for pulse transformations using dispersion varying optical fibre tapers.

I introduce the problem of transforming one optical pulse into another via nonlinear propagation in a length of dispersion varying optical fibre. Then using a genetic algorithm to design the dispersion profiles, I show that the problem can be solved leading to high quality pulse transforms that are significantly better than what has been published previously. Finally I suggestion further work and other applications for this method.

Dysplastic kidneys in children - do they grow?

OBJECTIVES: Dysplastic kidneys (DK) are a common cause of chronic kidney disease (CKD). Little is known about their growth or how their sonographic appearance changes. This study aimed to test the hypothesis that DK gain little length, and to identify radiologic trends predictive of CKD. METHODS: Ultrasound scans of children with DK born in 1980-2005 and referred to a single tertiary centre were analysed by a pediatric radiologist. Renal lengths were plotted on standard nomograms and the degree of dysplastic appearance noted. Factors related to DK - bladder outlet obstruction, vesico-ureteric reflux and renal impairment - were noted. RESULTS: Fifty-three children were studied (83 kidneys), of whom 41 were boys; 289 scans were analysed. In 33 children there was associated bladder outlet obstruction or vesico-ureteric reflux. Forty-four DK were noted to fall off their renal length 'centile'. This correlated well with the development of CKD and is statistically significant. Deterioration occurred in 53% of DK; primarily progressive reduction in corticomedullary differentiation. This also correlated well with development of CKD. CONCLUSION: More than half of the DK showed poor growth velocity. This, together with the degree of sonographic abnormality, carries a high predictive value for development of CKD. We recommend diligent serial sonography to follow renal growth and dysplastic appearance in children with DK.

Improved method for estimating the minimum length of modal filters fabricated for stellar interferometry.

We present an improved theoretical model to estimate the minimum fiber length required for achieving a desired degree of wavefront filtering in stellar interferometry. The proposed model is based on modal analysis of the fiber and is compared with numerical results obtained through the beam propagation method as well as with reported experimental observations. We also study the effect of introducing a spatial filter at the output end of the fiber and show that the required fiber length can be reduced significantly by introducing a circular aperture of optimum radius after the fiber.

Radiological features of Meckel's diverticulum and its complications.

Meckel's diverticulum is the most common congenital abnormality of the small bowel. The majority of patients with this anomaly will remain asymptomatic; however, several complications may occur, including obstruction, intussusception, perforation, diverticulitis, and gastrointestinal haemorrhage. These complications may produce a variety of different clinical features and radiological appearances. The purpose of this article is to review the potential imaging manifestations of Meckel's diverticulum and its complications and discuss the advantages and disadvantages of the imaging techniques available.

Optical snakes and ladders: dispersion and nonlinearity in microcoil resonators.

Microcoil resonators are a radical new geometry for high Q resonators with unique linear features. In this paper I briefly summarise their linear properties before extending the analysis to nonlinear interactions in microcoil resonators. As expected such nonlinear resonators are bistable and exhibit hysteresis. Finally I discuss possible applications and extensions to such resonators.

Control of surface modes in low loss hollow-core photonic bandgap fibers.

We report on the fabrication and characterization of hollow-core photonic bandgap fibers that do not suffer from surface mode coupling within the photonic bandgap of the cladding. This enables low attenuation over the full spectral width of the bandgap--we measured a minimum loss of 15 dB/km and less than 50 dB/km over 300 nm for a fiber operating at 1550 nm. As a result of the increased bandwidth, the fiber has reduced dispersion and dispersion slope--by a factor of almost 2 compared to previous fibers. These features are important for several applications in high-power ultrashort pulse compression and delivery. Realizing these advances has been possible due to development of a modified fabrication process which makes the production of low-loss hollow-core fibers both simpler and quicker than previously.

The effect of periodicity on the defect modes of large mode area microstructured fibers.

It is well known that periodic variations in refractive index can be used to create guidance in an optical fiber via photonic bandgap effects. It has also been shown that periodic structure in index-guiding microstructured fibers can lead to the guidance of additional leaky higher-order modes due to bandgap effects. Here we demonstrate that this additional guidance mechanism can have important practical implications in large mode area silica microstructured fibers. We also demonstrate that similar modes can exist when a bandgap is not present and attribute this guidance to a low density of states. Excellent agreement between theoretical predictions and experimental observations is demonstrated. We explore the impact of these additional modes on the practical operation of these fibers and explore ways of minimizing their effects via the fiber geometry.

Design of 7 and 19 cells core air-guiding photonic crystal fibers for low-loss, wide bandwidth and dispersion controlled operation.

We study the modal properties of feasible hollow-core photonic bandgap fibers (HC-PBGFs) with cores formed by omitting either 7 or 19 central unit-cells. Firstly, we analyze fibers with thin core surrounds and demonstrate that even for large cores the proposed structures are optimum for broad-band transmission. We compare these optimized structures with fibers which incorporate antiresonant core surrounds which are known to have low-loss. Trade-offs between loss and useful bandwidth are presented. Finally, we study the effects that small modifications to the core surround have on the fiber's group velocity dispersion, showing the possibility of engineering the dispersion in hollow-core photonic bandgap fibers.

Brillouin characterization of holey optical fibers.

We report the results of detailed measurements on the Brillouin frequency shift (BFS), gain bandwidth, and gain coefficients of several small-core holey optical fibers (HFs) of both uniform and axially varying structural characteristics and compare these with measurements on more conventional fibers. Our measurements show that the BFS of HFs is first-order proportional to the modal index for light propagating along the fiber and is thus extremely sensitive to its precise structural parameters. Our results highlight the possibility of using distributed Brillouin scattering measurements to perform nondestructive structural characterization of HFs, and the possibility of producing Brillouin-suppressed HFs using controlled structural variation along the fiber length.

Cascaded-chi(2)-interaction-based frequency-resolved optical gating in a periodically poled LiNbO3 waveguide.

We demonstrate a novel frequency-resolved optical gating (FROG) configuration based on cascaded second-order nonlinear interactions. Its implementation in a 2.6 cm long quasi-phase-matched LiNbO3 waveguide allowed high-quality retrieval of 2 ps to 80 fJ pulses at 1.56 microm.

Optimizing the usable bandwidth and loss through core design in realistic hollow-core photonic bandgap fibers.

The operational bandwidth of hollow-core photonic bandgap fibers (PBGFs) is drastically affected by interactions between the fundamental core mode and surface modes guided at the core-cladding interface. By systematically studying realistic hollow-core PBGFs we identify a new design regime robust in eliminating the presence of surface modes. We present new fiber designs with a fundamental core mode free of anticrossings with surface modes at all wavelengths within the bandgap, allowing for a low-loss operational bandwidth of ~17% of the central gap wavelength.

Inverse design and fabrication tolerances of ultra-flattened dispersion holey fibers.

We employ a Genetic Algorithm for the dispersion optimization of a range of holey fibers (HF) with a small number of air holes but good confinement loss. We demonstrate that a dispersion of 0 +/- 0.1 ps/nm/km in the wavelength range between 1.5 and 1.6 microm is achievable for HFs with a range of different transversal structures, and discuss some of the trade-offs in terms of dispersion slope, nonlinearity and confinement loss. We then analyze the sensitivity of the total dispersion to small variations from the optimal value of specific structural parameters, and estimate the fabrication accuracy required for the reliable fabrication of such fibers.

The effect of core asymmetries on the polarization properties of hollow core photonic bandgap fibers.

We present the results of numerical simulations of the modal properties of Photonic Band Gap Fibers (PBGFs) in which a structural distortion of the silica ring surrounding the air core is gradually introduced. We demonstrate that surface modes supported within such fibers are very sensitive to structural distortions, and that any asymmetric change in the structure can break their degeneracy resulting in associated changes in the anticrossing behavior of the orthogonally polarized core modes, and the development of polarization dependent transmission properties. Our results provide insight into recent experimental observations of wavelength dependent PDL and birefringence in PBGFs.

Small bowel volvulus due to giant mesenteric lipoma.

We report on a 14-year-old girl with acute intestinal obstruction due to volvulus of the small bowel caused by a giant mesenteric lipoma. To the best of our knowledge, this presentation of a mesenteric lipoma is unknown in the previous paediatric literature.

A survey of non-accidental injury imaging in England, Scotland and Wales.

AIM: To identify the potential national variation in non-accidental injury (NAI) imaging in England, Scotland and Wales. MATERIALS AND METHODS: A postal survey was sent to 323 hospitals with both paediatric and radiology departments. These were identified by a search through the Medical Directory. RESULTS: One hundred and thirteen of 323 postal questionnaires were returned within the study period (35%). Sixteen were excluded from the study because either no NAI imaging was performed at that institution or an incorrect address had been used. The total number of completed questionnaires was 97 (30%). Extensive variation was seen in all aspects of NAI imaging including imaging techniques used, total case numbers, follow-up imaging and those who report the NAI imaging. CONCLUSIONS: There is currently no national protocol that incorporates all aspects of NAI imaging in England, Scotland and Wales. Extensive variation in practice has been shown by this survey. Further standardization of NAI imaging practice is required. The draft BSPR skeletal survey guidelines and routine neurological imaging is recommended.