Professionals' knowledge, skills and confidence on using the best practices for spinal cord injury physical activity counseling in Canada and the Netherlands.

Context: To improve physical activity (PA) participation in people with spinal cord injury (SCI), an international panel co-created theory- and evidence-based best practices for SCI PA counseling. This study aimed to identify and compare Canadian and Dutch counselors' knowledge, skills, and confidence in using these best practices.

Methods: An online survey was conducted in Canada and the Netherlands.

Nursing Practice of Airway Care Interventions and Prone Positioning in ICU Patients with COVID-19-A Dutch National Survey.

: Airway care interventions and prone positioning are used in critically ill patients with coronavirus disease 2019 (COVID-19) admitted to the intensive care unit (ICU) to improve oxygenation and facilitate mucus removal. At the onset of the COVID-19 pandemic, the decision-making process regarding the practice of airway care interventions and prone positioning was challenging. To provide an overview of the practice of airway care interventions and prone positioning during the second wave of the pandemic in the Netherlands.

Impact of Transforming Interface Geometry on Edge States in Valley Photonic Crystals.

We investigate how altering the interface geometry from a zigzag to a glide plane interface between two topologically distinct valley Hall emulating photonic crystals (VPC), profoundly affects edge states. We experimentally observe a transition from gapless to gapped edge states, accompanied by the occurrence of slow light within the Brillouin zone, rather than at its edge. We numerically simulate the propagation and measure the transmittance of the modified edge states through a specially designed valley-conserving defect.

The co-development and evaluation of an e-learning course on spinal cord injury physical activity counselling: a randomized controlled trial.

Background: Health, fitness and lifestyle professionals can play important roles in promoting physical activity in groups at risk of developing an inactive lifestyle, such as people with spinal cord injury (SCI). Tailored counselling is a promising tool to promote and improve physical activity levels. To support professionals to effectively have a conversation about physical activity with clients with SCI, evidence-based training and resources are needed.

Ultrafast Time Dynamics of Plasmonic Fractional Orbital Angular Momentum.

The creation and manipulation of optical vortices, both in free space and in two-dimensional systems such as surface plasmon polaritons (SPPs), has attracted widespread attention in nano-optics due to their robust topological structure. Coupled with strong spatial confinement in the case of SPPs, these plasmonic vortices and their underlying orbital angular momentum (OAM) have promise in novel light-matter interactions on the nanoscale with applications ranging from on-chip particle manipulation to tailored control of plasmonic quasiparticles. Until now, predominantly integer OAM values have been investigated.

Simultaneous Characterization of Two Ultrashort Optical Pulses at Different Frequencies Using a WS Monolayer.

The precise characterization of ultrashort laser pulses has been of interest to the scientific community for many years. Frequency-resolved optical gating (FROG) has been extensively used to retrieve the temporal and spectral field distributions of ultrashort laser pulses. In this work, we exploit the high, broad-band nonlinear optical response of a WS monolayer to simultaneously characterize two ultrashort laser pulses with different frequencies.

Breakdown of Spin-to-Helicity Locking at the Nanoscale in Topological Photonic Crystal Edge States.

We measure the local near-field spin in topological edge state waveguides that emulate the quantum spin Hall effect. We reveal a highly structured spin density distribution that is not linked to a unique pseudospin value. From experimental near-field real-space maps and numerical calculations, we confirm that this local structure is essential in understanding the properties of optical edge states and light-matter interactions.

Morphology-induced spectral modification of self-assembled WS pyramids.

Due to their intriguing optical properties, including stable and chiral excitons, two-dimensional transition metal dichalcogenides (2D-TMDs) hold the promise of applications in nanophotonics. Chemical vapor deposition (CVD) techniques offer a platform to fabricate and design nanostructures with diverse geometries. However, the more exotic the grown nanogeometry, the less is known about its optical response.

Radiationless anapole states in on-chip photonics.

High-index nanoparticles are known to support radiationless states called anapoles, where dipolar and toroidal moments interfere to inhibit scattering to the far field. In order to exploit the striking properties arising from these interference conditions in photonic integrated circuits, the particles must be driven in-plane via integrated waveguides. Here, we address the excitation of electric anapole states in silicon disks when excited on-chip at telecom wavelengths.

Effective pair-interaction of phase singularities in random waves.

In two-dimensional random waves, phase singularities are point-like dislocations with a behavior reminiscent of interacting particles. This-qualitative-consideration stems from the spatial arrangement of these entities, which finds its hallmark in a pair correlation reminiscent of a liquid-like system. Starting from their pair correlation function, we derive an effective pair-interaction for phase singularities in random waves by using a reverse Monte Carlo method.

Nonlinear Optical Response of a WS Monolayer at Room Temperature upon Multicolor Laser Excitation.

Currently, the nonlinear optical properties of 2D materials are attracting the attention of an ever-increasing number of research groups due to their large potential for applications in a broad range of scientific disciplines. Here, we investigate the interplay between nonlinear photoluminescence (PL) and several degenerate and nondegenerate nonlinear optical processes of a WS monolayer at room temperature. We illuminate the sample using two femtosecond laser pulses at frequencies ω and ω with photon energies below the optical bandgap.

Direct quantification of topological protection in symmetry-protected photonic edge states at telecom wavelengths.

Topological on-chip photonics based on tailored photonic crystals (PhCs) that emulate quantum valley-Hall effects has recently gained widespread interest owing to its promise of robust unidirectional transport of classical and quantum information. We present a direct quantitative evaluation of topological photonic edge eigenstates and their transport properties in the telecom wavelength range using phase-resolved near-field optical microscopy. Experimentally visualizing the detailed sub-wavelength structure of these modes propagating along the interface between two topologically non-trivial mirror-symmetric lattices allows us to map their dispersion relation and differentiate between the contributions of several higher-order Bloch harmonics.

Nanoscale Optical Addressing of Valley Pseudospins through Transverse Optical Spin.

Valley pseudospin has emerged as a good quantum number to encode information, analogous to spin in spintronics. Two-dimensional transition metal dichalcogenides (2D TMDCs) recently attracted enormous attention for their easy access to the valley pseudospin through valley-dependent optical transitions. Different ways have been reported to read out the valley pseudospin state.

Vertically-oriented MoS nanosheets for nonlinear optical devices.

Transition metal dichalcogenides such as MoS represent promising candidates for building blocks of ultra-thin nanophotonic devices. For such applications, vertically-oriented MoS (v-MoS) nanosheets could be advantageous as compared to conventional horizontal MoS (h-MoS) given that their inherent broken symmetry would favor an enhanced nonlinear response. However, the current lack of a controllable and reproducible fabrication strategy for v-MoS limits the exploration of this potential.

Poynting singularities in the transverse flow-field of random vector waves.

In order to utilize the full potential of tailored flows of electromagnetic energy at the nanoscale, we need to understand its general behavior given by its generic representation of interfering random waves. For applications in on-chip photonics as well as particle trapping, it is important to discern between the topological features in the flow-field of the commonly investigated cases of fully vectorial light fields and their 2D equivalents. We demonstrate the distinct difference between these cases in both the allowed topology of the flow-field and the spatial distribution of its singularities, given by their pair correlation function ().

Direct observation of topological edge states in silicon photonic crystals: Spin, dispersion, and chiral routing.

Topological protection in photonics offers new prospects for guiding and manipulating classical and quantum information. The mechanism of spin-orbit coupling promises the emergence of edge states that are helical, exhibiting unidirectional propagation that is topologically protected against back scattering. We directly observe the topological states of a photonic analog of electronic materials exhibiting the quantum spin Hall effect, living at the interface between two silicon photonic crystals with different topological order.

Circular Dichroism Measurement of Single Metal Nanoparticles Using Photothermal Imaging.

Circular dichroism (CD) spectroscopy is a powerful optical technique for the study of chiral materials and molecules. It gives access to an enantioselective signal based on the differential absorption of right and left circularly polarized light, usually obtained through polarization analysis of the light transmitted through a sample of interest. CD is routinely used to determine the secondary structure of proteins and their conformational state.

A full vectorial mapping of nanophotonic light fields.

Light is a union of electric and magnetic fields, and nowhere is the complex relationship between these fields more evident than in the near fields of nanophotonic structures. There, complicated electric and magnetic fields varying over subwavelength scales are generally present, which results in photonic phenomena such as extraordinary optical momentum, superchiral fields, and a complex spatial evolution of optical singularities. An understanding of such phenomena requires nanoscale measurements of the complete optical field vector.

Label-Free Optical Detection of DNA Translocations through Plasmonic Nanopores.

Solid-state nanopores are single-molecule sensors that hold great potential for rapid protein and nucleic-acid analysis. Despite their many opportunities, the conventional ionic current detection scheme that is at the heart of the sensor suffers inherent limitations. This scheme intrinsically couples signal strength to the driving voltage, requires the use of high-concentration electrolytes, suffers from capacitive noise, and impairs high-density sensor integration.

Electromagnetic Helicity in Complex Media.

Optical helicity density is usually discussed for monochromatic electromagnetic fields in free space. It plays an important role in the interaction with chiral molecules or nanoparticles. Here we introduce the optical helicity density in a dispersive isotropic medium.

Screening and fluctuation of the topological charge in random wave fields.

Vortices, phase singularities, and topological defects of any kind often reflect information that is crucial for understanding physical systems in which such entities arise. With near-field experiments supported by numerical calculations, we determine the fluctuations of the topological charge for phase singularities in isotropic random waves as a function of the size R of the observation window. We demonstrate that for two-dimensional fields such fluctuations increase with a superlinear scaling law, consistent with a R log R behavior.

Persistence and Lifelong Fidelity of Phase Singularities in Optical Random Waves.

Phase singularities are locations where light is twisted like a corkscrew, with positive or negative topological charge depending on the twisting direction. Among the multitude of singularities arising in random wave fields, some can be found at the same location, but only when they exhibit opposite topological charge, which results in their mutual annihilation. New pairs can be created as well.

Core-Shell Plasmonic Nanohelices.

We introduce core-shell plasmonic nanohelices, highly tunable structures that have a different response in the visible for circularly polarized light of opposite handedness. The glass core of the helices is fabricated using electron beam induced deposition and the pure gold shell is subsequently sputter coated. Optical measurements allow us to explore the chiral nature of the nanohelices, where differences in the response to circularly polarized light of opposite handedness result in a dissymmetry factor of 0.