Swallowing difficulties are estimated to affect 590 million people worldwide and the modification of food and fluids is considered the cornerstone of dysphagia management. Contemporary practice uses the International Dysphagia Diet Standardisation Initiative (IDDSI), however, the validity and reliability of IDDSI when translated into another language has not been investigated. This study describes the translation process and confirms the validity and reliability of IDDSI when translated into another language (Swedish).
View Article and Find Full Text PDFWe analyse the dynamics and conditions for stability in an array of two laterally-coupled nanowire lasers in terms of their separation, difference in resonant frequencies and pumping rate under conditions of weak coupling. We find that the regions of stability are very small and are found close to zero frequency offset between the lasers. Outside these regions various forms of instability including periodic oscillation, chaos and complex dynamics are predicted.
View Article and Find Full Text PDFWe consider a modified version of the spin-flip model (SFM) that describes optically pumped quantum dot (QD) spin-polarized vertical-cavity surface-emitting lasers (VCSELs). Maps showing different dynamical regions and those consisting of various key bifurcations are constructed by direct numerical simulations and a numerical path continuation technique, respectively. A comparison between them clarifies the physical mechanism that governs the underlying dynamics as well as routes to chaos in QD spin-VCSELs.
View Article and Find Full Text PDFWe study the nonlinear dynamics of solitary and optically injected two-element laser arrays with a range of waveguide structures. The analysis is performed with a detailed direct numerical simulation, where high-resolution dynamic maps are generated to identify regions of dynamic instability in the parameter space of interest. Our combined one- and two-parameter bifurcation analysis uncovers globally diverse dynamical regimes (steady-state, oscillation, and chaos) in the solitary laser arrays, which are greatly influenced by static design waveguiding structures, the amplitude-phase coupling factor of the electric field, i.
View Article and Find Full Text PDFWe report here for the first time (to our knowledge), a new and universal mechanism by which a two-element laser array is locked to external optical injection and admits stably injection-locked states within a nontrivial trapezoidal region. The rate equations for the system are studied both analytically and numerically. We derive a simple mathematical expression for the locking conditions, which reveals that two parallel saddle-node bifurcation branches, not reported for conventional single lasers subject to optical injection, delimit the injection locking range and its width.
View Article and Find Full Text PDFWe report on a master and slave configuration consisting of two optically pumped spin-vertical-cavity surface-emitting lasers for chaos synchronization and secure communication. Under appropriate conditions, high-quality chaos synchronization is achieved. We propose two encryption schemes, where either the pump magnitude or polarization is modulated.
View Article and Find Full Text PDFSustained, large amplitude and tunable birefringence-induced oscillations are obtained in a spin-vertical cavity surface-emitting laser (spin-VCSEL). Experimental evidence is provided using a spin-VCSEL operating at 1300 nm, under continuous-wave optical pumping and at room temperature. Numerical and stability analyses are performed to interpret the experiments and to identify the combined effects of pump ellipticity, spin relaxation rate, and cavity birefringence.
View Article and Find Full Text PDFBackground: During a routine human immunodeficiency virus (HIV) investigation, Florida Department of Health staff identified a house (house A) in which over 150 individuals had resided at least briefly. Further investigation revealed that house A is used by the producer of a small adult film production company to board his actors. This report describes sexually transmitted infection (STI) prevalence among male actors in gay adult films residing in a common Florida residence.
View Article and Find Full Text PDFPsychotherapy supervision and training are now widely available online. However, many supervisors still may be unclear on how online supervision actually works, or what it actually looks like in practice. In this article, three case examples of online videoconference-based supervision programs will be described.
View Article and Find Full Text PDFTunable microwave signal generation with frequencies ranging from below 1 GHz to values over 40 GHz is demonstrated experimentally with a 1310 nm Quantum Dot (QD) Distributed-Feedback (DFB) laser. Microwave signal generation is achieved using the period 1 dynamics induced in the QD DFB under optical injection. Continuous tuning in the positive detuning frequency range of the quantum dot's unique stability map is demonstrated.
View Article and Find Full Text PDFA modified spin-flip model is used to investigate the stability of optically-pumped quantum-dot spin-vertical cavity surface-emitting lasers. in terms of pump intensity and polarization. The stability maps exhibit pronounced polarization switching in the stable regions.
View Article and Find Full Text PDFAutomated protocols have been developed to characterize time series data in terms of stability. These techniques are applied to the output power time series of an optically injected vertical cavity surface emitting laser (VCSEL) subject to varying injection strength and optical frequency detuning between master and slave lasers. Dynamic maps, generated from high resolution, computer controlled experiments, identify regions of dynamic instability in the parameter space.
View Article and Find Full Text PDFWe report the first room temperature optical spin-injection of a dilute nitride 1300 nm vertical-cavity surface-emitting laser (VCSEL) under continuous-wave optical pumping. We also present a novel experimental protocol for the investigation of optical spin-injection with a fiber setup. The experimental results indicate that the VCSEL polarization can be controlled by the pump polarization, and the measured behavior is in excellent agreement with theoretical predictions using the spin flip model.
View Article and Find Full Text PDFWe present results from the first gridless networking field trial with flexible spectrum switching nodes and 620 km of installed fibre links. Signals at 10G, 12.25G, 42.
View Article and Find Full Text PDFWe report a new approach to mimic basic functionalities of a neuron using a 1550 nm Vertical Cavity Surface Emitting Laser (VCSEL) which is based on the polarisation switching (PS) that can be induced in these devices when subject to polarised optical injection. Positive and negative all-optical threshold operations are demonstrated experimentally using external optical injection into the two orthogonal polarizations of the fundamental transverse mode. The polarisation of the light emitted by the device is used to determine the state of the VCSEL-Neuron, active (orthogonal) or inactive (parallel).
View Article and Find Full Text PDFThe nonlinear properties of semiconductor lasers and laser amplifiers when subject to optical injection are reviewed and new results are presented for multisection lasers, vertical cavity semiconductor optical amplifiers, and surface-emitting lasers. The main underlying material parameters are outlined and the key design approaches are discussed for both edge-emitting and vertical cavity devices. An overview of theoretical modeling approaches is discussed and a summary of key experimental results is presented.
View Article and Find Full Text PDFWe report an experimental study of nonlinear effects, characteristic of mutual optical coupling, in an ultra-short coupling regime observed in a distributed Bragg reflector laser pair fabricated on the same chip. Optical feedback is amplified via a double pass through a common on-chip optical amplifier, which introduces further nonlinear phenomena. Optical coupling has been introduced via back reflection from a cleave-ended fibre.
View Article and Find Full Text PDFDifferent forms of wavelength polarization switching and bistability are reported in a 1550 nm vertical-cavity surface-emitting laser (VCSEL) operated just above threshold and subject to orthogonally polarized optical injection into the subsidiary orthogonal polarization mode. This diversity of behavior at the wavelength of 1550 nm offers promise for the use of VCSELs in optical signal processing and optical switching applications.
View Article and Find Full Text PDFExperimental observation of Optical Bistability (OB) and nonlinear gain is reported in a 1550-nm Vertical Cavity Semiconductor Optical Amplifier (VCSOA) under parallel and orthogonal polarized optical injection into the two orthogonal polarizations of the fundamental mode. Different nonlinear switching mechanisms, including anticlockwise and clockwise nonlinear gain and bistability, have been found when the polarization of the externally injected signal matches that of the injected mode, whilst a linear response is measured when the polarization is orthogonal to that of the mode under injection. This diversity of behavior with input polarization offers promise for the potential use of VCSOAs for all-optical signal processing and all-optical switching/routing applications.
View Article and Find Full Text PDF"Environmental medicine" is a new sub-discipline in the spectrum of medical specialization in Germany. The Berlin Academy of Occupational Medicine and Health Protection, now a branch of the Berlin Chamber of Physicians, developed a 200-lesson curriculum for physicians who want to specialize in this field. Coincidentally during the initial courses, the attendants were already highly qualified ("Facharzt"-level) and experts in various occupational fields, and hence the composition of the classes was highly heterogeneous on the levels of practical experience as well as theoretical knowledge.
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