Guideline for the management of hip fractures 2020: Guideline by the Association of Anaesthetists.

We convened a multidisciplinary Working Party on behalf of the Association of Anaesthetists to update the 2011 guidance on the peri-operative management of people with hip fracture. Importantly, these guidelines describe the core aims and principles of peri-operative management, recommending greater standardisation of anaesthetic practice as a component of multidisciplinary care. Although much of the 2011 guidance remains applicable to contemporary practice, new evidence and consensus inform the additional recommendations made in this document. Specific changes to the 2011 guidance relate to analgesia, medicolegal practice, risk assessment, bone cement implantation syndrome and regional review networks. Areas of controversy remain, and we discuss these in further detail, relating to the mode of anaesthesia, surgical delay, blood management and transfusion thresholds, echocardiography, anticoagulant and antiplatelet management and postoperative discharge destination. Finally, these guidelines provide links to supplemental online material that can be used at readers' institutions, key references and UK national guidance about the peri-operative care of people with hip and periprosthetic fractures during the COVID-19 pandemic.

Genetic algorithm-based control of birefringent filtering for self-tuning, self-pulsing fiber lasers.

Polarization-based filtering in fiber lasers is well-known to enable spectral tunability and a wide range of dynamical operating states. This effect is rarely exploited in practical systems, however, because optimization of cavity parameters is nontrivial and evolves due to environmental sensitivity. Here, we report a genetic algorithm-based approach, utilizing electronic control of the cavity transfer function, to autonomously achieve broad wavelength tuning and the generation of Q-switched pulses with variable repetition rate and duration. The practicalities and limitations of simultaneous spectral and temporal self-tuning from a simple fiber laser are discussed, paving the way to on-demand laser properties through algorithmic control and machine learning schemes.

An Irish Experience in Establishing and Evaluating an Intern Led Teaching Programme.

Near-Peer Teaching is a relatively new and expanding area of medical education. The benefit to medical students has been demonstrated in numerous contexts around the world. Our aim was to establish a structured Intern-Led Teaching (ILT) programme in the context of an Irish Intern Training Network affiliated to an Irish Medical School. We then sought to evaluate the success of this programme. Seventy interns were enrolled in the ILT programme and completed a Train the Trainer course involving teaching methods and skills of effective feedback. Following this, the intern tutors delivered several one-hour teaching sessions in small groups to final year medical students on a weekly basis. At the end of each teaching block, a feedback questionnaire was distributed to participating students to evaluate their experiences of this new teaching modality. Tutorial topics were varied. They included clinical examination, history taking, prescribing, and emergencies. Eighty-one percent of students found the intern-led tutorials to be beneficial compared to tutorials run by more senior doctors. Additionally, students felt that with intern led tutorials they could ask questions they otherwise would not. There was a more comfortable environment, and information taught was considered more relevant. A significant number of students felt less nervous about the final medical examinations after the intern-led tutorials. The establishment of a structured intern-led teaching programme was well received by final year medical students. This project shows that interns are a valuable teaching resource in the medical school and should be included in medical schools' curricula.

Highly efficient mid-infrared difference-frequency generation using synchronously pulsed fiber lasers.

We report the development of a high average power, picosecond-pulse, mid-infrared source based on difference-frequency generation (DFG) of two synchronous master oscillator power fiber amplifier systems. The generated idler can be tuned over the range 3.28-3.45 µm delivering greater than 3.4 W of average power, with a maximum pump to total DFG power conversion efficiency of 78%. The benefits of a synchronously pumped scheme, compared to CW seeding of DFG sources, are discussed.

Fiber-integrated frequency-doubling of a picosecond Raman laser to 560 nm.

We report the development of a fiber-integrated picosecond source at 560 nm by second harmonic generation of a Raman fiber laser. A picosecond ytterbium master oscillator power fiber amplifier is used to pulse-pump a Raman amplifier, which is seeded by a continuous wave distributed feedback laser diode operating at 1120 nm. The pulse train generated at 1120 nm is frequency-doubled in a fiber-coupled periodically-poled lithium niobate crystal module, producing 450 mW of average power at 560 nm with a pulse duration of 150 ps at a repetition rate of 47.5 MHz. The near diffraction-limited (M(2) = 1.02) collimated output beam is ideal for super-resolution microscopy applications.

Wideband saturable absorption in few-layer molybdenum diselenide (MoSe2) for Q-switching Yb-, Er- and Tm-doped fiber lasers.

We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices.

Duration-tunable picosecond source at 560 nm with watt-level average power.

A pulse source at 560 nm that is tunable in duration between 50 ps and 2.7 ns with >1 W of average power and near diffraction-limited beam quality is demonstrated. The source is based on efficient (up to 50%) second-harmonic generation in a periodically poled lithium tantalate crystal of a linearly polarized fiber-integrated Raman amplifier operating at 1120 nm. A duration-tunable ytterbium master-oscillator power-fiber amplifier is used to pulse-pump the Raman amplifier, which is seeded by a continuous-wave distributed-feedback laser diode at 1120 nm. The performance of the system using two different master oscillator schemes is compared. A pulse energy of up to 765 nJ is achieved with a conversion efficiency of 25% from the ytterbium fiber pump, demonstrating a compact and turn-key architecture for obtaining high peak-power radiation at 560 nm.

Fiber grating compression of giant-chirped nanosecond pulses from an ultra-long nanotube mode-locked fiber laser.

We demonstrate that the giant chirp of coherent, nanosecond pulses generated in an 846 m long, all-normal dispersion, nanotube mode-locked fiber laser can be compensated using a chirped fiber Bragg grating compressor. Linear compression to 11 ps is reported, corresponding to an extreme compression factor of ∼100. Experimental results are supported by numerical modeling, which is also used to probe the limits of this technique. Our results unequivocally conclude that ultra-long cavity fiber lasers can support stable dissipative soliton attractors and highlight the design simplicity for pulse-energy scaling through cavity elongation.

Excess of rare novel loss-of-function variants in synaptic genes in schizophrenia and autism spectrum disorders.

Schizophrenia (SZ) and autism spectrum disorders (ASDs) are complex neurodevelopmental disorders that may share an underlying pathology suggested by shared genetic risk variants. We sequenced the exonic regions of 215 genes in 147 ASD cases, 273 SZ cases and 287 controls, to identify rare risk mutations. Genes were primarily selected for their function in the synapse and were categorized as: (1) Neurexin and Neuroligin Interacting Proteins, (2) Post-synaptic Glutamate Receptor Complexes, (3) Neural Cell Adhesion Molecules, (4) DISC1 and Interactors and (5) Functional and Positional Candidates. Thirty-one novel loss-of-function (LoF) variants that are predicted to severely disrupt protein-coding sequence were detected among 2 861 rare variants. We found an excess of LoF variants in the combined cases compared with controls (P=0.02). This effect was stronger when analysis was limited to singleton LoF variants (P=0.0007) and the excess was present in both SZ (P=0.002) and ASD (P=0.001). As an individual gene category, Neurexin and Neuroligin Interacting Proteins carried an excess of LoF variants in cases compared with controls (P=0.05). A de novo nonsense variant in GRIN2B was identified in an ASD case adding to the growing evidence that this is an important risk gene for the disorder. These data support synapse formation and maintenance as key molecular mechanisms for SZ and ASD.

De novo mutations in schizophrenia implicate chromatin remodeling and support a genetic overlap with autism and intellectual disability.

Schizophrenia is a serious psychiatric disorder with a broadly undiscovered genetic etiology. Recent studies of de novo mutations (DNMs) in schizophrenia and autism have reinforced the hypothesis that rare genetic variation contributes to risk. We carried out exome sequencing on 57 trios with sporadic or familial schizophrenia. In sporadic trios, we observed a ~3.5-fold increase in the proportion of nonsense DNMs (0.101 vs 0.031, empirical P=0.01, Benjamini-Hochberg-corrected P=0.044). These mutations were significantly more likely to occur in genes with highly ranked probabilities of haploinsufficiency (P=0.0029, corrected P=0.006). DNMs of potential functional consequence were also found to occur in genes predicted to be less tolerant to rare variation (P=2.01 × 10(-)(5), corrected P=2.1 × 10(-)(3)). Genes with DNMs overlapped with genes implicated in autism (for example, AUTS2, CHD8 and MECP2) and intellectual disability (for example, HUWE1 and TRAPPC9), supporting a shared genetic etiology between these disorders. Functionally CHD8, MECP2 and HUWE1 converge on epigenetic regulation of transcription suggesting that this may be an important risk mechanism. Our results were consistent in an analysis of additional exome-based sequencing studies of other neurodevelopmental disorders. These findings suggest that perturbations in genes, which function in the epigenetic regulation of brain development and cognition, could have a central role in the susceptibility to, pathogenesis and treatment of mental disorders.

Tunable Q-switched fiber laser based on saturable edge-state absorption in few-layer molybdenum disulfide (MoS2).

We fabricate a few-layer molybdenum disulfide (MoS2) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from 1030 to 1070 nm. Self-starting Q-switching generates 2.88 µs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS2 sample, despite operating at photon energies lower than the material bandgap.

Fiber-integrated 780 nm source for visible parametric generation.

We report the development of a fully fiber-integrated pulsed master oscillator power fibre amplifier (MOPFA) source at 780 nm, producing 3.5 W of average power with 410 ps pulses at a repetition rate of 50 MHz. The source consists of an intensity modulated 1560 nm laser diode amplified in an erbium fiber amplifier chain, followed by a fiber coupled periodically poled lithium niobate crystal module for frequency doubling. The source is then used for generating visible light through four-wave mixing in a length of highly nonlinear photonic crystal fiber: 105 mW at 668 nm and 95 mW at 662 nm are obtained, with pump to anti-Stokes conversion slope efficiencies exceeding 6% in both cases.

Chirped pulse formation dynamics in ultra-long mode-locked fiber lasers.

By modeling giant chirped pulse formation in ultra-long, normally dispersive, mode-locked fiber lasers, we verify convergence to a steady-state consisting of highly chirped and coherent, nanosecond-scale pulses, which is in good agreement with recent experimental results. Numerical investigation of the transient dynamics reveals the existence of dark soliton-like structures within the envelope of the initial noisy pulse structure. Quasi-stationary dark solitons can persist throughout a large part of the evolution from noise to a stable dissipative soliton solution of the mode-locked laser cavity.

Stimulated Brillouin scattering of visible light in small-core photonic crystal fibers.

We characterize stimulated Brillouin scattering (SBS) of visible light in small-core photonic crystal fiber (PCF). Threshold powers under 532 nm excitation agree with established theory, in contrast to measured values up to five times greater than expected for Brillouin scattering of 1550 nm light. An isolated, single-peaked signal at a Stokes shift of 33.5 GHz is observed, distinct from the multi-peaked Stokes spectra expected when small-core PCF is pumped in the infrared. This wavelength-dependence of the Brillouin threshold, and the corresponding spectrum, are explained by the acousto-optic interactions in the fiber, governed by dimensionless length scales that relate the modal area to the core size, and the pump wavelength to PCF hole pitch. Our results suggest new opportunities for exploiting SBS of visible light in small-core PCFs.

Characterization of nonlinear saturation and mode-locking potential of ionically-doped colored glass filter for short-pulse fiber lasers.

The nonlinear saturable absorption of an ionically-doped colored glass filter is measured directly using a Z-scan technique. For the first time, we demonstrate the potential of this material as a saturable asborber in fiber lasers. We achieve mode-locking of an ytterbium doped system. Mode-locking of cavities with all-positive and net-negative group velocity dispersion are demonstrated, achieving pulse durations of 60 ps and 4.1 ps, respectively. This inexpensive and optically robust material, with the potential for broadband operation, could surplant other saturable absorber devices in affordable mode-locked fiber lasers.

Simultaneous scalar and cross-phase modulation instabilities in highly birefringent photonic crystal fiber.

We report the experimental observation of scalar and cross-phase modulation instabilities by pumping a highly birefringent photonic crystal fiber in the normal dispersion regime at 45° to its principal polarization axes. Five sideband pairs (two scalar and three vector ones) are observed simultaneously in the spontaneous regime, four of which have a large frequency shift from the pump, in the range 79-93 THz. These results are in excellent agreement with phase-matching arguments and numerical simulations.

Mid-infrared Raman-soliton continuum pumped by a nanotube-mode-locked sub-picosecond Tm-doped MOPFA.

We demonstrate a mid-infrared Raman-soliton continuum extending from 1.9 to 3 µm in a highly germanium-doped silica-clad fiber, pumped by a nanotube mode-locked thulium-doped fiber system, delivering 12 kW sub-picosecond pulses at 1.95 µm. This simple and robust source of light covers a portion of the atmospheric transmission window.

Recurring themes arising during medical research ethics committee review.

A standard application form for the ethical review of health-related research studies has recently been adopted by many Irish medical research ethics committees. In order to assess the impact of the new form, we reviewed all comments made by the Beaumont Hospital Ethics Committee during two six-month periods, immediately prior to adoption of the new form (2010), and soon afterwards (2011). Neither volume nor comment type differed significantly between the two observation periods. Participant documentation (information leaflets and consent forms) accounted for the largest proportion of comments (2010; 44%, 2011; 37%). Other common areas prompting queries were study administration (7%), design (12%) and procedures (13%), participant selection and recruitmen (8%), and lastly data protection (9%). Because of these findings, the standard operating procedures of the committee have been revised--use of provided template participant documentation is strongly encouraged, and a "Recurring Review Themes" checklist is highlighted to all applicants.

Tm-doped fiber laser mode-locked by graphene-polymer composite.

We demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94 µm, using a graphene-polymer based saturable absorber. The laser outputs 3.6 ps pulses, with ~0.4 nJ energy and an amplitude fluctuation ~0.5%, at 6.46 MHz. This is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.

Fission of solitons in continuous-wave supercontinuum.

We use numerical simulations to revisit the generation of fiber supercontinua pumped by partially coherent continuous-wave (CW) sources. Specifically, we show that intensity fluctuations characteristic of temporal partial coherence can be described as a stochastic train of high-order solitons, whose individual dynamics drive continuum formation. For sources with sufficiently low coherence, these solitons actually undergo fission rather than modulation instability, changing the nature of the CW supercontinuum evolution.