Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Elasticity and antiferromagnetism of metallic antiferromagnetics

If an antiferromagnetic is spontaneously deformed on cooling through the Néel temperature, then the application of an external stress results in a redistribution of domain vectors, e.g. they may rotate or antiferromagnetic domain walls may move. This causes an additional strain component which will be apparent as an anomalous variation of the Young's modulus with the temperature. The results of measurements of the temperature dependence of Young's modulus for antiferromagnetic γ-CuMn alloys and mixed phase (α + γ) CuMn alloys are reported. The (α + y) alloys show (a) a Young's modulus variation of the expected form which is due to the contained α-Mn, (b) a Young's modulus anomaly at about 130 °K associated with the precipitated γ-CuMn (containing 40 atomic percent Mn). It is shown that the latter phase below 130 °K exhibits ferromagnetic characteristics. A smooth temperature variation of Young's modulus has been obtained for Pd which is consistent with the assumption that Pd is not antiferromagnetic at low temperatures.On peut prévoir une variation du module d'Young avec la température au point de Néel sur les substances antiferromagnétiques. Nous donnons ici les résultats des mesures relatives aux alliages CuMn(γ) et aux alliages CuMn à plusieurs phases (α + y) On trouve sur ces derniers la variation prévue due à Mn α et également une anomalie, vers 130 °K, attribuée à la présence de MnCu y précipité. Cette dernière phase est ferromagnétique au-dessous de 130 °K. Une variation régulière avec la température du module d'Young de Pd confirme le fait qu'aux basses températures Pd ne serait pas antiferromagnétique

Passive harmonic modelocking in monolithic compound-cavity laser diodes

Passive harmonic modelocking operation of novel compound-cavity laser diodes is demonstrated. The modelocking rates can be readily scaled up into the terahertz domain and enable applications in terahertz imaging, medicine, ultrafast optical links, and atmospheric sensing

Terahertz Frequency Mode-Locking of Monolithic Compound-Cavity Laser Diodes Incorporating Photonic-Bandgap Reflectors

Semiconductor lasers are modelocked at a harmonic of the round-trip frequency with pulse repetition rates up to 2.1 THz. The devices incorporate a monolithic compound cavity with a photonic-bandgap reflector. Possible applications include local oscillators and optical clocks

The application of the selective intermixing in selected area (SISA) technique to the fabrication of photonic devices in GaAs/AlGaAs structures

We demonstrate the fabrication of multiple wavelength lasers, and multi-channel wavelength division multiplexers using the one-step 'selective intermixing in selected area' quantum well intermixing technique in GaAs/AlGaAs structures. This technique is based on impurity-free vacancy diffusion and enables one to control the degree of intermixing across a wafer. Lasers with the bandgaps tuned to five different positions have been fabricated on a single chip. These lasers showed only small variations in transparency current, internal quantum efficiency and internal propagation loss, which indicates that the quality of the material remains good after being intel mixed. Four-channel wavelength demultiplexers or waveguide photodetectors have also been fabricated. Photocurrent and spontaneous emission spectra from individual diodes showed the shift of the absorption edge by different degrees due to the selective degree of quantum well intermixing. The results obtained also demonstrate the use of this technique in the fabrication of broad wavelength emission superluminescent diodes

Modulation of the second-order nonlinear tensor components in multiple-quantum-well structures

In this paper, we present experimental results which demonstrate that quantum-well intermixing techniques can be used to modulate the magnitude of the second-order nonlinear coefficient /spl chi//sup (2)/. Impurity-free vacancy disordering with SiO/sub 2/ and Ga/sub 2/O/sub 3/ caps was used to modulate the position of the band edge and hence, the magnitude of /spl chi//sub eff//sup (2)/. Using a coupled quantum-well structure we were able to demonstrate modulation of the d/sub 33/ tensor components associated with the asymmetric structure and of the d/sub 14/ component associated with the bulk crystal structure

Terahertz-Frequency Mode-Locking of Monolithic Compound-Cavity Laser Diodes

We present harmonic modelocked operation of a novel design of monolithic compound-cavity semiconductor laser. Modelocking is achieved at a harmonic of the fundamental round-trip frequency with pulse repetition rates from 131 GHz to 2.1 THz

Control of the second- and third-order nonlinearities in GaAs-AlGaAs multiple quantum wells

We report the use of impurity-free vacancy disordering techniques to control the nonlinear optical properties of GaAs–AlGaAs multiple quantum wells. These processes result in a shift in the position of the absorption edge to higher energy and have been used to modify the second- and third-order nonlinear coefficients. Working at photon energies just below the half bandgap we have observed a reduction of ∼ 50% in the value of nonlinear refractive coefficient n2 for a bandgap shift of around 40 nm. This change arises due to the combined effects of increasing the bandgap and increasing the detuning. The process can also result in a modulation in the magnitude of the second-order susceptibility χ(2) coefficient and provides a potential mechanism for realizing quasi-phase-matched structures

Quantum-well intermixing for the control of second-order nonlinear effects in AlGaAs multiple-quantum-well waveguides

We present experimental evidence to demonstrate the feasibility of a promising new quasi-phase-matching technique in AlGaAs multiple-quantum-well waveguides. Non-phase-matched second-harmonic-generation measurements indicate that, for sub-half-bandgap excitation near 1.5  µm, quantum-well intermixing by impurity-free vacancy disordering results in a reduction of the nonlinear susceptibility