An Explanation of Scientific nomenclature

Volume: XXI

Notes on the East African Miocene Primates

Volume: XVI

Tubular structures of GaS

In this Brief Report we demonstrate, using density-functional tight-binding theory, that gallium sulfide (GaS) tubular nanostructures are stable and energetically viable. The GaS-based nanotubes have a semiconducting direct gap which grows towards the value of two-dimensional hexagonal GaS sheet and is in contrast to carbon nanotubes largely independent of chirality. We further report on the mechanical properties of the GaS-based nanotubes

A pilot cluster randomised trial to assess the effect of a structured communication approach on quality of life in secure mental health settings: the Comquol study

Background There is a lack of research in forensic settings examining therapeutic relationships. A structured communication approach, placing patients’ perspectives at the heart of discussions about their care, was used to improve patients’ quality of life in secure settings. The objectives were to: • Establish the feasibility of the trial design • Determine the variability of the outcomes of interest • Estimate the costs of the intervention • If necessary, refine the intervention Methods A pilot cluster randomised controlled trial was conducted. Data was collected from July 2012 to January 2015 from participants in 6 medium secure in–patient services in London and Southern England. 55 patients and 47 nurses were in the intervention group with 57 patients and 45 nurses in the control group. The intervention comprised 6 nurse-patient meetings over a 6 month period. Patients rated their satisfaction with a range of domains followed by discussions on improving patient identified problems. Assessments took place at baseline, 6 months, and 12 months. Participants were not blind to their allocated group. The primary outcome was self-reported quality of life collected by a researcher blind to participants’ allocation status. Results The randomisation procedures and intervention approach functioned well. The measures used were understood by the participants and gave relevant outcome information. The response rates were good with low patient withdrawal rates. The quality of life estimated treatment effect was 0.2 (95% CI: -0.4 to 0.8) at 6 months and 0.4 (95% CI: -0.3 to 1.1) indicating the likely extreme boundaries of effect in the main trial. The estimated treatment effect of the primary outcome is clinically important, and a positive effect of the intervention is not ruled out. The estimate of the ICC for the primary outcome at 6 and 12 months was 0.04 (0.00 to 0.17) and 0.05 (0.00 to 0.18). The cost of the intervention was £529 per patient. Conclusions The trial design was viable as the basis for a full-scale trial. A full trial is justified to estimate the effect of the intervention with greater certainty. The variability of the outcomes could be used to calculate numbers needed for a full-scale trial. Ratings of need for therapeutic security may be useful in any future study

Helically corrugated waveguides for compression of frequency swept microwave pulses

Short pulse high power microwave radiation can be used for time of flight diagnostic measurements in plasmas, e.g. density profiles by reflectometry. A three-fold helical corrugation of the inner surface of a waveguide synthesises eigenwaves having useful dispersive properties by combining two distinct counter-rotating modes of a corresponding circular waveguide. The dispersion may be tailored to the requirements of an application by adjusting the amplitude and period of the corrugations. Such dispersive properties have proven useful in broadband radiation amplifiers, or to achieve passive compression of smoothly frequency modulated microwave pulses. The paper presents results of experiments using a solid state source to produce an optimised frequency-chirped input pulse and amplified by a high power Travelling Wave Tube Amplifier (TWTA). The waveforms of the input and output microwave signals were captured on a UHF Digital Storage Oscilloscope. The results demonstrated at 5.7kW input power levels that X-band radiation pulses of 67ns duration with 5% frequency modulation can be compressed into a 2.8ns pulse having 12 times higher peak power, whilst retaining 50% of the energy in the input signal. The technique offers great potential for scaling to higher frequencies and power levels

A high-power Ka-band free electron maser, defined by a 2D – 1D Bragg lasing cavity

One of the on-going research programs, at the University of Strathclyde, involves the development of high-power, pulsed, Free-Electron Masers (FEMs) with the lasing cavity defined using periodic corrugations on the drift-tube walls 1-4 . These corrugations form 1D and 2D Bragg resonators, whose reflection bands determine the dominant resonance of the maser 5 . Proper selection of the FEM undulator magnetic field strength, allows for efficient extraction of energy from a mildly relativistic (400 - 500 keV) electron beam at the resonant frequency of the lasing cavity, leading to monochromatic output at power levels of several tens of megawatts and pulse durations of ~150ns (determined primarily by the pulse duration of the driving power supply of ~250ns)

Finding apparent horizons and other two-surfaces of constant expansion

Apparent horizons are structures of spacelike hypersurfaces that can be determined locally in time. Closed surfaces of constant expansion (CE surfaces) are a generalisation of apparent horizons. I present an efficient method for locating CE surfaces. This method uses an explicit representation of the surface, allowing for arbitrary resolutions and, in principle, shapes. The CE surface equation is then solved as a nonlinear elliptic equation. It is reasonable to assume that CE surfaces foliate a spacelike hypersurface outside of some interior region, thus defining an invariant (but still slicing-dependent) radial coordinate. This can be used to determine gauge modes and to compare time evolutions with different gauge conditions. CE surfaces also provide an efficient way to find new apparent horizons as they appear e.g. in binary black hole simulations.Comment: 21 pages, 8 figures; two references adde

Thermal conductivity measurement of liquids in a microfluidic device

A new microfluidic-based approach to measuring liquid thermal conductivity is developed to address the requirement in many practical applications for measurements using small (microlitre) sample size and integration into a compact device. The approach also gives the possibility of high-throughput testing. A resistance heater and temperature sensor are incorporated into a glass microfluidic chip to allow transmission and detection of a planar thermal wave crossing a thin layer of the sample. The device is designed so that heat transfer is locally one-dimensional during a short initial time period. This allows the detected temperature transient to be separated into two distinct components: a short-time, purely one-dimensional part from which sample thermal conductivity can be determined and a remaining long-time part containing the effects of three-dimensionality and of the finite size of surrounding thermal reservoirs. Identification of the one-dimensional component yields a steady temperature difference from which sample thermal conductivity can be determined. Calibration is required to give correct representation of changing heater resistance, system layer thicknesses and solid material thermal conductivities with temperature. In this preliminary study, methanol/water mixtures are measured at atmospheric pressure over the temperature range 30–50°C. The results show that the device has produced a measurement accuracy of within 2.5% over the range of thermal conductivity and temperature of the tests. A relation between measurement uncertainty and the geometric and thermal properties of the system is derived and this is used to identify ways that error could be further reduced