Studies in alkaloid biosynthesis

Imperial Users onl

THERMAL POST-FABRICATION PROCESSING OF Y2O3:Tm CERAMIC SCINTILLATORS

The effects of thermal post-fabrication processing in O2 flux on the luminescence and scintillation of Y2O3:Tm transparent ceramics were investigated. The material\u27s microstructure, optical properties, and scintillation properties were characterized using X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy, thermoluminescence measurements, differential pulse height distribution measurements, Archimedes density measurements, photoluminescence measurements, and ultra violet-visible transmission measurements. The processing is effective if performed in the time frame of 60-120mins at 1050°C under oxygen flow. After the first hour of processing, about 40% enhancement in the luminescence output together with about 20% enhancement in the scintillation light yield were observed. The enhancements were tentatively assigned to the incorporation of oxygen into vacancy sites. Longer cumulative processing times lead to the incorporation of oxygen as interstitials that is detrimental to scintillation light yield but not to luminescence output. This work also revealed that thermoluminescence measurements are a useful tool to predict scintillation light yield of Y2O3:Tm

Adaptive gait changes due to spectacle magnification and dioptric blur in older people

YesPurpose. A recent study suggested that updated spectacles could increase falls rate in older people. We hypothesized that this may be due to changes in spectacle magnification and this study assessed the effects of spectacle magnification on adaptive gait. Methods. Adaptive gait and visual function was measured in 10 older adults (mean age 77.1 ¿ 4.3 years) with the participants¿ optimal refractive correction and when blurred with +1.00DS, +2.00DS, -1.00DS and -2.00DS lenses. Adaptive gait measurements for the lead and trail foot included foot position before the step, toe clearance of the step edge and foot position on the step. Vision measurements included visual acuity, contrast sensitivity and stereoacuity. Results. The blur lenses led to equal decrements in visual acuity and stereoacuity for the +1.00DS and -1.00DS and the +2.00DS and -2.00DS lenses. However, they had very different effects on adaptive gait compared to the optimal correction: Positive blur lenses led to an increased distance of the feet from the step, increased vertical toe clearance and reduced distance of the lead heel position on the step. Negative lenses led to the opposite of these changes. Conclusion. The adaptive gait changes did not mirror the effects of blur on vision, but were driven by the magnification changes of the lenses. Steps appear closer and larger with positive lenses and further away and smaller with negative ones. Magnification likely explains the mobility problems some older adults have with updated spectacles and after cataract surgery.Federation of Ophthalmic and Dispensing Optician

Data for Elimination of visceral leishmaniasis in the Indian subcontinent: a comparison of predictions from three transmission models: Warwick model description and parameter uncertainty analysis

We present three transmission models of visceral leishmaniasis (VL) in the Indian subcontinent (ISC) with structural differences regarding the disease stage that provides the main contribution to transmission, including models with a prominent role of asymptomatic infection, and fit them to recent case data from 8 endemic districts in Bihar, India. Following a geographical cross-validation of the models, we compare their predictions for achieving the WHO VL elimination targets with ongoing treatment and vector control strategies. All the transmission models suggest that the WHO elimination target (<1 new VL case per 10,000 capita per year at sub-district level) is likely to be met in Bihar, India, before or close to 2020 in sub-districts with a pre-control incidence of 10 VL cases per 10,000 people per year or less, when current intervention levels (60% coverage of indoor residual spraying (IRS) of insecticide and a delay of 40 days from onset of symptoms to treatment (OT)) are maintained, given the accuracy and generalizability of the existing data regarding incidence and IRS coverage. In settings with a pre-control endemicity level of 5/10,000, increasing the effective IRS coverage from 60 to 80% is predicted to lead to elimination of VL 1–3 years earlier (depending on the particular model), and decreasing OT from 40 to 20 days to bring elimination forward by approximately 1 year. However, in all instances the models suggest that L. donovani transmission will continue after 2020 and thus that surveillance and control measures need to remain in place until the longer-term aim of breaking transmission is achieved

Leadership styles used by senior medical leaders : patterns, influences and implications for leadership development

Purpose: Clinician leadership is important in healthcare delivery and service development. The use of different leadership styles in different contexts can influence individual and organisational effectiveness. The purpose of this study was to determine the predominant leadership styles used by medical leaders and factors influencing leadership style use. Design: A mixed methods approach was used, combining a questionnaire distributed electronically to 224 medical leaders in acute hospital trusts with in depth ‘critical incident’ interviews with six medical leaders. Questionnaire responses were analysed quantitatively to determine firstly the overall frequency of use of six predefined leadership styles, and secondly, individual leadership style based on a consultative/decision-making paradigm. Interviews were analysed thematically using both a confirmatory approach with predefined leadership styles as themes; and also an inductive grounded theory approach exploring influencing factors. Findings: Leaders used a range of styles, the predominant styles being democratic, affiliative and authoritative. Although leaders varied in their decision-making authority and consultative tendency, virtually all leaders showed evidence of active leadership. Organisational culture, context, individual propensity and ‘style history’ emerged during the inductive analysis as important factors in determining use of leadership styles by medical leaders. Implications: The outcomes of this evaluation are useful for leadership development at the level of the individual, organisation and wider NHS. Originality/value: This study adds to the very limited evidence base on patterns of leadership style use in medical leadership and reports a novel conceptual framework of factors influencing leadership style use by medical leaders.</p

Rapid determination of LISA sensitivity to extreme mass ratio inspirals with machine learning

Gravitational wave observations of the inspiral of stellar-mass compact objects into massive black holes (MBHs), extreme mass ratio inspirals (EMRIs), enable precision measurements of parameters such as the MBH mass and spin. The Laser Interferometer Space Antenna is expected to detect sufficient EMRIs to probe the underlying source population, testing theories of the formation and evolution of MBHs and their environments. Population studies are subject to selection effects that vary across the EMRI parameter space, which bias inference results if unaccounted for. This bias can be corrected, but evaluating the detectability of many EMRI signals is computationally expensive. We mitigate this cost by (i) constructing a rapid and accurate neural network interpolator capable of predicting the signal-to-noise ratio of an EMRI from its parameters, and (ii) further accelerating detectability estimation with a neural network that learns the selection function, leveraging our first neural network for data generation. The resulting framework rapidly estimates the selection function, enabling a full treatment of EMRI detectability in population inference analyses. We apply our method to an astrophysically motivated EMRI population model, demonstrating the potential selection biases and subsequently correcting for them. Accounting for selection effects, we predict that LISA will measure the MBH mass function slope to a precision of 8.8%, the CO mass function slope to a precision of 4.6%, the width of the MBH spin magnitude distribution to a precision of 10% and the event rate to a precision of 12% with EMRIs at redshifts below z=6.Comment: 12 pages, 4 figure