Work relations for a system governed by Tsallis statistics

We derive analogues of the Jarzynski equality and Crooks relation to characterise the nonequilibrium work associated with changes in the spring constant of an overdamped oscillator in a quadratically varying spatial temperature profile. The stationary state of such an oscillator is described by Tsallis statistics, and the work relations for certain processes may be expressed in terms of q-exponentials. We suggest that these identities might be a feature of nonequilibrium processes in circumstances where Tsallis distributions are found

Deposition of organic thin films by plasma and photochemical techniques

The work detailed in this thesis concerns organic thin films synthesised either using R.F. inductively coupled plasmas excited in unsaturated monomers containing either fluorine or a nitrile group, or else irradiating the said monomers in vacuo using ultraviolet light. The effect of the following parameters on the composition and structure of the resultant films was determined using ESCA/XPS : a) power input to the R.F. plasma system, b) photon flux during UV irradiation, c) monomer type (including structural isomerism), and d) monomer flow rate. Relative system deposition rates were rationalised in terms of Yasuda's parameter, W/FM, which was found to hold true qualitatively, if not quantitatively. Introduction of halogen vapour to the plasma system in the presence of nitrile monomers physically decreased the glow volume. Analysis by ESCA and UV absorption spectroscopy revealed the presence of ionic halogen species in the resultant films. An overall decrease in deposition rate of the system was also observed. A similar result for the latter was seen for UV irradiation in the presence of iodine. The results were rationalised by assigning a free radical mechanism for both plasma and photochemical film deposition which is inhibited by halogens. Films formed by irradiation at &gt;200 nm were found to have differing chemical compositions compared to those obtained in the vacuum ultraviolet (<200 nm). This result was attributed to the differing photochemistries occurring in the two wavelength regions. Reference to the gas-phase photochemical literature enabled identification of the likely intermediates and term states involved, including 1,1 and 1,2 molecular elimination from ethylenic monomers in the vacuum UV to give the respective ethynes, together with secondary photolysis products. Consequently a mechanism for surface photopolymerisation was outlined which was compared with that proposed for plasma polymerisation, both of which involve vibrationally excited ground states for the monomers studied

Case Report: Successful Staged Ureteroscopic Treatment of a 5 cm Staghorn Renal Calculus

It is widely accepted that percutaneous nephrostolithotorny (PCNL) is the standard of choice for the removal of large staghorn renal calculi. Although data exists supporting a stagad ureteroscopic as an alternate treatment for stones up to 3 cm in select patients, little data exists to support a ureteroscopic approach for stones as large as 5 cm. We present a case of a 68 year old female with a 5 cm staghorn renal calculus managed successfully with a staged ureteroscopic approach. A staged ureteroscopic approach can be effective in treating stones as large as 5 cm

Layered BiOI single crystals capable of detecting low dose rates of X-rays

Detecting low dose rates of X-rays is critical for making safer radiology instruments, but is limited by the absorber materials available. Here, we develop bismuth oxyiodide (BiOI) single crystals into effective X-ray detectors. BiOI features complex lattice dynamics, owing to the ionic character of the lattice and weak van der Waals interactions between layers. Through use of ultrafast spectroscopy, first-principles computations and detailed optical and structural characterisation, we show that photoexcited charge-carriers in BiOI couple to intralayer breathing phonon modes, forming large polarons, thus enabling longer drift lengths for the photoexcited carriers than would be expected if self-trapping occurred. This, combined with the low and stable dark currents and high linear X-ray attenuation coefficients, leads to strong detector performance. High sensitivities reaching 1.1  × 103 μC Gyair−1 cm−2 are achieved, and the lowest dose rate directly measured by the detectors was 22 nGyair s−1. The photophysical principles discussed herein offer new design avenues for novel materials with heavy elements and low-dimensional electronic structures for (opto)electronic applications

Health and wellbeing impacts of housing converted from non-residential buildings: a mixed-methods exploratory study in London, UK

Housing quality is a determinant of health, wellbeing and inequities. Since 2013, changes to Permitted Development Rights (PDR) allow conversions of non-residential buildings into housing without planning permission in England. We explored the potential health and wellbeing impacts of such ‘PDR housing’ through an online survey and semi-structured interviews in four London boroughs. We found an association between low wellbeing and lack of residential space and accommodation cooling options, fewer local amenities and lower perceived safety. Participants highlighted problems with windows and outdoor space. Poor quality PDR conversions may pose health and wellbeing risks that could be avoided through regulation and enforcement

Molecular evolutionary consequences of island colonization

Island endemics are expected to have low effective population sizes (Ne), first because some may experience population bottlenecks when they are founded, and second because they have restricted ranges. Therefore, we expect island species to have reduced genetic diversity, inefficient selection, and reduced adaptive potential compared with their mainland counterparts. We used both polymor- phism and substitution data to address these predictions, improving on the approach of recent studies that only used substitution data. This allowed us to directly test the assumption that island species have small values of Ne. We found that island species had significantly less genetic diversity than mainland species; however, this pattern could be attributed to a subset of island species that appeared to have undergone a recent population bottleneck. When these species were excluded from the analysis, island and mainland species had similar levels of genetic diversity, despite island species occupying considerably smaller areas than their mainland counterparts. We also found no overall difference between island and mainland species in terms of the effectiveness of selection or the mutation rate. Our evidence suggests that island colonization has no lasting impact on molecular evolution. This surprising result highlights gaps in our knowledge of the relationship between census and effective population size