Pottery in the computer age

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Dispersive diffusion controlled distance dependent recombination in amorphous semiconductors

The photoluminescence in amorphous semiconductors decays according to power law $t^{-delta}$ at long times. The photoluminescence is controlled by dispersive transport of electrons. The latter is usually characterized by the power $alpha$ of the transient current observed in the time-of-flight experiments. Geminate recombination occurs by radiative tunneling which has a distance dependence. In this paper, we formulate ways to calculate reaction rates and survival probabilities in the case carriers execute dispersive diffusion with long-range reactivity. The method is applied to obtain tunneling recombination rates under dispersive diffusion. The theoretical condition of observing the relation $delta = alpha/2 + 1$ is obtained and theoretical recombination rates are compared to the kinetics of observed photoluminescence decay in the whole time range measured.Comment: To appear in Journal of Chemical Physic

Reluctance of general practice staff to register patients without documentation: a qualitative study in North East London.

BACKGROUND: Lack of access to documentation is a key barrier to GP registration, despite NHS England guidance stating that documents are not required. Staff attitudes and practice regarding registration of those without documentation are under- researched. AIM: To understand the processes through which registration might be refused for those without documents, and the factors operating to influence this. DESIGN AND SETTING: Qualitative study conducted in general practice across three clinical commissioning groups in North East London. METHOD: In total, 33 participants (GP staff involved in registering new patients) were recruited through email invitation. Semi-structured interviews and focus groups were conducted. Data were analysed using Braun and Clarke's reflexive thematic analysis. Two social theories informed this analysis: Lipsky's street-level bureaucracy and Bourdieu's theory of practice. RESULTS: Despite good knowledge of guidance, most participants expressed reluctance to register those without documentation, often introducing additional hurdles or requirements in their everyday practice. Two explanatory themes were generated: that those without documents were perceived as burdensome, and/or that moral judgements were made about their deservedness to finite resources. Participants described a context of high workload and insufficient funding. Some felt that GP services should be restricted by immigration status, as is widespread in secondary care. CONCLUSION: Improving inclusive registration practice requires addressing staff concerns, supporting navigation of high workloads, tackling financial disincentives to registering transient groups, and challenging narratives that undocumented migrants represent a 'threat' to NHS resources. Furthermore, it is imperative to acknowledge and address upstream drivers, in this instance the Hostile Environment

Exactly solvable model of a quantum spin glass

A mean field spherical model with random couplings between pairs, quartets, and possibly higher multiplets of spins is considered. It has the same critical behavior as the Sherrington-Kirkpatrick model. It thus exhibits replica symmetry breaking. The order parameter function is solved exactly in the whole low temperature phase. The zero field cooled susceptibility remains finite at low $T$. Next a quantum version of the system is considered. Whereas the magnetic properties are not altered qualitatively, the thermodynamics is now regular at small temperatures.Comment: 4 pages postscript. Revised version, to appear in Phys. Rev. Let

Thermo-oxidative Stability and Flammability of Three-dimensional Polymers Based on Olygocarbonate-methacrylates

By the irreversible condensation reaction of the mono-methacrylic ester of ethylene glycol and chlorocarbonic esters of 2,2-dimethylpropandiol- 1,3 and 2,2-dimethylene chloride-propandiol-1,3, two olygocarbonate methacrylate (OCM-I and -II, respectively) containing unsaturated ends were synthesised. The polymerization of OCM-I and OCM-II in the presence of cumene hydro.peroxide and an accelerator gave two cross-liinked polymers Ln a yield of 70-750/o. The thermal and thermo-oxidative decompositions of the prepared polymers were studied by the thermogravimetric method and by characterization of the volatile pyrolysis products and the nonvolatile polymer residue. The influence of the polymer structure on the mechanism of the decomposition reactions in vacuo as well as iin the presence of oxygen was discussed. The temperature dependence of thermostabiLity was compared with some polymer flammability parameters

Analytic Behaviour of Competition among Three Species

We analyse the classical model of competition between three species studied by May and Leonard ({\it SIAM J Appl Math} \textbf{29} (1975) 243-256) with the approaches of singularity analysis and symmetry analysis to identify values of the parameters for which the system is integrable. We observe some striking relations between critical values arising from the approach of dynamical systems and the singularity and symmetry analyses.Comment: 14 pages, to appear in Journal of Nonlinear Mathematical Physic