Colloidal templating at a cholesteric - oil interface: Assembly guided by an array of disclination lines

We simulate colloids (radius $R \sim 1\mu$m) trapped at the interface between a cholesteric liquid crystal and an immiscible oil, at which the helical order (pitch p) in the bulk conflicts with the orientation induced at the interface, stabilizing an ordered array of disclinations. For weak anchoring strength W of the director field at the colloidal surface, this creates a template, favoring particle positions eitheron top of or midway between defect lines, depending on $\alpha = R/p$. For small $\alpha$, optical microscopy experiments confirm this picture, but for larger $\alpha$ no templating is seen. This may stem from the emergence at moderate W of a rugged energy landscape associated with defect reconnections.Comment: 5 pages, 4 figure

The integrated database for African policymakers

The Integrated Database for African Policymakers (IDAPs; http://www.walker.ac.uk/projects/idaps-integrated-database-for-african-policy-makers/), is a technological initiative to intended to provide valuable insight and quantitative evidence to policy makers, planners and doers, at international, national and local levels to inform scenario planning and support investment interventions for early action and adaptation. It also provides a rich source of data for researchers exploring the impacts of climate change in rural African communities, and potentially beyond. IDAPS is jointly led by the Walker Institute and Evidence for Development, our embedded NGO partner

The impact of grassland management regime on the community structure of selected bacterial groups in soils

The impact of long-term grassland management regimes on microbial community structure in soils was assessed using multivariate analysis of polymerase chain reaction^denaturing gradient gel electrophoresis (PCR^DGGE) banding patterns of selected bacterial groups and PLFA (phospholipid fatty acid) profiling. The management regimes assessed were inorganic nitrogen (N) fertiliser application and soil drainage. PCR^DGGE profiles of the eubacteria, actinomycetes, ammonia oxidisers and pseudomonads were assessed by principal co-ordinate analysis of similarity indices which were generated from binary data using both Dice and Jaccard coefficients. The analysis of binary DGGE data revealed significant impacts of N fertiliser on the eubacterial and actinomycete community structure using the Jaccard coefficient, whilst N fertiliser had a significant impact on the actinomycete community structure only when using similarity indices generated from the Dice coefficient. Soil drainage had a significant impact on the community structures of the actinomycetes and the pseudomonads using both Dice and Jaccard derived similarity indices. Multivariate analysis of principal components derived from PLFA profiling revealed that N fertiliser had a significant impact on the microbial community structure. Although drainage alone was not a significant factor in discriminating between PLFA community profiles of the different treatments, there was a significant interaction with N fertiliser. Analysis of principal component analysis (PCA) loadings revealed that PLFAs i15:0 and i17:0 were partly responsible for the clustering away of the undrained^N fertilised treatment. Although soil management regime influenced some background soil data, correlation analysis using PC1 from PLFA data revealed no significant relationship with soil organic matter, pH, total C and total N

Effect of fatigue loading on structure and functional behaviour of fascicles from energy-storing tendons

Tendons can broadly be categorized according to their function: those that act purely to position the limb and those that have an additional function as energy stores. Energy-storing tendons undergo many cycles of large deformations during locomotion, and so must be able to extend and recoil efficiently, rapidly and repeatedly. Our previous work has shown rotation in response to applied strain in fascicles from energy-storing tendons, indicating the presence of helical substructures which may provide greater elasticity and recovery. In the current study, we assessed how preconditioning and fatigue loading affect the ability of fascicles from the energy-storing equine superficial digital flexor tendon to extend and recoil. We hypothesized that preconditioned samples would exhibit changes in microstructural strain response, but would retain their ability to recover. We further hypothesized that fatigue loading would result in sample damage, causing further alterations in extension mechanisms and a significant reduction in sample recovery. The results broadly support these hypotheses: preconditioned samples showed some alterations in microstructural strain response, but were able to recover following the removal of load. However, fatigue loaded samples showed visual evidence of damage and exhibited further alterations in extension mechanisms, characterized by decreased rotation in response to applied strain. This was accompanied by increased hysteresis and decreased recovery. These results suggest that fatigue loading results in a compromised helix substructure, reducing the ability of energy-storing tendons to recoil. A decreased ability to recoil may lead to an impaired response to further loading, potentially increasing the likelihood of injury

The Gaussian Plasma Lens in Astrophysics. Refraction

We consider the geometrical optics for refraction of a distant radio source by an interstellar plasma lens, with application to a lens with a Gaussian electron column density profile. The refractive properties of the lens are specified completely by a dimensionless parameter, alpha, which is a function of the wavelength of observation, the lens' electron column density, the lens-observer distance, and the transverse diameter of the lens. Relative motion of the observer and lens produces modulations in the source's light curve. Plasma lenses are diverging so the light curve displays a minimum, when the lens is on-axis, surrounded by enhancements above the unlensed flux density. Lensing can also produce caustics, multiple imaging, and angular position wander of the background source. If caustics are formed, the separation of the outer caustics can constrain alpha, while the separation of the inner caustics can constrain the size of the lens. We apply our analysis to 0954+654, a source for which we can identify caustics in its light curve, and 1741-038, for which polarization observations were obtained during and after the scattering event. We find general agreement between modelled and observed light curves at 2.25 GHz, but poor agreement at 8.1 GHz. The discrepancies may result from a combination of lens substructure or anisotropic shape, a lens that only grazes the source, or unresolved source substructure. Our analysis places the following constraints on the lenses: Toward 0954+654 (1741-038) the lens was 0.38 AU (0.065 AU) in diameter, with a peak column density of 0.24 pc cm^{-3} (1E-4 pc cm^{-3}) and an electron density of 1E5 cm^{-3} (300 cm^{-3}). The angular wander caused by the lens was 250 mas (0.4 mas) at 2.25 GHz. For 1741-038, we place an upper limit of 100 mG on the lens' magnetic field.Comment: 26 pages, LaTeX2e using AASTeX macro aaspp4, 11 PostScript figures; to be published in Ap

Effects of Thermal Shock on Mechanical Behaviour of Kevlar Fibre Composites

The development of composite technology represents one of the most significant advances in materials science since 1940s. The major advantages of composite materials are their high strength and stiffness, light weight, corrosion resistance, crack and fatigue resistance and design flexibility as compared to metallic materials. Because of the attractive properties. the use of composite materials has been increasing steadily in recent years. Unfortunately, there are disadvantages in composite materials as compared with metals. They include brittleness, vulnerability to stress concentration, inflexibility for localised multidirectional stresses, sensitivity to environmental effects, and poor damage tolerance to impact. These factors must be critically considered in designing a composite system. The aramid keviar family of fibres have been accepted as reinforcement for composites and finds wider and newer applications in various industrial and aerospace sectors. The interfacial bond strength between aramid fibres and epoxy resins is normally lower than what is experienced with carbon fibre composites. This weakness with kevlar necessitates investigation and evaluation of the interlaminar shear strength (ILSS) and modulus under some realistic environmental conditions. The present work has been taken up to evaluate the variation of ILS S and modulus values after being given the extreme thermal shock of 160°C thermal gradient. The thermal shock is given in two separate ways, firstly, one series of kevlar/ epoxy and kevlar/polyester short beam shear (SBS) specimens are kept in a oven at 80°C for different time intervals and then immersed in a liquid bath at -80`'C temperature. The other experiment is done in reverse way i.e. first kept at -80°C and then exposed to 80°C temperature. The interesting variations of ELSS and modulus values have generated some ideas for assessment in this area. The thermal shock, positive temperature and cryogenic temperature affect the kevlar/epoxy and kevlar/polyester composites in a very complex way. The wide fluctuation in results necessitates further investigation and depth analysis of this interaction, It may be hypothesised that the extreme thermal shock may introduce some decohesion between fibre/matrix interface especially when the gradient is positive in thermal shock

The Addition and Cessation of Inorganic Fertiliser Amendments in Long-Term Managed Grasslands: Impacts on Above and Below-Ground Communities

In recent times, land use in the United Kingdom has undergone considerable changes because of social and economic pressures, leading to a fine balance between the demands of highly productive intensive systems and practices which are perceived to be more environmentally acceptable. Plant productivity is governed by the supply of nutrients from the soil, which in turn is dependent on the dynamics of organic matter decomposition driven by soil micro-, meso- and macro fauna. Considerable information is available concerning the impact of inorganic fertiliser additions on communities of macro-fauna and flora, but the effects on specific microbial communities in soils are less clear. The effects of withholding inorganic nitrogen (N) are much less studied. The present study investigated the impact on plant and soil communities of either adding or withholding N from long-term managed plots

A New Look At Carbon Abundances In Planetary Nebulae. III. DDDM1, IC 3568, IC4593, NGC 6210, NGC 6720, NGC 6826, & NGC 7009

This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database containing consistently-reduced spectra to measure line strengths of C III] 1909 along with numerous other UV lines for the planetary nebulae DDDM1, IC 3568, IC 4593, NGC 6210, NGC 6720, NGC 6826, & NGC 7009. We combine the IUE data with line strengths from optical spectra obtained specifically to match the IUE slit positions as closely as possible, to determine values for the abundance ratios He/H, O/H, C/O, N/O, and Ne/O. The ratio of C III] 1909/C II 4267 is found to be effective for merging UV and optical spectra when He II 1640/4686 is unavailable. Our abundance determination method includes a 5-level program whose results are fine-tuned by corrections derived from detailed photoionization models constrained by the same set of emission lines. All objects appear to have subsolar levels of O/H, and all but one show N/O levels above solar. In addition, the seven planetary nebulae span a broad range in C/O values. We infer that many of our objects are matter bounded, and thus the standard ionization correction factor for N/O may be inappropriate for these PNe. Finally, we estimate C/O using both collisionally-excited and recombination lines associated with C+2 and find the well established result that abundances from recombination lines usually exceed those from collisionally-excited lines by several times.Comment: 36 pages, 7 tables, 2 figures, latex. Tables and figures supplied as two separate postscript files. Accepted for publication in Ap

Reflecting on the experiential journey: Creating, developing and understanding leadership in Equality, Diversity and Inclusion within a Faculty

London South Bank University (LSBU) appointed equality, diversity and inclusion (EDI) leads in each of its Schools in 2021/22. The leaders’ remit was to deliver and embed LSBU’s EDI strategy cognisant of the uniqueness of the Schools. LSBU’s pioneering EDI strategy has been recognised as a symbol of excellence and shortlisted for two national EDI awards. The composition of LSBU’s academic senior management does not yet fully reflect the intersectional diversity of the organisation. Therefore, this session aims to share the experience of LSBU’s EDI leads and facilitate discussion about the benchmarks for achieving leadership in EDI within a School