The Mode and Timing of Microplate Docking along the Highland Boundary Fault Zone, Scotland

The Highland Boundary Fault Zone is a major crustal fracture with a long and complex structural history, in which brittle deformation was superimposed upon pre-existing fabrics produced by ductile deformation. This thesis describes and interprets the history of HBFZ tectonism, presented in reverse chronological order (youngest events first). Although the HBFZ still experiences small-scale earthquakes, there is evidence to show that significant fault displacement has not occurred since the end of the Carboniferous. Extensional deformation during the Upper Devonian and the Carboniferous was small-scale and localised. Upper crustal deformation in mid-Devonian times, possibly caused by the accretion of the Avalonian terrane with Laurentia, was low in magnitude but widespread in aerial extent. The results and interpretations of a mesofracture analysis are presented to help constrain mid-Devonian brittle deformation across central Scotland. The results show that regional north-south compression caused transpressional reactivation of the pre-existing HBFZ. Because our existing understanding of transpression is incapable of explaining the results of the mesofracture analysis, an alternative transpression model is proposed, in which transpressive strain is "partitioned" into two components; a strike-slip component restricted to the fault zone, and a thrust component deforming the rocks that flank the zone. The "strain-partitioning" model, with some elaboration, helps to explain the mid-Devonian deformation seen in central Scotland. The balance of evidence from the Highland Border, Dalradian, and Midland Valley terranes suggests that ductile deformation along the HBFZ occurred in response to terrane accretion, which probably took place in Ordovician times. A palaeo-tectonic model is presented in which Highland Border and Midland Valley terranes were accreted and laterally displaced, with a sinistrally transpressive sense, onto the Laurentian margin in the Llandeilo and/or Caradoc, and again in the Ashgill and/or Llandovery. The extreme difficulties of postulating the palaeo-tectonic histories of disrupted terranes are discussed in detail

High-density correlation energy expansion of the one-dimensional uniform electron gas

We show that the expression of the high-density (i.e small-$r_s$) correlation energy per electron for the one-dimensional uniform electron gas can be obtained by conventional perturbation theory and is of the form \Ec(r_s) = -\pi^2/360 + 0.00845 r_s + ..., where $r_s$ is the average radius of an electron. Combining these new results with the low-density correlation energy expansion, we propose a local-density approximation correlation functional, which deviates by a maximum of 0.1 millihartree compared to the benchmark DMC calculations.Comment: 7 pages, 2 figures, 3 tables, accepted for publication in J. Chem. Phy

Energy Gaps in a Spacetime Crystal

This paper presents an analysis of the band structure of a spacetime potential lattice created by a standing electromagnetic wave. We show that there are energy band gaps. We estimate the effect, and propose a measurement that could confirm the existence of such phenomena.Comment: 8 pages. 2 figure

Optical BCS conductivity at imaginary frequencies and dispersion energies of superconductors

We present an efficient expression for the analytic continuation to arbitrary complex frequencies of the complex optical and AC conductivity of a homogeneous superconductor with arbitrary mean free path. Knowledge of this quantity is fundamental in the calculation of thermodynamic potentials and dispersion energies involving type-I superconducting bodies. When considered for imaginary frequencies, our formula evaluates faster than previous schemes involving Kramers--Kronig transforms. A number of applications illustrates its efficiency: a simplified low-frequency expansion of the conductivity, the electromagnetic bulk self-energy due to longitudinal plasma oscillations, and the Casimir free energy of a superconducting cavity.Comment: 20 pages, 7 figures, calculation of Casimir energy adde

Long-range/short-range separation of the electron-electron interaction in density functional theory

By splitting the Coulomb interaction into long-range and short-range components, we decompose the energy of a quantum electronic system into long-range and short-range contributions. We show that the long-range part of the energy can be efficiently calculated by traditional wave function methods, while the short-range part can be handled by a density functional. The analysis of this functional with respect to the range of the associated interaction reveals that, in the limit of a very short-range interaction, the short-range exchange-correlation energy can be expressed as a simple local functional of the on-top pair density and its first derivatives. This provides an explanation for the accuracy of the local density approximation (LDA) for the short-range functional. Moreover, this analysis leads also to new simple approximations for the short-range exchange and correlation energies improving the LDA.Comment: 18 pages, 14 figures, to be published in Phys. Rev.

Long‐Term Retinal Differentiation of Human Induced Pluripotent Stem Cells in a Continuously Perfused Microfluidic Culture Device

Understanding how microenvironmental cues influence cellular behavior will enable development of efficient and robust pluripotent stem cell differentiation protocols. Unlike traditional cell culture dishes, microfluidic bioreactors can provide stable microenvironmental conditions by continuous medium perfusion at a controlled rate. The aim of this study is to investigate whether a microfluidic culture device could be used as a perfused platform for long‐term cell culture processes such as the retinal differentiation of human induced pluripotent stem cells. The perfusion flow rate is established based on the degradation and consumption of growth factors (DKK‐1, Noggin, IGF‐1, and bFGF) and utilizing the Péclet number. The device's performance analyzed by qRT‐PCR show improvements compared to the well‐plate control as characterized by significantly higher expression of the markers Pax6, Chx10, and Crx on Day 5, Nrl on day 10, Crx, and Rhodopsin on day 21. Optimization of perfusion rate is an important operating variable in development of robust processes for differentiation cultures. Result demonstrates convective delivery of nutrients via perfusion has a significant impact upon the expression of key retinal markers. This study is the first continuously perfused long‐term (21 days) retinal differentiation of hiPSCs in a microfluidic device

Transfection in perfused microfluidic cell culture devices: a case study

Automated microfluidic devices are a promising route towards a point-of-care autologous cell therapy. The initial steps of induced pluripotent stem cell (iPSC) derivation involve transfection and long term cell culture. Integration of these steps would help reduce the cost and footprint of micro-scale devices with applications in cell reprogramming or gene correction. Current examples of transfection integration focus on maximising efficiency rather than viable long-term culture. Here we look for whole process compatibility by integrating automated transfection with a perfused microfluidic device designed for homogeneous culture conditions. The injection process was characterised using fluorescein to establish a LabVIEW-based routine for user-defined automation. Proof-of-concept is demonstrated by chemically transfecting a GFP plasmid into mouse embryonic stem cells (mESCs). Cells transfected in the device showed an improvement in efficiency (34%, n = 3) compared with standard protocols (17.2%, n = 3). This represents a first step towards microfluidic processing systems for cell reprogramming or gene therapy

Tracking the Real-Time Evolution of a Writing Event: Second Language Writers at Different Proficiency Levels

The current study focused on emergent processes during real-time second language (L2) writing activity in an English as a foreign language university context, examining differences in these processes across individual capacities. Participants included 22 adult Japanese learners of L2 English and their tutor. The data were collected using digital screen capture and eye-tracking technologies while the learners wrote a 35-minute argumentative essay. Supplementary stimulated retrospective recalls were also conducted to document the learners’ and the tutor’s reflections on the writing event. Results revealed clear differences in L2 writing activity at different periods in time as well as differences in cognitive activity which appear to be mediated by L2 proficiency. Importantly, the obtained patterns differed depending on whether duration or frequency data were considered. These findings thus demonstrate the need to broaden the study of the temporal dimension of L2 writing and to consider more nuanced mixed-methods approaches in future work

UK: racial violence and the night-time economy

This article examines fifty-five racist attacks over a six-month period in the UK’s night-time economy, showing the risks faced by members of the public and workers at taxi firms, takeaways, convenience stores and service stations. It argues that flexible and highly casualised labour conditions exacerbate the risk of racial violence