BiFeO3/La0.7Sr0.3MnO3 heterostructures deposited on Spark Plasma Sintered LaAlO3 Substrates

Multiferroic BiFeO3 (BFO) / La0.7Sr0.3MnO3 heterostructured thin films were grown by pulsed laser deposition on polished spark plasma sintered LaAlO3 (LAO) polycrystalline substrates. Both polycrystalline LAO substrates and BFO films were locally characterized using electron backscattering diffraction (EBSD), which confirmed the high-quality local epitaxial growth on each substrate grain. Piezoforce microscopy was used to image and switch the piezo-domains, and the results are consistent with the relative orientation of the ferroelectric variants with the surface normal. This high-throughput synthesis process opens the routes towards wide survey of electronic properties as a function of crystalline orientation in complex oxide thin film synthesis.Comment: 10 pages, 4 figures, Submitted to Applied Physics Letter

In-plane electronic anisotropy in underdoped Ba(Fe1−x_{1-x}Cox_x)2_2As2_2 revealed by detwinning in a magnetic field

We present results of angle-dependent magnetoresistance measurements and direct optical images of underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ which reveal partial detwinning by action of a 14T magnetic field. Driven by a substantial magneto-elastic coupling, this result provides evidence for an electronic origin of the lattice distortion in underdoped iron pnictides. The observed anisotropy in these partially detwinned samples implies a substantial in-plane electronic anisotropy in the broken symmetry state, with a smaller resistivity along the antiferromagnetic ordering direction.Comment: 5 pages, 5 figure

Novel Ground-State Crystals with Controlled Vacancy Concentrations: From Kagom\'{e} to Honeycomb to Stripes

We introduce a one-parameter family, $0 \leq H \leq 1$, of pair potential functions with a single relative energy minimum that stabilize a range of vacancy-riddled crystals as ground states. The "quintic potential" is a short-ranged, nonnegative pair potential with a single local minimum of height $H$ at unit distance and vanishes cubically at a distance of \rt. We have developed this potential to produce ground states with the symmetry of the triangular lattice while favoring the presence of vacancies. After an exhaustive search using various optimization and simulation methods, we believe that we have determined the ground states for all pressures, densities, and $0 \leq H \leq 1$. For specific areas below 3\rt/2, the ground states of the "quintic potential" include high-density and low-density triangular lattices, kagom\'{e} and honeycomb crystals, and stripes. We find that these ground states are mechanically stable but are difficult to self-assemble in computer simulations without defects. For specific areas above 3\rt/2, these systems have a ground-state phase diagram that corresponds to hard disks with radius \rt. For the special case of H=0, a broad range of ground states is available. Analysis of this case suggests that among many ground states, a high-density triangular lattice, low-density triangular lattice, and striped phases have the highest entropy for certain densities. The simplicity of this potential makes it an attractive candidate for experimental realization with application to the development of novel colloidal crystals or photonic materials.Comment: 25 pages, 11 figure

The Capacity of ICT to Transform Teaching and Learning: A Critical View from Within a Building Schools for the Future Project

Announced in 2003, Building Schools for the Future (BSF) was New Labour’s attempt to revolutionise secondary education in the UK, both in terms of infrastructure and pedagogy. The country’s school building stock was decades (and in some cases centuries) old and in poor repair, built for a different age with a history of lack of investment in modern technologies. BSF was to change all that with massive investment and plans to transform teaching and learning. The new buildings were to be of contemporary and revolutionary design more akin to modern office spaces than their Victorian predecessors. Each school project had £1,400 per pupil (approximately £1.4m) of its budget ‘ring fenced’ to be spent on Information Communication Technology (ICT), as this was to be a major transformational tool; the key to equipping students with the skills needed for a 21st Century economy. This Doctorate report is written from within one of the first BSF projects in the country, planned from 2005 and opened in 2007, with the ICT contract coming to an end in 2014. The author is the only surviving member of the original BSF planning team still working within the LA as a Deputy Head Teacher. The main research questions ‘To what extent and in what ways has the huge investment in ICT during BSF transformed teaching and learning and what was the perspective of this from the three main stakeholder groups; those leading, those teaching and those learning?’ sets out to investigate the impact of the ICT component of BSF, it does however also reflect on the BSF process as a whole because this set the context in which the ICT systems were deployed; through a Managed Service Provider (MSP) procured from the private sector. This contract cast a long shadow over the prospect of transformation as BSF became largely about procurement, contracts and cost, the ‘B’ prevailed; teaching and learning were marginalized. Another major influence was that the schools in BSF re-opened in the same educational climate of accountability, curriculum, timetables and assessment methodology as they had had in their old accommodation. Conflicting government policy streams only served to make this more evident. Teacher and pupils assimilated their new environments and continued as before. That is not to say the ICT did not have an impact; there were many positive outcomes ranging from a greatly reduced pupil to device ratios and multimedia lesson content readily available to all. Pupils in particular were delighted (initially at least) with their new environments. Communication and the sharing of ideas and resources were the result of modern networks and systems that meant efficiencies for some and up to date information for most. Overall, classroom teachers had little capacity to transform their professional lives with the ICT provision, and there was no real pressure for them to do so given the unchanged nature of the structures of education within which they worked. Although many saw the potential of the new ICT, the opportunities to improve their skills were frustratingly lacking or not suited to their needs, consequently most incorporated the ICT into their classroom practice at a level with which they were comfortable. The cancellation of BSF in 2011 was one of the first acts of the new coalition government, although the schools included in this work had a managed ICT service that ran until August 2014. At the end of this contract schools were left with both expensive change and refresh costs that were likely to be a financial burden many could ill afford and so they were hindered in their ability to embrace newer technologies that might assist transformation

Complication rates of resident-performed cataract surgery: Impact of early introduction of cataract surgery training.

PURPOSE: To determine the effect of the early introduction of cataract surgery training on the complication rates of resident-performed cataract surgery. SETTING: University of California San Diego, San Diego, California, USA. DESIGN: Retrospective case series. METHODS: Two classes of ophthalmology residents were examined, one class with a late introduction of cataract surgery and one with an early introduction of cataract surgery. All cataract cases in which residents acted as primary surgeon were included. Patient charts were reviewed to collect data on patient characteristics, surgical details, and intraoperative and postoperative complications. RESULTS: The late-introduction cohort comprised 3 residents who performed 540 cataract cases, all during their final year of residency. The early-introduction cohort comprised 4 residents who performed 780 cataract cases beginning in the first year of residency. The late-introduction cohort had higher rates of major intraoperative complications than the early-introduction cohort (8.5% versus 3.1%) and of anterior vitrectomy (7.6% versus 2.1%) (both P < .001). Examination of the anterior vitrectomy rate as a function of experience showed the early-introduction cohort had a stable anterior vitrectomy rate of 1% to 2% throughout training, while the late-introduction cohort had a peak anterior vitrectomy rate of 12% at approximately case 20. Multivariable regression analysis showed the early-introduction cohort was independently associated with a lower rate of anterior vitrectomy (hazard ratio, 0.49; 95% confidence interval, 0.36-0.66) after adjusting for differences in patient characteristics and surgical complexity. CONCLUSIONS: Early introduction of cataract surgery training significantly decreased the rate of major intraoperative complications, specifically anterior vitrectomy, in resident-performed cataract surgeries

The interaction of transmission intensity, mortality, and the economy: a retrospective analysis of the COVID-19 pandemic

The COVID-19 pandemic has caused over 6.4 million registered deaths to date, and has had a profound impact on economic activity. Here, we study the interaction of transmission, mortality, and the economy during the SARS-CoV-2 pandemic from January 2020 to December 2022 across 25 European countries. We adopt a Bayesian vector autoregressive model with both fixed and random effects. We find that increases in disease transmission intensity decreases Gross domestic product (GDP) and increases daily excess deaths, with a longer lasting impact on excess deaths in comparison to GDP, which recovers more rapidly. Broadly, our results reinforce the intuitive phenomenon that significant economic activity arises from diverse person-to-person interactions. We report on the effectiveness of non-pharmaceutical interventions (NPIs) on transmission intensity, excess deaths and changes in GDP, and resulting implications for policy makers. Our results highlight a complex cost-benefit trade off from individual NPIs. For example, banning international travel increases GDP however reduces excess deaths. We consider country random effects and their associations with excess changes in GDP and excess deaths. For example, more developed countries in Europe typically had more cautious approaches to the COVID-19 pandemic, prioritising healthcare and excess deaths over economic performance. Long term economic impairments are not fully captured by our model, as well as long term disease effects (Long Covid). Our results highlight that the impact of disease on a country is complex and multifaceted, and simple heuristic conclusions to extract the best outcome from the economy and disease burden are challenging

Quantum Oscillations Measurement of the Heavy Electron Mass near the van Hove Singularity in a Kagome Metal

Kagome metals with the Fermi energy tuned near the van Hove singularities (vHss) have shown to host exotic phases including unconventional superconductivity and a chiral flux phase arising from a charge density wave. However, most quantum oscillations studies of the electronic structure of kagome metals focus on compounds which electronically or magnetically order, obscuring the unperturbed vHs. Here we present quantum oscillation measurements of YV$_6$Sn$_6$ which contains a pristine kagome lattice free from long range order. We discovered quantum oscillations corresponding to a large orbit ($\approx$70% of the Brillouin Zone area) with the heaviest mass ever observed in vanadium based kagome metals ($\approx3.3 m_e$), consistent with a Fermi pocket whose Fermi level is near the vHs. Comparing with first principles calculations suggests that the effective mass of this pocket is highly sensitive to the position of Fermi level. Our study establishes the enhanced density of states associated with a vHs in a kagome metal, allowing further insight into a potential driving mechanism for the unconventional electronic orderings in this class of materials

Genomics-based re-examination of the taxonomy and phylogeny of human and simian Mastadenoviruses: an evolving whole genomes approach, revealing putative zoonosis, anthroponosis, and amphizoonosis

With the advent of high-resolution and cost-effective genomics and bioinformatics tools and methods contributing to a large database of both human (HAdV) and simian (SAdV) adenoviruses, a genomics-based re-evaluation of their taxonomy is warranted. Interest in these particular adenoviruses is growing in part due to the applications of both in gene transfer protocols, including gene therapy and vaccines, as well in oncolytic protocols. In particular, the re-evaluation of SAdVs as appropriate vectors in humans is important as zoonosis precludes the assumption that human immune system may be na€ıve to these vectors. Additionally, as impor- tant pathogens, adenoviruses are a model organism system for understanding viral pathogen emergence through zoonosis and anthroponosis, particularly among the primate species, along with recombination, host adaptation, and selection, as evidenced by one long-standing human respiratory pathogen HAdV-4 and a recent re-evaluation of another, HAdV-76. The latter reflects the insights on amphizoonosis, defined as infections in both directions among host species including “other than human”, that are pos- sible with the growing database of nonhuman adenovirus genomes. HAdV-76 is a recombinant that has been isolated from human, chimpanzee, and bonobo hosts. On-going and potential impacts of adenoviruses on public health and translational medicine drive this evaluation of 174 whole genome sequences from HAdVs and SAdVs archived in GenBank. The conclusion is that rather than separate HAdV and SAdV phylogenetic lineages, a single, intertwined tree is observed with all HAdVs and SAdVs forming mixed clades. Therefore, a single designation of “primate adenovirus” (PrAdV) superseding either HAdV and SAdV is proposed, or alter- natively, keeping HAdV for human adenovirus but expanding the SAdV nomenclature officially to include host species identifica- tion as in ChAdV for chimpanzee adenovirus, GoAdV for gorilla adenovirus, BoAdV for bonobo adenovirus, and ad libitum