Floquet topological transitions in extended Kane-Mele models with disorder

In this work we use Floquet theory to theoretically study the influence of circularly polarized light on disordered two-dimensional models exhibiting topological transitions. We find circularly polarized light can induce a topological transition in extended Kane-Mele models that include additional hopping terms and on-site disorder. The topological transitions are understood from the Floquet-Bloch band structure of the clean system at high symmetry points in the first Brillouin zone. The light modifies the equilibrium band structure of the clean system in such a way that the smallest gap in the Brillouin zone can be shifted from the $M$ points to the $K(K')$ points, the $\Gamma$ point, or even other lower symmetry points. The movement of the minimal gap point through the Brillouin zone as a function of laser parameters is explained in the high frequency regime through the Magnus expansion. In the disordered model, we compute the Bott index to reveal topological phases and transitions. The disorder can induce transitions from topologically non-trivial states to trivial states or vice versa, both examples of Floquet topological Anderson transitions. As a result of the movement of the minimal gap point through the Brillouin zone as a function of laser parameters, the nature of the topological phases and transitions is laser-parameter dependent--a contrasting behavior to the Kane-Mele model.Comment: 10 pages, 7 figure

Faster Calculation of Superquadric Shapes

Nonparametric methods of calculating points on the curve produce the recently introduced superquadric objects at great savings in time

Change in viral bronchiolitis management in hospitals in the UK after the publication of NICE guideline.

BACKGROUND: Viral bronchiolitis is one of the most common causes of hospitalisation in young infants. It has previously been shown that many United Kingdom (UK) hospital Trusts were not compliant with many aspects of the National Institute for Health and Care Excellence (NICE) bronchiolitis guideline prior to its publication. OBJECTIVES: This study aimed to investigate changes in the management of bronchiolitis by hospital Trusts between 2015 (before NICE guideline publication) and 2017, after publication. STUDY DESIGN: We prospectively surveyed paediatricians at UK hospital Trusts on the management of bronchiolitis before (March to May 2015) and after (January to May 2017) the NICE bronchiolitis guideline publication in June 2015, using an electronic, structured questionnaire. RESULTS: In 2015 111 Trusts were represented and in 2017 100 Trusts. Significant improvements were seen in the use of nebulised bronchodilators and hypertonic saline and provision of parental written guidance. However, full compliance with the guideline did not change with 18% of Trusts compliant before publication of the guideline in 2015 and 19% fully compliant with the guideline in 2017. CONCLUSIONS: Overall there were modest but important improvements in the reported management of bronchiolitis after the publication of the NICE guideline

Slip casting and extruding shapes of rhenium with metal oxide additives. 1: Feasibility demonstration

The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the rhenium of up to 15 weight percent were used. Tubes of 17 mm diameter with 0.5 mm walls were slip cast by adapting current ceramic oxide techniques. A complete cast double conical nozzle demonstrated the ability to meet shapes and tolerances. Extrusion of meter long tubing lengths of 3.9 mm o.d. x 2.3 mm i.d. final dimension is documented. Sintering schedules are presented to produce better than 95% of theoretical density parts. Finished machining was found possible were requried by electric discharge machining and diamond grinding

Research on the application of satellite remote sensing to local, state, regional, and national programs involved with resource management and environmental quality

Project summaries and project reports are presented in the area of satellite remote sensing as applied to local, regional, and national environmental programs. Projects reports include: (1) Douglas County applications program; (2) vegetation damage and heavy metal concentration in new lead belt; (3) evaluating reclamation of strip-mined land; (4) remote sensing applied to land use planning at Clinton Reservoir; and (5) detailed land use mapping in Kansas City, Kansas

Simple supersymmetric solution to the strong CP problem

It is shown that the minimal supersymmetric left-right model can provide a natural solution to the strong {\it CP} problem without the need for an axion, nor any additional symmetries beyond supersymmetry and parity.Comment: Plain Latex. 10 pages, including two figures which are part of the Latex file. Shortened version, to appear in Phys. Rev. Lett. 7

Influence of Reactor Design on Product Distributions from Biomass Pyrolysis

This paper explores the elements of experimental design that affect outcomes of pyrolysis experiments. Primary pyrolysis products are highly reactive, and reactor properties that tend to promote or suppress their secondary reactions play a key role in determining final product distributions. In assessing particular experimental designs, it is often useful to compare results from different configurations under similar experimental conditions. In the case of pure cellulose, char yields from pyrolysis experiments were observed to vary between 1 and 26%, as a function of changes in reactor design and associated operating parameters. Most other examples have been selected from the pyrolysis of ligno-cellulosic biomass and its main constituents, although relevant data from coal pyrolysis experiments have also been examined. The work focuses on identifying the ranges of conditions where diverse types of reactors provide more dependable data. The greater reliability of fluidized-bed reactors for weight loss (total volatile) determinations in the 300–550 °C range, particularly relevant to the study of biomass pyrolysis, has been highlighted and compared with challenges encountered in using wire-mesh reactors and thermogravimetric balances in this temperature range

Identifying Synergistic Effects between Biomass Components during Pyrolysis and Pointers Concerning Experiment Design

A review of existing data has shown that “char yield deficits” develop during the pyrolysis of lignocellulosic biomass, relative to char yields expected from pyrolyzing chemically isolated lignins and the proportion of lignin in the particular biomass. This paper describes two sets of pyrolysis experiments. The work done in a thermogravimetric (TG) balance was initiated to probe whether diminishing heating rates might reduce, or even wipe out, the “char yield deficits” identified in previous work, where a wide range of heating rates had been used. Experiments were performed at 2 °C min–1, a lower heating rate than that has hitherto been used to investigate char deficits. The effect was confirmed at this slow heating rate, using samples of birchwood and almond shells. A parallel set of differential scanning calorimetry (DSC) experiments provided evidence that mechanisms by which biomass samples pyrolyze are distinct from those of biomass components pyrolyzing in isolation. Moreover, the observed effects could not be replicated by simply mixing the three biomass components in appropriate proportions. The “lignin char deficit” is consistent with chemical interactions between intermeshed biomass components during pyrolysis altering reaction pathways and product distributions relative to the pyrolysis of biomass components pyrolyzed in isolation. The present work also shows that sample mass loss in TG balances is affected by altering sample loading, leading to potential errors. The design of pyrolysis experiments is discussed and approaches are suggested to prevent masking of key pyrolysis phenomena, viz. synergistic effects between biomass components or onset-of-pyrolysis temperatures, through the appropriate selection of experimental parameters

Liquid biofuels from food crops in transportation – A balance sheet of outcomes

The production and utilization of biofuels from food crops have been reviewed. Developments in Brazil, the United States, the European Union and China have been assessed in relation to the aims of biofuels policies, their costs and outcomes. The energy input for making biofuels has been compared with energy released during their combustion. The effect of using crops for fuel on the cost of grain for food and of arable land have been examined. There is evidence that current international policies have caused environmental degradation greater than the fossil fuels they were purported to replace. However, policy choices are difficult to reverse. Despite vast effort and expense, the actual scale of biofuels production is small compared to the resources that have been mobilized. As these processes have evolved, new groups of commercial interests have coalesced internationally, to take advantage of the subsidies with little recognizable benefit to the environment

Simulating Impacts of Extreme Weather Events on Urban Transport Infrastructure in the UK

Urban areas face many risks from future climate change and their infrastructure will be placed under more pressure due to changes in climate extremes. Using the Tyndall Centre Urban Integrated Assessment Framework, this paper describes a methodology used to assess the impacts of future climate extremes on transport infrastructure in London. Utilising high-resolution projections for future climate in the UK, alongside stochastic weather generators for downscaling, urban temperature and flooding models are used to provide information on the likelihood of future extremes. These are then coupled with spatial network models of urban transport infrastructure and, using thresholds to define the point at which systems cease to function normally, disruption to the networks can be simulated. Results are shown for both extreme heat and urban surface water flooding events and the impacts on the travelling population, in terms of both disruption time and monetary cost