Scoring the sum of correlated results in analytical proficiency testing

In proficiency tests the participants' results are usually converted into scores. In some schemes the participants are required to report the sum of the concentrations of a number of analytes and this total also is converted into a score. In such instances the scoring procedure for the total should be mathematically consistent with that for the separate analytes. When these analytes are determined from a single test portion, however, the errors in the results from a participant are likely to be correlated because some stages of the analysis are common to all of the analytes. For a consistent outcome, the scoring method must take account of such correlation

Nonlinear dynamic Interactions between flow-induced galloping and shell-like buckling

Acknowledgement The research of J.S. is supported by EPSRC Grant EP/J010820/1.Peer reviewedPublisher PD

Effectiveness of Ninth-Grade Physics in Maine: Conceptual Understanding

The Physics First movement - teaching a true physics course to ninth grade students - is gaining popularity in high schools. There are several different rhetorical arguments for and against this movement, and it is quite controversial in physics education. However, there is no actual evidence to assess the success, or failure, of this substantial shift in the science teaching sequence. We have undertaken a comparison study of physics classes taught in ninth- and 12th grade classes in Maine. Comparisons of student understanding and gains with respect to mechanics concepts were made with excerpts from well-known multiple-choice surveys and individual student interviews. Results indicate that both populations begin physics courses with similar content knowledge and specific difficulties, but that in the learning of the concepts ninth graders are more sensitive to the instructional method used.Comment: 15 pages, 2 tables, 0 figures, to be published in The Physics Teache

Wired Up for Extra Value

The demand for Internet connectivity in office buildings opens up opportunities for landlords to provide added-value services to their tenants. This article seeks to explore the hypothesis that the provision of high bandwidth telecommunications to a building increases its value relative to buildings without this facility. The article builds upon research undertaken into existing use of the Internet over the past two years as evidence of demand for facilities and explores the likely impact of the provision of connectivity on different types of office. The connected building is defined and issues affecting its valuation analyzed. Finally, a hypothetical business model is constructed for a large multi-let building to demonstrate the likely income stream and timing that would be applicable.

A post-Brexit agreement for research and innovation Outcomes from a simulated negotiation process. Bruegel Special Report 28 January 2020

The UK will leave the European Union on 31 January 2020. Negotiators and commentators have spent more than three years discussing the terms on which the UK will withdraw, but comparatively little attention has been paid to the future relationship between the UK and the EU after Brexit at a sectoral level. Withdrawing is merely the first stage of the process, and the UK and the EU will soon begin to think about negotiating a new relationship and decide which issues to prioritise. Research and innovation is one of the key areas in which the UK and the EU will need to establish a post-Brexit relationship. Over the past two decades, the UK and the EU have been at the forefront of that enterprise through the development of the European Research Area (ERA). Together, European nations have created a world-leading research base. Six of the world’s top twenty universities are in the ERA, and Europe produces a third of the world’s scientific publications with just 7% of the global population. A new post-Brexit relationship on research and innovation will need to be negotiated to ensure we sustain and grow this valuable and mutually beneficial partnership. Research and innovation are critical to achieving lasting competitiveness and economic development, especially with the dominance of the USA and the rising challenge of China in this field. An early agreement providing for cooperation on research and innovation would reflect the economic and social importance of research and innovation to the people of the UK and the EU. This report sets out what the Wellcome Trust and Bruegel have learned from a project to simulate a negotiation process between the UK and EU to create a post-Brexit research and innovation agreement. Our negotiating scenario assumed that the UK had left the EU with a withdrawal agreement, and that the negotiation was taking place during a ‘standstill’ transition period. Our exercise demonstrated that it is possible to reach agreement among experts on the terms of an EU-UK research and innovation deal. However, the project also revealed that some elements of an agreement may be harder to negotiate than expected. A shared purpose and belief in the importance of research and innovation is not enough to see a deal come to fruition. It is also necessary to overcome a number of political and technical challenges that are spelled out in this report. The process must start now to ensure an agreement is reached as soon as possible. We hope that this report will provide inspiration and guidance for that process

A delay differential model of ENSO variability: Parametric instability and the distribution of extremes

We consider a delay differential equation (DDE) model for El-Nino Southern Oscillation (ENSO) variability. The model combines two key mechanisms that participate in ENSO dynamics: delayed negative feedback and seasonal forcing. We perform stability analyses of the model in the three-dimensional space of its physically relevant parameters. Our results illustrate the role of these three parameters: strength of seasonal forcing $b$, atmosphere-ocean coupling $\kappa$, and propagation period $\tau$ of oceanic waves across the Tropical Pacific. Two regimes of variability, stable and unstable, are separated by a sharp neutral curve in the $(b,\tau)$ plane at constant $\kappa$. The detailed structure of the neutral curve becomes very irregular and possibly fractal, while individual trajectories within the unstable region become highly complex and possibly chaotic, as the atmosphere-ocean coupling $\kappa$ increases. In the unstable regime, spontaneous transitions occur in the mean ``temperature'' ({\it i.e.}, thermocline depth), period, and extreme annual values, for purely periodic, seasonal forcing. The model reproduces the Devil's bleachers characterizing other ENSO models, such as nonlinear, coupled systems of partial differential equations; some of the features of this behavior have been documented in general circulation models, as well as in observations. We expect, therefore, similar behavior in much more detailed and realistic models, where it is harder to describe its causes as completely.Comment: 22 pages, 9 figure

Forward modelling of sub-photospheric flows for time-distance helioseismology

Context: The results of forward modelling of acoustic wave propagation in a realistic solar sub-photosphere with two cases of steady horizontal flows are presented and analysed by the means of local helioseismology. Aims: This paper is devoted to an analysis of the influence of steady flows on the propagation of sound waves through the solar interior. Methods: The simulations are based on fully compressible ideal hydrodynamical modelling in a Cartesian grid. The initial model is characterised by solar density and pressure stratifications taken from the standard Model S and is adjusted in order to suppress convective instability. Acoustic waves are excited by a non-harmonic source located below the depth corresponding to the visible surface of the Sun. Numerical experiments with coherent horizontal flows of linear and Gaussian dependences of flow speed on depth are carried out. These flow fields may mimic horizontal motions of plasma surrounding a sunspot, differential rotation or meridional circulation. An inversion of the velocity profiles from the simulated travel time differences is carried out. The inversion is based on the ray approximation. The results of inversion are then compared with the original velocity profiles. Results: The results of forward modelling of acoustic wave propagation in a realistic solar sub-photosphere with two cases of steady horizontal flows are presented. The influence of steady flow on the propagation of sound waves through the solar interior is analysed. A time-distance analysis technique is applied to compute the direct observable signatures of the background bulk motions on travel times and phase shifts. This approach allows direct comparison with observational data. Further, we propose a method of obtaining the travel-time differences for the waves propagating in sub-photospheric solar regions with horizontal flows. The method employs directly the difference between travel-time diagrams of waves propagating with and against the background flow. Conclusions: The analysis shows that the flow speed profiles obtained from inversion based on the ray approximation differ from the original ones. The difference between the original and observed profiles is caused by the fact that the wave packets propagate along the ray bundle, which has a finite extent, and thus reach deeper regions of the sub-photosphere in comparison with ray theory