Computational modelling suggests dynamic interactions between Ca2+, IP3 and G protein-coupled modules are key to robust Dictyostelium aggregation

Under conditions of starvation, Dictyostelium cells begin a programme of development during which they aggregate to form a multicellular structure by chemotaxis, guided by propagating waves of cyclic AMP that are relayed robustly from cell to cell. In this paper, we develop and analyse a new model for the intracellular and extracellular cAMP dependent processes that regulate Dictyostelium migration. The model allows, for the first time, a quantitative analysis of the dynamic interactions between calcium, IP(3) and G protein-dependent modules that are shown to be key to the generation of robust cAMP oscillations in Dictyostelium cells. The model provides a mechanistic explanation for the transient increase in cytosolic free Ca(2+) concentration seen in recent experiments with the application of the calmodulin inhibitor calmidazolium (R24571) to Dictyostelium cells, and also allows elucidation of the effects of varying both the conductivity of stretch-activated channels and the concentration of external phosphodiesterase on the oscillatory regime of an individual cell. A rigorous analysis of the robustness of the new model shows that interactions between the different modules significantly reduce the sensitivity of the resulting cAMP oscillations to variations in the kinetics of different Dictyostelium cells, an essential requirement for the generation of the spatially and temporally synchronised chemoattractant cAMP waves that guide Dictyostelium aggregation

Econometric estimation of nested production functions and testing in a computable general equilibrium analysis of economy-wide rebound effects

Quantitative models, such as computable general equilibrium (CGE), that are increasingly used to inform policy processes rely on a number of assumptions concerning how good and services are produced. Previous research has shown that the elasticity of substitution between inputs and the structure in which these inputs interact can have large impacts on model output. However, the choice of elasticities and production structure is often made without the support of statistical evidence. This research aims to address these points by estimating nesting structure and the elasticities of substitution therein across a number of sectors in the UK then testing the implications of introducing these estimates to parameterise a CGE model that is then used to simulation the economy-wide impacts of increased efficiency in the productive use of energy

A spectral collocation approximation for the radial-infall of a compact object into a Schwarzschild black hole

The inhomogeneous Zerilli equation is solved in time-domain numerically with the Chebyshev spectral collocation method to investigate a radial-infall of the point particle towards a Schwarzschild black hole. Singular source terms due to the point particle appear in the equation in the form of the Dirac $\delta$-function and its derivative. For the approximation of singular source terms, we use the direct derivative projection method without any regularization. The gravitational waveforms are evaluated as a function of time. We compare the results of the spectral collocation method with those of the explicit second-order central-difference method. The numerical results show that the spectral collocation approximation with the direct projection method is accurate and converges rapidly when compared with the finite-difference method.Comment: Accepted for publication in International Journal of Modern Physics C (IJMPC

Tevatron Top AFBA_{FB} Versus LHC Top Physics

We carry out a comprehensive analysis of models for top A_{FB} at CDF in light of new top data arriving from the LHC. We begin with a careful Tevatron analysis, considering in general which sets of effective vertices give rise to a large forward-backward asymmetry while suppressing the contribution to the total t tbar cross-section. We show on general grounds that scalar models struggle to produce sufficient asymmetries consistent with CDF observations, while vector models can produce a large asymmetry with a less significant tension in the total cross-section and $t\bar{t}$ invariant mass distribution at the Tevatron. We examine the essential observables of these models for top physics at LHC7 with 1 fb^{-1} of data, including the total cross-section, invariant mass distribution and number of additional jets in t tbar events. In the case of t-channel mediators, the LHC total cross-section places a strong constraint on light mediators, while the Tevatron invariant mass distributions place strong constraints on heavy mediators that are able to produce the asymmetry. Heavy axigluons are becoming increasingly squeezed by LHC7 t tbar and dijet resonance searches. We conclude that LHC7 top analyses are rapidly closing the window for viable models of the CDF top A_{FB}.Comment: 51 pages, 25 figures, 7 tables; v2: refs. added, typos fixed, figures improved, notes adde

High-performance athletes’ transition out of sport: developing corporate social responsibility

This study investigates high-performance athletes’ experiences of transitioning out of sport and the support provided to them and describes how the findings suggest Corporate Social Responsibility (CSR) initiatives which may inform the development of sport policies addressing issues surrounding sport career transitions. Semi-structured interviews were used to collect data exploring athletes’ lived experiences of adapting to life after sport. Purposive sampling was applied to 20 retired high-performance athletes (10 male; 10 female), from six different countries, representing 11 Olympic sports. The causes of career termination are found to be multifaceted, with the findings indicating different factors such as ‘feelings of reaching saturation point’, shifts in priorities, decreased self-awareness of performance, policy changes (e.g. reductions in funding, changes in coaching personnel), and significant singular events such as crucial losses to key rivals. Lost goals and identity and a lack of pre-retirement planning were considered as major challenges post-retirement. Refocusing and developing new priorities in life and the importance of seeking support were highlighted in discussions on coping with life post-transition. The findings demonstrate that high-performance athletes require support and care from sport governing bodies and social support providers in adapting to post-athletic life. The implications of these findings for CSR initiatives and their relevance to the policymaking process are discussed

Organisational Support for High-Performance Athletes to Develop Financial Literacy and Self-Management Skills

This paper reports the results of analysing desk-based data on organisational support for high performance athletes to develop their financial literacy and self-management skills when transitioning out of sport. There are two research questions: (1) Do sport organisations provide support schemes or other interventions such that high-performance athletes develop their financial literacy and self-management skills? and (2) Do sport organisations provide financial support schemes for high-performance athletes’ retirements? If so, what do they involve? Desk-based data collection was applied to 23 sporting organisations; these comprised 21 national organisations representing 19 countries, the International Olympic Committee (IOC) and the Oceanic National Olympic Committee (ONOC). Fifteen of the 23 organisations, representing 14 countries, provided some support or interventions on financial planning and self-management within their career assistance programmes. The findings also indicate that most organisations in 17 different countries did not provide any financial support for athletes’ retirements. While a number of sport organisations have developed appropriate interventions to assist high-performance athletes to develop financial literacy and self-management skills, such schemes appear only to be provided to high-performance athletes who have competed at the highest level e.g., Olympics, world championships, etc. Support for athletes at lower levels should also be developed and delivered by national governments, or by national sport organisations

Platinum-group element geochemistry of the volcanic rocks associated with the Jaguar and Bentley Cu-Zn volcanogenic massive sulfide (VMS) deposits, Western Australia: implications for the role of chalcophile element fertility on VMS mineralization

We report whole-rock major, trace, and platinum-group element (PGE) geochemistry of volcanic rocks from the Teutonic Bore complex that hosts the Jaguar and Bentley Cu–Zn volcanogenic massive sulfide (VMS) deposits. This study aims to understand their sulfide saturation history and chalcophile element evolution during differentiation of the Jaguar and Bentley magmas, and investigate the role of chalcophile element fertility on the formation of VMS deposits. The fractionated primitive mantle– normalized trace element patterns, with negative Nb and Ti anomalies of basalts, andesites, dacites, and rhyolites from Jaguar and Bentley, are similar to each other. The trace elements and PGE show continuous variations when plotted against fractionation indices such as Yb, which can be explained by a two-stage fractional crystallization model: stage 1 Rayleigh fractionation of plagioclase + clinopyroxene + Cr-spinel, and stage 2 the fractional of plagioclase + clinopyroxene + magnetite + 0.1 wt% sulfide liquid. Dolerites, which postdate the mineralization, differ from the other rock types and require a different magma source. Andesite and basalt are the most PGE-enriched lithologies in Jaguar and Bentley. The PGE behave incompatibly in the early stage of magma differentiation at 4 ppm Yb, indicating sulfide saturation at this point. When Pd/MgO and Pd/Pt are used as chalcophile element fertility indicators, the andesite before sulfide saturation (< 4 ppm Yb) is as fertile as the magmas associated with porphyry Cu-only deposits. In contrast, the andesite after sulfide saturation and other lithologies are characterized by markedly depleted fertility similar to those of barren suites. This suggests that sulfideundersaturated andesite, and probably basalt, may have been a significant source for Cu in the Jaguar and Bentley Cu–Zn VMS deposits. However, the Au fertility of the Jaguar and Bentley andesite must have been low and not enough to form Au-rich VMS deposits because their Pd/MgO and Pd/Pt values are 5–10 times lower than those of andesite and dacite from the modern Au-rich seafloor massive sulfide deposits. This can be explained if ore formation occurred shortly after sulfide saturation. If the amount of sulfide melt to precipitate was small, Au, with its high partition coefficient into immiscible sulfide melts, would have been largely stripped from the silicate melt, whereas Cu, with its lower partition coefficient, would be little affected. Our study shows that chalcophile element fertility may play an important role in the formation of VMS deposits, especially in controlling the Au contents of the ore, if the magmatic-hydrothermal component is the dominant source for metals in VMS systems.This research was funded by the ARC Linkage Project LP110200747, and we thank its sponsors, particularly the Independence Group, for access to the Jaguar and Bentley VMS deposits and to their geochemical and petrological data. We also acknowledge that part of this study was supported by the National Research Foundation (NRF) of Korea grant funded by the Korea government (No. 2019R1A2C1009809) for a project entitled “Understanding the deepsea biosphere on seafloor hydrothermal vents in the Indian Ridge (No. 20170411)” funded by the Ministry of Oceans and Fisheries, Kore

Circuit and Electromagnetic Modelling of a low cost IEMI Sensor

The design of a low cost broadband Intentional Electromagnetic Interference (IEMI) detector and antenna to achieve a flat frequency response over a broad range is considered. SPICE simulation of the antenna, detector and low power log-amplifier circuit is used to predict the detector performance. The SPICE Antenna model is derived from numerical electromagnetic simulation. Simulations are compared with measured performance

'My Sport Won't Pay the Bills Forever': High-Performance Athletes' Need for Financial Literacy and Self-Management

This paper investigates high-performance athletes’ development of their financial literacy and self-management skills and the related organisational support available to them during their athletic careers. The data were collected from 20 retired high-performance athletes (10 male and 10 female) representing six different countries (Japan, Mexico, Portugal, Singapore, South Korea, and the UK). Thematic analysis was applied to the processing of the data and five themes emerged: (1) Funding battles: financial challenges and misjudgements; (2) Coping Strategies; (3) Support from sponsors, parents, and sport organisations; (4) Development of Financial Literacy; and (5) Life After Sport. The data indicates that athletes experienced financial challenges due to a lack of organisational support, reduced or terminated funding, and limited opportunities to access sponsorship. Typically, athletes developed their financial literacy and self-management skills by ‘self-help’ or ‘trial and error’. The findings contribute to both literature and practice by providing empirical evidence on the coping strategies adopted by athletes in order to overcome financial challenges and on the methods used in order to develop their financial literacy and self-management skills. These findings inform sport organisations and governing bodies to develop support schemes for high-performance athletes as well as deepen our knowledge of athletes’ career development and transitions focusing on the financial aspect