Universal nonlinear infection kernel from heterogeneous exposure on higher-order networks

The colocation of individuals in different environments is an important prerequisite for exposure to infectious diseases on a social network. Standard epidemic models fail to capture the potential complexity of this scenario by (1) neglecting the higher-order structure of contacts which typically occur through environments like workplaces, restaurants, and households; and by (2) assuming a linear relationship between the exposure to infected contacts and the risk of infection. Here, we leverage a hypergraph model to embrace the heterogeneity of environments and the heterogeneity of individual participation in these environments. We find that combining heterogeneous exposure with the concept of minimal infective dose induces a universal nonlinear relationship between infected contacts and infection risk. Under nonlinear infection kernels, conventional epidemic wisdom breaks down with the emergence of discontinuous transitions, super-exponential spread, and hysteresis

Structure and function of the Rad9-binding region of the DNA-damage checkpoint adaptor TopBP1

TopBP1 is a scaffold protein that coordinates activation of the DNA-damage-checkpoint response by coupling binding of the 9-1-1 checkpoint clamp at sites of ssDNA, to activation of the ATR-ATRIP checkpoint kinase complex. We have now determined the crystal structure of the N-terminal region of human TopBP1, revealing an unexpected triple-BRCT domain structure. The arrangement of the BRCT domains differs significantly from previously described tandem BRCT domain structures, and presents two distinct sites for binding phosphopeptides in the second and third BRCT domains. We show that the site in the second but not third BRCT domain in the N-terminus of TopBP1, provides specific interaction with a phosphorylated motif at pSer387 in Rad9, which can be generated by CK2

Turbulent transport of impurities in 3D devices

A large diffusive turbulent contribution to the radial impurity transport in Wendelstein 7-X (W7-X) plasmas has been experimentally inferred during the first campaigns and numerically confirmed by means of gyrokinetic simulations with the code stella. In general, the absence of strong impurity accumulation during the initial W7-X campaigns is attributed to this diffusive term. In the present work the diffusive contribution is also calculated in other stellarator plasmas. In particular, the diffusion (D) and convection (V) coefficients of carbon and iron impurities produced by ion-temperature-gradient (ITG) turbulence are obtained for W7-X, LHD, TJ-II and NCSX. The results show that, although the size of D and V can differ across the four devices, inward convection is found for all of them. For W7-X, TJ-II and NCSX the two coefficients are comparable and the turbulent peaking factor is surprisingly similar. In LHD, appreciably weaker diffusive and convective impurity transport and significantly larger turbulent peaking factor are predicted. All this suggests that ITG turbulence, although not strongly, would lead to negative impurity density gradients in stellarators. Then, considering mixed ITG/Trapped Electron Mode (TEM) turbulence for the specific case of W7-X, it has been quantitatively assessed to what degree pellet fueled reduced turbulence scenarios feature reduced turbulent transport of impurities as well. The results for trace iron impurities show that, although their turbulent transport is not entirely suppressed, a significant reduction of V and a stronger decrease of D are found. Although the diffusion is still above neoclassical levels, the neoclassical convection would gain under such conditions a greater specific weight on the dynamics of impurities in comparison with standard ECRH scenarios.Comment: 16 pages, 8 figure

Thinking together: What makes Communities of Practice work?

In this article, we develop the founding elements of the concept of Communities of Practice by elaborating on the learning processes happening at the heart of such communities. In particular, we provide a consistent perspective on the notions of knowledge, knowing and knowledge sharing that is compatible with the essence of this concept – that learning entails an investment of identity and a social formation of a person. We do so by drawing richly from the work of Michael Polanyi and his conception of personal knowledge, and thereby we clarify the scope of Communities of Practice and offer a number of new insights into how to make such social structures perform well in professional settings. The conceptual discussion is substantiated by findings of a qualitative empirical study in the UK National Health Service. As a result, the process of ‘thinking together’ is conceptualized as a key part of meaningful Communities of Practice where people mutually guide each other through their understandings of the same problems in their area of mutual interest, and this way indirectly share tacit knowledge. The collaborative learning process of ‘thinking together’, we argue, is what essentially brings Communities of Practice to life and not the other way round

Are Paleomagnetic Records From U‐Channels Appropriate for Studies of Reversals and Excursions?

Sampling of sediment cores using plastic U‐channels has made possible the acquisition of detailed records of paleomagnetic secular variation, geomagnetic polarity, environmental magnetic studies, and relative paleointensity over the past several million years. U‐channel measurements provide the great advantage of rapid measurements of long sediment cores, but the signal resolution is attenuated by the response function of the magnetometer sensors, which therefore restrains the recovery of rapid and large‐amplitude field changes. Here we focus on the suitability of the dynamics of reversals and excursions derived from U‐channel measurements. We compare successive individual paleomagnetic directions of 1.5 cm × 1.5 cm × 1.5 cm cubic discrete samples with those of a 1.5‐m equivalent U‐channel sample train obtained by placing the samples adjacent to each other. We use varying excursion and transition lengths and generate transitional directions that resemble those of the most detailed paleomagnetic records. Excursions with opposite polarity directions recorded over less than 7.5 cm are barely detected in U‐channel measurements. Regarding reversals, U‐channel measurements smooth the signal of low‐resolution records and generate artificial transitional directions. Despite producing misleading similarities with the overall structure of transition records, longer transitional intervals fail also to reproduce the complexity of field changes. Finally, we test the convolution of magnetization by different response functions. The simulation reveals that even small response function changes can generate significant differences in results. -- Keywords : geomagnetic reversals ; geomagnetic excursions ; paleomagnetic measurements

New linear stability parameter to describe low-β\beta electromagnetic microinstabilities driven by passing electrons in axisymmetric toroidal geometry

In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, $\beta$, can become sufficiently large that electromagnetic microinstabilities become unstable, driving turbulence that distorts or reconnects the equilibrium magnetic field. In this paper, a theory is proposed for electromagnetic, electron-driven linear instabilities that have current layers localised to mode-rational surfaces and binormal wavelengths comparable to the ion gyroradius. The model retains axisymmetric toroidal geometry with arbitrary shaping, and consists of orbit-averaged equations for the mode-rational surface layer, with a ballooning space kinetic matching condition for passing electrons. The matching condition connects the current layer to the large scale electromagnetic fluctuations, and is derived in the limit that $\beta$ is comparable to the square root of the electron-to-ion-mass ratio. Electromagnetic fluctuations only enter through the matching condition, allowing for the identification of an effective $\beta$ that includes the effects of equilibrium flux surface shaping. The scaling predictions made by the asymptotic theory are tested with comparisons to results from linear simulations of micro-tearing and electrostatic microinstabilities in MAST discharge #6252, showing excellent agreement. In particular, it is demonstrated that the effective $\beta$ can explain the dependence of the local micro-tearing mode (MTM) growth rate on the ballooning parameter $\theta_0$ -- possibly providing a route to optimise local flux surfaces for reduced MTM-driven transport.Comment: 29 pages, 14 figure

Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change

<p>Abstract</p> <p>Background</p> <p>Lyme disease is the commonest vector-borne zoonosis in the temperate world, and an emerging infectious disease in Canada due to expansion of the geographic range of the tick vector <it>Ixodes scapularis</it>. Studies suggest that climate change will accelerate Lyme disease emergence by enhancing climatic suitability for <it>I. scapularis</it>. Risk maps will help to meet the public health challenge of Lyme disease by allowing targeting of surveillance and intervention activities.</p> <p>Results</p> <p>A risk map for possible Lyme endemicity was created using a simple risk algorithm for occurrence of <it>I. scapularis </it>populations. The algorithm was calculated for each census sub-division in central and eastern Canada from interpolated output of a temperature-driven simulation model of <it>I. scapularis </it>populations and an index of tick immigration. The latter was calculated from estimates of tick dispersion distances by migratory birds and recent knowledge of the current geographic range of endemic <it>I. scapularis </it>populations. The index of tick immigration closely predicted passive surveillance data on <it>I. scapularis </it>occurrence, and the risk algorithm was a significant predictor of the occurrence of <it>I. scapularis </it>populations in a prospective field study. Risk maps for <it>I. scapularis </it>occurrence in Canada under future projected climate (in the 2020s, 2050s and 2080s) were produced using temperature output from the Canadian Coupled Global Climate Model 2 with greenhouse gas emission scenario enforcing '<it>A2</it>' of the Intergovernmental Panel on Climate Change.</p> <p>Conclusion</p> <p>We have prepared risk maps for the occurrence of <it>I. scapularis </it>in eastern and central Canada under current and future projected climate. Validation of the risk maps provides some confidence that they provide a useful first step in predicting the occurrence of <it>I. scapularis </it>populations, and directing public health objectives in minimizing risk from Lyme disease. Further field studies are needed, however, to continue validation and refinement of the risk maps.</p

Murmuration

Murmuration is an outcome of the EU Culture funded EMDL project (EMDL.eu), exhibited at Society for Arts and Technology’s (SAT) Satosphere. The artistic research initiative brought together an international interdisciplinary group to explore the fulldome environment as a platform for creative innovation. Murmuration consolidated research into networked navigation devices for virtual spaces, swarm algorithms for audience participation, 3D scanning (MRI volumetric modelling) and 3D sonification for game engines in performance

Recent sedimentation in three adjacent fjord-lakes on the Québec North Shore (eastern Canada): facies analysis, laminae preservation, and potential for varve formation

Cet article analyse de courtes carottes gravitaires échantillonnées le long de transects dans trois lacs de fjord profonds adjacents (les lacs Pentecôte, Walker et Pasteur) sur la Côte-Nord du Québec (est du Canada), afin d’évaluer la répartition de sédiments laminés et le potentiel de formation de varves. L’analyse des faciès basée sur la description lithologique, des photos numériques, des images par tomodensitométrie et des données bathymétriques, a permis l’identification de quatre principaux faciès sédimentaires : des sédiments laminés, des sédiments partiellement laminés, des sédiments bioturbés et des sédiments massifs. Des preuves directes sur la stratification thermique du Lac Walker ont été acquises de 2014 à 2016. Les taux de sédimentation moyens et les flux de sédimentation postglaciaires dans les bassins distaux des trois lacs étudiés sont ≤0,12 cm a−1 et de 0,03 à 0,16 g cm−2 a−1, respectivement, à la lumière de la datation aux 210Pb, 137Cs et radiocarbone par SMA. Sur la base de l’analyse d’images de lames minces et d’un modèle de chronologie du 210Pb (CIC), le Lac Pentecôte contient des sédiments principalement massifs à partiellement laminés, alors que le Lac Pasteur contient des sédiments partiellement laminés et des sédiments laminés non annuels ressemblants à des varves. Le Lac Walker contient toutefois des sédiments laminés qui sont vraisemblablement des varves. Le plus grand potentiel de préservation de laminations observé pour le lac Walker par rapport aux lacs Pentecôte et Pasteur est associé à des caractéristiques morphologiques plus favorables, dont sa profondeur relative, sa profondeur moyenne, sa profondeur maximum et son exposition topographique plus importantes. -- Keywords : Limnogeology ; sedimentary structures ; laminations ; varves ; CT-scan ; Québec North Shore