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Intervening on causal systems can illuminate their underlying structures. Past work has shown that, relative to adults, young children often make intervention decisions that appear to confirm a single hypothesis rather than those that optimally discriminate alternative hypotheses. Here, we investigated how the ability to make informative causal interventions changes across development. Ninety participants between the ages of 7 and 25 completed 40 different puzzles in which they had to intervene on various causal systems to determine their underlying structures. Each puzzle comprised a three- or four-node computer chip with hidden wires. On each trial, participants viewed two possible arrangements of the chip’s hidden wires and had to select a single node to activate. After observing whether their intervention caused other nodes to turn on, participants selected a wire configuration, and rated their confidence in their selection. We characterized participant choices with a Bayesian measurement model that indexed the extent to which participants selected nodes that would best disambiguate the two possible causal structures vs. those that elicited evidence in favor of one of the two causal hypotheses, but did not necessarily discriminate between them. Our model estimates revealed that the use of discriminatory strategies increased through early adolescence. Further, developmental improvements in intervention strategy were related to changes in the ability to accurately judge the strength of evidence that their interventions revealed, as indexed by participants’ confidence in their selections. Our results suggest that improvements in causal information-seeking extend into adolescence and may be driven by metacognitive sensitivity to the efficacy of previous interventions in discriminating competing ideas.

Acute respiratory distress syndrome is a pulmonary disease that requires the use of mechanical ventilation for patient recovery. However, this can lead to development of ventilator-induced lung injury caused by the over-distension of alveolar tissue and by the repetitive closure (de-recruitment) and reopening (recruitment) of airways. In this study, we developed a multi-scale model of the lung from a reduced-dimension approach to investigate the dynamics of ventilation in the lung during airway collapse and reopening. The model consisted of an asymmetric network geometry with 16 generations of liquid-lined airways with airflow driven by a variable pleural pressure. During the respiratory cycle changes in airway radii and film thickness yield the formation of liquid plugs that propagate and rupture throughout the airway network. Simulations were conducted with constant surface tension values [Formula: see text] dyn/cm. It was observed that the time onset of plug creation and rupture depended on the surface tension, as well as the plug aggregation/splitting behavior at bifurcations. Additionally, the plug propagation behavior was significantly influenced by presence of plugs in adjacent airways (i.e. parent and daughters) that affected the driving pressure distribution locally at bifurcations and resulted in complex aggregation and splitting behavior. This model provides an approach that has the ability to simulate normal and pathophysiological lung conditions with the potential to be used in personalized clinical medicine.

We describe a new version of GBS, a 3D global, flux-driven plasma turbulence code to simulate the turbulent dynamics in the tokamak scrape-off layer (SOL), superseding the code presented by Ricci et al. (2012) [14]. The present work is driven by the objective of studying SOL turbulent dynamics in medium size tokamaks and beyond with a high-fidelity physics model. We emphasize an intertwining framework of improved physics models and the computational improvements that allow them. The model extensions include neutral atom physics, finite ion temperature, the addition of a closed field line region, and a non-Boussinesq treatment of the polarization drift. GBS has been completely refactored with the introduction of a 3-D Cartesian communicator and a scalable parallel multigrid solver. We report dramatically enhanced parallel scalability, with the possibility of treating electromagnetic fluctuations very efficiently. The method of manufactured solutions as a verification process has been carried out for this new code version, demonstrating the correct implementation of the physical model. (C) 2016 Published by Elsevier Inc.

“Nudge units” within governments, most notably in the United Kingdom and the United States, seek to encourage people to behave a certain way by using insights gained from behavioral science. The aim is to influence people’s choices through policies that offer the right incentive or hurdle so that people choose the more economically beneficial options. Getting people to save for retirement, eat more healthful foods, and pay their taxes on time are some examples of institutionally desirable activities. The 10-fold rise in “nudge” projects undertaken since 2010—more than 20 countries have deployed or expressed interest in them—have revealed many lessons for policymakers. Chief among these lessons: the necessity of obtaining buy-in from key political leaders and other stakeholders, and the benefits of testing multiple intervention strategies at once. Although detailed cost–benefit analyses are not yet available, we estimate that behaviorally inspired interventions can help government agencies save hundreds of millions of dollars per year.

We introduce the anti-symmetric representation of the extended magnetohydrodynamic (MHD) equations. In this representation, the use of the anti-symmetric flux operator ( ∇ · v + v · ∇ ) results in conservation theorems with discrete analogs. Inherently robust numerical applications are achieved with little effort, and conservation to machine precision is possible with simple numerical schemes. Starting from the two-fluid equations, we construct a single-fluid MHD model based on generalized center-of-mass variables for the mass ( ρ), momentum ( ρ v), and pressure ( p). This model is shown to possess identical conservation properties to the two-fluid system, with the only restriction being the use of a single temperature. Common approximations to the Braginskii heat fluxes and to the gyroviscous stress tensor are cast into our representation for convenience. The discrete conservation properties are verified using the classic Orszag–Tang vortex problem. In addition to the favorable mass, momentum, and energy conservation properties, the time reversibility of the simulations is demonstrated.

Semantic memory retrieval is a function of a search algorithm and a semantic representation. A challenge in studying retrieval has been that different search algorithms on different representations of the same concepts often produce similar results, making theorizing of the underlying processes a slippery endeavor. In this paper we outline a method that bypasses this challenge by estimating representations directly from fluency data. We showcase our method by performing model comparison on existing and new models of memory search. Our results show that the constrained random walk (Austerweil, Abbott, & Griffiths, 2012) and a random walk without repeats (Millsap & Meredith, 1987) are able to fit the data almost equally well across several large and diverse datasets.

We report that the well-known Marangoni film thickening in surfactant-laden Landau–Levich–Bretherton coating flow can be completely suppressed by wall slip. The analysis is made by mainly looking at how the deposited film thickness varies with the capillary number $Ca$ ($\ll 1$) and the dimensionless slip length ${\it\Lambda}={\it\lambda}/R$ ($\ll 1$) in the presence of a trace amount of insoluble surfactant, where ${\it\lambda}$ is the slip length and $R$ is the radius of the meniscus. When slip effects are weak at sufficiently large $Ca$ (but still $\ll 1$) such that $Ca\gg {\it\Lambda}^{3/2}$, the film thickness can still vary as $Ca^{2/3}$ and be thickened by surfactant as if wall slip were absent. However, when slip effects become strong by lowering $Ca$ to $Ca\ll {\it\Lambda}^{3/2}$, the film, especially when surface diffusion of surfactant is negligible, does not get thinner according to the strong-slip quadratic law reported previously (Liao et al., Phys. Rev. Lett., vol. 111, 2013, 136001; Li et al., J. Fluid Mech., vol. 741, 2014, pp. 200–227). Instead, the film behaves as if both surfactant and wall slip were absent, precisely following the no-slip $2/3$ law without surfactant. Effects of surface diffusion are also examined, revealing three distinct regimes as $Ca$ is varied from small to large values: the strong-slip quadratic scaling without surfactant, the no-slip $2/3$ scaling without surfactant and the film thickening along the no-slip $2/3$ scaling with surfactant. An experiment is also suggested to test the above findings.

A strategy of ‘radical incrementalism’ is herein advocated as a useful approach to policy making which makes proper use of evaluation. It is argued that small, incremental changes, supported by small-scale and tightly focused evaluations, are under-utilised as an approach to cost effective policy improvement.

This paper presents two discretisation schemes for the parallel gradient operator used in scrape-off layer plasma turbulence simulations. First, a simple model describing the propagation of electrostatic shear-Alfven waves, and retaining the key elements of the parallel dynamics, is used to test the accuracy of the different schemes against analytical predictions. The most promising scheme is then tested in simulations of limited scrape-off layer turbulence with the flux-driven 3D fluid code GBS (Ricci et al., 2012): the new approach is successfully benchmarked against the original parallel gradient discretisation implemented in GBS. Finally, GBS simulations using a radially varying safety profile, which were inapplicable with the original scheme are carried out for the first time: the well-known stabilisation of resistive ballooning modes at negative magnetic shear is recovered. The main conclusion of this paper is that a simple approach to the parallel gradient, namely centred finite differences in the poloidal and toroidal direction, is able to simulate scrape-off layer turbulence provided that a higher resolution and higher convergence order are used.

The impact of data assimilation on the transports of eastward-flowing Equatorial Undercurrent (EUC) and North Equatorial Countercurrent (NECC) in the Pacific Ocean from 145°E to 95°W during 2004–05 and 2009–11 was assessed. Two Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2), solutions were analyzed: one with data assimilation and one without. Assimilated data included satellite observations of sea surface temperature and ocean surface topography, in which the sampling patterns were approximately uniform over the 5 years, and in situ measurements of subsurface salinity and temperature profiles, in which the sampling patterns varied considerably in space and time throughout the 5 years. Velocity measurements were not assimilated. The impact of data assimilation was considered significant when the difference between the transports computed with and without data assimilation was greater than 5.5 × 106 m3 s−1 (or 5.5 Sv; 1 Sv ≡ 106 m3 s−1) for the EUC and greater than 5.0 Sv for the NECC. In addition, the difference of annual-mean transports computed from 3-day-averaged data was statistically significant at the 95% level. The impact of data assimilation ranged from no impact to very substantial impact when data assimilation increased the EUC transport and decreased the NECC transport. The study’s EUC results had some correspondence with other studies and no simple agreement or disagreement pattern emerged among all studies of the impact of data assimilation. No comparable study of the impact of data assimilation on the NECC has been made.

We investigate the question of how plasma currents circulate and close in the scrape-off-layer (SOL) of convection-limited tokamak plasmas. A simplified two-fluid model describes how currents must evacuate charge at the sheaths due to cross-field currents that are not divergence-free. These include turbulence-driven polarization currents and poloidally asymmetric equilibrium diamagnetic currents. The theory provides an estimate for the radial profile of the floating potential, which reveals a dipolar structure like the one observed experimentally. Simulations with a fluid turbulence code provide evidence for the predicted behaviour of currents and floating potential.

The need for new antimicrobials to treat bacterial infections has led to the use of type II fatty acid synthesis (FASII) enzymes as front-line targets. However, recent studies suggest that FASII inhibitors may not work against the opportunist pathogen Staphylococcus aureus , as environmental fatty acids favor emergence of multi-anti-FASII resistance. As fatty acids are abundant in the host and one FASII inhibitor, triclosan, is widespread, we investigated whether fatty acid pools impact resistance in clinical and veterinary S. aureus isolates. Simple addition of fatty acids to the screening medium led to a 50% increase in triclosan resistance, as tested in 700 isolates. Moreover, nonculturable triclosan-resistant fatty acid auxotrophs, which escape detection under routine conditions, were uncovered in primary patient samples. FASII bypass in selected isolates correlated with polymorphisms in the acc and fabD loci. We conclude that fatty-acid-dependent strategies to escape FASII inhibition are common among S. aureus isolates and correlate with anti-FASII resistance and emergence of nonculturable variants.

International audience; Antimicrobials targeting the fatty acid synthesis (FASII) pathway are being developed as alternative treatments for bacterial infections. Emergence of resistance to FASII inhibitors was mainly considered as a consequence of mutations in the FASII target genes. However, an alternative and efficient anti-FASII resistance strategy, called here FASII bypass, was uncovered. Bacteria that bypass FASII incorporate exogenous fatty acids in membrane lipids, and thus dispense with the need for FASII. This strategy is used by numerous Gram-positive low GC % bacteria, including streptococci, enterococci, and staphylococci. Some bacteria repress FASII genes once fatty acids are available, and "constitutively" shift to FASII bypass. Others, such as the major pathogen Staphylococcus aureus, can undergo high frequency mutations that favor FASII bypass. This capacity is particularly relevant during infection, as the host supplies the fatty acids needed for bacteria to bypass FASII and thus become resistant to FASII inhibitors. Screenings for anti-FASII resistance in the presence of exogenous fatty acids confirmed that FASII bypass confers anti-FASII resistance among clinical and veterinary isolates. Polymorphisms in S. aureus FASII initiation enzymes favor FASII bypass, possibly by increasing availability of acyl-carrier protein, a required intermediate. Here we review FASII bypass and consequences in light of proposed uses of anti-FASII to treat infections, with a focus on FASII bypass in S. aureus. (C) 2017 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM).

To investigate the mechanisms leading to the heat deposition onto the first wall in the Scrape-Off Layer (SOL), we perform dedicated numerical non-linear simulations of the SOL plasma dynamics of a TCV discharge using the GBS code. The simulated parallel heat flux profiles on the limiter agree qualitatively with the experimental ones obtained by means of infrared thermography, showing a double scale length. Non-ambipolar currents are found to flow to the limiter, consistently with the experiments. The contribution of the latter to the total heat flux is discussed. The results of a second simulation identical to the first one but with 40 times higher resistivity are also discussed. Keywords: Plasma, Scrape-Off Layer, TCV, GBS simulations heat flux

In inboard-limited plasmas, the Scrape-Off Layer (SOL) shows two regions: the near SOL, extending a few mm from the Last Closed Flux Surface (LCFS), characterized by a steep gradient of the parallel heat flux radial profile, and a far SOL, typically some cm wide, with flatter heat flux profiles. The physics of the near SOL is investigated in TCV with two series of experiments featuring deuterium and helium plasmas, in which the plasma current, density and elongation have been varied. The parallel heat flux profiles are measured on the limiter by means of infrared thermography. For the first time, the near SOL is reported to disappear for low plasma current or at high density, for values of the SOL collisionality νlowast corresponding to a conduction-limited regime. The power in the near SOL ∆PSOL is shown to decrease with the normalized Spitzer resistivity ν as ∆PSOL ν−1. The floating potential profiles, measured at the limiter using flush-mounted Langmuir probes (LP), show the presence of non-ambipolar currents, and their relation to the presence of a velocity shear layer is discussed. The shearing rate is shown to strictly correlate with the power in the near SOL ∆PSOL, consistently with a recent theoretical model. Measurements of the near SOL on the Low Field Side (LFS) are performed using a reciprocating Langmuir probe (RP). The near SOL is reported to vanish simultaneously at the LFS and at the limiter. The near and far SOL widths are compared with the predictions from existing theoretical models, to which empirical corrections with resistivity and elongation are proposed.

The bacterial pathway for fatty acid biosynthesis, FASII, is a target for development of new anti-staphylococcal drugs. This strategy is based on previous reports indicating that self-synthesized fatty acids appear to be indispensable for Staphylococcus aureus growth and virulence, although other bacteria can use exogenous fatty acids to compensate FASII inhibition. Here we report that staphylococci can become resistant to the FASII-targeted inhibitor triclosan via high frequency mutations in fabD, one of the FASII genes. The fabD mutants can be conditional for FASII and not require exogenous fatty acids for normal growth, and can use diverse fatty acid combinations (including host fatty acids) when FASII is blocked. These mutants show cross-resistance to inhibitors of other FASII enzymes and are infectious in mice. Clinical isolates bearing fabD polymorphisms also bypass FASII inhibition. We propose that fatty acid-rich environments within the host, in the presence of FASII inhibitors, might favour the emergence of staphylococcal strains displaying resistance to multiple FASII inhibitors., The bacterial pathway for fatty acid biosynthesis, FASII, is a target for development of new anti-staphylococcal drugs. Here, Morvan et al. show that exogenous fatty acids can favour the emergence of staphylococcal strains displaying resistance to multiple FASII inhibitors.

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that infernal modes drive fast growing islands on neighbouring rational surfaces. Numerical simulations of such instabilities in a MAST-like configuration are performed with the initial value stability code XTOR-2F in the resistive frame. The evolution of magnetic islands are computed from XTOR-2F simulations and an analytical model is developed based on Rutherford’s theory in combination with a model of resistive infernal modes. The parameter Δ ′ is extended from the linear phase to the non-linear phase. Additionally, the destabilising contribution due to a helically perturbed bootstrap current is considered. Comparing the numerical XTOR-2F simulations to the model, we find that coupling has a strong destabilising effect on (neoclassical) tearing modes and is able to seed 2/1 magnetic islands in situations when the standard NTM theory predicts stability.

This report is the response to a request by the Committee on Space Research of the International Council for Science to prepare a roadmap on observation and integrated Earth-system science for the coming ten years. Its focus is on the combined use of observations and modelling to address the functioning, predictability and projected evolution of interacting components of the Earth system on timescales out to a century or so. It discusses how observations support integrated Earth-system science and its applications, and identifies planned enhancements to the contributing observing systems and other requirements for observations and their processing. All types of observation are considered, but emphasis is placed on those made from space.\ud \ud The origins and development of the integrated view of the Earth system are outlined, noting the interactions between the main components that lead to requirements for integrated science and modelling, and for the observations that guide and support them. What constitutes an Earth-system model is discussed. Summaries are given of key cycles within the Earth system.\ud \ud The nature of Earth observation and the arrangements for international coordination essential for effective operation of global observing systems are introduced. Instances are given of present types of observation, what is already on the roadmap for 2016–2025 and some of the issues to be faced. Observations that are organised on a systematic basis and observations that are made for process understanding and model development, or other research or demonstration purposes, are covered. Specific accounts are given for many of the variables of the Earth system.\ud \ud The current status and prospects for Earth-system modelling are summarized. The evolution towards applying Earth-system models for environmental monitoring and prediction as well as for climate simulation and projection is outlined. General aspects of the improvement of models, whether through refining the representations of processes that are already incorporated or through adding new processes or components, are discussed. Some important elements of Earth-system models are considered more fully.\ud \ud Data assimilation is discussed not only because it uses observations and models to generate datasets for monitoring the Earth system and for initiating and evaluating predictions, in particular through reanalysis, but also because of the feedback it provides on the quality of both the observations and the models employed. Inverse methods for surface-flux or model-parameter estimation are also covered. Reviews are given of the way observations and the processed datasets based on them are used for evaluating models, and of the combined use of observations and models for monitoring and interpreting the behaviour of the Earth system and for predicting and projecting its future.\ud \ud A set of concluding discussions covers general developmental needs, requirements for continuity of space-based observing systems, further long-term requirements for observations and other data, technological advances and data challenges, and the importance of enhanced international co-operation.

The properties of plasma turbulence in a poloidally limited scrape-off layer (SOL) are addressed, with focus on ISTTOK, a large aspect ratio tokamak with a circular cross section. Theoretical investigations based on the drift-reduced Braginskii equations are carried out through linear calculations and non-linear simulations, in two-and three-dimensional geometries. The linear instabilities driving turbulence and the mechanisms that set the amplitude of turbulence as well as the SOL width are identified. A clear asymmetry is shown to exist between the low-field and the high-field sides of the machine. While the comparison between experimental measurements and simulation results shows good agreement in the far SOL, large intermittent events in the near SOL, detected in the experiments, are not captured by the simulations., United States. Department of Energy (Grant DE-FG02-91ER54109)

The liquid lining in small human airways can become unstable and form liquid plugs that close off the airways. Direct numerical simulations are carried out on an airway model to study this airway instability and the flow-induced stresses on the airway walls. The equations governing the fluid motion and the interfacial boundary conditions are solved using the finite-volume method coupled with the sharp interface method for the free surface. The dynamics of the closure process is simulated for a viscous Newtonian film with constant surface tension and a passive core gas phase. In addition, a special case is examined that considers the core dynamics so that comparisons can be made with the experiments of Bian et al. (J. Fluid Mech., vol. 647, 2010, p. 391). The computed flow fields and stress distributions are consistent with the experimental findings. Within the short time span of the closure process, there are large fluctuations in the wall shear stress. Furthermore, dramatic velocity changes in the film during closure indicate a steep normal stress gradient on the airway wall. The computational results show that the wall shear stress, normal stress and their gradients during closure can be high enough to injure airway epithelial cells.

We derive a set of fluid moment equations with inherent consistency and numerical stability, conceived by exploiting the anti-symmetric nature of the plasma flow operator (∇·v+v·∇). The obtained equations can be interpreted as an alternative to the traditional Eulerian and Lagrangian representations—one in which plasma flows generate infinitesimal rotations of generalized fluid moments n, nv, and p. The continuous model has a discrete analog with exact mass, momentum, and energy conservation, which is achieved by construction through vanishing integrals of the anti-symmetric flow terms. Positivity preservation is obtained through the use of the generalized moment quantities. The conservation properties of the approach are illustrated in simulations of seeded blob propagation, where we verify numerical conservation to machine accuracy.

The opinions of the minority risk creating a dangerous inroad into Salamon and Caparo. The opinions of the majority avoid that risk but reach the right result by tortuous reasoning. The answer to the case lies in a proper application of Caparo.

The liquid lining in small human airways can become unstable and form liquid plugs that close off the airways. Bench-top experiments have been performed in a glass capillary tube as a model airway to study the airway instability and the flow-induced stresses on the airway walls. A microscale particle image velocimetry system is used to visualize quantitatively the flow fields during the dynamic process of airway closure. An annular film is formed by injecting low-viscosity Si-oil into the glycerol-filled capillary tube. The viscosity ratio between these two fluids is similar to that between water and air. The thickness of the film varies with the infusion rate of the core fluid, which is controlled by a syringe pump. After a uniform film is formed, the syringe pump is shut off so that the core flow speed is close to zero during closure. Instantaneous velocity fields in the annular film at various stages of airway closure are computed from the images and analysed. The wall shear stress at the instant when a liquid plug forms is found to be approximately one order of magnitude higher than the exponential growth period before closure. Within the short time span of the closure process, there are large wall shear stress fluctuations. Furthermore, dramatic velocity changes in the film flow during closure indicate a steep normal stress gradient on the airway wall. The experimental results show that the wall shear stress during closure can be high enough to injure airway epithelial cells. An airway that experiences closure and reopening cyclically during breathing could be injured from fluid forces during both phases of the cycle (i.e. inspiration and expiration).

We describe the mechanisms by which liquids and surfactants can be delivered into the pulmonary airways. These are instilled and transported throughout the lung in clinical therapies such as surfactant replacement therapy, partial liquid ventilation and drug delivery. The success of these treatments is contingent on the liquid distribution and the delivery to targeted regions of the lung. The targeting of a liquid plug can be influenced by a variety of factors such as the physical properties of the liquid, the interfacial activity, the gravitational orientation, instillation method and propagation speed. We provide a review of experimental and theoretical studies that examine these effects in single tubes or channels, in tubes with single bifurcations and in the whole lung.

The nonlinear development of the interfacial-surfactant instability is studied for the semi-infinite plane Couette film flow. Disturbances whose spatial period is close to the marginal wavelength of the long-wave instability are considered first. Appropriate weakly nonlinear partial differential equations (PDEs) which couple the disturbances of the film thickness and the surfactant concentration are obtained from the strongly nonlinear lubrication-approximation PDEs. In a rescaled form each of the two systems of PDEs is controlled by a single parameter C, the ‘shear-Marangoni number’. From the weakly nonlinear PDEs, a single Stuart–Landau ordinary differential equation (ODE) for an amplitude describing the unstable fundamental mode is derived. By comparing the solutions of the Stuart–Landau equation with numerical simulations of the underlying weakly and strongly nonlinear PDEs, it is verified that the Stuart–Landau equation closely approximates the small-amplitude saturation to travelling waves, and that the error of the approximation converges to zero at the marginal stability curve. In contrast to all previous stability work on flows that combine interfacial shear and surfactant, some analytical nonlinear results are obtained. The Hopf bifurcation to travelling waves is supercritical for C < Cs and subcritical for C > Cs, where Cs is approximately 0.29. This is confirmed with a numerical continuation and bifurcation technique for ODEs. For the subcritical cases, there are two values of equilibrium amplitude for a range of C near Cs, but the travelling wave with the smaller amplitude is unstable as a periodic orbit of the associated dynamical system (whose independent variable is the spatial coordinate). By using the Bloch (‘Floquet’) disturbance modes in the linearized PDEs, it transpires that all the small-amplitude travelling-wave equilibria are unstable to sufficiently long-wave disturbances. This theoretical result is confirmed by numerical simulations which invariably show the large-amplitude saturation of the disturbances. In view of this secondary instability, the existence of small-amplitude periodic solutions (on the real line) bifurcating from the uniform flow at the marginal values of the shear-Marangoni number does not contradict the earlier conclusions that the interfacial-surfactant instability has a strongly nonlinear character, in the sense that there are no small-amplitude attractors such that the entire evolution towards them is captured by weakly-nonlinear equations. This suggests that, in general, for flowing-film instabilities that have zero wavenumber at criticality, the saturated disturbance amplitudes do not always have to decrease to zero as the control parameter approaches its value at criticality.

The study conducted included four school districts that were addressing New York State Chapter 405 citations related to disproportionality. The purpose of this study was to identify the districts' common characteristics related to disproportionality, as well as common approaches and processes used to address the issue. An action research, multi-case study method was used, with the researchers assuming the dual role of consultants and researchers. Data were collected from questionnaires and facilitated focus group discussions. This paper will address both the methods and findings of the study. Implications of the results and recommendations for practice in interdistrict support will be discussed.

In this work, we theoretically explore the characteristics of electroosmostic flow (EOF) in a microcavity with nonuniform surface charges. It is well known that a uniformly charged EOF does not give rise to flow separation because of its irrotational nature, as opposed to the classical problem of viscous flow past a cavity. However, if the cavity walls bear nonuniform surface charges, then the similitude between electric and flow fields breaks down, leading to the generation of vorticity in the cavity. Because this vorticity must necessarily diffuse into the exterior region that possesses a zero vorticity set by a uniform EOF, a new flow structure emerges. Assuming Stokes flow, we employ a boundary element method to explore how a nonuniform charge distribution along the cavity surface affects the flow structure. The results show that the stream can be susceptible to flow separation and exhibits a variety of flow structures, depending on the distributions of zeta potentials and the aspect ratio of the cavity. The interactions between patterned EOF vortices and Moffatt eddies are further demonstrated for deep cavities. This work not only has implications for electrokinetic flow induced by surface imperfections but also provides optimal strategies for achieving effective mixing in microgrooves.

Since the attack on the World Trade Center in New York, and on the Pentagon in the United States, concerns over security issues have been at an all-time high in this country. Both state and federal governments continue to discuss legislation on these issues amid much controversy. One key concern of both employers and employees is the extent that employers, espousing a “need to know” mentality, continue to expand their capability and implementation of surveillance of employees in the workplace. With the technology typically growing faster than the speed of legislation, protective or permissive, the management and legal issues involved in electronic monitoring of employee communications in the workplace, are and well should be on the agenda for discussion of every management and legal team in American business today. Companies have a legitimate right to protect their trade secrets from disclosure by disgruntled employees. Similarly, companies also have a duty to protect their good names and reputations from unauthorized employee communications with outside parties, and even other employees, that may damage them. It is also a prime duty of management to ensure, in their direction of their workforces, that the employees execute their responsibilities by working full time on their stated objectives. In this regard, any management that fails to oversee its workforce to ensure that employees are not expending valuable company time, for which they are being compensated, on personal business, including unauthorized communications, is remiss in its responsibilities to its shareholders. The company may see a reduction of the price of its shares in the marketplace if it does not protect the economic interests of its shareholders.

Online data collection has begun to revolutionize the behavioral sciences. However, conducting carefully controlled behavioral experiments online introduces a number of new of technical and scientific challenges. The project described in this paper, psiTurk, is an open-source platform which helps researchers develop experiment designs which can be conducted over the Internet. The tool primarily interfaces with Amazon's Mechanical Turk, a popular crowd-sourcing labor market. This paper describes the basic architecture of the system and introduces new users to the overall goals. psiTurk aims to reduce the technical hurdles for researchers developing online experiments while improving the transparency and collaborative nature of the behavioral sciences.

A numerical study of pressure driven magnetohydrodynamic (MHD) instabilities in a low-shear tight aspect ratio configuration is presented. When the magnetic shear is sufficiently small over an extended region in the core, enhanced instability occurs due to the coupling to poloidal sidebands, which itself occurs due to toroidicity. Numerical simulations have been performed with the initial value code XTOR-2F both in the ideal and resistive MHD frame. Two-fluid effects (plasma diamagnetic flows) have been retained as well. The predictions of the XTOR-2F code on the amplitude of the growth rate, and on the rotation frequency of the modes, have been compared with analytic linear theory of infernal modes. Qualitative agreement has been found between numerical and analytical results, in spite of the tight aspect ratio configuration. The intermediate scaling gamma similar to S-3/8, predicted by the linear theory (Brunetti et al 2014 Plasma Phys. Control. Fusion 56 075025), is recovered by the numerical results. A study of the nonlinear evolution of the magnetic island of the tearing sideband has been performed and the results from the simulations are compared with Rutherford's theory.

Background Bacteroides sp. are dominant constituents of the human and animal intestinal microbiota require porphyrins (i.e., protoporphyrin IX or iron-charged heme) for normal growth. The highly stimulatory effect of porphyrins on Bacteroides growth lead us to propose their use as a potential determinant of bacterial colonization. However, showing a role for porphryins would require sensitive detection methods that work in complex samples such as feces. Results We devised a highly sensitive semi-quantitative porphyrin detection method (detection limit 1-4 ng heme or PPIX) that can be used to assay pure or complex biological samples, based on Bacteroides growth stimulation. The test revealed that healthy colonized or non-colonized murine and human hosts provide porphyrins in feces, which stimulate Bacteroides growth. In addition, a common microbiota constituent, Escherichia coli, is shown to be a porphyrin donor, suggesting a novel basis for intestinal bacterial interactions. Conclusions A highly sensitive method to detect porphyrins based on bacterial growth is devised and is functional in complex biological samples. Host feces, independently of their microbiota, and E. coli, which are present in the intestine, are shown to be porphryin donors. The role of porphyrins as key bioactive molecules can now be assessed for their impact on Bacteroides and other bacterial populations in the gut. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0616-0) contains supplementary material, which is available to authorized users.

© 2015 IOP Publishing Ltd. We carry out a quantitative comparison between gas puff imaging (GPI) turbulence measurements in Alcator C Mod inner wall limited discharges (Zweben et al 2009 Phys. Plasmas 18 082505) and 3D flux driven drift reduced Braginskii turbulence simulations of scrape off layer dynamics. The comparison is carried out for a series of inner wall limited discharges where the magnetic field and the density are varied. The comparison between GPI data and non linear simulations yields overall good agreement for several observables such as the Da emission levels and intermittency the radial and poloidal correlation lengths and propagation velocities and the power and frequency spectral density.

Carcinosarcomas are very uncommon tumors, which are comprised of both malignant epithelial and mesenchymal elements. They occur most commonly in the head and neck, respiratory tract, and female reproductive organs. In the gastrointestinal tract, they are most often found in the oropharynx, esophagus, and, to a lesser extent, in the stomach. Carcinosarcomas rarely originate from the colon, but when they do, they are extremely aggressive malignancies. We report the radiologic and pathologic findings of a patient with a carcinosarcoma believed to have arisen from the colon and which involved the adjacent mesentery and omentum.

We investigate the unsteady motion of a long bubble advancing under either prescribed pressure p(b) or prescribed volume flux q(b) into a fluid-filled flexible-walled channel at zero Reynolds number, an idealized model for the reopening of a liquid-lined lung airway. The channel walls are held under longitudinal tension and are supported by external springs; the bubble moves with speed U. Provided p(b) exceeds a critical pressure p(crit) the system exhibits two types of steady motion. At low speeds, the bubble acts like a piston, slowly pushing a column of fluid ahead of itself, and U decreases with increasing p(b). At high speeds, the bubble rapidly peels the channel walls apart and U increases with increasing p(b.) Using two independent time-dependent simulation techniques (a two-dimensional boundary-element method and a one-dimensional asymptotic approximation), we show that with prescribed p(b) > p(crit), peeling motion is stable and the steady pushing solution is unstable; for p(b) > p(crit) the system ultimately exhibits unsteady pushing behaviour for which U continually diminishes with time. When q(b) is prescribed, peeling motion (with large q(b)) is again stable, but pushing motion (with small q(b)) loses stability at long times to a novel instability leading to spontaneous relaxation oscillations of increasing amplitude and period, for which the bubble switches abruptly between slow unsteady pushing and rapid quasi-steady peeling. This stick-slip motion is characterized using a third-order lumped-parameter model which in turn is reduced to a nonlinear map. Implications for the inflation of occluded lung airways are discussed.

Soluble surfactant and airway surface liquid transport are examined using a mathematical model of Marangoni flows which accounts for airway branching and for cyclic airway stretching. Both radial and longitudinal wall strains are considered. The model allows for variation of the amplitude and frequency of the motion, as may occur under a variety of ventilatory situations occurring during surfactant replacement therapy. The soluble surfactant dynamics of the thin fluid film are modeled by linear sorption. The delivery of surfactants into the lung is handled by setting the proximal boundary condition to a higher concentration compared to the distal boundary condition. Starting with a steady-state, nonuniform, surfactant distribution, we find that transport of surfactant into the lung is enhanced for increasing strain amplitudes. However, for fixed amplitude, increasing frequency has a smaller effect. At small strain amplitudes, increasing frequency enhances transport, but at large strain amplitudes, increasing cycling frequency has the opposite effect.

In this paper, the stability of core–annular flows consisting of two immiscible fluids in a cylindrical tube with circular cross-section is examined. Such flows are important in a wide range of industrial and biomedical applications. For example, in secondary oil recovery, water is pumped into the well to displace the remaining oil. It is also of relevance in the lung, where a thin liquid film coats the inner surface of the small airways of the lungs. In both cases, the flow is influenced by a surface-tension instability, which may induce the breakup of the core fluid into short plugs, reducing the efficiency of the oil recovery, or blocking the passage of air in the lung thus inducing airway closure. We consider the stability of a thin film coating the inner surface of a rigid cylindrical tube with the less viscous fluid in the core. For thick enough films, the Rayleigh instability forms a liquid bulge that can grow to eventually create a plug blocking the tube. The analysis explores the effect of an oscillatory core flow on the interfacial dynamics and particularly the nonlinear stabilization of the bulge. The oscillatory core flow exerts tangential and normal stresses on the interface between the two fluids that are simplified by uncoupling the core and film analyses in the thin-film high-frequency limit of the governing equations. Lubrication theory is used to derive a nonlinear evolution equation for the position of the air–liquid interface which includes the effects of the core flow. It is shown that the core flow can prevent plug formation of the more viscous film layer by nonlinear saturation of the capillary instability. The stabilization mechanism is similar to that of a reversing butter knife, where the core shear wipes the growing liquid bulge back on to the tube wall during the main tidal volume stroke, but allows it to grow back as the stoke and shear turn around. To be successful, the leading film thickness ahead of the bulge must be smaller than the trailing film thickness behind it, a requirement necessitating a large enough core capillary number which promotes a large core shear stress on the interface. The core capillary number is defined to be the ratio of core viscous forces to surface tension forces. When this process is tuned correctly, the two phases balance and there is no net growth of the liquid bulge over one cycle. We find that there is a critical frequency above which plug formation does not occur, and that this critical frequency increases as the tidal volume amplitude of the core flow decreases.

This article reviews the current state of the debate about the political orientation and social attitudes of young people. After cautioning against a pessimistic view of moral decline, the article reports the results from a survey of 1249 young people in Hertfordshire. While showing evidence of low levels of political knowledge, interest, trust and efficacy, the findings do not confirm a lack of engagement with the wider social world. They show that young people contribute to social capital, by volunteering, for example, and that young people have broadly developed moral awareness. We explore students' engagement in citizenship-type activities both within and outside school; the extent to which they have covered the citizenship National Curriculum in school; and the degree to which they are active participants in their school. Our findings are generally positive, identifying reasonably high levels of engagement and integration. In short, there is a base from which to develop curricular reforms to promote ...

A simplified model is developed for an alveolar liquid lining undergoing cyclic stretching which mimics breathing motions. A thin, viscous film coats an extensible alveolar wall with small aspect ratio, $\varepsilon$ . Scaling analysis and asymptotic theory are used to describe the interface profile and surfactant distribution during the oscillation cycle for either insoluble or soluble surfactants. The flow consists of two distinct regimes: an outer region away from the rigid endwalls where flow is near-parallel and a boundary-layer region at the rigid endwalls where flow is non-parallel. The system is solved asymptotically in the limit of $\varepsilon\ll 1$ and small strain amplitudes, $\Delta \ll 1$ . For leading order in $\varepsilon$ , steady streaming vortical flows are found at $O(\Delta^2)$ and their size, number and flow direction depend on the system parameter values. This preliminary model can be useful for understanding alveolar transport characteristics for slowly diffusing molecules with large Peclet number, such as endogenous surfactants and proteins as well as delivered surfactants, drugs and genetic material that may occur in various therapies or partial liquid ventilation. The flow pattern also provides a pathway for cell–cell signalling within the alveolus.

Creeping flow of a two-layer system with a monolayer of an insoluble surfactant on the interface is considered. The linear-stability theory of plane Couette-Poiseuille flow is developed in the Stokes approximation. To isolate the Marangoni effect, gravity is excluded. The shear-flow instability due to the interfacial surfactant, uncovered earlier for long waves only (Frenkel & Halpern), is studied with inclusion of all wavelengths, and over the entire parameter space of the Marangoni number M, the viscosity ratio m, the interfacial velocity shear s, and the thickness ratio n (≥ 1). The complex wave speed of normal modes solves a quadratic equation, and the growth rate function is continuous at all wavenumbers and all parameter values. If M > 0, s ¬= 0, m 1, the small disturbances grow provided they are sufficiently long wave. However, the instability is not long wave in the following sense: the unstable waves are not necessarily much longer than the smaller of the two layer thicknesses. On the other hand, there are parametric regimes for which the instability has a mid-wave character, the flow being stable at both sufficiently large and small wavelengths and unstable in between

In the context of an international trend toward the renewal of citizenship teaching, this paper reports the results of a survey of citizen education practice in Hertfordshire, England, carried out in June 2000. The research aims to find out if the practice in schools was as negligible as conventional wisdom and existing research suggest. We find out that only 8% of schools claimed not to be doing anything at all; about 17% delivered citizenship as a discrete subject; most schools offered extra-curricular activities which contributed to citizenship education; 80% of mainstream schools provided at least some coverage of most topics; just under 80% of the mainstream schools designated someone to co-ordinate citizenship education; and about one-third (32%) of schools thought citizenship education should be devised at the discretion of each school. Overall the findings convey the diversity of practices, which do not co-vary with the type of school. Our results suggest a more autonomist conception of citizen ed...

We consider two problems in which a semi-infinite bubble moves into a uniformly convergent two-dimensional channel under creeping-flow conditions. In the first (steady) problem, the bubble is stationary with respect to the channel walls, which move away from the channel vertex parallel to themselves, each entraining a liquid film of uniform thickness; the appropriate flux is provided by a line source at the channel vertex. In the second (unsteady) problem, the channel walls are fixed and the bubble is drawn at a constant speed towards the channel vertex by a line sink. In this case the bubble interface assumes a self-similar shape, and wedge-shaped films are deposited on the channel walls. The boundary-element method, supported by asymptotic approximations, is used to compute flows over a range of bubble speeds (measured by a capillary number Ca) and wedge angles α. In the steady problem, the deposited film thickness increases monotonically with α at low Ca, but diminishes with increasing α at sufficiently high Ca. In the unsteady problem, the film thickness was found always to increase with both α and Ca. In both cases, the dimensionless pressure drop across the bubble tip can be nonmonotonic in α. Implications of these results in modeling coating and peeling flows are discussed.

The steady motion at zero Reynolds number of a semi-infinite bubble through a fluid-filled, flexible-walled channel, a model for the reopening of a collapsed lung airway, is described using asymptotic and numerical methods. The channel walls are membranes that are supported by external springs and are held under large longitudinal tension. An asymptotic analysis is presented under the assumption that membrane slopes are uniformly small. Near the bubble tip, the flow is equivalent to that of a semi-infinite bubble in a weakly tapered channel. Key features of this two-dimensional flow are matched to long-wavelength approximations describing the remainder of the solution domain. The analysis is valid for a wide range of bubble speeds, and it takes a particularly simple form when the bubble peels apart the channel walls as it advances. Predictions of bubble pressure as a function of bubble speed are validated by comparison with existing computations, new boundary-element simulations describing bubble motion in a channel with one rigid and one deformable wall, and experiments.

Chapter 1 Introduction and Background: What is mental illness? What is meant by "the planned environment"? Mental illness and the environment: early studies Recurrent methodological issues. Chapter 2 Classical Environmental Stressors: What is environmental stress? Air pollution The seasons, heat, wind and weather Noise New evidence on noise: the effects from road traffic Summary. Chapter 3 Social Environmental Stressors: What is a social environmental stressor? Crowding Crime, fear and the environment Summary and refinements to the stress model. Chapter 4 Social Support and the Planned Environment: Introduction Social networks, social support and mental health Social factors affecting neighbouring behaviour The physical environment and social support Conclusion: the ideal neighbour and the ideal neighbourhood. Chapter 5 The Environment as Symbol and the Example of the High-Rise: Introduction Labelling Aspiration achievement discrepancies The example of the high-rise flat. Chapter 6 The Planning Process: Introduction Relocation and slum-clearance Resident participation in the planning process Case study: demolition!. Chapter 7 Improving Mental Health Through the Environment - A Case Study: Design and methodology About the estate The intervention The impact of the changes The impact on residents' mental health Summary. Chapter 8 Mental Illness and the Planned Environment: Is there a causal relationship between mental illness and the planned environment? Broader implications.