The nonlinear stability of two-dimensional (2-D) plane Couette flow subject to a constant throughflow is analysed at finite and asymptotically large Reynolds numbers $\textit {Re}$. The speed of this throughflow is quantified by the non-dimensional throughflow number $\eta$. The base flow exhibits a linear instability provided $\eta \gtrsim 3.35$, with multi-deck upper and lower branch structures developing in the limit $1\ll \eta \ll \mathit {O}(\textit {Re})$. This instability provides a springboard for the computation of nonlinear travelling waves which bifurcate subcritically from the linear neutral curve, allowing us to map out a neutral surface at different values of $\eta$. Using strongly nonlinear critical layer theory, we investigate the waves that bifurcate from the upper branch at asymptotically large $\textit {Re}$. This asymptotic structure exists provided the throughflow number is larger than the critical value of $\eta _c\approx 1.20$ and is shown to give quantitatively similar results to the numerical solutions at Reynolds numbers of $\mathit {O}(10^5)$.

Iron is essential for many physiological functions of the body, and it is required for normal growth and development. Iron deficiency (ID) is the most common form of micronutrient malnutrition and is particularly prevalent in infants and young children in developing countries. Iron supplementation is considered the most effective strategy to combat the risk of ID and ID anaemia (IDA) in infants, although iron supplements cause a range of deleterious gut-related problems in malnourished children. The purpose of this review is to assess the available evidence on the effect of iron supplementation on the gut microbiota during childhood ID and to further assess whether prebiotics offer any benefits for iron supplementation. Prebiotics are well known to improve gut-microbial health in children, and recent reports indicate that prebiotics can mitigate the adverse gut-related effects of iron supplementation in children with ID and IDA. Thus, provision of prebiotics alongside iron supplements has the potential for an enhanced strategy for combatting ID and IDA among children in the developing world. However, further understanding is required before the benefit of such combined treatments of ID in nutritionally deprived children across populations can be fully confirmed. Such enhanced understanding is of high relevance in resource-poor countries where ID, poor sanitation and hygiene, alongside inadequate access to good drinking water and poor health systems, are serious public health concerns.

With the aim of producing a 3D representation of tumors, imaging and molecular annotation of xenografts and tumors (IMAXT) uses a large variety of modalities in order to acquire tumor samples and produce a map of every cell in the tumor and its host environment. With the large volume and variety of data produced in the project, we developed automatic data workflows and analysis pipelines. We introduce a research methodology where scientists connect to a cloud environment to perform analysis close to where data are located, instead of bringing data to their local computers. Here, we present the data and analysis infrastructure, discuss the unique computational challenges and describe the analysis chains developed and deployed to generate molecularly annotated tumor models. Registration is achieved by use of a novel technique involving spherical fiducial marks that are visible in all imaging modalities used within IMAXT. The automatic pipelines are highly optimized and allow to obtain processed datasets several times quicker than current solutions narrowing the gap between data acquisition and scientific exploitation.

This article contributes to normative debates about residential segregation and its relationship to inequality. It defends a position often disregarded in literature: that there is merit to advancing residential integration through some scenarios where advantaged individuals move to disadvantaged areas. It develops this case in dialogue with three other views. In relation to advocates of addressing the inequalities of residential segregation through redistribution, it defends integration as a means of tackling social and political factors that sustain injustice. It challenges those who defend relocating disadvantaged individuals to advantaged areas by highlighting the burdens and demand for cultural assimilation this imposes on the disadvantaged. It considers the worry that advantaged individuals relocating to disadvantaged areas harbours the problematic features of gentrification. It responds that these concerns, while important in some cases, do not arise in all scenarios of this kind.

Plane Poiseuille flow has long served as the simplest testing ground for Tollmien–Schlichting wave instability. In this paper, we provide a comprehensive comparison of equilibrium Tollmien–Schlichting wave solutions arising from new high-resolution Navier–Stokes calculations and the corresponding predictions of various large-Reynolds-number asymptotic theories developed in the last century, such as double-deck theory, viscous nonlinear critical layer theory and strongly nonlinear critical layer theory. In the relatively small to moderate amplitude regime, the theories excellently predict the behaviour of the numerical solutions at Reynolds numbers of order $10^{6}$ and above, whilst for larger amplitudes our computations suggest the need for further asymptotic theories to be developed.

The recently understood relationship between high-Reynolds-number vortex–wave interaction theory and computationally generated self-sustaining processes provides a possible route to an understanding of some of the underlying structures of fully turbulent flows. Here vortex–wave interaction (VWI) theory is used in the long streamwise wavelength limit to continue the development found at order-one wavelengths by Hall & Sherwin (J. Fluid Mech., vol. 661, 2010, pp. 178–205). The asymptotic description given reduces the Navier–Stokes equations to the so-called boundary-region equations, for which we find equilibrium states describing the change in the VWI as the wavelength of the wave increases from $O(h)$ to $O(Rh)$, where $R$ is the Reynolds number and $2h$ is the depth of the channel. The reduced equations do not include the streamwise pressure gradient of the perturbation or the effect of streamwise diffusion of the wave–vortex states. The solutions we calculate have an asymptotic error proportional to ${R}^{- 2} $ when compared to the full Navier–Stokes equations. The results found correspond to the minimum drag configuration for VWI states and might therefore be of relevance to the control of turbulent flows. The key feature of the new states discussed here is the thickening of the critical layer structure associated with the wave part of the flow to completely fill the channel, so that the roll part of the flow is driven throughout the flow rather than as in Hall & Sherwin as a stress discontinuity across the critical layer. We identify a critical streamwise wavenumber scaling, which, when approached, causes the flow to localize and take on similarities with computationally generated or experimentally observed turbulent spots. In effect, the identification of this critical wavenumber for a given value of the assumed high Reynolds number fixes a minimum box length necessary for the emergence of localized structures. Whereas nonlinear equilibrium states of the Navier–Stokes equations are thought to form a backbone on which turbulent flows hang, our results suggest that the localized states found here might play a related role for turbulent spots.

In this article I consider two consequentialist positions on whether individuals in affluent countries ought to purchase Fair Trade goods. One is a narrow argument, which asserts that individuals should purchase Fair Trade goods because this will have positive direct effects on poverty reduction, by, for example, channelling money into development. I argue that this justification is insufficient to show that individuals should purchase Fair Trade goods because individuals could achieve similar results by donating money to charity and, therefore, without purchasing Fair Trade goods. The second position has a wider focus. It notes both the direct effects of purchasing Fair Trade goods and possible indirect effects, such as the impact this might have on other individuals. I argue that certain actions, of which Fair Trade is one example, will be more likely to encourage individuals who would not otherwise contribute to poverty reduction to contribute and that this may produce additional positive value. Although space prohibits specific conclusions about Fair Trade, I note that considerations of this kind could give us reason to purchase such goods beyond those that issue from the direct effects of doing so and that, as such, they are crucial for determining whether individuals should purchase Fair Trade goods.

The high-Reynolds-number stability of unsteady pipe flow to axisymmetric disturbances is studied using asymptotic analysis. It is shown that as the disturbance amplitude is increased, nonlinear effects first become significant within the critical layer, which moves away from the pipe wall as a result. It is found that the flow stabilizes once the basic profile has become sufficiently fully developed. By tracing the nonlinear neutral curve back to earlier times, it is found that in addition to the wall mode, which arises from a classical upper branch linear stability analysis, there also exists a nonlinear neutral centre mode, governed primarily by inviscid dynamics. The centre mode problem is solved numerically and the results show the existence of a concentrated region of vorticity centred on or close to the pipe axis and propagating downstream at almost the maximum fluid velocity. The connection between this structure and the puffs and slugs of vorticity observed in experiments is discussed.

Nutrition support is an important part of care management in critically ill patients, not only to prevent and treat malnutrition but also it has a significant impact on recovery from illness and overall outcome. There is little information available about present nutritional support practice for patients in intensive care units (ICU) in the UK. This survey was designed to evaluate the present nutrition support practice in ICU and high dependency units (HDU) in England. Data were gathered by a 72 h phone survey from 245 ICU and HDU in 196 hospitals in England. A questionnaire was completed over the telephone, including general information, nutrition support and teams involved in the nutrition management in the ICU. Of 1286 total patients in the ICU, 703 (54·6 %) were receiving nasogastric feeding, two (1·5 %) were receiving feeding via a percutaneous endoscopically placed gastrostomy tube and two (1·5 %) were receiving nasojejunal feeding. One hundred and forty-seven (11·4 %) patients were on parenteral feeding during the study period. A nutrition support team was not available in 158 (83·1 %) ICU and there was no dietitian or specialist nutrition nurse to cover ICU in nine (4·7 %) hospitals. In conclusion, the present survey reported an increased trend in usage of enteral feeding in ICU in England, and a reduction in the use of parenteral nutrition compared with previous surveys. However, we are still far from integrating nutrition into care management in the ICU.

The diatom, Phaeodactylum tricornutum is a common inhabitant of inshore waters and can exist in different morphotypes that are thought to be adapted for survival in different habitats. Despite this diatom being widely used for physiological and genetic studies of microalgae, little is known about biochemical or physiological differences between the cell morphotypes. The present study was aimed at comparing differences in the antibacterial properties of the fusiform and oval morphotypes, the dominant cell types found in laboratory cultures of most strains of P. tricornutum. In cultures differing in proportions of fusiform and oval cells, there is a significant and positive correlation between the proportion of cells in the fusiform morphotype and the antibacterial activity of cell extracts. Extracts prepared from cultures enriched for fusiform cells (~76%) show greater antibacterial activity against the Gram-positive bacterium, Staphylococcus aureus, than those prepared from pure (100%) oval cultures. Thus fusiform cells contain greater antibacterial activity per cell compared to the ovals. Gas–liquid chromatographic analyses of the extracts reveal that those from enriched fusiform populations contain significantly greater levels of the free fatty acids, eicosapentaenoic acid (EPA), hexadecatrienoic acid (HTA) and palmitoleic acid (PA) than the pure oval cell cultures. These free fatty acids from P. tricornutum have been previously shown by us to have potent antibacterial activity against S. aureus. Free fatty acids, released from damaged microalgal cells, defend the microalgal population against grazing predators but, here, we suggest that these free fatty acids could also act against pathogenic bacteria in the vicinity of the algae. As cell extracts from the fusiform cells contain greater quantities of these fatty acids, fusiform cells may have greater potential than the ovals for this type of protection.