The expensive-tissue hypothesis (ETH) posited a brain–gut trade-off to explain how humans evolved large, costly brains. Versions of the ETH interrogating gut or other body tissues have been tested in non-human animals, but not humans. We collected brain and body composition data in 70 South Asian women and used structural equation modelling with instrumental variables, an approach that handles threats to causal inference including measurement error, unmeasured confounding and reverse causality. We tested a negative, causal effect of the latent construct ‘nutritional investment in brain tissues’ (MRI-derived brain volumes) on the construct ‘nutritional investment in lean body tissues’ (organ volume and skeletal muscle). We also predicted a negative causal effect of the brain latent on fat mass. We found negative causal estimates for both brain and lean tissue (−0.41, 95% CI, −1.13, 0.23) and brain and fat (−0.56, 95% CI, −2.46, 2.28). These results, although inconclusive, are consistent with theory and prior evidence of the brain trading off with lean and fat tissues, and they are an important step in assessing empirical evidence for the ETH in humans. Analyses using larger datasets, genetic data and causal modelling are required to build on these findings and expand the evidence base.

The Hierarchical Taxonomy of Psychopathology (HiTOP) has emerged out of the quantitative approach to psychiatric nosology. This approach identifies psychopathology constructs based on patterns of co-variation among signs and symptoms. The initial HiTOP model, which was published in 2017, is based on a large literature that spans decades of research. HiTOP is a living model that undergoes revision as new data become available. Here we discuss advantages and practical considerations of using this system in psychiatric practice and research. We especially highlight limitations of HiTOP and ongoing efforts to address them. We describe differences and similarities between HiTOP and existing diagnostic systems. Next, we review the types of evidence that informed development of HiTOP, including populations in which it has been studied and data on its validity. The paper also describes how HiTOP can facilitate research on genetic and environmental causes of psychopathology as well as the search for neurobiologic mechanisms and novel treatments. Furthermore, we consider implications for public health programs and prevention of mental disorders. We also review data on clinical utility and illustrate clinical application of HiTOP. Importantly, the model is based on measures and practices that are already used widely in clinical settings. HiTOP offers a way to organize and formalize these techniques. This model already can contribute to progress in psychiatry and complement traditional nosologies. Moreover, HiTOP seeks to facilitate research on linkages between phenotypes and biological processes, which may enable construction of a system that encompasses both biomarkers and precise clinical description.

Weed competition in soybeans [Glycine max (L.) Merr. ‘Clark 63′] with planted stands of velvetleaf (Abutilon theophrasti Medic.), prickly sida (Sida spinosa L.), and Venice mallow (Hibiscus trionum L.) is reported. Weeds were planted 0, 10, 20, 30, and 40 days after soybeans and competed until soybeans matured. Soybean seed yields were reduced 720, 250, and 230 kg/ha by velvetleaf, Venice mallow, and prickly sida, respectively. Weeds that emerged with soybeans reduced yields 1,010 kg/ha. Weeds planted 10 days later reduced yields 480 kg/ha, but weeds planted 20 to 40 days after soybeans did not significantly reduced yield. Soybean yields were reduced regardless of weed placement in or between soybean rows. Weed competition reduced numbers of soybean pods per plant more than other soybean-yield components.

Competition studies were conducted with soybeans Glycine max. (L.) Merr. ‘Clark 63’ and Venice mallow (Hibiscus trionum L.). One Venice mallow per 7.5 cm of soybean row reduced soybean seed yield 632 kg/ha after 85 days competition. Thirty to 40-cm weed bands in and between soybean rows reduced yields 270 to 651 kg/ha with 35 to 40 days of competition. A natural stand of 215 Venice mallow plants per square meter reduced soybean yield 454 kg/ha after 30 days of competition, and competition up to 110 days reduced yield as much as 1490 kg/ha. Weed competition affected the number of pods per soybean plant more than any other seed-yield component, and soybean height was reduced. Soybean yields were reduced more when soil moisture was abundant early in the growing season and limited in late summer than when moisture was limited early in the growing season and above average until soybeans matured.

In paediatric practice, mean reference energy requirements for groups are often used to predict individual infant energy requirements. References from the FAO/WHO/United Nations University are based on infants not fed according to the current infant feeding recommendations. The objective of the present study was to measure total energy expenditure (TEE) and determine energy requirements using criterion methods, and validate the use of TEE prediction equation and mean energy requirement references for predicting individual TEE and energy requirements, respectively, in infants who were exclusively breast-fed (EBF) to 6 months of age. EBF infants were included from Greater Glasgow for measurements at 3·5 (n 36) and 6 (n 33) months of age. TEE was measured using doubly labelled water and energy requirements were determined using the factorial approach. TEE and energy requirements were also predicted using equations based on body weight. Relationships between criterion methods and predictions were assessed using correlations. Paired t tests and Bland–Altman plots were used to assess agreement. At the population level, predicted and measured TEE were similar. The energy requirement reference significantly underestimated energy requirements by 7·2 % at 3·5 months at the population level, but there was no bias at 6 months. Errors at individual levels were large and energy requirements were underestimated to a larger extent for infants with higher energy requirements. This indicates that references presently used in clinical practice to estimate energy requirements may not fully account for the different growth pattern of EBF infants. More studies in infants EBF to 6 months of age are needed to understand how growth of EBF infants influences energy requirements.

The turbulent flow development was examined for a two-dimensional boundary layer over a bump. The upstream boundary layer had a momentum-thickness. Reynolds number of approximately 4030. The ratios of upstream boundary layer thickness to bump height and convex radius of curvature were 1.5 and 0.06, respectively. The bump was defined by three tangential circular arcs, which subjected the flow to alternating signs of pressure gradient and surface curvature. The boundary layer grew rapidly on the downstream side of the bump but did not separate. The mean velocity profiles deviated significantly from the law of the wall above the bump. The change from concave to convex surface curvature near the leading edge triggered an internal boundary layer, as shown by knee points in the turbulent stress profiles. The internal layer grew rapidly away from the wall on the downstream side of the bump owing to the adverse pressure gradient. The effect of convex surface curvature was considered small since the flow behaviour was generally explained by the effects due to streamwise pressure gradient. A second internal layer was triggered by the change from convex to concave curvature near the trailing edge. The boundary layer recovered rapidly in the downstream section and approached typical flat-plate boundary layer behaviour at the last measurement location.

The interactions between small dense particles and fluid turbulence have been investigated in a downflow fully developed channel in air. Particle velocities of, and fluid velocities in the presence of, 50 μm glass, 90 μm glass and 70 μm copper spherical beads were measured by laser Doppler anemometry, at particle mass loadings up to 80%. These particles were smaller than the Kolmogorov lengthscale of the flow and could respond to some but not all of the scales of turbulent motion. Streamwise mean particle velocity profiles were flatter than the mean fluid velocity profile, which was unmodified by particle loading. Particle velocity fluctuation intensities were larger than the unladen-fluid turbulence intensity in the streamwise direction but were smaller in the transverse direction. Fluid turbulence was attenuated by the addition of particles; the degree of attenuation increased with particle Stokes number, particle mass loading and distance from the wall. Turbulence was more strongly attenuated in the transverse than in the streamwise direction, because the turbulence energy is at higher frequencies in the transverse direction. Streamwise turbulence attenuation displayed a range of preferred frequencies where attenuation was strongest.

The evolution of the turbulent boundary layer over a bump defined by three tangential circular arcs and swept at 45° was examined. The flat-plate boundary layer approaching the swept bump had a momentum thickness Reynolds number of approximately 3800. The ratios of upstream boundary-layer thickness to bump height and convex radius of curvature were 1.5 and 0.06, respectively. The boundary layer was influenced by alternating signs of streamwise pressure gradient, wall curvature, and mean crossflow, which resulted in a complex boundary-layer flow that grew rapidly on the downstream side of the bump. The mean flow profiles deviated significantly from typical logarithmic layer behaviour, but the flow remained attached. The evolution of the Reynolds stress components was explained by the growth of two internal layers triggered by discontinuities in wall curvature near the leading and trailing edges of the bump. The shear stress vector was found to lag the velocity gradient vector, despite the spanwise flow changing direction above the bump. The measurements were compared to the previous results from a two-dimensional bump with the same profile shape and Reynolds number. Contrary to previous studies, the addition of mean crossflow to this complex flow field did not reduce the vertical mixing relative to the turbulent kinetic energy.

High-resolution laser-Doppler anemometer measurements were acquired in a two-dimensional turbulent boundary layer over a $4^\circ$ ramp. The goals were to provide a detailed data set for an adverse pressure gradient boundary layer far from separation and to examine near-wall behaviour of the Reynolds stresses as compared to flat-plate boundary layers. The flow develops over a flat plate, reaching a momentum thickness Reynolds number of 3350 at an upstream reference location. The boundary layer is then subjected to a varying pressure gradient along the length of the ramp and partially redevelops on a downstream flat plate. Mean velocity measurements show a log law region in all velocity profiles, but the outer layer does not collapse in deficit coordinates indicating that the boundary layer is not in equilibrium. Measurements of non-dimensional stress ratios and quadrant analysis of the two-component data indicate relatively small changes to the turbulence structure. However, the streamwise normal stress has an extended outer layer plateau, and the shear stress and wall-normal stress have outer layer peaks. Near the wall, the streamwise normal stress and shear stress collapse with flat-plate data using standard scaling, but the wall normal stress is substantially larger than flat-plate cases.

Measurements in the turbulent momentum and thermal boundary layers on a rotating disk with a uniform heat flux surface are described for Reynolds numbers up to 106. Measurements include mean velocities and temperatures, all six Reynolds stresses, turbulent temperature fluctuations, and three turbulent heat fluxes. The mean velocity profiles have no wake region, but the mean temperature profiles do. The turbulent temperature fluctuations have a large peak in the outer layer, and there is a third turbulent heat flux in the cross-flow direction. Correlation coefficients and structure parameters are not constant across the boundary layer as they are in two-dimensional boundary layers (2DBLs), and their values are lower. The turbulent Prandtl number agrees with 2DBL values in the lower part of the outer region but is reduced from the 2DBL values higher in the boundary layer. In the outer region of the boundary layer, the transport processes differ significantly from what is observed in two-dimensional turbulent boundary layers: ejections dominate the transport of momentum while both ejections and sweeps contribute to the transport of the passive scalar.

We study the stability of linear filters associated with certain types of linear difference equations with variable coefficients. We show that stability is determined by the locations of the poles of a rational transfer function relative to the spectrum of an associated weighted shift operator. The known theory for filters associated with constant-coefficient difference equations is a special case.

We obtain automatic continuity results for finite-rank perturbations of causal sequence space operators, and provide examples to illustrate cases where automatic continuity does not hold.

Associations between affective disorders, anxiety disorders, and substance use disorders were examined in epidemiological studies conducted in Germany, Switzerland, Puerto Rico, and the mainland US. There was a remarkable degree of similarity across studies in the magnitude and type of specific disorders associated with the affective disorders. Comorbidity with affective disorders was greater for the anxiety disorders than for substance misuse. Panic disorder was the subtype of anxiety that was most highly comorbid with depression. Social phobia was the specific phobic type with the strongest association with the affective disorders. The magnitude of associations between substance misuse and affective disorders generally was quite low and less consistent across sites. No major differences were found in the patterns of comorbidity by gender or age group, affective subtype or prevalence period. The onset of anxiety disorders generally preceded that of depression, whereas alcohol misuse was equally likely to pre- or post-date the onset of affective disorders. Finally, comorbidity was associated with an elevation in treatment ratesacross all sites, confirming Berkson's paradox on an international level.

We report on the further development of an ion source for producing intense, continuous beams of large positive and negative cluster ions comprised of high temperature materials. This device, the Smoke-Ion Source, is the result of combining inert gas condensation methods with techniques for injecting electrons directly into expanding jets. We demonstrate the capability of this ion source to generate strong beams of cluster ions comprised of materials including metals, semiconductors, and metal oxide ceramics.