We present a dataset of 1,119 radiocarbon dates and their contexts for Oaxaca, Mexico, a best effort to include all published dates, plus hundreds of unpublished samples. We illustrate its potential and limitations with five examples: (1) dated stratigraphy in stream cutbanks show how aggradation, downcutting, and stability responded to global climate and human activities; (2) 14C samples from Late/Terminal Formative contexts allow interregional comparisons of temple and palace construction, use, and abandonment; (3) new 14C dates provide better understanding of events during the Late Classic/Epiclassic, a problematic time in the ceramic chronology; (4) individual Classic/Postclassic residential contexts had long durations—several hundred years; and (5) model constraints from other data permit refinement at times of calibration curve deviation, as during AD 1400–1600. We recommend further chronological refinement with best-practice standards, new samples, existing collections, and statistical modeling.

Policy-makers are paying increasing attention to ecosystem services, given improved understanding that they underpin human well-being, and following their integration within the Aichi Targets of the Convention on Biological Diversity. Decision-makers need information on trends in biodiversity and ecosystem services but tools for assessing the latter are often expensive, technically demanding and ignore the local context. In this study we used a simple, replicable participatory assessment approach to gather information on ecosystem services at important sites for biodiversity conservation in Nepal, to feed into local and national decision-making. Through engaging knowledgeable stakeholders we assessed the services delivered by Nepal's 27 Important Bird and Biodiversity Areas, the pressures affecting services through impacts on land cover and land use, and the consequences of these for people. We found that these sites provide ecosystem services to beneficiaries at a range of scales but under current pressures the balance of services will change, with local communities incurring the greatest costs. The approach provided valuable information on the trade-offs between ecosystem services and between different people, developed the capacity of civil society to engage in decision-making at the local and national level, and provided digestible information for Nepal's government. We recommend this approach in other countries where there is a lack of information on the likely impacts of land-use change on ecosystem services and people.

A direct numerical simulation of a Batchelor vortex has been carried out in the presence of freely decaying turbulence, using both periodic and symmetric boundary conditions; the latter most closely approximates typical experimental conditions, while the former is often used in computational simulations for numerical convenience. The higher-order velocity statistics were shown to be strongly dependent upon the boundary conditions, but the dependence could be mostly eliminated by correcting for the random, Gaussian modulation of the vortex trajectory, commonly referred to as ‘wandering’, using a technique often employed in the analysis of experimental data. Once this wandering had been corrected for, the strong peaks in the Reynolds stresses normally observed at the vortex centre were replaced by smaller local extrema located within the core region but away from the centre. The distributions of the corrected Reynolds stresses suggest that the formation and organization of secondary structures within the core is the main mechanism in turbulent production during the linear growth phase of vortex development.

The measurement of vortex flows with particle-image velocimetry (PIV) is particularly susceptible to error arising from the finite mass of the tracer particles, owing to the high velocities and accelerations typically experienced. A classical model of Stokes-flow particle transport is adopted, and an approximate solution for the case of particle transport within an axisymmetric, quasi-two-dimensional Batchelor $q$ -vortex is presented. A generalized expression for the maximum particle tracking error is proposed for each of the velocity components, and the importance of finite particle size distributions is discussed. The results indicate that the tangential velocity component is significantly less sensitive to tracking error than the radial component, and that the conventional particle selection criterion (based on the particle Stokes number) may result in either over- or under-sized particles for a specified allowable error bound. Results were demonstrated by means of PIV measurements carried out in air and water using particles with very different properties.

The streamwise velocity component is studied in fully developed turbulent channel flow for two very rough surfaces and a smooth surface at comparable Reynolds numbers. One rough surface comprises sparse and isotropic grit with a highly non-Gaussian distribution. The other is a uniform mesh consisting of twisted rectangular elements which form a diamond pattern. The mean roughness heights (±) the standard deviation) are, respectively, about 76(±42) and 145(±150) wall units. The flow is shown to be two-dimensional and fully developed up to the fourth-order moment of velocity. The mean velocity profile over the grit surface exhibits self-similarity (in the form of a logarithmic law) within the limited range of 0.04≤y/h≤0.06, but the profile over the mesh surface does not, even though the mean velocity deficit and higher moments (up to the fourth order) all exhibit outer scaling over both surfaces. The distinction between self-similarity and outer similarity is clarified and the importance of the former is explained. The wake strength is shown to increase slightly over the grit surface but decrease over the mesh surface. The latter result is contrary to recent measurements in rough-wall boundary layers. Single- and two-point velocity correlations reveal the presence of large-scale streamwise structures with circulation in the plane orthogonal to the mean velocity. Spanwise correlation length scales are significantly larger than corresponding ones for both internal and external smooth-wall flows.

The effects of nitrogen ion implantation of Ti-6AI-4V alloy on growth of Pseudomonas aeruginosa bacteria on surfaces of the alloy have been investigated. Results for ion implanted samples were compared with controls with similarly smoothly polished surfaces and with controls that had intentionally roughened surfaces. The test consisted of exposing sterile alloy samples to a microbiological broth, to which 24 hour-old cultures of Pseudomonas aeruginosa had been added. After bioassociation at normal temperature 37°C, bacteria adhering to the surface were fixed and treated with a new ruthenium tetroxide staining method, and quantified by use of scanning electron microscopy (SEM), back-scattered electron imaging and EDAX energy dispersive microanalysis. For smooth samples of the alloy, after a 12 hour growth period, the retained bacteria (revealed by the biologically incorporated ruthenium), decreased monotonically with nitrogen dose out to a total fluence of approximately 7 × 1017/cm2 in an affected depth of approximately 0.1500 μm. The SEM confirmed that the Pseudomonas aeruginosa adhered equally to control materials. The ruthenium studies revealed that the amount of bacterial adhesion is indirectly proportional to the nitrogen ion implantation of the titanium. The greater the percentage of nitrogen ion implantation in the titanium alloy, the less bacteria colonized the disk.