Hunter-gatherer and Environmental Relations during the Mesolithic of Atlantic Europe.

Environmental change is a major concern for society today. This concern extends the flooding of people’s homes, the reduction of biodiversity due to habitat loss, and the threat to economic prosperity where it is dependent upon the exploitation of wild resources. In terms of past climate change there has been significant amounts of research conducted into the Pleistocene to Holocene transition. This project explores the evidence for environmental change, of a less severe yet potentially disruptive amplitude, and its influence on the behaviour and decisions of Mesolithic hunter-gatherers on the Atlantic façade of Europe. The archaeological record is reviewed with a particular focus on the 8.2K cal bp event and the 2nd half of the 5th millennium cal BC. The resulting datasets are interrogated utilising a multiproxy approach and consideration is given to that which is archaeologically visible and that which is not. The limitations of the archaeological record are addressed through the development of new methodologies and interpretative frameworks. The findings are significant, as the severity of the 8.2k cal bp event at northern latitudes is confirmed, although this falls short of being able to assert a total abandonment at higher latitudes. During the 5th millennium cal BC, a period of instability related to more energetic shoreline conditions has been identified and this is very likely a regional phenomenon. The period of instability is accompanied by changes in hunter-gatherer behaviour, and this includes changes in the spatial organisation of settlement, and adjustments to procurement strategies. The overall situation is that environmental change is the norm during the Mesolithic of the Atlantic façade, almost certainly due to its highly moderated climate. The adaptability of hunter-gatherer societies in response to the changes brought about by fluctuations in the moderating mechanisms is strongly attested. In many ways not much has changed, as flooded homes, reductions in biodiversity and changes in the resources available for exploitation are all observed

Hydrodynamic stability of swimming in ostraciid fishes: role of the carapace in the smooth trunkfish Lactophrys triqueter (Teleostei: Ostraciidae)

The hydrodynamic bases for the stability of locomotory motions in fishes are poorly understood, even for those fishes, such as the rigid-bodied smooth trunkfish Lactophrys triqueter, that exhibit unusually small amplitude recoil movements during rectilinear swimming. We have studied the role played by the bony carapace of the smooth trunkfish in generating trimming forces that self-correct for instabilities. The flow patterns, forces and moments on and around anatomically exact, smooth trunkfish models positioned at both pitching and yawing angles of attack were investigated using three methods: digital particle image velocimetry (DPIV), pressure distribution measurements, and force balance measurements. Models positioned at various pitching angles of attack within a flow tunnel produced well-developed counter-rotating vortices along the ventro-lateral keels. The vortices developed first at the anterior edges of the ventro-lateral keels, grew posteriorly along the carapace, and reached maximum circulation at the posterior edge of the carapace. The vortical flow increased in strength as pitching angles of attack deviated from 0°, and was located above the keels at positive angles of attack and below them at negative angles of attack. Variation of yawing angles of attack resulted in prominent dorsal and ventral vortices developing at far-field locations of the carapace; far-field vortices intensified posteriorly and as angles of attack deviated from 0°. Pressure distribution results were consistent with the DPIV findings, with areas of low pressure correlating well with regions of attached, concentrated vorticity. Lift coefficients of boxfish models were similar to lift coefficients of delta wings, devices that also generate lift through vortex generation. Furthermore, nose-down and nose-up pitching moments about the center of mass were detected at positive and negative pitching angles of attack, respectively. The three complementary experimental approaches all indicate that the carapace of the smooth trunkfish effectively generates self-correcting forces for pitching and yawing motions — a characteristic that is advantageous for the highly variable velocity fields experienced by trunkfish in their complex aquatic environment. All important morphological features of the carapace contribute to producing the hydrodynamic stability of swimming trajectories in this species

Long-distance dispersal helps germinating mahogany seedlings escape defoliation by a specialist caterpillar

Herbivores and pathogens with acute host specificity may promote high tree diversity in tropical forests by causing distance- and density-dependent mortality of seedlings, but evidence is scarce. Although Lepidoptera larvae are the most abundant and host-specific guild of herbivores in these forests, their impact upon seedling distributions remains largely unknown. A firm test of the mechanism underpinning the Janzen-Connell hypothesis is difficult, even for a single tree species, because it requires more than just manipulating seeds and seedlings and recording their fates. Experimental tests require: (1) an insect herbivore that is identified and highly specialised, (2) linkage to an in situ measure (or prevention) of herbivory, and (3) evaluation and confirmation among many conspecific adult trees across years. Here we present experimental evidence for a spatially explicit interaction between newly germinating seedlings of a Neotropical emergent tree, big-leaf mahogany (Swietenia macrophylla, Meliaceae), and caterpillars of a noctuid moth (Steniscadia poliophaea). In the understory of a southeastern Amazon forest, the proportion of attacks, leaf area lost, and seedling mortality due to this specialised herbivore peaked near Swietenia trees, but declined significantly with increasing distance from mature fruiting trees, as predicted by the Janzen-Connell hypothesis. We conclude that long-distance dispersal events (>50m) provided an early survival advantage for Swietenia seedlings, and propose that the role of larval Lepidoptera as Janzen-Connell vectors may be underappreciated in tropical forest

Flow Patterns Around the Carapaces of Rigid-bodied, Multi-propulsor Boxfishes (Teleostei: Ostraciidae)

Boxfishes (Teleostei: Ostraciidae) are rigid-body, multi-propulsor swimmers that exhibit unusually small amplitude recoil movements during rectilinear locomotion. Mechanisms producing the smooth swimming trajectories of these fishes are unknown, however. Therefore, we have studied the roles the bony carapaces of these fishes play in generating this dynamic stability. Features of the carapaces of four morphologically distinct species of boxfishes were measured, and anatomically-exact stereolithographic models of the boxfishes were constructed. Flow patterns around each model were investigated using three methods: 1) digital particle image velocimetry (DPIV), 2) pressure distribution measurements, and 3) force balance measurements. Significant differences in both cross-sectional and longitudinal carapace morphology were detected among the four species. However, results from the three interrelated approaches indicate that flow patterns around the various carapaces are remarkably similar. DPIV results revealed that the keels of all boxfishes generate strong longitudinal vortices that vary in strength and position with angle of attack. In areas where attached, concentrated vorticity was detected using DPIV, low pressure also was detected at the carapace surface using pressure sensors. Predictions of the effects of both observed vortical flow patterns and pressure distributions on the carapace were consistent with actual forces and moments measured using the force balance. Most notably, the three complementary experimental approaches consistently indicate that the ventral keels of all boxfishes, and in some species the dorsal keels as well, effectively generate self-correcting forces for pitching motions—a characteristic that is advantageous for the highly variable velocity fields in which these fishes reside

Patterns of Structural Response to Simulated Partial Harvesting of Boreal Mixedwood Stands

Partial harvesting has been proposed as an approach for maintaining late-successional structure within managed boreal mixedwood stands. Although little long-term data is available to evaluate its effects in this stand type, recent advances in individual tree-based stand modeling provide an opportunity to simulate post-harvest stand development following different retention harvests. Using the stand dynamics model SORTIE-ND, we examined 40-year patterns of structural change in response to different intensities (30%, 50%, and 70% removal) and spatial patterns (uniform, small patch, large patch) of harvesting in aspen-dominated mixedwood stands. We assessed structural dynamics through a suite of variables representing the distribution of tree sizes, understory development, regeneration, standing and fallen dead wood characteristics, and within-stand heterogeneity. Partial harvesting induced a reciprocal increase in understory and downed woody debris development and decrease in overstory structure over the first 20 years after harvest, with this effect reversing after 25 years as harvest-induced regeneration reached the canopy. Densities of large trees and snags were reduced by harvesting, and did not recover to pre-harvest levels within 40 years. Harvesting promoted within-stand heterogeneity in the short and long term, and also produced transient increases in early-decay downed woody debris and ground exposure. These effects largely increased in proportion to harvest intensity. Although spatial pattern was of lesser importance than intensity, aggregated harvests induced somewhat less pronounced impacts on structure (with the exception of heterogeneity) than dispersed harvesting. These simulation results can form a basis for more detailed hypotheses regarding maintenance of late-successional stand structure and function through partial harvesting. Such hypotheses may in turn be translated into real-world silvicultural experiments to be evaluated, refined, and either accepted or rejected within an adaptive management framework

Dynamics and Energetics of Animal Swimming and Flying: Introduction

A few broad general questions have been central to the study of the dynamics and energetics of animal swimming and flying since the field began. A partial list includes: 1. What are the biomechanical bases for swimming and flying in the various groups of animals? 2. What are the kinematic and kinetic bases for swimming and flying? How do the shapes and movements of involved body parts generate thrust, drag, lift, dynamic stability, and maneuverability? 3. What are the energy costs of swimming and flying

A Syndrome of Neuromotor Speech Deficit and Dysgraphia?

TB

Combination of Isosorbide Dinitrate and Hydralazine in Blacks with Heart Failure

BACKGROUND We examined whether a fixed dose of both isosorbide dinitrate and hydralazine provides additional benefit in blacks with advanced heart failure, a subgroup previously noted to have a favorable response to this therapy. METHODS A total of 1050 black patients who had New York Heart Association class III or IV heart failure with dilated ventricles were randomly assigned to receive a fixed dose ofisosorbide dinitrate plus hydralazine or placebo in addition to standard therapy for heart failure. The primary end point was a composite score made up of weighted values for death from any cause, a first hospitalization for heart failure, and change in the quality of life. RESULTS The study was terminated early owing to a significantly higher mortality rate in the placebo group than in the group given isosorbide dinitrate plus hydralazine (10.2 percent vs. 6.2 percent, P=0.02). The mean primary composite score was significantly better in the group given isosorbide dinitrate plus hydralazine than in the placebo group (-0.1±1.9 vs. -0.5±2.0, P=0.01; range of possible values, -6 to + 2), as were its individual components (43 percent reduction in the rate of death from any cause [hazard ratio, 0.57; P=0.01] 33 percent relative reduction in the rate of first hospitalization for heart failure [16.4 percent vs. 22.4 percent, P=0.001], and an improvement in the quality of life [change in score, -5.6±20.6 vs. -2.7±21.2, with lower scores indicating better quality of life; P=0.02; range of possible values, 0 to 105]). CONCLUSIONS The addition ofa fixed dose of isosorbide dinitrate plus hydralazine to standard therapy for heart failure including neurohormonal blockers is efficacious and increases survival among black patients with advanced heart failure