Vortex scattering by step topography

The scattering at a rectilinear step change in depth of a shallow-water vortex pair consisting of two patches of equal but opposite-signed vorticity is studied. Using the constants of motion, an explicit relationship is derived relating the angle of incidence to the refracted angle after crossing. A pair colliding with a step from deep water crosses the escarpment and subsequently propagates in shallow water refracted towards the normal to the escarpment. A pair colliding with a step from shallow water either crosses and propagates in deep water refracted away from the normal or, does not cross the step and is instead totally internally reflected by the escarpment. For large depth changes, numerical computations show that the coherence of the vortex pair is lost on encountering the escarpment

Beach vortices near circular topography

Finite-area monopolar vortices which propagate around topography without change in shape are computed for circular seamounts and wells including the limiting cases of each: islands and infinitely-deep wells. The time-dependent behaviour of vortex pairs propagating toward circular topography is also examined. Trajectories of pointvortex pairs exterior to the topography are found and compared to trajectories of vortex patches computed using contour dynamics

A new approach to profiling taphonomic history through bone fracture analysis, with an example application to the Linearbandkeramik site of Ludwinowo 7.

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This paper presents a new method of assessing and displaying taphonomic history through detailed bone fracture analysis. Bone is a particularly useful indicator of taphonomic processes as it is sensitive to when it is broken based on degradation over time. Our proposed ‘fracture history profiles’ show the sequences of fracture and fragmentation that have affected assemblages of bone specimens from the death of the animal to recovery by archaeologists. The method provides an assessment of the carcass processing traditions of past people, relating specifically to bone marrow and bone grease extraction. In addition, by analysing post-deposition fracture and bone modifications caused by burning, gnawing and other taphonomic agents, it is possible to reconstruct a comprehensive taphonomic history for each archaeological context. This has implications for understanding effects on other artefacts that have no equivalent diagnostic features for determining timing of breakage, and also for establishing the nature of events such as secondary disturbance of deposits. This method will be demonstrated using a case study from the Neolithic Linearbandkeramik culture.This work was supported by the European Research Council (ERC Advanced Grant ERC324202

La formation des granulats plats et leur influence sur la résistance mécanique des agrégats des granites et gneiss du Togo

Cet article est consacré, d’une part, à l’étude de l’influence des différentes textures et structures des gneiss et des granites sur la formation des granulats plats lors du concassage et, d’autre part, à l’étude de l’impact du contenu de ces granulats plats sur la résistance mécanique des granulats, en général. Les résultats obtenus montrent que les roches ayant une structure grenue, donnent une meilleure qualité de forme (granulats de forme cubique) par rapport aux roches à structure porphyroblastique et lépidoblastique qui donnent beaucoup plus de granulats plats. En outre, la diminution du contenu de granulats plats contribue à améliorer la qualité des agrégats et à augmenter leur résistance mécanique.Mots-clés : Coefficient Los Angles, structure, gneiss, granite, granulat plat

Deterring poaching in western Tanzania: The presence of wildlife researchers

Illegal poaching threatens wildlife across Africa. Historically and even today, conservationists have lobbied local and national governments to create and better manage protected lands to reduce this threat. In many cases, however, governments are either unable or unwilling to invest further resources in exclusive protected areas, such as national parks. In addition to traditional methods, or where such approaches are not feasible, a complimentary form of protection is researcher presence, which has been described recently to deter wildlife poaching. We present data over four years that assesses the impact of researcher presence on wildlife and snare encounter rate in an unprotected area in western Tanzania, where there is a mid-term chimpanzee study ongoing. We systematically collected spatiotemporal presence data on the nine, most common mammal species in the study area, as well as all snares. Snare encounter rates increased with distance from researcher base station, whilst overall mammal encounter rates decreased. Further, mammal encounter rates have increased each year since the arrival and permanence of researchers in this remote area. Our findings have implications for the benefits of researcher presence, namely in deterring poaching, especially in unprotected areas with minimal governmental surveillance

The ecological determinants of baboon troop movements at local and continental scales.

BACKGROUND: How an animal moves through its environment directly impacts its survival, reproduction, and thus biological fitness. A basic measure describing how an individual (or group) travels through its environment is Day Path Length (DPL), i.e., the distance travelled in a 24-hour period. Here, we investigate the ecological determinants of baboon (Papio spp.) troop DPL and movements at local and continental scales. RESULTS: At the continental scale we explore the ecological determinants of annual mean DPL for 47 baboon troops across 23 different populations, updating a classic study by Dunbar (Behav Ecol Sociobiol 31: 35-49, 1992). We find that variation in baboon DPLs is predicted by ecological dissimilarity across the genus range. Troops that experience higher average monthly rainfall and anthropogenic influences have significantly shorter DPL, whilst troops that live in areas with higher average annual temperatures have significantly longer DPL. We then explore DPLs and movement characteristics (the speed and distribution of turning angles) for yellow baboons (Papio cynocephalus) at a local scale, in the Issa Valley of western Tanzania. We show that our continental-scale model is a good predictor of DPL in Issa baboons, and that troops move significantly slower, and over shorter distances, on warmer days. We do not find any effect of season or the abundance of fruit resources on the movement characteristics or DPL of Issa baboons, but find that baboons moved less during periods of high fruit availability. CONCLUSION: Overall, this study emphasises the ability of baboons to adapt their ranging behaviour to a range of ecological conditions and highlights how investigations of movement patterns at different spatial scales can provide a more thorough understanding of the ecological determinants of movement

Behavioral implications of shortlisting procedures

We consider two-stage “shortlisting procedures” in which the menu of alternatives is first pruned by some process or criterion and then a binary relation is maximized. Given a particular first-stage process, our main result supplies a necessary and sufficient condition for choice data to be consistent with a procedure in the designated class. This result applies to any class of procedures with a certain lattice structure, including the cases of “consideration filters,” “satisficing with salience effects,” and “rational shortlist methods.” The theory avoids background assumptions made for mathematical convenience; in this and other respects following Richter’s classical analysis of preference-maximizing choice in the absence of shortlisting

Inspiratory muscle training reduces blood lactate concentration during volitional hyperpnoea

Although reduced blood lactate concentrations ([lac−]B) have been observed during whole-body exercise following inspiratory muscle training (IMT), it remains unknown whether the inspiratory muscles are the source of at least part of this reduction. To investigate this, we tested the hypothesis that IMT would attenuate the increase in [lac−]B caused by mimicking, at rest, the breathing pattern observed during high-intensity exercise. Twenty-two physically active males were matched for 85% maximal exercise minute ventilation (V˙Emax) and divided equally into an IMT or a control group. Prior to and following a 6 week intervention, participants performed 10 min of volitional hyperpnoea at the breathing pattern commensurate with 85% V˙Emax

Local stellar kinematics from RAVE data: III. Radial and Vertical Metallicity Gradients based on Red Clump Stars

We investigate radial and vertical metallicity gradients for a sample of red clump stars from the RAdial Velocity Experiment (RAVE) Data Release 3. We select a total of 6781 stars, using a selection of colour, surface gravity and uncertainty in the derived space motion, and calculate for each star a probabilistic (kinematic) population assignment to a thin or thick disc using space motion and additionally another (dynamical) assignment using stellar vertical orbital eccentricity. We derive almost equal metallicity gradients as a function of Galactocentric distance for the high probability thin disc stars and for stars with vertical orbital eccentricities consistent with being dynamically young, e_v<=0.07, i.e. d[M/H]/dR_m = -0.041(0.003) and d[M/H]/dR_m = -0.041(0.007) dex/kpc. Metallicity gradients as a function of distance from the Galactic plane for the same populations are steeper, i.e. d[M/H]/dz_{max} = -0.109(0.008) and d[M/H]/dz_{max} = -0.260(0.031) dex/kpc, respectively. R_m and z_{max} are the arithmetic mean of the perigalactic and apogalactic distances, and the maximum distance to the Galactic plane, respectively. Samples including more thick disc red clump giant stars show systematically shallower abundance gradients. These findings can be used to distinguish between different formation scenarios of the thick and thin discs.Comment: 27 pages, including 15 figures and 4 tables, accepted for publication in MNRA