941 research outputs found

    Plant food economy and environment during the epipalaeolithic in southwest Anatolia : an investigation of the botanical macroremains from Öküzini and Karain B

    Get PDF
    Located in southwest Turkey, not far from the seacoast, the natural caves of Öküzini and Karain B were inhabited by prehistoric populations during the Late Glacial and beyond. The Epipalaeolithic populations left traces of different occupation phases dated between 16.560 ±180 uncal BP (18.200-17.400 cal BC) to 12.130 ±100 uncal BP (14.400-11.800 cal BC) in Öküzini, around 15.000 uncal BP in Karain B. The topic of this research was to examine the macrobotanical remains associated with the Epipalaeolithic occupations, with the underlying aims to acquire insights about the economy of these communities and their use of the environmental resources. A first research paper addresses the issue of plant macroremain identification, in particular the identification of „thick shelled“ plant remains. Morphological comparison with the range of potential species and present geographical distribution made it possible to refine the determination to a double species: Amygdalus orientalis or A. graeca. These plants could grow in the surroundings of the sites on rocky slopes or sandy hills and had to be collected during late summer. All wild Amygdalus seeds are toxic, so that their use as food can be disputed. However, through examination of the detoxification possibilities, nutritional properties and ethnographic analogies for the use of wild almonds, we came to the conclusion that the seeds probably played a notable role in the diet of the Epipalaeolithic population of southwest Anatolia. A comparison with further published prehistoric “nutshell” finds from the Near East supports a long and widely distributed tradition of wild almond use. The analyses of the whole plant macroremain assemblages (excluding wood charcoals) identified at least 18 taxa and “categories” of remains, mainly carbonised. The importance and the role of the plants – particularly in the diet and their bearing on the seasonality of occupation of the sites – have been evaluated with quantitative and qualitative data. Nuts (principally Amygdalus, wild almond), fruits (principally Pyrus, wild pear), bulbs, roots or tubers (underground storage organs) seem to have occupied a particularly important place in these communities during all Epipalaeolithic phases, at the expense of small-seeded plants. The attested plants would have provided carbohydrates, lipids and micronutrients complementing well the meat diet. The cost of acquisition of the major plant resources was estimated: nuts and underground storage organs were generally considered as high ranked resources, providing a resource easy to gather and to process for a high calorific return. The almonds had a higher cost of acquisition. Their richness in fats and their availability at the onset of the winter season however could justify the additional work required for their detoxification. Judging from the seasonality indices of the plants and ungulate fauna at Öküzini, the cave could have been inhabited periodically in all seasons, but particularly in spring and autumn. A third paper presented the use of firewood and palaeoenvironmental reconstruction using anthracological and other environmental data. The diversity of fuel wood used was moderate and at both sites Acer (maple), Amygdalus (wild almond) and Fraxinus (ash) were the most common and important taxa. Secondary taxa were composed of Maloideae, Pyrus (wild pear), Prunus (wild plum), Quercus (cadufoliate oak), and Rhamnus/Phillyrea (buckthorn/mock privet). No chronological changes were observed. The major difference between both caves was the presence of hygrophilous and mesophillous taxa in Öküzini, whereas Coniferous wood was more common in Karain B, leading to the interpretation of an opportunistic exploitation of the surroundings of each site. Despite the poverty of the Late Glacial vegetation, there was no indication of use of alternative fuel material. These Epipalaeolithic populations seem to have responded to shortages rather through mobility than intensification. The anthracological results have been integrated to present-day knowledge of the environment of southwest Anatolia in an attempt to reconstruct the local vegetation. Among the different models of optimal foraging, the diet breadth model predicts that the resource a forager chooses from an available set of resources depends on their efficiency rank and abundance in the environment. Knowing from former investigations what plant resources were collected by the Epipalaeolithic populations from Öküzini and Karain B, we used this model to estimate the richness of the various classes of plant resources in the environment of the sites. An exploitation of high ranked plant resources, the nuts and the roots, bulbs or tubers, instead of small seeds, probably reflected their good availability in the environment. On the other hand, although the pattern of fuel use did not show any indices of wood scarcity, the reconstruction of the vegetation resulted in an environment not particularly rich in plant resources. The density of population being low, we suppose that the Epipalaeolithic populations living in this region adapted to their natural conditions in moving regularly their camps

    Effect of water level on migratory birds habitat at lake maggiore

    Get PDF
    Migratory birds need to stop along their route to rest and feed at so called stopover sites. "Bolle di Magadino"is a protected wetland located near lake Maggiore (CH), an internationally recognized nesting and stop-over site for birds. The waters of Lake Maggiore are important resources for multiple usages, and are artificially regulated through a dam. Even slight variations in the water level are sufficient to cause flooding and draining of large portions of the wetlands, affecting foraging and resting opportunities for birds. We use open data and FOSS4G to study the effect of water level on bird migration. We compared the extent and type of flooded habitat using two approaches: Sentinel-1 remote sensing imagery and simulations based on the measured water level. The effect of type and extent of submerged vegetation obtained with both methods was tested against a time series of bird captures. Both methods had a similar temporal pattern of flooding in autumn, but nearly opposite in spring. The total extent and the type of submerged habitats showed significant differences. The results obtained by simulations based on water level were more correlated to birds captures and species richness than the estimations of flooded habitat derived by with Sentinel-1. The results presented here will contribute to the definition sustainable management tools of water management of lake Maggiore taking into account the effect of lake level on biodiversity

    Local Communication Protocols for Learning Complex Swarm Behaviors with Deep Reinforcement Learning

    Full text link
    Swarm systems constitute a challenging problem for reinforcement learning (RL) as the algorithm needs to learn decentralized control policies that can cope with limited local sensing and communication abilities of the agents. While it is often difficult to directly define the behavior of the agents, simple communication protocols can be defined more easily using prior knowledge about the given task. In this paper, we propose a number of simple communication protocols that can be exploited by deep reinforcement learning to find decentralized control policies in a multi-robot swarm environment. The protocols are based on histograms that encode the local neighborhood relations of the agents and can also transmit task-specific information, such as the shortest distance and direction to a desired target. In our framework, we use an adaptation of Trust Region Policy Optimization to learn complex collaborative tasks, such as formation building and building a communication link. We evaluate our findings in a simulated 2D-physics environment, and compare the implications of different communication protocols.Comment: 13 pages, 4 figures, version 2, accepted at ANTS 201

    Living on the edge: Space use of Eurasian red squirrels in marginal high-elevation habitat.

    Get PDF
    In marginal habitats located at the edge of a species\u2019 range, environmental conditions are frequently extreme and individuals may be subject to different selective pressures compared to central populations. These so-called edge or marginal populations tend to have lower densities and reproductive rates than populations located in more suitable habitats, but little is known about local adaptations in spacing behavior. We studied space use and social organization in a population of Eurasian red squirrels (Sciurus vulgaris) in a high-elevation marginal habitat of dwarf mountain pine (Pinus mugo) and compared it with spacing patterns in high-quality Scots pine (Pinus sylvestris) forest at lower-elevation. Home ranges and core areas were larger in the marginal habitat. In both habitats, males used larger home ranges than females, but sex differences in core area size were significant only in the edge population. Patterns of core area overlap were similar in both habitats with intra-sexual territoriality among adult females and higher degrees of inter-sexual overlap, typical for the species throughout its range. However, low densities in the edge population resulted in higher female by males overlap in spring-summer, suggesting males increased home ranges and core areas during mating season to augment access to estrus females. Thus, in the marginal habitat, with low food abundance and low population densities, linked with extreme winter conditions, squirrels, especially males, used large home ranges. Finally, squirrels responded more strongly to variation in food availability (inverse relation between home range size and seed abundance), and even to fluctuations in density (inverse relation between core area size and density of animals of the same sex), in the marginal than in the high-quality habitat, suggesting high behavioral plasticity to respond to the ecological constraints in marginal habitats

    Pokrovsky-Talapov Model at finite temperature: a renormalization-group analysis

    Full text link
    We calculate the finite-temperature shift of the critical wavevector QcQ_{c} of the Pokrovsky-Talapov model using a renormalization-group analysis. Separating the Hamiltonian into a part that is renormalized and one that is not, we obtain the flow equations for the stiffness and an arbitrary potential. We then specialize to the case of a cosine potential, and compare our results to well-known results for the sine-Gordon model, to which our model reduces in the limit of vanishing driving wavevector Q=0. Our results may be applied to describe the commensurate-incommensurate phase transition in several physical systems and allow for a more realistic comparison with experiments, which are always carried out at a finite temperature

    A novel uncoupled quasi-3D Euler-Euler model to study the spiral jet mill micronization of pharmaceutical substances at process scale: model development and validation

    Get PDF
    In this work we present a novel approach to model the micronization of pharmaceutical ingredients at process scales and times. 3D single-phase fluid-dynamics simulations are used to compute the gas velocity field within a spiral jet mill which are provided as input in a 1D compartmentalized model to calculate solid velocities along the radial direction. The particles size reduction is taken into account through a breakage kernel that is function of gas energy and local solid holdup. Simulation results are validated against micronization experiments for lactose and paracetamol, comparing the model predictions with D10, D50 and D90 diameters values coming from Design of Experiments isosurfaces. The developed model allows for a fair estimation of the outlet particle size distribution in a short computational time, with very good predictions especially for D90 values

    Orientational pinning and transverse voltage: Simulations and experiments in square Josephson junction arrays

    Full text link
    We study the dependence of the transport properties of square Josephson Junctions arrays with the direction of the applied dc current, both experimentally and numerically. We present computational simulations of current-voltage curves at finite temperatures for a single vortex in the array (Ha2/Φ0=f=1/L2Ha^2/\Phi_0=f=1/L^2), and experimental measurements in 100×1000100\times1000 arrays under a low magnetic field corresponding to f0.02f\approx0.02. We find that the transverse voltage vanishes only in the directions of maximum symmetry of the square lattice: the [10] and [01] direction (parallel bias) and the [11] direction (diagonal bias). For orientations different than the symmetry directions, we find a finite transverse voltage which depends strongly on the angle ϕ\phi of the current. We find that vortex motion is pinned in the [10] direction (ϕ=0\phi=0), meaning that the voltage response is insensitive to small changes in the orientation of the current near ϕ=0\phi=0. We call this phenomenon orientational pinning. This leads to a finite transverse critical current for a bias at ϕ=0\phi=0 and to a transverse voltage for a bias at ϕ0\phi\not=0. On the other hand, for diagonal bias in the [11] direction the behavior is highly unstable against small variations of ϕ\phi, leading to a rapid change from zero transverse voltage to a large transverse voltage within a few degrees. This last behavior is in good agreement with our measurements in arrays with a quasi-diagonal current drive.Comment: 9 pages, 9 figure

    Local recurrence of soft tissue sarcoma: A radiomic analysis

    Get PDF
    Background To perform a radiomics analysis in local recurrence (LR) surveillance of limb soft tissue sarcoma (STS) Patients and methods This is a sub-study of a prospective multicenter study with Institutional Review Board approval supported by ESSR (European Society of Musculoskeletal Radiology). radiomics analysis was done on fast spin echo axial T1w, T2w fat saturated and post-contrast T1w (T1wGd) 1.5T MRI images of consecutively recruited patients between March 2016 and September 2018. Results N = 11 adult patients (6 men and 5 women; mean age 57.8 \ub1 17.8) underwent MRI to exclude STS LR: a total of 33 follow-up events were evaluated. A total of 198 data-sets per patients of both pathological and normal tissue were analyzed. Four radiomics features were significantly correlated to tumor size (p < 0.02) and four radiomics features were correlated with grading (p < 0.05). ROC analysis showed an AUC between 0.71 (95%CI: 0.55-0.87) for T1w and 0.96 (95%CI: 0.87-1.00) for post-contrast T1w. Conclusions radiomics features allow to differentiate normal tissue from pathological tissue in MRI surveillance of local recurrence of STS. radiomics in STS evaluation is useful not only for detection purposes but also for lesion characterization

    Nutcrackers become choosy seed harvesters in a mast-crop year.

    Get PDF
    As an efficient seed-disperser, Eurasian nutcrackers (Nucifraga caryocatactes) generally consume and hoard mature, edible pine seeds for future use. In 2009, when the Arolla pine, Pinus. cembra, produced a mast-crop, we investigated cones discarded by nutcrackers. Most cones were only partly eaten and some mature seeds remained in the distal part. This was in contrast to years of lower seed production when nearly all seeds were harvested from the majority of cones. To determine whether nutcracker cone-discarding behaviour maximised intake rate, seed kernels and the aborted seeds rate were measured from the different cone parts. In 2009, seeds from cone-tops were on average 17% lighter than in the base and middle sections, and the proportion of aborted seeds in the top part was 81% higher than in the other sections. There was no difference in seed mass and proportion of aborted seeds in cone-tops of intact cones and cones handled by nutcrackers. Regarding each cone as a patch, cone discarding behaviour can be considered as an optimal cone-leaving rule, maximising rate of energy-intake, supporting the Marginal Value Theorem. Hence, we suggest that increased food abundance leads to more selective seed harvesting in nutcrackers
    corecore