1,221 research outputs found

    Vectors of subsurface stormflow in a layered hillslope during runoff initiation

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    The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m<sup>2</sup> trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil) to 40 cm (close to bedrock interface). The mean values resulted as follows <i><b>v</b><sub>x</sub></i>=16.1 mm min<sup>-1</sup>, <i><b>v</b><sub>y</sub></i>=-0.2 mm min<sup>-1</sup>, and <i><b>v</b><sub>z</sub></i>=11.9 mm min<sup>-1</sup>. The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis) dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis) varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The lateral velocities of the vector approach are compared with subsurface stromflow collected at the downhill end of the slope. Velocities were 25-140 times slower than lateral saturated tracer movements on top of the bedrock. Beside other points, we conclude that this method is restricted to non-complex substrate (skeleton or portion of big stones)

    Phylogeny of the Genus Dichotrachelus (Coleoptera: Curculionidae: Cyclominae)

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    A phylogenetic analysis of the genus Dichotrachelus (Curculionidae: Cyclominae) was carried out, based on a morphological matrix and, for some species, on mitochondrial cytochrome oxidase I sequences. Bayesian Inference, Maximum Likelihood and Maximum Parsimony were implemented and the results were compared. The genus is found to be isolated in the subfamily, not related to the only other Palaearctic tribe (Hipporhinini) and possibly nearer to the south-American genera of Cyclominae of the tribe Listroderini. Among these, Macrostyphlus is also equally associated to mosses as the host plant. In Dichotrachelus, two main clades were recognized, one distributed in the western part of the Mediterranean region (Iberian Peninsula, northern Africa and southern France) and the second distributed in the Alps and Apennines. Within each clade, some differentiated monophyletic subgroups could be identified. An evaluation of the most important characters that led to the phylogenetic reconstruction indicated the male genital sclerite as the most useful structure to characterize the different clades

    Control of fine-structure splitting and excitonic binding energies in selected individual InAs/GaAs quantum dots

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    A systematic study of the impact of annealing on the electronic properties of single InAs/GaAs quantum dots (QDs) is presented. Single QD cathodoluminescence spectra are recorded to trace the evolution of one and the same QD over several steps of annealing. A substantial reduction of the excitonic fine-structure splitting upon annealing is observed. In addition, the binding energies of different excitonic complexes change dramatically. The results are compared to model calculations within eight-band k.p theory and the configuration interaction method, suggesting a change of electron and hole wave function shape and relative position.Comment: 4 pages, 4 figure

    Bio-inspired Tensegrity Soft Modular Robots

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    In this paper, we introduce a design principle to develop novel soft modular robots based on tensegrity structures and inspired by the cytoskeleton of living cells. We describe a novel strategy to realize tensegrity structures using planar manufacturing techniques, such as 3D printing. We use this strategy to develop icosahedron tensegrity structures with programmable variable stiffness that can deform in a three-dimensional space. We also describe a tendon-driven contraction mechanism to actively control the deformation of the tensegrity mod-ules. Finally, we validate the approach in a modular locomotory worm as a proof of concept.Comment: 12 pages, 7 figures, submitted to Living Machine conference 201

    A reduced model for shock and detonation waves. II. The reactive case

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    We present a mesoscopic model for reactive shock waves, which extends a previous model proposed in [G. Stoltz, Europhys. Lett. 76 (2006), 849]. A complex molecule (or a group of molecules) is replaced by a single mesoparticle, evolving according to some Dissipative Particle Dynamics. Chemical reactions can be handled in a mean way by considering an additional variable per particle describing a rate of reaction. The evolution of this rate is governed by the kinetics of a reversible exothermic reaction. Numerical results give profiles in qualitative agreement with all-atom studies

    The Production of Hospitable Space: Commercial Propositions and Consumer Co-Creation in a Bar Operation

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    This paper examines the processes through which a commercial bar is transformed into a hospitable space. Drawing on a study of a venue patronized by lesbian, gay, bisexual and transsexual/transgender consumers, it considers how social and commercial forms of hospitality are mobilized. The paper argues that hospitable space has an ideological, normative and situational dimension. More specifically, it suggests the bar’s operation is tied to a set of ideological conceptions, which become the potential basis of association and disassociation among consumers. It examines the forces and processes that shape who participates in the production and consumption of hospitality and how. Finally, it considers the situational, emergent nature of hospitality and the discontinuous production of hospitable space. Rather than focusing exclusively on host-guest or provider-customer relations, which dominates existing work on hospitality, the paper examines how consumers’ perceptions, actions and interactions shape the production of hospitality. By doing so the paper offers an alternative approach to understanding queer spaces, bar operation as well as hospitality

    Fatigue analysis-based numerical design of stamping tools made of cast iron

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    This work concerns stress and fatigue analysis of stamping tools made of cast iron with an essentially pearlitic matrix and containing foundry defects. Our approach consists at first, in coupling the stamping numerical processing simulations and structure analysis in order to improve the tool stiffness geometry for minimizing the stress state and optimizing their fatigue lifetime. The method consists in simulating the stamping process by considering the tool as a perfect rigid body. The estimated contact pressure is then used as boundary condition for FEM structure loading analysis of the tool. The result of this analysis is compared with the critical stress limit depending on the automotive model. The acceptance of this test allows calculating the fatigue lifetime of the critical zone by using the S–N curve of corresponding load ratio. If the prescribed tool life requirements are not satisfied, then the critical region of the tool is redesigned and the whole simulation procedures are reactivated. This method is applied for a cast iron EN-GJS-600-3. The stress-failure (S–N) curves for this material is determined at room temperature under push pull loading with different load ratios R0σmin/σmax0−2, R0−1 and R00.1. The effects of the foundry defects are determined by SEM observations of crack initiation sites. Their presence in tested specimens is associated with a reduction of fatigue lifetime by a factor of 2. However, the effect of the load ratio is more important

    Drone-based photogrammetry combined with deep-learning to estimate hail size distributions and melting of hail on the ground

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    Hail is a major threat associated with severe thunderstorms and an estimation of the hail size is important for issuing warnings to the public. Operational radar products exist that estimate the size of the expected hail. For the verification of such products, ground based observations are necessary. Automatic hail sensors, as for example within the Swiss hail network, record the kinetic energy of hailstones and can estimate with this the hail diameters. However, due to the small size of the observational area of these sensors (0.2 m2) the estimation of the hail size distribution (HSD) can have large uncertainties. To overcome this issue, we combine drone-based aerial photogrammetry with a state-of-the-art custom trained deep-learning object detection model to identify hailstones in the images and estimate the HSD in a final step. This approach is applied to photogrammetric image data of hail on the ground from a supercell storm, that crossed central Switzerland from southwest to northeast in the afternoon of June 20, 2021. The hail swath of this intense right-moving supercell was intercepted a few minutes after the passage at a soccer field near Entlebuch (Canton Lucerne, Switzerland) and aerial images of the hail on the ground were taken by a commercial DJI drone, equipped with a 50 megapixels full frame camera system. The average ground sampling distance (GSD) that could be reached was 1.5 mm per pixel, which is set by the mounted camera objective with a focal length of 35 mm and a flight altitude of 12 m above ground. A 2D orthomosaic model of the survey area (750 m2) is created based on 116 captured images during the first drone mapping flight. Hail is then detected by using a region-based Convolutional Neural Network (Mask R-CNN). We first characterize the hail sizes based on the individual hail segmentation masks resulting from the model detections and investigate the performance by using manual hail annotations by experts to generate validation and test data sets. The final HSD, composed of 18209 hailstones, is compared with nearby automatic hail sensor observations, the operational weather radar based hail product MESHS (Maximum Expected Severe Hail Size) and some crowdsourced hail reports. Based on the retrieved drone hail data set, a statistical assessment of sampling errors of hail sensors is carried out. Furthermore, five repetitions of the drone-based photogrammetry mission within about 18 min give the unique opportunity to investigate the hail melting process on the ground for this specific supercell hailstorm and location

    Incidence trends of lung and gastroenteropancreatic neuroendocrine neoplasms in Switzerland.

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    The incidence of neuroendocrine neoplasms (NENs) seems to increase worldwide. Long-term, population-based series that consider tumor differentiation are, however, sparse. We assessed the incidence trend of lung and gastroenteropancreatic (GEP) NENs according to the latest International Agency for Research on Cancer/World Health Organization classification over a 41-year time period in two Swiss regions. All cases of lung and GEP NENs recorded in the Vaud and Neuchâtel Cancer Registries from 1976 to 2016 were included. NENs were stratified into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). Changes in annual age-standardized incidence rates were calculated for lung and GEP NETs and NECs by sex. Of 4,141 patients diagnosed with NENs, 65% were men. The incidence of lung NETs among men and women increased by 3.9%/year (95% CI: -5.3, 14.1%) and 4.9%/year (0.1, 9.9%), respectively, between 1976 and 2016. The incidence of lung NECs decreased by 2.6%/year (-3.1,-1.8%) in men from 1985 to 2016 whereas it increased in women between 1976 and 1998 by 6%/year (4.2, 7.9%). For GEP NETs, a steady annual increase in incidence occurred between 1976 and 2016 with a magnitude of 1.7% (0.7, 2.7%) in men and 1.3% (0.5, 2.1%) in women. No significant trend in incidence of GEP NECs was found for both sexes. The incidence trends of lung NECs in men and women parallel changes in smoking prevalence in the population. Causes of the increase in incidence of GEP NETs are likely multifactorial. Our study supports the importance of evaluating the epidemiology of NENs by tumor differentiation
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