Development and Application of a Climate-driven Human Dispersal Model

The origin and spread of the Anatomically Modern Human (AMH) is still debated and regu-larly renewed as new findings challenge the current consensus. While the fossil remains suggest a gradual evolution and spread, molecular genetic studies propose an outburst of AMH that spread out and became dominant. Human population and migration models are used to bridge over ranges of time and space that lack sufficient data, utilizing diffusion-reaction models to simulate the spread and population dynamics. The aim of this study is to expand these migration models with a directed dispersal rather than the isotropic spread through diffusion. To achieve this, spatial and temporal climate simulation data is used in conjunction with archaeological data to estimate the Human Existence Potential (HEP), a measure for the survivability for a specific culture of AMH. The directed dispersal is proportional to the gradient of this potential field and the population distribution, combining different factors that can trigger migration. The dispersal model is presented in detail as part of the Human Modeling Framework, which combines several models and applications that build upon the HEP. Idealized and realistic test scenarios are broad out to evaluate the performance of the dispersal model, which show reasonable results in regards to numeric stability and consistency. The realistic simulations include a representative Dansgaard-Oeschger event for the Aurignacian technocomplex and a simulation of monthly changing HEP for the Last Glacial Maximum. The former produces a reasonable response, while the latter illustrates the limitations of the dispersal model. As the final application, a complete simulation of AMH dispersal from the Levant to Europe from 45-25 kyr BP shows promising results regarding possible dispersal routes and the timing of first arrivals. The uncertainties in radiocarbon dating make it difficult, however, to evaluate the estimation of the timings. The presented model is a feasible foundation that can be further expanded, for example, by using more than one population and include social interactions in a simplified formulation

A note on the transitive Hurwitz action on decompositions of parabolic Coxeter elements

In this note, we provide a short and self-contained proof that the braid group on n strands acts transitively on the set of reduced factorizations of a Coxeter element in a Coxeter group of finite rank n into products of reflections. We moreover use the same argument to also show that all factorizations of an element in a parabolic subgroup of W lie as well in this parabolic subgroup.Comment: 5 page

Hall-effect sign-inversion in a realizable 3D metamaterial

In 2009, Briane and Milton proved mathematically the existence of three-dimensional isotropic metamaterials with a classical Hall coefficient which is negative with respect to that of all of the metamaterial constituents. Here, we significantly simplify their blueprint towards an architecture composed of only a single constituent material in vacuum/air, which can be seen as a special type of porosity. We show that the sign of the Hall voltage is determined by a separation parameter between adjacent tori. This qualitative behavior is robust even for only a small number of metamaterial unit cells. The combination of simplification and robustness brings experimental verifications of this striking sign-inversion into reach.Comment: 9 figures, 7 page

TimeWeaver: A Tool for Hybrid Worst-Case Execution Time Analysis

Many embedded control applications have real-time requirements. If the application is safety-relevant, worst-case execution time bounds have to be determined in order to demonstrate deadline adherence. For high-performance multi-core architectures with degraded timing predictability, WCET bounds can be computed by hybrid WCET analysis which combines static analysis with timing measurements. This article focuses on a novel tool for hybrid WCET analysis based on non-intrusive instruction-level real-time tracing

Experimental Evidence for Sign Reversal of the Hall Coefficient in Three-Dimensional Metamaterials

International audienceIn the precedingComment [1] on our Letter [2], Oswald points out “thatin Kern’s structure the sign reversal happens already in theindividual building blocks of their crystal, which makes itsidentification as a metamaterial effect questionable.” Hefurther argues that in photonic crystals “the interactionbetween the elementary building blocks is decisive, whilethis is not the case in Kern’s structure.” This appears to be amisunderstanding. Photonic crystals are distinct frommetamaterials [3,4].We will provide a clarifying discussionto the definition of a metamaterial below

Ocurrencia de individuos bisexuados y con anomalías en flores y frutos en dos clones de Populus deltoides Marsh. cultivados en la Argentina

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The Proprotein Convertase Encoded by amontillado (amon) Is Required in Drosophila Corpora Cardiaca Endocrine Cells Producing the Glucose Regulatory Hormone AKH

Peptide hormones are potent signaling molecules that coordinate animal physiology, behavior, and development. A key step in activation of these peptide signals is their proteolytic processing from propeptide precursors by a family of proteases, the subtilisin-like proprotein convertases (PCs). Here, we report the functional dissection of amontillado (amon), which encodes the Drosophila homolog of the mammalian PC2 protein, using cell-type specific inactivation and rescue experiments, and we show that amon is required in the islet-like adipokinetic hormone (AKH)–producing cells that regulate sugar homeostasis. In Drosophila, AKH acts analogously to vertebrate glucagon to increase circulating sugar levels from energy stores, while insulin-like peptides (DILPs) act to decrease sugar levels. amon mutant larvae have significantly reduced hemolymph sugar levels, and thus phenocopy larvae where the AKH–producing cells in the corpora cardiaca have been ablated. Reduction of amon expression in these cells via cell-specific RNA inactivation also results in larvae with reduced sugar levels while expression of amon in AKH cells in an amon mutant background rescues hypoglycemia. Hypoglycemia in larvae resulting from amon RNA inactivation in the AKH cells can be rescued by global expression of the akh gene. Finally, mass spectrometric profiling shows that the production of mature AKH is inhibited in amon mutants. Our data indicate that amon function in the AKH cells is necessary to maintain normal sugar homeostasis, that amon functions upstream of akh, and that loss of mature AKH is correlated with loss of amon activity. These observations indicate that the AKH propeptide is a proteolytic target of the amon proprotein convertase and provide evidence for a conserved role of PC2 in processing metabolic peptide hormones

Failure mechanisms and cutting characteristics of brazed single diamond grains

The knowledge about the cutting characteristics and the critical loading of brazed diamonds is essential for a safe and economic application of engineered grinding tools. Scratch tests were performed with single grains. The experiments were conducted with standard polyhedral diamond grains of different sizes, ranging from 300 to 850μm, brazed with an Ag-Cu-based and a Cu-Sn-based active filler alloy onto a steel pin. Two failure mechanisms were revealed, namely "grain pullout” and "grain fracture”. Large grits mainly fail by grain fracture, whereas the smaller ones were mostly pulled out. This trend is supported by a simple mechanical model. The critical values, i.e. cutting force/scratch area, for grain fracture and grain pullout show a decrease with bigger grit size. Scratches are also analysed in terms of cutting characteristics. The dependency of the cutting and the normal force on the scratch area can be described by a power law with powers ranging between about 0.2 and 0.7, respectively. The measured cutting forces strongly depend on the rake angle, which was tested for −19.5° and −35.3

Influence of the brazing parameters on microstructure, residual stresses and shear strength of diamond-metal joints

The reliability and integrity of diamond cutting tools depend on the properties of diamond-metal joints as created by a brazing process. Block-shaped monocrystalline diamonds were brazed onto a steel substrate (X2CrNiMo 18-14-3), using silver-copper based Cusil-ABA™ (Ag-35wt%Cu-1.75wt%Ti) filler alloy. The experimental procedure includes a thorough microstructural investigation of the filler alloy, the determination of the induced residual stresses by Raman spectroscopy as well as the joint's shear strength utilizing a special shear device. The brazing processes were carried out at 850, 880 and 910°C for dwell durations of 10 and 30min, respectively. At the steel interface two interlayers develop. The layers grow with extended dwell duration and higher brazing temperature. The residual stresses only slightly depend on the brazing parameters and exhibit a maximum value of −400MPa. Unlike the residual stresses, the shear strength strongly depends on the brazing parameters and thus on the microstructure. Three failure modes could be identified; a ductile fracture in the filler alloy, a brittle fracture in the interlayers and a partly shattering of the diamon