1,105 research outputs found

    Spatial bias correction for sporadic meteors photographed in New Mexico

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    Spatial bias correction for sporadic meteors photographed in New Mexic

    Effect of on- and off-ramps in cellular automata models for traffic flow

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    We present results on the modeling of on- and off-ramps in cellular automata for traffic flow, especially the Nagel-Schreckenberg model. We study two different types of on-ramps that cause qualitatively the same effects. In a certain density regime one observes plateau formation in the fundamental diagram. The plateau value depends on the input-rate of cars at the on-ramp. The on-ramp acts as a local perturbation that separates the system into two regimes: A regime of free flow and another one where only jammed states exist. This phase separation is the reason for the plateau formation and implies a behaviour analogous to that of stationary defects. This analogy allows to perform very fast simulations of complex traffic networks with a large number of on- and off-ramps because one can parametrise on-ramps in an exceedingly easy way.Comment: 11 pages, 9 figures, accepted for publication in Int. J. Mod. Phys.

    50 Jahre Deutsche Gesellschaft für Polarforschung e.V. Jubiläumsveranstaltung in Potsdam am 20. November 2009

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    The study of luminophores base influence activated by europium on their acid-base and luminescent properties

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    Five samples of luminophores, activated by europium and synthesized by sol-gel and СВС methods were investigated. The researched samples have basic surface character, differing depending on the base of luminophor and percentage of europium. Excitation and photoluminescent spectra were obtained. Photoluminescent spectrum of the samples, containing Eu(III) ions have the similar character. They have 5 stripes with maximum at 580, 598, 622, 658 nm and the doublet with stripes at 702 and 706 nm which are referred to innerconfigurational 4f-4f transits if europium ion 7F0-5D4. The samples YVPO4(P10):Eu8% and YVO4:Eu10% have the most intense luminescence. Their intensity is about 60 times higher than the YPO4:Eu10% sample has

    Afferent Convergence from Divergent Sources Appears to Enhance the Spastic Patient\u27s Ability to Inhibit Antagonist Motoneurons During an Agonist Contraction

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    Spasticity and excessive muscular cocontraction during movement are common impairments following upper motor neuron (UMN) lesions. For example, during voluntary ankle dorsiflexion, individuals with spastic type cerebral palsy (CP) do not inhibit the antagonist triceps surae motoneuron pool

    Perceptions of cyclone preparedness: assessing the role of individual adaptive capacity and social capital in the Wet Tropics, Australia

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    Given projections of future climate-related disasters, understanding the conditions that facilitate disaster preparedness is critical to achieving sustainable development. Here, we studied communities within the Wet Tropics bioregion, Australia to explore whether people’s perceived preparedness for a future cyclone relates to their: (1) perceived individual adaptive capacity (in terms of flexibility and capacity to plan and learn); and (2) structural and cognitive social capital. We found that people's perceived cyclone preparedness was only related to their perceived individual flexibility in the face of change. Given that people's perceived cyclone preparedness was related to individualistic factors, it is plausible that individualism-collectivism orientations influence people's perceptions at an individual level. These results suggest that in the Wet Tropics region, enhancing people’s psychological flexibility may be an important step when preparing for future cyclones. Our study highlights the need to tailor disaster preparedness initiatives to the region in question, and thus our results may inform disaster risk management and sustainable development policies

    Two types of bone necrosis in the middle triassic pistosaurus longaevus bones: The results of integrated studies

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    Avascular necrosis, diagnosed on the basis of either a specific pathological modification of the articular surfaces of bone or its radiologic appearance in vertebral centra, has been recognized in many Mesozoic marine reptiles as well as in present-day marine mammals. Its presence in the zoological and paleontologic record is usually associated with decompression syndrome, a disease that affects secondarily aquatic vertebrates that could dive. Bone necrosis can also be caused by infectious processes, but it differs in appearance from decompression syndrome-associated aseptic necrosis. Herein, we report evidence of septic necrosis in the proximal articular surface of the femur of a marine reptile, Pistosaurus longaevus, from the Middle Triassic of Poland and Germany. This is the oldest recognition of septic necrosis associated with septic arthritis in the fossil record so far, and the mineralogical composition of pathologically altered bone is described herein in detail. The occurrence of septic necrosis is contrasted with decompression syndrome-associated avascular necrosis, also described in Pistosaurus longaevus bone from Middle Triassic of Germany

    The Effect of absorbing sites on the one-dimensional cellular automaton traffic flow with open boundaries

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    The effect of the absorbing sites with an absorbing rate β0\beta_{0}, in both one absorbing site (one way out) and two absorbing sites (two ways out) in a road, on the traffic flow phase transition is investigated using numerical simulations in the one-dimensional cellular automaton traffic flow model with open boundaries using parallel dynamics.In the case of one way out, there exist a critical position of the way out ic1 i_{c1} below which the current is constant for β0\beta_{0}<<β0c2\beta_{0c2} and decreases when increasing β0\beta_{0} for β0\beta_{0}>>β0c2\beta_{0c2}. When the way out is located at a position greater than ic2 i_{c2}, the current increases with β0\beta_{0} for β0\beta_{0}<<β0c1\beta_{0c1} and becomes constant for any value of β0\beta_{0} greater than β0c1\beta_{0c1}. While, when the way out is located at any position between ic1 i_{c1} and ic2 i_{c2} (ic1 i_{c1}<<ic2 i_{c2}), the current increases, for β0\beta_{0}<<β0c1\beta_{0c1}, with β0\beta_{0} and becomes constant for β0c1\beta_{0c1}<<β0\beta_{0}<<β0c2\beta_{0c2} and decreases with β0\beta_{0} for β0\beta_{0}>>β0c2\beta_{0c2}. In the later case the density undergoes two successive first order transitions; from high density to maximal current phase at β0\beta_{0}==β0c1\beta_{0c1} and from intermediate density to the low one at β0\beta_{0}==β0c2\beta_{0c2}. In the case of two ways out located respectively at the positions i1 i_{1} and i2 i_{2}, the two successive transitions occur only when the distance i2i_{2}-i1i_{1} separating the two ways is smaller than a critical distance dcd_{c}. Phase diagrams in the (α,β0\alpha,\beta_{0}), (β,β0\beta,\beta_{0}) and (i1,β0i_{1},\beta_{0}) planes are established. It is found that the transitions between Free traffic, Congested traffic and maximal current phase are first order

    Readiness of Quantum Optimization Machines for Industrial Applications

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    There have been multiple attempts to demonstrate that quantum annealing and, in particular, quantum annealing on quantum annealing machines, has the potential to outperform current classical optimization algorithms implemented on CMOS technologies. The benchmarking of these devices has been controversial. Initially, random spin-glass problems were used, however, these were quickly shown to be not well suited to detect any quantum speedup. Subsequently, benchmarking shifted to carefully crafted synthetic problems designed to highlight the quantum nature of the hardware while (often) ensuring that classical optimization techniques do not perform well on them. Even worse, to date a true sign of improved scaling with the number of problem variables remains elusive when compared to classical optimization techniques. Here, we analyze the readiness of quantum annealing machines for real-world application problems. These are typically not random and have an underlying structure that is hard to capture in synthetic benchmarks, thus posing unexpected challenges for optimization techniques, both classical and quantum alike. We present a comprehensive computational scaling analysis of fault diagnosis in digital circuits, considering architectures beyond D-wave quantum annealers. We find that the instances generated from real data in multiplier circuits are harder than other representative random spin-glass benchmarks with a comparable number of variables. Although our results show that transverse-field quantum annealing is outperformed by state-of-the-art classical optimization algorithms, these benchmark instances are hard and small in the size of the input, therefore representing the first industrial application ideally suited for testing near-term quantum annealers and other quantum algorithmic strategies for optimization problems.Comment: 22 pages, 12 figures. Content updated according to Phys. Rev. Applied versio

    Toward a High-Frequency Pulsed-Detonation Actuator

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    This paper describes the continued development of an actuator, energized by pulsed detonations, that provides a pulsed jet suitable for flow control in high-speed applications. A high-speed valve, capable of delivering a pulsed stream of reactants a mixture of H2 and air at rates of up to 1500 pulses per second, has been constructed. The reactants burn in a resonant tube and the products exit the tube as a pulsed jet. High frequency pressure transducers have been used to monitor the pressure fluctuations in the device at various reactant injection frequencies, including both resonant and off-resonant conditions. Pulsed detonations have been demonstrated in the lambda/4 mode of an 8 inch long tube at approx. 600 Hz. The pulsed jet at the exit of the device has been observed using shadowgraph and an infrared camera
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