2,916 research outputs found

    Preliminary Checklist of the Fishes of the Illinois River, Arkansas

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    A survey of the fishes of the mainstream of the Illinois River in northwestern Arkansas produced 51 species representing 11 families. Four of these species, Ictiobus bubalus, smallmouth buffalo; Moxostoma carinatum, river redhorse; Lepomis gulosus, warmouth; and Percina phoxocephala, slenderhead darter, have not been recorded previously from the Arkansas part of the Illinois. Eleven additional species have been reported previously that were not collected during this survey, for a total of 62 species known in the Illinois River

    Toward a Cognitive Classical Linguistics. The Embodied Basis of Constructions in Greek and Latin

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    The volume that gathers a series of papers bringing together the study of grammatical and syntactic constructions in Greek and Latin under the perspective of theories of embodied meaning developed in cognitive linguistics

    Patterning the insect eye: from stochastic to deterministic mechanisms

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    While most processes in biology are highly deterministic, stochastic mechanisms are sometimes used to increase cellular diversity, such as in the specification of sensory receptors. In the human and Drosophila eye, photoreceptors sensitive to various wavelengths of light are distributed randomly across the retina. Mechanisms that underlie stochastic cell fate specification have been analysed in detail in the Drosophila retina. In contrast, the retinas of another group of dipteran flies exhibit highly ordered patterns. Species in the Dolichopodidae, the "long-legged" flies, have regular alternating columns of two types of ommatidia (unit eyes), each producing corneal lenses of different colours. Individual flies sometimes exhibit perturbations of this orderly pattern, with "mistakes" producing changes in pattern that can propagate across the entire eye, suggesting that the underlying developmental mechanisms follow local, cellular-automaton-like rules. We hypothesize that the regulatory circuitry patterning the eye is largely conserved among flies such that the difference between the Drosophila and Dolichopodidae eyes should be explicable in terms of relative interaction strengths, rather than requiring a rewiring of the regulatory network. We present a simple stochastic model which, among its other predictions, is capable of explaining both the random Drosophila eye and the ordered, striped pattern of Dolichopodidae.Comment: 24 pages, 4 figure

    Understanding the mechanisms of amorphous creep through molecular simulation

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    Molecular processes of creep in metallic glass thin films are simulated at experimental timescales using a metadynamics-based atomistic method. Space-time evolutions of the atomic strains and nonaffine atom displacements are analyzed to reveal details of the atomic-level deformation and flow processes of amorphous creep in response to stress and thermal activations. From the simulation results, resolved spatially on the nanoscale and temporally over time increments of fractions of a second, we derive a mechanistic explanation of the well-known variation of creep rate with stress. We also construct a deformation map delineating the predominant regimes of diffusional creep at low stress and high temperature and deformational creep at high stress. Our findings validate the relevance of two original models of the mechanisms of amorphous plasticity: one focusing on atomic diffusion via free volume and the other focusing on stress-induced shear deformation. These processes are found to be nonlinearly coupled through dynamically heterogeneous fluctuations that characterize the slow dynamics of systems out of equilibrium. Keywords: creep, molecular simulation, deformation mechanism, atomistic modeling, metallic glassUnited States. Department of Energy (Grant DE-NE0008450)National Science Foundation (U.S.) (CAREER Grant DMR-1654548)United States. Department of Energy. Office of Basic Energy Sciences (Grant DE-SC0002633

    Business Practices and Procedures Regarding Smartphone Security

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    Smartphones are having a transformational effect on the way that users access, use, and store information. Smartphones have essentially blurred the line of what is considered a phone, becoming the pinnacle multi-tasking devices of today’s world. Current smartphones have their own dedicated operating system, Bluetooth capabilities, GPS, WiFi, constant network connection, PC connectivity, and are internet enabled, leading them to have similar security risks as that of a computer. Businesses are now worrying about the information employees are storing on these devices and want to find new ways to protect it (Schiller, 2011). Smartphone capabilities used for business application will be investigated for their potential vulnerabilities due to lack of employees’ precautions and smartphone usage

    Concentric circles and spiral configurations for large correlator arrays in radio astronomy

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    Aperture synthesis arrays are commonly used in radio astronomy to take images of radio point sources, with the planned Square Kilometre Array (SKA) being the most common example. One approach to enhancing the quality of the images is to optimize an antenna array configuration in a possible SKA implementation. An ideal arrangement must ensure optimal configurations to capture a clear image by either decreasing the sidelobe level (SLL) in the l-m domain or increasing the sampled data in the spatial-frequency domain. In this paper a novel configuration is considered to optimize the array by considering all possible observation situations through the positions of the antenna array elements via a mathematical model that we call geometrical method (GM). To demonstrate its efficiency, the technique is applied to developing an optimal configuration for the elements of the Giant Metrewave Radio Telescope (GMRT). The effect of these changes, particularly in the forms of circular and spiral arrangements, is discussed. It is found that a spiral configuration results in fewer overlapping samples than the number of antennas placed along three arms of the GMRT with fewer than 11% and 27% overlapping samples in the snapshot and 6 hr tracking observations, respectively. Finally, the spiral configuration reduces the first SLL from -13.01 dB, using the arms of the current GMRT configuration, to - 15.64 dB.Web of Science1564art. no. 17

    Crime, punishment, and evolution in an adversarial game

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    We examine the game theoretic properties of a model of crime first introduced by Short et al. (2010 Phys. Rev. E 82, 066114) as the SBD Adversarial Game. We identify the rationalizable strategies and one-shot equilibria under multiple equilibrium refinements. We further show that SBD’s main result about the effectiveness of defecting-punishers (“Informants”) in driving the system to evolve to the cooperative equilibrium under an imitation dynamic generalizes to a best response dynamic, though only under certain parameter regimes. The nature of this strategy’s role, however, differs significantly between the two dynamics: in the SBD imitation dynamic, Informants are sufficient but not necessary to achieve the cooperative equilibrium, while under the best response dynamic, Informants are necessary but not sufficient for convergence to cooperation. Since a policy of simply converting citizens to Informants will not guarantee success under best response dynamics, we identify alternative strategies that may help the system reach cooperation in this case, e.g., the use of moderate but not too severe punishments on criminals

    Reinforcing Regulatory Regimes: How States, Civil Society, and Codes of Conduct Promote Adherence to Global Labor Standards

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    In response to pressure from various stakeholders, many transnational businesses have developed codes of conduct and monitoring systems to ensure that working conditions in their supply chain factories meet global labor standards. Many observers have questioned whether these codes of conduct have any impact on working conditions or are merely a marketing tool to deflect criticism of valuable global brands. Using a proprietary dataset from one of the world’s largest social auditors, containing audit-level data for 31,915 audits of 14,922 establishments in 43 countries on behalf of 689 clients in 33 countries, we conduct one of the first large-scale comparative studies of adherence to labor codes of conduct to determine what combination of institutional conditions promotes compliance with the global labor standards embodied in codes. We find that these private transnational governance tools are most effective when they are embedded in states that have made binding domestic and international legal commitments to protect workers’ rights and that have high levels of press freedom and nongovernmental organization activity. Taken together, these findings suggest the importance of multiple, robust, overlapping, and reinforcing governance regimes to meaningful transnational regulation

    Equilibration of isolated macroscopic quantum systems

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    We investigate the equilibration of an isolated macroscopic quantum system in the sense that deviations from a steady state become unmeasurably small for the overwhelming majority of times within any sufficiently large time interval. The main requirements are that the initial state, possibly far from equilibrium, exhibits a macroscopic population of at most one energy level and that degeneracies of energy eigenvalues and of energy gaps (differences of energy eigenvalues) are not of exceedingly large multiplicities. Our approach closely follows and extends recent works by Short and Farrelly [2012 New J. Phys. 14 013063], in particular going beyond the realm of finite-dimensional systems and large effective dimensions.Comment: 19 page
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