25,636 research outputs found

    Farm Accidents Costly Insurance Lessens the Burden

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    Peeling Back the Onion of Cyber Espionage after Tallinn 2.0

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    Tallinn 2.0 represents an important advancement in the understanding of international law’s application to cyber operations below the threshold of force. Its provisions on cyber espionage will be instrumental to states in grappling with complex legal problems in the area of digital spying. The law of cyber espionage as outlined by Tallinn 2.0, however, is substantially based on rules that have evolved outside of the digital context, and there exist serious ambiguities and limitations in its framework. This Article will explore gaps in the legal structure and consider future options available to states in light of this underlying mismatch

    Observation of Single Transits in Supercooled Monatomic Liquids

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    A transit is the motion of a system from one many-particle potential energy valley to another. We report the observation of transits in molecular dynamics (MD) calculations of supercooled liquid argon and sodium. Each transit is a correlated simultaneous shift in the equilibrium positions of a small local group of particles, as revealed in the fluctuating graphs of the particle coordinates versus time. This is the first reported direct observation of transit motion in a monatomic liquid in thermal equilibrium. We found transits involving 2 to 11 particles, having mean shift in equilibrium position on the order of 0.4 R_1 in argon and 0.25 R_1 in sodium, where R_1 is the nearest neighbor distance. The time it takes for a transit to occur is approximately one mean vibrational period, confirming that transits are fast.Comment: 19 pages, 8 figure

    Metal alloy resistivity measurements at very low temperatures

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    High speed, automated system accurately measures to approximately one percent in three minutes. System identifies materials having constant thermal or electric conductivity, predicts new material properties, develops alloys in accordance with desired specifications, and develops nondestructive devices for measuring precipitation hardening

    Our Land Policy Takes Shape

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    The American record of land misuse is almost unparalleled. Perhaps only the Chinese can match it. But they have been on the job longer than we have. It has often been remarked that the Chinese are the greatest individualists on earth. They cut their forests, silted up their streams, and destroyed millions of acres of their land by erosion. Their soil, shorn o£ its cover, fed countless dust storms. Again and again their individualistic handling of the land has exposed millions of Chinese to flood and drought, to famine, pestilence, and death

    Control and Elimination of Quackgrass

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    This publication describes Quackgrass characteristics and identification information. Control methods such as intensive cultivation, special cropping, and chemical application recommendations are also included

    Ab initio parametrised model of strain-dependent solubility of H in alpha-iron

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    The calculated effects of interstitial hydrogen on the elastic properties of alpha-iron from our earlier work are used to describe the H interactions with homogeneous strain fields using ab initio methods. In particular we calculate the H solublility in Fe subject to hydrostatic, uniaxial, and shear strain. For comparison, these interactions are parametrised successfully using a simple model with parameters entirely derived from ab initio methods. The results are used to predict the solubility of H in spatially-varying elastic strain fields, representative of realistic dislocations outside their core. We find a strong directional dependence of the H-dislocation interaction, leading to strong attraction of H by the axial strain components of edge dislocations and by screw dislocations oriented along the critical slip direction. We further find a H concentration enhancement around dislocation cores, consistent with experimental observations.Comment: part 2/2 from splitting of 1009.3784 (first part was 1102.0187), minor changes from previous version

    Analysing Magnetism Using Scanning SQUID Microscopy

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    Scanning superconducting quantum interference device microscopy (SSM) is a scanning probe technique that images local magnetic flux, which allows for mapping of magnetic fields with high field and spatial accuracy. Many studies involving SSM have been published in the last decades, using SSM to make qualitative statements about magnetism. However, quantitative analysis using SSM has received less attention. In this work, we discuss several aspects of interpreting SSM images and methods to improve quantitative analysis. First, we analyse the spatial resolution and how it depends on several factors. Second, we discuss the analysis of SSM scans and the information obtained from the SSM data. Using simulations, we show how signals evolve as a function of changing scan height, SQUID loop size, magnetization strength and orientation. We also investigated 2-dimensional autocorrelation analysis to extract information about the size, shape and symmetry of magnetic features. Finally, we provide an outlook on possible future applications and improvements.Comment: 16 pages, 10 figure

    Muon spin relaxation and rotation study on the solid solution of the two spin-gap systems (CH3)2CHNH3-CuCl3 and (CH3)2CHNH3-CuBr3

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    Muon-spin-rotation and relaxation studies have been performed on (CH3_3)2_2CHNH3_3Cu(Clx_xBr1x_{1-x})3_3 with xx=0.85 and 0.95, which are solid solutions of the two isomorphic spin-gap systems (CH3_3)2_2CHNH3_3CuCl3_3 and (CH3_3)2_2CHNH3_3CuBr3_3 with different spin gaps. The sample with xx=0.85 showed a clear muon spin rotation under zero-field below TNT_{\rm N}=11.65K, indicating the existence of a long-range antiferromagnetic order. A critical exponent of the hyperfine field was obtained to be β\beta=0.33, which agrees with 3D-Ising model. In the other sample with xx=0.95, an anomalous enhancement of the muon spin relaxation was observed at very low temperatures indicating a critical slowing down due to a magnetic instability of the ground state
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