8,928 research outputs found

    Traversing the time of COVID-19 lockdown with mindful leisure

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    Comments on "Proving Reliability of Anonymous Information in VANETs" by Kounga et al.

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    Securing emergent behaviour in swarm robotics

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    Doping evoluton of antiferromagnetic order and structural distortion in LaFeAsO1−x_{1-x}Fx_x

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    We use neutron scattering to study the structural distortion and antiferromagnetic (AFM) order in LaFeAsO1−x_{1-x}Fx_{x} as the system is doped with fluorine (F) to induce superconductivity. In the undoped state, LaFeAsO exhibits a structural distortion, changing the symmetry from tetragonal (space group P4/nmmP4/nmm) to orthorhombic (space group CmmaCmma) at 155 K, and then followed by an AFM order at 137 K. Doping the system with F gradually decreases the structural distortion temperature, but suppresses the long range AFM order before the emergence of superconductivity. Therefore, while superconductivity in these Fe oxypnictides can survive in either the tetragonal or the orthorhombic crystal structure, it competes directly with static AFM order.Comment: reference update

    Threshold Anonymous Announcement in VANETs.

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    Vehicular ad hoc networks (VANETs) allow wireless communications between vehicles without the aid of a central server. Reliable exchanges of information about road and traffic conditions allow a safer and more comfortable travelling environment. However, such profusion of information may allow unscrupulous parties to violate user privacy. On the other hand, a degree of auditability is desired for law enforcement and maintenance purposes. In this paper we propose a Threshold Anonymous Announcement service using direct anonymous attestation and one-time anonymous authentication to simultaneously achieve the seemingly contradictory goals of reliability, privacy and auditability

    Spin gap and magnetic resonance in superconducting BaFe1.9_{1.9}Ni%_{0.1}As2_{2}

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    We use neutron spectroscopy to determine the nature of the magnetic excitations in superconducting BaFe1.9_{1.9}Ni0.1_{0.1}As2_{2} (Tc=20T_{c}=20 K). Above TcT_{c} the excitations are gapless and centered at the commensurate antiferromagnetic wave vector of the parent compound, while the intensity exhibits a sinusoidal modulation along the c-axis. As the superconducting state is entered a spin gap gradually opens, whose magnitude tracks the TT-dependence of the superconducting gap observed by angle resolved photoemission. Both the spin gap and magnetic resonance energies are temperature \textit{and} wave vector dependent, but their ratio is the same within uncertainties. These results suggest that the spin resonance is a singlet-triplet excitation related to electron pairing and superconductivity.Comment: 4 pages, 4 figure

    The Effect of Textiles on Perceived Physiological Comfort While Backpacking in the Cold

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    Clothing is the primary means that wilderness backpackers have to protect themselves from illnesses and injuries that can occur while hiking in the cold. Currently, backpackers are recommended to dress in clothing layers; however, when hiking in the cold, this system may not meet backpackers’ simultaneous, yet conflicting needs for thermal insulation and heat dissipation
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