379 research outputs found

    Kondo decoherence: finding the right spin model for iron impurities in gold and silver

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    We exploit the decoherence of electrons due to magnetic impurities, studied via weak localization, to resolve a longstanding question concerning the classic Kondo systems of Fe impurities in the noble metals gold and silver: which Kondo-type model yields a realistic description of the relevant multiple bands, spin and orbital degrees of freedom? Previous studies suggest a fully screened spin SS Kondo model, but the value of SS remained ambiguous. We perform density functional theory calculations that suggest S=3/2S = 3/2. We also compare previous and new measurements of both the resistivity and decoherence rate in quasi 1-dimensional wires to numerical renormalization group predictions for S=1/2,1S=1/2,1 and 3/2, finding excellent agreement for S=3/2S=3/2.Comment: 4 pages, 4 figures, shortened for PR

    Investigation of superconducting interactions and amorphous semiconductors

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    Research papers on superconducting interactions and properties and on amorphous materials are presented. The search for new superconductors with improved properties was largely concentrated on the study of properties of thin films. An experimental investigation of interaction mechanisms revealed no new superconductivity mechanism. The properties of high transition temperature, type 2 materials prepared in thin film form were studied. A pulsed field solenoid capable of providing fields in excess of 300 k0e was developed. Preliminary X-ray measurements were made of V3Si to determine the behavior of cell constant deformation versus pressure up to 98 kilobars. The electrical properties of amorphous semiconducting materials and bulk and thin film devices, and of amorphous magnetic materials were investigated for developing radiation hard, inexpensive switches and memory elements

    Evaporation of a packet of quantized vorticity

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    A recent experiment has confirmed the existence of quantized turbulence in superfluid He3-B and suggested that turbulence is inhomogenous and spreads away from the region around the vibrating wire where it is created. To interpret the experiment we study numerically the diffusion of a packet of quantized vortex lines which is initially confined inside a small region of space. We find that reconnections fragment the packet into a gas of small vortex loops which fly away. We determine the time scale of the process and find that it is in order of magnitude agreement with the experiment.Comment: figure 1a,b,c and d, figure2, figure

    Dynamics of ripple formation on silicon surfaces by ultrashort laser pulses in sub-ablation conditions

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    An investigation of ultrashort pulsed laser induced surface modification due to conditions that result in a superheated melted liquid layer and material evaporation are considered. To describe the surface modification occurring after cooling and resolidification of the melted layer and understand the underlying physical fundamental mechanisms, a unified model is presented to account for crater and subwavelength ripple formation based on a synergy of electron excitation and capillary waves solidification. The proposed theoretical framework aims to address the laser-material interaction in sub-ablation conditions and thus minimal mass removal in combination with a hydrodynamics-based scenario of the crater creation and ripple formation following surface irradiation with single and multiple pulses, respectively. The development of the periodic structures is attributed to the interference of the incident wave with a surface plasmon wave. Details of the surface morphology attained are elaborated as a function of the imposed conditions and results are tested against experimental data

    Slow 4He^{4}He Quenches Produce Fuzzy, Transient Vortices

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    We examine the Zurek scenario for the production of vortices in quenches of liquid 4He^{4}He in the light of recent experiments. Extending our previous results to later times, we argue that short wavelength thermal fluctuations make vortices poorly defined until after the transition has occurred. Further, if and when vortices appear, it is plausible that that they will decay faster than anticipated from turbulence experiments, irrespective of quench rates.Comment: 4 pages, Revtex file, no figures Apart from a more appropriate title, this paper differs from its predecessor by including temperature, as well as pressure, quenche

    Zurek-Kibble domain structures: The Dynamics of Spontaneous Vortex formation in Annular Josephson Tunnel Junctions

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    Phase transitions executed in a finite time show a domain structure with defects, that has been argued by Zurek and Kibble to depend in a characteristic way on the quench rate. In this letter we present an experiment to measure the Zurek-Kibble scaling exponent sigma. Using symmetric and long Josephson Tunnel Junctions, for which the predicted index is sigma = 0.25, we find sigma = 0.27 +/- 0.05. Further, there is agreement with the ZK prediction for the overall normalisation.Comment: To be published in Phys. Rev. Lett

    Anesthesiology for Trauma Medicine: Roles, Medications, Airway Management, and Multidisciplinary Team Coordination

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    Given the complex nature of trauma, a highly organized, multidisciplinary approach is necessary to ensure the best possible outcomes. Anesthesia providers play a critical role in the management and effective treatment of trauma patients. This chapter will address both the multidisciplinary and multitiered management of trauma patients with a focus on the intersection of trauma staff and anesthesia in three phases: the initial evaluation (i.e., in the bay), intraoperative care, and postoperative care. Included is a brief discussion on more recent methodologies and newly incorporated technologies in the resuscitation of trauma patients

    Commercial Bioinoculants Increase Root Length Colonization and Improve Petiole Nutrient Concentration of Field-grown Grapevines

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    Agricultural bioinoculants containing arbuscular mycorrhizal fungi represent a potential opportunity to reduce the dependence of grapevines (Vitis) on agrochemicals. This field study assessed the ability of four commercial bioinoculants to colonize grapevine roots and their effects on petiole nutrient concentration, berry composition, and root morphology of ‘Pinot noir’ (Vitis vinifera) grafted onto rootstock ‘Couderc 3309’ (Vitis riparia × Vitis rupestris) and ‘Riesling’ (V. vinifera) grafted onto ‘Couderc 3309’ and Selection Oppenheim four (Vitis berlandieri × V. riparia). Three bioinoculants increased root mycorrhizal colonization; however, regardless of the treatment, mycorrhizal fungal structures were enhanced. Grapevine petiole nutrient concentration was improved by bioinoculants. Root diameter, root length density, and specific root length increased with greater mycorrhizal root colonization. Using bioinoculants to reduce chemical fertilizers may be a good strategy to improve grapevine productivity and health in cool climates; however, the impact of mycorrhizal bioinoculants in the vineyard may differ among scion–rootstocks, edaphoclimatic conditions, and vineyard soil microbiomes

    Dynamics of Quantum Phase Transition in an Array of Josephson Junctions

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    We study the dynamics of the Mott insulator-superfluid quantum phase transition in a periodic 1D array of Josephson junctions. We show that crossing the critical point diabatically i.e. at a finite rate with a quench time τQ\tau_Q induces finite quantum fluctuations of the current around the loop proportional to τQ−1/6\tau_Q^{-1/6}. This scaling could be experimentally verified with in array of weakly coupled Bose-Einstein condensates or superconducting grains.Comment: 4 pages in RevTex, 3 .eps figures; 2 references added; accepted for publication in Phys.Rev.Let
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