2,513 research outputs found

    Quantum orbits of R-matrix type

    Get PDF
    Given a simple Lie algebra \gggg, we consider the orbits in \gggg^* which are of R-matrix type, i.e., which possess a Poisson pencil generated by the Kirillov-Kostant-Souriau bracket and the so-called R-matrix bracket. We call an algebra quantizing the latter bracket a quantum orbit of R-matrix type. We describe some orbits of this type explicitly and we construct a quantization of the whole Poisson pencil on these orbits in a similar way. The notions of q-deformed Lie brackets, braided coadjoint vector fields and tangent vector fields are discussed as well.Comment: 18 pp., Late

    Impurity Band Conduction in a High Temperature Ferromagnetic Semiconductor

    Full text link
    The band structure of a prototypical dilute ferromagnetic semiconductor, Ga1x_{1-x}Mnx_{x}As, is studied across the phase diagram via optical spectroscopy. We prove that the Fermi energy (EFE_{F}) resides in a Mn induced impurity band (IB). This conclusion is based upon careful analysis of the frequency and temperature dependence of the optical conductivity (σ1(ω,T)\sigma_{1}(\omega,T)). From our analysis of σ1(ω,T)\sigma_{1}(\omega,T) we infer a large effective mass (mm^*) of the carriers, supporting the view that conduction occurs in an IB. Our results also provide useful insights into the transport properties of Mn-doped GaAs.Comment: 4 pages, 4 figure

    Thermal transport in thin films measured by time-resolved, grazing incidence x-ray diffraction

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98715/1/JApplPhys_110_102203.pd

    The first products made in space: Monodisperse latex particles

    Get PDF
    The preparation of large particle size 3 to 30 micrometer monodisperse latexes in space confirmed that original rationale unequivocally. The flight polymerizations formed negligible amounts of coagulum as compared to increasing amounts for the ground-based polymerizations. The number of offsize large particles in the flight latexes was smaller than in the ground-based latexes. The particle size distribution broadened and more larger offsize particles were formed when the polymerizations of the partially converted STS-4 latexes were completed on Earth. Polymerization in space also showed other unanticipated advantages. The flight latexes had narrower particle size distributions than the ground-based latexes. The particles of the flight latexes were more perfect spheres than those of the ground-based latexes. The superior uniformity of the flight latexes was confirmed by the National Bureau of Standards acceptance of the 10 micrometer STS-6 latex and the 30 micrometer STS-11 latexes as Standard Reference Materials, the first products made in space for sale on Earth. The polymerization rates in space were the same as those on Earth within experimental error. Further development of the ground-based polymerization recipes gave monodisperse particles as large as 100 micrometer with tolerable levels of coagulum, but their uniformity was significantly poorer than the flight latexes. Careful control of the polymerization parameters gave uniform nonspherical particles: symmetrical and asymmetrical doublets, ellipsoids, egg-shaped, ice cream cone-shaped, and popcorn-shaped particles

    Antisite effect on ferromagnetism in (Ga,Mn)As

    Full text link
    We study the Curie temperature and hole density of (Ga,Mn)As while systematically varying the As-antisite density. Hole compensation by As-antisites limits the Curie temperature and can completely quench long-range ferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by molecular beam epitaxy without substrate rotation in order to smoothly vary the As to Ga flux ratio across a single wafer. This technique allows for a systematic study of the effect of As stoichiometry on the structural, electronic, and magnetic properties of (Ga,Mn)As. For concentrations less than 1.5% Mn, a strong deviation from Tc ~ p^0.33 is observed. Our results emphasize that proper control of As-antisite compensation is critical for controlling the Curie temperatures in (Ga,Mn)As at the low doping limit.Comment: 10 pages, 7 figure

    Fundamentals of microcrack nucleation mechanics

    Get PDF
    A foundation for ultrasonic evaluation of microcrack nucleation mechanics is identified in order to establish a basis for correlations between plane strain fracture toughness and ultrasonic factors through the interaction of elastic waves with material microstructures. Since microcracking is the origin of (brittle) fracture, it is appropriate to consider the role of stress waves in the dynamics of microcracking. Therefore, the following topics are discussed: (1) microstress distributions with typical microstructural defects located in the stress field; (2) elastic wave scattering from various idealized defects; and (3) dynamic effective-properties of media with randomly distributed inhomogeneities

    Immobilization of Polyethylene Oxide Surfactants for Non-Fouling Biomaterial Surfaces Using an Argon Glow Discharge Treatment

    Get PDF
    A non-fouling (protein-resistant) polymer surface is achieved by the covalent immobilization of polyethylene oxide (PEO) surfactants using an inert gas discharge treatment. Treated surfaces have been characterized using electron spectroscopy for chemical analysis (ESCA), static secondary ion mass spectrometry (SSIMS), water contact angle measurement, fibrinogen adsorption, and platelet adhesion. This paper is intended to review our recent work in using this simple surface modification process to obtain wettable polymer surfaces in general, and non-fouling biomaterial surfaces in particular

    Proceedings of the 7th International Conference on Systematic Innovation - ICSI 2016

    Get PDF
    It is our pleasure to welcome you at the 7th International Conference on Systematic Innovation. It is our objective to provide a forum for the discussion and dissemination of recent advances in the field of TRIZ Methodology, Knowledge-Based and Systematic Innovation. The goal is to enable practitioners, researchers and scientists to exchange ideas on the these topics and to provide an international forum for exchanging new ideas and recent achievements by the TRIZ community and enabling further advances and collaboration with the industrial community. We wish to express our sincere gratitude to the members of the organizing, scientific and technical committees. The reviewers of the papers had a very important job, contributing significantly to the success of the conference. We also wish to express our thanks to our invited speakers. Very special thanks to our students, sponsors and to all who helped us with logistics, conference website, and publications. Welcome to Portugal and Lisbon. We hope you all have a very happy and rewarding meeting.publishersversionpublishe
    corecore