2,747 research outputs found

    Fuzzy bases and the fuzzy dimension of fuzzy vector spaces

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    In this paper, new definitions of a fuzzy basis and a fuzzy dimension for a fuzzy vector space are presented. A fuzzy basis for a fuzzy vector space (E,mu)(E,mu) is a fuzzy set betabeta on EE. The cardinality of a fuzzy basis betabeta is called the fuzzy dimension of (E,mu)(E,mu). The fuzzy dimension of a finite dimensional fuzzy vector space is a fuzzy natural number. For a fuzzy vector space, any two fuzzy bases have the same cardinality. If widetildeE1widetilde{E}_1 and widetildeE2widetilde{E}_2 are two fuzzy vector spaces, then dim(widetildeE1+widetildeE2)+dim(widetildeE1capwidetildeE2)=dim(widetildeE1)+dim(widetildeE2)dim(widetilde{E}_1+widetilde{E}_2)+dim(widetilde{E}_1cap widetilde{E}_2)=dim(widetilde{E}_1) +dim(widetilde{E}_2) and dim(widetildermkerf)+dim(widetildermimf)=dim(widetildeE)dim({widetilde{rm{ker }}f})+dim({widetilde{rm{im }}f})=dim(widetilde{E}) hold without any restricted conditions. end{abstract

    Ediacaran Macro Body Fossils

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    This paper, Ediacaran Macro Body Fossils, reports a new discovery of well preserved three dimensional macro body fossils of the Ediacaran Period in central YunNan province in the People's Republic of China. These body fossils will enable more detailed and in-depth exploration of the evolution of multi-cellular macro organisms on this planet, whereas in the past, researches could only rely on cast or imprint fossils

    THE CHARTERISTICS OF LOWER LIMB MOMENTS IN BASEBALL PITCHING

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    The aim of this study was to examine the characteristics of lower limb moments in baseball pitching. Ten senior high school pitchers participated in this study (age: 16.7±0.7 yr; height: 179.1±5.8 cm; body mass: 73.7±8.9 kg). Ten VICON cameras (200Hz) and two Kistler force plates (1000Hz) fixed on a pitching mound were used to collect 3-D kinematic and GRF data. Three successful trials for each subject were used to compute lower limbs joint moments. The results indicated, for the pivot leg, ankle plantarflexor moment, knee and hip adductor moment are the key moments to transform energy to trunk and upper extremities by driving and rotating the knee. For the lead leg, ankle plantarflexor moment and hip flexor moment are the main joint moments to brake upper extremities by a knee extention during baseball pitching

    Unconventional Superconducting Symmetry in a Checkerboard Antiferromagnet

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    We use a renormalized mean field theory to study the Gutzwiller projected BCS states of the extended Hubbard model in the large UU limit, or the tt-tt'-JJ-JJ' model on a two-dimensional checkerboard lattice. At small t/tt'/t, the frustration due to the diagonal terms of tt' and JJ' does not alter the dx2y2d_{x^2-y^2}-wave pairing symmetry, and the negative (positive) t/tt'/t enhances (suppresses) the pairing order parameter. At large t/tt'/t, the ground state has an extended s-wave symmetry. At the intermediate t/tt'/t, the ground state is d+idd+id or d+isd+is-wave with time reversal symmetry broken.Comment: 6 pages, 6 figure

    Andreev and Single Particle Tunneling Spectroscopies in Underdoped Cuprates

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    We study tunneling spectroscopy between a normal metal and underdoped cuprate superconductor modeled by a phenomenological theory in which the pseudogap is a precursor to the undoped Mott insulator. In the transparent tunneling limit, the spectra show a small energy gap associated with Andreev reflection. In the Giaever limit, the spectra show a large energy gap associated with single particle tunneling. Our theory semi-quantitatively describes the two gap behavior observed in tunneling experiments.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Lett. minor changes of reference

    Charge Ordered RVB States in the Doped Cuprates

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    We study charge ordered d-wave resonating valence bond states (dRVB) in the doped cuprates, and estimate the energies of these states in a generalized tJt-J model by using a renormalized mean field theory. The long range Coulomb potential tends to modulate the charge density in favor of the charge ordered RVB state. The possible relevance to the recently observed 4×44 \times 4 checkerboard patterns in tunnelling conductance in high TcT_c cuprates is discussed.Comment: 4 pages, 4 figures, 3 table

    SAGITTAL AND FRONTAL LOWER LIMBS KINETICS DURING STEPPING DOWN IN TAICHI ELDERLY

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    The aim was to compare the kinetic characteristics of the beginning stance phase during stepping down in Taichi and normal elderly. Nine elderly taichi subjects and eleven matched controls participated in the study. Whole body kinematics and ground reaction forces (GRF) were recorded using 10 Vicon cameras (250Hz) and two Kistler force plates (1000Hz). Sagittal and frontal kinetic parameters were calculated by using Visual3D software. Differences in variables between groups were tested using t-test. The results indicated hip extensor / knee flexor / ankle plantarflexor / support moment and peak hip/knee/ankle power were greater in Taichi group. It was concluded that Taichi group has ability to translate forward movement (hip moment / power), to control body (knee moment /power) and to absorption energy (ankle moment / power) in sagittal plane
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