278 research outputs found
Skyrmion Dynamics and NMR Line Shapes in QHE Ferromagnets
The low energy charged excitations in quantum Hall ferromagnets are
topological defects in the spin orientation known as skyrmions. Recent
experimental studies on nuclear magnetic resonance spectral line shapes in
quantum well heterostructures show a transition from a motionally narrowed to a
broader `frozen' line shape as the temperature is lowered at fixed filling
factor. We present a skyrmion diffusion model that describes the experimental
observations qualitatively and shows a time scale of for
the transport relaxation time of the skyrmions. The transition is characterized
by an intermediate time regime that we demonstrate is weakly sensitive to the
dynamics of the charged spin texture excitations and the sub-band electronic
wave functions within our model. We also show that the spectral line shape is
very sensitive to the nuclear polarization profile along the z-axis obtained
through the optical pumping technique.Comment: 6 pages, 4 figure
Non-Abelian (p,q) Strings in the Warped Deformed Conifold
We calculate the tension of -strings in the warped deformed conifold
using the non-Abelian DBI action. In the large flux limit, we find exact
agreement with the recent expression obtained by Firouzjahi, Leblond and
Henry-Tye up to and including order terms if is also taken to be
large. Furthermore using the finite prescription for the symmetrised trace
operation we anticipate the most general expression for the tension valid for
any . We find that even in this instance, corrections to the tension
scale as which is not consistent with simple Casimir scaling.Comment: 18 pages, Latex, 1 figure; Added a discussion of the case when the
warp factor parameter and typos correcte
A variational approach to the macroscopic electrodynamics of anisotropic hard superconductors
We consider the Bean's critical state model for anisotropic superconductors.
A variational problem solved by the quasi--static evolution of the internal
magnetic field is obtained as the -limit of functionals arising from
the Maxwell's equations combined with a power law for the dissipation.
Moreover, the quasi--static approximation of the internal electric field is
recovered, using a first order necessary condition. If the sample is a long
cylinder subjected to an axial uniform external field, the macroscopic
electrodynamics is explicitly determined.Comment: 24 pages, 15 figure
Practical Flapping Mechanisms for 20cm-span Micro Air Vehicles
[[abstract]]In the body of research relevant to high-performance flapping micro air vehicles (MAV), development of light-weight, compact and energy-efficient flapping mechanisms occupies a position of primacy due to its direct impact on the flight performance and mission capability. Realization of such versatile flapping mechanism with additional ability of producing thrust levels that fulfill requirements of cruising forward flight and vertical take-off and landing (VTOL) conditions demand extensive design validation and performance evaluation. This paper presents a concerted approach for mechanism development of a 20 cm span flapping MAV through an iterative design process and synergistic fabrication options involving electrical-discharge-wire-cutting (EDWC) and injection molding. Dynamic characterization of each mechanism is done through high speed photography, power take-off measurement, wind tunnel testing and proof-of-concept test flights. The research outcome represents best-in-class mechanism for a 20 cm span flapping MAV with desirable performance features of extra-large flapping stroke up to 100°, minimal transverse vibrations and almost no phase lag between the wings.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]US
Quasivariational solutions for first order quasilinear equations with gradient constraint
We prove the existence of solutions for an evolution quasi-variational
inequality with a first order quasilinear operator and a variable convex set,
which is characterized by a constraint on the absolute value of the gradient
that depends on the solution itself. The only required assumption on the
nonlinearity of this constraint is its continuity and positivity. The method
relies on an appropriate parabolic regularization and suitable {\em a priori}
estimates. We obtain also the existence of stationary solutions, by studying
the asymptotic behaviour in time. In the variational case, corresponding to a
constraint independent of the solution, we also give uniqueness results
The controlled teleportation of an arbitrary two-atom entangled state in driven cavity QED
In this paper, we propose a scheme for the controlled teleportation of an
arbitrary two-atom entangled state
in driven cavity QED.
An arbitrary two-atom entangled state can be teleported perfectly with the help
of the cooperation of the third side by constructing a three-atom GHZ entangled
state as the controlled channel. This scheme does not involve apparent (or
direct) Bell-state measurement and is insensitive to the cavity decay and the
thermal field. The probability of the success in our scheme is 1.0.Comment: 10 page
NMR and NQR Fluctuation Effects in Layered Superconductors
We study the effect of thermal fluctuations of the s-wave order parameter of
a quasi two dimensional superconductor on the nuclear spin relaxation rate near
the transition temperature Tc. We consider both the effects of the amplitude
fluctuations and the Berezinskii-Kosterlitz-Thouless (BKT) phase fluctuations
in weakly coupled layered superconductors. In the treatment of the amplitude
fluctuations we employ the Gaussian approximation and evaluate the longitudinal
relaxation rate 1/T1 for a clean s-wave superconductor, with and without pair
breaking effects, using the static pair fluctuation propagator D. The increase
in 1/T1 due to pair breaking in D is overcompensated by the decrease arising
from the single particle Green's functions. The result is a strong effect on
1/T1 for even a small amount of pair breaking. The phase fluctuations are
described in terms of dynamical BKT excitations in the form of pancake
vortex-antivortex (VA) pairs. We calculate the effect of the magnetic field
fluctuations caused by the translational motion of VA excitations on 1/T1 and
on the transverse relaxation rate 1/T2 on both sides of the BKT transitation
temperature T(BKT)<Tc. The results for the NQR relaxation rates depend strongly
on the diffusion constant that governs the motion of free and bound vortices as
well as the annihilation of VA pairs. We discuss the relaxation rates for real
multilayer systems where the diffusion constant can be small and thus increase
the lifetime of a VA pair, leading to an enhancement of the rates. We also
discuss in some detail the experimental feasibility of observing the effects of
amplitude fluctuations in layered s-wave superconductors such as the
dichalcogenides and the effects of phase fluctuations in s- or d-wave
superconductors such as the layered cuprates.Comment: 38 pages, 12 figure
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
The spiritual organization: critical reflections on the instrumentality of workplace spirituality
Authors' draft of article. Final version published by Routledge in Journal of Management, Spirituality and Religion available online at: http://www.tandf.co.uk/journals/titles/14766086.aspThis paper offers a theoretical contribution to the current debate on workplace spirituality by: (a) providing a selective critical review of scholarship, research and corporate practices which treat workplace spirituality in performative terms, that is, as a resource or means to be manipulated instrumentally and appropriated for economic ends; (b) extending Ezioni’s analysis of complex organizations and proposing a new category, the ‘spiritual organization’, and; (c) positing three alternative positions with respect to workplace spirituality that follow from the preceding critique. The spiritual organization can be taken to represent the development of a trajectory of social technologies that have sought, incrementally, to control the bodies, minds, emotions and souls of employees. Alternatively, it might be employed to conceptualize the way in which employees use the workplace as a site for pursuing their own spiritualities (a reverse instrumentalism). Finally, we consider the possible incommensurability of ‘work organization’ and ‘spirituality’ discourses
Fungal Planet description sheets: 1042–1111
Novel species of fungi described in this study include those from various countries as follows: Antarctica, Cladosporium arenosum from marine sediment sand. Argentina, Kosmimatamyces alatophylus (incl. Kosmimatamyces gen. nov.) from soil. Australia, Aspergillus banksianus, Aspergillus kumbius, Aspergillus luteorubrus, Aspergillus malvicolor and Aspergillus nanangensis from soil, Erysiphe medicaginis from leaves of Medicago polymorpha, Hymenotorrendiella communis on leaf litter of Eucalyptus bicostata, Lactifluus albopicri and Lactifluus austropiperatus on soil, Macalpinomyces collinsiae on Eriachne benthamii, Marasmius vagus on soil, Microdochium dawsoniorum from leaves of Sporobolus natalensis, Neopestalotiopsis nebuloides from leaves of Sporobolus elongatus, Pestalotiopsis etonensis from leaves of Sporobolus jacquemontii, Phytophthora personensis from soil associated with dying Grevillea mccutcheonii. Brazil, Aspergillus oxumiae from soil, Calvatia baixaverdensis on soil, Geastrum calycicoriaceum on leaf litter, Greeneria kielmeyerae on leaf spots of Kielmeyera coriacea. Chile, Phytophthora aysenensis on collar rot and stem of Aristotelia chilensis. Croatia, Mollisia gibbospora on fallen branch of Fagus sylvatica. Czech Republic, Neosetophoma hnaniceana from Buxus sempervirens. Ecuador, Exophiala frigidotolerans from soil. Estonia, Elaphomyces bucholtzii in soil. France, Venturia paralias from leaves of Euphorbia paralias. India, Cortinarius balteatoindicus and Cortinarius ulkhagarhiensis on leaf litter. Indonesia, Hymenotorrendiella indonesiana on Eucalyptus urophylla leaf litter. Italy, Penicillium taurinense from indoor chestnut mill. Malaysia, Hemileucoglossum kelabitense on soil, Satchmopsis pini on dead needles of Pinus tecunumanii. Poland, Lecanicillium praecognitum on insects' frass. Portugal, Neodevriesia aestuarina from saline water. Republic of Korea, Gongronella namwonensis from freshwater. Russia, Candida pellucida from Exomias pellucidus, Heterocephalacria septentrionalis as endophyte from Cladonia rangiferina, Vishniacozyma phoenicis from dates fruit, Volvariella paludosa from swamp. Slovenia, Mallocybe crassivelata on soil. South Africa, Beltraniella podocarpi, Hamatocanthoscypha podocarpi, Coleophoma podocarpi and Nothoseiridium podocarpi (incl. Nothoseiridium gen. nov.)from leaves of Podocarpus latifolius, Gyrothrix encephalarti from leaves of Encephalartos sp., Paraphyton cutaneum from skin of human patient, Phacidiella alsophilae from leaves of Alsophila capensis, and Satchmopsis metrosideri on leaf litter of Metrosideros excelsa. Spain, Cladophialophora cabanerensis from soil, Cortinarius paezii on soil, Cylindrium magnoliae from leaves of Magnolia grandiflora, Trichophoma cylindrospora (incl. Trichophoma gen. nov.) from plant debris, Tuber alcaracense in calcareus soil, Tuber buendiae in calcareus soil. Thailand, Annulohypoxylon spougei on corticated wood, Poaceascoma filiforme from leaves of unknown Poaceae. UK, Dendrostoma luteum on branch lesions of Castanea sativa, Ypsilina buttingtonensis from heartwood of Quercus sp. Ukraine, Myrmecridium phragmiticola from leaves of Phragmites australis. USA, Absidia pararepens from air, Juncomyces californiensis (incl. Juncomyces gen. nov.) from leaves of Juncus effusus, Montagnula cylindrospora from a human skin sample, Muriphila oklahomaensis (incl. Muriphila gen. nov.)on outside wall of alcohol distillery, Neofabraea eucalyptorum from leaves of Eucalyptus macrandra, Diabolocovidia claustri (incl. Diabolocovidia gen. nov.)from leaves of Serenoa repens, Paecilomyces penicilliformis from air, Pseudopezicula betulae from leaves of leaf spots of Populus tremuloides. Vietnam, Diaporthe durionigena on branches of Durio zibethinus and Roridomyces pseudoirritans on rotten wood. Morphological and culture characteristics are supported by DNA barcodes
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