2,784 research outputs found

    Bioactive glass engineered coatings for Ti6Al4V alloys: Influence of strontium substitution for calcium on sintering behaviour

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    NOTICE: this is the author’s version of a work that was accepted for publication in JOURNAL OF NON-CRYSTALLINE SOLIDS. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in JOURNAL OF NON-CRYSTALLINE SOLIDS, [VOL 356, ISSUE 44-49, (2010), DOI 10.1016/j.jnoncrysol.2010.05.01

    On the Mapping of Time-Dependent Densities onto Potentials in Quantum Mechanics

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    The mapping of time-dependent densities on potentials in quantum mechanics is critically examined. The issue is of significance ever since Runge and Gross (Phys. Rev. Lett. 52, 997 (1984)) established the uniqueness of the mapping, forming a theoretical basis for time-dependent density functional theory. We argue that besides existence (so called v-representability) and uniqueness there is an important question of stability and chaos. Studying a 2-level system we find innocent, almost constant densities that cannot be constructed from any potential (non-existence). We further show via a Lyapunov analysis that the mapping of densities on potentials has chaotic regions in this case. In real space the situation is more subtle. V-representability is formally assured but the mapping is often chaotic making the actual construction of the potential almost impossible. The chaotic nature of the mapping, studied for the first time here, has serious consequences regarding the possibility of using TDDFT in real-time settings

    Structure of fluoride-containing bioactive glasses

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    Subpicosecond transient absorption studies of the photocycloreversion of an aromatic endoperoxide.

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    Selbstbestimmung und Selbstverständnis: Themenschwerpunkte im Umgang mit der Patientenverfügung

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    Measuring Polynomial Invariants of Multi-Party Quantum States

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    We present networks for directly estimating the polynomial invariants of multi-party quantum states under local transformations. The structure of these networks is closely related to the structure of the invariants themselves and this lends a physical interpretation to these otherwise abstract mathematical quantities. Specifically, our networks estimate the invariants under local unitary (LU) transformations and under stochastic local operations and classical communication (SLOCC). Our networks can estimate the LU invariants for multi-party states, where each party can have a Hilbert space of arbitrary dimension and the SLOCC invariants for multi-qubit states. We analyze the statistical efficiency of our networks compared to methods based on estimating the state coefficients and calculating the invariants.Comment: 8 pages, 4 figures, RevTex4, v2 references update

    Trapping Solids at the Inner Edge of the Dead Zone: 3-D Global MHD Simulations

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    The poorly-ionized interior of the protoplanetary disk is the location where dust coagulation processes may be most efficient. However even here, planetesimal formation may be limited by the loss of solid material through radial drift, and by collisional fragmentation of the particles. Our aim is to investigate the possibility that solid particles are trapped at local pressure maxima in the dynamically evolving disk. We perform the first 3-D global non-ideal MHD calculations of the disk treating the turbulence driven by the magneto-rotational instability. The domain contains an inner MRI-active region near the young star and an outer midplane dead zone, with the transition between the two modeled by a sharp increase in the magnetic diffusivity. The azimuthal magnetic fields generated in the active zone oscillate over time, changing sign about every 150 years. We thus observe the radial structure of the `butterfly pattern' seen previously in local shearing-box simulations. The mean magnetic field diffuses from the active zone into the dead zone, where the Reynolds stress nevertheless dominates. The greater total accretion stress in the active zone leads to a net reduction in the surface density, so that after 800 years an approximate steady state is reached in which a local radial maximum in the midplane pressure lies near the transition radius. We also observe the formation of density ridges within the active zone. The dead zone in our models possesses a mean magnetic field, significant Reynolds stresses and a steady local pressure maximum at the inner edge, where the outward migration of planetary embryos and the efficient trapping of solid material are possible.Comment: 17 pages, 30 *.ps files for figures. Accepted 16 November 2009 in A&

    Casimir elements from the Brauer-Schur-Weyl duality

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    We consider Casimir elements for the orthogonal and symplectic Lie algebras constructed with the use of the Brauer algebra. We calculate the images of these elements under the Harish-Chandra isomorphism and thus show that they (together with the Pfaffian-type element in the even orthogonal case) are algebraically independent generators of the centers of the corresponding universal enveloping algebras.Comment: 19 page

    Universal deformation rings of modules for algebras of dihedral type of polynomial growth

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    Let k be an algebraically closed field, and let \Lambda\ be an algebra of dihedral type of polynomial growth as classified by Erdmann and Skowro\'{n}ski. We describe all finitely generated \Lambda-modules V whose stable endomorphism rings are isomorphic to k and determine their universal deformation rings R(\Lambda,V). We prove that only three isomorphism types occur for R(\Lambda,V): k, k[[t]]/(t^2) and k[[t]].Comment: 11 pages, 2 figure

    Hormonal replacement therapy prescribing in menopausal women in the UK: A descriptive study

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    BACKGROUND: Recent studies on the prescribing of hormonal replacement therapy (HRT) medicines to treat symptoms of menopause are lacking. AIM: To describe the prescribing of HRT in a cohort of UK menopausal women. DESIGN & SETTING: Population-based drug utilization study using IQVIA Medical Research Database. METHOD: Primary care data of women with recorded menopause and/or 50 years and older between January 2010 and November 2021 were extracted from the database. The incidence rate (IR) of women who received their first prescription for HRT was calculated annually using person-years at risk (PYAR) as the denominator. IRs of HRT were estimated by type and route of administration. Relative changes in annual IR were expressed as percentages and the average percentage change was assessed using linear regression. Annual prescribing prevalence per 100 women was calculated using mid-year menopausal population estimates. RESULTS: The IR of prescribing of HRT increased from 5.01 in 2010-18.16 per 1000 PYAR in 2021, a relative increase of 13.64% (95% CI 6.97-20.30) per year. IR of fixed combinations of HRT increased from 3.33 to 12.23 per 1000 PYAR in 2010 and 2021, respectively. Transdermal formulations of HRT increased from 1.48 to 14.55 per 1000 PYAR in 2010 and 2021, respectively. The overall proportion of women in receipt of a prescription for HRT changed from 7.89% in 2010 to 6.8% in 2020. CONCLUSION: Our study shows steady increase in the number of women receiving their first prescription for HRT during the study period which suggests regained acceptance of HRT medicines
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