4,970 research outputs found

    Micromachined Oblique Incidence Refleciometry (OIR) Probe for Skin Cancer Detection

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    We present the design, fabrication and in-vivo testing of a new micromachined probe for skin cancer detection based on oblique incidence reflectometry (OIR). The device miniaturization and fabrication precision provided by micromachining ensure reliable and repeatable high performance of the probe. The developed probe has been tested in a pre-clinical condition. An overall sensitivity of 100% and specificity of 93% haven been achieved in the classification of malignant and benign skin lesions

    Finite element approximation of the p()p(\cdot)-Laplacian

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    We study a~priori estimates for the Dirichlet problem of the p()p(\cdot)-Laplacian, div(vp()2v)=f.-\mathrm{div}(|\nabla v|^{p(\cdot)-2} \nabla v) = f. We show that the gradients of the finite element approximation with zero boundary data converges with rate O(hα)O(h^\alpha) if the exponent pp is α\alpha-H\"{o}lder continuous. The error of the gradients is measured in the so-called quasi-norm, i.e. we measure the L2L^2-error of vp22v|\nabla v|^{\frac{p-2}{2}} \nabla v

    Nonlinear viscosity and velocity distribution function in a simple longitudinal flow

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    A compressible flow characterized by a velocity field ux(x,t)=ax/(1+at)u_x(x,t)=ax/(1+at) is analyzed by means of the Boltzmann equation and the Bhatnagar-Gross-Krook kinetic model. The sign of the control parameter (the longitudinal deformation rate aa) distinguishes between an expansion (a>0a>0) and a condensation (a<0a<0) phenomenon. The temperature is a decreasing function of time in the former case, while it is an increasing function in the latter. The non-Newtonian behavior of the gas is described by a dimensionless nonlinear viscosity η(a)\eta^*(a^*), that depends on the dimensionless longitudinal rate aa^*. The Chapman-Enskog expansion of η\eta^* in powers of aa^* is seen to be only asymptotic (except in the case of Maxwell molecules). The velocity distribution function is also studied. At any value of aa^*, it exhibits an algebraic high-velocity tail that is responsible for the divergence of velocity moments. For sufficiently negative aa^*, moments of degree four and higher may diverge, while for positive aa^* the divergence occurs in moments of degree equal to or larger than eight.Comment: 18 pages (Revtex), including 5 figures (eps). Analysis of the heat flux plus other minor changes added. Revised version accepted for publication in PR

    Pulsed laser deposition growth of heteroepitaxial YBa2Cu3O7/La0.67Ca0.33MnO3 superlattices on NdGaO3 and Sr0.7La0.3Al0.65Ta0.35O3 substrates

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    Heteroepitaxial superlattices of [YBa2Cu3O7(n)/ La0.67Ca0.33MnO3(m)]x, where n and m are the number of YBCO and LCMO monolayers and x the number of bilayer repetitions, have been grown with pulsed laser deposition on NdGaO3 (110) and Sr0.7La0.3Al0.65Ta0.35O3 (LSAT) (001). These substrates are well lattice matched with YBCO and LCMO and, unlike the commonly used SrTiO3, they do not give rise to complex and uncontrolled strain effects due to structural transitions at low temperature. The growth dynamics and the structure have been studied in-situ with reflection high energy electron diffraction (RHEED) and ex-situ with scanning transmission electron microscopy (STEM), x-ray diffraction, and neutron reflectometry. The individual layers are found to be flat and continuous over long lateral distances with sharp and coherent interfaces and with a well-defined thickness of the individual layer. The only visible defects are antiphase boundaries in the YBCO layers that originate from perovskite unit cell height steps at the interfaces with the LCMO layers. We also find that the first YBCO monolayer at the interface with LCMO has an unusual growth dynamics and is lacking the CuO chain layer while the subsequent YBCO layers have the regular Y-123 structure. Accordingly, the CuO2 bilayers at both the LCMO/YBCO and the YBCO/LCMO interfaces are lacking one of their neighboring CuO chain layers and thus half of their hole doping reservoir. Nevertheless, from electric transport measurements on asuperlattice with n=2 we obtain evidence that the interfacial CuO2 bilayers remain conducting and even exhibit the onset of a superconducting transition at very low temperature. Finally, we show from dc magnetization and neutron reflectometry measurements that the LCMO layers are strongly ferromagnetic

    Evidence for spin-triplet superconducting correlations in metal-oxide heterostructures with non-collinear magnetization

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    Heterostructures composed of ferromagnetic La0.7Sr0.3MnO3, ferromagnetic SrRuO3, and superconducting YBa2Cu3Ox were studied experimentally. Structures of composition Au/La0.7Sr0.3MnO3/SrRuO3/YBa2Cu3Ox were prepared by pulsed laser deposition, and their high quality was confirmed by X-ray diffraction and reflectometry. A non-collinear magnetic state of the heterostructures was revealed by means of SQUID magnetometry and polarized neutron reflectometry. We have further observed superconducting currents in mesa-structures fabricated by deposition of a second superconducting Nb layer on top of the heterostructure, followed by patterning with photolithography and ion-beam etching. Josephson effects observed in these mesa-structures can be explained by the penetration of a triplet component of the superconducting order parameter into the magnetic layers.Comment: 10 pages, 6 figure

    Legendrian Distributions with Applications to Poincar\'e Series

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    Let XX be a compact Kahler manifold and LXL\to X a quantizing holomorphic Hermitian line bundle. To immersed Lagrangian submanifolds Λ\Lambda of XX satisfying a Bohr-Sommerfeld condition we associate sequences {Λ,k}k=1\{ |\Lambda, k\rangle \}_{k=1}^\infty, where k\forall k Λ,k|\Lambda, k\rangle is a holomorphic section of LkL^{\otimes k}. The terms in each sequence concentrate on Λ\Lambda, and a sequence itself has a symbol which is a half-form, σ\sigma, on Λ\Lambda. We prove estimates, as kk\to\infty, of the norm squares Λ,kΛ,k\langle \Lambda, k|\Lambda, k\rangle in terms of Λσσ\int_\Lambda \sigma\overline{\sigma}. More generally, we show that if Λ1\Lambda_1 and Λ2\Lambda_2 are two Bohr-Sommerfeld Lagrangian submanifolds intersecting cleanly, the inner products Λ1,kΛ2,k\langle\Lambda_1, k|\Lambda_2, k\rangle have an asymptotic expansion as kk\to\infty, the leading coefficient being an integral over the intersection Λ1Λ2\Lambda_1\cap\Lambda_2. Our construction is a quantization scheme of Bohr-Sommerfeld Lagrangian submanifolds of XX. We prove that the Poincar\'e series on hyperbolic surfaces are a particular case, and therefore obtain estimates of their norms and inner products.Comment: 41 pages, LaTe

    Remarks on the naturality of quantization

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    Hamiltonian quantization of an integral compact symplectic manifold M depends on a choice of compatible almost complex structure J. For open sets U in the set of compatible almost complex structures and small enough values of Planck's constant, the Hilbert spaces of the quantization form a bundle over U with a natural connection. In this paper we examine the dependence of the Hilbert spaces on the choice of J, by computing the semi-classical limit of the curvature of this connection. We also show that parallel transport provides a link between the action of the group Symp(M) of symplectomorphisms of M and the Schrodinger equation.Comment: 20 page

    Depth profile of the ferromagnetic order in a YBa2_2Cu3_3O7_7 / La2/3_{2/3}Ca1/3_{1/3}MnO3_3 superlattice on a LSAT substrate: a polarized neutron reflectometry study

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    Using polarized neutron reflectometry (PNR) we have investigated a YBa2Cu3O7(10nm)/La2/3Ca1/3MnO3(9nm)]10 (YBCO/LCMO) superlattice grown by pulsed laser deposition on a La0.3Sr0.7Al0.65Ta0.35O3 (LSAT) substrate. Due to the high structural quality of the superlattice and the substrate, the specular reflectivity signal extends with a high signal-to-background ratio beyond the fourth order superlattice Bragg peak. This allows us to obtain more detailed and reliable information about the magnetic depth profile than in previous PNR studies on similar superlattices that were partially impeded by problems related to the low temperature structural transitions of the SrTiO3 substrates. In agreement with the previous reports, our PNR data reveal a strong magnetic proximity effect showing that the depth profile of the magnetic potential differs significantly from the one of the nuclear potential that is given by the YBCO and LCMO layer thickness. We present fits of the PNR data using different simple block-like models for which either a ferromagnetic moment is induced on the YBCO side of the interfaces or the ferromagnetic order is suppressed on the LCMO side. We show that a good agreement with the PNR data and with the average magnetization as obtained from dc magnetization data can only be obtained with the latter model where a so-called depleted layer with a strongly suppressed ferromagnetic moment develops on the LCMO side of the interfaces. The models with an induced ferromagnetic moment on the YBCO side fail to reproduce the details of the higher order superlattice Bragg peaks and yield a wrong magnitude of the average magnetization. We also show that the PNR data are still consistent with the small, ferromagnetic Cu moment of 0.25muB that was previously identified with x-ray magnetic circular dichroism and x-ray resonant magnetic reflectometry measurements on the same superlattice.Comment: 11 pages, 7 figure

    Archaeological prospection with corona and wv-3 satellite imagery of the archaeological site of zar tepe (uzbekistan)

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    Abstract. The use of different data from satellite platforms for archaeological prospecting and remote sensing has been applied since the end of the 20th century. Although the current use of drones with different visible and multispectral sensors for small areas has partially replaced in some cases the use of this type of satellite information due to its higher spatial resolution. The historical importance of satellite imagery is essential to find out about and compare the transformations of the archaeological landscape of the last 60 years since the CORONA satellite program started in 1960. In this paper we propose the evaluation of a proposal for the automation of processes of two photographic reconnaissance correlative satellite programs CORONA (1960-1972), HEXAGON (1971-1986) declassified since 1995 and 2011 respectively, and the commercial satellite WorldView-3 (WV3) (2014) for use in the detection of buried archaeological structures at the archaeological site of Zar Tepe in the southeast of Uzbekistan. This is a site located in the Surkhan Darya region very little known between the first century BC and the fourth century AD. This methodology is part of the IPAEB project (International Pluridisciplinary Archaeological Expedition to Bactria) led by the University of Barcelona, the University of Salamanca and recently in 2019 the University of Zaragoza. IPAEB was started in 2006 in the South of Uzbekistan and is currently trying to explore the urban planning of the Zar Tepe archaeological site and the elements that make up its natural physical environment: evidence of communication routes, smallholdings, irrigation channels, fences and sources of raw materials

    Is There a Patient Profile That Characterizes a Patient With Adult Spinal Deformity as a Candidate for Minimally Invasive Surgery?

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    Study designRetrospective review.ObjectivesThe goal of this study was to evaluate the baseline characteristics of patients chosen to undergo traditional open versus minimally invasive surgery (MIS) for adult spinal deformity (ASD).MethodsA multicenter review of 2 databases including ASD patients treated with surgery. Inclusion criteria were age &gt;45 years, Cobb angle minimum of 20°, and minimum 2-year follow-up. Preoperative radiographic parameters and disability outcome measures were reviewed.ResultsA total of 350 patients were identified: 173 OPEN patients and 177 MIS. OPEN patients were significantly younger than MIS patients (61.5 years vs 63.74 years, P = .013). The OPEN group had significantly more females (87% vs 76%, P = .006), but both groups had similar body mass index. Preoperative lumbar Cobb was significantly higher for the OPEN group (34.2°) than for the MIS group (26.0°, P &lt; .001). The mean preoperative Oswestry Disability Index was significantly higher in the MIS group (44.8 in OPEN patients and 49.8 in MIS patients, P &lt; .011). The preoperative Numerical Rating Scale value for back pain was 7.2 in the OPEN group and 6.8 in the MIS group preoperatively, P = .100.ConclusionsPatients chosen for MIS for ASD are slightly older and have smaller coronal deformities than those chosen for open techniques, but they did not have a substantially lesser degree of sagittal malalignment. MIS surgery was most frequently utilized for patients with an sagittal vertical axis under 6 cm and a baseline pelvic incidence and lumbar lordosis mismatch under 30°
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