4,846 research outputs found

    Classification of pointed fusion categories of dimension p3p^3 up to weak Morita equivalence

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    We give a complete classification of pointed fusion categories over C\mathbb{C} of global dimension p3p^3 for pp any odd prime. We proceed to classify the equivalence classes of pointed fusion categories of dimension p3p^3 and we determine which of these equivalence classes have equivalent categories of modules

    Boundedness of Pseudodifferential Operators on Banach Function Spaces

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    We show that if the Hardy-Littlewood maximal operator is bounded on a separable Banach function space X(Rn)X(\mathbb{R}^n) and on its associate space Xâ€Č(Rn)X'(\mathbb{R}^n), then a pseudodifferential operator Op⁥(a)\operatorname{Op}(a) is bounded on X(Rn)X(\mathbb{R}^n) whenever the symbol aa belongs to the H\"ormander class Sρ,ÎŽn(ρ−1)S_{\rho,\delta}^{n(\rho-1)} with 0<ρ≀10<\rho\le 1, 0≀Ύ<10\le\delta<1 or to the the Miyachi class Sρ,ÎŽn(ρ−1)(Ï°,n)S_{\rho,\delta}^{n(\rho-1)}(\varkappa,n) with 0≀Ύ≀ρ≀10\le\delta\le\rho\le 1, 0≀Ύ00\le\delta0. This result is applied to the case of variable Lebesgue spaces Lp(⋅)(Rn)L^{p(\cdot)}(\mathbb{R}^n).Comment: To appear in a special volume of Operator Theory: Advances and Applications dedicated to Ant\'onio Ferreira dos Santo

    Logarithmic bump conditions for CalderĂłn-Zygmund operators on spaces of homogeneous type

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    We establish two-weight norm inequalities for singular integral operators defined on spaces of homogeneous type. We do so first when the weights satisfy a double bump condition and then when the weights satisfy separated logarithmic bump conditions. Our results generalize recent work on the Euclidean case, but our proofs are simpler even in this setting. The other interesting feature of our approach is that we are able to prove the separated bump results (which always imply the corresponding double bump results) as a consequence of the double bump theorem

    Reconstitution of T cell receptor signaling in ZAP-70-deficient cells by retroviral transduction of the ZAP-70 gene.

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    A variant of severe combined immunodeficiency syndrome (SCID) with a selective inability to produce CD8 single positive T cells and a signal transduction defect in peripheral CD4+ cells has recently been shown to be the result of mutations in the ZAP-70 gene. T cell receptor (TCR) signaling requires the association of the ZAP-70 protein tyrosine kinase with the TCR complex. Human T cell leukemia virus type I-transformed CD4+ T cell lines were established from ZAP-70-deficient patients and normal controls. ZAP-70 was expressed and appropriately phosphorylated in normal T cell lines after TCR engagement, but was not detected in T cell lines from ZAP-70-deficient patients. To determine whether signaling could be reconstituted, wild-type ZAP-70 was introduced into deficient cells with a ZAP-70 retroviral vector. High titer producer clones expressing ZAP-70 were generated in the Gibbon ape leukemia virus packaging line PG13. After transduction, ZAP-70 was detected at levels equivalent to those observed in normal cells, and was appropriately phosphorylated on tyrosine after receptor engagement. The kinase activity of ZAP-70 in the reconstituted cells was also appropriately upregulated by receptor aggregation. Moreover, normal and transduced cells, but not ZAP-70-deficient cells, were able to mobilize calcium after receptor ligation, indicating that proximal TCR signaling was reconstituted. These results indicate that this form of SCID may be corrected by gene therapy

    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

    A novel micro optical probe for early diagnosis of upper gastrointestinal (GI) cancers

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    In this paper, we present the development of a new micro fiber optical sensor probe with side viewing capability for early diagnosis of cancers in upper gastrointestinal tract. The probe consists of a oblique incidence source and a collection array of microfabricated curved SU-8 waveguides for collecting spatially resolved diffuse reflectance from tissue surface. The probe has been used to measure ex-vivo esophagus specimens to differentiate cancerous tissues from benign ones

    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

    Micromachined “side-viewing” optical sensor probe for detection of esophageal cancers

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    In this paper, we report the design, fabrication and testing of a new miniaturized optical sensor probe with “side viewing” capability for oblique incidence diffuse reflectance spectrometry. The sensor probe consists of a lithographically patterned polymer waveguides chip and two micromachined positioning substrates and source/collection fibers to achieve 45° light incidence and collection of spatially resolved diffuse reflectance. Diffuse reflectance of human esophageal surface has been successfully measured for differentiation of cancerous tissues from normal ones
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