5,451 research outputs found

    Fatigue testing of low-cost fiberglass composite wind turbine blade materials

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    The static and fatigue behavior of transverse filament tape (TFT) fiberglass/epoxy and TFT/polyester composites was established by the testing of specimens cut from panels fabricated by a filament winding process used for the construction of large experimental wind turbine blades

    Displacement energy of unit disk cotangent bundles

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    We give an upper bound of a Hamiltonian displacement energy of a unit disk cotangent bundle DMD^*M in a cotangent bundle TMT^*M, when the base manifold MM is an open Riemannian manifold. Our main result is that the displacement energy is not greater than Cr(M)C r(M), where r(M)r(M) is the inner radius of MM, and CC is a dimensional constant. As an immediate application, we study symplectic embedding problems of unit disk cotangent bundles. Moreover, combined with results in symplectic geometry, our main result shows the existence of short periodic billiard trajectories and short geodesic loops.Comment: Title slightly changed. Close to the version published online in Math Zei

    New obstructions to symplectic embeddings

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    In this paper we establish new restrictions on symplectic embeddings of certain convex domains into symplectic vector spaces. These restrictions are stronger than those implied by the Ekeland-Hofer capacities. By refining an embedding technique due to Guth, we also show that they are sharp.Comment: 80 pages, 3 figures, v2: improved exposition and minor corrections, v3: Final version, expanded and improved exposition and minor corrections. The final publication is available at link.springer.co

    Algebraic Torsion in Contact Manifolds

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    We extract a nonnegative integer-valued invariant, which we call the "order of algebraic torsion", from the Symplectic Field Theory of a closed contact manifold, and show that its finiteness gives obstructions to the existence of symplectic fillings and exact symplectic cobordisms. A contact manifold has algebraic torsion of order zero if and only if it is algebraically overtwisted (i.e. has trivial contact homology), and any contact 3-manifold with positive Giroux torsion has algebraic torsion of order one (though the converse is not true). We also construct examples for each nonnegative k of contact 3-manifolds that have algebraic torsion of order k but not k - 1, and derive consequences for contact surgeries on such manifolds. The appendix by Michael Hutchings gives an alternative proof of our cobordism obstructions in dimension three using a refinement of the contact invariant in Embedded Contact Homology.Comment: 53 pages, 4 figures, with an appendix by Michael Hutchings; v.3 is a final update to agree with the published paper, and also corrects a minor error that appeared in the published version of the appendi

    Enhanced heparan sulfate proteoglycan-mediated uptake of cell-penetrating peptide-modified liposomes

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    Protein transduction domains (PTDs) are used to enhance cellular uptake of drugs, proteins, polynucleotides or liposomes. In this study, functionalized Antennapedia (Antp, aa 43--58) and HIV Tat (aa 47-57) peptides were coupled to small unilamellar liposomes via thiol-maleimide linkage. Modified liposomes showed higher uptake into a panel of cell lines including tumor and dendritic cells than unmodified control liposomes. Liposome uptake was time and concentration dependent as analyzed by flow cytometry and live-cell microscopy. At least 100 PTD molecules per small unilamellar liposome (100 ± 30 nm) were necessary for efficient translocation into cells. Cellular uptake of PTD-modified liposomes was 15- to 25-fold increased compared to unmodified liposomes and was inhibited by preincubation of liposomes with heparin. Glycosaminoglycan-deficient CHO cells showed dramatically reduced cell association of PTD-modified liposomes, confirming the important role of heparan sulfate proteoglycans in PTD-mediated uptake. Antp-liposomes used as carriers of the cytotoxic drug N4-octadecyl-1-β-D-arabinofuranosylcytosine-(5′- 5′)-3′-C-ethinylcytidine showed a reduction of the IC50 by 70% on B16F1 melanoma cells compared with unmodified liposomes. PTD-functionalized liposomes, particularly Antp-liposomes, represent an interesting novel carrier system for enhanced cell-specific delivery of a large variety of liposome-entrapped molecule

    An exact sequence for contact- and symplectic homology

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    A symplectic manifold WW with contact type boundary M=WM = \partial W induces a linearization of the contact homology of MM with corresponding linearized contact homology HC(M)HC(M). We establish a Gysin-type exact sequence in which the symplectic homology SH(W)SH(W) of WW maps to HC(M)HC(M), which in turn maps to HC(M)HC(M), by a map of degree -2, which then maps to SH(W)SH(W). Furthermore, we give a description of the degree -2 map in terms of rational holomorphic curves with constrained asymptotic markers, in the symplectization of MM.Comment: Final version. Changes for v2: Proof of main theorem supplemented with detailed discussion of continuation maps. Description of degree -2 map rewritten with emphasis on asymptotic markers. Sec. 5.2 rewritten with emphasis on 0-dim. moduli spaces. Transversality discussion reorganized for clarity (now Remark 9). Various other minor modification

    Studies of Electron-Beam Penetration and Free-Carrier Generation in Diamond Films

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    Experimental observations of the energy‐dependent electron‐beam penetration in type II‐A natural diamond are reported. The experimental data are compared with results obtained from numerical Monte Carlo simulations, and the results are in very good agreement. The results also reveal that a threshold energy of about 125 keV is necessary for complete penetration for a 35 μm sample. It is found that over the 30–180 keV range, the energy dependence of the penetration depth and total path length exhibits a power‐law relation. Monte Carlo simulations have also been performed to investigate the excess carrier‐generation profiles within diamond for a set of incident e‐beam energy distributions. The simulation results demonstrate the feasibility of tailoring the internal source function, and hence influencing the diffusion currents, the internal electric fields, and charge injection through the contacts

    Rapidly Evolving Giant Dermatofibroma

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    Dermatofibroma, also known as “fibrous histiocytoma”, is a benign dermal or subcutaneous poorly circumscribed proliferation of spindle-shaped fibroblasts and macrophages in the dermis. Although it is commonly present as a brownish nodule the legs of females, it may also arise on the upper extremities, trunk, and rarely on the head. The exact pathogenesis is unclear. However, it is widely believed that the originating insult to the dermis is a folliculitis, an arthropod bite, or an unspecified initial inflammatory condition. Giant dermatofibromas of greater than 5 cm in diameter are rare, with only 22 cases reported in the literature. We present a case of a rapidly evolving pedunculated mass in the groin of a male patient. Histological examination confirmed this to be a giant dermatofibroma. Though this specimen cannot is not confirmed as such, the cellular subtype is sometimes present as a larger lesion with anecdotal reports of local recurrence and distant metastases. The clinical and radiological features which were somewhat suspicious of malignancy are considered in the context of the definitive pathological diagnosis of a benign lesion

    Clinical evaluation of the FloTrac/VigileoTM system and two established continuous cardiac output monitoring devices in patients undergoing cardiac surgery†‡

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    Background Assessment of cardiac output (CO) by the FloTrac/Vigileo™ system may offer a less invasive means of determining the CO than either the pulmonary artery catheter (PAC) or the PiCCOplus™ system. The aim of this study was to compare CO measurements made using the FloTrac/Vigileo™ system with upgraded software (FCO, Edwards Lifesciences, Irvine CA, USA), the PiCCOplus™ system (PCO, Pulsion Medical Systems, Munich, Germany) and continuous CO monitoring using a PAC (CCO; Vigilance™ monitoring, Edwards Lifesciences, Irvine CA, USA) with intermittent pulmonary artery thermodilution (ICO). The study was conducted in patients undergoing elective cardiac surgery. Methods Thirty-one patients with preserved left ventricular function were enrolled. CCO, FCO, and PCO were recorded in the perioperative period at six predefined time points after achieving stable haemodynamic conditions; ICO was determined from the mean of three bolus injections. Bland-Altman analysis was used to compare CCO, FCO, and PCO with ICO. Results Bland-Altman analysis revealed a comparable mean bias and limits of agreement for all tested continuous CO monitoring devices using ICO as reference method. Agreement for all devices decreased in the postoperative period. Conclusion The performance of the FloTrac/Vigileo™ system, the PiCCOplus™, and the Vigilance™ CCO monitoring for CO measurement were comparable when tested against intermittent thermodilution in patients undergoing elective cardiac surger
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