1,253 research outputs found

    Development of Channeled Nanofibrous Scaffolds for Oriented Tissue Engineering

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    A tissue‐engineering scaffold resembling the structure of the natural extracellular matrix can often facilitate tissue regeneration. Nerve and tendon are oriented micro‐scale tissue bundles. In this study, a method combining injection molding and thermally induced phase separation techniques is developed to create single‐ and multiple‐channeled nanofibrous poly( L ‐lactic acid) scaffolds. The overall shape, the number and spatial arrangement of channels, the channel wall matrix architecture, the porosity and mechanical properties of the scaffolds are all tunable. The porous NF channel wall matrix provides an excellent microenvironment for protein adsorption and the attachment of PC12 neuronal cells and tendon fibroblast cells, showing potential for neural and tendon tissue regeneration. A method combining injection molding and thermally induced phase separation is developed to create single‐ and multiple‐channeled nanofibrous polymer scaffolds. The porous nanofibrous channel wall provides an excellent microenvironment for protein adsorption and cell attachment, showing potential for nerve and tendon regeneration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92054/1/761_ftp.pd

    Mathematical and numerical analysis for PDE systems modeling intravascular drug release from arterial stents and transport in arterial tissue

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    This paper is concerned with the PDE and numerical analysis of a modified one-dimensional intravascular stent model originally proposed in [4]. It is proved that the modified model has a unique weak solution using the Galerkin method combined with a compactness argument. A semi-discrete finite element method and a fully discrete scheme using the Euler time-stepping are formulated for the PDE model. Optimal order error estimates in the energy norm are proved for both schemes. Numerical results are presented along with comparisons between different decoupling strategies and time-stepping schemes. Lastly, extensions of the model and its PDE and numerical analysis results to the two-dimensional case are also briefly discussed.Comment: 21 page

    Txilm: Lossy Block Compression with Salted Short Hashing

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    Current blockchains are restricted by the low throughput. Aimed at this problem, we propose Txilm, a protocol that compresses the size of transaction presentation in each block to save the bandwidth of the network. In this protocol, a block carries short hashes of TXIDs instead of complete transactions. Combined with the sorted transactions based on TXIDs, Txilm realizes 80 times of data size reduction compared with the original blockchains. We also evaluate the probability of hash collisions, and provide methods of resolving such collisions. Finally, we design strategies to protect against potential attacks on Txilm.Comment: 5 pages and 2 figure

    Finite-Time Chaos Control of a Complex Permanent Magnet Synchronous Motor System

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    This paper investigates the finite-time chaos control of a permanent magnet synchronous motor system with complex variables. Based on the finite-time stability theory, two control strategies are proposed to realize stabilization of the complex permanent magnet synchronous motor system in a finite time. Two numerical simulations have been conducted to demonstrate the validity and feasibility of the theoretical analysis

    Hopf Bifurcation Analysis for the van der Pol Equation with Discrete and Distributed Delays

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    We consider the van der Pol equation with discrete and distributed delays. Linear stability of this equation is investigated by analyzing the transcendental characteristic equation of its linearized equation. It is found that this equation undergoes a sequence of Hopf bifurcations by choosing the discrete time delay as a bifurcation parameter. In addition, the properties of Hopf bifurcation were analyzed in detail by applying the center manifold theorem and the normal form theory. Finally, some numerical simulations are performed to illustrate and verify the theoretical analysis

    Nanofibrous Spongy Microspheres for the Delivery of Hypoxia-primed Human Dental Pulp Stem Cells to Regenerate Vascularized Dental Pulp

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    Dental pulp infection and necrosis are widespread diseases. Conventional endodontic treatments result in a devitalized and weakened tooth. In this work, we synthesized novel star-shaped polymer to self-assemble into unique nanofibrous spongy microspheres (NF-SMS), which were used to carry human dental pulp stem cells (hDPSCs) into the pulp cavity to regenerate living dental pulp tissues. It was found that NF-SMS significantly enhanced hDPSCs attachment, proliferation, odontogenic differentiation and angiogenesis, as compared to control cell carriers. Additionally, NF-SMS promoted vascular endothelial growth factor (VEGF) expression of hDPSCs in a 3D hypoxic culture. Hypoxia-primed hDPSCs/NF-SMS complexes were injected into the cleaned pulp cavities of rabbit molars for subcutaneous implantation in mice. After 4 weeks, the hypoxia group significantly enhanced angiogenesis inside the pulp chamber and promoted the formation of ondontoblast-like cells lining along the dentin-pulp interface, as compared to the control groups (hDPSCs alone group, NF-SMS alone group, and hDPSCs/NF-SMS group pre-cultured under normoxic conditions). Furthermore, in an in situ dental pulp repair model in rats, hypoxia-primed hDPSCs/NF-SMS were injected to fully fill the pulp cavity and regenerate pulp-like tissues with a rich vasculature and a histological structure similar to the native pulp

    Deep Residual Text Detection Network for Scene Text

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    Scene text detection is a challenging problem in computer vision. In this paper, we propose a novel text detection network based on prevalent object detection frameworks. In order to obtain stronger semantic feature, we adopt ResNet as feature extraction layers and exploit multi-level feature by combining hierarchical convolutional networks. A vertical proposal mechanism is utilized to avoid proposal classification, while regression layer remains working to improve localization accuracy. Our approach evaluated on ICDAR2013 dataset achieves F-measure of 0.91, which outperforms previous state-of-the-art results in scene text detection.Comment: IAPR International Conference on Document Analysis and Recognition (ICDAR) 201
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