227 research outputs found

    On the essential spectrum of complete non-compact manifolds

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    In this paper, we prove that the LpL^p essential spectra of the Laplacian on functions are [0,+∞)[0,+\infty) on a non-compact complete Riemannian manifold with non-negative Ricci curvature at infinity. The similar method applies to gradient shrinking Ricci soliton, which is similar to non-compact manifold with non-negative Ricci curvature in many ways.Comment: Minor modification

    ShaDDR: Real-Time Example-Based Geometry and Texture Generation via 3D Shape Detailization and Differentiable Rendering

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    We present ShaDDR, an example-based deep generative neural network which produces a high-resolution textured 3D shape through geometry detailization and conditional texture generation applied to an input coarse voxel shape. Trained on a small set of detailed and textured exemplar shapes, our method learns to detailize the geometry via multi-resolution voxel upsampling and generate textures on voxel surfaces via differentiable rendering against exemplar texture images from a few views. The generation is real-time, taking less than 1 second to produce a 3D model with voxel resolutions up to 512^3. The generated shape preserves the overall structure of the input coarse voxel model, while the style of the generated geometric details and textures can be manipulated through learned latent codes. In the experiments, we show that our method can generate higher-resolution shapes with plausible and improved geometric details and clean textures compared to prior works. Furthermore, we showcase the ability of our method to learn geometric details and textures from shapes reconstructed from real-world photos. In addition, we have developed an interactive modeling application to demonstrate the generalizability of our method to various user inputs and the controllability it offers, allowing users to interactively sculpt a coarse voxel shape to define the overall structure of the detailized 3D shape

    Gadolinium Enhancement May Indicate a Condition at Risk of Developing Necrosis in Marchiafava–Bignami Disease: A Case Report and Literature Review

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    Marchiafava–Bignami disease (MBD) is a rare condition characterized by demyelination, necrosis and atrophy of the corpus callosum (CC), and mainly associated with alcoholism. MBD may present with various clinical manifestations. Brain magnetic resonance imaging (MRI) scan is important in prompt diagnosis and treatment of MBD. Here we reported a case of MBD and reviewed literature about the usage of gadolinium-enhanced MRI in MBD. Gadolinium enhancement may indicate a condition at risk of developing necrosis. We therefore recommend a contrast-enhanced MRI study in severe alcoholics with suspected diagnosis of MBD

    PACT/RAX Regulates the Migration of Cerebellar Granule Neurons in the Developing Cerebellum

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    PACT and its murine ortholog RAX were originally identified as a protein activator for the dsRNA-dependent, interferon-inducible protein kinase PKR. Recent studies indicated that RAX played a role in embryogenesis and neuronal development. In this study, we investigated the expression of RAX during the postnatal development of the mouse cerebellum and its role in the migration of cerebellar granule neurons (CGNs). High expression of RAX was observed in the cerebellum from postnatal day (PD) 4 to PD9, a period when the CGNs migrate from the external granule layer (EGL) to the internal granule layer (IGL). The migration of the EGL progenitor cells in vivo was inhibited by RAX knockdown on PD4. This finding was confirmed by in vitro studies showing that RAX knockdown impaired the migration of CGNs in cerebellar microexplants. PACT/RAX-regulated migration required its third motif and was independent of PKR. PACT/RAX interacted with focal adhesion kinase (FAK) and PACT/RAX knockdown disturbed the FAK phosphorylation in CGNs. These findings demonstrated a novel function of PACT/RAX in the regulation of neuronal migration

    High nitrate accumulation in the Vadose Zone after land-use change from croplands to orchards

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    Additional evidence indicates that the nitrate stored in the deep soil profile has an important role in regulating the global nitrogen (N) cycle. This study assessed the effects of land-use changes from croplands to intensive orchards (LUCO) on N surplus, nitrate accumulation in deep soil, and groundwater quality in the kiwifruit belt of the northern slope region of the Qinling Mountains, China. LUCO resulted in comparatively high N surplus in orchards (282 vs 1206 kg ha–1 yr–1, respectively). The average nitrate accumulation within the 0–10 m profiles of orchards was 7113 kg N ha–1, which was equal to approximately the total N surplus of 6 years of the orchards. The total nitrate stock within 0–10 m soil profiles of the kiwifruit belt was 266.5 Gg N, which was 3.5 times higher than the total annual N input. The nitrate concentrations of 97% of groundwater samples exceeded the WHO standard. The LUCO resulted in large nitrate storage in the vadose zone and caused serious contamination of groundwater. Our study highlights that nitrate accumulation in the vadose zone of an intensive land-use system is one of the main fates of surplus N and also a hotspot of nitrate accumulation

    Interferometric Radar for Activity Recognition and Benchmarking in Different Radar Geometries

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    Radar micro-Doppler signatures have been proposed for human activity classification for surveillance and ambient assisted living in healthcare-related applications. A known issue is the performance reduction when the target is moving tangentially to the line-of-sight of the radar. Multiple techniques have been proposed to address this, such as multistatic radar and to some extent, interferometric radar. A simulator is presented to generate synthetic data representative of 8 different radar systems (including configurations as monostatic, multistatic, and interferometric) to quantify classification performances as a function of aspect angles and deployment geometries. This simulator allows an unbiased performance evaluation of the different radar systems. 6 human activities are considered with signatures originating from motion-captured data of 14 different subjects. The results show that interferometric radar data with fusion outperforms the other methods with over 97.6% accuracy consistently across all aspect angles, as well as the potential for simplified indoor deployment

    Application of CRISPR-Cas system in the diagnosis and therapy of ESKAPE infections

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    Antimicrobial-resistant ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens represent a global threat to human health. ESKAPE pathogens are the most common opportunistic pathogens in nosocomial infections, and a considerable number of their clinical isolates are not susceptible to conventional antimicrobial therapy. Therefore, innovative therapeutic strategies that can effectively deal with ESKAPE pathogens will bring huge social and economic benefits and ease the suffering of tens of thousands of patients. Among these strategies, CRISPR (clustered regularly interspaced short palindromic repeats) system has received extra attention due to its high specificity. Regrettably, there is currently no direct CRISPR-system-based anti-infective treatment. This paper reviews the applications of CRISPR-Cas system in the study of ESKAPE pathogens, aiming to provide directions for the research of ideal new drugs and provide a reference for solving a series of problems caused by multidrug-resistant bacteria (MDR) in the post-antibiotic era. However, most research is still far from clinical application

    New aneurysm formation after endovascular embolization of a vertebral epidural AV fistula: a rare sequelae of NF AV fistulae

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    BackgroundNeurofibromatosis type 1 (NF-1) is a dominant genetic disorder often accompanied by lesions of the neurovascular system. Patients with NF-1 are predisposed to unique vertebral artery fistula (AVF).Case descriptionWe report on a rare case of multiple neurovascular abnormalities in a 47-year-old man with neurofibromatosis. He was admitted due to a sudden headache and was found to have suffered a subarachnoid hemorrhage from a left vertebral arteriovenous fistula. He underwent two endovascular procedures complicated by a delayed extraspinal mass 7 days after treatment. Angiography revealed a new vascular abnormality, and although we performed another embolization, it failed to respond to further embolization.ConclusionVascular abnormalities in patients with NF-1 can be complex. Endovascular intervention remains feasible for NF-1 related AVF, however, partial occlusion of the fistula should be avoided to limit and iatrogenic damage to the blood vessels
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