128 research outputs found

    On the illumination of a class of convex bodies

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    We study Boltyanski’s illumination problem (or Hadwiger's covering problem) for the class of convex bodies in Rn\mathbb{R}^n consisting of convex hulls of a pair of compact convex sets contained in two parallel hyperplanes of Rn\mathbb{R}^n. This special case of the problem is completely solved when n=3n=3

    Co-Attention Hierarchical Network: Generating Coherent Long Distractors for Reading Comprehension

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    In reading comprehension, generating sentence-level distractors is a significant task, which requires a deep understanding of the article and question. The traditional entity-centered methods can only generate word-level or phrase-level distractors. Although recently proposed neural-based methods like sequence-to-sequence (Seq2Seq) model show great potential in generating creative text, the previous neural methods for distractor generation ignore two important aspects. First, they didn't model the interactions between the article and question, making the generated distractors tend to be too general or not relevant to question context. Second, they didn't emphasize the relationship between the distractor and article, making the generated distractors not semantically relevant to the article and thus fail to form a set of meaningful options. To solve the first problem, we propose a co-attention enhanced hierarchical architecture to better capture the interactions between the article and question, thus guide the decoder to generate more coherent distractors. To alleviate the second problem, we add an additional semantic similarity loss to push the generated distractors more relevant to the article. Experimental results show that our model outperforms several strong baselines on automatic metrics, achieving state-of-the-art performance. Further human evaluation indicates that our generated distractors are more coherent and more educative compared with those distractors generated by baselines.Comment: 8 pages, 3 figures. Accepted by AAAI202

    A Coumarin–Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide

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    In this study, we synthesized a coumarin–hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol−1·cm−1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN−). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN−) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN−). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN− over the concentration range of 1–9 μM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 μM. Using UV-Vis spectrophotometry, the linear detection range for CN− was found to be 1–27 μM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 μM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN− by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively

    Thermodynamic and kinetic analysis of the melt spinning process of Fe-6.5 wt.% Si alloy

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    The microstructural evolution of Fe-6.5 wt.% Si alloy during rapid solidification was studied over a quenching rate of 4 × 104 K/s to 8 × 105 K/s. The solidification and solid-state diffusional transformation processes during rapid cooling were analyzed via thermodynamic and kinetic calculations. The Allen-Cahn theory was adapted to model the experimentally measured bcc_B2 antiphase domain sizes under different cooling rates. The model was calibrated based on the experimentally determined bcc_B2 antiphase domain sizes for different wheel speeds and the resulting cooling rates. Good correspondence of the theoretical and experimental data was obtained over the entire experimental range of cooling rates. Along with the asymptotic domain size value at the infinite cooling rates, the developed model represents a reliable extrapolation for the cooling rate \u3e 106 K/s and allows one to optimize the quenching process

    Allele-specific induction of IL-1beta expression by C/EBPbeta and PU.1 contributes to increased tuberculosis susceptibility

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    Mycobacterium tuberculosis infection is associated with a spectrum of clinical outcomes, from long-term latent infection to different manifestations of progressive disease. Pro-inflammatory pathways, such as those controlled by IL-1beta, have the contrasting potential both to prevent disease by restricting bacterial replication, and to promote disease by inflicting tissue damage. Thus, the ultimate contribution of individual inflammatory pathways to the outcome of M. tuberculosis infection remains ambiguous. In this study, we identified a naturally-occurring polymorphism in the human IL1B promoter region, which alters the association of the C/EBPbeta and PU.1 transcription factors and controls Mtb-induced IL-1beta production. The high-IL-1beta expressing genotype was associated with the development of active tuberculosis, the severity of pulmonary disease and poor treatment outcome in TB patients. Higher IL-1beta expression did not suppress the activity of IFN-gamma-producing T cells, but instead correlated with neutrophil accumulation in the lung. These observations support a specific role for IL-1beta and granulocytic inflammation as a driver of TB disease progression in humans, and suggest novel strategies for the prevention and treatment of tuberculosis

    Bone Marrow-Derived Microglia-Based Neurturin Delivery Protects Against Dopaminergic Neurodegeneration in a Mouse Model of Parkinson\u27s Disease

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    Although neurotrophic factors have long been recognized as potent agents for protecting against neuronal degeneration, clinical success in treating Parkinson\u27s disease and other neurodegenerative disorders has been hindered by difficulties in delivery of trophic factors across the blood brain barrier (BBB). Bone marrow hematopoietic stem cell-based gene therapy is emerging as a promising tool for overcoming drug delivery problems, as myeloid cells can cross the BBB and are recruited in large numbers to sites of neurodegeneration, where they become activated microglia that can secrete trophic factors. We tested the efficacy of bone marrow-derived microglial delivery of neurturin (NTN) in protecting dopaminergic neurons against neurotoxin-induced death in mice. Bone marrow cells were transduced ex vivo with lentivirus expressing the NTN gene driven by a synthetic macrophage-specific promoter. Infected bone marrow cells were then collected and transplanted into recipient animals. Eight weeks after transplantation, the mice were injected with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropuridine (MPTP) for seven days to induce dopaminergic neurodegeneration. Microglia-mediated NTN delivery dramatically ameliorated MPTP-induced degeneration of tyrosine hydroxylase (TH)-positive neurons of the substantia nigra and their terminals in the striatum. Microglia-mediated NTN delivery also induced significant recovery of synaptic marker staining in the striatum of MPTP-treated animals. Functionally, NTN treatment restored MPTP-induced decline in general activity, rearing behavior, and food intake. Thus, bone marrow-derived microglia can serve as cellular vehicles for sustained delivery of neurotrophic factors capable of mitigating dopaminergic injury

    Case report: Application of morphology in the diagnosis of siderosis in a patient with tuberculosis infection

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    A 49-year-old male who had been working in welding for more than 30 years was admitted to the hospital for a medical checkup that revealed a lung shadow without specific symptoms such as coughing and sputum. Imaging studies showed diffuse ground-glass changes in both lungs, wall cavities with wall nodules, multiple peripheral nodules, and some nodules with calcification. The patient has been engaged in welding work for more than 30 years and exposed to iron dust. Lung tissue biopsy, routine morphological and pathological fluid basis examination of alveolar lavage fluid, can be considered as pulmonary iron particles, which can be regarded as iron dust lung. Acid-fast bacilli were detected in both fibrobronchoscopic brush extract and alveolar lavage fluid acid-fast staining. As the pathological examination revealed granulomatous inflammation showed caseation necrosis, the patient was judged to have concomitant pulmonary TB. After the diagnosis was made, the patient was no longer exposed to dust and was treated with appropriate anti- tuberculosis (TB) therapy. Lung lesions caused by welding have been reported, but the simultaneous finding of siderosis with pulmonary TB is specific to the case presented here. By describing the imaging features, combining different staining methods of alveolar lavage fluid and pathological examination of lung tissue, we showed various morphological manifestations of this case, aiming at improving the morphological diagnosis level of laboratory physicians and enabling patients to be diagnosed and treated early
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