164 research outputs found

    A conclusive theorem on Finsler metrics of sectional flag curvature

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    If the flag curvature of a Finsler manifold reduces to sectional curvature, then locally either the Finsler metric is Riemannian, or the flag curvature is isotropic.Comment: 6 page

    Affine vector fields on Finsle manifolds

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    We give characterizations of affine transformations and affine vector fields in terms of the spray. By utilizing the Jacobi type equation that characterizes affine vector fields, we prove some rigidity theorems of affine vector fields on compact or forward complete non-compact Finsler manifolds with non-positive total Ricci curvature.Comment: 9 page

    ON THE CONSTRUCTION OF DUALLY FLAT FINSLER METRICS

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    In this paper, we give a new approach to find a dually flat Finsler metric. As its application, we produce many new spherically symmetric dually flat Fins ler metrics by using known projective spherically symmetric Fins ler metrics.National Natural Science Foundation of China [11371032, 11301283]; Doctoral Program of Higher Education of China [20110001110069]SCI(E)[email protected]; [email protected]; [email protected]

    Sharp uncertainty principles on general Finsler manifolds

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    The paper is devoted to sharp uncertainty principles (Heisenberg-Pauli-Weyl, Caffarelli-Kohn-Nirenberg and Hardy inequalities) on forward complete Finsler manifolds endowed with an arbitrary measure. Under mild assumptions, the existence of extremals corresponding to the sharp constants in the Heisenberg-Pauli-Weyl and Caffarelli-Kohn-Nirenberg inequalities fully \textit{characterizes} the nature of the Finsler manifold in terms of three non-Riemannian quantities, namely, its \textit{reversibility} and the vanishing of the \textit{flag curvature} and SS\textit{-curvature} induced by the measure, respectively. It turns out in particular that the Busemann-Hausdorff measure is the optimal one in the study of sharp uncertainty principles on Finsler manifolds. The optimality of our results are supported by Randers-type Finslerian examples originating from the Zermelo navigation problem

    DFN modelling constrained by multiple seismic attributes using the steering pyramid technology

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    Fracture modelling is essential for understanding fluid flow in fractured hydrocarbon reservoirs, particularly in the phase of production; however, traditional discrete fracture network (DFN) modelling methods lack constraints that reflect characteristics of fracture development. Fractures or fracture networks exhibit a high degree of randomness; as such, it is difficult to model fracture characteristics. This paper proposes a new approach for DFN modelling constrained by seismic attributes. Firstly, the steerable pyramid method is adopted to improve seismic data resolution; secondly, multiple seismic attributes are extracted and combined into a composite attribute to characterize fracture spatial distribution; finally, a DFN modelling method is established by using the composite attribute as a location constraint. To verify the effectiveness of the approach, a case study is conducted in the Bonan Depression, in East China. The results show that, compared with the traditional DFN modelling methods, the DFN modelling with the location constraint create a more realistic fracture model which accurately reflects fracture distribution characteristics. The application demonstrates the potential of wide application prospects in fractured reservoirs

    Quercus texana ‘Jin Fen Shi Jia’: A New Colored Landscape Tree

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    Quercus L. is an important tree of the family Fagaceae, and widely distributed in Asia, Africa, Europe, and the Americas (Jiang et al. 2019). There are ∼500 species, which can be generally divided into two subgenera and eight sections (Chassé 2018). The section Lobatae is naturally distributed in North America, Central America, and Colombia in South America. There are reports of breeding horticultural cultivars from tree species of this section in Europe and the United States. These cultivars include different leaf colors and tree shapes, such as Quercus coccinea ‘Splendens’, Quercus palustris Pacific Brilliance™ ‘PWJR08’ (bright red leaves in autumn), Quercus texana ‘New Madrid’ (red leaves in spring), Quercus rubra ‘Aurea’ (yellow leaves in spring), Q. texana Highpoint® ‘QNFTA’, Q. palustris Green Pillar® ‘Pringreen’ and Quercus phellos Hightower® ‘QPSTA’ (have narrow crown and are densely branched), and Q. palustris ‘Green Dwarf’ (low tree-shape) (Iqbal et al. 2017; Lancaster 1977; Russell et al. 2021; Torres-Miranda et al. 2011). Q. texana, also known as Nuttall’s oak, is a medium-sized deciduous tree with rapid growth, strong adaptability, and high ornamental value (Costello et al. 2011). It belongs to the section Lobatae, which are native to the Mississippi River Basin in the southeastern United States (Barrón et al. 2017; Manos et al. 1999; Sargent 1918). The trunk of Q. texana is upright with a tower-shaped crown. The leaves of Q. texana are simple, with lobed and toothed margins, broad and rounded lobes, and leaf length of 10 to 15 cm. The leaves are green and give dense shade in summer, and then turn bright red or reddish-brown in autumn; the leaves remain until late in the year on the twigs. Q. texana is commonly used for landscaping purposes and timber production, fuel wood, firewood, and charcoal. The species is known for its straight grain, resistance to fungal decay, and overall durability, making it a desirable species for industrial applications such as flooring, paneling, and furniture (Wang et al. 2022). This species is often chosen for landscape applications because of its adaptable nature, rapid growth rate, and beautiful foliage. In recent years, researchers have been working to produce improved cultivars of Q. texana, and various new cultivars have been created with enhanced characteristics such as greater biotic and abiotic resistance, improved growth rate, and desirable foliage shapes and colors. In China, some institutes have conducted systematic research since the 1990s on the introduction and cultivation of Q. texana. After screening, we selected some cultivars and provenances with good growth and strong adaptability (Chen et al. 2013). Now there are five cultivars of Q. texana authorized by the National Forestry and Grassland Administration (China): cultivars Yan Yu (red leaves in autumn), Long Xiang No. 7 and Long Xiang No. 10 (yellow leaves in spring), and Long Xiang No. 3 and Long Xiang No. 8 (red leaves in spring). The new cultivars possess excellent ornamental features and provide more options in landscape applications

    Uncovering the Functional Link Between SHANK3 Deletions and Deficiency in Neurodevelopment Using iPSC-Derived Human Neurons

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    SHANK3 mutations, including de novo deletions, have been associated with autism spectrum disorders (ASD). However, the effects of SHANK3 loss of function on neurodevelopment remain poorly understood. Here we generated human induced pluripotent stem cells (iPSC) in vitro, followed by neuro-differentiation and lentivirus-mediated shRNA expression to evaluate how SHANK3 knockdown affects the in vitro neurodevelopmental process at multiple time points (up to 4 weeks). We found that SHANK3 knockdown impaired both early stage of neuronal development and mature neuronal function, as demonstrated by a reduction in neuronal soma size, growth cone area, neurite length and branch numbers. Notably, electrophysiology analyses showed defects in excitatory and inhibitory synaptic transmission. Furthermore, transcriptome analyses revealed that multiple biological pathways related to neuron projection, motility and regulation of neurogenesis were disrupted in cells with SHANK3 knockdown. In conclusion, utilizing a human iPSC-based neural induction model, this study presented combined morphological, electrophysiological and transcription evidence that support that SHANK3 as an intrinsic, cell autonomous factor that controls cellular function development in human neurons
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