7,905 research outputs found

    Axion Free-kick Misalignment Mechanism

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    We propose an alternative scenario for the axion misalignment mechanism based on the nontrivial interplay between the axion and a light dilaton in the early universe. Dark matter abundance is still sourced by the initial misalignment of the axion field, whose motion along the potential kicks the dilaton field away from its minimum, and dilaton starts to oscillate later with a delayed onset time for oscillation and a relatively large misalignment value due to the kick; eventually the dilaton dominates over the axion in their energy densities, and the dilaton is identified as dark matter. The kick effect due to axion motion is the most significant if the initial field value of dilaton is near its minimum; therefore, we call this scenario axion free-kick misalignment mechanism, where axion plays the role similar to a football player. Dark matter abundance can be obtained with a lower axion decay constant compared to the conventional misalignment mechanism.Comment: v2: 5+3 pages, 4 figures, references added, typo fixed, some improvements, results unchange

    Schwann cell transplantation and descending propriospinal regeneration after spinal cord injury

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    After spinal cord injury (SCI), poor ability of damaged axons of the central nervous system (CNS) to regenerate causes very limited functional recovery. Schwann cells (SCs) have been widely explored as promising donors for transplantation to promote axonal regeneration in the CNS including the spinal cord. Compared with other CNS axonal pathways, injured propriospinal tracts display the strongest regenerative response to SC transplantation. Even without providing additional neurotrophic factors, propriospinal axons can grow into the SC environment which is rarely seen in supraspinal tracts. Propriospinal tract has been found to respond to several important neurotrophic factors secreted by SCs. Therefore, the SC is considered to be one of the most promising candidates for cell-based therapies for SCI. Since many reviews have already appeared on topics of SC transplantation in SCI repair, this review will focus particularly on the rationale of SC transplantation in mediating descending propriospinal axonal regeneration as well as optimizing such regeneration by using different combinatorial strategies. This article is part of a Special Issue entitled SI: Spinal cord injury

    The Influence of Augmented Reality Technology on the Learning Interest, Achievement of Learning Goals and Cognitive Load of Middle School Students

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    In order to test the influence of augmented reality technology on the learning interest achievement of learning goals and cognitive load the instruction of topographic map was taken as an example for experimental study This paper selected 427 students from 8 classes of Grade one who all come from Zhantan Middle School in Xindu District of Chengdu as experimental samples set two classes with similar level in learning as one group the one is the experimental class and the other is the control class and formed 4 groups in total The experimental classes adopted AR three-dimensional videos as teaching aids to give new lessons and the control classes adopted traditional two- dimensional videos and then the students learning interest level achievement of learning goals and cognitive load were measured The results showed that the application of AR technology in teaching could improve students learning interest and achievement of learning goals but had no effect on reducing cognitive loa

    Signature of Pseudo Nambu-Goldstone Higgs boson in its Decay

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    If the Higgs boson is a pseudo Nambu-Goldstone boson (PNGB), the hZΞ³hZ\gamma contact interaction induced by the O(p4)\mathcal{O}(p^4) invariants of the non-linear sigma model is free from its nonlinearity effects. The process hβ†’ZΞ³h\rightarrow Z\gamma can be used to eliminate the universal effects of heavy particles, which can fake the nonlinearity effects of the PNGB Higgs boson in the process hβ†’Vβˆ—Vh\rightarrow V^*V (V=WΒ±V=W^\pm,\ ZZ). We demonstrate that the ratio of the signal strength of hβ†’ZΞ³h\rightarrow Z\gamma and hβ†’Vβˆ—Vh\rightarrow V^*V is good to distinguish the signature of the PNGB Higgs boson from Higgs coupling deviations
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