Autocrine trophic functions of brain-derived neurotrophic factor (BDNF) have been proposed for many central neurons because this neurotrophin displays striking colocalization with its receptor trkB within the CNS. In the cortex, the distribution patterns of BDNF and trkB expression are almost identical. Corticospinal neurons (CSNs) are a major cortical long-distance projecting system. They are localized in layer V of the somatosensory cortex, and their axons project into the spinal cord where they contribute to the innervation of spinal motoneurons. We have shown recently that adult CSNs express trkB mRNA and are rescued from axotomy-induced death by BDNF treatment. Half of the axotomized CSNs survived without BDNF infusions. These findings raise the possibility that endogenous cortical BDNF is involved in the trophic support of this neuronal population. To test the hypothesis that endogenous cortical BDNF promotes survival of adult CSNs, we infused the BDNFneutralizing affinity-purified antibody RAB to axotomized and unlesioned CSNs for 7 d. This treatment resulted in increased death of axotomized CSNs. Survival of unlesioned CSNs was not affected by RAB treatment. In situ hybridizations for BDNF and trkB mRNA revealed that virtually all CSNs express trkB, whereas only half of them express BDNF. Thus, autocrine/ paracrine mechanisms are likely to contribute to the endogenous BDNF protection of axotomized CSNs. We have demonstrated previously that, in addition to BDNF, glial cell linederived neurotrophic factor (GDNF) and neurotrophin 3 (NT-3) also rescue CSNs from axotomy-induced death. We now show that the rescuing by GDNF requires the presence of endogenous cortical BDNF, implicating a central role of this neurotrophin in the trophic support of axotomized CSNs and a trophic cross-talk between BDNF and GDNF regarding the maintenance of lesioned CSNs. In contrast, NT-3 promotes survival of axotomized CSNs even when endogenous cortical BDNF is neutralized by RAB, indicating a potential of compensatory mechanisms for the trophic support of CSNs.

This study shows that the prevalence of workplace violence against GPs is high in Hubei, China. Creating a prevention strategy and providing safer workplace environments for GPs should be urgently prioritized.

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In this paper, we propose a discrete Hartley transform (DHT)-spread technique for peak-to-average power ratio (PAPR) reduction in a DHT-based asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) system. At the complementary cumulative distribution function of 10 À3 , the PAPR values of our proposed scheme are about 9.7 and 6.2 dB lower than those of conventional DHT-based ACO-OFDM without DHT-spread technique for 2-pulse-amplitude modulation (2-PAM) and 4-PAM, respectively. The transmission experiment over a 100-km standard singlemode fiber had been realized to verify the feasibility of the proposed scheme. When the overall link rate was about 10 Gb/s, the proposed scheme had an approximately 7-dB improvement of received sensitivity at forward error correction limit compared with the conventional scheme. The proposed scheme has better transmission performance than the conventional scheme due to its low PAPR and effective equalization.Index Terms: Discrete Hartley transform (DHT), DHT-spread technique, asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM), peak-to-average power ratio (PAPR) reduction, intensity-modulated/direct-detection (IM/DD) systems.

Coal and gas outburst is a dynamic phenomenon in underground mining engineering that is often accompanied by the throwing and breakage of large amounts of coal. To study the crushing effect and its evolution during outbursts, coal samples with different initial particle sizes were evaluated using a coal and gas outburst testing device. Three basic particle sizes, 5-10 mesh, 10-40 mesh, and 40-80 mesh, as well as some mixed particle size coal samples were used in tests. The coal particles were pre-compacted at a pressure of 4 MPa before the tests. The vertical ground stress (4 MPa) and the horizontal ground stress (2.4 MPa) were initially simulated by the hydraulic system and maintained throughout. During the tests, the samples were first placed in a vacuum for 3 h, and the coal was filled with gas (CH 4) for an adsorption time of approximately 5 h. Finally, the gas valve was shut off and the coal and gas outburst was induced by quickly opening the outburst hole. The coal particles that were thrown out by the outburst test device were collected and screened based on the particle size. The results show the following. (1) Smaller particle sizes have a worse crushing effect than larger sizes. Furthermore, the well-graded coal particles are weakly broken during the outburst process. (2) As the number of repeated tests increases, the relative breakage index grows; however, the increment of growth decreases after each test, showing that further fragmentation becomes increasingly difficult.