Posttraumatic epilepsy is a major source of disability following traumatic brain injury (TBI) and a common cause of medically-intractable epilepsy. Previous attempts to prevent the development of posttraumatic epilepsy with treatments administered immediately following TBI have failed. Recently, the mammalian target of rapamycin complex 1 (mTORC1) pathway has been implicated in mechanisms of epileptogenesis and the mTORC1 inhibitor, rapamycin, has been proposed to have antiepileptogenic effects in preventing some types of epilepsy. In this study, we have tested the hypothesis that rapamycin has antiepileptogenic actions in preventing the development of posttraumatic epilepsy in an animal model of TBI. A detailed characterization of posttraumatic epilepsy in the mouse controlled cortical impact model was first performed using continuous video-EEG monitoring for 16 weeks following TBI. Controlled cortical impact injury caused immediate hyperactivation of the mTORC1 pathway lasting at least one week, which was reversed by rapamycin treatment. Rapamycin decreased neuronal degeneration and mossy fiber sprouting, although the effect on mossy fiber sprouting was reversible after stopping rapamycin and did not directly correlate with inhibition of epileptogenesis. Most posttraumatic seizures occurred greater than 10 weeks after TBI, and rapamycin treatment for one month after TBI decreased the seizure frequency and rate of developing posttraumatic epilepsy during the entire 16 week monitoring session. These results suggest that rapamycin may represent a rational treatment for preventing posttraumatic epilepsy in patients with TBI.

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Abstract-In this paper, we investigate the secrecy performance of multiuser dual-hop relay networks where a base station (BS) communicates with multiple legitimate users via the assistance of a trustful regenerative relay in the presence of multiple eavesdroppers. Particularly, the maximal ratio transmission (MRT) scheme is exploited at the BS and a threshold-based multiuser scheduling scheme is employed over the legitimate users, while concerning the imperfect decoding at the regenerative relay. To evaluate the secrecy performance of the considered system, two practical situations are addressed based on the availability of eavesdropper's channel state information (CSI), i.e., Scenario I, where the eavesdropper's CSI is not available at the relay, and Scenario II, where the eavesdropper's CSI is available at the relay. For both scenarios, we further consider two eavesdropping modes, i.e., colluding eavesdropping and non-colluding eavesdropping. For Scenario I, new exact and asymptotic closed-form expressions of the secrecy outage probability (SOP) are derived. For Scenario II, we derive new exact and asymptotic closedform expressions of ergodic secrecy rate (ESR). The asymptotic SOPs demonstrate that the secrecy diversity order is independent of the number of legitimate users NB and eavesdroppers NE, the number of antennas equipped at eavesdroppers AE as well as fading factor of the wiretap channel mE. Furthermore, we also determine the secrecy multiplexing gain and the power cost to explicitly quantify the impact of the legitimate channel and wiretap channel on ergodic secrecy rate. Our findings demonstrate that increasing the switching threshold, the number of antennas at the BS, and the number of legitimate users have a positive impact on secrecy performance.Index Terms-Physical layer security, cooperative relay, multiuser diversity, threshold-based scheduling scheme, secrecy outage probability, ergodic secrecy rate.

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Seizures may directly cause brain injury by disrupting the structure and function of synapses. Previous studies using in vivo time-lapse imaging have demonstrated an acute beading of dendrites and loss of dendritic spines immediately following status epilepticus, but the effects of brief seizures and the long-term evolution of this dendritic injury are unknown. Here, we examined the effects of seizures of varying durations on dendritic structure over several weeks using in vivo multiphoton imaging with kainate-induced seizures in mice. The degree of dendritic injury was directly dependent on the duration of the seizures, with seizures lasting more than 30 minutes (status epilepticus) resulting in a greater than 75% spine loss. However, even brief seizures (<5 minutes) induced moderate dendritic beading and spine loss. The dendritic injury from brief seizures usually recovered within two weeks, whereas status epilepticus-induced injury only partially reversed. These studies demonstrate that seizures of all durations may trigger at least transient neuronal injury.

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Power cables operate at high temperatures over long periods of time, and the electrical behavior of silicone rubber (SIR) in the new types of extra-high-voltage prefabricated cable accessories would change as a result of thermal aging. In this study, tests were conducted to reveal the effects of thermal aging (1000 h at 60-180°C) on the electrical treeing behavior. It was found that with increasing thermal aging time, the average electrical tree initiation voltage (ATIV) of SIR initially increases to a peak value and then decreases, finally becoming stable within 1000 h. Meanwhile, the probability of pine-like trees decreases at first and then increases, whereas the probability of bush-like trees initially increases and then decreases. The thermal aging temperature affects the rate of ATIV following the Arrhenius equation. These results strongly imply the existence of a thermal aging process that greatly influences the treeing degradation process. The results obtained using differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) indicate that thermal oxidation plays a major role in the initial thermal aging process and facilitates additional crosslinking, which enhances ATIV. With increasing thermal aging time, thermal degradation and thermal crack reactions play leading roles, resulting in decreased crystallinity and ATIV. Microcracks are present after long-term thermal aging, and they are the dominant factor in ATIV stability. ATIV stability also provides a theoretical basis for the electrical strength design margin for insulating materials.