Genetic Approach for Joint Transmission Grouping in Next-Generation Cellular Networks.

Coordinated multipoint joint transmission (JT) is one of the critical downlink transmission technologies to improve network throughput. However, multiple cells in a JT group should have the same user data to transmit simultaneously, resulting in a considerable backhaul burden. Even when cells are already equipped with caches in fifth-generation networks, JT groups, without effectively utilizing the caching data, still cause unnecessary backhaul data traffic. In this article, we investigate the JT grouping problem with the consideration of caches at cells. Then, we propose a genetic approach to solve the above problem with the objective of minimizing the amount of backhaul data traffic subject to the data-rate requirement of each user. The simulation results show that our proposed generic algorithm can significantly decrease the backhaul bandwidth consumption compared to the two baselines.

Cross-Cycled Uplink Resource Allocation over NB-IoT.

Before each user equipment (UE) can send data using the narrowband physical uplink shared channel (NPUSCH), each UE should periodically monitor a search space in the narrowband physical downlink control channel (NPDCCH) to decode a downlink control indicator (DCI) over narrowband Internet of Things (NB-IoT). This monitoring period, called the NPDCCH period in NB-IoT, can be flexibly adjusted for UEs with different channel qualities. However, because low-cost NB-IoT UEs operate in the half-duplex mode, they cannot monitor search spaces in NPDCCHs and transmit data in the NPUSCH simultaneously. Thus, as we observed, a percentage of uplink subframes will be wasted when UEs monitor search spaces in NPDCCHs, and the wasted percentage is higher when the monitored period is shorter. In this paper, to address this issue, we formulate the cross-cycled resource allocation problem to reduce the consumed subframes while satisfying the uplink data requirement of each UE. We then propose a cross-cycled uplink resource allocation algorithm to efficiently use the originally unusable NPUSCH subframes to increase resource utilization. Compared with the two resource allocation algorithms, the simulation results verify our motivation of using the cross-cycled radio resources to achieve massive connections over NB-IoT, especially for UEs with high channel qualities. The results also showcase the efficiency of the proposed algorithm, which can be flexibly applied for more different NPDCCH periods.

Bracteanolide A abrogates oxidative stress-induced cellular damage and protects against hepatic ischemia and reperfusion injury in rats.

Liver diseases, including viral hepatitis, liver cirrhosis, and liver cancer, mostly remain silent until the late stages and pose a continuing threat to millions of people worldwide. Liver transplantation is the most appropriate solution in the case of liver failure, but it is associated with hepatic ischemia and reperfusion (I/R) injury which severely reduces the prognosis of the patients. In order to ameliorate I/R injury, we investigated the potential of bracteanolide A, from the herb Tradescantia albiflora Kunth in protecting the liver from I/R injury. We first determined the protective effect of bracteanolide A against oxidative stress and DNA damage using HepG2 hepatocyte cell line and then assessed the levels of inflammatory cytokines and antioxidant proteins in response to hepatic insult using an animal model of hepatic I/R injury. The results showed bracteanolide A greatly enhanced cell survival and decreased reactive oxygen species (ROS) production under H2O2 induction. It also upregulated the expression of nuclear factor (erythroid-derived 2)-like2 (Nrf2) and its downstream cytoprotective proteins NAD(P)H quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). Bracteanolide A effectively reduced the severity of liver lesions in I/R-injured rats revealed by histological analysis and significantly decreased the levels of alanine transaminase (ALT), aspartate transaminase (AST), cyclooxygenase-2, and inflammatory cytokines interleukin (IL)-1ß and tumor necrosis factor (TNF)-α. Bracteanolide A preconditioning effectively protected the liver from I/R damage in the animal model, and this easily applied procedure may provide a new means to ameliorate hepatic I/R injury during liver surgeries.

Conversation effects on neural mechanisms underlying reaction time to visual events while viewing a driving scene using MEG.

Magnetoencephalography (MEG) imaging examined the neural mechanisms that modulate reaction times to visual events while viewing a driving video, with and without a conversation. Twenty-four subjects ages 18-65 were monitored by whole-head MEG. The primary tasks were to monitor a driving video and to depress a foot pedal in response to a small red light presented to the left or below the driving scene at unpredictable times. The behavioral reaction time (RT) to the lights was recorded. The secondary task was a hands-free conversation. The subject pressed a button to answer a ring tone, and then covertly answered pre-recorded non-emotional questions such as "What is your birth date?" RTs for the conversation task (1043 ms, SE=65 ms) were slightly longer than for the primary task (baseline no conversation (944 ms, SE=48 ms)). During the primary task RTs were inversely related to the amount of brain activity detected by MEG in the right superior parietal lobe (Brodmann's Area 7). Brain activity was seen in the 200 to 300 ms range after the onset of the red light and in the visual cortex (BA 19) about 85 ms after the red light. Conversation reduced the strengths of these regression relationships and increased mean RT. Conversation may contribute to increased reaction times by (1) damping brain activation in specific regions during specific time windows, or (2) reducing facilitation from attention inputs into those areas or (3) increasing temporal variability of the neural response to visual events. These laboratory findings should not be interpreted as indicative of real-world driving, without on-road validation, and comparison to other in-vehicle tasks.

Conversation effects on neural mechanisms underlying reaction time to visual events while viewing a driving scene: fMRI analysis and asynchrony model.

This neuroimaging study investigated the neural mechanisms of the effect of conversation on visual event detection during a driving-like scenario. The static load paradigm, established as predictive of visual reaction time in on-road driving, measured reaction times to visual events while subjects watched a real-world driving video. Behavioral testing with twenty-eight healthy volunteers determined the reaction time effects from overt and covert conversation tasks in this paradigm. Overt and covert conversation gave rise to longer visual event reaction times in the surrogate driving paradigm compared to just driving with no conversation, with negligible effect on miss rates. The covert conversation task was then undertaken by ten right-handed healthy adults in a 4-Tesla fMRI magnet. We identified a frontal-parietal network that maintained event detection performance during the conversation task while watching the driving video. Increased brain activations for conversation vs. no conversation during such simulated driving was found not only in language regions (Broca's and Wernicke's areas), but also specific regions in bilateral inferior frontal gyrus, bilateral anterior insula and orbitofrontal cortex, bilateral lateral prefrontal cortex (right middle frontal gyrus and left frontal eye field), supplementary motor cortex, anterior and posterior cingulate gyrus, right superior parietal lobe, right intraparietal sulcus, right precuneus, and right cuneus. We propose an Asynchrony Model in which the frontal regions have a top-down influence on the synchrony of neural processes within the superior parietal lobe and extrastriate visual cortex that in turn modulate the reaction time to visual events during conversation while driving.