Although a number of publications have highlighted the important and challenging issues involved in designing RRM algorithms for OFDMA networks, only recently a number of papers have investigated relay-enhanced OFDMA-based multicellular networks. By and large, the literature indicates that these issues constitute a hot research topic that will continue to attract interest. This paper provides a survey of the current literature on OFDMA networks enhanced with decode-and-forward relaying and provides their link to earlier literature in non-OFDMA networks. In addition, a rich list of references is provided to direct the readers toward some of the emerging techniques.

Huntington's disease (HD), an inherited neurodegenerative disorder, is caused by an expansion of cytosine-adenine-guanine repeats in the huntingtin gene. The aggregation of mutant huntingtin (mtHTT) and striatal cell loss are representative features to cause uncontrolled movement and cognitive defect in HD. However, underlying mechanism of mtHTT aggregation and cell toxicity remains still elusive. Here, to find new genes modulating mtHTT aggregation, we performed cell-based functional screening using the cDNA expression library and isolated IRE1 gene, one of endoplasmic reticulum (ER) stress sensors. Ectopic expression of IRE1 led to its self-activation and accumulated detergent-resistant mtHTT aggregates. Treatment of neuronal cells with ER stress insults, tunicamycin and thapsigargin, increased mtHTT aggregation via IRE1 activation. The kinase activity of IRE1, but not the endoribonuclease activity, was necessary to stimulate mtHTT aggregation and increased death of neuronal cells, including SH-SY5Y and STHdhQ111/111 huntingtin knock-in striatal cells. Interestingly, ER stress impaired autophagy flux via IRE1-TRAF2 pathway, thus enhancing cellular accumulation of mtHTT. Atg5 deficiency in M5-7 cells increased mtHTT aggregation but blocked ER stress-induced mtHTT aggregation. Further, ER stress markers including p-IRE1 and autophagy markers such as p62 were up-regulated exclusively in the striatal tissues of HD mouse models and in HD patients. Moreover, down-regulation of IRE1 expression rescues the rough-eye phenotype by mtHTT in a HD fly model. These results suggest that IRE1 plays an essential role in ER stress-mediated aggregation of mtHTT via the inhibition of autophagy flux and thus neuronal toxicity of mtHTT aggregates in HD.

Abstract-Relaying and orthogonal frequency division multiple access (OFDMA) are the accepted technologies for emerging wireless communications standards. The activities in many wireless standardization bodies and forums, for example IEEE 802.16 j/m and LTE-Advanced, attest to this fact. The availability or lack thereof of efficient radio resource management (RRM) could make or mar the opportunities in these networks. Although distributed schemes are more attractive, it is essential to seek outstanding performance benchmarks to which various decentralized schemes can be compared. Therefore, this paper provides a comprehensive centralized RRM algorithm for downlink OFDMA cellular fixed relay networks in a way to ensure user fairness with minimal impact on network throughput. In contrast, it has been observed that pure opportunistic schemes and fairness-aware schemes relying solely on achievable and allocated capacities may not attain the desired fairness, e.g., proportional fair scheduling. The proposed scheme is queueaware and performs three functions jointly; dynamic routing, fair scheduling, and load balancing among cell nodes. We show that the proposed centralized scheme is different from the traditional centralized schemes in terms of the substantial savings in complexity and feedback overhead.

Abnormally hyperphosphorylated tau is often caused by tau kinases, such as GSK3β and Cdk5. Such occurrence leads to neurofibrillary tangle formation and neuronal degeneration in tauopathy, including Alzheimer's disease (AD). However, little is known about the signaling cascade underlying the pathologic phosphorylation of tau by Aβ(42). In this study, we show that adenylate kinase 1 (AK1) is a novel regulator of abnormal tau phosphorylation. AK1 expression is markedly increased in the brains of AD patients and AD model mice and is significantly induced by Aβ(42) in the primary neurons. Ectopic expression of AK1 alone augments the pathologic phosphorylation of tau at PHF1, CP13 and AT180 epitopes and enhances the formation of tau aggregates. Inversely, downregulation of AK1 alleviates Aβ(42)-induced hyperphosphorylation of tau. AK1 plays a role in Aβ(42)-induced impairment of AMPK activity and GSK3β activation in the primary neurons. Pharmacologic studies show that treatment with an AMPK inhibitor activates GSK3β, and a GSK3β inhibitor attenuates AK1-mediated tau phosphorylation. In a Drosophila model of human tauopathy, the retinal expression of human AK1 severely exacerbates rough eye phenotype and increases abnormal tau phosphorylation. Further, neural expression of AK1 reduces the lifespan of tau transgenic files. Taken together, these observations indicate that the neuronal expression of AK1 is induced by Aβ(42) to increase abnormal tau phosphorylation via AMPK-GSK3β and contributes to tau-mediated neurodegeneration, providing a new upstream modulator of GSK3β in the pathologic phosphorylation of tau.

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