Behavioral Anomalies in Cryptocurrency Markets

If behavioral biases explain asset pricing anomalies, they should also materialize in cryptocurrency markets. I test more than 20 stock return anomalies based on daily cryptocurrency data, and document strong evidence of price momentum. Controlling for market and size, price momentum remains statistically significant, whereas price reversal and risk-based anomalies are weak. Cryptocurrency anomalies can be explained by behavioral theories that emphasize noise trader risks than fundamental risks

Mixed-Frequency Predictive Regressions

We explore the performance of mixed-frequency predictive regressions for stock returns from the perspective of a Bayesian investor. We develop a constrained parameter learning approach for sequential estimation allowing for belief revisions. Empirically, we find that mixed-frequency models improve predictability, not only because of the combination of predictors with different frequencies but also due to the preservation of high-frequency features such as time-varying volatility. Temporally aggregated models misspecify the evolution frequency of the volatility dynamics, resulting in poor volatility timing and worse portfolio performance than the mixed-frequency specification. These results highlight the importance of preserving the potential mixed-frequency nature of predictors and volatility in predictive regressions

Improving the Transferability of Adversarial Examples via Direction Tuning

In the transfer-based adversarial attacks, adversarial examples are only generated by the surrogate models and achieve effective perturbation in the victim models. Although considerable efforts have been developed on improving the transferability of adversarial examples generated by transfer-based adversarial attacks, our investigation found that, the big deviation between the actual and steepest update directions of the current transfer-based adversarial attacks is caused by the large update step length, resulting in the generated adversarial examples can not converge well. However, directly reducing the update step length will lead to serious update oscillation so that the generated adversarial examples also can not achieve great transferability to the victim models. To address these issues, a novel transfer-based attack, namely direction tuning attack, is proposed to not only decrease the update deviation in the large step length, but also mitigate the update oscillation in the small sampling step length, thereby making the generated adversarial examples converge well to achieve great transferability on victim models. In addition, a network pruning method is proposed to smooth the decision boundary, thereby further decreasing the update oscillation and enhancing the transferability of the generated adversarial examples. The experiment results on ImageNet demonstrate that the average attack success rate (ASR) of the adversarial examples generated by our method can be improved from 87.9\% to 94.5\% on five victim models without defenses, and from 69.1\% to 76.2\% on eight advanced defense methods, in comparison with that of latest gradient-based attacks

β-Elemene enhances cisplatin-induced apoptosis of nasopharyngeal carcinoma cells involving an endoplasmic reticulum stress pathway

Purpose: To investigate whether β-elemene can enhance the anticancer activity of cisplatin in nasopharyngeal carcer (NPC) 5-8F cells and the possible molecular mechanism involved. Methods: The cytotoxicity of β-elemene and its combination with cisplatin in 5-8F cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle arrest was assessed by flow cytometry. Immunoblotting was performed to determine the expression levels of proteins related to the cell cycle (cyclin D1, p21, p27) and to cell apoptosis (Bax, cleaved caspase 9, Bcl-2, and cleaved caspase 3), as well as the endoplasmic reticulum (ER) stress pathway associated proteins. Results: In 5-8F cells, β-elemene (40 μg/mL) and cisplatin (10 mM) exhibited synergistic effects on cell apoptosis and cell cycle arrest. The endoplasmic reticulum stress pathway-related proteins were significantly upregulated after the combination treatment of β-elemene and cisplatin (p < 0.05). Conclusion: β-Elemene enhances the antitumor activity of cisplatin in 5-8F cells via a mechanism involving the endoplasmic reticulum stress pathway. Thus, β-elemene is a potential tumor-suppressive agent in the clinical management of nasopharyngeal carcinoma

FedCut: A Spectral Analysis Framework for Reliable Detection of Byzantine Colluders

This paper proposes a general spectral analysis framework that thwarts a security risk in federated Learning caused by groups of malicious Byzantine attackers or colluders, who conspire to upload vicious model updates to severely debase global model performances. The proposed framework delineates the strong consistency and temporal coherence between Byzantine colluders' model updates from a spectral analysis lens, and, formulates the detection of Byzantine misbehaviours as a community detection problem in weighted graphs. The modified normalized graph cut is then utilized to discern attackers from benign participants. Moreover, the Spectral heuristics is adopted to make the detection robust against various attacks. The proposed Byzantine colluder resilient method, i.e., FedCut, is guaranteed to converge with bounded errors. Extensive experimental results under a variety of settings justify the superiority of FedCut, which demonstrates extremely robust model performance (MP) under various attacks. It was shown that FedCut's averaged MP is 2.1% to 16.5% better than that of the state of the art Byzantine-resilient methods. In terms of the worst-case model performance (MP), FedCut is 17.6% to 69.5% better than these methods