Differentially Private Consensus With Quantized Communication.

This paper focuses on studying the differentially private consensus problem in multiagent networks under a quantized communication environment, where the exact real-value state is not available for transmission due to the range limitation of digital channels. We first extend the differentially private consensus model to the case of a quantized communication environment integrated with a dynamic encoding/decoding scheme and propose a differentially private communication algorithm utilizing the quantized state with a bounded quantizer instead of the exact real-value state to reach an agreement while protecting the initial or current states of the participants from information disclosure. Then, the convergence analysis of mean square consensus in the case of an unbounded quantizer is given to explain the sufficiency of the extended model and convergence conditions. To overcome the uncertainty of saturation in the case of a bounded quantizer, we also give a statistical analysis on the boundedness of quantization that the bounded quantizer with a finite number of bits can remain unsaturated with a desired high probability under certain conditions. Furthermore, we provide the statistical analysis on the convergent accuracy, which shows that the agreement value just converges to a random variable that falls in the neighboring range of the initial state average and the expectation of the agreement value is equal to the initial state average exactly. In addition, we provide the differential privacy analysis for individual agents and the whole network, and then establish the potential relationship between the dynamic encoding/decoding scheme and the differential privacy mechanism. Finally, the simulation results visually show that the proposed algorithm and the main theoretical results are effective and correct.

An Enhanced Privacy-Preserving Authentication Scheme for Vehicle Sensor Networks.

Vehicle sensor networks (VSNs) are ushering in a promising future by enabling more intelligent transportation systems and providing a more efficient driving experience. However, because of their inherent openness, VSNs are subject to a large number of potential security threats. Although various authentication schemes have been proposed for addressing security problems, they are not suitable for VSN applications because of their high computation and communication costs. Chuang and Lee have developed a trust-extended authentication mechanism (TEAM) for vehicle-to-vehicle communication using a transitive trust relationship, which they claim can resist various attacks. However, it fails to counter internal attacks because of the utilization of a shared secret key. In this paper, to eliminate the vulnerability of TEAM, an enhanced privacy-preserving authentication scheme for VSNs is constructed. The security of our proposed scheme is proven under the random oracle model based on the assumption of the computational Diffie-Hellman problem.

Comment on "Exponential stabilization of chaotic systems with delay by periodically intermittent control" [Chaos 17, 013103 (2007)].

In the referenced paper, there is a technical carelessness in the second lemma, and it is highlighted here to avoid possible failure when the result is used to design the intermittent controller for nonlinear systems.

Organolithium-mediated diversification of peptide thiazoles.

[Reaction: see text] We report a one-step, racemization-free method for the diversification of peptide thiazoles via direct lithiation of the thiazole ring. The method is compatible with N-Boc, N-trityl, carboxylic ester, and carboxamide protecting groups and has been used to directly functionalize the thiazole ring of cyclopeptide natural products.

Kinetic control of proline amide rotamers: total synthesis of trans,trans- and cis,cis-ceratospongamide.

Ceratospongamide is a cyclic peptide natural product that is biosynthesized as a mixture of two proline rotamers. Remarkably, these rotamers do not detectably interconvert at temperatures up to 100 degress C. Here we report high-yielding syntheses of each rotamer and demonstrate that the threonine-derived oxazoline plays a critical role in determining the kinetic distribution of conformational isomers.

First Total Synthesis of an Exceptionally Potent Antitumor Saponin, OSW-1.

OSW-1 (1), an acylated disaccharide cholestane saponin from Ornithogalum saudersiae with exceptionally potent antitumor activity, was first synthesized from commercially available dehydroisoandrosterone, L-arabinose, and D-xylose in total 27 steps with the longest linear sequence of 14 steps and in 6% yield.