rac-4-[4-Cyano-2-(hy­droxy­meth­yl)phen­yl]-4-(4-fluoro­phen­yl)-4-hy­droxy-N,N-dimethyl­butanaminium hemifumarate

In the title salt, C20H24FN2O2 +·0.5C4H2O4 2−, the fumarate anion is located on an inversion centre. In the cation, the two benzene rings are nearly perpendicular to each other, making a dihedral angle of 87.41 (10)°. The cation is linked to the anion by a bifurcated N—H⋯O hydrogen bond. Classical O—H⋯O and weak C—H⋯F hydrogen bonding is also present in the crystal structure. Three C atoms of the N,N-dimethyl­butanaminium moiety are disordered over two sites with refined site occupancies of 0.466 (14) and 0.534 (14)

A Cost-effective Shuffling Method against DDoS Attacks using Moving Target Defense

Moving Target Defense (MTD) has emerged as a newcomer into the asymmetric field of attack and defense, and shuffling-based MTD has been regarded as one of the most effective ways to mitigate DDoS attacks. However, previous work does not acknowledge that frequent shuffles would significantly intensify the overhead. MTD requires a quantitative measure to compare the cost and effectiveness of available adaptations and explore the best trade-off between them. In this paper, therefore, we propose a new cost-effective shuffling method against DDoS attacks using MTD. By exploiting Multi-Objective Markov Decision Processes to model the interaction between the attacker and the defender, and designing a cost-effective shuffling algorithm, we study the best trade-off between the effectiveness and cost of shuffling in a given shuffling scenario. Finally, simulation and experimentation on an experimental software defined network (SDN) indicate that our approach imposes an acceptable shuffling overload and is effective in mitigating DDoS attacks

Detecting non-Markovian plasmonic band gaps in quantum dots using electron transport

Placing a quantum dot close to a metal nanowire leads to drastic changes in its radiative decay behavior because of evanescent couplings to surface plasmons. We show how two non-Markovian effects, band-edge and retardation, could be observed in such a system. Combined with a quantum dot p-i-n junction, these effects could be readout via current-noise measurements. We also discuss how these effects can occur in similar systems with restricted geometries, like phononic cavities and photonic crystal waveguides. This work links two previously separate topics: surface-plasmons and current-noise measurements.Comment: 8 page

3β-Hydroxy­friedelan-17β-carboxylic acid

The title compound, C30H50O3, which was isolated from a marine endophytic fungus, is a new friedelan derivative. The mol­ecule contains five six-membered rings, which exhibit boat (ring A), distorted boat (ring B) and chair (rings C–E) conformations. The crystal structure is stabilized by inter­molecular O—H⋯O hydrogen bonds, which link neighbouring mol­ecules into 12-membered rings

Investigating the topological structure of quenched lattice QCD with overlap fermions by using multi-probing approximation

The topological charge density and topological susceptibility are determined by multi-probing approximation using overlap fermions in quenched SU(3) gauge theory. Then we investigate the topological structure of the quenched QCD vacuum, and compare it with results from the all-scale topological density, the results are consistent. Random permuted topological charge density is used to check whether these structures represent underlying ordered properties. Pseudoscalar glueball mass is extracted from the two-point correlation function of the topological charge density. We study $3$ ensembles of different lattice spacing $a$ with the same lattice volume $16^{3}\times32$, the results are compatible with the results of all-scale topological charge density, and the topological structures revealed by multi-probing are much closer to all-scale topological charge density than that by eigenmode expansion.Comment: 12 pages,34 figure