Optimal Attack against Autoregressive Models by Manipulating the Environment

We describe an optimal adversarial attack formulation against autoregressive time series forecast using Linear Quadratic Regulator (LQR). In this threat model, the environment evolves according to a dynamical system; an autoregressive model observes the current environment state and predicts its future values; an attacker has the ability to modify the environment state in order to manipulate future autoregressive forecasts. The attacker's goal is to force autoregressive forecasts into tracking a target trajectory while minimizing its attack expenditure. In the white-box setting where the attacker knows the environment and forecast models, we present the optimal attack using LQR for linear models, and Model Predictive Control (MPC) for nonlinear models. In the black-box setting, we combine system identification and MPC. Experiments demonstrate the effectiveness of our attacks

Transition in Hypersonic Boundary Layers: Role of Dilatational Waves

Transition and turbulence production in a hypersonic boundary layer is investigated in a Mach 6 quiet wind tunnel using Rayleigh-scattering visualization, fast-response pressure measurements, and particle image velocimetry. It is found that the second instability acoustic mode is the key modulator of the transition process. The second mode experiences a rapid growth and a very fast annihilation due to the effect of bulk viscosity. The second mode interacts strongly with the first vorticity mode to directly promote a fast growth of the latter and leads to immediate transition to turbulence.Comment: 5 pages, 6 figure

A New World for Chemical Synthesis?

This perspective seeks to provide an overarching vision of the current state of chemical synthesis methodology using machinery as enabling tools. It highlights current capabilities and limitations in this highly digitally-connected world and suggests areas where new opportunities may arise in the future by going well beyond our present levels of innovation and automation. There is a new need for improved downstream processing tools, advanced reactor design, computational predictive algorithms and integration of robotic systems to maximise the human resource to facilitate a new era in the assembly of our functional materials.The authors gratefully acknowledge financial support from Pfizer (Y.C.), DSTL (O. M.) and the H2020-FET OPEN-2016-2017 Programme of the European commission (D.E.F., S.V.L.;grant agreement number:737266-ONE FLOW

A Practical Method for Continuous Production of sp3-Rich Compounds from (Hetero)Aryl Halides and Redox-Active Esters.

A practically useful coupling reaction between aromatic halides and redox-active esters was realized by nickel catalysis through the use of a packed zinc bed column in continuous flow. Multiple reuse of the column showed a negligible decrease in efficiency, affording high space/time yields. A wide range of substrates, including a number of heteroaryl halides and polyfunctional materials were coupled in generally good yields. Longer-time and larger-scale experiments further demonstrates the robustness of the system

Exploring Social Networks: An Analysis of Intra-organizational Networks

This research investigates intra-organizational social networks by employing network science methods, aiming to provide actionable insights for both managers and employees. Using datasets from the Colorado Index of Complex Networks (ICON), this study examines four intra-organizational networks from a consulting firm and a research team, focusing on advice requests and skill awareness. The analysis includes network topology, degree distribution, community detection, correlation between communities and node attributes, maximal clique detection, and multilayer network analysis. The findings reveal that intra-organizational networks are intricate and significantly impact organizational efficiency and individual career development. Key insights include the importance of mid-level employees in network connectivity, the existence of bad edges where advice is sought from less competent peers, and the influence of regional and locational factors on communication patterns. The study emphasizes the need to enhance knowledge sharing and inter-region communications. For employees, understanding the structure of these networks can guide them to more effectively leverage their social connections for career advancement. This interdisciplinary effort bridges gaps in the existing literature and showcases the potential of integrating network science methods into social science research

A Photoredox Coupling Reaction of Benzylboronic Esters and Carbonyl Compounds in Batch and Flow.

Mild cross-coupling reaction between benzylboronic esters with carbonyl compounds and some imines was achieved under visible-light-induced iridium-catalyzed photoredox conditions. Functional group tolerance was demonstrated by 51 examples, including 13 heterocyclic compounds. Gram-scale reaction was realized through the use of computer-controlled continuous flow photoreactors.Uniqsis Ltd and Mark Ladlow for the generous loan 236 of a Photosyn reactor. Y.C. thanks Pfizer for funding the 237 postdoctoral fellowship. The authors also gratefully acknowl- 238 edge financial support from H2020-FETOPEN-2016-2017 239 program of European commission (S.V.L.; grant agreement 240 no.: 737266-ONE FLOW)