Comprehensive sequence-to-function mapping of cofactor-dependent RNA catalysis in the glmS ribozyme.

Massively parallel, quantitative measurements of biomolecular activity across sequence space can greatly expand our understanding of RNA sequence-function relationships. We report the development of an RNA-array assay to perform such measurements and its application to a model RNA: the core glmS ribozyme riboswitch, which performs a ligand-dependent self-cleavage reaction. We measure the cleavage rates for all possible single and double mutants of this ribozyme across a series of ligand concentrations, determining kcat and KM values for active variants. These systematic measurements suggest that evolutionary conservation in the consensus sequence is driven by maintenance of the cleavage rate. Analysis of double-mutant rates and associated mutational interactions produces a structural and functional mapping of the ribozyme sequence, revealing the catalytic consequences of specific tertiary interactions, and allowing us to infer structural rearrangements that permit certain sequence variants to maintain activity

Cybersecurity

The Internet has given rise to new opportunities for the public sector to improve efficiency and better serve constituents in the form of e-government. But with a rapidly growing user base globally and an increasing reliance on the Internet, digital tools are also exposing the public sector to new risks. An accessible primer, Cybersecurity: Public Sector Threats and Responses focuses on the convergence of globalization, connectivity, and the migration of public sector functions online. It identifies the challenges you need to be aware of and examines emerging trends and strategies from around the world. Offering practical guidance for addressing contemporary risks, the book is organized into three sections: Global Trends—considers international e-government trends, includes case studies of common cyber threats and presents efforts of the premier global institution in the field National and Local Policy Approaches—examines the current policy environment in the United States and Europe and illustrates challenges at all levels of government Practical Considerations—explains how to prepare for cyber attacks, including an overview of relevant U.S. Federal cyber incident response policies, an organizational framework for assessing risk, and emerging trends Also suitable for classroom use, this book will help you understand the threats facing your organization and the issues to consider when thinking about cybersecurity from a policy perspective

Ohm's Law in the Fast Lane: General Relativistic Charge Dynamics

Fully relativistic and causal equations for the flow of charge in curved spacetime are derived. It is believed that this is the first set of equations to be published that correctly describes the flow of charge, and evolution of the electromagnetic field, in highly dynamical relativistic environments on time scales much shorter than the collapse time ($GM/c^3$). The equations will be important for correctly investigating problems such as the dynamical collapse of magnetized stellar cores to black holes and the production of jets and gravitational waves. This system of equations, given the name of `charge dynamics', is analogous to those of hydrodynamics (which describe the flow of {\em mass} in spacetime rather than the flow of charge). The most important one in the system is the relativistic generalized Ohm's law, which is used to compute time-dependent four-current. Unlike previous equations for the current, this one ensures that charge drift velocities remain less than the speed of light, takes into account the finite current rise time, is expressed in a covariant form, and is suitable for general relativistic computations in an arbitrary metric. It includes the standard known effects (Lorentz force, Hall effect, pressure effect, and resistivity) and reduces to known forms of Ohm's law in the appropriate limits. In addition, the plasma particles are allowed to have highly relativistic drift velocities, resulting in an implicit equation for the `current beaming factor' $\gamma_q$.Comment: 23 pages, 0 figures; accepted for publication in the Astrophysical Journa

Lidar-level localization with radar? The CFEAR approach to accurate, fast and robust large-scale radar odometry in diverse environments

This paper presents an accurate, highly efficient, and learning-free method for large-scale odometry estimation using spinning radar, empirically found to generalize well across very diverse environments -- outdoors, from urban to woodland, and indoors in warehouses and mines - without changing parameters. Our method integrates motion compensation within a sweep with one-to-many scan registration that minimizes distances between nearby oriented surface points and mitigates outliers with a robust loss function. Extending our previous approach CFEAR, we present an in-depth investigation on a wider range of data sets, quantifying the importance of filtering, resolution, registration cost and loss functions, keyframe history, and motion compensation. We present a new solving strategy and configuration that overcomes previous issues with sparsity and bias, and improves our state-of-the-art by 38%, thus, surprisingly, outperforming radar SLAM and approaching lidar SLAM. The most accurate configuration achieves 1.09% error at 5Hz on the Oxford benchmark, and the fastest achieves 1.79% error at 160Hz.Comment: Accepted for publication in Transactions on Robotics. Edited 2022-11-07: Updated affiliation and citatio

Static cylindrically symmetric spacetimes

We prove existence of static solutions to the cylindrically symmetric Einstein-Vlasov system, and we show that the matter cylinder has finite extension. The same results are also proved for a quite general class of equations of state for perfect fluids coupled to the Einstein equations, extending the class of equations of state considered in \cite{BL}. We also obtain this result for the Vlasov-Poisson system.Comment: Added acknowledgemen

Energy efficient fish attraction

Fish migration past a hydro power plant (HPP) requires not only flow in the actual fish passage (e.g. fish ladder) but also sufficient water to attract the fish to the entrance. Such attraction water is typically created by spilling water of the order of 10 m3/s, and there are potential savings if the amount of water can be reduced without loss of functionality. The possibility to use ejectors (jet pumps) to pump water from the area downstream of the HPP into the fish passage has been investigated with physical model tests and numerical modelling (CFD). The ambition has been to make use of fairly simple geometries without changing the layout of the suggested fish ladder, and a solution in which the ejectors are located in a separate channel parallel to the fish ladder has been evaluated. The results show that the required spill can be reduced to 1/3 despite the low head (7 m) of the considered HPP, and the savings will be even larger in HPPs with higher head. More energy efficient ways to attract fish can be obtained if the jets are positioned within the actual fish way, but a prerequisite for such solution is that the fish is not intimidated by the jets. Another interesting option to evaluate is the possibility to guide the fish to the fish ladder entrance by an array of individual jets positioned in the river. To investigate these ideas tests with live fish are scheduled during second half of 2018

Visible-Light Photoswitching by Azobenzazoles

Three visible-light responsive photoswitches are reported, azobis(1-methyl-benzimidazole) (1), azobis(benzoxazole) (2) and azobis(benzothiazole) (3). Photostationary distributions are obtained upon irradiation with visible light comprising approximately 80 % of the thermally unstable isomer, with thermal half-lives up to 8 min and are mostly invariant to solvent. On protonation, compound 1H+ has absorption extending beyond 600 nm, allowing switching with yellow light, and a thermal half-life just under 5 minutes. The two isomers have significantly different pKa values, offering potential as a pH switch. The absorption spectra of 2 and 3 are insensitive to acid, although changes in the thermal half-life of 3 indicate more basic intermediates that significantly influence the thermal barrier to isomerization. These findings are supported by high-level ab initio calculations, which validate that protonation occurs on the ring nitrogen and that the Z isomer is more basic in all cases