On the origin of exponential growth in induced earthquakes in Groningen

The Groningen gas field shows exponential growth in earthquakes event counts around a magnitude M1 with a doubling time of 6-9 years since 2001. This behavior is identified with dimensionless curvature in land subsidence, which has been evolving at a constant rate over the last few decades {essentially uncorrelated to gas production.} We demonstrate our mechanism by a tabletop crack formation experiment. The observed skewed distribution of event magnitudes is matched by that of maxima of event clusters with a normal distribution. It predicts about one event $<$\,M5 per day in 2025, pointing to increasing stress to human living conditions.Comment: 12 pages, 7 figures, to appear in Earthquakes and Structure

Numerical Integration of Nonlinear Wave Equations for General Relativity

A second-order numerical implementation is given for recently derived nonlinear wave equations for general relativity. The Gowdy T$^3$ cosmology is used as a test bed for studying the accuracy and convergence of simulations of one-dimensional nonlinear waves. The complete freedom in space-time slicing in the present formulation is exploited to compute in the Gowdy line-element. Second-order convergence is found by direct comparison of the results with either analytical solutions for polarized waves, or solutions obtained from Gowdy's reduced wave equations for the more general unpolarized waves. Some directions for extensions are discussed.Comment: 19 pages (LaTex), 3 figures (ps

Uniqueness in MHD in divergence form: right nullvectors and well-posedness

Magnetohydrodynamics in divergence form describes a hyperbolic system of covariant and constraint-free equations. It comprises a linear combination of an algebraic constraint and Faraday's equations. Here, we study the problem of well-posedness, and identify a preferred linear combination in this divergence formulation. The limit of weak magnetic fields shows the slow magnetosonic and Alfven waves to bifurcate from the contact discontinuity (entropy waves), while the fast magnetosonic wave is a regular perturbation of the hydrodynamical sound speed. These results are further reported as a starting point for characteristic based shock capturing schemes for simulations with ultra-relativistic shocks in magnetized relativistic fluids.Comment: To appear in J Math Phy

Scattering Lens Resolves sub-100 nm Structures with Visible Light

The smallest structures that conventional lenses are able to optically resolve are of the order of 200 nm. We introduce a new type of lens that exploits multiple scattering of light to generate a scanning nano-sized optical focus. With an experimental realization of this lens in gallium phosphide we have succeeded to image gold nanoparticles at 97 nm optical resolution. Our work is the first lens that provides a resolution in the nanometer regime at visible wavelengths.Comment: 4 pages, 3 figure

Efficient and Practical Transfer Hydrogenation of Ketones Catalyzed by a Simple Bidentate Mn−NHC Complex

Catalytic reductions of carbonyl‐containing compounds are highly important for the safe, sustainable, and economical production of alcohols. Herein, we report on the efficient transfer hydrogenation of ketones catalyzed by a highly potent Mn(I)−NHC complex. Mn−NHC 1 is practical at metal concentrations as low as 75 ppm, thus approaching loadings more conventionally reserved for noble metal based systems. With these low Mn concentrations, catalyst deactivation is found to be highly temperature dependent and becomes especially prominent at increased reaction temperature. Ultimately, understanding of deactivation pathways could help close the activity/stability‐gap with Ru and Ir catalysts towards the practical implementation of sustainable earth‐abundant Mn‐complexes

A valuable burden? The impact of children with profound intellectual and multiple disabilities on family life

Background: This study analysed parents' positive and negative appraisals of the impact of raising children with profound intellectual and multiple disabilities (PIMD) on family life. Method: Mothers (n = 52) and fathers (n = 27) of 56 children with PIMD completed a questionnaire focused on their positive and negative appraisals of the impact of childhood disability on family life. Scale means (ranging from 10 to 40) were calculated, as was the relationship between the two subscales. Results: Mothers and fathers indicated that their children affect family life both positively (M = 31.4 and 32.8, respectively) and negatively (M = 31.3 and 28.5, respectively). Only fathers showed a positive significant relationship between the positive and negative subscales. Conclusions: Parents' positive and negative appraisals co-occur. Although parents positively appraise the impact on family life, their substantial negative appraisals demand tailored support for families raising children with PIMD with a strong focus on practical support

Exploring spontaneous interactions between people with profound intellectual and multiple disabilities and their peers

Background Peers living in the same group form important interaction partners for people with profound intellectual and multiple disabilities (PIMD). Given the severity of their disabilities, direct support persons (DSPs) play a significant role in facilitating interactions between these peers. This study explores the spontaneous interactions between persons with PIMD and the possibilities provided by DSPs related to physical positioning. Method Observational data were obtained from 14 people with PIMD for three consecutive hours in a non-controlled situation. Results Of all 213 observed interactions, 5.1% were with peers, 73.4% with DSPs, 14.9% with the observer, and 6.5% with others. In 61.3% of the observed timeframes, the participants with PIMD were positioned in a way that made it impossible to touch or/and to look at a peer. Conclusion Generally, the observed positioning of the participants made contacts between peers nearly impossible. DSPs should create optimal conditions for interaction between peers