Enhanced acoustic transmission through a slanted grating

It is known that an acoustic wave incident on an infinite array of aligned rectangular blocks of a different acoustic material exhibits total transmission if certain conditions are met [1] which relate the unique "intromission" angle of incidence with geometric and material properties of the slab. This extraordinary acoustic transmission phenomenon holds for any slab thickness, making it analogous to a Brewster effect in optics, and is independent of frequency as long as the slab microstructure is sub-wavelength in the length-wise direction. Here we show that the enhanced transmission effect is obtained in a slab with grating elements oriented obliquely to the slab normal. The dependence of the intromission angle $\theta_i$ is given explicitly in terms of the orientation angle. Total transmission is achieved at incidence angles $\pm \theta_i$, with a relative phase shift between the transmitted amplitudes of the $+\theta_i$ and $- \theta_i$ cases. These effects are shown to follow from explicit formulas for the transmission coefficient. In the case of grating elements that are rigid the results have direct physical interpretation. The analytical findings are illustrated with full wave simulations.Comment: 15 page, 16 figure

PROSOCIAL BEHAVIOR IN ENVY SCENARIOS

We investigated prosocial behavior in different envy conditions. Participants (N = 118) responded to partners&#39; requests for help after taking part in either a control scenario or scenarios where they felt that their partner was envious of them based on their performance (input), a reward (output), or both (input-output). Results showed significantly different levels of prosocial behavior, with this being highest in the output envy scenario and lowest in the input-output envy scenario. Effects of benign and malicious envy were also assessed across scenarios. In the input and output scenarios, malicious envy positively predicted prosocial behaviors and benign envy negatively predicted prosocial behaviors, whereas the opposite was true in the input-output scenario. Our results imply that employees experiencing benign envy can be motivated to improve their own abilities and performance, whereas perceiving malicious envy is likely to elicit prosocial behavior by the envied person toward envious employees.</p

Selective Formation of S4- and T-Symmetric Supramolecular Tetrahedral Cages and Helicates in Polar Media Assembled via Cooperative Action of Coordination and Hydrogen-Bonds

We report on the synthesis and self-assembly study of novel supramolecular monomers encompassing quadruple hydrogen-bonding motifs and metal coordinating 2,2’-bipyridine units. When mixed with metal ions such as Fe2+ or Zn2+, the tetrahedron cage complexes are formed in quantitative yields and full diastereoselectivity, even in highly polar acetonitrile or methanol solvents. The symmetry of the complexes obtained has been shown to depend critically on the flexibility of the ligand. Restriction of the rotation of the hydrogen-bonding unit with respect to the metal coordinating site results in a T-symmetric cage, whereas by introducing flexibility either through a methylene linker or rotating benzene ring allows the formation of S4-symmetric cages with self-filled interior. In addition, the possibility to select between tetrahedral cages or helicates, and to control the dimensions of the aggregate, has been demonstrated with three component assembly using external hydrogen-bonding molecular inserts or by varying the radius of the metal ion (Hg2+ vs Fe2+). Self-sorting studies of individual Fe2+ complexes of with ligands of different sizes revealed their inertness toward ligand scrambling.peerReviewe