University of Jena

About: University of Jena is a education organization based out in Jena, Thüringen, Germany. It is known for research contribution in the topics: Laser & Population. The organization has 22198 authors who have published 45159 publications receiving 1401514 citations. The organization is also known as: Friedrich-Schiller-Universität Jena & Friedrich Schiller University Jena.

Resource pulses, species interactions and diversity maintenance in arid and semi-arid environments

Abstract: Arid environments are characterized by limited and variable rainfall that supplies resources in pulses. Resource pulsing is a special form of environmental variation, and the general theory of coexistence in variable environments suggests specific mechanisms by which rainfall variability might contribute to the maintenance of high species diversity in arid ecosystems. In this review, we discuss physiological, morphological, and life-history traits that facilitate plant survival and growth in strongly water-limited variable environments, outlining how species differences in these traits may promote diversity. Our analysis emphasizes that the variability of pulsed environments does not reduce the importance of species interactions in structuring communities, but instead provides axes of ecological differentiation between species that facilitate their coexistence. Pulses of rainfall also influence higher trophic levels and entire food webs. Better understanding of how rainfall affects the diversity, species composition, and dynamics of arid environments can contribute to solving environmental problems stemming from land use and global climate change.

Metamaterial-inspired silicon nanophotonics

Abstract: Applying metamaterial concepts to dielectric systems offers low losses compared with metallic structures. Here, silicon-based metamaterial and nanophotonic advances are reviewed. The prospect of creating metamaterials with optical properties greatly exceeding the parameter space accessible with natural materials has been inspiring intense research efforts in nanophotonics for more than a decade. Following an era of plasmonic metamaterials, low-loss dielectric nanostructures have recently moved into the focus of metamaterial-related research. This development was mainly triggered by the experimental observation of electric and magnetic multipolar Mie-type resonances in high-refractive-index dielectric nanoparticles. Silicon in particular has emerged as a popular material choice, due to not only its high refractive index and very low absorption losses in the telecom spectral range, but also its paramount technological relevance. This Review overviews recent progress on metamaterial-inspired silicon nanostructures, including Mie-resonant and off-resonant regimes.

Observation of a Topological Transition in the Bulk of a Non-Hermitian System.

Abstract: We present the first experimental observation of a topological transition in a non-Hermitian system. In contrast to standard methods for examining topological properties, which involve probing edge (or surface) states, we monitor the topological transition by employing bulk dynamics only. The system is composed of a lattice of evanescently coupled optical waveguides, and non-Hermitian behavior is engineered by inducing bending loss by spatially "wiggling" every second waveguide.

Does contact reduce prejudice or does prejudice reduce contact? A longitudinal test of the contact hypothesis among majority and minority groups in three European countries.

Abstract: A widely researched panacea for reducing intergroup prejudice is the contact hypothesis. However, few longitudinal studies can shed light on the direction of causal processes: from contact to prejudice reduction (contact effects) or from prejudice to contact reduction (prejudice effects). The authors conducted a longitudinal field survey in Germany, Belgium, and England with school students. The sample comprised members of both ethnic minorities (n = 512) and ethnic majorities (n = 1,143). Path analyses yielded both lagged contact effects and prejudice effects: Contact reduced prejudice, but prejudice also reduced contact. Furthermore, contact effects were negligible for minority members. These effects were obtained for 2 indicators of prejudice: negative intergroup emotions and desire for social distance. For both majority and minority members, contact effects on negative emotions were stronger when outgroup contacts were perceived as being typical of their group. Contact effects were also mediated by intergroup anxiety. This mediating mechanism was impaired for minority members because of a weakened effect of anxiety on desire for social distance. Theoretical and practical implications of these findings are discussed.