199 research outputs found
Non-adiabatic effects in periodically driven-dissipative open quantum systems
We present a general method to calculate the quasi-stationary state of a
driven-dissipative system coupled to a transmission line (and more generally,
to a reservoir) under periodic modulation of its parameters. Using Floquet's
theorem, we formulate the differential equation for the system's density
operator which has to be solved for a single period of modulation. On this
basis we also provide systematic expansions in both the adiabatic and
high-frequency regime. Applying our method to three different systems -- two-
and three-level models as well as the driven nonlinear cavity -- we propose
periodic modulation protocols of parameters leading to a temporary suppression
of effective dissipation rates, and study the arising non-adiabatic features in
the response of these systems.Comment: 12 pages, 8 figure
Toward a transformative-activist co-exploration of the world?:Emancipatory co-research in Psychology from the Standpoint of the Subject
Layered van der Waals crystals with hyperbolic light dispersion
AbstractCompared to artificially structured hyperbolic metamaterials, whose performance is limited by the finite size of the metallic components, the sparse number of naturally hyperbolic materials recently discovered are promising candidates for the next generation of hyperbolic materials. Using first-principles calculations, we extend the number of known naturally hyperbolic materials to the broad class of layered transition metal dichalcogenides (TMDs). The diverse electronic properties of the transition metal dichalcogenides result in a large variation of the hyperbolic frequency regimes ranging from the near-infrared to the ultraviolet. Combined with the emerging field of van der Waals heterostructuring, we demonstrate how the hyperbolic properties can be further controlled by stacking different two-dimensional crystals opening new perspectives for atomic-scale design of photonic metamaterials. As an application, we identify candidates for Purcell factor control of emission from diamond nitrogen-vacancy centers.</jats:p
Metformin-induced changes of the gut microbiota in healthy young men:results of a non-blinded, one-armed intervention study
Recent Progress of the Computational 2D Materials Database (C2DB)
The C2DB is a highly curated open database organizing a wealth of computed
properties for more than 4000 atomically thin two-dimensional (2D) materials.
Here we report on new materials and properties that were added to the database
since its first release in 2018. The set of new materials comprise several
hundred monolayers exfoliated from experimentally known layered bulk materials,
(homo)bilayers in various stacking configurations, native point defects in
semiconducting monolayers, and chalcogen/halogen Janus monolayers. The new
properties include exfoliation energies, Bader charges, spontaneous
polarisations, Born charges, infrared polarisabilities, piezoelectric tensors,
band topology invariants, exchange couplings, Raman- and second harmonic
generation spectra. We also describe refinements of the employed material
classification schemes, upgrades of the computational methodologies used for
property evaluations, as well as significant enhancements of the data
documentation and provenance. Finally, we explore the performance of Gaussian
process-based regression for efficient prediction of mechanical and electronic
materials properties. The combination of open access, detailed documentation,
and extremely rich materials property data sets make the C2DB a unique resource
that will advance the science of atomically thin materials.Comment: 30 pages, 26 figure
Diversity Arrays Technology (DArT) for Pan-Genomic Evolutionary Studies of Non-Model Organisms
Background: High-throughput tools for pan-genomic study, especially the DNA microarray platform, have sparked a remarkable increase in data production and enabled a shift in the scale at which biological investigation is possible. The use of microarrays to examine evolutionary relationships and processes, however, is predominantly restricted to model or near-model organisms.
Methodology/Principal Findings: This study explores the utility of Diversity Arrays Technology (DArT) in evolutionary studies of non-model organisms. DArT is a hybridization-based genotyping method that uses microarray technology to identify and type DNA polymorphism. Theoretically applicable to any organism (even one for which no prior genetic data are available), DArT has not yet been explored in exclusively wild sample sets, nor extensively examined in a phylogenetic framework. DArT recovered 1349 markers of largely low copy-number loci in two lineages of seed-free land plants: the diploid fern Asplenium viride and the haploid moss Garovaglia elegans. Direct sequencing of 148 of these DArT markers identified 30 putative loci including four routinely sequenced for evolutionary studies in plants. Phylogenetic analyses of DArT genotypes reveal phylogeographic and substrate specificity patterns in A. viride, a lack of phylogeographic pattern in Australian G. elegans, and additive variation in hybrid or mixed samples.
Conclusions/Significance: These results enable methodological recommendations including procedures for detecting and analysing DArT markers tailored specifically to evolutionary investigations and practical factors informing the decision to use DArT, and raise evolutionary hypotheses concerning substrate specificity and biogeographic patterns. Thus DArT is a demonstrably valuable addition to the set of existing molecular approaches used to infer biological phenomena such as adaptive radiations, population dynamics, hybridization, introgression, ecological differentiation and phylogeography
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