25,114 research outputs found
90 degree polarization rotator using a bilayered chiral metamaterial with giant optical activity
A bilayered chiral metamaterial (CMM) is proposed to realize a 90 degree
polarization rotator, whose giant optical activity is due to the transverse
magnetic dipole coupling among the metallic wire pairs of enantiomeric
patterns. By transmission through this thin bilayered structure of less than
\lambda/30 thick, a linearly polarized wave is converted to its cross
polarization with a resonant polarization conversion efficiency (PCE) of over
90%. Meanwhile, the axial ratio of the transmitted wave is better than 40 dB.
It is demonstrated that the chirality in the propagation direction makes this
efficient cross-polarization conversion possible. The transversely isotropic
property of this polarization rotator is also experimentally verified. The
optical activity of the present structure is about 2700 degree/\lambda, which
is the largest optical activity that can be found in literature.Comment: 16 pages, 4 figure
Time-Periodic Solutions of the Einstein's Field Equations II
In this paper, we construct several kinds of new time-periodic solutions of
the vacuum Einstein's field equations whose Riemann curvature tensors vanish,
keep finite or take the infinity at some points in these space-times,
respectively. The singularities of these new time-periodic solutions are
investigated and some new physical phenomena are found. The applications of
these solutions in modern cosmology and general relativity can be expected.Comment: 10 pages, 1 figur
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Quantification of the morphology of shelly carbonate sands using 3D images
Shelly carbonate sands proliferate in regions of the world where construction of offshore structures is in high demand. These structurally weak sands have high intra-granular voids and complex angular grain shapes. To improve the understanding of the mechanical properties of the material, a detailed morphological quantification is required. This paper presents a three-dimensional characterisation of the morphology of shelly carbonate sands based on analyses of X-ray computed tomography images. Two sands from the Persian Gulf with distinct grading were investigated. An adaptive watershed segmentation technique was developed to identify the individual grains for subsequent grain-scale analysis, which overcomes the challenges posed by the intricate microstructure of these sands. Non-invasive measurements of size, intra-granular void and various shape parameters were carried out, and statistical analyses were conducted, to characterise the grains. The results help to better understand the mechanisms of grain interlocking, and the role of grain angularity and intra-granular void ratio on the mechanical behaviour of shelly carbonate sands
Domain-mediated interactions for protein subfamily identification
Within a protein family, proteins with the same domain often exhibit different cellular functions, despite the shared evolutionary history and molecular function of the domain. We hypothesized that domain-mediated interactions (DMIs) may categorize a protein family into subfamilies because the diversified functions of a single domain often depend on interacting partners of domains. Here we systematically identified DMI subfamilies, in which proteins share domains with DMI partners, as well as with various functional and physical interaction networks in individual species. In humans, DMI subfamily members are associated with similar diseases, including cancers, and are frequently co-associated with the same diseases. DMI information relates to the functional and evolutionary subdivisions of human kinases. In yeast, DMI subfamilies contain proteins with similar phenotypic outcomes from specific chemical treatments. Therefore, the systematic investigation here provides insights into the diverse functions of subfamilies derived from a protein family with a link-centric approach and suggests a useful resource for annotating the functions and phenotypic outcomes of proteins.11Ysciescopu
Logarithmic corrections in the free energy of monomer-dimer model on plane lattices with free boundaries
Using exact computations we study the classical hard-core monomer-dimer
models on m x n plane lattice strips with free boundaries. For an arbitrary
number v of monomers (or vacancies), we found a logarithmic correction term in
the finite-size correction of the free energy. The coefficient of the
logarithmic correction term depends on the number of monomers present (v) and
the parity of the width n of the lattice strip: the coefficient equals to v
when n is odd, and v/2 when n is even. The results are generalizations of the
previous results for a single monomer in an otherwise fully packed lattice of
dimers.Comment: 4 pages, 2 figure
Growth of High-Mobility Bi2Te2Se Nanoplatelets on hBN Sheets by van der Waals Epitaxy
The electrical detection of the surface states of topological insulators is
strongly impeded by the interference of bulk conduction, which commonly arises
due to pronounced doping associated with the formation of lattice defects. As
exemplified by the topological insulator Bi2Te2Se, we show that via van der
Waals epitaxial growth on thin hBN substrates the structural quality of such
nanoplatelets can be substantially improved. The surface state carrier mobility
of nanoplatelets on hBN is increased by a factor of about 3 compared to
platelets on conventional Si/SiOx substrates, which enables the observation of
well-developed Shubnikov-de Haas oscillations. We furthermore demonstrate the
possibility to effectively tune the Fermi level position in the films with the
aid of a back gate
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