31,419 research outputs found
The Invariant Fields of the Sylow groups of Classical Groups in the natural characteristic
Let X be any finite classical group defined over a finite field of
characteristic p>0. In this paper we determine the fields of rational
invariants for the Sylow p-subgroups of X, acting on the natural module. In
particular we prove that these fields are generated by orbit products of
variables and certain invariant polynomials which are images under Steenrod
operations, applied to the respective invariant linear forms defining X.Comment: 33 page
Complete light absorption in graphene-metamaterial corrugated structures
We show that surface-plasmon polaritons excited in negative permittivity
metamaterials having shallow periodic surface corrugation profiles can be
explored to push the absorption of single and continuous sheets of graphene up
to 100%. In the relaxation regime, the position of the plasmonic resonances of
the hybrid system is determined by the plasma frequency of the metamaterial,
allowing the frequency range for enhanced absorption to be set without the need
of engineering graphene.Comment: 6 pages, 4 figures; published version: text revised and references
adde
Transition on the entropic elasticity of DNA induced by intercalating molecules
We use optical tweezers to perform stretching experiments on DNA molecules
when interacting with the drugs daunomycin and ethidium bromide, which
intercalate the DNA molecule. These experiments are performed in the low-force
regime from zero up to 2 pN. Our results show that the persistence length of
the DNA-drug complexes increases strongly as the drug concentration increases
up to some critical value. Above this critical value, the persistence length
decreases abruptly and remains practically constant for larger drug
concentrations. The contour length of the molecules increases monotonically and
saturates as drugs concentration increases. Measured in- tercalants critical
concentrations for the persistence length transition coincide with reported
values for the helix-coil transition of DNA-drug complexes, obtained from
sedimentation experiments.Comment: This experimental article shows and discuss a transition observed in
the persistence length of DNA molecules when studied as a function of some
intercalating drug concentrations, like daunomycin and ethidium bromide. It
has 15 pages and 4 figures. The article presented here is in preprint forma
Confined magneto-optical waves in graphene
The electromagnetic mode spectrum of single-layer graphene subjected to a
quantizing magnetic field is computed taking into account intraband and
interband contributions to the magneto-optical conductivity. We find that a
sequence of weakly decaying quasi-transverse-electric modes, separated by
magnetoplasmon polariton modes, emerge due to the quantizing magnetic field.
The characteristics of these modes are tuneable, by changing the magnetic field
or the Fermi energy.Comment: 9 pages, 7 figures. published version: text and figures revised and
updated + new references and one figure adde
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