1,534 research outputs found
Nonlinear Elasticity of Single Collapsed Polyelectrolytes
Nonlinear elastic responses of short and stiff polyelectrolytes are
investigated by dynamic simulations on a single molecule level. When a
polyelectrolyte condensate undergoes a mechanical unfolding, two types of
force-extension curves, i.e., a force plateau and a stick-release pattern, are
observed depending on the strength of the electrostatic interaction. We provide
a physical interpretation of such force-extension behavior in terms of
intramolecular structures of the condensates. We also describe a charge
distribution of condensed counterions onto a highly stretched polyelectrolyte,
which clarifies a formation of one-dimensional strongly correlated liquid at
large Coulomb coupling regime where a stick-release pattern is observed. These
findings may provide significant insights into the relationship between a
molecular elasticity and a molecular mechanism of like-charge attractions
observed in a wide range of charged biopolymer systems.Comment: 5pages, 5figure
Tunable plasmonic luminescence in reconfigurable metamaterials
We show that new intense luminescence lines associated with transitions from collective plasmonic states below the Fermi level can be artificially created by metamaterial nanostructuring of plasmonic metals and tuned by nanoscale reconfiguration of metamaterial. We report on the experimental demonstration of a new radiation phenomenon on the nanoscale and its engineering into a reconfigurable metadevice: luminescence emission lines within the Fermi sea can be created by nanopatterning metal surfaces and controlled by external electrical inputs. Luminescence emission lines are associated with the decay of plasmonic excitation and are spectrally linked to the plasmonic absorption lines. Wavelength, polarization and intensity of metallic luminescence can be flexibly and independently adjusted by tweaking the geometric parameters of the metamaterial design similar to the way nanostructuring helps engineering semiconductor multiple quantum well and quantum dot luminescence
Validation of the EORTC QLQ-GINET21 questionnaire for assessing quality of life of patients with gastrointestinal neuroendocrine tumours
Background:Quality of life is an important end point in clinical trials, yet there are few quality of life questionnaires for neuroendocrine tumours.Methods:This international multicentre validation study assesses the QLQ-GINET21 Quality of Life Questionnaire in 253 patients with gastrointestinal neuroendocrine tumours. All patients were requested to complete two quality of life questionnaires - the EORTC Core Quality of Life questionnaire (QLQ-C30) and the QLQ-GINET21 - at baseline, and at 3 and 6 months post-baseline; the psychometric properties of the questionnaire were then analysed.Results:Analysis of QLQ-GINET21 scales confirmed appropriate aggregation of the items, except for treatment-related symptoms, where weight gain showed low correlation with other questions in the scale; weight gain was therefore analysed as a single item. Internal consistency of scales using Cronbach's α coefficient was >0.7 for all parts of the QLQ-GINET21 at 6 months. Intraclass correlation was >0.85 for all scales. Discriminant validity was confirmed, with values <0.70 for all scales compared with each other.Scores changed in accordance with alterations in performance status and in response to expected clinical changes after therapies. Mean scores were similar for pancreatic and other tumours.Conclusion:The QLQ-GINET21 is a valid and responsive tool for assessing quality of life in the gut, pancreas and liver neuroendocrine tumours
Surface Gap Soliton Ground States for the Nonlinear Schr\"{o}dinger Equation
We consider the nonlinear Schr\"{o}dinger equation , with and and with periodic in each coordinate direction. This problem
describes the interface of two periodic media, e.g. photonic crystals. We study
the existence of ground state solutions (surface gap soliton ground
states) for . Using a concentration compactness
argument, we provide an abstract criterion for the existence based on ground
state energies of each periodic problem (with and ) as well as a more practical
criterion based on ground states themselves. Examples of interfaces satisfying
these criteria are provided. In 1D it is shown that, surprisingly, the criteria
can be reduced to conditions on the linear Bloch waves of the operators
and .Comment: definition of ground and bound states added, assumption (H2) weakened
(sign changing nonlinearity is now allowed); 33 pages, 4 figure
Plasmonic nanoparticle monomers and dimers: From nano-antennas to chiral metamaterials
We review the basic physics behind light interaction with plasmonic
nanoparticles. The theoretical foundations of light scattering on one metallic
particle (a plasmonic monomer) and two interacting particles (a plasmonic
dimer) are systematically investigated. Expressions for effective particle
susceptibility (polarizability) are derived, and applications of these results
to plasmonic nanoantennas are outlined. In the long-wavelength limit, the
effective macroscopic parameters of an array of plasmonic dimers are
calculated. These parameters are attributable to an effective medium
corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial
where plasmonic monomers or dimers have the function of "meta-atoms". It is
shown that planar dimers consisting of rod-like particles generally possess
elliptical dichroism and function as atoms for planar chiral metamaterials. The
fabricational simplicity of the proposed rod-dimer geometry can be used in the
design of more cost-effective chiral metamaterials in the optical domain.Comment: submitted to Appl. Phys.
Past Achievements and Future Challenges in 3D Photonic Metamaterials
Photonic metamaterials are man-made structures composed of tailored micro- or
nanostructured metallo-dielectric sub-wavelength building blocks that are
densely packed into an effective material. This deceptively simple, yet
powerful, truly revolutionary concept allows for achieving novel, unusual, and
sometimes even unheard-of optical properties, such as magnetism at optical
frequencies, negative refractive indices, large positive refractive indices,
zero reflection via impedance matching, perfect absorption, giant circular
dichroism, or enhanced nonlinear optical properties. Possible applications of
metamaterials comprise ultrahigh-resolution imaging systems, compact
polarization optics, and cloaking devices. This review describes the
experimental progress recently made fabricating three-dimensional metamaterial
structures and discusses some remaining future challenges
- …