973 research outputs found
Quantum spill out in few-nanometer metal gaps: Effect on gap plasmons and reflectance from ultrasharp groove arrays
Plasmons in ultranarrow metal gaps are highly sensitive to the electron
density profile at the metal surfaces. Using a fully quantum mechanical
approach, we study the effects of electron spill-out on gap plasmons and
reflectance from ultrasharp metal grooves. We demonstrate that the mode index
of ultranarrow gap plasmons converges to the bulk refractive index in the limit
of vanishing gap and, thereby, rectify the unphysical divergence found in
classical models. Surprisingly, spill-out also significantly increases the
plasmonic absorption for few-nanometer gaps and lowers the reflectance from
arrays of ultrasharp metal grooves. These findings are explained in terms of
enhanced gap plasmon absorption taking place inside the gap 1-2 {\AA} from the
walls and delocalization near the groove bottom. Reflectance calculations
taking spill-out into account are shown to be in much better agreement with
measurements compared with classical models
Quantum spill-out in nanometer-thin gold slabs: Effect on plasmon mode index and plasmonic absorption
A quantum mechanical approach and local response theory are applied to study
plasmons propagating in nanometer-thin gold slabs sandwiched between different
dielectrics. The metal slab supports two different kinds of modes, classified
as long-range and short-range plasmons. Quantum spill-out is found to
significantly increase the imaginary part of their mode indices, and,
surprisingly, even for slabs wide enough to approach bulk the increase is 20%.
This is explained in terms of enhanced plasmonic absorption, which mainly takes
place at narrow peaks located near the slab surface
Cross sector and interdisciplinary cooperation in brain injury rehabilitation:Introducing an Organization Education approach
What enhances bio-psycho-social outcome in brain injury rehabilitation? Towards a predicting model
Trace formula for noise corrections to trace formulas
We consider an evolution operator for a discrete Langevin equation with a
strongly hyperbolic classical dynamics and Gaussian noise. Using an integral
representation of the evolution operator we investigate the high order
corrections to the trace of arbitary power of the operator.
The asymptotic behaviour is found to be controlled by sub-dominant saddle
points previously neglected in the perturbative expansion. We show that a trace
formula can be derived to describe the high order noise corrections.Comment: 4 pages, 2 figure
Practical design of a nonlinear tuned vibration absorber
The aim of the paper is to develop a new nonlinear tuned vibration absorber (NLTVA) capable of mitigating the vibrations of nonlinear systems which are known to exhibit frequency-energy-dependent oscillations. A nonlinear generalization of Den Hartog’s equal-peak method is proposed to ensure equal peaks in the nonlinear frequency response for a large range of forcing amplitudes. An analytical tuning procedure is developed and provides the load-deflection characteristic of the NLTVA. Based on this prescribed relation, the NLTVA design is performed by two different approaches, namely thanks to (i) analytical formulas of uniform cantilever and doubly-clamped beams and (ii) numerical shape optimization of beams with varying width and thickness. A primary system composed of a cantilever beam with a geometrically nonlinear component at its free end serves to illustrate the proposed methodology.ERC Starting Grant NoVib 307265; ERC Starting Grant INNODY
Effects of trophic status, water level, and temperature on shallow lake metabolism and metabolic balance: A standardized pan‐European mesocosm experiment
Important drivers of gross primary production (GPP) and ecosystem respiration (ER) in lakes are temperature, nutrients, and light availability, which are predicted to be affected by climate change. Little is known about how these three factors jointly influence shallow lakes metabolism and metabolic status as net heterotrophic or autotrophic. We conducted a pan‐European standardized mesocosm experiment covering a temperature gradient from Sweden to Greece to test the differential temperature sensitivity of GPP and ER at two nutrient levels (mesotrophic or eutrophic) crossed with two water levels (1 m and 2 m) to simulate different light regimes. The findings from our experiment were compared with predictions made according the metabolic theory of ecology (MTE). GPP and ER were significantly higher in eutrophic mesocosms than in mesotrophic ones, and in shallow mesocosms compared to deep ones, while nutrient status and depth did not interact. The estimated temperature gains for ER of ~ 0.62 eV were comparable with those predicted by MTE. Temperature sensitivity for GPP was slightly higher than expected ~ 0.54 eV, but when corrected for daylight length, it was more consistent with predictions from MTE ~ 0.31 eV. The threshold temperature for the switch from autotrophy to heterotrophy was lower under mesotrophic (~ 11°C) than eutrophic conditions (~ 20°C). Therefore, despite a lack of significant temperature‐treatment interactions in driving metabolism, the mesocosm's nutrient level proved to be crucial for how much warming a system can tolerate before it switches from net autotrophy to net heterotrophy
LigpKa – a database of pKa values for small molecule ligands designed for the use in structure-based pKa calculations
Finite-Difference Time-Domain Simulation of Strong-Field Ionization:A Perfectly Matched Layer Approach
A Finite-Difference Time-Domain (FDTD) scheme with Perfectly Matched Layers
(PMLs) is considered for solving the time-dependent Schr\"{o}dinger equation,
and simulate the ionization of an electron initially bound to a one-dimensional
-potential, when applying a strong time-oscillating electric field. The
performance of PMLs based on different absorption functions are compared, where
we find slowly growing functions to be preferable. PMLs are shown to be able to
reduce the computational domain, and thus the required numerical resources, by
several orders of magnitude. This is demonstrated by testing the proposed
method against an FDTD approach without PMLs and a very large computational
domain. We further show that PMLs outperform the well known Exterior Complex
Scaling (ECS) technique for short-range potentials when implemented in FDTD,
though ECS remains superior for long-range potentials. The accuracy of the
method is furthermore demonstrated by comparing with known numerical and
analytical results for the -potential
Dynamical energy analysis on mesh grids: a new tool for describing the vibro-acoustic response of complex mechanical structures
We present a new approach for modelling noise and vibration in complex mechanical structures in the mid-to-high frequency regime. It is based on a dynamical energy analysis (DEA) formulation which extends standard techniques such as statistical energy analysis (SEA) towards non-diffusive wave fields. DEA takes into account the full directionality of the wave field and makes sub-structuring obsolete. It can thus be implemented on mesh grids commonly used, for example, in the finite element method (FEM). The resulting mesh based formulation of DEA can be implemented very efficiently using discrete flow mapping (DFM) as detailed in [1] and described here for applications in vibro-acoustics
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