FIBONACCI OPTICAL LATTICE: A FRACTAL BIOMODULATION DEVICE

Fractals ◽  
2019 ◽  
Vol 27 (03) ◽  
pp. 1950039 ◽  
Author(s):  
BENNY JOHANSSON ◽  
AGNES LUKACS
Keyword(s):  
Optical Lattice ◽  
Electromagnetic Waves ◽  
Incident Light ◽  
Natural Scenes ◽  
Scale Invariant ◽  
Scaling Properties ◽  
Self Assembling ◽  
Physiological Properties ◽  
Silica Clusters ◽  
Nanostructured Silica

Natural scenes or structures share fractal-like geometries with scale-invariant statistical patterns that exhibit useful functional physiological properties in humans. This paper explores the self-assembling of alumina microelements on a nanostructured silica-embedded PET substrate and the application of Fibonacci fractal geometry as a photonic wave-guiding device. Two concentric Fibonacci circles impinged on the top of embedded silica clusters were investigated using fractal analysis. Calculating the fractal dimension of spatial scaling properties demonstrated the potential of a fractal photonic element. Simulating the propagation of spectral visible or low NIR incident light through the fractal trajectory shows that the fractal scaling properties generate novel nonlinear and double-twisted electromagnetic waves with biophilic interconnecting potential.

scholarly journals Scale invariant events and dry spells for medium-resolution local rain data

2014 ◽  
Vol 21 (2) ◽  
pp. 555-567 ◽  
Author(s):  
A. Deluca ◽  
Á. Corral
Keyword(s):  
Finite Size ◽  
Mediterranean Coast ◽  
Rain Event ◽  
Scale Invariant ◽  
Scaling Properties ◽  
Medium Resolution ◽  
Dry Spells ◽  
Dry Spell ◽  
Rain Events ◽  
Rain Data

Abstract. We analyze distributions of rain-event sizes, rain-event durations, and dry-spell durations for data obtained from a network of 20 rain gauges scattered in a region of the northwestern Mediterranean coast. While power-law distributions model the dry-spell durations with a common exponent 1.50 ± 0.05, density analysis is inconclusive for event sizes and event durations, due to finite size effects. However, we present alternative evidence of the existence of scale invariance in these distributions by means of different data collapses of the distributions. These results demonstrate that scaling properties of rain events and dry spells can also be observed for medium-resolution rain data.

scholarly journals A Thermal Tuning Meta-Duplex-Lens (MDL): Design and Characterization

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1135 ◽  
Author(s):  
Ning Xu ◽  
Yaoyao Liang ◽  
Yuan Hao ◽  
Min Mao ◽  
Jianping Guo ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Electromagnetic Waves ◽  
Incident Light ◽  
Polarization State ◽  
Transmission Efficiency ◽  
Metallic State ◽  
Phase Gradient ◽  
Storage Devices ◽  
Change Material

Multifunctional metasurfaces play an important role in the development of integrated optical paths. However, some of the realizations of current multifunctional metasurface devices depend on polarization selectivity, and others change the polarization state of the outgoing light. Here, based on vanadium dioxide (VO2) phase change material, a strategy to design a meta-duplex-lens (MDL) is proposed and numerical simulation calculations demonstrate that at low temperature (about 300 K), VO2 behaves as a dielectric so that the MDL can act as a transmission lens (transmission efficiency of 87.6%). Conversely, when VO2 enters the metallic state (about 355 K), the MDL has the ability to reflect and polymerize electromagnetic waves and works as a reflection lens (reflection efficiency of 85.1%). The dielectric waveguide and gap-surface plasmon (GSP) theories are used in transmission and reflection directions, respectively. In order to satisfy the coverage of the phase gradient in the range of 2π in both cases, we set the antenna as a nanopillar with a high aspect ratio. It is notable that, via symmetrical antennas acting in concert with VO2 phase change material, the polarization states of both the incident light and the outgoing light are not changed. This reversible tuning will play a significant role in the fields of imaging, optical storage devices, communication, sensors, etc.

Natural scenes have matched amplitude-modulated sounds that systematically influence visual scanning

2012 ◽  
Vol 25 (0) ◽  
pp. 121
Author(s):  
Marcia Grabowecky ◽  
Aleksandra Sherman ◽  
Satoru Suzuki
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Memory Task ◽  
High Spatial Frequency ◽  
Visual Object ◽  
Natural Scenes ◽  
Scale Invariant ◽  
Visual Coding ◽  
Visual Spatial ◽  
Spatial Frequencies

We have previously demonstrated a linear perceptual relationship between auditory amplitude-modulation (AM) rate and visual spatial-frequency using gabors as the visual stimuli. Can this frequency-based auditory–visual association influence perception of natural scenes? Participants consistently matched specific auditory AM rates to diverse visual scenes (nature, urban, and indoor). A correlation analysis indicated that higher subjective density ratings were associated with faster AM-rate matches. Furthermore, both the density ratings and AM-rate matches were relatively scale invariant, suggesting that the underlying crossmodal association is between visual coding of object-based density and auditory coding of AM rate. Based on these results, we hypothesized that concurrently presented fast (7 Hz) or slow (2 Hz) AM-rates might influence how visual attention is allocated to dense or sparse regions within a scene. We tested this hypothesis by monitoring eye movements while participants examined scenes for a subsequent memory task. To determine whether fast or slow sounds guided eye movements to specific spatial frequencies, we computed the maximum contrast energy at each fixation across 12 spatial frequency bands ranging from 0.06–10.16 cycles/degree. We found that the fast sound significantly guided eye movements toward regions of high spatial frequency, whereas the slow sound guided eye movements away from regions of high spatial frequency. This suggests that faster sounds may promote a local scene scanning strategy, acting as a ‘filter’ to individuate objects within dense regions. Our results suggest that auditory AM rate and visual object density are crossmodally associated, and that this association can modulate visual inspection of scenes.

THE MULTIFRACTAL SCALING OF CLOUD RADIANCES FROM 1M TO 1KM

Fractals ◽  
2002 ◽  
Vol 10 (03) ◽  
pp. 253-264 ◽  
Author(s):  
D. SACHS ◽  
S. LOVEJOY ◽  
D. SCHERTZER
Keyword(s):  
Entire Range ◽  
Atmospheric Dynamics ◽  
Wave Number ◽  
Two Dimensional ◽  
Scale Invariant ◽  
Spectral Exponent ◽  
Scaling Properties ◽  
Anisotropic Scaling ◽  
Multifractal Scaling ◽  
Cloud Thickness

The cloud radiances and atmospheric dynamics are strongly nonlinearly coupled, the observed scaling of the former from 1 km to planetary scales is prima facae evidence for scale invariant dynamics. In contrast, the scaling properties of radiances at scales <1 km have not been well studied (contradictory claims have been made) and if a characteristic vertical cloud thickness existed, it could break the scaling of the horizontal radiances. In order to settle this issue, we use ground-based photography to study the cloud radiance field through the range scales where breaks in scaling have been reported (30 m to 500 m). Over the entire range 1 m to 1 km the two-dimensional (2D) energy spectrum (E(k)) of 38 clouds was found to accurately follow the scaling form E(k)≈ k-β where k is a wave number and β is the spectral exponent. This indirectly shows that there is no characteristic vertical cloud thickness, and that "radiative smoothing" of cloud structures occurs at all scales. We also quantitatively characterize the type of (multifractal) scaling showing that the main difference between transmitted and reflected radiance fields is the (scale-by-scale) non-conservation parameter H. These findings lend support to the unified scaling model of the atmosphere which postulates a single anisotropic scaling regime from planetary down to dissipation scales.

scholarly journals Study on the Plasmonic Properties of Ag-Coated Spherical Dielectric Nanoparticles by Finite-Difference Time-Domain Calculations

2021 ◽  
Author(s):  
Qing-Wei Sun ◽  
Qi Sun ◽  
Qing-Yu Zhang ◽  
Nan Zhou ◽  
Xi-Na Li
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Electromagnetic Waves ◽  
Incident Light ◽  
Plasmonic Resonance ◽  
Ag Nps ◽  
Zno Nps ◽  
Infrared Band ◽  
Difference Time

Abstract The optical properties of nanostructures are rather important for designing plasmonic devices. In this work, the plasmonic properties of Ag-coated spherical dielectric nanoparticles (NPs), namely, Ag-SiO2-NPs, Ag-ZnO-NPs, and Ag-TiO2-NPs, were studied using a method of finite-difference time-domain calculations. It was found that the Ag-coated dielectric NPs start to exhibit unique plasmonic properties different from Ag-NPs as the thickness of Ag shells is reduced to be less than a critical value, which is basically determined by the penetration depth of light in silver. On the other hand, the core-shell structures of Ag-coated dielectric NPs were found to be of benefit to the plasmonic resonance high-efficiently coupled with the incident light. In the extinction spectra of Ag-coated dielectric NPs with sufficient thin Ag shells, the dipole plasmonic resonance is predominant and exhibits a pronounced red-shift up to infrared band with increasing the NP sizes. In addition to the electromagnetic waves of emission towards the outside, the electromagnetic field in the dielectric NP inside is uniformly enhanced as well and both of dipole and quadrupole plasmonic resonances are identified. The Ag-coated dielectric NPs are suggested to have great potential in the plasmonic devices working in infrared band, such as the light emitters and SERS substrates for biosensing.

A regional scale invariant depth-duration-frequency model for sub-hourly extreme rainfall estimation in Sicily

2020 ◽  
Author(s):  
Brunella Bonaccorso ◽  
Giuseppina Brigandì ◽  
Giuseppe Tito Aronica
Keyword(s):  
Risk Assessment ◽  
Regional Scale ◽  
Extreme Rainfall ◽  
Scaling Exponent ◽  
Scale Invariant ◽  
Frequency Model ◽  
Scaling Properties ◽  
Rain Gauges ◽  
Simple Scaling ◽  
Idf Curves

&lt;p&gt;Depth (or intensity)-duration-frequency (DDF or IDF) curves are commonly applied in hydrology to derive storms of fixed duration and return period for hydraulic infrastructures design and risk assessment. Usually, annual maxima rainfall (AMR) data from 1 to 24-hour duration are used to develop DDF or IDF curves. However, design of urban drainage systems or flood risk assessment in small catchments often requires knowledge of very short-duration rainfall events (less than 1 hour), whose data are often unavailable or too scarce for estimating reliable quantile values. Regularities in the temporal pattern exhibited by storm records, known as scaling properties, could help in characterizing extreme storms at partially gauged sites better than the application of traditional statistical techniques. In this work, a scaling approach for estimating the distribution of sub-hourly extreme rainfall in Sicily (Italy) is presented based on data from high-resolution rain gauges with a short functioning period and from low-resolution rain gauges with longer samples. First, simple scaling assumption versus multiple scaling one is verified for annual maxima rainfall (AMR) data from 10 minute to 24-hour duration, revealing that the simple scaling regime holds from 20 to 60 minutes for most of the stations. Three scaling homogeneous regions are classified based on the scaling exponent values. In each region, this parameter is regionalized by means of power law relationships with the maximum 1 hour AMR data. Then, regional DDF curves are developed by combining the scale-invariant framework with the generalized extreme value (GEV) probability distribution, in order to estimate T-year sub-hourly extreme rainfalls at sites where only rainfall data for longer durations (&amp;#8805; 1 hour) are available. The regional GEV simple scaling DDF model is validated against sub-hourly historical observations at five rain gauges. Results indicate that the proposed model provides reliable sub-hourly estimates.&lt;/p&gt;

scholarly journals Scaling in Quantum Transport in Silicon Nano-Transistors

2009 ◽  
Vol 156-158 ◽  
pp. 517-521 ◽  
Author(s):  
Ulrich Wulf ◽  
Hans Richter
Keyword(s):  
Quantum Transport ◽  
Characteristic Length ◽  
Field Effect Transistors ◽  
Effective Theory ◽  
Control Parameters ◽  
Scale Invariant ◽  
Electron Channel ◽  
Scaling Properties ◽  
Starting Point ◽  
Long Channel

We develop a theory for scaling properties of quantum transport in nano-field effect transistors. Our starting point is a one-dimensional effective expression for the drain current in the Landauer-Büttiker formalism. Assuming a relatively simple total potential acting on the electrons the effective theory can be reduced to a scale-invariant form yielding a set of dimensionless control parameters. Among these control parameters are the characteristic length l and -width w of the electron channel which are its physical length and -width in units of the scaling length . Here is the Fermi energy in the source contact and is the effective mass in the electron channel. In the limit of wide transistors and low temperatures we evaluate the scale-invariant i-v characteristics as a function of the characteristic length. In the strong barrier regime, i. e. for long-channel behavior is found. At weaker barriers source-drain tunneling leads to increasingly significant deviations from the long-channel behavior.

scholarly journals ASYMPTOTIC SCALING SYMMETRIES FOR NONLINEAR PDES

2005 ◽  
Vol 02 (06) ◽  
pp. 1081-1114 ◽  
Author(s):  
GIUSEPPE GAETA ◽  
ROSARIA MANCINELLI
Keyword(s):  
Anomalous Diffusion ◽  
Reaction Diffusion ◽  
Reaction Diffusion Equations ◽  
Diffusion Equations ◽  
Nonlinear Pdes ◽  
Scale Invariant ◽  
Geometrical Meaning ◽  
Scaling Properties ◽  
Symmetries Of Differential Equations ◽  
Asymptotic Scaling

In some cases, solutions to nonlinear PDEs happen to be asymptotically (for large x and/or t) invariant under a group G which is not a symmetry of the equation. After recalling the geometrical meaning of symmetries of differential equations — and solution-preserving maps — we provide a precise definition of asymptotic symmetries of PDEs; we deal in particular, for ease of discussion and physical relevance, with scaling and translation symmetries of scalar equations. We apply the general discussion to a class of "Richardson-like" anomalous diffusion and reaction-diffusion equations, whose solution are known by numerical experiments to be asymptotically scale invariant; we obtain an analytical explanation of the numerically observed asymptotic scaling properties. We also apply our method to a different class of anomalous diffusion equations, relevant in optical lattices. The methods developed here can be applied to more general equations, as shown by their geometrical construction.

Spatial Scale Interactions and Image Statistics

Perception ◽  
1997 ◽  
Vol 26 (9) ◽  
pp. 1089-1100 ◽  
Author(s):  
Nuala Brady
Keyword(s):  
Visual System ◽  
Spatial Scale ◽  
Visual Processing ◽  
Spatial Scales ◽  
Power Spectra ◽  
Visual Image ◽  
Natural Scenes ◽  
Sources Of Information ◽  
Scale Invariant ◽  
Scale Interactions

In natural scenes and other broadband images, spatial variations in luminance occur at a range of scales or frequencies. It is generally agreed that the visual image is initially represented by the activity of separate frequency-tuned channels, and this notion is supported by physiological evidence for a stage of multi-resolution filtering in early visual processing. The question whether these channels can be accessed as independent sources of information in the normal course of events is a more contentious one. In the psychophysical study of both motion and spatial vision, there are examples of tasks in which fine-scale structure dominates perception or performance and obscures information at coarser scales. It is argued here that one important factor determining the relative salience of information from different spatial scales in broadband images is the distribution of response activity across spatial channels. The special case of natural scenes that have characteristic ‘scale-invariant’ power spectra in which image contrast is roughly constant in equal octave frequency bands is considered. A review is presented of evidence which suggests that the sensitivity of frequency-tuned filters in the visual system is matched to this image statistic, so that, on average, different channels respond with equal activity to natural scenes. Under these conditions, the visual system does appear to have independent access to information at different spatial scales and spatial scale interactions are not apparent.

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