Spatial dispersion in metamaterials based on three-dimensional arrays of spheres and disks

2015 ◽  
Author(s):  
Alexander V. Chebykin ◽  
Maxim A. Gorlach ◽  
Alexey A. Gorlach ◽  
Pavel A. Belov
Keyword(s):  
Spatial Dispersion ◽  
Three Dimensional ◽  
Arrays Of Spheres

scholarly journals Spatial dispersion management in three-dimensional drawn magnetic metamaterials

2012 ◽  
Author(s):  
Alessandro Tuniz ◽  
Benjamin Pope ◽  
Alexander Argyros ◽  
Simon Fleming ◽  
Anna Wang ◽  
...  
Keyword(s):  
Spatial Dispersion ◽  
Three Dimensional ◽  
Dispersion Management

Interplay between temporal and spatial dispersion of repolarization in the initiation and perpetuation of Torsades de Pointes in the chronic AV-block dog

2021 ◽  
Author(s):  
Agnieszka Smoczynska ◽  
Errol W. Aarnink ◽  
Albert Dunnink ◽  
Alexandre Bossu ◽  
Valerie Y.H. van Weperen ◽  
...  
Keyword(s):  
Ventricular Arrhythmias ◽  
Spatial Dispersion ◽  
Three Dimensional ◽  
Torsades De Pointes ◽  
Av Block ◽  
Dispersion Of Repolarization ◽  
Ectopic Beats ◽  
The Mean ◽  
Temporal And Spatial ◽  
Temporal Dispersion

Ventricular arrhythmias, consisting of single ectopic beats (sEB), multiple EB (mEB), and Torsades de Pointes (TdP, defined as >5 beats with QRS vector twisting around isoelectric line) can be induced in the anesthetized chronic AV-block (CAVB) dog by dofetilide (IKr-blocker). The interplay between temporal dispersion of repolarization, quantified as short-term variability (STV), and spatial dispersion of repolarization (SDR) in the initiation and perpetuation of these arrhythmias remains unclear. Five inducible (>3 TdPs/10') CAVB dogs were observed for 10' from the start of dofetilide infusion (0.025mg/kg, 5'). An intracardiac decapolar electrogram (EGM) catheter and 30 intramural cardiac needles in the left ventricle (LV) were introduced. STVARI was derived from 31 consecutive activation recovery intervals (ARI) on the intracardiac EGM, using the formula: . The mean SDR3D in the LV was determined as the three-dimensional repolarization time differences between the intramural cardiac needles. Moments of measurement included baseline (BL) and after dofetilide infusion prior to first 1) sEB (occurrence at 100±35"), 2) mEB (224±96"), and 3) non self-terminating TdP (454±298"). STVARI increased from 2.15±0.32ms at BL to 3.73±0.99ms* prior to the first sEB and remained increased without further significant progression to mEB (4.41±0.45ms*) and TdP (5.07±0.84ms*) (*p<0.05 compared to BL). SDR3D did not change from 31±11ms at BL to 43±13ms prior to sEB, but increased significantly prior to mEB (68±7ms*) and to TdP (86±9ms*+) (+p<0.05 compared to sEB). An increase in STV contributes to the initiation of sEB whereas an increase in SDR is important for the perpetuation of non self-terminating TdPs.

Spatial dispersion of interstellar civilizations: a probabilistic site percolation model in three dimensions

2012 ◽  
Vol 12 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Thomas W. Hair ◽  
Andrew D. Hedman
Keyword(s):  
Cellular Automaton ◽  
Uniform Distribution ◽  
Spatial Dispersion ◽  
Three Dimensional ◽  
Percolation Model ◽  
Three Dimensions ◽  
Site Percolation ◽  
Original Seed ◽  
Probabilistic Cellular Automaton

AbstractA model of the spatial emergence of an interstellar civilization into a uniform distribution of habitable systems is presented. The process of emigration is modelled as a three-dimensional probabilistic cellular automaton. An algorithm is presented which defines both the daughter colonies of the original seed vertex and all subsequent connected vertices, and the probability of a connection between any two vertices. The automaton is analysed over a wide set of parameters for iterations that represent up to 250 000 years within the model's assumptions. Emigration patterns are characterized and used to evaluate two hypotheses that aim to explain the Fermi Paradox. The first hypothesis states that interstellar emigration takes too long for any civilization to have yet come within a detectable distance, and the second states that large volumes of habitable space may be left uninhabited by an interstellar civilization and Earth is located in one of these voids.

scholarly journals Fabricating polyoxometalates-stabilized single-atom site catalysts in confined space with enhanced activity for alkynes diboration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yiwei Liu ◽  
Xi Wu ◽  
Zhi Li ◽  
Jian Zhang ◽  
Shu-Xia Liu ◽  
...  
Keyword(s):  
High Performance ◽  
Spatial Dispersion ◽  
Three Dimensional ◽  
Phosphomolybdic Acid ◽  
Single Atom ◽  
Confined Space ◽  
Organic Reaction ◽  
Metal Precursors ◽  
Square Planar ◽  
Metal Organic

AbstractEffecting the synergistic function of single metal atom sites and their supports is of great importance to achieve high-performance catalysts. Herein, we successfully fabricate polyoxometalates (POMs)-stabilized atomically dispersed platinum sites by employing three-dimensional metal-organic frameworks (MOFs) as the finite spatial skeleton to govern the accessible quantity, spatial dispersion, and mobility of metal precursors around each POM unit. The isolated single platinum atoms (Pt1) are steadily anchored in the square-planar sites on the surface of monodispersed Keggin-type phosphomolybdic acid (PMo) in the cavities of various MOFs, including MIL-101, HKUST-1, and ZIF-67. In contrast, either the absence of POMs or MOFs yielded only platinum nanoparticles. Pt1-PMo@MIL-101 are seven times more active than the corresponding nanoparticles in the diboration of phenylacetylene, which can be attributed to the synergistic effect of the preconcentration of organic reaction substrates by porous MOFs skeleton and the decreased desorption energy of products on isolated Pt atom sites.

Wave arrival singularities at cuspidal points in the acoustic wave surfaces of anisotropic solids and their unfolding under weak spatial dispersion

2007 ◽  
Vol 463 (2087) ◽  
pp. 2983-3000
Author(s):  
A.G Every ◽  
J.D Kaplunov ◽  
A.V Pichugin ◽  
G.A Rogerson
Keyword(s):  
Acoustic Wave ◽  
Green’S Function ◽  
Green's Function ◽  
Spatial Dispersion ◽  
Three Dimensional ◽  
Step Function ◽  
Two Dimensional ◽  
Displacement Response ◽  
Wave Surfaces ◽  
Wave Arrival

This paper is concerned with wave arrival singularities in the elastodynamic Green's functions of infinite anisotropic elastic solids, and their unfolding into smooth wave trains, known as quasi-arrivals, through spatial dispersion. The wave arrivals treated here are those occurring in (i) the displacement response to a suddenly applied point force or three-dimensional Green's function, , and (ii) the displacement response to an impulsive line force or two-dimensional Green's function, . These arrivals take on various analytical forms, including step function and logarithmic and power-law divergences. They travel outwards from the source at the group velocities in each direction, and their locus defines the three- and two-dimensional acoustic wave surfaces, respectively. The main focus of this paper is on the form of the wave arrivals in the neighbourhood of cuspidal points in the wave surfaces, and how these arrivals unfold into quasi-arrivals under the first onset of spatial dispersion. This regime of weak spatial dispersion, where the acoustic wavelength, λ , begins to approach the natural length scale, l , of the medium, is characterized by a correction to the phase velocity, which is quadratic in the wavevector, k , and the presence of fourth-order spatial derivatives of the displacement field in the wave equation. Integral expressions are established for the quasi-arrivals near to cuspidal points, involving the Airy function in the case of and the Scorer function in the case of . Numerical results are presented, illustrating the oscillatory nature of the quasi-arrivals and the interference effects that occur near to cuspidal points in the wave surface.

scholarly journals Quantification of 3D Brain Microangioarchitectures in an Animal Model of Krabbe Disease

2019 ◽  
Vol 20 (10) ◽  
pp. 2384 ◽  
Author(s):  
Marco Righi ◽  
Mirella Belleri ◽  
Marco Presta ◽  
Arianna Giacomini
Keyword(s):  
Cerebral Cortex ◽  
Spatial Dispersion ◽  
Three Dimensional ◽  
Krabbe Disease ◽  
3D Analysis ◽  
Wild Type ◽  
Microvascular Network ◽  
Microvascular Changes ◽  
Starting Point ◽  
The Central Nervous System

We performed a three-dimensional (3D) analysis of the microvascular network of the cerebral cortex of twitcher mice (an authentic model of Krabbe disease) using a restricted set of indexes that are able to describe the arrangement of the microvascular tree in CD31-stained sections. We obtained a near-linear graphical “fingerprint” of the microangioarchitecture of wild-type and twitcher animals that describes the amounts, spatial dispersion, and spatial relationships of adjacent classes of caliber-filtered microvessels. We observed significant alterations of the microangioarchitecture of the cerebral cortex of twitcher mice, whereas no alterations occur in renal microvessels, which is keeping with the observation that kidney is an organ that is not affected by the disease. This approach may represent an important starting point for the study of the microvascular changes that occur in the central nervous system (CNS) under different physiopathological conditions.

scholarly journals Spatial dispersion in three-dimensional drawn magnetic metamaterials

2012 ◽  
Vol 20 (11) ◽  
pp. 11924 ◽  
Author(s):  
Alessandro Tuniz ◽  
Benjamin Pope ◽  
Anna Wang ◽  
Maryanne C. J. Large ◽  
Shaghik Atakaramians ◽  
...  
Keyword(s):  
Spatial Dispersion ◽  
Three Dimensional

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

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