scholarly journals Phosphorescence and electron traps II. The interpretation of long-period phosphorescence

1945 ◽  
Vol 184 (999) ◽  
pp. 390-407 ◽  
Keyword(s):  
Power Law ◽  
Alkaline Earth ◽  
Decay Curve ◽  
Zinc Sulphide ◽  
Electron Multiplier ◽  
Long Period ◽  
Detailed Explanation ◽  
Inverse Power Law ◽  
Quantitative Basis ◽  
Exponential Trap Distribution

This paper is concerned with the measurement and theory of long-period phosphorescence in solids. The delayed emission is, in such cases, due to the time electrons spend in traps or metastable states before returning to the luminescence centres. The theory shows how the observed decay laws are related to the trap distributions found in Paper I. In alkaline earth phosphors there are equal numbers of traps at all depths over the range considered, and the expression developed shows that the intensity of phosphorescence should be inversely proportional to time. For zinc sulphide phosphors an exponential trap distribution has been found, and this leads to a simple inverse power law for the theoretical decay curve. Measurements of decay on these phosphors utilizing an electron multiplier have confirmed the theory, and put on a quantitative basis the connexion between thermoluminescence and long-period decay. At the same time the work provides the first satisfactory and detailed explanation of longperiod decays. The extent -to which retrapping of electrons modifies the picture given is discussed.

Inverse Power Law Behavior in a Memory Scanning Experiment

2006 ◽  
Author(s):  
Gerardo Ramirez ◽  
Sonia Perez ◽  
John G. Holden
Keyword(s):  
Power Law ◽  
Inverse Power ◽  
Memory Scanning ◽  
Inverse Power Law

scholarly journals Inverse-power-law behavior of cellular motility reveals stromal–epithelial cell interactions in 3D co-culture by OCT fluctuation spectroscopy

Optica ◽  
2015 ◽  
Vol 2 (10) ◽  
pp. 877 ◽  
Author(s):  
Amy L. Oldenburg ◽  
Xiao Yu ◽  
Thomas Gilliss ◽  
Oluwafemi Alabi ◽  
Russell M. Taylor ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Power Law ◽  
Cell Interactions ◽  
Inverse Power ◽  
Cellular Motility ◽  
Inverse Power Law

Anomalies in Strongly Coupled Harmonic Quantum Brownian Motion

2013 ◽  
Vol 20 (01) ◽  
pp. 1350002 ◽  
Author(s):  
F. Giraldi ◽  
F. Petruccione
Keyword(s):  
Time Evolution ◽  
Power Law ◽  
Weak Coupling ◽  
Inverse Power ◽  
Strong Coupling Regime ◽  
Weak Coupling Regime ◽  
Spectral Densities ◽  
Inverse Power Law ◽  
Critical Configurations ◽  
Long Time

The exact dynamics of a quantum damped harmonic oscillator coupled to a reservoir of boson modes has been formally described in terms of the coupling function, both in weak and strong coupling regime. In this scenario, we provide a further description of the exact dynamics through integral transforms. We focus on a special class of spectral densities, sub-ohmic at low frequencies, and including integrable divergencies referred to as photonic band gaps. The Drude form of the spectral densities is recovered as upper limit. Starting from special distributions of coherent states as external reservoir, the exact time evolution, described through Fox H-functions, shows long time inverse power law decays, departing from the exponential-like relaxations obtained for the Drude model. Different from the weak coupling regime, in the sub-ohmic condition, undamped oscillations plus inverse power law relaxations appear in the long time evolution of the observables position and momentum. Under the same condition, the number of excitations shows trapping of the population of the excited levels and oscillations enveloped in inverse power law relaxations. Similarly to the weak coupling regime, critical configurations give arbitrarily slow relaxations useful for the control of the dynamics. If compared to the value obtained in weak coupling condition, for strong couplings the critical frequency is enhanced by a factor 4.

scholarly journals SCALE-FREE UNIVERSAL SPECTRUM FOR ATMOSPHERIC AEROSOL SIZE DISTRIBUTION FOR DAVOS, MAUNA LOA AND IZANA

2013 ◽  
Vol 23 (02) ◽  
pp. 1350028 ◽  
Author(s):  
A. M. SELVAM
Keyword(s):  
Size Distribution ◽  
Power Law ◽  
Aerosol Size Distribution ◽  
Scale Free ◽  
Mauna Loa ◽  
Atmospheric Particulates ◽  
Inverse Power Law ◽  
Universal Scale ◽  
Radius Size ◽  
Fractal Fluctuations

Atmospheric flows exhibit fractal fluctuations and inverse power law for power spectra indicates an eddy continuum structure for the self-similar fluctuations. A general systems theory for aerosol size distribution based on fractal fluctuations is proposed. The model predicts universal (scale-free) inverse power law for fractal fluctuations expressed in terms of the golden mean. Atmospheric particulates are held in suspension in the fractal fluctuations of vertical wind velocity. The mass or radius (size) distribution for homogeneous suspended atmospheric particulates is expressed as a universal scale-independent function of the golden mean, the total number concentration and the mean volume radius. Model predicted spectrum is compared with the total averaged radius size spectra for the AERONET (aerosol inversions) stations Davos and Mauna Loa for the year 2010 and Izana for the year 2009. There is close agreement between the model predicted and the observed aerosol spectra. The proposed model for universal aerosol size spectrum will have applications in computations of radiation balance of earth–atmosphere system in climate models.

scholarly journals Modeling Epidemics in Seed Systems and Landscapes To Guide Management Strategies: The Case of Sweet Potato in Northern Uganda

2019 ◽  
Vol 109 (9) ◽  
pp. 1519-1532 ◽  
Author(s):  
K. F. Andersen ◽  
C. E. Buddenhagen ◽  
P. Rachkara ◽  
R. Gibson ◽  
S. Kalule ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Power Law ◽  
Inverse Power ◽  
Centrality Measures ◽  
Northern Uganda ◽  
Seed Systems ◽  
Negative Exponential Function ◽  
Improved Varieties ◽  
Inverse Power Law ◽  
Negative Exponential

Seed systems are critical for deployment of improved varieties but also can serve as major conduits for the spread of seedborne pathogens. As in many other epidemic systems, epidemic risk in seed systems often depends on the structure of networks of trade, social interactions, and landscape connectivity. In a case study, we evaluated the structure of an informal sweet potato seed system in the Gulu region of northern Uganda for its vulnerability to the spread of emerging epidemics and its utility for disseminating improved varieties. Seed transaction data were collected by surveying vine sellers weekly during the 2014 growing season. We combined data from these observed seed transactions with estimated dispersal risk based on village-to-village proximity to create a multilayer network or “supranetwork.” Both the inverse power law function and negative exponential function, common models for dispersal kernels, were evaluated in a sensitivity analysis/uncertainty quantification across a range of parameters chosen to represent spread based on proximity in the landscape. In a set of simulation experiments, we modeled the introduction of a novel pathogen and evaluated the influence of spread parameters on the selection of villages for surveillance and management. We found that the starting position in the network was critical for epidemic progress and final epidemic outcomes, largely driven by node out-degree. The efficacy of node centrality measures was evaluated for utility in identifying villages in the network to manage and limit disease spread. Node degree often performed as well as other, more complicated centrality measures for the networks where village-to-village spread was modeled by the inverse power law, whereas betweenness centrality was often more effective for negative exponential dispersal. This analysis framework can be applied to provide recommendations for a wide variety of seed systems.[Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Inverse-Power-Law Light Scattering in Fused-Silica Optical Fiber

1988 ◽  
Vol 61 (12) ◽  
pp. 1388-1391 ◽  
Author(s):  
S. H. Perlmutter ◽  
M. D. Levenson ◽  
R. M. Shelby ◽  
M. B. Weissman
Keyword(s):  
Light Scattering ◽  
Optical Fiber ◽  
Power Law ◽  
Fused Silica ◽  
Inverse Power ◽  
Inverse Power Law ◽  
Silica Optical Fiber

On braneworld inverse power-law inflation

2018 ◽  
Vol 33 (10) ◽  
pp. 1850058 ◽  
Author(s):  
H. Es-sobbahi ◽  
M. Nach
Keyword(s):  
Observational Data ◽  
Power Law ◽  
Equations Of Motion ◽  
High Energy ◽  
Type Ii ◽  
Scalar Model ◽  
Slow Roll ◽  
Inverse Power Law ◽  
Perturbation Spectrum ◽  
High Energy Regime

In the framework of the braneworld Randall–Sundrum type II model, we investigate an inflationary scalar model in the high-energy regime. In this regime, the slow-roll parameters and the perturbation spectrum of the model are derived. The corresponding results are dealt with according to the known observational data. Then the solutions to the equations of motion on the brane are given.

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