A bibliometric study in crystallography

2006 ◽  
Vol 62 (6) ◽  
pp. 993-1001 ◽  
Author(s):  
Heinrich Behrens ◽  
Peter Luksch
Keyword(s):  
Power Law ◽  
Inorganic Compounds ◽  
Inverse Power ◽  
Inorganic Crystal Structure Database ◽  
The Past ◽  
Relational Database System ◽  
Inorganic Crystal ◽  
Inverse Power Law ◽  
Author Productivity ◽  
Crystal Structure Database

This is an application of the mathematical and statistical techniques of bibliometrics to the field of crystallography. This study is, however, restricted to inorganic compounds. The data were taken from the Inorganic Crystal Structure Database, which is a well defined and evaluated body of literature and data published from 1913 to date. The data were loaded in a relational database system, which allows a widespread analysis. The following results were obtained: The cumulative growth rate of the number of experimentally determined crystal structures is best described by a third-degree polynomial function. Except for the upper end of the curve, Bradford's plot can be described well by the analytical Leimkuhler function. The publication process is dominated by a small number of periodicals. The probability of the author productivity in terms of publications follows an inverse power law of the Lotka form and in terms of database entries an inverse power law in the Mandelbrot form. In both cases the exponent is about 1.7. For the lower tail of the data an exponential correction factor has to be applied. Multiple authorship has increased from 1.4 authors per publication to about four within the past eight decades. The author distribution itself is represented by a lognormal distribution.

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.

Systematic prediction of new ferroelectrics in space group R3. II

2007 ◽  
Vol 63 (2) ◽  
pp. 257-269 ◽  
Author(s):  
S. C. Abrahams
Keyword(s):  
Inorganic Crystal Structure Database ◽  
Additional Structure ◽  
Stability Range ◽  
Acta Cryst ◽  
Space Group ◽  
Structure Database ◽  
Inorganic Crystal ◽  
Crystal Class ◽  
Thermal Stability Range ◽  
Crystal Structure Database

Release 2006/1 of the Inorganic Crystal Structure Database contains 155 entries under space group R3. Atomic coordinate analysis of the first 81 structures, with 52 different structure types, in Part I [Abrahams (2006). Acta Cryst. B62, 26–41] identified a total of 18 new types that satisfy the structural criteria for ferroelectricity, five that are more likely to have or undergo a transition to 3m symmetry, 19 more likely to be or undergo a transition to nonpolar symmetry and ten with a lower property predictability. Coordinate analysis of the remaining 71 entries with 54 different structure types in Part II leads to 11 materials including Al4B6O15, PbTa3(PO4)(P2O7)3.5, the KCd4Ga5S12 family, the LiZnPO4 family, Ca3Nb1.95O8V0.05 and Mn4Ta2O9 as new candidates which satisfy the structural criteria, together with the three known ferroelectrics Na3MoO3F3, Pb2ScTaO6, and RbTi2(PO4)3 at 6.2 GPa. Two additional ferroelectric predictions are at a lower level of confidence. The analysis also reveals nine materials, two of which are isostructural, that more likely belong or are capable of undergoing a transition to crystal class 3m. There are 14 additional structure types which are more likely to be nonpolar or undergo a transition to nonpolarity, ten have reduced predictive properties, with a further nine for which the space group is expected to remain R3 over the full thermal stability range. The increasing use of methods for identifying overlooked inversion centers in structural determinations may be extended by using coordinate analysis for detecting additional commonly overlooked symmetry elements.

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
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