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The Growth and Decline of the Western Roman Empire: Quantifying the Dynamics of Army Size, Territory, and Coinage
We model the Western Roman Empire from 500 BCE to 500 CE, aiming to understand the interdependent dynamics of army size, conquered territory and the production and debasement of coins within the empire. The relationships are represented through feedback relationships and modelled mathematically via a dynamical system, specified as a set of ordinary differential equations. We analyze the stability of a subsystem and determine that it is neutrally stable. Based on this, we find that to prevent decline, the optimal policy was to stop debasement and reduce the army size and territory during the rule of Marcus Aurelius. Given the nature of the stability of the system and the kind of policies necessary to prevent decline, we argue that a high degree of centralized control was necessary, in line with basic tenets of structural-demographic theory. This article was updated on 01/09/2020 to correct an error in equation (3.5). Page numbers were updated on 01/05/2021
Microstructure and chemical composition of Roman orichalcum coins emitted after the monetary reform of Augustus (23 B.C.)
A collection of ancient Roman orichalcum coins, i.e., a copper-zinc alloy, minted under the reigns from Caesar to Domitianus, have been characterised using scanning electron microscopy (SEM-EDS) and electron microprobe analysis (EMPA). We studied, for the first time, coins emitted by Romans after the reforms of Augustus (23 B.C.) and Nero (63-64 A.D). These coins, consisting of asses, sestertii, dupondii and semisses, were analysed using non- and invasive analyses, aiming to explore microstructure, corrosive process and to acquire quantitative chemical analysis. The results revealed that the coins are characterized by porous external layers, which are affected by dezincification and decuprification processes. As pictured by the X-ray maps, the elemental distribution of Cu and Zn shows patterns of depletion that in some cases penetrate in deep up to 1 mm. The composition of the un-corroded nucleus is a Cu-Zn alloy containing up to 30% of Zn, typical of coins produced via cementation process
The Bahmani “currency reform” of the early fifteenth century in light of the Akola hoard
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Nanoplasmonics simulations at the basis set limit through completeness-optimized, local numerical basis sets
We present an approach for generating local numerical basis sets of improving
accuracy for first-principles nanoplasmonics simulations within time-dependent
density functional theory. The method is demonstrated for copper, silver, and
gold nanoparticles that are of experimental interest but computationally
demanding due to the semi-core d-electrons that affect their plasmonic
response. The basis sets are constructed by augmenting numerical atomic orbital
basis sets by truncated Gaussian-type orbitals generated by the
completeness-optimization scheme, which is applied to the photoabsorption
spectra of homoatomic metal atom dimers. We obtain basis sets of improving
accuracy up to the complete basis set limit and demonstrate that the
performance of the basis sets transfers to simulations of larger nanoparticles
and nanoalloys as well as to calculations with various exchange-correlation
functionals. This work promotes the use of the local basis set approach of
controllable accuracy in first-principles nanoplasmonics simulations and
beyond.Comment: 11 pages, 6 figure
The Bahmani “currency reform” of the early fifteenth century in light of the Akola hoard
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The role of reconstruction in self-assembly of alkylthiolate monolayers on coinage metal surfaces
Through a combination of standard laboratory-based surface science methods, together with synchrotron radiation-based normal incidence X-ray standing wave (NIXSW) experiments, the interface structure of simple alkylthiolate ‘self-assembled monolayers’ on Cu(1 1 1), Ag(1 1 1) and Au(1 1 1) has been investigated over the last not, vert, similar15 years. A key conclusion is that in all cases the adsorbate produces a substantial, density-lowering, reconstruction of the outermost metal layer, although the nature of these reconstructions is quite different on the three metals. The main results of these investigations are briefly reviewed and contrasted
Azobenzene versus 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) at Au(111): Characterizing the role of spacer groups
We present large-scale density-functional theory (DFT) calculations and
temperature programmed desorption measurements to characterize the structural,
energetic and vibrational properties of the functionalized molecular switch
3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular
emphasis is placed on exploring the accuracy of the semi-empirical dispersion
correction approach to semi-local DFT (DFT-D) in accounting for the substantial
van der Waals component in the surface chemical bond. In line with previous
findings for benzene and pure azobenzene at coinage metal surfaces, DFT-D
significantly overbinds the molecule, but seems to yield an accurate adsorption
geometry as far as can be judged from the experimental data. Comparing the
trans adsorption geometry of TBA and azobenzene at Au(111) reveals a remarkable
insensitivity of the structural and vibrational properties of the -N=N- moiety.
This questions the established view of the role of the bulky tert-butyl-spacer
groups for the switching of TBA in terms of a mere geometric decoupling of the
photochemically active diazo-bridge from the gold substrate.Comment: 9 pages including 6 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Special Libraries, January 1922
Volume 13, Issue 1https://scholarworks.sjsu.edu/sla_sl_1922/1000/thumbnail.jp
Metaphoric competence and communicative language ability
Recent developments in cognitive linguistics have highlighted the importance as well as the ubiquity of metaphor in language. Despite this, the ability of second language learners to use metaphors is often still not seen as a core ability. In this paper, we take a model of communicative competence that has been widely influential in both language teaching and language testing, namely Bachman (1990), and argue, giving a range of examples of language use and learner difficulty, that metaphoric competence has in fact an important role to play in all areas of communicative competence. In other words, it can contribute centrally to grammatical competence, textual competence, illocutionary competence, sociolinguistic competence, and strategic competence. Metaphor is thus highly relevant to second language learning, teaching and testing, from the earliest to the most advanced stages of learning
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