Vintage Capital and the Dynamics of the AK Model

This paper analyzes the equilibrium dynamics of an AK-type endogenous growth model with vintage capital. The inclusion of vintage capital leads to oscillatory dynamics governed by replacement echoes, which additionally influence the intercept of the balanced growth path. These features, which are in sharp contrast to those from the standard AK model, can contribute to explaining the short-run deviations observed between investment and growth rates time series. To characterize the convergence properties and the dynamics of the model we develop analytical and numerical methods that should be of interest for the general resolution of endogenous growth models with vintage capital.

Vintage capital and the dynamics of the AK model

This paper analyzes the equilibrium dynamics of an AK-type endogenous growth model with vintage capital. The inclusion of vintage capital leads to oscillatory dynamics governed by replacement echoes, which additionally influence the intercept of the balanced growth path. These features, which are in sharp contrast to those from the standard AK model, can contribute to explaining the short-run deviations observed between investment and growth rates time series. To characterize the optimal solutions of the model we develop analytical and numerical methods that should be of interest for the general resolution of endogenous growth models with vintage capital.Endogenous growth, Vintage capital, AK model, Differencedifferential equations

Technological Progress, Employment and the Lifetime of Capital

We study the impact of technological progress on the level of employment in a vintage capital model where: i) capital and labor are gross complementary; ii) labor supply is endogenous and indivisible; iii) there is full employment, and iv) the rate of labor-saving technological progress is endogenous. We characterize the stationary distributions of vintage capital goods and the corresponding equilibrium values for employment and capital lifetime. It is shown that both variables are non-monotonic functions of technological progress indicators. Technological accelerations are found to increase employment provided innovations are not too radical

Risk Sharing and Growth in Small-Open Economies

In this paper, we revisit the question of how domestic and foreign risks affect growth through the lens of an AK small-open economy model with risky borrowing/lending and global diversification. Wealth is allocated between domestic and foreign assets and the optimal allocation depends on both the difference in deterministic returns and the relative magnitude and correlation of domestic and foreign risks. Depending on parameters, the small-open economy may choose to either borrow from abroad, despite the fact that this is risky, or lend. In contrast to standard N-country models, whether growth is faster or slower (and whether growth is more or less volatile) compared to autarky is not entirely driven by relative risk aversion but also depends on the return and risk characteristics of domestic and foreign assets. We also show that growth volatility and mean growth have typically nonmonotonic relationships with the the levels and correlation of domestic and foreign risks. We argue that these results are in line with, and lay down some theoretical foundations for explaining the conflicting empirical results regarding the impact of international financial integration on growth and in particular threshold effects

Crystalline and Spectroscopic Experimental Study of the Dinitromesithylen (DNM) Compared with the Theoretical Results

International audienceThe aim by our group is to understand the behavior of the grouping Me starting from the study of mols. having a great symmetry. In this part of work, it is had the cryst. structure of the dinitromesitylen (DNM) who is solved starting from the diffraction of x-​rays starting from a monocrystal at the ambient temp. Parallel to the exptl. study, we undertook theor. calcns. conformation of the insulated mol. of DNM by using the methods of the DFT (D. Functional Theory)​. Calcns. of optimization of the mol. conformation of the DNM by using the chain of program GAUSSIAN03 and functional MPW1PW91, B3LYP level with the 6-​311G and LANL2DZ bases gave a conformation Cs with results very close to the expt. for the lengths and the angles of bond. The computation results obtained starting from the base set (6-​311G) and functional MPW1PW91 give for the conformation of Dinitromesitylen (DNM) a good agreement of about a 1.9​% for the lengths of bond and 1.2​% for the angles of bond compared with the results of the diffraction of x-​rays. Calcns. of Raman and infra-​red spectroscopy undertaken starting from the results of optimization by using same functional MPW1PW91 and B3LYP and the sets of bases 6-​311G LanL2DZ led to the values of frequencies very close to the exptl. results

Switching of excited states in cyclometalated platinum complexes incorporating pyridyl-acetylide ligands (Pt-C[triple bond, length as m-dash]C-py): a combined experimental and theoretical study

International audienceThis article presents the design of cyclometalated platinum(II) complexes incorporating pyridyl-appended acetylide ligands of the form Pt-C[triple bond, length as m-dash]C-py, acting either as sites for protonation or methylation reactions or as a host receptor for binding metal cations. The complexes studied are Pt(t-Bu2phbpy)(-C[triple bond, length as m-dash]C-py), 2, which can undergo protonation at the pyridyl N; its cationic N-methylated derivative [Pt(t-Bu2phbpy)(-C[triple bond, length as m-dash]C-pyMe)]+, 4, which serves as a model of the N-protonated species; and a derivative in which the pyridyl ring is incorporated into a macrocyclic diamide-crown ether ligand (3). The co-ligand t-Bu2phbpy is a cyclometalated, N[caret]N[caret]C-coordinated phenylbipyridine ligand carrying tert-butyl groups at the 4-positions of the pyridyl rings. The photophysical properties of the neutral compounds 2 and 3 have been compared to those of the pyridinium, methyl-pyridinium or metal-complexed species (namely 2-H+, 4 and 3-Pb2+). Detailed TD-DFT calculations provide a theoretical basis to account for the experimentally-observed changes upon protonation/methylation/complexation. The joint TD-DFT and experimental studies provide evidence for an unprecedented molecular switch in the nature of the excited state (from mixed L′LCT/MLCT to ML′CT) in which the acceptor ligand in the CT process switches from being the N[caret]N[caret]C ligand to the pyridyl acetylide

Contrasted photochromic and luminescent properties in dinuclear Pt(II) complexes linked through a central dithienylethene unit

We disclose two unprecedented complexes built with a central dithienylethene photochrome connecting two cyclometalated Pt(ii) moieties either on the reactive carbon atoms or on the lateral non-reactive carbon atoms of the photochrome. The two systems show vastly different properties that are rationalised thanks to quantum-chemical calculations

Azo-based iminopyridine ligands: synthesis, optical properties, theoretical calculations and complexation studies

We describe herein the full characterization of azobenzene based iminopyridine ligands (L1–L4) synthesized by a condensation reaction between N,N-Dimethyl-4,4′-azodianiline or 4-(4-nitrophenylazo)aniline and 2-pyridinecarboxaldehyde or 2,6-pyridinedicarboxaldehyde. The UV–visible absorption bands of these ligands were fully assigned using DFT and TD-DFT computations. The complexation of ligand L1 and ligand L2 with AgNO3 afforded two neutral silver metal complexes formulated as [AgL1NO3] and [AgL2NO3], respectively. The crystal structure analysis of the two complexes indicate the presence of a Y-shaped tricoordinated silver (I) ion for [AgL1NO3] and a tetracoordinated silver(I) ion displaying rather rare and distorted square planar geometry for [AgL2NO3]. In solid state, for both complexes, a 3D supramolecular architecture is generated via hydrogen bonds of type C–HċO and C–Hċπ. The UV–visible spectrophotometric titration studies of ligands L1–L4, by increasing amount of AgNO3 or of ZnCl2 indicates the possibility of forming transition metal complexes with these ligands

A "reverse interrupter": the novel molecular design of a fluorescent photochromic DTE-based bipyridine

International audienceAn original design of a fluorescent dithienylethene (DTE)-based bipyridine, where donor (D) and acceptor (A) groups are located on the same thiophene ring of the DTE unit, is reported; in non-polar solvents, UV or visible excitation triggers a photochromic reaction, disrupting the conjugation and quenching the fluorescence

A Theory of Energy Use *

Abstract The evidence shows that the short run elasticity of energy use is smaller than its long run elasticity. The recent evidence on energy use and energy prices suggests, though, that the short run response of energy use to energy prices has changed over time. Existing theories of energy use, namely, complementarity between capital and energy at the aggregate level, or putty-clay models of energy use, cannot account for this change in the short run elasticity of energy use. Here we propose a theory where, as in the data, the short run elasticity of energy use is smaller than the long run elasticity but it also may change depending on the rate of embodied technological progress, accounting for its increase in the recent years