2,053 research outputs found
Investment decisions in manufacturing: Assessing the effects of real oil prices and their uncertainty
We investigate the effects of real oil prices and their uncertainty on the investment decision. Making use of plant-level data, we estimate dynamic, discrete choice models that allow modeling investment inaction, under different assumptions related to initial conditions and unobserved heterogeneity. We find that increases in real oil price changes and in real oil price uncertainty significantly reduce the likelihood of investment action – in line with the predictions of irreversible investment theory. We also document that the investment decisions exhibit strong pure state dependence and are also significantly affected by initial conditions
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Competition and Contestability in Transition Banking: An Empirical Analysis
In this paper we focus on the market structure of the banking system in a set of Transition countries. In particular, by employing reduced-form revenue equations in a panel framework we are able to estimate the Panzar-Rosse h-statistic. We mainly control for heterogeneity by conditioning our estimation on bank-specific characteristics so as to account for differences in financial risk, size and finance mix. Our empirical results indicate that for the vast majority of cases banking systems operate under Monopolistic Competition
Structure and luminescence of intrinsic localized states in sodium silicate glasses
Sodium silicate glasses exhibit a characteristic luminescence with a maximum at about 3.4 eV, which is thought to be determined by optical excitation of local glass structures, called L centers. To investigate the atomic and electronic structures of these centers, we calculated the electronic properties of the ground and excited states of a sodium silicate glass using classical and ab initio methods. Classical molecular dynamics was used to generate glass models of
Na
2
O
−
3
SiO
2
molar composition, and the density functional theory (DFT), with hybrid functionals, was used to identify and characterize the geometric and electronic structures of L centers. The ground and excited
L
∗
center states are studied, and their calculated excitation and luminescence transition energies are in good agreement with experimental data. The results confirm that the lowest triplet excited states in sodium silicate glass are associated with small clusters of Na ions and nonbridging oxygen atoms. These clusters serve as structural precursors for the localization of the excited states, and the broad distribution of the luminescence energies is correlated with the short-range order of the Na cations. The atomic and electronic structures of the electron
E
−
1
and hole
H
+
1
centers are also studied. These results provide a more detailed insight into the atomistic structure of localized states in these important glasses
Modelling the local atomic structure of molybdenum in nuclear waste glasses with ab initio molecular dynamics simulations
The nature of chemical bonding of molybdenum in high level nuclear waste glasses has been elucidated by ab initio molecular dynamics simulations. Two compositions, (SiO2)57.5–(B2O3)10–(Na2O)15–(CaO)15–(MoO3)2.5 and (SiO2)57.3–(B2O3)20–(Na2O)6.8–(Li2O)13.4–(MoO3)2.5, were considered in order to investigate the effect of ionic and covalent components on the glass structure and the formation of the crystallisation precursors (Na2MoO4 and CaMoO4). The coordination environments of Mo cations and the corresponding bond lengths calculated from our model are in excellent agreement with experimental observations. The analysis of the first coordination shell reveals two different types of molybdenum host matrix bonds in the lithium sodium borosilicate glass. Based on the structural data and the bond valence model, we demonstrate that the Mo cation can be found in a redox state and the molybdate tetrahedron can be connected with the borosilicate network in a way that inhibits the formation of crystalline molybdates. These results significantly extend our understanding of bonding in Mo-containing nuclear waste glasses and demonstrate that tailoring the glass composition to specific heavy metal constituents can facilitate incorporation of heavy metals at high concentrations
Project Intermediation: The Critical Role of Negotiating Socio-Technical Regimes and Technological Niches to Achieve Climate Change Policies
This paper uses the socio-technical transitions model to understand the characteristics of the
evolving, interdisciplinary, and externalized context of climate change. Specifically, we (1) identify
the elements of the multi-level perspective that exist under new climate change policies and
trends and (2) conceptualized how this multi-level perspective will result in emerging project
practices. Together, these two areas of insights help us create a preliminary framework to better
understand and identify specific contextual characteristics that might influence the use and
adoption of project practices. This conceptual framework leads us to a key insight: the role of
projects in a socio-technical transitions context. Unlike projects that are delivered within a closedsystem environment, these projects are supported and affected by established institutional and
policy measures. The preliminary conceptual framework emphasizes project intermediaries and
how they choose project practices that translate policies into climate change outcomes. From this
framework, we lay forth propositions that will inform and be tested in subsequent empirical case
studies, where we plan to further explore project intermediation, focusing on the empirical setting
of climate change infrastructure
Computational modelling of structural, dynamical and electronic properties of multicomponent silicate glasses
Amorphous silica doped with alkali, alkaline-earth and boron ions is an important class of materials used in many technological applications. Computer simulations are able to provide atomic pictures of the glass structures and detailed insight into compositional atomic structure relationships. In this thesis several glasses of current interest for nuclear waste immobilisation and microelectronics are studied, using classical and \textit{ab initio} methods. A method to calculate the glass transition temperature in alkali borosilicate glasses, with pre-defined molar composition, was implemented and validated through the comparison with the available experimental data. The addition of alkali and boron oxides to pure SiO glass resulted in a vast decrease in the glass transition temperature. A systematic study of the density, atomic and electronic structure for lithium sodium borosilicate glasses with varying SiO / BO ratio and fixed molar composition of the alkali oxides is reported. \textit{Ab initio} molecular dynamics simulations were performed in order to model the local atomic structure of molybdenum in nuclear waste glasses. Analysis of the structural motifs and the environment of the molybdenum atoms provided direct insight into the solubility of Mo in the glass structures. The results significantly extend the understanding of how the chemical nature and molar composition of the glass host affect the bonding in Mo-containing nuclear glasses and demonstrate that tailoring the glass composition to specific heavy metal constituents can facilitate incorporation of heavy metals at high concentrations. A series of mixed alkali/alkaline-earth silicate glasses was investigated in order to understand the impact of the nature of the cations on the mobility of the alkaline-earth ions within the glass network. The size of the alkaline-earth cation was found to affect the short-range order and the short-time dynamical behaviour. An asymmetrical linear behaviour in the activation energy for diffusion with increasing cation size difference was observed. The electronic properties of excited states in sodium silicate glass were investigated with \textit{ab initio} modelling. The existence of two different configurations for the excited state are predicted, which correspond to two discrete ranges of luminescence energies. The different short-range ordering of Na cations corresponds to a structural precursor responsible for the calculated values of the luminescence energy
Polarization power spectra and dust cloud morphology
In the framework of studies of the CMB polarization and its Galactic
foregrounds, the angular power spectra of thermal dust polarization maps have
revealed an intriguing E/B asymmetry and a positive TE correlation. In
interpretation studies of these observations, magnetized ISM dust clouds have
been treated as filamentary structures only; however, sheet-like shapes are
also supported by observational and theoretical evidence. In this work, we
study the influence of cloud shape and its connection to the local magnetic
field on angular power spectra of thermal dust polarization maps. We simulate
realistic filament-like and sheet-like interstellar clouds, and generate
synthetic maps of their thermal dust polarized emission using the software
. We compute their polarization power spectra in multipole range
and quantify the E/B power asymmetry through the
ratio, and the correlation coefficient between T and E modes. We
quantify the dependence of and values on the offset angle
(between longest cloud axis and magnetic field) and inclination angle (between
line-of-sight and magnetic field) for both cloud shapes embedded either in a
regular or a turbulent magnetic field. We find that both cloud shapes cover the
same regions of the (, ) parameter space. The dependence on
inclination and offset angles are similar for both shapes although sheet-like
structures generally show larger scatter. In addition to the known dependence
on the offset angle, we find a strong dependence of and on
the inclination angle. The fact that filament-like and sheet-like structures
may lead to polarization power spectra with similar (, ) values
complicates their interpretation. In future analyses, this degeneracy should be
accounted for as well as the connection to the magnetic field geometry.Comment: 16 pages, 24 figures. Accepted for publication by A&
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