Wrong Choices, Missed Chances: The Motivations of Opposition Politicians and the Ensuing Failures at Regime Change in Venezuela, 2013-2022

This work presents a study of the failures to achieve regime change in Venezuela between 2013 and 2022. By using the critical juncture framework, this thesis shows that there have been moments of opportunity where permissive conditions (i.e., structural factors) were present to achieve regime change, that the Venezuelan opposition was incapable of seizing upon those moments of opportunity because they made sub-optimum strategic and coordination choices, and that these choices were influenced by the motivations that opposition actors have to be in politics

High efficiency cathodes for SOFCs prepared by spray-pyrolysis

In recent years, lowering the operating temper-ature of the Solid Oxide Fuel Cells (SOFCs) to the intermediate temperature range (500-700 ºC) has become the main challenge for this technology. The electrolyte resistance might be substantially reduced by using thin film electrolytes. However, the cathode polarization resitance is responsible for much of the loss in performance at low temperatures. Thus, the development of cathode materials with high electro-catalytic activity for the oxygen reduction reaction (ORR) is essential for this technology. Lanthanum strontium manganite La1-xSrxMnO3- (LSM) is the cathode material most widely used in SOFCs. However, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and poor ionic conductivity, limiting its application at high temperatures. Alternative mixed ionic-electronic conductors, such as La1-xSrxCo1-yFeyO3-δ (LSCF) and GdBaCo2O5+x (GBC) has been investi-gated, exhibiting better performances in the inter-mediate temperature range [1]. The performance of these electrodes might be improved at reduced temperature by extending the triple phase bounda-ry length at which gas, electrode and electrolyte phases are simultaneously in contact, serving as the predominant site for the electrochemical reac-tions. To date, the preparation of electrodes via wet infiltration of a cation solution into a porous electrolyte backbone is one of the most effective methods to increase the TPB area and to improve the efficiency of the cathodes, despite the limitations of this process for large-scale manufacturing of SOFCs. In this contribution an alternative preparation method based on spray-pyrolisis deposition into an electrolyte backbone is proposed, which posses a series of advantages with respect to the classical wet infiltration process, including easy industrial implementation, preparation in one single deposition/thermal step as well as low cost [2]. The most widely used cathodes in SOFCs technology were prepared by this alternative method process: La1-xSrxMnO3- and La0.6Sr0.4Co1-yFeyO3-δ (y = 0-2) series. The electrodes were deposited on porous Ce0.8Gd0.1O1.95 (CGO) backbones at 250 ºC by conventional spray pyrolysis from an aqueous precursor solution of metal nitrates. The structure, microstructure and electrochemical properties of these materials have been investigated by X-ray diffraction, field-emission SEM (Fig. 1.a) and im-pedance spectroscopy in symmetrical cells. The values of polarization resistance (Fig. 1.b) are ex-tremely low, ranging from 0.40 cm2 for LSM to 0.07 cm2 for LSCF0.2 at 600 ºC in air, compared to those previously reported in the literature for commercial electrolytes deposited at high tempera-ture, e.g. 25 cm2 for LSM.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Convergence Properties of the Likelihood of Computed Dynamic Models

This paper studies the econometrics of computed dynamic models. Since these models generally lack a closed-form solution, economists approximate the policy functions of the agents in the model with numerical methods. But this implies that, instead of the exact likelihood function, the researcher can evaluate only an approximated likelihood associated with the approximated policy function. What are the consequences for inference of the use of approximated likelihoods? First, we show that as the approximated policy function converges to the exact policy, the approximated likelihood also converges to the exact likelihood. Second, we prove that the approximated likelihood converges at the same rate as the approximated policy function. Third, we find that the error in the approximated likelihood gets compounded with the size of the sample. Fourth, we discuss convergence of Bayesian and classical estimates. We complete the paper with three applications to document the quantitative importance of our results.computed dynamic models, likelihood inference, asymptotic properties

Parent Stars of Extrasolar Planets. XII. Additional evidence for trends with vsini, condensation temperature, and chromospheric activity

Several recent studies have reported differences in vsini, abundance-condensation temperature trends, and chromospheric activity between samples of stars with and without Doppler-detected planets. These findings have been disputed, and the status of these results remains uncertain. We evaluate these claims using additional published data and find support for all three.Comment: 4 pages, 4 figures; accepted for publication in MNRAS as a Lette

Ce0.8Gd0.2O2‐δ / La0.6Sr0.4CoO3 Heterostructures prepared by pulsed laser deposition

Oxide interfaces have received greater attention due to the possibility to obtain properties that are very different from bulk materials. Due to the wide variety of electronic and ionic phenomena than can be detected at the interfaces, such materials have many technological applications [1]. Attention is being drawn to oxide heterostructures, a new family of artificial materials where electronic and ionic properties can be modulated at the interfaces by varying the characteristics of the layers [2, 3]. Slight variations in the near anionic-cationic order might take place if there exists strained interfaces. The interest in multilayared heterostructures derives from the mobility deffects and the space-charge-zone effects at the interfaces. In addition, a new degree of freedom related to the capacitive and resistive contributions is provided as a consequence of the size effects of these artificial structures. In the present work, for the first time, we investigate the structure, microstructure and electrical properties of a new family of heterostructured materials with alternated thin layers of La0.6Sr0.4CoO3 (LSC) and Ce0.8Gd0.2O2-δ (CGO) deposited by pulsed laser deposition on (110) NdGaO3 (NGO) single crystal substrates. In order to evaluate the interfacial contribution to ionic-electronic conductivity and know what is actually happens at the interface of MIECs, different heterostructures were prepared by varying both the number of bilayers (N) and the total thickness of the samples (N = 2 and 5; and the thickness were 50, 100 and 300 nm).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Novel microstructural strategies to enhance the electrochemical performance of La0.8Sr0.2MnO3-δ cathodes

Solid oxide fuel cells (SOFCs) are one of the most efficient technologies for direct conversion of fuels to electricity. La0.8Sr0.2MnO3-δ (LSM) is the cathode material most widely used in SOFCs [1], however, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and low ionic conductivity, which limits its application at reduced temperatures. In this material the electrochemically active reaction sites are restricted to the triple-phase boundary (TPB) near the electrolyte/electrode interface, where the electrolyte, air and electrode meet. Different strategies have been investigated to enlarge the TPB area of LSM, such as the production of nanocrystalline powders by precursor routes, preparation of composites by infiltration methods and thin films [2-4]. Here we present and compare innovative procedures to extend the TPB of LSM in contact with yttria-stabilized zirconia electrolyte: i) nanocrystalline LSM films deposited by spray-pyrolysis on polished YSZ electrolyte; ii) the addition of polymethyl methacrylate microspheres as pore formers during the spray-pyrolysis deposition to further increase the porosity of these films and (iii) the deposition of LSM by spray-pyrolysis on porous backbones of Zr0.84Y0.16O1.92 (YSZ), Ce0.9Gd0.1O1.95 (CGO) and Bi1.5Y0.5O3- (BYO) electrolytes previously fixed onto the YSZ electrolyte. The most remarkable peculiarity of this novel preparation method, compared to the traditional impregnation, is the formation of LSM thick film of 500 nm on the electrode surface (Fig. 1), which improves the electrical conductivity of the composite cathode. Thus, the optimization of this novel method would be an alternative to the classical infiltration with several advantages for the industry of planar SOFCs allowing the deposition of a wide variety of ceramic films over large areas with more uniform distribution of the catalyst, lower cost and only one deposition step is required to form the electrode. The morphology and electrochemical performance of the electrode have been investigated by scanning electron microscopy and impedance spectroscopy. Very low values of area specific resistance were obtained ranging from 1.4 cm2 for LSM deposited on polished YSZ to 0.06 cm2 for LSM deposited onto BYO backbone at a measured temperature of 650 ºC. This electrodes exhibit high performance even after annealing at 950 ºC making them interesting for applications at intermediate temperatures.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Empirical evidence for the continuing need to 'think small first' in UK company law

The most recent UK corporate law restatement has its stated aim to ‘think small first’ in company law legislation. This article is the first to use data science and imaging techniques to provide an empirical snapshot of the entire UK corporate database. It identifies the continuing need to think small first: most companies are small when tested by corporate type (public v private) and type of accounts publicly filed. We then factor in time series, which evidences that most companies are newer and smaller companies. This article then identifies the implications of this novel empirical analysis. First, corporate law analysis tends to ‘think big first’, and will either need to justify such an approach or change it. Second, a large number of companies provide no public financial information due to inherent time lag. The sheer scale of new companies challenges this approach. Third, the UK should provide a corporate governance framework for smaller companies. Fourth, the UK’s corporate accounting regime thinks small first in substance, but its form needs to be simplified to truly think small first. Fifth, whilst more mortgages were granted by smaller companies, larger companies granted more mortgages per company: so arguably corporate finance bucks the trend for the need to think small first

Entropy production, viscosity bounds and bumpy black holes

The ratio of shear viscosity to entropy density, η/s, is computed in various holographic geometries that break translation invariance (but are isotropic). The shear viscosity does not have a hydrodynamic interpretation in such backgrounds, but does quantify the rate of entropy production due to a strain. Fluctuations of the metric components δg xy are massive about these backgrounds, leading to η/s < 1/(4π) at all finite temperatures (even in Einstein gravity). As the temperature is taken to zero, different behaviors are possible. If translation symmetry breaking is irrelevant in the far IR, then η/s tends to a constant at T = 0. This constant can be parametrically small. If the translation symmetry is broken in the far IR (which nonetheless develops emergent scale invariance), then η/s ∼ T 2 ν as T → 0, with ν ≤ 1 in all cases we have considered. While these results violate simple bounds on η/s, we note that they are consistent with a possible bound on the rate of entropy production due to strain