The Twin Risks in the Dollarization Debate: Country and Devaluation Risks

This paper discusses dollarization from the perspective of the relation between country and devaluation risk. In the absence of balance sheet effects, we find that a full dollarization of an economy increases its country risk. On the other hand, when balance sheet effects are present, the full dollarization could reduce country risk. The link between these two risks is based on the government’s financial needs. In this paper government devalue the currency for fiscal purposes. Consequently, a full dollarization closes this avenue transferring the whole cost to bond holders. This paper stresses the idea that dollarization is at the very end a fiscal issue. Empirically, using the ratio of foreign currency deposit on total deposits as a proxy to the balance sheet effect, the paper tests the importance of this variable on country risk. We find that the balance sheet has a positive effect on country risk, in other words, country with higher balance sheet effect should have higher country risk.

The twin risks in the dollarization debate: country and devaluation risks

This paper discusses dollarization from the perspective of the relation between country and devaluation risk. In the absence of balance sheet effects, we find that a full dollarization of an economy increases its country risk. On the other hand, when balance sheet effects are present, the full dollarization could reduce country risk. The link between these two risks is based on the government's financial needs. In this paper government devalue the currency for fiscal purposes. Consequently, a full dollarization closes this avenue transferring the whole cost to bond holders. This paper stresses the idea that dollarization is at the very end a fiscal issue. Empirically, using the ratio of foreign currency deposit on total deposits as a proxy to the balance sheet effect, the paper tests the importance of this variable on country risk. We find that the balance sheet has a positive effect on country risk, in other words, country with higher balance sheet effect should have higher country risk.Departamento de Economí

DFT and kinetics study of O/O2 mixtures reacting over a graphite (0001) basal surface

Spin-polarised density functional calculations were used to investigate the interaction of atomic and molecular oxygen on the basal graphite surface at several atomic coverages. Two carbon layers were enough to represent the graphite surface. Oxygen atoms bind mainly over C-C bridge sites forming an epoxide-like structure with a two carbon puckering and with adsorption energies in the 0.95-1.28 eV range, depending on the atomic coverage. Molecular oxygen only shows a very weak physisorption. Atomic adsorption and diffusion along with atomic recombination via Eley-Rideal and Langmuir-Hinshelwood mechanisms were studied. All surfaces processes were activated with energy barriers that decreased for lower atomic coverages. Relaxation effects were non-negligible. A microkinetic model with six elementary surface processes was proposed to see the overall behavior of several initial O/O2 mixtures flowing over a graphite surface at 300-1000 K. Thermal rate constants were derived from Density Functional Theory (DFT) data and standard Transition State Theory. A very low steady-state atomic coverage ( < 0.5 %) was predicted and also very low atomic recombination coefficients were observed (gamma_O < 5x10-4). The Eley-Rideal together with the adsorption and desorption processes were much more important than the Langmuir-Hinshelwood reaction

The twin risks in the dollarization debate: country and devaluation risks

This paper discusses dollarization from the perspective of the relation between country and devaluation risk. In the absence of balance sheet effects, we find that a full dollarization of an economy increases its country risk. On the other hand, when balance sheet effects are present, the full dollarization could reduce country risk. The link between these two risks is based on the government's financial needs. In this paper government devalue the currency for fiscal purposes. Consequently, a full dollarization closes this avenue transferring the whole cost to bond holders. This paper stresses the idea that dollarization is at the very end a fiscal issue. Empirically, using the ratio of foreign currency deposit on total deposits as a proxy to the balance sheet effect, the paper tests the importance of this variable on country risk. We find that the balance sheet has a positive effect on country risk, in other words, country with higher balance sheet effect should have higher country risk.Departamento de Economí

Coleópteros lamelicornios (Coleoptera: Scarabaeoidea) de la barranca de Huehuetitla, Tlaxcala, México

Se presenta un estudio sobre las especies de coleópteros lamelicornios establecidas en la barranca de Huehuetitla, a 2,300-2,600 m de altitud en el estado de Tlaxcala. Durante las colectas realizadas entre agosto de 2008 y diciembre de 2009 en bosque de enebro y vegetación secundaria, se obtuvieron 2,751 ejemplares que representan cinco familias, siete subfamilias y 23 especies de los géneros: Phyllophaga, Diplotaxis, Cyclocephala, Orizabus, Ligyrys, Xyloryctes, Chrysina, Paranomala, Cotinis, Euphoria, Eucanthus, Labarrus, Cephalocyclus, Liothorax, Gonaphodiellus y Trox. El género con mayor número de especies fue Phyllophaga (5 spp.), mientras que Cephalocyclus fuliginosus fue la especie más abundante con el 50.4% de la muestra total. Por medio de un Análisis de Parsimonia de Endemismos se muestra la relación con otras faunas regionales, donde la barranca de Huehuetitla quedó agrupada junto con las faunas de La Michilía, Durango y Villa de Allende, Estado de México. Su composición genérica tiene un predominio de elementos pertenecientes al patrón Paleoamericano, seguido de elementos del Altiplano Mexicano.Se presenta un estudio sobre las especies de coleópteros lamelicornios establecidas en la barranca de Huehuetitla, a 2,300-2,600 m de altitud en el estado de Tlaxcala. Durante las colectas realizadas entre agosto de 2008 y diciembre de 2009 en bosque de enebro y vegetación secundaria, se obtuvieron 2,751 ejemplares que representan cinco familias, siete subfamilias y 23 especies de los géneros: Phyllophaga, Diplotaxis, Cyclocephala, Orizabus, Ligyrys, Xyloryctes, Chrysina, Paranomala, Cotinis, Euphoria, Eucanthus, Labarrus, Cephalocyclus, Liothorax, Gonaphodiellus y Trox. El género con mayor número de especies fue Phyllophaga (5 spp.), mientras que Cephalocyclus fuliginosus fue la especie más abundante con el 50.4% de la muestra total. Por medio de un Análisis de Parsimonia de Endemismos se muestra la relación con otras faunas regionales, donde la barranca de Huehuetitla quedó agrupada junto con las faunas de La Michilía, Durango y Villa de Allende, Estado de México. Su composición genérica tiene un predominio de elementos pertenecientes al patrón Paleoamericano, seguido de elementos del Altiplano Mexicano

Quasiclassical trajectory dynamics study of atomic oxygen collisions on an O-preadsorbed graphite (0001) surface with a new analytical potential energy surface

A new flexible periodic LEPS potential energy surface (FPLEPS) based on density functional theory data is constructed for the interaction of atomic oxygen with an O-preadsorbed graphite (0001) surface over a C-C bridge. New ingredients were added to the usual expression of the FPLEPS in order to take into account the entrance barriers, molecular orientation and morphology of the surface. A total of 563 DFT points were used to fit the Eley-Rideal (ER) reaction channel, achieving a root-mean-square deviation of 0.120 eV for energies lower than 1 eV over reactants. A quasiclassical trajectory (QCT) dynamics study has been performed at several initial conditions: collision energies (0.01 ≤ Ecol ≤ 2.0 eV), incident angles (0, 45) and surface temperatures (100 ≤ Tsurf ≤ 900 K). Also quasithermal and hyperthermal ( = 5.2 eV) conditions were considered. Eley-Rideal reaction and O reflection were the main processes, remaining the formed O2 molecules translationally and internally excited via the ER process. The calculated polar scattering angle distribution of hyperthermal atomic oxygen colliding onto a clean graphite surface matches better the experimental one for O/O2 mixtures impinging on HOPG than those obtained for O colliding onto an O-preadsorbed surface

Dynamics of the oxygen molecules scattered from graphite (0001) surface and comparison with experimental data

A quasiclassical trajectory dynamics study of molecular oxygen colliding over a free of defects and clean graphite (0001) surface has been performed with a recently published density functional theory based flexible periodic London-Eyring-Polanyi-Sato potential energy surface (PES). Although the PES was mainly constructed for describing accurately the recombination of atomic oxygen over an O-preadsorbed surface, here we show that this PES is also reliable to study the scattering of O2 over graphite surface. Thus, several initial conditions have been explored: collision energies (0.2 ≤ Ecol ≤ 1.2 eV), incident angles (0, 45), surface temperatures (100 ≤ Tsurf ≤ 900 K) and some rovibrational O2 levels (v = 0,1,2 and j = 1,17,25). The calculated polar scattering angular distributions are in good agreement with the experimental ones in a wide range of explored conditions. Moreover, the comparison with hyperthermal experimental data, which was unclear in a previous work, has been finally clarified. The effect of O2 (v,j) internal state on the scattering is very small

Classical dynamics study of atomic oxygen over graphite (0001) with new interpolated and analytical potential energy surfaces

Two adiabatic potential energy surfaces (PESs) based on density functional theory data are constructed for the interaction of atomic oxygen with graphite (0 0 0 1) surface: an analytical FPLEPS PES and an interpolated Modified Shepard one. A classical trajectory study has been performed for the two PESs for different initial conditions: collision energy (0.1 ⩽ Ecol ⩽ 1.3 eV), surface temperature (100 ⩽ Tsurf ⩽ 900 K) and two incident angles (θv = 0°, 45°), and also for thermal conditions (T = TOxygen = Tsurf = 300-1500 K). In addition, hyperthermal experimental conditions corresponding to a hot atom distribution (〈Ecol〉 = 5.2 eV) were also considered. All the properties studied for the two PESs were in close agreement in almost the major part of the explored conditions, although some differences were obtained for low Ecol due to the presence of a physisorption minimum in the MS PES that was not included into the FPLEPS one. The adsorption process occurs mainly over bridge sites. Adsorption probabilities are lower than reflection ones in practically all the conditions explored and increase quickly with Ecol until a maximum and then decrease smoothly. Polar scattering angle distributions present a peak centred around the specular angle position and broaden when increasing Ecol or Tsurf. A good agreement respect this peak position was found in comparison with the experimental hyperthermal data. The transfer of energy is mainly from the atom to the surface and increases when initial collision energy does

Recombination and chemical energy accommodation coefficients from chemical dynamics simulations: O/O2 mixtures reacting over a β-cristobalite (001) surface

A microkinetic model is developed to study the reactivity of an O/O2 gas mixture over a -cristobalite (001) surface. The thermal rate constants for the relevant elementary processes are either inferred from quasiclassical trajectory calculations or using some statistical approaches, resting on a recently developed interpolated multidimensional potential energy surface based on density functional theory. The kinetic model predicts a large molecular coverage at temperatures lower than 1000 K, in contrary to a large atomic coverage at higher temperatures. The computed atomic oxygen recombination coefficient, mainly involving atomic adsorption and Eley-Rideal recombination, is small and increases with temperature in the 700-1700 K range (0.01 < gamma_O < 0.02) in good agreement with experiments. In the same temperature range, the estimated chemical energy accommodation coefficient, the main contribution to which is the atomic adsorption process is almost constant and differs from unity (0.75 < beta_O < 0.80)

Building Hierarchical Tree Representations Using Homological-Based Tools

A new algorithm for computing the α-tree hierarchical repre sentation of a grey-scale digital image is presented here. The technique is based on an efficient simplified version of the Homological Spanning For est (HSF) for encoding homological and homotopy-based information of binary digital images. We create one Adjacency Tree (AdjT) for each intensity contrast in a fully parallel manner. These trees, which define a Contrast Adjacency Forest (CAdjF), are in turn transversely intercon nected by another couple of trees: the classical α-tree, and a new one complementing it, called here the α∗-tree. They convey the information of the contours and the flat regions of the original color image, plus the relations between them. Using both the α and α∗-trees, this new topolog ical representation prevents some classical drawbacks that appear when working with a single tree. An implementation in OCTAVE/MATLAB validates the correctness of our algorithm.Ministerio de Ciencia e Innovación PID2019-110455GB-I00 (Par-HoT