Methodology to evaluate rock slope stability under seismic conditions at Solà de Santa Coloma, Andorra

An analytical methodology is presented to evaluate rock slope stability under seismic conditions by considering the geomechanical and topographic properties of a slope. The objective is to locate potential rockfall source areas and evaluate their susceptibility in terms of probability of failure. For this purpose, the slope face of a study area is discretized into cells having homogenous aspect, slope angle, rock properties and joint set orientations. A pseudostatic limit equilibrium analysis is performed for each cell, whereby the destabilizing effect of an earthquake is represented by a horizontal force. The value of this force is calculated by linear interpolation between the peak horizontal ground acceleration PGA at the base and the top of the slope. The ground acceleration at the top of the slope is increased by 50% to account for topographic amplification. The uncertainty associated with the joint dip is taken into account using the Monte Carlo method. The proposed methodology was applied to a study site with moderate seismicity in Solà de Santa Coloma, located in the Principality of Andorra. The results of the analysis are consistent with the spatial distribution of historical rockfalls that have occurred since 1997. Moreover, the results indicate that for the studied area, 1) the most important factor controlling the rockfall susceptibility of the slope is water pressure in joints and 2) earthquake shaking with PGA of ≤0.16 g will cause a significant increase in rockfall activity only if water levels in joints are greater than 50% of the joint height

Stability of DON and DON-3-glucoside during baking as affected by the presence of food additives

The mycotoxin deoxynivalenol (DON) is one of the most common mycotoxins of cereals worldwide, and its occurrence has been widely reported in raw wheat. The free mycotoxin form is not the only route of exposure; modified forms can also be present in cereal products. Deoxynivalenol-3-glucoside (DON-3-glucoside) is a common DON plant conjugate. The mycotoxin concentration could be affected by food processing; here, we studied the stability of DON and DON-3-glucoside during baking of small doughs made from white wheat flour and other ingredients. A range of common food additives and ingredients were added to assess possible interference: ascorbic acid (E300), citric acid (E330), sorbic acid (E200), calcium propionate (E282), lecithin (E322), diacetyltartaric acid esters of fatty acid mono- and diglycerides (E472a), calcium phosphate (E341), disodium diphosphate (E450i), xanthan gum (E415), polydextrose (E1200), sorbitol (E420i), sodium bicarbonate (E500i), wheat gluten and malt flour. The DON content was reduced by 40%, and the DON-3-glucoside concentration increased by >100%, after baking for 20 min at 180°C. This confirmed that DON and DON-3-glucoside concentrations can vary during heating, and DON-3-glucoside could even increase after baking. However, DON and DON- 3-glucoside are not affected significantly by the presence of the food additives tested.The authors are grateful to the Spanish government (project AGL2014-55379-P) for providing financial support. A. Vidal thanks the Spanish government (Ministry of Education) for the pre-doctoral grant

Universality in percolation of arbitrary Uncorrelated Nested Subgraphs

The study of percolation in so-called {\em nested subgraphs} implies a generalization of the concept of percolation since the results are not linked to specific graph process. Here the behavior of such graphs at criticallity is studied for the case where the nesting operation is performed in an uncorrelated way. Specifically, I provide an analyitic derivation for the percolation inequality showing that the cluster size distribution under a generalized process of uncorrelated nesting at criticality follows a power law with universal exponent $\gamma=3/2$. The relevance of the result comes from the wide variety of processes responsible for the emergence of the giant component that fall within the category of nesting operations, whose outcome is a family of nested subgraphs.Comment: 5 pages, no figures. Mistakes found in early manuscript have been remove

Evolución durante el Cuaternario del Barranco de Tirajana, Gran Canaria

[Resumen] El barranco de Tirajana en su evolución ha pasado por diferentes etapas. Se ha podido constatar que ya funcionaba en el Mioceno superior pero su evolución principal se ha desarrollado en el Cuaternario entre los 0.6 m.a. y los 125.000 años. En este periodo se produce la depresión de Tirajana, que es la cuenca superior actual, como resultado de la producción de grandes deslizamientos de terreno (Lomoschitz y Corominas, 1992a y b; YLomoschitz, 1995). Asimismo, se ha comprobado que el desalojo hacia el mar de los materiales deslizados es lo que justifica la formación del complejo deltaico de Juan Grande, que es el único depósito de estas características de la isla.[Abstract] The evolution of the Barranco de Tirajana has followed different stages. We conclude that it was already active in upper Miocene although the main development ocurred in the Quaternary, 0.6 m.y. to 125.000 years ago. In this period Tirajana's Depression was originated, which is nowadays the upper basin, due to the triggering of large landslides in the area (Lomoschitz & Corominas, 1992a and b; Lomoschitz, 1995). Due the mobilization of the slide material to the sea it has built a complex deltaic formation named Juan Grande, unique in Gran Canaria

On the origin of ambiguity in efficient communication

This article studies the emergence of ambiguity in communication through the concept of logical irreversibility and within the framework of Shannon's information theory. This leads us to a precise and general expression of the intuition behind Zipf's vocabulary balance in terms of a symmetry equation between the complexities of the coding and the decoding processes that imposes an unavoidable amount of logical uncertainty in natural communication. Accordingly, the emergence of irreversible computations is required if the complexities of the coding and the decoding processes are balanced in a symmetric scenario, which means that the emergence of ambiguous codes is a necessary condition for natural communication to succeed.Comment: 28 pages, 2 figure

Methodology to evaluate rock slope stability under seismic conditions at Solà de Santa Coloma, Andorra

An analytical methodology is presented to evaluate rock slope stability under seismic conditions by considering the geomechanical and topographic properties of a slope. The objective is to locate potential rockfall source areas and evaluate their susceptibility in terms of probability of failure. For this purpose, the slope face of a study area is discretized into cells having homogenous aspect, slope angle, rock properties and joint set orientations. A pseudostatic limit equilibrium analysis is performed for each cell, whereby the destabilizing effect of an earthquake is represented by a horizontal force. The value of this force is calculated by linear interpolation between the peak horizontal ground acceleration PGA at the base and the top of the slope. The ground acceleration at the top of the slope is increased by 50% to account for topographic amplification. The uncertainty associated with the joint dip is taken into account using the Monte Carlo method. The proposed methodology was applied to a study site with moderate seismicity in Sol`a de Santa Coloma, located in the Principality of Andorra. The results of the analysis are consistent with the spatial distribution of historical rockfalls that have occurred since 1997. Moreover, the results indicate that for the studied area, 1) the most important factor controlling the rockfall susceptibility of the slope is water pressure in joints and 2) earthquake shaking with PGA of 0.16 g will cause a significant increase in rockfall activity only if water levels in joints are greater than 50% of the joint height.Postprint (published version