Seismic Behavior of the Cube of Zoroaster Tower Using the Discrete Element Method

There are several ancient stone masonry structures of great archeological significance in earthquake-prone areas around the world. Kaʻba-ye Zartošt (Cube of Zoroaster) is a 14.0 m square in shape tower, which was built using white limestone blocks and dry joints. The tower dates back to the Achaemenid empire era and is located in the earthquake-prone area of Nagsh-e Rustam in Fars, Iran. Although, after approximately 2,500 years the tower is still standing, it is now in a severely deteriorated condition and may be vulnerable against future large in magnitude earthquakes. This paper presents the application of a previously developed three-dimensional numerical model based on the discrete element method of analysis to investigate the seismic behavior of the Cube of Zoroaster tower. The tower was represented by a series of distinct blocks separated by zero-thickness interfaces. The developed model allows finite displacements and rotations of distinct blocks while new contacts between the blocks are automatically recognized and updated as the calculation progresses. A series of non-linear dynamic analysis have been performed. To this end, the behavior of the tower to different ground shaking motions is discussed and the possible failure modes for each case are explored

Neuroprotective Effects of Rosmarinic Acid on Ciguatoxin in Primary Human Neurons

International audienceCiguatoxin (CTX), is a toxic compound produced by microalgae (dinoflagellate) Gambierdiscus spp., and is bio-accumulated and bio-transformed through the marine food chain causing neurological deficits. To determine the mechanism of CTX-mediated cytotoxicity in human neurons, we measured extracellular lactate dehydrogenase (LDH) activity, intracellular levels of nicotinamide adenine dinucleotide (NAD(+)) and H2AX phosphorylation at serine 139 as a measure for DNA damage in primary cultures of human neurons treated with Pacific (P)-CTX-1B and P-CTX-3C. We found these marine toxins can induce a time and dose-dependent increase in extracellular LDH activity, with a concomitant decline in intracellular NAD(+) levels and increased DNA damage at the concentration range of 5-200 nM. We also showed that pre- and post-treatment with rosmarinic acid (RA), the active constituent of the Heliotropium foertherianum (Boraginaceae) can attenuate CTX-mediated neurotoxicity. These results further highlight the potential of RA in the treatment of CTX-induced neurological deficits