Simulation of granular soil behaviour using the bullet physics library

A physics engine is computer software which provides a simulation of certain physical systems, such as rigid body dynamics, soft body dynamics and fluid dynamics. Physics engines were firstly developed for using in animation and gaming industry ; nevertheless, due to fast calculation speed they are attracting more and more attetion from researchers of the engineering fields. Since physics engines are capable of performing fast calculations on multibody rigid dynamic systems, soil particles can be modeled as distinct rigid bodies. However, up to date, it is not clear to what extent they perform accurately in modeling soil behaviour from a geotechnical viewpoint. To investigate this, examples of pluviation and vibration-induced desification were simulated using the physics engine called Bullet physics library. In order to create soil samples, first, randomly shaped polyhedrons, representing gravels, were generated using the Voronoi tessellation approach. Then, particles were pluviated through a funnel into a cylinder. Once the soil particles settled in a static state, the cylinder was subjected to horizontal sinusoidal vibration for a period of 20 seconds. The same procedure for sample perparation was performed in the laboratory. The results of pluviation and vibration tests weere recorded and compared to those of simulations. A good agreement has been found between the results of simulations and laboratory tests. The findings in this study reinforce the idea that physics engines can be employed as a geotechnical engineering simulation tool

Circulating levels of adiponectin, orexin-A, ghrelin and the antioxidant paraoxonase-1 in metabolic syndrome

Aim. Metabolic syndrome (MS) is a disorder consisting of various abnormalities such as dyslipidemia, obesity, hypertension and hyperglycemia. Over the past two decades, the prevalence of MS has greatly increased, and it has become a global health problem. We measured and compared plasma concentrations of adiponectin, orexin-A, ghrelin and the antioxidant paraoxonase-1 (PON1) between patients with metabolic syndrome (MS) and healthy controls