An increase in intracellular Ca2+ concentration ([Ca2+]) and morphological were simultaneously observed by epifluorescence and differential interference contrast (DIC) microscopy during fertilization of the sand dollar, Clypeaster japonicus. [Ca2+], which was detected by a Ca2+ indicator, Fluo-3, initially increased just beneath the sperm-attached site on the egg surface 8.6 sec after attachmen...

We summarize information concerning Recent and Pleistocene-Holocene Uruguayan sand dollars (Mellitidae), as well as Miocene taxa (Monophorasteridae). Recent and Pleistocene-Holocene species (Encope emarginata, Mellita quinquiesperforata, and Leodia sexisperforata) are at their southernmost limits of distribution, with only E. emarginata recorded further south than Uruguay. Lower temperatures to...

Many larvae and other plankton have complex and variable morphologies of unknown functional significance. We experimentally and theoretically investigated the functional consequences of the complex morphologies of larval sand dollars, Dendraster excentricus (Eschscholtz), for hydrodynamic interactions between swimming and turbulent water motion. Vertical shearing flows (horizontal gradients of ...

Microbially induced calcium carbonate precipitation (MICP) is a phenomenon based on urease activity of halotolerant and alkaliphilic microorganisms that can be used for the soil bioclogging and biocementation in geotechnical engineering. However, enrichment cultures produced from indigenous soil bacteria cannot be used for large-scale MICP because their urease activity decreased with the rate a...

Studies of dunefields in central and western North America show that mineralogical maturity can provide new insights into the origin and evolution of aeolian sand bodies. Many of the world’s great sand seas in Africa, Asia and Australia are quartzdominated and thus can be considered to be mineralogically mature. The Algodones (California) and Parker (Arizona) dunes in the southwestern United St...

The seabed of the Pontine Archipelago (Tyrrhenian Sea) insular shelf is peculiar as it characterized by a mixed siliciclastic–carbonate sedimentation. In order to reconstruct Late Quaternary paleoenvironmental evolution Archipelago, this study investigates succession facies recorded two sediment cores. For purpose, benthic foraminifera and rhodoliths assemblages were considered. cores (post-Las...

Mixed siliciclastic-carbonate active orogens are common on Earth's surface, yet most studies have focused erosion and weathering in silicate-rich landscapes. Relative to purely siliciclastic landscapes, the response of uplift may differ mixed-lithology regions. However, our knowledge mixed carbonate-silicate lithologies is limited and, thus, so understanding mechanistic coupling between uplift,...

Carbonate sand is characterized by the presence of fragile grains, which may influence their mechanical response due to imposed loading; especially cyclic loading. The shear wave velocity (VS) provides relevant information for design foundation inserted in this type soil, can be obtained from laboratory tests with use bender elements (BE). This paper aims evaluate VS value a carbonate triaxial ...