A method for measuring in situ compressional wave attenuation exploiting the spectral decay of reflection coefficient Bragg resonances is applied to fine-grained sediments New England Mud Patch. Measurements layer-averaged a 10.3 m mud layer yield 0.04 {0.03, 0.055} dB/m/kHz (braces indicate outer bounds); twice as large at site with 3.2 thickness. It shown that both results are heavily influen...

Many biological networks grow under strong spatial constraints, where the large-scale structure emerges from the extension, the branching and intersection of growing parts of the network. One example is provided by ant tunnelling networks, which represent the most common nest architecture in ants. Our goal was to understand how these network structures emerge from the tunnel growth dynamics. We...

Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modelling in order to investigate the genesis and early development stages of costal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation flux and the growth of vegetat...

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 ...

Sand patches are one of the precursors to early stage protodunes and occur widely in both desert coastal aeolian environments. Here we show field evidence a mechanism explain initiation sand on non-erodible surfaces, such as gravels moist beaches. Changes transport dynamics, directly associated with height saltation layer variable law, observed at boundary between erodible surfaces lead deposit...

Land use and land cover change have been of great concern in global change research in recent years. Base on comparison with the remote sensing data in1982 and 2000 and field investigation, the results of land cover and land use change were obtained by the method of landscape analysis. Ten types of land use were identified: riparian woods, riparian shrubbery, desert shrubbery, desert grassland,...