نتایج جستجو برای: sand desert metaphor
تعداد نتایج: 54821 فیلتر نتایج به سال:
The lizardScincus scincus, also known as sandfish, can move through aeolian desert sand in a swimming-like manner. A prerequisite for this ability is a special integument, i.e. scales with a very low friction for sand and a high abrasion resistance. Glycans in the scales are causally related to the low friction. Here, we analysed the glycans and found that neutral glycans with five to nine mann...
Soil organic carbon (SOC) plays an important role in improving soil properties and the C global cycle. Limited attention, though, has been given to assessing the spatial patterns and stocks of SOC in desert ecosystems. In this study, we quantitatively evaluated the spatial variability of SOC and its influencing factors and estimated SOC storage in a region (40 km2) of the Gobi desert. SOC exhib...
Differences in level of herbivory can select for local adaptation and genetic differentiation of plant populations in different environments. Mean bulb depth of the desert lily Pancratium sickenbergeri, differs considerably among populations differing in the level of herbivory by the dorcas gazelle. The gazelle digs in the sand to remove most of the bulb of the lily. Deeper bulbs have less mate...
Booming dunes” are large desert sand dunes that make a loud droning or humming noise during an avalanching of sand. The phenomenon has been observed for censturies, yet it remains largely unexplained. This note demonstrates that the booming frequency does not scale with the size of the particle or with the shearing speed of the avalanching sand. Instead, the dune may act as a waveguide with a f...
Remote sensing and field evidence are used to describe sand deposits found in associated pathways of emplacement in the eastern Mojave Desert. Two separate pathways are identified here: one extending eastward from the Bristol Playa through the Cadiz and Danby Playas and Rice Valley to the Colorado River, and a second parallel path extending eastward from Dale Playa through the Palen and Ford Pl...
Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand partic...
Wind-blown sand is a typical example of twophase particle-laden flows. Owing to lack of simultaneous measured data of the wind and wind-blown sand, interactions between them have not yet been fully understood. In this study, natural sand of 100–125 lm taken from Taklimakan Desert was tested at the freestream wind speed of 8.3 m/s in an atmospheric boundary layer wind tunnel. The captured flow i...
The male sand rat (Psammomys obesus), captured alive in the Sahara desert in the area of Béni-Abbès (Algeria), exhibited seasonal changes in plasma concentrations of LH, characterized by an increase in early summer. Administration of a standard dose of GnRH (200 ng/100 g body weight) failed to elicit significant season-dependent changes in LH release, whereas the increase in plasma testosterone...
Sand-swimming, a form of desert burrowing, offers interesting potential as a locomotion mode for robots operating in loose, granular environments. Unfortunately, the computational cost of modeling the relevant physics raises obstacles to a thorough exploration of the system dynamics. Geometric mechanics offers techniques for reducing the complexity of evaluating gaits, thereby offering the pote...
Wind erosion measurements were carried out in Nellis Dunes Recreation Area, southern Nevada, USA. Gross erosion (the total mass of sediment effectively blown away from a surface), gross deposition (the total mass of sediment effectively depositing on a surface) and net erosion (the difference in sediment mass before and after an event) were measured for 1 year, on 17 different types of surfaces...
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