T HE significance of the myelin sheath in electric excitation and in conduction of a nerve impulse has already been elucidated to a great extent by previous investigations (1-3). The results of these investigations are consistent, indicating that the myelin sheath has a distributed capacity and a very high leakage resistance. This capacity and resistance of the myelin sheath are considered to f...

A 1-d Ising model is shown to reproduce qualitatively the dynamics of ripple formation. Saltation effect is imposed using a Kawasaki dynamics and a pair interaction over some distance l. Within this model, the ripple state turns out to be metastable in agreement with cellular automata simulations as well as recent under water experiments. A dynamical phase diagram is obtained. A mean-field solu...

the understanding soil erosion processes and the development of accurate erosion prediction models require understanding of detachment, deposition and sediment transport in rills. to evaluate the effect of soil type and flow stream power on the relative importance of flow driven processes of sediment transport, and on the boundary between the processes regarding to particle size, experiments we...

Extended Abstract 1Introduction Estimating correct volume of sediment in a fluvial system is one of the most important issues in water engineering, river engineering, water resources, facilities, structures, water and environmental projects and programs for the development of them. The bed load transfers by saltation and suspension forms according to the sediment particle size. The sediment loa...

The dominant process in producing fine dust aerosols during saltation is thought to be sandblasting. Recent studies claim that due to competing physical processes, emission efficiencies of dust aerosols oscillate with increasing wind friction speed. These oscillations can result in order of magnitude changes in dust mass emissions. Our work shows that emission efficiencies, and hence emissions ...

Many barchan dune corridors appear to contain dunes of stable size and spacing [1], and dune fields often exhibit regular patterns [2, 3] with apparent characteristic size and spacing (figure 1). It is still an open question as to what sets this characteristic scaling – local conditions such as topography or sand supply, or common dynamic processes such as those relating to saltation. Additiona...

Introduction: The shapes produced on terrestrial surfaces that are continually subject to aeolian processes range in size from tiny ripples to giant draa [1]. The physical mechanism of the formation of ripples, the smallest of aeolian bedforms, is intimately related to saltation and reptation processes. Sand and granule ripples are typically tens of reptation path lengths wide and do not alter ...

The rate of movement for 3and 10-cm-high granule ripples was documented in September of 2006 at Great Sand Dunes National Park and Preserve during a particularly strong wind event. Impact creep induced by saltating sand caused 24 granules min 1 to cross each cm of crest length during wind that averaged 9 m s 1 (at a height well above 1 m), which is substantially larger than the threshold for sa...

Sand traps are used to measure Aeolian flux. Since they modify the surrounding wind velocity field their gauging represents an important challenge. We use numerical simulations under the assumption of homogeneous turbulence based on FLUENT to systematically study the flow field and trapping efficiency of one of the most common devices based on a hollow cylinder with two slits. In particular, we...

A n experimental investigation of a solid–liquid dispersion pipe flow was conducted using a pulsed ultrasonic Doppler velocimeter. The solid phase was composed of buoyant particles dispersed in water. This particular two-phase flow was used to mimic the behaviour of ice–water flow. Four diagnostics were used to study the complex nature of the two-phase flow mixtures: mean velocity profiles, spa...