scholarly journals Asymmetric mixing transport: A horizontal transport mechanism for sinking plankton and sediment in tidal flows

2001 ◽  
Vol 46 (2) ◽  
pp. 381-391 ◽  
Author(s):  
James M. Pringle ◽  
Peter J. S. Franks
Keyword(s):  
Transport Mechanism ◽  
Horizontal Transport ◽  
Tidal Flows

Routes of Transport across the Antarctic Polar Vortex in the Southern Spring

2012 ◽  
Vol 69 (2) ◽  
pp. 741-752 ◽  
Author(s):  
Alvaro de la Cámara ◽  
Ana M. Mancho ◽  
Kayo Ide ◽  
Encarna Serrano ◽  
Carlos R. Mechoso
Keyword(s):  
Lyapunov Exponents ◽  
Transport Mechanism ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Polar Vortex ◽  
Horizontal Transport ◽  
The Past ◽  
Lobe Dynamics ◽  
Antarctic Polar Vortex ◽  
The Antarctic

Abstract Transport in the lower stratosphere over Antarctica has been studied in the past by means of several approaches, such as contour dynamics or Lyapunov exponents. This paper examines the problem by means of a new Lagrangian descriptor, which is referred to as the function M. The focus is on the southern spring of 2005, which allows for a comparison with previous analyses based on Lyapunov exponents. With the methodology based on the function M, a much sharper depiction of key Lagrangian features is achieved and routes of large-scale horizontal transport across the vortex edge are captured. These results highlight the importance of lobe dynamics as a transport mechanism across the Antarctic polar vortex.

The Kinematical Principles Governing Horizontal Transport Induced by Vertical Migration in Tidal Flows

1995 ◽  
Vol 75 (1) ◽  
pp. 3-13 ◽  
Author(s):  
A.E. Hill
Keyword(s):  
Vertical Migration ◽  
Horizontal Displacement ◽  
Tidal Currents ◽  
Tidal Period ◽  
Diel Migration ◽  
Horizontal Transport ◽  
Preferred Direction ◽  
Tidal Flows ◽  
Tidal Stream ◽  
Stream Transport

Vertical migration interacts with oscillatory tidal flows to produce horizontal transport. When the vertical migration period is an exact multiple of the tidal period then net uni-directional horizontal transport can occur. This happens most effectively in ‘selective tidal-stream transport’ for which vertical migration into the flow is specifically synchronized with the dominant (usually M2) tidal constituent. When migration and tide are not synchronized there is no net transport and, instead, a horizontal displacement oscillation of the organism takes place at the beat period between the vertical migration and tidal periods. The most common form of vertical migration is synchronized, not with the tide, but with the day-night cycle. Diel migration in M2-period tidal currents induces no net transport, but can produce excursions of several tens of kilometres over just a few days. Diel vertical migration can, however, interact with the sun-generated part of the semi-diurnal tide to produce net horizontal transport, the direction of which is controlled by the phase of the S2 tidal currents. The spatial distribution of phase implies that regions of horizontal convergence and divergence will result from diel migration. Diel migration in diurnal-period tides causes the preferred direction of transport to reverse at six-monthly intervals.

Effects of Vincristine on Endothelial Microtubules in the Spinal Cord

1976 ◽  
Vol 34 ◽  
pp. 58-59
Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller
Keyword(s):  
Spinal Cord ◽  
Biological Activity ◽  
Horseradish Peroxidase ◽  
Transport Mechanism ◽  
Vasogenic Edema ◽  
Vesicular Transport ◽  
Close Proximity

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.

A microscopic marker experiment study on high temperature oxidation of Ni-Al alloy

1986 ◽  
Vol 44 ◽  
pp. 514-515
Author(s):  
Shou-kong Fan
Keyword(s):  
Transport Mechanism ◽  
High Temperature Oxidation ◽  
Transverse Section ◽  
Al Alloy ◽  
Metal Interface ◽  
Electron Microscopic ◽  
Temperature Oxidation ◽  
Analytical Electron ◽  
Microscopic Studies ◽  
First Time

Transmission and analytical electron microscopic studies of scale microstructures and microscopic marker experiments have been carried out in order to determine the transport mechanism in the oxidation of Ni-Al alloy. According to the classical theory, the oxidation of nickel takes place by transport of Ni cations across the scale forming new oxide at the scale/gas interface. Any markers deposited on the Ni surface are expected to remain at the scale/metal interface after oxidation. This investigation using TEM transverse section techniques and deposited microscopic markers shows a different result,which indicates that a considerable amount of oxygen was transported inward. This is the first time that such fine-scale markers have been coupled with high resolution characterization instruments such as TEM/STEM to provide detailed information about evolution of oxide scale microstructure.

Molecular Basis of Glucose Transport Mechanism in Plants

2019 ◽  
Author(s):  
Balaji Selvam ◽  
Ya-Chi Yu ◽  
Liqing Chen ◽  
Diwakar Shukla
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Conformational Changes ◽  
Transport Mechanism ◽  
Conformational Dynamics ◽  
Site Directed Mutagenesis ◽  
Free Energy Barrier ◽  
Transport Cycle ◽  
Dynamics Simulations

<p>The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane. However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as 1 for the glucose the transport mechanism. SWEETs undergoes structural transition to outward-facing (OF), Occluded (OC) and inward-facing (IF) and strongly support alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly same for OF, OC and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and act as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.</p>

TISSUE DISTRIBUTION OF TRANSCRIPTS INVOLVED IN BIOSYNTHESIS OF BENZYLISOQUINOLINE ALKALOID IN MATURE PLANTS OF Argemone mexicana L. (Papaveraceae)

2018 ◽  
Vol 41 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Felipe Vázquez-Flota ◽  
Jorge Rubio-Piña ◽  
Jorge Xool-Tamayo ◽  
Mariela Vergara-Olivares ◽  
Yahaira Tamayo-Ordoñez ◽  
...  
Keyword(s):  
Tissue Distribution ◽  
Transport Mechanism ◽  
Gene Products ◽  
Argemone Mexicana ◽  
Benzylisoquinoline Alkaloid ◽  
Stems And Leaves ◽  
Specific Reactions

The distribution of berberine and sanguinarine was analyzed in roots, stems and leaves of mature Argemone mexicana plants, along with that of transcripts corresponding to selected genes involved in both early biosynthetic reactions, which are common to both alkaloids, and in the late specific reactions conducting to the formation of each of them. Roots were the main sites of alkaloid accumulation, though they showed the lowest accumulation of the analyzed transcripts. Results are discussed in terms of the operation of a possible transport mechanism of alkaloids between the aerial tissues and the roots, or the occurrence of different biosynthetic alternative reactions in both parts, aerial and underground tissues, involving different gene products, yet with similar catalytic capacities.

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