Peristaltic particle transport using the Lattice Boltzmann method

Peristaltic transport refers to a class of internal fluid flows where the periodic deformation of flexible containing walls elicits a non-negligible fluid motion. It is a mechanism used to transport fluid and immersed solid particles in a tube or channel when it is ineffective or impossible to impose a favorable pressure gradient or desirous to avoid contact between the transported mixture and mechanical moving parts. Peristaltic transport occurs in many physiological situations and has myriad industrial applications. We focus our study on the peristaltic transport of a macroscopic particle in a two-dimensional channel using the lattice Boltzmann method. We systematically investigate the effect of variation of the relevant dimensionless parameters of the system on the particle transport. We find, among other results, a case where an increase in Reynolds number can actually lead to a slight increase in particle transport, and a case where, as the wall deformation increases, the motion of the particle becomes non-negative only. We examine the particle behavior when the system exhibits the peculiar phenomenon of fluid trapping. Under these circumstances, the particle may itself become trapped where it is subsequently transported at the wave speed, which is the maximum possible transport in the absence of a favorable pressure gradient. Finally, we analyze how the particle presence affects stress, pressure, and dissipation in the fluid in hopes of determining preferred working conditions for peristaltic transport of shear-sensitive particles. We find that the levels of shear stress are most hazardous near the throat of the channel. We advise that shear-sensitive particles should be transported under conditions where trapping occurs as the particle is typically situated in a region of innocuous shear stress levels

Las cuatro defensas : novela policíaca

Ante

Migratory Bird Behavior and Bird Banding Education

Songbird migration is a marvel, especially that of the Wilson’s Warbler (Cardellina pusilla), which travels from as far north as Alaska to as far south as Costa Rica for breeding and wintering respectively. The Intermountain Bird Observatory in Boise, ID aids research in bird migration, productivity, and survivorship and puts an emphasis on public outreach and education. We created a children’s book to highlight the process of bird banding and Wilson’s Warblers\u27 lengthy migration. Based on a real Wilson’s Warbler banded in Denali National Park in Alaska and recaptured at Camas NWR in Idaho, that warbler traveled over 2000 miles in 3 weeks, and this fantastic endurance is what we chose to showcase in the book. Not only this but also breeding and migratory behavior, as well as interspecies interactions and the banding process. Endearingly named Wilma, the book follows her after a successful breeding season in Alaska, through the IBO banding station in Boise, between stops, another banding station in Albuquerque, and all the way to her wintering grounds in San Lui Potosi, Mexico. Meant to engage children in wildlife ecology and conservation, for every book bought from IBO, one to two, depending on the donation, are provided to a classroom in the Treasure Valley

The Dangerfield talisman / by J.J. Connington.

Mode of access: Internet

Relationships Among Migratory Behavior, Nesting Phenology, Reproductive Pace and Productivity of American Kestrels (\u3cem\u3eFalco sparverius\u3c/em\u3e)

Spring migratory behavior can have carry-over effects on nesting phenology, potentially affecting reproductive pace and productivity. However, the relationships among these factors remain unclear. American Kestrels, the smallest falcons in North America, vary in their migratory behavior across the continent, creating excellent opportunities for comparative studies. At our study site in Southern Idaho, some kestrels migrate, while others remain resident in the region throughout the year. We examined the relationships between migratory status, nest initiation date, length of incubation and nestling periods, and rate of successful fledging in two American Kestrel populations in the Treasure Valley and Camas Prairie Centennial Marsh, Idaho. Migratory status was determined using stable hydrogen isotope analyses on claw samples taken from both parents. We collected information on phenology, pace, and productivity using trail cameras within each nest box and in-person visits. We predicted that migrant kestrels would initiate nesting later in the breeding season, have a faster pace (as seen by shorter incubation and nestling periods), and have lower productivity (i.e. fledge less offspring) compared to resident kestrels. The results of our study will provide further insight into the relationships between migratory strategy, nesting phenology, reproductive pace, and productivity in partially migratory bird populations