Applying the mean free-path length model to juvenile Chinook salmon migrating in the Sacramento River, California

2020 ◽  
Vol 103 (12) ◽  
pp. 1603-1617
Author(s):  
Anna E. Steel ◽  
James J. Anderson ◽  
Brian Mulvey ◽  
David L. Smith
Keyword(s):  
Free Path ◽  
Chinook Salmon ◽  
Path Length ◽  
Free Path Length ◽  
Mean Free Path ◽  
Sacramento River ◽  
Juvenile Chinook Salmon ◽  
The Mean ◽  
Juvenile Chinook

Lattice Boltzmann Simulation of Rarefied Gas Flow Along Moving Rigid Objects in Micro-Cavities

2015 ◽  
Author(s):  
Weilin Yang ◽  
Hongxia Li ◽  
TieJun Zhang ◽  
Ibrahim M. Elfadel
Keyword(s):  
Free Path ◽  
Lattice Boltzmann ◽  
Path Length ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Free Path Length ◽  
Mean Free Path ◽  
Fluid Simulation ◽  
Transition Flow ◽  
Rarefied Gas Flow

Rarefied gas flow plays an important role in the design and performance analysis of micro-electro-mechanical systems (MEMS) under high-vacuum conditions. The rarefaction can be evaluated by the Knudsen number (Kn), which is the ratio of the molecular mean free path length and the characteristic length. In micro systems, the rarefied gas flow usually stays in the slip- and transition-flow regions (10−3 < Kn < 10), and may even go into the free molecular flow region (Kn > 10). As a result, conventional design tools based on continuum Navier-Stokes equation solvers are not applicable to analyzing rarefaction phenomena in MEMS under vacuum conditions. In this paper, we investigate the rarefied gas flow by using the lattice Boltzmann method (LBM), which is suitable for mesoscopic fluid simulation. The gas pressure determines the mean free path length and Kn, which further influences the relaxation time in the collision procedure of LBM. Here, we focus on the problem of squeezed film damping caused by an oscillating rigid object in a cavity. We propose an improved LBM with an immersed boundary approach, where an adjustable force term is used to quantify the interaction between the moving object and adjacent fluid, and further determines the slip velocity. With the proposed approach, the rarefied gas flow in MEMS with squeezed film damping is characterized. Different factors that affect the damping coefficient, such as pressure of gas and frequency of oscillation, are investigated in our simulation studies.

Imaging of Metal/Semiconductor Interface by Ballistic-Electron-Emission Microscopy (Beem)

1992 ◽  
Vol 295 ◽  
Author(s):  
E. Y. Lee ◽  
B. R. Turnew ◽  
J. R. Jimenez ◽  
L. J. Schowalter
Keyword(s):  
Free Path ◽  
Spatial Resolution ◽  
Electron Emission ◽  
Path Length ◽  
Free Path Length ◽  
Mean Free Path ◽  
Ballistic Electron Emission Microscopy ◽  
Semiconductor Interface ◽  
Ballistic Electron ◽  
Emission Microscopy

AbstractStudies in ballistic-electron-emission spectroscopy (BEES) have enabled precise energy measurements of Schottky barrier heights with excellent spatial resolution and, more recently, it was shown that even scattering at the metal/semiconductor interface affects the BEES spectrum [1]. Monte Carlo simulations have been done to predict the spatial resolution of ballistic-electron-emission microscopy (BEEM) [2]. In this paper, we will discuss the experimental spatial resolution of BEEM, and we will also give some of our BEES results for Au/Si and for Au/PtSi/Si. Our experimental BEEM studies indicate that, for Au/Si, hot electron transport is diffusive rather than ballistic, because the inelastic mean free path length (∼100 nm) is much larger than the elastic mean free path length (∼10 nm). This is in agreement with existing theories and with the literature on the internal photoemission method of studying the transport. Even in this diffusive regime, the spatial resolution of BEEM is still expected to be very good, being on the order of 10 nm [2]. Our preliminary work on PtSi shows that it has an attenuation length of 4 nm, which differs significantly from that of Au.

A STUDY ON PENETRATION DEPTH OF POLARIZATION IMAGING

2010 ◽  
Vol 03 (03) ◽  
pp. 177-181 ◽  
Author(s):  
RAN LIAO ◽  
NAN ZENG ◽  
DONGZHI LI ◽  
TIANLIANG YUN ◽  
YONGHONG HE ◽  
...  
Keyword(s):  
Penetration Depth ◽  
Free Path ◽  
Path Length ◽  
Free Path Length ◽  
Mean Free Path ◽  
Optical Measurements ◽  
Degree Of Polarization ◽  
Polarization Imaging ◽  
Optical Clearing ◽  
Different Response

Optical clearing improves the penetration depth of optical measurements in turbid tissues. Polarization imaging has been demonstrated as a potentially promising tool for detecting cancers in superficial tissues, but its limited depth of detection is a major obstacle to the effective application in clinical diagnosis. In the present paper, detection depths of two polarization imaging methods, i.e., rotating linear polarization imaging (RLPI) and degree of polarization imaging (DOPI), are examined quantitatively using both experiments and Monte Carlo simulations. The results show that the contrast curves of RLPI and DOPI are different. The characteristic depth of DOPI scales with transport mean free path length, and that of RLPI increases slightly with g. Both characteristic depths of RLPI and DOPI are on the order of transport mean free path length and the former is almost twice as large as the latter. It is expected that they should have different response to optical clearing process in tissues.

Mean free-path length theory of predator–prey interactions: Application to juvenile salmon migration

2005 ◽  
Vol 186 (2) ◽  
pp. 196-211 ◽  
Author(s):  
James J. Anderson ◽  
Eliezer Gurarie ◽  
Richard W. Zabel
Keyword(s):  
Free Path ◽  
Path Length ◽  
Free Path Length ◽  
Mean Free Path ◽  
Juvenile Salmon ◽  
Predator Prey

scholarly journals Reconciling fish and farms: Methods for managing California rice fields as salmon habitat

2020 ◽  
Author(s):  
Eric J. Holmes ◽  
Parsa Saffarinia ◽  
Andrew L. Rypel ◽  
Miranda N. Bell-Tilcock ◽  
Jacob V. Katz ◽  
...  
Keyword(s):  
Growth Rates ◽  
Chinook Salmon ◽  
Rice Fields ◽  
Sacramento River ◽  
Fish Conservation ◽  
Juvenile Chinook Salmon ◽  
Flooded Rice ◽  
Avian Predators ◽  
Juvenile Chinook ◽  
Field Drainage

AbstractThe rearing habitat for juvenile Chinook Salmon (Oncorhynchus tshawytscha) in California, the southernmost portion of their range, has drastically declined throughout the past century. Recently, through cooperative agreements with diverse stakeholders, winter-flooded agricultural rice fields in California’s Central Valley have emerged as promising habitat for rearing juvenile Chinook Salmon. From 2013 to 2016, we conducted a series of experiments examining methods for rearing fall-run Chinook Salmon on winter-flooded rice fields in the Yolo Bypass, a modified floodplain of the Sacramento River in California. These included: 1) influence of field substrate differences from previous season rice harvest; 2) effects of depth refugia from avian predators (trenches); 3) field drainage methods to promote efficient egress of fish; and 4) in-field salmon survivorship over time. Zooplankton (fish food) in the winter-flooded rice fields were 53-150x more abundant when directly compared to the adjacent Sacramento River. Correspondingly, somatic growth rates of juvenile hatchery-sourced fall-run Chinook Salmon stocked in rice fields were two to five times greater versus fish in the adjacent Sacramento River. Post-harvest field substrate treatments had little effect on the lower trophic food web and had an insignificant effect on growth rates of in-field salmon. Though depth refugia did not directly increase survival, it buffered maximum water temperatures in the trenches and facilitated outmigration from fields during draining. Rapid field drainage methods yielded the highest survival and were preferable to drawn-out drainage methods. High initial mortality immediately after stocking was observed in the survival over time experiment with stable and high survival after the first week. In-field survival ranged 7.4–61.6% and increased over the course of the experiments. Despite coinciding with the most extreme drought in California’s recorded history, which elevated water temperatures and reduced the regional extent of adjacent flooded habitats which concentrated avian predators, the adaptive research framework enabled incremental improvements in design to increase survival. The abundance of food resources and exceptionally high growth rates observed during these experiments illustrate the benefits associated with reconciling off-season agricultural land use with fish conservation practices. Without any detriment to flood control or agricultural yield, there is great promise for reconciliation ecology between agricultural floodplains and endangered fish conservation where minor alterations to farm management practices could greatly enhance the effectiveness of fish conservation outcomes.

scholarly journals Reconciling fish and farms: Methods for managing California rice fields as salmon habitat

2020 ◽  
Author(s):  
Eric J. Holmes ◽  
Parsa Saffarinia ◽  
Andrew L. Rypel ◽  
Miranda N. Bell-Tilcock ◽  
Jacob V. Katz ◽  
...  
Keyword(s):  
Growth Rates ◽  
Chinook Salmon ◽  
Rice Fields ◽  
Sacramento River ◽  
Fish Conservation ◽  
Juvenile Chinook Salmon ◽  
Flooded Rice ◽  
Avian Predators ◽  
Juvenile Chinook ◽  
Field Drainage

AbstractThe rearing habitat for juvenile Chinook Salmon (Oncorhynchus tshawytscha) in California, the southernmost portion of their range, has drastically declined throughout the past century. Recently, through cooperative agreements with diverse stakeholders, winter-flooded agricultural rice fields in California’s Central Valley have emerged as promising habitat for rearing juvenile Chinook Salmon. From 2013 to 2016, we conducted a series of experiments examining methods for rearing fall-run Chinook Salmon on winter-flooded rice fields in the Yolo Bypass, a modified floodplain of the Sacramento River in California. These included: 1) influence of field substrate differences from previous season rice harvest; 2) effects of depth refugia from avian predators (trenches); 3) field drainage methods to promote efficient egress of fish; and 4) in-field salmon survivorship over time. Zooplankton (fish food) in the winter-flooded rice fields were 53-150x more abundant when directly compared to the adjacent Sacramento River. Correspondingly, somatic growth rates of juvenile hatchery-sourced fall-run Chinook Salmon stocked in rice fields were two to five times greater versus fish in the adjacent Sacramento River. Post-harvest field substrate treatments had little effect on the lower trophic food web and had an insignificant effect on growth rates of in-field salmon. Though depth refugia did not directly increase survival, it buffered maximum water temperatures in the trenches and facilitated outmigration from fields during draining. Rapid field drainage methods yielded the highest survival and were preferable to drawn-out drainage methods. High initial mortality immediately after stocking was observed in the survival over time experiment with stable and high survival after the first week. In-field survival ranged 7.4–61.6% and increased over the course of the experiments. Despite coinciding with the most extreme drought in California’s recorded history, which elevated water temperatures and reduced the regional extent of adjacent flooded habitats which concentrated avian predators, the adaptive research framework enabled incremental improvements in design to increase survival. The abundance of food resources and exceptionally high growth rates observed during these experiments illustrate the benefits associated with reconciling off-season agricultural land use with fish conservation practices. Without any detriment to flood control or agricultural yield, there is great promise for reconciliation ecology between agricultural floodplains and endangered fish conservation where minor alterations to farm management practices could greatly enhance the effectiveness of fish conservation outcomes.

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