Air Movement Evokes Electro-Olfactogram Oscillations in the Olfactory Epithelium and Modulates Olfactory Processing in a Slug

2006 ◽  
Vol 96 (4) ◽  
pp. 1939-1948 ◽  
Author(s):  
Iori Ito ◽  
Satoshi Watanabe ◽  
Yutaka Kirino
Keyword(s):  
Olfactory Epithelium ◽  
Phase Locking ◽  
High Concentration ◽  
Constant Frequency ◽  
Flow Rates ◽  
Odor Concentration ◽  
Air Movement ◽  
Clean Air ◽  
Olfactory Processing ◽  
Mechanical Dynamics

In many animals, neurons in the olfactory system have been shown to respond not only to odorants but also to air movements. However, the manner in which the mechanical dynamics of odor stimulation affect olfactory processing remains poorly understood. Using a series of flow rates and odor concentrations from clean air to high-concentration vapors, we systematically analyzed the effects of air movement and odor concentration on olfactory processing. We extracellularly recorded local field potentials and spike units from the olfactory epithelium (OE) and tentacular nerve (TN), which connects the first and second relay centers of olfactory information, in the terrestrial slug Limax marginatus. We found that clean air puffs at a flow rate of 0.18 ml/s (gentle wind), but not high-concentration odor puffs at lower flow rates, induced electro-olfactogram (EOG) oscillations in the OE with a constant frequency (2.5 Hz), regardless of the odor. Surgically isolated OE preparations also showed these EOG oscillations, indicating that the oscillations arose from the OE independently of the downstream circuits. The EOG oscillations entrained the slower spontaneous TN oscillations (1–2 Hz) to the fixed rhythm (2.5 Hz). Spontaneous and odor-evoked units were phase-locked to the TN oscillation peaks. This TN oscillation entrainment by the EOG oscillations caused stronger phase-locking, specifically TN oscillation peaks and EOG oscillation troughs. Taken together, these results suggest that when odors are carried by a gentle wind, the air movement induces EOG oscillations and modulates rhythmic spike patterning of olfactory outputs to the second olfactory relay center in Limax.

Navigation Along Windborne Plumes of Pheromone and Resource-Linked Odors

2021 ◽  
Vol 66 (1) ◽  
pp. 317-336
Author(s):  
Ring T. Cardé
Keyword(s):  
Behavioral Response ◽  
Scale Structure ◽  
Turbulent Structure ◽  
Odor Source ◽  
Fine Scale ◽  
Odor Concentration ◽  
Flying Insects ◽  
Odor Plumes ◽  
Clean Air ◽  
Sequential Measurements

Many insects locate resources such as a mate, a host, or food by flying upwind along the odor plumes that these resources emit to their source. A windborne plume has a turbulent structure comprised of odor filaments interspersed with clean air. As it propagates downwind, the plume becomes more dispersed and dilute, but filaments with concentrations above the threshold required to elicit a behavioral response from receiving organisms can persist for long distances. Flying insects orient along plumes by steering upwind, triggered by the optomotor reaction. Sequential measurements of differences in odor concentration are unreliable indicators of distance to or direction of the odor source. Plume intermittency and the plume's fine-scale structure can play a role in setting an insect's upwind course. The prowess of insects in navigating to odor sources has spawned bioinspired virtual models and even odor-seeking robots, although some of these approaches use mechanisms that are unnecessarily complex and probably exceed an insect's processing capabilities.

scholarly journals Numerical Studies of the Aerodynamic Features of Dead-end Entries with Side Junction

2020 ◽  
Vol 174 ◽  
pp. 01057
Author(s):  
Yuri Govorukhin ◽  
Victor Krivolapov ◽  
Dmitry Paleev ◽  
Vyacheslav Portola
Keyword(s):  
Numerical Simulation ◽  
Turbulent Diffusion ◽  
Geometric Parameters ◽  
Simulation Data ◽  
Flow Rates ◽  
Numerical Studies ◽  
Air Movement ◽  
Dead End ◽  
Wide Range ◽  
The Dead

Investigations of aerodynamic processes occurring in dead-end short entriesaired by turbulent diffusion have been performed. The numerical simulation of the processes of air movement through the entry, flow stalling at the junction with the dead-end entry (for side junction), and the formation of vortices at the dead end have been carried out. The study has been done for a wide range of air flows submitted for computation of air consumption and for various geometric parameters of the dead-end entry. The sizes of the vortex structures and the flow rates in the dead endshave been determined. Based on the results of processing the simulation data, we obtained graphs of the dependences between the length of the ventilated zone of the dead end and its height and width.

Regional distribution of rat electroolfactogram

1995 ◽  
Vol 73 (6) ◽  
pp. 2207-2220 ◽  
Author(s):  
P. I. Ezeh ◽  
L. M. Davis ◽  
J. W. Scott
Keyword(s):  
Spatial Distribution ◽  
Olfactory Bulb ◽  
Olfactory Epithelium ◽  
Flow Rate ◽  
Olfactory Receptor ◽  
Action Potentials ◽  
Amyl Acetate ◽  
Flow Rates ◽  
Olfactory Receptor Cells ◽  
Receptor Cells

1. Electroolfactorgram (EOG) recordings were made from different regions of the rat olfactory epithelium to test for spatial distribution of odor responses. 2. The EOG recordings showed spatial distribution of the odor responses in the olfactory epithelium. While some odorants (amyl acetate, anisole, and ethyl butyrate) were more effective in evoking responses in the dorsal recess near the septum, other odorants (including limonene, cineole, cyclooctane, and hexane) were more effective in the lateral recesses among the turbinate bones. These differences were seen as statistically significant odorant-by-position interactions in analysis of variance. 3. Comparisons of recordings along the anteroposterior dimension of the epithelium produced smaller differences between the odor responses. These were not significant for 3-mm distances, but were statistically significant for 5- to 6-mm distances along the dorsomedial epithelium. 4. The latencies were significantly longer in the lateral recesses than in the medial region. This probably reflects a more tortuous air path along the turbinate bones to the lateral recesses. 5. The olfactory receptor cells were activated by antidromic stimulation via the nerve layer of the olfactory bulb. The population spikes evoked from the olfactory receptor cells could be suppressed by prior stimulation with odorants that evoked strong EOG responses. This collision of the antidromic action potentials with the odor-evoked action potentials indicates that the same population of receptor cells was activated in both cases. 6. The flow rate and duration of the artificial sniff were varied systematically in some experiments. The differential distribution of response sizes was present at all flow rates and sniff durations. Some odors (e.g., amyl acetate and anisole) produced increased responses in the epithelium of the lateral recesses when flow rates or sniff durations were high. We suggest that these changes may reflect the sorptive properties of the nasal membranes on these odors. The responses to other odors (e.g., hexane or limonene) were not greatly affected by flow rate or sniff duration. 7. Taken with existing anatomic data, the results indicate that the primary olfactory neurons that project axons to glomeruli in different parts of the olfactory bulb are responsive to different odors. The latency differences between responses at medial and lateral sites are large enough to be physiologically significant in the generation of the patterned responses of olfactory bulb neurons.

Thermal Performance of a Receiver Tube for a High Concentration Ratio Parabolic Trough System and Potential for Improved Performance With Syltherm800-CuO Nanofluid

2015 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Zhongjie Huan ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Concentration Ratio ◽  
Low Flow ◽  
Fluid Temperature ◽  
Parabolic Trough ◽  
High Concentration ◽  
Flow Rates

In this paper, the thermal performance of a high concentration ratio parabolic trough system and the potential for improved thermal performance using Syltherm800-CuO nanofluid were investigated and presented. The parabolic trough system considered in this study has a concentration ratio of 113 compared with 82 in current commercial systems. The heat transfer fluid temperature was varied between 350 K and 650 K and volume fractions of nanoparticle were in the range 1–6%. Monte-Carlo ray tracing was used to obtain the actual heat flux on the receiver’s absorber tube. The obtained heat flux profiles were subsequently coupled with a computational fluid dynamics tool to investigate the thermal performance of the receiver. From the study, the results show that with increased concentration ratios, receiver thermal performance degrades, with both the receiver heat loss and the absorber tube circumferential temperature differences increasing, especially at low flow rates. The results further show that the use of nanofluids significantly improves receiver thermal performance. The heat transfer performance increases up to 38% while the thermal efficiency increases up to 15%. Significant improvements in receiver thermal efficiency exist at high inlet temperatures and low flow rates.

scholarly journals The Precentral Gyrus Contributions to the Early Time-Course of Grapheme-to-Phoneme Conversion

2021 ◽  
pp. 1-61
Author(s):  
Erik Kaestner ◽  
Xiaojing Wu ◽  
Daniel Friedman ◽  
Patricia Dugan ◽  
Orrin Devinsky ◽  
...  
Keyword(s):  
Letter String ◽  
Time Course ◽  
Phase Locking ◽  
Silent Reading ◽  
Early Time ◽  
Superior Temporal Gyrus ◽  
Precentral Gyrus ◽  
High Concentration ◽  
High Gamma ◽  
Pars Opercularis

Abstract As part of silent reading models, visual orthographic information is transduced into an auditory phonological code in a process of grapheme-to-phoneme conversion (GPC). This process is often identified with lateral temporal-parietal regions associated with auditory phoneme encoding. However, the role of articulatory phonemic representations and the precentral gyrus in GPC is ambiguous. Though the precentral gyrus is implicated in many functional MRI studies of reading, it is not clear if the time course of activity in this region is consistent with the precentral gyrus being involved in GPC. We recorded cortical electrophysiology during a bimodal match/mismatch task from eight patients with perisylvian subdural electrodes to examine the time course of neural activity during a task which necessitated GPC. Patients made a match/mismatch decision between a three-letter string and the following auditory bi-phoneme. We characterized the distribution and timing of evoked broadband high gamma (BHG; 70–170 Hz) as well as phase-locking between electrodes. The precentral gyrus emerged with a high concentration of broadband high gamma responses to visual and auditory language as well as mismatch effects. The pars opercularis, supramarginal gyrus, and superior temporal gyrus were also involved. The precentral gyrus showed strong phase-locking with the caudal fusiform gyrus during letter-string presentation and with surrounding perisylvian cortex during the bimodal visual-auditory comparison period. These findings hint at a role for precentral cortex in transducing visual into auditory codes during silent reading.

scholarly journals The Recent Development Status and Future Role of Fuel Cells

1997 ◽  
Author(s):  
Rioji Anahara
Keyword(s):  
Fuel Cell ◽  
Environmental Impact ◽  
21St Century ◽  
Power Plants ◽  
Global Environment ◽  
Development Status ◽  
Air Movement ◽  
Clean Air ◽  
Principal Advantage

One of the most important tasks through the 21st century is to ensure a stable supply of energy and maintain a balanced clean global environment. The principal advantage of fuel cell power plants lies in their favorable environmental impact. Fuel cell development is of utmost important in the light of the recent worldwide clean air movement.

Particulate and Emulsion Sorting Using Microfluidics

2014 ◽  
Author(s):  
Li Lu ◽  
Rebecca M. Irwin ◽  
Jeffrey W. Schertzer ◽  
Paul R. Chiarot
Keyword(s):  
Microfluidic Device ◽  
High Throughput ◽  
Hydrodynamic Forces ◽  
Fluid Stream ◽  
High Concentration ◽  
Flow Rates ◽  
Membrane Biology ◽  
Wide Range ◽  
Delivery Vehicles ◽  
Oil Emulsions

We report on a microfluidic device capable of sorting nanoscale particulates and water-in-oil emulsions at high-throughput. The device is passive, relying solely on hydrodynamic forces and the emulsion mass to achieve separation. We use the microfluidic device to deliver surfactants and lipids to the emulsion surface. This is achieved by immersing the emulsions in a fluid stream with a high concentration of the nano-particulates. The particulates assemble on the surface of the emulsions as they are transported along the stream. The emulsions are then transferred (i.e. separated) into a second fluid stream that is devoid of surrounding material. The performance of the device is evaluated for a range of flow rates, nano-particulate concentrations, and emulsion sizes. We report separation efficiencies that exceed current technologies over a wide range of flow rates. The microfluidic device can be used to produce delivery vehicles for pharmaceuticals and models for membrane biology studies.

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