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Academic literature on the topic 'Leaf fluttering'
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Journal articles on the topic "Leaf fluttering"
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Wang, Yunfei, Weidong Jia, Shiqun Dai, et al. "Analytical Methods for Wind-Driven Dynamic Behavior of Pear Leaves (Pyrus pyrifolia)." Agriculture 15, no. 8 (2025): 886. https://doi.org/10.3390/agriculture15080886.
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The fluttering of leaves under wind fields significantly impacts the efficiency and precision of agricultural spraying. However, existing spraying technologies often overlook the complex mechanisms of wind–leaf interactions. This study integrates the fine-tuned Segment Anything Model 2 with multi-dimensional dynamic behavior analysis to provide a systematic approach for investigating leaf fluttering under wind fields. First, a segmentation algorithm based on Principal Component Analysis was employed to eliminate background interference in leaf fluttering data. The results showed that the segmentation algorithm achieved an Intersection over Union (IoU) ranging from 98.2% to 98.7%, with Precision reaching 99.0% to 99.5%, demonstrating high segmentation accuracy and reliability. Building on this, experiments on leaf segmentation and tracking in dynamic scenarios were conducted using the SAM2-FT model. The results indicated that SAM2-FT effectively captured the dynamic behavior of leaves by integrating spatiotemporal information, achieving Precision and AP50/% values exceeding 97%. Its overall performance significantly outperformed mainstream YOLO-series models. In the analysis of dynamic response patterns, the Hilbert transform and time-series quantification methods were introduced to reveal the amplitude, frequency, and trajectory characteristics of a leaf fluttering under wind fields across three dimensions: area, inclination angle, and centroid. This comprehensive analysis highlights the dynamic response characteristics of leaves to wind field perturbations.
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HASEBA, Tetsuya, Daijiro ITO, Hiroto ISHIDA, Kazuno OHNO, and Chiemi TAKAHASHI. "Boundary-Layer Transfer Coefficient for a Fluttering Leaf." Journal of Agricultural Meteorology 41, no. 4 (1986): 311–19. http://dx.doi.org/10.2480/agrmet.41.311.
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HASEBA, Tetsuya, Daijiro ITO, and Atsushi NISHIKAWA. "Boundary-layer transfer coefficient for a fluttering leaf. II. Model experiments to evaluate effects of leaf inclination and fluttering on transfer coefficient." Journal of Agricultural Meteorology 43, no. 2 (1987): 105–11. http://dx.doi.org/10.2480/agrmet.43.105.
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Brown, Brian, and Wendy Porras. "Extravagant female sexual display in a Megaselia Rondani species (Diptera: Phoridae)." Biodiversity Data Journal 3 (March 6, 2015): e4368. https://doi.org/10.3897/BDJ.3.e4368.
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The behavior of females of a species of <i>Megaselia</i> is described. Females perch on leaves and occasionally "dance", fluttering their wings while rapidly running on the leaf surface. During this dance, they evert bright white abdominal sacs that apparently constitute part of a visual display to attract males. The evolutionary basis of these behaviors is discussed.
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Derr, Julien, Renaud Bastien, Étienne Couturier, and Stéphane Douady. "Fluttering of growing leaves as a way to reach flatness: experimental evidence on Persea americana." Journal of The Royal Society Interface 15, no. 138 (2018): 20170595. http://dx.doi.org/10.1098/rsif.2017.0595.
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Simple leaves show unexpected growth motions: the midrib of the leaves swings periodically in association with buckling events of the leaf blade, giving the impression that the leaves are fluttering. The quantitative kinematic analysis of this motion provides information about the respective growth between the main vein and the lamina. Our three-dimensional reconstruction of an avocado tree leaf shows that the conductor of the motion is the midrib, presenting continuous oscillations and inducing buckling events on the blade. The variations in the folding angle of the leaf show that the lamina is not passive: it responds to the deformation induced by the connection to the midrib to reach a globally flat state. We model this movement as an asymmetric growth of the midrib, which directs an inhomogeneous growth of the lamina, and we suggest how the transition from the folded state to the flat state is mechanically organized.
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Byun, Junghwan, Minjo Park, Sang-Min Baek, et al. "Underwater maneuvering of robotic sheets through buoyancy-mediated active flutter." Science Robotics 6, no. 53 (2021): eabe0637. http://dx.doi.org/10.1126/scirobotics.abe0637.
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Falling leaves flutter from side to side due to passive and intrinsic fluid-body coupling. Exploiting the dynamics of passive fluttering could lead to fresh perspectives for the locomotion and manipulation of thin, planar objects in fluid environments. Here, we show that the time-varying density distribution within a thin, planar body effectively elicits minimal momentum control to reorient the principal flutter axis and propel itself via directional fluttery motions. We validated the principle by developing a swimming leaf with a soft skin that can modulate local buoyancy distributions for active flutter dynamics. To show generality and field applicability, we demonstrated underwater maneuvering and manipulation of adhesive and oil-skimming sheets for environmental remediation. These findings could inspire future intelligent underwater robots and manipulation schemes.
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Moulia, Bruno, Stéphane Douady, and Olivier Hamant. "Fluctuations shape plants through proprioception." Science 372, no. 6540 (2021): eabc6868. http://dx.doi.org/10.1126/science.abc6868.
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Plants constantly experience fluctuating internal and external mechanical cues, ranging from nanoscale deformation of wall components, cell growth variability, nutating stems, and fluttering leaves to stem flexion under tree weight and wind drag. Developing plants use such fluctuations to monitor and channel their own shape and growth through a form of proprioception. Fluctuations in mechanical cues may also be actively enhanced, producing oscillating behaviors in tissues. For example, proprioception through leaf nastic movements may promote organ flattening. We propose that fluctuation-enhanced proprioception allows plant organs to sense their own shapes and behave like active materials with adaptable outputs to face variable environments, whether internal or external. Because certain shapes are more amenable to fluctuations, proprioception may also help plant shapes to reach self-organized criticality to support such adaptability.
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Martin, Daniel, Vijay Singh, Mohamed A. Latheef, and Muthukumar Bagavathiannan. "Spray Deposition on Weeds (Palmer Amaranth and Morningglory) from a Remotely Piloted Aerial Application System and Backpack Sprayer." Drones 4, no. 3 (2020): 59. http://dx.doi.org/10.3390/drones4030059.
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This study was designed to determine whether a remotely piloted aerial application system (RPAAS) could be used in lieu of a backpack sprayer for post-emergence herbicide application. Consequent to this objective, a spray mixture of tap water and fluorescent dye was applied on Palmer amaranth and ivyleaf morningglory using an RPAAS at 18.7 and 37.4 L·ha−1 and a CO2-pressurized backpack sprayer at a 140 L·ha−1 spray application rate. Spray efficiency (the proportion of applied spray collected on an artificial sampler) for the RPAAS treatments was comparable to that for the backpack sprayer. Fluorescent spray droplet density was significantly higher on the adaxial surface for the backpack sprayer treatment than that for the RPAAS platforms. The percent of spray droplets on the abaxial surface for the RPAAS aircraft at 37.4 L·ha−1 was 4-fold greater than that for the backpack sprayer at 140 L·ha−1. The increased spray deposition on the abaxial leaf surfaces was likely caused by rotor downwash and wind turbulence generated by the RPAAS which caused leaf fluttering. This improved spray deposition may help increase the efficacy of contact herbicides. Test results indicated that RPAASs may be used for herbicide application in lieu of conventional backpack sprayers.
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You, Cheng-Shu, Ming-Jyh Chern, Dedy Zulhidayat Noor, and Tzyy-Leng Horng. "Numerical Investigation of Freely Falling Objects Using Direct-Forcing Immersed Boundary Method." Mathematics 8, no. 9 (2020): 1619. http://dx.doi.org/10.3390/math8091619.
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The fluid-structure interaction of solid objects freely falling in a Newtonian fluid was investigated numerically by direct-forcing immersed boundary (DFIB) method. The Navier–Stokes equations are coupled with equations of motion through virtual force to describe the motion of solid objects. Here, we rigorously derived the equations of motion by taking control-volume integration of momentum equation. The method was validated by a popular numerical test example describing the 2D flow caused by the free fall of a circular disk inside a tank of fluid, as well as 3D experimental measurements in the sedimentation of a sphere. Then, we demonstrated the method by a few more 2D sedimentation examples: (1) free fall of two tandem circular disks showing drafting, kissing and tumbling phenomena; (2) sedimentation of multiple circular disks; (3) free fall of a regular triangle, in which the rotation of solid object is significant; (4) free fall of a dropping ellipse to mimic the falling of a leaf. In the last example, we found rich falling patterns exhibiting fluttering, tumbling, and chaotic falling.
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Wang, Le, Lirong Xiang, Lie Tang, and Huanyu Jiang. "A Convolutional Neural Network-Based Method for Corn Stand Counting in the Field." Sensors 21, no. 2 (2021): 507. http://dx.doi.org/10.3390/s21020507.
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Accurate corn stand count in the field at early season is of great interest to corn breeders and plant geneticists. However, the commonly used manual counting method is time consuming, laborious, and prone to error. Nowadays, unmanned aerial vehicles (UAV) tend to be a popular base for plant-image-collecting platforms. However, detecting corn stands in the field is a challenging task, primarily because of camera motion, leaf fluttering caused by wind, shadows of plants caused by direct sunlight, and the complex soil background. As for the UAV system, there are mainly two limitations for early seedling detection and counting. First, flying height cannot ensure a high resolution for small objects. It is especially difficult to detect early corn seedlings at around one week after planting, because the plants are small and difficult to differentiate from the background. Second, the battery life and payload of UAV systems cannot support long-duration online counting work. In this research project, we developed an automated, robust, and high-throughput method for corn stand counting based on color images extracted from video clips. A pipeline developed based on the YoloV3 network and Kalman filter was used to count corn seedlings online. The results demonstrate that our method is accurate and reliable for stand counting, achieving an accuracy of over 98% at growth stages V2 and V3 (vegetative stages with two and three visible collars) with an average frame rate of 47 frames per second (FPS). This pipeline can also be mounted easily on manned cart, tractor, or field robotic systems for online corn counting.
Conference papers on the topic "Leaf fluttering"
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Yuk, Jisoo, Joseph Lee, Caroline Graves, and Sunghwan Jung. "Visual Measurements of Fluttering Leaf to Quantify Internal Water Stress." In 2022 Houston, Texas July 17-20, 2022. American Society of Agricultural and Biological Engineers, 2022. http://dx.doi.org/10.13031/aim.202200404.
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Schüler, Eckhard, and Stephan Faulhaber. "Preventing Tilting Pad Fluttering by Using Elastic Pad Fixation." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-125725.
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Abstract Tilting pad fluttering is a well-known phenomenon in journal and thrust bearings. It can occur on unloaded pads where the buildup of hydrodynamic pressure is not or not sufficiently achieved, which can be attributed to several causes. In severe forms of pad fluttering there is repetitive contact between the pad and the shaft. This can lead to bearing damages and, in the case of journal bearings, trigger subsynchronous rotor vibration with high amplitudes. There are various approaches to solving the problem, some of which relate to the elimination of existing pad fluttering. Proactive approaches are also described in the literature, but these are often associated with restrictions or certain disadvantages, meaning that these measures are not always applied in practice. To investigate a new approach, tilting pad fluttering was first caused and measured during experimental investigations on a conventional bearing. The bearing was then modified with the design solution “elastic pad fixation” which reliably prevented tilting pad fluttering without impairing the general properties and performance of the bearing.
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Đokić, Jelena, Jelica Davidović, and Jelica Dimitrijević. "THE IMPACT OF HEART RHYTHM DISORDERS ON TRAFFIC SAFETY." In Conference Road Safety in Local Community. Road Safety in Local Community, 2024. http://dx.doi.org/10.46793/rsaflc24.373dj.
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Heart rhythm disorders occur due to disturbances in the creation or conduction of impulses that lead to the contraction of the heart and the pumping of blood into the body. Symptoms may include palpitations, fast/slow heartbeat, fluttering in the chest, chest pain, shortness of breath, fainting, dizziness, weakness and loss of consciousness. While driving, there may be a drop in concentration, reduced attention, dizziness that reduces body coordination and loss of onsciousness. Due to the appearance of the mentioned symptoms, there may be a traffic accident and endangering traffic safety. The aim of this work is to show the potential risks of driving a motor vehicle for people with heart rhythm disorders and the measures that can be taken to improve the traffic safety of this category of road users.
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Hidalgo, Pablo, and Ari Glezer. "Small-Scale Vorticity Induced by a Self-Oscillating Fluttering Reed for Heat Transfer Augmentation in Air Cooled Heat Sinks." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48511.
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Heat transfer in a high aspect ratio, rectangular mm-scale channel that models a segment of a high-performance, air-cooled heat-sink is enhanced by deliberate formation of unsteady small-scale vortical motions. These small-scale motions are induced by self-fluttering, cantilevered planar thin-film reeds that are placed along the channel’s centerline. Heat transfer is enhanced by significant increases in both the local heat transfer coefficient at the fins surfaces, and in the mixing between the thermal boundary layers and the cooler core flow. The present investigation characterizes the thermal performance enhancement by reed actuation compared to the base flow (in the absence of the reeds) in terms of increased power dissipation over a range of flow rates, along with the associated fluid power. It is shown that because the cooling flow rate that is needed to sustain a given heat flux at a given surface temperature is almost two times higher than in the presence of the reeds, the reeds lead to a four-fold increase in thermal performance (as measured by the ratio of power dissipated to fluid power). The thermal effectiveness of the reeds is tested in a multi-channel heat sink, and it is shown that the improvement in heat transfer coefficient of the base flow is similar to that of the single channel.
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Okamoto, Satoru. "Structural Dynamics and Response of Roof Tiles Under Wind Loading." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93046.
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A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.
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Okamoto, Satoru. "Wind Tunnel Tests on Flow-Induced Vibrations and Scattering of Japanese Slates." In ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55016.
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A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.
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Okamoto, Satoru. "Effect on Slates by Wind Over Roof of Japanese Residence." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10575.
Full textAbstract:
A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.
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Okamoto, Satoru. "Interaction Between Wind Loading and Japanese Slates: Effect on Vibration and Scattering." In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61093.
Full textAbstract:
A series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibrations for the roof tiles were measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequencies of the roof tiles were analyzed by the impulse force hammer test method. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is similar to that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. The values of the frequencies for the oscillating relate to the values of natural frequencies of the vibration.
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Botros, K. K. "Selection Criteria of Spring Stiffness for Nozzle Type Check Valves in Compressor Station Applications." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45003.
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Nozzle type check valves are often employed in compressor stations in three locations: compressor outlet, station discharge and station by-pass. The fundamental design concept of these valves is based on creating a converging diverging flow through the valve internal geometry such that a minimum area is achieved at a location corresponding to the back of the check valve disc at fully open position. This will ensure maximum hydrodynamic force coefficient which allows the valve to be fully open with minimum flow. Spring forces and stiffness determine the performance of this type of check valves and impact the overall operation and integrity of compressor station. This paper examines the effects of various spring characteristics and stiffness in relation to the compressor and station flow characteristics. The results show that when the spring forces are higher than the maximum hydrodynamic force at minimum flow, the disc will not be at fully open position, which will give rise to disc fluttering and potential for cyclic high velocity impact between components of the internal valve assembly. This could lead to self destruction of the check valve and subsequent risk of damage to the compressor unit itself. The paper also points to the fact that the spring selection criteria for a unit check valve are different than that for station and bypass check valves. An example of a case study with actual field data from a high pressure ratio compressor station employing this type of check valves is presented to illustrate the associated dynamic phenomena and fluid-structure interaction within the internal assembly of the check valve.
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Mointire, V. L., A. J. Frangos, G. B. Rhee, G. S. Eskin, and R. E. Hall. "RHEOLOGY AND CELL ACTIVATION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643988.
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The subject of this work is to examine the hypothesis that some sublytic levels of mechanical perturbation of cells can stimulate cell metabolism. As a marker metabolite, we have chosen arachidonic acid. Principal metabolites for platelets include the cyclooxygenase product thromboxane A2(TXA2) and the lipoxygenase product 12-hydroperoxy-eicosatetraenoic acid (12-HPETE). Polymorphonuclear leukocytes (PMNLs) initally produce principally 5-HPETE, somtimes leading to the formation leukotrienes, though many other metabolites of arachidonic acid have been isolated from activated neutrophils. Human umbilical vein endothelial cells utilize arachidonic acid to produce mainly prostaglandin I2(PGI2). All of these metabolites are biologically active and modulate cell function - sometimes in quite contrasting ways. We will show that levels of sublytic mechanical stress exposure can stimulate arachidonic acid metabolism in all three of the cell types mentioned above. The biological implications of this stress/metabolism coupling may be quite far reaching.Human platelets, leukocytes and endothelial cells all appear to be sensitive to mechanical stress induced activation of arachidonic acid metabolism. Sheared PRP exhibited greatly increased synthesis of 12-HETE and surprisingly little thromboxane B2 production. This indicates that shear stress stimulation of platelets may produce quite different arachidonic acid metabolism than that seen with many direct chemical stimuli, such as thrombin or collagen.Our data demonstrate that a substance derived from shear induced platelet activation may activate the C-5 lipoxygenase of human PMNL under stress, leading to the production of LTB4. We hypothesize that this substance maybe 12-HPETE. LTB4 is known to be a very potent chemotactic factor and to induce PMNL aggregation and degranulation. Our studies provide further evidence that lipoxygenase products of one cell type can modulate production of lipoxygenase products in a second cell type, and that shear stress can initiate cell activation. This kind of coupling could have far reaching implications in terms of our understanding of cell/cell interaction in flowing systems, such as acute inflammation, artificial organ implantation and tumor metastasis.The data on PGI2 production by endothelial cells demonstrate that physiological levels of shear stress can dramatically increase arachidonic acid metabolism. Step increases in shear stress lead to a burst in production of PGI2 which decayed to a steady state value in several minutes. This longer term stimulation of prostacyclin production rate increased linearly with shear stress over the range of 0-24 dynes/cm2. In addition, pulsatile flow of physiological frequency and amplitude caused approximately 2.4 times the PGI2 production rate as steady flow with the same mean stress. Although only PGI2 was measured, it is likely that other arachidonic acid metabolites of endothelial cells are also affected by shear stress.The ability of cells to respond to external stimuli involves the transduction of a signal across the plasma membrane. One such external stimulus appears to be fluid shear stress. Steady shear flow induces cell rotation in suspended cells, leading to a periodic membrane loading, with the peak stress proportional to the bulk shear stress. On anchorage-dependent cells, such as endothelial cells, steady shear stress may act by amplifying the natural thermal or Brownian fluttering or rippling of the membrane. There are several possible mechanisms by which shear stress induced membrane perturbation could mimic a hormone/receptor interaction, leading to increased intracellular metabolism. Shear stress may induce increased phospholipase C activity, caused by translocation of the enzyme, increased substrate (arachidonic acid) pool availability to phospholipase C (particularly from that stored in phosphoinositols) due to shear-induced membrane movements or changes in membrane fluidity, direct activation of calcium - activated phospholipase A2 by increased membrane calcium ion permeability, or most probably by a combination of these mechanisms.