Volumetric analysis of fish swimming hydrodynamics using synthetic aperture particle image velocimetry

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 81-86).Abstract This thesis details the implementation of a three-dimensional PIV system to study the hydrodynamics of freely swimming Giant Danio (Danio aequipinnatus). Volumetric particle fields are reconstructed using synthetic aperture refocusing. The experiment is designed with minimal constraints on animal behavior to ensure that natural swimming occurs. Resultantly, the fish exhibits a variety of forward swimming and turning behaviors at speeds between 1.0-1.5 body-lengths/second. During these maneuvers, the imaging system is also used to track and reconstruct the fish body. The resultant velocity fields are used to characterize the size and shape of the vortex rings shed by the fish during forward swimming and turning. Results show clearly isolated and linked vortex rings in the wake structure, as well as the thrust jet coming off of a visual hull reconstruction of the fish body. Depending on the maneuver, the amount of symmetry in the wake varies, emphasizing the shortcomings of a single planar slice to characterize these behaviors. The additional information provided by volumetric measurement is also used to analyze the momentum in the fish's wake. The circulation of the vortex rings is computed across several slices of the ring taken through its center axis and analyzed over time. Circulation can be used to compute the fluid impulse in the vortex ring to better understand propulsive performance. The measured impulse, combined with visualization of the wake, provides a comparison between forward swimming and turning based on volumetric measurements. The development of this system lays a foundation for further volumetric studies of swimming hydrodynamics.by Leah Rose Mendelson.S.M

A brief report on the associations amongst social media use, gender, and body esteem in a UK student sample

Research into the effects of social media on personal wellbeing have been controversial in recent years, with recent research highlighting links between social media use and body esteem. This conceptual replication study aimed to explore relationships amongst social media use, body esteem and gender amongst UK university students (n=100). Participants completed measures of social media use and body image esteem. It was hypothesised that social media intensity and usage would negatively predict body esteem, with high social media intensity relating to lower body esteem. We find that gender was the only significant predictor of body esteem, with women having lower body esteem compared to men. We were unable to replicate previous findings, as our findings show no relationships amongst social media intensity, use, and body esteem

3D experimental study of archer fish jumping

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 197-209).Jumping for aerial prey from an aquatic environment requires both propulsive power and precise aim to succeed. Archer sh, better known for their spitting abilities, will jump multiple body lengths out of the water for prey capture, especially in competitive foraging scenarios. Prior to jumping, archer sh aim from a stationary position with the snout located directly below the water's surface. Rapid acceleration to a ballistic velocity sucient for reaching the prey height occurs with a mere body length to travel before the sh leaves the water completely and experiences a thousandfold drop in force-producing ability. In addition to speed, accuracy and stability are crucial for successful feeding by jumping. The combination of these factors in the archer fish's unique jumping strategy may bring new insights to the design of underwater vehicles capable of spatially-constrained acceleration or water exit. This thesis examines the hydrodynamic mechanisms underlying the archer fish's jumping abilities. First, behavioral and kinematic trends from five specimens are presented to elucidate key jump attributes. Modulation of oscillatory body kinematics and use of multiple ns for force production are identied as methods through which the sh can meet requirements for both acceleration and stabilization in limited space. In addition, flow field measurements made using planar particle image velocimetry (PIV) reveal vortical wake structures originating from the caudal, dorsal, anal, and pectoral ns. Exact n interactions cannot be identied from a single slice through the wake, suggesting a need for further three-dimensional study. To address this limitation, a volumetric particle image velocimetry system meeting specfic requirements for the study of jumping archer sh is developed. The multi-camera measurement system is based on the synthetic aperture particle image velocimetry (SAPIV) technique. The SAPIV system provides time-resolved measurements of both the fish's wake and its aerial trajectory, working within the optical access constraint created by the sh jumping from directly below the water's surface. Image processing improvements to measure fin-fin and n-body interactions despite partially-occluded tracer particles are also implemented. The capabilities of the system to make time-resolved measurements of multiple ns during a single jump are demonstrated. To utilize the 3D velocity field data provided by this technique, approaches to quantitative wake analysis suitable for isolated three-dimensional wake structures and interacting multi-vortex wakes are presented. Finally, detailed 3D SAPIV measurements of ow from the archer fish's dorsal, anal, and caudal ns at jump onset are obtained. Quantitative wake measurements reveal how variations in tail kinematics relate to thrust production throughout the course of a jumping maneuver and over a range of jump heights. Measurements also highlight momentum ux into the wake emanating from the upstream dorsal and anal ns. These ow structures augment the caudal n wake during subsequent tailbeats. By performing measurements in 3D, the timing, interactions, and relative contributions to thrust and lateral forces from each n can be evaluated, elucidating the complex hydrodynamics that enable archer sh water exit.by Leah Rose Mendelson.Ph. D

Quantitative wake analysis of a freely swimming fish using 3D synthetic aperture PIV

Synthetic aperture PIV (SAPIV) is used to quantitatively analyze the wake behind a giant danio (Danio aequipinnatus) swimming freely in a seeded quiescent tank. The experiment is designed with minimal constraints on animal behavior to ensure that natural swimming occurs. The fish exhibits forward swimming and turning behaviors at speeds between 0.9 and 1.5 body lengths/second. Results show clearly isolated and linked vortex rings in the wake structure, as well as the thrust jet coming off of a visual hull reconstruction of the fish body. As a benchmark for quantitative analysis of volumetric PIV data, the vortex circulation and impulse are computed using methods consistent with those applied to planar PIV data. Volumetric momentum analysis frameworks are discussed for linked and asymmetric vortex structures, laying a foundation for further volumetric studies of swimming hydrodynamics with SAPIV. Additionally, a novel weighted refocusing method is presented as an improvement to SAPIV reconstruction

Multi-camera volumetric PIV for the study of jumping fish

Archer fish accurately jump multiple body lengths for aerial prey from directly below the free surface. Multiple fins provide combinations of propulsion and stabilization, enabling prey capture success. Volumetric flow field measurements are crucial to characterizing multi-propulsor interactions during this highly three-dimensional maneuver; however, the fish’s behavior also drives unique experimental constraints. Measurements must be obtained in close proximity to the water’s surface and in regions of the flow field which are partially-occluded by the fish body. Aerial jump trajectories must also be known to assess performance. This article describes experiment setup and processing modifications to the three-dimensional synthetic aperture particle image velocimetry (SAPIV) technique to address these challenges and facilitate experimental measurements on live jumping fish. The performance of traditional SAPIV algorithms in partially-occluded regions is characterized, and an improved non-iterative reconstruction routine for SAPIV around bodies is introduced. This reconstruction procedure is combined with three-dimensional imaging on both sides of the free surface to reveal the fish’s three-dimensional wake, including a series of propulsive vortex rings generated by the tail. In addition, wake measurements from the anal and dorsal fins indicate their stabilizing and thrust-producing contributions as the archer fish jumps

Impact of age on the host response to sepsis in a murine model of fecal-induced peritonitis

Abstract Introduction Despite older adults being more vulnerable to sepsis, most preclinical research on sepsis has been conducted using young animals. This results in decreased scientific validity since age is an independent predictor of poor outcome. In this study, we explored the impact of aging on the host response to sepsis using the fecal-induced peritonitis (FIP) model developed by the National Preclinical Sepsis Platform (NPSP). Methods C57BL/6 mice (3 or 12 months old) were injected intraperitoneally with rat fecal slurry (0.75 mg/g) or a control vehicle. To investigate the early stage of sepsis, mice were culled at 4 h, 8 h, or 12 h to investigate disease severity, immunothrombosis biomarkers, and organ injury. Mice received buprenorphine at 4 h post-FIP. A separate cohort of FIP mice were studied for 72 h (with buprenorphine given at 4 h, 12 h, and then every 12 h post-FIP and antibiotics/fluids starting at 12 h post-FIP). Organs were harvested, plasma levels of Interleukin (IL)-6, IL-10, monocyte chemoattract protein (MCP-1)/CCL2, thrombin-antithrombin (TAT) complexes, cell-free DNA (CFDNA), and ADAMTS13 activity were quantified, and bacterial loads were measured. Results In the 12 h time course study, aged FIP mice demonstrated increased inflammation and injury to the lungs compared to young FIP mice. In the 72 h study, aged FIP mice exhibited a higher mortality rate (89%) compared to young FIP mice (42%) (p < 0.001). Aged FIP non-survivors also exhibited a trend towards elevated IL-6, TAT, CFDNA, CCL2, and decreased IL-10, and impaired bacterial clearance compared to young FIP non-survivors. Conclusion To our knowledge, this is the first study to investigate the impact of age on survival using the FIP model of sepsis. Our model includes clinically-relevant supportive therapies and inclusion of both sexes. The higher mortality rate in aged mice may reflect increased inflammation and worsened organ injury in the early stage of sepsis. We also observed trends in impaired bacterial clearance, increase in IL-6, TAT, CFDNA, CCL2, and decreased IL-10 and ADAMTS13 activity in aged septic non-survivors compared to young septic non-survivors. Our aging model may help to increase the scientific validity of preclinical research and may be useful for identifying mechanisms of age-related susceptibility to sepsis as well as age-specific treatment strategies

Impact of age on the host response to sepsis in a murine model of fecal-induced peritonitis

Abstract Introduction Despite older adults being more vulnerable to sepsis, most preclinical research on sepsis has been conducted using young animals. This results in decreased scientific validity since age is an independent predictor of poor outcome. In this study, we explored the impact of aging on the host response to sepsis using the fecal-induced peritonitis (FIP) model developed by the National Preclinical Sepsis Platform (NPSP). Methods C57BL/6 mice (3 or 12 months old) were injected intraperitoneally with rat fecal slurry (0.75 mg/g) or a control vehicle. To investigate the early stage of sepsis, mice were culled at 4 h, 8 h, or 12 h to investigate disease severity, immunothrombosis biomarkers, and organ injury. Mice received buprenorphine at 4 h post-FIP. A separate cohort of FIP mice were studied for 72 h (with buprenorphine given at 4 h, 12 h, and then every 12 h post-FIP and antibiotics/fluids starting at 12 h post-FIP). Organs were harvested, plasma levels of Interleukin (IL)-6, IL-10, monocyte chemoattract protein (MCP-1)/CCL2, thrombin-antithrombin (TAT) complexes, cell-free DNA (CFDNA), and ADAMTS13 activity were quantified, and bacterial loads were measured. Results In the 12 h time course study, aged FIP mice demonstrated increased inflammation and injury to the lungs compared to young FIP mice. In the 72 h study, aged FIP mice exhibited a higher mortality rate (89%) compared to young FIP mice (42%) (p < 0.001). Aged FIP non-survivors also exhibited a trend towards elevated IL-6, TAT, CFDNA, CCL2, and decreased IL-10, and impaired bacterial clearance compared to young FIP non-survivors. Conclusion To our knowledge, this is the first study to investigate the impact of age on survival using the FIP model of sepsis. Our model includes clinically-relevant supportive therapies and inclusion of both sexes. The higher mortality rate in aged mice may reflect increased inflammation and worsened organ injury in the early stage of sepsis. We also observed trends in impaired bacterial clearance, increase in IL-6, TAT, CFDNA, CCL2, and decreased IL-10 and ADAMTS13 activity in aged septic non-survivors compared to young septic non-survivors. Our aging model may help to increase the scientific validity of preclinical research and may be useful for identifying mechanisms of age-related susceptibility to sepsis as well as age-specific treatment strategies