High-speed Digital Imaging System Research Articles

Nasal polyps show decreased mucociliary transport despite vigorous ciliary beating

ObjectiveMucociliary transport function in the airway mucosa is essential for maintaining a clean mucosal surface. This function is impaired in upper and lower airway diseases. Nasal polyps are a noticeable pathological feature that develop in some of the patients with chronic rhinosinusitis. Like ordinary nasal mucosae, nasal polyps have a ciliated pseudostratified epithelium with vigorous ciliary beating. We measured ex vivo Mucociliary Transport Velocity (MCTV) and Ciliary Beat Frequency (CBF) and explored the expressions of Planar Cell Polarity (PCP) proteins in nasal polyps in comparison with turbinate mucosae. MethodsInferior turbinates and nasal polyps were surgically collected from patients with chronic rhinosinusitis. Ex vivo MCTV and CBF were measured using a high-speed digital imaging system. Expressions of PCP proteins were explored by fluorescence immunohistochemistry and quantitative RT-PCR. ResultsThe MCTV of nasal polyps was significantly lower than that of the turbinates (7.43 ± 2.01 vs. 14.56 ± 2.09 μm/s; p = 0.0361), whereas CBF did not differ between the two tissues. The MCTV vector was pointed to the posteroinferior direction in all turbinates with an average inclination angle of 41.0 degrees. Immunohistochemical expressions of Dishevelled-1, Dishevelled-3, Frizzled3, Frizzled6, Prickle2 and Vangl2 were lower in the nasal polyps than in the turbinates. Confocal laser scanning microscopy showed that Frizzled3 was localized along the cell junction on the apical surface. The expression levels of mRNAs for Dishevelled-1, Dishevelled-3 and Frizzled3 in the nasal polyps were also decreased in comparison with the turbinates. ConclusionThese results indicate that muco ciliary transport in nasal polyps is impaired although vigorous ciliary beating is maintained, and that the impairment may be caused by a decrease in Dishevelled/Frizzled proteins and resultant PCP disarrangement. Level of evidenceLevel 3.

Optimization analysis of droplet dust removal mass on tilted superhydrophobic surface based on regulating PV tilt angle and drop height

This study proposes a method for adjusting the mass of droplet dust removal based on droplet height and photovoltaic tilt angle, utilizing a model of droplet motion on inclined superhydrophobic surfaces. A droplet's motion on dusty and inclined hydrophobic surfaces is analyzed using a high-speed digital imaging system. The impact of drop height and photovoltaic tilt angle on the mass of dust removed by the droplet is experimentally investigated. The findings reveal that the mass of droplet dust removal increases quickly with the rise of drop height and tilt angle. The modification of the tilt angle yields a more pronounced enhancement in dust removal efficiency. At an angle of 40°, the drop height rises from 0.5 cm to 10 cm, leading to an extra 6.6 mg of dust removal per drop. At a height of 0 cm, the mass increased by 10.62 mg after raising the angle from 10° to 40°. Droplet impact on the surface is prone to shattering. The emitted minute droplets will adhere to the surface and form a cohesive ash band, with a visible light transmission rate of merely 67 %. When a droplet rolls on a tilted superhydrophobic surface, there's a dust removal threshold. Once exceeded, the rolling shape tends to become ellipsoidal. The experimental and model predictions of droplet dust removal mass are of the same order of magnitude and differ by a few micrograms. Therefore, the theoretical model can be used to improve the efficiency of droplet dust removal by adjusting the drop height and photovoltaic angle.

Liquid jet breakup and spray formation with annular swirl air

Spray formation is important for liquid fuel combustion from the perspective of emissions and sustaining combustion. Employing swirl flow increases turbulent intensity, which leads to a much-desired outcome for sprays in a reduction of the jet breakup length, better air-fuel mixing and vaporization characteristics, and stabilizes the combustion operation. The present investigation endeavors to characterize the near field spray developing region of a swirl airblast atomizer. The high-speed digital imaging system is employed to record the unsteady dynamics when the liquid jet breaks to form mono-disperse or poly-disperse drop size distribution depending upon the atomizing air to liquid jet momentum ratio. The coherent spatial nature of the atomization process is identified using Proper Orthogonal Decomposition (POD) of acquired high-speed images of the spray in the near field. The simultaneous droplet size and velocities (axial, radial, and tangential) are measured through Phase Doppler Particle Analyzer (PDPA) technique to quantify the effect of the flow field on spray characteristics in the near field of an atomizer. Joint probability distributions of drop size and velocity along with Weber number distribution provide insight into the spray developing near field region. The spatial variations in the drop size distribution are found to be a function of turbulent Weber number (Wet) and shear Weber number (Wes) distribution. Double Gaussian function representing superimposed distributions for larger and smaller droplets provides the highest confidence fit for both velocity and dropsize distributions throughout the flow field. The volume-averaged statistics are proposed for a better description of the actual spray quality.

A water droplet-cleaning of a dusty hydrophobic surface: influence of dust layer thickness on droplet dynamics

Water droplet cleaning of a dusty hydrophobic surface is examined. Environmental dust are used in the experiments and cloaking velocity of a dust layer by a droplet fluid is measured and hemi-wicking conditions for the dust layer are analyzed adopting the pores media wick structure approach. A droplet motion on dusty and inclined hydrophobic surface is analyzed using a high speed digital imaging system. Influences of dust layer thickness, droplet volume, and surface inclination angle on the mechanisms of dust removal by a rolling droplet are evaluated. The findings revealed that dust cloaking velocity decreases exponentially with time. The droplet fluid can cloak the dust layer during its transition on the dusty surface. The transition period of droplet wetted length on the dusty surface remains longer than the cloaking time of the dust layer by the droplet fluid. Translational velocity of rolling droplet is affected by the dust layer thickness, which becomes apparent for small volume droplets. Small volume droplet (20 µL) terminates on the thick dust layer (150 µm) at low surface inclination angle (1°). The quantity of dust picked up by the rolling droplet increases as the surface inclination angle increases. The amount of dust residues remaining on the rolling droplet path is relatively larger for the thick dust layer (150 µm) as compared to its counterpart of thin dust layer (50 µm).

Ultrasonic Welding of Glass Fiber Reinforced PP Thermoplastic Composites: An Investigation of the Outer Layer Orientation and the Fiber Volume Fraction

This paper presents an experimental study of the influence of the orientation of the outer layer of polypropeylene (PP) reinforced with E-glass fiber laminate (GF/PP) and the influence of the fiber volume fraction on the quality of the welded joint using an ultrasonic welding process. An orthogonal L 16 array (OA) design of experiment was conducted in this paper based on the Taguchi method to evaluate the effect of the orientation of the outer layer and the fiber volume fraction, on the welding process parameters; the welding energy, the amplitude of vibration, the welding pressure, the holding pressure and the holding time were considered in order to achieve a high weld quality. The experiments were carried out using a 15 kHz ultrasonic welding unit with a maximum supplied power of 4000-Watt. GF/PP laminates with fiber volume fraction of 36% and 46% were used in this paper, and the GF/PP laminates were either unidierctional or had a 90 degree outer layer orienation. A 0.127 mm thick polypropeylene film was used as a flat energy director (ED). The evaluation of the weld quality was measured by the apparent shear strength of the single lap welded joints, and by using laser shearography as a non-destructive inspection technique . The failure mechanism of the single lap joint was monitored, using a high speed digital imaging system. A combination of the highest selected level of welding energy, lowest level of amplitude, lowest level of welding pressure, and the lowest level of both hold time and hold pressure of a unidirectional GF/PP with the lowest fiber volume fraction, were found to achieve a higher apparent shear strength of the welded adherends, as compared with the apparent shear strength obtained with the presence of the flat energy director for the same level of factors. A confirmation experiment was conducted to measure the predicted apparent shear strength and compare it with the measured apparent shear strength from the test.

Dynamic ice accretion process and its effects on the aerodynamic drag characteristics of a power transmission cable model

An experimental study was conducted to examine the dynamic ice accretion process over the surface of a high-voltage power transmission cable model and characterize the effects of the ice accretion on the aerodynamic forces acting on the test model. The experimental study was carried out by leveraging the unique Icing Research Tunnel of Iowa State University (i.e., ISU-IRT) to generate typical wet glaze and dry rime icing conditions experienced by power transmission cables. A cylindrical power cable model, which has the same diameter as that of typical power transmission cables, was mounted in ISU-IRT for the ice accretion experiments. In addition to using a high-speed digital imaging system to record the dynamic ice accretion process, a novel digital image projection (DIP) based technique was utilized to quantify the 3D shapes of the ice structures accreted on the surface of the power cable model as a function of the ice accretion time. The time variations of the aerodynamic drag force acting on the test model during the dynamic ice accretion process were also measured quantitatively by using high-sensitive force/moment traducers mounted at two ends of the test model. The ice structures accreted over the surface of the power cable model were found to change significantly under different icing conditions (i.e., rime icing vs. glaze icing). The characteristics of the aerodynamic drag acting on the test model was found to vary significantly during the dynamic ice accretion process depending on what types of ice structures were accreted on the test model. The acquired snapshots of the ice accretion images and the measured 3D shapes of the accreted ice structures on the test model are correlated with the aerodynamic force measurement results to elucidate the underlying physics.

The imaging of fluid sloshing within a closed tank undergoing oscillations

Abstract The formation of dynamic hydraulic jumps in an oscillating rectangular container was performed and videoed with a high resolution, high-speed digital imaging system. The jumps were observed traversing between the walls of the tank when the container was oscillated near the surface wave resonance frequency based on liquid depth and it was found that the directionally based hydraulic jump formation frequency matches the driven frequency. Furthermore, the spatial characteristics of the jump are dependent on the amplitude and frequency of the oscillation.

High-speed digital imaging system with a transnasal flexible fiberoptic endoscope for observing vocal fold vibration

High-speed digital imaging system with a transnasal flexible fiberoptic endoscope for observing vocal fold vibration

A novel high-speed digital imaging system for assessing vocal fold vibration

A novel high-speed digital imaging system for assessing vocal fold vibration

Glibenclamide Decreases ATP-Induced Intracellular Calcium Transient Elevation via Inhibiting Reactive Oxygen Species and Mitochondrial Activity in Macrophages

Increasing evidence has revealed that glibenclamide has a wide range of anti-inflammatory effects. However, it is unclear whether glibenclamide can affect the resting and adenosine triphosphate (ATP)-induced intracellular calcium ([Ca2+]i) handling in Raw 264.7 macrophages. In the present study, [Ca2+]i transient, reactive oxygen species (ROS) and mitochondrial activity were measured by the high-speed TILLvisION digital imaging system using the indicators of Fura 2-am, DCFDA and rhodamine-123, respectively. We found that glibenclamide, pinacidil and other unselective K+ channel blockers had no effect on the resting [Ca2+]i of Raw 264.7 cells. Extracellular ATP (100 µM) induced [Ca2+]i transient elevation independent of extracellular Ca2+. The transient elevation was inhibited by an ROS scavenger (tiron) and mitochondria inhibitor (rotenone). Glibenclamide and 5-hydroxydecanoate (5-HD) also decreased ATP-induced [Ca2+]i transient elevation, but pinacidil and other unselective K+ channel blockers had no effect. Glibenclamide also decreased the peak of [Ca2+]i transient induced by extracellular thapsigargin (Tg, 1 µM). Furthermore, glibenclamide decreased intracellular ROS and mitochondrial activity. When pretreated with tiron and rotenone, glibenclamide could not decrease ATP, and Tg induced maximal [Ca2+]i transient further. We conclude that glibenclamide may inhibit ATP-induced [Ca2+]i transient elevation by blocking mitochondria KATP channels, resulting in decreased ROS generation and mitochondrial activity in Raw 264.7 macrophages.

Culture of human nasal polyp epithelial cells at an air-liquid surface

To study the human nasal ciliated epithelial cells at an air-liquid surface (ALI) so as to establish a reliable cell culture model for nasal mucociliary transport study. The human nasal ciliated epithelial cells were cultured by low-temperature enzymatic digestion method at an air-liquid surface, the cell growth behavior was observed under the inverted phase-contrast microscope, the proliferation, confluence and differentiation of cultured cells were examined by scanning electron microscope and immunocytochemistry, the basal and stimulated ciliary beat frequency (CBF) of cultured epithelial cells were measured by using high-speed digital microscopic imaging system. Prism 4.0 software was used to analyze the data. (1) Under microscope, the cells on transwell membrane adhered well at 24 h and locked tightly to display with a cobblestone-like appearance; the monolayer cells got confluence to 80%-90% after one-week submersion culture, and thereafter exposed to air-liquid interface. (2) Under scanning electron microscope, the cilia and also the small microvilli could be observed to protrude from the cell's surface at ALI day 7; the ciliated cells differentiated well and distributed in cluster; goblet cells and nonciliated columnar cells distributed between ciliated cells. (3) Immunocytochemistry of β-tubulin IV and zona occludens-1 showed a good confluence and differentiation of cilia in cultured epithelial cells at ALI day 14, and the percentage of ciliated epithelial cells was 50%-60 %. (4) The basal CBF of cultured epithelial cells was (8.42 ± 1.24), (8.71 ± 1.11), (9.17 ± 1.11), (8.89 ± 0.91), (8.99 ± 0.91) Hz at ALI day 7, 14 , 21, 28, 35, respectively, no significant difference was found among them(F = 1.451, P > 0.05). (5) At the concentration of 100 µmol/L ATP, an exogenous stimulating agent, significantly increased the CBF of cultured epithelial cells. Air-liquid interface cultured human nasal epithelial cells by enzymatic digestion method manifest with good confluence and differentiation status; the cells could maintain differentiated morphology and physiological function close to in vivo epithelium for a long term, therefore, it may serve as an ideal cell model for mucociliary transport study.

Comparison of human nasal epithelial cells grown as explant outgrowth cultures or dissociated tissue cultures in vitro

The purpose of this study was to compare cell growth characteristics, ciliated cell differentiation, and function of human nasal epithelial cells established as explant outgrowth cultures or dissociated tissue cultures. Human nasal mucosa of the uncinate process was obtained by endoscopy and epithelial cell cultures were established by explant outgrowth or dissociated tissue culture methods. Epithelial cell growth characteristics were observed by inverted phase contrast microscopy. Ciliated cell differentiation was detected by β-tubulin IVand ZO-1 immunocytochemistry. Basal and ATP-stimulated ciliary beat frequency (CBF) was measured using a highspeed digital microscopic imaging system. Both the explant and dissociated tissue cultures established as monolayers with tight junctions and differentiated cell composition, with both types of cultures comprising ciliated and non-ciliated epithelial cells. Fibroblasts were also frequently found in explant cultures but rarely seen in dissociated tissue cultures. In both culture systems, the highest ciliated cell density appeared at 7th-10th culture day and declined with time, with the lifespan of ciliated cells ranging from 14 to 21 days. Overall, 10% of the cells in explant cultures and 20% of the cells in the dissociated tissue cultures were ciliated. These two cultures demonstrated similar ciliary beat frequency values at baseline (7.78 ± 1.99 Hz and 7.91 ± 2.52 Hz, respectively) and reacted equivalently following stimulation with 100 μM ATP. The results of this study indicate that both the explant outgrowth and dissociated tissue culture techniques are suitable for growing well-differentiated nasal ciliated and non-ciliated cells, which have growth characteristics and ciliary activity similar to those of nasal epithelial cells in vivo.

Vocal Fold Vibration of Patients with Reinke's Edema Observed Using High‐Speed Digital Imaging

Objectives: 1) Assess vocal fold vibration of patients with Reinke’s edema using high-speed digital imaging (HSDI) and videostoroboscopy. 2) Confirm that HSDI is useful for examining vocal folds with severe Reinke’s edema. Methods: Study design is observational and cross-sectional. The subjects were 7 patients with Reinke’s edema (6 severe, 1 moderate; 6 female, 1 male; 55–74 years of age, mean 64.7 years). Their vocal folds were examined with HSDI system (1200 fps) and videostoroboscopy before microphonosurgery from October 2009 through February 2012. The following characteristics of vocal fold vibration were analyzed; glottic closure, mucosal wave propagation, symmetry, phase shift, frequency difference, periodicity, and contact with false vocal fold. Postoperative examinations were also performed in 5 subjects. Results: HSDI revealed periodic or quasi-periodic vibration, anterior-posterior phase shift, and contact of true and false vocal folds in all patients before surgery. Distinct left-right asymmetry of vibration was observed in 6 patients. The vocal fold vibrations could not be tracked in 4 with severe edema. After surgery the vibrations became periodic and synchronized with strobolights in all patients. Little left-right asymmetry of vibration remained in all patients. Conclusions: Though the vocal fold vibrations with Reinke’s edema were periodic or quasi-periodic, they were often difficult to observe with videostroboscopy in severe cases. HSDI can be a very useful tool for examining the vocal folds of patients with severe Reinke’s edema, especially before surgery to find scarring and tumor.

Laser projection imaging for measurement of pediatric voice

The aim of the study was to present the development of a miniature laser projection endoscope and to quantify vocal fold length and vibratory amplitude of the pediatric glottis using high-speed digital imaging coupled with the laser endoscope. For this prospective study, absolute measurement of entire vocal fold length, membranous length of the vocal fold, and vibratory amplitude during phonation were obtained in one child (9 years old), one adult male (36 years old), and one adult female (20 years old) with the use of high-speed digital imaging, coupled with a custom-developed laser projection endoscope. The laser projection system consists of a module slip-fit sleeve with two 3-mW 650-nm laser diodes in horizontal orientation separated by a distance of 5 mm. Calibration involved projecting the laser onto grid patterns at depths ranging from 6 to 10 cm and tilt angles of 15 to -5 degrees to obtain pixel-to-millimeter conversion templates. Measurements of vocal fold length and vibratory amplitude were extracted based on methods of image processing. The system demonstrated a method for estimating vocal fold length and vibratory amplitude with a single laser point with high measurement precision. First measurements of vocal fold length (6.8 mm) and vibratory amplitude (0.25 mm) during phonation in a pediatric participant are reported. The proposed laser projection system can be used to obtain absolute length and vibratory measurements of the pediatric glottis. The projection system can be used with stroboscopy or high-speed digital imaging systems with a 70-degree rigid endoscope.

Regimes of spray formation in gas-centered swirl coaxial atomizers

Spray formation in ambient atmosphere from gas-centered swirl coaxial atomizers is described by carrying out experiments in a spray test facility. The atomizer discharges a circular air jet and an axisymmetric swirling water sheet from its coaxially arranged inner and outer orifices. A high-speed digital imaging system along with a backlight illumination arrangement is employed to record the details of liquid sheet breakup and spray development. Spray regimes exhibiting different sheet breakup mechanisms are identified and their characteristic features presented. The identified spray regimes are wave-assisted sheet breakup, perforated sheet breakup, segmented sheet breakup, and pulsation spray regime. In the regime of wave-assisted sheet breakup, the sheet breakup shows features similar to the breakup of two-dimensional planar air-blasted liquid sheets. At high air-to-liquid momentum ratios, the interaction process between the axisymmetric swirling liquid sheet and the circular air jet develops spray processes which are more specific to the atomizer studied here. The spray exhibits a periodic ejection of liquid masses whose features are dominantly controlled by the central air jet.

High-speed digital imaging laryngoscopy of the neoglottis following supracricoid laryngectomy with cricohyoidoepiglottopexy

This study aimed to analyse vocal performance and to investigate the nature of the neoglottal sound source in patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy, using a high-speed digital imaging system. High-speed digital imaging analysis of neoglottal kinetics was performed in two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy; laryngotopography, inverse filtering analysis and multiline kymography were also undertaken. In case one, laryngotopography demonstrated two vibrating areas: one matched with the primary (i.e. fundamental) frequency (75 Hz) and the other with the secondary frequency (150 Hz) at the neoglottis. In case two, laryngotopography showed two vibrating areas matched with the fundamental frequency (172 Hz) at the neoglottis. The interaction between the two areas was considered to be the sound source in both patients. The waveform of the estimated volume flow at the neoglottis, obtained by inverse filtering analysis, corresponded well to the neoglottal vibration patterns derived by multiline kymography. These findings indicated that the specific sites identified at the neoglottis by the present method were likely to be the sound source in each patient. High-speed digital imaging analysis is effective in locating the sites responsible for voice production in patients who have undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. This is the first study to clearly identify the neoglottal sound source in such patients, using a high-speed digital imaging system.

High-speed digital imaging method for ciliary beat frequency measurement

The aim of this study was to develop a high-speed digital imaging system and related software for ciliary beat frequency (CFB) analysis in order to establish an automated and reliable method that is observer independent and faster compared to the conventional computerized microscope photometry method. Using primary human nasal epithelial cell cultures, the CBF was recorded with a computerized microscope photometry system and a high-speed digital imaging system. To obtain a wide range of frequencies, glycocholate (0.5%) and chlorocresol (0.005%) were used as ciliostimulatory and cilio-inhibitory reference compounds, respectively. The mean values in hertz (+/- s.d.) obtained with the photometry and high-speed digital imaging systems were: controls 8.2 +/- 0.9 and 7.9 +/- 1.1; chlorocresol 5.0 +/- 0.9 and 5.1 +/- 1.1; glycocholate 9.8 +/- 1.0 and 9.7 +/- 0.8. A similar increase (by 20 and 24%) and decrease (by 38 and 35%) in CBF was determined by the two methods after glycocholate and chlorocresol treatment, respectively. The mean difference between the photometry and high-speed digital imaging methods was 0.2 +/- 0.6 Hz, and the Bland-Altman limits of agreement were from -1.0 to +1.4 Hz, suggesting that the results obtained by these two methods could be used interchangeably. These results show the reliability of the high-speed digital imaging system and the software developed for in-vitro CBF measurements. The advantages of the system include: (i) fast data acquisition and calculation, (ii) whole field automated CBF analysis and (iii) reduction in selection bias.

Discrete Element Simulations of Vibration Characteristics of Bulk Grain in Storage Bins

A discrete element model (DEM) (Particle Flow Code, PFC 3D ) was constructed to simulate vibration of bulk solids in a bin filled with soybeans. The vibration frequencies and amplitudes of individual particles were determined from simulated particle velocities and displacements at different excitation frequencies and amplitudes. The simulated results were compared with experimental data obtained from model bin tests. The model bin of 0.28 m height and 0.15 m diameter was made of Plexiglas and filled with soybeans. The bin was vibrated at frequencies from 5 to 30 Hz and amplitudes from 0.2 to 5.0 mm. A high-speed digital imaging system was used to record particle movement along the bin wall during vibration. Simulated vibration of particles was in good agreement with the experimental data. Simulations revealed that particle vibration was simple harmonic and had the same frequency and amplitude as the excitation at low excitation frequencies and amplitudes. Particles vibrated at their own frequencies and amplitudes when the excitation frequency and amplitude were high. Both the DEM model simulations and the experimental data showed that particles not only vibrated locally but also moved globally.

Rotation speed measurement of moving particles in a CFB riser

This paper presents a study on measuring rotation speed of moving glass beads with an average diameter of 500 μm in a pilot-scale circulating fluidized bed (CFB) riser with a high-speed digital imaging system. Two methods have been developed to calculate particle rotation speed from the particle images. The first method consists of a fully automated algorithm based on cross-correlation of gray distribution of particle images for particles whose rotation axes are (nearly) perpendicular to the imaging plane, and the second method calculates the speed of particle rotation by identifying its rotation axis using two or more characteristic points on its surface. The reliability of the two methods is verified by using a small sphere with known speed and direction of rotation. The first method is shown to be capable of measuring accurately the rotation speed for the particle with a rotation axis (nearly) perpendicular to the imaging plane and filtering off other particles using an appropriate threshold of correlation coefficient. The second method is shown to be capable of yielding both the speed and direction of particle rotation, with a measurement error of less than 10%. Results of both methods on real glass beads in a CFB riser are compared against each other.

Mudskipper pectoral fin kinematics in aquatic and terrestrial environments

Mudskippers use pectoral fins for their primary mode of locomotion on land and pectoral fins in conjunction with the axial musculature and caudal fin to move in water. We hypothesized that distinct pectoral fin movements enable effective locomotion in each environment. Additionally, we made three functional predictions about fin movements during locomotion on land versus water: the pectoral fin is depressed more on land than in water; the pectoral fin will have greater changes in fin area between propulsive and recovery phases in water versus land; anterior and posterior excursions will be greater on land than in water. Locomotion was recorded in each environment using a high-speed digital-imaging system and kinematic variables were calculated from digitized landmark points. Variables were analyzed using principal components analysis and matched pairs t-tests. Mudskippers produce distinct kinematic patterns across environments (P < 0.003), although only some of our predictions were supported. The magnitude of fin depression is the same across habitats. However, depression occurs during the propulsive phase on land (by -0.60 cm), whereas during the propulsive phase in water the fin is elevated (by +0.13 cm). We were unable to support the hypothesis that fin orientation differs between environments. Lastly, anterior extension of the fin is greater on land (1.8 cm, versus 1.3 cm in water), creating a larger stride length in this environment. We posit that the mudskipper pectoral fin may facilitate stability in water and thrust production on land, and suggest that the robust fin morphology of the goby lineage may predispose species within this group to terrestrial locomotion.