Effects of incline on speed, acceleration, body posture and hindlimb kinematics in two species of lizard Callisaurus draconoides and Uma scoparia.

1998 ◽  
Vol 201 (2) ◽  
pp. 273-287 ◽  
Author(s):  
D J Irschick ◽  
B C Jayne
Keyword(s):  
Related Species ◽  
High Speed ◽  
Stride Length ◽  
Body Posture ◽  
Level Surface ◽  
Locomotor Performance ◽  
Sandy Desert ◽  
Closely Related Species ◽  
High Speed Video ◽  
Hindlimb Kinematics

We examined the effects of incline on locomotor performance and kinematics in two closely related species of iguanian lizards that co-occur in sandy desert habitats. Callisaurus draconoides differs from Uma scoparia of equal snout-vent length by being less massive and having greater limb and tail lengths. We analyzed high-speed video tapes of lizards sprinting from a standstill on a sand-covered racetrack which was level or inclined 30 degrees uphill. C. draconoides sprinted significantly faster than U. scoparia on both level and uphill sand surfaces, although U. scoparia is considered to be more specialized for sandy habitats. Initial accelerations (over the first 50 ms) did not differ significantly either between species or between inclines within species. Overall, the effects of incline were more pronounced for C. draconoides than for U. scoparia. For example, the incline caused a significant decrease in the maximum stride length of C. draconoides but not in that of U. scoparia. For C. draconoides, uphill stride durations were significantly shorter than on the level surface, and this partially compensated for the effects of shorter uphill stride lengths on velocity. C. draconoides ran bipedally more often than did U. scoparia on both the level and uphill surfaces.

scholarly journals Three-dimensional launch kinematics in leaping, parachuting and gliding squirrels

2002 ◽  
Vol 205 (16) ◽  
pp. 2469-2477 ◽  
Author(s):  
Richard L. Essner
Keyword(s):  
Significant Variation ◽  
High Speed ◽  
Three Dimensional ◽  
Tamiasciurus Hudsonicus ◽  
Glaucomys Volans ◽  
Tamias Striatus ◽  
High Speed Video ◽  
Primary Means ◽  
Hindlimb Kinematics

SUMMARY Leaping, parachuting and gliding are the primary means by which arboreal squirrels negotiate gaps in the canopy. There are notable differences among the three locomotor modes with respect to mid-air postures and aerodynamics,yet it is unclear whether variation should also be expected during the launch phase of locomotion. To address this question, launch kinematic profiles were compared in leaping (Tamias striatus), parachuting (Tamiasciurus hudsonicus) and gliding (Glaucomys volans) squirrels. Animals were filmed launching to the ground from a platform using high-speed video. Statistical comparisons among taxa indicated that only six out of 23 variables were significantly different among the three species. Two were associated with tail kinematics and were a consequence of tail morphology. Two were forelimb-related and discriminated gliding from non-gliding taxa. The remaining two variables were performance attributes, indicating significant variation among the species in take-off velocity and horizontal range. The absence of significant differences in hindlimb kinematics indicates that propulsion is essentially identical in leaping, parachuting and gliding squirrels.

scholarly journals Illustrating a free, open-source method for quantifying locomotor performance with sprinting Aegean wall lizards

2014 ◽  
Author(s):  
Colin Donihue ◽  
Ben Kazez
Keyword(s):  
Natural History ◽  
Open Source ◽  
High Speed ◽  
Video Data ◽  
Locomotor Performance ◽  
Analysis Program ◽  
Video Cameras ◽  
High Speed Video ◽  
Position Data ◽  
Free Open Source

Locomotion is an important characteristic of many animals’ natural history. With the increasing availability of high-speed video cameras, videography is a powerful tool for analyzing fast or subtle motions with unprecedented resolution. However, the programs currently available for analyzing these videos are either dauntingly time intensive or prohibitively expensive. We have developed a free, open-source video analysis program, SAVRA, that enables the quick capture of scaled position data. Here we demonstrate its use with an analysis of several videos of the Aegean wall lizard (Podarcis erhardii). We hope making this program freely available will facilitate the analysis of video data across taxa, not just in laboratory settings but also in natural contexts.

scholarly journals Indirect evidence for elastic energy playing a role in limb recovery during toad hopping

2014 ◽  
Vol 10 (7) ◽  
pp. 20140418 ◽  
Author(s):  
Ariela Schnyer ◽  
Mirialys Gallardo ◽  
Suzanne Cox ◽  
Gary Gillis
Keyword(s):  
Elastic Energy ◽  
High Speed ◽  
Muscle Power ◽  
Rapid Development ◽  
Indirect Evidence ◽  
Knee Extension ◽  
Elastic Recoil ◽  
High Speed Video ◽  
Hindlimb Kinematics ◽  
Limb Flexion

Elastic energy is critical for amplifying muscle power during the propulsive phase of anuran jumping. In this study, we use toads ( Bufo marinus ) to address whether elastic recoil is also involved after take-off to help flex the limbs before landing. The potential for such spring-like behaviour stems from the unusually flexed configuration of a toad's hindlimbs in a relaxed state. Manual extension of the knee beyond approximately 90° leads to the rapid development of passive tension in the limb as underlying elastic tissues become stretched. We hypothesized that during take-off, the knee regularly extends beyond this, allowing passive recoil to help drive limb flexion in mid-air. To test this, we used high-speed video and electromyography to record hindlimb kinematics and electrical activity in a hindlimb extensor (semimembranosus) and flexor (iliofibularis). We predicted that hops in which the knees extended further during take-off would require less knee flexor recruitment during recovery. Knees extended beyond 90° in over 80% of hops, and longer hops involved greater degrees of knee extension during take-off and more intense semimembranosus activity. However, knee flexion velocities during recovery were maintained despite a significant decrease in iliofibularis intensity in longer hops, results consistent with elastic recoil playing a role.

Water relations and mineral nutrition of closely related woody plant species on desert dunes and interdunes

2008 ◽  
Vol 56 (1) ◽  
pp. 27 ◽  
Author(s):  
Alasdair M. Grigg ◽  
Erik J. Veneklaas ◽  
Hans Lambers
Keyword(s):  
Water Relations ◽  
Related Species ◽  
Soil Depth ◽  
Dry Season ◽  
Influential Factors ◽  
Plant Distribution ◽  
Mineral Nutrient ◽  
Nutrient Concentrations ◽  
Sandy Desert ◽  
Closely Related Species

Vegetation on dunes and interdunes in hot, subtropical deserts is profoundly influenced by the temporal and spatial variation in availability of water and nutrients in the landscape. We hypothesised that water is more available to plants on the dunes but that nutrients are in greater concentrations on the interdunes in the Great Sandy Desert, Western Australia. During the course of 2 years, we examined water relations and photosynthesis of six dominant woody species throughout each season, in addition to foliar δ13C, δ15N and nutrient composition. In general, stomatal conductance (gs) was greater and leaf water potential (ΨL) less negative for dune species than for closely related species on the interdunes. The largest tree species in the landscape, Corymbia chippendalei ((D.J.Carr & S.G.M.Carr) K.D.Hill & L.A.S.Johnson), occurred only on the dunes, and maintained moderate gs values year round, ranging between 240 mmol H2O m–2 s–1 in the wet season and 160 mmol H2O m–2 s–1 in the middle of the dry season. It also displayed a relatively stable ΨL, between –0.3 and –0.5 MPa at predawn, and between –1.3 and –1.6 MPa at midday throughout the year, unlike the closely related species on the interdunes, Eucalyptus victrix (L.A.S.Johnson & K.D.Hill), which always displayed significantly lower ΨL values (0.2–1.1 MPa more negative). The two Grevillea species displayed ΨL values within a similar range as for C. chippendalei, while the Acacia species exhibited consistently more negative values, especially late in the dry season. Considerable reductions in gs occurred at this time for all species, except C. chippendalei. Rates of photosynthesis (A) followed the trends in gs, yet δ13C values varied little between related species in the dune and interdune habitats. Mineral nutrient concentrations in soil and foliage tended to be greater in the interdunes. Average N : P ratio in foliage was 28 : 1, indicating P was more limiting than N. Soil depth and texture, in conjunction with their effects on water availability and root growth, were considered to be the most influential factors affecting plant distribution in the Great Sandy Desert. It is concluded that dunes hold relatively more water than adjacent interdunes, sustaining more favourable water status in deep-rooted species from this habitat, further into the dry season. Conversely, species on the interdunes must be more desiccation tolerant and develop root systems with greater ability to penetrate conglomerated lateritic gravel layers in order to access water where and when it is available.

scholarly journals Illustrating a free, open-source method for quantifying locomotor performance with sprinting Aegean wall lizards

2014 ◽  
Author(s):  
Colin Donihue ◽  
Ben Kazez
Keyword(s):  
Natural History ◽  
Open Source ◽  
High Speed ◽  
Video Data ◽  
Locomotor Performance ◽  
Analysis Program ◽  
Video Cameras ◽  
High Speed Video ◽  
Position Data ◽  
Free Open Source

Locomotion is an important characteristic of many animals’ natural history. With the increasing availability of high-speed video cameras, videography is a powerful tool for analyzing fast or subtle motions with unprecedented resolution. However, the programs currently available for analyzing these videos are either dauntingly time intensive or prohibitively expensive. We have developed a free, open-source video analysis program, SAVRA, that enables the quick capture of scaled position data. Here we demonstrate its use with an analysis of several videos of the Aegean wall lizard (Podarcis erhardii). We hope making this program freely available will facilitate the analysis of video data across taxa, not just in laboratory settings but also in natural contexts.

APPLICATION OF THE EARLY DAMAGE DIAGNOSTICS TECHNIQUE TO EXAMINATION OF THE AVIATION PANEL

2019 ◽  
Vol 85 (6) ◽  
pp. 53-63 ◽  
Author(s):  
I. E. Vasil’ev ◽  
Yu. G. Matvienko ◽  
A. V. Pankov ◽  
A. G. Kalinin
Keyword(s):  
Acoustic Emission ◽  
Damage Detection ◽  
High Speed ◽  
Early Stage ◽  
Video Data ◽  
High Speed Video ◽  
Damage Diagnostics ◽  
Subsurface Defect ◽  
Sensitive Coating ◽  
Early Damage

The results of using early damage diagnostics technique (developed in the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) for detecting the latent damage of an aviation panel made of composite material upon bench tensile tests are presented. We have assessed the capabilities of the developed technique and software regarding damage detection at the early stage of panel loading in conditions of elastic strain of the material using brittle strain-sensitive coating and simultaneous crack detection in the coating with a high-speed video camera “Video-print” and acoustic emission system “A-Line 32D.” When revealing a subsurface defect (a notch of the middle stringer) of the aviation panel, the general concept of damage detection at the early stage of loading in conditions of elastic behavior of the material was also tested in the course of the experiment, as well as the software specially developed for cluster analysis and classification of detected location pulses along with the equipment and software for simultaneous recording of video data flows and arrays of acoustic emission (AE) data. Synchronous recording of video images and AE pulses ensured precise control of the cracking process in the brittle strain-sensitive coating (tensocoating)at all stages of the experiment, whereas the use of structural-phenomenological approach kept track of the main trends in damage accumulation at different structural levels and identify the sources of their origin when classifying recorded AE data arrays. The combined use of oxide tensocoatings and high-speed video recording synchronized with the AE control system, provide the possibility of definite determination of the subsurface defect, reveal the maximum principal strains in the area of crack formation, quantify them and identify the main sources of AE signals upon monitoring the state of the aviation panel under loading P = 90 kN, which is about 12% of the critical load.

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