scholarly journals Effect of different head and neck positions on kinematics of elite dressage horses ridden at walk on treadmill

2018 ◽  
Vol 14 (2) ◽  
pp. 69-78 ◽  
Author(s):  
M. Rhodin ◽  
A. Byström ◽  
L. Roepstorff ◽  
E. Hernlund ◽  
P.R. Van Weeren ◽  
...  
Keyword(s):  
Head And Neck ◽  
High Speed ◽  
Metatarsophalangeal Joint ◽  
Movement Pattern ◽  
Video Cameras ◽  
Extended Position ◽  
High Level ◽  
Kinetics Of ◽  
Measuring Instrumentation ◽  
Head And Neck Position

The debate on proper head and neck positions (HNP) in horse training is lively, but little is known about the biomechanical effects of various HNPs in horses ridden at walk. The aim was to quantify the influence of different HNPs on the kinematics of horses ridden at walk. The standard competition position (HNP2) was compared to a free, unrestrained position (HNP1), more flexed positions (HNP3, HNP4), a raised extended position (HNP5) and a forward-downward extended position (HNP6). An experimental study in seven high-level dressage horses ridden at walk on a treadmill was designed. Kinetic and kinematic measurements were obtained with different HNPs. HNP2 was used as a speed-matched reference. Kinematics were measured from skin-fixed markers recorded by high-speed video cameras. The kinetics of the limbs were measured by the force-measuring instrumentation of the treadmill. In HNP1, compared to HNP2, the lumbar back and the pelvis were more horizontally positioned (more extended), and fore- and hindlimb pro- and retraction increased, with increased caudal rotation of the femur during the second half of hindlimb stance. HNP6 induced similar changes as HNP1, but caused larger increases in forelimb pro- and retraction. In HNP3, HNP4 and HNP5 the pelvis was more angled (less extended) compared to HNP2 at hindlimb midstance, and in HNP3 and HNP4 also in early hindlimb stance. All three HNPs caused increased maximum flexion of the tarsus, stifle and metatarsophalangeal joint during the swing phase. HNP3 and HNP5, but not HNP4, had a decreasing influence on fore- and hindlimb pro- and retraction, and decreased caudal rotation of the femur during the second half of hindlimb stance.The main limitation was that horses were not ridden overground and the number of horses was small. Our conclusion was that changes in head and neck position can markedly affect the horse’s movement pattern at walk.

scholarly journals Observation and analysis of diving beetle movements while swimming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debo Qi ◽  
Chengchun Zhang ◽  
Jingwei He ◽  
Yongli Yue ◽  
Jing Wang ◽  
...  
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Kinematic Model ◽  
Movement Pattern ◽  
Unmanned Vehicles ◽  
Power Stroke ◽  
Cross Sectional ◽  
Motion Data ◽  
The Cross ◽  
Diving Beetle

AbstractThe fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s2 in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.

The influence of head and neck position on ventilation with the i-gel airway in paralysed, anaesthetised patients

2011 ◽  
Vol 28 (8) ◽  
pp. 597-599 ◽  
Author(s):  
Takuro Sanuki ◽  
Rumiko Uda ◽  
Shingo Sugioka ◽  
Erina Daigo ◽  
Hiroki Son ◽  
...  
Keyword(s):  
Head And Neck ◽  
Neck Position ◽  
Head And Neck Position

Toward high-level theoretical studies on the reaction kinetics of PAHs growth based on HACA pathway: An ONIOM[G3(MP2,CC)//B3LYP:DFT] method developed

Fuel ◽  
2021 ◽  
Vol 301 ◽  
pp. 121052
Author(s):  
Chengcheng Ao ◽  
Shanshan Ruan ◽  
Wei He ◽  
Yi Liu ◽  
Chenliang He ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Theoretical Studies ◽  
High Level ◽  
Kinetics Of

R452 – Nasopharyngeal Yolk Sac Tumors: A Rare Pediatric Occurrence

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P196-P196 ◽  
Author(s):  
Lorraine M Smith ◽  
Ryan F Osborne
Keyword(s):  
Head And Neck ◽  
Clinical Presentation ◽  
Yolk Sac ◽  
High Dose ◽  
Presenting Symptoms ◽  
Mild Improvement ◽  
Pathologic Features ◽  
Yolk Sac Tumors ◽  
Infant Girl ◽  
High Level

Problem To report the rare occurrence of a yolk sac tumor of the nose and nasopharynx presenting as acute sinusitis and bilateral complete blindness. Methods The clinical presentation, pathologic features, and management of this 2-year-old infant girl is reviewed. We also performed a medical literature search in English using PUBMED and OVID databases. We then analyzed the literature with respect to clinical presentation, manifestations and therapies for other extra-gonadal yolk sac tumors presenting in the head and neck. Results The patient was treated with 4 courses of high dose cis-platinum, etoposide, bleomycin repeated every 3 weeks along with surgery. She had initial mild improvement in visual perception along with shrinkage of her tumor. The yolk sac malignancies of the head and neck are often, large, aggressive lesions on presentation that once treated have a tendency to recur. Conclusion Yolk sac tumors (endodermal sinus tumors) represent 3–5% of pediatric malignancies. They are rare malignancies in the head and neck, of germ cell origin. Successful treatment usually requires a combination of chemotherapy and surgical extirpation followed by postoperative chemotherapy. Significance Recurrent sinusitis and nasal obstruction in children should be evaluated carefully and with a high level of suspicion for rare nasal and nasopharyngeal malignancies. Early diagnosis and prompt treatment may alleviate many of the presenting symptoms and prolong life.

Study on the Formaldehyde Adsorption Kinetics of Dry Waters

2014 ◽  
Vol 809-810 ◽  
pp. 907-911
Author(s):  
Jun Long Wang ◽  
Jie Hou ◽  
Ting Jiang ◽  
Yong Jun He ◽  
Yao Dong Liang
Keyword(s):  
Adsorption Kinetics ◽  
High Speed ◽  
Adsorption Process ◽  
Average Diameter ◽  
Adsorption Rate ◽  
Absorption Kinetics ◽  
Order Model ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Formaldehyde Adsorption

Dry waters with an average diameter of 82 μm were prepared by a high speed mixed route. The formaldehyde absorption kinetics of dry waters was investigated by simulating indoor formaldehyde pollution in glass chamber. The results showed that pseudo-second order model could be used to simulate the adsorption process; the adsorption rate was highest in the initial 60 minutes; when the adsorption lasted for 180 minutes, the adsorption reached equilibrium.

Effect of Air Fraction on Force Coefficients in Oscillatory Flow

2021 ◽  
Author(s):  
Malene Hovgaard Vested ◽  
Erik Damgaard Christensen
Keyword(s):  
High Speed ◽  
Offshore Structures ◽  
Air Injection ◽  
Wave Loads ◽  
Morison Equation ◽  
Force Coefficients ◽  
Air Content ◽  
Set Up ◽  
High Level ◽  
Spilling Breakers

Abstract The forces on marine and offshore structures are often affected by spilling breakers. The spilling breaker is characterized by a roller of mixed air and water with a forward speed approximately equal to the wave celerity. This high speed in the top of the wave has the potential to induce high wave loads on upper parts of the structures. This study analyzed the effect of the air content on the forces. The analyses used the Morison equation to examine the effect of the percentage of air on the forces. An experimental set-up was developed to include the injection of air into an otherwise calm water body. The air-injection did introduce a high level a turbulence. It was possible to assess the amount of air content in the water for different amounts of air-injection. In the mixture of air and water the force on an oscillating square cylinder was measured for different levels of air-content, — also in the case without air. The measurements indicated that force coefficients for clear water could be use in the Morison equation as long as the density for water was replaced by the density for the mixture of air and water.

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