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Author

Sarah B. Williams

Other affiliations: University of Liverpool
Bio: Sarah B. Williams is an academic researcher from Royal Veterinary College. The author has contributed to research in topics: Acceleration & Kinematics. The author has an hindex of 9, co-authored 13 publications receiving 630 citations. Previous affiliations of Sarah B. Williams include University of Liverpool.

Papers
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Journal ArticleDOI
TL;DR: The results suggest that physical models may hold a significant advantage over alternative learning resources in enhancing visuospatial and 3D understanding of complex anatomical architecture, and that 3D computer models have significant limitations with regards to 3D learning.
Abstract: Three-dimensional (3D) information plays an important part in medical and veterinary education Appreciating complex 3D spatial relationships requires a strong foundational understanding of anatomy and mental 3D visualization skills Novel learning resources have been introduced to anatomy training to achieve this Objective evaluation of their comparative efficacies remains scarce in the literature This study developed and evaluated the use of a physical model in demonstrating the complex spatial relationships of the equine foot It was hypothesized that the newly developed physical model would be more effective for students to learn magnetic resonance imaging (MRI) anatomy of the foot than textbooks or computer-based 3D models Third year veterinary medicine students were randomly assigned to one of three teaching aid groups (physical model; textbooks; 3D computer model) The comparative efficacies of the three teaching aids were assessed through students' abilities to identify anatomical structures on MR images Overall mean MRI assessment scores were significantly higher in students utilizing the physical model (8639%) compared with students using textbooks (6261%) and the 3D computer model (6368%) (P < 0001), with no significant difference between the textbook and 3D computer model groups (P = 0685) Student feedback was also more positive in the physical model group compared with both the textbook and 3D computer model groups Our results suggest that physical models may hold a significant advantage over alternative learning resources in enhancing visuospatial and 3D understanding of complex anatomical architecture, and that 3D computer models have significant limitations with regards to 3D learning Anat Sci Educ 6: 216–224 © 2013 American Association of Anatomists

281 citations

Journal ArticleDOI
TL;DR: The greyhound thoracic limb appears to possess substantial differences from both that of more ‘sub‐maximal specialist’ quadrupeds, and from the greyhound pelvic limb, suggesting that it may be used to some extent in propulsion, or alternatively that stabilisation is very important in this animal.
Abstract: We provide quantitative muscle–tendon architecture and geometry data for the racing greyhound thoracic limb. Muscle mass, belly length, fascicle lengths, pennation angles and moment arms were measured, as were tendon masses and lengths. Maximum isometric force and maximum power were estimated for muscles, and maximum stress and strain were estimated for tendons. Results are compared with other fast quadrupedal runners, and to previously published data in mixed-breed dogs. The implications of the functional adaptations of the greyhound thoracic limb for sprinting performance are discussed. The thoracic limb was found to benefit from a similar proportion of locomotor muscle mass to the pelvic limb, suggesting that it may be used to some extent in propulsion, or alternatively that stabilisation is very important in this animal. Extrinsic muscles, especially latissimus dorsi and pectoralis profundus, were predicted to be powerful and important for generating net positive work during accelerations. Proximal biarticular muscles show specialisation toward preventing collapse of the shoulder and elbow joints to enable strut-like limb function, or some form of dynamic control. Distal muscles did not appear specialised for elastic energy storage, a functional difference to pelvic limb muscles, and the equivalents in horse thoracic limbs. The greyhound thoracic limb appears to possess substantial differences from both that of more ‘sub-maximal specialist’ quadrupeds, and from the greyhound pelvic limb.

136 citations

Journal ArticleDOI
TL;DR: The pelvic limb of the hare was found to contain substantial amounts of hip extensor and adductor/abductor muscle volume, which is likely to be required for power production and stability during rapid turning.
Abstract: We provide quantitative anatomical data on the muscle–tendon architecture of the hare pelvic limb (specifically muscle mass, fascicle length, pennation angle, tendon mass and length). In addition, moment arms of major pelvic limb muscles were measured. Maximum isometric force and power of muscles, the moment of force about a joint, and tendon stress and strain were estimated. Data are compared with published data for other cursorial mammals such as the horse and dog, and a non-specialised Lagamorph, the rabbit. The pelvic limb of the hare was found to contain substantial amounts of hip extensor and adductor/abductor muscle volume, which is likely to be required for power production and stability during rapid turning. A proximal to distal reduction in muscle volume and fascicle length was also observed, as is the case in other cursorial quadrupeds, along with a reduction in distal limb mass via the replacement of muscle volume by long distal limb tendons, capable of storing large amounts of elastic energy. The majority of hare pelvic limb muscle moment arms varied with joint position, giving the hare the capacity to vary muscle function with limb posture and presumably different locomotor activities.

72 citations

Journal ArticleDOI
TL;DR: This work examined two elite athletes bred and trained for acceleration performance when performing maximal acceleration (and deceleration for ponies) in a competitive setting and shows that maximum acceleration and de acceleration ability may be accounted for by two simple limits, one mechanical and one physiological.
Abstract: Rapid acceleration and deceleration are vital for survival in many predator and prey animals and are important attributes of animal and human athletes. Adaptations for acceleration and deceleration are therefore likely to experience strong selective pressures—both natural and artificial. Here, we explore the mechanical and physiological constraints to acceleration. We examined two elite athletes bred and trained for acceleration performance (polo ponies and racing greyhounds), when performing maximal acceleration (and deceleration for ponies) in a competitive setting. We show that maximum acceleration and deceleration ability may be accounted for by two simple limits, one mechanical and one physiological. At low speed, acceleration and deceleration may be limited by the geometric constraints of avoiding net nose-up or tail-up pitching, respectively. At higher speeds, muscle power appears to limit acceleration.

59 citations

Journal ArticleDOI
TL;DR: Hindlimb EMA decreased substantially with increased acceleration – a potential strategy to increase stance time and thus ground impulses for a given peak force, may also increase the mechanical advantage for applying the horizontal forces necessary for acceleration.
Abstract: Animals in their natural environments are confronted with a regular need to perform rapid accelerations (for example when escaping from predators or chasing prey). Such acceleration requires net positive mechanical work to be performed on the centre of mass by skeletal muscle. Here we determined how pelvic limb joints contribute to the mechanical work and power that are required for acceleration in galloping quadrupeds. In addition, we considered what, if any, biomechanical strategies exist to enable effective acceleration to be achieved. Simultaneous kinematic and kinetic data were collected for racing greyhounds undergoing a range of low to high accelerations. From these data, joint moments and joint powers were calculated for individual hindlimb joints. In addition, the mean effective mechanical advantage (EMA) of the limb and the `gear ratio' of each joint throughout stance were calculated. Greatest increases in joint work and power with acceleration appeared at the hip and hock joints, particularly in the lead limb. Largest increases in absolute positive joint work occurred at the hip, consistent with the hypothesis that quadrupeds power locomotion by torque about the hip. In addition, hindlimb EMA decreased substantially with increased acceleration – a potential strategy to increase stance time and thus ground impulses for a given peak force. This mechanism may also increase the mechanical advantage for applying the horizontal forces necessary for acceleration.

46 citations


Cited by
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Journal ArticleDOI
TL;DR: 3D printing offers many advantages over plastination as it allows rapid production of multiple copies of any dissected specimen, at any size scale and should be suitable for any teaching facility in any country, thereby avoiding some of the cultural and ethical issues associated with cadaver specimens either in an embalmed or plastinated form.
Abstract: The teaching of anatomy has consistently been the subject of societal controversy, especially in the context of employing cadaveric materials in professional medical and allied health professional training. The reduction in dissection-based teaching in medical and allied health professional training programs has been in part due to the financial considerations involved in maintaining bequest programs, accessing human cadavers and concerns with health and safety considerations for students and staff exposed to formalin-containing embalming fluids. This report details how additive manufacturing or three-dimensional (3D) printing allows the creation of reproductions of prosected human cadaver and other anatomical specimens that obviates many of the above issues. These 3D prints are high resolution, accurate color reproductions of prosections based on data acquired by surface scanning or CT imaging. The application of 3D printing to produce models of negative spaces, contrast CT radiographic data using segmentation software is illustrated. The accuracy of printed specimens is compared with original specimens. This alternative approach to producing anatomically accurate reproductions offers many advantages over plastination as it allows rapid production of multiple copies of any dissected specimen, at any size scale and should be suitable for any teaching facility in any country, thereby avoiding some of the cultural and ethical issues associated with cadaver specimens either in an embalmed or plastinated form. Anat Sci Educ 7: 479–486. © 2014 American Association of Anatomists.

480 citations

Journal ArticleDOI
TL;DR: 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines, and the overall costs of a 3D printing laboratory must be balanced by the clinical benefits.
Abstract: While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article.

444 citations

Journal ArticleDOI
TL;DR: The goal is to discuss the current and emerging applications of 3D printing in medicine, a brief summary on additive manufacturing technologies and available printable materials, and the technological and regulatory barriers that are slowing down the full implementation of 3d printing in the medical field.
Abstract: Three-dimensional (3D) printing enables the production of anatomically matched and patient-specific devices and constructs with high tunability and complexity. It also allows on-demand fabrication with high productivity in a cost-effective manner. As a result, 3D printing has become a leading manufacturing technique in healthcare and medicine for a wide range of applications including dentistry, tissue engineering and regenerative medicine, engineered tissue models, medical devices, anatomical models and drug formulation. Today, 3D printing is widely adopted by the healthcare industry and academia. It provides commercially available medical products and a platform for emerging research areas including tissue and organ printing. In this review, our goal is to discuss the current and emerging applications of 3D printing in medicine. A brief summary on additive manufacturing technologies and available printable materials is also given. The technological and regulatory barriers that are slowing down the full implementation of 3D printing in the medical field are also discussed.

355 citations

Journal ArticleDOI
TL;DR: In this paper, the design and control of a prismatic series elastic actuator with high mechanical power output in a small and lightweight form factor is discussed. And the actuator's performance is demonstrated through a series of experiments designed to operate at the limits of its mechanical and control capability.
Abstract: This paper discusses design and control of a prismatic series elastic actuator with high mechanical power output in a small and lightweight form factor. A design is introduced that pushes the performance boundary of electric series elastic actuators by using high motor voltage coupled with an efficient drivetrain to enable large continuous actuator force while retaining speed. Compact size is achieved through the use of a novel piston-style ball screw support mechanism and a concentric compliant element. Generic models for two common series elastic actuator configurations are introduced and compared. These models are then used to develop controllers for force and position tracking based on combinations of PID, model-based, and disturbance observer control structures. Finally, our actuator's performance is demonstrated through a series of experiments designed to operate the actuator at the limits of its mechanical and control capability.

332 citations

Journal ArticleDOI
13 Jun 2013-Nature
TL;DR: A new tracking collar is described and used, containing a combination of Global Positioning System (GPS) and inertial measurement units, to capture the locomotor dynamics and outcome of 367 predominantly hunting runs of five wild cheetahs in Botswana, providing the first detailed locomotor information on the hunting dynamics of a large cursorial predator in its natural habitat.
Abstract: Although the cheetah is recognised as the fastest land animal, little is known about other aspects of its notable athleticism, particularly when hunting in the wild. Here we describe and use a new tracking collar of our own design, containing a combination of Global Positioning System (GPS) and inertial measurement units, to capture the locomotor dynamics and outcome of 367 predominantly hunting runs of five wild cheetahs in Botswana. A remarkable top speed of 25.9 m s−1 (58 m.p.h. or 93 km h−1) was recorded, but most cheetah hunts involved only moderate speeds. We recorded some of the highest measured values for lateral and forward acceleration, deceleration and body-mass-specific power for any terrestrial mammal. To our knowledge, this is the first detailed locomotor information on the hunting dynamics of a large cursorial predator in its natural habitat. A novel tracking collar provides highly precise location, speed and acceleration data from 367 runs by five cheetahs in the wild; although a top speed of 58 m.p.h. was reported, few runs were above 45 m.p.h. with the average run around 31 m.p.h., and hunting success depended on grip, manoeuvrability and muscle power rather than outright speed. The cheetah is widely recognized as the fastest animal on land, with a reported top speed of 29 metres per second. However, few precise measurements have been made and only rarely have speeds faster than racing greyhounds (18 m s−1) been recorded. Now a team from the Royal Veterinary College, UK, working with the Botswana Predator Conservation Trust, has used custom-built tracking collars containing GPS and inertial measurement units to capture the locomotor dynamics of cheetahs hunting in the wild. The top speed observed was 25.9 m s−1 (93 kilometres per hour). Most hunts involved only moderate speeds, their success relying on a combination of power, acceleration and agility.

289 citations