This article reports on an in‐depth, qualitative study into the pro‐environmental engagement of small businesses in the east of England, with respect to climate change in particular. Managers of environmentally pro‐active small businesses were asked about the pro‐environmental measures they had implemented in their firms, their motivations for doing so, and their understanding of climate change. The managers in this study had a relatively good understanding of environmental issues in general and climate change in particular, and had implemented a range of pro‐environmental measures in their firms. Their understanding of climate change was a holistic one, which sat within their overall understanding of environmental and social issues. While economic arguments and external pressure played a role in their pro‐environmental engagement, perhaps the most notable motivation for managers in this study to engage with environmental and climate change issues was personal values and beliefs. Environmentally engaged managers exhibited an internal locus of control. Some of these findings contrast with the views of key informants in local government and business advice organisations, who tend to emphasise the business case and cost arguments when trying to encourage small businesses towards greater environmental engagement. These findings suggest that public policy and business advice in this area should perhaps focus more strongly on personal values and a sense of being able to contribute to environmental protection in their engagement with small businesses. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.
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 (86.39%) compared with students using textbooks (62.61%) and the 3D computer model (63.68%) (P < 0.001), with no significant difference between the textbook and 3D computer model groups (P = 0.685). 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.
We provide quantitative anatomical data on the muscle-tendon architecture and geometry of the pelvic limb of an elite sprint athlete, the racing greyhound. Specifically, muscle masses, muscle lengths, fascicle lengths, pennation angles and muscle moment arms were measured. Maximum isometric force and power of muscles, the maximum muscle torque at joints and tendon stress and strain were estimated. We compare data with that published for a generalized breed of canid, and other cursorial mammals such as the horse and hare. The pelvic limb of the racing greyhound had a relatively large volume of hip extensor muscle, which is likely to be required for power production. Per unit body mass, some pelvic limb muscles were relatively larger than those in less specialized canines, and many hip extensor muscles had longer fascicle lengths. It was estimated that substantial extensor moments could be created about the tarsus and hip of the greyhound allowing high power output and potential for rapid acceleration. The racing greyhound hence possesses substantial specializations for enhanced sprint performance.
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.
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.
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.
SUMMARYAnimals 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 ʻgear ratioʼ 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.
Walking with relatively stiff limbs, vaulting the hips (or hips and shoulders in the case of quadrupeds) over incompliant legs, presents a strategy for limiting the cost of locomotion. With this gait, mechanical energy forms interchange for 'free' -potential energy converts to kinetic as the centre of mass (COM) falls, and returns to potential as it rises again -so walking in bipeds is often described in terms of an 'inverted pendulum ' (e.g. Cavagna et al., 1977). While fluctuations in kinetic and potential energy of the COM are also largely out of phase in walking quadrupeds (Cavagna et al., 1977) including dogs (Griffin et al., 2004), the mechanics of quadrupedal walking is generally less clear: although kinetic and potential energy oscillations can be broadly out of phase, the degree to which limbs can be treated as stiff, inverted pendulums is uncertain.Consideration of passive dynamic walking for bipeds (McGeer, 1990;Garcia et al., 1998) and quadrupeds (Smith and Berkemeir, 1997) subjectively shows remarkably life-like motions with simple stiff-limbed machines powered only by changes in potential energy due to walking down a gentle slope in order to overcome collisional losses. The relevance of the energetic cost of collisions at each limb placement is being increasingly understood in a variety of locomotory systems, including bipedal walking (Kuo, 2002;Donelan et al., 2002;Collins et al., 2005), gibbon brachiation (Usherwood and Bertram, 2003) and horse galloping . Here, we discuss some of the implications of minimising or managing collisions in quadrupedal walking and their potential use in accounting for observed footfall patterns and powering strategies.As highlighted by Aristotle, 'Again, why do quadrupeds move their legs criss-cross? We have to examine the reasons for all these facts, and others cognate to them; that the facts are such is clear from our Natural History, we have now to ask reasons for the facts.' In an effort to approach this issue in the case of quadrupedal walking, we present a passive model based on the geometry of a 4-bar linkage to show (1) the fluctuations in potential and kinetic energy, (2) the vertical and horizontal forces, and (3) the mechanical energy losses that would be associated with each foot placement for a stiff-limbed, walking quadruped represented as a pair of inverted pendulums linked by a stiff, incompressible back. This model is not intended to accurately predict the kinetics, forces or energetics of actual quadrupedal walking; rather, it provides a reductionist position, from which the observed deviations from the passive, stifflimbed case can be highlighted and their implications discussed.
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