In former times, selections in beef cattle were based on conformation alone. Today increased costs of production, competition from other feedstuffs and current exponential growth rates of human populations suggest that while energetic efficiency and volume of production are not the sole over-riding factors in beef cattle production, they are becoming increasingly important. The time has come wh...

We investigate the hydrodynamic response of plasma gradients during the interaction with ultraintense energetic laser pulses, using kinetic particle simulations. Energetic laser pulses are capable of compressing preformed plasma gradients over short times while accelerating low-density plasma backwards. As light is absorbed on a steepened interface, hot-electron temperature and coupling efficie...

Locomotor activity by diving marine mammals is accomplished while breath-holding and often exceeds predicted aerobic capacities. Video sequences of freely diving seals and whales wearing submersible cameras reveal a behavioral strategy that improves energetic efficiency in these animals. Prolonged gliding (greater than 78% descent duration) occurred during dives exceeding 80 meters in depth. Gl...

This study tests the hypothesis that arterial vascular stiffening adversely influences in situ left ventricular contractile function and energetic efficiency. Ten reflex-blocked anesthetized dogs underwent a bypass operation in which a Dacron graft was sewn to the ascending aorta and connected to the infrarenal abdominal aorta via a plastic conduit. Flow was directed through either native aorta...

Synopsis Foraging by large (425 kg), mammalian carnivores often entails cryptic tactics to surreptitiously locate and overcome highly mobile prey. Many forms of intermittent locomotion from stroke-and-glide maneuvers by marine mammals to sneak-and-pounce behaviors by terrestrial canids, ursids, and felids are involved. While affording proximity to vigilant prey, these tactics are also associate...

Heterothermic insects like honeybees, foraging in a variable environment, face the challenge of keeping their body temperature high to enable immediate flight and to promote fast exploitation of resources. Because of their small size they have to cope with an enormous heat loss and, therefore, high costs of thermoregulation. This calls for energetic optimisation which may be achieved by differe...

Foraging by large (>25 kg), mammalian carnivores often entails cryptic tactics to surreptitiously locate and overcome highly mobile prey. Many forms of intermittent locomotion from stroke-and-glide maneuvers by marine mammals to sneak-and-pounce behaviors by terrestrial canids, ursids, and felids are involved. While affording proximity to vigilant prey, these tactics are also associated with un...

The functional roles of individual lower limb muscles during human walking may differ depending on walking speed or duration. In this study, 11 volunteers walked on a treadmill for 60 min at speeds corresponding to both optimal and 20% above optimal energetic cost of transport whilst oxygen consumption and medial gastrocnemius (MG) and soleus fascicle lengths were measured. Although energetic c...