We review the arguments supporting the existence of a maximal acceleration for a massive particle and show that different values of this upper limit can be predicted in different physical situations. ∗E-mail: [email protected]

40 41 To successfully intercept or avoid moving objects, we must compensate for the sensorimotor 42 delays associated with visual processing and motor movement. While straightforward in the 43 case of constant velocity motion, it is unclear how humans compensate for accelerations, as 44 our visual system is relatively poor at detecting changes in velocity. Work on free falling 45 objects sugges...

When a powerful laser beam is focussed on a free electron the acceleration of the latter is so violent that the interaction is nonlinear. We review the prospects for experimental studies of nonlinear electrodynamics of a single electron, with emphasis on the most accessible effect, non-linear Thomson scattering. We also speculate on the possibility of laboratory studies of a novel effect relate...

Nowadays, metropolitan railway systems are in great demand, so they offer highfrequency services for the most part of the day. Therefore there are only a few hours during night available to carry out maintenance tasks. This research develops a system that records the vertical accelerations undergone by the bogies of in-service railway vehicles. As accelerations are measured during regular servi...

Variability and stability of walking of eight transfemoral amputees and eight healthy controls was studied under four conditions: walking inside on a smooth terrain, walking while performing a dual-task and walking outside on (ir)regular surfaces. Trunk accelerations were recorded with a tri-axial accelerometer. Walking speed, mean and coefficient of variation of stride times (ST) and the root ...

OBJECTIVE Shocks and vibrations experienced while using a hand-rim wheelchair can contribute to discomfort, fatigue and injury. The aim of this study was to compare the seat forces and head accelerations experienced by manual wheelchair users during independent curb descent landings in a standard and 3 suspension-type rigid-frame wheelchairs. DESIGN EXPERIMENTAL repeated measures analysis ...

Emu eggs weigh approximately 600 g and have an incubation duration (ID) of approximately 50 days. The egg mass is approximately 10-fold heavier than the chicken egg and the ID is approximately 2.5-fold longer. Daily changes in mean heart rate (MHR) of emu embryos were previously determined, but further measurement was needed to investigate the species-specific behavior of cardiac rhythm for com...

Kemp eliminases represent the most successful class of computationally designed enzymes, with rate accelerations of up to 109-fold relative to the rate of the same reaction in aqueous solution. Nevertheless, several other systems such as micelles, catalytic antibodies, and cavitands are known to accelerate the Kemp elimination by several orders of magnitude. We found that the naturally occurrin...

The performance characteristics of football helmets are currently evaluated by simulating head impacts in the laboratory using a linear drop test method. To encourage development of helmets designed to protect against concussion, the National Operating Committee for Standards in Athletic Equipment recently proposed a new headgear testing methodology with the goal of more closely simulating in v...