John Schmitt

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We study the dynamics and stability of legged locomotion in the horizontal plane. Motivated by experimental studies of insects, we develop two- and three-degree-of freedom rigid body models with pairs of ‘virtual’ elastic legs in intermittent contact with the ground. We focus on conservative compliant-legged models, but we also consider prescribed forces,(More)
We study the dynamics and stability of legged locomotion in the horizontal plane. We discuss the relevance of idealized mechanical models, developed in a companion paper, to recent experiments and simulations on insect running and turning. Applying our results to rapidly running cockroaches, we show that the models' gait and force characteristics match(More)
 We extend the analysis of simple, energy-conserving models for the dynamics of insect locomotion in the horizontal plane developed in Schmitt and Holmes (2000a,b, 2001), where gaits characteristic of steady cockroach running and turning were evoked. In this paper, we include dissipation and energy inputs via active “muscles” in three forms: via prescribed(More)
A rapidly expanding empirical literature has addressed the widely accepted claim that employmentunfriendly labor market institutions explain the pattern of unemployment across countries. The main culprits are held to be protective institutions, namely unemployment benefit entitlements, employment protection laws, and trade unions. Our assessment of the(More)
The Lateral Leg Spring model (LLS) was developed by Schmitt and Holmes to model the horizontal-plane dynamics of a running cockroach. The model captures several salient features of real insect locomotion, and demonstrates that horizontal plane locomotion can be passively stabilized by a well-tuned mechanical system, thus requiring minimal neural reflexes.(More)
Animals can swerve, dodge, dive, climb, turn and stop abruptly. Their stability and maneuverability are remarkable, but a challenge to quantify. Formal stability analysis can allow for quantitative comparisons within and among species. Stability analysis used in concert with a template (a simple, general model that serves as a guide for control) can lead to(More)
It is widely believed that regional labor markets in the USA are highly flexible, so that employment shocks have only transitory effects on joblessness since induced migration quickly offsets much of the initial impact. However, time-series analysis of the response to shocks is very sensitive to errors of measurement, and such errors are large in some(More)
Facility experience primarily in drug-oriented fermentation equipment (producing small molecules such as secondary metabolites, bioconversions, and enzymes) and, to a lesser extent, in biologics-oriented fermentation equipment (producing large molecules such as recombinant proteins and microbial vaccines) in an industrial fermentation pilot plant over the(More)
The ability to traverse unknown, rough terrain is an advantage that legged locomoters have over their wheeled counterparts. However, due to the complexity of multi-legged systems, research in legged robotics has not yet been able to reproduce the agility found in the animal kingdom. In an effort to reduce the complexity of the problem, researchers have(More)
Botulinum neurotoxin (BoNT) binds peripheral neurons at the neuromuscular junction through a dual-receptor mechanism that includes interactions with ganglioside and protein receptors. The receptor identities vary depending on BoNT serotype (A-G). BoNT/B and BoNT/G bind the luminal domains of synaptotagmin I and II, homologous synaptic vesicle proteins. We(More)