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Abstract Ultrafast movements propelled by springs and released by latches are thought limited to energetic adjustments prior to movement, and seemingly cannot adjust once movement begins. Even so, across the tree of life, ultrafast organisms navigate dynamic environments and generate a range of movements, suggesting unrecognized capabilities for control. We develop a framework of control pathways leveraging the non-linear dynamics of spring-propelled, latch-released systems. We analytically model spring dynamics and develop reduced-parameter models of latch dynamics to quantify how they can be tuned internally or through changing external environments. Using Lagrangian mechanics, we test feedforward and feedback control implementation via spring and latch dynamics. We establish through empirically-informed modeling that ultrafast movement can be controllably varied during latch release and spring propulsion. A deeper understanding of the interconnection between multiple control pathways, and the tunability of each control pathway, in ultrafast biomechanical systems presented here has the potential to expand the capabilities of synthetic ultra-fast systems and provides a new framework to understand the behaviors of fast organisms subject to perturbations and environmental non-idealities. 

Bonamia(Haplosporida) are oyster parasites capable of devastating oyster populations. The near-circumglobal distribution of the host generalistB. exitiosahas previously been associated with the natural and anthropogenic dispersal of broadly distributed non-commercial oysters in theOstrea stentinaspecies complex. Here, we took a global snapshot approach to explore the role of the widely introduced Pacific oysterMagallana gigas, a commercially important species that can be found on every continent except Antarctica, in transportingBonamia.We screened 938M. gigasindividuals from 41 populations in this oyster’s native and non-native geographic range for presence ofBonamiaDNA using PCR.B. exitiosawas the only species detected and only within 2 of 5 populations from southern California, USA (10 and 42% PCR prevalence). Therefore,M. gigascould have played a role in transportingB. exitiosato California (if introduced) and/or maintainingB. exitiosapopulations within California, but morphological confirmation of infection needs to be done to better understand the host-parasite dynamics within this system. We detected noBonamiaDNA within any other non-nativeM. gigaspopulations (n = 302) nor within nativeM. gigaspopulations in Japan and Korea (n = 582) and thus found no evidence to support the co-dispersal ofM. gigasand otherBonamiaspecies. Lower sample sizes within some populations and the non-systematic nature of our sampling design may have led to false negatives, especially in areas whereBonamiaare known to occur. Nevertheless, this global snapshot provides preliminary guidance for managing both natural and farmed oyster populations. 

Context. Protostellar jets are an important agent of star formation feedback, tightly connected with the mass-accretion process. The history of jet formation and mass ejection provides constraints on the mass accretion history and on the nature of the driving source. Aims. We characterize the time-variability of the mass-ejection phenomena at work in the class 0 protostellar phase in order to better understand the dynamics of the outflowing gas and bring more constraints on the origin of the jet chemical composition and the mass-accretion history. Methods. Using the NOrthern Extended Millimeter Array (NOEMA) interferometer, we have observed the emission of the CO 2–1 and SO N J = 5 4 –4 3 rotational transitions at an angular resolution of 1.0″ (820 au) and 0.4″ (330 au), respectively, toward the intermediate-mass class 0 protostellar system Cep E. Results. The CO high-velocity jet emission reveals a central component of ≤400 au diameter associated with high-velocity molecular knots that is also detected in SO, surrounded by a collimated layer of entrained gas. The gas layer appears to be accelerated along the main axis over a length scale δ 0 ~ 700 au, while its diameter gradually increases up to several 1000 au at 2000 au from the protostar. The jet is fragmented into 18 knots of mass ~10 −3 M ⊙ , unevenly distributed between the northern and southern lobes, with velocity variations up to 15 km s −1 close to the protostar. This is well below the jet terminal velocities in the northern (+ 65 km s −1 ) and southern (−125 km s −1 ) lobes. The knot interval distribution is approximately bimodal on a timescale of ~50–80 yr, which is close to the jet-driving protostar Cep E-A and ~150–20 yr at larger distances >12″. The mass-loss rates derived from knot masses are steady overall, with values of 2.7 × 10 −5 M ⊙ yr −1 and 8.9 × 10 −6 M ⊙ yr −1 in the northern and southern lobe, respectively. Conclusions. The interaction of the ambient protostellar material with high-velocity knots drives the formation of a molecular layer around the jet. This accounts for the higher mass-loss rate in the northern lobe. The jet dynamics are well accounted for by a simple precession model with a period of 2000 yr and a mass-ejection period of 55 yr.