Exosuit-induced improvements in walking after stroke: comprehensive analysis on gait energetics and biomechanics

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Biomechanical mechanisms underlying exosuit-induced improvements in walking economy after stroke

Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance—walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint powers, and metabolic power. Compared to walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2= 0.83, P= 0.004) and nonparetic (R2= 0.73, P= 0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in nonparetic limb COM power (R2= 0.80, P= 0.007), not paretic limb COM power (P> 0.05). These findings provide a fundamental understanding of how individuals poststroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.Accepted manuscript2019-03-0

Non-topological solitons as nucleation sites for cosmological phase transitions

I consider quantum field theories that admit charged non-topological solitons of the Q-ball type, and use the fact that in a first-order cosmological phase transition, below the critical temperature, there is a value of the soliton charge above which the soliton becomes unstable and expands, converting space to the true vacuum, much like a critical bubble in the case of ordinary tunneling. Using a simple model for the production rate of Q-balls through charge accretion during a random walk out of equilibrium, I calculate the probability for the formation of critical charge solitons and estimate the amount of supercooling needed for the phase transition to be completed.Comment: 20 pages, 2 figures, some comments and references adde

A protocol to determine seed storage behaviour

This publications provides an approach by which conservationists can determine whether or not long-term seed storage is feasible for a particular species, i.e. whether or not that species shows orthodox seed storage behaviour. It provides advice on the implementation of the protocol, examples of ways in which the results from seed storage studies could be misinterpreted due to confounding factors, as well as several alternative approaches for estimating seed storage behaviour prior to carrying out actual investigations with the seeds. In particular, the latter section introduces the concept of a multicriteria approach for estimating seed storage behaviour. It is intended to be used along with the Compendium (see IPGRI Handbooks for Genebanks No.4 - Seed Storage behaviour: a Compendium); these two publications are essentially complementary. The overall aim of the protocol is to guide and encourage further work in this area of seed physiology (particularly for species on which relatively less work has been done to date)m with the objective to expanding on/up-dating the type of species-specific data compiled in the compendium

Phase Transition in Ferromagnetic Ising Models with Non-Uniform External Magnetic Fields

In this article we study the phase transition phenomenon for the Ising model under the action of a non-uniform external magnetic field. We show that the Ising model on the hypercubic lattice with a summable magnetic field has a first-order phase transition and, for any positive (resp. negative) and bounded magnetic field, the model does not present the phase transition phenomenon whenever $\liminf h_i> 0$, where ${\bf h} = (h_i)_{i \in \Z^d}$ is the external magnetic field.Comment: 11 pages. Published in Journal of Statistical Physics - 201

Implications of Space-Time foam for Entanglement Correlations of Neutral Kaons

The role of $CPT$ invariance and consequences for bipartite entanglement of neutral (K) mesons are discussed. A relaxation of $CPT$ leads to a modification of the entanglement which is known as the $\omega$ effect. The relaxation of assumptions required to prove the $CPT$ theorem are examined within the context of models of space-time foam. It is shown that the evasion of the EPR type entanglement implied by $CPT$ (which is connected with spin statistics) is rather elusive. Relaxation of locality (through non-commutative geometry) or the introduction of decoherence by themselves do not lead to a destruction of the entanglement. So far we find only one model which is based on non-critical strings and D-particle capture and recoil that leads to a stochastic contribution to the space-time metric and consequent change in the neutral meson bipartite entanglement. The lack of an omega effect is demonstrated for a class of models based on thermal like baths which are generally considered as generic models of decoherence

Seed storage behavior: a compendium

This handbook provides an introduction to seed storage physiology for those responsible for plant genetic conservation and a selective summary of the literature on seed survival in storage, and thus on seed storage behaviour, for over 7000 species from 251 families. Part IA summarizes progress in our understanding of seed physiology in relation to seed storage for genetic conservation in the past 17 years since the publication of The Storage of Recalcitrant Seeds: Achievements and Possible Approaches by King and Roberts (1979), and particularly the various problems that may result in the misclassification of seed storage behaviour. Part IB provides a compendium of information on seed survival during storage and attempts to classify plant species into the several categories of seed storage behaviour. You can search the data on seed storage behavio

Scaling Solutions and reconstruction of Scalar Field Potentials

Starting from the hypothesis of scaling solutions, the general exact form of the scalar field potential is found. In the case of two fluids, it turns out to be a negative power of hyperbolic sine. In the case of three fluids the analytic form is not found, but is obtained by quadratures.Comment: 5 pages, 2 figures, some changes in references and figures caption

Neutrino-Deuteron Scattering in Effective Field Theory at Next-to-Next-to Leading Order

We study the four channels associated with neutrino-deuteron breakup reactions at next-to-next to leading order in effective field theory. We find that the total cross-section is indeed converging for neutrino energies up to 20 MeV, and thus our calculations can provide constraints on theoretical uncertainties for the Sudbury Neutrino Observatory. We stress the importance of a direct experimental measurement to high precision in at least one channel, in order to fix an axial two-body counterterm.Comment: 32 pages, 14 figures (eps