We present a theory and accompanying importance sampling method for computing rate constants in spatially inhomogeneous systems. Using the relationship between rate constants and path space partition functions, we illustrate that the relative change in the rate of a rare event through space is isomorphic to the calculation of a free energy difference, albeit in a trajectory ensemble. Like equilibrium free energies, relative rate constants can be estimated by importance sampling. An extension to transition path sampling is proposed that combines biased path ensembles and weighted histogram analysis to accomplish this estimate. We show that rate constants can also be decomposed into different contributions, including relative changes in stability, barrier height, and flux. This decomposition provides a means of interpretation and insight into rare processes in complex environments. We verify these ideas with a simple model of diffusion with spatially varying diffusivity and illustrate their utility in a model of ion pair dissociation near an electrochemical interface.
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http://dx.doi.org/10.1063/1.5092837 | DOI Listing |
Despite advancements in surgical techniques for rotator cuff repair, retear rates remain a significant concern. This study systematically reviews the evidence on the effectiveness of the Regeneten Bioinductive Implant in improving healing outcomes. A systematic review of the literature was conducted by searching on PubMed, Embase, Web of Science Core Collection and Cochrane Library.
View Article and Find Full Text PDFRev Esc Enferm USP
January 2025
Universidade Federal de Viçosa, Departamento de Medicina e Enfermagem, Viçosa, MG, Brazil.
Objective: To compare the effectiveness of ear acupuncture with laser and needles in the treatment of anxiety in university students in the post-pandemic context of Covid-19, as well as to evaluate the possible symptoms or adverse reactions triggered by the interventions.
Method: Randomized clinical trial carried out with 126 university students, allocated to the "Needle" (control) and "Laser" (experimental) groups. Five ear acupuncture sessions were performed.
J Gen Physiol
March 2025
Department of Animal, Veterinary, and Food Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, USA.
The mechanisms underlying cooperative activation and inactivation of myocardial force extend from local, near-neighbor interactions involving troponin-tropomyosin regulatory units (RU) and crossbridges (XB) to more global interactions across the sarcomere. To better understand these mechanisms in the hearts of small and large mammals, we undertook a simplified mathematical approach to assess the contribution of three types of near-neighbor cooperative interactions, i.e.
View Article and Find Full Text PDFUnlabelled: Electric fields used in clinical trials with transcranial direct current stimulation (tDCS) are small, with magnitudes that have yet to demonstrate measurable effects in preclinical animal models. We hypothesized that weak stimulation will nevertheless produce sizable effects, provided that it is applied concurrently with behavioral training, and repeated over multiple sessions. We tested this here in a rodent model of dexterous motor-skill learning.
View Article and Find Full Text PDFEven after folding, proteins transiently sample unfolded or partially unfolded intermediates, and these species are often at risk of irreversible alteration ( via proteolysis, aggregation, or post-translational modification). Kinetic stability, in addition to thermodynamic stability, can directly impact protein lifetime, abundance, and the formation of alternative, sometimes disruptive states. However, we have very few measurements of protein unfolding rates or how mutations alter these rates, largely due to technical challenges associated with their measurement.
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