Persistence and Memory in Patchwork Dynamics for Glassy Models

Slow dynamics in disordered materials prohibits direct simulation of their rich nonequilibrium behavior at large scales. "Patchwork dynamics" is introduced to mimic relaxation over a very broad range of time scales by equilibrating or optimizing directly on successive length scales. This dynamics is used to study coarsening and to replicate memory effects for spin glasses and random ferromagnets. It is also used to find, with high confidence, exact ground states in large or toroidal samples.Comment: 4 pages, 4 figures; reference correctio

Short-Term Memory in Orthogonal Neural Networks

We study the ability of linear recurrent networks obeying discrete time dynamics to store long temporal sequences that are retrievable from the instantaneous state of the network. We calculate this temporal memory capacity for both distributed shift register and random orthogonal connectivity matrices. We show that the memory capacity of these networks scales with system size.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

Reducing food loss in agricultural development projects through value chain efficiency

Food loss and waste (FLW) reduces the amount of food available for distribution and consumption, decreases food security, and increases the environmental burden of food production. Combating FLW addresses the key pillars of climate-smart agriculture for farmers by increasing productivity, promoting adaption to climate change, and mitigating greenhouse gas emissions. Although studies of interventions to reduce FLW exist, almost no research systematically investigates FLW interventions across value chains or in multiple countries, most likely due to challenges in collecting and synthesizing multi-country estimates. Our research team investigated changes in FLW in projects supported by the United States Government’s global hunger and food security initiative: Feed the Future. This provided a unique opportunity to conduct ex-ante estimates of the impacts of interventions across 20 value chains in 12 countries based on interviews with United States Agency for International Development (USAID) and project staff. We provide specific examples of interventions used in each value chain and country context. The results provide an evidence base of interventions that successfully decreased FLW at multiple points along the food value chain, from upstream producer-dominated stages to downstream consumer-dominated stages. Results also show that no single FLW solution or intervention works across agriculture sub-sectors, value chain stages, and countries. Amongst the sub-sectors studied, results showed that FLW interventions directed at extensive dairy systems could provide meaningful greenhouse mitigation. In the dairy supply chain, FLW estimates ranged from 5-50% in the business-as- usual approach and declined 4-10% as a result of intervention

Taking a PEEK into YOLOv5 for Satellite Component Recognition via Entropy-based Visual Explanations

The escalating risk of collisions and the accumulation of space debris in Low Earth Orbit (LEO) has reached critical concern due to the ever increasing number of spacecraft. Addressing this crisis, especially in dealing with non-cooperative and unidentified space debris, is of paramount importance. This paper contributes to efforts in enabling autonomous swarms of small chaser satellites for target geometry determination and safe flight trajectory planning for proximity operations in LEO. Our research explores on-orbit use of the You Only Look Once v5 (YOLOv5) object detection model trained to detect satellite components. While this model has shown promise, its inherent lack of interpretability hinders human understanding, a critical aspect of validating algorithms for use in safety-critical missions. To analyze the decision processes, we introduce Probabilistic Explanations for Entropic Knowledge extraction (PEEK), a method that utilizes information theoretic analysis of the latent representations within the hidden layers of the model. Through both synthetic in hardware-in-the-loop experiments, PEEK illuminates the decision-making processes of the model, helping identify its strengths, limitations and biases

Mechanical thrombectomy in patients with acute ischemic stroke: a cost-effectiveness and value of implementation analysis

Background: Recent clinical trials have demonstrated the efficacy of mechanical thrombectomy in acute ischemic stroke. Aims: To determine the cost-effectiveness, value of future research, and value of implementation of mechanical thrombectomy. Methods: Using UK clinical and cost data from the Pragmatic Ischemic Stroke Thrombectomy Evaluation (PISTE) trial, we estimated the cost-effectiveness of mechanical thrombectomy over time horizons of 90-days and lifetime, based on a decision-analytic model, using all existing evidence. We performed a meta-analysis of seven clinical trials to estimate treatment effects. We used sensitivity analysis to address uncertainty. Value of implementation analysis was used to estimate the potential value of additional implementation activities to support routine delivery of mechanical thrombectomy. Results: Over the trial period (90 days), compared with best medical care alone, mechanical thrombectomy incurred an incremental cost of £5207 and 0.025 gain in QALY (incremental cost-effectiveness ratio (ICER) £205,279), which would not be considered cost-effective. However, mechanical thrombectomy was shown to be cost-effective over a lifetime horizon, with an ICER of £3466 per QALY gained. The expected value of perfect information per patient eligible for mechanical thrombectomy in the UK is estimated at £3178. The expected value of full implementation of mechanical thrombectomy is estimated at £1.3 billion over five years. Conclusion: Mechanical thrombectomy was cost-effective compared with best medical care alone over a patient’s lifetime. On the assumption of 30% implementation being achieved throughout the UK healthcare system, we estimate that the population health benefits obtained from this treatment are greater than the cost of implementation. Trial registration: NCT01745692

Everything Is Science: A Free City-Wide Science Festival

A week-long, city-wide science festival called Everything is Science (EiS) was developed to educate the community in an informal manner. The festival serves as a platform for presenters from diverse professions to give engaging talks (without PowerPoint slides) to the public, free of charge, in restaurants and bars around town. Over 350 people attended the events over 5 days with 33 presenters. Surveys completed by attendees and session coordinators indicate strong support for this festival. Altogether, the EiS festival serves as a no-cost method to engage with the community and improve science literacy with potential for adoption in other cities

The Stellar Content of Obscured Galactic Giant H II Regions IV.: NGC3576

We present deep, high angular resolution near-infrared images of the obscured Galactic Giant H II region NGC3576. Our images reach objects to ~3M_sun. We collected high signal-to-noise K-band spectra of eight of the brightest objects, some of which are affected by excess emission and some which follow a normal interstellar reddening law. None of them displayed photospheric features typical of massive OB type stars. This indicates that they are still enshrouded in their natal cocoons. The K-band brightest source (NGC3576 #48) shows CO 2.3 micron bandhead emission, and three others have the same CO feature in absorption. Three sources display spatially unresolved H_2 emission, suggesting dense shocked regions close to the stars. We conclude that the remarkable object NGC3576 #48 is an early-B/late-O star surrounded by a thick circumstellar disk. A number of other relatively bright cluster members also display excess emission in the K-band, indicative of reprocessing disks around massive stars (YSOs). Such emission appears common in other Galactic Giant H II regions we have surveyed. The IMF slope of the cluster, Gamma = -1.51, is consistent with Salpeter's distribution and similar to what has been observed in the Magellanic Cloud clusters and in the periphery of our Galaxy.Comment: 14 pages, 11 figures, accepted for publication in A

Oxidation of Thiols to Disulfides using an Environmentally “Green” Organocatalyst and New Mechanistic Insights

The selective oxidation of thiols to disulfides is an area of great importance in the areas of materials and medicinal chemistry research. The production of polymers, rubber, pharmaceuticals, and the folding of proteins in biological systems all rely on the formation of disulfide bonds. Herein, we introduce a stoichiometric and electrocatalytic method for the oxidation of various pharmaceutically and biologically relevant thiols into their respective disulfides in more environmentally benign solvents such as water and alcohol solvents. The scope of the transformation was evaluated and a detailed mechanistic study involving control experiments, experimental kinetic studies, and computational investigations led to new insights into how the oxidation takes place via an unusual anionic process