241 research outputs found

    Persistence and Memory in Patchwork Dynamics for Glassy Models

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    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

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    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

    The Interscutularis Muscle Connectome

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    The complete connectional map (connectome) of a neural circuit is essential for understanding its structure and function. Such maps have only been obtained in Caenorhabditis elegans. As an attempt at solving mammalian circuits, we reconstructed the connectomes of six interscutularis muscles from adult transgenic mice expressing fluorescent proteins in all motor axons. The reconstruction revealed several organizational principles of the neuromuscular circuit. First, the connectomes demonstrate the anatomical basis of the graded tensions in the size principle. Second, they reveal a robust quantitative relationship between axonal caliber, length, and synapse number. Third, they permit a direct comparison of the same neuron on the left and right sides of the same vertebrate animal, and reveal significant structural variations among such neurons, which contrast with the stereotypy of identified neurons in invertebrates. Finally, the wiring length of axons is often longer than necessary, contrary to the widely held view that neural wiring length should be minimized. These results show that mammalian muscle function is implemented with a variety of wiring diagrams that share certain global features but differ substantially in anatomical form. This variability may arise from the dominant role of synaptic competition in establishing the final circuit.National Institutes of Health (U.S.

    Reducing food loss in agricultural development projects through value chain efficiency

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    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

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    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

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

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    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

    Agricultural development addresses food loss and waste while reducing greenhouse gas emissions

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    Food loss and waste (FLW) reduce food available for consumption and increase the environmental burden of production. Reducing FLW increases agricultural and value-chain productivity and may reduce greenhouse gas emissions associated with feeding the global population. Although studies of interventions that reduce FLW exist, almost no research systematically investigates FLW interventions across multiple value chains or countries, most likely due to challenges in collecting and synthesizing data and estimates, let alone estimating greenhouse gas emissions. Our research team investigated changes in FLW in projects supported by the United States Agency for International Development\u27s (USAID) global hunger and food security initiative, Feed the Future. This was a unique opportunity to conduct ex-ante estimates of the impacts of FLW interventions across 20 value chains in 12 countries, based on project documents and interviews with USAID and project staff. This paper describes specific interventions in each value chain and country context, providing insight to interventions that decrease FLW at multiple points along food value chains, from upstream producer-dominated stages to downstream consumer-dominated stages. Amongst the sub-sectors studied, FLW interventions directed at extensive dairy systems could decrease FLW by 4–10%, providing meaningful greenhouse gas mitigation, since these systems are both emission-intensive and experience high FLW. More modest emissions reductions were found for other key agricultural products, including maize, rice, vegetables, fruits and market goods

    Parliamentary reaction to the announcement and implementation of the UK Soft Drinks Industry Levy: applied thematic analysis of 2016-2020 parliamentary debates

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    Objective: The UK Soft Drinks Industry Levy (SDIL) (announced in March 2016; implemented in April 2018) aims to incentivise reformulation of soft drinks to reduce added sugar levels. The SDIL has been applauded as a policy success, and it has survived calls from parliamentarians for it to be repealed. We aimed to explore parliamentary reaction to the SDIL following its announcement until two years post-implementation in order to understand how health policy can become established and resilient to opposition. Design: Searches of Hansard for parliamentary debate transcripts that discussed the SDIL retrieved 186 transcripts, with 160 included after screening. Five stages of Applied Thematic Analysis were conducted: familiarisation and creation of initial codebooks; independent second coding; codebook finalisation through team consensus; final coding of the dataset to the complete codebook; and theme finalisation through team consensus. Setting: The United Kingdom Parliament. Participants: N/A Results: Between the announcement (16/03/2016) – royal assent (26/04/2017), two themes were identified 1: SDIL welcomed cross-party 2: SDIL a good start but not enough. Between royal assent – implementation (5/04/2018), one theme was identified 3: The SDIL worked – what next? The final theme identified from implementation until 16/03/2020 was 4: Moving on from the SDIL. Conclusions: After the announcement, the SDIL had cross-party support and was recognised to have encouraged reformulation prior to implementation. Lessons for governments indicate that the combination of cross-party support and a policy’s documented success in achieving its aim can help cement the resilience of it to opposition and threats of repeal
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