Tensor-network method to simulate strongly interacting quantum thermal machines

We present a methodology to simulate the quantum thermodynamics of thermal machines which are built from an interacting working medium in contact with fermionic reservoirs at fixed temperature and chemical potential. Our method works at finite temperature, beyond linear response and weak system-reservoir coupling, and allows for non-quadratic interactions in the working medium. The method uses mesoscopic reservoirs, continuously damped towards thermal equilibrium, in order to represent continuum baths and a novel tensor network algorithm to simulate the steady-state thermodynamics. Using the example of a quantum-dot heat engine, we demonstrate that our technique replicates the well known Landauer-B\"uttiker theory for efficiency and power. We then go beyond the quadratic limit to demonstrate the capability of our method by simulating a three-site machine with non-quadratic interactions. Remarkably, we find that such interactions lead to power enhancement, without being detrimental to the efficiency. Furthermore, we demonstrate the capability of our method to tackle complex many-body systems by extracting the super-diffusive exponent for high-temperature transport in the isotropic Heisenberg model. Finally, we discuss transport in the gapless phase of the anisotropic Heisenberg model at finite temperature and its connection to charge conjugation-parity, going beyond the predictions of single-site boundary driving configurations.Comment: 21 figures, 25 pages. Updated results, content and references. Journal version (Feature in APS Physics

Future of Leadership in Healthcare: Enabling Complexity Dynamics Across Levels

Healthcare is one of the world\u27s fastest-growing industries with over $10 trillion in projected spending by 2022 (Deloitte, 2019). Despite this growth, the industry faces several challenges including rising costs, care delivery outside urban areas and to marginalized populations, digital transformation, and regulatory compliance. To navigate these challenges and capitalize on growth opportunities, leaders must build and manage complex dynamics occurring in the space between the organization and a wide range of internal and external stakeholders. In this symposium, we address this issue by assembling a group of scholars trained in healthcare management, strategy, leadership, and organizational theory to discuss the role of leaders in the future of healthcare. Through a series of presentations, we will illustrate how leaders in healthcare enable complexity dynamics across organizational levels to drive desired outcomes. In doing so, we bring to the forefront the multilevel and complex nature of healthcare leadership and invite innovative thinking about leadership for the future of healthcare. Building Extra-Organizational Adaptive Networks: Complexity Leadership in Healthcare Presenter: Erin Bass; U. of Nebraska, Omaha Presenter: Ivana Milosevic; College of Charleston Physician CEOs & Patient Safety Presenter: Geoffrey Silvera; Auburn U. Presenter: Timothy J. Vogus; Vanderbilt U. Presenter: Jonathan Clark; U. of Texas At San Antonio Management Practices of Under-Resourced Nursing Homes Presenter: Justin Lord; Louisiana State U. Shreveport Stitching Ties: Team Performance in the Connected Organization Presenter: John Hollingsworth; U. of Michigan Presenter: Jason Owen-Smith; U. of Michigan, Ann Arbor Presenter: Dennie Kim; U. of Virginia Darden School of Business Presenter: Marlon DeMarcie Twyman; U. of Southern California, Annenberg School for Communication and Journalism Identifying Healthcare\u27s Future Leaders: Development of a Leadership Potential Model for Healthcare Presenter: Kevin S. Groves; Pepperdine U. Presenter: Ann E. Feyerherm; Pepperdine Graziadio Business Schoo

diXa: a data infrastructure for chemical safety assessment

Motivation: The field of toxicogenomics (the application of ‘-omics' technologies to risk assessment of compound toxicities) has expanded in the last decade, partly driven by new legislation, aimed at reducing animal testing in chemical risk assessment but mainly as a result of a paradigm change in toxicology towards the use and integration of genome wide data. Many research groups worldwide have generated large amounts of such toxicogenomics data. However, there is no centralized repository for archiving and making these data and associated tools for their analysis easily available. Results: The Data Infrastructure for Chemical Safety Assessment (diXa) is a robust and sustainable infrastructure storing toxicogenomics data. A central data warehouse is connected to a portal with links to chemical information and molecular and phenotype data. diXa is publicly available through a user-friendly web interface. New data can be readily deposited into diXa using guidelines and templates available online. Analysis descriptions and tools for interrogating the data are available via the diXa portal. Availability and implementation: http://www.dixa-fp7.eu Contact: [email protected]; [email protected] Supplementary information: Supplementary data are available at Bioinformatics onlin

Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape

Citation: Leys, B. A., Commerford, J. L., & McLauchlan, K. K. (2017). Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape. Plos One, 12(4), 15. doi:10.1371/journal.pone.0176445Fire is a key Earth system process, with 80% of annual fire activity taking place in grassland areas. However, past fire regimes in grassland systems have been difficult to quantify due to challenges in interpreting the charcoal signal in depositional environments. To improve reconstructions of grassland fire regimes, it is essential to assess two key traits: (1) charcoal count, and (2) charcoal shape. In this study, we quantified the number of charcoal pieces in 51 sediment samples of ponds in the Great Plains and tested its relevance as a proxy for the fire regime by examining 13 potential factors influencing charcoal count, including various fire regime components (e.g. the fire frequency, the area burned, and the fire season), vegetation cover and pollen assemblages, and climate variables. We also quantified the width to length (W: L) ratio of charcoal particles, to assess its utility as a proxy of fuel types in grassland environments by direct comparison with vegetation cover and pollen assemblages. Our first conclusion is that charcoal particles produced by grassland fires are smaller than those produced by forest fires. Thus, a mesh size of 120 mu m as used in forested environments is too large for grassland ecosystems. We recommend counting all charcoal particles over 60 mu m in grasslands and mixed grass-forest environments to increase the number of samples with useful data. Second, a W: L ratio of 0.5 or smaller appears to be an indicator for fuel types, when vegetation surrounding the site is before composed of at least 40% grassland vegetation. Third, the area burned within 1060m of the depositional environments explained both the count and the area of charcoal particles. Therefore, changes in charcoal count or charcoal area through time indicate a change in area burned. The fire regimes of grassland systems, including both human and climatic influences on fire behavior, can be characterized by long-term charcoal records

Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia

Forest fires are a key disturbance in boreal forests, and characteristics of fire regimes are among the most important factors explaining the variation in forest structure and species composition. The occurrence of fire is connected with climate, but earlier, mostly local-scale studies in the northern European boreal forests have provided little insight into fire-climate relationship before the modern fire suppression period. Here, we compiled annually resolved fire history, temperature, and precipitation reconstructions from eastern Fennoscandia from the mid-16th century to the end of the 19th century, a period of strong human influence on fires. We used synchrony of fires over the network of 25 fire history reconstructions as a measure of climatic forcing on fires. We examined the relationship between fire occurrence and climate (summer temperature, precipitation, and a drought index summarizing the influence of variability in temperature and precipitation) across temporal scales, using a scale space multiresolution correlation approach and Bayesian inference that accounts for the annually varying uncertainties in climate reconstructions. At the annual scale, fires were synchronized during summers with low precipitation, and most clearly during drought summers. A scale-derivative analysis revealed that fire synchrony and climate varied at similar, roughly decadal scales. Climatic variables and fire synchrony showed varying correlation strength and credibility, depending on the climate variable and the time period. In particular, precipitation emerged as a credible determinant of fire synchrony also at these time scales, despite the large uncertainties in precipitation reconstruction. The findings explain why fire occurrence can be high during cold periods (such as from the mid-17th to early-18th century), and stresses the notion that future fire frequency will likely depend to a greater extent on changes in precipitation than temperature alone. We showed, for the first time, the importance of climate as a decadal-scale driver of forest fires in the European boreal forests, discernible even during a period of strong human influence on fire occurrence. The fire regime responded both to anomalously dry summers, but also to decadal-scale climate changes, demonstrating how climatic variability has shaped the disturbance regimes in the northern European boreal forests over various time scales.Peer reviewe

History of fires and vegetation since the Neolithic in the Cantabrian Mountains (Spain)

Fire has been one of the main causes of disturbance of vegetation over time, and since the Neolithic has become an irreplaceable tool for the opening of forest spaces and maintenance of pastures. Previous studies showed that the intensity and effects of wildfires are related to the biomass and controlled by climate factors. However, in regions such as Cantabria, where agriculture and livestock have spread throughout the territory since prehistory, fires should also be closely related to human land uses. The aim of this paper was to investigate the history of fires and vegetation since the Neolithic in the Cantabrian Mountains, using sedimentary charcoal and pollen data to study the role of human activities in the processes that have shaped ecosystems throughout the Holocene. The asynchrony and quantitative differences in the results obtained at different sites indicate significant variations in fire patterns at regional scale since the Neolithic, although the type and size of each basin also had a strong influence on charcoal accumulation. Maximum values for charcoal accumulation rate at La Molina were observed between the Neolithic and the Bronze Age but occurred after about 3500 cal years BP at El Cueto de la Avellanosa. At El Sertal, low charcoal accumulation rate values were observed, probably because the sequence begins in a space that already had been cleared; the maximum values occurred during the most recent millennium. These data provide evidence that fire has been a key factor in forest retreat and in maintaining open landscapes since the Neolithic.This article was made possible by two Coordinated Project grants from Spain's Ministry of Economics and Competitiveness (MEC), “El uso del fuego y la conformación de los paisajes en la Montaña cantábrica y el Pirineo oriental: estudio comparado de su evolución histórica y tendencias actuales” (CSO2012-39680-C02-01) awarded to the Department of Geography, Urban studies and Land Planning, Universidad de Cantabria and “Geohistoria ambiental del fuego en el Holoceno. Patrones culturales y gestión territorial desde el inicio de la ganadería y la agricultura en la montaña Cantábrica y Pirineo “awarded to the Department of Geography, Universitat Autónoma de Barcelona (CSO2012-39680-C02-02). In addition, the project was funded by the Catalan government's Applied Geography program, “Grup de Geografia Aplicada” (AGAUR, Generalitat de Catalunya, 2014 SGR 1090)

Microplastics in marine sediments near Rothera Research Station, Antarctica

publisher: Elsevier articletitle: Microplastics in marine sediments near Rothera Research Station, Antarctica journaltitle: Marine Pollution Bulletin articlelink: https://doi.org/10.1016/j.marpolbul.2018.05.068 content_type: article copyright: © 2018 Elsevier Ltd. All rights reserved