Showing papers by "United States Department of Energy published in 2021"

A unified catalog of 204,938 reference genomes from the human gut microbiome.

Abstract: Comprehensive, high-quality reference genomes are required for functional characterization and taxonomic assignment of the human gut microbiota. We present the Unified Human Gastrointestinal Genome (UHGG) collection, comprising 204,938 nonredundant genomes from 4,644 gut prokaryotes. These genomes encode >170 million protein sequences, which we collated in the Unified Human Gastrointestinal Protein (UHGP) catalog. The UHGP more than doubles the number of gut proteins in comparison to those present in the Integrated Gene Catalog. More than 70% of the UHGG species lack cultured representatives, and 40% of the UHGP lack functional annotations. Intraspecies genomic variation analyses revealed a large reservoir of accessory genes and single-nucleotide variants, many of which are specific to individual human populations. The UHGG and UHGP collections will enable studies linking genotypes to phenotypes in the human gut microbiome.

Metagenomic compendium of 189,680 DNA viruses from the human gut microbiome.

Abstract: Bacteriophages have important roles in the ecology of the human gut microbiome but are under-represented in reference databases. To address this problem, we assembled the Metagenomic Gut Virus catalogue that comprises 189,680 viral genomes from 11,810 publicly available human stool metagenomes. Over 75% of genomes represent double-stranded DNA phages that infect members of the Bacteroidia and Clostridia classes. Based on sequence clustering we identified 54,118 candidate viral species, 92% of which were not found in existing databases. The Metagenomic Gut Virus catalogue improves detection of viruses in stool metagenomes and accounts for nearly 40% of CRISPR spacers found in human gut Bacteria and Archaea. We also produced a catalogue of 459,375 viral protein clusters to explore the functional potential of the gut virome. This revealed tens of thousands of diversity-generating retroelements, which use error-prone reverse transcription to mutate target genes and may be involved in the molecular arms race between phages and their bacterial hosts.

NOAA National Centers for Environmental Information Fisheries Acoustics Archive Network Deep Dive

Abstract: Author(s): Zurawski, Jason; Addleman, Hans; Miller, Ken; Southworth, Doug | Abstract: EPOC uses the Deep Dive process to discuss and analyze current and planned science use cases and anticipated data output of a particular use case, site, or project to help inform the strategic planning of a campus or regional networking environment. This includes understanding future needs related to network operations, network capacity upgrades, and other technological service investments. A Deep Dive comprehensively surveys major research stakeholders’ plans and processes in order to investigate data management requirements over the next 5–10 years. Deep Dives help ensure that key stakeholders have a common understanding of the issues and the actions that a campus or regional network may need to undertake to offer solutions. The EPOC team leads the effort and relies on collaboration with the hosting site or network, and other affiliated entities that participate in the process. EPOC organizes, convenes, executes, and shares the outcomes of the review with all stakeholders. Between May 2021 and August 2021, staff members from the Engagement and Performance Operations Center (EPOC) met with researchers and staff from the National Oceanic and Atmospheric Administration (NOAA)'s N-Wave (the Enterprise network that supports the NOAA mission) and National Centers for Environmental Information (NCEI)'s Fisheries Acoustics Archive for the purpose of a recording a Deep Dive into research drivers. The goal of these meetings was to help characterize the requirements for the research use case, and to enable cyberinfrastructure support staff to better understand the needs of the researchers they support.

Expert elicitation survey predicts 37% to 49% declines in wind energy costs by 2050

Abstract: Wind energy has experienced accelerated cost reduction over the past five years—far greater than predicted in a 2015 expert elicitation. Here we report results from a new survey on wind costs, compare those with previous results and discuss the accuracy of the earlier predictions. We show that experts in 2020 expect future onshore and offshore wind costs to decline 37–49% by 2050, resulting in costs 50% lower than predicted in 2015. This is due to cost reductions witnessed over the past five years and expected continued advancements. If realized, these costs might allow wind to play a larger role in energy supply than previously anticipated. Considering both surveys, we also conclude that there is considerable uncertainty about future costs. Our results illustrate the importance of considering cost uncertainty, highlight the value and limits of using experts to reveal those uncertainties, and yield possible lessons for energy modellers and expert elicitation. Costs of renewable energy generation have fallen rapidly in recent years, often faster than predicted. Wiser et al. undertake an expert elicitation survey to project wind power costs to 2050, finding substantial continued cost reductions, and compare back to a previous survey to understand what has changed.

Calendar aging of silicon-containing batteries

Abstract: High-energy batteries for automotive applications require cells to endure well over a decade of constant use, making their long-term stability paramount. This is particularly challenging for emerging cell chemistries containing silicon, for which extended testing information is scarce. While much of the research on silicon anodes has focused on mitigating the consequences of volume changes during cycling, comparatively little is known about the time-dependent degradation of silicon-containing batteries. Here we discuss a series of studies on the reactivity of silicon that, collectively, paint a picture of how the chemistry of silicon exacerbates the calendar aging of lithium-ion cells. Assessing and mitigating this shortcoming should be the focus of future research to fully realize the benefits of this battery technology. Silicon-containing batteries are increasingly becoming a reality in the mass market, but their calendar aging behaviours have received comparatively little attention. Researchers from the Silicon Consortium Project discuss the issues surrounding the calendar lifetime of silicon anodes for lithium-ion batteries.

Boosting CO 2 Electrochemical Reduction with Atomically Precise Surface Modification on Gold Nanoclusters.

Abstract: Thiolate-protected gold nanoclusters (NCs) are promising catalytic materials for the electrochemical CO2 reduction reaction (CO2 RR). In this work an atomic level modification of a Au23 NC is made by substituting two surface Au atoms with two Cd atoms, and it enhances the CO2 RR selectivity to 90-95 % at the applied potential between -0.5 to -0.9 V, which is doubled compared to that of the undoped Au23 . Additionally, the Cd-doped Au19 Cd2 exhibits the highest CO2 RR activity (2200 mA mg-1 at -1.0 V vs. RHE) among the reported NCs. This synergetic effect between Au and Cd is remarkable. Density-functional theory calculations reveal that the exposure of a sulfur active site upon partial ligand removal provides an energetically feasible CO2 RR pathway. The thermodynamic energy barrier for CO formation is 0.74 eV lower on Au19 Cd2 than on Au23 . These results reveal that Cd doping can boost the CO2 RR performance of Au NCs by modifying the surface geometry and electronic structure, which further changes the intermediate binding energy. This work offers insights into the surface doping mechanism of the CO2 RR and bimetallic synergism.

High-throughput design of high-performance lightweight high-entropy alloys.

Abstract: Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further improves the accuracy of the thermodynamic database of the discovered alloy system. This study shows that integrating high-throughput screening, multiscale modeling, and experimental validation proves to be efficient and useful in accelerating the discovery of advanced precipitation-strengthened structural materials tuned by the high-entropy alloy concept.

Deep ocean metagenomes provide insight into the metabolic architecture of bathypelagic microbial communities.

Abstract: The deep sea, the largest ocean’s compartment, drives planetary-scale biogeochemical cycling. Yet, the functional exploration of its microbial communities lags far behind other environments. Here we analyze 58 metagenomes from tropical and subtropical deep oceans to generate the Malaspina Gene Database. Free-living or particle-attached lifestyles drive functional differences in bathypelagic prokaryotic communities, regardless of their biogeography. Ammonia and CO oxidation pathways are enriched in the free-living microbial communities and dissimilatory nitrate reduction to ammonium and H 2 oxidation pathways in the particle-attached, while the Calvin Benson-Bassham cycle is the most prevalent inorganic carbon fixation pathway in both size fractions. Reconstruction of the Malaspina Deep Metagenome-Assembled Genomes reveals unique non-cyanobacterial diazotrophic bacteria and chemolithoautotrophic prokaryotes. The widespread potential to grow both autotrophically and heterotrophically suggests that mixotrophy is an ecologically relevant trait in the deep ocean. These results expand our understanding of the functional microbial structure and metabolic capabilities of the largest Earth aquatic ecosystem.

Control of polarization in bulk ferroelectrics by mechanical dislocation imprint

Abstract: Defects are essential to engineering the properties of functional materials ranging from semiconductors and superconductors to ferroics. Whereas point defects have been widely exploited, dislocatio...

A light-induced phononic symmetry switch and giant dissipationless topological photocurrent in ZrTe5

Abstract: Dissipationless currents from topologically protected states are promising for disorder-tolerant electronics and quantum computation. Here, we photogenerate giant anisotropic terahertz nonlinear currents with vanishing scattering, driven by laser-induced coherent phonons of broken inversion symmetry in a centrosymmetric Dirac material ZrTe5. Our work suggests that this phononic terahertz symmetry switching leads to formation of Weyl points, whose chirality manifests in a transverse, helicity-dependent current, orthogonal to the dynamical inversion symmetry breaking axis, via circular photogalvanic effect. The temperature-dependent topological photocurrent exhibits several distinct features: Berry curvature dominance, particle–hole reversal near conical points and chirality protection that is responsible for an exceptional ballistic transport length of ~10 μm. These results, together with first-principles modelling, indicate two pairs of Weyl points dynamically created by B1u phonons of broken inversion symmetry. Such phononic terahertz control breaks ground for coherent manipulation of Weyl nodes and robust quantum transport without application of static electric or magnetic fields. Femtosecond optical pulses are used to generate coherent phonons that break inversion symmetry and drive anisotropic terahertz photocurrents in the topological material ZrTe5.

FLUXNET-CH4: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands

Abstract: . Methane (CH4) emissions from natural landscapes constitute roughly half of global CH4 contributions to the atmosphere, yet large uncertainties remain in the absolute magnitude and the seasonality of emission quantities and drivers. Eddy covariance (EC) measurements of CH4 flux are ideal for constraining ecosystem-scale CH4 emissions due to quasi-continuous and high-temporal-resolution CH4 flux measurements, coincident carbon dioxide, water, and energy flux measurements, lack of ecosystem disturbance, and increased availability of datasets over the last decade. Here, we (1) describe the newly published dataset, FLUXNET-CH4 Version 1.0, the first open-source global dataset of CH4 EC measurements (available at https://fluxnet.org/data/fluxnet-ch4-community-product/, last access: 7 April 2021). FLUXNET-CH4 includes half-hourly and daily gap-filled and non-gap-filled aggregated CH4 fluxes and meteorological data from 79 sites globally: 42 freshwater wetlands, 6 brackish and saline wetlands, 7 formerly drained ecosystems, 7 rice paddy sites, 2 lakes, and 15 uplands. Then, we (2) evaluate FLUXNET-CH4 representativeness for freshwater wetland coverage globally because the majority of sites in FLUXNET-CH4 Version 1.0 are freshwater wetlands which are a substantial source of total atmospheric CH4 emissions; and (3) we provide the first global estimates of the seasonal variability and seasonality predictors of freshwater wetland CH4 fluxes. Our representativeness analysis suggests that the freshwater wetland sites in the dataset cover global wetland bioclimatic attributes (encompassing energy, moisture, and vegetation-related parameters) in arctic, boreal, and temperate regions but only sparsely cover humid tropical regions. Seasonality metrics of wetland CH4 emissions vary considerably across latitudinal bands. In freshwater wetlands (except those between 20∘ S to 20∘ N) the spring onset of elevated CH4 emissions starts 3 d earlier, and the CH4 emission season lasts 4 d longer, for each degree Celsius increase in mean annual air temperature. On average, the spring onset of increasing CH4 emissions lags behind soil warming by 1 month, with very few sites experiencing increased CH4 emissions prior to the onset of soil warming. In contrast, roughly half of these sites experience the spring onset of rising CH4 emissions prior to the spring increase in gross primary productivity (GPP). The timing of peak summer CH4 emissions does not correlate with the timing for either peak summer temperature or peak GPP. Our results provide seasonality parameters for CH4 modeling and highlight seasonality metrics that cannot be predicted by temperature or GPP (i.e., seasonality of CH4 peak). FLUXNET-CH4 is a powerful new resource for diagnosing and understanding the role of terrestrial ecosystems and climate drivers in the global CH4 cycle, and future additions of sites in tropical ecosystems and site years of data collection will provide added value to this database. All seasonality parameters are available at https://doi.org/10.5281/zenodo.4672601 (Delwiche et al., 2021). Additionally, raw FLUXNET-CH4 data used to extract seasonality parameters can be downloaded from https://fluxnet.org/data/fluxnet-ch4-community-product/ (last access: 7 April 2021), and a complete list of the 79 individual site data DOIs is provided in Table 2 of this paper.

Graphene nanosheets derived from plastic waste for the application of DSSCs and supercapacitors

Abstract: The present study reports the upcycling process of waste plastics into value-added product graphene nanosheets (GNs) and their subsequent applications in dye sensitized solar cells (DSSCs) and supercapacitors. Bentonite nanoclay has been used as an agent for the degradation of waste plastics with two step pyrolysis processes at 450 °C and 945 °C in an inert atmosphere of N2 gas to obtain GNs. The GNs with few layers were confirmed by the RAMAN spectroscopy, XRD and HRTEM analyses. Further, FT-IR and EDX analyses also performed for the identification and quantitative analysis of functional groups in GNs. The GNs thus synthesized from plastic waste have been used for the fabrication of DSSCs and supercapacitors. The DSSC fabrication with GNs as part of photo-anode with polymeric electrolyte showed a high fill factor of 86.4% and high Voc of 0.77 V, which were also supported by the computational findings. On the other hand, the utilization of GNs as an active layer material of supercapacitor electrodes offered a high specific capacitance of 398 F/g with a scan rate of 0.005 V/s. The supercapacitor also exhibited significant energy density (Ed) and power density (Pd) of 38 Wh/kg and 1009.74 W/kg, respectively. Thus, the process illustrated the utility of waste plastics upcycling for conservation of EEE i.e., ecology, economy and energy for better tomorrow.

Improved biodiesel production from waste cooking oil with mixed methanol-ethanol using enhanced eggshell-derived CaO nano-catalyst.

Abstract: In this report, the utilization of mixed methanol-ethanol system for the production of biodiesel from waste cooking oil (WCO) using enhanced eggshell-derived calcium oxide (CaO) nano-catalyst was investigated. CaO nano-catalyst was produced by calcination of eggshell powder at 900 °C and followed by hydration-dehydration treatment to improve its catalytic activity. The particle size, morphology, and elemental composition of a catalyst were characterized by using XRD, SEM, and EDX techniques, respectively. After hydration-dehydration the shape of a catalyst was changed from a rod-like to honeycomb-like porous microstructure. Likewise, average particle size was reduced from 21.30 to 13.53 nm, as a result, its surface area increases. The main factors affecting the biodiesel yield were investigated, accordingly, an optimal biodiesel yield of 94% was obtained at 1:12 oil to methanol molar ratio, 2.5 wt% catalyst loading, 60 °C, and 120-min reaction time. A biodiesel yield of 88% was obtained using 6:6 equimolar ratio of methanol to ethanol, the yield even increased to 91% by increasing the catalyst loading to 3.5 wt%. Moreover, by slightly increasing the share of methanol in the mixture, at 8:4 ratio, the maximum biodiesel yield could reach 92%. Therefore, we suggest the utilization of methanol-ethanol mixture as a reactant and eggshell-derived CaO as a catalyst for enhanced conversion of WCO into biodiesel. It is a very promising approach for the development of low-cost and environmentally friendly technology. Properties of the biodiesel were also found in good agreement with the American (ASTM D6571) fuel standards.

Genome Analysis of a Verrucomicrobial Endosymbiont With a Tiny Genome Discovered in an Antarctic Lake.

Abstract: Organic Lake in Antarctica is a marine-derived, cold (−13∘C), stratified (oxic-anoxic), hypersaline (>200 gl–1) system with unusual chemistry (very high levels of dimethylsulfide) that supports the growth of phylogenetically and metabolically diverse microorganisms. Symbionts are not well characterized in Antarctica. However, unicellular eukaryotes are often present in Antarctic lakes and theoretically could harbor endosymbionts. Here, we describe Candidatus Organicella extenuata, a member of the Verrucomicrobia with a highly reduced genome, recovered as a metagenome-assembled genome with genetic code 4 (UGA-to-Trp recoding) from Organic Lake. It is closely related to Candidatus Pinguicocccus supinus (163,218 bp, 205 genes), a newly described cytoplasmic endosymbiont of the freshwater ciliate Euplotes vanleeuwenhoeki ( Serra et al., 2020 ). At 158,228 bp (encoding 194 genes), the genome of Ca. Organicella extenuata is among the smallest known bacterial genomes and similar to the genome of Ca. Pinguicoccus supinus (163,218 bp, 205 genes). Ca. Organicella extenuata retains a capacity for replication, transcription, translation, and protein-folding while lacking any capacity for the biosynthesis of amino acids or vitamins. Notably, the endosymbiont retains a capacity for fatty acid synthesis (type II) and iron–sulfur (Fe-S) cluster assembly. Metagenomic analysis of 150 new metagenomes from Organic Lake and more than 70 other Antarctic aquatic locations revealed a strong correlation in abundance between Ca. Organicella extenuata and a novel ciliate of the genus Euplotes. Like Ca. Pinguicoccus supinus, we infer that Ca. Organicella extenuata is an endosymbiont of Euplotes and hypothesize that both Ca. Organicella extenuata and Ca. Pinguicocccus supinus provide fatty acids and Fe-S clusters to their Euplotes host as the foundation of a mutualistic symbiosis. The discovery of Ca. Organicella extenuata as possessing genetic code 4 illustrates that in addition to identifying endosymbionts by sequencing known symbiotic communities and searching metagenome data using reference endosymbiont genomes, the potential exists to identify novel endosymbionts by searching for unusual coding parameters.

Lignocellulosic biomass pre-treatment using low-cost ionic liquid for bioethanol production: An economically viable method for wheat straw fractionation

Abstract: Low-cost Ionic Liquid (IL) is a promising method for the lignocellulosic biomass pretreatment to produce bioethanol. This study investigates utilizing low-cost IL, [TEA][HSO4], for wheat straw pretreatment. The pretreatment was investigated in conditions characterized by a temperature of 130 °C, a high solid-to-solvent load ratio of 1:5 g/g, and 20 wt % water to separate lignin and carbohydrates from the source, which would subsequently undergo enzymatic hydrolysis. The highest delignification rate of 80% and the hemicellulose removal rate of 64.45% were observed in the case of a 3-h pretreated sample with [TEA][HSO4]. Two biomass samples pretreated for 0.5 h and 3-h showed high glucose saccharification yield levels of 50.36 and 87.19%, respectively, and 78.23% xylose yield was achieved in 3-h pretreated sample in enzymatic hydrolysis with commercial enzyme CelluMax in 72 h. Ethanol production and yield of 3-h pretreated biomass reached 43.1 g/L and 84.34% of the maximum theoretical yield after 48 h of fermentation time. However, the yield of the untreated biomass was only 10.76%. Obtained results clearly demonstrated that pretreatment with low-cost IL prior to enzymatic hydrolysis led to higher ethanol yield due to successful delignification. The process developed in this study exhibited economic feasibility of this technique in industrial bioprocess.

Disturbance-Observer-Based Complementary Sliding-Mode Speed Control for PMSM Drives: A Super-Twisting Sliding-Mode Observer-Based Approach

Abstract: This article proposes a novel disturbance-observer-based complementary sliding-mode (DO-CSM) speed controller for the field-oriented controlled permanent-magnet synchronous motor (FOC-PMSM) drive system. At first, the rotor speed dynamics of the PMSM drive system considering the lumped disturbance, which consists of external disturbances, parametric uncertainties, and unmodeled dynamics, is presented. Then, the classic CSM speed controller and a typical artificial neural network (ANN)-based CSM speed controller, i.e., the Elman NN (ENN)-based intelligent CSM (ENN-ICSM) speed controller for the FOC-PMSM drive system, are reviewed. Afterward, the design of the proposed DO-CSM speed controller, which combines the signum-function-based CSM controller with the super-twisting sliding-mode observer (STSMO), is presented. In such a speed controller, the rotor speed tracking control is accomplished by the adopted CSM controller, whereas the STSMO is employed to estimate and compensate for the lumped disturbance in the rotor speed dynamics. Finally, experimental comparisons among the proposed DO-CSM speed controller, the classic CSM speed controller, and three selected ENN-ICSM speed controllers are carried out. Experimental results verify the effectiveness and superiority of the proposed DO-CSM speed controller.

The challenge of forecasting the role of biofuel in EU transport decarbonisation at 2050: A meta-analysis review of published scenarios

Abstract: The European New Green Deal and the REDII set ambitious targets, aiming to achieve a climate-neutral Europe by 2050. The transport sector is the most critical area to decarbonize, given the rigidity of both infrastructure and end-use technologies, as well as the challenge of reaching cost-effective production of sustainable advanced renewable fuels. Several researchers, stakeholders and groups of interest, such as international and governmental organisations, NGOs, business analysists, scientists and other actors elaborated scenarios on biofuels market penetration by 2050. These studies are largely used by policy makers, even if not necessarily were subject to a rigid peer review and verification process. This work presents an extensive literature review of the main published investigations, to assess and quantify the authors' different visions. These forecasts intend to evaluate the possible future development of the sector based on current and foreseeable policies, as well as industry and investors’ business plans; at the same time, these estimates should also provide policy makers with a sound base for policy development towards achieving climate goals. Through preliminary screening, based on a methodology of a set of ex-ante conditions, this work identified the most relevant publications and structured the analysis of the collected data. A total of 18 publications were selected from the literature review, resulting in 56 scenarios to be examined. This work allowed to achieve a comprehensive summary and quantification of the selected scenarios, all of which focus on biofuel contribution to transport decarbonisation in the period 2030–2050. Given the occurrence of several factors, as the ongoing and future technological development, the adoption of more efficient mobility models, the hybridization and electrification of transports, the Total Fuel Consumption for the transport sector is expected to reduce in Europe: averaged projections from the analyzed scenarios account for 312.8 Mtoe in 2030 and 274.2 Mtoe in 2050. Biofuels are expected to significantly contribute to achieve the EU targets, with a progressive shift towards advanced feedstock: on average, their total contribution is expected to account for 24.5 Mtoe in 2030, and for 48.3 Mtoe in 2050, while advanced biofuels are projected for an average contribution of 8.7 Mtoe in 2030 and 36.5 Mtoe in 2050. This work analysed pre-pandemic published scenarios: the effects that the COVID-19 pandemic is having on the global as well as EU economies are uncertain, but there is a serious risk of hampering and postponing investment decisions in the whole energy area, making the achievement of RED and EU Green Deal targets even more challenging in this historical moment.

Omics-Driven Biotechnology for Industrial Applications

Abstract: Biomanufacturing is a key component of biotechnology that uses biological systems to produce bioproducts of commercial relevance, which are of great interest to the energy, material, pharmaceutical, food, and agriculture industries. Biotechnology-based approaches, such as synthetic biology and metabolic engineering are heavily reliant on "omics" driven systems biology to characterize and understand metabolic networks. Knowledge gained from systems biology experiments aid the development of synthetic biology tools and the advancement of metabolic engineering studies toward establishing robust industrial biomanufacturing platforms. In this review, we discuss recent advances in "omics" technologies, compare the pros and cons of the different "omics" technologies, and discuss the necessary requirements for carrying out multi-omics experiments. We highlight the influence of "omics" technologies on the production of biofuels and bioproducts by metabolic engineering. Finally, we discuss the application of "omics" technologies to agricultural and food biotechnology, and review the impact of "omics" on current COVID-19 research.

Project Coolbit: Can your watch predict heat stress and thermal comfort sensation?

Abstract: Global climate is changing as a result of anthropogenic warming, leading to higher daily excursions of temperature in cities. Such elevated temperatures have great implications on human thermal comfort and heat stress, which should be closely monitored. Current methods for heat exposure assessments (surveys, microclimate measurements, and laboratory experiments), however, present several limitations: measurements are scattered in time and space and data gathered on outdoor thermal stress and comfort often does not include physiological and behavioral parameters. To address these shortcomings, Project Coolbit aims to introduce a human-centric approach to thermal comfort assessments. In this study, we propose and evaluate the use of wrist-mounted wearable devices to monitor environmental and physiological responses that span a wide range of spatial and temporal distributions. We introduce an integrated wearable weather station that records a) microclimate parameters (such as air temperature and humidity), b) physiological parameters (heart rate, skin temperature and humidity), and c) subjective feedback. The feasibility of this methodology to assess thermal comfort and heat stress is then evaluated using two sets of experiments: controlled-environment physiological data collection, and outdoor environmental data collection. We find that using the data obtained through the wrist-mounted wearables, core temperature can be predicted non-invasively with 95 percent of target attainment (PTA) within 0.27C. Additionally, a direct connection between the air temperature at the wrist (Ta,w) and the perceived activity level (PAV) of individuals was drawn. We observe that with increased Ta,w, the desire for physical activity is significantly reduced, reaching "Transition only" PAV level at 36C. These assessments reveal that the wearable methodology provides a comprehensive and accurate representation of human heat exposure, which can be extended in real-time to cover a large spatial distribution in a given city and quantify the impact of heat exposure on human life.

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography.

Abstract: Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10−4, with an over threefold improvement on the previous measurement. CPT violation could manifest itself in annihilating positronium events, but searching for this effect would require to know the spin of the annihilating system. Here, the authors do this using a positron-emission tomography scanner, finding no violation with a statistical precision of 10−4.