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The controllable response of materials to small-molecule absorbates helps control the information duration on rewritable paper., Controlling the duration that information lasts on paper so that it disappears as desired is crucial for information security. However, this area is rarely studied. Here, we report [TEMA]2SbCl5 (1, TEMA+ = methyltriethylammonium), [TEA]2SbCl5 (2, TEA+ = tetraethylammonium), [TEBA]2SbCl5 (3, TEBA+ = benzyltriethylammonium), and [Ph4P]2SbCl5 (4, Ph4P+ = tetraphenylphosphonium) with structure-dependent reversible photoluminescent switching induced by the absorption and thermal release of small guest molecules including H2O, methanol, and ethylene glycol. Comparing the structural disorder levels, bond lengths, and luminescent Stokes shifts of the compounds aided in understanding their selective absorption behavior. Our results indicated that the information duration on the rewritable paper coated with the title compounds is easily tuned by changing the cation of the compounds, the type of guest molecules, and laser heating power. Our study opens previously unidentified avenues for information security and extends the potential applications of rewritable paper.

Lithium (Li) metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries. However, the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites, resulting in poor cycling stability and severe safety issues. Herein, vertical graphene (VG) film grown on graphite paper (GP) as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites. The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients, thus regulating the Li deposition to suppress the dendrite growth. The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal, which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential. As a result, the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5 mA cm -2 in half cells and a small hysteresis of 50 mV at 1 mA cm -2 in symmetric cells. This work provides an efficient strategy for the rational design of highly stable Li metal anodes.

Stable isotope labeling of agricultural polyesters enables demonstration of their microbial utilization in soils., Plastic materials are widely used in agricultural applications to achieve food security for the growing world population. The use of biodegradable instead of nonbiodegradable polymers in single-use agricultural applications, including plastic mulching, promises to reduce plastic accumulation in the environment. We present a novel approach that allows tracking of carbon from biodegradable polymers into CO2 and microbial biomass. The approach is based on 13C-labeled polymers and on isotope-specific analytical methods, including nanoscale secondary ion mass spectrometry (NanoSIMS). Our results unequivocally demonstrate the biodegradability of poly(butylene adipate-co-terephthalate) (PBAT), an important polyester used in agriculture, in soil. Carbon from each monomer unit of PBAT was used by soil microorganisms, including filamentous fungi, to gain energy and to form biomass. This work advances both our conceptual understanding of polymer biodegradation and the methodological capabilities to assess this process in natural and engineered environments.

Organic fertilizer from recycled biowaste was identified as a vehicle for entry of microplastic particles into the environment., The contamination of the environment with microplastic, defined as particles smaller than 5 mm, has emerged as a global challenge because it may pose risks to biota and public health. Current research focuses predominantly on aquatic systems, whereas comparatively little is known regarding the sources, pathways, and possible accumulation of plastic particles in terrestrial ecosystems. We investigated the potential of organic fertilizers from biowaste fermentation and composting as an entry path for microplastic particles into the environment. Particles were classified by size and identified by attenuated total reflection-Fourier transform infrared spectroscopy. All fertilizer samples from plants converting biowaste contained plastic particles, but amounts differed significantly with substrate pretreatment, plant, and waste (for example, household versus commerce) type. In contrast, digestates from agricultural energy crop digesters tested for comparison contained only isolated particles, if any. Among the most abundant synthetic polymers observed were those used for common consumer products. Our results indicate that depending on pretreatment, organic fertilizers from biowaste fermentation and composting, as applied in agriculture and gardening worldwide, are a neglected source of microplastic in the environment.

A new graphene structure allowing unprecedented stretchability in graphene electrodes was designed., Two-dimensional materials, such as graphene, are attractive for both conventional semiconductor applications and nascent applications in flexible electronics. However, the high tensile strength of graphene results in fracturing at low strain, making it challenging to take advantage of its extraordinary electronic properties in stretchable electronics. To enable excellent strain-dependent performance of transparent graphene conductors, we created graphene nanoscrolls in between stacked graphene layers, referred to as multilayer graphene/graphene scrolls (MGGs). Under strain, some scrolls bridged the fragmented domains of graphene to maintain a percolating network that enabled excellent conductivity at high strains. Trilayer MGGs supported on elastomers retained 65% of their original conductance at 100% strain, which is perpendicular to the direction of current flow, whereas trilayer films of graphene without nanoscrolls retained only 25% of their starting conductance. A stretchable all-carbon transistor fabricated using MGGs as electrodes exhibited a transmittance of >90% and retained 60% of its original current output at 120% strain (parallel to the direction of charge transport). These highly stretchable and transparent all-carbon transistors could enable sophisticated stretchable optoelectronics.

Replacing petroleum by biomass can be economically feasible by generating revenue from the three primary biomass constituents., The production of renewable chemicals and biofuels must be cost- and performance- competitive with petroleum-derived equivalents to be widely accepted by markets and society. We propose a biomass conversion strategy that maximizes the conversion of lignocellulosic biomass (up to 80% of the biomass to useful products) into high-value products that can be commercialized, providing the opportunity for successful translation to an economically viable commercial process. Our fractionation method preserves the value of all three primary components: (i) cellulose, which is converted into dissolving pulp for fibers and chemicals production; (ii) hemicellulose, which is converted into furfural (a building block chemical); and (iii) lignin, which is converted into carbon products (carbon foam, fibers, or battery anodes), together producing revenues of more than $500 per dry metric ton of biomass. Once de-risked, our technology can be extended to produce other renewable chemicals and biofuels.

11 pages, 5 figures, 1 table, supplementary materials https://www.science.org/doi/10.1126/sciadv.add9031.-- Data and materials availability: All data needed to evaluate the conclusions of the paper are present in the paper and/or the Supplementary Materials. The measurements and fluxes from the Southern Ocean can be accessed through the following DOI: https://doi.org/10.5281/zenodo.6523780 (last access 23 November 2022). The measurements and fluxes from the Arctic can be accessed through the following DOI: https://doi.org/10.21963/13271 (last access 23 November 2022). The CAM-Chem (public version) code is available at www2.acom.ucar.edu/gcm/cam-chem (last access 23 November 2022). Some of the data presented here were collected by the Canadian research icebreaker CCGS Amundsen and made available by the Amundsen Science program, which is supported by the Canada Foundation for Innovation Major Science Initiatives Fund. The views expressed in this publication do not necessarily represent the views of Amundsen Science or that of its partners, Reactive trace gas emissions from the polar oceans are poorly characterized, even though their effects on atmospheric chemistry and aerosol formation are crucial for assessing current and preindustrial aerosol forcing on climate. Here, we present seawater and atmospheric measurements of benzene and toluene, two gases typically associated with pollution, in the remote Southern Ocean and the Arctic marginal ice zone. Their distribution suggests a marine biogenic source. Calculated emission fluxes were 0.023 ± 0.030 (benzene) and 0.039 ± 0.036 (toluene) and 0.023 ± 0.028 (benzene) and 0.034 ± 0.041 (toluene) μmol m−2 day−1 for the Southern Ocean and the Arctic, respectively. Including these average emissions in a chemistry-climate model increased secondary organic aerosol mass concentrations only by 0.1% over the Arctic but by 7.7% over the Southern Ocean, with transient episodes of up to 77.3%. Climate models should consider the hitherto overlooked emissions of benzene and toluene from the polar oceans, This work was supported by the European Union Horizon 2020 grant SUMMIT ERC-2018-AdG 834162 (to R.S.), the Spanish National Research Council grant PEGASO CTM2012-37615 (to R.S.), the “Severo Ochoa Centre of Excellence” accreditation grant CEX2019-000928-S (to ICM), the European Union Horizon 2020 grant CLIMAHAL ERC-2016-COG 726349 (to A.S.-L.), the UK Research and Innovation grant ORCHESTRA NE/N018095/1, and the NSF grant CESM

Philip Yeagle Ensuring the scientific integrity behind every paper published in scientific journals is an essential standard in the world of scientific publishing. Scientists depend on published work that accurately represents the experiments performed and the results obtained so that future work can be effectively planned and performed. Readers must know that high standards have been met for the integrity of the data and the experimental protocols utilized. The public must have confidence in the integrity of the results that are presented in the published papers because those results may influence and have import in their lives. The need to focus on scientific integrity in publishing is perhaps even more critical in our current climate. Some high-profile cases of misconduct have raised questions as to how widespread scientific misconduct is. The explosion in the number of scientific publishing outlets, some less subject to rigorous peer review than others, can shake confidence in the quality of published work. The …

Globally, agriculture depends on industrial nitrogen fertilizer to improve crop growth. Fertilizer production consumes fossil fuels and contributes to environmental nitrogen pollution. A potential solution would be to harness nitrogenases—enzymes capable of converting atmospheric nitrogen N 2 to NH 3 in ambient conditions. It is therefore a major goal of synthetic biology to engineer functional nitrogenases into crop plants, or bacteria that form symbiotic relationships with crops, to support growth and reduce dependence on industrially produced fertilizer. This review paper highlights recent work toward understanding the functional requirements for nitrogenase expression and manipulating nitrogenase gene expression in heterologous hosts to improve activity and oxygen tolerance and potentially to engineer synthetic symbiotic relationships with plants.

Walter et al. issue a number of critical comments on our report about the discovery of davemaoite to the end that they believe to show that our results do not provide compelling evidence for the presence of davemaoite in the type specimen and that the hosting diamond had formed in the lithosphere. Their claim is based on a misinterpretation of the diffraction data contained in the paper, an insufficient analysis of the compositional data that disregards the three-dimensional distribution of inclusions, and the arbitrary assumption that Earth’s mantle shows no lateral variations in temperature, inconsistent with state-of-the-art assessments of mantle temperature variations and with their own published results.

Contemporary proliferation of renewable power generation is causing an overhaul in the topology, composition, and dynamics of electrical grids. These low-output, intermittent generators are widely distributed throughout the grid, including at the household level. It is critical for the function of modern power infrastructure to understand how this increasingly distributed layout affects network stability and resilience. This paper uses dynamical models, household power consumption, and photovoltaic generation data to show how these characteristics vary with the level of distribution. It is shown that resilience exhibits daily oscillations as the grid’s effective structure and the power demand fluctuate. This can lead to a substantial decrease in grid resilience, explained by periods of highly clustered generator output. Moreover, the addition of batteries, while enabling consumer self-sufficiency, fails to ameliorate these problems. The methodology identifies a grid’s susceptibility to disruption resulting from its network structure and modes of operation.

Description, Instant interfacial self-assembly of nanoparticle monolayer advances the thin film technology in a “lift-on” and conformal manner., Thin film fabrication is of great importance in modern engineering. Here, we propose a universal and conformal thin film technique enabled by the wetting empowered interfacial self-assembly. By tailoring the contact angle of nanoparticle (NP), a NP monolayer can be assembled instantly (within 5 seconds) with an excellent harvesting efficiency (up to 97.5 weight %). This self-assembly strategy presents a universal applicability on various materials, e.g., nonmetal, metal, and core-shell structures, and can achieve a monolayer with same in-plane area as a 95 cm2 wafer in a single process, indicating great potential for scale-up manufacturing. Through a template transfer, we coat the surface of different substrates (plastic, paper, etc.) with the assembled film in a conformal and nondestructive “lift-on” manner and subsequently demonstrate fluorescent micropatterns. This self-assembly strategy has great implications in advancing thin film technology in a user-friendly and cost-effective fashion for applications in anti-counterfeiting, actuators, and wearable/flexible electronics.

Description, This study finds that no-excuse absentee voting policies did not meaningfully increase turnout in the 2020 U.S. election., The 2020 U.S. election saw a record turnout, saw a huge increase in absentee voting, and brought unified national Democratic control—yet these facts alone do not imply that vote-by-mail increased turnout or benefited Democrats. Using new microdata on millions of individual voters and aggregated turnout data across all 50 states, this paper offers a causal analysis of the impact of absentee vote-by-mail during the COVID-19 (coronavirus disease 2019) pandemic. Focusing on natural experiments in Texas and Indiana, we find that 65-year-olds voted at nearly the same rate as 64-year-olds, despite the fact that only 65-year-olds could vote absentee without an excuse. Being just old enough to vote no-excuse absentee did not substantially increase Democratic turnout relative to Republican turnout. Voter interest appeared to be more important in driving turnout across vote modes, neutralizing the electoral impact of Democrats voting by mail at higher rates during the historic pandemic.

Authorship is the primary form of symbolic capital in science. Despite this, authorship is rife with injustice and malpractice, with women expressing concerns regarding the fair attribution of credit. Based on an international survey, we examine gendered practices in authorship communication, disagreement, and fairness. Our results demonstrate that women were more likely to experience authorship disagreements and experience them more often. Their contributions to research papers were more often devalued by both men and women. Women were more likely to discuss authorship with coauthors at the beginning of the project, whereas men were more likely to determine authorship unilaterally at the end. Women perceived that they received less credit than deserved, while men reported the opposite. This devaluation of women’s work in science creates cumulative disadvantages in scientific careers. Open discussion regarding power dynamics related to gender is necessary to develop more equitable distribution of credit for scientific labor.

Funding Information: This work was supported in part by the National Natural Science Foundation of China (Grant Nos. 51879022, 91648120, 61633002, 51575005, 61503008, 61973172, and 62003175), the Beijing Natural Science Foundation (No. 4192026), the Fundamental Research Funds for the Central Universities (Grants Nos. 3132019037 and 3132019197), and the Academy of Finland (Grant No. 315660). Publisher Copyright: © 2021 Peng Xu et al. Exclusive Licensee Science and Technology Review Publishing House. Distributed under a Creative Commons Attribution License (CC BY 4.0). Since designing efficient tactile sensors for autonomous robots is still a challenge, this paper proposes a perceptual system based on a bioinspired triboelectric whisker sensor (TWS) that is aimed at reactive obstacle avoidance and local mapping in unknown environments. The proposed TWS is based on a triboelectric nanogenerator (TENG) and mimics the structure of rat whisker follicles. It operates to generate an output voltage via triboelectrification and electrostatic induction between the PTFE pellet and copper films (0.3mm thickness), where a forced whisker shaft displaces a PTFE pellet (10mm diameter). With the help of a biologically inspired structural design, the artificial whisker sensor can sense the contact position and approximate the external stimulation area, particularly in a dark environment. To highlight this sensor's applicability and scalability, we demonstrate different functions, such as controlling LED lights, reactive obstacle avoidance, and local mapping of autonomous surface vehicles. The results show that the proposed TWS can be used as a tactile sensor for reactive obstacle avoidance and local mapping in robotics.

Differential cross-sectional cusps, occurring at the vicinity of newly open channels, are used for enhanced avionic sensing., Typical sensors detect small perturbations by measuring their effects on a physical observable, using a linear response principle (LRP). It turns out that once LRP is abandoned, new opportunities emerge. A prominent example is resonant systems operating near Nth-order exceptional point degeneracies (EPDs) where a small perturbation ε ≪ 1 activates an inherent sublinear response ∼εN≫ε in resonant splitting. Here, we propose an alternative sublinear optomechanical sensing scheme that is rooted in Wigner’s cusp anomalies (WCAs), first discussed in the framework of nuclear reactions: a frequency-dependent square-root singularity of the differential scattering cross section around the energy threshold of a newly opened channel, which we use to amplify small perturbations. WCA hypersensitivity can be applied in a variety of sensing applications, besides optomechanical accelerometry discussed in this paper. Our WCA platforms are compact, do not require a judicious arrangement of active elements (unlike EPD platforms), and, if chosen, can be cavity free.

A detailed analysis of contact electrification between metals reveals a mechanism leading to unexpectedly high voltages., Although the electrical charging of objects brought into contact has been observed for at least 2000 years, the details of the underlying mechanism are still not yet fully understood. The present paper deals with the very basic process of contact electrification between two metals. We have developed an experimental method to follow the charge of a small sphere bouncing on a grounded planar electrode on a time scale down to 1 μs. It reveals that the sphere is discharged in the moment of contact, which lasts about 6 to 8 μs. However, at the very moment of disruption of the electrical contact, it regains charge far beyond the expectation according to the contact potential difference. The excess charge rises with increasing contact area.

Metamaterial absorber/emitter is an important aspect of infrared radiation manipulation. In this paper, we proposed four simple switchable infrared metamaterial absorbers/emitters with Ag/VO 2 disks on the Ag plane employing triangle, square, hexagon, and circle unit cells. The spectral absorption peaks whose intensities are above 0.99 occur at ~4 μ m after structure optimization when VO 2 is in insulating state and disappear when VO 2 becomes metallic state. The simulated electromagnetic field reveals that the spectral absorption peaks are attributed to the excitation of magnetic polariton within the insulating VO 2 spacer layer, whose values exceed 1.59 orders of magnitude higher than the incident magnetic field. Longer resonant wavelength would be excited in square arrays because its configuration is a better carrier of charges at the same spans. For absorption stability, the absorbers/emitters with square and circular structures do not have any change with the polarization angles changing from 0° to 90°, due to the high rotational symmetric structure. And four absorbers/emitters reveal similar shifts and attenuations under different incident angles. We believed that the switchable absorber/emitter demonstrates promising applications in the sensing technology and adaptive infrared system.

A highly sensitive odorant sensor was developed by using insect olfactory receptors reconstituted into a lipid bilayer membrane., This paper reports a volatile organic compound (VOC) sensor based on olfactory receptors that were reconstituted into a lipid bilayer and used in a specifically designed gas flow system for rapid parts per billion (ppb)–level detection. This VOC sensor achieves both rapid detection and high detection probability because of its gas flow system and array design. Specifically, the gas flow system includes microchannels and hydrophobic microslits, which facilitate both the introduction of gas into the droplet and droplet mixing. We installed this system into a parallel lipid bilayer device and subsequently demonstrated parts per billion–level (0.5 ppb) detection of 1-octen-3-ol in human breath. Therefore, this system extends the various applications of biological odorant sensing, including breath diagnosis systems and environmental monitoring.

With the continuous development of artificial intelligence, the demand for sensors with simple preparation and strong concealment continues to increase. However, most of the high-sensitivity sensors have complex manufacturing methods, high costs, and single functions. In this paper, a sensitive motion sensor based on the triboelectric interaction between a living plant and the human body was designed to detect the real-time movements of human beings and provide danger warning. A certain relationship exists between the triboelectric signal and the distance between the plant and the human body, with effective signals being detected in the range of 1.8 m. In addition, the triboelectric signal generated by each person is unique like a fingerprint, which can be used for biometrics. On the basis of the triboelectric signal, a wireless character entry warning system is designed. This sensor can not only send out a wireless warning signal at a specific distance but also allow one to receive the warning information synchronously on a mobile phone in real time. The wireless movement sensor receives signals through a living plant, and it has the characteristics of convenient use, strong concealment, and shielding difficulty. This sensor has the potential to be widely used in person recognition, danger warning, and motion monitoring.

A tissue-engineered model of the trabecular bone microenvironment elucidates spatiotemporal aspects of bone remodeling processes., Trabecular bone maintains physiological homeostasis and consistent structure and mass through repeated cycles of bone remodeling by means of tightly localized regulation. The molecular and cellular processes that regulate localized bone remodeling are poorly understood because of a lack of relevant experimental models. A tissue-engineered model is described here that reproduces bone tissue complexity and bone remodeling processes with high fidelity and control. An osteoid-inspired biomaterial—demineralized bone paper—directs osteoblasts to deposit structural mineralized bone tissue and subsequently acquire the resting-state bone lining cell phenotype. These cells activate and shift their secretory profile to induce osteoclastogenesis in response to chemical stimulation. Quantitative spatial mapping of cellular activities in resting and activated bone surface coculture showed that the resting-state bone lining cell network actively directs localized bone remodeling by means of paracrine signaling and cell-to-cell contact. This model may facilitate further investigation of trabecular bone niche biology.

Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale., This paper is the result of the Latin American and Caribbean Seasonally Dry Tropical Forest Floristic Network (DRYFLOR), which has been supported at the Royal Botanic Garden Edinburgh by a Leverhulme Trust International Network Grant (IN-074). This work was also supported by the U.K. Natural Environment Research Council grant NE/ I028122/1; Colciencias Ph.D. scholarship 529; Synthesys Programme GBTAF-2824; the NSF (NSF 1118340 and 1118369); the Instituto Humboldt (IAvH)–Red colombiana de investigación y monitoreo en bosque seco; the Inter-American Institute for Global Change Research (IAI; Tropi-Dry, CRN2-021, funded by NSF GEO 0452325); Universidad Nacional de Rosario (UNR); and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The data reported in this paper are available at www.dryflor.info. R.T.P. conceived the study. M.P., A.O.-F., K.B.-R., R.T.P., and J.W. designed the DRYFLOR database system. K.B.-R. and K.G.D. carried out most analyses. K.B.-R. R.T.P., and K.G.D. wrote the manuscript with substantial input from A.D.-S., R.L.-P., A.O.-F., D.P., C.Q., and R.R.

Soft robotic sensor arrays for left-atrial mapping demonstrate highly conformal contact to complex patient anatomies., Devices that perform cardiac mapping and ablation to treat atrial fibrillation provide an effective means of treatment. Current devices, however, have limitations that either require tedious point-by-point mapping of a cardiac chamber or have limited ability to conform to the complex anatomy of a patient’s cardiac chamber. In this work, a detailed, scalable, and manufacturable technique is reported for fabrication of a multielectrode, soft robotic sensor array. These devices exhibit high conformability (~85 to 90%) and are equipped with an array of stretchable electronic sensors for voltage mapping. The form factor of the device is intended to match that of the entire left atrium and has a hydraulically actuated soft robotic structure whose profile facilitates deployment from a 13.5-Fr catheter. We anticipate that the methods described in this paper will serve a new generation of conformable medical devices that leverage the unique characteristics of stretchable electronics and soft robotics.

This paper shows that mandatory vote-by-mail increases voter turnout but does not advantage one political party over the other., Recently, mandatory vote-by-mail has received a great deal of attention as a means of administering elections in the United States. However, policy-makers disagree on the merits of this approach. Many of these debates hinge on whether mandatory vote-by-mail advantages one political party over the other. Using a unique pairing of historical county-level data that covers the past three decades and more than 40 million voting records from the two states that have conducted a staggered rollout of mandatory vote-by-mail (Washington and Utah), we use several methods for causal inference to show that mandatory vote-by-mail slightly increases voter turnout but has no effect on election outcomes at various levels of government. Our results find meaning given contemporary debates about the merits of mandatory vote-by-mail. Mandatory vote-by-mail ensures that citizens are given a safe means of casting their ballot while simultaneously not advantaging one political party over the other.

Lord Robert May, groundbreaking ecologist, died in Oxford, England, on 28 April. He was 84. In addition to ecology, Bob made substantial contributions to a wide variety of fields, including epidemiology and economics. A towering figure in British and international scientific life, he served as both chief scientific adviser for the United Kingdom and president of the Royal Society. Slight of build with a formidable intellect, Bob changed the way we investigate the dynamics of the living world. Born in Sydney, Australia, on 8 January 1936, Bob attended Sydney Boys High School, where he excelled both academically and athletically. In 1956, he received his bachelor's degree in physics from the University of Sydney. He stayed on to earn his Ph.D. in superconductivity in 1959 and then conducted further research in theoretical physics as a faculty member. In the late 1960s, Bob learned of a movement in ecology, associated with George Evelyn Hutchinson and Robert MacArthur, that aimed to put the subject on a more rigorous and quantitative footing. At the time, some of the simplest models in ecology, such as those describing predator-prey dynamics, were often unstable, leading to predictions of the extinction of some or all of the modeled species. It was tacitly assumed that when these simple systems were embedded in more complex ecosystems, stability would inevitably emerge, but there was no way to assess this assumption. In his 1973 monograph, Stability and Complexity in Model Ecosystems , Bob showed that stability was not inevitable. He introduced new mathematical techniques to ecology and initiated a research program that to this day continues to investigate what aspects of natural communities allow their persistence. So impressive were Bob's immediate contributions to ecology that, upon MacArthur's tragic and untimely death in 1972, Bob was offered his position in ecology at Princeton University. Models of a single species competing for access to food often predict a transition from stable to cyclic population dynamics as birth rate increases. Bob studied these models and found that as birth rate continues to increase, more complicated patterns of cycles occur, culminating in what is now called chaotic dynamics. The ecological difference equation models that Bob studied, together with the differential equations that meteorologist Edward Norton Lorenz had previously analyzed, spurred the mathematical development of chaos theory and placed limits on our ability to make predictions about systems governed by non linear dynamics. At his Princeton going-away party in 1988, the celebrants serenaded Bob with a song called “Kid Chaos,” composed by his colleague Henry Horn. Bob was quietly proud of this song and enjoyed Henry's reprise at Bob's 70th birthday celebration at the University of Oxford. Through most of the 1970s and 1980s, Bob spent his summers at Imperial College London's Silwood Park campus near Windsor, England. There, he initiated a series of long-term collaborations with far-reaching consequences. For example, he and epidemiologist Roy Anderson transformed the field of epidemiological dynamics, and with biologist Michael Hassell he reshaped insect predator-prey dynamics. Summers at Silwood Park were characterized by intense work with a large and changing cast of collaborators, punctuated by equally intense competitive sport in which winning was more important than strict adherence to the rules. The order of authorship for several papers was decided by the outcome of croquet games played on a lawn sculpted by the local rabbits, whose effect on the game only Bob really understood. After taking a position at the University of Oxford in 1988, Bob quickly became influential in U.K. scientific life and in 1995 was appointed government chief scientific adviser (GCSA). Among Bob's many achievements as GCSA was codifying the role of science advisers, a move that remains critically important today during the coronavirus disease 2019 (COVID-19) pandemic. In this role and later as president of the Royal Society, Bob worked actively, and often behind the scenes, to promote greater inclusivity and encourage early career scientists. Throughout his life, Bob remained a proud Australian and would often play up to the image of the plain-spoken Aussie. He claimed that his favorite film was the Australian classic Mad Max . A British civil servant once tried to summarize Bob's dismissal of a daft idea by saying he “expressed himself in a somewhat…‘Australian way’!” Bob was a master of the witty put-down. With a smile, he once told a very senior botanist, “In my experience, the intellectual capability of any biologist is directly proportional to the speed of locomotion of the organisms with which they work.” In scientific debate, he could be cutting, although always with reason. He was immensely kind and loyal to friends and colleagues and enormously encouraging to people at the start of their careers, something we both experienced personally as young academics at Imperial College London and the University of Oxford. Bob loved being in the wild. For nearly 50 years, he organized an annual hiking trip with colleagues, and he spent most of his holidays walking with his wife, Judith. At the end of one hiking trip, just before the final descent, Bob asked the rest of us to go on ahead so he could have a final moment alone to soak in the mountain ambience. It was this deep attachment to the natural world that we believe motivated his great concern for the future of the environment. Bob May was knighted, awarded the Order of Merit, and made a peer in the U.K. House of Lords as well as a Companion of the Order of Australia. He received the Crafoord Prize, the Balzan Prize, and many other prizes and honors for his scientific research. He is survived by his wife, Judith, and their daughter, Naomi. Bob leaves the field of ecology stronger and more rigorous than it was when he joined it in the early 1970s, a transformation in great part due to the combined force of his leadership and his intellect.

In this paper, we review and demonstrate how population phenomena can inflate genotype-phenotype associations., Heritability, genetic correlation, and genetic associations estimated from samples of unrelated individuals are often perceived as confirmation that genotype causes the phenotype(s). However, these estimates can arise from indirect mechanisms due to population phenomena including population stratification, dynastic effects, and assortative mating. We introduce these, describe how they can bias or inflate genotype-phenotype associations, and demonstrate methods that can be used to assess their presence. Using data on educational achievement and parental socioeconomic position as an exemplar, we demonstrate that both heritability and genetic correlation may be biased estimates of the causal contribution of genotype. These results highlight the limitations of genotype-phenotype estimates obtained from samples of unrelated individuals. Use of these methods in combination with family-based designs may offer researchers greater opportunities to explore the mechanisms driving genotype-phenotype associations and identify factors underlying bias in estimates.

Woody bioenergy demand and carbon sequestration payments increase forest area and produce net carbon benefits., There is a continuing debate over the role that woody bioenergy plays in climate mitigation. This paper clarifies this controversy and illustrates the impacts of woody biomass demand on forest harvests, prices, timber management investments and intensity, forest area, and the resulting carbon balance under different climate mitigation policies. Increased bioenergy demand increases forest carbon stocks thanks to afforestation activities and more intensive management relative to a no-bioenergy case. Some natural forests, however, are converted to more intensive management, with potential biodiversity losses. Incentivizing both wood-based bioenergy and forest sequestration could increase carbon sequestration and conserve natural forests simultaneously. We conclude that the expanded use of wood for bioenergy will result in net carbon benefits, but an efficient policy also needs to regulate forest carbon sequestration.

The chaperone Hsp90 remodels the structural ensemble of Tau, resulting in the formation of potentially neurotoxic oligomers., Aggregation of the microtubule-associated protein Tau is a hallmark of Alzheimer’s disease with Tau oligomers suspected as the most toxic agent. Tau is a client of the molecular chaperone Hsp90, although it is unclear whether and how the chaperone massages the structure of intrinsically disordered Tau. Using electron paramagnetic resonance, we extract structural information from the very broad conformational ensemble of Tau: Tau in solution is highly dynamic and polymorphic, although “paper clip”–shaped by long-range contacts. Interaction with Hsp90 promotes an open Tau conformation, which we identify as the molecular basis for the formation of small Tau oligomers by exposure of the aggregation-prone repeat domain to other Tau molecules. At the same time, formation of Tau fibrils is inhibited. We therefore provide the nanometer-scale zoom into chaperoning an amyloid client, highlighting formation of oligomers as the consequence of this biologically relevant interaction.

This paper describes geometric effects in the evolution of atoms through a double-slit type experiment on an atom chip., The geometric phase due to the evolution of the Hamiltonian is a central concept in quantum physics and may become advantageous for quantum technology. In noncyclic evolutions, a proposition relates the geometric phase to the area bounded by the phase-space trajectory and the shortest geodesic connecting its end points. The experimental demonstration of this geodesic rule proposition in different systems is of great interest, especially due to the potential use in quantum technology. Here, we report a previously unshown experimental confirmation of the geodesic rule for a noncyclic geometric phase by means of a spatial SU(2) matter-wave interferometer, demonstrating, with high precision, the predicted phase sign change and π jumps. We show the connection between our results and the Pancharatnam phase. Last, we point out that the geodesic rule may be applied to obtain the red shift in general relativity, enabling a new quantum tool to measure gravity.

The 30th of July 2020 marked the centenary of the birth of a woman who was central to the development of the field of Earth sciences: Marie Tharp, a pioneer of ocean floor cartography and marine geology. Her work was crucial in reintroducing a mobilist (drift) vision of Earth and for the development of the plate tectonics revolution in the early 1960s. The theory of continental drift proposed by Alfred Wegener in 1912—which was based on sound correspondences between rocks, fossils, and geological structures on opposite sides of the Atlantic—was initially heavily criticized and rejected by the scientific community. Some paleontologists invoked the past presence of continental bridges that subsequently collapsed to explain the similarity of the faunas between the two sides of the ocean. The hardest attack came from the field of geophysics, which perceived the biggest obstacles to be the identification of a possible “driving force” or “engine” that could move rigid crust, causing such prodigious continental drift. However, Wegener, by combining geological data that included isostasy and the evidence of radiogenic heat, proposed two main possible mechanisms for the drifting of fragments of continental crust (the so called sial)—that is, “Pohlflucht” (gravitational migration away from the poles) and/or solid tides induced by the Moon—but neither was considered plausible or able to generate such movements. A crucial missing piece in this debate was in-depth knowledge of the ocean floor, which covers more than 70% of Earth's surface. Indeed, until the first half of the past century, almost nothing was known about the real composition and physiography of the ocean floor, an area of the planet too large to be ignored in geological models at the macroscale. This is where, as some had begun to suspect, the evidence for the driving force of continental drift was hiding. Here, Marie Tharp played a key role in the 1950s when, by comparing bathymetric profiles across the Atlantic Ocean, she realized the continuity of the ocean ridges and the presence of an axial valley testifying to their expansion. The mid-Atlantic ridge was discovered by Tharp in 1952 by comparing six sheets of cruise profiles, but the existence of a V-shaped rift was initially cautiously rejected by her colleague Bruce Heezen because its mobilist implications were too radical for a scientific community that had largely rejected, if not ridiculed, the Wegener continental drift hypotheses. In a later interview, Heezen declared, “I discounted it as girl talk and didn't believe it for a year.” Subsequent research by Tharp and Heezen at the Lamont Geological Observatory of Columbia University (now the Lamont-Doherty Earth Observatory) led to a completely new and unexpected picture of the ocean floor, providing a crucial piece of data (together with magnetic reversal and hypocenter location) that would lead in a few years to the plate tectonic hypothesis. Heezen made several important discoveries in marine geology, especially with regard to sea-floor sediments and currents, challenging the traditional “permanentist” geological conception; he was also one of the principal collectors of data from the sea floor, with a 30-year project of collaborations that resulted in the first world map of the ocean floor in 1977, a document distinctive for its geological importance. By then, Heezen had devoted his professional life to studying the secrets of the oceans, dying at sea from a heart attack aboard a submarine in 1977. Having graduated with degrees in both geology and mathematics, Marie Tharp had skills that proved to be fundamental to the realization of ocean-basin topographic maps, a process that required in-depth knowledge of geography, mathematics, and geology. By using her mathematic skills, she was able to transform the huge amount of collected raw bathymetric data (the echo-sounders were in their early stage, having been invented only a few decades before) into profiles and maps. From the early 1960s onward, Heezen and Tharp published influential papers with profiles, graphs, and contour diagrams focused on the mid-Atlantic ridge and all the systems of fractures affecting this major feature. The ability to graphically transform ocean floor data into visible objects considerably facilitated new inferences and hypotheses, as well as easier communication of the evidence on which new theories could be soundly based. It was precisely these graphical results that inspired authors like J. Tuzo Wilson to propose an entirely new category of “faults”: the transform faults, a system of faults along a plate boundary characterized by a predominantly horizontal motion. Once they were appreciated, transform faults played a fundamental role in the paradigm shift of plate tectonics in geology. The publication in 1977 by Heezen and Tharp of the legendary first complete world map of the ocean floors (see the photo ) revealed to the general public the thousands-of-kilometers-long complex system of ocean ridges, fracture zones, seamounts, and trenches, revealing the geodynamic processes shaping our planet. It is regrettable to note that at the beginning of her career, Marie Tharp, as a woman, was not allowed to board the ships that were collecting the data she was studying and that her first hypotheses on sea-floor spreading were treated as mere “girl talk.” Now, her intuitions have been fully appreciated and vindicated, stressing the too-often-ignored central contribution of women to the development of science.

Imperceptible magnetic sensor matrix system realizes real-time mapping of 2D magnetic field distribution., Artificial electronic skins (e-skins) comprise an integrated matrix of flexible devices arranged on a soft, reconfigurable surface. These sensors must perceive physical interaction spaces between external objects and robots or humans. Among various types of sensors, flexible magnetic sensors and the matrix configuration are preferable for such position sensing. However, sensor matrices must efficiently map the magnetic field with real-time encoding of the positions and motions of magnetic objects. This paper reports an ultrathin magnetic sensor matrix system comprising a 2 × 4 array of magnetoresistance sensors, a bootstrap organic shift register driving the sensor matrix, and organic signal amplifiers integrated within a single imperceptible platform. The system demonstrates high magnetic sensitivity owing to the use of organic amplifiers. Moreover, the shift register enabled real-time mapping of 2D magnetic field distribution.

Going through decades of development, great progress in both theory and experiment has been achieved in thermoelectric materials. With the growing enhancement in thermoelectric performance, it is also companied with the complexation of defects induced in the materials. 0D point defects, 1D linear defects, 2D planar defects, and 3D bulk defects have all been induced in thermoelectric materials for the optimization of thermoelectric performance. Considering the distinct characteristics of each type of defects, in-depth understanding of their roles in the thermoelectric transport process is of vital importance. In this paper, we classify and summarize the defect-related physical effects on both band structure and transport behavior of carriers and phonons when inducing different types of defects. Recent achievements in experimental characterization and theoretical simulation of defects are also summarized for accurately determining the type of defects serving for the design of thermoelectric materials. Finally, based on the current theoretical and experimental achievements, strategies engaged with multiple dimensional defects are reviewed for thermoelectric performance optimization.

Single-cell network analysis demonstrates species-conserved functional roles for pulmonary alveolar cell types., Efforts to decipher chronic lung disease and to reconstitute functional lung tissue through regenerative medicine have been hampered by an incomplete understanding of cell-cell interactions governing tissue homeostasis. Because the structure of mammalian lungs is highly conserved at the histologic level, we hypothesized that there are evolutionarily conserved homeostatic mechanisms that keep the fine architecture of the lung in balance. We have leveraged single-cell RNA sequencing techniques to identify conserved patterns of cell-cell cross-talk in adult mammalian lungs, analyzing mouse, rat, pig, and human pulmonary tissues. Specific stereotyped functional roles for each cell type in the distal lung are observed, with alveolar type I cells having a major role in the regulation of tissue homeostasis. This paper provides a systems-level portrait of signaling between alveolar cell populations. These methods may be applicable to other organs, providing a roadmap for identifying key pathways governing pathophysiology and informing regenerative efforts.

This paper reports that a fine-tuning of orbital hybridization opens a door to atomic-level engineering of spin-orbit physics., Current-induced spin-orbit torques provide an effective way to manipulate magnetization in spintronic devices, promising for fast switching applications in nonvolatile memory and logic units. Recent studies have revealed that the spin-orbit torque is strongly altered by the oxidation of heterostructures with broken inversion symmetry. Although this finding opens a new field of metal-oxide spin-orbitronics, the role of the oxidation in the spin-orbit physics is still unclear. Here, we demonstrate a marked enhancement of the spin-orbit torque induced by a fine-tuning of oxygen-induced modification of orbital hybridization. This is evidenced by a concomitant enhancement of the interface spin-orbit torque, interface spin loss, and interface perpendicular magnetic anisotropy within a narrow range of the oxidation level of metallic heterostructures. This result reveals the crucial role of the atomic-scale effects in the generation of the spin-orbit torques, opening the door to atomic-level engineering of the spin-orbit physics.

This paper summarises the conclusions from the 2nd Terawatt PV workshop (2018).

To examine the contributions of impaired gut microbial community development to childhood undernutrition, we combined metabolomic and proteomic analyses of plasma samples with metagenomic analyses of fecal samples to characterize the biological state of Bangladeshi children with severe acute malnutrition (SAM) as they transitioned, after standard treatment, to moderate acute malnutrition (MAM) with persistent microbiota immaturity. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes targeting weaning-phase bacterial taxa underrepresented in SAM and MAM microbiota were characterized in gnotobiotic mice and gnotobiotic piglets colonized with age- and growth-discriminatory bacteria. A randomized, double-blind controlled feeding study identified a lead MDCF that changes the abundances of targeted bacteria and increases plasma biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function in children with MAM. INTRODUCTION There is a dimension to post-natal human development that involves assembly of microbial communities in different body habitats, including the gut. Children with acute malnutrition have impaired development of their gut microbiota, leaving them with communities that appear younger (more immature) than those of chronologically age-matched healthy individuals. Current therapeutic foods given to children with acute malnutrition have not been formulated based on knowledge of how they affect the developmental biology of the gut microbiota. Moreover, they are largely ineffective in ameliorating the long-term sequelae of malnutrition that include persistent stunting, neurodevelopmental abnormalities, and immune dysfunction. RATIONALE Repairing microbiota immaturity and determining the degree to which such repair restores healthy growth requires identification of microbial targets that are not only biomarkers of community assembly but also mediators of various aspects of growth. Identifying ingredients in complementary foods, consumed during the transition from exclusive milk feeding to a fully weaned state, that increase the representation and expressed beneficial functions of growth-promoting bacterial taxa in the developing microbiota could provide an effective, affordable, culturally acceptable, and sustainable approach to treatment. RESULTS Metabolomic and proteomic analyses of serially collected plasma samples were combined with metagenomic analyses of serially collected fecal samples from Bangladeshi children with severe acute malnutrition (SAM) treated with standard therapy. The results provided a readout of their biological features as they transitioned from SAM to a state of persistent moderate acute malnutrition (MAM) with accompanying persistent microbiota immaturity. Significant correlations were identified between levels of plasma proteins, anthropometry, plasma metabolites, and the representation of bacteria in their microbiota. Gnotobiotic mice were subsequently colonized with a defined consortium of bacterial strains that represent various phases of microbiota development in healthy Bangladeshi children. Administration of different combinations of Bangladeshi complementary food ingredients to colonized mice and germ-free controls revealed diet-dependent increases in the abundance and changes in the metabolic activities of targeted weaning-phase strains as well as diet- and colonization-dependent augmentation of growth-promoting host signaling pathways. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes were subsequently examined in gnotobiotic mice colonized with immature microbiota from children with post-SAM MAM and in gnotobiotic piglets colonized with a defined consortium of targeted age- and growth-discriminatory taxa. A randomized, double-blind study of standard therapy versus various MDCF prototypes emerging from these preclinical models, conducted in Bangladeshi children with MAM, identified a lead MDCF that increased levels of biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function toward a state resembling healthy children. Using an approach inspired by statistical methods applied to financial markets, we show in the accompanying paper by Raman et al. that this lead MDCF was most effective in repairing the microbiota. CONCLUSION These findings demonstrate the translatability of results obtained from pre-clinical gnotobiotic animal models to humans, directly support the hypothesis that healthy microbiota development is causally linked to healthy growth, illustrate an approach for treating childhood undernutrition, and with the capacity to deliberately reconfigure immature microbiota, suggest a means to decipher how elements of the gut microbial community operate to regulate various host systems involved in healthy growth. Overview of therapeutic food discovery and testing. The approach used for integrating preclinical gnotobiotic animal models with human studies to understand the contributions of perturbed gut microbiota development to childhood malnutrition and to identify MDCFs.

The direct product between classical and quantum degrees of freedom may be left unopened., We propose a solution to the matrix dimension problem in quantum mechanical simulations of MRI (magnetic resonance imaging) experiments on complex molecules. This problem is very old; it arises when Kronecker products of spin operators and spatial dynamics generators are taken—the resulting matrices are far too large for any current or future computer. However, spin and spatial operators individually have manageable dimensions, and we note here that the action by their Kronecker products on any vector may be computed without opening those products. This eliminates large matrices from the simulation process. MRI simulations for coupled spin systems of complex metabolites in three dimensions with diffusion, flow, chemical kinetics, and quantum mechanical treatment of spin relaxation are now possible. The methods described in this paper are implemented in versions 2.4 and later of the Spinach library.

N-type ZrCoBi-based half-Heusler thermoelectric performance is predicted by weighted mobility ratio and experimentally verified., Thermoelectric modules, consisting of multiple pairs of n- and p-type legs, enable converting heat into electricity and vice versa. However, the thermoelectric performance is often asymmetrical, in that one type outperforms the other. In this paper, we identified the relationship between the asymmetrical thermoelectric performance and the weighted mobility ratio, a correlation that can help predict the thermoelectric performance of unreported materials. Here, a reasonably high ZT for the n-type ZrCoBi-based half-Heuslers is first predicted and then experimentally verified. A high peak ZT of ~1 at 973 K can be realized by ZrCo0.9Ni0.1Bi0.85Sb0.15. The measured heat-to-electricity conversion efficiency for the unicouple of ZrCoBi-based materials can be as high as ~10% at the cold-side temperature of ~303 K and at the hot-side temperature of ~983 K. Our work demonstrates that the ZrCoBi-based half-Heuslers are highly promising for the application of mid- and high-temperature thermoelectric power generation.

We demonstrate a counterintuitive mechanism of converting compressive impact to tensile waves in origami-based metamaterials., The principles underlying the art of origami paper folding can be applied to design sophisticated metamaterials with unique mechanical properties. By exploiting the flat crease patterns that determine the dynamic folding and unfolding motion of origami, we are able to design an origami-based metamaterial that can form rarefaction solitary waves. Our analytical, numerical, and experimental results demonstrate that this rarefaction solitary wave overtakes initial compressive strain waves, thereby causing the latter part of the origami structure to feel tension first instead of compression under impact. This counterintuitive dynamic mechanism can be used to create a highly efficient—yet reusable—impact mitigating system without relying on material damping, plasticity, or fracture.

Failed attempts to reproduce measurements suffer from lower resolution not ghosts., Gehring et al. argue that a splitting observed by us in the transverse acoustic (TA) phonon in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)1−xTix]O3 with x = 0.30 (PMN-30PT) is caused by a combination of inelastic-elastic multiple scattering processes called ghostons. Their argument is motivated by differences observed between their measurements made on a triple-axis spectrometer and our measurements on a time-of-flight spectrometer. We show that the differences can be explained by differences in the instrument resolution functions. We demonstrate that the multiple scattering conditions proposed by Gehring et al. do not work for our scattering geometry. We also show that, when a ghoston is present, it is too weak to detect and therefore cannot explain the splitting. Last, this phonon splitting is just one part of the argument, and the overall conclusion of the original paper is supported by other results.

An accommodation-free displays, also known as Maxwellian displays, keep the displayed image sharp regardless of the viewer’s focal distance. However, they typically suffer from a small eye-box and limited effective field of view (FOV) which requires careful alignment before a viewer can see the image. This paper presents a high-quality accommodation-free head mounted display (aHMD) based on pixel beam scanning for direct image forming on retina. It has an enlarged eye-box and FOV for easy viewing by replicating the viewing points with an array of beam splitters. A prototype aHMD is built using this concept, which shows high definition, low colour aberration 3D augmented reality (AR) images with an FOV of 36°. The advantage of the proposed design over other head mounted display (HMD) architectures is that, due to the narrow, collimated pixel beams, the high image quality is unaffected by changes in eye accommodation, and the approach to enlarge the eye-box is scalable. Most importantly, such an aHMD can deliver realistic three-dimensional (3D) viewing perception with no vergence-accommodation conflict (VAC). It is found that viewing the accommodation-free 3D images with the aHMD presented in this work is comfortable for viewers and does not cause the nausea or eyestrain side effects commonly associated with conventional stereoscopic 3D or HMD displays, even for all day use.

The well-known small-world network model was established by randomly rewiring edges, aiming to enhance the synchronizability of an undirected nearest-neighbor regular network. This paper demonstrates via extensive numerical simulations that randomly redirecting edges could enhance the robustness of the network controllability for directed snapback networks against both random and intentional node-removal and edge-removal attacks.

Commensals rule the MAITrix Mucosal-associated invariant T (MAIT) cells play an important role in mucosal homeostasis. MAIT cells recognize microbial small molecules presented by the major histocompatibility complex class Ib molecule MR1. MAIT cells are absent in germ-free mice, and the mechanisms by which microbiota control MAIT cell development are unknown (see the Perspective by Oh and Unutmaz). Legoux et al. show that, in mice, development of MAIT cells within the thymus is governed by the bacterial product 5-(2-oxopropylideneamino)-6- d -ribitylaminouracil, which rapidly traffics from the mucosa to the thymus, where it is captured by MR1 and presented to developing MAIT cells. Constantinides et al. report that MAIT cell induction only occurs during a limited, early-life window and requires exposure to defined microbes that produce riboflavin derivatives. Continual interactions between MAIT cells and commensals in the skin modulates tissue repair functions. Together, these papers highlight how the microbiota can direct immune cell development and subsequent function at mucosal sites by secreting compounds that act like self-antigens. Science , this issue p. 494 , p. eaax6624 ; see also p. 419

The growth of crystalline Si (c-Si) via direct electron beam writing shows promise for fabricating Si nanomaterials due to its ultrahigh resolution. However, to increase the writing speed is a major obstacle, due to the lack of systematic experimental explorations of the growth process and mechanisms. This paper reports a systematic experimental investigation of the beam-induced formation of c-Si nanoparticles (NPs) from amorphous SiO 2 under a range of doses and temperatures by in situ transmission electron microscopy at the atomic scale. A three-orders-of-magnitude writing speed-up is identified under 80 keV irradiation at 600°C compared with 300 keV irradiation at room temperature. Detailed analysis reveals that the self-organization of c-Si NPs is driven by reduction of c-Si effective free energy under electron irradiation. This study provides new insights into the formation mechanisms of c-Si NPs during direct electron beam writing and suggests methods to improve the writing speed.

Fungal effectors of wheat stem rust The fungal pathogen Ug99 (named for its identification in Uganda in 1999) threatens wheat crops worldwide. Ug99 can kill entire fields of wheat and is undeterred by many of the disease-resistance genes that otherwise protect wheat crops. Two papers describe two peptides secreted by the fungus as it attacks the wheat (see the Perspective by Moscou and van Esse). Chen et al. show that fungal AvrSr50 binds to the plant's immune receptor Sr50, and Salcedo et al. show that fungal AvrSr35 binds to Sr35. Successful binding activates the plant's immune defenses. Removing or inactivating these Avr effectors leaves the plant defenseless and susceptible to disease. Science , this issue p. 1607 , p. 1604 ; see also p. 1541

The 30 Doradus star-forming region in the Large Magellanic Cloud is a nearby analogue of large star-formation events in the distant Universe. We determine the recent formation history and the initial mass function (IMF) of massive stars in 30 Doradus based on spectroscopic observations of 247 stars more massive than 15 solar masses ($\mathrm{M}_\odot$). The main episode of massive star formation started about $8\,\mathrm{Myr}$ ago and the star-formation rate seems to have declined in the last $1\,\mathrm{Myr}$. The IMF is densely sampled up to $200\,\mathrm{M}_\odot$ and contains $32\pm12\%$ more stars above $30\,\mathrm{M}_\odot$ than predicted by a standard Salpeter IMF. In the mass range $15-200\,\mathrm{M}_\odot$, the IMF power-law exponent is $1.90^{+0.37}_{-0.26}$, shallower than the Salpeter value of 2.35., Authors' version of paper published in Science at http://science.sciencemag.org/content/359/6371/69 ; 15 pages main text (3 figures), 47 pages supplementary materials (10 figures, 3 tables)

Electrochemical twin channels make glucose in vessels measurable by noninvasive ultrathin skin-like highly sensitive biosensors., Currently, noninvasive glucose monitoring is not widely appreciated because of its uncertain measurement accuracy, weak blood glucose correlation, and inability to detect hyperglycemia/hypoglycemia during sleep. We present a strategy to design and fabricate a skin-like biosensor system for noninvasive, in situ, and highly accurate intravascular blood glucose monitoring. The system integrates an ultrathin skin-like biosensor with paper battery–powered electrochemical twin channels (ETCs). The designed subcutaneous ETCs drive intravascular blood glucose out of the vessel and transport it to the skin surface. The ultrathin (~3 μm) nanostructured biosensor, with high sensitivity (130.4 μA/mM), fully absorbs and measures the glucose, owing to its extreme conformability. We conducted in vivo human clinical trials. The noninvasive measurement results for intravascular blood glucose showed a high correlation (>0.9) with clinically measured blood glucose levels. The system opens up new prospects for clinical-grade noninvasive continuous glucose monitoring.

We introduce MINFLUX, a concept for localizing photon emitters in space. By probing the emitter with a local intensity minimum of excitation light, MINFLUX minimizes the fluorescence photons needed for high localization precision. A 22-fold reduction of photon detections over that required in popular centroid-localization is demonstrated. In superresolution microscopy, MINFLUX attained ~1 nm precision, resolving molecules only 6 nm apart. Tracking single fluorescent proteins by MINFLUX increased the temporal resolution and the localizations per trace by 100-fold, as demonstrated with diffusing 30S ribosomal subunits in living E. coli. Since conceptual limits have not been reached, we expect this localization modality to break new ground for observing the dynamics, distribution, and structure of macromolecules in living cells and beyond., Equal contributions: Francisco Balzarotti, Yvan Eilers, Klaus C. Gwosch Correspondence to: shell@gwdg.de; Phone +495512012500 Pages: 17 (main paper), Figures: 5

Pulsars emit low-frequency radio waves through to high-energy gamma-rays that are generated anywhere from the surface out to the edges of the magnetosphere. Detecting correlated mode changes in the multi-wavelength emission is therefore key to understanding the physical relationship between these emission sites. Through simultaneous observations, we have detected synchronous switching in the radio and X-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio 'bright' mode, the X-rays show only an un-pulsed, non-thermal component. Conversely, when the pulsar is in a radio 'quiet' mode, the X-ray luminosity more than doubles and a 100%-pulsed thermal component is observed along with the non-thermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories., Paper published in Science including supplementary material

This paper uses temporal variations in seismic velocity to identify pressurized pore fluids in forearc crust., In subduction zones, elevated pore fluid pressure, generally linked to metamorphic dehydration reactions, has a profound influence on the mechanical behavior of the plate interface and forearc crust through its control on effective stress. We use seismic noise–based monitoring to characterize seismic velocity variations following the 2012 Nicoya Peninsula, Costa Rica earthquake [Mw (moment magnitude) 7.6] that we attribute to the presence of pressurized pore fluids. Our study reveals a strong velocity reduction (~0.6%) in a region where previous work identified high forearc pore fluid pressure. The depth of this velocity reduction is constrained to be below 5 km and therefore not the result of near-surface damage due to strong ground motions; rather, we posit that it is caused by fracturing of the fluid-pressurized weakened crust due to dynamic stresses. Although pressurized fluids have been implicated in causing coseismic velocity reductions beneath the Japanese volcanic arc, this is the first report of a similar phenomenon in a subduction zone setting. It demonstrates the potential to identify pressurized fluids in subduction zones using temporal variations of seismic velocity inferred from ambient seismic noise correlations.