Search for: All records

Abstract The deliberate addition of sulfur dioxide in the stratosphere to form reflective sulfate aerosols, reflect sunlight, and reduce surface temperatures is increasingly being considered as an option for minimizing the impacts of climate change. This strategy would create an unprecedented climate where the relationship between surface temperature and carbon dioxide concentration is decoupled. The implications of stratospheric aerosol intervention (SAI) for global crop protein concentrations have not yet been explored. While elevated CO₂concentrations are expected to reduce crop protein, higher temperatures may increase crop protein concentrations. Here we report changes of maize, rice, soybean, and wheat protein concentrations under a medium emissions climate change scenario and a SAI scenario to maintain global average temperatures at 1.5 °C above preindustrial levels, as simulated by three global gridded crop models. We show that using SAI to offset surface temperature increases would create decreases in the global protein concentrations of maize and rice, with minimal impact on wheat and soybean. Some already protein-deficient and malnourished nations that rely heavily on these crops to meet protein demands would show large decreases in protein intake under SAI with the current diet pattern, which could exacerbate their nutrient scarcity. The range of results between crop models highlights the need for a more comprehensive analysis using additional crop models, climate models, a broader range of climate intervention scenarios, and advancements in crop models to better represent protein responses to climate changes. 

Crop production is among the most extensive human activities on the planet – with critical importance for global food security, land use, environmental burden, and climate. Yet despite the key role that croplands play in global land use and Earth systems, there remains little understanding of how spatial patterns of global crop cultivation have recently evolved and which crops have contributed most to these changes. Here we construct a new data library of subnational crop-specific irrigated and rainfed harvested area statistics and combine it with global gridded land cover products to develop a global gridded (5-arcminute) irrigated and rainfed cropped area (MIRCA-OS) dataset for the years 2000 to 2015 for 23 crop classes. These global data products support critical insights into the spatially detailed patterns of irrigated and rainfed cropland change since the start of the century and provide an improved foundation for a wide array of global assessments spanning agriculture, water resource management, land use change, climate impact, and sustainable development. 

Abstract Hi-C characterizes three-dimensional chromatin organization, facilitates haplotype phasing, and enables genome-assembly scaffolding, but encounters difficulties across complex regions. By coupling chromosome conformation capture (3C) with PacBio HiFilong-read sequencing, here we develop a method (CiFi) that enables analysis of genomic interactions across repetitive regions. Starting with as little as 60,000 cells (sub-microgram DNA), the method produces multi-kilobasepair HiFi reads that contain multiple interacting, concatenated segments (~350 bp to 2 kbp). This multiplicity and increase in segment length versus standard short-read-based Hi-C improves read-mapping efficiency and coverage in repetitive regions and enhances haplotype phasing. CiFi pairwise interactions are largely concordant with Hi-C from a human lymphoblastoid cell line, with gains in assigning topologically associating domains across centromeres, segmental duplications, and human disease-associated genomic hotspots. As CiFi requires less input versus established methods, we apply the approach to characterize single small insects: assaying chromatin interactions across the genome from anAnopheles coluzziimosquito and producing a chromosome-scale scaffolded assembly from aCeratitis capitataMediterranean fruit fly. Together, CiFi enables assessment of chromosome-scale interactions of previously recalcitrant low-complexity loci, low-input samples, and small organisms. 

The OS page cache is central to the performance of many applications, by reducing excessive accesses to storage. However, its one-size-fits-all eviction policy performs poorly in many workloads. While the systems community has experimented with a plethora of new and adaptive eviction policies in non-OS settings (e.g., key-value stores, CDNs), it is very difficult to implement such policies in the page cache, due to the complexity of modifying kernel code. To address these shortcomings, we design a flexible eBPF-based framework for the Linux page cache, called cache_ext, that allows developers to customize the page cache without modifying the kernel. cache_ext enables applications to customize the page cache policy for their specific needs, while also ensuring that different applications’ policies do not interfere with each other and preserving the page cache’s ability to share memory across different processes. We demonstrate the flexibility of cache_ext’s interface by using it to implement eight different policies, including sophisticated eviction algorithms. Our evaluation shows that it is indeed beneficial for applications to customize the page cache to match their workloads’ unique properties, and that they can achieve up to 70% higher throughput and 58% lower tail latency. 

The advent of artificial intelligence and machine learning has led to significant technological and scientific progress, but also to new challenges. Partial differential equations, usually used to model systems in the sciences, have shown to be useful tools in a variety of tasks in the data sciences, be it just as physical models to describe physical data, as more general models to replace or construct artificial neural networks, or as analytical tools to analyse stochastic processes appearing in the training of machine-learning models. This article acts as an introduction of a theme issue covering synergies and intersections of partial differential equations and data science. We briefly review some aspects of these synergies and intersections in this article and end with an editorial foreword to the issue. This article is part of the theme issue ‘Partial differential equations in data science’. 

Increasing evidence strongly links neuroinflammation to Alzheimer’s disease (AD) pathogenesis. Peripheral monocytes are crucial components of the human immune system, but their contribution to AD pathogenesis is still largely understudied partially due to limited human models. Here, we introduce human cortical organoid microphysiological systems (hCO-MPSs) to study AD monocyte-mediated neuroinflammation. By culturing doughnut-shape organoids on 3D-printed devices within standard 96-well plates, we generate hCO-MPSs with reduced necrosis, minimized hypoxia, and improved viability. Using these models, we found that monocytes from AD patients exhibit increased infiltration ability, decreased amyloid-β clearance capacity, and stronger inflammatory response than monocytes from age-matched control donors. Moreover, we observed that AD monocytes induce pro-inflammatory effects such as elevated astrocyte activation and neuronal apoptosis. Furthermore, the marked increase in IL1B and CCL3 expression underscores their pivotal role in AD monocyte-mediated neuroinflammation. Our findings provide insight into understanding monocytes’ role in AD pathogenesis, and our lab-compatible MPS models may offer a promising way for studying various neuroinflammatory diseases. 

Abstract AB-stacked bilayer graphene has emerged as a fascinating yet simple platform for exploring macroscopic quantum phenomena of correlated electrons. Under large electric displacement fields and near low-density van-Hove singularities, it exhibits a phase with features consistent with Wigner crystallization, including negative dR/dT and nonlinear bias behavior. However, direct evidence for the emergence of an electron crystal at zero magnetic field remains elusive. Here, we explore low-frequency noise consistent with depinning and sliding of a Wigner crystal or solid. At large magnetic fields, we observe enhanced noise at low bias current and a frequency-dependent response characteristic of depinning and sliding, consistent with earlier scanning tunnelling microscopy studies confirming Wigner crystallization in the fractional quantum Hall regime. At zero magnetic field, we detect pronounced AC noise whose peak frequency increases linearly with applied DC current—indicative of collective electron motion. These transport signatures pave the way toward confirming an anomalous Hall crystal. 

Abstract Converting CO₂into industrially useful products is an appealing strategy for utilization of an abundant chemical resource. Electrochemical CO₂reduction (eCO₂R) offers a pathway to convert CO₂into CO and ethylene, using renewable electricity. These products can be efficiently copolymerized by organometallic catalysts to generate polyketones. However, the conditions for these reactions are very different, presenting the challenge of coupling microenvironments typically encountered for the transformation of CO₂into highly complex but desirable multicarbon products. Herein, we present a system to produce polyketone plastics entirely derived from CO₂and water, where both the CO and C₂H₄intermediates are produced by eCO₂R. In this system, a combination of Cu and Ag gas diffusion electrodes is used to generate a gas mixture with nearly equal concentrations of CO and C₂H₄, and a recirculatory CO₂reduction loop is used to reach concentrations of above 11% each, leading to a current‐to‐polymer efficiency of up to 51% and CO₂utilization of 14%. 

Abstract A coronal hole formed as a result of a quiet-Sun filament eruption close to the solar disk center on 2014 June 25. We studied this formation using images from the Atmospheric Imaging Assembly (AIA), magnetograms from the Helioseismic and Magnetic Imager, and a differential emission measure analysis derived from the AIA images. The coronal hole developed in three stages: (1) formation, (2) migration, and (3) stabilization. In the formation phase, the emission measure (EM) and temperature started to decrease 6 hr before the filament erupted. Then, the filament erupted and a large coronal dimming formed over the following 3 hr. Subsequently, in a phase lasting 15.5 hr, the coronal dimming migrated by ≈150″from its formation site to a location where potential field source surface extrapolations indicate the presence of open magnetic field lines, marking the transition into a coronal hole. During this migration, the coronal hole drifted across quasi-stationary magnetic elements in the photosphere, implying the occurrence of magnetic interchange reconnection at the boundaries of the coronal hole. In the stabilization phase, the magnetic properties and area of the coronal hole became constant. The EM of the coronal hole decreased, which we interpret as a reduction in plasma density due to the onset of plasma outflow into interplanetary space. As the coronal hole rotated toward the solar limb, it merged with a nearby preexisting coronal hole. At the next solar rotation, the coronal hole was still apparent, indicating a lifetime of >1 solar rotation.