161 research outputs found
When things matter: A survey on data-centric Internet of Things
With the recent advances in radio-frequency identification (RFID), low-cost wireless sensor devices, and Web technologies, the Internet of Things (IoT) approach has gained momentum in connecting everyday objects to the Internet and facilitating machine-to-human and machine-to-machine communication with the physical world. IoT offers the capability to connect and integrate both digital and physical entities, enabling a whole new class of applications and services, but several significant challenges need to be addressed before these applications and services can be fully realized. A fundamental challenge centers around managing IoT data, typically produced in dynamic and volatile environments, which is not only extremely large in scale and volume, but also noisy and continuous. This paper reviews the main techniques and state-of-the-art research efforts in IoT from data-centric perspectives, including data stream processing, data storage models, complex event processing, and searching in IoT. Open research issues for IoT data management are also discussed
Time-reversal symmetry breaking driven topological phase transition in EuB
The interplay between time-reversal symmetry (TRS) and band topology plays a
crucial role in topological states of quantum matter. In
time-reversal-invariant (TRI) systems, the inversion of spin-degenerate bands
with opposite parity leads to nontrivial topological states, such as
topological insulators and Dirac semimetals. When the TRS is broken, the
exchange field induces spin splitting of the bands. The inversion of a pair of
spin-splitting subbands can generate more exotic topological states, such as
quantum anomalous Hall insulators and magnetic Weyl semimetals. So far, such
topological phase transitions driven by the TRS breaking have not been
visualized. In this work, using angle-resolved photoemission spectroscopy, we
have demonstrated that the TRS breaking induces a band inversion of a pair of
spin-splitting subbands at the TRI points of Brillouin zone in EuB, when a
long-range ferromagnetic order is developed. The dramatic changes in the
electronic structure result in a topological phase transition from a TRI
ordinary insulator state to a TRS-broken topological semimetal (TSM) state.
Remarkably, the magnetic TSM state has an ideal electronic structure, in which
the band crossings are located at the Fermi level without any interference from
other bands. Our findings not only reveal the topological phase transition
driven by the TRS breaking, but also provide an excellent platform to explore
novel physical behavior in the magnetic topological states of quantum matter.Comment: 22 pages, 7 figures, accepted by Phys. Rev.
Persistent sulfate formation from London Fog to Chinese haze
Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world
ACEMBL Tool-Kits for High-Throughput Multigene Delivery and Expression in Prokaryotic and Eukaryotic Hosts
Haplotype-resolved genome assembly and allele-specific gene expression in cultivated ginger
Ginger (Zingiber officinale) is one of the most valued spice plants worldwide; it is prized for its culinary and folk medicinal applications and is therefore of high economic and cultural importance. Here, we present a haplotype-resolved, chromosome-scale assembly for diploid ginger anchored to 11 pseudochromosome pairs with a total length of 3.1âGb. Remarkable structural variation was identified between haplotypes, and two inversions larger than 15âMb on chromosome 4 may be associated with ginger infertility. We performed a comprehensive, spatiotemporal, genome-wide analysis of allelic expression patterns, revealing that most alleles are coordinately expressed. The alleles that exhibited the largest differences in expression showed closer proximity to transposable elements, greater coding sequence divergence, more relaxed selection pressure, and more transcription factor binding site differences. We also predicted the transcription factors potentially regulating 6-gingerol biosynthesis. Our allele-aware assembly provides a powerful platform for future functional genomics, molecular breeding, and genome editing in ginger.https://www.nature.com/hortreshj2022BiochemistryGeneticsMicrobiology and Plant Patholog
Vitamin D and cause-specific vascular disease and mortality:a Mendelian randomisation study involving 99,012 Chinese and 106,911 European adults
Challenges of additive manufacturing technologies from an optimisation perspective
Three-dimensional printing offers varied possibilities of design that can be bridged to optimisation tools. In this review paper, a critical opinion on optimal design is delivered to show limits, benefits and ways of improvement in additive manufacturing. This review emphasises on design constrains related to additive manufacturing and differences that may appear between virtual and real design. These differences are explored based on 3D imaging techniques that are intended to show defect related processing. Guidelines of safe use of the term âoptimal designâ are derived based on 3D structural information
Overexpression of a brassinosteroid biosynthetic gene Dwarf enhances photosynthetic capacity through activation of Calvin cycle enzymes in tomato
The topographic evolution of the Tibetan Region as revealed by palaeontology
The Tibetan Plateau was built through a succession of Gondwanan terranes colliding with Asia during the Mesozoic. These accretions produced a complex Paleogene topography of several predominantly eastâwest trending mountain ranges separated by deep valleys. Despite this piecemeal assembly and resultant complex relief, Tibet has traditionally been thought of as a coherent entity rising as one unit. This has led to the widely used phrase âthe uplift of the Tibetan Plateauâ, which is a false concept borne of simplistic modelling and confounds understanding the complex interactions between topography climate and biodiversity. Here, using the rich palaeontological record of the Tibetan region, we review what is known about the past topography of the Tibetan region using a combination of quantitative isotope and fossil palaeoaltimetric proxies, and present a new synthesis of the orography of Tibet throughout the Paleogene. We show why âthe uplift of the Tibetan Plateauâ never occurred, and quantify a new pattern of topographic and landscape evolution that contributed to the development of todayâs extraordinary Asian biodiversity
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