One of the most promising approaches to reach a high gain in inertial confinement fusion is the fast ignition scheme. In this scheme, a relativistic electron beam is generated; this passes through ...the imploded plasma and deposits parts of its energy in the core. However, the large angular spread of the relativistic electron beam and the poorly controlled compression of the target affect realization of the fast ignition technique. Here, we demonstrate that indirectly driven (that is, driven by X-rays generated inside a gold hohlraum) implosions with a ‘high-foot’ and a short-coast time of less than 200 ps allow us to tightly compress the shell. Furthermore, we show the ability to optimize the symmetry of the imploding shell by changing the hohlraum length, successfully tuning a suitable tube-shaped shell to compensate for the large angular spread of the relativistic electron beam and to enhance the electron-to-core coupling efficiency via resistive magnetic fields. Benefiting from those experimental techniques, a significant enhancement in neutron yield was achieved in our indirectly driven fast ignition experiments. These results pave the way towards high-coupling fast ignition experiments with indirectly driven targets similar to those at the National Ignition Facility.Experiments realizing the indirect-drive fast ignition scheme for inertial confinement fusion are reported. Enabled by a tightly compressed target, an increase of neutron yield is observed.
MicroRNAs have been shown to play an important role in normal hematopoisis and leukemogenesis. Here, we report function and mechanisms of miR-181 family in myeloid differentiation and acute myeloid ...leukemia (AML). The aberrant overexpression of all the miR-181 family members (miR-181a/b/c/d) was detected in French-American-British M1, M2 and M3 subtypes of adult AML patients. By conducting gain- and loss-of-function experiments, we demonstrated that miR-181a inhibits granulocytic and macrophage-like differentiation of HL-60 cells and CD34+ hematopoietic stem/progenitor cells (HSPCs) by directly targeting and downregulating the expression of PRKCD (which then affected the PRKCD-P38-C/EBPα pathway), CTDSPL (which then affected the phosphorylation of retinoblastoma protein) and CAMKK1. The three genes were also demonstrated to be the targets of miR-181b, miR-181c and miR-181d, respectively. Significantly decreases in the expression levels of the target proteins were detected in AML patients. Inhibition of the expression of miR-181 family members owing to Lenti-miRZip-181a infection in bone marrow blasts of AML patients increased target protein expression levels and partially reversed myeloid differentiation blockage. In the mice implanted with AML CD34+ HSPCs, expression inhibition of the miR-181 family by Lenti-miRZip-181a injection improved myeloid differentiation, inhibited engraftment and infiltration of the leukemic CD34+ cells into the bone marrow and spleen, and released leukemic symptoms. In conclusion, our findings revealed new mechanism of miR-181 family in normal hematopoiesis and AML development, and suggested that expression inhibition of the miR-181 family could provide a new strategy for AML therapy.
The North China Plain (NCP) frequently experiences heavy haze pollution, particularly during wintertime. In winter 2015–2016, the NCP region suffered several extremely severe haze episodes with air ...pollution red alerts issued in many cities. We have investigated the sources and aerosol evolution processes of the severe pollution episodes in Handan, a typical industrialized city in the NCP region, using real-time measurements from an intensive field campaign during the winter of 2015–2016. The average (±1σ) concentration of submicron aerosol (PM1) during 3 December 2015–5 February 2016 was 187.6 (±137.5) µg m−3, with the hourly maximum reaching 700.8 µg m−3. Organic was the most abundant component, on average accounting for 45 % of total PM1 mass, followed by sulfate (15 %), nitrate (14 %), ammonium (12 %), chloride (9 %) and black carbon (BC, 5 %). Positive matrix factorization (PMF) with the multilinear engine (ME-2) algorithm identified four major organic aerosol (OA) sources, including traffic emissions represented by a hydrocarbon-like OA (HOA, 7 % of total OA), industrial and residential burning of coal represented by a coal combustion OA (CCOA, 29 % of total OA), open and domestic combustion of wood and crop residuals represented by a biomass burning OA (BBOA, 25 % of total OA), and formation of secondary OA (SOA) in the atmosphere represented by an oxygenated OA (OOA, 39 % of total OA). Emissions of primary OA (POA), which together accounted for 61 % of total OA and 27 % of PM1, are a major cause of air pollution during the winter. Our analysis further uncovered that primary emissions from coal combustion and biomass burning together with secondary formation of sulfate (mainly from SO2 emitted by coal combustion) are important driving factors for haze evolution. However, the bulk composition of PM1 showed comparatively small variations between less polluted periods (daily PM2. 5 ≤ 75 µg m−3) and severely polluted periods (daily PM2. 5 > 75 µg m−3), indicating relatively synchronous increases of all aerosol species during haze formation. The case study of a severe haze episode, which lasted 8 days starting with a steady buildup of aerosol pollution followed by a persistently high level of PM1 (326.7–700.8 µg m−3), revealed the significant influence of stagnant meteorological conditions which acerbate air pollution in the Handan region. The haze episode ended with a shift of wind which brought in cleaner air masses from the northwest of Handan and gradually reduced PM1 concentration to < 50 µg m−3 after 12 h. Aqueous-phase reactions under higher relative humidity (RH) were found to significantly promote the production of secondary inorganic species (especially sulfate) but showed little influence on SOA.
Conventional hardware platforms consume huge amount of energy for cognitive learning due to the data movement between the processor and the off-chip memory. Brain-inspired device technologies using ...analogue weight storage allow to complete cognitive tasks more efficiently. Here we present an analogue non-volatile resistive memory (an electronic synapse) with foundry friendly materials. The device shows bidirectional continuous weight modulation behaviour. Grey-scale face classification is experimentally demonstrated using an integrated 1024-cell array with parallel online training. The energy consumption within the analogue synapses for each iteration is 1,000 × (20 ×) lower compared to an implementation using Intel Xeon Phi processor with off-chip memory (with hypothetical on-chip digital resistive random access memory). The accuracy on test sets is close to the result using a central processing unit. These experimental results consolidate the feasibility of analogue synaptic array and pave the way toward building an energy efficient and large-scale neuromorphic system.
Background
The aim of this study was to investigate the prevalence of epidemiologic and physician‐diagnosed pollen‐induced AR (PiAR) in the grasslands of northern China and to study the impact of the ...intensity and time of pollen exposure on PiAR prevalence.
Methods
A multistage, clustered and proportionately stratified random sampling with a field interviewer‐administered survey study was performed together with skin prick tests (SPT) and measurements of the daily pollen count.
Results
A total of 6043 subjects completed the study, with a proportion of 32.4% epidemiologic AR and 18.5% PiAR. The prevalence was higher in males than females (19.6% vs 17.4%, P = .024), but no difference between the two major residential and ethnic groups (Han and Mongolian) was observed. Subjects from urban areas showed higher prevalence of PiAR than rural areas (23.1% vs 14.0%, P < .001). Most PiAR patients were sensitized to two or more pollens (79.4%) with artemisia, chenopodium, and humulus scandens being the most common pollen types, which were similarly found as the top three sensitizing pollen allergens by SPT. There were significant regional differences in the prevalence of epidemiologic AR (from 18.6% to 52.9%) and PiAR (from 10.5% to 31.4%) among the six areas investigated. PiAR symptoms were positively associated with pollen counts, temperature, and precipitation (P < .05), but negatively with wind speed and pressure P < .05).
Conclusion
Pollen‐induced AR (PiAR) prevalence in the investigated region is extremely high due to high seasonal pollen exposure, which was influenced by local environmental and climate conditions.
Particle trapping and binding in optical potential wells provide a versatile platform for various biomedical applications. However, implementation systems to study multi-particle contact interactions ...in an optical lattice remain rare. By configuring an optofluidic lattice, we demonstrate the precise control of particle interactions and functions such as controlling aggregation and multi-hopping. The mean residence time of a single particle is found considerably reduced from 7 s, as predicted by Kramer's theory, to 0.6 s, owing to the mechanical interactions among aggregated particles. The optofluidic lattice also enables single-bacteria-level screening of biological binding agents such as antibodies through particle-enabled bacteria hopping. The binding efficiency of antibodies could be determined directly, selectively, quantitatively and efficiently. This work enriches the fundamental mechanisms of particle kinetics and offers new possibilities for probing and utilising unprecedented biomolecule interactions at single-bacteria level.
Neuromorphic visual systems have considerable potential to emulate basic functions of the human visual system even beyond the visible light region. However, the complex circuitry of artificial visual ...systems based on conventional image sensors, memory and processing units presents serious challenges in terms of device integration and power consumption. Here we show simple two-terminal optoelectronic resistive random access memory (ORRAM) synaptic devices for an efficient neuromorphic visual system that exhibit non-volatile optical resistive switching and light-tunable synaptic behaviours. The ORRAM arrays enable image sensing and memory functions as well as neuromorphic visual pre-processing with an improved processing efficiency and image recognition rate in the subsequent processing tasks. The proof-of-concept device provides the potential to simplify the circuitry of a neuromorphic visual system and contribute to the development of applications in edge computing and the internet of things.
The effect and mechanism of ultrasonic vibration on the microstructure and performance of laser cladding 316L coating has been studied, providing a theoretical basis and technical support for the ...application of the ultrasonic-assisted laser cladding process. The results show that ultrasonic vibrations with different amplitudes can effectively improve the macroscopic forming quality of the cladding layer, among which the ultrasonic vibration with 17.5 μm amplitude is the best. Ultrasonic vibration can also significantly improve the micro-forming quality of the cladding layer, such as homogenizing the structure, refining grains and reducing porosity. The wear mechanism of the cladding layer with an ultrasonic assistance of 17.5 μm is mainly abrasive wear, so the wear resistance has been significantly improved. The ultrasonic-assisted cladding layer exhibits significant passivation behavior in 3.5 wt% NaCl solution. It may be that the surface roughness reduction and grain refinement caused by ultrasonic assistance can improve the integrity and compactness of the cladding layer, so the dynamic equilibrium process of the dissolution and reformation of the passive film is changed, which can improve the corrosion resistance of the surface. There are some equiaxed grains in the columnar-grains area of the ultrasonic-assisted cladding layer, mainly because the inside of some primary columnar grains has gone through a process of lattice distortion → dislocation multiplication → substructure rotation → formation of small-angle grain boundary → misorientation accumulation → formation of new grains in the process of ultrasonic-assisted laser cladding of 316L stainless steel.
•Effect of ultrasonic vibration on 316 L cladding layer is described.•Action mechanism of ultrasonic vibration on 316 L cladding layer is explained.•Formation mechanism of equiaxed grains in the columnar-grains area is proposed.
Calcium imaging with protein-based indicators
is widely used to follow neural activity in intact nervous systems, but current protein sensors report neural activity at timescales much slower than ...electrical signalling and are limited by trade-offs between sensitivity and kinetics. Here we used large-scale screening and structure-guided mutagenesis to develop and optimize several fast and sensitive GCaMP-type indicators
. The resulting 'jGCaMP8' sensors, based on the calcium-binding protein calmodulin and a fragment of endothelial nitric oxide synthase, have ultra-fast kinetics (half-rise times of 2 ms) and the highest sensitivity for neural activity reported for a protein-based calcium sensor. jGCaMP8 sensors will allow tracking of large populations of neurons on timescales relevant to neural computation.
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