Twenty‐three published proxy temperature series over China spanning the last 2000 years were selected for an uncertainty analysis in five climate regions. Results indicated that, although large ...uncertainties are found for the period prior to the 16th century, high level of consistency were identified in all regions during the recent 500‐years, highlighted by the two cold periods 1620s–1710s and 1800s–1860s, and the warming during the 20th century. The latter started in Tibet, Northwest and Northeast, and migrated to Central East and Southeast. The analysis also indicates that the warming during the 10–14th centuries in some regions might be comparable in magnitude to the warming of the last few decades of the 20th century which was unprecedented within the past 500 years.
A remarkable manifestation of the quantum character of electrons in matter is offered by graphene, a single atomic layer of graphite. Unlike conventional solids where electrons are described with the ...Schrödinger equation, electronic excitations in graphene are governed by the Dirac hamiltonian. Some of the intriguing electronic properties of graphene, such as massless Dirac quasiparticles with linear energy-momentum dispersion, have been confirmed by recent observations. Here, we report an infrared spectromicroscopy study of charge dynamics in graphene integrated in gated devices. Our measurements verify the expected characteristics of graphene and, owing to the previously unattainable accuracy of infrared experiments, also uncover significant departures of the quasiparticle dynamics from predictions made for Dirac fermions in idealized, free-standing graphene. Several observations reported here indicate the relevance of many-body interactions to the electromagnetic response of graphene.
A solar cell based on the n-MoS
2
/i-SiO
2
/p-Si heterojunction is fabricated. The device exhibits a high power-conversion efficiency of 4.5% due to the incorporation of a nano-scale SiO
2
buffer ...into the MoS
2
/Si interface. The present device architectures are envisaged as potentially valuable candidates for high-performance photovoltaic devices.
A solar cell based on the n-MoS
2
/i-SiO
2
/p-Si heterojunction is fabricated.
We use principal component regression and partial least squares regression to separately reconstruct a composite series of temperature variations in China, and associated uncertainties, at a decadal ...resolution over the past 2000 yr. The reconstruction is developed using proxy temperature data with relatively high confidence levels from five regions across China, and using a temperature series from observations by the Chinese Meteorological Administration, covering the period from 1871 to 2000. Relative to the 1851–1950 climatology, our two reconstructions show four warm intervals during AD 1–AD 200, AD 551–AD 760, AD 951–AD 1320, and after AD 1921, and four cold intervals during AD 201–AD 350, AD 441–AD 530, AD 781–AD 950, and AD 1321–AD 1920. The temperatures during AD 981–AD 1100 and AD 1201–AD 1270 are comparable to those of the Present Warm Period, but have an uncertainty of ±0.28 °C to ±0.42 °C at the 95% confidence interval. Temperature variations over China are typically in phase with those of the Northern Hemisphere (NH) after 1000, a period which covers the Medieval Climate Anomaly, the Little Ice Age, and the Present Warm Period. In contrast, a warm period in China during AD 541–AD 740 is not obviously seen in the NH.
A monitoring program for particulate matter pollution was designed and implemented in six Asian cities/metropolitan regions including Bandung, Bangkok, Beijing, Chennai, Manila, and Hanoi, within the ...framework of the Asian regional air pollution research network (AIRPET), coordinated by the Asian Institute of Technology. As uniform the methodologies as possible were intended with an established QA/QC procedure in order to produce reliable and comparable data by the network. The monsoon effects and seasonal changes in the sources/activities require long-term monitoring to understand the nature of air pollution in the cities. During phase 1 (2001–2004) of the AIRPET around 3000 fine and coarse particulate matter samples were collected from characteristic urban sites, which provide insight into temporal and spatial variations of PM in the cities. In all six cities, the levels of PM
10 and PM
2.5 were found high, especially during the dry season, which frequently exceeded the corresponding 24
h US EPA standards at a number of sites. The average concentrations of PM
2.5 and PM
10 in the cities ranged, respectively, 44–168 and 54–262
μg
m
−3 in the dry season, and 18–104 and 33–180
μg
m
−3 in the wet season. Spatial and temporal distribution of PM in each city, the ratios of PM
2.5 to PM
10, and the reconstructed mass were presented which provide useful information on possible PM sources in the cities. The findings help to understand the nature of particulate matter air pollution problems in the selected cities/metropolitan regions.
Synthetic streamflows at different sites in a river basin are needed for planning, operation, and management of water resources projects. Modeling the temporal and spatial dependence structure of ...monthly streamflow at different sites is generally required. In this study, the maximum entropy copula method is proposed for multisite monthly streamflow simulation, in which the temporal and spatial dependence structure is imposed as constraints to derive the maximum entropy copula. The monthly streamflows at different sites are then generated by sampling from the conditional distribution. A case study for the generation of monthly streamflow at three sites in the Colorado River basin illustrates the application of the proposed method. Simulated streamflow from the maximum entropy copula is in satisfactory agreement with observed streamflow.
Key Points
Development of the copula with maximum entropy
Proposal of the maximum entropy copula for streamflow simulation
Modeling of the temporal and spatial dependence structure
Lattice structures have advantages such as energy absorption and heat transfer; however, they can often suffer failure because of stress distribution and lack of stiffness. A ...spherical-node-body-centred-cubic (SNBCC) structure was developed to reduce the stress concentration and improve the stiffness. The relative density, surface area, and equivalent modulus of the SNBCC structure were studied, and a method to select suitable parameters was developed. The results showed that the prediction errors of the theoretical relative density and surface area were both <1.00% compared with that of the CAD model. The theoretical modulus's prediction error was approximately 10.00% compared with that of the finite element analysis. Compared with the BCC structure, the relative density of the SNBCC structure only increased from 1.00% to 7.00%, the stress concentration reduced from 10.00% to 30.00%, and the stiffness increased from 5.00% to 58.10%, when the ratio of the strut diameter to the unit cell length was within 0.02–0.10. The projection approach for the lattice structure's multi-property design was applied. If a solid material's modulus is 200.00 GPa, the design range of the relative density and the equivalent modulus can be within 0.0021–0.1197 and 0.10 MPa–1.00 GPa respectively.
Display omitted
•The SNBCC structure is developed to reduce the stress concentration and reinforce the BCC structure.•The maximum stress can be reduced by 10% to 30%, the stiffness can be improved by 5.00% to 58.10%.•The joint sphere don’t have remarkable effect on the relative density and the surface area.•A projection approach for the multi-property design was developed to select suitable structure parameters.
The human brain can be characterized as functional networks. Therefore, it is important to subdivide the brain appropriately in order to construct reliable networks. Resting-state functional ...connectivity-based parcellation is a commonly used technique to fulfill this goal. Here we propose a novel individual subject-level parcellation approach based on whole-brain resting-state functional magnetic resonance imaging (fMRI) data. We first used a supervoxel method known as simple linear iterative clustering directly on resting-state fMRI time series to generate supervoxels, and then combined similar supervoxels to generate clusters using a clustering method known as graph-without-cut (GWC). The GWC approach incorporates spatial information and multiple features of the supervoxels by energy minimization, simultaneously yielding an optimal graph and brain parcellation. Meanwhile, it theoretically guarantees that the actual cluster number is exactly equal to the initialized cluster number. By comparing the results of the GWC approach and those of the random GWC approach, we demonstrated that GWC does not rely heavily on spatial structures, thus avoiding the challenges encountered in some previous whole-brain parcellation approaches. In addition, by comparing the GWC approach to two competing approaches, we showed that GWC achieved better parcellation performances in terms of different evaluation metrics. The proposed approach can be used to generate individualized brain atlases for applications related to cognition, development, aging, disease, personalized medicine, etc. The major source codes of this study have been made publicly available at https://github.com/yuzhounh/GWC.
Abstract
Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered ...kagome material ScV
6
Sn
6
does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe an enhancement of the internal field width sensed by the muon ensemble, which takes place within the charge ordered state. More importantly, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. Taken together with the hidden magnetism found in
A
V
3
Sb
5
(
A
= K, Rb, Cs) and FeGe kagome systems, our results suggest ubiqitous time-reversal symmetry-breaking in charge ordered kagome lattices.
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