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The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite has been widely used in climate and environment studies to obtain the vertical profiles of atmospheric aerosols. To retrieve the vertical profile of aerosol extinction, the CALIOP algorithm assumes column-averaged lidar ratios based on a clustering of aerosol optical properties measured at surface stations. On one hand, these lidar ratio assumptions may not be appropriate or representative at certain locations. One the other hand, the two-wavelength design of CALIOP has the potential to constrain aerosol size information, which has not been considered in the operational algorithm. In this study, we present a modified inversion algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using two-wavelength elastic lidars such as CALIOP. Specifically, a lookup table is built to relate the lidar ratio with the Ångström exponent calculated using aerosol extinction at the two wavelengths, and the lidar ratio is then determined iteratively without a priori assumptions. The retrieved two-wavelength extinction at each layer is then converted to the particle effective radius assuming a lognormal distribution. The algorithm is tested on synthetic data, Raman lidar measurements and then finally the real CALIOP backscatter measurements. Results show improvements over the CALIPSO operational algorithm by comparing with ground-based Raman lidar profiles.

Light propagation in Photonic integrated circuits (PICs), which can nowadays involve complex systems of light-guiding structures, is measured with different approaches(Nuzhdin et al., 2020, Lončar et al., 2002, Hopman et al., 2007, Morichetti et al., 2014, Sapienza et al., 2012, Vesseur et al., 2007). An interferometric polarization-sensitive measurement of the evanescent fields of these structures provides insight in the performance of the circuit detects possible malfunction with sub-wavelength precision(Engelen et al., 2007, Gersen et al., 2005, Barwick et al., 2009). We demonstrate a Near-field scanning optical microscopy (NSOM) measurement on coupled ring resonators that shows how the guided modes evolve as they propagate across the optical chip. Analysis of the measurements provides information about intensity distribution of the two polarization components (TE and TM) and their spatial confinement. The data validates our methodology and opens new possibilities for analysis of signal propagation in prototyping and optimization of integrated optical systems. Direct observation of polarization state of the guided modes allows for clear understanding of mode conversion in coupling systems.

Spectropolarimetric results of Fraunhofer lines between 516.3 and 532.6 nm are presented in local upper solar chromosphere and inner corona below a height of about 0.04 solar radius above the solar limb. The data were acquired on 2013 November 3 during a total solar eclipse in Gabon by the prototype Fiber Arrayed Solar Optical Telescope. It is found that the linear polarizations of the Fraunhofer lines in these layers depend strongly on specific spectral lines and positions. A Fraunhofer line at Mg i b _1 518.4 nm can have a polarization amplitude up to 0.36% with respect to the continuum polarization level, while polarizations of lines like Fe i /Cr i 524.7 nm are often merged in the noise level of 6.0 × 10 ^−4 . The polarizations of the Fraunhofer lines, like the emission ones and the continuum, increase with height as a whole trend, and their amplitudes can be close to those of emission ones yielded in close positions, and generally larger than those of the continuum. Rotations of the polarization directions of the Fraunhofer lines are often accompanied by variations in their polarization amplitudes and profile shapes. It is also judged from these polarimetric properties, along with other evidence, that neutral metal atoms exist in these atmospheric layers.

High levels of fine particulate matter (PM2.5) pollution in East Asia often exceed local air quality standards. Observations from the Korea–United States Air Quality (KORUS-AQ) field campaign in May and June 2016 showed that development of extreme pollution (haze) occurred through a combination of long-range transport and favorable meteorological conditions that enhanced local production of PM2.5. Atmospheric models often have difficulty simulating PM2.5 chemical composition during haze, which is of concern for the development of successful control measures. We use observations from KORUS-AQ to examine the ability of the GEOS-Chem chemical transport model to simulate PM2.5 composition throughout the campaign and identify the mechanisms driving the pollution event. At the surface, the model underestimates sulfate by −64 % but overestimates nitrate by +36 %. The largest underestimate in sulfate occurs during the pollution event, for which models typically struggle to generate elevated sulfate concentrations due to missing heterogeneous chemistry in aerosol liquid water in the polluted boundary layer. Hourly surface observations show that the model nitrate bias is driven by an overestimation of the nighttime peak. In the model, nitrate formation is limited by the supply of nitric acid, which is biased by +100 % against aircraft observations. We hypothesize that this is due to a large missing sink, which we implement here as a factor of 5 increase in dry deposition. We show that the resulting increased deposition velocity is consistent with observations of total nitrate as a function of photochemical age. The model does not account for factors such as the urban heat island effect or the heterogeneity of the built-up urban landscape, resulting in insufficient model turbulence and surface area over the study area that likely results in insufficient dry deposition. Other species such as NH3 could be similarly affected but were not measured during the campaign. Nighttime production of nitrate is driven by NO2 hydrolysis in the model, while observations show that unexpectedly elevated nighttime ozone (not present in the model) should result in N2O5 hydrolysis as the primary pathway. The model is unable to represent nighttime ozone due to an overly rapid collapse of the afternoon mixed layer and excessive titration by NO. We attribute this to missing nighttime heating driving deeper nocturnal mixing that would be expected to occur in a city like Seoul. This urban heating is not considered in air quality models run at large enough scales to treat both local chemistry and long-range transport. Key model failures in simulating nitrate, mainly overestimated daytime nitric acid, incorrect representation of nighttime chemistry, and an overly shallow and insufficiently turbulent nighttime mixed layer, exacerbate the model's inability to simulate the buildup of PM2.5 during haze pollution. To address the underestimate in sulfate most evident during the haze event, heterogeneous aerosol uptake of SO2 is added to the model, which previously only considered aqueous production of sulfate from SO2 in cloud water. Implementing a simple parameterization of this chemistry improves the model abundance of sulfate but degrades the SO2 simulation, implying that emissions are underestimated. We find that improving model simulations of sulfate has direct relevance to determining local vs. transboundary contributions to PM2.5. During the haze pollution event, the inclusion of heterogeneous aerosol uptake of SO2 decreases the fraction of PM2.5 attributable to long-range transport from 66 % to 54 %. Locally produced sulfate increased from 1 % to 25 % of locally produced PM2.5, implying that local emissions controls could have a larger effect than previously thought. However, this additional uptake of SO2 is coupled to the model nitrate prediction, which affects the aerosol liquid water abundance and chemistry driving sulfate–nitrate–ammonium partitioning. An additional simulation of the haze pollution with heterogeneous uptake of SO2 to aerosol and simple improvements to the model nitrate simulation results in 30 % less sulfate due to 40 % less nitrate and aerosol water, and this results in an underestimate of sulfate during the haze event. Future studies need to better consider the impact of model physical processes such as dry deposition and nighttime boundary layer mixing on the simulation of nitrate and the effect of improved nitrate simulations on the overall simulation of secondary inorganic aerosol (sulfate + nitrate + ammonium) in East Asia. Foreign emissions are rapidly changing, increasing the need to understand the impact of local emissions on PM2.5 in South Korea to ensure continued air quality improvements.

The wave propagation and power deposition inside and outside the blue-core helicon plasma are computed, together with their transitional behaviours prior to and after the blue-core formation. Computations refer to the experiments on the CSDX (controlled shear decorrelation experiment) (Thakur et al., Plasma Sources Science and Technology 23: 044,006, 2014 and Thakur et al., IEEE Transactions on Plasma Science 43: 2754–2759, 2015). It is found that the radial profile of wave electric field peaks off-axis during the blue-core formation, and the location of this peak is very close to that of particle transport barrier observed in experiment; the radial profile of wave magnetic field shows multiple radial modes inside the blue-core column, which is consistent with the experimental observation of coherent high m modes through Bessel function. The axial profiles of wave field indicate that the decay length shortens for increased external field strength, especially when the blue-core mode has been achieved, and this length is relatively longer inside the core than that outside. The wave energy density is overall lower in two orders after blue-core formation than that prior to, and the energy distribution shows a periodic boundary layer near the edge of blue-core column. The dispersion relation inside the blue-core column suggests the presence of two radial modes, while outside the blue-core column it shows no variation, i.e. constant wave number with changed frequency. The power deposition appears to be off-axis in the radial direction, forming a hollow profile, and when the blue-core mode has been formed it shows periodic structure in the axial direction. Analyses based on the step-like function theory and introduced blue-core constant provide consistent results and more physics understanding. These details of wave propagation and power deposition during the blue-core formation are presented for the first time, and helpful for understanding the mechanism of blue-core phenomenon. The equivalence of blue-core plasma column to optical fiber for electromagnetic communication is also explored, and preliminary calculation shows that total reflection can indeed occur if the incident angle is larger than a threshold value. This may inspire a novel application of helicon plasma, and is one of the most interesting findings of present work.

Aluminum gallium arsenide-on-insulator (AlGaAsOI) exhibits large χ2 and χ3 optical nonlinearities, a wide tunable bandgap, low waveguide propagation loss, and a large thermo-optic coefficient, making it an exciting platform for integrated quantum photonics. With ultrabright sources of quantum light established in AlGaAsOI, the next step is to develop the critical building blocks for chip-scale quantum photonic circuits. Here we expand the quantum photonic toolbox for AlGaAsOI by demonstrating edge couplers, 3 dB splitters, tunable interferometers, and waveguide crossings with performance comparable to or exceeding silicon and silicon-nitride quantum photonic platforms. As a demonstration, we de-multiplex photonic qubits through an unbalanced interferometer, paving the route toward ultra-efficient and high-rate chip-scale demonstrations of photonic quantum computation and information applications.

Land subsidence caused by groundwater overpumping threatens the sustainable development in Beijing. Hazard assessments of land subsidence can provide early warning information to improve prevention measures. However, uncertainty and fuzziness are the major issues during hazard assessments of land subsidence. We propose a method that integrates fuzzy set theory and weighted Bayesian model (FWBM) to evaluate the hazard probability of land subsidence measured by Interferometric Synthetic Aperture Radar (InSAR) technology. The model is structured as a directed acyclic graph. The hazard probability distribution of each factor triggering land subsidence is determined using Bayes' theorem. Fuzzification of the factor significance reduces the ambiguity of the relationship between the factors and subsidence. The probability of land subsidence hazard under multiple factors is then calculated with the FWBM. The subsidence time series obtained by InSAR is used to infer the updated posterior probability. The upper and middle parts of the Chaobai River alluvial fan are taken as a case-study site, which locates the first large-scale emergency groundwater resource region in the Beijing plain. The results show that rates of groundwater level decrease more than 1 m yr−1 in the confined and unconfined aquifers, with cumulative thicknesses of the compressible sediments between 160 and 170 m and Quaternary thicknesses between 400 and 500 m, yielding maximum hazard probabilities of 0.65, 0.68, 0.32, and 0.35, respectively. The overall hazard probability of land subsidence in the study area decreased from 51.3 % to 28.3 % between 2003 and 2017 due to lower rates of groundwater level decrease. This study provides useful insights for decision makers to select different approaches for land subsidence prevention.

Long-term (10 years) application of conservation tillage following conversion from conventional tillage (CT) can achieve a new equilibrium in the soil environment, which is vital to reverse soil biodiversity declines and fulfil the goal of maintaining agroecosystem sustainability. However, in such a situation, how the soil community regulates nutrient cycling impacting crop yield is not well documented. Therefore, the relations between mineralized nitrogen (N) delivered by soil food web and soybean (Glycine max Merr.) yield were investigated after 14 years application of CT, reduced tillage (RT) and no tillage (NT) in a black soil (Typic Hapludoll) of Northeast China. We hypothesized that soil mineralizable N would increase with the complexity of the soil food web, and that the trophic groups involved in associating N mineralization with crop yield will vary with soil depth in the conservation tillage practice. During the soybean growing season, soil organisms, including bacteria, fungi, nematodes, mites and collembolans, were extracted and identified monthly from 0–5 and 5–15 cm soil depths to estimate the complexity of the food web indicated by the species richness and connectance indices, and to simulate the mineralized N using energetic food web modelling. The species richness and connectance of the food web at both soil depths were significantly affected by tillage practices, and their values decreased of the order of NT > RT > CT. A similar trend was also revealed for the simulated N mineralization, that is, the mineralized N released either from the functional feeding guilds or from the energy pathways of the food web were greater in RT and NT than in CT at both soil depths. Multiple linear regression analysis showed that soil organisms involved in coupling the mineralized N with soybean yield were different at different soil depths, in which fungal and root pathways at 0–5 cm and bacterial pathway at 5–15 cm were the driving factors for the supply of mineralized N to soybean in NT and RT soils. These results support our hypothesis and highlight the essential role of soil food web complexity in coupling N mineralization and crop yield after long-term application of conservation tillage. Additionally, the current modelling work provides basic hypotheses for future studies to test the impact of soil biodiversity or specific functional guilds on the fate of N in agro-ecosystems.

This study investigates the use of Advanced Land Observing Satellite 2 (ALOS-2) equipped with an enhanced L-band SAR sensor imagery alongside with Landsat-8 optical sensor in detection and mapping of burnt and unburnt scars occurring after a bushfire in Victoria, Australia. The bushfires had recently occurred in the period of 2018–2019. The analysis was explored using a contextual classifier Support Vector Machine (SVM), as SVM allows us to integrate spectral information and spatial context through the optimal smoothing parameter without degrading image quality. The training and test set datasets consisting of burnt and unburnt pixels were created from Landsat-8 scenes used as reference data. The backscatter intensity maps (acquired before and after the forest fires) from ALOS-2 data were compared and investigated, with a special concern on topographic influence removal. The dual polarizations (HH and HV) have been used to improve the forest fire mapping capability. These change detection techniques were based on image feature differences, index calculation such as normalized burn ratio. The burnt area and unburnt area were then classified via a threshold given by the pre- and post- disaster differences. The classification result achieved an accuracy of 80% Landsat-8 and 89% ALOS-2. This result shows the limitations of burnt area mapping with ALOS-2 due to effect local incidence angle and topography were of greater impact resulting in shadows. Nevertheless, the results in both areas verify the use of satellite SAR sensors and optical in forestry application.

Abstract Beginning with results for the leading-twist two-particle distribution amplitudes of $$\pi $$ π - and K-mesons, each of which exhibits dilation driven by the mechanism responsible for the emergence of hadronic mass, we develop parameter-free predictions for the pointwise behaviour of all $$\pi $$ π and K distribution functions (DFs), including glue and sea. The large-x behaviour of each DF meets expectations based on quantum chromodynamics; the valence-quark distributions match extractions from available data, including the pion case when threshold resummation effects are included; and at $$\zeta _5=5.2\,$$ ζ 5 = 5.2 GeV, the scale of existing measurements, the light-front momentum of these hadrons is shared as follows: $$\langle x_{\mathrm{valence}} \rangle ^\pi = 0.41(4)$$ ⟨ x valence ⟩ π = 0.41 ( 4 ) , $$\langle x_{\mathrm{glue}} \rangle ^\pi = 0.45(2)$$ ⟨ x glue ⟩ π = 0.45 ( 2 ) , $$\langle x_{\mathrm{sea}} \rangle ^\pi = 0.14(2)$$ ⟨ x sea ⟩ π = 0.14 ( 2 ) ; and $$\langle x_{\mathrm{valence}} \rangle ^K = 0.42(3)$$ ⟨ x valence ⟩ K = 0.42 ( 3 ) , $$\langle x_{\mathrm{glue}} \rangle ^K = 0.44(2)$$ ⟨ x glue ⟩ K = 0.44 ( 2 ) , $$\langle x_{\mathrm{sea}} \rangle ^K = 0.14(2)$$ ⟨ x sea ⟩ K = 0.14 ( 2 ) . The kaon’s glue and sea distributions are similar to those in the pion, although the inclusion of mass-dependent splitting functions introduces some differences on the valence-quark domain. This study should stimulate improved analyses of existing data and motivate new experiments sensitive to all $$\pi $$ π and K DFs. With little known empirically about the structure of the Standard Model’s (pseudo-) Nambu-Goldstone modes and analyses of existing, limited data being controversial, it is likely that new generation experiments at upgraded and anticipated facilities will provide the information needed to resolve the puzzles and complete the picture of these complex bound states.

High-Asia glaciers have been observed to be retreating the fastest in the southeastern Tibet Plateau (SETP), where vast numbers of glaciers and amounts of snow feed the streamflow of the Brahmaputra, a transboundary river linking the world's two most populous countries, China and India. However, the low temporal resolutions in previous observations of glacier and snow (GS) mass balance obscured the seasonal accumulation–ablation variations, and their modelling estimates were divergent. Here we use monthly satellite gravimetry observations from August 2002 to June 2017 to estimate GS mass variation in the SETP. We find that the “spring-accumulation-type” glaciers and snow in the SETP reach their maximum in May. This is in stark contrast to seasonal variations in terrestrial water storage, which is controlled by summer precipitation and reaches the maximum in August. These two seasonal variations are mutually orthogonal and can be easily separated in time-variable gravity observations. Our GS mass balance results show a long-term trend of -6.5±0.8 Gt yr−1 (or 0.67±0.08 m w.e. yr−1) and annual mass decreases ranging from −49.3 to −78.3 Gt with an average of -64.5±8.9 Gt in the SETP between August 2002 and June 2017. The contribution of summer meltwater to the Brahmaputra streamflow is estimated to be 51±9 Gt. This result could help to resolve previous divergent modelling estimates and underlines the importance of meltwater to the Brahmaputra streamflow. The high sensitivity between GS melting and temperature on both annual and monthly scales suggests that the Brahmaputra will suffer from not only changes in total annual discharge but also an earlier runoff peak due to ongoing global warming.

The Korean Geostationary Ocean Color Imager (GOCI) satellite has monitored the East Asian region in high temporal (e.g., hourly) and spatial resolution (e.g., 6 km) every day for the last decade, providing unprecedented information on air pollutants over the upstream region of the Korean Peninsula. In this study, the GOCI aerosol optical depth (AOD), retrieved at the 550 nm wavelength, is assimilated to enhance the quality of the aerosol analysis, thereby making systematic improvements to air quality forecasting over South Korea. For successful data assimilation, GOCI retrievals are carefully investigated and processed based on data characteristics such as temporal and spatial distribution. The preprocessed data are then assimilated in the three-dimensional variational data assimilation (3D-Var) technique for the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). For the Korea–United States Air Quality (KORUS-AQ) period (May 2016), the impact of GOCI AOD on the accuracy of surface PM2.5 prediction is examined by comparing with effects of other observations including Moderate Resolution Imaging Spectroradiometer (MODIS) sensors and surface PM2.5 observations. Consistent with previous studies, the assimilation of surface PM2.5 measurements alone still underestimates surface PM2.5 concentrations in the following forecasts, and the forecast improvements last only for about 6 h. When GOCI AOD retrievals are assimilated with surface PM2.5 observations, however, the negative bias is diminished and forecast skills are improved up to 24 h, with the most significant contributions to the prediction of heavy pollution events over South Korea.

Asymmetric responses of aboveground net primary productivity (ANPP) to precipitation were identified as a signal to predict ecosystem state shifts at temperate grassland zones in Inner Mongolia, China. However, mechanism studies were still lacking. This study hypothesized that the enhanced growth and newly emerged herbaceous after increased precipitation resulted in the highest asymmetry at the transition zone between desert and typical steppe. We monitored the responses of the normalized difference vegetation index (NDVI) of different species to precipitation events using un-manned aerial vehicle technology to test this hypothesis. NDVI and species richness were measured twice at fixed points in July and August with a time interval of 15 days. Results showed that: (1) From July to August, NDVI in the transition zone increased significantly after precipitation (P < 0.05), but NDVI in both the desert and typical steppe showed a non-significant change (P > 0.05). (2) In the transition zone, NDVI increases from the shrub and herbaceous contributed to 37 and 63% increases of the site NDVI, respectively. (3) There was a significant difference in species richness between July and August in the transition zone (P < 0.05), mainly caused by the herbaceous (Chenopodiaceae, Composite, Convolvulaceae, Gramineae, Leguminosae, and Liliaceae), which either emerged from soil or tillers growth from surviving plants. This study demonstrated that herbaceous dominant the changes of NDVI in the transition zone, which provides a scientific basis for the mechanism studies of ANPP asymmetric response to precipitation and warrants long-term measurements.

Summary Background Neuroimaging studies have identified obesity‐related differences in the brain's resting state activity. An imbalance between homeostatic and reward aspects of ingestive behaviour may contribute to obesity and food addiction. The interactions between early life adversity (ELA), the reward network and food addiction were investigated to identify obesity and sex‐related differences, which may drive obesity and food addiction. Methods Functional resting state magnetic resonance imaging was acquired in 186 participants (high body mass index [BMI]: ≥25: 53 women and 54 men; normal BMI: 18.50–24.99: 49 women and 30 men). Participants completed questionnaires to assess ELA (Early Traumatic Inventory) and food addiction (Yale Food Addiction Scale). A tripartite network analysis based on graph theory was used to investigate the interaction between ELA, brain connectivity and food addiction. Interactions were determined by computing Spearman rank correlations, thresholded at q

Pion and kaon structural properties provide insights into the emergence of mass within the Standard Model and attendant modulations by the Higgs boson. Novel expressions of these effects, in impact parameter space and in mass and pressure profiles, are exposed via π and K generalised parton distributions, built using the overlap representation from light-front wave functions constrained by one-dimensional valence distribution functions that describe available data. Notably, e.g. K pressure profiles are spatially more compact than π profiles and both achieve near-core pressures of similar magnitude to that found in neutron stars.

The definition of a magnetic shuttle is introduced to describe the magnetic space enclosed by two magnetic mirrors with the same field direction and high mirror ratio. Helicon plasma immersed in such a magnetic shuttle (mirror ratio 5) that can provide the confinement of charged particles is modeled using an electromagnetic solver. The perpendicular structure of the wave field along this shuttle is given in terms of stream vector plots, showing a significant change from midplane to ending throats, and the vector field rotates and forms a circular layer that separates the plasma column radially into core and edge regions near the throats. The influences of the driving frequency (f = 6.78 MHz–40.68 MHz), plasma density (nemax = 1016 m−3 to 1019 m−3), and field strength (B0max = 0.017 T–1.7 T) on the wave field structure and power absorption are computed in detail. It is found that the wave energy and power absorption decrease for increased driving frequency and reduced field strength and increase significantly when the plasma density is above a certain value. The axial standing-wave feature always exists, due to the interference between forward and reflected waves from ending magnetic mirrors. Distributions of wave energy density and power absorption density all show a shrinking feature from midplane to ending throats, which is consistent with the nature of the helicon mode that propagates along field lines. Theoretical analysis based on a simple magnetic shuttle and the governing equation of helicon waves shows consistency with computed results and previous studies. This hypothetical work is a valuable to guide the helicon physics prototype experiment, which is designed for the fundamental wave–particle interaction study in helicon plasma, to achieve high plasma density and energy absorption efficiency.

Severe ozone (O3) pollution episodes plague a few regions in eastern China at certain times of the year, e.g., the Yangtze River Delta (YRD). However, the formation mechanisms, including meteorological factors, contributing to these severe pollution events remain elusive. A severe summer smog stretched over the YRD region from 22 to 25 August 2016. This event displayed hourly surface O3 concentrations that exceeded 300 µg m−3 on 25 August in Nanjing, an urban area in the western YRD. The weather pattern during this period was characterized by near-surface prevailing easterly winds and continuous high air temperatures. The formation mechanism responsible for this O3 pollution episode over the YRD region, particularly the extreme values over the western YRD, was investigated using observation data and by running simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem). The results showed that the extremely high surface O3 concentration in the western YRD area on 25 August was largely due to regional O3 transport in the nocturnal residual layer (RL) and the diurnal change in the atmospheric boundary layer. On 24 August, high O3 levels, with peak values of 220 µg m−3, occurred in the daytime mixing layer over the eastern YRD region. During nighttime from 24 to 25 August, a shallow stable boundary layer formed near the surface which decoupled the RL above it from the surface. Ozone in the decoupled RL remained quite constant, which resulted in an O3-rich reservoir forming in this layer. This reservoir persisted due to the absence of O3 consumption from nitrogen oxide (NO) titration or dry deposition during nighttime. The prevailing easterly winds in the lower troposphere governed the regional transport of this O3-rich air mass in the nocturnal RL from the eastern to the western YRD. As the regional O3 transport reached the RL over the western YRD, O3 concentrations in the RL accumulated and rose to 200 µg m−3 over the western Nanjing site during the sunrise hours on 25 August. The development of the daytime convective boundary layer after sunrise resulted in the disappearance of the RL, as the vertical mixing in the convective boundary layer uniformly redistributed O3 from the upper levels via the entrainment of O3-rich RL air down to the O3-poor air at the ground. This net downward transport flux reached up to 35 µg m−3 h−1, and contributed a considerable surface O3 accumulation, resulting in severe daytime O3 pollution during the summer smog event on 25 August in the western YRD region. The mechanism of regional O3 transport through the nocturnal RL revealed in this study has great implications regarding understanding O3 pollution and air quality change.

The black carbon (BC) deposition on the ice core at Muztagh Ata Mountain, northern Tibetan Plateau, was analyzed. Two sets of measurements were used in this study, which included the air samplings of BC particles during 2004–2006 and the ice core drillings of BC deposition during 1986–1994. Two numerical models were used to analyze the measured data. A global chemical transportation model (MOZART-4) was used to analyze the BC transport from the source regions, and a radiative transfer model (SNICAR) was used to study the effect of BC on snow albedo. The results show that during 1991–1992, there was a strong spike in the BC deposition at Muztagh Ata, suggesting that there was an unusual emission in the upward region during this period. This high peak of BC deposition was investigated by using the global chemical transportation model (MOZART-4). The analysis indicated that the emissions from large Kuwait fires at the end of the first Gulf War in 1991 caused this high peak of the BC concentrations and deposition (about 3–4 times higher than other years) at Muztagh Ata Mountain, suggesting that the upward BC emissions had important impacts on this remote site located on the northern Tibetan Plateau. Thus, there is a need to quantitatively estimate the effect of surrounding emissions on the BC concentrations on the northern Tibetan Plateau. In this study, a sensitivity study with four individual BC emission regions (Central Asia, Europe, the Persian Gulf, and South Asia) was conducted by using the MOZART-4 model. The result suggests that during the normal period (non-Kuwait fires), the largest effect was due to the Central Asia source (44 %) during the Indian monsoon period, while during the non-monsoon period, the largest effect was due to the South Asia source (34 %). The increase in radiative forcing increase (RFI) due to the deposition of BC on snow was estimated by using the radiative transfer model (SNICAR). The results show that under the fresh snow assumption, the estimated increase in RFI ranged from 0.2 to 2.5 W m−2, while under the aged snow assumption, the estimated increase in RFI ranged from 0.9 to 5.7 W m−2. During the Kuwait fires period, the RFI values increased about 2–5 times higher than in the normal period, suggesting a significant increase for the snow melting on the northern Tibetan Plateau due to this fire event. This result suggests that the variability of BC deposition at Muztagh Ata Mountain provides useful information to study the effect of the upward BC emissions on environmental and climate issues in the northern Tibetan Plateau. The radiative effect of BC deposition on the snow melting provides important information regarding the water resources in the region.

A two-fluid flowing plasma model is applied to describe the plasma rotation and resulted instability evolution in magnetically enhanced vacuum arc thruster (MEVAT). Typical experimental parameters are employed, including plasma density, equilibrium magnetic field, ion and electron temperatures, cathode materials, axial streaming velocity, and azimuthal rotation frequency. It is found that the growth rate of plasma instability increases with growing rotation frequency and field strength, and with descending electron temperature and atomic weight, for which the underlying physics are explained. The radial structure of density fluctuation is compared with that of equilibrium density gradient, and the radial locations of their peak magnitudes are very close, implying that the mode may be driven by density gradient. Temporal evolution of perturbed mass flow in the cross section of plasma column is also presented, which behaves in the form of clockwise rotation (direction of electron diamagnetic drift) at edge and anti-clockwise rotation (direction of ion diamagnetic drift) in the core, separated by a mode transition layer from n = 0 to n = 1. This work, to our best knowledge, is the first treatment of plasma instability caused by rotation and axial flow in MEVAT, and is also of great practical interest for other electric thrusters where rotating plasma is concerned for long-time stable operation and propulsion efficiency optimization.

In order to learn effectively from measurements of generalised parton distributions (GPDs), it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL) truncation of QCD's Dyson–Schwinger equations and exemplified via the pion's valence dressed-quark GPD, Hπv(x,ξ,t). Our analysis focuses primarily on ξ=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hπv(x,ξ=±1,t) with the pion's valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to define the pion's valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hπv(x,0,t), expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hπv(x,0,t) and the associated impact-parameter dependent distribution, qπv(x,|b→⊥|), which provide a qualitatively sound picture of the pion's dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ζ=2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods. Keywords: Deeply virtual Compton scattering, Dynamical chiral symmetry breaking, Dyson–Schwinger equations, Generalised parton distribution functions, π-meson

The near band edge emission of the tensile-strained m-plane ZnO film grown on (112)LaAlO3 substrates shows abnormal low polarization degree (ρ = 0.1). The temperature dependency of polarization degree clarifies the origins of different emission peaks. In tensile-strained m-plane ZnO, the [0001] polarized state is upper shifted and is overlapping with the [112̅0] polarized state. This phenomenon causes the abnormal low polarization degree and reveals the effect of strain on the emission anisotropy of m-plane ZnO.

Due to rapid population growth, China, and urbanization, the Dongwan catchment, with a drainage area of 2856 km2 and located in Henan Province, has been subjected to considerable land-use changes since the 1990s. Distributed or semi-distributed models have been widely used in catchment hydrological modeling, along with the rapid development of computer and GIS technologies. The objective of this study is to assess the impact of underlying surface change on catchment hydrological response using the Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS), which is a distributed hydrological model. Specifically, 21 flood events were selected for calibrating and validating the model parameters. The satisfactory results show that the HEC-HMS model can be used to simulate the rainfall–runoff response in the Dongwan catchment. In light of the analyses of simulation results, it is shown that the flood peaks and runoff yields after 1990 moderately decrease in comparison with that before 1990 at the same precipitation level. It is also indicated that the underlying surface change leads to the increased flood storage capacity after 1990 in this region.

Period2 is a core circadian gene, which not only maintains the circadian rhythm of cells but also regulates some organic functions. We investigated the effects of mPeriod2 (mPer2) expression on radiosensitivity in normal mouse cells exposed to 60Co-γ-rays. NIH 3T3 cells were treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) to induce endogenous mPer2 expression or transfected with pcDNA3.1(+)-mPer2 and irradiated with 60Co-γ-rays, and then analyzed by several methods such as flow cytometry, colony formation assay, RT-PCR, and immunohistochemistry. Flow cytometry and colony formation assay revealed that irradiated NIH 3T3 cells expressing high levels of mPer2 showed a lower death rate (TPA: 24 h 4.3% vs 12 h 6.8% and control 9.4%; transfection: pcDNA3.1-mPer2 3.7% vs pcDNA3.1 11.3% and control 8.2%), more proliferation and clonogenic survival (TPA: 121.7 ± 6.51 vs 66.0 ± 3.51 and 67.7 ± 7.37; transfection: 121.7 ± 6.50 vs 65.3 ± 3.51 and 69.0 ± 4.58) both when treated with TPA and transfected with mPer2. RT-PCR analysis showed an increased expression of bax, bcl-2, p53, c-myc, mre11, and nbs1, and an increased proportionality of bcl-2/bax in the irradiated cells at peak mPer2 expression compared with cells at trough mPer2 expression and control cells. However, no significant difference in rad50 expression was observed among the three groups of cells. Immunohistochemistry also showed increased protein levels of P53, BAX and proliferating cell nuclear antigen in irradiated cells with peak mPer2 levels. Thus, high expression of the circadian gene mPer2 may reduce the radiosensitivity of NIH 3T3 cells. For this effect, mPer2 may directly or indirectly regulate the expressions of cell proliferation- and apoptosis-related genes and DNA repair-related genes.

Mezquital Valley (MV), a Mexican wastewater-based agricultural and industrial region, is a "hot spot" of regulated air pollutants emissions, but the concurrent unregulated ones, like hazardous metals and polycyclic aromatic hydrocarbons (PAH), remain undocumented. A biomonitoring survey with the epiphytic Tillandsia recurvata was conducted there to detect spatial patterns and potential sources of 20 airborne elements and 15 PAH. The natural δ13C and δ15N ratios of this plant helped in source identification. The regional mean concentration of most elements was two (Cr) to over 40 times (Ni, Pb, V) higher than reported for Tillandsia in other countries. Eleven elements, pyrene and chrysene had 18–214% higher mean concentration at the industrial south than at the agricultural north of MV. The total quantified PAH (mean, 572 ng g−1; range, 143–2568) were composed by medium (65%, phenanthrene to chrysene), low (28%, naphthalene to fluorene) and high molecular weight compounds (7%, Benzo(b)fluoranthene to indeno(1,2,3-cd)pyrene). The δ13C (mean, −14.6‰; range, −15.7‰ to −13.7‰) was consistently lower than −15‰ near the major petroleum combustion sources. The δ15N (mean, −3.0‰; range, −9.9‰ to 3.3‰) varied from positive at agriculture/industrial areas to negative at rural sites. Factor analysis provided a five-factor solution for 74% of the data variance: 1) crustal rocks, 39.5% (Al, Ba, Cu, Fe, Sr, Ti); 2) soils, 11.3%, contrasting contributions from natural (Mg, Mn, Zn) and saline agriculture soils (Na); 3) cement production and fossil fuel combustion, 9.8% (Ca, Ni, V, chrysene, pyrene); 4) probable agricultural biomass burning, 8.1% (K and benzo(g,h,i)perylene), and 5) agriculture with wastewater, 5.2% (δ15N and P). These results indicated high deposition of bioaccumulative air pollutants at MV, especially at the industrial area. Since T. recurvata reflected the regional differences in exposition, it is recommended as a biomonitor for comparisons within and among countries where it is distributed: southern USA to Argentina.

We describe here a quantitative realtime PCR assay for the detection of single-base-pair differences that does not require fluorescently labeled gene-specific probes or complicated primer combinations. Following PCR or RT-PCR of a gene segment that may contain allele-specific differences, 100 pg amplified product are used for a real-time PCR with allele-specific primers and SYBR® Green. The use of HEPES buffer at a pH of 6.95 together with Ampli-Taq® DNA polymerase results in a threshold difference between the correct template and the mismatched template of as many as 20 cycles, depending on the mismatch. Correct matches can be detected in an excess of mismatched template at least at the 0.01 level for the six primer-template matches versus mismatches tested: GC vs. A·C, AT vs. G·T, GC vs. C·C, GC vs. G·G, AT vs. C·T, and GC vs. G·A. Because the initial amplification is separate from real-time detection, conditions can be independently optimized for each step, making the assay particularly suitable for the detection of allele-specific expression in single cells.