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Lower-crust-derived adakitic rocks in the Gangdese belt provide important constraints on the timing of Tibetan crustal thickening and on the relative contributions of magmatic and tectonic processes. Here we present geochronological and geochemical data for the Wangdui porphyritic monzogranites in the western Gangdese belt. Zircon U–Pb dating yields emplacement ages of 46–44 Ma. All samples have high Sr (321–599 ppm), low Yb (0.76–1.33 ppm) and Y (10.6–18.3 ppm) contents, with high La/Yb (51.1–72.3) and Sr/Y (21.0–51.4) ratios, indicating adakitic affinities. The low MgO (0.97–1.76 wt %), Cr (7.49–53.6 ppm) and Ni (4.75–29.1 ppm) contents, as well as high 87Sr/86Sr(i) (0.7143–0.7145), low ϵNd(t) (−10.4 to −9.8) and zircon ϵHf(t) (−17.7 to 0.4) values, suggest that the Wangdui pluton most likely originated from partial melting of the thickened ancient lower crust. In combination with previously published data, despite the east–west-trending heterogeneity of crustal composition in the Gangdese belt, the La/Yb ratios of magmatic rocks reveal that both western and eastern segments experienced remarkable crustal thickening in the Eocene. However, in contrast to the thickened juvenile lower crust in the eastern segment formed by the underplating of mantle-derived magmas, tectonic shortening plays a more crucial role in thickening of the ancient basement in western Gangdese. In fact, such Eocene-thickened ancient lower-crust-derived adakitic rocks are widely distributed in the central Himalayan–Tibetan orogen. This, together with the extensive development of fold–thrust belts, suggests that tectonic shortening might be the main mechanism accounting for the crustal thickening associated with the India–Asia collision.
β-Glucan has been reported for its health benefits on blood lipids in hypercholesterolaemic individuals for years. However, people have paid little attention to the effects of β-glucan in populations with mild hypercholesterolaemia as well as the various delivering matrices. Our objective was to perform a meta-analysis to analyse the effects of β-glucan with different delivering matrices in mildly hypercholesterolaemic individuals. After conducting a comprehensive search in Web of Science, PubMed, Scopus and Cochrane Library, a total of twenty-one randomised controlled trials involving 1120 participants were identified to measure the pooled effect. The overall results indicated that consuming a dose of ≥3 g/d of β-glucan for at least 3 weeks could significantly reduce total cholesterol (TC) (−0·27 mmol/l, 95 % CI −0·33, −0·21, P < 0·001) and LDL-cholesterol (−0·26 mmol/l, 95% CI −0·32, −0·20, P < 0·001) compared with the control group in mildly hypercholesterolaemic individuals, while no significant difference was observed in TAG (−0·03 mmol/l, 95% CI −0·11, 0·06, P = 0·521) and HDL-cholesterol (0·01 mmol/l, 95% CI −0·03, 0·04, P = 0·777). There was evidence for modest unexplained heterogeneity in the meta-analysis. In conclusion, β-glucan can significantly reduce risk factors like TC and LDL-cholesterol for CVD in mildly hypercholesterolaemic individuals; furthermore, it appears that the effects of food matrices with both ‘solid products’ and ‘liquid products’ where β-glucan was incorporated into were ranked as the best way to exert its beneficial properties, while ‘liquid’ and ‘solid’ products were ranked as the second and third positions, respectively.
Image stitching is important for the perception and manipulation of undersea robots. In spite of a well-developed technique, it is still challenging for undersea images because of their inevitable appearance ambiguity caused by the limited light in the undersea environment, and local disturbance caused by moving objects, ocean current, etc. To get a clean and stable background panorama in the undersea environment, this paper proposes an undersea image-stitching method by introducing graph-based registration and blending procedures. Specifically, in the registration procedure, matching the features in each undersea image pair is formulated and solved by graph matching, to incorporate the structural information between features. In the blending procedure, an energy function on the indirect graph Markov random field is proposed, which takes both image consistency and neighboring consistency into consideration. Coincidentally, both graph matching and energy minimization can be mathematically formulated by integer quadratic programming problems with different constraints; the recently proposed graduated nonconvexity and concavity procedure is used to optimize both problems. Experiments on both synthetic images and real-world undersea images witness the effectiveness of the proposed method.
Coastal lake sediments are valuable paleoclimate archives provided that they can be accurately dated. Here, we report radiocarbon ages of bulk sediment organic matter (OM), plants, shells, particulate OM, and dissolved OM from coastal lakes in Florida. Bulk sediment OM yielded ages that are consistently older than contemporaneous plants and shells, indicating significant radiocarbon deficiencies in sedimentary OM in these lakes. The data show that the OM radiocarbon deficiency varies over time and with location, making it impossible to determine a proper correction factor for radiocarbon ages of bulk sediments from these lakes. As a result, we consider ages obtained from bulk sediment OM from these lakes unreliable. The age reversals in bulk sediment OM observed in the sediment cores are likely caused by rapid increases in erosion and sedimentation resulting from large storm events. The data also show that sedimentation rate can vary considerably within a given lake, implying that an age-depth model established for one core cannot be directly applied to other cores despite their close proximity. Analyses of shells from one of the lakes suggest that fresh/brackish-water shells may serve as a good substrate for radiocarbon dating owing to a small reservoir effect on inorganic carbon.
The microstructure evolution of high nitrogen austenitic steel wires under various annealing times and drawing temperatures was carefully characterized. Special attention was paid to the widely distributed twins and the nanoprecipitates at twin boundaries (TBs) in high nitrogen stainless steels (HNSSs). The results of microhardness indicated that the traditional Hall–Petch (H–P) equation, which only took the role of grain boundaries into account, was unsuitable. A new H–P equation that connected grain size, twin density, precipitates at TBs, and microhardness in HNSS was established for the first time and showed to be in good agreement with the experimental results. By analyzing the strained regions near TBs, a model describing the precipitation of nano-M23C6 carbides on coherent twin boundaries and incoherent twin boundaries was proposed. In addition, the influence mechanism of the nano-M23C6 at TBs on microhardness was discussed.
In this paper, we propose a novel method for constructing upper bounds of the quasi-stationary distribution of SIS processes. Using this method, we obtain an upper bound that is better than the state-of-the-art upper bound. Moreover, we prove that the fixed point map Φ  actually preserves the equilibrium reversed hazard rate order under a certain condition. This allows us to further improve the upper bound. Some numerical results are presented to illustrate the results.
A new planar microstrip-fed monopole ultra-wideband (UWB) antenna with dual notched bands has been presented. By employing a simple dual-mode resonator with two symmetrical outer high-impedance lines beside the microstrip feed line of the proposed UWB antenna, two controllable rejection bands with high-frequency selectivity are created. The parametric studies of the proposed structure are explored for the dual band-notched operating mechanism. Finally, the experimental results, including return losses, radiation patterns, and peak gains are shown, declaring that the proposed antenna has good impedance matching performance and radiation pattern properties.
Sign truncated matching pursuit (STrMP) algorithm is presented in this paper. STrMP is a new greedy algorithm for the recovery of sparse signals from the sign measurement, which combines the principle of consistent reconstruction with orthogonal matching pursuit (OMP). The main part of STrMP is as concise as OMP and hence STrMP is simple to implement. In contrast to previous greedy algorithms for one-bit compressed sensing, STrMP only need to solve a convex and unconstrained subproblem at each iteration. Numerical experiments show that STrMP is fast and accurate for one-bit compressed sensing compared with other algorithms.
New numerical techniques are presented for the solution of the two-dimensional time fractional evolution equation in the unit square. In these methods, Galerkin finite element is used for the spatial discretization, and, for the time stepping, new alternating direction implicit (ADI) method based on the backward Euler method combined with the first order convolution quadrature approximating the integral term are considered. The ADI Galerkin finite element method is proved to be convergent in time and in the L2 norm in space. The convergence order is 𝓞(k|ln k| + hr), where k is the temporal grid size and h is spatial grid size in the x and y directions, respectively. Numerical results are presented to support our theoretical analysis.
The numerical solution of a parabolic Volterra integro-differential equation with a memory term on a one-dimensional unbounded spatial domain is considered. A quasi-wavelet based numerical method is proposed to handle the spatial discretisation, the Crank-Nicolson scheme is used for the time discretisation, and second-order quadrature to approximate the integral term. Some numerical examples are presented to illustrate the efficiency and accuracy of this approach.
The z-transform is introduced to analyze a full discretization method for a partial integro-differential equation (PIDE) with a weakly singular kernel. In this method, spectral collocation is used for the spatial discretization, and, for the time stepping, the finite difference method combined with the convolution quadrature rule is considered. The global stability and convergence properties of complete discretization are derived and numerical experiments are reported.
Investigation of optical absorption in ∼25μm thick, monocrystalline silicon (Si) substrates obtained from a novel exfoliation technique is done by fabricating solar cells with single heterojunction architecture (without using intrinsic amorphous silicon layer) with diffused back junction and local back contact. The ease of process flow and the rugged and flexible nature of the substrates due to thick metal backing enables use of various light-trapping and optical absorption enhancement schemes traditionally practiced in the industry for thicker (>120μm) substrates. Optical measurement of solar cells using antireflective coating, texturing on both surfaces, and back surface dielectric/metal stack as mirror to reflect the long wavelength light from the back surface show a very low front surface reflectance of 4.6% in the broadband spectrum (300nm-1200nm). The illuminated current voltage (IV) and external quantum efficiency (EQE) measurement of such solar cell shows a high integrated current density of 34.4mA/cm2, which implies significant internal photon reflection. Our best cell with intrinsic amorphous silicon (i-a-Si) layer with only rear surface textured shows an efficiency of 14.9%. EQE data shows improved blue response and current density due to better front surface passivation. Simulations suggest that with optimized light trapping and surface passivation, such thin c-Si cells can reach efficiencies >20%.
This paper is concerned with a compact difference scheme with the truncation error of order 3/2 for time and order 4 for space to an evolution equation with a weakly singular kernel. The integral term is treated by means of the second order convolution quadrature suggested by Lubich. The stability and convergence are proved by the energy method. A numerical experiment is reported to verify the theoretical predictions.
In order to deposit YBCO coated conductor with high critical current densities on rolling assisted biaxially textured Ni-W tapes, this paper has systematically studied the influence of deposition conditions on the orientation, in-plane texture and surface morphology of buffers and superconducting layers. It was found that the crystalline alignment and the in-plane texture of cerium oxide cap-layers were well improved by optimizing deposition parameters. The full width at half maximum of phi-scan x-ray diffraction peaks were reduced from original values of 7-8 degrees to 5-6 degrees. A high critical current density of 4.6×106 A/cm2 has been achieved on optimized buffer layers. This value is comparable with the critical current density of YBCO thin films deposited on single crystalline substrates.
The elusive snow leopard Panthera unica is a rare and little studied species in China. Over 1 March–15 May 2006 we conducted a survey for the snow leopard in the Gouli Region, East Burhanbuda Mountain, Kunlun Mountains, Qinghai Province, China, in an area of c. 300 km2 at altitudes of 4,000–4,700 m. We surveyed 29 linear transects with a total length of c. 440 km, and located a total of 72 traces (pug marks, scrapes and urine marks) of snow leopard along four of the transects. We obtained eight photographs of snow leopard from four of six camera traps. We also recorded 1,369 blue sheep, 156 Tibetan gazelles, 47 argali, 37 red deer and one male white-lipped deer. We evaluated human attitudes towards snow leopard by interviewing the heads of 27 of the 30 Tibetan households living in the study area. These local people did not consider that snow leopard is the main predator of their livestock, and thus there is little retaliatory killing. Prospects for the conservation of snow leopard in this area therefore appear to be good. We analysed the potential threats to the species and propose the establishment of a protected area for managing snow leopard and the fragile alpine ecosystem of this region.
To investigate the wheat transcriptional profile under drought stress, a drought-tolerant variety of wheat (Triticum aestivum), Hanxuan 10, was treated with polyethylene glycol (PEG6000) and samples were collected at 0, 1, 6 and 24 h. Complementary DNA was labelled with fluorescent dye and hybridized with the BGI-RiceChip, a whole genome rice gene chip platform, which contains over 60 000 oligos based on the rice genome sequence. Data analysis detected 166, 207 and 328 differentially expressed genes (DGs), respectively, at 1, 6 and 24 h, indicating that the number of DGs increased with the length of the PEG treatment. Functional category analysis showed that the number of DGs related to energy metabolism pathways increased – 4.2%, 8.2% and 16.8%, respectively, as a proportion of the total number of DGs. Most of the photosynthesis-related genes were up-regulated. It is interesting to note that Psbr and ribulose-bisphosphate carboxylase (Rubisco)-coding genes were down-regulated, suggesting their potential role in the response to drought tolerance.