科研成果

[This corrects the article DOI: 10.1371/journal.pgen.1006528.].

On the cover: The cover image, by Yanmei Dou et al., is based on the Research Article Postzygotic single‐nucleotide mosaicisms contribute to the etiology of autism spectrum disorder and autistic traits and the origin of mutations, Pages 1002–1013. DOI 10.1002/humu. 23284

The firework algorithm (FWA) is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude (MW) 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region, inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15, 15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s, respectively.

We present high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-IDTIMS) U-Pb zircon and isotope dilution-negative-diennal ionization mass spectrometry (ID-N-TIMS) Re-Os molybdenite geochronology of the world class Tibetan Qulong porphyry Cu-NIo deposit. The data is used to constrain the timing, duration, and to yield implications for the ore -forming processes. The (-Pb data suggest that the preore Bonginuctiola pluton crystallized at 17.142 0.014/0.014/0.023 Ma (uncertainties presented as analytical /+ tracer /+ decay constant uncertainties), with emplacements of the synore P porphyry and postore quartz diorite occurring at 16.009 +/- 0.016/0.017/0.024 and 15.166 +/- 0.010/0.011/0.020 Ma, respectively. The Re-Os analysis of nudtiple independent molybdenite separations from single molybdenite-bearing quartz veins yields sub-%(0) level analytical precision (<1%(0)), which is comparable with that of modern CA[D-TINTSU-Pb zircon geochronology. The new Re-Os data indicate that the majority of the metals at Qulong were deposited over a minimum duration of 266 13 k.y., between 16.126 +/- 0.008/0.060/0.077 and 1.5.86 +/- 00.010/0.058/0.075 Ma, with die main phase of mineralization being broadly synchronous with the emplacement of die P porphyry. However, our Re-Os data of molybdenite hosted within the Rongmuctiola pillion imply that a portion of mineralizadon also predated die P porphyry and suggest that die P porphyry is an intermineral porphyry stock, although mineralization cut by P porphyry has not been previously documented or observed in this study. Correlating the Re-Os ages with vein types (A-B-D veins) demonstrates that the mineralization process was cyclical, with the presence of at least three short-lived (38 +/- 11 to 59 10 k.y.) mineralization pulses between 16.1.26 +/- 0.008 and 16.050 +/- 0.005, 16.040 +/- 0.007 and 15.981 +/- 0.007, and similar to 15.981 +/- 0.007 and 15.860 +/- 0.010 Ma. Coupling die Re-Os molybdenite ages and quartz (coprecipitated with die dated molybdenite) fluid inclusion data suggests that die cooling history was also cyclic, and implies a rapid cooling rate during the entire mineralization process (0.55 degrees +/- 0.11 C/k.y.), with much faster cooling rates (1.19 degrees +/- 0.82 degrees to 1.27 degrees +/- 0.53 degrees C/k.y.) for the individual mineralization pulses. The cyclic and rapid cooling process requires an additional cooling mechanism rather than the inefficient conduction, which we attribute to meteoric water circulation.The presence of mineralization predating the intermineral P porphyry stock and the absence of evidence of an early porphyry stock at Qulong suggest that mineralization potentially can take place without contemporaneous magmatism at mineralization levels. As a result, dating magmatic events may not necessarily bracket the entire mineralization duration of a porphyry system. This highlights the importance of dating ore minerals to reveal a comprehensive picture of the magma-hydrothermal process. In addition, the absence of contemporaneous magmatism during mineralization has broad implications for the classification of porphyry copper deposits and mineral exploration. The timescales of mineralization cycles constrained here via direct dating of ore minerals (tens of k.y.) are comparable with those recently proposed through high -precision U-Pb zircon dating, diffusion modeling, and numerical simulation. We propose that the cyclic mineralization pulses are linked with the periodic release of volatiles from the lower crustal magma chamber, which are common for porphyry copper systems worldwide. The episodic/cyclic metal enrichment process potentially is one of the controlling factors of porphyry copper ore formation and is the key to differentiate the formation of economic and subeconomic porphyry deposits.Finally, direct comparison of molybdenite Re-Os dates from different laboratories and with the zircon U-Pb system needs to account for the much larger uncertainties from tracer calibration and decay constants, respectively. As a result, we lose the necessary resolution to investigate the ore -forming process at the k.y. level. Therefore, to reduce these uncertainties, calibration between the two chronometers, using shared tracer solutions and a transparent data reduction platform within the community is required.

Objective To examine whether previous observed inverse associations of dairy intake with systolic blood pressure and risk of hypertension were causal.Design Mendelian randomization study using the single nucleotide polymorphism rs4988235 related to lactase persistence as an instrumental variable.Setting CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium.Participants Data from 22 studies with 171 213 participants, and an additional 10 published prospective studies with 26 119 participants included in the observational analysis.Main outcome measures The instrumental variable estimation was conducted using the ratio of coefficients approach. Using meta-analysis, an additional eight published randomized clinical trials on the association of dairy consumption with systolic blood pressure were summarized.Results Compared with the CC genotype (CC is associated with complete lactase deficiency), the CT/TT genotype (TT is associated with lactose persistence, and CT is associated with certain lactase deficiency) of LCT-13910 (lactase persistence gene) rs4988235 was associated with higher dairy consumption (0.23 (about 55 g/day), 95% confidence interval 0.17 to 0.29) serving/day; P<0.001) and was not associated with systolic blood pressure (0.31, 95% confidence interval -0.05 to 0.68 mm Hg; P=0.09) or risk of hypertension (odds ratio 1.01, 95% confidence interval 0.97 to 1.05; P=0.27). Using LCT-13910 rs4988235 as the instrumental variable, genetically determined dairy consumption was not associated with systolic blood pressure (beta=1.35, 95% confidence interval -0.28 to 2.97 mm Hg for each serving/day) or risk of hypertension (odds ratio 1.04, 0.88 to 1.24). Moreover, meta-analysis of the published clinical trials showed that higher dairy intake has no significant effect on change in systolic blood pressure for interventions over one month to 12 months (intervention compared with control groups: beta=-0.21, 95% confidence interval -0.98 to 0.57 mm Hg). In observational analysis, each serving/day increase in dairy consumption was associated with -0.11 (95% confidence interval -0.20 to -0.02 mm Hg; P=0.02) lower systolic blood pressure but not risk of hypertension (odds ratio 0.98, 0.97 to 1.00; P=0.11).Conclusion The weak inverse association between dairy intake and systolic blood pressure in observational studies was not supported by a comprehensive instrumental variable analysis and systematic review of existing clinical trials.

Using coupled dynamic substance flow and environmental fate models, CiP-CAFE and BETR-Global, we investigated whether degradation of side-chain fluorotelomer-based polymers (FTPs), mostly in waste stocks (i.e., landfills and dumps), serves as a long-term source of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylates (PFCAs) to the global environment. The modelling results indicate that, in the wake of the worldwide transition from long-chain to short-chain products, in-use stocks of C8 FTPs will peak and decline afterwards while the in-use stocks of C6 FTPs and waste stocks of both FTPs will generally grow. FTP degradation in waste stocks is making an increasing contribution to FTOH generation, the bulk of which readily migrates from waste stocks and degrades into PFCAs in the environment; the remaining part of the generated FTOHs degrade in waste stocks, which makes those stocks reservoirs that slowly release PFCAs into the environment over the long run because of the low leaching rate and extr...

An ellipsoid, the simplest nonspherical shape, has been extensively used as a model for elongated building blocks for a wide spectrum of molecular, colloidal, and granular systems. Yet the densest packing of congruent hard ellipsoids, which is intimately related to the high-density phase of many condensed matter systems, is still an open problem. We discover an unusual family of dense crystalline packings of self-dual ellipsoids (ratios of the semiaxes α:√α:1), containing 24 particles with a quasi-square-triangular (SQ-TR) tiling arrangement in the fundamental cell. The associated packing density ϕ exceeds that of the densest known SM2 crystal [ A. Donev et al., Phys. Rev. Lett. 92, 255506 (2004)] for aspect ratios α in (1.365, 1.5625), attaining a maximal ϕ≈0.75806... at α=93/64. We show that the SQ-TR phase derived from these dense packings is thermodynamically stable at high densities over the aforementioned α range and report a phase diagram for self-dual ellipsoids. The discovery of the SQ-TR crystal suggests organizing principles for nonspherical particles and self-assembly of colloidal systems.

© 2017 IEEE. Quantitative effects of Moore's Law have driven qualitative changes in FPGA architecture, applications, and tools. As a consequence, the existing EDA tools takes several hours or even days to implement the applications onto FPGAs. Typically, routing is a very time-consuming process in the EDA design flow. While several attempts have accelerated this process through parallelization, they still do not provide a strong parallel scheme for FPGA routing. In this paper we introduce a dependency-aware parallel approach, named Bamboo, to accelerate the routing time for FPGAs. With the dependency detection, Bamboo partitions the nets into multiple subsets, where the nets in the same subsets are independent, and the dependency only exists among different subsets. Specifically, the independent nets in the same subset are routed in parallel, and the subsets are processed in serial according to the original routing ordering. The partitioning problem is solved optimally using dynamic programming, and the parallelization is implemented by speculative parallelism on a single GPU. Experimental results show that our approach achieves an average of 15.13x speedup with negligible influence on the routing quality. Most importantly, it effectively maintains deterministic results and always produces the same results as the serial version.

The theoretical study of a step-tunable gyrotron controlled by successive excitation of multi-harmonic modes is presented in this paper. An axis-encircling electron beam is employed to eliminate the harmonic mode competition. Physics images are depicted to elaborate the multi-harmonic interaction mechanism in determining the operating parameters at which arbitrary harmonic tuning can be realized by magnetic field sweeping to achieve controlled multiband frequencies' radiation. An important principle is revealed that a weak coupling coefficient under a high-harmonic interaction can be compensated by a high Q-factor. To some extent, the complementation between the high Q-factor and weak coupling coefficient makes the high-harmonic mode potential to achieve high efficiency. Based on a previous optimized magnetic cusp gun, the multi-harmonic step-tunable gyrotron is feasible by using harmonic tuning of first-to-fourth harmonic modes. Multimode simulation shows that the multi-harmonic gyrotron can operate on the 34 GHz first-harmonic TE11 mode, 54 GHz second-harmonic TE21 mode, 74 GHz third-harmonic TE31 mode, and 94 GHz fourth-harmonic TE41 mode, corresponding to peak efficiencies of 28.6%, 35.7%, 17.1%, and 11.4%, respectively. The multi-harmonic step-tunable gyrotron provides new possibilities in millimeter–terahertz source development especially for advanced terahertz applications.

Line-shape engineering is a key strategy to endow extra stretchability to 1D silicon nanowires (SiNWs) grown with self-assembly processes. We here demonstrate a deterministic line-shape programming of in-plane SiNWs into extremely stretchable springs or arbitrary 2D patterns with the aid of indium droplets that absorb amorphous Si precursor thin film to produce ultralong c-Si NWs along programmed step edges. A reliable and faithful single run growth of c-SiNWs over turning tracks with different local curvatures has been established, while high resolution transmission electron microscopy analysis reveals a high quality monolike crystallinity in the line-shaped engineered SiNW springs. Excitingly, in situ scanning electron microscopy stretching and current–voltage characterizations also demonstrate a superelastic and robust electric transport carried by the SiNW springs even under large stretching of more than 200%. We suggest that this highly reliable line-shape programming approach holds a strong promise to extend the mature c-Si technology into the development of a new generation of high performance biofriendly and stretchable electronics.