| 1. |
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| 2. |
- Yuan, Qin, et al.
(författare)
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A late Eocene palynological record from the Nangqian Basin, TibetanPlateau: Implications for stratigraphy and paleoclimate
- 2017
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Ingår i: Palaeoworld. - Nanjing : Elsevier. - 1871-174X .- 1875-5887. ; 26, s. 369-379
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Tidskriftsartikel (refereegranskat)abstract
- With the uplifting, large-scale thrusting and striking of the Tibetan Plateau, several Paleogene intracontinental basins formed within the northernTibetan Plateau (TP). Stratigraphical and paleoenvironmental studies of the sedimentary successions within these basins are critical for understandingPaleogene climatological changes in Eurasia. The Nangqian Basin, one of such basins, formed in the Yushu area of the northeastern Tibetan Plateau.A set of lacustrine sediments, dominated by red clasolite, marlite, and gypsum, developed in the Yang Ala section in this basin. Paleontologicalrecords from the Nangqian Basin remain poorly known. Here, we investigate the palynological assemblages of one sedimentary succession at theYang Ala section that belongs to the Gongjue Formation, and their implications regarding the geological age and paleoclimate are discussed. Theresults reveal that the assemblages are dominated mainly by angiosperm pollen (tricolpates and tricolporate), includingNitrariadites (Pokrovskaja), Quercoidites, and Labitricolpites, followed by gymnosperm pollen taxa, such as Ephedripites and Taxodiaceaepollenites, and sparse pteridophytespores produced by ferns. A late Eocene age is inferred based on palynostratigraphy and comparison with other pollen assemblages in the TP. Arelatively dry climate with brief humid periods is indicated by the high abundance of xerophytic pollen taxa, such as Ephedripites and Nitrariadites,which are associated with broadleaved deciduous and evergreen plants. The characteristics of the pollen assemblages from the studied Yang Alasection are consistent with other Cenozoic palynofloras from the Mahalagou Formation in the Xining Basin and with those of the Yaxicuo Groupin the Hoh Xil Basin. These results provide an improved stratigraphical scheme for parts of the Cenozoic and enrich the current knowledge of thevegetation history of the northeastern Tibetan Plateau.
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| 3. |
- Chen, Shao-Chun, et al.
(författare)
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First nationwide study regarding ceftriaxone resistance and molecular epidemiology of Neisseria gonorrhoeae in China
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press. - 0305-7453 .- 1460-2091. ; 71:1, s. 92-99
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major public health concern worldwide. This is the first nationwide study, performed within the China Gonococcal Antimicrobial Susceptibility Programme (China-GASP), regarding AMR, including ceftriaxone genetic resistance determinants, and molecular epidemiology of gonococci in China.Methods: Gonococcal isolates (naEuroS=aEuroS1257) from consecutive patients were collected at 11 sentinel sites distributed across China during 2012-13. Susceptibility to ceftriaxone, spectinomycin, ciprofloxacin and tetracycline was determined using the agar dilution method. Ceftriaxone resistance determinants penA and penB were examined using sequencing. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed for molecular epidemiology.Results: Among isolates, 0.2% were resistant to spectinomycin, 4.4% to ceftriaxone, 42.9% to tetracyclines (high-level resistance) and 99.8% to ciprofloxacin. Among 890 sequenced isolates, 16 (1.8%) possessed a penA mosaic allele; 4 of these isolates belonged to the MDR internationally spread NG-MAST genogroup G1407 (first description in China). Non-mosaic penA alleles with an A501T mutation and an A102D alteration in porB1b were statistically associated with decreased susceptibility/resistance to ceftriaxone. NG-MAST G10339, G1424 and G1053 were associated with decreased susceptibility/resistance to ceftriaxone.Conclusions: In China, ceftriaxone and spectinomycin can continue to be recommended for gonorrhoea treatment, with the possible exception of Hainan and Sichuan provinces where ceftriaxone resistance exceeded 5% and AMR surveillance needs to be strengthened. Molecular approaches including genotyping and AMR determinant analysis can be valuable to supplement and enhance conventional surveillance of gonococcal AMR in China.
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| 4. |
- Foote, Andrew D., et al.
(författare)
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Convergent evolution of the genomes of marine mammals
- 2015
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 47:3, s. 272-275
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Tidskriftsartikel (refereegranskat)abstract
- Marine mammals from different mammalian orders share several phenotypic traits adapted to the aquatic environment and therefore represent a classic example of convergent evolution. To investigate convergent evolution at the genomic level, we sequenced and performed de novo assembly of the genomes of three species of marine mammals (the killer whale, walrus and manatee) from three mammalian orders that share independently evolved phenotypic adaptations to a marine existence. Our comparative genomic analyses found that convergent amino acid substitutions were widespread throughout the genome and that a subset of these substitutions were in genes evolving under positive selection and putatively associated with a marine phenotype. However, we found higher levels of convergent amino acid substitutions in a control set of terrestrial sister taxa to the marine mammals. Our results suggest that, whereas convergent molecular evolution is relatively common, adaptive molecular convergence linked to phenotypic convergence is comparatively rare.
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| 5. |
- Jiao, Xiang, et al.
(författare)
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PHIP - a novel candidate breast cancer susceptibility locus on 6q14.1
- 2017
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Ingår i: Oncotarget. - : IMPACT JOURNALS LLC. - 1949-2553. ; 8:61, s. 102769-102782
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Tidskriftsartikel (refereegranskat)abstract
- Most non-BRCA1/2 breast cancer families have no identified genetic cause. We used linkage and haplotype analyses in familial and sporadic breast cancer cases to identify a susceptibility locus on chromosome 6q. Two independent genome-wide linkage analysis studies suggested a 3 Mb locus on chromosome 6q and two unrelated Swedish families with a LOD > 2 together seemed to share a haplotype in 6q14.1. We hypothesized that this region harbored a rare high-risk founder allele contributing to breast cancer in these two families. Sequencing of DNA and RNA from the two families did not detect any pathogenic mutations. Finally, 29 SNPs in the region were analyzed in 44,214 cases and 43,532 controls from BCAC, and the original haplotypes in the two families were suggested as low-risk alleles for European and Swedish women specifically. There was also some support for one additional independent moderate-risk allele in Swedish familial samples. The results were consistent with our previous findings in familial breast cancer and supported a breast cancer susceptibility locus at 6q14.1 around the PHIP gene.
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| 6. |
- Liu, Lingling, et al.
(författare)
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Uniform and perfectly linear current-voltage characteristics of nitrogen-doped armchair graphene nanoribbons for nanowires
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:1, s. 44-48
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Tidskriftsartikel (refereegranskat)abstract
- Metallic nanowires with desired properties for molecular integrated circuits (MICs) are especially significant in molectronics, but preparing such wires at a molecular level still remains challenging. Here, we propose, from first principles calculations, experimentally realizable edge-nitrogen-doped graphene nanoribbons (N-GNRs) as promising candidates for nanowires. Our results show that edge N-doping has distinct effects on the electronic structures and transport properties of the armchair GNRs and zigzag GNRs (AGNRs, ZGNRs), due to the formation of pyridazine and pyrazole rings at the edges. The pyridazine rings raise the Fermi level and introduce delocalized energy bands near the Fermi level, resulting in a highly enhanced conductance in N-AGNRs at the stable nonmagnetic ground state. Especially for the family of AGNRs with widths of n = 3p + 2, their semiconducting characteristics are transformed to metallic characteristics via N-doping, and they exhibit perfectly linear current-voltage (I-V) behaviors. Such uniform and excellent features indicate bright application prospects of the N-AGNRs as nanowires and electrodes in molectronics.
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| 7. |
- Meng, Xiang-hai, et al.
(författare)
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Safety evaluation of freeway basic segment based on CPMs and LOSS
- 2016
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Konferensbidrag (refereegranskat)abstract
- Safety evaluation of basic segments of freeway plays an important role in freeway safety management. Common methods for dividing basic segments were introduced and compared at first, and then a dynamic cluster segment division method was put forward based on where crashes located. Based on the numbers of crashes on divided segments, the statistical distribution of crashes was analyzed, and the result showed that the number of crashes on the divided segments followed the Negative Binomial (i.e., NB) distribution. Hence, Crash Prediction Models (i.e., CPMs) based on the NB distribution were established, and a method to evaluate the safety situation of freeway was proposed. Furthermore level of service of safety (i.e., LOSS) was introduced and the classification standard was determined, then a segment safety evaluation method based on LOSS was put forward. Both methods based on CPMs and based on LOSS were applied to the Jingzhu freeway, and the comparison showed that 57.8% segments were under the same level while the other were different. What’s more, it also could be find that the evaluation result based on CPM methods is more in line with actual situation. Safety evaluation method based on NB distribution considers traffic volume and geometric alignment, so it is more suitable for the freeway with complex geometric alignment conditions, mountainous freeway as Jingzhu freeway for instance. On the other hand, the safety evaluation method based on LOSS considers traffic volume and crash number, so it is more suitable for the freeway with good geometric alignment conditions.
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| 8. |
- Qin, Changliang, et al.
(författare)
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Process optimizations to recessed e-SiGe source/drain for performance enhancement in 22 nm all-last high-k/metal-gate pMOSFETs
- 2016
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Ingår i: Solid-State Electronics. - : Elsevier. - 0038-1101 .- 1879-2405. ; 123, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the technology of recessed embedded SiGe (e-SiGe) source/drain (S/D) module is optimized for the performance enhancement in 22 nm all-last high-k/metal-gate (HK/MG) pMOSFETs. Different Si recess-etch techniques were applied in S/D regions to increase the strain in the channel and subsequently, improve the performance of transistors. A new recess-etch method consists of a two-step etch method is proposed. This process is an initial anisotropic etch for the formation of shallow trench followed by a final isotropic etch. By introducing the definition of the upper edge distance (D) between the recessed S/D region and the channel region, the process advantage of the new approach is clearly presented. It decreases the value of D than those by conventional one-step isotropic or anisotropic etch of Si. Therefore, the series resistance is reduced and the channel strain is increased, which confirmed by the simulation results. The physical reason of D reducing is analyzed in brief. Applying this recess design, the implant conditions for S/D extension (SDE) are also optimized by using a two-step implantation of BF2 in SiGe layers. The overlap space between doping junction and channel region has great effect on the device's performance. The designed implantation profile decreases the overlap space while keeps a shallow junction depth for a controllable short channel effect. The channel resistance as well as the transfer ID-VG curves varying with different process conditions are demonstrated. It shows the drive current of the device with the optimized SDE implant condition and Si recess-etch process is obviously improved. The change trend of on-off current distributions extracted from a series of devices confirmed the conclusions. This study provides a useful guideline for developing high performance strained PMOS SiGe technology.
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| 9. |
- Shu, Xiang, et al.
(författare)
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Associations of obesity and circulating insulin and glucose with breast cancer risk : a Mendelian randomization analysis
- 2019
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Ingår i: International Journal of Epidemiology. - : OXFORD UNIV PRESS. - 0300-5771 .- 1464-3685. ; 48:3, s. 795-806
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Tidskriftsartikel (refereegranskat)abstract
- Background: In addition to the established association between general obesity and breast cancer risk, central obesity and circulating fasting insulin and glucose have been linked to the development of this common malignancy. Findings from previous studies, however, have been inconsistent, and the nature of the associations is unclear. Methods: We conducted Mendelian randomization analyses to evaluate the association of breast cancer risk, using genetic instruments, with fasting insulin, fasting glucose, 2-h glucose, body mass index (BMI) and BMI-adjusted waist-hip-ratio (WHRadj BMI). We first confirmed the association of these instruments with type 2 diabetes risk in a large diabetes genome-wide association study consortium. We then investigated their associations with breast cancer risk using individual-level data obtained from 98 842 cases and 83 464 controls of European descent in the Breast Cancer Association Consortium. Results: All sets of instruments were associated with risk of type 2 diabetes. Associations with breast cancer risk were found for genetically predicted fasting insulin [odds ratio (OR) = 1.71 per standard deviation (SD) increase, 95% confidence interval (CI) = 1.26-2.31, p = 5.09 x 10(-4)], 2-h glucose (OR = 1.80 per SD increase, 95% CI = 1.3 0-2.49, p = 4.02 x 10(-4)), BMI (OR = 0.70 per 5-unit increase, 95% CI = 0.65-0.76, p = 5.05 x 10(-19)) and WHRadj BMI (OR = 0.85, 95% CI = 0.79-0.91, p = 9.22 x 10(-6)). Stratified analyses showed that genetically predicted fasting insulin was more closely related to risk of estrogen-receptor [ER]-positive cancer, whereas the associations with instruments of 2h glucose, BMI and WHRadj BMI were consistent regardless of age, menopausal status, estrogen receptor status and family history of breast cancer. Conclusions: We confirmed the previously reported inverse association of genetically predicted BMI with breast cancer risk, and showed a positive association of genetically predicted fasting insulin and 2-h glucose and an inverse association of WHRadj BMI with breast cancer risk. Our study suggests that genetically determined obesity and glucose/insulin-related traits have an important role in the aetiology of breast cancer.
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| 10. |
- Wang, Xiang-Gao, et al.
(författare)
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HOW BAD OR GOOD ARE THE EXTERNAL FORWARD SHOCK AFTERGLOW MODELS OF GAMMA-RAY BURSTS?
- 2015
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 219:1
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Tidskriftsartikel (refereegranskat)abstract
- The external forward shock models have been the standard paradigm to interpret the broadband afterglow data of gamma-ray bursts (GRBs). One prediction of the models is that some afterglow temporal breaks at different energy bands should be achromatic; that is, the break times should be the same in different frequencies. Multiwavelength observations in the Swift era have revealed chromatic afterglow behaviors at least in some GRBs, casting doubts on the external forward shock origin of GRB afterglows. In this paper, using a large sample of GRBs with both X-ray and optical afterglow data, we perform a systematic study to address the question: how bad or good are the external forward shock models? Our sample includes 85 GRBs up to 2014 March with well-monitored X-ray and optical light curves. Based on how well the data abide by the external forward shock models, we categorize them into five grades and three samples. The first two grades (Grade I and II) include 45 of 85 GRBs. They show evidence of, or are consistent with having, an achromatic break. The temporal and spectral behaviors in each afterglow segment are consistent with the predictions (the "closure relations") of the forward shock models. These GRBs are included in the Gold sample. The next two grades (Grade III and IV) include 37 of 85 GRBs. They are also consistent with having an achromatic break, even though one or more afterglow segments do not comply with the closure relations. These GRBs are included in the Silver sample. Finally, Grade V (3/85) shows direct evidence of chromatic behaviors, suggesting that the external shock models are inconsistent with the data. These are included in the Bad sample. We further perform statistical analyses of various observational properties (temporal index alpha, spectral index beta, break time t(b)) and model parameters (energy injection index q, electron spectral index p, jet opening angle theta(j), radiative efficiency eta(gamma), and so on) of the GRBs in the Gold sample, and derive constraints on the magnetization parameter epsilon(B) in the forward shock. Overall, we conclude that the simplest external forward shock models can account for the multiwavelength afterglow data of at least half of the GRBs. When more advanced modeling (e.g., long-lasting reverse shock, structured jets, arbitrary circumburst medium density profile) is invoked, up to >90% of the afterglows may be interpreted within the framework of the external shock models.
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| 11. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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