The Kuroshio Current (KC), which redistributes heat and moisture from the tropics toward mid-latitudes, considerably affects ocean–atmosphere–land interactions along its pathways. However, our ...knowledge about the KC strength and associated forcing, based on investigations of instrumental data and model simulations, is controversial, impeding assessment of its possible change in the near future. In this study, we investigated KC strength over the past 4400 yr by analyzing alkenone (U37K′) sea surface temperature (SST) signal in a sediment core under the influence of the Yellow Sea Warm Current (YSWC), a branch of the KC in the western North Pacific, along with a coastal SST record over the last 1000 yr outside of the YSWC effect. Our SST record in the warm current pathway, opposite to the patterns of coastal SST and solar irradiance changes at multi-centennial timescales, effectively manifests variations of YSWC strength. In conjunction with published records, we show a remarkably intensified YSWC, and probably the KC as well, during the cool interval between 1400–1850 AD (the Little Ice Age, LIA). We suggest that cold climate conditions, perhaps in relation to strengthened East Asian winter monsoon and Pacific Walker circulation, were more favorable for KC enhancement.
•Alkenone (U37K′)-based SST records from basin-wide cyclonic gyre in the Yellow Sea.•SST increase (∼5°C) during Little Ice Age implies enhanced Yellow Sea Warm Current.•The Kuroshio Current (KC) is likely intensified during cooling climate intervals.
Characterizing the Connectivity of Railway Networks Xu, Zhongzhi; Zhang, Qingpeng; Chen, Dingjun ...
IEEE transactions on intelligent transportation systems,
2020-April, 2020-4-00, Letnik:
21, Številka:
4
Journal Article
Recenzirano
How well stations are connected with each other is a critical performance assessment of railway systems. Network analysis is a highly intuitive and interpretable approach to characterizing the ...physical connectivity of railway systems. However, the physical connectivity is often limited in depicting transportation network dynamics due to the lack of traffic flow information. This paper first comprehensively reviews the physical connectivity metrics and applies these metrics to evaluate the connectivity of China's high-speed railway system. Then, through integrating the real-world network topology and travel demand data, we conduct the first data-driven research on comparing the physical connectivity with the logical connectivity of railway systems. The experiments demonstrate that the physical connectivity metrics cannot well represent the connectivity of railway systems, due to the neglect of the heterogeneous distribution and temporal patterns of the passenger flows.
Infertility is a growing health concern among many couples worldwide. Men account for half of infertility cases. CatSper, a sperm-specific Ca2+ channel, is expressed on the cell membrane of mammalian ...sperm. CatSper plays an important role in male fertility because it facilitates the entry of Ca2+ necessary for the rapid change in sperm motility, thereby allowing it to navigate the hurdles of the female reproductive tract and successfully locate the egg. Many pollutants present in the environment have been shown to affect the functions of CatSper and sperm, which is a matter of capital importance to understanding and solving male infertility issues. Environmental pollutants can act as partial agonists or inhibitors of CatSper or exhibit a synergistic effect. In this article, we briefly describe the structure, functions, and regulatory mechanisms of CatSper, and discuss the body of literature covering the effects of environmental pollutants on CatSper.
●CatSper plays an important role in male fertility and sperm functions.●Environmental pollutants can act as partial agonists or inhibitors of CatSper or exhibit a synergistic effect.●The regulation of CatSper functions by environmental pollutants maybe provide new ideas for male infertility.●Some medicines targeted CatSper may alleviate the male reproductive toxicity caused by environmental pollutants.
Accumulating evidence has revealed the dysbiosis of gut/fecal microbiota induced by heat stress (HS) in mammals and poultry. However, the effects of HS on microbiota communities in different ...intestinal segments of Cherry-Valley ducks (a widely used meat-type breed) and their potential associations with growth performances, fat deposition, intestinal morphology, and antioxidant capacity have not been well evaluated yet. In this study, room temperature (RT) of 25°C was considered as control, and RT at 32°C for 8 h per day was set as the HS treatment. After 3 weeks, the intestinal contents of jejunum, ileum, and cecum were harvested to investigate the microbiota composition variations by 16S ribosomal RNA amplicon sequencing. And the weight gain, adipose indices, intestinal morphology, and a certain number of serum biochemical parameters were also measured and analyzed. The results showed the microbial species at different levels differentially enriched in duck jejunum and cecum under HS, while no significant data were observed in ileum. HS also caused the intestinal morphological changes (villus height and the ratio of villus height to crypt depth) and the reductions of growth speed (daily gain), levels of serum triglyceride (TG) and total cholesterol, and antioxidant activity (higher malondialdehyde (MDA) content and lower total antioxidant). The higher abdominal fat content and serum glucose level were also observed in HS ducks. The Spearman correlation analysis indicated that in jejunum the phyla
and
were associated with average daily gain, feed/gain, serum TG and MDA levels, and villus height/crypt depth (
< 0.05). The phylum
and genus
were significantly associated with fat deposition and serum glucose level (
< 0.05). The genus
was positively associated with serum total antioxidant (
< 0.05), while some other microbial species were found negatively associated, including order
, genera
, and
. However, no significant correlations were observed in cecum. These findings imply the potential roles of duck gut microbiota in the intestinal injuries, fat deposition, and reductions of growth speed and antioxidant capacity caused by HS, although the molecular mechanisms requires further investigation.
Abstract
Gas infall motions play a crucial role in high-mass star formation and are characterized by observable signatures of blueshifted asymmetric spectral line profiles (“blue profiles”). However, ...the connection between blue profiles and infall motions is unclear due to complex gas motions at parsec scales. In this study, we present the results of an HCN (4–3) mapping survey conducted with the James Clerk Maxwell Telescope, toward 38 massive clumps exhibiting blue profiles in HCO
+
(3–2). We extract 34 HCN cores from the 38 observed fields. The core-averaged spectra show various line profiles, indicating that blue-profile HCO
+
(3–2) does not guarantee the same in HCN (4–3). Through non-LTE radiative-transfer calculations, we attribute the low detection rate of high-
J
blue profiles to a combination of insufficient HCN (4–3) opacity and the intricate gas motion across different density layers. A comparison between the MALT90 and Bolocam Galactic Plane Survey line surveys highlights the importance of appropriate tracers, high spectral resolution, and column density thresholds when searching for blue profiles. We select 11 reliable infall candidates and adopt the Hill5 model to fit the infall velocity of 0.2–1.6 km s
−1
, corresponding to 5%–74% of freefall velocity. Assuming a spherically collapsing model, we estimate the median and mean mass infall rates to be 4.5 × 10
−3
and 7.6 × 10
−3
M
⊙
yr
−1
, respectively. The consistency of the mass infall rates among different transitions suggests a steady accretion process from the clump gas envelope to the inner region.
Defects, such as debonding and foreign matters in transformer insulation paperboard, lead to local field strength concentration, thereby seriously affecting the safe operation of equipment. At ...present, industrial X-ray computed tomography scanning technology is mostly used to detect such defects. However, the equipment is expensive, the operation is complicated, and radiation hazard exists. In this study, terahertz time domain spectroscopy is introduced to explore the nondestructive testing method of oil-paper insulation defects. Three typical insulation paperboard defects of interface debonding, metal foreign matter mixing, and local carbonization traces were taken as the research objects. An artificial defect model is prepared. The time and frequency domain waveform characteristics of terahertz pulse wave propagating in the defect model are tested and analyzed. The results show that when the thickness of insulation paperboard covering is less than 5 mm, based on the amplitude and delay characteristics of terahertz time-domain signal, the location and size of typical internal defects can be accurately obtained, and time spectrum imaging can be realized. This study proves theoretically and experimentally the feasibility of noncontact and nondestructive testing for the internal defects of insulation paperboard by using terahertz technology.
Interspecific hybridization and whole genome duplication are driving forces of genomic and organism diversification. But the effect of interspecific hybridization and whole genome duplication on the ...non-coding portion of the genome in particular remains largely unknown. In this study, we examine the profile of long non-coding RNAs (lncRNAs), comparing them with that of coding genes in allotetraploid cotton (Gossypium hirsutum), its putative diploid ancestors (G. arboreum; G. raimondii), and an F
hybrid (G. arboreum × G. raimondii, AD).
We find that most lncRNAs (80%) that were allelic expressed in the allotetraploid genome. Moreover, the genome shock of hybridization reprograms the non-coding transcriptome in the F
hybrid. Interestingly, the activated lncRNAs are predominantly transcribed from demethylated TE regions, especially from long interspersed nuclear elements (LINEs). The DNA methylation dynamics in the interspecies hybridization are predominantly associated with the drastic expression variation of lncRNAs. Similar trends of lncRNA bursting are also observed in the progress of polyploidization. Additionally, we find that a representative novel lncRNA XLOC_409583 activated after polyploidization from a LINE in the A subgenome of allotetraploid cotton was involved in control of cotton seedling height.
Our results reveal that the processes of hybridization and polyploidization enable the neofunctionalization of lncRNA transcripts, acting as important sources of increased plasticity for plants.
Based on ~150‐year of sedimentary records, we identify that autochthonous carbonate deposition in Lake Wuliangsu, in the upper reaches of the Yellow River, was independent of both hydrological and ...ecological variations before 1965, influenced by hydrological changes due to agricultural activities during 1965–1990, and slightly impacted by higher productivity under the eutrophication process after 1990. By comparing with data from lakes across the globe, we find that lake size and lake stratification control the contribution of recycled organic carbon to autochthonous carbonate deposition. Continuous mixing and aeration in shallow lakes facilitate the transformation of organic carbon into 29–45% of sedimentary carbonate, different from large and deep lakes (2–25%). Organic carbon recycling in lakes remains generally stable or decreases under the pressure of lake eutrophication, requiring further investigations on whether more organic carbon will be buried in the carbonate form.
Plain Language Summary
The mechanisms that control the deposition, on the bottom of lakes, of carbonate matter that forms within the lakes themselves, are important for the carbon cycles at regional and global scales. Here we present data of carbonate content and carbon isotope composition from the past ~150 years recorded at Lake Wuliangsu, where the historical hydrological and ecological conditions have been well studied. We first investigate the factors that control the deposition of carbonate matter and calculate how much of it derives from recycled organic carbon using a carbon isotope mass‐balance model. Furthermore, we compile published data from lake systems across the globe and we incorporate them into our framework, so as to seek a better understanding of organic carbon recycling in a global perspective. Finally, we find that the size of the lake (area and depth) and the lake stratification play a key role in determining the contribution of recycled organic carbon to the overall carbonate deposition.
Key Points
Carbonate deposition in Lake Wuliangsu is influenced by human‐induced hydrological and ecological changes after 1965
In Lake Wuliangsu, recycling of organic carbon contributes more than 30% of the sedimentary carbonate
In the global perspective, lake size and lake stratification are crucial for contribution of recycled organic carbon to carbonate
•Behaviors and fates of soil OC and fossil OC in the Yellow River mouth were studied.•Terrigenous OC accumulation is controlled by hydrodynamic processes.•The relative contribution of terrigenous OC ...ranges from 14% to 57% in Laizhou Bay.•On average, 58% fossil OC exported by the Yellow River is lost during deposition.
Organic geochemical studies of surface sediments from Laizhou Bay, the Yellow River mouth, northeast China, were conducted to reveal the sources, distributions, and burial efficiency of terrigenous OC exported by the Yellow River. Bulk OC contents and δ13Corg values from 204 samples show that terrigenous OC mainly accumulates in two muddy patches, basically controlled by hydrodynamic conditions. Distributions and stable carbon isotopic compositions of individual n-alkanes from 45 samples suggest that short-chain n-alkanes, with even carbon-number predominance, are most likely microbial products from degradation of riverine fossil OC, whereas long-chain odd-numbered n-alkanes (n-C27, n-C29 and n-C31) and long-chain even-numbered n-alkanes (n-C26,n-C28 and n-C30) are representative of riverine soil OC and fossil OC, respectively. Integrated with previous reports of ∼100% burial efficiency of soil OC in the Yellow River mouth, concentration ratios of n-C27+29+31 to OC and n-C26+28+30 to n-C27+29+31 from the riverine particles to surface sediments in Laizhou Bay were constructed to indicate relative terrigenous OC contributions and fossil OC burial efficiency, respectively. The results suggest that the terrigenous OC contribution ranges from 14% to 57% in Laizhou Bay, with the highest values in the two muddy patches as well as in areas near the river mouth. The fossil OC burial efficiency ranges from 36% to 76%, with an TOC-weighted mean value of 42%. The 58% fossil OC lost during the transport and burial processes in the Yellow River mouth may provide a significant CO2 source.
•After 15 cycles of F-T cycling, PGS with fibers had a weight loss less than those without fibers.•The losses in flexural strength and anti-impact work of PGS are due to water softening ...reduced.•Major hydration products in PGS are C-S-H and AFt. They may be a major cause during PGS expansion.•At optimal fiber content, performance of PGS with PP fiber is better than mineral and glass fibers.
Cementitious materials made primarily with phosphogypsum (PG) and ground-granulated blast-furnace slag (GGBFS, or slag) are studied. Mineral, glass and polypropene (PP) fibers with various dosages are incorporated into this PG-slag (PGS) system. The anti-impact work, flexural strength, and freeze-thaw (F-T) resistance of these fiber-reinforced PGS mixes are evaluated, and the microstructures of these fiber-reinforced PGS mixes are also examined. The results show that addition of any of these fibers can significantly increase the flexural strength, anti-impact work, water resistance, and freezing-thawing resistance of PGS. Among the three fibers studied, the PP fiber is the easiest to disperse, and it also has a good bond with the PGS matrix. Addition of 1.35% (by volume) of the PP fiber has increased the flexural strength of the PGS twice and increased the anti-impact work up to 7 times. At the optimal fiber content, the PP fiber provides a better overall performance than mineral and glass fibers.
PDF
