94 research outputs found
Modelling study of transport time scales for a hyper-tidal estuary
This paper presents a study of two transport timescales (TTS), i.e., the residence time and exposure time, of a hyper-tidal estuary using a widely used numerical model. The numerical model was calibrated against field measured data for various tidal conditions. The model simulated current speeds and directions generally agreed well with the field data. The model was then further developed and applied to study the two transport timescales, namely the exposure time and residence time for the hyper-tidal Severn Estuary. The numerical model predictions showed that the inflow from the River Severn under high flow conditions reduced the residence and exposure times by 1.5 to 3.5% for different tidal ranges and tracer release times. For spring tide conditions, releasing a tracer at high water reduced the residence time and exposure time by 49.0% and 11.9%, respectively, compared to releasing the tracer at low water. For neap tide conditions, releasing at high water reduced the residence time and exposure time by 31.6% and 8.0%, respectively, compared to releasing the tracer at low water level. The return coefficient was found to be vary between 0.75 and 0.88 for the different tidal conditions, which indicates that the returning water effects for different tidal ranges and release times are all relatively high. For all flow and tide conditions, the exposure times were significantly greater than the residence times, which demonstrated that there was a high possibility for water and/or pollutants to re-enter the Severn Estuary after leaving it on an ebb tide. The fractions of water and/or pollutants re-entering the estuary for spring and neap tide conditions were found to be very high, giving 0.75–0.81 for neap tides, and 0.79–0.88 for spring tides. For both the spring and neap tides, the residence and exposure times were lower for high water level release. Spring tide conditions gave significantly lower residence and exposure times. The spatial distribution of exposure and residence times showed that the flow from the River Severn only had a local effect on the upstream part of the estuary, for both the residence and exposure time
MaNGA DynPop – III. Stellar dynamics versus stellar population relations in 6000 early-type and spiral galaxies: Fundamental Plane, mass-to-light ratios, total density slopes, and dark matter fractions
We present dynamical scaling relations, combined with the stellar population properties, for a subsample of about 6000 nearbygalaxies with the most reliable dynamical models extracted from the full Mapping Nearby Galaxies at Apache Point Observatory(MaNGA) sample of 10 000 galaxies. We show that the inclination-corrected mass plane for both early-type galaxies (ETGs) andlate-type galaxies (LTGs), which links dynamical mass, projected half-light radius Re, and the second stellar velocity momentσe within Re, satisfies the virial theorem and is even tighter than the uncorrected one. We find a clear parabolic relation betweenlg(M/L)e, the total mass-to-light ratio (M/L) within a sphere of radius Re, and lg σe, with the M/L increasing with σe andfor older stellar populations. However, the relation for ETGs is linear and the one for the youngest galaxies is constant. Weconfirm and improve the relation between mass-weighted total density slopes γT and σe: γT become steeper with increasingσe until lg(σe/km s−1) ≈ 2.2 and then remain constant around γT ≈ 2.2. The γT –σe variation is larger for LTGs than ETGs. Atfixed σe the total density profiles steepen with galaxy age and for ETGs. We find generally low dark matter fractions, medianfDM(<Re) = 8 per cent, within a sphere of radius Re. However, we find that fDM(<Re) depends on σe better than stellar mass:dark matter increases to a median fDM(<Re) = 33 per cent for galaxies with σe 100 km s−1. The increased fDM(<Re) at lowσe explains the parabolic lg(M/L)e– lg σe relation
Jiamusi Pulsar Observations: II. Scintillations of 10 Pulsars
Context. Pulsars scintillate. Dynamic spectra show brightness variation of
pulsars in the time and frequency domain. Secondary spectra demonstrate the
distribution of fluctuation power in the dynamic spectra. Aims. Dynamic spectra
strongly depend on observational frequencies, but were often observed at
frequencies lower than 1.5 GHz. Scintillation observations at higher
frequencies help to constrain the turbulence feature of the interstellar medium
over a wide frequency range and can detect the scintillations of more distant
pulsars. Methods. Ten pulsars were observed at 2250 MHz (S-band) with the
Jiamusi 66 m telescope to study their scintillations. Their dynamic spectra
were first obtained, from which the decorrelation bandwidths and time scales of
diffractive scintillation were then derived by autocorrelation. Secondary
spectra were calculated by forming the Fourier power spectra of the dynamic
spectra. Results. Most of the newly obtained dynamic spectra are at the highest
frequency or have the longest time span of any published data for these
pulsars. For PSRs B0540+23, B2324+60 and B2351+61, these were the first dynamic
spectra ever reported. The frequencydependence of scintillation parameters
indicates that the intervening medium can rarely be ideally turbulent with a
Kolmogorov spectrum. The thin screen model worked well at S-band for the
scintillation of PSR B1933+16. Parabolic arcs were detected in the secondary
spectra of three pulsars, PSRs B0355+54, B0540+23 and B2154+40, all of which
were asymmetrically distributed. The inverted arclets of PSR B0355+54 were seen
to evolve along the main parabola within a continuous observing session of 12
hours, from which the angular velocity of the pulsar was estimated that was
consistent with the measurement by very long baseline interferometry (VLBI).Comment: 15 pages, 19 figures. Accepted for publication in A&
Cytotoxic necrotizing factor 1 promotes bladder cancer angiogenesis through activating RhoC
Uropathogenic Escherichia coli (UPEC), a leading cause of urinary tract infections, is associated with prostate and bladder cancers. Cytotoxic necrotizing factor 1 (CNF1) is a key UPEC toxin; however, its role in bladder cancer is unknown. In the present study, we found CNF1 induced bladder cancer cells to secrete vascular endothelial growth factor (VEGF) through activating Ras homolog family member C (RhoC), leading to subsequent angiogenesis in the bladder cancer microenvironment. We then investigated that CNF1- mediated RhoC activation modulated the stabilization of hypoxia- inducible factor 1α (HIF1α) to upregulate the VEGF. We demonstrated in vitro that active RhoC increased heat shock factor 1 (HSF1) phosphorylation, which induced the heat shock protein 90α (HSP90α) expression, leading to stabilization of HIF1α. Active RhoC elevated HSP90α, HIF1α, VEGF expression, and angiogenesis in the human bladder cancer xenografts. In addition, HSP90α, HIF1α, and VEGF expression were also found positively correlated with the human bladder cancer development. These results provide a potential mechanism through which UPEC contributes to bladder cancer progression, and may provide potential therapeutic targets for bladder cancer.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155984/1/fsb220522.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155984/2/fsb220522-sup-0001-Supinfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155984/3/fsb220522_am.pd
Screening and Degradation Characteristics of a Fumonisin B1-Degrading Fungal Strain
A fungal strain capable of degrading fumonisin B1 (FB1) from ground maize samples heavily contaminated with fumonisin was obtained by enrichment culture method. The strain was named as FDS-2, and was characterized for its growth and degradation characteristics, and the initial degradation pathway of FB1 by FDS-2 was investigated. The strain was identified as Exophiala spinifera according to its culture characteristics, microscopic characteristics and phylogenetic tree based on RNA-internal transcribed spacer (ITS) sequence characteristics. The optimum growth and degradation conditions were 30 ℃ and pH 5.0. Under these conditions, the strain could completely degrade 250 μg of FB1 within 48 h. Intracellular FB1-degrading enzymes were discovered in this strain. Using liquid chromatography-mass spectrometry (LC-MS) to analyze the degradation products, it was determined that the primary degradation pathway began with the degradation of FB1 into hydrolyzed FB1. This study provides a strain resource and a theoretical basis for the biodegradation of fumonisin in grain and feed
SDSS-IV MaNGA: the inner density slopes of nearby galaxies
We derive the mass-weighted total density slopes within the effective (half-light) radius, γ′, for more than 2000 nearby galaxies from the SDSS-IV (Sloan Digital Sky Survey IV) MaNGA survey using Jeans-anisotropic-models applied to integral field unit observations. Our galaxies span a wide range of the stellar mass (109 M⊙ 100 km s−1, the density slope has a mean value 〈γ′〉 = 2.24 and a dispersion σγ = 0.22, almost independent of velocity dispersion, consistent with previous lensing and stellar dynamical analysis. We also quantitatively confirm with high accuracy a turnover in the γ′–σv relation is present at σ ∼ 100 km s−1, below which the density slope decreases rapidly with σv, consistent with the results reported by previous analysis of ATLAS3D survey. Our analysis shows that a large fraction of dwarf galaxies (below M* = 1010 M⊙) have total density slopes shallower than 1, which implies that they may reside in cold dark matter haloes with shallow density slopes. We compare our results with that of galaxies in hydrodynamical simulations of EAGLE, Illustris, and IllustrisTNG projects, and find all simulations predict shallower density slopes for massive galaxies with high σv. Finally, we explore the dependence of γ′ on the positions of galaxies in haloes, namely centrals versus satellites, and find that for the same velocity dispersion, the amplitude of γ′ is higher for satellite galaxies by about 0.1
MicroRNA-197 Promotes Metastasis of Hepatocellular Carcinoma by Activating Wnt/β-Catenin Signaling
Background/Aims: MicroRNA-197 (miR-197) has been shown to play roles in epithelialmesenchymal transition (EMT) and metastasis. The Wnt/β-catenin pathway is associated with EMT, but whether miR-197 regulatesWnt/β-catenin remains unclear. This study was to demonstrate the role of miR-197 on the Wnt/β-catenin pathway in hepatocellular carcinoma (HCC). Methods: Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect the expression of miR-197 in 105 HCC specimens and 15 HCC cell lines. We tested the predicted target gene of miR-197 using a genetic report system. The role of miR-197 in HCC cell invasion and migration (wound healingand cell invasion and migrationby Transwell assays) and in an HCC xenograft modelwas analyzed. Results: Using a miRNA microarray analysis of HCC specimens and compared with non-metastatic HCC, miR-197 was identified as one of the most upregulated miRNAs in metastatic HCC. miR-197 expression was positively associated with the invasiveness of HCC cell lines. Metastatic HCC cells with high miR-197 expression had Wnt/β-catenin signaling activation. High levels of miR-197 expression also promoted EMT and invasionHCC cells in vitro and in vivo. miR-197 directly targeted Axin-2, Naked cuticle 1 (NKD1), and Dickkopf-related protein 2 (DKK2), leading to inhibition of Wnt/β-catenin signaling. High miR-197 expression was found in HCC specimens from patients with portal vein metastasis;high miR-197 expression correlated to the expression of Axin2, NKD1, and DKK2. Conclusion: miR-197 promotes HCC invasion and metastasis by activating Wnt/β-catenin signaling. miR-197 could possibly be used as a prognostic marker and therapeutic target for HCC
Occurrence and characterization of NDM-5-producing Escherichia coli from retail eggs
The New Delhi Metallo-β-lactamase (NDM) producing Enterobacterales has been detected from diverse sources but has rarely been reported in retail eggs. In this study, 144 eggshell and 96 egg content samples were collected in 2022 from Guangdong province and were screened for NDM-producing strains. Four Escherichia coli strains (ST3014, ST10, ST1485, and ST14747) recovered from two (1.39%, 2 of 144) eggshells and two (2.08%, 2 of 96) egg content samples were identified as blaNDM−5-positive strains. Oxford Nanopore MinION sequencing and conjugation assays revealed that the blaNDM−5 gene was carried by IncX3 (n = 1), IncI1 (n = 1), and IncHI2 (n = 2). The IncI1-plasmid-carrying blaNDM−5 displayed high homology with one plasmid pEC6563-NDM5 from the human clinic, while the IncHI2 plasmid harboring blaNDM−5 shared highly similar structures with plasmids of animal origin. To the best of our knowledge, this is the first report on the identification of blaNDM−5-positive bacteria in retail eggs. NDM-producing E. coli could be transmitted to humans by the consumption of eggs or direct contact, which could pose a potential threat to human health
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