59 research outputs found
Environmental impact of the tourism industry in China: analyses based on multiple environmental factors using novel Quantile Autoregressive Distributed Lag model
This study examines the impact of tourism on China’s environmental quality under the framework of the Environment Kuznets
Curve. In this study, tourism is measured by the number of tourist
arrival and environmental pollution is measured by three proxies:
carbon emissions, atmospheric particulate matter, and greenhouse
gases. The study additionally controls trade openness effects
using annual data from 1995 to 2018. Based on the asymmetric
behavior of environmental variables, the study applies the
Quantile Autoregressive Distributed Lag model that helps to integrate both dynamic trends and non-linearity. The findings confirmed the validity of Environment Kuznets in the long run and
unveiled that tourist arrivals reduce carbon emissions, atmospheric particulate matter, and greenhouse gases in the long run,
but in short-run dynamics, tourist arrivals only reduce carbon
emissions. Similarly, trade openness increases carbon emissions,
atmospheric particulate matter, and greenhouse gases at initial
quantiles in the long run. In contrast, in the case of the short run,
trade openness reduces atmospheric particulate matter and
greenhouse gases. These results imply that the emissions mitigating (contributing) effects of tourism and trade varied across lower
and higher quantiles. In conclusion, the findings reveal that the
government should take effective measures to implement appropriate strategies required to sustain tourism and trade in China
Cytotoxic activity of lithospermum erythrorhizon root extract against childhood acute leukemia cells via regulation of PI3K/AKT/mTOR pathway
Purpose: To investigate the effect and mechanism of action of Lithospermum erythrorhizon root extract (LR) in childhood acute leukemia.
Methods: Human leukemic lymphoblast (CCRF-CEM cell line) cells were treated with LR (2, 4, and 8 mg/mL). Cell viability, cell apoptosis and cell cycle were measured using 3-(4,5-dimethylthiazol-2- thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. The levels of cell-cycle-related proteins including cyclin D1, cyclin E1, cyclin-dependent kinase 2 (CDK2), CDK4 and CDK6, as well as cleaved caspase 3, cleaved caspase 9 and Bcl-2-associated x (Bax). Also determined were B-cell lymphoma-2 (Bcl-2), E-cadherin, N-cadherin, vimentin, zonula occludens 1 (ZO-1), matrix metalloproteinase-2 (MMP-2) and MMP-9. Cell migration and invasion were assessed using scratch and Transwell assays. Finally, phosphoinositide 3-kinase (PI3K), phosphorylated serine/threonine kinase (pAKT), total AKT (t-AKT), mammalian target of rapamycin (mTOR), and phosphorylated mTOR (pmTOR) were measured using western blotting.
Results: Lithospermum erythrorhizon root extract not only dose-dependently inhibited cell viability, induced G1 phase accumulation, and downregulated CDK2, CDK4, CDK6, cyclin D1, and cyclin E1, but also elevated apoptosis, cleaved caspase 3, cleaved caspase 9, and Bax and decreased Bcl-2 expression levels. In addition, Lithospermum erythrorhizon root extract suppressed migration and invasion of CCRF-CEM cells, downregulated N-cadherin, vimentin, MMP-2, and MMP-9, and upregulated E-cadherin and ZO-1. Moreover, Lithospermum erythrorhizon root extracts dosedependently inhibited PI3K, p-AKT (ser473)/t-AKT, p-mTOR (ser2448)/mTOR, and p-mTOR (ser2481)/mTOR.
Conclusion: The findings provide a potential therapeutic approach to the treatment of childhood acute leukemia
Velocity Dispersion Aperture Corrections as a Function of Galaxy Properties from Integral-field Stellar Kinematics of 10,000 MaNGA Galaxies
The second moment of the stellar velocity within the effective radius,
denoted by , is a crucial quantity in galaxy studies as it
provides insight into galaxy properties and their mass distributions. However,
large spectroscopic surveys typically do not measure directly,
instead providing , the second moment of the stellar
velocity within a fixed fiber aperture. In this paper, we derive an empirical
aperture correction formula, given by , using spatially resolved stellar kinematics
extracted from approximately 10,000 Sloan Digital Sky Survey-Mapping Nearby
Galaxies at Apache Point Observatory (SDSS-MaNGA) integral field unit
observations. Our analysis reveals a strong dependence of on the
-band absolute magnitude , color, and Sersic index , where values are lower for brighter, redder galaxies with
higher Sersic indices. Our results demonstrate that the aperture correction
derived from previous literature on early-type galaxies cannot be applied to
predict the aperture corrections for galaxies with intermediate Sersic indices.
We provide a lookup table of values for different galaxy types, with
parameters in the ranges of , , and . A Python script is provided to obtain the correction factors from the
lookup table.Comment: 12 pages, 10 figures, 1 table, published in Research in Astronomy and
Astrophysic
MaNGA DynPop -- V. The dark-matter fraction versus stellar velocity dispersion relation and initial mass function variations: dynamical models and full spectrum fitting of integral-field spectroscopy
Using the final MaNGA sample (DR17) of 10K galaxies, we investigate the dark
matter fraction within one half-light radius for about
6K galaxies with good kinematics spanning a wide range of morphologies and
stellar velocity dispersion (). We employ two techniques to estimate
: (i) Jeans Anisotropic Modelling (JAM), which performs dark matter
decomposition based on the stellar kinematics and (ii) comparing the total
dynamical mass-to-light ratios and the from Stellar Population Synthesis (SPS). We find that both methods
consistently show a significant trend of increasing with
decreasing , for and very low at larger
. For the 235 early-type galaxies with the best dynamical
models, we explore the variation of the stellar initial mass function (IMF) by
comparing the stellar mass-to-light ratios from JAM
and SPS. We confirm that the stellar mass excess , which reflects the IMF shape,
increases with , in agreement with previous studies that
reported a transition from Chabrier-like to Salpeter IMF among galaxies. We
also detect weak positive correlations between and age, but
no correlations with metallicity (). Finally, we stack galaxy spectra
according to their to search for differences in
IMF-sensitive spectral features (e.g. the doublet). We only
find marginal evidence for such differences, which casts doubt on the validity
of one or both methods to measure the IMF.Comment: 17 pages, 9 figures, 2 tables; Submitted to MNRAS on 21 September
202
A complete catalogue of broad-line AGNs and double-peaked emission lines from MaNGA integral-field spectroscopy of 10K galaxies: stellar population of AGNs, supermassive black holes, and dual AGNs
We analyse the integral-field spectroscopy data for the
galaxies in final data release of the MaNGA survey. We identify 188 galaxies
for which the emission lines cannot be described by single Gaussian components.
These galaxies can be classified into (1) 38 galaxies with broad and
[OIII] 5007 lines, (2) 101 galaxies with broad lines but no
broad [OIII] 5007 lines, and (3) 49 galaxies with double-peaked narrow
emission lines. Most of the broad line galaxies are classified as Active
Galactic Nuclei (AGN) from their line ratios. The catalogue helps us further
understand the AGN-galaxy coevolution through the stellar population of
broad-line region host galaxies and the relation between broad lines'
properties and the host galaxies' dynamical properties. The stellar population
properties (including mass, age and metallicity) of broad-line host galaxies
suggest there is no significant difference between narrow-line Seyfert-2
galaxies and Type-1 AGN with broad lines. We use the broad-
line width and luminosity to estimate masses of black hole in these galaxies,
and test the relation in Type-1 AGN host galaxies.
Furthermore we find three dual AGN candidates supported by radio images from
the VLA FIRST survey. This sample may be useful for further studies on AGN
activities and feedback processes.Comment: 21 pages, 17 figures, LaTeX. Accepted by MNRA
MaNGA DynPop -- I. Quality-assessed stellar dynamical modelling from integral-field spectroscopy of 10K nearby galaxies: a catalogue of masses, mass-to-light ratios, density profiles and dark matter
This is the first paper in our series on the combined analysis of the
Dynamics and stellar Population (DynPop) for the MaNGA survey in the final SDSS
Data Release 17 (DR17). Here we present a catalogue of dynamically-determined
quantities for over 10000 nearby galaxies based on integral-field stellar
kinematics from the MaNGA survey. The dynamical properties are extracted using
the axisymmetric Jeans Anisotropic Modelling (JAM) method, which was previously
shown to be the most accurate for this kind of study. We assess systematic
uncertainties using eight dynamical models with different assumptions. We use
two orientations of the velocity ellipsoid: either cylindrically-aligned
JAM or spherically-aligned JAM. We also make four
assumptions for the models' dark vs. luminous matter distributions: (1)
mass-follows-light, (2) free NFW dark halo, (3) cosmologically-constrained NFW
halo, (4) generalized NFW dark halo, i.e. with free inner slope. In this
catalogue, we provide the quantities related to the mass distributions (e.g.
the density slopes and enclosed mass within a sphere of a given radius for
total mass, stellar mass, and dark matter mass components). We also provide the
complete models which can be used to compute the full luminous and mass
distribution of each galaxy. Additionally, we visually assess the qualities of
the models to help with model selections. We estimate the observed scatter in
the measured quantities which decreases as expected with improvements in
quality. For the best data quality, we find a remarkable consistency of
measured quantities between different models, highlighting the robustness of
the results.Comment: 30 pages, 15 figures, 4 tables, accepted by MNRAS, the catalogue is
available here https://manga-dynpop.github.io
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
MaNGA DynPop – VI. Matter density slopes from dynamical models of 6000 galaxies versus cosmological simulations: the interplay between baryonic and dark matter
We try to understand the trends in the mass density slopes as a function of
galaxy properties. We use the results from the best Jeans Anisotropic Modelling
(JAM) of the integral-field stellar kinematics for near 6000 galaxies from the
MaNGA DynPop project, with stellar masses of ,
including both early-type and late-type galaxies. We use the mass-weighted
density slopes for the stellar , dark
, and total mass from
the MaNGA DynPop project. The approaches a constant
value of 2.2 for high galaxies, and flattens for
lg, reaching 1.5 for
lg. The total and stellar slopes
track each other tightly, with over the full range. This
confirms the dominance of stellar matter within . We also show that
there is no perfect conspiracy between baryonic and dark matter, as
and do not vary inversely
within the range. We find that the central galaxies from TNG50
and TNG100 simulations do not reproduce the observed galaxy mass distribution,
which we attribute to the overestimated dark matter fraction, possibly due to a
constant IMF and excessive adiabatic contraction effects in the simulations.
Finally, we present the stacked dark matter density profiles and show that they
are slightly steeper than the pure dark matter simulation prediction of
, suggesting moderate adiabatic contraction
in the central region of galaxies. Our work demonstrate the power of stellar
dynamics modelling for probing the interaction between stellar and dark matter
and testing galaxy formation theories.Comment: 17 pages, 14 figures; accepted by MNRA
Can lignocellulosic hydrocarbon liquids rival lignocellulose-derived ethanol as a future transport fuel?
Although transport fuels are currently obtained mainly from petroleum, alternative fuels derived from lignocellulosic biomass (LB) have drawn much attention in recent years in light of the limited reserves of crude oil and the associated environmental issues. Lignocellulosic ethanol (LE) and lignocellulosic hydrocarbons (LH) are two typical representatives of the LB-derived transport fuels. This editorial systematically compares LE and LB from production to their application in transport fuels. It can be demonstrated that LH has many advantages over LE relative to such uses. However, most recent studies on the production of the LB-derived transport fuels have focused on LE production. Hence, it is strongly recommended that more research should be aimed at developing an efficient and economically viable process for industrial LH production
Significance of cuproptosis- related genes in the diagnosis and classification of psoriasis
Cuproptosis is a novel form of cell death linked to mitochondrial metabolism and is mediated by protein lipoylation. The mechanism of cuproptosis in many diseases, such as psoriasis, remains unclear. In this study, signature diagnostic markers of cuproptosis were screened by differential analysis between psoriatic and non-psoriatic patients. The differentially expressed cuproptosis-related genes (CRGs) for patients with psoriasis were screened using the GSE178197 dataset from the gene expression omnibus database. The biological roles of CRGs were identified by GO and KEGG enrichment analyses, and the candidates of cuproptosis-related regulators were selected from a nomogram model. The consensus clustering approach was used to classify psoriasis into clusters and the principal component analysis algorithms were constructed to calculate the cuproptosis score. Finally, latent diagnostic markers and drug sensitivity were analyzed using the pRRophetic R package. The differential analysis revealed that CRGs (MTF1, ATP7B, and SLC31A1) are significantly expressed in psoriatic patients. GO and KEGG enrichment analyses showed that the biological functions of CRGs were mainly related to acetyl-CoA metabolic processes, the mitochondrial matrix, and acyltransferase activity. Compared to the machine learning method used, the random forest model has higher accuracy in the occurrence of cuproptosis. However, the decision curve of the candidate cuproptosis regulators analysis showed that patients can benefit from the nomogram model. The consensus clustering analysis showed that psoriasis can be grouped into three patterns of cuproptosis (clusterA, clusterB, and clusterC) based on selected important regulators of cuproptosis. In advance, we analyzed the immune characteristics of patients and found that clusterA was associated with T cells, clusterB with neutrophil cells, and clusterC predominantly with B cells. Drug sensitivity analysis showed that three cuproptosis regulators (ATP7B, SLC31A1, and MTF1) were associated with the drug sensitivity. This study provides insight into the specific biological functions and related mechanisms of CRGs in the development of psoriasis and indicates that cuproptosis plays a non-negligible role. These results may help guide future treatment strategies for psoriasis
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