57 research outputs found
Implications of global carbon governance for corporate carbon emissions reduction
Global warming not only affects biodiversity, but also threatens human health and wellbeing. As the main source of greenhouse gas emissions, enterprises play a critical role in carbon emissions reduction. However, only a small number of enterprises have disclosed their âlow-carbon transition roadmapâ, primarily due to the lack of immediate payoffs of green investment, which is disadvantageous to achieve net-zero emissions. First, through case analysis of carbon governance in typical countries around the world, we identify effective emissions reduction measures that firms can learn from. Next, this paper summarizes the multi-dimensional impact framework of corporate carbon emissions reduction. Last, we propose a carbon emissions reduction roadmap for companies from four aspects: companies should 1) actively engage in the carbon emissions trading system, 2) increase the application of green technology, 3) enhance corporate governance structure, and 4) ensure sufficient cash flow for low-carbon transition. This study contributes to the framework of corporate sustainable transition, providing practical references for balancing corporate environmental footprint and value growth
The SUPERCOLD-CGM survey: \\ I. Probing the extended CO(4-3) Emission of the Circumglactic medium in a sample of 10 Enormous Ly Nebulae at
To understand how massive galaxies at high- co-evolve with enormous
reservoirs of halo gas, it is essential to study the coldest phase of the
circum-galactic medium (CGM), which directly relates to stellar growth. The
SUPERCOLD-CGM survey is the first statistical survey of cold molecular gas on
CGM scales. We present ALMA+ACA observations of CO(4-3) and continuum emission
from 10 Enormous Ly Nebula (ELANe) around ultraluminous type-I QSOs at
. We detect CO(4-3) in 100 of our targets, with 60 showing
extended CO on scales of 15100 kpc. Q1228+3128 reveals the most extended
CO(4-3) reservoir of 100 kpc and is the only radio-loud target in our
sample. The CO reservoir is located along the radio axis, which could indicate
a link between the inner radio-jet and cold halo gas. For the other five
radio-quiet ELANe, four of them show extended CO(4-3) predominantly in the
direction of their companions. These extended CO(4-3) reservoirs identify
enrichment of the CGM, and may potentially contribute to widespread star
formation. However, there is no evidence from CO(4-3) for diffuse molecular gas
spread across the full extent of the Ly nebulae. One target in our
sample (Q0107) shows significant evidence for a massive CO disk associated with
the QSO. Moreover, 70 of our QSO fields contain at least one CO companion,
two of which reveal extended CO emission outside the ELANe. Our results provide
insight into roles of both the cold CGM and companions in driving the early
evolution of massive galaxies.Comment: Accepted for publication in ApJ. 27 pages, 16 figure
The Mass-Metallicity Relation of Dwarf Galaxies at the Cosmic Noon in the JWST Era
We present the mass-metallicity relation (MZR) at in the stellar mass
range of using 55 dwarf galaxies in
the Abell 2744 and SMACS J0723-3732 galaxy cluster fields. These dwarf galaxies
are identified and confirmed by deep JWST/NIRISS imaging and slitless grism
spectroscopic observations. Taking advantage of the gravitational lensing
effect, we extend the previous MZR relation at to a much lower mass
regime by more than 2.5 orders of magnitude compared with previous studies. We
find that the MZR has a shallower slope at the low-mass end
() compared to that at the high-mass end
(), with a slope turnover point at around the stellar
mass of . This implies that dominating feedback processes in
dwarf galaxies may be different from that in galaxies with higher mass. From
to , the metallicity of the dwarf galaxies is enhanced by
dex for a given stellar mass, consistent with the mild evolution
found in galaxies with higher mass. Further, we confirm the existence of a 3D
relation between the gas-phase metallicity, stellar mass, and star formation
rate, i.e., fundamental metallicity relation (FMR), in dwarf galaxies at
. Our derived FMR, which has no significant redshift evolution, can be
used as a benchmark to understand the origin of the anti-correlation between
SFR and metallicity of dwarf galaxies in the high-redshift Universe.Comment: 16 pages, 4 figures, 1 table, submitted to AAS Journal; welcome
comment
Searching for C ii Emission from the First Sample of z ⌠6 O i Absorption-associated Galaxies with the Atacama Large Millimeter/submillimeter Array
We report the first statistical analyses of [C ii ] and dust continuum observations in six strong O i absorber fields at the end of the reionization epoch obtained by the Atacama Large Millimeter/submillimeter Array (ALMA). Combined with one [C ii ] emitter reported in Wu et al., we detect one O i -associated [C ii ] emitter in six fields. At redshifts of O i absorbers in nondetection fields, no emitters are brighter than our detection limit within impact parameters of 50 kpc and velocity offsets between ±200 km s ^â1 . The averaged [C ii ]-detection upper limit is 50 kpc) and having larger outflow velocities within ±600 km s ^â1 . If these detections are confirmed in the future, then the mechanism of pushing metals at larger distances with higher velocities needs to be further explored from the theoretical side
Metal-Enriched Neutral Gas Reservoir around a Strongly-lensed, Low-mass Galaxy at Identified by JWST/NIRISS and VLT/MUSE
Direct observations of low-mass, low-metallicity galaxies at
provide an indispensable opportunity for detailed inspection of the ionization
radiation, gas flow, and metal enrichment in sources similar to those that
reionized the Universe. Combining the James Webb Space Telescope (JWST),
VLT/MUSE, and ALMA, we present detailed observations of a strongly lensed,
low-mass ( ) galaxy at (also see
Vanzella et al. 2022). We identify strong narrow nebular emission, including
CIV , HeII , OIII]
, [NeIII] , [OII] , and
Balmer series of Hydrogen from this galaxy, indicating a metal-poor HII region
() powered by massive stars. Further, we detect a
metal-enriched damped Ly system (DLA) associated with the galaxy with
the HI column density of cm. The
metallicity of the associated DLA may reach the super solar metallicity
(). Moreover, thanks to JWST and gravitational lensing, we
present the resolved UV slope () map at the spatial resolution of
pc at , with steep UV slopes reaching
around three star-forming clumps. Combining with low-redshift analogs, our
observations suggest that low-mass, low-metallicity galaxies, which dominate
reionization, could be surrounded by a high covering fraction of the
metal-enriched, neutral-gaseous clouds. This implies that the metal enrichment
of low-mass galaxies is highly efficient, and further support that in low-mass
galaxies, only a small fraction of ionizing radiation can escape through the
interstellar or circumgalactic channels with low column-density neutral gas.Comment: 4 pages, 1 table; submitted to the ApJL; welcome comment
A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): JWST Reveals a Filamentary Structure around a z = 6.61 Quasar
© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/We present the first results from the JWST program A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE). This program represents an imaging and spectroscopic survey of 25 reionization-era quasars and their environments by utilizing the unprecedented capabilities of NIRCam Wide Field Slitless Spectroscopy (WFSS) mode. ASPIRE will deliver the largest ( âŒ280arcmin2 ) galaxy redshift survey at 3â4 ÎŒm among JWST Cycle 1 programs and provide extensive legacy values for studying the formation of the earliest supermassive black holes, the assembly of galaxies, early metal enrichment, and cosmic reionization. In this first ASPIRE paper, we report the discovery of a filamentary structure traced by the luminous quasar J0305â3150 and 10 [O iii] emitters at z = 6.6. This structure has a 3D galaxy overdensity of ÎŽ gal = 12.6 over 637 cMpc3, one of the most overdense structures known in the early universe, and could eventually evolve into a massive galaxy cluster. Together with existing VLT/MUSE and ALMA observations of this field, our JWST observations reveal that J0305â3150 traces a complex environment where both UV-bright and dusty galaxies are present and indicate that the early evolution of galaxies around the quasar is not simultaneous. In addition, we discovered 31 [O iii] emitters in this field at other redshifts, 5.3 < z < 6.7, with half of them situated at z ⌠5.4 and 6.2. This indicates that star-forming galaxies, such as [O iii] emitters, are generally clustered at high redshifts. These discoveries demonstrate the unparalleled redshift survey capabilities of NIRCam WFSS and the potential of the full ASPIRE survey data set.Peer reviewe
A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of z > 6.5 Quasars Using JWST
© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/Studies of rest-frame optical emission in quasars at z > 6 have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at z > 6.5 using the JWST/NIRCam Wide Field Slitless Spectroscopy as a part of the âA SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)â program. Our JWST spectra cover the quasarsâ emission between rest frame âŒ4100 and 5100 Ă
. The profiles of these quasarsâ broad HÎČ emission lines span a full width at half maximum from 3000 to 6000 km sâ1. The HÎČ-based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their Mg ii-based BH masses. The new measurements based on the more reliable HÎČ tracer thus confirm the existence of a billion solar-mass BHs in the reionization epoch. In the observed [O iii] λ λ 4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components (†1200 km sâ1), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [O iii] emission, thought to trace galactic-scale outflows, with median velocities of â610 and â1430 km sâ1 relative to the [C ii] 158 ÎŒm line. All eight quasars show strong optical Fe ii emission and follow the eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.Peer reviewe
Can independent directors identify the companyâs risk of financial fraud: Evidence from predicting financial fraud based on machine learning
ABSTRACTCombining the companyâs risk of financial fraud predicted by the machine learning method and unique Chinese data of board voting, this study investigates whether independent directors can identify the companyâs risk of financial fraud. We find that independent directors are more likely to express dissenting opinions on boardâs financial-related proposals when the company has a higher risk of financial fraud; this impact is more pronounced when independent directors have more financial backgrounds or higher reputations. Further study shows that companies with independent directorsâ dissension have a lower risk of financial fraud in the future after controlling the risk of financial fraud in the current year. Our findings indicate that independent directors can identify the companyâs risk of financial fraud and play as a supervisor, thereby reducing the probability of the companyâs future financial fraud. Our findings provide direct empirical evidence for the effectiveness of the independent director system and enhance our understanding of independent directorsâ actual voting behaviour
A Method for Screening Climate Change-Sensitive Infectious Diseases
Climate change is a significant and emerging threat to human health, especially where infectious diseases are involved. Because of the complex interactions between climate variables and infectious disease components (i.e., pathogen, host and transmission environment), systematically and quantitatively screening for infectious diseases that are sensitive to climate change is still a challenge. To address this challenge, we propose a new statistical indicator, Relative Sensitivity, to identify the difference between the sensitivity of the infectious disease to climate variables for two different climate statuses (i.e., historical climate and present climate) in non-exposure and exposure groups. The case study in Anhui Province, China has demonstrated the effectiveness of this Relative Sensitivity indicator. The application results indicate significant sensitivity of many epidemic infectious diseases to climate change in the form of changing climatic variables, such as temperature, precipitation and absolute humidity. As novel evidence, this research shows that absolute humidity has a critical influence on many observed infectious diseases in Anhui Province, including dysentery, hand, foot and mouth disease, hepatitis A, hemorrhagic fever, typhoid fever, malaria, meningitis, influenza and schistosomiasis. Moreover, some infectious diseases are more sensitive to climate change in rural areas than in urban areas. This insight provides guidance for future health inputs that consider spatial variability in response to climate change
Mesoporous silica dispersed Co3O4-CuO nanocomposite and its catalytic reduction of 4-nitrophenol
Herein, a catalyst Co _3 O _4 -CuO nanocomposite uniformly dispersed on mesoporous silica nanospheres (MSN) has been successfully synthesized through hydrothermal method. The synthesis method is simple and convenient, the prepared Co _3 O _4 -CuO nanocomposites have high dispersibility, and the support SiO _2 maintains the structure of mesoporous nanospheres. Whatâs more, the porous structure enables the obtained composite to have a high specific surface area (128.89 m ^2 g ^â1 ), which is easier to be contacted by catalytic substrates. The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was investigated. The results show that the nanocomposite catalyst Co _3 O _4 -CuO@MSN present good catalytic performance, which can completely convert 4-NP to 4-AP in 200 s and the reaction rate constant k is up to 0.149 s ^â1 . More important, the possible degradation mechanism was also proposed in the paper
- âŠ