The Sarbanes-Oxley Act (SOX) mandates management evaluation and independent audits of internal control effectiveness. The mandate is costly to firms but may yield benefits through lower information ...risk that translates into lower cost of equity. We use unaudited pre-SOX 404 disclosures and SOX 404 audit opinions to assess how changes in internal control quality affect firm risk and cost of equity. After controlling for other risk factors, we find that firms with internal control deficiencies have significantly higher idiosyncratic risk, systematic risk, and cost of equity. Our change analyses document that auditor-confirmed changes in internal control effectiveness (including remediation of previously disclosed internal control deficiencies) are followed by significant changes in the cost of equity that range from 50 to 150 basis points. Overall, our cross-sectional and intertemporal change test results are consistent with internal control reports affecting investors' risk assessments and firms' cost of equity.
This study was conducted to characterize metabolic features of the breast muscle (pectoralis major) in chickens affected with the Wooden Breast myopathy. Live birds from two purebred chicken lines ...and one crossbred commercial broiler population were clinically examined by manual palpation of the breast muscle (pectoralis major) at 47-48 days of age. Metabolite abundance was determined by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using breast muscle tissue samples from 16 affected and 16 unaffected chickens. Muscle glycogen content was also quantified in breast muscle tissue samples from affected and unaffected chickens. In total, levels of 140 biochemicals were significantly different (FDR<0.1 and fold-change A/U>1.3 or <0.77) between affected and unaffected chickens. Glycogen content measurements were considerably lower (1.7-fold) in samples taken from Wooden Breast affected birds when compared with samples from unaffected birds. Affected tissues exhibited biomarkers related to increased oxidative stress, elevated protein levels, muscle degradation, and altered glucose utilization. Affected muscle also showed elevated levels of hypoxanthine, xanthine, and urate molecules, the generation of which can contribute to altered redox homeostasis. In conclusion, our findings show that Wooden Breast affected tissues possess a unique metabolic signature. This unique profile may identify candidate biomarkers for diagnostic utilization and provide mechanistic insight into altered biochemical processes contributing to tissue hardening associated with the Wooden Breast myopathy in commercial chickens.
Polymerization of monomers into periodic two-dimensional networks provides structurally precise, layered macromolecular sheets that exhibit desirable mechanical, optoelectronic, and molecular ...transport properties. Two-dimensional covalent organic frameworks (2D COFs) offer broad monomer scope but are generally isolated as powders comprising aggregated nanometer-scale crystallites. We found that 2D COF formation could be controlled using a two-step procedure in which monomers are added slowly to preformed nanoparticle seeds. The resulting 2D COFs are isolated as single-crystalline, micrometer-sized particles. Transient absorption spectroscopy of the dispersed COF nanoparticles revealed improvement in signal quality by two to three orders of magnitude relative to polycrystalline powder samples, and suggests exciton diffusion over longer length scales than those obtained through previous approaches. These findings should enable a broad exploration of synthetic 2D polymer structures and properties.
Per- and polyfluorinated alkyl substances (PFAS), such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), and ammonium perfluoro-2-propoxypropionate (GenX), contaminate ground and ...surface waters throughout the world. The cost and performance limitations of current PFAS removal technologies motivate efforts to develop selective and high-affinity adsorbents. Covalent organic frameworks (COFs) are unexplored yet promising adsorbents because of their high surface area and tunable pore sizes. Here we show that imine-linked two-dimensional (2D) COFs bearing primary amines adsorb GenX rapidly at environmentally relevant concentrations. COFs with partial amine incorporation showed the highest capacity and fastest removal, suggesting that the synergistic combination of the polar group and hydrophobic surfaces are responsible for GenX binding. A COF with 28% amine loading also removed more than 90% of 12 out of 13 PFAS. These results demonstrate the promise of COFs for PFAS removal and suggest design criteria for maximizing adsorbent performance.
The simultaneous polymerization and crystallization of monomers featuring directional bonding designs provides covalent organic frameworks (COFs), which are periodic polymer networks with robust ...covalent bonds arranged in two- or three-dimensional topologies. The range of properties characterized in COFs has rapidly expanded to include those of interest for heterogeneous catalysis, energy storage and photovoltaic devices, and proton-conducting membranes. Yet many of these applications will require materials quality, morphological control, and synthetic efficiency exceeding the capabilities of contemporary synthetic methods. This level of control will emerge from an improved fundamental understanding of COF nucleation and growth processes. More powerful characterization of structure and defects, improved syntheses guided by mechanistic understanding, and accessing diverse isolated forms, ranging from single crystals to thin films to colloidal suspensions, remain important frontier problems.
Abstract
We investigate the evolution of galaxy gas-phase metallicity (O/H) over the range
z
= 0–3.3 using samples of ∼300 galaxies at
z
∼ 2.3 and ∼150 galaxies at
z
∼ 3.3 from the MOSDEF survey. ...This analysis crucially utilizes different metallicity calibrations at
z
∼ 0 and
z
> 1 to account for evolving interstellar medium (ISM) conditions. We find significant correlations between O/H and stellar mass (
M
*
) at
z
∼ 2.3 and
z
∼ 3.3. The low-mass power-law slope of the mass–metallicity relation (MZR) is remarkably invariant over
z
= 0–3.3, such that O/H ∝
at all redshifts in this range. At fixed
M
*
, O/H decreases with increasing redshift as
d
log(O/H)/
dz
= −0.11 ± 0.02. We find no evidence that the fundamental metallicity relation between
M
*
, O/H, and star formation rate evolves out to
z
∼ 3.3. We employ analytic chemical evolution models to place constraints on the mass and metal loading factors of galactic outflows. The efficiency of metal removal increases toward lower
M
*
at fixed redshift and toward higher redshift at fixed
M
*
. These models suggest that the slope of the MZR is primarily set by the scaling of the outflow metal loading factor with
M
*
, not by the change in gas fraction as a function of
M
*
. The evolution toward lower O/H at fixed
M
*
with increasing redshift is driven by both higher gas fraction (leading to stronger dilution of ISM metals) and higher metal removal efficiency. These results suggest that the processes governing the smooth baryonic growth of galaxies via gas flows and star formation hold in the same form over at least the past 12 Gyr.
Using observations from the MOSFIRE Deep Evolution Field survey, we investigate the physical conditions of star-forming regions in z ~ 2.3 galaxies, specifically the electron density and ionization ...state. From measurements of the OIIlambdalambda3726,3729 and SIIlambdalambda6716,6731 doublets, we find a median electron density of ~250 cm super(-3) at z ~ 2.3, an increase of an order of magnitude compared to measurements of galaxies at z ~ 0. While z ~ 2.3 galaxies are offset toward significantly higher O sub(32) values relative to local galaxies at fixed stellar mass, we find that the high-redshift sample follows a similar distribution to the low-metallicity tail of the local distribution in the O sub(32) versus R sub(23) and O3N2 diagrams. Based on these results, we propose that z ~ 2.3 star-forming galaxies have the same ionization parameter as local galaxies at fixed metallicity. In combination with simple photoionization models, the position of local and z ~ 2.3 galaxies in excitation diagrams suggests that there is no significant change in the hardness of the ionizing spectrum at fixed metallicity from z ~ 0 to z ~ 2.3. We find that z ~ 2.3 galaxies show no offset compared to low-metallicity local galaxies in emission line ratio diagrams involving only lines of hydrogen, oxygen, and sulfur, but show a systematic offset in diagrams involving NIIlambda6584. We conclude that the offset of z ~ 2.3 galaxies from the local star-forming sequence in the NII BPT diagram is primarily driven by elevated N/O at fixed O/H compared to local galaxies. These results suggest that the local gas-phase and stellar metallicity sets the ionization state of star-forming regions at z ~ 0 and z ~ 2.
Single-cell RNA sequencing (scRNA-seq) has become an essential tool for characterizing gene expression in eukaryotes, but current methods are incompatible with bacteria. Here, we introduce microSPLiT ...(microbial split-pool ligation transcriptomics), a high-throughput scRNA-seq method for Gram-negative and Gram-positive bacteria that can resolve heterogeneous transcriptional states. We applied microSPLiT to >25,000
cells sampled at different growth stages, creating an atlas of changes in metabolism and lifestyle. We retrieved detailed gene expression profiles associated with known, but rare, states such as competence and prophage induction and also identified unexpected gene expression states, including the heterogeneous activation of a niche metabolic pathway in a subpopulation of cells. MicroSPLiT paves the way to high-throughput analysis of gene expression in bacterial communities that are otherwise not amenable to single-cell analysis, such as natural microbiota.
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