We examine the microstructure of liquidity provision in the COVID-19 corporate bond liquidity crisis. During the two weeks leading up to Federal Reserve System interventions, volume shifted to liquid ...securities, transaction costs soared, trade-size pricing inverted, and dealers, particularly non-primary dealers, shifted from buying to selling, causing dealers’ inventories to plummet. Liquidity provisions in electronic customer-to-customer trading increased, though at prohibitively high costs. By improving dealer funding conditions and providing a liquidity backstop, the Primary Dealer Credit Facility and the Secondary Market Corporate Credit Facility (SMCCF) stabilized trading conditions. Most of the impact of SMCCF on bond liquidity seems to have materialized following its announcement. We argue that the Federal Reserve's actions reflect a new role as market maker of last resort.
Focusing on downgrades as stress events that drive the selling of corporate bonds, we show that the illiquidity of stressed bonds has increased after the Volcker Rule. Dealers regulated by the rule ...have curtailed their market-making activities and non-Volcker-affected dealers have not offset the decreased activities of Volcker-affected dealers. Furthermore, even Volcker-affected dealers that are not constrained by Basel III and Comprehensive Capital Analysis and Review regulations change their behavior, inconsistent with the effects being driven by these other regulations. Because Volcker-affected dealers have been the main liquidity providers, bonds have become less liquid during times of stress due to the Volcker Rule.
Large shareholders and credit ratings Kedia, Simi; Rajgopal, Shivaram; Zhou, Xing (Alex)
Journal of financial economics,
06/2017, Letnik:
124, Številka:
3
Journal Article
Recenzirano
This paper addresses regulatory concerns that large shareholders of credit rating agencies can influence the rating process. Unlike Standard & Poor's, which is a privately held division of ...McGraw-Hill, Moody's is a public company listed on the NYSE. From 2001 to 2010, Moody's has two shareholders, Berkshire Hathaway and Davis Selected Advisors, which collectively own about 23.5% of Moody's. Moody's ratings on bonds issued by important investee firms of these two stable large shareholders are more favorable relative to S&P, as well as Fitch, ratings. We exploit Moody's initial public offering in 2000 to address endogeneity and to mitigate concerns that the results are driven by issuer characteristics or by the greater informativeness of Moody's ratings. S&P's parent, McGraw-Hill, has a large shareholder for much less time, and some weak evidence exists that S&P ratings are relatively more favorable toward the owners of McGraw-Hill. These findings are consistent with regulatory concerns about the ownership and governance of rating agencies, especially those that are publicly listed.
Thermal conductivity is one of the most fundamental properties of solid materials. The thermal conductivity of ideal crystal materials has been widely studied over the past hundreds years. On the ...contrary, for amorphous materials that have valuable applications in flexible electronics, wearable electrics, artificial intelligence chips, thermal protection, advanced detectors, thermoelectrics, and other fields, their thermal properties are relatively rarely reported. Moreover, recent research indicates that the thermal conductivity of amorphous materials is quite different from that of ideal crystal materials. In this article, the authors systematically review the fundamental physical aspects of thermal conductivity in amorphous materials. They discuss the method to distinguish the different heat carriers (propagons, diffusons, and locons) and the relative contribution from them to thermal conductivity. In addition, various influencing factors, such as size, temperature, and interfaces, are addressed, and a series of interesting anomalies are presented. Finally, the authors discuss a number of open problems on thermal conductivity of amorphous materials and a brief summary is provided.
A systematic review of the fundamental physical aspects of thermal conductivity in amorphous materials, which have valuable applications in flexible electronics, artificial intelligence chips, thermal protection, and thermoelectrics, is presented. The contributions from different heat carriers, including propagons, diffusons, and locons, are comprehensively discussed. Various influencing factors are addressed, and a series of interesting anomalies are presented.
This study was to investigate the protective effect of hyperbaric oxygen (HBO) on HT22 and PC12 cell damage caused by oxygen-glucose deprivation/reperfusion-induced ferroptosis. A 2-h oxygen-glucose ...deprivation and 24-h reperfusion model on HT22 and PC12 cells was used to simulate cerebral ischemia-reperfusion injury. Cell viabilities were detected by Cell Counting Kit-8 (CCK-8) method. The levels of reactive oxygen species (ROS) and lipid reactive oxygen species (Lipid ROS) were detected by fluorescent probes Dihydroethidium (DHE) and C11 BODIPY 581/591. Iron Colorimetric Assay Kit, malondialdehyde (MDA) and glutathione (GSH) activity assay kits were used to detect intracellular iron ion, MDA and GSHcontent. Cell ferroptosis-related ultrastructures were visualized using transmission electron microscopy (TEM). Furthermore, PCR and Western blot analyses were used to detect the expressions of ferroptosis-related genes and proteins. After receiving oxygen-glucose deprivation/reperfusion, the viabilities of HT22 and PC12 cells were significantly decreased; ROS, Lipid ROS, iron ions and MDA accumulation occurred in the cells; GSH contents decreased; TEM showed that cells were ruptured and blebbed, mitochondria atrophied and became smaller, mitochondrial ridges were reduced or even disappeared, and apoptotic bodies appeared. And the expressions of Nrf2, SLC7A11 and GPX4 genes were reduced; the expressions of p-Nrf2/Nrf2, xCT and GPX4 proteins were reduced. Notably, these parameters were significantly reversed by HBO, indicating that HBO can protect HT22 cells and PC12 cells from damage caused by oxygen-glucosedeprivation/reperfusion via the inhibition of Nrf2/System Xc-/GPX4 axis-mediated ferroptosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Inhaled aerosol BCG was well tolerated by healthy adults who had no previous exposure to either M tuberculosis or BCG. ...the successful recovery of BCG from the lungs after aerosol inhalation ...considerably strengthens the feasibility of using this approach to evaluate the effectiveness of potential vaccines. ...the study suggests the feasibility of administering a BCG vaccine via inhaled aerosol to humans—a vaccination strategy that is gaining attention given its potency for inducing robust respiratory mucosal immunity, which cannot be achieved with injectable vaccines.8,9 However, ensuring the safety of delivering BCG through inhaled aerosols requires comprehensive evaluation across various scenarios. The study also underscores the importance of addressing key variables in the BCG aerosol human challenge model, including ensuring the accuracy of the aerosol delivery device, adjusting the dose of BCG owing to potential viability changes during long-term storage, and refining bronchoalveolar lavage techniques for consistent BCG recovery.
Emotion recognition represents the position and motion of facial muscles. It contributes significantly in many fields. Current approaches have not obtained good results. This paper aimed to propose a ...new emotion recognition system based on facial expression images. We enrolled 20 subjects and let each subject pose seven different emotions: happy, sadness, surprise, anger, disgust, fear, and neutral. Afterward, we employed biorthogonal wavelet entropy to extract multiscale features, and used fuzzy multiclass support vector machine to be the classifier. The stratified cross validation was employed as a strict validation model. The statistical analysis showed our method achieved an overall accuracy of 96.77±0.10%. Besides, our method is superior to three state-of-the-art methods. In all, this proposed method is efficient.
Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has ...been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials.
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the most formidable challenge to humanity in a century. It is widely ...believed that prepandemic normalcy will never return until a safe and effective vaccine strategy becomes available and a global vaccination programme is implemented successfully. Here, we discuss the immunological principles that need to be taken into consideration in the development of COVID-19 vaccine strategies. On the basis of these principles, we examine the current COVID-19 vaccine candidates, their strengths and potential shortfalls, and make inferences about their chances of success. Finally, we discuss the scientific and practical challenges that will be faced in the process of developing a successful vaccine and the ways in which COVID-19 vaccine strategies may evolve over the next few years.
Insurance companies often follow highly correlated investment strategies. As major investors in corporate bonds, their investment commonalities subject investors to fire sale risk when regulatory ...restrictions prompt widespread divestment of a bond following a rating downgrade. Reflective of fire sale risk, the clustering of insurance companies in a bond has significant explanatory power for yield spreads, controlling for liquidity, credit risk, and other factors. The effect of insurer clustering on bond yield spreads is more evident for bonds held to a greater extent by capital-constrained insurance companies, those with ratings closer to National Association of Insurance Commissioners risk categories with larger capital requirements, and during the financial crisis.
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