Is Bitcoin Really Untethered? GRIFFIN, JOHN M.; SHAMS, AMIN
The Journal of finance (New York),
August 2020, Letnik:
75, Številka:
4
Journal Article
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This paper investigates whether Tether, a digital currency pegged to the U.S. dollar, influenced Bitcoin and other cryptocurrency prices during the 2017 boom. Using algorithms to analyze blockchain ...data, we find that purchases with Tether are timed following market downturns and result in sizable increases in Bitcoin prices. The flow is attributable to one entity, clusters below round prices, induces asymmetric autocorrelations in Bitcoin, and suggests insufficient Tether reserves before month-ends. Rather than demand from cash investors, these patterns are most consistent with the supply-based hypothesis of unbacked digital money inflating cryptocurrency prices.
This article analyzes the available evidence to address airborne, aerosol transmission of the SARS‐CoV‐2. We review and present three lines of evidence: case reports of transmission for asymptomatic ...individuals in association with studies that show that normal breathing and talking produce predominantly small droplets of the size that are subject to aerosol transport; limited empirical data that have recorded aerosolized SARS‐CoV‐2 particles that remain suspended in the air for hours and are subject to transport over distances including outside of rooms and intrabuilding, and the broader literature that further supports the importance of aerosol transmission of infectious diseases. The weight of the available evidence warrants immediate attention to address the significance of aerosols and implications for public health protection.
Did FinTech Lenders Facilitate PPP Fraud? GRIFFIN, JOHN M.; KRUGER, SAMUEL; MAHAJAN, PRATEEK
The Journal of finance (New York),
June 2023, Letnik:
78, Številka:
3
Journal Article
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ABSTRACT
In the $793 billion Paycheck Protection Program, we examine metrics related to potential misreporting including nonregistered businesses, multiple businesses at residential addresses, ...abnormally high implied compensation per employee, and large inconsistencies with jobs reported in another government program. These measures consistently concentrate in certain FinTech lenders and are cross‐verified by seven additional measures. FinTech market share increased significantly over time, and suspicious lending by FinTechs in 2021 is four times the level at the start of the program. Suspicious loans are being overwhelmingly forgiven at rates similar to other loans.
Supercapacitors (or electric double-layer capacitors) are high-power energy storage devices that store charge at the interface between porous carbon electrodes and an electrolyte solution. These ...devices are already employed in heavy electric vehicles and electronic devices, and can complement batteries in a more sustainable future. Their widespread application could be facilitated by the development of devices that can store more energy, without compromising their fast charging and discharging times. In situ characterization methods and computational modeling techniques have recently been developed to study the molecular mechanisms of charge storage, with the hope that better devices can be rationally designed. In this Perspective, we bring together recent findings from a range of experimental and computational studies to give a detailed picture of the charging mechanisms of supercapacitors. Nuclear magnetic resonance experiments and molecular dynamics simulations have revealed that the electrode pores contain a considerable number of ions in the absence of an applied charging potential. Experiments and computer simulations have shown that different charging mechanisms can then operate when a potential is applied, going beyond the traditional view of charging by counter-ion adsorption. It is shown that charging almost always involves ion exchange (swapping of co-ions for counter-ions), and rarely occurs by counter-ion adsorption alone. We introduce a charging mechanism parameter that quantifies the mechanism and allows comparisons between different systems. The mechanism is found to depend strongly on the polarization of the electrode, and the choice of the electrolyte and electrode materials. In light of these advances we identify new directions for supercapacitor research. Further experimental and computational work is needed to explain the factors that control supercapacitor charging mechanisms, and to establish the links between mechanisms and performance. Increased understanding and control of charging mechanisms should lead to new strategies for developing next-generation supercapacitors with improved performances.
Ten Years of Evidence Griffin, John M.
Journal of economic literature,
12/2021, Letnik:
59, Številka:
4
Journal Article
Recenzirano
This article synthesizes the large literature regarding the role of various players in residential mortgage-backed securities (RMBS) securitization at the center of the 2008–09 US housing and ...financial crisis. Underwriting banks facilitated wide-scale mortgage fraud by knowingly misreporting key loan characteristics underlying mortgage-backed securities (MBS). Under the cover of complexity, credit rating agencies catered to investment banks by issuing increasingly inflated ratings on both RMBS and collateralized debt obligations (CDOs). Originators who engaged in mortgage fraud gained market share, as did CDO managers who catered to underwriters by accepting the lowest-quality MBS collateral. Appraisal targeting and inflated appraisals were the norm. RMBS and CDO prices indicate that the marginal AAA investor was unaware of pervasive mortgage fraud and ratings inflation, but these factors were strongly related to future deal performance. The supply of fraudulent credit was not uniform, but clustered in certain geographic regions and zip codes. As these dubious originators extended credit to those who could not afford the loans, the credit expansion led to house price booms and subsequent crashes in these zip codes. Overall, a consistent narrative based on substantial research indicates that conflicts of interest, misreporting, and fraud were focal features of the financial crisis.
This paper examines apparent fraud among securitized nonagency loans using three indicators: unreported second liens, owner occupancy misreporting, and appraisal overstatements. We find that around ...48% of loans exhibited at least one indicator of misrepresentation. Surprisingly, misreporting is similar in both low and full documentation loans and is associated with a 51% higher likelihood of delinquency. Two-thirds of loans with unreported second liens had the same originator issuing both the first and second lien. Misrepresentations in MBS pools can explain substantial cross-sectional differences in future losses. Losses were predictable and initiating from apparent fraud by MBS underwriters and loan originators.
The homeostatic blood protease, activated protein C (APC), can function as (1) an antithrombotic on the basis of inactivation of clotting factors Va and VIIIa; (2) a cytoprotective on the basis of ...endothelial barrier stabilization and anti-inflammatory and antiapoptotic actions; and (3) a regenerative on the basis of stimulation of neurogenesis, angiogenesis, and wound healing. Pharmacologic therapies using recombinant human and murine APCs indicate that APC provides effective acute or chronic therapies for a strikingly diverse range of preclinical injury models. APC reduces the damage caused by the following: ischemia/reperfusion in brain, heart, and kidney; pulmonary, kidney, and gastrointestinal inflammation; sepsis; Ebola virus; diabetes; and total lethal body radiation. For these beneficial effects, APC alters cell signaling networks and gene expression profiles by activating protease-activated receptors 1 and 3. APC’s activation of these G protein–coupled receptors differs completely from thrombin’s activation mechanism due to biased signaling via either G proteins or β-arrestin-2. To reduce APC-associated bleeding risk, APC variants were engineered to lack >90% anticoagulant activity but retain normal cell signaling. Such a neuroprotective variant, 3K3A-APC (Lys191-193Ala), has advanced to clinical trials for ischemic stroke. A rich data set of preclinical knowledge provides a solid foundation for potential translation of APC variants to future novel therapies.
Nanostructuring and nanosizing have been widely employed to increase the rate capability in a variety of energy storage materials. While nanoprocessing is required for many materials, we show here ...that both the capacity and rate performance of low-temperature bronze-phase TT- and T-polymorphs of Nb2O5 are inherent properties of the bulk crystal structure. Their unique “room-and-pillar” NbO6/NbO7 framework structure provides a stable host for lithium intercalation; bond valence sum mapping exposes the degenerate diffusion pathways in the sites (rooms) surrounding the oxygen pillars of this complex structure. Electrochemical analysis of thick films of micrometer-sized, insulating niobia particles indicates that the capacity of the T-phase, measured over a fixed potential window, is limited only by the Ohmic drop up to at least 60C (12.1 A·g–1), while the higher temperature (Wadsley–Roth, crystallographic shear structure) H-phase shows high intercalation capacity (>200 mA·h·g–1) but only at moderate rates. High-resolution 6/7Li solid-state nuclear magnetic resonance (NMR) spectroscopy of T-Nb2O5 revealed two distinct spin reservoirs, a small initial rigid population and a majority-component mobile distribution of lithium. Variable-temperature NMR showed lithium dynamics for the majority lithium characterized by very low activation energies of 58(2)–98(1) meV. The fast rate, high density, good gravimetric capacity, excellent capacity retention, and safety features of bulk, insulating Nb2O5 synthesized in a single step at relatively low temperatures suggest that this material not only is structurally and electronically exceptional but merits consideration for a range of further applications. In addition, the realization of high rate performance without nanostructuring in a complex insulating oxide expands the field for battery material exploration beyond conventional strategies and structural motifs.
ZIP codes with high concentrations of originators who misreported mortgage information experienced a 75% larger relative increase in house prices from 2003 to 2006 and a 90% larger relative decrease ...from 2007 to 2012 compared with other ZIP codes. Several causality tests show that high fractions of dubious originators in a ZIP code lead to large price distortions. Originators with high misreporting gave credit to borrowers with high ex ante risk, yet further understated the borrowers' true risk. Overall, excess credit facilitated through dubious origination practices explain much of the regional variation in house prices over a decade.
Is COVID Revealing a Virus in CMBS 2.0? GRIFFIN, JOHN M.; PRIEST, ALEX
The Journal of finance (New York),
August 2023, Letnik:
78, Številka:
4
Journal Article
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ABSTRACT
Commercial loan valuations crucially depend on accurate loan income, but underwritten income on commercial mortgage‐backed securities (CMBS) loans is commonly overstated relative to actual ...property income. Consistent with these differences being originator‐specific, income overstatement in CMBS 2.0 deals varies widely and persistently across originators, is priced by originators, is related across property types within an originator, is predictable ex ante, and is accompanied by inflation of past financials. Risk retention and associated regulation had no discernible effect on income overstatement. Originator income overstatement is highly predictive of pre‐ and COVID‐period loan distress. Overall, recent market stresses reveal large systemic differences in underwriting standards across originators.
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