31,621 research outputs found
The Discretionary Effect of CEOs and Board Chairs on Corporate Governance Structures
Get PDFIn this study we analyze the effect of latent managerial characteristics on corporate governance. We find that CEO and board chair fixed effects explain a significant portion of the variation in board size, board independence, and CEO-chair duality even after controlling for several firm characteristics and firm fixed effects. The effect of CEOs on corporate governance practices is attributable mainly to executives who simultaneously hold the position of CEO and board chair in the same firm. Our results do not show a decline in CEO discretionary influence on corporate governance after the enactment of the Sarbanes–Oxley Act and stock exchange governance regulations
Unclassified autoimmune pancreatitis mimicking pancreatic cancer
Get PDFA 24-year-old black male presented with a 1-week obstructive jaundice and intermittent abdominal pain, with no significant weight loss and an unsuspicious abdominal exam. Blood chemistry showed a cholestatic pattern but a complete immunological and tumoral panel (anti-smooth muscle antibody, anti-mitochondrial antibody, anti-nuclear antibody, anti-neutrophil cytoplasmic antibody, anti-Smith, anti-double-stranded-DNA antibody (anti-dsDNA), complement C3/C4, carcinoembryonic antigen, CA 19-9 and IgG4) were all within normal limits. Abdominal ultrasound revealed dilatation of the intra and extra-hepatic bile ducts. CT scan showed an abnormal dilatation of the distal bile duct but no focal enlargement of the head of the pancreas. Endoscopic ultrasound suggested an inflammatory process but the magnetic resonance cholangio-pancreatography favored a neoplastic obstruction of the distal common bile duct. Fine-needle aspiration cytology was insufficient for definitive diagnosis and the patient underwent major surgery. Follow-up with mild exocrine pancreatic insufficiency treated with enzyme replacement.info:eu-repo/semantics/publishedVersio
The Flash Crash: An Examination of Shareholder Wealth and Market Quality
Get PDFWe investigate stock returns, market quality, and options market activity around the flash crash of May 6, 2010. Abnormal returns are negative on the day of and the day after the flash crash for stocks that had trades that executed during the crash subsequently cancelled by either Nasdaq or NYSE Arca. Consistent with studies that suggest that other sources of liquidity withdrew from the markets during the flash crash, we find that the fraction of trades executed by the NYSE increases during this volatile period. Market quality deteriorates following the flash crash as bid-ask spreads increase and quote depths decrease. Evidence from the options markets indicates that investor uncertainty increased around the time of the crash and remained elevated for several days
Crime prediction through urban metrics and statistical learning
Full text linkUnderstanding the causes of crime is a longstanding issue in researcher's
agenda. While it is a hard task to extract causality from data, several linear
models have been proposed to predict crime through the existing correlations
between crime and urban metrics. However, because of non-Gaussian distributions
and multicollinearity in urban indicators, it is common to find controversial
conclusions about the influence of some urban indicators on crime. Machine
learning ensemble-based algorithms can handle well such problems. Here, we use
a random forest regressor to predict crime and quantify the influence of urban
indicators on homicides. Our approach can have up to 97% of accuracy on crime
prediction, and the importance of urban indicators is ranked and clustered in
groups of equal influence, which are robust under slightly changes in the data
sample analyzed. Our results determine the rank of importance of urban
indicators to predict crime, unveiling that unemployment and illiteracy are the
most important variables for describing homicides in Brazilian cities. We
further believe that our approach helps in producing more robust conclusions
regarding the effects of urban indicators on crime, having potential
applications for guiding public policies for crime control.Comment: Accepted for publication in Physica
- …
