Temple University

About: Temple University is a education organization based out in Philadelphia, Pennsylvania, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 32154 authors who have published 64375 publications receiving 2219828 citations.

Empirical Performance of Alternative Option Pricing Models

Abstract: Substantial progress has been made in extending the Black-Scholes model to incorporate such features as stochastic volatility, stochastic interest rates and jumps.On the empirical front, however, it is not yet known whether and by how much each generalized feature will improve option pricing and hedging performance. This paper fills this gap by first developing an implementable option model in closed form that allows volatility, interest rates and jumps to bestochastic and that is parsimonious in the number of parameters. The model includes many known ones as special cases. Delta-neutral and single-instrument minimum-variance hedging strategies are derived analytically. Using S&P 500 options, we examine a set of alternative models from three perspectives: (1) internal consistency of implied parameters/volatility with relevant time-series data, (2)out-of-sample pricing and (3) hedging performance. The models of focus include the benchmark Black-Scholes formula and the ones that respectively allow for (i) stochastic volatility, (ii) both stochastic volatility and stochastic interest rates, and (iii) stochastic volatility and jumps.Overall, incorporating both stochastic volatility and random jumps produces the best pricing performance and the most internally-consistent implied-volatility process. Its implied volatility does not "smile" across moneyness. But, for hedging, adding either jumps or stochastic interest rates does not seem to improve performance any further once stochastic volatility is taken into account.

Phosphate is a specific signal for induction of osteopontin gene expression

Abstract: Osteopontin is a phosphorylated glycoprotein secreted to the mineralizing extracellular matrix by osteoblasts during bone development. It is believed to facilitate the attachment of osteoblasts and osteoclasts to the extracellular matrix, allowing them to perform their respective functions during osteogenesis. Several other functions have been suggested for this protein, and its up-regulation is associated with various disease states related to calcification, including arterial plaque formation and the formation of kidney stones. Although expression of this gene has been demonstrated in multiple tissues, its regulation is not well understood. Our previous studies on the roles of the retinoblastoma protein (pRB) and p300/CBP in the regulation of osteoblast differentiation revealed a link between osteopontin induction and the synthesis of alkaline phosphatase. In this paper, we describe results specifically linking induction of osteopontin to the enzymatic activity of alkaline phosphatase in the medium, which results in the generation of free phosphate. This elevation of free phosphate in the medium is sufficient to signal induction of osteopontin RNA and protein. The strong and specific induction of osteopontin in direct response to increased phosphate levels provides a mechanism to explain how expression of this product is normally regulated in bone and suggests how it may become up-regulated in damaged tissue.

Treatment with Bivalirudin (Hirulog) as Compared with Heparin during Coronary Angioplasty for Unstable or Postinfarction Angina

Abstract: Background Heparin is often administered during and after coronary angioplasty to prevent closure of the dilated vessel. However, ischemic or hemorrhagic complications occur in 5 to 10 percent of treated patients. We studied whether these complications could be prevented when the direct thrombin inhibitor bivalirudin (Hirulog) was used in place of heparin. Methods We performed a double-blind, randomized trial in 4098 patients undergoing angioplasty for unstable or postinfarction angina. Patients were assigned to receive either heparin or bivalirudin immediately before angioplasty. The primary end point was death in the hospital, myocardial infarction, abrupt vessel closure, or rapid clinical deterioration of cardiac origin. Results In the total study group, bivalirudin did not significantly reduce the incidence of the primary end point (11.4 percent, vs. 12.2 percent for heparin) but did result in a lower incidence of bleeding (3.8 percent vs. 9.8 percent, P<0.001). In the prospectively stratified subgrou...

Disintegrins: A Family of Integrin Inhibitory Proteins from Viper Venoms

Abstract: Disintegrins represent a new class of low molecular weight, RGD-containing, cysteine-rich peptides isolated from the venom of various snakes. They interact with the β1 and β3 families of in...