Oklahoma State University–Stillwater

About: Oklahoma State University–Stillwater is a education organization based out in Stillwater, Oklahoma, United States. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 18267 authors who have published 36743 publications receiving 1107500 citations. The organization is also known as: Oklahoma State University & OKState.

Does Hedging Affect Firm Value? Evidence from the US Airline Industry

Abstract: Does hedging add value to the firm, and if so, is the source of the added value consistent with hedging theory? We investigate jet fuel hedging behavior of firms in the US airline industry during 1992–2003 to examine whether such hedging is a source of value for these companies. We illustrate that the investment and financing climate in the airline industry conforms well to the theoretical framework of Froot, Scharfstein, and Stein (1993). In general, airline industry investment opportunities correlate positively with jet fuel costs, while higher fuel costs are consistent with lower cash flow. Given that jet fuel costs are hedgeable, airlines with a desire for expansion may find value in hedging future purchases of jet fuel. Our results show that jet fuel hedging is positively related to airline firm value. The coefficients on the hedging variables in our regression analysis suggest that the “hedging premium” is greater than the 5% documented in Allayannis and Weston (2001), and might be as large as 10%. We find that the positive relation between hedging and value increases in capital investment, and that most of the hedging premium is attributable to the interaction of hedging with investment. This result is consistent with the assertion that the principal benefit of jet fuel hedging by airlines comes from reduction of underinvestment costs.

Comparison of Species Richness Estimates Obtained Using Nearly Complete Fragments and Simulated Pyrosequencing-Generated Fragments in 16S rRNA Gene-Based Environmental Surveys

Abstract: Pyrosequencing-based 16S rRNA gene surveys are increasingly utilized to study highly diverse bacterial communities, with special emphasis on utilizing the large number of sequences obtained (tens to hundreds of thousands) for species richness estimation. However, it is not yet clear how the number of operational taxonomic units (OTUs) and, hence, species richness estimates determined using shorter fragments at different taxonomic cutoffs correlates with the number of OTUs assigned using longer, nearly complete 16S rRNA gene fragments. We constructed a 16S rRNA clone library from an undisturbed tallgrass prairie soil (1,132 clones) and used it to compare species richness estimates obtained using eight pyrosequencing candidate fragments (99 to 361 bp in length) and the nearly full-length fragment. Fragments encompassing the V1 and V2 (V1+V2) region and the V6 region (generated using primer pairs 8F-338R and 967F-1046R) overestimated species richness; fragments encompassing the V3, V7, and V7+V8 hypervariable regions (generated using primer pairs 338F-530R, 1046F-1220R, and 1046F-1392R) underestimated species richness; and fragments encompassing the V4, V5+V6, and V6+V7 regions (generated using primer pairs 530F-805R, 805F-1046R, and 967F-1220R) provided estimates comparable to those obtained with the nearly full-length fragment. These patterns were observed regardless of the alignment method utilized or the parameter used to gauge comparative levels of species richness (number of OTUs observed, slope of scatter plots of pairwise distance values for short and nearly complete fragments, and nonparametric and parametric species richness estimates). Similar results were obtained when analyzing three other datasets derived from soil, adult Zebrafish gut, and basaltic formations in the East Pacific Rise. Regression analysis indicated that these observed discrepancies in species richness estimates within various regions could readily be explained by the proportions of hypervariable, variable, and conserved base pairs within an examined fragment.

Detection, quantification and characterization of β-glucosaminidase activity in soil

Abstract: A simple and sensitive method was developed to detect and quantify N-acetyl-β- D -glucosaminidase (EC 3.2.1.30) activity in soil. This enzyme is also listed as β-hexosaminidase (EC 3.2.1.52) in Enzyme Nomenclature. The optimum pH and temperature for the enzyme were approximately pH 5.5 and 63°C, respectively. The Km and Vmax values were calculated from three linear transformations of the Michaelis–Menten equation. The Km values of the enzymatic reaction in the two soils tested ranged from 0.56 to 1.48 mM and the Vmax values ranged from 29 to 40 mg ρ-nitrophenol released kg−1soil h−1. The activation energy (Ea) for the enzymatic reaction was about 58 kJ mol−1 for soils tested. The Q10 values ranged from 1.35 to 2.50 at temperatures ranging from 10 to 60°C. With the exception of field-moist Renfrow soil, neither chloroform fumigation nor toluene pretreatment of soil samples affected the activity of β-glucosaminidase significantly. The activity of this enzyme in field-moist Renfrow soil increased about 20% upon fumigation or toluene treatment. Autoclaving the soils reduced β-glucosaminidase activity by about 58% in the air-dried soils and 96% in the field-moist soils. Air-drying of field-moist soil samples reduced β-glucosaminidase activity by 12% and 22% in Renfrow and Teller soil, respectively. Our results suggest that activity of β-glucosaminidase is mostly due to extracellular enzymes.