On the geometry of C^3/D_27 and del Pezzo surfaces

We clarify some aspects of the geometry of a resolution of the orbifold X = C3/D_27, the noncompact complex manifold underlying the brane quiver standard model recently proposed by Verlinde and Wijnholt. We explicitly realize a map between X and the total space of the canonical bundle over a degree 1 quasi del Pezzo surface, thus defining a desingularization of X. Our analysis relys essentially on the relationship existing between the normalizer group of D_27 and the Hessian group and on the study of the behaviour of the Hesse pencil of plane cubic curves under the quotient.Comment: 23 pages, 5 figures, 2 tables. JHEP style. Added references. Corrected typos. Revised introduction, results unchanged

APPLICATIONS OF COHERENT ANTI-STOKES RAMAN SPECTROSCOPY…. 15 min (1:47)

S. Lemont: NRC/NRL Postdoctoral Research Associate (Sept. 1976 - present).Author Institution: Chemistry Division, Naval Research Laboratory; Center of Materials Research, University of Maryland; Department of Chemistry, George Mason UniversityCARS is shown to be an extremely important analytical tool for probing gas molecules in electrical discharges and combustion systems. The successful use of CARS to measure vibrational temperatures of electrically discharged $D_{2}$ in an experimental $D_{2}$-HCl V-V energy transfer laser will be discussed first. This technique is also shown to be a powerful means of making temperature profile and number density measurements of species in flames and other combustion systems. Measurements made in a calibrated flat flame burner will be discussed

Seismic Evidence for Widespread Possible Gas Hydrate Horizons on Continental Slopes and Rises

Anomalous reflections in marine seismic reflection data from continental slopes are often correlated with the base of gas hydrated sedimentary rocks. Examination of University of Texas Marine Science Institute reflection data reveals the possible presence of such gas hydrates along the east coast of the United States, the western Gulf of Mexico, the coasts of northern Colombia and northern Panama, and along the Pacific side of Central America in areas extending from Panama to near Acapulco, Mexico. Suspected hydrates are present in water depths of 700 to 4,400 m and extend from 100 to 1,100 m subbottom. Geometric relations, reflection coefficients, reflection polarity, and pressure-temperature relations all support the identification of the anomalous reflections as the base of gas hydrated sediments. In most places, gas hydrate association is related to structural anomalies (anticlines, dipping strata), which may allow gas to concentrate and migrate updip into pressure and temperature conditions suitable for hydrate formation. The gas hydrate boundary can be used to estimate thermal gradients. In general, thermal gradients estimated from the gas hydrate phase boundary are higher than reported thermal gradients measured by conventional means