Effect of Mach number on the structure of turbulent spots

Direct numerical simulations have been performed to study the dynamics of isolated turbulent spots in compressible isothermal-wall boundary layers. Results of a bypass transition scenario at Mach 2, 4 and 6 are presented. At all Mach numbers the evolved spots have a leading-edge overhang, followed by a turbulent core and a calmed region at the rear interface. The spots have an upstream-pointing arrowhead shape when visualized by near-wall slices, but a downstream-pointing arrowhead in slices away front the wall. The lateral spreading of the spot decreases substantially with the Mach number, consistent with a growth mechanism based on the instability of lateral shear layers. Evidence for a supersonic (Mach) mode substructure is found in the Mach 6 case, where coherent spanwise structures are observed under the spot overhang region

Marginalizing the likelihood function for modeled gravitational wave searches

Matched filtering is a commonly used technique in gravitational wave searches for signals from compact binary systems and from rapidly rotating neutron stars. A common issue in these searches is dealing with four extrinsic parameters which do not affect the phase evolution of the system: the overall amplitude, initial phase, and two angles determining the overall orientation of the system. The F-statistic maximizes the likelihood function analytically over these parameters, while the B-statistic marginalizes over them. The B-statistic, while potentially more powerful and capable of incorporating astrophysical priors, is not as widely used because of the computational difficulty of performing the marginalization. In this paper we address this difficulty and show how the marginalization can be done analytically by combining the four parameters into a set of complex amplitudes. The results of this paper are applicable to both transient non-precessing binary coalescence events, and to long lived signals from rapidly rotating neutron stars.Comment: 26 page

Assessment of maturation and induction of spawning in marine finfish- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

The cultivation of many economically important species has been helped greatly by the growing use of the technique of artificial fertilization and incubation. The discovery of artificial fertilization is supposed to be very old and this technique is said to have been practiced in the middle ages by the monk Don Pinchon in trout. The rediscovery of wet artificial fertilization in salmonids in 1842 by two anglers Gehin and Remy and the discovery of dry fertilization by the Russian Vrassky and its application between 1856 and 1870 led to great technical progress. Artificial spawning was first achieved in striped mullet in 1930 in Italy. In general the technique of hypophysation has triggered rapid progress in the induced breeding of cultured species, in the controlled rearing of fish larvae and in selective breeding

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