An analysis of correlating parameters relating to hot gas ingestion characteristics of jet VTOL aircraft

Jet VTOL fighter-type model inlet-air temperature rise analysis with various exhaust pressure ratios and gas temperatures and surface wind velocities for correlating parameter

Carbonic anhydrase activity in the gills ofEtroplus maculatus (Teleostei) as a function of salinity acclimation

1. Carbonic anhydrase in the gills of the freshwater teleost,Etroplus maculatus, was demonstrated to be influenced by transfer of the animal to saline media. 2. Sudden and direct exposure of the fish to saline media resulted in a decrease of the enzyme activity. 3. The enzyme activity was reduced gradually with progressive increase of the salinity after two months acclimation of the fish in the medium. 4. It was concluded that reduced carbonic anhydrase activity of the gill on acclimation to higher salinities, is associated with Cl− uptake but not Cl− excretio

F-Sets in graphs

AbstractA subset S of the vertex set of a graph G is called an F-set if every α ϵ Γ(G), the automorphism group of G, is completely specified by specifying the images under α of all the points of S, and S has a minimum number of points. The number of points, k(G), in an F-set is an invariant of G, whose properties are studied in this paper. For a finite group Γ we define k(Γ) = max{k(G) | Γ(G) = Γ}. Graphs with a given Abelian group and given k-value (k ≤ k(Γ)) have been constructed. Graphs with a given group and k-value 1 are constructed which give simple proofs to the theorems of Frucht and Bouwer on the existence of graphs with given abstract/permutation groups

Sensitivity to image recurrence across eye-movement-like image transitions through local serial inhibition in the retina

Standard models of stimulus encoding in the retina postulate that image presentations activate neurons according to the increase of preferred contrast inside the receptive field. During natural vision, however, images do not arrive in isolation, but follow each other rapidly, separated by sudden gaze shifts. We here report that, contrary to standard models, specific ganglion cells in mouse retina are suppressed after a rapid image transition by changes in visual patterns across the transition, but respond with a distinct spike burst when the same pattern reappears. This sensitivity to image recurrence depends on opposing effects of glycinergic and GABAergic inhibition and can be explained by a circuit of local serial inhibition. Rapid image transitions thus trigger a mode of operation that differs from the processing of simpler stimuli and allows the retina to tag particular image parts or to detect transition types that lead to recurring stimulus patterns

An isobar contour plot progrz

A computer program was developed to obtain ; isobar contours from the total pressure measurements at the engine face of an 1/3 scale model of an aircraft intake duct provided by ADA . A cubic spline method was used to interpolate the total pressure value between the measuring stations . The isobar contour plots were obtained for engine face Mach numbers\ud varying from 0.17 to 0 .43

A k-out-of-n reliability system with an unreliable server and phase type repairs and services: the (N, T) policy

In this paper we study a k-out-of-n reliability system in which a single unreliable server maintains n identical components. The reliability system is studied under the (N,T) policy. An idle server takes a vacation for a random amount of time T and then attends to any failed component waiting in line upon completion of the vacation. The vacationing server is recalled instantaneously upon the failure of the Nth component. The failure times of the components are assumed to follow an exponential distribution. The server is subject to failure with failure times exponentially distributed. Repair times of the component, fixing times of the server, and vacationing times of the server are assumed to be of phase type. Using matrix-analytic methods we perform steady state analysis of this model. Time spent by a failed component in service, total time in the repair facility, vacation time of the server, non-vacation time of the server, and time until failure of the system are all shown to be of phase type. Several performance measures are evaluated. Illustrative numerical examples are presented

Topological Transitions in Metamaterials

The ideas of mathematical topology play an important role in many aspects of modern physics - from phase transitions to field theory to nonlinear dynamics (Nakahara M (2003) in Geometry, Topology and Physics, ed Brewer DF (IOP Publishing Ltd, Bristol and Philadelphia), Monastryskiy M (1987) in Riemann Topology and Physics, (Birkhauser Verlag AG)). An important example of this is the Lifshitz transition (Lifshitz IM (1960) Anomalies of electron characteristics of a metal in the high-pressure region, Sov Phys JETP 11: 1130-1135), where the transformation of the Fermi surface of a metal from a closed to an open geometry (due to e.g. external pressure) leads to a dramatic effect on the electron magneto-transport (Kosevich AM (2004) Topology and solid-state physics. Low Temp Phys 30: 97-118). Here, we present the optical equivalent of the Lifshitz transition in strongly anisotropic metamaterials. When one of the components of the dielectric permittivity tensor of such a composite changes sign, the corresponding iso-frequency surface transforms from an ellipsoid to a hyperboloid. Since the photonic density of states can be related to the volume enclosed by the iso-frequency surface, such a topological transition in a metamaterial leads to a dramatic change in the photonic density of states, with a resulting effect on every single physical parameter related to the metamaterial - from thermodynamic quantities such as its equilibrium electromagnetic energy to the nonlinear optical response to quantum-electrodynamic effects such as spontaneous emission. In the present paper, we demonstrate the modification of spontaneous light emission from quantum dots placed near the surface of the metamaterial undergoing the topological Lifshitz transition, and present the theoretical description of the effect

Antibacterial activity of diff erent solvent extracts of Caulerpa chemnitzia (Esper) J.V. Lamououx, from Mandapam, Gulf of Mannar Southeast Coast, Tamil Nadu, India

Phytochemical analyses and in vitro antibacterial activity of different extracts of hexane, chloroform, ethyl acetate,acetone, and methanol extracts of green algae, Caulerpa chemnitzia (Esper) J.V. Lamououx, against Bacillussubtilis, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris,Pseudomonas aeruginosa, Salmonella typhimurium, Shigella flexneri, and Vibrio cholerae. The extent of theinhibitory zone, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) weredetermined. The ethyl acetate extract of C. chemnitzia showed the presence of phytochemicals, terpenoids,tannins and phenolic compounds strongly than the other solvent extracts. The mean zone of inhibition producedby the extracts in agar diffusion assays against the tested bacterial strains ranged from 7.1 to 13.6 mm. The MICwas between 125 and 500 μg/mL while the MBC were between 250 and 1000 μg/mL. The highest mean zoneof inhibition (13.6 mm) and the lowest MIC (125 μg/mL) and MBC (250 μg/mL) values were observed in ethylacetate extract against B. subtilis. These findings suggest that the ethyl acetate extract of C. chemnitzia can beused as an antibacterial substance for the treatment of bacteria causing acquired infection