14,149 research outputs found
Effect of chronic administration of acetylsalicylic acid on lipid metabolism in growing rats
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Extreme throat initial data set and horizon area--angular momentum inequality for axisymmetric black holes
We present a formula that relates the variations of the area of extreme
throat initial data with the variation of an appropriate defined mass
functional. From this expression we deduce that the first variation, with fixed
angular momentum, of the area is zero and the second variation is positive
definite evaluated at the extreme Kerr throat initial data. This indicates that
the area of the extreme Kerr throat initial data is a minimum among this class
of data. And hence the area of generic throat initial data is bounded from
below by the angular momentum. Also, this result strongly suggests that the
inequality between area and angular momentum holds for generic asymptotically
flat axially symmetric black holes. As an application, we prove this inequality
in the non trivial family of spinning Bowen-York initial data.Comment: 11 pages. Changes in presentation and typos correction
The second order Raman spectrum of calcium fluoride
The second-order Raman spectrum of calcium fluoride recorded recently by Russell, using a He-Ne laser source, is discussed in the light of current theories on the dynamics of crystals. The observed spectrum of CaF2 is examined in detail with a calculation of the frequencies of the supercell modes using the lattice dynamic models of Ramanathan and Ganesan and Srinivasan, with the selection rules for the combinations from the critical points X for CaF2 structures. Satisfactory explanations have been given for most of the observed second-order frequency shifts
Effect of Burning Rate Modifiers on Subatmospheric Flame Temperatures of AP/HTPB Composite Solid Propellants
Using 30 um. pt and Pt 13 percent Rh thermocouples, flame temperatures of uncatalysed andcatalysed ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/lffPB) composite solidpropellants were measured under subatmospheric conditions. Ferric oxide F e 2 and copper chromite(CC) were the catalysts used. The study demonstrates that Fe2O3 catalysed propellant, notwithstandingits least combustion efficiency undt;r subatmospheric conditions and weak gas-phase flame, has themaximum burning rate enhancement. This is argued to be due to the increased surface and subsurfacereactions caused by Fe2O3. CC-catalysed propellant burns to the least subatmospheric pressure withminimum loss in combustion efficiency indicating that this class of propellant may be more suitablefor base-bleed applications
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