Dynamics of high-bypass-engine thrust reversal using a variable-pitch fan

The test program demonstrated that successful and rapid forward-to reverse-thrust transients can be performed without any significant engine operational limitations for fan blade pitch changes through either feather pitch or flat pitch. For through-feather-pitch operation with a flight inlet, fan stall problems were encountered, and a fan blade overshoot technique was used to establish reverse thrust

Vertical laser beam propagation through the troposphere

The characteristics of the earth's atmosphere and its effects upon laser beams was investigated in a series of balloon borne, optical propagation experiments. These experiments were designed to simulate the space to ground laser link. An experiment to determine the amplitude fluctuation, commonly called scintillation, caused by the atmosphere was described

On the Applicability of Weak-Coupling Results in High Density QCD

Quark matter at asymptotically high baryon chemical potential is in a color superconducting state characterized by a gap Delta. We demonstrate that although present weak-coupling calculations of Delta are formally correct for mu -> Infinity, the contributions which have to this point been neglected are large enough that present results can only be trusted for mu >> mu_c ~ 10^8 MeV. We make this argument by using the gauge dependence of the present calculation as a diagnostic tool. It is known that the present calculation yields a gauge invariant result for mu -> Infinity; we show, however, that the gauge dependence of this result only begins to decrease for mu > mu_c, and conclude that the result can certainly not be trusted for mu < mu_c. In an appendix, we set up the calculation of the influence of the Meissner effect on the magnitude of the gap. This contribution to Delta is, however, much smaller than the neglected contributions whose absence we detect via the resulting gauge dependence.Comment: 21 pages, 3 figures, uses LaTeX2e and ReVTeX, updated figures, made minor text change

A Statistical Treatment of the Gamma-Ray Burst "No Host Galaxy" Problem: II. Energies of Standard Candle Bursts

With the discovery that the afterglows after some bursts are coincident with faint galaxies, the search for host galaxies is no longer a test of whether bursts are cosmological, but rather a test of particular cosmological models. The methodology we developed to investigate the original "no host galaxy" problem is equally valid for testing different cosmological models, and is applicable to the galaxies coincident with optical transients. We apply this methodology to a family of models where we vary the total energy of standard candle bursts. We find that total isotropic energies of E<2e52~erg are ruled out while log(E)~53 erg is favored.Comment: To appear in Ap.J., 514, 15 pages + 7 figures, AASTeX 4.0. Revisions are: additional author, updated data, and minor textual change

Tip Anchor Flap in Decubital Surgery

Anchoring a flap remains a key procedure in decubital surgery because a flap needs to be stable against shearing forces. This allows an early mobilization and undisturbed primary wound healing. This study evaluated a uniform group of eight paraplegic patients with sacral decubital ulcers and covered the lesions using gluteal rotation flaps with a deepithelialized tip to anchor the flap subcutaneously on the contralateral ischial tuber. Initial wound healing and recurrence after one year were evaluated. All but one flap showed uneventful wound healing, and all the flaps presented without any signs of recurrence or instability. The authors suggest that sufficient anchoring using a deepithelialized part of the flap helps to integrate and stabilize sacral rotation flap

The plasma statistics computer aboard Explorer 34

Plasma statistics computer aboard Explorer 3

Scanning electron microscopy study of di-calcium phosphate dehydrate coatings on magnesium substrates for potential use in orthopaedic implants

Magnesium has attracted considerable medical interest due to its mechanical properties being similar to bone. In addition, magnesium is also biocompatible and biodegradable, which makes it an ideal candidate for biodegradable orthopaedic implants. However, magnesium’s high corrosion rate in body fluids makes it an unsuitable material for the manufacture of implants. The present study investigates a straightforward chemical immersion technique that deposits di-calcium phosphate dehydrate (DCPD) coatings onto magnesium substrates to increase their corrosion resistance to body simulated fluids like phosphate buffer saline solution and Ringer’s solution. Scanning electron microscopy revealed the coating structures and morphologies were characterised by flower-like surface feature that were resistant to both body simulated fluids. Thus, indicating the coatings could significantly reduce magnesium corrosion rates in the body environment

Structure of a Cyclophane Host Molecule

The cyclophane tetramethyl 3,8,13,18a,2l,26,31,36aoctahydro- 4,6:9,12:22,24:27,30-tetraetheno-l5,18,21:-33,36,39-diethenylylidenedibenzo[k,ɑl][1,8,17,24]tetraoxacyclodotriacontene-1,2,19,20-tetracarboxylate acetonitrile solvate, C_(56)H_(44)O_(12).CH_3C=N, contains a large cavity and forms host-guest complexes in solution with a variety of quaternary nitrogen compounds. Crystallization from an acetonitrile solution that contained damantyltrimethylammonium iodide led, though, to crystals of the uncomplexed cyclophane (but containing one molecule of acetonitrile of crystallization). The cavity, about 7.6 x 4.0 Å and roughly rectangular in cross section, is occupied by ester groupings from two adjacent cyclophanes, entering from opposite sides. Crystal data: orthorhombic, P2_12_12_1, with a= 11.741 (6), b = 16.155 (5), c = 25.895 (7) Å, v = 4912 Å^3, T = 296 K, Z = 4, M_r= 950.01, D_x = 1.28 g cm^(-3), F(000) = 1992, Mo Kɑ, λ = 0.7107 Å, μ = 0.84 cm^(-1), R = 0.0538 for 2410 independent reflections with I> 0, S = 2.29 for 2610 total reflections