Flight-measured X-24A lifting body control surface hinge moments and correlation with wind tunnel predictions

Control-surface hinge-moment measurements obtained in the X-24A lifting body flight-test program are compared with results from wind-tunnel tests. The effects of variations in angle of attack, angle of sideslip, rudder bias, rudder deflection, upper-flap deflection, lower-flap deflection, Mach number, and rocket-engine operation on the control-surface hinge moments are presented. In-flight motion pictures of tufts attached to the inboard side of the right fin and the rudder and upper-flap surfaces are discussed

Differentiation and Replication of Spots in a Reaction Diffusion System with Many Chemicals

The replication and differentiation of spots in reaction diffusion equations are studied by extending the Gray-Scott model with self-replicating spots to include many degrees of freedom needed to model systems with many chemicals. By examining many possible reaction networks, the behavior of this model is categorized into three types: replication of homogeneous fixed spots, replication of oscillatory spots, and differentiation from `m ultipotent spots'. These multipotent spots either replicate or differentiate into other types of spots with different fixed-point dynamics, and as a result, an inhomogeneous pattern of spots is formed. This differentiation process of spots is analyzed in terms of the loss of chemical diversity and decrease of the local Kolmogorov-Sinai entropy. The relevance of the results to developmental cell biology and stem cells is also discussed.Comment: 8 pages, 12 figures, Submitted to EP

On the statistical evaluation of dose-response functions

The linear-quadratic dependence of effect on the dose of ionizing radiation and its biophysical implications are considered. The estimation of the parameters of the response function and the derivation of the joint confidence region of the estimates are described. The method is applied to the induction of pink mutations inTradescantia which follows the linear-quadratic model. The statistical procedure is also suitable for other response functions

Spring weights of some Palaearctic passerines in Ethiopia and Kenya: evidence for important migration staging areas in eastern Ethiopia

Palaearctic migrants were trapped in late April and early May at a passage site near Jijiga in eastern Ethiopia. Willow Warblers Phylloscopus trochilus and Spotted Flycatchers Muscicapa striata were predominant, while Red-backed Shrikes Lanius collurio, Sedge Warblers Acrocephalus schoenobaenus, Reed Warblers A. scirpaceus, Garden Warblers Sylvia borin and Common Whitethroats S. communis also featured prominently. Weights were high in all species, and over 70% of the birds caught were extremely fat. Spring weights and fat scores at Jijiga were compared with those found in the same species in Kenya, and the difference was striking. In Kenya, most species had mean spring weights 10–20% above lean weight; at Jijiga, species’ mean weights ranged from 30% to 55% above lean weight. Whereas the reserves of most migrants departing from Kenya would have supported flights only as far as Ethiopia, the fat loads of birds at Jijiga indicated a potential for crossing Arabia with little need to feed. This suggests important staging and fattening grounds between these two areas, perhaps in the Acacia–Commiphora bushlands drained by the upper Juba and Shebelle rivers and their tributaries

Monte Carlo simulation of coagulation in discrete particle-size distributions. Part 2. Interparticle forces and the quasi-stationary equilibrium hypothesis

Hunt (1982) and Friedlander (1960a, b) used dimensional analysis to derive expressions for the steady-state particle-size distribution in aerosols and hydrosols. Their results were supported by the Monte Carlo simulation of a non-interacting coagulating population of suspended spherical particles developed by Pearson, Valioulis & List (1984). Here the realism of the Monte Carlo simulation is improved by accounting for the modification to the coagulation rate caused by van der Waals', electrostatic and hydrodynamic forces acting between particles. The results indicate that the major hypothesis underlying the dimensional reasoning, that is, collisions between particles of similar size are most important in determining the shape of the particle size distribution, is valid only for shear-induced coagulation. It is shown that dimensional analysis cannot, in general, be used to predict equilibrium particle-size distributions, mainly because of the strong dependence of the interparticle force on the absolute and relative size of the interacting particles

cis-3,3-Dimethyl-3,3a,4,5,6,6a-hexa­hydro-1H-cyclo­penta­[c]furan-1,6-dione

The bicyclic mol­ecule of the title compound, C9H12O3, contains two five-membered rings with different functional groups, viz. a ketone and an ester. Both rings assume an envelope conformation. The mean planes of these functional groups form a dihedral angle of 60.7 (1)°. The crystal structure exhibits weak inter­molecular C—H⋯O inter­actions, which link the mol­ecules into zigzag chains extended in the [010] direction. The unit cell contains a racemic mixture of enanti­omers