High rate of nasopharyngeal carriage of potential pathogens among children in Greenland: results of a clinical survey of middle-ear disease

Nasopharyngeal and middle-ear colonization with bacteria and viruses, including Mycoplasma pneumoniae and chlamydiae, was investigated in a survey of 54 children with acute otitis media (AOM) and 201 control children without AOM in Greenland. In total, 98% with AOM and 91% without AOM carried potentially pathogenic bacteria in the nasopharynx. Two or more potentially pathogenic species were carried by 78% with AOM and 57% without AOM. Haemophilus influenzae was found in 92% and 77%, respectively, but only Streptococcus pneumoniae was found significantly more often in the nasopharynx of children with AOM than in age-matched controls (P < .03). The two species were found in 22 of 24 ear-discharge specimens. Nine children (three with AOM) had chlamydiae in the nasopharynx, and seven of them reported rhinitis. Enteroviruses or rhinoviruses were detected in 23 nasopharyngeal specimens from 39 children with AOM, in 13 such specimens from 39 children without AOM (P = .040), and in 4 of 14 ear-discharge specimens. The potentially pathogenic load in the nasopharynx was massive, suggesting an association with the high prevalence of otitis media among children in Greenland.     

Axisymmetric static and dynamic buckling of orthotropic shallow spherical cap with circular hole

Nonlinear axisymmetric static and dynamic buckling of clamped isotropic and cylindrically orthotropic elastic cap with central circular hole have been investigated. The governing equations are expressed in terms of normal displacement ω and stress function ψ. The orthogonal point collocation method has been used in the space domain and Newmark-β scheme in the time domain. The cases of shallow cap with free hole and with a hole plugged by rigid central mass are considered. Analysis has been carried out for uniformly distributed load and a ring load at the hole. Dynamic load is taken as a step function load. Detailed new results for static and dynamic buckling loads have been presented for the isotropic and orthotropic cases.     

Retarding and antioxidant activity of 1-cyclohexylthio-2-mercaptobenzimidazole in the vulcanization of NR accelerated by thiocarbamyl sulfenamide

The effect of 1-cyclohexylthio-2-mercaptobenzimidazole (CMB) on the vulcanization of NR accelerated by N-oxydiethylene thiocarbamyl-N′-oxydiethylene sulfenamide (OTOS) has been studied. It is found that CMB delays the onset of cure and generates 2-mercaptobenzimidazole during vulcanization. The results indicate the retarding as well as antioxidant activity of CMB.     

Unsteady compressible 3-dimensional boundary-layer flow near an asymmetric stagnation point with mass transfer

The heat and mass transfer for unsteady laminar compressible boundary-layer flow, which is asymmetric with respect to a 3-dimensional stagnation point (i.e. for a jet incident at an angle on the body), have been studied. It is assumed that the free-stream velocity, wall temperature, and surface mass transfer vary arbitrarily with time and also that the gas has variable properties. The solution in the neighbourhood of the stagnation point has been obtained by series expansion in the longitudinal distance. The resulting partial differential equations have been solved numerically using an implicit finite-difference scheme. The results show that, in contrast with the symmetric flow, the maximum heat transfer does not occur at the stagnation point. The skin-friction and heat-transfer components due to asymmetric flow are only weakly affected by the mass transfer as compared to those components associated with symmetric flow. The variation of the wall temperature with time has a strong effect on the heat transfer component associated with the symmetric part of the flow. The skin friction and heat transfer are strongly affected by the variation of the density-viscosity product across the boundary layer. The skin friction responds more to the fluctuations of the free stream oscillating velocities than the heat transfer. The results have been compared with the available results and they are found to be in excellent agreement.     

The w-plane finite element method for the solution of scalar field problems in two dimensions

A simple, efficient finite element method has been presented for the solution of a variety of scalar field problems in two dimensions. It is based on the mapping of the physical problem domain into an ‘image’ domain in the w-plane. The governing equation(s) and the boundary conditions in the physical plane are also appropriately transformed into the w-plane. The processes of standard finite element analysis are then implemented to obtain a solution in the w-plane. The method has been explained in detail, with illustrative examples where appropriate; it has several important advantages over the standard finite element method, particularly for the solution of infinite or semi-infinite domain problems. The method has been demonstrated to be simple, efficient, economical and potentially capable of dealing with a large repartoire of two-dimensional problems, including non-homogeneity, nonlinearity, etc.     

Cyclic symmetry and the Shannon entropy

The authors have axiomatically characterized the Shannon entropy using cyclic symmetry.     

Compressible axially symmetric laminar boundary layer flow in the stagnation region of a blunt body in the presence of magnetic field

Summary In this paper, the steady laminar viscous hypersonic flow of an electrically conducting fluid in the region of the stagnation point of an insulating blunt body in the presence of a radial magnetic field is studied by similarity solution approach, taking into account the variation of the product of density and viscosity across the boundary layer. The two coupled non-linear ordinary differential equations are solved simultaneously using Runge-Kutta-Gill method. It has been found that the effect of the variation of the product of density and viscosity on skin friction coefficient and Nusselt number is appreciable. The skin friction coefficient increases but Nusselt number decreases as the magnetic field or the total enthalpy at the wall increases.

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Kompressible axialsymmetrische laminare Grenzschichtströmung in der Nähe des Staupunktes eines stumpfen Körpers unter Einwirkung eines Magnetfeldes

Zusammenfassung In dieser Arbeit wird die stationäre laminare viskose Überschallströmung einer elektrisch leitenden Flüssigkeit in der Nähe des Staupunktes eines isolierten stumpfen Körpers unter Einwirkung eines Magnetfeldes studiert unter Berücksichtigung der Veränderlichkeit des Produktes Dichte—Zähigkeit über die Grenzschicht. Die zwei gekoppelten nichtlinearen Gleichungen wurden mit Hilfe des Verfahrens von Runge-Kutta-Gill gelöst. Es zeigte sich, daß der Einfluß der Ortsabhängigkeit des Produktes Dichte—Zähigkeit auf den örtlichen Reibungsbeiwert und die Nusselt-Zahl keineswegs gering ist. Mit Zunahme des Magnetfeldes, oder der totalen Enthalpie an der Wand, nimmt der örtliche Reibungsbeiwert zu, die Nusselt-Zahl jedoch ab.

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With 3 Figures     

Wear characteristics and bearing performance of aluminium-mica particulate composite material

Some tribological properties of a mica-dispersed Al-4%Cu-1.5%Mg alloy cast by a conventional foundry technique are reported. The effect of mica dispersion on the wear rate and journal bearing performance of the matrix alloy was studied under different pressures and under different interface friction conditions. The dispersion of mica was found (a) to increase the wear rate of the base alloy, (b) to decrease the temperature rise during wear and (c) to improve the ability of the alloy to resist seizure.