Zero Viscosity Limit for Analytic Solutions, of the Navier-Stokes Equation on a Half-Space.¶I. Existence for Euler and Prandtl Equations

This is the first of two papers on the zero-viscosity limit for the incompressible Navier-Stokes equations in a half-space. In this paper we prove short time existence theorems for the Euler and Prandtl equations with analytic initial data in either two or three spatial dimensions. The main technical tool in this analysis is the abstract Cauchy-Kowalewski theorem. For the Euler equations, the projection method is used in the primitive variables, to which the Cauchy-Kowalewski theorem is directly applicable. For the Prandtl equations, Cauchy-Kowalewski is applicable once the diffusion operator in the vertical direction is inverted. Received: 5 September 1995 / Accepted: 14 July 1997     

Choice of the Focal Point Position Using Lasentec FBRM

The Focused Beam Reflectance Measurement (FBRM) technique provides on‐line and in situ information about the chord length distribution (CLD) of a population of particles in dispersion. The effect of changing the focal point position on the measured CLD is experimentally analyzed by carrying out single particle FBRM determinations in both pure water and a dispersion of fines. The results allow some general conclusions to be drawn about optimal focal point positions.     

Multifield hyperelasticity: variational theorems for complex bodies

We present some multifield variational principles for complex elastic solids characterized by any material microstructure. Some general constitutive arguments in the context of multifield hyperelasticity are also discussed.     

Characterization of a protease produced by a Trichoderma harzianum isolate which controls cocoa plant witches' broom disease

Background  

Several Trichoderma strains have been reported to be effective in controlling plant diseases, and the action of fungal hydrolytic enzymes has been considered as the main mechanism involved in the antagonistic process. However, although Trichoderma strains were found to impair development of Crinipellis perniciosa, the causal agent of cocoa plant witches' broom disease, no fungal strain is available for effective control of this disease. We have then undertaken a program of construction of hydrolytic enzyme-overproducing Trichoderma strains aiming improvement of the fungal antagonistic capacity. The protease of an indian Trichoderma isolate showing antagonistic activity against C. perniciosa was purified to homogeneity and characterized for its kinetic properties and action on the phytopathogen cell wall.     

A Multivalued Approach to the Planar Isosceles Three Body Problem

The isosceles three body problem consists of three point masses located on the vertices of an isosceles triangle on the plane. The two masses on the asymmetric edge are equal. This problem has been extensively studied but not as a perturbation of the Kepler problem. In this case we arrive at a differential inclusion as a natural formulation when we regularize the problem. We also derive an extension of the vectorfield that allows us to consider orbits across singular sets.      

Classical and accelerated evaluation of neutron escape probability

Neutron escape probability from a monodimensional plane medium is determined by resorting to the integral neutron transport equation.Both a projection procedure and an appropriate variational approach, yielding an acceleration of the convergence rate, are employed; their numerical results are reported and discussed.The theory is presented in a general form, since it can be applied directly to many basic problems in other branches of applied sciences.

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Riassunto La probabilità di fuga di un neutrone da un mezzo monodimensionale piano viene determinata nell'ambito della teoria integrale del trasporto. Vengono impiegati sia un procedimento proiezionale classico, che un opportuno metodo variazionale in grado di produrre un'accelerazione della velocità di convergenza; i relativi risultati numerici sono riportati e discussi. La teoria è esposta nella sua forma generale, in quanto può essere applicata direttamente a diversi problemi di base in altri rami delle scienze applicate.

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Work supported by the National Group for Mathematical Physics of C.N.R.     

The normodistributive expansion of a category

Summary Starting from a categoryC, verifying certain hypotheses, we define a categoryC ^♯ called normodistributive expansion ofC. The categoryC ^♯is orthoquaternary, then canonical isomorphisms between subquotients ofC ^♯ are composable. This is a generalization of the construction of the distributive expansion ε^♯ of an exact catagory ε, which can be applied to a larger class of categories (including the category of groups).

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Riassunto Partendo da una categoriaC, che verifica certe ipotesi, si costruisce una categoriaC ^♯ detta espansione normodistributiva diC. La categoriaC ^♯ risulta essere orto-quaternaria, quindi gli isomorfismi canonici fra i suoi subquozienti sono componibili. Si è così generalizzato il passaggio da una categoria esatta ε alla sua espansione distributiva ε^♯, al caso di una famiglia più vasta di catagorie comprendente, fra le altre, quella (non esatta) dei gruppi.

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Lavoro eseguito nell’ambito dei gruppi di ricerca matematici del C.N.R.     

Hypervalent iodine as good leaving group: oxidative rearrangement of 1-IODO-2-methoxy-2-arylalkanes.

A new example of the good leaving group properties of hypervalent iodine is reported: oxidative rearrangement of 1-iodo-2-methoxy-2-arylalkanes 1 (R=alkyl) provides, via 1,2-aryl shift, alkyl benzyl ketones 3 in good yields.