A new method of predicting of gas chromatographic retention indices for polychlorinated dibenzofurans (PCDFs)

A new method has been developed to describe the quantitative relationship between molecular structures of PCDFs and their gas chromatographic retention indices on a 30-m fused silica column coated with DB-5 stationary phase. The regression equation is derived with a multiple correlation coefficient greater than 0.9995. The highest residual is 20 index units. The standard deviation is less than 7 index units. Using this regression equation, the retention indices of PCDFs for which data is not available have also been predicted. (C) 2000 Elsevier Science Ltd. All rights reserved.

Preparation and characteristic of a new class of silica/polyimide nanocomposites

A new class of silica/polyimide nanocomposites was successfully prepared by the sol-gel reaction, tetraethoxysilane, (TEOS), was hydrolyzed by the water released from imidization at low and high temperature. Silica particles with diameter of around 30-50 nm were observed in the hybrid films by scanning electron microscopy. The flame retardance, decomposition temperature and glass transition temperature of the film increased with increasing silica content. The tensile strength increased slightly while the elongation at break of the films decreased with increasing silica content. (C) 2002 Kluwer Academic Publishers.

Form, fi gure, and the experience of time in seven southern composers of the 1950s-60s

After the 1980s it is diffi cult, following stylistic criteria, to draw a map of contemporary academic music. All styles are compossible, and all are practiced. In this context, the geographical entity “South of Italy” does not stand out for a musical identity with special technical-stylistic features. Rather, at a socio-cultural level, the South remains today – in music no less than in all areas where there is a gap between top development and stagnation – a land of emigrants: six out of the seven composers treated (Ivan Fedele, Giuseppe Colardo, Rosario Mirigliano, Giuseppe Soccio, Nicola Cisternino, Biagio Putignano, Paolo Aralla) live in the North of Italy. The positive aspect of this is the affi nity of the South with the transnational and superstructural community of contemporary music, which from European and Western has now become almost global. The composers under consideration belong to the generation of the ‘50s, rooted in the serial and post-serial movements (from which Franco Donatoni, Luciano Berio, Luigi Nono, Salvatore Sciarrino, Giacinto Scelsi, are the principals models, to mention only the Italians), dipped in the general phenomenon of timbrism (particularly spectralism), and acquainted with electronics. They draw from these sources various instruments of compositional technique and aspects of their poetics. In particular these composers, active from the ‘80s, develop new ways of construction of the temporal form of music. They share the goal to establish a new continuity, different from the tonal one but at the same time transcending the serial and post-serial disintegration and fragmentation. The primary means to this end is a new enhancement of the category of fi gure, as a clear and distinct, recognizable aggregate of pitches, intervals, register, durations, timbre, articulation, dynamics, and texture. Each composer elaborates the atonal fi gural material in different ways, emphasizing one aspect or another. For example, Fedele (1953) is a master in the management of form per se, Colardo (1953) in the activation of disturbed harmonic effects, Mirigliano (1950) in the creation of a slight tension from the smallest vibrations of sound, Soccio (1950) in the set up of movement by means of accumulations and discharges of energy, Cisternino (1957) in a Cagean-Scelsian emphasis on sound as such, Putignano (1960) in the suspension of time through the succession and transformation of images, Aralla (1960) in the foundation of form from below, from the concreteness of sound.

New Notions of Reduction and Non-Semantic Proofs of β-Strong Normalization in Typed λ-Calculi

Two new notions of reduction for terms of the λ-calculus are introduced and the question of whether a λ-term is beta-strongly normalizing is reduced to the question of whether a λ-term is merely normalizing under one of the new notions of reduction. This leads to a new way to prove beta-strong normalization for typed λ-calculi. Instead of the usual semantic proof style based on Girard's "candidats de réductibilité'', termination can be proved using a decreasing metric over a well-founded ordering in a style more common in the field of term rewriting. This new proof method is applied to the simply-typed λ-calculus and the system of intersection types.

Addendum to "New Notions of Reduction and Non-Semantic Proofs of β-Strong Normalization in Typed λ-Calculi"

This is an addendum to our technical report BUCS TR-94-014 of December 19, 1994. It clarifies some statements, adds information on some related research, includes a comparison with research be de Groote, and fixes two minor mistakes in a proof.