Masking of filtered noise bursts by synthetic vowels.

The present investigation assessed the simultaneous and temporal masking produced by computer-generated synthetic vowels. The durations (100 and 200 ms) of each of four vowel-like maskers were employed. The masker was presented at 70 dB SPL. The probe signals were three filtered noise bursts whose spectral distributions corresponded to regions of high spectral energy in three English stop consonants. Quiet and masked thresholds were determined using the method of adjustment. Data are reported for two experienced listeners who participated in all the listening conditions. The results were generally in accord with the results of masking experiments using nonspeech signals in that both the frequency specificity of masking and temporal masking effects were demonstrated.     

Extremal dependence measure and extremogram: the regularly varying case

The dependence of large values in a stochastic process is an important topic in risk, insurance and finance. The idea of risk contagion is based on the idea of large value dependence. The Gaussian copula notoriously fails to capture this phenomenon. Two notions in a process or vector context which summarize extremal dependence in a function comparable to a correlation function are the extremal dependence measure (EDM) and the extremogram. We review these ideas and compare the two tools and end with a central limit theorem for a natural estimator of the EDM which allows drawing confidence bands comparable to those provided by Bartlett’s formula in a classical context of sample correlation functions.     

Domains of attraction and regular variation in IRd

A general form for regular variation in IR² is introduced and applied to domains of attraction of stable distribution in IR² where the components have different indices. The situation in IR^d with d > 2 is more complicated but not essentially different. For simplicity this paper is limited to IR².     

A discussion on mean excess plots

The mean excess plot is a tool widely used in the study of risk, insurance and extreme values. One use is in validating a generalized Pareto model for the excess distribution. This paper investigates some theoretical and practical aspects of the use of the mean excess plot.     

New industrial fluoropolymer science and technology

Teflon® AF, a family of copolymers of perfluoro-2,2-dimethyldioxole with tetrafluoroethylene, and Cytop®, a ring-cyclized homopolymer of CF₂=CFO(CF₂)₂CF=CF₂ are the first commercial amorphous perfluoroplastics which combine high optical clarity and solubility with outstanding chemical, thermal and electrical properties. The processes for making these materials are described and recent structure-property studies that reveal dramatic substituent effects on polymer T_g and related properties are reviewed. The results of some initial fundamental kinetic studies on fluorinated free-radical cyclizations that relate to efficient cyclopolymerization of fluorinated dienes and the design of new ring-containing fluoroplastics are discussed.