of Intel Research, Santa Clara, with special thanks to my mentor Carl Livadas for all the help, support and discussions. I am also thankful to Eve M. Schooler for her encouragement and supervision. Above all, I am thankful to Prof. Roch Guerin for providing me with the opportunity to undertake

Many styles of multimedia conferencing are likely to co-exist on the Internet, and many of them share the need to invite users to participate. The Session Invitation Protocol (SIP) is a simple protocol designed to enable the invitation of users to participate in such multimedia sessions. It is not tied to any specific conference control scheme, providing support for either loosely or tightly controlled sessions. In particular, it aims to enable user mobility by relaying and redirecting invitations to a user’s current location. This document is a product of the Multiparty Multimedia Session Control (MMUSIC) working group of the Internet Engineering Task Force. Comments are solicited and should be addressed to the working group’s mailing list at

Keywords H5.m. Information interfaces and presentation (e.g., HCI):

M. Yvan Petit, directeur de mémoire Département de génie mécanique à l'École de technologie supérieure M. Stefan Parent, codirecteur, chimrgien orthopédiste Département de chimrgie à l'hôpital Sainte-Justine

ered while the hands were at rest. At the point of per- circles in Figure 2A) did not differ significantly from ceptual equality, the comparison tap was not signifi- those in the first group (F1,20 < 0.58; p> 0.45), and the cantly different from the test tap (M = 94 % of test tap, greatest

rule correctly captures the subtyping relation (that relation which establishes which sets of functions can replace another given set m eve ~ contezt). A covariant relation, instead, characterizes the speczalizatzon of code (i.e., the definition of new code which replaces old def-initions in some

easily VlSUahzed m terms of a two-dimensional format for formulas. An implementation by Eve Cohen has yielded encouraging preliminary results. Some implementation issues are discussed.

A photometric criterium (m parameter) deduced from the Geneva 7-colour photometry provides good Am-candidates. In the classical magnitude vs colour diagrams of clusters, the Am-stars tend to be above the main sequence. Following points will be examined: a) the validity of the photometric criterium

of the module is illuminated by light waveforms with peak optical power between 1 and 10 mW (at 780 nm). We do not see how three of these behaviors could be immediately useful for Eve, and omit their description for brevity. However, the fourth behavior can, under some conditions, be used by Eve to control Bob

astro-ph/9806015 Massless (pseudo-)scalar seeds of CMB anisotropy R. Durrer(1), M. Gasperini(2), M. Sakellariadou(1),(3), G. Veneziano(4)