Baryon stopping and particle production in Pb+Pb collisions at 158 GeV/nucleon are studied as a function of the collision centrality using new proton, antiproton, charged kaon and charged pion production data measured with the NA49 experiment at the CERN Super Proton Synchrotron (SPS). Stopping, which is measured by the shift in rapidity of net protons or baryons from the initial beam rapidity, increases in more central collisions. This is expected from a geometrical picture of the collisions. The stopping data are quantitatively compared to models incorporating various mechanisms for stopping. In general, microscopic transport calculations which incorporate current theoretical models of baryon stopping or use phenomenological extrapolations from simpler systems overestimate the dependence of stopping on centrality. Approximately, the yield of produced pions scales with the number of nucleons participating in the collision. A small increase in yield beyond this scaling, accompanied by a small suppression in the yield of the fastest pions, reflects the variation in stopping with centrality. Consistent with the observations from central collisions of light and heavy nuclei at the SPS, the transverse momentum distributions of all particles are observed to become harder with increasing centrality. This effect is most pronounced for the heaviest particles. This hardening is discussed in terms of multiple scattering of the incident nucleons of one colliding nucleus as they traverse the other nucleus and in terms of rescattering within the system of produced particles.

Hadronic spectra from collisions of heavy ions at ultrarelativistic energies are discussed, concentrating on recent measurements at the SPS of central Pb+Pb collisions at 158 GeV/nucleon, which are compared to collisions of lighter ions and at lower beam energies. Baryon stopping is seen to be larger for heavier systems and lower energies. Total yields of pions and kaons scale with the number of participants in central collisions at the SPS; in particular, the K/[pi] ratio is constant between central S+S and Pb+Pb at the SPS. Transverse mass spectra indicate significantly larger radial flow for the heavier systems. At midrapidity, an enhancement of [pi]−/[pi] and K−/K at low P{sub T} are best explained by final state Coulomb interaction with the residual charge of the fireball.

This proceedings volume brings together the contributions of experts from different fields within the nuclear physics community. Topics such as rare kaon decays, astrophysics, relativistic heavy ion collisions, and few-GeV electromagnetic probes are covered. The strange quark plays a vital role in understanding such diverse phenomena as CP violation (article by Lincoln Wolfenstein), the ?spin crisis? (article by Brad Filipone), and supernova explosions (article by Chris Fryer). Additional topics of interest are parity violation experiments, strangeness content of the proton, and enhanced strangeness production at CERN and RHIC. This unique blend of recent results, with a focus on the role of the strange quark, shows the prominence of strangeness in nuclear physics over the past 50 years.