SCIENCEWEEK - PART A December 26, 2003 Vol. 7 Number 52A Contents: 1. Carbon Cycle, Fossil Fuels, and the Atmosphere 2. Materials Science: On Cracks 3. Physics of Fluids: On Drop Breakup 4. Genome Biology: On Heterochronic Genes 5. Medical Biology: Gene Silencing and Cancer 6. Medical Biology: On Clinical Proteomics =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=