Events at Physics |
Events on Tuesday, October 7th, 2008
- Chaos & Complex Systems Seminar
- Molecular mechanisms of synaptic growth: insights from the Drosophila neuromuscular junction
- Time: 12:05 pm
- Place: 4274 Chamberlin (Refreshments will be served)
- Speaker: Kate O'Connor-Giles, UW Department of Genetics
- Abstract: Neural function requires effective communication between neurons and their targets at synapses. Thus, the proper formation, growth and plasticity of synapses are critical to behavior. Despite this, the mechanisms that determine synapse size and complexity remain poorly understood. The Drosophila larval neuromuscular junction (NMJ) has become a powerful model system for dissecting the molecular mechanisms that regulate synaptic growth. Drosophila NMJs are dynamic structures that coordinate their size and strength with muscle growth and undergo changes in morphology and physiology in response to environmental stimuli and altered levels of activity. These processes depend on intercellular communication between neurons and their muscle targets. A retrograde (muscle to neuron) transforming growth factor (TGF-b/BMP) signal is required to promote synaptic growth, homeostasis and stability at NMJs. We have recently found that neuronal responsiveness to this signal is modulated by a presynaptic endocytic mechanism. This additional level of regulation underscores the high degree of molecular control over synaptic growth and highlights the importance to the organism of getting it right. I will present recent insights from studies at the Drosophila NMJ that have increased our understanding of how this complex task is achieved.
- Astronomy Colloquium
- Dark Energy and The Hubble Constant
- Time: 3:30 pm
- Place: 6515 Sterling Hall
- Speaker: Jim Condon, NRAO
- Abstract: Dark energy (DE) dominates the energy density and future expansion of the universe, and its nature is a major unsolved problem for theoretical physics. The equation-of-state and energy density of DE can be constrained observationally by comparing an accurate (< 3% rms) value of the Hubble constant with the known distance to the last-scattering surface of the cosmic microwave background. The Megamaser Cosmology Project (MCP) is now measuring geometric distances to water masers in the nuclei of distant Seyfert galaxies in order to obtain an accurate value of H0 free from the systematic errors associated with "standard candles." I will review the effect of DE on the Hubble constant and present the latest MCP results.
- Host: Professor Amy Barger