Saturday Morning Lecture - SFU

We are Made of Starstuff: Producing Heavy Elements in Astrophysics - Nicole Vassh (TRIUMF)

In this lecture, I will discuss the prevailing theories on how and where elements such as gold and uranium are formed, and highlight how our new capabilities in nuclear physics and astrophysics are serendipitously aligning towards a golden era of illuminating heavy element origins.

The building blocks of the world around us have been a focus of scientific research for hundreds of years across world-wide cultures. We know that matter is made of molecules comprised of different combinations of elements like carbon and oxygen. Elements are themselves comprised of more fundamental constituents, the proton and the neutron. These can be combined to form different nuclear species such as uranium-235 (with 92 protons and 143 neutrons), which is the primary fuel used in nuclear power reactors. But how did these elements get here on Earth to begin with?The answer is closely connected to our own cosmic origins, for it is in the heart of stars that elements crucial to life such as carbon are formed.

After decades of observation of numerous stars, we now know that their conditions are extreme enough to fuse elements up to iron, but to explain the origin of heavier elements requires more exotic events, such as a core-collapse supernova (the explosive death of a star). Explosive astrophysical events such as this eject the elements produced into interstellar space where they can then be part of the initial gas that forms a new star. Additionally, explosive events leave behind a “remnant” such as a neutron star which is a dense object comprised mainly of neutrons. These remnants can eventually find one another in space, merge, and correspondingly undergo their own explosive nucleosynthesis to produce heavy elements. Within just the last few years, thanks to gravitational wave detectors, we have begun to observe such mergers in real time, along with the light they emit, which is imprinted with information about the elements produced.

From radioactivity to brain function: 60 years of Positron Emission Tomography (PET) - Vesna Sossi (UBC)

Brain PET originally started as a quantitative technique to investigate brain metabolism and blood flow. While compared to today’s standards the studies performed in the early days would be considered technically very simple, they revolutionized our understanding of brain function as related to health, disease and personality, with related health and social impact. Rapid advancements in detector technology, PET tracer development and data processing algorithms, facilitated by increasing computing power, led to increasingly more accurate and selective imaging of specific neurochemical targets and processes. More advanced image analysis methods are now shedding new light on neurochemical connectivity and its interplay with functional and structural networks revealing the complexity of brain function and hopefully identifying new therapeutic targets for several devastating brain disorders.

This talk will discuss this fascinating journey emphasizing the interplay between scientific discoveries and developments in instrumentation and data analysis and how their synergies are opening news fields of investigation and ultimately facilitate clinical applications.