Nov. 12th: Making Semiconductors Ferromagnetic: Opportunities and Challenges

Presentation by:Jacek Furdyna from the University of Notre Dame.

Abstract:
Introducing ferromagnetism into semiconductors holds out the promise of using the spin of the electron, alongside its charge, for the purpose of increasing the functionality of semiconductor devices. This is the focus of the emerging technology referred to as "spintronics". It has already been demonstrated that III-V semiconductor compounds (e.g., GaAs) can indeed be made ferromagnetic by replacing a fraction of the III-V lattice by substitutional Mn ions to form III{1-x}Mn{x}V alloys (e.g., Ga{1-x}Mn{x}As). The Mn enters the III-V lattice as divalent Mn++ ions, and thus act both as magnetic moments and as acceptors. It is the large concentration of holes generated by the acceptor nature of Mn++ which provides the mechanism for long-range ferromagnetic coupling between the Mn spins. In this talk I will discuss the various methods of preparing such III{1-x}Mn{x}V alloys; their representative ferromagnetic properties (the Curie temperature, magnetic domains, magnetic anisotropy, etc.) methods of controlling these properties; and I will present several examples of prototype spintronic devices based on these materials. And I will give special emphasis to the challenges that still remain to be overcome in order to bring these applications to practical reality.

~ It only takes one bottle cap moving at 23,000 mph to ruin your whole day ~

Nov. 19th: Surfing Gene Networks

Presentation by: Brett McKinney from the University of Tulsa and Laureate Institute for Brain Research.

Abstract:
Just as the connectivity of your social network depends on context, such as family, friends, or business relationships, a gene will exhibit differences in network connectivity that depend on contexts such as the environment, the organism or particular phenotype being investigated. Most network approaches define connections based simply on the correlation between genes but neglect context. I will discuss an information-theoretic, context-sensitive approach for inferring gene networks from the most common form of genetic variation, single nucleotide polymorphisms (SNPs). I will then discuss our representation of a SNP network as a dynamic probabilistic Markov chain and discuss a random surfer approach to identifying important nodes in the network.

~ It only takes one bottle cap moving at 23,000 mph to ruin your whole day ~

Dec. 3: Characterizing the Chemistry of the Milky Way Halo

Presentation by: Ian Roederer from the University of Texas at Austin.

Abstract:
To what extent does stellar nucleosynthesis trace the hierarchical merger history of the Galaxy, and to what degree is it necessary to know the kinematics of a star in order to correctly interpret its chemical enrichment history? We investigate these questions by performing detailed abundance analyses of stars selected by virtue of their kinematics. We compare the chemistry of the so-called inner and outer components of the halo, finding that the outer halo may be slightly more chemically diverse than the inner halo. We also examine the composition of one of the confirmed building blocks of the halo, a stellar stream, which has the same star-to-star chemical dispersion as field halo stars. These studies are naturally limited by the need to target relatively bright, hence nearby, stars in order to acquire sufficient signal; if we hope to eventually unravel the history of enrichment and accretion of the Galactic halo we must begin to examine samples of stars beyond the Solar neighborhood.

~ It only takes one bottle cap moving at 23,000 mph to ruin your whole day ~

Dec. 10: Title unavailable

Presentation by: Boris Kayser from Fermilab.

Abstract:
Not available

~ It only takes one bottle cap moving at 23,000 mph to ruin your whole day ~