Integrated Calendar

Learned fear is a process allowing quick detection of associations between cues in the environment and prediction of imminent threat ahead of time. Adaptive function in a changing environment, however, requires organisms to quickly update this learned information and have the ability to hinder fear responses when predictions are no longer correct. Research on changing fear has highlighted several techniques, most of which rely on the inhibition of the learned fear response. An inherent problem with these inhibition techniques is that the fear commonly returns, for example with stress or even just with the passage of time. I will present research that examines new ways to flexibly control fear and the underlying brain mechanisms. I will describe a brain system mediating various strategies to modulate fear, and present findings suggesting a novel non-invasive technique that could be potentially used to permanently block or even erase fear memories.

The talk will discuss evidence for a high-energy physical analogy between the extensively studied coronae of stars and the putative, poorly understood coronae of accretion disks in active galactic
nuclei (AGNs). The current picture of magnetic energy powering the X-ray and radio emission of stellar coronae will be reviewed with an emphasis on recent results for large X-ray flares. Subsequently, empirical evidence will be presented suggesting that the X-ray and
radio emission from AGNs originates in a corona akin to stellar. It will be demonstrated how the AGN coronal plasma parameters can be estimated using basic Compton scattering and synchrotron self-
absorption theory. The physical similarities between stellar and AGN coronal sources will be pointed out along with some obvious differences. Finally, X-ray and radio observations will be proposed to further explore the AGN coronal hypothesis.

There are aspects in the cuprate high temperature superconductor (HTSC) phase diagram which remain unexplained despite the compelling amount of related studies. These include the origin of pseudogap phase, the universal dome structure of the superconducting region, as well as the abrupt drop in Tc at the x = 1/8 doping level in lanthanum based cuprates (known as the ‘1/8 anomaly’). Understanding these problems is considered to be a crucial step towards resolving the mechanism underlying HTSC.
To address these issues, we studied proximity effects in normal-metal/La2-xSrxCuO4 (LSCO) bilayers, providing evidence for paring, or precursor superconductivity, in the pseudogap regime of LSCO. We also demonstrated that the Tc of bilayers comprising underdoped LSCO films can be enhanced with respect to the bare LSCO film, manifesting the roles of the pairing scale and phase stiffness in shaping the superconducting dome. Finally, our scanning tunneling spectroscopy studies of x = 0.12 LSCO films reveal distinct spectral features of the recently predicted anti-phase ordering of the superconductor order parameter, an effect intimately related to the 1/8 anomaly.