Integrated Calendar

Drug addiction is a chronically relapsing disorder characterized by compulsive drug use despite catastrophic personal consequences (e.g., loss of family, job) and even when the substance is no longer perceived as pleasurable. In this talk, I will present results of human neuroimaging studies, utilizing a multimodal approach (neuropsychology, functional magnetic resonance imaging, event-related potentials recordings), to explore the neurobiology underlying the core psychological impairments in drug addiction (impulsivity, drive/motivation, insight/awareness) as associated with its clinical symptomatology (intoxication, craving, bingeing, withdrawal). The focus of this talk is on understanding the role of the dopaminergic mesocorticolimbic circuit, and especially the prefrontal cortex, in higher-order executive dysfunction (e.g., disadvantageous decision-making such as trading a car for a couple of cocaine hits) in drug addicted individuals. The theoretical model that guides the presented research is called iRISA (Impaired Response Inhibition and Salience Attribution), postulating that abnormalities in the orbitofrontal cortex and anterior cingulate cortex, as related to dopaminergic dysfunction, contribute to the core clinical symptoms in drug addiction. Specifically, our multi-modality program of research is guided by the underlying working hypothesis that drug addicted individuals disproportionately attribute reward value to their drug of choice at the expense of other potentially but no-longer-rewarding stimuli, with a concomitant decrease in the ability to inhibit maladaptive drug use. In this talk I will also explore whether treatment (as usual) and 6-month abstinence enhance recovery in these brain-behavior compromises in treatment seeking cocaine addicted individuals. Promising neuroimaging studies, which combine pharmacological (i.e., oral methylphenidate, or RitalinTM) and salient cognitive tasks or functional connectivity during resting-state, will be discussed as examples for using neuroimaging in the empirical guidance for the development of effective neurorehabilitation strategies (including cognitive training) in drug addiction.

The "active" aspect of active matter, from the statistical-physics perspective, is the breaking of detailed balance in the microscopic dynamics. Hence, modelling of nonequilibrium microscopic conditions and their implications, such as the appearance of emergent equilibrium, is now active as a field of research. Recent theory studies and experiments with ultracold ions trapped in vacuum, make surprising contact with these questions;
A fundamental model of transport in a noisy environment is that of the Brownian ratchet, or Brownian motor. It models the emergence of nonvanishing currents in a noisy system despite the vanishing of the mean force. Crucially based on symmetry breaking, it is a basic model for some of the physics underlying, e.g., biological molecular motors. I will discuss self-organized ion crystals featuring transport of ratchet-like discrete solitons. The rate and direction of selective topological-charge transport can be described as a Kramer's escape applied to a collective coordinate, with an emergent effective temperature [1].
If time permits, I will briefly discuss other relevant physics encountered with trapped ions - stochastic dynamics with single ions [2], and the simulation of microscopic friction models [3].

[1] J. Brox, P. Kiefer, M. Bujak, T. Schaetz (experiment), H. Landa (theory), PRL 119, 153602 (2017).
[2] V. Roberdel, A. Maitra, D. Leibfried, D. Ullmo, and H. Landa, in preparation.
[3] T. Fogarty, C. Cormick, H. Landa, V. M. Stojanović, E. Demler, and G. Morigi, PRL 115, 233602 (2015).

Increasing evidence indicates that the brain can control immunity. But how is the brain informed of the state of the immune response? What information is available to the brain regarding the immune system, and how do these essential systems communicate and interact? In this talk, I will try to bridge these gaps. I will demonstrate how specific activity in the brain affects the immune response, and how the peripheral nervous system can convey signals from the brain to the periphery to regulate immunity.

Quantum Material, as exemplified by unconventional superconductors and topological insulators, is a fascinating and rapidly developing field of modern physics. High-temperature superconductivity in cupper and iron based materials, with critical temperature well above what was anticipated by the BCS, remains a major unsolved physics problem today. The challenge of this problem is symbolized by a complex phase diagram consists of intertwined states with extreme properties in addition to unconventional superconductivity. None of them can be described by conventional theory, thus compounding the difficulty to understand high-temperature superconductivity itself as these states are different manifestations of the same underlying physical system, making an integrated understanding a necessity.

Angle-resolved photoemission spectroscopy (ARPES), derived from Einstein’s formulation of photoelectric effect, has emerged as a leading experimental tool to push the frontier of this important field of modern physics. Over the last three decades, the improved resolution and carefully matched experiments have been the keys to turn this technique into a sophisticated many-body physics tool. As a result, ARPES played a critical role in setting the intellectual agenda by testing new ideas and discovering surprises. ARPES has impacted both the field of unconventional superconductors and topological phases of matter.




In this talk, we discuss ARPES evidence for a general theme of high temperature superconductivity - cooperative enhancement and positive feedback loop of different interactions exemplified by electron-electron and electron-phonon interactions. The accumulated evidence comes from an expanded version of angle-resolved photoemission spectroscopy and its match to in-situ material synthesis. In such experiments, the precision measurements of electron’s energy, momentum and time dynamics provide evidence for cooperative interactions as a pathway to increase the superconducting transition temperature. An outlook for ARPES development and application for other quantum materials will also be discussed.