לוח שנה משולב

Abstract: Chern-Simons theories coupled to matter have a wide variety of applications ranging from anyonic physics to quantum gravity via the AdS/CFT correspondence. These theories enjoy a strong-weak duality that has been tested to a very good accuracy via large N computations. Scattering amplitudes are some of the most basic observables in QFT's. S matrices computed to all orders in the 't Hooft coupling serve as important testing grounds for the strong-weak duality. Although beginning with 4 point amplitudes this is doable, the complexity of the problem increases with the number of external legs. As a first step towards computing all loop arbitrary n point amplitudes, we address the problem of computing arbitrary n point tree level amplitudes. We show that BCFW recursion relations can be used to compute all tree level scattering amplitudes in terms of $2
ightarrow2$ scattering amplitude in $U(N)$ ${mathcal N}=2$ Chern-Simons (CS) theory coupled to matter in fundamental representation. As a byproduct, we also obtain a recursion relation for the CS theory coupled to regular fermions, even though in this case standard BCFW deformations do not have a good asymptotic behavior. We then proceed to take the first steps towards all loop computations of arbitrary n point amplitudes. As a first step we explain the result of arXiv:1505.06571, where it was shown that the $2
ightarrow 2$ scattering is tree level exact to all orders except in the anyonic channel, where it gets renormalized by a simple function of 't Hooft coupling. We show that tree level $2 o 2$ scattering amplitudes in 3d ${cal N}=2$ Chern-Simons theory coupled to a fundamental chiral multiplet are dual superconformal invariant. We further show that the large $N$ all loop exact amplitude also has dual superconformal symmetry, which implies dual superconformal symmetry is all loop exact which is in contrast to other known highly supersymmetric examples such as ${cal N}=4$ SYM and ABJM where the dual superconformal symmetry is in general anomalous. The presence of superconformal and dual superconformal symmetry indicate the existence of a Yangian symmetry, further providing indications that the N=2 theory may be integrable.

Quantum mechanics sets an upper bound on the amount of charge flow as well as on the amount of heat flow in ballistic one-dimensional channels. The two relevant upper bounds, which combine only fundamental constants, are the quantum of the electrical conductance, Ge=e2/h, and the quantum of the thermal conductance, Gth=0T=(π2kB2/3h)T. Remarkably, the latter does not depend on the particles charge, particles exchange statistics, and is expected also to be insensitive to the interaction strength among the particles. However, unlike the relative ease in observing the quantization of the electrical conductance, measuring accurately the thermal conductance is more challenging.
The universality of the Gth quantization in 1D ballistic channels was demonstrated for weakly interacting particles: phonons [1], photons [2], and in an electronic Fermi-liquid [3]. I will describe our recent experiments with heat flow in a strongly interacting system of 2D electrons in the fractional quantum Hall regime. In the lowest Landau level we studied particle-like states (v

Cancer is driven by genomic alterations, and can evolve in response to selective pressures. Sampling of tumour material however is a limiting factor for both diagnostics and research. Blood plasma contains cell-free fragments of circulating tumour DNA (ctDNA) that can be collected non-invasively. With advanced genomic techniques this becomes an effective source of information. “Liquid biopsy” assays are now entering clinical use for non-invasive molecular profiling of advanced cancers to guide targeted therapy. Serially-collection plasma samples can be used to track response to treatment, cancer progression and emergence of known or new resistance mechanisms. Methods that can detect minute amounts of ctDNA are being used to study early-stage cancer and for detection of minimal residual disease after initial definitive treatment.

Consider a random sequence of n bits that has entropy at least n-k, where k

An extensive body of research has established that the hippocampus plays a pivotal role in the encoding of new associations. Yet it remains unclear how entire episodes that unfold over time are bound together in memory. Real-life episodes can be viewed as a sequence of interrelated episodic elements, and their encoding may be incremental, such that each element that is encountered is registered to memory. Conversely, the episode may be stored in a temporary buffer and registered to long-term memory as a cohesive unit when it has come to closure. Using short film clips as memoranda, we find that hippocampal encoding-related activity is time-locked to the offset of the event, potentially reflecting the encoding of a bound representation to long-term memory. Notably, when distinct clips were presented in immediate succession, the hippocampus responded at the offset of each event, suggesting hippocampal activity is triggered the occurrence of event boundaries (transition between events). However, while brief film clips mimic several aspects of real-life, they are still discrete events. To determine whether event boundaries drive hippocampal activity in an ongoing experience, we analysed brain activity of over 200 participants who viewed a naturalistic film and found that the hippocampus responded both reliably and specifically to shifts between scenes. Taken together, these results suggest that during encoding of a continuous experience, event boundaries drive hippocampal processing, potentially supporting the transformation of the continuous stream of information into distinct episodic representations.