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Quantum dots (QDs) are conducting regions which can localize few charge carriers, and where the energy spectrum is dominated by Coulomb repulsion. QDs can be as large as few hundreds of nanometers, or as small as a single molecule, their sizes depending on their physical realization – whether in two-dimensional materials, nanowires, molecular systems.
In my talk I will describe our work on a new type of an atomically-sized QD, realized in defects residing in ultrathin two-dimensional insulators. These defect-dots are found in layered materials such as hexagonal Boron Nitride (hBN), which we study by their assembly into stacked devices. By using graphene electrodes, we are able to electronically couple to the QD, while allowing the QD energy to be externally tuned exploiting the penetration of electric field through graphene.
A consequence of the structure of our devices is that the defect QDs are placed at atomic distance to the conductors on both sides. I will show how the presence of such energy-tunable, atomically sized QDs at nanometer proximity to other conducting systems opens new opportunities for sensitive measurements, including use of QDs as highly sensitive spectrometers [1], or as single electron transistors, unique in their sensitivity to local electric fields at the nanometer scale [2]. I will discuss our future prospects of using defect QDs as quantum sensors.

References

1. Devidas, T.R., I. Keren, and H. Steinberg, Spectroscopy of NbSe2 Using Energy-Tunable Defect-Embedded Quantum Dots. Nano Letters, 2021. 21(16): p. 6931-6937.
2. Keren, I., et al., Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene. Nature Communications, 2020. 11(1): p. 3408.

The warfare between bacteria and phages - viruses that infect bacteria - has been raging for billions of years. During this time both sides have evolved various attack and defense systems. In this talk I will describe 3 related projects: 1. Is there an optimal number of such defense or anti-defense systems? 2. How can different phages which prey on the same bacteria co-exist, in contradiction with the expected competitive exclusion? 3. Some phages have developed the ability to garner environmental information, enabling them to make more "intelligent" decisions. How much is such intelligence worth, in terms of other resources?
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Promiscuous binding of Janus kinases (JAKs) to class I/II cytokine receptors has been
reported, yet its role in signaling is unclear. To systematically explore JAK pairing in type
I interferon (IFN-I) signaling, we generated an artificial IFN-I receptor (AIR) by replacing
the extracellular domains of IFNAR1 and IFNAR2 with anti-mEGFP and mCherry
nanobodies. The heterodimeric AIR restored near-native IFN-I activity, while the
homomeric variant of IFNAR2 (AIR-dR2) initiated much weaker signaling despite
harboring docking sites for STAT proteins. To further investigate the roles of JAKs on the
receptors, knockout (KO) JAK1, JAK2, TYK2, and JAK2/TYK2 were generated. JAK1
KO led to a complete loss of IFN-I signaling, partially restored by TYK2 overexpression.
TYK2 KO cells retained partial activity, which was elevated by JAK1 overexpression,
suggesting both JAKs partially substitute each other.
Conversely, JAK2 KO only moderately impacted the biological activity of IFN-Is, even in
JAK2/TYK2 KO cells. Live cell micropatterning confirmed promiscuous binding of JAK1,
JAK2, and TYK2 to IFNAR1 and IFNAR2. Moreover, the identities of recruitment of
different JAKs on the ICDs were related to their respective concentrations in the cell, which
varies between cell lines. Yet, the efficiency of JAK cross-phosphorylation and
downstream signaling also depend on their identity. Promiscuity of JAK binding was also
observed for IFNL1, IL-10-Rbβ, TPOR, and GHR but not for EPOR, accompanied by
different downstream signaling activities. The competitive binding of JAKs to cytokine
receptors and the highly diverse absolute and relative JAK expression levels in different
cell types can account for cell type-dependent signaling pleiotropy observed for cytokine
receptors.