8 research outputs found
Rank-2 Fano bundles over a smooth quadric Q 3
In the present paper we examine rank-2 stable bundles over Q3 with c1 = 0 and c2 = 2 or 4
A high finesse bow-tie cavity for strong atom-photon coupling in Rydberg arrays
We report a high-finesse bow-tie cavity designed for atomic physics
experiments with Rydberg atom arrays. The cavity has a finesse of and
a waist of m at the cesium D2 line ( nm). With these
parameters, the cavity induces strong coupling between a single atom and a
single photon, corresponding to a cooperativity per traveling mode of at
the cavity waist. To trap and image atoms, the cavity setup utilizes two
in-vacuum aspheric lenses with numerical aperture (N.A.) and is capable
of housing N.A. microscope objectives. In addition, the large atom-mirror
distance ( cm) provides good optical access and minimizes stray
electric fields at the position of the atoms. This cavity setup can operate in
tandem with the Rydberg array platform, creating a fully connected system for
quantum simulation and computation
Dormant Pathogenic CD4(+) T Cells Are Prevalent in the Peripheral Repertoire of Healthy Mice
Thymic central tolerance eliminates most immature T cells with autoreactive T cell receptors (TCR) that recognize self MHC/peptide complexes. Regardless, an unknown number of autoreactive CD4+Foxp3− T cells escape negative selection and in the periphery require continuous suppression by CD4+Foxp3+ regulatory cells (Tregs). Here, we compare immune repertoires of Treg-deficient and Treg-sufficient mice to find Tregs continuously constraining one-third of mature CD4+Foxp3− cells from converting to pathogenic effectors in healthy mice. These dormant pathogenic clones frequently express TCRs activatable by ubiquitous autoantigens presented by class II MHCs on conventional dendritic cells, including selfpeptides that select them in the thymus. Our data thus suggest that identification of most potentially autoreactive CD4+ T cells in the peripheral repertoire is critical to harness or redirect these cells for therapeutic advantage
Self and Microbiota-Derived Epitopes Induce CD4⁺ T Cell Anergy and Conversion into CD4⁺Foxp3⁺ Regulatory Cells
The physiological role of T cell anergy induction as a key mechanism supporting self-tolerance remains undefined, and natural antigens that induce anergy are largely unknown. In this report, we used TCR sequencing to show that the recruitment of CD4+CD44+Foxp3−CD73+FR4+ anergic (Tan) cells expands the CD4+Foxp3+ (Tregs) repertoire. Next, we report that blockade in peripherally-induced Tregs (pTregs) formation due to mutation in CNS1 region of Foxp3 or chronic exposure to a selecting self-peptide result in an accumulation of Tan cells. Finally, we show that microbial antigens from Akkermansia muciniphila commensal bacteria can induce anergy and drive conversion of naive CD4+CD44-Foxp3− T (Tn) cells to the Treg lineage. Overall, data presented here suggest that Tan induction helps the Treg repertoire to become optimally balanced to provide tolerance toward ubiquitous and microbiome-derived epitopes, improving host ability to avert systemic autoimmunity and intestinal inflammation
Dipolar quantum solids emerging in a Hubbard quantum simulator
In quantum mechanical many-body systems, long-range and anisotropic
interactions promote rich spatial structure and can lead to quantum
frustration, giving rise to a wealth of complex, strongly correlated quantum
phases. Long-range interactions play an important role in nature; however,
quantum simulations of lattice systems have largely not been able to realize
such interactions. A wide range of efforts are underway to explore long-range
interacting lattice systems using polar molecules, Rydberg atoms, optical
cavities, and magnetic atoms. Here, we realize novel quantum phases in a
strongly correlated lattice system with long-range dipolar interactions using
ultracold magnetic erbium atoms. As we tune the dipolar interaction to be the
dominant energy scale in our system, we observe quantum phase transitions from
a superfluid into dipolar quantum solids, which we directly detect using
quantum gas microscopy with accordion lattices. Controlling the interaction
anisotropy by orienting the dipoles enables us to realize a variety of stripe
ordered states. Furthermore, by transitioning non-adiabatically through the
strongly correlated regime, we observe the emergence of a range of metastable
stripe-ordered states. This work demonstrates that novel strongly correlated
quantum phases can be realized using long-range dipolar interaction in optical
lattices, opening the door to quantum simulations of a wide range of lattice
models with long-range and anisotropic interactions
Commensal epitopes drive differentiation of colonic T regs
© 2020 The Authors. The gut microbiome is the largest source of intrinsic non-self-antigens that are continuously sensed by the immune system but typically do not elicit lymphocyte responses. CD4+ T cells are critical to sustain uninterrupted tolerance to microbial antigens and to prevent intestinal inflammation. However, clinical interventions targeting commensal bacteria-specific CD4+ T cells are rare, because only a very limited number of commensal-derived epitopes have been identified. Here, we used a new approach to study epitopes and identify T cell receptors expressed by CD4+Foxp3+ (Treg) cells specific for commensal-derived antigens. Using this approach, we found that antigens from Akkermansia muciniphila reprogram naïve CD4+ T cells to the Treg lineage, expand preexisting microbe specific Tregs, and limit wasting disease in the CD4+ T cell transfer model of colitis. These data suggest that the administration of specific commensal epitopes may help to widen the repertoire of specific Tregs that control intestinal inflammation