Single-cell multi-omics analysis of the immune response in COVID-19

Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts (CD16+C1QA/B/C+) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34+ hematopoietic stem/progenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8+ T cells and an increased ratio of CD8+ effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy

Time-resolved photoluminescence from hot two-dimensional carriers in GaAsGaAlAs MQWS

Picosecond time-resolved measurements of luminescence from hot carriers confined in GaAsGaAlAs multiple quantum wells show that energy loss rates are substantially slower than those predicted for 2D carriers. We review our recent experiments and present results for photoexcitation of (1) GaAs layers only, (2) both GaAs and GaAlAs layers. We compare the energy loss rates in samples with different well widths. Finally, we present measurements of hot 2D carrier relaxation in the presence of high magnetic fields; at low fields the energy loss rate is reduced, but for B > 9 T we observe a rapid increase. © 1986

Picosecond photoluminescence measurements of Landau level lifetimes and time dependent Landau level linebroadening in modulation-doped GaAs-GaAlAs multiple quantum wells

We report the first picosecond time-resolved photoluminescence measurementsof hot-carrier relaxation in a modulation-doped GaAs-GaAlAs MQW in the presence of strong magnetic fields. We have measured the lifetimes of carriers in excited Landau levels and have determined the time-dependent carrier temperature. We find that the cooling rate is slower in applied field tthan at B=0; also there is a significant increase in the cooling rate for B {greater-than or approximate} 10T. We report also the observation of highly time-dependent linewidths of the Landau levels. © 1985

The management of isolated distal radius fractures in children.

In a consecutive series of 175 forearm fractures requiring manipulation in children who presented to the John Radcliffe Hospital between 1 January 1991 and 30 June 1992, 23 had isolated distal radius fractures, all of which required manipulation for unacceptable angulation or displacement. We had previously noted that these fractures had a high incidence of loss of position leading to malunion. The 23 patients were randomly allocated to one of two treatment groups: either manipulation and cast alone, or manipulation and percutaneous Kirschner wiring with cast. These two groups were followed up clinically and radiographically until union occurred. Those fractures treated by percutaneous wiring had no significant complications, and all had a satisfactory result. The fractures treated by manipulation and casting alone required further manipulation in 10 cases (91%). We conclude that these problematic fractures should be treated by stabilisation with percutaneous wiring

Time-resolved photoluminescence of two-dimensional hot carriers in GaAs-AlGaAs heterostructures

We have studied the picosecond time dependence of luminescence from a two-dimensional electron system following absorption of an ultrashort light pulse. From our measurements we determine the temporal evolution of the carrier temperature, finding that the cooling of hot carriers is suppressed by a factor 60 below that predicted on a three-dimensional nondegenerate-electron model. Additionally, we determine the electron-hole radiative life-time and invoke a hole trap to explain shortened luminescence lifetimes at low carrier densities. © 1984 The American Physical Society

HOT ELECTRON RELAXATION AND TRAPPING IN MODULATION-DOPED GaAs/GaA1As MULTIPLE QUANTUM WELL HETEROSTRUCTURES.

There is much current interest in determining the energy relaxation processes of hot carriers confined in quantum well heterostructures. We present measurements of time-resolved photoluminescence from hot carriers and from carrier recombination at shallow traps. The experimental technique is basically the same as described previously except that the laser (h upsilon //L equals 1. 76 eV) excites carriers only in the GaAs layers

Early human lung immune cell development and its role in epithelial cell fate

Studies of human lung development have focused on epithelial and mesenchymal cell types and function, but much less is known about the developing lung immune cells, even though the airways are a major site of mucosal immunity after birth. An unanswered question is whether tissue-resident immune cells play a role in shaping the tissue as it develops in utero. Here, we profiled human embryonic and fetal lung immune cells using scRNA-seq, smFISH, and immunohistochemistry. At the embryonic stage, we observed an early wave of innate immune cells, including innate lymphoid cells, natural killer cells, myeloid cells, and lineage progenitors. By the canalicular stage, we detected naive T lymphocytes expressing high levels of cytotoxicity genes and the presence of mature B lymphocytes, including B-1 cells. Our analysis suggests that fetal lungs provide a niche for full B cell maturation. Given the presence and diversity of immune cells during development, we also investigated their possible effect on epithelial maturation. We found that IL-1β drives epithelial progenitor exit from self-renewal and differentiation to basal cells in vitro. In vivo, IL-1β-producing myeloid cells were found throughout the lung and adjacent to epithelial tips, suggesting that immune cells may direct human lung epithelial development