Reflection of neutrons from an optical grating

Specular and off-specular neutron intensities were measured at grazing incidence from an optical grating. Thee periodicity of the grating was determined from the locations of the intensity peaks in the off-specular data. An analysis of the widths of the off-specular intensity peaks showed that the effect of the coherence length of the neutron beam on the determination of a surface length scale {approximately}30 {mu}m was negligible compared to that of the instrument resolution. Although the structure of an optical grating used in this paper is simple, it has served to illustrate the simple relationship between the off-specular data structure and the real-space properties. For more general rough systems, a practical theoretical model will be needed to relate the off-specular data to the real-space roughness structure so that the diffusive data can be analyzed. Owing to the intrinsic complexity of diffuse scattering, the development of such a theoretical model will be a significant technical challenge, and its solution will constitute a major breakthrough in the development of the diffuse reflectivity technique for rough surface/interface characterization

Resolution and Coherence Length at a Pulsed Neutron Reflectometer

U of I OnlyRestricted to UIUC communit

Resolution and Coherence Length at a Pulsed Neutron Reflectometer

U of I OnlyRestricted to UIUC communit

Reflection of Neutrons from an Optical Grating

Specular and off-specular neutron intensities were measured at grazing incidence from an optical grating. Thee periodicity of the grating was determined from the locations of the intensity peaks in the off-specular data. An analysis of the widths of the off-specular intensity peaks showed that the effect of the coherence length of the neutron beam on the determination of a surface length scale {approximately}30 {mu}m was negligible compared to that of the instrument resolution. Although the structure of an optical grating used in this paper is simple, it has served to illustrate the simple relationship between the off-specular data structure and the real-space properties. For more general rough systems, a practical theoretical model will be needed to relate the off-specular data to the real-space roughness structure so that the diffusive data can be analyzed. Owing to the intrinsic complexity of diffuse scattering, the development of such a theoretical model will be a significant technical challenge, and its solution will constitute a major breakthrough in the development of the diffuse reflectivity technique for rough surface/interface characterization

Rare predicted loss-of-function variants of type I IFN immunity genes are associated with life-threatening COVID-19

BackgroundWe previously reported that impaired type I IFN activity, due to inborn errors of TLR3- and TLR7-dependent type I interferon (IFN) immunity or to autoantibodies against type I IFN, account for 15-20% of cases of life-threatening COVID-19 in unvaccinated patients. Therefore, the determinants of life-threatening COVID-19 remain to be identified in similar to 80% of cases.MethodsWe report here a genome-wide rare variant burden association analysis in 3269 unvaccinated patients with life-threatening COVID-19, and 1373 unvaccinated SARS-CoV-2-infected individuals without pneumonia. Among the 928 patients tested for autoantibodies against type I IFN, a quarter (234) were positive and were excluded.ResultsNo gene reached genome-wide significance. Under a recessive model, the most significant gene with at-risk variants was TLR7, with an OR of 27.68 (95%CI 1.5-528.7, P=1.1x10(-4)) for biochemically loss-of-function (bLOF) variants. We replicated the enrichment in rare predicted LOF (pLOF) variants at 13 influenza susceptibility loci involved in TLR3-dependent type I IFN immunity (OR=3.70[95%CI 1.3-8.2], P=2.1x10(-4)). This enrichment was further strengthened by (1) adding the recently reported TYK2 and TLR7 COVID-19 loci, particularly under a recessive model (OR=19.65[95%CI 2.1-2635.4], P=3.4x10(-3)), and (2) considering as pLOF branchpoint variants with potentially strong impacts on splicing among the 15 loci (OR=4.40[9%CI 2.3-8.4], P=7.7x10(-8)). Finally, the patients with pLOF/bLOF variants at these 15 loci were significantly younger (mean age [SD]=43.3 [20.3] years) than the other patients (56.0 [17.3] years; P=1.68x10(-5)).ConclusionsRare variants of TLR3- and TLR7-dependent type I IFN immunity genes can underlie life-threatening COVID-19, particularly with recessive inheritance, in patients under 60 years old