60 research outputs found
Exclusive electroproduction and the quark structure of the nucleon
The natural interpretation of deep inelastic scattering is in terms of hard
scattering on QCD constituents of the target. We examine the relation between
amplitudes measured in exclusive lepto-production and the quark content of the
nucleon. We show that in the Bjorken limit, the natural interpretation of
amplitudes measured in these hard exclusive processes is in terms of the quark
content of the meson cloud and not the target itself. Therefore the most
efficient representation of these exclusive processes is in terms of leading
Regge amplitudes.Comment: 11 pages, 1 figure, typos corrected, references adde
Large-scale sequencing identifies multiple genes and rare variants associated with Crohn's disease susceptibility
Genome-wide association studies (GWASs) have identified hundreds of loci associated with Crohn's disease (CD). However, as with all complex diseases, robust identification of the genes dysregulated by noncoding variants typically driving GWAS discoveries has been challenging. Here, to complement GWASs and better define actionable biological targets, we analyzed sequence data from more than 30,000 patients with CD and 80,000 population controls. We directly implicate ten genes in general onset CD for the first time to our knowledge via association to coding variation, four of which lie within established CD GWAS loci. In nine instances, a single coding variant is significantly associated, and in the tenth, ATG4C, we see additionally a significantly increased burden of very rare coding variants in CD cases. In addition to reiterating the central role of innate and adaptive immune cells as well as autophagy in CD pathogenesis, these newly associated genes highlight the emerging role of mesenchymal cells in the development and maintenance of intestinal inflammation.Large-scale sequence-based analyses identify novel risk variants and susceptibility genes for Crohn's disease, and implicate mesenchymal cell-mediated intestinal homeostasis in disease etiology.Cellular mechanisms in basic and clinical gastroenterology and hepatolog
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