Deoxyribonucleic Acid Encoded and Size-Defined π-Stacking of Perylene Diimides.

Funder: University of CambridgeNatural photosystems use protein scaffolds to control intermolecular interactions that enable exciton flow, charge generation, and long-range charge separation. In contrast, there is limited structural control in current organic electronic devices such as OLEDs and solar cells. We report here the DNA-encoded assembly of π-conjugated perylene diimides (PDIs) with deterministic control over the number of electronically coupled molecules. The PDIs are integrated within DNA chains using phosphoramidite coupling chemistry, allowing selection of the DNA sequence to either side, and specification of intermolecular DNA hybridization. In this way, we have developed a "toolbox" for construction of any stacking sequence of these semiconducting molecules. We have discovered that we need to use a full hierarchy of interactions: DNA guides the semiconductors into specified close proximity, hydrophobic-hydrophilic differentiation drives aggregation of the semiconductor moieties, and local geometry and electrostatic interactions define intermolecular positioning. As a result, the PDIs pack to give substantial intermolecular π wave function overlap, leading to an evolution of singlet excited states from localized excitons in the PDI monomer to excimers with wave functions delocalized over all five PDIs in the pentamer. This is accompanied by a change in the dominant triplet forming mechanism from localized spin-orbit charge transfer mediated intersystem crossing for the monomer toward a delocalized excimer process for the pentamer. Our modular DNA-based assembly reveals real opportunities for the rapid development of bespoke semiconductor architectures with molecule-by-molecule precision.ERC Horizon 2020 (grant agreement No 670405 and No 803326) EPSRC Tier-2 capital grant EP/P020259/1. Winton Advanced Research Programme for the Physics of Sustainability. Simons Foundation (Grant 601946). Swedish research council, Vetenskapsrådet 2018-0023

Why High Leverage is Optimal for Banks

Abstract Liquidity production is a central role of banks. High leverage is optimal for banks in a capital structure model in which there is a market premium for (socially valuable) liquid financial claims and no deviations fro

Somatic mosaicism and common genetic variation contribute to the risk of very-early-onset inflammatory bowel disease

Abstract: Very-early-onset inflammatory bowel disease (VEO-IBD) is a heterogeneous phenotype associated with a spectrum of rare Mendelian disorders. Here, we perform whole-exome-sequencing and genome-wide genotyping in 145 patients (median age-at-diagnosis of 3.5 years), in whom no Mendelian disorders were clinically suspected. In five patients we detect a primary immunodeficiency or enteropathy, with clinical consequences (XIAP, CYBA, SH2D1A, PCSK1). We also present a case study of a VEO-IBD patient with a mosaic de novo, pathogenic allele in CYBB. The mutation is present in ~70% of phagocytes and sufficient to result in defective bacterial handling but not life-threatening infections. Finally, we show that VEO-IBD patients have, on average, higher IBD polygenic risk scores than population controls (99 patients and 18,780 controls; P < 4 × 10−10), and replicate this finding in an independent cohort of VEO-IBD cases and controls (117 patients and 2,603 controls; P < 5 × 10−10). This discovery indicates that a polygenic component operates in VEO-IBD pathogenesis

Handbook of the Economics of Finance

Although financial innovation has been an important part of the financial landscape throughout modern economic history, it has received relatively little attention in academia. This essay surveys the existing literature on financial innovation from the disciplines of financial economics, history, law, and industrial organization. I begin by defining financial innovation and discussing problems with creating taxonomies of financial innovations. I then discuss the explanations given for the extensive amount of financial innovation we observe both today and in history, which include: (a) completing inherently incomplete markets; (b) addressing persistent agency concerns and information asymmetries; (c) minimizing transaction, search or marketing costs; (d) responding to tax and regulatory forces; (e) responding to changes in economic conditions, in particular new or newly perceived risks; and (f) capitalizing on technological developments. I review work that studies the identity of innovators, the process of diffusion of innovation, and private benefits of innovation. I illustrate these general trends with a description of a sequence of innovations that show that repeated experimentation and failure characterize the evolutionary process. As difficult as it may be to measure the private benefits to innovators, it has proven even more problematic to conclusively model or measure the social welfare benefits of financial innovation, although one can point to specific innovations that appear to enhance welfare.

Left ventricular mass regression following implantation of MIRA bileaflet valves in patients with severe aortic stenosis

The aim of this study was to evaluate the factors that determine the course of left ventricular mass regression in a homogeneous group of patients following aortic valve replacement by use of the mechanical Edwards MIRA bileaflet prosthesis. Furthermore, we examined if the 19-mm valve leads to an equally good outcome when compared with larger 21- and 23-mm valves. We included 79 patients (49 men) with a mean age of 65+/-9 years operated on for isolated aortic valve replacement with the MIRA valve prosthesis. The analyses included preoperative and postoperative echocardiograms during a follow-up of at least 18 months (995+/-439 days) after valve surgery. Indication for valve replacement was aortic stenosis in 59 and combined disease (aortic stenosis and regurgitation) in 20 patients. Concomitant coronary artery bypass grafting was performed in 28 patients. Left ventricular mass index declined from 155.6+/-47 g/m(2) to 128.8+/-35 g/m(2) (P>0.001) at final visit and normalized in 49% of the patients. Female sex and a preoperatively highly elevated left ventricular mass index were identified as risk factors for residual hypertrophy. However, age and valve size did not have a predictive value for completeness of left ventricular mass regression. This study supports the evidence that an extensive preoperative left ventricular hypertrophy results in an incomplete postoperative mass regression in patients with aortic bileaflet valves. It shows that the slightly elevated pressure gradient in MIRA 19-mm valves does not affect left ventricular mass regression