Publications

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1579 Publications visible to you, out of a total of 1579

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Authors: Ariane Nunes-Alves, Fabian Ormersbach, Rebecca C. Wade

Date Published: 26th Jul 2021

Publication Type: Journal

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Authors: Jonas Beyrer, Beatrice Pozzetti

Date Published: 15th Jul 2021

Publication Type: Journal

Abstract (Expand)

Asteroseismic measurements enable inferences of the underlying stellar structure, such as the density and the speed of sound at various points within the interior of the star. This provides an opportunity to test stellar evolution theory by assessing whether the predicted structure of a star agrees with the measured structure. Thus far, this kind of inverse analysis has only been applied to the Sun and three solar-like main-sequence stars. Here we extend the technique to stars on the subgiant branch, and apply it to one of the best-characterized subgiants of the Kepler mission, HR 7322. The observation of mixed oscillation modes in this star facilitates inferences of the conditions of its inert helium core, nuclear-burning hydrogen shell, and the deeper parts of its radiative envelope. We find that despite significant differences in the mode frequencies, the structure near to the center of this star does not differ significantly from the predicted structure.

Authors: Earl P. Bellinger, Sarbani Basu, Saskia Hekker, Jørgen Christensen-Dalsgaard, Warrick H. Ball

Date Published: 13th Jul 2021

Publication Type: Journal

Abstract

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Authors: Frédéric Mahé, Lucas Czech, Alexandros Stamatakis, Christopher Quince, Colomban de Vargas, Micah Dunthorn, Torbjørn Rognes

Date Published: 9th Jul 2021

Publication Type: Journal

Abstract (Expand)

The present work describes the reaction of triplet dioxygen with the porphyrinogenic calix[4]pyrrolato aluminates to alkylperoxido aluminates in high selectivity. Multiconfigurational quantum chemical computations disclose the mechanism for this spin-forbidden process. Despite a negligible spin–orbit coupling constant, the intersystem crossing (ISC) is facilitated by singlet and triplet state degeneracy and spin–vibronic coupling. The formed peroxides are stable toward external substrates but undergo an unprecedented oxidative pyrrole α-cleavage by ligand aromatization/dearomatization-initiated O−O σ-bond scission. A detailed comparison of the calix[4]pyrrolato aluminates with dioxygen-related enzymology provides insights into the ISC of metal- or cofactor-free enzymes. It substantiates the importance of structural constraint and element–ligand cooperativity for the functions of aerobic life.

Authors: Lukas Maximilian Sigmund, Christopher Ehlert, Markus Enders, Jürgen Graf, Ganna Gryn'ova, Lutz Greb

Date Published: 5th Jul 2021

Publication Type: Journal

Abstract (Expand)

Abstract Lynch syndrome (LS), the most common inherited colorectal cancer (CRC) syndrome, increases the cancer risk in affected individuals. LS is caused by pathogenic germline variants in one of the DNA mismatch repair (MMR) genes, complete inactivation of which causes numerous mutations in affected cells. As CRC is believed to originate in colonic crypts, understanding the intra-crypt dynamics caused by mutational processes is essential for a complete picture of LS CRC and may have significant implications for cancer prevention. We propose a computational model describing the evolution of colonic crypts during LS carcinogenesis. Extending existing modeling approaches for the non-Lynch scenario, we incorporated MMR deficiency and implemented recent experimental data demonstrating that somatic CTNNB1 mutations are common drivers of LS-associated CRCs, if affecting both alleles of the gene. Further, we simulated the effect of different mutations on the entire crypt, distinguishing non-transforming and transforming mutations. As an example, we analyzed the spread of mutations in the genes APC and CTNNB1, which are frequently mutated in LS tumors, as well as of MMR deficiency itself. We quantified each mutation's potential for monoclonal conversion and investigated the influence of the cell location and of stem cell dynamics on mutation spread. The in silico experiments underline the importance of stem cell dynamics for the overall crypt evolution. Further, simulating different mutational processes is essential in LS since mutations without survival advantages (the MMR deficiency-inducing second hit) play a key role. The effect of other mutations can be simulated with the proposed model. Our results provide first mathematical clues towards more effective surveillance protocols for LS carriers.

Authors: Saskia Haupt, Nils Gleim, Aysel Ahadova, Hendrik Bläker, Magnus von Knebel Doeberitz, Matthias Kloor, Vincent Heuveline

Date Published: 4th Jul 2021

Publication Type: Journal

Abstract

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Authors: Ben Bettisworth, Alexandros Stamatakis

Date Published: 25th Jun 2021

Publication Type: Journal

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