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

Abstract

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Authors: Fabian R. N. Schneider, Philipp Podsiadlowski, Eva Laplace

Date Published: 15th Jun 2023

Publication Type: Journal

Abstract (Expand)

This document defines challenges and requirements for predictive computational models constructed for research purposes in personalized medicine. It specifies recommendations and requirements for the setup, formatting, validation, simulation, storing and sharing of such models, as well as their application in clinical trials and other research areas. It summarizes specific challenges regarding data input, as well as verifying and validating of such models that can be considered as best practices for modelling in research and development in the field of personalized medicine. This document also specifies recommendations and requirements for data used to construct or needed for validating models, including rules and requirements for formatting, description, annotation, interoperability, integration, accessing, as well as recording and documenting the provenance of such data. This document does not provide specific rules or requirements for the use of computational models in the clinical routine, or for diagnostic or therapeutic purposes.

Authors: Marc Kirschner, Martin Golebiewski, Heike Moser, EU-STANDS4PM consortium, ISO/TC 276/WG 5

Date Published: 8th Jun 2023

Publication Type: Manual

Abstract (Expand)

Chemical (molecular, quantum) machine learning relies on representing molecules in unique and informative ways. Here, we present the matrix of orthogonalized atomic orbital coefficients (MAOC) as a quantum-inspired molecular and atomic representation containing both structural (composition and geometry) and electronic (charge and spin multiplicity) information. MAOC is based on a cost-effective localization scheme that represents localized orbitals via a predefined set of atomic orbitals. The latter can be constructed from such small atom-centered basis sets as pcseg-0 and STO-3G in conjunction with guess (non-optimized) electronic configuration of the molecule. Importantly, MAOC is suitable for representing monatomic, molecular, and periodic systems and can distinguish compounds with identical compositions and geometries but distinct charges and spin multiplicities. Using principal component analysis, we constructed a more compact but equally powerful version of MAOC—PCX-MAOC. To test the performance of full and reduced MAOC and several other representations (CM, SOAP, SLATM, and SPAHM), we used a kernel ridge regression machine learning model to predict frontier molecular orbital energy levels and ground state single-point energies for chemically diverse neutral and charged, closed- and open-shell molecules from an extended QM7b dataset, as well as two new datasets, N-HPC-1 (N-heteropolycycles) and REDOX (nitroxyl and phenoxyl radicals, carbonyl, and cyano compounds). MAOC affords accuracy that is either similar or superior to other representations for a range of chemical properties and systems.

Authors: Stiv Llenga, Ganna Gryn’ova

Date Published: 7th Jun 2023

Publication Type: Journal

Abstract (Expand)

The chloroquine resistance transporter (PfCRT) confers resistance to a wide range of quinoline and quinoline-like antimalarial drugs in Plasmodium falciparum , with local drug histories driving itsrum , with local drug histories driving its evolution and, hence, the drug transport specificities. For example, the change in prescription practice from chloroquine (CQ) to piperaquine (PPQ) in Southeast Asia has resulted in PfCRT variants that carry an additional mutation, leading to PPQ resistance and, concomitantly, to CQ re-sensitization. How this additional amino acid substitution guides such opposing changes in drug susceptibility is largely unclear. Here, we show by detailed kinetic analyses that both the CQ- and the PPQ-resistance conferring PfCRT variants can bind and transport both drugs. Surprisingly, the kinetic profiles revealed subtle yet significant differences, defining a threshold for in vivo CQ and PPQ resistance. Competition kinetics, together with docking and molecular dynamics simulations, show that the PfCRT variant from the Southeast Asian P . falciparum strain Dd2 can accept simultaneously both CQ and PPQ at distinct but allosterically interacting sites. Furthermore, combining existing mutations associated with PPQ resistance created a PfCRT isoform with unprecedented non-Michaelis-Menten kinetics and superior transport efficiency for both CQ and PPQ. Our study provides additional insights into the organization of the substrate binding cavity of PfCRT and, in addition, reveals perspectives for PfCRT variants with equal transport efficiencies for both PPQ and CQ.

Authors: Guillermo M. Gomez, Giulia D’Arrigo, Cecilia P. Sanchez, Fiona Berger, Rebecca C. Wade, Michael Lanzer

Date Published: 7th Jun 2023

Publication Type: Journal

Abstract

Not specified

Authors: Natalia Lahén, Thorsten Naab, Guinevere Kauffmann, Dorottya Szécsi, Jessica May Hislop, Antti Rantala, Alexandra Kozyreva, Stefanie Walch, Chia-Yu Hu

Date Published: 1st Jun 2023

Publication Type: Journal

Abstract (Expand)

Context. Observations of young multiple star systems find a bimodal distribution in companion frequency and separation. The origin of these peaks has often been attributed to binary formation via corebeen attributed to binary formation via core and disc fragmentation. However, theory and simulations suggest that young stellar systems that form via core fragmentation undergo significant orbital evolution. Aims. We investigate the influence of the environment on the formation and orbital evolution of multiple star systems, and how core fragmentation contributes to the formation of close (20 − 100 AU) binaries. We use multiple simulations of star formation in giant molecular clouds and compare them to the multiplicity statistics of the Perseus star-forming region. Methods. Simulations were run with the adaptive mesh refinement code RAMSES with sufficient resolution to resolve core fragmentation beyond 400 AU and dynamical evolution down to 16.6 AU, but without the possibility of resolving disc fragmentation. The evolution of the resulting stellar systems was followed over millions of years. Results. We find that star formation in lower gas density environments is more clustered; however, despite this, the fractions of systems that form via dynamical capture and core fragmentation are broadly consistent at ∼40% and ∼60%, respectively. In all gas density environments, we find that the typical scale at which systems form via core fragmentation is 10 3 − 3.5  AU. After formation, we find that systems that form via core fragmentation have slightly lower inspiral rates (∼10 −1.68  AU yr −1 measured over the first 10 000 yr) compared to dynamical capture (∼10 −1.32  AU yr −1 ). We then compared the simulation with the conditions most similar to the Perseus star-forming region to determine whether the observed bimodal distribution can be replicated. We find that it can be replicated, but it is sensitive to the evolutionary state of the simulation. Conclusions. Our results indicate that a significant number of low-mass close binaries with separations from 20 − 100 AU can be produced via core fragmentation or dynamical capture due to efficient inspiral, without the need for a further contribution from disc fragmentation.

Authors: Rajika L. Kuruwita, Troels Haugbølle

Date Published: 1st Jun 2023

Publication Type: Journal

Abstract

Not specified

Author: Johannes Resin

Date Published: 31st May 2023

Publication Type: Journal

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