480 research outputs found
Artificial Intelligence for Science in Quantum, Atomistic, and Continuum Systems
Advances in artificial intelligence (AI) are fueling a new paradigm of
discoveries in natural sciences. Today, AI has started to advance natural
sciences by improving, accelerating, and enabling our understanding of natural
phenomena at a wide range of spatial and temporal scales, giving rise to a new
area of research known as AI for science (AI4Science). Being an emerging
research paradigm, AI4Science is unique in that it is an enormous and highly
interdisciplinary area. Thus, a unified and technical treatment of this field
is needed yet challenging. This work aims to provide a technically thorough
account of a subarea of AI4Science; namely, AI for quantum, atomistic, and
continuum systems. These areas aim at understanding the physical world from the
subatomic (wavefunctions and electron density), atomic (molecules, proteins,
materials, and interactions), to macro (fluids, climate, and subsurface) scales
and form an important subarea of AI4Science. A unique advantage of focusing on
these areas is that they largely share a common set of challenges, thereby
allowing a unified and foundational treatment. A key common challenge is how to
capture physics first principles, especially symmetries, in natural systems by
deep learning methods. We provide an in-depth yet intuitive account of
techniques to achieve equivariance to symmetry transformations. We also discuss
other common technical challenges, including explainability,
out-of-distribution generalization, knowledge transfer with foundation and
large language models, and uncertainty quantification. To facilitate learning
and education, we provide categorized lists of resources that we found to be
useful. We strive to be thorough and unified and hope this initial effort may
trigger more community interests and efforts to further advance AI4Science
Robust automatic assignment of nuclear magnetic resonance spectra for small molecules
Abstract. In this document we describe a fully automatic assignment system for Nuclear Magnetic Resonance (NMR) for small molecules. This system has 3 main features: 1. it uses as input raw NMR data. Which means it should be able to extract from them the information that is useful while ignores the noise; 2. it assigns the signals to atoms in the structure, and associates to each assignment a confidence value, which is used to sort all possible solutions; 3. it does not depend on chemical shifts predictions. So it can use the connectivity information observed in 2D NMR spectra and integrals to perform an assignment(coupling constants are also a possibility, but were not explored in this work). However, the system can use chemical shifts if available.; 4. it can learn in an unsupervised fashion, the relation between configurations of atoms and chemical shifts while solving assignment problems, which allows the system to improve while working. Analogous to the way a human works. This system is completely open source, as well as the data used in this work.En este trabajo describimos un sistema completamente automático de asignación de espectros de Resonancia Magnética Nuclear(RMN) para moléculas pequeñas. Este sistema tiene la siguientes características: 1. usa como entrada datos de RMN crudos. Lo que significa que debe ser capaz de extraer de ellos, la información que es útil y dejar de lado el ruido; 2. asigna las señales a átomos en la estructura, y asocia a cada asignación un valor de confianza, que es usado para ordenar todas las posibles soluciones; 3. no depende de predicciones de desplazamientos químicos, de forma que puede usar solo la información de conectividad observada en los espectros de RMN 2D y las integrales( las constantes de acople también son una posibilidad, pero no fueron exploradas en este trabajo). Sin embargo el sistema puede usar los desplazamientos químicos si están disponibles; 4. puede aprender de forma no supervisada, la relación entre configuraciones de átomos y desplazamientos químicos mientras resuelve problemas de asignación, lo que le permite mejorar mientras trabaja, de forma análoga a como lo hace un humano. Este sistema es completamente de código abierto, al igual que los datos que se usaron en este trabajo.Doctorad
Quadratic Binary Programming Models in Computational Biology
In this paper we formulate four problems in computational molecular biology as 0-1 quadratic programs. These problems are all NP-hard and the current solution methods used in practice consist of heuristics or approximation algorithms tailored to each problem. Using test problems from scientific databases, we address the question, “Can a general-purpose solver obtain good answers in reasonable time?” In addition, we use the latest heuristics as incumbent solutions to address the question, “Can a general-purpose solver confirm optimality or find an improved solution in reasonable time?” Our computational experiments compare four different reformulation methods: three forms of linearization and one form of quadratic convexification
Exact, constraint-based structure prediction in simple protein models
Die Arbeit untersucht die exakte Vorhersage der Struktur von Proteinen in dreidimensionalen, abstrakten Proteinmodellen; insbesondere wird ein exakter Ansatz zur Strukturvorhersage in den HP-Modellen (Lau und Dill, ACS, 1989) des kubischen und kubisch-flächenzentrierten Gitters entwickelt und diskutiert. Im Gegensatz zu heuristischen Methoden liefert das vorgestellte exakte Verfahren beweisbar korrekte Strukturen. HP-Modelle (Hydrophob, Polar) repräsentieren die Rückgratkonformation eines Proteins durch Gitterpunkte und berücksichti\-gen ausschließlich die hydrophobe Wechselwirkung als treibende Kraft bei der Ausbildung der Proteinstruktur. Wesentlich für die erfolgreiche Umsetzung des vorgestellten Verfahrens ist die Verwendung von constraint-basierten Techniken. Im Zentrum steht die Berechnung und Anwendung hydrophober Kerne für die Strukturvorhersage
Briefing Book for the Zeuthen Workshop
On Jun 18th 2004, the CERN Council, upon the initiative of its President, Prof. Enzo Iarocci, established an ad hoc scientific advisory group (the Strategy Group), to produce a draft strategy for European particle physics, which is to be considered by a special meeting of the CERN Council, to be held in Lisbon on Jul 14th 2006. There are three volumes to the Briefing Book. This first volume contains an introductory essay on particle physics, a summary of the issues discussed at the Open Symposium, and discussions of the other themes that the Strategy should address. The introductory essay on particle physics and the other themes were commissioned by the Preparatory Group. The summary of the issues discussed in the Symposium was prepared by the chairs of the sessions, the session speakers and the scientific secretaries. We acknowledge that this has been a difficult task, again on a very tight timescale, and we would like to thank all of those who have contributed to this volume
Towards the european strategy for particle physics: The briefing book
This document was prepared as part of the briefing material for the Workshop
of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May
2006. It gives an overview of the physics issues and of the technological
challenges that will shape the future of the field, and incorporates material
presented and discussed during the Symposium on the European Strategy for
Particle Physics, held in Orsay from 30th January to 2nd February 2006,
reflecting the various opinions of the European community as recorded in
written submissions to the Strategy Group and in the discussions at the
Symposium
Emergence of fractal geometries in the evolution of a metabolic enzyme
Fractals are patterns that are self-similar across multiple length-scales. Macroscopic fractals are common in nature; however, so far, molecular assembly into fractals is restricted to synthetic systems. Here we report the discovery of a natural protein, citrate synthase from the cyanobacterium Synechococcus elongatus, which self-assembles into Sierpiński triangles. Using cryo-electron microscopy, we reveal how the fractal assembles from a hexameric building block. Although different stimuli modulate the formation of fractal complexes and these complexes can regulate the enzymatic activity of citrate synthase in vitro, the fractal may not serve a physiological function in vivo. We use ancestral sequence reconstruction to retrace how the citrate synthase fractal evolved from non-fractal precursors, and the results suggest it may have emerged as a harmless evolutionary accident. Our findings expand the space of possible protein complexes and demonstrate that intricate and regulatable assemblies can evolve in a single substitution
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