Dataset Information

Explicit IMF B _y -Dependence of Energetic Protons and the Ring Current.

ABSTRACT: The most important parameter driving the solar wind-magnetosphere interaction is the southward (B _z ) component of the interplanetary magnetic field (IMF). While the dawn-dusk (B _y ) component of the IMF is also known to play an important role, its effects are usually assumed to be independent of its sign. Here we demonstrate for the first time a seasonally varying, explicit IMF B _y -dependence of the ring current and Dst index. Using satellite observations and a global magnetohydrodynamic model coupled with a ring current model, we show that for a fixed level of solar wind driving the flux of energetic magnetospheric protons and the growth-rate of the ring current are greater for B _y < 0 (B _y > 0) than for B _y > 0 (B _y < 0) in Northern Hemisphere summer (winter). While the physical mechanism of this explicit B _y -effect is not yet fully understood, our results suggest that IMF B _y modulates magnetospheric convection and plasma transport in the inner magnetosphere.

SUBMITTER: Holappa L

PROVIDER: S-EPMC9286478 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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Explicit IMF B y -Dependence of Energetic Protons and the Ring Current.

Holappa L L Buzulukova N Y NY

Geophysical research letters 20220426 8

The most important parameter driving the solar wind-magnetosphere interaction is the southward (B z ) component of the interplanetary magnetic field (IMF). While the dawn-dusk (B y ) component of the IMF is also known to play an important role, its effects are usually assumed to be independent of its sign. Here we demonstrate for the first time a seasonally varying, explicit IMF B y -dependence of the ring current and ...[more]

PMID: 35866060

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Project description:Protein structure modeling and prediction have important applications throughout the biological sciences, from the design of pharmaceuticals to the elucidation of enzyme mechanisms. At the core of most protein modeling is an energy function, the minimum of which represents the free energy "cost" for forming a correct protein structure. The most commonly used energy functions are knowledge-based statistical potential functions; that is, they are empirically derived from statistical analysis of a set of high-resolution protein structures. When that kind of potential function is constructed, the anisotropic orientation dependence between the interacting groups is a critical component for accurately representing key molecular interactions, such as those involved in protein side-chain packing. In the literature, however, many potential functions are limited in their ability to describe orientation dependence. In all-atom potentials, they typically ignore heterogeneous chemical-bond connectivity. In coarse-grained potentials, such as (semi)-residue-based potentials, the simplified representation of residues often reduces the sensitivity of the potential to side-chain orientation. Recently, in an effort to maximally capture the orientation dependence in side-chain interactions, a new type of all-atom statistical potential was developed: OPUS-PSP (potential derived from side-chain packing). The key feature of this potential is its explicit description of orientation dependence in molecular interactions, which is achieved with a basis set of 19 rigid-body blocks extracted from the chemical structures of 20 amino acid residues. This basis set is specifically designed to maximally capture the essential elements of orientation dependence in molecular packing interactions. The potential is constructed from the orientation-specific packing statistics of pairs of those blocks in a nonredundant structural database. On decoy set tests, OPUS-PSP significantly outperforms most of the existing knowledge-based potentials in terms of both its ability to recognize native structures and its consistency in achieving high Z scores across decoy sets. The application of OPUS-PSP to conformational modeling of side chains has led to another method, called OPUS-Rota. In terms of combined speed and accuracy, OPUS-Rota outperforms all of the other methods in modeling side-chain conformation. In this Account, we briefly outline the basic scheme of the OPUS-PSP potential and its application to side-chain modeling via OPUS-Rota. Future perspectives on the modeling of orientation dependence are also discussed. The computer programs for OPUS-PSP and OPUS-Rota can be downloaded at http://sigler.bioch.bcm.tmc.edu/MaLab . They are free for academic users.

Dataset Information

Explicit IMF B _y -Dependence of Energetic Protons and the Ring Current.

Publications

Explicit IMF <i>B</i> <sub><i>y</i></sub> -Dependence of Energetic Protons and the Ring Current.

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