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1579 Publications visible to you, out of a total of 1579
Impact of central mixing scheme and nuclear reaction network on the extent of convective cores

Abstract (Expand)

Convective cores are the hydrogen reservoirs of main sequence stars that are more massive than around 1.2 solar masses. The characteristics of the cores have a strong impact on the evolution and structure … of the star. However, such results rely on stellar evolution codes, in which simplistic assumptions are often made on the physics in the core. Indeed, mixing is commonly considered to be instantaneous and the most basic nuclear networks assume beryllium at its equilibrium abundance. Those assumptions lead to significant differences in the central composition of the elements for which the timescale to reach nuclear equilibrium is lower than the convective timescale. In this work, we show that those discrepancies impact the nuclear energy production and, therefore, the size of convective cores in models computed with overshoot. We find that cores computed with instantaneous mixing are up to 30% bigger than those computed with diffusive mixing. Similar differences are found when using basic nuclear networks. Additionally, we observed an extension of the duration of the main sequence due to those core size differences. We then investigated the impact of those structural differences on the seismic modeling of solar-like oscillators. Modeling two stars observed by Kepler, we find that the overshoot parameter of the best models computed with a basic nuclear network is significantly lower, compared to models computed with a full nuclear network. This work is a necessary step in improving the modeling of convective cores, which is key to determining accurate ages in the framework of future space missions such as Plato.

Authors: Anthony Noll, Sébastien Deheuvels

Date Published: 1st Aug 2023

Publication Type: Journal

Exoplanet interior retrievals: core masses and metallicities from atmospheric abundances

Abstract (Expand)

ABSTRACT The mass and distribution of metals in the interiors of exoplanets are essential for constraining their formation and evolution processes. Never the less, with only masses and radii measured, … the determination of exoplanet interior structures is degenerate, and so far simplified assumptions have mostly been used to derive planetary metallicities. In this work, we present a method based on a state-of-the-art interior code, recently used for Jupiter, and a Bayesian framework, to explore the possibility of retrieving the interior structure of exoplanets. We use masses, radii, equilibrium temperatures, and measured atmospheric metallicities to retrieve planetary bulk metallicities and core masses. Following results on the giant planets in the Solar system and recent development in planet formation, we implement two interior structure models: one with a homogeneous envelope and one with an inhomogeneous one. Our method is first evaluated using a test planet and then applied to a sample of 37 giant exoplanets with observed atmospheric metallicities from the pre-JWST era. Although neither internal structure model is preferred with the current data, it is possible to obtain information on the interior properties of the planets, such as the core mass, through atmospheric measurements in both cases. We present updated metal mass fractions, in agreement with recent results on giant planets in the Solar system.

Authors: S Bloot, Y Miguel, M Bazot, S Howard

Date Published: 1st Aug 2023

Publication Type: Journal

Ganna (Anya) Gryn'ova

Abstract

Not specified

Editor:

Date Published: 1st Aug 2023

Publication Type: Journal

First Draft of the VHT Roadmap

Abstract (Expand)

The VHT Roadmap is due – in its final version – by the end of the EDITH Coordination and Support Action (i.e., September 2024). The present document is the first draft of the Roadmap, This preliminary …y version of the Roadmap was planned in EDITH’s Grant Agreement as an initial contribution to the internal decision-making process of the European Commission. It has the declared purpose of allowing the Commission to start specifying already at an early stage by what steps the goal of pursuing the development of a VHT-based healthcare will be likely to trigger an effective engagement of Europe’s researchers, clinicians, industries, and regulators. This interim version is therefore meant to highlight what is currently the envisioned structure of what will be in a year time the final roadmap and its main contents, leaving open the possibility that these contents can still be subject to both substantial and formal changes, in response to suggestions coming from both the European Commission and from different sectors of the broadening community of practice that the EDITH CSA is addressing. In consideration of these double-edge purposes, this preliminary draft aims to capture the main concepts and the overall approach of the VHT Roadmap, while also identifying relevant challenges (from the perspective of research, infrastructure, and other specific aspects) that need to be addressed in the remaining year of the EDITH CSA (and beyond) and which will require further analysis, with the support of the whole VHT Community. For the technology, standards, regulatory, and legal aspects, the draft provides an overview of the state of the art and an analysis of VHT-specific needs, without determining as yet any conclusive choice. Given the evolving nature of this document, the submitted text will again be made publicly available for further comments and feedback, in view of possibly including valuable inputs in a next version. For general discussions, we encourage everyone to use the slack channel on the In silico World Community of Practice (ISW_CoP: https://insilico.world/community/join-the-community-of-practice-channels/). Critical remarks are welcome, as well as additional contributions, but also comments highlighting what sections are particularly appreciated will definitely help. if you would like to stay updated on EDITH's progress, you can enter your details via the contact form on the website: https://www.edith-csa.eu/contact/

Author: Gerhard Mayer, Martin Golebiewski

Date Published: 31st Jul 2023

Publication Type: Misc

Type Ia Supernova Explosions in Binary Systems: A Review

Abstract

Not specified

Authors: Zheng-Wei Liu, Friedrich K. Röpke, Zhanwen Han

Date Published: 26th Jul 2023

Publication Type: Journal

Allosteric activation of vinculin by talin

Abstract (Expand)

The talin-vinculin axis is a key mechanosensing component of cellular focal adhesions. How talin and vinculin respond to forces and regulate one another remains unclear. By combining single molecule … magnetic tweezer experiments, Molecular Dynamics simulations, actin bundling assays, and adhesion assembly experiments in live cells, we here discover a two-ways allosteric network within vinculin as a regulator of the talin-vinculin interaction. We directly observe a maturation process of vinculin upon talin binding which reinforces the binding to talin at a rate of 0.03 s−1. This allosteric transition can compete with force-induced dissociation of vinculin from talin only at 7-10 pN. Mimicking the allosteric activation by mutation yields a vinculin molecule that bundles actin and localizes to focal adhesions in a force-independent manner. Hence, the allosteric switch confines talin-vinculin interactions and focal adhesion build-up to intermediate force levels. The ‘allosteric vinculin mutant’ is a valuable molecular tool to further dissect the mechanical and biochemical signalling circuits at focal adhesions and elsewhere.

Authors: Florian Franz, Rafael Tapia-Rojo, Sabina Winograd-Katz, Rajaa Boujemaa-Paterski, Wenhong Li, Tamar Unger, Shira Albeck, Camilo Aponte-Santamaría, Sergi Garcia-Manyes, Ohad Medalia, Benjamin Geiger, Frauke Gräter

Date Published: 18th Jul 2023

Publication Type: Journal

HITS at DISRPT 2023: Discourse segmentation, connective detection, and relation classification

Abstract

Not specified

Authors: Wei Liu, Yi Fan, Michael Strube

Date Published: 14th Jul 2023

Publication Type: InProceedings

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