1,405 research outputs found
A graph theory-based multi-scale analysis of hierarchical cascade in molecular clouds : Application to the NGC 2264 region
The spatial properties of small star-clusters suggest that they may originate
from a fragmentation cascade of the cloud for which there might be traces up to
a few dozen of kAU. Our goal is to investigate the multi-scale spatial
structure of gas clumps, to probe the existence of a hierarchical cascade and
to evaluate its possible link with star production in terms of multiplicity.
From the Herschel emission maps of NGC 2264, clumps are extracted using getsf
software at each of their associated spatial resolution, respectively [8.4,
13.5, 18.2, 24.9, 36.3]". Using the spatial distribution of these clumps and
the class 0/I Young Stellar Object (YSO) from Spitzer data, we develop a
graph-theoretic analysis to represent the multi-scale structure of the cloud as
a connected network. From this network, we derive three classes of multi-scale
structure in NGC 2264 depending on the number of nodes produced at the deepest
level: hierarchical, linear and isolated. The structure class is strongly
correlated with the column density since the hierarchical ones
dominate the regions whose Ncm. Although
the latter are in minority, they contain half of the class 0/I YSOs proving
that they are highly efficient in producing stars. We define a novel
statistical metric, the fractality coefficient F that measure the fractal index
describing the scale-free process of the cascade. For NGC 2264, we estimate F =
1.450.12. However, a single fractal index fails to fully describe a
scale-free process since the hierarchical cascade starts at a 13 kAU
characteristic spatial scale. Our novel methodology allows us to correlate YSOs
with their multi-scale gaseous environment. This hierarchical cascade that
drives efficient star formation is suspected to be both hierarchical and rooted
by the larger-scale gas environment up to 13 kAU
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Enumerating molecules.
This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecular design, and combinatorial library design purposes. This review is to appear as a chapter in Reviews in Computational Chemistry volume 21 edited by Kenny B. Lipkowitz
Electron Thermal Runaway in Atmospheric Electrified Gases: a microscopic approach
Thesis elaborated from 2018 to 2023 at the Instituto de AstrofÃsica de AndalucÃa under the supervision of Alejandro Luque (Granada, Spain) and Nikolai Lehtinen (Bergen, Norway). This thesis presents a new database of atmospheric electron-molecule collision cross sections which was published separately under the DOI :
With this new database and a new super-electron management algorithm which significantly enhances high-energy electron statistics at previously unresolved ratios, the thesis explores general facets of the electron thermal runaway process relevant to atmospheric discharges under various conditions of the temperature and gas composition as can be encountered in the wake and formation of discharge channels
From in vitro evolution to protein structure
In the nanoscale, the machinery of life is mainly composed by macromolecules and macromolecular complexes that through their shapes create a network of interconnected mechanisms of biological processes. The relationship between shape and function of a biological molecule is the foundation of structural biology, that aims at studying the structure of a protein or a macromolecular complex to unveil the molecular mechanism through which it exerts its function. What about the reverse: is it possible by exploiting the function for which a protein was naturally selected to deduce the protein structure? To this aim we developed a method, called CAMELS (Coupling Analysis by Molecular Evolution Library Sequencing), able to obtain the structural features of a protein from an artificial selection based on that protein function. With CAMELS we tried to reconstruct the TEM-1 beta lactamase fold exclusively by generating and sequencing large libraries of mutational variants. Theoretically with this method it is possible to reconstruct the structure of a protein regardless of the species of origin or the phylogenetical time of emergence when a functional phenotypic selection of a protein is available. CAMELS allows us to obtain protein structures without needing to purify the protein beforehand
First International Conference on Laboratory Research for Planetary Atmospheres
Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices
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