28 research outputs found
Development of a High Intensity Neutron Source at the European Spallation Source: The HighNESS project
The European Spallation Source (ESS), presently under construction in Lund,
Sweden, is a multidisciplinary international laboratory that will operate the
world's most powerful pulsed neutron source. Supported by a 3M Euro Research
and Innovation Action within the EU Horizon 2020 program, a design study
(HighNESS) is now underway to develop a second neutron source below the
spallation target. Compared to the first source, located above the spallation
target and designed for high cold and thermal brightness, the new source will
provide higher intensity, and a shift to longer wavelengths in the spectral
regions of cold (2 /- 20 {\AA}), very cold (VCN, 10 /- 120 {\AA}), and ultra
cold (UCN, > 500 {\AA}) neutrons. The core of the second source will consist of
a large liquid deuterium moderator to deliver a high flux of cold neutrons and
to serve secondary VCN and UCN sources, for which different options are under
study. The features of these new sources will boost several areas of condensed
matter research and will provide unique opportunities in fundamental physics.
Part of the HighNESS project is also dedicated to the development of future
instruments that will make use of the new source and will complement the
initial suite of instruments in construction at ESS. The HighNESS project
started in October 2020. In this paper, the ongoing developments and the
results obtained in the first year are described.Comment: 10 pages, 10 figures, 14th International Topical Meeting on Nuclear
Applications of Accelerators, November 30 to December 4, 2021, Washington, D
Analysis of RNA sequence structure maps by exhaustive enumeration .1. Neutral networks
Grüner W, Giegerich R, Strothmann D, et al. Analysis of RNA sequence structure maps by exhaustive enumeration .1. Neutral networks. Monatshefte für Chemie. 1996;127(4):355-374.Global relations between RNA sequences and secondary structures are understood as mappings from sequence space into shape space. These mappings are investigated by exhaustive folding of all GC and AU sequences with chain lengths up to 30. The computed structural data are evaluated through exhaustive enumeration and used as an exact reference for testing analytical results derived from mathematical models and sampling based on statistical methods. Several new concepts of RNA sequence to secondary structure mappings are investigated, among them that of neutral networks (being sets of sequences folding into the same structure). Exhaustive enumeration allows to test several previously suggested relations: the number of(minimum free energy) secondary structures as a function of the chain length as well as the frequency distribution of structures at constant chain length (commonly resulting in generalized forms of Zipf's law)