| 61. |
|
|
| 62. |
|
|
| 63. |
|
|
| 64. |
|
|
| 65. |
- Baker, C. J., et al.
(författare)
-
Laser cooling of antihydrogen atoms
- 2021
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 592:7852, s. 35-42
-
Tidskriftsartikel (refereegranskat)abstract
- The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision(1). Slowing the translational motion of atoms and ions by application of such a force(2,3), known as laser cooling, was first demonstrated 40 years ago(4,5). It revolutionized atomic physics over the following decades(6-8), and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen(9), the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-alpha laser radiation(10,11), we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic(11-13) and gravitational(14) studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.
|
|
| 66. |
- Carter, Aarynn L., et al.
(författare)
-
A benchmark JWST near-infrared spectrum for the exoplanet WASP-39 b
- 2024
-
Ingår i: Nature Astronomy. - 2397-3366. ; 8:8, s. 1008-1019
-
Tidskriftsartikel (refereegranskat)abstract
- A combined analysis of datasets across four JWST instrument modes provides a benchmark transmission spectrum for the Saturn-mass WASP-39 b. The broad wavelength range and high resolution constrain orbital and stellar parameters to below 1%.
|
|
| 67. |
- Hibbett, D. S., et al.
(författare)
-
A higher-level phylogenetic classification of the Fungi
- 2007
-
Ingår i: Mycological Research. - : Elsevier BV. - 0953-7562 .- 1469-8102. ; 111, s. 509-547
-
Tidskriftsartikel (refereegranskat)abstract
- A comprehensive phylogenetic classification of the kingdom Fungi is proposed, with reference to recent molecular phylogenetic analyses, and with input from diverse members of the fungal taxonomic community. The classification includes 195 taxa, down to the level of order, of which 16 are described or validated here: Dikarya subkingdom nov.; Chytridiomycota, Neocallimastigomycota phyla nov.; Monoblepharidomycetes, Neocallimastigomycetes class. nov.; Eurotiomycetidae, Lecarioromycetidae, Mycocaliciomycetidae subclass. nov.; Acarosporales, Corticiales, Baeomycetales, Candelariales, Gloeophyllales, Melanosporales, Trechisporales, Umbilicariales ords. nov. The clade containing Ascomycota and Basidiomycota is classified as subkingdom Dikarya, reflecting the putative synapomorphy of dikaryotic hyphae. The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotiria. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella. (c) 2007 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
|
|
| 68. |
- Kattge, Jens, et al.
(författare)
-
TRY plant trait database - enhanced coverage and open access
- 2020
-
Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
-
Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
|
|
| 69. |
- van Rheenen, Wouter, et al.
(författare)
-
Genome-wide association analyses identify new risk variants and the genetic architecture of amyotrophic lateral sclerosis
- 2016
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48:9, s. 1043-1048
-
Tidskriftsartikel (refereegranskat)abstract
- To elucidate the genetic architecture of amyotrophic lateral sclerosis (ALS) and find associated loci, we assembled a custom imputation reference panel from whole-genome-sequenced patients with ALS and matched controls (n = 1,861). Through imputation and mixed-model association analysis in 12,577 cases and 23,475 controls, combined with 2,579 cases and 2,767 controls in an independent replication cohort, we fine-mapped a new risk locus on chromosome 21 and identified C21orf2 as a gene associated with ALS risk. In addition, we identified MOBP and SCFD1 as new associated risk loci. We established evidence of ALS being a complex genetic trait with a polygenic architecture. Furthermore, we estimated the SNP-based heritability at 8.5%, with a distinct and important role for low-frequency variants (frequency 1-10%). This study motivates the interrogation of larger samples with full genome coverage to identify rare causal variants that underpin ALS risk.
|
|
| 70. |
- Zuntini, Alexandre R., et al.
(författare)
-
Phylogenomics and the rise of the angiosperms
- 2024
-
Ingår i: NATURE. - 0028-0836 .- 1476-4687. ; 629, s. 843-850
-
Tidskriftsartikel (refereegranskat)abstract
- Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods(1,2). A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome(3,4). Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins(5-7). However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes(8). This 15-fold increase in genus-level sampling relative to comparable nuclear studies(9) provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade.
|
|
