| 1. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 2. |
- Hudson, Lawrence N, et al.
(författare)
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
- 2017
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 7:1, s. 145-188
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Tidskriftsartikel (refereegranskat)abstract
- The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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| 3. |
- Arias-Aragón, F., et al.
(författare)
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Cosmic imprints of XENON1T axions
- 2020
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing Ltd. - 1475-7516. ; 2020:11
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Tidskriftsartikel (refereegranskat)abstract
- The recent electron recoil excess observed by XENON1T has a possible interpretation in terms of solar axions coupled to electrons. If such axions are still relativistic at recombination they would also leave a cosmic imprint in the form of an additional radiation component, parameterized by an effective neutrino number Δ Neff. We explore minimal scenarios with a detectable signal in future CMB surveys: axions coupled democratically to all fermions, axion-electron coupling generated radiatively, the DFSZ framework for the QCD axion. The predicted Δ Neff is larger than 0.03-0.04 for all cases, close to the 2σ forecasted sensitivity of CMB-S4 experiments. This opens the possibility of testing with cosmological observations the solar axion interpretation of the XENON1T excess.
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| 4. |
- Arias-Aragon, Fernando, et al.
(författare)
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Production of thermal axions across the electroweak phase transition
- 2021
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :3
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Tidskriftsartikel (refereegranskat)abstract
- Light axions can potentially leave a cosmic background, just like neutrinos. We complete the study of thermal axion production across the electroweak scale by providing a smooth and continuous treatment through the two phases. Focusing on both flavor conserving and violating couplings to third generation quarks, we compute the amount of axions produced via scatterings and decays of thermal bath particles. We perform a model independent analysis in terms of axion effective couplings, and we also make predictions for specific microscopic QCD axion scenarios. This observable effect, parameterized as it is conventional by an effective number of additional neutrinos, is above the 1 sigma sensitivity of future CMB-S4 surveys. Moreover, if one assumes no large hierarchies among dimensionless axion couplings to standard model particles, future axion helioscopes will provide a complementary probe for the parameter region we study.
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| 5. |
- Bjorkmo, Theodor, et al.
(författare)
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Mild non-Gaussianities under perturbative control from rapid-turn inflation models
- 2019
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP PUBLISHING LTD. - 1475-7516. ; :12
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Tidskriftsartikel (refereegranskat)abstract
- Inflation can be supported in very steep potentials if it is generated by rapidly turning fields, which can be natural in negatively curved field spaces. The curvature perturbation, zeta, of these models undergoes an exponential, transient amplification around the time of horizon crossing, but can still be compatible with observations at the level of the power spectrum. However, a recent analysis (based on a proposed single-field effective theory with an imaginary speed of sound) found that the trispectrum and other higher-order, non-Gaussian correlators also undergo similar exponential enhancements. This arguably leads to 'hyper-large' non-Gaussianities in stark conflict with observations, and even to the loss of perturbative control of the calculations. In this paper, we provide the first analytic solution of the growth of the perturbations in two-field rapid-turn models, and find it in good agreement with previous numerical and single-field EFT estimates. We also show that the nested structure of commutators of the in-in formalism has subtle and crucial consequences: accounting for these commutators, we show analytically that the naively leading-order piece (which indeed is exponentially large) cancels exactly in all relevant correlators. The remaining non-Gaussianities of these models are modest, and there is no problem with perturbative control from the exponential enhancement of zeta. Thus, rapid-turn inflation with negatively curved field spaces remains a viable and interesting class of candidate theories of the early universe.
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| 6. |
- Di Valentino, E., et al.
(författare)
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Late time transitions in the quintessence field and the H0 tension
- 2019
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Ingår i: Physics of the Dark Universe. - : Elsevier. - 2212-6864. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- We consider a quintessence field which transitions from a matter-like to a cosmological constant behaviour between recombination and the present time. We aim at easing the tension in the measurement of the present Hubble rate, and we assess the ΛCDM model properly enlarged to include our quintessence field against cosmological observations. The model does not address the scope we proposed. This result allows us to exclude a class of quintessential models as a solution to the tension in the Hubble constant measurements.
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| 7. |
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| 8. |
- Ferreira, Ricardo Z., et al.
(författare)
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Dine-Fischler-Srednicki-Zhitnitsky axion in the CMB
- 2021
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Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 103:6
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Tidskriftsartikel (refereegranskat)abstract
- We perform for the first time a dedicated analysis of cosmological constraints on Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) QCD axion models. Such constructions are especially interesting in light of the recent XENON rrexcess and of hints from stellar cooling. In DFSZ models, for m(a) greater than or similar to 0.1 eV, scatterings of pions and muons can produce a sizable cosmic background of thermal axions, that behave similarly to massive neutrinos. However, the pion coupling depends on the alignment between the vacuum expectation value (vevs) of two Higgs doublets, and can be significantly suppressed or enhanced with respect to the Kim-Shifman-Vainshtein-Zakharov scenario (KSVZ). Using the latest Planck and BAO data, we find m(a) <= 0.2 eV at 95% C.L., when the axion coupling to pions c(a pi) is maximal. Constraints on m(a), instead, can be significantly relaxed when c(a pi) is small. In particular, we point out that in the so-called DFSZ-II model, where the axion coupling to leptons does not vanish simultaneously with c(a pi), production via muons gives m(a) < 0.6 eV at 95% C.L., whereas in the DFSZ-I model bounds on m a can be fully lifted. We then combine cosmological data with recent hints of a DFSZ axion coupled to electrons from the XENON1T experiment, finding in this case that the axion mass is constrained to be in the window 0.07 eV less than or similar to m(a) less than or similar to 1.8(0.3) eV for the DFSZ-I (DFSZ-II) model. A similar analysis with stellar cooling hints gives 3 meV less than or similar to m(a) less than or similar to 0.2 eV for DFSZ-II, while no constraint arises in the DFSZ-I case. Forthcoming cosmic microwave background stage 4 experiments will be able to further test such scenarios; for instance the XENON1T window should be fully probed at 2 sigma for a DFSZ-I axion.
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| 9. |
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| 10. |
- Ferreira, Ricardo Z., et al.
(författare)
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Do Direct Detection Experiments Constrain Axionlike Particles Coupled to Electrons?
- 2022
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 128:22
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Tidskriftsartikel (refereegranskat)abstract
- Several laboratory experiments have published limits on axionlike particles (ALPs) with feeble couplings to electrons and masses in the kilo-electron-volt to mega-electron-volt range, under the assumption that such ALPs comprise the dark matter. We note that ALPs decay radiatively into photons, and show that for a large subset of the parameter space ostensibly probed by these experiments, the lifetime of the ALPs is shorter than the age of the Universe. Such ALPs cannot consistently make up the dark matter, which significantly affects the interpretation of published limits from GERDA, Edelweiss-III, SuperCDMS, and Majorana. Moreover, constraints from x-ray and γ-ray astronomy exclude a wide range of the ALP-electron coupling, and supersede all current laboratory limits on dark matter ALPs in the 6 keV to 1 MeV mass range. These conclusions are rather model independent, and can only be avoided at the expense of significant fine-tuning in theories where the ALP has additional couplings to other particles.
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