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Sökning: WFRF:(Margalef J)

  • Resultat 1-10 av 16
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1.
  • Kanai, M, et al. (författare)
  • 2023
  • swepub:Mat__t
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2.
  • Niemi, MEK, et al. (författare)
  • 2021
  • swepub:Mat__t
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3.
  • The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
  • 2022
  • Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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4.
  • Pàmies, O., et al. (författare)
  • Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution : From Design to Applications
  • 2021
  • Ingår i: Chemical Reviews. - : American Chemical Society. - 0009-2665 .- 1520-6890. ; 121:8, s. 4373-4505
  • Tidskriftsartikel (refereegranskat)abstract
    • This Review compiles the evolution, mechanistic understanding, and more recent advances in enantioselective Pd-catalyzed allylic substitution and decarboxylative and oxidative allylic substitutions. For each reaction, the catalytic data, as well as examples of their application to the synthesis of more complex molecules, are collected. Sections in which we discuss key mechanistic aspects for high selectivity and a comparison with other metals (with advantages and disadvantages) are also included. For Pd-catalyzed asymmetric allylic substitution, the catalytic data are grouped according to the type of nucleophile employed. Because of the prominent position of the use of stabilized carbon nucleophiles and heteronucleophiles, many chiral ligands have been developed. To better compare the results, they are presented grouped by ligand types. Pd-catalyzed asymmetric decarboxylative reactions are mainly promoted by PHOX or Trost ligands, which justifies organizing this section in chronological order. For asymmetric oxidative allylic substitution the results are grouped according to the type of nucleophile used. © 2021 American Chemical Society.
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6.
  • Margalef, O., et al. (författare)
  • Environmental processes in Rano Aroi (Easter Island) peat geochemistry forced by climate variability during the last 70 kyr
  • 2014
  • Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 414, s. 438-450
  • Tidskriftsartikel (refereegranskat)abstract
    • We analyze the geochemistry of Rano Aroi mire record (Easter Island) using bulk peat composition (C, N, S) and stable isotopes (delta C-13, delta N-15, delta S-34) and major, minor and trace elemental compositions obtained by ICP-AES (Al, Ti, Zr, Sc, V, Y, Fe, Mn, Th, Ba, Ca, Mg and Sr). Peat geochemistry and the pollen record are used to reconstruct the environmental changes during the last 70 kyr BP. Principal component analysis on ICP-AES data revealed that three main components account for the chemical signatures of the peat. The first component, characterized by lithogenic elements (combined signal of V. Al, Sc, Y, Cr, Cd, Ti, Zr and Cu), evidences long-term changes in the basal fluxes of mineral material into the mire. This component, in combination with stable isotopes and pollen data suggests a link between soil erosion and vegetation cover changes in the Rano Aroi watershed. The second component is identified by the signal of Fe, Mn, Th, Ba, Zr and Ti, and is indicative of strong runoff events during enhanced precipitation periods. The third component (tied mainly to Ca, Sr and Mg) reflects a strong peat oxidation event that occurred during an arid period with more frequent droughts, sometime between 39 and 31 kyr BP. Correlation coefficients and a multiple regression model (PCR analysis) between peat organic chemistry and the principal components of ICP-AES analysis were calculated. Isotope chemistry of the peat organic matter further contributes to define Rano Aroi environmental history: delta C-13 data corroborates a vegetation shift documented by the palynological record from C-4 to C-3 between 55 and 45 cal kyr BP; the delta N-15 record identifies periods of changes in mire productivity and denitrification processes, while the delta S-34 peat signature indicates a marine origin of S and significant diagenetic cycling. The geochemical and environmental evolution of Rano Aroi mire is coherent with the regional climatic variability and suggests that climate was the main forcing in mire evolution during the last 70 kyr BP. The coupling of geochemical and biological proxies improves our ability to decipher depositional processes in tropical and subtropical peatlands and to use these sequences for paleoenvironmental and paleoclimate reconstructions.
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7.
  • Wahlers, J., et al. (författare)
  • Proofreading experimentally assigned stereochemistry through Q2MM predictions in Pd-catalyzed allylic aminations
  • 2021
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The palladium-catalyzed enantioselective allylic substitution by carbon or nitrogen nucleophiles is a key transformation that is particularly useful for the synthesis of bioactive compounds. Unfortunately, the selection of a suitable ligand/substrate combination often requires significant screening effort. Here, we show that a transition state force field (TSFF) derived by the quantum-guided molecular mechanics (Q2MM) method can be used to rapidly screen ligand/substrate combinations. Testing of this method on 77 literature reactions revealed several cases where the computationally predicted major enantiomer differed from the one reported. Interestingly, experimental follow-up led to a reassignment of the experimentally observed configuration. This result demonstrates the power of mechanistically based methods to predict and, where necessary, correct the stereochemical outcome. A predictive model has been created for a stereoselective palladium-catalysed allylic amination reaction. Derived only from quantum chemical data, the method is accurate enough to reveal multiple erroneous assignments in literature experiments.
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8.
  • Amendola, Giandomenico, et al. (författare)
  • Low-Earth Orbit User Segment in the Ku and Ka-Band
  • 2023
  • Ingår i: IEEE Microwave Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1527-3342 .- 1557-9581. ; 24:2, s. 32-48
  • Tidskriftsartikel (refereegranskat)abstract
    • Low-Earth orbit (LEO) constellations are revolutionizing the world of satellite communication (Satcom), providing new opportunities to manufacturers and operators and enabling innovative and attractive services to users.
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9.
  • Gunnarsson, Gunnar, et al. (författare)
  • Zero Prevalence of Influenza A Virus in Two Raptor Species by Standard Screening
  • 2010
  • Ingår i: Vector-borne and zoonotic diseases. - : Mary Ann Liebert Inc. - 1530-3667 .- 1557-7759. ; 10:4, s. 387-390
  • Tidskriftsartikel (refereegranskat)abstract
    • Disease can have sever impact on animal populations, especially in rare species. Baseline data for atypical host species are missing for a range of infectious diseases, although such hosts are potentially more affected than the normal vectors and reservoir species. If highly pathogenic avian influenza strikes rare birds of prey, this may have crucial impact on the predator species itself, but also on the food web in which it interacts. Here we present the first large-scale screening of raptors that regularly consume birds belonging to the natural reservoir of influenza A viruses. Influenza A virus prevalence was studied in two rare raptors, the white-tailed sea eagle (Haliaetus albicilla) and the peregrine falcon (Falco peregrinus). Nestlings were screened for active (181 white-tailed sea eagles and 168 peregrine falcons) and past (123 white-tailed sea eagles and 6 peregrine falcons) infection in 2006-2007, and an additional 20 succumbed adult white-tailed sea eagles were sampled in 2003-2006. Neither high- nor low-pathogenic influnza infections were found in our sample, but this does not rule out that the former may have major impact on rare raptors and their food webs.
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10.
  • Latorre-Margalef, Neus, et al. (författare)
  • Effects of influenza A virus infection on migrating mallard ducks
  • 2009
  • Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 276:1659, s. 1029-1036
  • Tidskriftsartikel (refereegranskat)abstract
    • The natural reservoir of influenza A virus is waterfowl, particularly dabbling ducks (genus Anas). Although it has long been assumed that waterfowl are asymptomatic carriers of the virus, a recent study found that low-pathogenic avian influenza (LPAI) infection in Bewick's swans (Cygnus columbianus bewickii) negatively affected stopover time, body mass and feeding behaviour. In the present study, we investigated whether LPAI infection incurred ecological or physiological costs to migratory mallards (Anas platyrhynchos) in terms of body mass loss and staging time, and whether such costs could influence the likelihood for long-distance dispersal of the avian influenza virus by individual ducks. During the autumn migrations of 2002-2007, we collected faecal samples (n = 10 918) and biometric data from mallards captured and banded at Ottenby, a major staging site in a flyway connecting breeding and wintering areas of European waterfowl. Body mass was significantly lower in infected ducks than in uninfected ducks (mean difference almost 20 g over all groups), and the amount of virus shed by infected juveniles was negatively correlated with body mass. There was no general effect of infection on staging time, except for juveniles in September, in which birds that shed fewer viruses stayed shorter than birds that shed more viruses. LPAI infection did not affect speed or distance of subsequent migration. The data from recaptured individuals showed that the maximum duration of infection was on average 8.3 days (s.e. 0.5), with a mean minimum duration of virus shedding of only 3.1 days (s.e. 0.1). Shedding time decreased during the season, suggesting that mallards acquire transient immunity for LPAI infection. In conclusion, deteriorated body mass following infection was detected, but it remains to be seen whether this has more long-term fitness effects. The short virus shedding time suggests that individual mallards are less likely to spread the virus at continental or intercontinental scales.
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