| 1. |
- Adlarson, Patrik, et al.
(författare)
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Abashian-Booth-Crowe Effect in Basic Double-Pionic Fusion : A New Resonance?
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:24, s. 242302-
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Tidskriftsartikel (refereegranskat)abstract
- We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction pn -> d pi(0)pi(0) over the full energy region of the ABC effect, a pronounced low-mass enhancement in the pi pi-invariant mass spectrum. The measurements, which cover also the transition region to the conventional t- channel Delta Delta process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with m = 2.37 GeV, Gamma approximate to 70 MeV and I(J(P)) = 0(3(+)) in both pn and Delta Delta systems. Necessary further tests of the resonance interpretation are discussed.
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| 2. |
- Artedi, Peter, et al.
(författare)
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Ichthyologia
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Bargholtz, Chr., et al.
(författare)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 4. |
- Bargholtz, Chr., et al.
(författare)
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The WASA detector facility at CELSIUS
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
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Tidskriftsartikel (refereegranskat)abstract
- The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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| 5. |
- Bashkanov, M., et al.
(författare)
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Double-Pionic Fusion of Nuclear Systems and the "ABC" Effect : Approaching a Puzzle by Exclusive and Kinematically Complete Measurements
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 052301-
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Tidskriftsartikel (refereegranskat)abstract
- The ABC effect-a puzzling low-mass enhancement in the pi pi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn -> d pi(0)pi(0) at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pi pi)(I=L=0) channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a Delta Delta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.
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| 6. |
- Bashkanov, M., et al.
(författare)
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Exclusive measurements of pd -> He-3 pi pi : The ABC effect revisited
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 637:4-5, s. 223-228
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Tidskriftsartikel (refereegranskat)abstract
- Exclusive measurements of the reactions pd -> He-3 pi(+)7 pi(-) and pd -> He-3 pi(0)pi(0) have been carried out at T-p = 0.893 GeV at the CELSIUS storage ring using the WASA detector. The pi(+)pi(-) channel evidences a pronounced enhancement at low invariant pi pi masses-as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar pi(0)pi(0) channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. Delta Delta calculations give a good description of the data, if a boundstate condition is imposed for the intermediate Delta Delta system.
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| 7. |
- Bashkanov, M., et al.
(författare)
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Low-mass pi pi enhancement in baryonic pi pi production : ABC effect revised by exclusive measurements
- 2007
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Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 22:2-3, s. 625-628
-
Tidskriftsartikel (refereegranskat)abstract
- The ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of double-pionic fusion to nuclear bound states - has been investigated since 40 years by inclusive measurements without providing a conclusive interpretation. First exclusive measurements to this topic have now been carried out at CELSIUS-WASA. They confirm a huge ππ threshold enhancement, prove it to be of scalar-isoscalar nature, i.e., a σ-channel phenomenon and reveal the theoretically predicted high-mass enhancement in inclusive spectra to be of πππ rather than of ππ nature - falsifying thus corresponding model predictions for the ABC effect. From the kinematically complete data samples we infer that the interaction between the two Δ particles created in this process is of crucial importance.
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| 8. |
- Bashkanov, M., et al.
(författare)
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Measurement of the slope parameter for the η → 3π0 decay in the pp → ppη reaction
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 048201-
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Tidskriftsartikel (refereegranskat)abstract
- The CELSIUS-WASA setup is used to measure the 3π0 decay of η mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter α yielding α = −0.026 ± 0.010(stat) ± 0.010(syst). This value is compared to recent experimental results and theoretical predictions.
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| 9. |
- Bashkanov, M., et al.
(författare)
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Two-pion production in proton-proton collisions
- 2004
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Ingår i: Hadron Spectroscopy, Tenth International Conference on Hadron Spectrscopy, Aschaffenburg, Germany 31 August - 6 September 2003. - 0735401977 ; , s. 241-244
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
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| 11. |
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| 12. |
- Berlowski, M., et al.
(författare)
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Measurement of eta meson decays into lepton-antilepton pairs
- 2008
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:3, s. 032004-
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Tidskriftsartikel (refereegranskat)abstract
- A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta -> e(+)e(-)e(+)e(-) events are reported with a background of 1.3 +/- 0.2 events. This allows to set an upper limit to the branching ratio of 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Britz, Ralf, et al.
(författare)
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Dario tigris and Dario melanogrammus, two new species of miniature chameleon fishes from northern Myanmar (Teleostei: Badidae)
- 2022
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Ingår i: Zootaxa. - : Magnolia Press. - 1175-5326 .- 1175-5334. ; 5138:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Dario tigris, new species, is described from mountain streams south of Mogaung, in the Ayeyarwaddy River basin, Myanmar. It differs from congeneric species by its unique colour pattern, which consists of a series of eight straight vertical bars, the first two of which in males are ash-grey and the subsequent six are orange-red in life, combined with a series of small black spots arranged in three to four rows dorsolaterally on the head and nape. It differs further from its close relative Dario hysginon, with which it may occur syntopically, by fewer dorsal-fin spines (modally 14 vs modally 15), and fewer vertebrae (modally 12+12=24 vs modally 12+13= 25). Dario melanogrammus, new species, is another barred Dario from the Chindwin River basin. It differs from all other species of the genus by its zigzagging dark vertical bars; amongst Myanmar species, it can be further distinguished from D. hysginon and D. tigris by more vertebrae (modally 26 vs 25 in D. hysginon, and 24 in D. tigris).
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| 17. |
- Britzke, Ricardo, et al.
(författare)
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Apistogramma ortegai (Teleostei: Cichlidae), a new species of cichlid fish from the Ampyiacu River in the Peruvian Amazon basin
- 2014
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Ingår i: Zootaxa. - : Magnolia Press. - 1175-5326 .- 1175-5334. ; 3869:4, s. 409-419
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Tidskriftsartikel (refereegranskat)abstract
- Apistogramma ortegai, new species, is described from small streams tributaries of the Ampiyacu River near Pebas, in easternPeru. It belongs to the Apistogramma regani species group and is distinguished from all other species of Apistogrammaby the combination of contiguous caudal spot to bar 7, presence of abdominal stripes, short dorsal-fin lappets in both sexes,absence of vertical stripes on the caudal fin, and reduced number of predorsal and prepelvic scales.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Brodowski, W, et al.
(författare)
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Two-Pion Production in Nucleon-Nucleon Collisions
- 2002
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Ingår i: Proc. Int. Conf. on Production, Properties and Interaction of Mesons, MESON 2002, Cracow, Poland, 2002..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 22. |
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| 23. |
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| 24. |
- Calén, Hans, et al.
(författare)
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Measurement of η meson decays into lepton-antilepton pairs
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A search for rare lepton decays of the η meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay η→e+e−e+e− events are reported with a background of 1.3±0.2 events. This allows to set an upper limit to the branching ratio of 9.7×10−5 η(90% CL). The branching ratio for the decay η→e+e−γ is determined to (7.8±0.5stat ±0.8syst)×10−3 in agreement with world average value. An upper limit (90% CL) for the branching ratio for the η→e+e− decay is 2.7 × 10−5 and a limit for the sum of the η→μ+μ−μ+μ− and η→π+π−μ+μ− decays is 3.6 × 10−4.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- de Jong, Yde, et al.
(författare)
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PESI - a taxonomic backbone for Europe
- 2015
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Ingår i: Biodiversity Data Journal. - 1314-2836 .- 1314-2828. ; 3, s. 1-51
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Tidskriftsartikel (refereegranskat)abstract
- Reliable taxonomy underpins communication in all of biology, not least nature conservation and sustainable use of ecosystem resources. The flexibility of taxonomic interpretations, however, presents a serious challenge for end-users of taxonomic concepts. Users need standardised and continuously harmonised taxonomic reference systems, as well as high-quality and complete taxonomic data sets, but these are generally lacking for non-specialists. The solution is in dynamic, expertly curated web-based taxonomic tools.The Pan-European Species-directories Infrastructure (PESI) worked to solve this key issue by providing a taxonomic e-infrastructure for Europe. It strengthened the relevant social (expertise) and information (standards, data and technical) capacities of five major community networks on taxonomic indexing in Europe, which is essential for proper biodiversity assessment and monitoring activities. The key objectives of PESI were: 1) standardisation in taxonomic reference systems, 2) enhancement of the quality and completeness of taxonomic data sets and 3) creation of integrated access to taxonomic information.This paper describes the results of PESI and its future prospects, including the involvement in major European biodiversity informatics initiatives and programs.
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| 32. |
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| 33. |
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| 34. |
- Deprá, Gabriel C., et al.
(författare)
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A new colorful species of Geophagus (Teleostei: Cichlidae), endemic to the rio Aripuanã in the Amazon basin of Brazil
- 2014
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Ingår i: Neotropical Ichthyology. - : FapUNIFESP (SciELO). - 1679-6225 .- 1982-0224. ; 12:4, s. 737-746
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Tidskriftsartikel (refereegranskat)abstract
- Geophagus mirabilis, new species, is endemic to the rio Aripuanã drainage upstream from Dardanelos/Andorinhas falls.The new species is distinguished from all other species of the genus by the presence of one to five large black spots arrangedlongitudinally along the middle of the flank, in addition to the black midlateral spot that is characteristic of species in thegenus and by a pattern of iridescent spots and lines on the head in living specimens. It is further distinguished from allcongeneric species, except G. camopiensis and G. crocatus, by the presence of seven (vs. eight or more) scale rows in thecircumpeduncular series below the lateral line (7 in G. crocatus; 7-9 in G. camopiensis). Including the new species, five cichlids and 11 fish species in total are known only from the upper rio Aripuanã, and 15 fish species in total are known only from the rio Aripuanã drainage
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| 35. |
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| 36. |
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| 37. |
- Fang, Fang, et al.
(författare)
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Molecular phylogenetic interrelationships of the south Asian cyprinid genera Danio, Devario and Microrasbora (Teleostei, Cyprinidae, Danioninae)
- 2009
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Ingår i: Zoologica Scripta. - : Wiley. - 0300-3256 .- 1463-6409. ; 38:3, s. 237-256
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Tidskriftsartikel (refereegranskat)abstract
- Molecular analysis of mitochondrial cytochrome b sequences from 159 species of the family Cyprinidae supports the subfamily Danioninae, of which Rasborinae is shown to be a junior synonym. Analysis of combined cytochrome b and a fragment of the nuclear rhodopsin gene from 68 species, including 43 species representing the subfamily Danioninae, supports phylogenetic distinctness of Danio and Devario. In the combined molecular analysis Microrasbora rubescens, Chela, Laubuca, Devario, and Inlecypris form a clade with M. gatesi, M. nana and M. kubotai being in sister group position to the rest. The sister group of this Devario clade is Danio. Inlecypris is synonymized with Devario. Microdevario, new genus, is proposed for M. gatesi, M. nana and M. kubotai, supported by morphological characters. In the cytochrome b analysis, M. rubescens falls outside Devario, and there is no morphological support for including M. rubescens in Devario. In the cytochrome b analysis Esomus+Danionella is the sister group of Danio and Devario clades, whereas in individual rhodopsin and combined analyses Esomus is the sister group of Danio, and of Danio and the Devario clade, respectively. Sundadanio presents at least one strong morphological synapomorphy with Danio, but is positioned in molecular trees either as a member of the Cyprininae or as sister group of the remaining Danioninae. In the morphological analysis, small-sized species grouped together based on shared reductions that are not necessarily synapomorphies. In the molecular analysis, small-sized species such as Danionella and Sundadanio possess long branches and their position varies, but they did not group together. This suggests morphological homoplasy, but phylogenetic positions are not well supported in the molecular analyses.
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| 38. |
- Fernholm, Bo, et al.
(författare)
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Hagfish phylogeny and taxonomy, with description of the new genus Rubicundus (Craniata, Myxinidae)
- 2013
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - : Hindawi Limited. - 0947-5745 .- 1439-0469. ; 51:4, s. 296-307
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Tidskriftsartikel (refereegranskat)abstract
- A recent phylogenetic analysis of the Myxinidae based on the 16S rRNA gene resulted in synonymization of Paramyxine with Eptatretus. This created homonymy of Paramyxine fernholmi with Eptatretus fernholmi and Paramyxine wisneri with Eptatretus wisneri. In order to resolve this nomenclatural dilemma, we made a more extensive phylogenetic assessment of the Myxinidae and examined the nomenclature of the family. We used 75 sequences (37 of which new for this study) of a 561 bp fragment of the 16S rRNA gene, representing 33 species, and 72 sequences (37 of which new for this study) of a 687 bp fragment of the cytochrome c oxidase subunit I (COI) gene, representing 23 species, to reconstruct the phylogeny of Myxinidae. The monophyly of the subfamily Myxininae, traditionally characterized by having a single pair of external gill openings, was rejected (0.50 Bayesian posterior probability) by the 16S analysis, but supported by the COI and combined COI+16S analyses (0.99 and 0.81 Bpp, respectively). The monophyly of the subfamily Eptatretinae, characterized by having several pairs of external gill openings, was not supported by the 16S analysis and rejected by the COI and combined COI+16S analysis due to the placement of Eptatretus lopheliae as the earliest branch of Myxinidae (0.71 and 0.57 Bpp, respectively). Eptatretus lopheliae and Eptatretus rubicundus formed a monophyletic group and were allocated to a new genus, Rubicundus, characterized by the presence of an elongated tubular nostril and reddish coloration. A new monotypic subfamily, Rubicundinae, was proposed for Rubicundus. The synonymy of the genera Paramyxine and Quadratus with Eptatretus was confirmed. E. fernholmi is renamed Eptatretus luzonicus. Eptatretus wisneri was renamed Eptatretus bobwisneri. Petromyzon cirrhatus Forster, 1801, Homea banksii Fleming, 1822, and Bdellostoma forsteri Müller, 1836 are synonyms, but no type specimens are known to exist. Petromyzon cirrhatus was designated as type species of Eptatretus, conserving present usage. Gastrobranchus dombeyi Shaw, 1804 has priority over other names for Chilean myxinids. Bdellostoma stoutii was designated as type species of Polistotrema Gill. The validity of the Western Atlantic Myxine limosa as distinct from the Eastern Atlantic Myxine glutinosa was confirmed.
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| 39. |
- Grandin, Karl, et al.
(författare)
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Nuclear Energy
- 2010
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Ingår i: AMBIO. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 39:Suppl. 1, s. 26-30
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear energy can play a role in carbon free production of electrical energy, thus making it interesting for tomorrow’s energy mix. However, several issues have to be addressed. In fission technology, the design of so-called fourth generation reactors show great promise, in particular in addressing materials efficiency and safety issues. If successfully developed, such reactors may have an important and sustainable part in future energy production. Working fusion reactors may be even more materials efficient and environmental friendly, but also need more development and research. The roadmap for development of fourth generation fission and fusion reactors, therefore, asks for attention and research in these fields must be strengthened.
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| 40. |
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| 41. |
- Hammarström, Leif, et al.
(författare)
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Preface : Special Report: Capturing the Sun
- 2012
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 41:Suppl 2, s. 101-102
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 42. |
- Hedberg, Dick, et al.
(författare)
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The World Needs a New Energy Paradigm
- 2010
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 39, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- During 19-20 October 2009, the Royal Swedish Academy of Sciences arranged the international symposium Energy 2050 in Stockholm. The symposium was held in association with the Swedish EU presidency in autumn 2009. Internationally renowned scientists assessed the energy issue in a broad perspective, with particular emphasis on the possibilities of a fossil-free future. The symposium focused on key topics emanating from the in-depth energy studies carried through by the Academys Energy Committee since 2005. The world community is facing a challenge of historic proportions to define a new energy paradigm based on fossil-energy substitutes. This article gives an overview of the current global energy situation (2007) and of the technologies which have the major potential for supplying energy up to year 2050 without jeopardizing the CO2 emission targets.
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| 43. |
- Jacewicz, Marek, 1973-
(författare)
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Measurement of the Reaction pp→ppπ+π-π0 with CELSIUS/WASA at 1.36 GeV
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A versatile detector setup prepared by the CELSIUS/WASA collaboration for exclusive studies of rare processes produced in proton and deuteron collisions with hydrogen and deuterium pellet targets is presented. For the near-threshold production of light mesons, π0 and η, the scattered beam and target particles are measured in the forward detector, while the products of the decaying mesons are registered in a central detector covering close-to-4π sr.The central detector is composed of a mini-drift chamber consisting of 1738 straw tubes for tracking of the charged particles and a plastic scintillator barrel consisting of 146 scintillation counters providing fast signals of the passing particles. These two detector parts are placed inside of a superconducting solenoid providing an axial magnetic field.Outside of the solenoid is placed an electromagnetic calorimeter consisting of 1012 CsI crystals. The construction, calibration and performance of the plastic scintillator barrel is presented in detail. Its main purpose is the discrimination of charged and neutral particles on the trigger level. It is also used for the identification of charged particles by ΔE-p (ΔE-E) technique in the off-line analysis.The mini-drift chamber is a detector for determination of particles momenta and reaction vertex. It is built with minimum structural material and designed to withstand high particle fluxes at a luminosity 1032cm-2s-1. The design of the mini-drift chamber, a description of the calibration procedure, its performance and integration in the data analysis are presented.The overall performance of the WASA detector is demonstrated by the analysis of the pp→ppπ+π-π0 reaction at 1.36 GeV incident proton energy. The total cross section for the non-resonant part of the reaction is estimated for the first time in this energy region to be 4.6 ±1.2 -0.9 +0.7 μb. The pp→ppη part of the total reaction cross section is estimated to be 4.8 μb which is consistent with the existing experimental information.
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| 44. |
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| 45. |
- Khakimova, O., et al.
(författare)
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Observation of the abc effect in the first exclusive measurements of pn -> d pi(0)pi(0)
- 2007
-
Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 22:2-3, s. 617-620
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pn → dπ0π0 constitutes the most fundamental system for the study of the ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of the ππ system in double-pionic fusion to nuclear bound states. The first exclusive measurements of this reaction have now been carried out at CELSIUS-WASA. They exhibit a striking low-mass enhancement in the ππ invariant mass spectrum, prove it to be a σ-channel phenomenon and falsify conventional theoretical models, which predict an associated high-mass enhancement not present in the new exclusive data. In the kinematically complete data sample we observe a ΔΔ excitation, where the interaction between the two Δ obviously plays a crucial role for the generation of the ππ low-mass enhancement.
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| 46. |
- Koch, Inken, 1972-
(författare)
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Measurements of 2π0 and 3π0 Production in Proton-Proton Collisions at a Center of Mass Energy of 2.465 GeV
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neutral two- and three-pion productions in proton-proton collisions at a center of mass energy of 2.465 GeV have been studied using the WASA detector and an internal pellet target at the CELSIUS storage ring in Uppsala. An important part of the detector for the measurments was a central electromagnetic calorimeter composed of 1012 CsI crystals, which measured the photons originating from neutral pion decays. Test measurements and calibration procedures for this detector part were carried out. An important part of the analysis was the identification of the neutral pions from the invariant mass of the decay gammas and the use of Monte Carlo simulations to understand the detector responds.Total cross sections for the pp→ppπ0π0 and pp→ppπ0π0π0 reactions are presented as well as distributions of relevant kinematical variables for the pp→ppπ0π0 reaction.The distributions show significant deviations from phase space predictions. These deviations are typical for resonance production. The excitation of two simultaneous Δ resonances seems to be the main reaction mechanism.
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| 47. |
- Kren, F., et al.
(författare)
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Exclusive measurements of pp -> d pi(+)pi(0) : Double-pionic fusion without ABC effect
- 2010
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 684:2-3, s. 110-113
-
Tidskriftsartikel (refereegranskat)abstract
- Exclusive measurements of the reaction pp -> d pi(+)pi(0) have been carried out at T-p = 1.1 GeV at the CELSIUS storage ring using the WASA detector. The isovector pi(+)pi(0) channel exhibits no enhancement at low invariant pi pi masses, i.e. no ABC effect. Therefore this most basic isovector double-pionic fusion reaction qualifies as an ideal test case for the conventional t-channel Delta Delta excitation process. Indeed, the obtained differential distributions reveal the conventional t-channel Delta Delta mechanism as the appropriate reaction process, which also accounts for the observed energy dependence of the total cross section.
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| 48. |
- Kren, F., et al.
(författare)
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THE pp -> d pi(+)pi(0) REACTION - A CASE OF Delta Delta EXCITATION WITHOUT ABC-EFFECT
- 2009
-
Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 24:2-3, s. 561-563
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Tidskriftsartikel (refereegranskat)abstract
- The ABC effect, a low-mass enhancement in the invariant pp mass, is observed in double-pionic fusion reactions leading to a bound nuclear system in the final state. From previous measurements there have been indications that this phenomenon is resctricted to the sigma channel of the pp system. With exclusive measurements of the pp -> d pi(+)pi(0) reaction at T-p = 1.1 GeV we demonstrate that, indeed, the ABC effect does not occur in the vector-isovector Delta Delta channel (rho channel) despite the fact that the Delta Delta excitation is oberved to be the dominant reaction process. We also show that this reaction is well described by a t-channel Delta Delta excitation with the subsequent decay into the vector-isovector Delta Delta channel given by the rho channel operator.
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| 49. |
- Kullander, Sven, 1952-, et al.
(författare)
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Chalinochromis cyanophleps, a new species of cichlid fish (Teleostei: Cichlidae) from Lake Tanganyika
- 2014
-
Ingår i: Zootaxa. - : Magnolia Press. - 1175-5326 .- 1175-5334. ; 3790:3, s. 425-438
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Tidskriftsartikel (refereegranskat)abstract
- Chalinochromis cyanophleps is described from nine specimens, the largest 129 mm SL, from Namansi. It differs fromother species of Chalinochromis in plain trunk colouration, absence of black stripes on the head, relatively narrow lips, presence of tricuspid jaw teeth, and presence of five rather than four dentary lateralis foramina. The blue iridescent stripe below the eye is shared with other lamprologin cichlids, but is broader and more conspicuous in C. cyanophleps. Chalinochromis cyanophleps occurs at depths between 6 and 45 m in rocky habitats along the Tanzanian coast of Lake Tanganyika,from Mvuna Island south to Kalala Island, a stretch of about 90 km. Field observations were made of specimens up to 18 cm total length. The COI DNA barcode sequence differs by 1.8% from that of C. popelini.
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- Kullander, Sven
(författare)
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Concluding Remarks for STORI’02
- 2003
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Ingår i: Proc. 5th Int. Conf. on Nuclear Physics at Storage Rings, STORI’02, Uppsala, Sweden, 2002, Physics Scripta. ; , s. 196-
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Konferensbidrag (refereegranskat)
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