| 1. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Poropat, Stephen F., et al.
(författare)
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Photographic Atlas and Three-Dimensional Reconstruction of the Holotype Skull of Euhelopus zdanskyi with Description of Additional Cranial Elements
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:11, s. e79932-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Euhelopus zdanskyi is one of relatively few sauropod taxa known from an almost complete skull and mandible. Recent phylogenetic analyses suggest that Euhelopus is a somphospondylan titanosauriform, and that it is a member of the clade (Euhelopodidae) which is the sister taxon to the hugely successful, dominantly Cretaceous sauropod group Titanosauria. Methodology/Principal Findings: The skull elements of Euhelopus were CT scanned at Uppsala Akademiska Sjukhuset. Three-dimensional models of the elements were constructed from the DICOM data using Mimics 14.0, InVesalius 3.0, and GeoMagic Studio 2012, the skull was rearticulated in Rhinoceros 4.0, and the final version was rendered in GeoMagic Studio 2012. Conclusions/Significance: The fact that relatively complete sauropod skulls are so rare in the fossil record, particularly among titanosauriforms, means that the skulls that are known should be as thoroughly described and well-illustrated as possible. This contribution supplements previous descriptions of the cranial elements of Euhelopus, one of the few euhelopodid taxa for which cranial material is known, by presenting a comprehensive photographic atlas of the skull elements to facilitate a better understanding of their morphology. We describe several elements which have been overlooked in past studies of Euhelopus, and also provide as accurate a reconstruction of the skull as possible (in the absence of the braincase), the most significant components of which are the articulations of the palate and the mandible.
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| 3. |
- Poropat, Stephen F., et al.
(författare)
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Reassessment of coelurosaurian (Dinosauria, Theropoda) remains from the Upper Cretaceous Wangshi Group of Shandong Province, China
- 2013
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Ingår i: Cretaceous research (Print). - : Elsevier BV. - 0195-6671 .- 1095-998X. ; 45, s. 103-113
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Tidskriftsartikel (refereegranskat)abstract
- Non-avian theropods are well represented in the Cretaceous of Asia. However, the first theropod remains ever reported from China, from the Wangshi Group of Shandong Province, have not been reassessed since they were described by Carl Wiman in 1929, despite the great strides that have been made in theropod phylogenetics in the last eight decades. The remains redescribed herein consist of four vertebrae (two cervicals, one dorsal and one caudal) from one site, and a caudal vertebra and ungual phalanx from another. The vertebrae from the first site are assigned to tyrannosauroids and ornithomimosaurs, as is the caudal vertebra from the second site, whereas the manual ungual also bears resemblances to those of non-maniraptoran coelurosaurs (specifically compsognathids and ornithomimosaurs). Theropods remain relatively rare in the Wangshi Group; nevertheless, the remains redescribed herein highlight the potential for the discovery of more theropod remains in future excavations.
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| 4. |
- Poropat, Stephen F., et al.
(författare)
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The significance of Carl Wiman's sauropod dinosaurs
- 2011
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Ingår i: The 2nd Wiman Meeting. Carl Wiman's Legacy: 100 Years of Swedish Palaeontology. ; , s. 20-21
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Of the Mesozoic vertebrate fossils received and published on by Carl Wiman during his diverse career as Sweden's first Professor of Palaeontology, his sauropod dinosaurs arguably remain some of the most significant to modern researchers. In particular, Euhelopus [Helopus] zdanskyi described by Wiman in 1929 from the Lower Cretaceous Qingshan Formation of China is one of the best-known taxa, being represented by a partial skull and associated presacral axial skeleton, referred dorsal vertebral series, complete hind limb, and partial forelimb. Paradoxically, the anatomy, phylogenetic relationships, and stratigraphical disposition of Euhelopus have until recently been highly controversial. Indeed, on-going work is now focused upon the biomechanical aspects of the skull and ultimately will undertake a complete CT-based reconstruction of the head and neck to investigate eco-morphological adaptations amongst titanosauriforms. Wiman's other important sauropod discoveries include several isolated vertebrae also from the Qingshan Formation: (1) a caudal interpreted as the first Asian diplodocid; and (2) a cervical and dorsal, both of which are under study but might represent other titanosauriform taxa. Another collection of sauropod postcranial elements (an ilium, cervical vertebra, and three sacral vertebrae) sent by the famous American dinosaur collector Charles H. Sternberg in 1921, might represent components of the holotype of Alamosaurus sanjuanensis, a Late Cretaceous (Maastrichtian) titanosaurid from the Kirtland Formation of New Mexico. Despite having been in the scientific spotlight for more than 80 years, Carl Wiman's specimens are still critical to the broader understanding of Cretaceous sauropod evolution.
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