| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Adolph, C, et al.
(författare)
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Measurement of the eta -> 3 pi(0) Dalitz plot distribution with the WASA detector at COSY
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 677:1-2, s. 24-29
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Tidskriftsartikel (refereegranskat)abstract
- In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pious was Studied using 1.2 x 10(5) fully reconstructed events. and the quadratic slope parameter alpha was determined to be -0.027 +/- 0.008(stat) +/- 0.005(syst). The result is consistent with previous measurements and further corroborates the importance of pion-pion final state interactions. (C) 2009 Elsevier B.V. All rights reserved.
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| 4. |
- Cuello, C., et al.
(författare)
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Vitrification of in vitro cultured porcine two-to-four cell embryos
- 2007
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Ingår i: Theriogenology. - : Elsevier. - 0093-691X .- 1879-3231. ; 68:2, s. 258-264
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this experiment was to evaluate the effect of a 5-day period of in vitro culture of two-to-four cell porcine embryos up to the blastocyst stage on their ability to survive vitrification and warming. In order to increase the cooling rate, superfine open pulled straws and Vit-Master (R) technology were used for vitrification. Two-to-four cell embryos were collected from weaned sows (n = 11) on day 2 (DO = onset of estrus). Some embryos (N = 63) were vitrified within 3 It after collection, warmed and cultured for 120 h (Group V2). Additionally, 81 two-to-four cell embryos were cultured for 96 It in order to obtain blastocysts; these were then vitrified, warmed and cultured for 24 h (Group VB; N = 65). The remaining two-to-four cell embryos were used as controls and thus not vitrified (control embryos; N = 70) but were cultured in vitro for 120 h. The V2, VB and control embryos were evaluated for their developmental progression and morphology during culture. All embryos (V2, VB and controls) were fixed on the same day of development in order to assess the total number of blastomeres. The survival and blastocyst formation rates obtained from V2 embryos were very poor (9.6 +/- 0.7% and 3.2 +/- 0.5%, respectively). The survival and hatching rates of VB embryos (75.0 +/- 0.69% and 33.6 +/- 0.13%) were lower (p less than 0.001) than those obtained with control embryos (89.1 +/- 0.8% and 47.5 +/- 0.12%). Hatched VB embryos had a lower (p less than 0.01) total cell number than hatched control embryos (70.3 +/- 4.5 versus 90.6 +/- 3.2, respectively). There was no difference between expanded VB and control blastocysts. In conclusion, blastocysts derived from in vitro culture of two-to-four cell pig embryos could be successfully vitrified using SOPS straws and Vit-Master (R). (c) 2007 Elsevier Inc. All rights reserved.
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| 5. |
- D'Agrella-Filho, Manoel Souza, et al.
(författare)
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Proterozoic paleogeographic evolution of South American cratons
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The South American platform is composed of four major cratons (Amazonian, São Francisco, Rio de la Plata and São Luis) and other smaller continental blocks and terrains that may have taken part in supercontinental assemblages. Here, paleogeographic configurations from the Paleoproterozoic up to the Cambrian are tested by means of an updated paleomagnetic and geochronologic record of South America, including new high-quality poles from the Amazonian and São Francisco cratons. These poles are compared to those of other cratons thought to have interacted with South American units in the Proterozoic, such as Baltica and Laurentia. The oldest assemblage of continents to be addressed is the Paleoproterozoic Columbia (~1800 Ma), for which our data support a configuration aligning Laurentia, Baltica, North China and Amazonia through their Paleo-Mesoproterozoic belts. For Neoproterozoic times (~1200-1000 Ma) a connection between Laurentia and the Amazonian craton in an evolving configuration (with relative movement between the two units) is supported by a pole-to-pole comparison. In contrast, striking differences in Laurentia's drift history compared to São Francisco, São Luis (=West Africa) and Kalahari rule-out the effective participation of these cratons in Rodinia. The assembly of Gondwana has probably occurred in different steps, comprising first (~630 Ma) the connection between Sao Francisco, Rio de la Plata, other minor blocks and the African cratons, followed by the collision of these central Gondwanan blocks with the Amazonian craton and adjoining blocks by mid-Cambrian times (~530 Ma), after the opening of the Iapetus ocean basin between Laurentia and the Amazonian craton. In this scenario, the West Gondwana was not a coherent tectonic unit before the end of Precambrian times.
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| 6. |
- Kanungo, R., et al.
(författare)
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One-Neutron Removal Measurement Reveals O-24 as a New Doubly Magic Nucleus
- 2009
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 102:15
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Tidskriftsartikel (refereegranskat)abstract
- The first measurement of the momentum distribution for one-neutron removal from O-24 at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s(1/2) neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that O-24 is a new doubly magic nucleus.
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| 7. |
- Nociforo, C., et al.
(författare)
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Shell Closure N=16 in O-24
- 2009
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1165, s. 90-93 461
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Konferensbidrag (refereegranskat)abstract
- Advanced nuclear structure models predict the presence of the shell closures N=14, 16 in neutron-rich O isotopes rather than N=20. Spectroscopic investigations performed at the neutron drip line have recently confirmed such predictions showing that the O-24 is a doubly magic nucleus (Z=8, N=16). Predictions within the shell model calculation for the O-23,O-24 ground state have been confirmed measuring their spectroscopic factors. Results obtained in one-neutron removal reactions performed by using in-flight radioactive ion beams produced at the Fragment Separator FRS of GSI are reported.
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| 8. |
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| 9. |
- Sancho, S., et al.
(författare)
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Effects of cryopreservation on semen quality and the expression of sperm membrane hexose transporters in the spermatozoa of Iberian pigs
- 2007
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Ingår i: Reproduction. - : BioScientifica. - 1470-1626 .- 1476-3990. ; 134:1, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the effects of cooling, freezing and thawing on the plasma membrane integrity, kinetics and expression of two sugar transporters glucose transporter-3 and -5 (GLUT-3 and GLUT-5) in spermatozoa from Iberian boars. Semen samples were collected twice weekly from eight young, fertile Iberian boars of the Entrepelado and Lampino breeds. The samples were suspended in a commercial extender and refrigerated to 17 degrees C for transport to the laboratory (step A), where they were further extended with a lactose-egg yolk-based extender and chilled to 5 degrees C (step B) prior to freezing in the presence of glycerol (3%). Spermatozoa were assessed for plasma membrane integrity and sperm motility at each of the steps, including post-thaw (step C). Aliquots were also prepared for immunocytochemical localisation of the sugar transporters (fixed and thin smears for transmission and scanning electron microscopy levels respectively) and for SDS-PAGE electrophoresis and subsequent western blotting, using the same antibodies (rabbit anti-GLUT-3 and anti-GLUT-5 polyclonal antibodies). The results showed lower percentages of progressively motile spermatozoa at step C in both breeds, while the percentage of live spermatozoa was significantly lower only in the Entrepelado breed. The results obtained from electron microscopy clearly showed that Iberian boar spermatozoa expressed the hexose transporters, GLUT-3 and GLUT-5. The pattern of expression, in terms of location and concentration, was characteristic in each case but, in the case of isoform GLUT-5, it remained constant during the different steps of freezing-thawing protocol. These results indicate that cryopreservation affects the status of sperm cells of Iberian boars by altering the distribution of some membrane receptors and decreasing the percentage values of parameters linked to sperm quality.
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| 10. |
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