| 1. |
- Hyldegaard, S., et al.
(författare)
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Precise branching ratios to unbound 12C states from 12N and 12B [beta]-decays
- 2009
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 678:5, s. 459 - 464
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Tidskriftsartikel (refereegranskat)abstract
- Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in 12C from 12N and 12B [beta]-decays. In the first the three [alpha]-particles emitted after [beta]-decay are measured in coincidence in separate detectors, while in the second method 12N and 12B are implanted in a detector and the summed energy of the three [alpha]-particles is measured directly. For the narrow states at 7.654 MeV (0+) and 12.71 MeV (1+) the resulting branching ratios are both smaller than previous measurements by a factor of [similar, equals]2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.
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| 2. |
- Bertolotto, L, et al.
(författare)
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phi phi associated production in (p)over-bar-p annihilation from JETSET
- 1996
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Ingår i: PHYSICS OF ATOMIC NUCLEI. - : AMER INST PHYSICS. ; , s. 1444-1449
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Konferensbidrag (refereegranskat)abstract
- The JETSET (PS202) experiment at CERN has studied the reaction (p) over bar p --> 4K(+/-) in the invariant-mass range from 2.15 to 2.43 GeV/c(2). The phi phi, phi K+K-, and 4K(+/-) cross sections have been measured, and a spin-parity analysis of the phi p
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| 3. |
- Fynbo, H. O. U., et al.
(författare)
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The β-decay approach for studying 12C
- 2008
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 111:1
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Tidskriftsartikel (refereegranskat)abstract
- The β-decays of the mirror nuclei 12B and 12N both populate states in 12C and they are therefore a precious source of information about this nucleus. Due to the selection rules of β-decay only 0+, 1+ and 2+ states are populated. This allows a very clean study of unbound states just above the 3α-threshold with those spin and parities. This probe has been applied in two experiments using two complementary experimental techniques: in the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors using the ISOL method, while in the second method 12B and 12N are implanted in a detector and the summed energy of the three α-particles is measured directly. Preliminary results from the two approaches are presented. © 2008 IOP Publishing Ltd.
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| 4. |
- Hyldegaard, S., et al.
(författare)
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R-matrix analysis of the beta decays of 12N and 12B
- 2010
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 81:2
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Tidskriftsartikel (refereegranskat)abstract
- The β decays of 12N and 12B have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2+ strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the 12N Q-value window suggests the presence of additional 0+ and 2+ components in the 12C structure at energies above 12.7 MeV.
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| 5. |
- Kirsebom, O. S., et al.
(författare)
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Discovery of an Exceptionally Strong β -Decay Transition of F 20 and Implications for the Fate of Intermediate-Mass Stars
- 2019
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Ingår i: Physical Review Letters. - 0031-9007. ; 123:26
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Tidskriftsartikel (refereegranskat)abstract
- A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on Ne20 in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of Ne20 and F20, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood
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| 6. |
- Kirsebom, O. S., et al.
(författare)
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Measurement of the 2+→0+ ground-state transition in the β decay of F 20
- 2019
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Ingår i: Physical Review C. - 2469-9985. ; 100:6
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first detection of the second-forbidden, nonunique, 2+→0+, ground-state transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities.
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| 7. |
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| 8. |
- BERTOLOTTO, L, et al.
(författare)
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RESULTS FROM (P)OVER-BAR-P-]PHI-PHI
- 1994
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Ingår i: NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA A-NUCLEI PARTICLES AND FIELDS. - : EDITRICE COMPOSITORI BOLOGNA. ; , s. 2329-2337
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Konferensbidrag (refereegranskat)abstract
- The reaction ($) over bar pp --> phi phi is investigated in the JETSET (PS202) experiment using an internal target in LEAR. Data have been analysed at a variety of beam momenta from 1.2 GeV/c to 2.0 GeV/c, corresponding to centre-of-mass energies between
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| 9. |
- Buzzo, A, et al.
(författare)
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Search for narrow (p)over-bar-p resonances in the reaction (p)over-bar-p->(p)over-bar-p pi(+)pi(-)
- 1997
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Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 76:3, s. 475-478
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Tidskriftsartikel (refereegranskat)abstract
- The reaction (p) over bar p --> (p) over bar p pi(+)pi(-) has been studied with high statistics at CERN-LEAR with incident (p) over bar momenta from 1.65 to 2.0 GeV/c by the JETSET (PS202) experiment. The aim of this paper is to search for narrow resonanc
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Kirsebom, B. E., et al.
(författare)
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Stable cerebrospinal fluid neurogranin and beta-site amyloid precursor protein cleaving enzyme 1 levels differentiate predementia Alzheimer's disease patients
- 2022
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Ingår i: Brain Communications. - : Oxford University Press (OUP). - 2632-1297. ; 4:5
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Tidskriftsartikel (refereegranskat)abstract
- Kirsebom & Richter et al. report that levels of the CSF synapse markers neurogranin and BACE1 remain stable in Alzheimer's disease A/T/N subgroups, even when progressing to dementia. Their results suggest that CSF levels may differentiate pathomechanistic Alzheimer's disease subtypes, putatively with different options for treatment. Cerebrospinal fluid (CSF) beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), neurogranin and the neurogranin/BACE1 ratio are proposed markers for Alzheimer's disease. BACE1 is also a drug target. However, CSF levels may differ between early-stage amyloid plaque formation (A) and later stage downstream tau-tangle pathology (T) and neurodegeneration (N) and may be expressed as an A/T/N stage (e.g. A+/T-/N or A+/T+/N+). Whether BACE1 and neurogranin levels are persistent traits or change with disease progression is unknown. The aim of this study was to investigate whether CSF neurogranin and BACE1 concentrations differ between A/T/N stages, whether these change over time and correlate with memory decline. This may have implications for patient selection in future trials. We used CSF markers to determine A/T/N stage using amyloid beta42/40 ratio, p-tau181 and total-tau respectively in predementia Alzheimer's disease cases (n = 176) [including cases that progressed to dementia (n = 10)] and controls (n = 74) from the Norwegian Dementia Disease Initiation cohort. We selected cases at the presumed early (A+/T-/N-, n = 86) and late stages (A+/T+/N+, n = 90) of the Alzheimer's disease continuum and controlled with normal markers (A-/T-/N-, n = 74). A subset of subjects in all A/T/N groups underwent repeat CSF sampling at approximately 2-year intervals up to 6 years from baseline. Using linear mixed models, longitudinal measurements of CSF BACE1 and neurogranin levels in A+/T-/N- and A+/T+/N+ as compared to A-/T-/N- healthy controls were performed. Next, we measured changes in CSF BACE1 and neurogranin levels in cases that progressed from A-/T-/N- to A+/T-/N- (n = 12), from A+/T-/N- to A+/T or N+ (n = 12), remained stable A+/T-/N- (n = 26), remained stable A+/T+/N+ (n = 28) compared with controls remaining stable A-/T-/N- (n = 33). Lastly, associations between these markers and memory decline were assessed. Compared with A-/T-/N- healthy controls, neurogranin was unaltered in A+/T-/N- (n.s.) but higher in A+/T+/N+ (P < 0.0001). In contrast, BACE1 was lower in A+/T-/N- (P < 0.05) and higher in A+/T+/N+ (P < 0.0001). The neurogranin/BACE1 ratio was increased in both A+/T-/N- (P < 0.05) and A+/T+/N+ (P < 0.0001) groups as compared to A-/T-/N- healthy controls and was more strongly associated with memory decline (b = -0.29, P = 0.0006) than neurogranin (b = -0.20, P = 0.002) and BACE1 (b = -0.13, P = 0.046). Neurogranin and BACE1 level differences remained stable over time not only within A/T/N groups but also in patients progressing to more pathological A/T/N stages (e.g. progressing from A+/T-/N- to A + T or N+) and in cases progressing to dementia. Our results suggest that neurogranin and BACE1 levels may differentiate pathomechanistic Alzheimer's disease subgroups, putatively with different options for treatment.
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| 14. |
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| 15. |
- Roger, T., et al.
(författare)
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Precise Determination of the Unperturbed B8 Neutrino Spectrum
- 2012
-
Ingår i: Phys. Rev. Lett.. ; 108:16, s. Art. no. 162502-
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of the final state distribution of the 8B beta decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvaskyla [O. S.Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measuredspectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, theneutrino spectrum is for the first time directly extracted from the measured final state distribution, thusavoiding the uncertainties related to the extrapolation of R-matrix fits. Combined with the IGISOL data,this leads to an improvement of the overall errors and the extension of the neutrino spectrum at highenergy. The new unperturbed neutrino spectrum represents a benchmark for future measurements of thesolar neutrino flux as a function of energy.
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| 16. |
- Abdeldaim, Guma M. K., et al.
(författare)
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Detection of Haemophilus influenzae in respiratory secretions from pneumonia patients by quantitative real-time polymerase chain reaction
- 2009
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Ingår i: Diagnostic microbiology and infectious disease. - : Elsevier. - 0732-8893 .- 1879-0070. ; 64:4, s. 366-373
-
Tidskriftsartikel (refereegranskat)abstract
- A quantitative real-time polymerase chain reaction (PCR) based on the omp P6 gene was developed to detect Haemophilus influenzae. Its specificity was determined by analysis of 29 strains of 11 different Haemophilus spp. and was compared with PCR assays having other target genes: rnpB, 16S rRNA, and bexA. The method was evaluated on nasopharyngeal aspirates from 166 adult patients with community-acquired pneumonia. When 104 DNA copies/mL was used as cutoff limit for the method, P6 PCR had a sensitivity of 97.5% and a specificity of 96.0% compared with the culture. Of 20 culture-negative but P6 PCR-positive cases, 18 were confirmed by fucK PCR as H. influenzae. Five (5.9%) of 84 nasopharyngeal aspirates from adult controls tested PCR positive. We conclude that the P6 real-time PCR is both sensitive and specific for identification of H. influenzae in respiratory secretions. Quantification facilitates discrimination between disease-causing H. influenzae strains and commensal colonization.
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| 17. |
- Alcorta, M., et al.
(författare)
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Nuclear Structure of C-12 from Break-up Studies in Complete Kinematics
- 2009
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735407022 ; 1165, s. 27-30 461
-
Konferensbidrag (refereegranskat)abstract
- A complete kinematics study of the B-10(He-3,p alpha alpha alpha) and B-11(He-3,d alpha alpha alpha) reactions has been performed to study the multi-particle break-up of C-12 resonances above the triple-alpha threshold. Four-particle coincidence detection gives us complete information on the direction and energy of the individual alpha particles from the decay of C-12, allowing us to extract new information on the structure of C-12 which we shall present in this contribution. We have observed gamma de-excitation of the T=1 15.11 MeV resonance using charged particle detectors, and have constructed Dalitz plots of the individual resonances in C-12 using the complete kinematics information of the alpha particles which come from their break-up.
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| 18. |
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| 19. |
- Alcorta, M., et al.
(författare)
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Properties of resonances in 12C above the triple-alpha threshold
- 2011
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 312:SECTION 9, s. Art. no. 092013-
-
Konferensbidrag (refereegranskat)abstract
- A complete kinematics study of the 10B(3He, pααα) and the 11B(3He, dααα) reactions has been performed to study the multi-particle break-up of 12C resonances above the triple-alpha threshold. The values of energy and widths of some states has been improved, and in states of natural parity partial branches of decay through the ground state of 8Be have been extracted. The influence of the "ghost" of the 8Be ground state has been taken into account in order to clarify the partial branches.
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| 20. |
- Altman, S, et al.
(författare)
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Catalysis by the RNA subunit of RNase P
- 1989
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Ingår i: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 82:1, s. 63-64
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Forskningsöversikt (refereegranskat)abstract
- RNase P, an enzyme that contains both RNA and protein components, cleaves tRNA precursors to generate mature 5' termini. The catalytic activity of RNase P resides in the RNA component, with the protein cofactor affecting the rate of the cleavage reaction. The reaction is also influenced by the nature of the tRNA substrate.
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| 21. |
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| 22. |
- Borda, MG, et al.
(författare)
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Timed Up and Go in People with Subjective Cognitive Decline Is Associated with Faster Cognitive Deterioration and Cortical Thickness
- 2022
-
Ingår i: Dementia and geriatric cognitive disorders. - : S. Karger AG. - 1421-9824 .- 1420-8008. ; 51:1, s. 63-72
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Introduction:</i></b> Early markers of neurodegeneration provide an opportunity to detect, monitor, and initiate interventions in individuals who have an increased risk of developing dementia. Here, we investigated whether the Timed Up and Go (TUG) test is associated with early brain neurodegeneration and whether the TUG test could be a marker of cognitive decline in people with subjective cognitive decline (SCD). <b><i>Methods:</i></b> This is a longitudinal analysis of the Dementia Disease Initiation Study, a prospective, community-based, cohort study from Norway, designed to investigate early markers of cognitive impairment and dementia. Participants were classified as SCD and healthy controls (HC). The main studied variables were the TUG test and cognition as measured by the Mini-Mental State Examination and the Consortium to Establish a Registry for Alzheimer’s Disease memory composite score. Additionally, we investigated the cross-sectional association of brain morphology with the TUG using 1.5T-MRI. <b><i>Results:</i></b> The sample included 45 participants (SCD = 21, HC = 24) followed during a mean time of 1.50 ± 0.70 years. At baseline, the cognitive performance did not differ between the groups, but TUG was longer in SCD. Slower baseline TUG was associated with a faster cognitive decline in both groups and it was also associated with reduced cortical thickness especially in motor, executive, associative, and somatosensory cortical regions in people with SCD. <b><i>Discussion/Conclusion:</i></b> TUG predicted cognitive change in individuals with SCD, and there was a negative association between TUG and cortical thickness. TUG is a promising cheap and noninvasive marker of early cognitive decline and may help initiate interventions in individuals who have an increased risk of dementia.
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| 23. |
- Borge, M. J. G., et al.
(författare)
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Rare beta p decays in light nuclei
- 2013
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 40:3, s. art.no. 035109-
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Tidskriftsartikel (refereegranskat)abstract
- Beta-delayed proton emission may occur at very low rates in the decays of the light nuclei Be-11 and B-8. This paper explores the potential physical significance of such decays, estimates their rates and reports on first attempts to detect them: an experiment at ISOLDE/CERN gives a branching ratio for Be-11 of ( 2.5 +/- 2.5) x 10(-6) and an experiment at JYFL a 95% confidence upper limit of 2.6 x 10(-5) for B-8.
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| 24. |
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| 25. |
- Eliassen, I. V., et al.
(författare)
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Predictive and diagnostic utility of brief neuropsychological assessment in detecting Alzheimer's pathology and progression to dementia
- 2020
-
Ingår i: Neuropsychology. - : American Psychological Association (APA). - 1931-1559 .- 0894-4105. ; 34:8, s. 851-861
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the role of brief neuropsychological assessments in prediction and identification of Alzheimer's disease (AD) pathology and progression to AD dementia. Method: Adults (N = 255; range = 40-81 years) with self-reported cognitive decline underwent baseline and 2-year follow-up clinical assessment, including a brief neuropsychological screening and lumbar puncture. Five different mild cognitive impairment (MCI) algorithms were applied on baseline cognitive test results: one conventional, three amnestic (lenient, stringent, multidomain), and one comprehensive criterion. We compared predictive and diagnostic accuracy of these MCI criteria by performing logistic regression analyses and calculating diagnostic accuracy measures for 2-year outcomes of (1) clinical diagnosis of AD dementia and (2) cerebrospinal fluid biomarkers in the Alzheimer's continuum. Results: The lenient amnestic MCI criterion showed the largest effect size for predicting progression to AD dementia (OR = 13.762, 99% CI = 1.969-96.194, p = .001) and AD biomarkers (OR = 4.855, 99% CI = 1.974-11.924, p < .001) after 2 years. This criterion was sensitive for progression to dementia (sensitivity = 92.0%, specificity = 54.8%, positive likelihood ratio [LR+] = 2.03, LR- = 0.15) and showed the highest overall diagnostic accuracy for AD biomarkers (sensitivity = 72.7%, specificity = 59.1%, LR+ = 1.78, negative likelihood ratio [LR-] = 0.46). The multidomain amnestic MCI criterion produced the highest specificity for dementia (sensitivity = 76.0%, specificity = 73.0%, LR+ = 2.82, LR- = 0.33) and AD biomarkers (sensitivity = 46.8% specificity = 70.9% LR+ = 1.61, LR- = 0.75). Conclusions: Defining MCI using a brief neuropsychological battery provided limited accuracy for progression to AD dementia and cerebrospinal fluid Aβ. The lenient amnestic MCI criterion identified the highest number of individuals who progressed to clinical AD or showed biomarker pathology, but this approach included a substantial number of false positives. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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| 26. |
- Espenes, J., et al.
(författare)
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Demographically adjusted trail making test norms in a Scandinavian sample from 41 to 84 years
- 2020
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Ingår i: Clinical Neuropsychologist. - : Informa UK Limited. - 1385-4046 .- 1744-4144. ; 34:suppl. 1, s. 110-126
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Tidskriftsartikel (refereegranskat)abstract
- Objective The trail making test (TMT) is one of the most widely used neuropsychological tests. TMT-A provides measures of visual scanning/visuomotor speed and TMT-B involves additional demands on executive functions. Derived scores TMT B-A and TMT B/A enhance measures of executive functioning. However, simple B-A subtraction may lead to false estimates of executive dysfunction in clinical samples. Norms for TMT have been published in several countries but are currently lacking for Scandinavia. Methods A total of 292 healthy controls between age 41 and 84 years were included from the Norwegian "Dementia Disease Initiation" (DDI) study (n = 170) and the Gothenburg Mild Cognitive Impairment (MCI) study (n = 122). We used a regression-based procedure to develop demographically adjusted norms for basic (TMT-A and TMT-B) and derived measures (TMT B-A and B/A). We also propose a regression-based alternative to the TMT B-A measure named "TMT-beta". The proposed norms were compared to norms from Heaton et al. and Tombaugh. Results Due to differences in the estimated normative effects of demographics on performance, the proposed norms for TMT were better suited in the Scandinavian sample compared with published non-Scandinavian norms. The proposed TMT-beta measure was highly correlated to TMT B-A (r = 0.969,p < 0.001). Conclusion We here propose demographically adjusted norms for the TMT for ages 41 through 84 years based on a Scandinavian sample. We also present the regression-based derived measure TMT-beta which may resolve issues with the conventional TMT B-A measure.
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| 27. |
- Espenes, J., et al.
(författare)
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Regression-based normative data for the Rey Auditory Verbal Learning Test in Norwegian and Swedish adults aged 49-79 and comparison with published norms
- 2023
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Ingår i: Clinical Neuropsychologist. - : Informa UK Limited. - 1385-4046 .- 1744-4144. ; 37:6, s. 1276-1301
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The Rey Auditory Verbal Learning Test (RAVLT) is a widely used measure of episodic verbal memory. To our knowledge, culturally adapted and demographically adjusted norms for the RAVLT are currently not available for Norwegian and Swedish adults, and imported North American norms are often used. We here develop regression-based norms for Norwegian and Swedish adults and compare our norms to North American norms in an independent sample of cognitively healthy adults. Method: Participants were 244 healthy adults from Norway and Sweden between the aged 49 and 79 years, with between 6 and 24 years of education. Using a multiple multivariate regression-based norming procedure, we estimated effects of age, sex, and years of education on basic and derived RAVLT test scores. The newly developed norms were assessed in an independent comparison group of cognitively healthy adults (n = 145) and compared to recently published North American regression-based norms. Results: Lower age, female sex and more years of education predicted higher performance on the RAVLT. The new norms adequately adjusted for age, education, and sex in the independent comparison group. The American norms corrected for demographics on all RAVLT trials except trials 4, 7, list B, and trials 1-5 total. Test-retest (M = 2.55 years) reliability varied from poor to good. Conclusion: We propose regression-based norms for the RAVLT adjusting for pertinent demographics. The norms may be used for assessment of Norwegian and Swedish adults between the aged of 49 and 79 years, with between 6 and 24 years of education.
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| 28. |
- Evangelista, C, et al.
(författare)
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Measurement of the (p)over-barp->KsKs reaction for 0.6 to 1.9 GeV/c
- 1997
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Ingår i: PHYSICAL REVIEW D. - : AMER INST PHYSICS. - 0556-2821. ; 56:7, s. 3803-3810
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Tidskriftsartikel (refereegranskat)abstract
- The <(p)over bar p> --> KSKS --> 4 pi(+/-) cross section was measured at incident antiproton momenta between 0.6 and 1.9 GeV/c using the CERN Low Energy Antiproton Ring. This investigation was part of a systematic study of in-flight antiproton-proton anni
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| 29. |
- Evangelista, C, et al.
(författare)
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Study of the reaction (p)over-bar-p ->phi phi from 1.1 to 2.0 GeV/c
- 1998
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Ingår i: PHYSICAL REVIEW D. - : AMERICAN PHYSICAL SOC. - 0556-2821. ; 57:9, s. 5370-5381
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Tidskriftsartikel (refereegranskat)abstract
- A study has been performed of the reaction <(p)over bar p>-->4K(+/-) using in-flight antiprotons from 1.1 to 2.0 GeV/c incident momentum interacting with a hydrogen jet target. The reaction is dominated by the production of a pair of phi mesons. The <(p)o
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- IDS Collaboration, HASH(0x3dac240), et al.
(författare)
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Beta-delayed proton emission from 20Mg
- 2016
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 52:10, s. 304-
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Tidskriftsartikel (refereegranskat)abstract
- Beta-delayed proton emission from 20 Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station (IDS) setup including both charged-particle and gamma-ray detection capabilities. A total of 27 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in 20 Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State (IAS) in 20 Na is observed. This may allow studies of the 4032.9(2.4)keV resonance in 19 Ne through the beta decay of 20 Mg, which is important for the astrophysically relevant reaction 15O(?,?)19Ne. Beta-delayed protons were used to obtain a more precise value for the half-life of 20 Mg, 91.4(1.0)ms.
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| 34. |
- Jensen, E. A.M., et al.
(författare)
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Detailed study of the decay of 21Mg
- 2024
-
Ingår i: European Physical Journal A. - 1434-601X .- 1434-6001. ; 60:7
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Tidskriftsartikel (refereegranskat)abstract
- Beta-delayed proton and gamma emission in the decay of 21Mg has been measured at ISOLDE, CERN with the ISOLDE Decay Station (IDS) set-up. The existing decay scheme is updated, in particular what concerns proton transitions to excited states in 20Ne. Signatures of interference in several parts of the spectrum are used to settle spin and parity assignments to highly excited states in 21Na. The previously reported βpα branch is confirmed. A half-life of 120.5(4) ms is extracted for 21Mg. The revised decay scheme is employed to test mirror symmetry in the decay and to extract the beta strength distribution of 21Mg that is compared with theory.
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| 35. |
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| 36. |
- Kirsebom, Leif A, et al.
(författare)
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Effects of growth conditions and mutations in RNA polymerase on translational activity in vitro in Escherichia coli
- 1980
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Ingår i: Molecular General Genetics. - 0026-8925 .- 1432-1874. ; 180:1, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- The translational capacity in vitro in Escherichia coli, using RNA from phage R17 or Q beta as messenger, is several times higher if the extracts are prepared from cells harvested in early exponential phase or grown under conditions of good aeration compared to if extracts are prepared from cells harvested in a later growth phase or grown under semi-aerobic conditions. In low activity extracts the production of phage replicase protein is preferentially affected. Growth of a wild type strain under semi-aerobic conditions has a less pronounced effect on translational capacity in vitro using crude mRNA from normal or T4 infected cells or with poly(U). Mutants were fortuitously found which did not show a lowered translational activity in vitro as a result of entering late phase of growth. Two of these were changed in RNA polymerase. Two different translational inhibitors can be demonstrated in the ribosomal wash fraction obtained from semi-aerobically grown wild type cells, whereas only one was found in the case of aerobically grown cells. The low translational activity of semi-aerobically grown cells in vitro is implied to be dependent on the induction or activation of a translational inhibitor. It behaves like a protein but is not likely to be a protease or RNAse.
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| 37. |
- Kirsebom, O. S., et al.
(författare)
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Breakup of 12C resonances into three α particles
- 2010
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 81:6
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Tidskriftsartikel (refereegranskat)abstract
- The reaction He-3 + B-11 -> d + C-12* has been used to populate resonances in C-12 up to an excitation energy of 15 MeV. The subsequent breakup to three alpha particles has been measured in complete kinematics. Dalitz plots are used to visualize and analyze the data. The Dalitz plot intensity distribution exhibits zero points characteristic of the total spin and parity of the 3 alpha system allowing us to determine the spin and parity of a state in C-12 at 13.35 MeV whose quantum numbers were hitherto not well established. The Dalitz plot intensity distributions of the 2(-) state at 11.83 MeV and the 1(+) state at 12.71 MeV are compared with the predictions of a recent three-body calculation as well as with simpler models. All are able to reproduce the gross structures seen in the Dalitz plot, but none give an accurate description of the detailed profile of the distributions.
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| 38. |
- Kirsebom, O. S., et al.
(författare)
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First Accurate Normalization of the β -delayed α Decay of N 16 and Implications for the C 12 (α,γ) O 16 Astrophysical Reaction Rate
- 2018
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 121:14
-
Tidskriftsartikel (refereegranskat)abstract
- Published by the American Physical Society. The C12(α,γ)O16 reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced α width, γ11, of the bound 1- level in O16 is particularly important to determine the cross section. The magnitude of γ11 is determined via sub-Coulomb α-transfer reactions or the β-delayed α decay of N16, but the latter approach is presently hampered by the lack of sufficiently precise data on the β-decay branching ratios. Here we report improved branching ratios for the bound 1- level [bβ,11=(5.02±0.10)×10-2] and for β-delayed α emission [bβα=(1.59±0.06)×10-5]. Our value for bβα is 33% larger than previously held, leading to a substantial increase in γ11. Our revised value for γ11 is in good agreement with the value obtained in α-transfer studies and the weighted average of the two gives a robust and precise determination of γ11, which provides significantly improved constraints on the C12(α,γ) cross section in the energy range relevant to hydrostatic He burning.
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| 39. |
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| 40. |
- Kirsebom, O. S., et al.
(författare)
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Improved Limit on Direct α Decay of the Hoyle State
- 2012
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 108:20, s. 202501-
-
Tidskriftsartikel (refereegranskat)abstract
- The current evaluation of the triple-α reaction rate assumes that the α decay of the 7.65 MeV, 0+ state in 12C, commonly known as the Hoyle state, proceeds sequentially via the ground state of 8Be. This assumption is challenged by the recent identification of two direct α-decay branches with a combined branching ratio of 17(5)%. If correct, this would imply a corresponding reduction in the triple-α reaction rate with important astrophysical consequences. We have used the 11B(3He,d) reaction to populate the Hoyle state and measured the decay to three α particles in complete kinematics. We find no evidence for direct α-decay branches, and hence our data do not support a revision of the triple-α reaction rate. We obtain an upper limit of 5×10-3 on the direct α decay of the Hoyle state at 95% C.L., which is 1 order of magnitude better than a previous upper limit.
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| 41. |
- Kirsebom, O. S., et al.
(författare)
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Observation of gamma-delayed 3 alpha breakup of the 15.11 and 12.71 MeV states in C-12
- 2009
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 680:1, s. 44-49
-
Tidskriftsartikel (refereegranskat)abstract
- The reactions B-10(He-3, p alpha alpha alpha) at 4.9 MeV and B-11(He-3, d alpha alpha alpha) at 8.5 MeV have been used to investigate the gamma decay of states in C-12. By measuring the four-body final state in complete kinematics we are able to detect gamma transitions indirectly. We find gamma transitions from the 15.11 MeV state in C-12 to the 12.71, 11.83, 10.3 and 7.65 MeV states followed by their breakup into three alpha particles. The relative gamma-ray branching ratios obtained are (1.2 +/- 0.3), (0.32 +/- 0.12), (1.4 +/- 0.2) and (4.4 +/- 0.8)%, respectively, with the remaining (92.7 +/- 1.0)% of the gamma decays going to the bound states. We obtain Gamma(alpha)/Gamma = (2.8 +/- 1.2)% for the isospinforbidden alpha decay of the 15.11 MeV state. From the 12.71 MeV state we find gamma transitions to the 10.3 and 7.65 MeV states. The relative gamma-ray branching ratios are (0.9(-0.5)(+0.6)) and (2.6(-1.2)(+1.6))%, respectively, with the remaining (96.6(-1.3)(+1.7))% of the gamma decays going to the bound states. Finally. we discuss the relation between the beta decay of N-12 and B-12 to states in C-12 and the gamma decay of the 15.11 MeV analog in C-12 to the same states. (C) 2009 Elsevier B.V. All rights reserved.
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| 42. |
- Kirsebom, O. S., et al.
(författare)
-
Precise and accurate determination of the B-8 decay spectrum
- 2011
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 83:6
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate measurements of the B-8 neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the B-8 neutrino spectrum can be obtained from the measurement of the beta-delayed alpha spectrum. We report on an alpha-alpha coincidence measurement performed at the IGISOL facility in Jyvaskyla, Finland. Our measurement allows extensive cross-checks to be performed and gives a more intense neutrino spectrum at high energies compared to the present standard. The deviation reaches 4% at the end point of the spectrum. Below 11 MeV, the deviation is less than 1%.
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| 43. |
- Kirsebom, O. S., et al.
(författare)
-
The 8B neutrino spectrum
- 2010
-
Ingår i: 11th Symposium on Nuclei in the Cosmos, NIC 2010; Heidelberg; Germany; 19 July 2010 through 23 July 2010. - 1824-8039.
-
Konferensbidrag (refereegranskat)abstract
- Knowledge of the energy spectrum of the neutrinos emitted in the β decay of8B in the Sun is needed to interpret the neutrino spectrum measured on Earth. Experimentally, the 8B neutrino spectrum may be αextracted from the measurement of the β -delayed a spectrum. In this contribution, the results of a recent α-α coincidence measurement are presented and compared to previous measurements. The implications for the neutrino spectrum are clarified.
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| 44. |
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| 45. |
- Madurga, M., et al.
(författare)
-
Evidence of a new state in Be-11 observed in the Li-11 beta-decay
- 2009
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 677:5, s. 255-259
-
Tidskriftsartikel (refereegranskat)abstract
- Coincidences between charged particles emitted in the beta-decay of Li-11 were observed using highly segmented detectors. The breakup channels involving three particles were Studied in full kinematics allowing for the reconstruction of the excitation energy of the Be-11 states participating in the decay. In particular, the contribution of a previously unobserved state at 16.3 MeV in Be-11 has been identified selecting the alpha + He-7 -> alpha + He-6 + n channel. The angular correlations between the alpha particle and the center of mass of the He-6 + n system favors spin and parity assignment of 3/2(-) for this state as well as for the previously known state at 18 MeV. (C) 2009 Elsevier B.V. All rights reserved.
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| 46. |
- Madurga, M., et al.
(författare)
-
Kinematic identification of the t branch in the decay of 11Li
- 2009
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 42:3, s. 415-419
-
Tidskriftsartikel (refereegranskat)abstract
- The -delayed 8 Li + t branch of the 11Li decay was identified via kinematical analysis of the charged particles observed in coincidence. The back-to-back events observed in a narrow angular acceptance were compared to a Monte Carlo simulation. The 8 Li + t sum energy spectrum was fitted assuming that the decay occurs through an intermediate state in 11Be . The resulting energy centroid and full-width half maximum for the intermediate state are 18.35(30)MeV and 1.5(4)MeV, respectively. The -delayed 8 Li + t branching ratio obtained from the coincidence spectrum, BR t = 0.93(8)×10-4 , is in agreement with previous measurements but more precise.
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| 47. |
- Mao, Guanzhong, et al.
(författare)
-
Cleavage of Model Substrates by Arabidopsis thaliana PRORP1 Reveals New Insights into Its Substrate Requirements
- 2016
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
-
Tidskriftsartikel (refereegranskat)abstract
- Two broad classes of RNase P trim the 5' leader of precursor tRNAs (pre-tRNAs): ribonucleoprotein (RNP)- and proteinaceous (PRORP)-variants. These two RNase P types, which use different scaffolds for catalysis, reflect independent evolutionary paths. While the catalytic RNA-based RNP form is present in all three domains of life, the PRORP family is restricted to eukaryotes. To obtain insights on substrate recognition by PRORPs, we examined the 5' processing ability of recombinant Arabidopsis thaliana PRORP1 (AtPRORP1) using a panel of pre-tRNA(Ser) variants and model hairpin-loop derivatives (pATSer type) that consist of the acceptor-T-stem stack and the T-/D-loop. Our data indicate the importance of the identity of N-1 (the residue immediately 5' to the cleavage site) and the N-1: N+73 base pair for cleavage rate and site selection of pre-tRNA(Ser) and pATSer. The nucleobase preferences that we observed mirror the frequency of occurrence in the complete suite of organellar pre-tRNAs in eight algae/plants that we analyzed. The importance of the T-/D-loop in pre-tRNA(Ser) for tight binding to AtPRORP1 is indicated by the 200-fold weaker binding of pATSer compared to pre-tRNA(Ser), while the essentiality of the T-loop for cleavage is reflected by the near-complete loss of activity when a GAAA-tetraloop replaced the T-loop in pATSer. Substituting the 2'-OH at N-1 with 2'-H also resulted in no detectable cleavage, hinting at the possible role of this 2'-OH in coordinating Mg2+ ions critical for catalysis. Collectively, our results indicate similarities but also key differences in substrate recognition by the bacterial RNase P RNP and AtPRORP1: while both forms exploit the acceptor-T-stem stack and the elbow region in the pre-tRNA, the RNP form appears to require more recognition determinants for cleavage-site selection.
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| 48. |
- Marroquin, I., et al.
(författare)
-
MULTI-PARTICLE EMISSION FROM Ar-31 AT ISOLDE
- 2016
-
Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 47:3, s. 747-754
-
Tidskriftsartikel (refereegranskat)abstract
- A multi-particle decay experiment was successfully performed at the ISOLDE Decay Station. In this new permanent station, devoted to beta-decay studies, the novel MAGISOL Si-Plugin Chamber was installed to study the exotic decay modes of the proton drip-line nucleus Ar-31. The motivation was to search for beta 3p and beta 3p gamma channels, as well as to provide information on resonances in S-30 and P-29 relevant for the astrophysical rp-process. Description of the experimental set-up and preliminary results are presented.
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| 49. |
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| 50. |
- Tengblad, Olof, 1957, et al.
(författare)
-
12C formation: A classical quest in new light
- 2011
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735409378 ; 1377, s. 270-274
-
Konferensbidrag (refereegranskat)abstract
- In this work we have studied the break‐up of 12C following the reactions 10B(3He,pααα) and 11B(3He,dααα). The study was performed at the 5 MV tandem in Madrid. The break‐up gives us information on excited states in 12C from the famous Hoyle state up to an energy of almost 18 MeV. Using a highly segmented experimental set‐up the simultaneous detection of the three alpha particles in coincidence with a proton or deuteron respectively made possible a full kinematic reconstruction of the break‐up. On the basis of the energies of the 3 α particles and their angular correlations it has been possible to determine the spin and parity of states for cases in which the assignment has been doubtful. Some of these levels will also de‐excite via electromagnetic emission. The comparison between the energy of proton that populate a state of 12C and the sum of the energies of the 3α emitted from the same state makes possible to determine the presence of electromagnetic disintegration (γ) to lower states within 12C followed by the 3α break‐up.
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