| 11. |
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| 12. |
- Alsmeyer, H, et al.
(författare)
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Ex-vessel core melt stabilization research (ECOSTAR)
- 2005
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Ingår i: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 235:2-4, s. 271-284
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Tidskriftsartikel (refereegranskat)abstract
- The project on ex-vessel core melt stabilization research (ECOSTAR) started in January 2000 to be concluded by end of 2003. The project is performed by 14 partner institutions from five European countries and involves a large number of experiments with low- and high-temperature simulant melts and real corium at different scales. Model development and scaling analysis allows application of the research results to existing and to future LWRs in the area of reactor design and accident mitigation. The project is oriented toward the analysis and mitigation of severe accident sequences that could occur in the ex-vessel phase of a postulated core melt accident. The issues are: (1) the release of melt form the pressure vessel, (2) the transfer and spreading of the melt on the basement, (3) the analysis of the physical-chemical processes that are important for corium behavior especially during concrete erosion with onset of solidification, and (4) stabilization of the melt by cooling through direct water contact. The results achieved so far resolve a number of important issues: the amount of melt that could be transferred at RPV failure from the RPV into the containment can be substantially reduced by lowering the residual pressure in the primary circuit. It is found that melt dispersion also strongly depends on the location of the RPV failure, and that lateral failure results in substantially less melt dispersion. During melt release, the impinging melt jet could erode parts of the upper basement surface. Jet experiments and a derived heat transfer relation allow estimation of its contribution to concrete erosion. Spreading of the corium melt on the available basement surface is an important process, which defines the initial conditions for concrete attack or for the efficiency of cooling in case of water contact, respectively. Validation of the spreading codes based on a large-scale benchmark experiment is underway and will allow determination of the initial conditions, for which a corium melt can be assumed to spread homogeneously over the available surface. Experiments with UO(2)-based corium melts highlight the role of phase segregation during onset of melt solidification and during concrete erosion. To cool the spread corium melt, the efficacy of top flooding and bottom flooding is investigated in small-scale and in large-scale experiments, supported by model developments. Project assessment is continuing to apply the results to present and future reactors.
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| 13. |
- 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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| 14. |
- 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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| 15. |
- Belyaev, IY, et al.
(författare)
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Exposure of rat brain to 915 MHz GSM microwaves induces changes in gene expression but not double stranded DNA breaks or effects on chromatin conformation
- 2006
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Ingår i: Bioelectromagnetics. - : Wiley. - 0197-8462 .- 1521-186X. ; 27:4, s. 295-306
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether exposure of rat brain to microwaves (MWs) of global system for mobile communication (GSM) induces DNA breaks, changes in chromatin conformation and in gene expression. An exposure installation was used based on a test mobile phone employing a GSM signal at 915 MHz, all standard modulations included, output power level in pulses 2 W, specific absorption rate (SAR) 0.4 mW/g. Rats were exposed or sham exposed to MWs during 2 h. After exposure, cell suspensions were prepared from brain samples, as well as from spleen and thymus. For analysis of gene expression patterns, total RNA was extracted from cerebellum. Changes in chromatin conformation, which are indicative of stress response and genotoxic effects, were measured by the method of anomalous viscosity time dependencies (AVTD). DNA double strand breaks (DSBs) were analyzed by pulsed-field gel electrophoresis (PFGE). Effects of MW exposure were observed on neither conformation of chromatin nor DNA DSBs. Gene expression profiles were obtained by Affymetrix U34 GeneChips representing 8800 rat genes and analyzed with the Affymetrix Microarray Suite (MAS) 5.0 software. In cerebellum from all exposed animals, I I genes were upregulated in a range of 1.34-2.74 fold and one gene was downregulated 0.48-fold (P <.0025). The induced genes encode proteins with diverse functions including neurotransmitter regulation, blood-brain barrier (BBB), and melatonin production. The data shows that GSM MWs at 915 MHz did not induce PFGE-detectable DNA double stranded breaks or changes in chromatin conformation, but affected expression of genes in rat brain cells. Bioelectromagnetics 27:295-306, 2006. (c) 2006 Wiley-Liss, Inc.
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| 16. |
- 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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| 17. |
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| 18. |
- Einarsson, U, et al.
(författare)
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Activities of daily living and social activities in people with multiple sclerosis in Stockholm County
- 2006
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Ingår i: Clinical rehabilitation. - : SAGE Publications. - 0269-2155 .- 1477-0873. ; 20:6, s. 543-551
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To describe independence in personal and instrumental activities of daily living (ADL), and frequency of social/lifestyle activities in a population-based sample of people with multiple sclerosis in Stockholm. Design: Population-based survey. Setting: Data collection in home environment. Subjects: One hundred and sixty-six people with multiple sclerosis. Interventions: Data were collected using measurements and structured interviews. Main measures: Independence in ADL was assessed by the Barthel Index; independence in personal and instrumental ADL by the Katz Extended ADL Index; and frequency of social/lifestyle activities by the Frenchay Activities Index. Results: The mean age was 519 ± 12 years in the included 166 people with multiple sclerosis, of whom 71% ( n = 118) were women. Fifty-two per cent ( n = 85) were independent in personal ADL, 30% ( n = 50) in instrumental ADL, and 35% ( n = 57) had normal frequency of social/lifestyle activities. Most frequently affected ADL items were cleaning indoors and outdoors transportation (62%, n = 102) and the social/lifestyle items of household maintenance (59%, n = 97), walking outside (59%, n = 97), heavy housework (61%, n = 100), and gardening (68%, n = 112). Conclusions: ADL and social/lifestyle activities were affected in two-thirds of people with multiple sclerosis in Stockholm. The most affected items were items that could be classified as mobility-related and physically demanding, underlining the importance of developing and using evidence-based exercise treatments and rehabilitation to increase independence in people with multiple sclerosis in Stockholm.
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| 19. |
- Einarsson, U, et al.
(författare)
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Cognitive and motor function in people with multiple sclerosis in Stockholm County
- 2006
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Ingår i: Multiple sclerosis (Houndmills, Basingstoke, England). - : SAGE Publications. - 1352-4585 .- 1477-0970. ; 12:3, s. 340-353
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyse cognitive and motor function in a population-based sample of people with multiple sclerosis (PwMS), taking into account both disease-related data and sociodemographic factors. Data were collected from 166 PwMS during home visits. Cognitive function was assessed by the Mini-Mental State Examination (MMSE), the Free Recall and Recognition of 12 Random Words Test (FRR12RWT), and the Symbol Digit Modalities Test (SDMT); manual dexterity by the Nine-Hole Peg Test (NHPT); global motor capacity by the Lindmark Motor Capacity Assessment; and walking capacity by a timed 10-metre walk. On cognitive tests, 55% (MMSE), 84% (FRR12RWT), and 45% (SDMT) of PwMS scored within the normal range; 27% of PwMS displayed normal manual dexterity, 9% had a maximal motor-capacity score, and 8% walked at normal speed. Factors associated with normal cognitive function were lower disability and higher education; lower disability and current employment were predictive of capacity to perform the NHPT and to walk 10 metres. In conclusion, cognitive function was normal in approximately half of the PwMS investigated, while a minority displayed normal manual dexterity and normal walking capacity. Thus, both disease severity and socio-demographic factors appear to influence cognitive and motor function in MS.
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| 20. |
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