226 research outputs found

    DIRECT MEASUREMENTS OF TOTAL REACTION CROSS SECTIONS BETWEEN HEAVY IONS FROM 10 TO 100 MeV/amu : PRELIMINARY CONCLUSIONS

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    After a review of some theoretical formulations of the concept of total reaction cross σR, involving low energy (≤ 10 MeV/amu) and high energy (> GeV/amu) models, two experimental methods used for direct measurements of σR, are presented, namely the "beam attenuation" and the "associated γ-rays 4 π detection" methods. Then a number of experimental results of σR in the Fermi energy range is given and the data are compared on the one hand with the predictions of the "low energy" BASS model (assuming a classical one-dimensional nucleus-nucleus potential interaction), and on the other hand with the predictions of a "high-energy" microscopic calculation performed using the formalism of KAROL (assuming that nuclear reactions are produced by individual nucleon-nucleon interactions). Finally, some experimental and theoretical problems are discussed and general conclusions are tentatively proposed

    Ferromagnetic effect and spin assignment for the 390 keV state in 62Cu

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    The 390 keV isomeric state of 62Cu is assigned as Jπ = 4+. The magnetic hyperfine interaction has been observed in the 60Ni(α, pnγ) 62Cu reaction and the deduced Larmor period is consistent with known values of g and the hyperfine field of Cu in Ni

    Characteristics of the injected ion beam in the ECR charge breeder 1+n+1^{+}\to n^{+}

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    Different ion species (rare gases, alkali, metallic) have been injected on the axis of the MINIMAFIOS - 10 GHz - Electron Cyclotron Resonance Ion Source which is the basics of the 1+ -> n+ method, special attention have been paid to the optics of the incoming beam for the validation of the 1+ -> n+ method for the SPIRAL project (Radioactive Ion Beam facility). The capture of the incoming ion beam by the ECR plasma depends, first, on the relative energy of the incoming ions with respect to the average ion energy in the plasma, and secondly, on the optics of the injection line. The efficiency of the process when varying the potential V n+ of the MINIMAFIOS source with respect to the potential V 1+ applied to the 1+ source (DV=V n+ -V 1+ ) is an image of the energy dispersion of the 1+ beam. 1+ -> n+ spectra efficiencies, DV efficiency dependence for the most efficient charge state obtained, and measured primary beam emittances are given for the Ar, Rb, Pb, Cr. Highest efficiencies obtained are respectively Ar1+ -> Ar8+ : 8.7 %, Rb1+ -> Rb15+ : 5.5 %, Pb 1+ -> Pb 22+ : 4.8 % , Cr 1+ -> Cr 12+ : 3.5 %. Last results obtained are given for Sulfur and Uranium

    Malnutrition impact on stroke outcome: an analysis of a patient cohort 3 months after recanalization treatment

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    Background: Malnutrition is thought to affect 30% to 70% of hospitalized patients. Little is known about consequences of undernutrition during the acute phase of stroke. We would like to assess the impact of pre-infarction malnutrition on stroke patients treated with thrombolysis and/ or thrombectomy. Material and methods: We performed a retrospective observational study on a cohort of stroke patients who benefited from thrombolysis and/ or thrombectomy during 2015 in Saint Joseph Hospital’s Stroke Unit. The main objective of our research was to observe the clinical course of undernourished patients compared to the non-undernourished ones, using the NIHSS score at the stroke unit discharged and the 3 months modified Rankin score. Undernutrition was defined by a body mass index of (BMI) ≤ 21. Results: A total of 81 patients with thrombolysis and/or thrombectomy treatment were included. The median BMI in < 70-year-old patients was 24.5 and 25 in > 70-year-old patients. Initial severity measured by baseline NIHSS score was comparable among the undernourished and non-undernourished patients. Undernourished patients over 70 had a more severe neurological state at discharge (NIHSS 8.5 versus 3.9, NS) and were more disabled 3 months after discharge (Rankin 3.1 versus 2, NS). Conclusions: Undernutrition prior to stroke seems to have an impact on the functional prognosis of cerebral infarction, especially in patients > 70 years of age. Lack of significant results may be explained by the limited statistical means. A complementary study with a larger cohort is planned in order to assess this hypothesis

    High Current, High frequency ECRIS development program for LHC heavy ion beam application

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    A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb27+, with length and repetition ratecompatible with those desired by CERN (1 mAe / 400 ms / 10 Hz in the context of future heavy ion collisions at LHC) is organised in acollaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNG.Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHzgyrotron, (ii) tests on a non-superconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC hasborrowed from CEA a 28 GHz - 10 kW gyrotron transmitter.The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequencyof about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of thepresent ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of thesource), and with a plasma volume up to 2.5 larger.Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will bevaried so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as thosewhich can be produced by conventional magnets (less than 2 T axial field at injection - far from the 28 GHz High-B mode)

    Needle syringe programmes and opioid substitution therapy for preventing hepatitis C transmission in people who inject drugs.

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    BACKGROUND: Needle syringe programmes and opioid substitution therapy for preventing hepatitis C transmission in people who inject drugsNeedle syringe programmes (NSP) and opioid substitution therapy (OST) are the primary interventions to reduce hepatitis C (HCV) transmission in people who inject drugs. There is good evidence for the effectiveness of NSP and OST in reducing injecting risk behaviour and increasing evidence for the effectiveness of OST and NSP in reducing HIV acquisition risk, but the evidence on the effectiveness of NSP and OST for preventing HCV acquisition is weak. OBJECTIVES: To assess the effects of needle syringe programmes and opioid substitution therapy, alone or in combination, for preventing acquisition of HCV in people who inject drugs. SEARCH METHODS: We searched the Cochrane Drug and Alcohol Register, CENTRAL, the Cochrane Database of Systematic Reviews (CDSR), the Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment Database (HTA), the NHS Economic Evaluation Database (NHSEED), MEDLINE, Embase, PsycINFO, Global Health, CINAHL, and the Web of Science up to 16 November 2015. We updated this search in March 2017, but we have not incorporated these results into the review yet. Where observational studies did not report any outcome measure, we asked authors to provide unpublished data. We searched publications of key international agencies and conference abstracts. We reviewed reference lists of all included articles and topic-related systematic reviews for eligible papers. SELECTION CRITERIA: We included prospective and retrospective cohort studies, cross-sectional surveys, case-control studies and randomised controlled trials that measured exposure to NSP and/or OST against no intervention or a reduced exposure and reported HCV incidence as an outcome in people who inject drugs. We defined interventions as current OST (within previous 6 months), lifetime use of OST and high NSP coverage (regular attendance at an NSP or all injections covered by a new needle/syringe) or low NSP coverage (irregular attendance at an NSP or less than 100% of injections covered by a new needle/syringe) compared with no intervention or reduced exposure. DATA COLLECTION AND ANALYSIS: We followed the standard Cochrane methodological procedures incorporating new methods for classifying risk of bias for observational studies. We described study methods against the following 'Risk of bias' domains: confounding, selection bias, measurement of interventions, departures from intervention, missing data, measurement of outcomes, selection of reported results; and we assigned a judgment (low, moderate, serious, critical, unclear) for each criterion. MAIN RESULTS: We identified 28 studies (21 published, 7 unpublished): 13 from North America, 5 from the UK, 4 from continental Europe, 5 from Australia and 1 from China, comprising 1817 incident HCV infections and 8806.95 person-years of follow-up. HCV incidence ranged from 0.09 cases to 42 cases per 100 person-years across the studies. We judged only two studies to be at moderate overall risk of bias, while 17 were at serious risk and 7 were at critical risk; for two unpublished datasets there was insufficient information to assess bias. As none of the intervention effects were generated from RCT evidence, we typically categorised quality as low. We found evidence that current OST reduces the risk of HCV acquisition by 50% (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.40 to 0.63, I(2) = 0%, 12 studies across all regions, N = 6361), but the quality of the evidence was low. The intervention effect remained significant in sensitivity analyses that excluded unpublished datasets and papers judged to be at critical risk of bias. We found evidence of differential impact by proportion of female participants in the sample, but not geographical region of study, the main drug used, or history of homelessness or imprisonment among study samples.Overall, we found very low-quality evidence that high NSP coverage did not reduce risk of HCV acquisition (RR 0.79, 95% CI 0.39 to 1.61) with high heterogeneity (I(2) = 77%) based on five studies from North America and Europe involving 3530 participants. After stratification by region, high NSP coverage in Europe was associated with a 76% reduction in HCV acquisition risk (RR 0.24, 95% CI 0.09 to 0.62) with less heterogeneity (I(2) =0%). We found low-quality evidence of the impact of combined high coverage of NSP and OST, from three studies involving 3241 participants, resulting in a 74% reduction in the risk of HCV acquisition (RR 0.26 95% CI 0.07 to 0.89). AUTHORS' CONCLUSIONS: OST is associated with a reduction in the risk of HCV acquisition, which is strengthened in studies that assess the combination of OST and NSP. There was greater heterogeneity between studies and weaker evidence for the impact of NSP on HCV acquisition. High NSP coverage was associated with a reduction in the risk of HCV acquisition in studies in Europe

    Cognitive reserve and Alzheimer's disease biomarkers are independent determinants of cognition

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    The objective of this study was to investigate how a measure of educational and occupational attainment, a component of cognitive reserve, modifies the relationship between biomarkers of pathology and cognition in Alzheimer's disease. The biomarkers evaluated quantified neurodegeneration via atrophy on magnetic resonance images, neuronal injury via cerebral spinal fluid t-tau, brain amyloid-β load via cerebral spinal fluid amyloid-β1–42 and vascular disease via white matter hyperintensities on T2/proton density magnetic resonance images. We included 109 cognitively normal subjects, 192 amnestic patients with mild cognitive impairment and 98 patients with Alzheimer's disease, from the Alzheimer's Disease Neuroimaging Initiative study, who had undergone baseline lumbar puncture and magnetic resonance imaging. We combined patients with mild cognitive impairment and Alzheimer's disease in a group labelled ‘cognitively impaired’ subjects. Structural Abnormality Index scores, which reflect the degree of Alzheimer's disease-like anatomic features on magnetic resonance images, were computed for each subject. We assessed Alzheimer's Disease Assessment Scale (cognitive behaviour section) and mini-mental state examination scores as measures of general cognition and Auditory–Verbal Learning Test delayed recall, Boston naming and Trails B scores as measures of specific domains in both groups of subjects. The number of errors on the American National Adult Reading Test was used as a measure of environmental enrichment provided by educational and occupational attainment, a component of cognitive reserve. We found that in cognitively normal subjects, none of the biomarkers correlated with the measures of cognition, whereas American National Adult Reading Test scores were significantly correlated with Boston naming and mini-mental state examination results. In cognitively impaired subjects, the American National Adult Reading Test and all biomarkers of neuronal pathology and amyloid load were independently correlated with all cognitive measures. Exceptions to this general conclusion were absence of correlation between cerebral spinal fluid amyloid-β1–42 and Boston naming and Trails B. In contrast, white matter hyperintensities were only correlated with Boston naming and Trails B results in the cognitively impaired. When all subjects were included in a flexible ordinal regression model that allowed for non-linear effects and interactions, we found that the American National Adult Reading Test had an independent additive association such that better performance was associated with better cognitive performance across the biomarker distribution. Our main conclusions included: (i) that in cognitively normal subjects, the variability in cognitive performance is explained partly by the American National Adult Reading Test and not by biomarkers of Alzheimer's disease pathology; (ii) in cognitively impaired subjects, the American National Adult Reading Test, biomarkers of neuronal pathology (structural magnetic resonance imaging and cerebral spinal fluid t-tau) and amyloid load (cerebral spinal fluid amyloid-β1–42) all independently explain variability in general cognitive performance; and (iii) that the association between cognition and the American National Adult Reading Test was found to be additive rather than to interact with biomarkers of Alzheimer's disease pathology

    Cognitive Reserve and the Prevention of Dementia: the Role of Physical and Cognitive Activities

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    Purpose of Review: The article discusses the two most significant modifiable risk factors for dementia, namely, physical inactivity and lack of stimulating cognitive activity, and their effects on developing cognitive reserve. Recent Findings: Both of these leisure-time activities were associated with significant reductions in the risk of dementia in longitudinal studies. In addition, physical activity, particularly aerobic exercise, is associated with less age-related gray and white matter loss and with less neurotoxic factors. On the other hand, cognitive training studies suggest that training for executive functions (e.g., working memory) improves prefrontal network efficiency, which provides support to brain functioning in the face of cognitive decline. Summary: While physical activity preserves neuronal structural integrity and brain volume (hardware), cognitive activity strengthens the functioning and plasticity of neural circuits (software), thus supporting cognitive reserve in different ways. Future research should examine whether lifestyle interventions incorporating these two domains can reduce incident dementia

    Le modèle canadien à l'épreuve des années 1980

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    Like many former colonies, Canada has been looking for an identity distinct from its two mother-countries, France and the United Kingdom, but above all from its overpowering neighbor to the south, the United States. This obsessive quest for identity led, during the 1970s, to the creation of a bilingual and multicultural social-democracy. Yet hardly was this model defined when it was faced with the political and constitutional turmoil of the 1980s: a series of agreements and referendums endeavored to meet the various claims of Québec separatists, native populations, and the western provinces, all of whom questioned the federal structure. The first part of the study traces the difficult construction of the Canadians’ self-image and confronts it with the perception of foreign observers (limited to the three countries mentioned above). An analysis of the representation of Canada as it appears in a selection of the French, British and American weekly press then follows the evolution of this complex mirror game during the 1980s, whose impact on the Canadian image was minor yet perceptible. The rhetorical systems and projections of the nineteenth century linger on, but the model of a federation allowing peaceful coexistence between ethnic groups seems to have suffered from the turbulent decade and to have given way to a model of political experimentation and democratic debate. The portrait tells as much about the artist as about the subject: the observers' discourse on Canada is revealing of their own self-images and their continuing ideological debate about the vocation of the new world.Comme de nombreux pays jeunes et longtemps sous domination coloniale, le Canada se cherche une identité qui le distingue à la fois des deux anciennes mères-patries, la France et le Royaume-Uni, mais aussi et surtout de son encombrant voisin, la toute-puissante république américaine. Sa quête ontologique lancinante semble depuis la fin des années 1960 s'être cristallisée autour du modèle d'une sociale-démocratie bilingue et multiculturelle; mais à peine esquissé, ce modèle a été confronté de plein fouet aux bouleversements politiques et constitutionnels de la décennie 1980, émaillée d'accords et de referendums visant à répondre à la remise en question du fédéralisme canadien par les indépendantistes québécois, les provinces de l'ouest et les autochtones. Après avoir retracé la construction difficile de cette image nationale et l'avoir confrontée au regard des observateurs étrangers (limités aux trois pays évoqués ci-dessus), l'étude s'attache à suivre l'évolution de ce jeu de miroirs à travers le vecteur d'une sélection de la presse française, britannique et américaine. L’analyse des représentations du canada véhiculées par ces puissants diffuseurs d'images révèle la permanence de systèmes rhétoriques et de projections hérités du siècle dernier - comme le cliché d'un Québec "bouffée de France" ou la perception d'un Canada pâle copie des États-Unis - mais également la transformation d'un modèle de coexistence harmonieuse des peuples en paradigme de débat démocratique et d'expérimentation politique. Le portrait en dit cependant tout autant sur l'artiste que sur le sujet : le Canada agit en effet comme révélateur des propres représentations nationales des observateurs et demeure le théâtre d'affrontements idéologiques sur la vocation du nouveau monde
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