63 research outputs found

    Near-barrier Fusion Induced by Stable Weakly Bound and Exotic Halo Light Nuclei

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    The effect of breakup is investigated for the medium weight 6^{6}Li+59^{59}Co system in the vicinity of the Coulomb barrier. The strong coupling of breakup/transfer channels to fusion is discussed within a comparison of predictions of the Continuum Discretized Coupled-Channels model which is also applied to 6^{6}He+59^{59}Co a reaction induced by the borromean halo nucleus 6^{6}He.Comment: 6 pages, 3 figures. A talk given at the FUSION06: International Conference on Reaction Mechanisms and Nuclear Structure at the Coulomb barrier, March 19-23, 2006, San Servolo, Venezia, Ital

    Local Observations of Climate Change and Adaptation Responses: A Case Study in the Mountain Region of Burundi-Rwanda

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    Mountain regions and their communities are particularly vulnerable to climate change impacts. However, little is known on the impacts observed and adaptation responses used in Burundi’s mountain region and if these are different to those reported in the contiguous mountain region of Rwanda. This paper aims to fill in these knowledge gaps. Semi-structured interviews were conducted with 300 smallholder farmers, 150 in northern Burundi and 150 in southern Rwanda. Farmers in both countries reported negative impacts on crops, animals, and human health, with small differences between countries driven by the main cultivated crops. More adaptation strategies were used in Burundi than in Rwanda, and more farmers in Burundi were using multiple strategies. In both countries, farmers’ wealth affected farmers’ adaptation responses and their food security. Notably, for all wealth groups (poor, average, rich), food security was lower in Rwanda than in Burundi. We relate our findings to current agricultural intensification policies in both countries and argue for the greater involvement of local farmers in adaptation planning using, for example, science-with-society approaches.We are deeply grateful to our study participants, who graciously shared their time, energy, and stories. We thank our field assistants and facilitators for making this research possible. We also acknowledge the Mountain Research Initiative for funding support

    Study of Deformation Effects in the Charged Particle Emission from 46Ti

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    The 46Ti compound nucleus, as populated by the fusion-evaporation reaction 27Al + 19F at the bombarding energy of 144 MeV, has been investigated by charged particle spectroscopy using the multidetector array ICARE at the VIVITRON tandem facility of the IReS (Strasbourg). The light charged particles have been measured in coincidence with evaporation residues. The CACARIZO code, a Monte Carlo implementation of the statistical-model code CASCADE, has been used to calculate the spectral shapes of evaporated alpha-particles which are compared with the experimental spectra. This comparison indicates the possible signature of large deformations of the compound nucleus.Comment: 6 pages, 4 figures, Proceedings od the Zakopane 20004 Symposium, to be published in Acta Phys. Pol. B36 (2005

    Large Deformation Effects in the N = Z 44Ti Compound Nucleus

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    The N = Z 44Ti* nucleus has been populated in Fusion Evaporation process at very high excitation energies and angular momenta using two entrance channels with different mass-asymmetry. The deformation effects in the rapidly rotating nuclei have been investigated through the energy distribution of the alpha-particle combined to statistical-model calculations. In the case of low-multiplicity events, the ratio between first particle emitted has been measured and shows significant disagreement with the predictions of the statistical-model. This may explain The large discrepancies observed in proton energy spectra measured in previous experiments performed in the same mass region.Comment: Proceeding of the 10th International Conference on Nuclear Reaction Mechanisms, Varenna Italy, June 9-13 2003. 10 pages, 6 figures, 1 tabl

    Decay Modes of Narrow Molecular Resonances

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    présenté par Sandrine Courtin (DRS-IPHC)The heavy-ion radiative capture reactions 12C(12C,γ)24Mg^{12}C(^{12}C,\gamma)^{24}Mg and 12C(16O,γ)28Si^{12}C(^{16}O,\gamma)^{28}Si have been performed on and off resonance at TRIUMF using the Dragon separator and its associated BGO array. The decay of the studied narrow resonances has been shown to proceed predominantly through quasi-bound doorway states which cluster and deformed configurations would have a large overlap with the entry resonance states

    Clusters in Light Nuclei

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    A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich Oxygen isotopes.Comment: 12 pages, 5 figures. Invited Talk presented by C. Beck at the Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape" XLV in the series of Zakopane Schools of Physics - International Symposium - Zakopane, Poland, August 30 - September 5, 2010.To be publihed in Acta Physica Polonica B42 no 3, March 201

    Nature and decay of a JĎ€J\pi=36+36^{+} resonance in the 24^{24}Mg + 24^{24}Mg reaction

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    It has been proposed to associate the narrow (\Gamma=170 keV) and high spin (JĎ€J\pi=36^+) resonance in the 24Mg + 24Mg reaction at E_c.m= 45.7 MeV with a hyperdeformed molecular state in 48Cr. Such a description has important consequences for the resonance decay into the favoured inelastic channels. Through fragment- coincidence measurements performed ON and OFF resonance using the PRISMA-CLARA array, we have established that the 24Mg states selectively populated are the 2^+ and 4^+ members of the ground state band

    Decay of a JĎ€=36+J^{\pi}=36^+ Resonance in the 24Mg+24Mg^{24}Mg + ^{24}Mg Reaction

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    The narrow (Γ\Gamma=170 keV) and high spin (Jπ=36+J^{\pi}=36^+) resonance in the 24^{24}Mg + 24^{24}Mg reaction at ECM_{CM}= 45.7 MeV has been associated with a hyperdeformed molecular state in 48^{48}Cr. Such a description has important consequences for the resonance decay into the favored inelastic channels. Through fragment- γ\gamma coincidence measurements performed ON and OFF resonance using the PRISMA-CLARA array, we have identified the 24^{24}Mg states selectively populated: the 2+2^+ and 4+4^+ members of the ground state band

    Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: A prospective observational study

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    Background: Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C-C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C. Methods: In a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with =2 clinical signs/symptoms of NP-C were considered ''suspected NP-C'' cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI =70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible. Results: In total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores =70. Plasma 7-KC was higher than control cut-off values in all patients with two NPC1 mutations, and in the majority of patients with single mutations. Family studies identified three further NP-C patients. Conclusion: This approach may be very useful for laboratories that do not have mass spectrometry facilities and therefore, they cannot use other NP-C biomarkers for diagnosis
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