1,486 research outputs found

    Theoretical treatments of fusion processes in collisions of weakly bound nuclei

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    We review the theoretical methods to evaluate fusion cross sections in collisions of weakly bound nuclei. We piont out that in such collisions the coupling to the breakup channel leads to the appearance of different fusion processes. The extentsion of the coupled-channel method to coupling with the continuum is the most successful treatment for these collisions. However, evaluating separate cross section for each fusion process remains a very hard task.Comment: 8 pages, 3 figures. Invited talk (LFC) at the IX International Conference on Nucleus-Nucleus Collisions, Rio de Janeiro, August 28- September 1, 2006. Nuclear Physics A, in pres

    6Li direct breakup lifetimes

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    alpha-d coincidence data were studied for the 6Li + 59Co reaction at E(lab) = 29.6 MeV. By using a kinematic analysis, it was possible to identify which process, leading to the same final state, has the major contribution for each of the selected angular regions. Contributions of the 6Li sequential and direct breakup to the incomplete fusion/transfer process were discussed by considering the lifetimes obtained by using a semiclassical approach, for both breakup components.Comment: 5 pages, 4 figures, Invited Talk (Parrallel Sessions) of A. Szanto de Toledo, prepared for the Proccedings of the 10th International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009, Beijing, China; submitted to Nucl. Phys. A (Proceedings of NN2009

    Elastic Scattering and Total Reaction Cross Section for the 6He + 27Al System

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    The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier using the RIBRAS (Radioactive Ion Beams in Brazil) facility. The Sao Paulo Potential(SPP) was used and its diffuseness and imaginary strength were adjusted to fit the elastic scattering angular distributions. Reaction cross-sections were extracted from the optical model fits. The reduced reaction cross-sections of 6He on 27Al are similar to those for stable, weakly bound projectiles as {6,7}Li, 9Be and larger than stable, tightly bound projectile as 16O on 27Al.Comment: 7 pages, 1 table, 3 figure

    Projectile breakup dynamics for 6^{6}Li + 59^{59}Co: kinematical analysis of α\alpha-dd coincidences

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    A study of the kinematics of the α\alpha-dd coincidences in the 6^{6}Li + 59^{59}Co system at a bombarding energy of Elab=29.6E_{lab} = 29.6 MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential projectile breakup and direct projectile breakup components. A careful analysis using a semiclassical approach of these processes provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to direct breakup to the 6^6Li high-lying continuum spectrum. %Comment: Revised version including new Fig.3 and Fig.4 with new CDCC calculations. Accepted for publication at Eur. Phys. Jour. A. 11 pages, 6 figure

    Allergic Reactions to Metamizole: Immediate and Delayed Responses

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    [EN] Background: Pyrazolones are the most common causes of selective nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity. We studied a large group of patients with immediate and delayed selective responses to metamizole. Methods: Patients with suspicion of hypersensitivity to metamizole were evaluated. We verified acetylsalicylic acid tolerance and classified patients as immediate or delayed responders if they showed symptoms less or more than 24 h after metamizole administration. Skin tests were performed and if negative, a basophil activation test (BAT) was performed on immediate responders. If it was negative, we performed a drug provocation test (DPT) with metamizole. Results: A total of 137 patients were included: 132 reacted within 24 h (single NSAID-induced urticaria/angioedema/ anaphylaxis; SNIUAA) and 5 after 24 h (single NSAID-induced delayed hypersensitivity reaction; SNIDHR). Most SNIUAA patients developed anaphylaxis (60.60%); for SNIDHR, maculopapular exanthema was the most frequent entity (60%). Skin testing was positive in 62.04% of all cases and BAT in 28% of the SNIUAA patients with negative skin tests. In 5.1% of the cases, DPT with metamizole was needed to establish the diagnosis. In 22.62% of the cases, diagnosis was established by consistent and unequivocal history of repeated allergic episodes in spite of a negative skin test and BAT. Conclusions: SNIUAA to metamizole is the most frequent type of selective NSAID hypersensitivity, with anaphylaxis being the most common clinical entity. It may occur within 1 h after drug intake. SNIDHR occurs in a very low percentage of cases. The low sensitivity of diagnostic tests may be due to incomplete characterization of the chemical structures of metamizole and its metabolites.The present study has been supported by the Institute of Health ‘Carlos III’ of the Ministry of Economy and Competitiveness [grants cofounded by European Regional Development Fund (ERDF), Red de Reacciones Adversas a Alergenos y Farmacos (RD12/0013/0001 and PI15/01317)] and by Consejeria de Salud de la Junta de Andalucía (PI-0463-2013).Blanca-López, N.; Pérez-Sanchez, N.; Agúndez, JA.; García-Martín, E.; Torres, MJ.; Cornejo-Garcia, JA.; Perkins, JR.... (2016). Allergic Reactions to Metamizole: Immediate and Delayed Responses. International Archives of Allergy and Immunology. 169(4):223-230. https://doi.org/10.1159/000444798S223230169

    Reaction mechanisms in the 6Li+59Co system

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    The reactions induced by the weakly bound 6Li projectile interacting with the intermediate mass target 59Co were investigated. Light charged particles singles and α\alpha-dd coincidence measurements were performed at the near barrier energies E_lab = 17.4, 21.5, 25.5 and 29.6 MeV. The main contributions of the different competing mechanisms are discussed. A statistical model analysis, Continuum-Discretized Coupled-Channels calculations and two-body kinematics were used as tools to provide information to disentangle the main components of these mechanisms. A significant contribution of the direct breakup was observed through the difference between the experimental sequential breakup cross section and the CDCC prediction for the non-capture breakup cross section.Comment: 30 pages, 8 figure

    About Low DFR for QC-MDPC Decoding

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    International audienceMcEliece-like code-based key exchange mechanisms using QC-MDPC codes can reach IND-CPA security under hardness assumptions from coding theory, namely quasi-cyclic syndrome decoding and quasi-cyclic codeword finding. To reach higher security requirements, like IND-CCA security, it is necessary in addition to prove that the decoding failure rate (DFR) is negligible, for some decoding algorithm and a proper choice of parameters. Getting a formal proof of a low DFR is a difficult task. Instead, we propose to ensure this low DFR under some additional security assumption on the decoder. This assumption relates to the asymptotic behavior of the decoder and is supported by several other works. We define a new decoder, Backflip, which features a low DFR. We evaluate the Backflip decoder by simulation and extrapolate its DFR under the decoder security assumption. We also measure the accuracy of our simulation data, in the form of confidence intervals, using standard techniques from communication systems

    Hypersensitivity to Nonsteroidal Anti-inflammatory Drugs in Children and Adolescents: Cross-Intolerance Reactions.

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    Journal Article; Research Support, Non-U.S. Gov't; Review;Nonsteroidal anti-inflammatory drugs (NSAIDs) are used worldwide and are responsible for several types of drug hypersensitivity reactions (DHRs) in all age groups. The 2 major groups of DHRs to NSAIDs are those induced by immunological mechanisms (selective reactions) and those where inflammatory mediators are released through activation of the prostaglandin-leukotriene pathway without specific immunological recognition (cross-intolerance). In the present review, we focus on cross-intolerance reactions, which are the most frequent DHRs and are becoming a topic of major interest in children and adolescents. Paracetamol and ibuprofen are the drugs that most frequently cause DHRs in children; other NSAIDs are responsible for reactions in adolescents. In vivo and in vitro tests are of limited diagnostic value, with some exceptions for the less common selective reactions. In cross-intolerance, the clinical history and controlled administration are in many instances the only way to establish a diagnosis and look for alternatives. The clinical history is diagnostic when consistent symptoms occur repeatedly after exposure to NSAIDs with different chemical structures. Cutaneous and respiratory symptoms often co-occur in young children. The natural history of these reactions in children is unknown, and some patients can develop tolerance over time. Atopy remains a major risk factor for cross-intolerant reactions. The increasing interest in hypersensitivity to NSAIDs with improvements in patient phenotyping and the information provided by pharmacogenetics will improve our understanding and management of these reactions in the near future.The present study was supported by grants from the Carlos III National Health Institute RD12/0013 (RIRAAF Network), FIS PI12/02247, and FIS PI13/02598. It was also supported by Marie Curie (IAPP 7th Framework Program Mr. SymBioMath, no. 324554) and the Andalusian Public Health Service (PI-0279-2012 and PI-0463-2013).YesLos antiinflamatorios no esteroideos (AINEs) son ampliamente utilizados en todo el mundo y en todos los tramos de edad. Son responsables de un número importante de reacciones de hipersensibilidad a fármacos (RHFs), que no sólo afectan a adultos sino también a niños y adolescentes. Existen dos grandes grupos: reacciones selectivas, inducidas por mecanismos inmunológicos específicos, y de intolerancia cruzada (IC), donde se liberan mediadores inflamatorios en ausencia de reconocimiento inmunológico específico. En esta revisión nos ocuparemos de la IC, que es la causa más frecuente de RHFs y resulta de gran interés en niños y adolescentes. El paracetamol y el ibuprofeno son los medicamentos más frecuentemente implicados en las RHFs en niños. El uso diagnóstico de los tests in vivo e in vitro es muy limitado, con algunas excepciones en las reacciones selectivas. En las de IC, la historia clínica y la administración controlada son en ocasiones la única vía para confirmar el diagnóstico y determinar las alternativas terapéuticas más adecuadas. La historia clínica tiene valor diagnóstico cuando se reproducen síntomas consistentes repetidamente tras la exposición a AINEs no relacionados estructuralmente. En niños de corta edad es especialmente frecuente la combinación de síntomas cutáneos y respiratorios. Aunque se desconoce la historia natural de la IC en niños, es probable que se desarrolle tolerancia a lo largo de la vida. El fenotipado detallado junto con la información proporcionada por la fármaco-genética no sólo proporcionarán un conocimiento más preciso de la IC sino que también facilitará el manejo clínico de estos pacientes

    Soft drink intake is associated with weight gain, regardless of physical activity levels: The health workers cohort study

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    Background: While soft drink intake is positively associated with weight gain, no previous study has investigated whether leisure-time physical activity modifies this association. We estimated the association between soft drink intake and body weight, and explored if this association differed by levels of leisure-time physical activity. Methods: We used data from the health workers cohort study, a prospective study of Mexican adults (20 to 85y old), including 1268 health workers and their families, who were assessed at baseline (2004-2006) and follow-up (2010-2012). We assessed soft drink intake (cola and flavored soda) using a validated food frequency questionnaire. We measured leisure-time physical activity using a self-report questionnaire, and categorized according to the 2010 World Health Organization (WHO) recommendations. Body weight was measured by trained personnel. The association between changes in soft drink intake and weight change, and if such association varied by levels of physical activity was estimated through fixed-effect models. Results: An increase in one serving per day of soft drink was associated with 0.10 kg (95% CI 0.00, 0.19) increase in weight per year. This association was not modified by leisure-time physical activity, as demonstrated by the magnitude of the coefficient of the interaction between soft drink, leisure-time physical activity, and time (-0.03 kg, 95% CI-0.27 to 0.21); people who complied with the WHO physical activity recommendations gained 0.36 kg/year per serving of soft drink, compared to 0.48 kg/year for people without sufficient physical activity. Conclusions: Soft drink intake was associated with weight gain. Leisure-time physical activity did not modify the association between soft drink intake and weight gain. This finding challenges the idea that leisure-time physical activity is sufficient to counterbalance weight gain associated to soft drink intake
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