4,279 research outputs found

    A study of stopping power in nuclear reactions at intermediate energies

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    We show a systematic experimental study based on INDRA data of the stopping power in central symmetric nuclear reactions. Total mass of the systems goes from 80 to 400 nucleons while the incident energy range is from 12 AMeV to 100 AMeV. The role of isospin diffusion at 32 and 45 MeV/nucleon with 124,136Xe projectiles on 112,124Sn targets performed at GANIL is also discussed. Results suggest a strong memory of the entrance channel above 20 AMeV/A (nuclear transparency) and, as such, constitute valuable tests of the microscopic transport models.Comment: 7 pages, 3 figures, Proceedings of International Workshop on Multifragmentation and Related Topics (IWM 2009), Catania, Italy, 4 Nov-7 Nov 200

    Precision measurements in nuclear {\beta}-decay with LPCTrap

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    The experimental achievements and the current program with the LPCTrap device installed at the LIRAT beam line of the SPIRAL1-GANIL facility are presented. The device is dedicated to the study of the weak interaction at low energy by means of precise measurements of the {\beta}-{\nu} angular correlation parameter. Technical aspects as well as the main results are reviewed. The future program with new available beams is briefly discussed.Comment: Annalen der Physik (2013

    Localizing the Latent Structure Canonical Uncertainty: Entropy Profiles for Hidden Markov Models

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    This report addresses state inference for hidden Markov models. These models rely on unobserved states, which often have a meaningful interpretation. This makes it necessary to develop diagnostic tools for quantification of state uncertainty. The entropy of the state sequence that explains an observed sequence for a given hidden Markov chain model can be considered as the canonical measure of state sequence uncertainty. This canonical measure of state sequence uncertainty is not reflected by the classic multivariate state profiles computed by the smoothing algorithm, which summarizes the possible state sequences. Here, we introduce a new type of profiles which have the following properties: (i) these profiles of conditional entropies are a decomposition of the canonical measure of state sequence uncertainty along the sequence and makes it possible to localize this uncertainty, (ii) these profiles are univariate and thus remain easily interpretable on tree structures. We show how to extend the smoothing algorithms for hidden Markov chain and tree models to compute these entropy profiles efficiently.Comment: Submitted to Journal of Machine Learning Research; No RR-7896 (2012

    Update on the ICUD-SIU consultation on multi-parametric magnetic resonance imaging in localised prostate cancer

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    Introduction: Prostate cancer (PCa) imaging is a rapidly evolving field. Dramatic improvements in prostate MRI during the last decade will probably change the accuracy of diagnosis. This chapter reviews recent current evidence about MRI diagnostic performance and impact on PCa management. Materials and methods: The International Consultation on Urological Diseases nominated a committee to review the literature on prostate MRI. A search of the PubMed database was conducted to identify articles focussed on MP-MRI detection and staging protocols, reporting and scoring systems, the role of MP-MRI in diagnosing PCa prior to biopsy, in active surveillance, in focal therapy and in detecting local recurrence after treatment. Results: Differences in opinion were reported in the use of the strength of magnets [1.5 Tesla (T) vs. 3T] and coils. More agreement was found regarding the choice of pulse sequences; diffusion-weighted MRI (DW-MRI), dynamic contrast-enhanced MRI (DCE MRI), and/or MR spectroscopy imaging (MRSI) are recommended in addition to conventional T2-weighted anatomical sequences. In 2015, the Prostate Imaging Reporting and Data System (PI-RADS version 2) was described to standardize image acquisition and interpretation. MP-MRI improves detection of clinically significant PCa (csPCa) in the repeat biopsy setting or before the confirmatory biopsy in patients considering active surveillance. It is useful to guide focal treatment and to detect local recurrences after treatment. Its role in biopsy-naive patients or during the course of active surveillance remains debated. Conclusion: MP-MRI is increasingly used to improve detection of csPCa and for the selection of a suitable therapeutic approach

    Incidence of viral respiratory infections in a prospective cohort of outpatient and hospitalized children aged ≀5 years and its associated cost in Buenos Aires, Argentina

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    Background: Although information about the incidence of viral respiratory illnesses and their associated cost can help health officials explore the value of interventions, data are limited from middle-income countries. Methods: During 2008-2010, we conducted a prospective cohort study and followed ~1,800 Argentinian children aged ≀5years to identify those children who were hospitalized or who sought care at an emergency room with any acute respiratory infection sign or symptom (e.g., rhinorrhea, cough, wheezing, tachypnea, retractions, or cyanosis). Respiratory samples were obtained for respiratory syncytial virus, influenza, parainfluenza, adenovirus, and metapneumovirus testing by immunofluorescence and for rhinovirus by real-time reverse transcription polymerase chain reaction. Results: The incidence of respiratory syncytial virus (24/1000 children-years), human metapneumovirus (8/1000 children-years), and influenza (8/1000 children-years) illnesses was highest among hospitalized children aged <6months and decreased among older children. In contrast, the incidence of rhinovirus was highest (12/1000 children-years) among those aged 6-23 months. In the emergency room, the incidence of rhinovirus was 459; respiratory syncytial virus 352; influenza 185; parainfluenza 177; metapneumovirus 130; and adenovirus 73/1,000 children-years. The total cost of hospitalization was a median of US529(Interquartilerange,US529 (Interquartile range, US362-789). Conclusions: Our findings indicate that respiratory viruses, in particular rhinovirus, respiratory syncytial virus, metapneumovirus, and influenza may be associated with severe illness causing substantial economic burden.Fil: Marcone, DĂ©bora Natalia. Centro de Educaciones MĂ©dicas e InvestigaciĂłn ClĂ­nica ; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Durand, Lizette O.. Centers for Disease Control and Prevention; Estados UnidosFil: Azziz Baumgartner, Eduardo. Centers for Disease Control and Prevention; Estados UnidosFil: Vidaurreta, Santiago Manuel. Centro de Educaciones MĂ©dicas e InvestigaciĂłn ClĂ­nica ; ArgentinaFil: Ekstrom, Jorge. Centro de Educaciones MĂ©dicas e InvestigaciĂłn ClĂ­nica ; ArgentinaFil: Carballal, Guadalupe. Centro de Educaciones MĂ©dicas e InvestigaciĂłn ClĂ­nica ; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: EchavarrĂ­a, Marcela Silvia. Centro de Educaciones MĂ©dicas e InvestigaciĂłn ClĂ­nica ; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; Argentin

    A three-dimensional full Stokes model of the grounding line dynamics: effect of a pinning point beneath the ice shelf

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    The West Antarctic ice sheet is confined by a large area of ice shelves, fed by inland ice through fast flowing ice streams. The dynamics of the grounding line, which is the line-boundary between grounded ice and the downstream ice shelf, has a major influence on the dynamics of the whole ice sheet. However, most ice sheet models use simplifications of the flow equations, as they do not include all the stress components, and are known to fail in their representation of the grounding line dynamics. Here, we present a 3-D full Stokes model of a marine ice sheet, in which the flow problem is coupled with the evolution of the upper and lower free surfaces, and the position of the grounding line is determined by solving a contact problem between the shelf/sheet lower surface and the bedrock. Simulations are performed using the open-source finite-element code Elmer/Ice within a parallel environment. The model's ability to cope with a curved grounding line and the effect of a pinning point beneath the ice shelf are investigated through prognostic simulations. Starting from a steady state, the sea level is slightly decreased to create a contact point between a seamount and the ice shelf. The model predicts a dramatic decrease of the shelf velocities, leading to an advance of the grounding line until both grounded zones merge together, during which an ice rumple forms above the contact area at the pinning point. Finally, we show that once the contact is created, increasing the sea level to its initial value does not release the pinning point and has no effect on the ice dynamics, indicating a stabilising effect of pinning points

    New approach of fragment charge correlations in 129Xe+(nat)Sn central collisions

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    A previous analysis of the charge (Z) correlations in the ΔZ−\Delta Z- plane for Xe+Sn central collisions at 32 MeV/u has shown an enhancement in the production of equally sized fragments (low ΔZ\Delta Z) which was interpreted as an evidence for spinodal decomposition. However the signal is weak and rises the question of the estimation of the uncorrelated yield. After a critical analysis of its robustness, we propose in this paper a new technique to build the uncorrelated yield in the charge correlation function. The application of this method to Xe+Sn central collision data at 32, 39, 45 and 50 MeV/u does not show any particular enhancement of the correlation function in any ΔZ\Delta Z bin.Comment: 23 pages, 9 figures, revised version with an added figure and minor changes. To appear in Nuclear Physics
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