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Search Results: 1 - 10 of 208445 matches for " L. Perasso "
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Evaluación de métodos por la Evaluación Externa de Calidad en Química Clínica
Eduardo Perasso,Daniel Mazziotta
Acta bioqu?-mica cl?-nica latinoamericana , 2004,
Abstract:
Aprendiendo Con las manos en la tierra: Educación Ambiental a través de la lumbricultura
María Laura Perasso
Boletín Biológica , 2011,
Abstract:
The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals
Y. Abe,T. Akiri,A. Cabrera,B. Courty,J. V. Dawson,L. F. G. Gonzalez,A. Hourlier,M. Ishitsuka,H. de Kerret,D. Kryn,P. Novella,M. Obolensky,S. Perasso,A. Remoto,R. Roncin
Physics , 2013, DOI: 10.1088/1748-0221/8/08/P08015
Abstract: We present the waveform digitiser used in the Double Chooz experiment. We describe the hardware and the custom-built firmware specifically developed for the experiment. The performance of the device is tested with regards to digitising low light level signals from photomultiplier tubes and measuring pulse charge. This highlights the role of quantisation effects and leads to some general recommendations on the design and use of waveform digitisers.
Systemic Administration of Mesenchymal Stem Cells Increases Neuron Survival after Global Cerebral Ischemia In Vivo (2VO)
Luisa Perasso,Carla Emilia Cogo,Debora Giunti,Carlo Gandolfo,Piero Ruggeri,Antonio Uccelli,Maurizio Balestrino
Neural Plasticity , 2010, DOI: 10.1155/2010/534925
Abstract: Although many studies have shown that administration of stem cells after focal cerebral ischemia improves brain damage, very little data are available concerning the damage induced by global cerebral ischemia. The latter causes neuronal death in selectively vulnerable areas, including the hippocampal CA1 region. We tested the hypothesis that intravenous infusion of bone marrowderived stromal cells (mesenchimal stem cells, MSC) reduce brain damage after transient global ischemia. In adult male Sprague-Dawley rats transient global ischemia was induced using bilateral common carotid artery occlusion for 20?min in addition to controlled hypotension. Five days after, the animals were anaesthetized with urethane and the brain was fixed, sectioned and stained with hematoxylin-eosin to investigate histological damage. MSC did not fully protect against ischemic damage, as the number of viable neurons in this group was lower than in normal (sham-operated) rats. However, in MSC-treated rats the number of viable CA1 pyramidal neurons was significally higher than in rats that had been subjected to ischemia but not treated with MSC. We conclude that intravenous administration of MSC after transient global ischemia reduces hippocampal damage. 1. Introduction Bone marrow (BM) contains populations of precursors that are multipotent and have the characteristics of stem cells of nonhematopoietic tissues. The precursors of nonhematopoietic tissues are referred to as bone marrow stromal cells (BMSCs) or mesenchymal stem cells (MSCs). They have attracted interest because of their capacity for self-renewal in a number of nonhematopoietic tissues and their multipotentiality for differentiation. They are able to cross the blood-brain barrier, to migrate throughout forebrain and cerebellum, and to differentiate to some extent into astrocytes and neurons. Despite their transdifferentiation potential, recent data have shown that MSCs display a significant capacity of decreasing inflammation, modulating immune responses, and protecting tissues from injuries, mostly through bystander paracrine mechanisms [1]. Cellular therapy of brain injury, including stroke and anoxic damage, stemmed from the assumption that stem cells differentiate and replace dead cells [2]. However, the usefulness of these cells in rebuilding neural networks is controversial [3], and several studies have now provided significant evidence that other mechanisms are likely to play a major role in protection and neural repair. These include induction of neurogenesis [4] and oligodendrogenesis [5], production of
A new anti-neutrino detection technique based on positronium tagging with plastic scintillators
G. Consolati,D. Franco,C. Jollet,A. Meregaglia,A. Minotti,S. Perasso,A. Tonazzo
Physics , 2015, DOI: 10.1016/j.nima.2015.06.021
Abstract: The main signature for anti-neutrino detection in reactor and geo-neutrino experiments based on scintillators is provided by the space-time coincidence of positron and neutron produced in the Inverse Beta Decay reaction. Such a signature strongly suppresses backgrounds and allows for measurements performed underground with a relatively high signal-to-background ratio. In an aboveground environment, however, the twofold coincidence technique is not sufficient to efficiently reject the high background rate induced by cosmogenic events. Enhancing the positron-neutron twofold coincidence efficiency has the potential to pave the way future aboveground detectors for reactor monitoring. We propose a new detection scheme based on a threefold coincidence, between the positron ionization, the ortho-positronium (o-Ps) decay, and the neutron capture, in a sandwich detector with alternated layers of plastic scintillator and aerogel powder. We present the results of a set of dedicated measurements on the achievable light yield and on the o-Ps formation and lifetime. The efficiencies for signal detection and background rejection of a preliminary detector design are also discussed.
Measurement of ortho-Positronium Properties in Liquid Scintillators
S. Perasso,G. Consolati,D. Franco,S. Hans,C. Jollet,A. Meregaglia,A. Tonazzo,M. Yeh
Physics , 2013, DOI: 10.1088/1748-0221/9/03/C03028
Abstract: Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.
Characterization of positronium properties in doped liquid scintillators
G. Consolati,D. Franco,S. Hans,C. Jollet,A. Meregaglia,S. Perasso,A. Tonazzo,M. Yeh
Physics , 2013, DOI: 10.1103/PhysRevC.88.065502
Abstract: Ortho-positronium (o-Ps) formation and decay can replace the annihilation process, when positron interacts in liquid scintillator media. The delay induced by the positronium decay represents either a potential signature for anti-neutrino detection, via inverse beta decay, or to identify and suppress positron background, as recently demonstrated by the Borexino experiment. The formation probability and decay time of o-Ps depend strongly on the surrounding material. In this paper, we characterize the o-Ps properties in liquid scintillators as function of concentrations of gadolinium, lithium, neodymium, and tellurium, dopers used by present and future neutrino experiments. In particular, gadolinium and lithium are high neutron cross section isotopes, widely used in reactor anti-neutrino experiments, while neodymium and tellurium are double beta decay emitters, employed to investigates the Majorana neutrino nature. Future neutrino experiments may profit from the performed measurements to tune the preparation of the scintillator in order to maximize the o-Ps signature, and therefore the discrimination power.
Mass hierarchy discrimination with atmospheric neutrinos in large volume ice/water Cherenkov detectors
Franco, D.;Jollet, C.;Kouchner, A.;Kulikovskiy, V.;Meregaglia, A.;Perasso, S.;Pradier, T.;Tonazzo, A.;Van Elewyck, V.
High Energy Physics - Phenomenology , 2013,
Abstract: Large mass ice/water Cherenkov experiments, optimized to detect low energy (1-20 GeV) atmospheric neutrinos, have the potential to discriminate between normal and inverted neutrino mass hierarchies. The sensitivity depends on several model and detector parameters, such as the neutrino flux profile and normalization, the Earth density profile, the oscillation parameter uncertainties, and the detector effective mass and resolution. A proper evaluation of the mass hierarchy discrimination power requires a robust statistical approach. In this work, the Toy Monte Carlo, based on an extended unbinned likelihood ratio test statistic, was used. The effect of each model and detector parameter, as well as the required detector exposure, was then studied. While uncertainties on the Earth density and atmospheric neutrino flux profiles were found to have a minor impact on the mass hierarchy discrimination, the flux normalization, as well as some of the oscillation parameter (\Delta m^2_{31}, \theta_{13}, \theta_{23}, and \delta_{CP}) uncertainties and correlations resulted critical. Finally, the minimum required detector exposure, the optimization of the low energy threshold, and the detector resolutions were also investigated.
Mass hierarchy discrimination with atmospheric neutrinos in large volume ice/water Cherenkov detectors
D. Franco,C. Jollet,A. Kouchner,V. Kulikovskiy,A. Meregaglia,S. Perasso,T. Pradier,A. Tonazzo,V. Van Elewyck
Physics , 2013, DOI: 10.1007/JHEP04(2013)008
Abstract: Large mass ice/water Cherenkov experiments, optimized to detect low energy (1-20 GeV) atmospheric neutrinos, have the potential to discriminate between normal and inverted neutrino mass hierarchies. The sensitivity depends on several model and detector parameters, such as the neutrino flux profile and normalization, the Earth density profile, the oscillation parameter uncertainties, and the detector effective mass and resolution. A proper evaluation of the mass hierarchy discrimination power requires a robust statistical approach. In this work, the Toy Monte Carlo, based on an extended unbinned likelihood ratio test statistic, was used. The effect of each model and detector parameter, as well as the required detector exposure, was then studied. While uncertainties on the Earth density and atmospheric neutrino flux profiles were found to have a minor impact on the mass hierarchy discrimination, the flux normalization, as well as some of the oscillation parameter (\Delta m^2_{31}, \theta_{13}, \theta_{23}, and \delta_{CP}) uncertainties and correlations resulted critical. Finally, the minimum required detector exposure, the optimization of the low energy threshold, and the detector resolutions were also investigated.
Solar neutrino physics with Borexino I
L. Ludhova,G. Bellini,J. Benziger,D. Bick,G. Bonfini,D. Bravo,M. Buizza Avanzini,B. Caccianiga,L. Cadonati,F. Calaprice,C. Carraro,P. Cavalcante,A. Chavarria,D. D'Angelo,S. Davini,A. Derbin,A. Etenko,K. Fomenko,D. Franco,C. Galbiati,S. Gazzana,C. Ghiano,M. Giammarchi,M. Goeger-Nef,A. Goretti,L. Grandi,E. Guardincerri,S. Hardy,Aldo Ianni,Andrea Ianni,A. Kayunov,V. Kobychev,D. Korablev,G. Korga,Y. Koshio,D. Kryn,M. Laubenstein,T. Lewke,E. Litvinovich,B. Loer,F. Lombardi,P. Lombardi,I. Machulin,S. Manecki,W. Maneschg,G. Manuzio,Q. Meindl,E. Meroni,L. Miramonti,M. Misiaszek,D. Montanari,P. Mosteiro,V. Muratova,L. Oberauer,M. Obolenksy,F. Ortica,K. Otis,M. Pallavicini,L. Papp,L. Perasso,S. Perasso,A. Pocar,R. S. Raghavan,G. Ranucci,A. Razeto,A. Re,P. A. Romani,A. Sabelnikov,R. Saldanha,C. Salvo,S. Schoenert,H. Simgen,M. Skorokhvatov,O. Smirnov,A. Sotnikov,S. Sukhotin,Y. Suvorov,R. Tartaglia,G. Testera,D. Vignaud,R. B. Vogelaar,F. Von Feilitzsch,J. Winter,M. Wojcik,A. Wright,M. Wurm,J. Xu,O. Zaimidoroga,S. Zavatarelli,G. Zuzel
Physics , 2012,
Abstract: Borexino is a large-volume liquid scintillator detector installed in the underground halls of the Laboratori Nazionali del Gran Sasso in Italy. After several years of construction, data taking started in May 2007. The Borexino phase I ended after about three years of data taking. Borexino provided the first real time measurement of the $^{7}$Be solar neutrino interaction rate with accuracy better than 5% and confirmed the absence of its day-night asymmetry with 1.4% precision. This latter Borexino results alone rejects the LOW region of solar neutrino oscillation parameters at more than 8.5 $\sigma$ C.L. Combined with the other solar neutrino data, Borexino measurements isolate the MSW-LMA solution of neutrino oscillations without assuming CPT invariance in the neutrino sector. Borexino has also directly observed solar neutrinos in the 1.0-1.5 MeV energy range, leading to the first direct evidence of the $pep$ solar neutrino signal and the strongest constraint of the CNO solar neutrino flux up to date. Borexino provided the measurement of the solar $^{8}$B neutrino rate with 3 MeV energy threshold.
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