767 research outputs found

    LUNA: Status and Prospects

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    The essential ingredients of nuclear astrophysics are the thermonuclear reactions which shape the life and death of stars and which are responsible for the synthesis of the chemical elements in the Universe. Deep underground in the Gran Sasso Laboratory the cross sections of the key reactions responsible for the hydrogen burning in stars have been measured with two accelerators of 50 and 400 kV voltage right down to the energies of astrophysical interest. As a matter of fact, the main advantage of the underground laboratory is the reduction of the background. Such a reduction has allowed, for the first time, to measure relevant cross sections at the Gamow energy. The qualifying features of underground nuclear astrophysics are exhaustively reviewed before discussing the current LUNA program which is mainly devoted to the study of the Big-Bang nucleosynthesis and of the synthesis of the light elements in AGB stars and classical novae. The main results obtained during the study of reactions relevant to the Sun are also reviewed and their influence on our understanding of the properties of the neutrino, of the Sun and of the Universe itself is discussed. Finally, the future of LUNA during the next decade is outlined. It will be mainly focused on the study of the nuclear burning stages after hydrogen burning: helium and carbon burning. All this will be accomplished thanks to a new 3.5 MV accelerator able to deliver high current beams of proton, helium and carbon which will start running under Gran Sasso in 2019. In particular, we will discuss the first phase of the scientific case of the 3.5 MV accelerator focused on the study of 12^{12}C+12^{12}C and of the two reactions which generate free neutrons inside stars: 13^{13}C(α\alpha,n)16^{16}O and 22^{22}Ne(α\alpha,n)25^{25}Mg.Comment: To be published in Progress in Particle and Nuclear Physics 98C (2018) pp. 55-8

    Electromagnetic Properties of Neutrinos

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    In this review we discuss the main theoretical aspects and experimental effects of neutrino electromagnetic properties. We start with a general description of the electromagnetic form factors of Dirac and Majorana neutrinos. Then, we discuss the theory and phenomenology of the magnetic and electric dipole moments, summarizing the experimental results and the theoretical predictions. We discuss also the phenomenology of a neutrino charge radius and radiative decay. Finally, we describe the theory of neutrino spin and spin-flavor precession in a transverse magnetic field and we summarize its phenomenological applications.Comment: 39 pages. Invited review for the special issue of Advances in High Energy Physics on Neutrino Physic

    Sub MeV Particles Detection and Identification in the MUNU detector ((1)ISN, IN2P3/CNRS-UJF, Grenoble, France, (2)Institut de Physique, Neuch\^atel, Switzerland, (3) INFN, Padova Italy, (4) Physik-Institut, Z\"{u}rich, Switzerland)

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    We report on the performance of a 1 m3^{3} TPC filled with CF4_{4} at 3 bar, immersed in liquid scintillator and viewed by photomultipliers. Particle detection, event identification and localization achieved by measuring both the current signal and the scintillation light are presented. Particular features of α\alpha particle detection are also discussed. Finally, the 54{54}Mn photopeak, reconstructed from the Compton scattering and recoil angle is shown.Comment: Latex, 19 pages, 20 figure

    Allylsulfones through Palladium-Catalyzed Allylic C−H Sulfonylation of Terminal Alkenes

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    Two previously unknown protocols for Pd-catalyzed allylic C-H sulfonylation of terminal alkenes have been developed. While the former consists of a direct Pd(II)-catalyzed oxidative C-H allylic sulfonylation in the presence of sulfinate anions, the latter involves a sequential one-pot Pd(II)-catalyzed C-H allylic acetoxylation followed by a Pd(0)-catalyzed sulfonylation. The scope of both protocols was studied on 25 examples

    Detection of the fire blight biocontrol agent Bacillus subtilis BD170 (Biopro®) in a Swiss apple orchard

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    Fire blight, caused by Erwinia amylovora, is a major disease threat to apple, pear and other pome fruit worldwide. The disease is widespread in Europe and has recently become established in Switzerland. Antibiotics are the most effective controls used in North America but these are not permitted for agricultural use in most European countries. A newly registered biological control product Biopro®, based on the antagonist Bacillus subtilis strain BD170, is being used as an alternative strategy for fire blight management. A specific molecular marker was developed for monitoring the spread of this agent on blossoms after Biopro® spray application in a Swiss apple orchard throughout the bloom period for 2years. Direct spraying resulted in efficient primary colonisation of pistils in flowers that were open at the time of treatment. Subsequent bacterial dissemination (secondary colonisation) of flowers that were closed or at bud stage at the time of treatment was observed but was found to be dependent on the timing of treatments relative to bloom stage in the orchard. Foraging honeybees were shown to be disseminators of Biopro®. We also report detection of the biocontrol agent in honey collected from hives where bees were exposed by placing Biopro® at the entrance or in the hatching nest and from hives that were simply placed in sprayed orchard

    New Avoparcin-like Molecules from the Avoparcin Producer Amycolatopsis coloradensis ATCC 53629

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    Amycolatopsis coloradensis ATCC 53629 is the producer of the glycopeptide antibiotic avoparcin. While setting up the production of the avoparcin complex, in view of its use as analytical standard, we uncovered the production of a to-date not described ristosamynil-avoparcin. Ristosamynil-avoparcin is produced together with α-and β-avoparcin (overall indicated as the avoparcin complex). Selection of one high producer morphological variant within the A. coloradensis population, together with the use of a new fermentation medium, allowed to increase productivity of the avoparcin complex up to 9 g/L in flask fermentations. The selected high producer displayed a non-spore forming phenotype. All the selected phenotypes, as well as the original unselected population, displayed invariably the ability to produce a complex rich in ristosamynil-avoparcin. This suggested that the original strain deposited was not conforming to the description or that long term storage of the lyovials has selected mutants from the original population

    A candidate gene for fire blight resistance in Malus × robusta 5 is coding for a CC-NBS-LRR

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    Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Fire blight is the most important bacterial disease in apple (Malus ×  domestica) and pear (Pyrus communis) production. Today, the causal bacterium Erwinia amylovora is present in many apple- and pear-growing areas. We investigated the natural resistance of the wild apple Malus ×  robusta 5 against E. amylovora, previously mapped to linkage group 3. With a fine-mapping approach on a population of 2,133 individuals followed by phenotyping of the recombinants from the region of interest, we developed flanking markers useful for marker-assisted selection. Open reading frames were predicted on the sequence of a BAC spanning the resistance locus. One open reading frame coded for a protein belonging to the NBS–LRR family. The in silico investigation of the structure of the candidate resistance gene against fire blight of M. ×  robusta 5, FB_MR5, led us hypothesize the presence of a coiled-coil region followed by an NBS and an LRR-like structure with the consensus ‘LxxLx[IL]xxCxxLxxL’. The function of FB_MR5 was predicted in agreement with the decoy/guard model, that FB_MR5 monitors the transcribed RIN4_MR5, a homolog of RIN4 of Arabidopsis thaliana that could interact with the previously described effector AvrRpt2EA of E. amylovora

    A new FSA approach for in situ γ\gamma-ray spectroscopy

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    An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, γ\gamma-spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of γ\gamma-ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only 40^{40}K, 238^{238}U, and 232^{232}Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like 137^{137}Cs and 131^{131}I, which are used to monitor the effect of nuclear accidents or other human activities. The Full Spectrum Analysis (FSA) approach has been chosen to analyze the γ\gamma-spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the χ2\chi ^2 minimization which could lead to artifacts and non physical results in the analysis. A new calibration procedure has been developed for the FSA method by using in situ γ\gamma-spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring γ\gamma-spectra with a 10.16 cm x 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected in the different sites, showing a satisfactory agreement between them. In particular, the 137^{137}Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.Comment: accepted by Science of Total Environment: 8 pages, 10 figures, 3 table
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