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Fil: Hojsgaard, Diego Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina. Consiglio Nazionale delle Ricerche; Italia

Shashlik calorimeters equipped with a compact readout based on Silicon PhotoMultipliers can be longitudinally segmented by directly coupling the WLS fibers with the photosensors thus embedding the readout in the bulk of the calorimeter. Results on energy resolution and particle identification for such calorimeters are presented. The SiPMs for the readout have also been characterized after being exposed to neutron fluences up to 2×1011 n/cm2 (1 MeV eq.). Alternative options for the active material were also investigated; we studied in particular polysiloxane as a substitute for plastic scintillator.

The next generation of neutrino experiments requires measurements of absolute neutrino cross sections at the GeV scale with high precision (∼1%) presently limited by the uncertainties on neutrino flux. Monitoring the lepton production in the decay tunnel of neutrino beams is the most straightforward way to measure the neutrino flux at source. The ENUBET Collaboration develops novel technologies to monitor positrons from K+ → νee+π0 decays on an event by event basis. This technique can achieve a precision in the νe flux below 1% and enable a new generation of cross section and short baseline experiments. In this paper, we present the achievements of the first year of the Project on beamline simulation, rate and dose assessment, detector prototyping and evaluation of the physics reach.

Cytogenetic and DNA molecular analyses have been carried out in 3 wheat introgression lines (ILs; CS×V58, CS×V59, and CS×V60) derived from Triticum aestivum cv. ‘Chinese Spring’ (CS) × Dasypyrum villosum(Dv) intergeneric hybridization. All lines, which showed several phenotypic differences compared to CS, had the same chromosome number (2n = 42) and structure as CS, and neither chromosomes nor chromatin from Dv were apparently added to their complement. However, Feulgen/DNA cytophotometry showed that there was more nuclear DNA in the lines than in the parental wheat (by 1.85%, 2.76%, and 1.26% in CS×V58, CS×V59, and CS×V60, respectively). Molecular investigation indicated the presence of Dv DNA in the ILs. AFLP analysis of genomic DNA from the ILs, CS, and Dv detected a total of 120 polymorphic bands, of which 7 (5.8%) were present in some or all the ILs and Dv but were absent in CS. PCR amplification, sequence analysis of amplicons, and Southern blot hybridization confirmed the presence of Dv-specific sequences in each of the ILs. These results indicate cryptic introgression of Dv DNA sequences into the genome of the ILs. Some implications of this finding are discussed.

In plants, gametophytic apomixis is a form of asexual reproduction that leads to the formation of seed-derived offspring that are genetically identical to the mother plant. A common set of RFLP markers, including five rice anchor markers previously shown to be linked to apomixis in Paspalum simplex, were used to detect linkage with apomixis in P. notatum and P. malacophyllum. A comparative map of the region around the apomixis locus was constructed for the three Paspalum species, and compared to the rice map. The locus that controls apomixis in P. simplex was almost completely conserved in the closely related species P. malacophyllum, whereas it was only partially represented in the distantly related species P. notatum. Although strong synteny of markers was noted between this locus and a portion of rice chromosome 12 in both P. simplex and P. malacophyllum, the same locus in P. notatum was localized to a hybrid chromosome which carries markers that map to rice chromosomes 2 and 12. All three Paspalum species showed recombination suppression at the apomixis locus; in the case of P. notatum, this might be due to a heterozygosity for a translocation that most probably negatively interferes with chromosomal pairing near the locus. A common set of markers that show linkage with apomixis in all three Paspalum species define a portion of the apomixis-controlling locus that is likely to contain genes critical for apomictic reproduction.

Apomixis is a clonal mode of reproduction via seeds, which results from the failure of meiosis and fertilization in the sexual female reproductive pathway. In previous transcriptomic surveys, we identified a mitogen-activated protein kinase kinase kinase (N46) displaying differential representation in florets of sexual and apomictic genotypes. Here, we retrieved and characterized the N46 full cDNA sequence from sexual and apomictic floral transcriptomes. Phylogenetic analyses showed that N46 was a member of the family, which was re-named ( ). Differential expression in florets of sexual and apomictic plants was confirmed by qPCR. hybridization experiments revealed expression in the nucellus of aposporous plants' ovules, which was absent in sexual plants. RNAi inhibition of expression in two apomictic genotypes resulted in significantly reduced rates of aposporous embryo sac formation, with respect to the level detected in wild type aposporous plants and transformation controls. The locus segregated independently of apospory. However, a probe derived from a related long non-coding RNA sequence ( ) revealed RFLP bands cosegregating with the apospory-controlling region (ACR). is expressed in florets of apomictic plants only. Our results indicate that the activity of in the nucellus of apomictic plants is necessary to form non-reduced embryo sacs and that a long non-coding sequence with regulatory potential is similar to sequences located within the ACR.

A bstract The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino interaction target, made of Emulsion Cloud Chambers, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by π 0 s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate m 4 is introduced. At high Δ m 41 2 (≳0.1 eV 2 ), an upper limit on sin 2 2 θ μe is set to 0.021 at 90% C.L. and Δ m 41 2  ≳ 4 × 10 − 3 eV 2 is excluded for maximal mixing in appearance mode.

A bstract A first result of the search for ν μ → ν e oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ν e in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters θ new and suggested by the LSND and MiniBooNE experiments. For large values ( > 0.1 eV 2 ), the OPERA 90% C.L. upper limit on sin 2 (2 θ new ) based on a Bayesian statistical method reaches the value 7 . 2 × 10 −3 .

A bstract The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the ν μ → ν τ channel, via the detection of the τ -leptons created in charged current ν τ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first ν τ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional ν τ candidate has been observed. The significance of the two events in terms of a ν μ → ν τ oscillation signal is of 2.40 σ .

Direct Dark Matter searches are nowadays one of the most fervid research topics with many experimental efforts devoted to the search for nuclear recoils induced by the scattering of Weakly Interactive Massive Particles (WIMPs). Detectors able to reconstruct the direction of the nucleus recoiling against the scattering WIMP are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also prove the galactic origin of Dark Matter with an unambiguous signal-to-background separation. Indeed, the angular distribution of recoiled nuclei is centered around the direction of the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we present the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and of optical read-out systems reaching unprecedented nanometric resolution.