The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies.An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (6.5 ± 7.4 (stat.) +8.3 −8.0 (sys.)) ns was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light (v − c)/c = (2.7 ± 3.1 (stat.) +3.4 −3.3 (sys.)) × 10 −6 . The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 µs long extractions, was confirmed by a test performed at the end of 2011 using a short bunch beam allowing to measure the neutrino time of flight at the single interaction level.
review the design and construction of the detector and of its related infrastructures, and report on some technical performances of the various components. The construction of the detector started in 2003 and it was completed in Summer 2008. The experiment is presently in the data taking phase. The whole sequence of operations has proven to be successful, from triggering to brick selection, development, scanning and event analysis.
Seeds respond to multiple different environmental stimuli that regulate germination. Nitrate stimulates germination in many plants but how it does so remains unclear. Here we show that the Arabidopsis NIN-like protein 8 (NLP8) is essential for nitrate-promoted seed germination. Seed germination in nlp8 loss-of-function mutants does not respond to nitrate. NLP8 functions even in a nitrate reductase-deficient mutant background, and the requirement for NLP8 is conserved among Arabidopsis accessions. NLP8 reduces abscisic acid levels in a nitrate-dependent manner and directly binds to the promoter of CYP707A2, encoding an abscisic acid catabolic enzyme. Genetic analysis shows that NLP8-mediated promotion of seed germination by nitrate requires CYP707A2. Finally, we show that NLP8 localizes to nuclei and unlike NLP7, does not appear to be activated by nitrate-dependent nuclear retention of NLP7, suggesting that seeds have a unique mechanism for nitrate signalling.
In plants, excess light has the potential to damage the photosynthetic apparatus. The damage is caused in part by reactive oxygen species (ROS) generated by electrons leaking from the photosynthetic electron transport system. To investigate the mechanisms equipped in higher plants to reduce high light (HL) stress, we surveyed the response of 7000 Arabidopsis genes to HL, taking advantage of the recently developed microarray technology. Our analysis revealed that 110 genes had a positive response to a 3 h treatment at a light intensity of 150 W m(-2). In addition to the scavenging enzymes of ROS, the genes involved in biosynthesis of lignins and flavonoids are activated by HL and actually resulted in increased accumulation of lignins and anthocyanins. Comparing the HL-responsive genes with drought-inducible genes identified with the same microarray system revealed a dense overlap between HL- and drought-inducible genes. In addition, we have identified 10 genes that showed upregulation by HL, drought, cold and also salt stress. These genes include RD29A, ERD7, ERD10, KIN1, LEA14 and COR15a, most of which are thought to be involved in the protection of cellular components.
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