735 research outputs found
Evidence for resonance behaviour of A1 and A3 mesons coherently produced on nuclei
No full textAn analysis of about 60 000 events produced in the reaction π-A → (π+π-π-)A on nine different nuclear targets A at 8.9, 12.9, and 15.1 GeV/c has been performed using the Illinois PWA program. In the A1 region our "coherent" sample of events (which contains about 11% of incoherently produced events) is described by only four partial waves: the 1+S and 1+P amplitudes, which both show a peak, and the O-S and O-P waves, which are rather constant. We observed variations of both 1+S and 1+P phases relative to the O-P phase by about 90° across the A1 peak. This observation suggests the presence of resonant 1+ waves in the A1 mass region (∼1.1 GeV). In the A3 region we observe that the 2- state shows resonance behaviour and that fπ and ρ{variant}π are two decays modes with amplitudes of opposite signs
Evidence that absorption in the π+ π− π− system in nuclear matter is stronger in the JP = 0− than in the JP = 1+ state
No full textIn the reaction π- + A → π+ π- π- + A at 15.1 GeV/c the coherently produced 3π mass spectrum has a broad peak around 1.1 GeV which consists mainly of a JP = 1+ state and of a smaller fraction of 0-. Comparing the observed dependence of the production of these diffractive states on the atomic weight A of the target nuclei with the optical model, we have studied the absorption of the produced states in nuclear matter. We have found the following values of the absorption cross-sections: σ2(0-) = 49-7+9 mb and σ2(1+) = 15.8-1.3+1.5 mb
Simulation of light collection in the CMS lead tungstate crystals with the program Litrani: coating and surface effects
No full textThe accuracy of the lead tungstate electromagnetic calorimeter of the CMS experiment under construction at CERN relies, among other things, on the correction of the calibration parameter from variations dues to crystal ageing. This ageing will be measured by a so-called monitoring system, but the relation between monitoring and calibration parameter variations is not so trivial, and depends much on the overall optical characteristics of crystal and photodetector. We present here simulations done with the program Litrani based on real ageing data for a realistic CMS crystal with a defined surface quality (optically polished, with or without one lateral face slightly depolished), covered by coatings of various characteristics, from totally absorbing to nominal aluminum or diffusing medium. The correlation coefficient between monitoring and scintillation signals depends greatly o n these characteristics, and varies between about 1.3 and more than 10 (the optimum being one). Submitted to or Presented at: Contact e-mail - [email protected]
Simulation of light collection in the CMS lead tungstate crystals with the program Litrani: coating and surface effects
No full textSeveral uses of MC 68000 in CAMAC systems
No full textCAMAC is the universally used standard in high energy physics experiments. In order to give to technicians a debugging and trouble shooting tool and to physicists a cheap system for apparatus test the authors have developed an Autonomous Camac Branch Driver using the MC 68000, 16 bits, microprocessor. To achieve it they have designed a powerful CAMAC interface and interactive software allowing very simple use of this tool. In the same way they have also designed an Auxiliary Crate Controller, with an associated 64K to 256K words (16 bits) memory, for data acquisition and preprocessing at the CAMAC Crate Level. Keeping in the mind the same idea the authors are designing a new Branch Driver with a large memory, devoted to data acquisition and working as a frontal processor, at the CAMAC Branch level, for the main experiment computer. (0 refs)
Haplotypes of "Candidatus Liberibacter solanacearum" identified in Umbeliferous crops in Spain
No full text[EN] 'Candidatus Liberibacter solanacearum' is a phloem-limited Gram-negative bacterium that causes serious damage to different crops of the botanical families Solanaceae and Apiaceae. Five haplotypes have been described: LsoA and LsoB are present in solanaceous crops in America and vectored by the tomato/potato psyllid Bactericera cockerelli; LsoC affects carrots from Northern and Central Europe, and is transmitted by the carrot psyllid Trioza apicalis; haplotypes LsoD and LsoE are present in Southern Europe and Morocco in carrot and celery, and are associated with the psyllid Bactericera trigonica. Thirty-four 'Ca. L. solanacearum' isolates were collected in six different regions of Spain from distinct Apiaceae hosts (carrot, celery, parsley and parsnip) in eight consecutive years and were analysed. Their haplotypes were determined by a sequence analysis of 16S ribosomal RNA, the 16S-26S ribosomal RNA intergenic spacer, and the 23S ribosomal RNA and rplJ and rplL genes. Both haplotypes LsoD and LsoE were found across Spain, and no host specificity appeared between these two haplotypes. This is the first report of 'Ca. L. solanacearum' associated with parsley and parsnip.This work has been supported by grant INIA (RTA2011-00142). This paper is dedicated to the memory of F.J. Villaescusa (1981-2011). The technical support of S. Sanjuan and J.C. Ferrandiz from Agricola Villena Coop. V. is also acknowledged.Alfaro Fernández, AO.; Hernández-Llopis, D.; Font San Ambrosio, MI. (2017). Haplotypes of "Candidatus Liberibacter solanacearum" identified in Umbeliferous crops in Spain. European Journal of Plant Pathology. 149(1):127-131. https://doi.org/10.1007/s10658-017-1172-2S1271311491Alfaro-Fernández A., Cebrián M.C., Villaescusa F.J., Hermoso de Mendoza A., Ferrándiz J.C., Sanjuán S., Font M.I. (2012). ‘Candidatus Liberibacter solanacearum’ associated with Bactericera trigonica affected carrots in the Canary Islands. 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M., Wilm, A., Lopez, R., Thompson, J. D., Gibson, T. J., & Higgins, D. G. (2007). Clustal W and Clustal X version 2.0. Bioinformatics, 23, 2947–2948.Loiseau, M., Garnier, S., Boirin, V., Merieau, M., Leguay, A., Renaudin, I., Renvoisé, J.-P., & Gentit, P. (2014). First report of ‘Candidatus Liberibacter solanacearum’ in carrot in France. Plant Disease, 98, 839.Munyaneza, J. E. (2012). Zebra chip disease of potato: biology, epidemiology and management. American Journal of Potato Research, 89, 329–350.Munyaneza, J., Buchman, J., Upton, J., Goolsby, J., Crosslin, J., & Bester, G. (2008). Impact of different potato psyllid populations on zebra chip disease incidence, severity, and potato yield. Subtropical Plant Science, 60, 27–37.Munyaneza, J., Sengoda, V., Crosslin, J., de la Rosa-Lorenzo, G., & Sanchez, A. (2009). First report of ‘Candidatus Liberibacter psyllaurous’ in potato tubers with zebra Chip disease in Mexico. Plant Disease, 93, 552.Munyaneza, J. E., Fisher, T. W., Sengoda, V. G., & Garczynski, S. F. (2010a). First report of ‘Candidatus Liberibacter solanacearum’ associated with psyllid-affected carrots in Europe. Plant Disease, 94, 639.Munyaneza, J. E., Fisher, T. W., Sengoda, V. G., Garczynski, S. F., Nissinen, A., & Lemmetty, A. (2010b). Association of ‘Candidatus Liberibacter solanacearum’ with the psyllid Trioza apicalis (hemiptera: Triozidae). Journal of Economic Entomology, 103, 1060–1070.Munyaneza, J. E., Swisher, K. D., Hommes, M., Willhauck, A., Buck, H., & Meadow, R. (2015). First report of ‘Candidatus Liberibacter solanacearum’ associated with psyllid-infested carrots in Germany. Plant Disease, 99, 1269.Nelson, W. R., Fisher, T. W., & Munyaneza, J. E. (2011). Haplotypes of “Candidatus Liberibacter solanacearum” suggest long-standing separation. European Journal of Plant Patholology, 130, 5–12.Nelson, W. R., Sengoda, V. G., Alfaro-Fernández, A., Font, M. I., Crosslin, J. M., & Munyaneza, J. E. (2013). 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Spanish Journal of Agricultural Research, 13, e10–002
Towards dissecting the structural determinant of Peach latent mosaic viroid inducing mosaic symptoms
No full textMost isolates of Peach latent mosaic viroid (PLMVd) do not incite foliar symptoms, but a few number of isolates cause peach mosaic (PM) or peach calico (PC), an extreme albino phenotype. The PC determinant has been previously mapped at an insertion of 12-13 nt folding into a hairpin capped by a U-rich loop but the PM determinant, which is not associated with a specific insertion, remains unidentified and could reside in one or more domains of the branched conformation proposed for PLMVd. To tackle this problem we have selected for further dissection one variant (GDS6), recovered from a typical PM isolate (GDS), which is very infectious and elicits consistently a characteristic PM. We have initially focused on G337, a position that appears associated with PM in multiple alignments that include GDS6 and other PM-inducing and latent variants. To determine the role of G337 in infectivity and symptoms, GF-305 peach seedlings were inoculated with in vitro transcripts of recombinant plasmids containing dimeric tandem inserts of PLMVd-cDNAs with all possible changes at this position introduced by site-directed mutagenesis. Deletion of G337 abolished infectivity, while substitutions by A, C or U incited, in most inoculated plants, PM symptoms. Cloning and sequencing showed that the A substitution at position 337 was preserved in the progeny or reverted to G, while C or U substitutions at this position were not stable and reverted to A or G in the progenies. Extending this approach to additional nucleotides of loop A, or of other PLMVd domains, may provide hints in identifying the determinant of PM. Keywords: Viroids, Pathogenesis, Peach diseas
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