304 research outputs found
Nuevos registros de Coccoidea (Homoptera: Sternorrhyncha) para Cuba
No full textSe dan a conocer nuevos registros de Coccoidea para Cuba, en los cuales se incluye el genera Parasaissetia Takahashi (Coccidae) y las especies Saissetia neglecta DeLotto (Coccidae) y Eriococcu,s dubius Cockerell (Eriococcidae). Ademas se relacionan las plantas hospedantes, con nuevos registros para estas especies.New records of Coccoidea for Cuba are given, they include new records of the species Parasaissetia nigra (Nietner) (Coccidae), Saissetia neglecta DeLotto (Coccidae) and Eriococcus dubius (Eriococcidae). Besides the host plants with new records
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Master's thesis recital (percussion)
No full textRebonds B / Iannis Xenakis -- Cello suite no. 6 in D major, BWV 1012 / Johann Sebastian Bach -- Ricochet / Shaun Tilburg -- Suomineito / Nebojsa Jovan Zivkovic -- The acoustic impression / Aaron Spevak -- Home triology. II., White pines Michael Burritt.Musi
Nucleocytoplasmic shuttling mediates the dynamic maintenance of nuclear Dorsal levels during Drosophila embryogenesis
No full textUdgivelsesdato: 2007-DecIn Drosophila, the NF-kappaB/REL family transcription factor, Dorsal, redistributes from the cytoplasm to nuclei, forming a concentration gradient across the dorsoventral axis of the embryo. Using live imaging techniques in conjunction with embryos expressing a chimeric Dorsal-GFP, we demonstrate that the redistribution of Dorsal from cytoplasm to nucleus is an extremely dynamic process. Nuclear Dorsal concentration changes continuously over time in all nuclei during interphase. While Dorsal appears to be nuclearly localized primarily in ventral nuclei, it is actively shuttling into and out of all nuclei, including nuclei on the dorsal side. Nuclear export is blocked by leptomycin B, a potent inhibitor of Exportin 1 (CRM1)-mediated nuclear export. We have developed a novel in vivo assay revealing the presence of a functional leucine-rich nuclear export signal within the carboxyterminal 44 amino acids of Dorsal. We also find that diffusion of Dorsal is partially constrained to cytoplasmic islands surrounding individual syncitial nuclei. A model is proposed in which the generation and maintenance of the Dorsal gradient is a consequence of an active process involving both restricted long-range diffusion and the balancing of nuclear import with nuclear export
Observation of orbitally excited B mesons
No full textExperimental evidence for the existence of orbitally excited B meson states is presented in an analysis of the Bπ and B*π distribution of Q = m(B**) - m(B(*)) - m(π) using Z0 decay data taken with the DELPHI detector at LEP. The mean Q-value of the decays B** → B(*)π is measured to be 284 ± 5 (stat.) ± 15 (syst.) MeV/c2, and the Gaussian width of the signal is 79 ± 5 (stat.) ± 8 (syst.) MeV/c2. This signal can be described as a single resonance of mass m = 5732 ± 5 (stat.) ± 20 (syst.) MeV/c2 and full width Γ = 145 ± 28 MeV/c2. The observed shape is also consistent with the production of several broad and narrow states as predicted by the quark model and partly observed in the D-meson sector. The production rate of B** per b-jet is found to be 0.27 ± 0.02 (stat.) ± 0.06 (syst.).0info:eu-repo/semantics/publishe
A Measurement of the mean lifetimes of charged and neutral B hadrons
No full textThe decays of B-hadrons have been reconstructed using the charged particles recorded in the DELPHI silicon microstrip detector. The sum of the charges of the secondaries determines the charge of the B-hadron parent. Some 232 114 multihadronic Z0 decays recorded during the 1991 run of LEP at centre-of-mass energies between 88.2 GeV and 94.2 GeV yield 253 B-hadron candidates with well-measured charge. From these the mean lifetimes of neutral and charged B-hadrons are found to be 1.44 ± 0.21 (stat.) ± 0.14(syst.) ps and 1.56 ± 0.19(stat.) ± 0.13(syst.) ps respectively. The ratio of their lifetimes is 1.09+0.28 -0.23(stat.) ± 0.11 (syst.). Under some assumptions on the abundance and lifetime of the Λ0 b and B0 s states, the B0 and B+ lifetimes are inferred.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Search for exclusive decays of the Lambda(b) baryon and measurement of its mass
No full textA search for fully reconstructed Lambda(b)(0) beauty baryons is performed using about 3 million Z decays collected with the DELPHI detector at LEP. The analysis relies on the combined use of the accurate tracking and of the hadron identification capabilities of DELPHI. A total of four events has been found, three in the Lambda(c)(+)pi(-) channel and one in the Lambda(c)(+)a(1)(-) channel over a small background. The Lambda(b)(0) beauty baryon mass is measured to be (5668 +/- 16 (stat.) +/-8 (syst.)) MeV/c(2)
Determination of alpha-s for b quarks at the Z0 resonance
No full textThe strong coupling constant for b quarks has been determined, and its flavour independence, as predicted by QCD, investigated. The analysis involved events with lepton candidates selected from approximately 356 000 hadronic decays of the Z0, collected by the DELPHI detector at LEP in 1990 and 1991 A method based on a direct comparison of the three-jet fraction in a b enriched sample, selected by requiring leptons with large momenta and transverse momenta, to that of the entire hadronic sample, illustrated the significant effect of the b quark mass on the multi-jet cross section, and verified the flavour independence of the strong coupling constant to an accuracy of ±6%. A second procedure based on a fit to the momentum and transverse momentum spectra of the lepton candidates in both two-jet and three (or more)-jet event samples simultaneously determined the b content in each, and, using second order QCD calculations, gave an absolute measurement of αs for b quarks of 0.118 ± 0.004 (stat.) ± 0.003 (syst.) ± 0.008 (scale). A comparison with αs for all quark flavours, as measured from the three-jet fraction in all hadronic events, further allowed the coupling strength for b quarks to be expressed in terms relative to that for udsc quarks, thereby cancelling certain common systematic uncertainties, and yielded αsb/αsudsc = 1.00 ± 0.04 (stat.) ± 0.03 (syst.)
Production of charged particles, K0(s), K+-, p and Lambda in Z --> b anti-b events and in the decay of b hadrons
No full textA sample of events enriched in bb̄ quark pairs was selected in the data recorded by the DELPHI experiment at LEP during 1992 and 1993, by the presence of secondary decay vertices from short-lived particles. Using this sample, the average multiplicities of KS0, K±, p(p̄), Λ(Λ̄) and of charged particles in bb̄ events have been measured, distinguishing the component from fragmentation and the component coming from the decay of b-hadrons. The measurement of the average charge multiplicity in bb̄ events was used to compute the mean fractional beam energy carried by the primary b-hadron, and the difference in charged particle multiplicity between bb̄ events and light quark (uū, dd̄, ss̄) events
A Study of B0 - anti-B0 mixing using semileptonic decays of B hadrons produced from Z0
No full textThe B0-B̄0 mixing was studied by using about 250000 hadronic decays of the Z0,_collected with the DELPHI detector at LEP. With 1665 dilepton events, the probability for a b quark to become a b̄ before decaying was found to be χ = 0.121-0.040 0.044 ± 0.017. The semileptonic branching ratio of the b was measured from the dilepton and single lepton events and found to be Br(b → l) = (10.0 ± 0.7 ± 0.7)%.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
SEARCH FOR THE t AND b-prime QUARKS IN HADRONIC DECAYS OF THE Z0 BOSON
No full textWe present a search for the third generation up type quark t and a possible fourth down type quark b' in hadronic Z0 decays observed in DELPHI at the LEP collider. For any scenario with a decay through the charged current or into a charged Higgs with a mass at least 6 GeV/c2 below the t and 3 GeVc2 below the b' mass, we set a lower limit for the t quark mass at 44.0 GeV/c2 and for the b' mass at 44.5 GeV/c2. For specific scenarios the mass limits are slightly higher, e.g. for charged current decays the limits are 44.5 and 45.0 GeV/c2 respectively, where all limits are given at a 95% confidence level. © 1990.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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