490 research outputs found

    Identification of endophytic bactéria from micropropagated yacon (Smallanthus sonchifolius) crowing under autotrophic and Heterotrophic systems.

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    Yacon, Smallanthus sonchifolius, an Andean species. is a rich source of dictetíc oligofructans with low glucose content. proteins and phenolic compounds. These constituents have shown efficacy in the prevention of diet-related ehronic diseases, including gastroin-testinal disorders and diabetes |1,2|. Yacon is part of a research program at the National Center for Natural Products Research (NCNPR) and University of Mississippi Field Station to develop new alternative root crops for Mississippi while attempting to im-prove the diet of low incorne families. Yacon can be easily propa-gated by cultings. Virus and nematode infections have been re-ported on plants propagated by cuttings in Brazil. a country that hás adopted Yacon as specialty crop [3|. We have developed two culture systems. autotrophic and heterotrophic, to produce healthy plants. Herem we describe the presence of endophytic bactéria m micropropagated Yacon. In auxin free media, new roots were induced. Overa 15day period. the average root mduction per expiam was 5.45 to 8.75 under autotrophic and heterotrophic cul-tures, respectively. Root lenglh vaned between 3 and 60mrn. The presence of root hairs and lateral roots was noticed only in auto-trophic condilions. These beneficiai bactéria were identified and chemically ctiaracterized. Acknowledgement: This research work was partially supported by the USDA/ARS Cooperative Research Agreement No. 58-6408-2-009. Referentes; |1) Terada S. et ai. (2006] Yakugaku Zasshi 126(8): 665-669. (2| Valentová K. Ulri-chová j. (2003) Biomedical Papers 147: 119-130. [3| Mogor C. et ai, (2003) Acta Horticulturea 597: 311 -313

    Quartz Cherenkov Counters for Fast Timing: QUARTIC

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    We have developed particle detectors based on fused silica (quartz) Cherenkov radiators read out with micro-channel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (Sigma(t) about 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, e.g. p + p - p + H + p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored beams. The detectors have small areas (square cm), but need to be active very close (a few mm) to the intense LHC beam, and so must be radiation hard and nearly edgeless. We present results of tests of detectors with quartz bars inclined at the Cherenkov angle, and with bars in the form of an "L" (with a 90 degree corner). We also describe a possible design for a fast timing hodoscope with elements of a few square mm.Comment: 24 pages, 14 figure

    An Improved Limit on Invisible Decays of Positronium

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    The results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evid ence for new physics beyond the Standard Model (SM): for example the existence of extra--dimensions, of milli-charged particles, of new light gauge bosons or of mirror particles. Mirror matter could be a relevant dark matter candidate. In this paper the setup and the results of a new experiment are presented. In a collected sample of about (6.31±0.28)×106(6.31\pm0.28) \times 10^6 orthopositronium decay s, no evidence for invisible decays in an energy window [0,80] keV was found and an upper limit on the branching ratio of orthopositronium \invdecay could be set: \binvdecay<4.2\times 10^{-7} (90% C.L.) Our results provide a limit on the photon mirror-photon mixing strength ϵ1.55×107\epsilon \leq 1.55\times 10^{-7} (90% C.L.) and rule out particles lighter than the electron mass with a fraction Qx3.4×105Q_x \leq 3.4 \times 10^{-5} of the electron charge. Furthermore, upper limits on the branching ratios for the decay of parapositronium Br(pPsinvisible)4.3×107Br(p-Ps\to invisible)\leq 4.3 \times 10^{-7} (90% C.L.) and the direct annihilation Br(e+einvisible)2.1×108Br(e^+e^-\to invisible)\leq 2.1 \times 10^{-8} (90% C.L.) could be set.Comment: 17 pages, 7 figures, added references, fixed limit on millicharged particles and changed two plots accordingl

    Study of the ηπo\eta\pi^o system in the mass range up to 1200 MeV

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    The reaction πpηπon\pi^-p \to \eta\pi^o n has been studied with GAMS-2000 spectrometer in the secondary 38 GeV/c π\pi^--beam of the IHEP U-70 accelerator. Partial wave analysis of the reaction has been performed in the ηπo\eta\pi^o mass range up to 1200 MeV. The a0(980)a_0(980)-meson is seen as a sharp peak in S-wave. The tt-dependence of a0(980)a_0(980) production cross section has been studied. Dominant production of the a0(980)a_0(980) at a small transfer momentum tt confirms the hypothesis of Achasov and Shestakov about significant contribution of the ρ2\rho_2 exchange (IGJPC=1+2I^GJ^{PC}=1^+2^{--}) in the mechanism of a0(980)a_0(980) meson production in tt-channel of the reaction.Comment: 4 pages, 3 figures, talk given at HADRON'9

    Test of an LED Monitoring System for the PHOS Spectrometer

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    Preprint submitted to Elsevier Print on 26th January 2000A prototype monitoring system for the Photon Spectrometer (PHOS) of the ALICE experiment at LHC is described in detail. The prototype consists of Control and Master modules. The first one is 8x8 matrix of Light Emitting Diodes coupled with stable generators of current pulses. The system provides an individual control for each of the 64 channels of PHOS prototype based on lead-tungstate crystals. A long term stability of order of 10-3 has been achieved in integral beam tests of the monitoring system and PHOS prototypes

    О формировании стоимости разработки летательного аппарата

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    The article discusses approaches to the formation of the limit prices of aircraft with using of elements of economic-mathematical modeling. Theoretical and practical aspects of development of methods of solving economic problems in the implementation of the mechanism of formation of effective innovation-stimulating prices in the drafting and design of aircraft.В статье рассматриваются подходы к формированию лимитных цен летательных аппаратов с использованием элементов экономико-математического моделирования. Рассмотрены теоретические и практические аспекты разработки методик решения экономических задач по реализации механизма формирования эффективных инновационно-стимулирующих цен при разработке и проектировании летательных аппаратов

    Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS

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    We report on a direct search for sub-GeV dark photons (A') which might be produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The A's would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75\cdot 10^{9} electrons on target. We set new limits on the \gamma-A' mixing strength and exclude the invisible A' with a mass < 100 MeV as an explanation of the muon g_\mu-2 anomaly.Comment: 6 pages, 3 figures; Typos corrected, references adde

    Measurement of the charged-pion polarisability

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    The COMPASS collaboration at CERN has investigated pion Compton scattering, πγπγ\pi^-\gamma\rightarrow \pi^-\gamma, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction πNiπγ  Ni\pi^-\mathrm{Ni}\rightarrow\pi^-\gamma\;\mathrm{Ni}, which is initiated by 190\,GeV pions impinging on a nickel target. The exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q2<0.0015Q^2<0.0015\,(GeV/cc)2^2. From a sample of 63\,000 events the pion electric polarisability is determined to be $\alpha_\pi\ =\ (\,2.0\ \pm\ 0.6_{\mbox{\scriptsize stat}}\ \pm\ 0.7_{\mbox{\scriptsize syst}}\,) \times 10^{-4}\,\mbox{fm}^3undertheassumption under the assumption \alpha_\pi=-\beta_\pi$, which relates the electric and magnetic dipole polarisabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction, that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambigiously known, was performed for an independent estimate of the systematic uncertainty.Comment: Published version: 9 pages, 3 figures, 1 tabl

    Synthesis, biological evaluation, X-ray molecular structure and molecular docking studies of RGD mimetics containing 6-amino-2,3-dihydroisoindolin-1-one fragment as ligands of integrin αIIbβ3

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    AbstractA series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born’s method was shown to be due to inhibition of fibrinogen binding to αIIbβ3. Molecular docking of RGD mimetics to αIIbβ3 receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores. The single crystal X-ray data were obtained for five mimetics
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