815 research outputs found

    A halo event created at 200 m above the Chacaltaya emulsion chamber

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    The results of analysis on a cosmic-ray induced nuclear event with the total visible energy approx. = 1300 TeV which is characterized by the central (halo) part of a strong energy concentration and the outer part of a large lateral spread are presented. The event (named as P06) was detected in the 18th two-storied emulsion chamber exposed at Chacaltaya by Brasil-Japan Collaboration. As the nuclear emulsion plates were inserted at every layer of the concerned blocks in the upper and the lower chambers together with RR- and N-type X-ray films, it is possible to study the details of the event. Some results on P06 have already been reported 1 based on the general measurement of opacity on N-type X-ray films: (1) the total energy of halo is approx. = 1000 TeV; (2) the shower transition reaches its maximum at approx. 16 cu; and (3) the radius of halo is 6.5 mm (at the level of 10 to the 6th power electrons/sq.cm.). The results in more details will be described

    A binocular-type atmospheric interaction generating sequential exotic features

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    A cosmic-ray induced nuclear event is presented, which is of clear binocular-type and contains several exotic features through its passage in the atmosphere and the emulsion chamber

    Atmospheric interactions detected in both the upper and the lower chambers at Chacaltaya

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    The cosmic ray interactions in the energy region 10 to the 13th power to 10 to the 17th power eV were studied by emulsion chambers exposed at Chacaltaya, 5220 m above sea-level. The chambers have a two-storied structure, and the events observed in both chambers give important informations on these phenomena. The first Centauro event was detected as a small shower at the bottom of the upper chamber and as a big fraction of energy deposit in the lower chamber, which indicates a high contribution of hadronic showers. Results of the events with continuation in the rather low energy region are described

    Threshold electronic structure at the oxygen K edge of 3d transition metal oxides: a configuration interaction approach

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    It has been generally accepted that the threshold structure observed in the oxygen K edge X-ray absorption spectrum in 3d transition metal oxides represents the electronic structure of the 3d transition metal. There is, however, no consensus about the correct description. We present an interpretation, which includes both ground state hybridization and electron correlation. It is based on a configuration interaction cluster calculation using a MO6 cluster. The oxygen K edge spectrum is calculated by annihilating a ligand hole in the ground state and is compared to calculations representing inverse photoemission experiments in which a 3d transition metal electron is added. Clear differences are observed related to the amount of ligand hole created in the ground state. Two "rules" connected to this are discussed. Comparison with experimental data of some early transition metal compounds is made and shows that this simple cluster approach explains the experimental features quite well.Comment: 10 pages, submitted to Phys. Rev. B, tried to make a better PS file

    Dynamical Gauge Symmetry Breaking in SU(3)L⊗U(1)XSU(3)_L\otimes U(1)_X Extension of the Standard Model

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    We study the SU(3)L⊗U(1)XSU(3)_L\otimes U(1)_X extension of the Standard model with a strong U(1) coupling. We argue that current experiments limit this coupling to be relatively large. The model is dynamically broken to the Standard SU(2)L⊗U(1)SU(2)_L \otimes U(1) model at the scale of a few TeV with all the extra gauge bosons and the exotic quarks acquiring masses much larger than the scale of electroweak symmetry breaking. Furthermore we find that the model leads to large dynamical mass of the top quark and hence also breaks the electroweak gauge symmetry. It therefore leads to large dynamical effects within the Standard model and can partially replace the Higgs interactions.Comment: 4 pages, revtex, no figures; revised version predicting realistic mass spectru

    Efecto de la aireación y la concentración de cloruro sódico en el desarrollo de la flora microbiológica y en los parámetros fisicoquímicos en la fermentación de Olea europaea L. c.v. Sevillana al estilo negras naturales en la zona de La Yarada-Tacna

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    The aerobic fermentation of the table olive variety, Sevillana a black style, was carried out, taking into account the parameters of fermentation of fixed acidity between 1.2 to 1.5% and depended on the chloride concentration in the brine. This concentration was under 6.5% in the 9 treatments assayed, allowing for the lactic bacteria to develop. In the aerobic fermentation there were no differences in the decline of pH in relation to the anaerobic fermentation, which reached values below 3.5. The air effect is of great significance in the purge of the carbon dioxide in the brine. At the same time, the effect of air significantly affects the increase in aerobic yeast. The facultative anaerobic yeasts developed in the treatments with an initial salt level of 12% at the beginning of fermentation. The reduction of sugar concentration into the fruit decreased significantly in the treatment with air. Aerobic fermentation is more rapid than anaerobic fermentation.La fermentación aerobia de aceituna variedad Sevillana estilo negra se desarrolló en los parámetros de acidez fija entre de 1.2 a 1.5%, debido a la concentración de cloruros en la salmuera los cuales se mantuvieron por debajo de 6.5% durante el periodo de fermentación en los 9 tratamientos ensayados lo que permitió el desarrollo de bacterias lácticas. No hubo diferencia en la evolución del pH entre la fermentación con aireación o en condiciones anaeróbicas alcanzándose valores menores a 3.5. La aireación tiene un efecto significativo en la purga del CO2 en la salmuera e incrementó la población de levaduras aerobias; así mismo en los tratamientos con 12% de sal se favoreció el desarrollo de levaduras fermentativas al inicio de la fermentación. La concentración de azúcares reductores en el fruto disminuyó significativamente en los tratamientos con aireación, acelerando el proceso de fermentación con respecto a la fermentación anaerobia

    Aerosol single scattering albedo dependence on biomass combustion efficiency: Laboratory and field studies

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    Single scattering albedo (ω) of fresh biomass burning (BB) aerosols produced from 92 controlled laboratory combustion experiments of 20 different woods and grasses was analyzed to determine the factors that control the variability in ω. Results show that ω varies strongly with fire-integrated modified combustion efficiency (MCEFI)—higher MCEFI results in lower ω values and greater spectral dependence of ω. A parameterization of ω as a function of MCEFI for fresh BB aerosols is derived from the laboratory data and is evaluated by field observations from two wildfires. The parameterization suggests that MCEFI explains 60% of the variability in ω, while the 40% unexplained variability could be accounted for by other parameters such as fuel type. Our parameterization provides a promising framework that requires further validation and is amenable for refinements to predict ω with greater confidence, which is critical for estimating the radiative forcing of BB aerosols

    Maintenance of glucose-sensitive insulin secretion of cryopreserved human islets with University of Wisconsin solution and ascorbic acid-2 glucoside

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    Normal human islet cells are an ideal source for pancreas-targeted cell therapies, but the availability of human donor pancreata for islet isolation is severely limited. To effectively utilize such scarce donor organs for cell therapies, it is crucial to develop an excellent isolation, effective cryopreservation, and efficient gene transfer techniques for the transportation of isolated cells. In the present study, we investigate the effect of University of Wisconsin (UW) solution and ascorbic acid-2 glucoside (AA2G) on the cryopreservation of human islets. We also evaluate the gene transfer efficiency of a lentiviral vector expressing the E. coli LacZ gene, Lt-NLS/LacZ, in human islets. Human islets were isolated with a standard digestion method at the University of Alberta. Isolated islets were transported to Japan for 40 h and then subjected to cryopreservation experiments. The following preservation solutions were tested: UW solution with 100 mug/mL of AA2G, UW solution, 100% fetal bovine serum (FBS), and CMRL supplemented with 10% FBS. Following three months of cryopreservation, the islets were thawed and analyzed for viability, glucose-sensitive insulin secretion, proinsulin gene expression profile, and in vivo engraftment. The islets were also subjected to monolayer formation with 804G-cell-line-derived extracellular matrix (ECM), followed by Lt-NLS/LacZ transduction. The viability, morphology, glucose-sensitive insulin secretion, proinsulin gene expression, and monolayer formation efficiency of the thawed cryopreserved islets are significantly better maintained by the use of UW solution. When AA2G (100 mug/mL) is combined with UW, such parameters are further improved. The adequate engraftment of UW + AA2G-cryopreserved human islets is achieved in the liver of nude mice. Efficient Lt-NLS/LacZ transduction is identified in monolayered islets cryopreserved with UW solution with AA2G. The present work demonstrates that the combination of UW solution with AA2G (100 mug/mL) would be a useful cryopreservation means for human islets. Human islets monolayer-cultured with 804G-derived ECM are efficiently transduced with a lentiviral vector Lt-NLS/LacZ
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