106 research outputs found

    s-Process Nucleosynthesis in Carbon Stars

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    We present the first detailed and homogeneous analysis of the s-element content in Galactic carbon stars of N-type. Abundances of Sr,Y, Zr (low-mass s-elements, or ls) and of Ba, La, Nd, Sm and Ce (high-mass s-elements, hs) are derived using the spectral synthesis technique from high-resolution spectra. The N-stars analyzed are of nearly solar metallicity and show moderate s-element enhancements, similar to those found in S stars, but smaller than those found in the only previous similar study (Utsumi 1985), and also smaller than those found in supergiant post-AGB stars. This is in agreement with the present understanding of the envelope s-element enrichment in giant stars, which is increasing along the spectral sequence M-->MS-->S-->SC-->C during the AGB phase. We compare the observational data with recent ss-process nucleosynthesis models for different metallicities and stellar masses. Good agreement is obtained between low mass AGB star models (M < 3 M_o) and s-elements observations. In low mass AGB stars, the 13C(alpha, n)16O reaction is the main source of neutrons for the s-process; a moderate spread, however, must exist in the abundance of 13C that is burnt in different stars. By combining information deriving from the detection of Tc, the infrared colours and the theoretical relations between stellar mass, metallicity and the final C/O ratio, we conclude that most (or maybe all) of the N-stars studied in this work are intrinsic, thermally-pulsing AGB stars; their abundances are the consequence of the operation of third dredge-up and are not to be ascribed to mass transfer in binary systems.Comment: 31 pages, 10 figures, 6 tables. Accepted in Ap

    When Color meets Gravity; Near-Threshold Exclusive J/ψJ/\psi Photoproduction on the Proton

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    The proton is one of the main building blocks of all visible matter in the universe. Among its intrinsic properties are its electric charge, mass, and spin. These emerge from the complex dynamics of its fundamental constituents, quarks and gluons, described by the theory of quantum chromodynamics (QCD). Using electron scattering its electric charge and spin, shared among the quark constituents, have been the topic of active investigation until today. An example is the novel precision measurement of the proton's electric charge radius. In contrast, little is known about the proton's inner mass density, dominated by the energy carried by the gluons, which are hard to access through electron scattering since gluons carry no electromagnetic charge. In the present work we chose to probe this gluonic gravitational density using a small color dipole, the J/ψJ/\psi particle, through its threshold photoproduction. From our data we determined, for the first time, the proton's gluonic gravitational form factors, which encode its mass density. We used a variety of methods and determined in all cases a mass radius that is notably smaller than the electric charge radius. In some cases, the determined radius is in excellent agreement with first-principle predictions from lattice QCD. This work paves the way for a deeper understanding of the salient role of gluons in providing gravitational mass to visible matter.Comment: Under peer revie

    First Measurement of the EMC Effect in 10^{10}B and 11^{11}B

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    The nuclear dependence of the inclusive inelastic electron scattering cross section (the EMC effect) has been measured for the first time in 10^{10}B and 11^{11}B. Previous measurements of the EMC effect in A12A \leq 12 nuclei showed an unexpected nuclear dependence; 10^{10}B and 11^{11}B were measured to explore the EMC effect in this region in more detail. Results are presented for 9^9Be, 10^{10}B, 11^{11}B, and 12^{12}C at an incident beam energy of 10.6~GeV. The EMC effect in the boron isotopes was found to be similar to that for 9^9Be and 12^{12}C, yielding almost no nuclear dependence in the EMC effect in the range A=412A=4-12. This represents important, new data supporting the hypothesis that the EMC effect depends primarily on the local nuclear environment due to the cluster structure of these nuclei.Comment: Submitted to PR

    Pseudonocardia hispaniensis sp. nov., a novel actinomycete isolated from industrial wastewater activated sludge

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    A novel actinomycete, designated PA3T, was isolated from an oil refinery wastewater treatment plant, located in Palos de la frontera, Huelva, Spain, and characterized taxonomically by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate formed a distinct subclade in the Pseudonocardia tree together with Pseudonocardia asaccharolytica DSM 44247T. The chemotaxonomic properties of the isolate, for example, the presence of MK-8 (H4) as the predominant menaquinone and iso-C16:0 as the major fatty acid are consistent with its classification in the genus Pseudonocardia. DNA:DNA pairing experiments between the isolate and the type strain of P. asaccharolytica DSM 44247T showed that they belonged to separate genomic species. The two strains were readily distinguished using a combination of phenotypic properties. Consequently, it is proposed that isolate PA3T represents a novel species for which the name Pseudonocardia hispaniensis sp. nov. is proposed. The type strain is PA3T (= CCM 8391T = CECT 8030T).Cuesta Amat, G.; Soler Hernández, A.; Alonso Molina, JL.; Ruvira, M.; Lucena, T.; Arahal, D.; Goodfellow, M. (2013). Pseudonocardia hispaniensis sp. nov., a novel actinomycete isolated from industrial wastewater activated sludge. Antonie van Leeuwenhoek. 103(1):135-142. doi:10.1007/s10482-012-9792-1S1351421031Alonso JL, Cuesta G, Ramírez GW, Morenilla JJ, Bernácer I, Lloret RM (2009) Manual de técnicas avanzadas para la identificación y control de bacterias filamentosas. Epsar-Generalitat Valenciana, España, p 21–36Ara I, Tsetseg B, Daram D, Suto M, Ando K (2011) Pseudonocardia mongoliensis sp. nov. and Pseudonocardia khuvsgulensis sp. nov., isolated from soil. 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Int J Syst Evol Microbiol 60:2818–2822Kaewkla O, Franco CMM (2011) Pseudonocardia eucalypti sp. nov., an endophytic actinobacterium with a unique knobby spore surface, isolated from roots of a native Australian eucalyptus tree. Int J Syst Evol Microbiol 61:742–746Kämpfer P, Kohlweyer U, Thiemer B, Andreesen JR (2006) Pseudonocardia tetrahydrofuranoxydans sp. nov. Int J Syst Evol Microbiol 56:1535–1538Labeda DP, Goodfellow M, Chun J, Zhi XY, Li WJ (2011) Reassessment of the systematics of the suborder Pseudonocardineae: transfer of genera within the family Actinosynnemataceae Labeda and Kroppenstedt 2000 emend. Zhi et al. 2009 into an emended family Pseudonocardiaceae Embley et al. 1989 emend. Zhi et al. 2009. Int J Syst Evol Microbiol 61:1259–1264Lane DJ (1991) 16S/23S rRNA sequencing. In: Stackebrandt E, Goodfellow M (eds) Nucleic acid techniques in bacterial systematics. Wiley, Chichester, pp 115–148Lechevalier MP, Lechevalier H (1970) Chemical composition as a criterion in the classification of aerobic actinomycetes. Int J Syst Bacteriol 20:435–443Lechevalier MP, Stern AER, Lechevalier HA (1981) Phospholipids in the taxonomy of actinomycetes. Zbl Bakt Suppl 11:111–116Li J, Zhao GZ, Huang HY, Zhu WY, Lee JC, Kim CJ, Xu LH, Zhang LX, Li WJ (2010) Pseudonocardia rhizophila sp. nov., a novel actinomycete isolated from a rhizosphere soil. Antonie Van Leeuwenhoek 98:77–83Liu ZP, Wu JF, Liu ZH, Liu SJ (2006) Pseudonocardia ammonioxydans sp. nov., isolated from coastal sediment. Int J Syst Evol Microbiol 56:555–558Lucena T, Pascual J, Garay E, Arahal DR, Macián MC, Pujalte MJ (2010) Haliea mediterranea sp. nov., a new marine gammaproteobacterium. Int J Syst Evol Microbiol 60:1844–1848Ludwig W et al (2004) ARB: a software environment for sequence data. Nucleic Acids Res 32:1363–1371Mahendra S, Alvarez-Cohen L (2005) Pseudonocardia dioxanivorans sp. nov., a novel actinomycete that grows on 1,4-dioxane. Int J Syst Evol Microbiol 55:593–598Mesbah M, Premachandran U, Whitman WB (1989) Precise measurement of the G+C content of deoxyribonucleic acid by high-performance liquid chromatography. Int J Syst Bacteriol 39:159–167MIDI (2008) Sherlock microbial identification system operating manual, version 6.1. MIDI Inc., NewarkMinnikin DE, O’Donnell AG, Goodfellow M, Alderson G, Athalye M, Schaal A, Parlett JH (1984) An integrated procedure for the extraction of isoprenoid quinones and polar lipids. J Microbiol Methods 2:233–241Nam S-W, Chun J, Kim S, Kim W, Zakrzewska-Czerwinska J, Goodfellow M (2003) Tsukamurella spumae sp. nov., a novel actinomycete associated with foaming in activated sludge plants. Syst Appl Microbiol 26:367–375Okoh A, Ajisebutu S, Babalola G, Trejo-Hernandez MR (2001) Potential of Burkholderia cepacia RQ1 in the biodegradation of heavy crude oil. Int Microbiol 4:83–87Park SW, Park ST, Lee JE, Kim YM (2008) Pseudonocardia carboxydivorans sp. nov., a carbon monoxide-oxidizing actinomycete, and an emended description of the genus Pseudonocardia. Int J Syst Evol Microbiol 58:2475–2478Pruesse E, Quast C, Knittel K, Fuchs B, Ludwig W, Peplies J, Glöckner FO (2007) SILVA: a comprehensive online resource for quality checked and aligned ribosomal RNA sequence data compatible with ARB. Nucleic Acids Res 35:7188–7196Qin S, Su YY, Zhang YQ, Wang HB, Jiang CL, Xu LH, Li WJ (2008) Pseudonocardia ailaonensis sp. nov., isolated from soil in China. Int J Syst Evol Microbiol 58:2086–2089Qin S, Zhu WY, Jiang JH, Klenk HP, Li J, Zhao GZ, Xu LH, Li WJ (2010) Pseudonocardia tropica sp. nov., an endophytic actinomycete isolated from the stem of Maytenus austroyunnanensis. Int J Syst Evol Microbiol 60:2524–2528Qin S, Xing K, Fei SM, Lin Q, Chen XM, Li WJ, Jiang JH (2011) Pseudonocardia sichuanensis sp. nov., a novel endophytic actinomycete isolated from the root of Jatropha curcus L. Antonie Van Leeuwenhoek 99:395–401Rehfuss M, Urban J (2005) Rhodococcus phenolicus sp. nov., a novel bioprocessor isolated actinomycete with the ability to degrade chlorobenzene, dichlorobenzene and phenol as sole carbon sources. Syst Appl Microbiol 28:695–701Reichert K, Lipski A, Pradella S, Stackebrandt E, Altendorf K (1998) Pseudonocardia asaccharolitica sp. nov. and Pseudonocardia sulfidoxidans sp. nov., two new dimethyl disulfide-degrading actinomycetes and emended description of the genus Pseudonocardia. Int J Syst Bacteriol 48:441–449Sakiyama Y, Thao NKN, Vinh HV, Giang NM, Miyadoh S, Hop DV, Ando K (2010) Pseudonocardia babensis sp. nov., isolated from plant litter. 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Syst Appl Microbiol 33:291–299Zhao GZ, Li J, Zhu WY, Li XP, Tian SZ, Zhao LX, Xu LH, Li WJ (2011a) Pseudonocadia bannaensis sp. nov., a novel actinomycete isolated from the surface-sterilized roots of Artemisiae annua L. Antonie Van Leeuwenhoek 100:35–42Zhao GZ, Li J, Huang HY, Zhu WY, Zhao LX, Tang SK, Xu LH, Li WJ (2011b) Pseudonocardia artemisiae sp. nov., isolated from surface-sterilized Artemisia annua L. Int J Syst Evol Microbiol 61:1061–1065Zhao GZ, Li J, Huang HY, Zhu WY, Park DJ, Kim CJ, Xu LH, Li WJ (2011c) Pseudonocardia kunmingensis sp. nov., an actinobacterium isolated from surface-sterilized roots of Artemisia annua L. Int J Syst Evol Microbiol 61:2292–229

    Beam-target helicity asymmetry e in K0 Λ and K0 Σ0 photoproduction on the neutron

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    We report the first measurements of the E beam-target helicity asymmetry for the γ - n - →K0Λ and K0Σ0 channels in the energy range 1.70≤W≤2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. The multivariate analysis method boosted decision trees is used to isolate the reactions of interest. Comparisons with predictions from the KaonMAID, SAID, and Bonn-Gatchina models are presented. These results will help separate the isospin I=0 and I=1 photocoupling transition amplitudes in pseudoscalar meson photoproduction
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