35 research outputs found

    Fusion-Fission of 16O+197Au at Sub-Barrier Energies

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    The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16O+197Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies.Comment: Fusion06 - Intl. Conf. on Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier, San Servolo, Venezia, Italy, March 19-223, 2006 5 pages, 4 figure

    Mitochondrial DNAs of Suillus: three fold size change in molecules that share a common gene order

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    We constructed restriction-site and gene maps for mitochondrial DNAs from seven isolates of five species of Suillus (Boletaceae, Basidiomycotina). Each mitochondrial genome exists as a single circular chromosome, ranging in size from 36 to 121 kb. Comparisons within species and between two closely related species revealed that insertions and deletions are the major form of genome change, whereas most restriction sites are conserved. Among more distantly related species, size and restriction-site differences were too great to allow precise alignments of maps, but small clusters of putatively homologous restriction sites were found. Two mitochondrial gene orders exist in the five species. These orders differ only by the relative positions of the genes for ATPase subunit 9 and the small ribosomal RNA and are interconvertible by a single transposition. One of the two gene arrangements is shared by four species whose mitochondrial DNAs span the entire size range of 36 to 121 kb. The conservation of gene order in molecules that vary over three-fold in size and share few restriction sites demonstrates a low frequency of rearrangements relative to insertions, deletions, and base substitutions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46963/1/294_2004_Article_BF00365756.pd

    Location and structure of the var1 gene on yeast mitochondrial DNA: Nucleotide sequence of the 40.0 allele

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    Alleles of the var1 locus on yeast mitochondrial DNA specify the size of var1 ribosomal protein. We report the nucleotide sequence of a var1 allele that determines the smallest var1 protein. It contains an open reading frame of 396 codons, which we identify as the structural gene for var1 protein. The var1 protein specified by this allele has an amino acid composition in close agreement with that predicted by the DNA sequence. The var1 coding region is highly unusual: it is 89.6% AT and contains a 46 bp GC-rich palindromic cluster that accounts for 38% of the total GC residues. Our results strongly suggest that like mammalian mitochondria but unlike those from Neurospora, yeast mitochondria use AUA as a methionine codon. Comparison with the sequence of a var1 allele specifying a larger protein suggests that some size polymorphism of var1 protein results from in-frame insertions of a variable number of AAT (Asn) codons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23885/1/0000124.pd

    Experimental limits on nucleon decay and ΔB=2 processes

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    Results from the IMB collabration to detect possible proton decay in a salt mine near Cleveland, Ohio are presented. Detection apparatus is described.(AIP)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87900/2/1_1.pd

    Independent Submission Request for Comments: 5456

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    IAX: Inter-Asterisk eXchange Version 2 This document describes IAX, the Inter-Asterisk eXchange protocol, an application-layer control and media protocol for creating, modifying, and terminating multimedia sessions over Internet Protocol (IP) networks. IAX was developed by the open source community for the Asterisk Private Branch Exchange (PBX) and is targeted primarily at Voice over Internet Protocol (VoIP) call control, but it can be used with streaming video or any other type of multimedia. IAX is an "all in one " protocol for handling multimedia in IP networks. It combines both control and media services in the same protocol. In addition, IAX uses a single UDP data stream on a static port greatly simplifying Network Address Translation (NAT) gateway traversal, eliminating the need for other protocols to work around NAT, and simplifying network and firewall management. IAX employs a compact encoding that decreases bandwidth usage and is well suited for Internet telephony service. In addition, its open nature permits new payload type additions needed to support additional services. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not a candidate for any level of Interne

    The IMB nucleon decay detector data acquisition and triggering system

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    The data acquisition hardware and software for a large deep underground nucleon stability detector is described. Such hardware must process the information from an array of greater than 2000 photomultiplier tubes in real time, in the presence of a cosmic-ray background of about three events per second. A hierarchical scheme of processors and memory is used to perform real time pattern recognition and event identification with negligible impact on dead time. Fast, but crude, algorithms have been developed to reduce the offline analysis work load without endangering any of the alternative physics objectives, such as neutrino oscillations or neutrino burst detection. (8 refs)