287 research outputs found

    Angular anisotropy of the fusion-fission and quasifission fragments

    Full text link
    The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the 16^{16}O+238^{238}U, 19^{19}F+208^{208}Pb and 32^{32}S+208^{208}Pb reactions is studied by analyzing the angular momentum distributions of the dinuclear system and compound nucleus which are formed after capture and complete fusion, respectively. The orientation angles of axial symmetry axes of colliding nuclei to the beam direction are taken into account for the calculation of the variance of the projection of the total spin onto the fission axis. It is shown that the deviation of the experimental angular anisotropy from the statistical model picture is connected with the contribution of the quasifission fragments which is dominant in the 32^{32}S+208^{208}Pb reaction. Enhancement of anisotropy at low energies in the 16^{16}O+238^{238}U reaction is connected with quasifission of the dinuclear system having low temperature and effective moment of inertia.Comment: 17 pages 8 figures. Submitted to Euro. Phys. Jour.

    A High-Resolution GSO-based Brain PET Camera

    Get PDF
    ABSTRACT A high-resolution GSO-based PET camera is being developed for brain imaging. The system is based upon a detector that uses Anger-logic positioning with 4 x 4 x 10 mm3 crystals coupled to a continuous light-guide and an array of 39-mm diameter photo-multiplier tubes. Measurements of a small crystal array have demonstrated that individual crystals can be resolved. The system is 3D (no septa) with a diameter of 42 cm and an axial field-of-view of 25 cm. The detector and overall scanner design has been guided by Monte Carlo simulations. The GSO PET scanner will have improved spatial resolution and higher count-rate capability than the NaI (TI) HEAD Penn-PET scanner that was built previously. GSO was chosen because of its higher stopping power, faster decay, and excellent energy resolution, which is critical for good scatter rejection

    A CI-Independent Form of Replicative Inhibition: Turn Off of Early Replication of Bacteriophage Lambda

    Get PDF
    Several earlier studies have described an unusual exclusion phenotype exhibited by cells with plasmids carrying a portion of the replication region of phage lambda. Cells exhibiting this inhibition phenotype (IP) prevent the plating of homo-immune and hybrid hetero-immune lambdoid phages. We have attempted to define aspects of IP, and show that it is directed to repλ phages. IP was observed in cells with plasmids containing a λ DNA fragment including oop, encoding a short OOP micro RNA, and part of the lambda origin of replication, oriλ, defined by iteron sequences ITN1-4 and an adjacent high AT-rich sequence. Transcription of the intact oop sequence from its promoter, pO is required for IP, as are iterons ITN3–4, but not the high AT-rich portion of oriλ. The results suggest that IP silencing is directed to theta mode replication initiation from an infecting repλ genome, or an induced repλ prophage. Phage mutations suppressing IP, i.e., Sip, map within, or adjacent to cro or in O, or both. Our results for plasmid based IP suggest the hypothesis that there is a natural mechanism for silencing early theta-mode replication initiation, i.e. the buildup of λ genomes with oop+ oriλ+ sequence

    Explaining state development: Indonesia from its pre-independence origins to contemporary democracy.

    Get PDF
    Explaining State Development: Indonesia from Pre-Independence Origins to Contemporary Democracy. This thesis uses the Indonesian case to present a new paradigm for explaining the state development of new or relatively new (post-World War II) states. The first chapter describes this paradigm of organic and mechanical types of state development, argues that the development of the Indonesian state from the 1950s to 1990s is a good example of the mechanical type of development and shows how this can be confirmed by assessing and comparing the capabilities of the four different versions of a modern state developed by Indonesia since independence. The next chapter examines Indonesia’s pre-independence debates about the form of state to be adopted, which led to Indonesia accepting a Western model of the state that has since undergone a development process involving four different versions of a ‘modern’ state. These four versions of the state are defined according to their type of regime and policymaking institutions: I) parliamentary democracy, II) Sukarno’s civilian presidential monarchy, III) Suharto’s military presidential monarchy and IV) presidential democracy. Chapters Three to Six assess and compare these four versions’ capability in three key areas: 1) achieving legal legitimacy, 2) control of the military and 3) dealing with political disorder – a crucial area of state capability that requires two chapters. Then Chapter Seven examines and explains the pre-democratic origins of the present version of the Indonesian state, the presidential democracy of Version IV. The Conclusion collates the findings of Chapters Three to Six on capabilities and summarises the arguments of Chapters Two and Seven regarding the 1940s acceptance of the Western model of the state and the late 1990s opportunity for democratisation. Finally, there is a concluding assessment of the potential of the organic/mechanical typology as a new paradigm for studying state development in other countries, regions and eras

    A General Catalyst Based on Cobalt Core–Shell Nanoparticles for the Hydrogenation of N‐Heteroarenes Including Pyridines

    No full text
    Herein, we report the synthesis of specific silica-supported Co/Co3O4 core–shell based nanoparticles prepared by template synthesis of cobalt-pyromellitic acid on silica and subsequent pyrolysis. The optimal catalyst material allows for general and selective hydrogenation of pyridines, quinolines, and other heteroarenes including acridine, phenanthroline, naphthyridine, quinoxaline, imidazo[1,2-a]pyridine, and indole under comparably mild reaction conditions. In addition, recycling of these Co nanoparticles and their ability for dehydrogenation catalysis are showcased. © 2020 The Authors. Published by Wiley-VCH Gmb
    corecore