12,499 research outputs found

    Production of large transverse momentum dileptons and photons in pppp, dAdA and AAAA collisions by photoproduction processes

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    The production of large PTP_{T} dileptons and photons originating from photoproduction processes in pppp, dAdA and AAAA collisions is calculated. We find that the contribution of dileptons and photons produced by photoproduction processes is not prominent at RHIC energies. However, the numerical results indicate that the modification of photoproduction processes becomes evident in the large PTP_{T} region for pppp, dAdA and AAAA collisions at LHC energies.Comment: 10 figure

    Tunable electronic anisotropy in single-crystal A2Cr3As3 (A = K, Rb) quasi-one-dimensional superconductors

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    Single crystals of A2Cr3As3 (A = K, Rb) were successfully grown using a self-flux method and studied via structural, transport and thermodynamic measurement techniques. The superconducting state properties between the two species are similar, with critical temperatures of 6.1 K and 4.8 K in K2Cr3As3 and Rb2Cr3As3, respectively. However, the emergence of a strong normal state electronic anisotropy in Rb2Cr3As3 suggests a unique electronic tuning parameter is coupled to the inter-chain spacing in the A2Cr3As3 structure, which increases with alkali metal ionic size while the one-dimensional [(Cr3As3)^{2-}]_{\infty} chain structure itself remains essentially unchanged. Together with dramatic enhancements in both conductivity and magnetoresistance (MR), the appearance of a strong anisotropy in the MR of Rb2Cr3As3 is consistent with the proposed quasi-one-dimensional character of band structure and its evolution with alkali metal species in this new family of superconductors.Comment: 6 pages, 8 figures; to appear in Phys. Rev.

    Acoustically evoked potentials in two cephalopods inferred using the auditory brainstem response (ABR) approach

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    It is still a matter of debate whether cephalopods can detect sound frequencies above 400 Hz. So far there is no proof for the detection of underwater sound above 400 Hz via a physiological approach. The controversy of whether cephalopods have a sound detection ability above 400 Hz was tested using the auditory brainstem response (ABR) approach, which has been successfully applied in fish, crustaceans, amphibians, reptiles and birds. Using ABR we found that auditory evoked potentials can be obtained in the frequency range 400 to 1500 Hz (Sepiotheutis lessoniana) and 400 to 1000 Hz (Octopus vulgaris), respectively. The thresholds of S. lessoniana were generally lower than those of O. vulgaris

    Correlated Photons from Collective Excitations of Three-Level Atomic Ensemble

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    We systematically study the interaction between two quantized optical fields and a cyclic atomic ensemble driven by a classic optical field. This so-called atomic cyclic ensemble consists of three-level atoms with Delta-type transitions due to the symmetry breaking, which can also be implemented in the superconducting quantum circuit by Yu-xi Liu et al. [Phys. Rev. Lett. 95, 087001 (2005)]. We explore the dynamic mechanisms to creating the quantum entanglements among photon states, and between photons and atomic collective excitations by the coherent manipulation of the atom-photon system. It is shown that the quantum information can be completely transferred from one quantized optical mode to another, and the quantum information carried by the two quantized optical fields can be stored in the collective modes of this atomic ensemble by adiabatically controlling the classic field Rabi frequencies.Comment: 10 pages, 2 figure

    Scaling of Anisotropic Flows and Nuclear Equation of State in Intermediate Energy Heavy Ion Collisions

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    Elliptic flow (v2v_2) and hexadecupole flow (v4v_4) of light clusters have been studied in details for 25 MeV/nucleon 86^{86}Kr + 124^{124}Sn at large impact parameters by Quantum Molecular Dynamics model with different potential parameters. Four parameter sets which include soft or hard equation of state (EOS) with/without symmetry energy term are used. Both number-of-nucleon (AA) scaling of the elliptic flow versus transverse momentum (ptp_t) and the scaling of v4/A2v_4/A^{2} versus (pt/A)2(p_t/A)^2 have been demonstrated for the light clusters in all above calculation conditions. It was also found that the ratio of v4/v22v_4/{v_2}^2 keeps a constant of 1/2 which is independent of ptp_t for all the light fragments. By comparisons among different combinations of EOS and symmetry potential term, the results show that the above scaling behaviors are solid which do not depend the details of potential, while the strength of flows is sensitive to EOS and symmetry potential term.Comment: 5 pages, 5 figure

    Cloning and Expression of the PHA Synthase Gene From a Locally Isolated Chromobacterium sp. USM2

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    Chromobacterium sp. USM2, a locally isolated bacterium was found to synthesize poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV) copolymer with high 3HV monomer composition. The PHA synthase gene was cloned and expressed in Cupriavidus necator PHB¯4 to investigate the possibilities of incorporating other monomer. The recombinant successfully incorporated 3-hydroxyhexanoate (3HHx) monomer when fed with crude palm kernel oil (CPKO) as the sole carbon source. Approximately 63 ± 2 wt% of P(3HB-co-3HHx) copolymer with 4 mol% of 3HHx was synthesized from 5 g/L of oil after 48 h of cultivation. In addition, P(3HB-co-3HV-co-3HHx) terpolymer with 9 mol% 3HV and 4 mol% 3HHx could be synthesized with a mixture of CPKO and sodium valerate. The presence of 3HV and 3HHx monomers in the copolymer and terpolymer was further confirmed with +H-NMR analysis. This locally isolated PHA synthase has demonstrated its ability to synthesize P(3HB-co-3HHx) copolymer from a readily available and renewable carbon source; CPKO, without the addition of 3HHx precursors

    Effects of communication and utility-based decision making in a simple model of evacuation

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    We present a simple cellular automaton based model of decision making during evacuation. Evacuees have to choose between two different exit routes, resulting in a strategic decision making problem. Agents take their decisions based on utility functions, these can be revised as the evacuation proceeds, leading to complex interaction between individuals and to jamming transitions. The model also includes the possibility to communicate and exchange information with distant agents, information received may affect the decision of agents. We show that under a wider range of evacuation scenarios performance of the model system as a whole is optimal at an intermediate fraction of evacuees with access to communication.Comment: 9 pages, 9 figure

    Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows

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    In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effect of the momentum dependence of nuclear symmetry potential on nuclear transverse and elliptic flows in the neutron-rich reaction 132^{132}Sn+124^{124}Sn at a beam energy of 400 MeV/nucleon is studied. We find that the momentum dependence of nuclear symmetry potential affects the rapidity distribution of the free neutron to proton ratio, the neutron and the proton transverse flows as a function of rapidity. The momentum dependence of nuclear symmetry potential affects the neutron-proton differential transverse flow more evidently than the difference of neutron and proton transverse flows as well as the difference of proton and neutron elliptic flows. It is thus better to probe the symmetry energy by using the difference of neutron and proton flows since the momentum dependence of nuclear symmetry potential is still an open question. And it is better to probe the momentum dependence of nuclear symmetry potential by using the neutron-proton differential transverse flow and the rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ
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