3,250 research outputs found

    Self-consistent quantum effects in the quark meson coupling model

    Full text link
    We derive the equation of state of nuclear matter including vacuum polarization effects arising from the nucleons and the sigma mesons in the quark-meson coupling model which incorporates explicitly quark degrees of freedom with quark coupled to the scalar and vector mesons. This leads to a softer equation of state for nuclear matter giving a lower value of incompressibility than would be reached without quantum effects. The {\it in-medium} nucleon and sigma meson masses are also calculated in a self-consistent manner.Comment: 10 pages, latex, 5 figure

    Dileptons from a Quark Gluon Plasma with Finite Baryon Density

    Get PDF
    We investigate the effects of a baryon-antibaryon asymmetry on the spectrum of dileptons radiating from a quark gluon plasma. We demonstrate the existence of a new set of processes in this regime. The dilepton production rate from the corresponding diagrams is shown to be as important as that obtained from the usual quark-antiquark annihilation.Comment: 20 pages, 5 figures, REVTEX. Typos corrected, references added. Version accepted for publication in Physical Review

    Security challenges of small cell as a service in virtualized mobile edge computing environments

    Get PDF
    Research on next-generation 5G wireless networks is currently attracting a lot of attention in both academia and industry. While 5G development and standardization activities are still at their early stage, it is widely acknowledged that 5G systems are going to extensively rely on dense small cell deployments, which would exploit infrastructure and network functions virtualization (NFV), and push the network intelligence towards network edges by embracing the concept of mobile edge computing (MEC). As security will be a fundamental enabling factor of small cell as a service (SCaaS) in 5G networks, we present the most prominent threats and vulnerabilities against a broad range of targets. As far as the related work is concerned, to the best of our knowledge, this paper is the first to investigate security challenges at the intersection of SCaaS, NFV, and MEC. It is also the first paper that proposes a set of criteria to facilitate a clear and effective taxonomy of security challenges of main elements of 5G networks. Our analysis can serve as a staring point towards the development of appropriate 5G security solutions. These will have crucial effect on legal and regulatory frameworks as well as on decisions of businesses, governments, and end-users

    Versatile transporter apparatus for experiments with optically trapped Bose-Einstein condensates

    Full text link
    We describe a versatile and simple scheme for producing magnetically and optically-trapped Rb-87 Bose-Einstein condensates, based on a moving-coil transporter apparatus. The apparatus features a TOP trap that incorporates the movable quadrupole coils used for magneto-optical trapping and long-distance magnetic transport of atomic clouds. As a stand-alone device, this trap allows for the stable production of condensates containing up to one million atoms. In combination with an optical dipole trap, the TOP trap acts as a funnel for efficient loading, after which the quadrupole coils can be retracted, thereby maximizing optical access. The robustness of this scheme is illustrated by realizing the superfluid-to-Mott insulator transition in a three-dimensional optical lattice

    Hydrodynamic Modes in a Trapped Strongly Interacting Fermi Gases of Atoms

    Full text link
    The zero-temperature properties of a dilute two-component Fermi gas in the BCS-BEC crossover are investigated. On the basis of a generalization of the variational Schwinger method, we construct approximate semi-analytical formulae for collective frequencies of the radial and the axial breathing modes of the Fermi gas under harmonic confinement in the framework of the hydrodynamic theory. It is shown that the method gives nearly exact solutions.Comment: 11 page

    Thermometry with spin-dependent lattices

    Full text link
    We propose a method for measuring the temperature of strongly correlated phases of ultracold atom gases confined in spin-dependent optical lattices. In this technique, a small number of "impurity" atoms--trapped in a state that does not experience the lattice potential--are in thermal contact with atoms bound to the lattice. The impurity serves as a thermometer for the system because its temperature can be straightforwardly measured using time-of-flight expansion velocity. This technique may be useful for resolving many open questions regarding thermalization in these isolated systems. We discuss the theory behind this method and demonstrate proof-of-principle experiments, including the first realization of a 3D spin-dependent lattice in the strongly correlated regime.Comment: 22 pages, 8 figures v2: Several references added; Section on heating rates updated to include dipole fluctuation terms; Section added on the limitations of the proposed method. To appear in New Journal of Physic

    Mental health challenges associated with adaptation and acculturation among international students studying in Scotland

    Get PDF
    Research has yet to explore the understandings and experiences of mental health, disclosure and help-seeking drawing upon international students' perspectives within the Scottish context. A series of studies were carried out using a multi-method approach including in-depth qualitative interviews with international students studying in Scotland and cross-sectional online surveys comparing domestic and international students in terms of mental health literacy, disclosure and help seeking behaviour. Qualitative data analysed using a thematic approach revealed that adaptation and acculturation difficulties, negative beliefs, stigma and fear of judgement adversely impacted on international students' mental health. Descriptive and inferential statistical analysis of the survey data showed that mental health literacy was positively associated with psychological adaptation, and lower stigma was positively associated with help seeking intention among international students. Supporting international students involves addressing the challenges and barriers in overcoming adaptation and acculturation difficulties that may inhibit disclosure and help seeking for mental health problems

    Simulation of the many-body dynamical quantum Hall effect in an optical lattice

    Get PDF
    We propose an experimental scheme to simulate the many-body dynamical quantum Hall effect with ultra-cold bosonic atoms in a one-dimensional optical lattice. We first show that the required model Hamiltonian of a spin-1/2 Heisenberg chain with an effective magnetic field and tunable parameters can be realized in this system. For dynamical response to ramping the external fields, the quantized plateaus emerge in the Berry curvature of the interacting atomic spin chain as a function of the effective spin-exchange interaction. The quantization of this response in the parameter space with the interaction-induced topological transition characterizes the many-body dynamical quantum Hall effect. Furthermore, we demonstrate that this phenomenon can be observed in practical cold-atom experiments with numerical simulations.Comment: 8 pages, 3 figures; accepted in Quantum Information Processin
    corecore