Accuracy of the Hartree-Fock method for Wigner molecules at high magnetic fields

Few-electron systems confined in two-dimensional parabolic quantum dots at high magnetic fields are studied by the Hartree-Fock (HF) and exact diagonalization methods. A generalized multicenter Gaussian basis is proposed in the HF method. A comparison of the HF and exact results allows us to discuss the relevance of the symmetry of the charge density distribution for the accuracy of the HF method. It is shown that the energy estimates obtained with the broken-symmetry HF wave functions become exact in the infinite magnetic-field limit. In this limit the charge density of the broken-symmetry solution can be identified with the classical charge distribution.Comment: to appear in EPJ

Microborings in mid Cretaceous fish teeth

Fish teeth and other remains from the British Cretaceous contain abundant evidence for post-mortem colonization by endolithic organisms. The borings are here recognised as occurring in three morphotypes, including a flask-shaped form not previously recorded. There is strong evidence to suggest that each of these boring types shows a strong preference for a particular substrate histology. The damage and destruction of vertebrate remains by microborings is here considered to exert a major taphonomic control on microvertebrate assemblages. The relationships between the intensity of colonization of vertebrate material by endolithic organisms and palaeoenvironment have implications for using these bone microborings as palaeoenvironmental indicators

A fundamental test of the Higgs Yukawa coupling at RHIC in A+A collisions

Searches for the intermediate boson, $W^{\pm}$, the heavy quantum of the Weak Interaction, via its semi-leptonic decay, $W\to e +\nu$, in the 1970's instead discovered unexpectedly large hadron production at high $p_T$, notably $\pi^0$, which provided a huge background of $e^{\pm}$ from internal and external conversions. Methods developed at the CERN ISR which led to the discovery of direct-single-$e^{\pm}$ in 1974, later determined to be from the semi-leptonic decay of charm which had not yet been discovered, were used by PHENIX at RHIC to make precision measurements of heavy quark production in p-p and Au+Au collisions, leading to the puzzle of apparent equal suppression of light and heavy quarks in the QGP. If the Higgs mechanism gives mass to gauge bosons but not to fermions, then a proposal that all 6 quarks are nearly massless in a QGP, which would resolve the puzzle, can not be excluded. This proposal can be tested with future measurements of heavy quark correlations in A+A collisionsComment: 12 pages, 16 figures, 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica WI, January 2-9, 2010. Corrected citation of 1974 direct single lepton discover

Determinants of ageism against older adults: a systematic review

Ageism is a widespread phenomenon and constitutes a significant threat to older people’s well-being. Identifying the factors contributing to ageism is critical to inform policies that minimise its societal impact. In this systematic review, we gathered and summarised empirical studies exploring the key determinants of ageism against older people for a period of over forty years (1970–2017). A comprehensive search using fourteen databases identified all published records related to the umbrella concept of “ageism”. Reviewers independently screened the final pool to identify all papers focusing on determinants, according to a predefined list of inclusion and exclusion criteria. All relevant information was extracted and summarised following a narrative synthesis approach. A total of 199 papers were included in this review. We identified a total of 14 determinants as robustly associated with ageism. Of these, 13 have an effect on other-directed ageism, and one on self-directed ageism. The quality of contact with older people and the positive or negative presentation of older people to others emerged as the most robust determinants of other-directed ageism; self-directed ageism is mostly determined by older adults’ health status. Given the correlational nature of most studies included in this review, inferences on causality should be made cautiously.info:eu-repo/semantics/publishedVersio

Nuclear suppression of heavy quark production at forward rapidities in relativistic heavy ion collisions

We calculate nuclear suppression $R_{AA}$ of heavy quarks produced from the initial fusion of partons in nucleus-nucleus collisions at RHIC and LHC energies. We take the shadowing as well as the energy loss suffered by them while passing through Quark Gluon Plasma into account. We obtain results for charm and bottom quarks at several rapidities using different mechanisms for energy loss, to see if we can distinguish between them.Comment: 21 pages including 13 figures. To appear in J. Phys.

Validation of 3D Model-Based Maximum-Likelihood Estimation of Normalisation Factors for Partial Ring Positron Emission Tomography

The next generation of organ specific Positron Emission Tomography (PET) scanners, e.g. for breast imaging, will use partial ring geometries. We propose a component-based Maximum-Likelihood (ML) estimation of normalisation factors for 3D PET data reconstruction applicable to partial ring geometries. This method is based on the Software for Tomographic Image Reconstruction (STIR) for full ring PET and is validated for a stationary partial ring scanner. The model includes the estimation for crystal efficiencies and geometric factors. The algorithm is validated using Maximum Likelihood Estimation Method (MLEM) based 3D reconstruction in STIR using Geant4 Application for Tomographic Emission (GATE) simulation data for full and partial ring scanners and experimental data from a demonstrator with partial ring geometry. The uniformity of the reconstructed images of simulated cylindrical and NEMAIQ phantoms in both scanner geometries and the image of a line source in the partial ring demonstrator is assessed. The results have shown that uniform images in both axial and transaxial directions are obtained after applying the estimated normalisation factors. The accuracy of the algorithm is validated by comparing the normalisation factors between the full and partial ring systems in simulation. We have shown that the estimated normalisation factors are almost identical, even though the separate components are not. This proves that the ML estimation of the 3D normalisation factors is valid and can be applied to the partial ring scanner

DevOps for network function virtualisation: an architectural approach

The Service Programming and Orchestration for Virtualised Software Networks (SONATA) project targets both the flexible programmability of software networks and the optimisation of their deployments by means of integrating Development and Operations in order to accelerate industry adoption of software networks and reduce time-to-market for networked services. SONATA supports network function chaining and orchestration, making service platforms modular and easier to customise to the needs of different service providers, and introduces a specialised Development and Operations model for supporting developers

Measurement of jet multiplicity distributions in [Formula: see text] production in pp collisions at [Formula: see text].

The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7[Formula: see text] at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton+jets decay channels using data corresponding to an integrated luminosity of 5.0[Formula: see text]. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the [Formula: see text] production is determined as a function of the additional jet multiplicity in the lepton+jets channel. Furthermore, the fraction of events with no additional jets is measured in the dilepton channel, as a function of the threshold on the jet transverse momentum. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed