5,791 research outputs found
Correlation between electrons and vortices in quantum dots
Exact many-body wave functions for quantum dots containing up to four
interacting electrons are computed and we investigated the distribution of the
wave function nodes, also called vortices. For this purpose, we evaluate the
reduced wave function by fixing the positions of all but one electron and
determine the locations of its zeros. We find that the zeros are strongly
correlated with respect to each other and with respect to the position of the
electrons and formulate rules describing their distribution. No multiple zeros
are found, i.e. vortices with vorticity larger than one. Our exact calculations
are compared to results extracted from the recently proposed rotating electron
molecule (REM) wave functions
Model for the on-site matrix elements of the tight-binding hamiltonian of a strained crystal: Application to silicon, germanium and their alloys
We discuss a model for the on-site matrix elements of the sp3d5s*
tight-binding hamiltonian of a strained diamond or zinc-blende crystal or
nanostructure. This model features on-site, off-diagonal couplings between the
s, p and d orbitals, and is able to reproduce the effects of arbitrary strains
on the band energies and effective masses in the full Brillouin zone. It
introduces only a few additional parameters and is free from any ambiguities
that might arise from the definition of the macroscopic strains as a function
of the atomic positions. We apply this model to silicon, germanium and their
alloys as an illustration. In particular, we make a detailed comparison of
tight-binding and ab initio data on strained Si, Ge and SiGe.Comment: Submitted to Phys. Rev.
A fundamental test of the Higgs Yukawa coupling at RHIC in A+A collisions
Searches for the intermediate boson, , the heavy quantum of the Weak
Interaction, via its semi-leptonic decay, , in the 1970's instead
discovered unexpectedly large hadron production at high , notably ,
which provided a huge background of from internal and external
conversions. Methods developed at the CERN ISR which led to the discovery of
direct-single- 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
Ablation of an idiopathic left ventricular tachycardia originating from the posterior mitral annulus in a toddler
Ablation of a mitral annulus (MA)-ventricular tachycardia (VT), a rare form of idiopathic left VT, has not yet been described in patients <2 years of age. We describe a case of a toddler with an incessant, poorly tolerated idiopathic VT (190 bpm) refractory to medical therapy, which was successfully ablated in the left ventricle at the infero-posterior part of the MA. Different diagnostic and ablation steps are described. Mitral annulus-ventricular tachycardia, a rare form of idiopathic left VT, can safely and successfully be ablated in very young children
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
Open charm enhancement by secondary interactions in relativistic nucleus-nucleus collisions?
We calculate open charm production in reactions at SPS energies
within the HSD transport approach - which is based on string, quark, diquark
() and hadronic degrees of freedom - including
the production of open charm pairs from secondary 'meson'-'baryon' (or
quark-diquark and antiquark-diquark) collisions. It is argued that at collision
energies close to the pair threshold the dominant production
mechanism is related to the two body (or quasi two body) reactions . Estimates within the framework of
the Quark-Gluon String model suggest cross sections of a few for in the region of 1 GeV above threshold. The dynamical
transport calculations for at 160 AGeV indicate that the open
charm enhancement reported by the NA50 Collaboration might be due to such
secondary reaction mechanisms.Comment: 14 pages, LaTeX, including 5 postscript figures, submitted to Phys.
Lett.
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
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Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at √s = 8 TeV
A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from Hγγ decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events
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