Top quark mass measurement with soft muons from b-hadron decay

The top quark mass has been measured with several methods. In this paper a method based on the Soft Muon Tagging is discussed; which relies on the identification of a muon in the semileptonic decays of hadrons originating from the hadronisation of the b (anti-b) quark coming from the top (anti-top) decay (t → Wb). By reconstructing the invariant mass of the soft muon and the prompt lepton coming from the leptonic W decay, it is possible to extract the top quark mass. This measurement is being developed for Run-2 data collected with the ATLAS detector at the LHC

Integrity constraints in logic databases

AbstractWe consider logic databases as logic programs and suggest how to deal with the problem of integrity constraint checking. Two methods for integrity constraint handling are presented. The first one is based on a metalevel consistency proof and is particularly suitable for an existing database which has to be checked for some integrity constraints. The second method is based on a transformation of the logic program which represents the database into a logic program which satisfies the given integrity constraints. This method is specially suggested for databases that have to be built specifying, separately, which are the deductive rules and the facts and which are the integrity constraints on a specific relation. Different tools providing for the two mechanisms are proposed for a flexible logic database management system

Nanostructuring surfaces: Deconstruction of the Pt(110)-(1x2) surface by C60

International audienceWhen deposited on metal surfaces, C60 creates nanoholes. Grazing incidence x-ray diffraction reveals a c( 4x 4) reconstruction induced by C60 on Pt 110) -( 1x 2) . While the initial (1x 2) missing row is partially deconstructed, under each fullerene we find double atomic vacancy involving two Pt layers. The resulting interface is deeply modified with a 75% Pt occupancy and regularly distributed double vacancy. The orientation of the molecule is compatible with local surface cm symmetry with a pentagonal ring almost parallel to the surface while hexagonal rings are almost parallel to the (111) facets of the nanohole. The short nearestneighbor C60 distances increase the van der Waals repulsion forces that are minimized by a charge transfer between molecule and substrate involving a large number of C-Pt bonds and a reduction of 6% of the apparent diameter of the C60 molecule

Strain driven monoclinic distortion of ultrathin CoO films in the exchange-coupled CoO/FePt/Pt(001) system

International audienceThe structure and strain of ultrathin CoO films grown on a Pt(001) substrate and on a ferro-magnetic FePt pseudomorphic layer on Pt(001) have been determined with insitu and real time surface x-ray diffraction. The films grow epitaxially on both surfaces with an in-plane hexagonal pattern that yields a pseudo-cubic CoO(111) surface. A refined x-ray diffraction analysis reveals a slight monoclinic distortion at RT induced by the anisotropic stress at the interface. The tetrag-onal contribution to the distortion results in a ratio c a > 1, opposite to that found in the low temperature bulk CoO phase. This distortion leads to a stable Co 2+ spin configuration within the plane of the film

Convergent Fabrication of a Nanoporous Two-Dimensional Carbon Network from an Aldol Condensation on Metal Surfaces

We report a convergent surface polymerization reaction scheme on Au(111), based on a triple aldol condensation, yielding a carbon-rich, covalent nanoporous two-dimensional network. The reaction is not self-poisoning and proceeds up to a full surface coverage. The deposited precursor molecules 1,3,5-tri(4'-acetylphenyl) first form supramolecular assemblies that are converted to the porous covalent network upon heating. The formation and structure of the network and of the intermediate steps are studied with scanning tunneling microscopy, Raman spectroscopy and density functional theory.Comment: 1 Scheme, 5 Figure

Spin orientation in an ultrathin CoO/PtFe double-layer with perpendicular exchange coupling

International audienceWe studied by soft x-ray absorption spectroscopy the magnetization axis in an 4nm thin CoO (111) layer exchange-coupled to an ultra thin L1 0 PtFe layer with perpendicular magnetic anisotropy. The angular dependence of the linear magnetic dichroism at 10K and the relative variations of the spectral features provide a full description of the spin orientation in this antiferromagnetic layer. The spins are found in the film plane, pointing along the 110 direction. This results is discussed in relation to the film strain and preferential occupation of t 2g orbitals.The strong orthogonal coupling between Co and Fe spins should be at the origin of the robustness of the exchange bias effect foun in this bilayer system

Effects of an innovative esoskeleton (Human Body Posturizer) on static balance in patients with Parkinson’s Disease

Parkinson disease (PD) is a progressive neurodegenerative disease, affecting 0.3% of the general population; cardinal symptoms include tremor, rigidity, bradykinesia, and postural instability. Individuals with PD commonly experience gait and postural stability impairments, which may lead to falls, mobility loss, and reduced independence (de Lau et al, 2006). Human Body Posturizer (HBP) is a fully articulated orthosis, light and able to adapt to the physical characteristics of each individual (Di Russo et al, 2013). Our aim has been to preliminary evaluate the role of HBP as an innovative tool for the conservative treatment of gait and postural stability impairments in patients affected by PD. This study analyzed 10 subjects (5 male and 5 female) affected by PD. A bipodal platform (Prokin, Tecnobody) was used to evaluate static balance. All patients were firstly evaluated without HBP and wearing normal clothes; then, patients were asked to wear HBP and, after 40 mins, a second acquisition with HBP was performed. For the static evaluation, the patients performed a stabilometric test, 30 sec with eyes open and then 30 sec with eyes closed; perimeter sway, area of the center of pressure (CoP), anterior-posterior velocity (VA-P), and medial-lateral velocity (VM-L) have been evaluated. Our results showed a significant reduction in VA-P (p<0.05) when patients wear HBP in both open and closen eyes condition. Moreover, a significant reduction (p<0.05) of the CoP area was observed in closen eyes evaluation. Area of the ellipse contained 95% of CoP data points, computed by considering the main axes of the ellipse, estimated using principal component analysis. This variable reflects the ability of balance system to achieve body stability. Our data suggest a stabilizing effect of HBP on anterior-posterior balance, in patients with PD

Robust perpendicular exchange coupling in an ultrathin CoO/PtFe double layer: Strain and spin orientation

5 pagesInternational audienceWe report on the exchange coupling and magnetic properties of a strained ultrathin CoO/PtFe double layer with perpendicular magnetic anisotropy. The cobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated PtFe/Pt(001) surface gives rise to a hexagonal surface and a monoclinic distorted CoO 3 nm film at room temperature. This distorted ultrathin CoO layer couples with the PtFe(001) layer establishing a robust perpendicular exchange bias shift. Soft x-ray absorption spectroscopy provides a full description of the spin orientations in the CoO/PtFe double layer. The exchange bias shift is preserved up to the N'eel antiferromagnetic ordering temperature of TN = 293 K. This unique example of selfsame value for blocking and ordering temperatures, yet identical to the bulk ordering temperature, is likely related to the original strain-induced distortion and strengthened interaction between the two well-ordered spin layers

Robust perpendicular exchange coupling in an ultrathin CoO/PtFe double layer: strain and spin orientation

Sem informaçãoWe report on the exchange coupling and magnetic properties of a strained ultrathin CoO/PtFe double layer with perpendicular magnetic anisotropy. The cobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated PtFe/Pt(001) surface gives rise to a hexagonal surface and a monoclinic distorted CoO 3 nm film at room temperature. This distorted ultrathin CoO layer couples with the PtFe(001) layer establishing a robust perpendicular exchange bias shift. Soft x-ray absorption spectroscopy provides a full description of the spin orientations in the CoO/PtFe double layer. The exchange bias shift is preserved up to the Néel antiferromagnetic ordering temperature of TN = 293 K. This unique example of selfsame value for blocking and ordering temperatures, yet identical to the bulk ordering temperature, is likely related to the original strain-induced distortion and strengthened interaction between the two well-ordered spin layers.We report on the exchange coupling and magnetic properties of a strained ultrathin CoO/PtFe double layer with perpendicular magnetic anisotropy. The cobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated PtFe/Pt(001) surface gives rise to a hexagonal surface and a monoclinic distorted CoO 3 nm film at room temperature. This distorted ultrathin CoO layer couples with the PtFe(001) layer establishing a robust perpendicular exchange bias shift. Soft x-ray absorption spectroscopy provides a full description of the spin orientations in the CoO/PtFe double layer. The exchange bias shift is preserved up to the Néel antiferromagnetic ordering temperature of TN = 293 K. This unique example of selfsame value for blocking and ordering temperatures, yet identical to the bulk ordering temperature, is likely related to the original strain-induced distortion and strengthened interaction between the two well-ordered spin layers.881415Sem informaçãoSem informaçãoSem informaçã