233 research outputs found

    Pb0.4Bi1.6Sr2Ca1Cu2O8+xPb_{0.4}Bi_{1.6}Sr_{2}Ca_{1}Cu_{2}O_{8+x} and Oxygen Stoichiometry: Structure, Resistivity, Fermi Surface Topology and Normal State Properties

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    Pb0.4Bi1.6Sr2CaCu2O8+xPb_{0.4}Bi_{1.6}Sr_2CaCu_2O_{8+x} (Bi(Pb)Bi(Pb)-2212) single crystal samples were studied using transmission electron microscopy (TEM), abab-plane (ρab\rho_{ab}) and cc-axis (ρc\rho_c) resistivity, and high resolution angle-resolved ultraviolet photoemission spectroscopy (ARUPS). TEM reveals that the modulation in the bb-axis for Pb(0.4)Pb(0.4)-doped Bi(Pb)Bi(Pb)-2212 is dominantly of PbPb-type that is not sensitive to the oxygen content of the system, and the system clearly shows a structure of orthorhombic symmetry. Oxygen annealed samples exhibit a much lower cc-axis resistivity and a resistivity minimum at 8013080-130K. He-annealed samples exhibit a much higher cc-axis resistivity and dρc/dT<0d\rho_c/dT<0 behavior below 300K. The Fermi surface (FS) of oxygen annealed Bi(Pb)Bi(Pb)-2212 mapped out by ARUPS has a pocket in the FS around the Mˉ\bar{M} point and exhibits orthorhombic symmetry. There are flat, parallel sections of the FS, about 60\% of the maximum possible along kx=kyk_x = k_y, and about 30\% along kx=kyk_x = - k_y. The wavevectors connecting the flat sections are about 0.72(π,π)0.72(\pi, \pi) along kx=kyk_x = k_y, and about 0.80(π,π)0.80(\pi, \pi) along kx=kyk_x = - k_y, rather than (π,π)(\pi,\pi). The symmetry of the near-Fermi-energy dispersing states in the normal state changes between oxygen-annealed and He-annealed samples.Comment: APS_REVTEX 3.0, 49 pages, including 11 figures, available upon request. Submitted to Phys. Rev. B

    Metadevice of three dimensional split ring resonators

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    Split-ring resonator (SRR), a kind of building block for metamaterial unit cell, has attracted wide attentions due to the resonance excitation of electric and magnetic dipolar response. Here, different from prior published lectures, fundamental plasmon properties and potential applications in novel three dimensional vertical split-ring resonators (VSRRs ) are designed and investigated. The resonant properties arose from the electric and magnetic interactions between the VSRR s and light are firstly theoretically and experimentally studied (Fig. 1(a)). Tuning the configuration of VSRR unit cells is able to generate various novel coupling phenomena in VSRRs, such as plasmon hybridization and Fano resonance, as shown in Figs. 1(b) and 1(c) . Subsequently, the VSRR-based refractive-index sensor will be demonstrated. Due to the unique structural configuration, the enhanced plasmon fields localized in VSRR gaps can be lifted off from the dielectric substrate, allowing for the increase of sensing volume and enhancing the sensitivity (Fig. 1(d)) . We further perform a VSRR based metasurface for light manipulation in optical communication frequency, as shown in Fig. 1(e). Moreover, isotropic VSRRs are approached by optimizing the structural arrangement within a unit cell (Fig. 1(f)). Figure 1(g) shows the schematic for isotropic VSRR-based perfect absorber. By incorporating a metallic mirror with isotropic VSRRs, a stronger field confinement happens to enhance the absorption ability, benefitting the development of refractive index sensor. Finally, a transverse toroidal moment generated by normal incident optical wave at gold dumbbell-shaped aperture and a VSRR is designed and experimentally demonstrated , as shown in Fig. 1(h)

    Creating 'Partnership in iSupport program' to optimise family carers' impact on dementia care: a randomised controlled trial protocol

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    Background: The majority of people with dementia are cared for by their family members. However, family carers are often unprepared for their caring roles, receiving less education and support compared with professional carers. The consequences are their reduced mental and physical health and wellbeing, and that of care recipients. This study protocol introduces the ‘Partnership in iSupport program’ that includes five interventional components: managing transitions, managing dementia progression, psychoeducation, carer support group and feedback on services. This health services research is built on family carer and dementia care service provider partnerships. The aims of the study are to evaluate the effectiveness, cost-effectiveness and family carers’ experiences in the program. Methods: A multicentre randomised controlled trial will be conducted with family carers of people living with dementia from two tertiary hospitals and two community aged care providers across three Australian states. The estimated sample size is 185 family carers. They will be randomly assigned to either the intervention group or the usual care group. Outcomes are measurable improvements in quality of life for carers and people with dementia, caregiving self-efficacy, social support, dementia related symptoms, and health service use for carers and their care recipients. Data will be collected at three time points: baseline, 6 months and 12 months post-initiation of the intervention. Discussion: This is the first large randomised controlled trial of a complex intervention on health and social care services with carers of people living with dementia in real-world practice across hospital and community aged care settings in three Australian states to ascertain the effectiveness, cost-effectiveness and carers’ experiences of the innovative program. We expect that this study will address gaps in supporting dementia carers in health and social care systems while generating new knowledge of the mechanisms of change in the systems. Findings will strengthen proactive health management for both people living with dementia and their carers by embedding, scaling up and sustaining the ‘Partnership in iSupport program’ in the health and social care systems.Lily Xiao, Ying Yu, Julie Ratcliffe, Rachel Milte, Claudia Meyer, Michael Chapman, Langduo Chen, Shahid Ullah, Alison Kitson, Andre Queiroz De Andrade, Elizabeth Beattie, Henry Brodaty, Sue McKechnie, Lee, Fay Low, Tuan Anh Nguyen, Craig Whitehead, Bianca Brijnath, Ronald Sinclair, and Diana Vos

    Accessory Genomes Drive Independent Spread of Carbapenem- Resistant Klebsiella pneumoniae Clonal Groups 258 and 307 in Houston, TX

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    Carbapenem-resistant Klebsiella pneumoniae (CRKp) is an urgent public health threat. Worldwide dissemination of CRKp has been largely attributed to clonal group (CG) 258. However, recent evidence indicates the global emergence of a CRKp CG307 lineage. Houston, TX, is the first large city in the United States with detected cocirculation of both CRKp CG307 and CG258. We sought to characterize the genomic and clinical factors contributing to the parallel endemic spread of CG258 and CG307. CRKp isolates were collected as part of the prospective, Consortium on Resistance against Carbapenems in Klebsiella and other Enterobacterales 2 (CRACKLE-2) study. Hybrid short-read and long-read genome assemblies were generated from 119 CRKp isolates (95 originated from Houston hospitals). A comprehensive characterization of phylogenies, gene transfer, and plasmid content with pan-genome analysis was performed on all CRKp isolates. Plasmid mating experiments were performed with CG307 and CG258 isolates of interest. Dissection of the accessory genomes suggested independent evolution and limited horizontal gene transfer between CG307 and CG258 lineages. CG307 contained a diverse repertoire of mobile genetic elements, which were shared with other non-CG258 K. pneumoniae isolates. Three unique clades of Houston CG307 isolates clustered distinctly from other global CG307 isolates, indicating potential selective adaptation of particular CG307 lineages to their respective geographical niches. CG307 strains were often isolated from the urine of hospitalized patients, likely serving as important reservoirs for genes encoding carbapenemases and extendedspectrum b-lactamases. Our findings suggest parallel cocirculation of high-risk lineages with potentially divergent evolution

    COVAD survey 2 long-term outcomes: unmet need and protocol

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    Vaccine hesitancy is considered a major barrier to achieving herd immunity against COVID-19. While multiple alternative and synergistic approaches including heterologous vaccination, booster doses, and antiviral drugs have been developed, equitable vaccine uptake remains the foremost strategy to manage pandemic. Although none of the currently approved vaccines are live-attenuated, several reports of disease flares, waning protection, and acute-onset syndromes have emerged as short-term adverse events after vaccination. Hence, scientific literature falls short when discussing potential long-term effects in vulnerable cohorts. The COVAD-2 survey follows on from the baseline COVAD-1 survey with the aim to collect patient-reported data on the long-term safety and tolerability of COVID-19 vaccines in immune modulation. The e-survey has been extensively pilot-tested and validated with translations into multiple languages. Anticipated results will help improve vaccination efforts and reduce the imminent risks of COVID-19 infection, especially in understudied vulnerable groups

    Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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    Search for the associated production of the Higgs boson with a top-quark pair

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    A search for the standard model Higgs boson produced in association with a top-quark pair t t ¯ H (tt¯H) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb &#8722;1 and 19.7 fb &#8722;1 collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H &#8594; hadrons, H &#8594; photons, and H &#8594; leptons. The results are characterized by an observed t t ¯ H tt¯H signal strength relative to the standard model cross section, &#956; = &#963;/&#963; SM ,under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is &#956; = 2.8 ± 1.0 for a Higgs boson mass of 125.6 GeV

    Measurements of the t(t)Overbar charge asymmetry using the dilepton decay channel in pp collisions at root s=7 TeV

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    The tt¯ charge asymmetry in proton-proton collisions at s&#8730; = 7 TeV is measured using the dilepton decay channel (ee, e &#956; , or &#956;&#956; ). The data correspond to a total integrated luminosity of 5.0 fb &#8722;1 , collected by the CMS experiment at the LHC. The tt and lepton charge asymmetries, defined as the differences in absolute values of the rapidities between the reconstructed top quarks and antiquarks and of the pseudorapidities between the positive and negative leptons, respectively, are measured to be A C = &#8722;0 . 010 ± 0 . 017 (stat . ) ± 0 . 008 (syst . ) and AlepC = 0 . 009 ± 0 . 010 (stat . ) ± 0 . 006 (syst . ). The lepton charge asymmetry is also measured as a function of the invariant mass, rapidity, and transverse momentum of the tt¯ system. All measurements are consistent with the expectations of the standard model

    Measurement of prompt Jψ\psi pair production in pp collisions at \sqrt s = 7 Tev

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    Production of prompt J/ &#968; meson pairs in proton-proton collisions at s s&#8730; = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 fb &#8722;1 . The two J/ &#968; mesons are fully reconstructed via their decays into &#956; + &#956; &#8722; pairs. This observation provides for the first time access to the high-transverse-momentum region of J/ &#968; pair production where model predictions are not yet established. The total and differential cross sections are measured in a phase space defined by the individual J/ &#968; transverse momentum ( p T J/ &#968; ) and rapidity (| y J/ &#968; |): | y J/ &#968; | 6.5 GeV/ c ; 1.2 4.5 GeV/ c . The total cross section, assuming unpolarized prompt J/ &#968; pair production is 1.49 ± 0.07 (stat) ±0.13 (syst) nb. Different assumptions about the J/ &#968; polarization imply modifications to the cross section ranging from &#8722;31% to +27%
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