2,410 research outputs found

    Advanced marketing education curriculum in secondary schools in Wisconsin

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    Includes bibliographical references

    Intercalation of graphene on SiC(0001) via ion-implantation

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    Electronic devices based on graphene technology are catching on rapidly and the ability to engineer graphene properties at the nanoscale is becoming, more than ever, indispensable. Here, we present a new procedure of graphene functionalization on SiC(0001) that paves the way towards the fabrication of complex graphene electronic chips. The procedure resides on the well-known ion-implantation technique. The efficiency of the working principle is demonstrated by the intercalation of the epitaxial graphene layer on SiC(0001) with Bi atoms, which was not possible following standard procedures. Our results put forward the ion-beam lithography to nanostructure and functionalize desired graphene chips

    Temperature-induced reversal of magnetic interlayer exchange coupling

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    For epitaxial trilayers of the magnetic rare-earth metals Gd and Tb, exchange coupled through a non-magnetic Y spacer layer, element-specific hysteresis loops were recorded by the x-ray magneto-optical Kerr effect at the rare-earth M5M_5 thresholds. This allowed us to quantitatively determine the strength of interlayer exchange coupling (IEC). In addition to the expected oscillatory behavior as a function of spacer-layer thickness dYd_Y, a temperature-induced sign reversal of IEC was observed for constant dYd_Y, arising from magnetization-dependent electron reflectivities at the magnetic interfaces.Comment: 4 pages, 4 figures; accepted version; minor changes and new Figs. 2 and 4 containing more dat

    Dynamics of Tachyonic Dark Matter

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    Usually considered highly speculative, tachyons can be treated via straightforward Einsteinian dynamics. Kinetic theory and thermodynamics for a gas of ``dark'' tachyons are readily constructed. Such a gas exhibits density and pressure which, for the dominant constituent of a suitable Friedmann-Robertson-Walker spacetime, can drive cosmic evolution with features both similar to and distinct from those of a standard dark-energy/dark-matter model. Hence, tachyons might bear further consideration as a cosmic dark-matter candidate.Comment: 16 pages, 1 figur

    LEED Holography applied to a complex superstructure: a direct view of the adatom cluster on SiC(111)-(3x3)

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    For the example of the SiC(111)-(3x3) reconstruction we show that a holographic interpretation of discrete Low Energy Electron Diffraction (LEED) spot intensities arising from ordered, large unit cell superstructures can give direct access to the local geometry of a cluster around an elevated atom, provided there is only one such prominent atom per surface unit cell. By comparing the holographic images obtained from experimental and calculated data we illuminate validity, current limits and possible shortcomings of the method. In particular, we show that periodic vacancies such as cornerholes may inhibit the correct detection of the atomic positions. By contrast, the extra diffraction intensity due to slight substrate reconstructions, as for example buckling, seems to have negligible influence on the images. Due to the spatial information depth of the method the stacking of the cluster can be imaged down to the fourth layer. Finally, it is demonstrated how this structural knowledge of the adcluster geometry can be used to guide the dynamical intensity analysis subsequent to the holographic reconstruction and necessary to retrieve the full unit cell structure.Comment: 11 pages RevTex, 6 figures, Phys. Rev. B in pres

    Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold

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    X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the Kramers-Kronig transformation, correspond to a magneto-optical Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.Comment: 4 pages, 2 figures, final version resubmitted to Phys. Rev. B, Brief Reports. Minor change

    Pathways to Employment

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    Background This project’s aims are twofold (1) to uncover and define the underlying theories of change guiding competing active labor market programs (ALMP) in Sweden, and (2) to assess the relative effectiveness of these competing programs in a theory-based non-randomized controlled trial. The purpose is to assess the extent to which competing ALMPs are effective in moving long-term unemployed individuals (i.e. unemployed for 6 months or more) closer to the labor-market. Methods/Design This project will engage ALMP program administrators and service providers in semi-structured interviews. The transcribed interview material will be used as a basis for program theory reconstruction. All specified program theories will be presented back to program stakeholders for validation. ALMP program effectiveness will be assessed quasi-experimentally with pre- (T1) and posttest (T2) collection of self-reported data. Additionally, official register data from the Longitudinal integrated database for health insurance and labor market studies (LISA) will be collected for all participants. In addition, a matched sample will be collected from LISA to be used as a non-treated control group on final policy outcomes (e.g., employment, salary/wage). This study also assesses program implementation and economic outcomes of the included ALMPs. Discussion Long-term unemployment has profound impact of the health and wellbeing of individuals, families, and communities. In addition, the effects of long-term unemployment have been found to impact subgroups differently. Today we have scant knowledge on the mechanisms that are influential in moving individuals from long-term unemployment closer to the labor market. This study is designed to answer six research questions using a variety of methods (mixed-methods) and outcome measures (self-report, official register). In addition, this study leverages official register data to construct an untreated control group. This study will assess the extent to which an emerging theory of becoming job ready holds under experimental scrutiny

    Uptake and fecal excretion of Coxiella burnetii by Ixodes ricinus and Dermacentor marginatus ticks

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    Background: The bacterium Coxiella burnetii is the etiological agent of Q fever and is mainly transmitted via inhalation of infectious aerosols. DNA of C. burnetii is frequently detected in ticks, but the role of ticks as vectors in the epidemiology of this agent is still controversial. In this study, Ixodes ricinus and Dermacentor marginatus adults as well as I. ricinus nymphs were fed on blood spiked with C. burnetii in order to study the fate of the bacterium within putative tick vectors. Methods: Blood-feeding experiments were performed in vitro in silicone-membrane based feeding units. The uptake, fecal excretion and transstadial transmission of C. burnetii was examined by quantitative real-time PCR as well as cultivation of feces and crushed tick filtrates in L-929 mouse fibroblast cells and cell-free culture medium. Results: Ticks successfully fed in the feeding system with engorgement rates ranging from 29% (D. marginatus) to 64% (I. ricinus adults). Coxiella burnetii DNA was detected in the feces of both tick species during and after feeding on blood containing 105 or 106 genomic equivalents per ml blood (GE/ml), but not when fed on blood containing only 104 GE/ml. Isolation and cultivation demonstrated the infectivity of C. burnetii in shed feces. In 25% of the I. ricinus nymphs feeding on inoculated blood, a transstadial transmission to the adult stage was detected. Females that molted from nymphs fed on inoculated blood excreted C. burnetii of up to 106 genomic equivalents per mg of feces. Conclusions: These findings show that transstadial transmission of C. burnetii occurs in I. ricinus and confirm that I. ricinus is a potential vector for Q fever. Transmission from both tick species might occur by inhalation of feces containing high amounts of viable C. burnetii rather than via tick bites
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