767 research outputs found

    Experimental Evidence for Two-Dimensional Magnetic Order in Proton Bombarded Graphite

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    We have prepared magnetic graphite samples bombarded by protons at low temperatures and low fluences to attenuate the large thermal annealing produced during irradiation. An overall optimization of sample handling allowed us to find Curie temperatures Tc350 T_c \gtrsim 350 K at the used fluences. The magnetization versus temperature shows unequivocally a linear dependence, which can be interpreted as due to excitations of spin waves in a two dimensional Heisenberg model with a weak uniaxial anisotropy.Comment: 4 pages, 3 figure

    How and when can one identify hadronic molecules in the baryon spectrum

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    A method to identify hadronic molecules in the particle spectrum is reviewed and the conditions for its applicability discussed. Special emphasis is put on the discussion of molecule candidates in the baryon spectrum.Comment: Talk presentent at NSTAR 2007, 5 - 8 September 2007, Bonn, German

    Magnetization structure of a Bloch point singularity

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    Switching of magnetic vortex cores involves a topological transition characterized by the presence of a magnetization singularity, a point where the magnetization vanishes (Bloch point). We analytically derive the shape of the Bloch point that is an extremum of the free energy with exchange, dipole and the Landau terms for the determination of the local value of the magnetization modulus.Comment: 4 pages, 2 figure

    Assessment of pulmonary antibodies with induced sputum and bronchoalveolar lavage induced by nasal vaccination against Pseudomonas aeruginosa: a clinical phase I/II study

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    <p>Abstract</p> <p>Background</p> <p>Vaccination against <it>Pseudomonas aeruginosa </it>is a desirable albeit challenging strategy for prevention of airway infection in patients with cystic fibrosis. We assessed the immunogenicity of a nasal vaccine based on the outer membrane proteins F and I from <it>Pseudomonas aeruginosa </it>in the lower airways in a phase I/II clinical trial.</p> <p>Methods</p> <p>N = 12 healthy volunteers received 2 nasal vaccinations with an OprF-OprI gel as a primary and a systemic (n = 6) or a nasal booster vaccination (n = 6). Antibodies were assessed in induced sputum (IS), bronchoalveolar lavage (BAL), and in serum.</p> <p>Results</p> <p>OprF-OprI-specific IgG and IgA antibodies were found in both BAL and IS at comparable rates, but differed in the predominant isotype. IgA antibodies in IS did not correlate to the respective serum levels. Pulmonary antibodies were detectable in all vaccinees even 1 year after the vaccination. The systemic booster group had higher IgG levels in serum. However, the nasal booster group had the better long-term response with bronchial antibodies of both isotypes.</p> <p>Conclusion</p> <p>The nasal OprF-OprI-vaccine induces a lasting antibody response at both, systemic and airway mucosal site. IS is a feasible method to non-invasively assess bronchial antibodies. A further optimization of the vaccination schedule is warranted.</p

    The DNDN, πΣc\pi \Sigma_c interaction in finite volume and the Λc(2595)\Lambda_c(2595) resonance

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    In this work the interaction of the coupled channels DNDN and πΣc\pi \Sigma_c in an SU(4) extrapolation of the chiral unitary theory, where the Λc(2595)\Lambda_c(2595) resonance appears as dynamically generated from that interaction, is extended to produce results in finite volume. Energy levels in the finite box are evaluated and, assuming that they would correspond to lattice results, the inverse problem of determining the phase shifts in the infinite volume from the lattice results is solved. We observe that it is possible to obtain accurate πΣc\pi \Sigma_c phase shifts and the position of the Λc(2595)\Lambda_c(2595) resonance, but it requires the explicit consideration of the two coupled channels. We also observe that some of the energy levels in the box are attached to the closed DNDN channel, such that their use to induce the πΣc\pi \Sigma_c phase shifts via L\"uscher's formula leads to incorrect results.Comment: 10 pages, 13 figures, accepted for publication in Eur. Phys. J.

    Penta-quark states with hidden charm and beauty

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    More and more hadron states are found to be difficult to be accommodated by the quenched quark models which describe baryons as 3-quark states and mesons as antiquark-quark states. Dragging out an antiquark-quark pair from the gluon field in hadrons should be an important excitation mechanism for hadron spectroscopy. Our recent progress on the penta-quark states with hidden charm and beauty is reviewed.Comment: Plenary talk at the 5th Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011), 22-26 Aug., 2011, Seoul, Kore

    Expressive and Instrumental Offending: Reconciling the Paradox of Specialisation and Versatility

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    Although previous research into specialisation has been dominated by the debate over the existence of specialisation versus versatility, it is suggested that research needs to move beyond the restrictions of this dispute. The current study explores the criminal careers of 200 offenders based on their criminal records, obtained from a police database in the North West of England, aiming to understand the patterns and nature of specialisation by determining the presence of differentiation within their general offending behaviours and examining whether the framework of Expressive and Instrumental offending styles can account for any specialised tendencies that emerge. Fifty-eight offences were subjected to Smallest Space Analysis. Results revealed that a model of criminal differentiation could be identified and that any specialisation is represented in terms of Expressive and Instrumental offending styles

    Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances

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    We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum numbers. We examine the scattering amplitudes and their poles, which can be associated to known JP=1/2,3/2J^P=1/2^-,3/2^- baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass of the resonances generated with only the basis of vector-baryon states
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