Serodiagnosis of infectious mononucleosis by using recombinant Epstein-Barr virus antigens and enzyme-linked immunosorbent assay technology

Four recombinant, diagnostically useful Epstein-Barr virus (EBV) proteins representative of the viral capsid antigen (p150), diffuse early antigen (p54), the major DNA-binding protein (p138), and the EBV nuclear antigen (p72) (W. Hinderer, H. Nebel-Schickel, H.H. Sonneborn, M. Motz, R. Kühbeck, and H. Wolf, J. Exp. Clin. Cancer Res. 7[Suppl.]:132, 1988) were used to set up individual enzyme-linked immunosorbent assays (ELISAs) for the qualitative and quantitative detection of immunoglobulin M (IgM) and IgG antibodies. In direct comparison with results obtained by standard immunofluorescence or immunoperoxidase assays, it was then shown that the recombinant EBV ELISAs provide the means for specific and sensitive serodiagnosis of infectious mononucleosis (IM) caused by EBV. The most useful markers in sera from such patients proved to be IgM antibodies against p54, p138, and p150. Additional positive markers for recent or ongoing IM apparently were IgG antibodies against p54 and p138. In contrast, anti-p72 IgG had a high preference for sera from healthy blood donors and, therefore, can be considered indicative of past exposure to the virus. Altogether, the individual ELISAs proved to be as specific and at least as sensitive for the diagnosis of IM as the currently available standard techniques are. Moreover, our findings suggest that, by combining individual test antigens, a workable ELISA system consisting of three assays (IgM against p54, p138, and p150; IgG against p54 and p138; and IgG against p72) can be established for the standardized rapid diagnosis of acute EBV infections

The Pauli equation with complex boundary conditions

We consider one-dimensional Pauli Hamiltonians in a bounded interval with possibly non-self-adjoint Robin-type boundary conditions. We study the influence of the spin-magnetic interaction on the interplay between the type of boundary conditions and the spectrum. A special attention is paid to PT-symmetric boundary conditions with the physical choice of the time-reversal operator T.Comment: 16 pages, 4 figure

PT-symmetric models in curved manifolds

We consider the Laplace-Beltrami operator in tubular neighbourhoods of curves on two-dimensional Riemannian manifolds, subject to non-Hermitian parity and time preserving boundary conditions. We are interested in the interplay between the geometry and spectrum. After introducing a suitable Hilbert space framework in the general situation, which enables us to realize the Laplace-Beltrami operator as an m-sectorial operator, we focus on solvable models defined on manifolds of constant curvature. In some situations, notably for non-Hermitian Robin-type boundary conditions, we are able to prove either the reality of the spectrum or the existence of complex conjugate pairs of eigenvalues, and establish similarity of the non-Hermitian m-sectorial operators to normal or self-adjoint operators. The study is illustrated by numerical computations.Comment: 37 pages, PDFLaTeX with 11 figure

From multiple perspectives to shared understanding

The aim of this study was to explore how learners operating in a small group reach shared understanding as they work out joint research questions and build a theoretical framework and to identify the resources and tools they used in the process. The learners’ own interpretations of their group activities and learning were also taken into account. The data, consisting of group discussions and the documents produced by the group, were subjected to a qualitative content analysis. The group members employed a variety of resources and tools to exchange their individual perspectives and achieve shared understanding. Summaries of relevant literature laid a foundation for the group’s theoretical discussions. Reflective comparisons between their book knowledge and their personal experiences of online interaction and collaboration were frequent, suggesting that such juxtapositions may have enhanced their learning by intertwining the content to be mastered and the activities entailed by this particular content

Pseudospectra in non-Hermitian quantum mechanics

We propose giving the mathematical concept of the pseudospectrum a central role in quantum mechanics with non-Hermitian operators. We relate pseudospectral properties to quasi-Hermiticity, similarity to self-adjoint operators, and basis properties of eigenfunctions. The abstract results are illustrated by unexpected wild properties of operators familiar from PT-symmetric quantum mechanics.Comment: version accepted for publication in J. Math. Phys.: criterion excluding basis property (Proposition 6) added, unbounded time-evolution discussed, new reference

Scattering in the PT-symmetric Coulomb potential

Scattering on the ${\cal PT}$-symmetric Coulomb potential is studied along a U-shaped trajectory circumventing the origin in the complex $x$ plane from below. This trajectory reflects ${\cal PT}$ symmetry, sets the appropriate boundary conditions for bound states and also allows the restoration of the correct sign of the energy eigenvalues. Scattering states are composed from the two linearly independent solutions valid for non-integer values of the 2L parameter, which would correspond to the angular momentum in the usual Hermitian setting. Transmission and reflection coefficients are written in closed analytic form and it is shown that similarly to other ${\cal PT}$-symmetric scattering systems the latter exhibit handedness effect. Bound-state energies are recovered from the poles of the transmission coefficients.Comment: Journal of Physics A: Mathematical and Theoretical 42 (2009) to appea

Mechanical properties and fracture behavior of high-strength steels

Typical thicknesses ofhigh-strength steels (HSS) sheets used in the car industry are inapplicablefor standardized testingprocedures. The aim ofthis study is topropose an appropriate methodologyfor testing and comparing of thin HSS sheets. Microstructures were observed by means of light and scanning electron microscopy. The modified Charpy impact tests andfracture toughness tests were used in order to compare thefracture properties of three different HSS sheets (Docol 1200 M, Multiphase 1200 and BTR 165). Ductile-to-brittle transition curves and tearing resistance (J —Δα) curves were measured. From thefracture toughness linked to the specimen thicknesses the value of fracture toughness KIc was estimated. Fractographic analysis of broken specimens has revealed that due to the fine microstructure of mixed ferrite-martensite fracture mechanism remains ductile even at low temperatures (down to —100° C).Толщины листовой высокопрочной стали, применяемой в автомобильной промышлен­ности, не соответствуют требованиям стан­дартных методов испытаний. Цель настоя­щего исследования - предложить приемле­мую методологию испытаний и сравненить между собой тонколистовые высокопрочные сталей. Микроструктуру изучали с помо­щью оптической и сканирующей электронной микроскопии. Для сравнения особенностей разрушения трех различных сталей (Docol 1200, M. Multiphase 1200 и BTR165) использовали модифицированный метод ударных испытаний по Шарпи и метод оценки вязкости разрушения. Были получены кривые перехода из вязкого состояния в хрупкое и кривые сопро­тивления разрыву (J —Δα). По вязкости раз­рушения, зависящей от толщины образцов, оценивали величину KIc . Фрактографический анализ разрушенных образцов пока­ зал, что вследствие тонкой микроструктуры смешанного феррита-мартенсита сохраняет­ся вязкий механизм разрушения даже при низких температурах (до —100° C)

Mechanical properties and fracture behavior of high-strength steels

Typical thicknesses ofhigh-strength steels (HSS) sheets used in the car industry are inapplicablefor standardized testingprocedures. The aim ofthis study is topropose an appropriate methodologyfor testing and comparing of thin HSS sheets. Microstructures were observed by means of light and scanning electron microscopy. The modified Charpy impact tests andfracture toughness tests were used in order to compare thefracture properties of three different HSS sheets (Docol 1200 M, Multiphase 1200 and BTR 165). Ductile-to-brittle transition curves and tearing resistance (J —Δα) curves were measured. From thefracture toughness linked to the specimen thicknesses the value of fracture toughness KIc was estimated. Fractographic analysis of broken specimens has revealed that due to the fine microstructure of mixed ferrite-martensite fracture mechanism remains ductile even at low temperatures (down to —100° C).Толщины листовой высокопрочной стали, применяемой в автомобильной промышлен­ности, не соответствуют требованиям стан­дартных методов испытаний. Цель настоя­щего исследования - предложить приемле­мую методологию испытаний и сравненить между собой тонколистовые высокопрочные сталей. Микроструктуру изучали с помо­щью оптической и сканирующей электронной микроскопии. Для сравнения особенностей разрушения трех различных сталей (Docol 1200, M. Multiphase 1200 и BTR165) использовали модифицированный метод ударных испытаний по Шарпи и метод оценки вязкости разрушения. Были получены кривые перехода из вязкого состояния в хрупкое и кривые сопро­тивления разрыву (J —Δα). По вязкости раз­рушения, зависящей от толщины образцов, оценивали величину KIc . Фрактографический анализ разрушенных образцов пока­ зал, что вследствие тонкой микроструктуры смешанного феррита-мартенсита сохраняет­ся вязкий механизм разрушения даже при низких температурах (до —100° C)