Fracture Toughness of Composite and Unfilled Restorative Resins

Fracture toughness, critical strain energy release rate, and critical stress intensity factor were determined for experimental and commercial restorative resins. A composite resin had lower resistance to arack initiation than an unfilled acrylic resin. The data were consistent with surface failure observed in single-pass wear studies of these resins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66920/2/10.1177_00220345770560070801.pd

Spin-dependent (magneto)transport through a ring due to spin-orbit interaction

Electron transport through a one-dimensional ring connected with two external leads, in the presence of spin-orbit interaction (SOI) of strength \alpha and a perpendicular magnetic field is studied. Applying Griffith's boundary conditions we derive analytic expressions for the reflection and transmission coefficients of the corresponding one-electron scattering problem. We generalize earlier conductance results by Nitta et al. [Appl. Phys. Lett. 75, 695 (1999)] and investigate the influence of \alpha, temperature, and a weak magnetic field on the conductance. Varying \alpha and temperature changes the position of the minima and maxima of the magnetic-field dependent conductance, and it may even convert a maximum into a minimum and vice versa.Comment: 19 pages, 9 figure

Anisotropic Superexchange for nearest and next nearest coppers in chain, ladder and lamellar cuprates

We present a detailed calculation of the magnetic couplings between nearest-neighbor and next-nearest-neighbor coppers in the edge-sharing geometry, ubiquitous in many cuprates. In this geometry, the interaction between nearest neighbor coppers is mediated via two oxygens, and the Cu-O-Cu angle is close to 90 degrees. The derivation is based on a perturbation expansion of a general Hubbard Hamiltonian, and produces numerical estimates for the various magnetic energies. In particular we find the dependence of the anisotropy energies on the angular deviation away from the 90 degrees geometry of the Cu-O-Cu bonds. Our results are required for the correct analysis of the magnetic structure of various chain, ladder and lamellar cuprates.Comment: 13 pages, Latex, 7 figure

Critical properties of 1-D spin 1/2 antiferromagnetic Heisenberg model

We discuss numerical results for the 1-D spin 1/2 antiferromagnetic Heisenberg model with next-to-nearest neighbour coupling and in the presence of an uniform magnetic field. The model develops zero frequency excitations at field dependent soft mode momenta. We compute critical quantities from finite size dependence of static structure factors.Comment: talk given by H. Kr{\"o}ger at Heraeus Seminar Theory of Spin Lattices and Lattice Gauge Models, Bad Honnef (1996), 20 pages, LaTeX + 18 figures, P

A new look at energy release rates for quasistatically propagating cracks in inelastic materials

A mapping technique is used to derive an integral expression for the energy release rate for a quasistatically propagating crack. The derivation does not depend on any assumptions in regard to the contitutive behavior of the material. It leads to a contour integral around the crack tip, plus an area integral over the region enclosed by this contour. Only the stress and displacement fields appear in the integrands. Although for stationary crack solutions known to the authors the area integral is not convergent, for propagating crack solutions in elastoplastic material, the integrals are convergent, and lead to zero energy release rate. This confirms conclusions by Rice from an independent point of view.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42773/1/10704_2004_Article_BF00012388.pd

Molecular and translational advances in meningiomas.

Meningiomas are the most common primary intracranial neoplasm. The current World Health Organization (WHO) classification categorizes meningiomas based on histopathological features, but emerging molecular data demonstrate the importance of genomic and epigenomic factors in the clinical behavior of these tumors. Treatment options for symptomatic meningiomas are limited to surgical resection where possible and adjuvant radiation therapy for tumors with concerning histopathological features or recurrent disease. At present, alternative adjuvant treatment options are not available in part due to limited historical biological analysis and clinical trial investigation on meningiomas. With advances in molecular and genomic techniques in the last decade, we have witnessed a surge of interest in understanding the genomic and epigenomic landscape of meningiomas. The field is now at the stage to adopt this molecular knowledge to refine meningioma classification and introduce molecular algorithms that can guide prediction and therapeutics for this tumor type. Animal models that recapitulate meningiomas faithfully are in critical need to test new therapeutics to facilitate rapid-cycle translation to clinical trials. Here we review the most up-to-date knowledge of molecular alterations that provide insight into meningioma behavior and are ready for application to clinical trial investigation, and highlight the landscape of available preclinical models in meningiomas

Understanding preventive behaviors among mid-Western African-American men: a pilot qualitative study of prostate screening

http://dx.doi.org/10.1016/j.jomh.2011.03.00

Representational predicaments for employees: Their impact on perceptions of supervisors\u27 individualized consideration and on employee job satisfaction

A representational predicament for a subordinate vis-à-vis his or her immediate superior involves perceptual incongruence with the superior about the subordinate\u27s work or work context, with unfavourable implications for the employee. An instrument to measure the incidence of two types of representational predicament, being neglected and negative slanting, was developed and then validated through an initial survey of 327 employees. A subsequent substantive survey with a fresh sample of 330 employees largely supported a conceptual model linking being neglected and negative slanting to perceptions of low individualized consideration by superiors and to low overall job satisfaction. The respondents in both surveys were all Hong Kong Chinese. Two case examples drawn from qualitative interviews illustrate and support the conceptual model. Based on the research findings, we recommend some practical exercises to use in training interventions with leaders and subordinates. © 2013 Copyright Taylor and Francis Group, LLC