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A noncontact laser-ultrasonic technique is described that allows determination of materials anisotropic properties. Plane waves are synthesized by scanning the surface with a laser line source at judiciously chosen intervals. The identification of the stiffness-tensor components is based on the inversion of the phase velocities of these transmitted plane waves. The procedure developed is presented and applied to both simulated and experimental signals. The influence of the spatial extent of the laser source in the identification of the stiffness-tensor components is also discussed; the effect of the spot size is analyzed in the ablation regime for which the acoustic source is localized at the surface, whereas the influence of the optical penetration depth is quantified in the thermoelastic regime. [ABSTRACT FROM AUTHOR]

This article examines school suspension, the ultimate punishment for rules violation, as both a process and an event. The characteristics of students who are involved in expulsion processes are discussed, and the effectiveness of expulsion, the event, as an educational intervention, is considered. The consideration of school expulsion, the event, is framed within the processes and contexts that lead to and result from the act of excluding students from a school when they have committed an expellable offense. Public education is faced with the ever-increasing challenge of educating all children to meet high standards in the context of limited school resources and communities of families and children with complex needs and problems. Teachers are confronted with students who represent a significant range of needs and abilities. Non-compliance and misbehavior add yet another level of complexity to teaching situations, and the developmental safety of students may be threatened in situations where misbehavior disrupts the classroom process.

A better understanding of expulsion as an act, a process, and an educational intervention leads to an entirely different understanding of student behavior and disciplinary consequences. [ABSTRACT FROM AUTHOR]