Simulating the propagation of displacement discontinuities in a regularized strain‐softening medium

A numerical model is developed which allows the inclusion of displacement discontinuities in a strain‐softening medium, independent of the finite element mesh structure. Inelastic deformations develop in the continuum and, when a critical threshold of inelastic deformation is reached, a displacement discontinuity is inserted. Discontinuities are introduced using the partition of unity concept which allows discontinuous functions to be added to the standard finite element basis. It is shown that the introduction of displacement discontinuities at the later stages of the failure process can lead to a failure mode that is fundamentally different than that using a continuum model only. This combined continuum‐discontinuous model is better able to describe the entire failure process than a continuum or a discrete model alone and treats mode‐I and mode‐II failure in a unified fashion. Copyright © 2001 John Wiley & Sons, Ltd.     

Organizing the clinical data in the medical record.

We have developed a method of collecting and arranging clinical data that makes the medical record more useful in patient care and research. The design is based on two principles: that detailed clinical findings should be recorded independently of any diagnostic interpretation, and that time should be integrated as a dimension of the medical record. Analysis of the principal components of the medical record as we have organized it allows identification of clinical entities on the basis of synchronous or sequential features and facilitates precise tracking of symptoms, evaluation of therapeutic effects, comparison of treatments, identification of patients at risk of recurrence, transmission of observations from physician to physician, and analysis and reinterpretation of the observations recorded.     

Dynamic channel-sensitive scheduling algorithms for wireless data throughput optimization

The relative delay tolerance of data applications, together with bursty traffic characteristics, opens up the possibility for scheduling transmissions so as to optimize throughput. A particularly attractive approach in fading environments is to exploit the variations in the channel conditions and transmit to the user with the current "best" channel. We show that the "best" user may be identified as the maximum-rate user when feasible rates are weighted with some appropriately determined coefficients. Interpreting the coefficients as shadow prices, or reward values, the optimal strategy may thus be viewed as a revenue-based policy, which always assigns the transmission slot to the user yielding the maximum revenue. Calculating the optimal-revenue vector directly is a formidable task, requiring detailed information on the channel statistics. Instead, we present adaptive algorithms for determining the optimal-revenue vector online in an iterative fashion, without the need for explicit knowledge of the channel behavior. Starting from an arbitrary initial vector, the algorithms iteratively adjust the reward values to compensate for observed deviations from the target throughput rates. The algorithms are validated through extensive numerical experiments. Besides verifying long-run convergence, we also examine the transient performance, in particular the rate of convergence to the optimal-revenue vector. The results show that the target throughput ratios are tightly maintained and that the algorithms are well able to track sudden changes in channel conditions or throughput targets.     

Failure to find homology in rat, cat, and monkey for functions of a subcortical structure in avoidance conditioning.

Notes that electrolytic lesions of the centrum-medianum and parafascicularis complex of the thalamus produce, in the rat, large deficits of both acquisition and retention of active-avoidance responses, especially in the 2-way shuttle-box test. The effect of such lesions on 26 male cats and 6 male and 2 female macaques was examined. It was found that lesions in the cat did not produce significant effects, either with acoustical or visual CS, during postoperative relearning. Moreover, rate of extinction was not affected. Negative results were also found in monkeys. These lesions did not modify the threshold of flinch or jump responses to electric shock in either species. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the numerical integration of interface elements

Eigenmode analyses of the element stiffness matrices have been used to assess the impact of the applied integration scheme on the stress predictions of two- and three-dimensional plane interface elements. It is demonstrated that large stress gradients over the element and coupling of the individual node-sets of the interface element may result in an oscillatory type of response. For line elements and linear plane interface elements the performance can be improved by using either a nodal lumping scheme or Newton-Cotes or Lobatto integration schemes instead of the more traditional Gauss scheme. For quadratic interface elements the same holds true except for a nodal lumping scheme.     

Highly rectifying Au-contacts on diamond-on-silicon substrate

Au Schottky diodes have been fabricated on highly oriented diamond (HOD) films, grown on silicon using AC-bias nucleation and microwave plasma chemical vapor deposition. The active layers were selectively grown and doped by solid boron source. High rectification ratios were obtained up to 500°C in a bias voltage range up to ±15 V. A current density of more than 1 A/cm² and a breakdown field strength up to 2.0·10⁶ V/cm for point contacts has been demonstrated     

Bone structures in avian and mammalian lungs

Ectopic bone was found in the interstitium of lungs of birds, guinea pigs and minks. There was no evidence of a relation between the ectopic bone and the occurrence of disease.