Validation and Application of an intervertebral Disc Finite Element Model Utilizing independently Constructed Tissue-Level Constitutive formulations That are Nonlinear, Anisotropic, and Time-Dependent

Finite element models are advantageous in the study of intervertebral disc mechanics as the stress-strain distributions can be determined throughout the tissue and the applied loading and material properties can be controlled and modified. However, the complicated nature of the disc presents a challenge in developing an accurate and predictive disc model, which has led to limitations in finite element geometries, material constitutive models and properties, and model validation. The objective of this dissertation is to develop a new finite element model of the intervertebral disc, to validate the model\u27s nonlinear and time-dependent responses without tuning or calibration, and to evaluate the effect of changes in nucleus pulposus and cartilaginous endplate material properties on the disc mechanical response. This was accomplished through a cohesive series of studies. First, structural hyperelastic constitutive models were used in conjunction with biphasic-swelling theory to obtain material parameters for the disc tissues from recent tissue tests. A new disc finite element model was then constructed utilizing an analytically-based geometry created from the mean shape of human L4/L5 discs, measured from high-resolution 3D MR images and averaged using signed distance functions. The full disc model was then validated against experimental intervertebral disc loading datasets for compressive slow loading ramp, creep, and stress-relaxation simulations, and finally the new disc model was used to investigate the role of each individual disc tissue. The significance of this new disc model is threefold. First, an extensive validation was performed using the full nonlinear response of the intervertebral disc in three different loading modalities. The finite element predictions fit within the experimental range (mean ±95% confidence interval) of the nonlinear response. Second, the validation was predictive; no material parameters were determined using fits to any motion-segment data. All parameters were obtained from fits to the individual tissue responses. Furthermore, the loading mechanisms tested at the tissue level (confined compression, uniaxial tension) were different than those implemented at the full disc scale (quasi-static slow ramp, creep, stress-relaxation). Lastly, model validation was accomplished without any tuning or adjustment of the material parameters in order to force agreement between the FE and experimental responses

The Revelation of God, East and West: Contrasting Special Revelation in Western Modernity with the Ancient Christian East

The questions of whether God reveals himself; if so, how we can know a purported revelation is authentic; and how such revelations relate to the insights of reason are discussed by John Locke, Thomas Hobbes, René Descartes, G. W. Leibniz, and Immanuel Kant, to name a few. Yet, what these philosophers say with such consistency about revelation stands in stark contrast with the claims of the Christian East, which are equally consistent from the second century through the fourteenth century. In this essay, I will compare the modern discussion of special revelation from Thomas Hobbes through Johann Fichte with the Eastern Christian discussion from Irenaeus through Gregory Palamas. As we will see, there are noteworthy differences between the two trajectories, differences I will suggest merit careful consideration from philosophers of religion

Network Architecture for Generating a Labeled Overhead Image

A computer-implemented process is disclosed for generating a labeled overhead image of a geographical area. A plurality of ground level images of the geographical area is retrieved. A ground level feature map is generated, via a ground level convolutional neural network, based on features extracted from the plurality of ground level images. An overhead image of the geographical area is also retrieved. A joint feature map is generated, via an overhead convolutional neural network based on the ground level feature map and features extracted from the plurality of ground level images. Geospatial function values at a plurality of pixels of the overhead image are estimated based on at least the joint feature map and the overhead image. The plurality of pixels of the overhead image is labeled according to the estimated geospatial function values

Early contingentnegative variation of the EEG and attentional flexibility are reduced in hypotension

This study explored the question as to whether hypotension is related to decreased attentional performance and reduced cortical activation. A total of 50 females aged 19 44 years participated in the study. Attentional performance was assessed using three subtests of the Attentional and Cognitive Efficiency (ACE) battery. Contingent negative variation (CNV) as a measure of cortical activation was registered during a constant fore-period reaction time paradigm: two conditions were defined using tones as S1 (80 or 60 dB) and S2 (70 dB). The following results were obtained. Hypotensive patients performed significantly more poorly on one subtest of the ACE, which indicates a reduced speed for switching from a routine to a controlled response (quantifying attentional flexibility). They also had longer reaction times and revealed a significantly smaller amplitude of the early CNV component. In addition, a significant correlation was observed between systolic blood pressure and the amplitude of the early CNV component. The data support previous findings that hypotension can be related to lowered cortical activation and indicate that specific aspects of attentional performance might be negatively affected by hypotension