On the mechanical stability of growing arteries

Arteries are modeled, within the framework of nonlinear elasticity, as incompressible two-layer cylindrical structures that are residually stressed through differential growth. These structures are loaded by an axial force, internal pressure and have nonlinear, anisotropic, hyperelastic response to stresses. Parameters for this model are directly related to experimental observations. The possible role of axial residual stress in regulating stress in arteries and preventing buckling instabilities is investigated. It is shown that axial residual stress lowers the critical internal pressure leading to buckling and that a reduction of axial loading may lead to a buckling instability which may eventually lead to arterial tortuosity

Analysis and prediction of vortex-induced vibrations of variable-tension vertical risers in linearly sheared currents

Many studies have tackled the problem of previous termvortex-induced vibrationsnext term (VIV) of a vertical riser with a constant tension and placed in uniform currents. In this study, attention is focused on the cross-flow VIV modelling, time-domain previous termanalysis and predictionnext term of variable-tension vertical risers in linearly sheared currents. The partial-differential equation governing the riser transverse motion is based on a flexural tensioned-beam model with typical pinned–pinned supports. The hydrodynamic excitation model describing the modulation of lift force is based on a distributed van der Pol wake oscillator whose nonlinear equation is also partial-differential due to the implementation of a diffusion term. The variation of empirical wake coefficients with system parameters and the water depth-dependent Reynolds number is introduced. Based on the assumed Fourier mode shape functions obtained by accounting for the effect of non-uniform tension, the Galerkin technique is utilized to construct a low-dimensional multi-mode model governing the coupled fluid-riser interaction system due to VIV. Numerical simulations in the case of varying sheared flow profiles are carried out to systematically evaluate riser nonlinear dynamics and highlight the influence of fluid–structure parameters along with associated VIV aspects. In particular, the effects of shear and tensioned-beam (tension versus bending) parameters are underlined. Some comparisons with published experimental results and observations are qualitatively and quantitatively discussed. Overall parametric previous termanalysis and predictionnext term results may be worthwhile for being a new benchmark against future experimental testing and/or numerical results predicted by an alternative model and methodology

Estimation of the Damping Parameter Governing the VIV of Long Flexible Cylinders

Much effort in the past half century has been made to explain the role of damping in the prediction of VIV. Scruton (1965), Griffin et al. (1975), Klamo, et al. (2005) and Govardhan & Williamson (2006) all made significant contributions. None fully characterized the role of damping in governing the response over the full range reduced velocities, which encompass the wake synchronized region. In 2012 Vandiver devised a way to do that with a new damping parameter c*. His results were verified using 2D spring-mounted cylinders in uniform flow. The primary objective of the research described in this paper is to find a c* -like quantity for flexible cylinders, which is capable of organizing response data for flexible cylinders, which may have many modes, be exposed to sheared flows and possess spatially varying properties, such as the coverage of strakes and fairings. Data from a recent high mode VIV model test campaign conducted by SHELL Exploration and Production Company are used to illustrate the application of c* to flexible cylinders. It is shown that, if one accounts for Reynolds number, the response of flexible cylinders with varying strake coverage in the SHELL Tests collapse onto a single curve

Susie and Frank Vandiver to James Silver, 8 November 1963

Personal correspondenc

Eleven Years of Lethal Injection Challenges in Arkansas

In 2015, the Supreme Court decided Glossip v. Gross, which upheld the denial of a challenge to the lethal injection protocol in Oklahoma. Justice Breyer dissented, writing that he believed the death penalty was unconstitutional because, among other reasons, it had become “unusual.” He pointed out that Arkansas, along with 10 other states, had not conducted an execution in more than 8 years. This Article provides a look into how Arkansas made it onto this list. The drought was not from a lack of effort by the state. In the ten years preceding Glossip, twenty-one execution dates were set and all were stayed. Nineteen of those were stayed because of lethal injection litigation. As this Article will recount, the decade-long hiatus was the result of dogged litigation on behalf of deathsentenced prisoners, repeated amendment of the state’s lethal injection law, and missteps by state officials

The Quality of Mercy: Race and Clemency in Florida Death Penalty Cases, 1924-1966

The scholarly literature on capital punishment includes few empirical studies of executive clemency. Commutations in capital cases have been rare since 1972 when the current era of capital punishment began with the United States Supreme Court\u27s ruling in Furman v. Georgia. A large proportion of pre-1972 death sentences were commuted; examination of clemency decisions in those cases promises to reveal much about the history of capital punishment in the United States. The present study attempts to identify factors which influenced decisions to grant commutations of Florida death sentences pre-Furman, focusing particularly on whether the race of defendants and victims influenced the decision to commute

In Quest of General Pershing

Address presented at the annual dinner of the Beta of Texas Chapter of Phi Beta Kappa on May 2, 196