Reflections on the Need for a More Complete History of The Deep Ecology Movement and Related Disciplines

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Nonlinear dynamic response of bottom-land deep ocean pipelines

A finite element formulation is developed for the prediction of the large displacement response of pipelines which are placed upon irregularly contoured marine sediments and are subsequently subjected to episodic hydrodynamic loads. The equations of motion during each episode of extreme wave activity are obtained from a variational form of Hamiltons principle and this form of the equations of motion is integrated using the Newmark method of implicit integration. Within each time step a Newton-Raphson iteration scheme is used to achieve equilibrium while accurately tracking the nonlinear path-dependent response. An updated Lagrangian formulation shifts the pipeline reference configuration and separates rigid body movements from pipeline deformations. This provides a large deflection, small strain transient analysis of the pipeline response. Nonlinear, elastic-plastic springs simulate transverse and axial bottom resistance from both cohesive and cohesionless sediments. Inclusion of a pressure differential across the pipe wall modifies tensile stresses and influences the flexural stiffness of the finite element model through the geometric stiffness matrix. Hydrodynamic added mass and nonlinear, viscous drag forces are included by means of the relative-motion form of the Morison equation. The formulation results in a three-dimensional finite element model of a bottom-laid pipeline that is constrained to follow the irregularly contoured ocean bottom. A finite element method computer model is developed and used to predict the pipeline response to both monochromatic and random wave loads. Numerical examples presented demonstrate the validity of the formulation and illustrate the results obtained from sample simulations. It is found that nonlinear structural behavior is a dominant factor in predicting pipeline response and that inclusion of nonlinear effects greatly reduces predicted pipeline displacements. It is further shown that both the directionality of wave attack and the wave length of incident waves significantly alters the magnitude and location of the maximum pipeline response. Computational times for the random wave simulations analyzed were substantial with an approximate ratio of CPU to real time ratio of 105 to 1 being typical for the finite element analysis of a prototype marine pipeline having 150 degrees of freedom

A Psychophysical Comparison of Two Methods for Adaptive Histogram Equalization

Adaptive histogram equalization (ahe) is a method for adaptive contrast enhancement of digital images propped by Pizer et. Al.. It has the properties that it is an automatic, reproducible method for the simultaneous viewing of contrast within a digital image with a large dynamic range. Recent experiments have show that in specific cases, there is no significant difference in the ability of ahe and linear intensity windowing to display grey-scale contrast. More recently, Pizer et al. have proposed a variant of ahe which limits the allowed contrast enhancement of the image. The contrast-limited adaptive histogram equalization (clahe) produces images in which the noise content of an image is nor excessively enhanced, but in which sufficient contrast is provided for the visualization of structures within the image. Images processed with clahe have a more natural appearance and facilitate the comparison of different areas of an image. However, the reduced contrast enhancement of clahe may hinder the ability of an observer to detect the presence of some significant grey-scale contrast. In this work, a psychophysical observer experiment was performed to determine if there is a significant difference in the ability of ahe and clahe to depict grey-scale contrast. Observers were presented with CT images of the chest processed with ahe and clahe into some of which subtle artificial lesions were introduced. The observers were asked to rate their confidence regarding the presence of the lesions; this rating-scale data was analyzed using Receiver Operating Characteristic curving techniques. These ROC curves were compared for significant differences in the observers\u27 performances. In this study, no difference was found in the abilities of ahe and clahe to depict contrast information

The cap-snatching SFTSV endonuclease domain is an antiviral target

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne virus with 12%-30% case mortality rates and is related to the Heartland virus (HRTV) identified in the United States. Together, SFTSV and HRTV are emerging segmented, negative-sense RNA viral (sNSV) pathogens with potential global health impact. Here, we characterize the amino-terminal cap-snatching endonuclease domain of SFTSV polymerase (L) and solve a 2.4-Å X-ray crystal structure. While the overall structure is similar to those of other cap-snatching sNSV endonucleases, differences near the C terminus of the SFTSV endonuclease suggest divergence in regulation. Influenza virus endonuclease inhibitors, including the US Food and Drug Administration (FDA) approved Baloxavir (BXA), inhibit the endonuclease activity in in vitro enzymatic assays and in cell-based studies. BXA displays potent activity with a half maximal inhibitory concentration (I

Light-induced nuclear export reveals rapid dynamics of epigenetic modifications

We engineered a photoactivatable system for rapidly and reversibly exporting proteins from the nucleus by embedding a nuclear export signal in the LOV2 domain from phototropin 1. Fusing the chromatin modifier Bre1 to the photoswitch, we achieved light-dependent control of histone H2B monoubiquitylation in yeast, revealing fast turnover of the ubiquitin mark. Moreover, this inducible system allowed us to dynamically monitor the status of epigenetic modifications dependent on H2B ubiquitylation