Application de la methode de fixation-coloration de Maillet à certains Invertébrés

Maillet’s osmium-zinc iodide technique gave the most interesting results and demonstrated the presence of amyelinated fibers in vertebrates. This method therefore was tried for invertebrates, including the Mollusca, where it proved fully efficient

Endometrium Cell Surface Abnormalities in the Syrian Hamster as a Result of In Utero Exposure to Diethylstilbestrol

Scanning electron microscopy (SEM) was used to observe changes in the hamster endometrium cell surface following in utero pre- and/or postnatal exposure to diethylstilbestrol (DES). Some of the changes in cell surfaces are associated with alterations in cell sizes and shapes (from columnar to cuboidal and/or squamous) and in microvilli and mucous secretion. In all cases, DES treated uteri show mucosal cell surface pleomorphism, apocrine secretion and cystic accumulation of secretory material. Microvillous pleomorphism and peculiar linkages attaching one microvillus to others were investigated. Although the function and nature of such linkages is unclear, their presence seems to be more prominent in the in utero DES treated hamster endometrium. These infrastructures may provide a support for the microvilli distributed on the mucosal cell surfaces, i.e., a morphological compromise between the single microvillous surface and the microridged structures. These interconnections may represent glycocalyx material or remodeling of cell surfaces toward squamous epithelium

Transplacental Cardiotoxicity of Cocaine: Atrial Damage Following Treatment in Early Pregnancy

Using light, transmission (TEM) and scanning (SEM) electron microscopy, cocaine-induced defects were observed in hamster atria. Compared with controls, the treated atria from neonates show endocardial and myocardial damages as the atrial walls thicken. SEM micrographs show intensive blebbing, damage and incomplete coverage of myocardium by the endocardial endothelium. TEM data demonstrate blebs, thinning, and other endothelial cell injuries and complement the SEM findings. Areas of endothelial sloughing may facilitate the formation of luminal and mural thrombi as noticed in many neonatal atria. Adjacent subendocardial myocardial cells display contraction bands, swellings, and vacuolizations. Local and large areas of damaged myocardial cells are observed in the subendothelial spaces; they contact fibroblasts squeezed or intercalated between the subendocardial spaces and the basal side of damaged endothelial cells. Many of these defects correspond to well-known ischemic changes. One can hypothesize that cocaine-induced defects appear to be linked to membranous alterations, including those associated with the endothelial cells of the endocardium

Control-informed geometric optimisation of wave energy converters

This paper concerns the interplay between the physical geometry of a wave energy converter (WEC) and the control strategy adopted for the converter, with the ultimate aim of optimising the energy output of the device. An energy-based performance function is employed and we attempt to perform numerical optimisation of a heaving buoy employing a latching control strategy. We allow both draught and radius of the axisymmetric buoy to be adjusted using a numerical optimisation. A linear time-domain hydrodynamic program is used in order to simulate the device motion, while the optimization problem is solved by means of a simplex method. Results show the difference in the frequency response of an optimal buoy for a particular sea-state designed with and without knowledge of the control system

Optimal Damping Profile for a Heaving Buoy Wave Energy Converter

This paper discusses optimal damping profiles for a heaving buoy Wave Energy Converter (WEC) with a single degree of freedom. The goal is to examine how the device can be controlled to harvest maximum energy from incident waves. Both latching and declutching strategies are allowed via a general parametrization of the damping force. Ultimately, the research attempts to determine the best control strategy to apply considering the relative resonant frequency of the device and the monochromatic wave frequency set

Optimal Damping Profile for a Heaving Buoy Wave Energy Converter

This paper discusses optimal damping profiles for a heaving buoy Wave Energy Converter (WEC) with a single degree of freedom. The goal is to examine how the device can be controlled to harvest maximum energy from incident waves. Both latching and declutching strategies are allowed via a general parametrization of the damping force. Ultimately, the research attempts to determine the best control strategy to apply considering the relative resonant frequency of the device and the monochromatic wave frequency set

A study on Prediction Requirements in time-domain Control of Wave Energy Converters

Wave energy converters (WECs) based on oscillating bodies or oscillating water columns would earn huge benefits from a time-domain control on a wave by wave basis. Such a control would allow efficient energy extraction over a wider range of frequencies than what could possibly be achieved when no real-time control is adopted, thus increasing the economical attractiveness of the WECs. Almost every control strategy that showed some potential, however, sffers from the problem that future knowledge of the incident wave elevation, or wave excitation force, is required. In this paper a general control framework for oscillating WECs is presented and a methodology to understand and quantify the wave excitation force prediction requirements, along with the achievable prediction accuracy, is discussed. The two features are compared against each other and linked to the dynamic characteristics of a device. Along with the qualitative discussion, the methodology is applied to some heaving cylinders when reactive control and linear passive control are applied, under different sea conditions