Alterpolitiques!

International audienc

Restoration of the Long-spined Sea Urchin, <i>Diadema antillarum</i>, to Caribbean Coral Reefs

Coral reefs are among the most valuable and threatened ecosystems on Earth. Lower species diversity, and subsequently reduced resilience, make Caribbean reefs especially vulnerable to anthropogenic stressors. Overfishing and disease have reduced Caribbean herbivore abundances and their associated compensatory dynamics, leading to a 53% decrease in scleractinian coral cover since the 1970s. The long-spined sea urchin, Diadema antillarum, is an important Caribbean herbivore, and its functional extinction in the early 1980s, coupled with a subsequent lack of recovery, makes its restoration a conservation priority. A combination of in situ ecological surveys and environmental manipulations are coupled with ex situ experimental studies to aid D. antillarum restoration efforts. The thesis begins by assessing the relative impacts of fish and urchin grazing on the structure and diversity of reef communities and concludes that, whilst reestablishment of D. antillarum ecosystem functions may not represent a long-term conservation solution, it will provide short-term resilience benefits. A lab-based investigation then indicates that D. antillarum will be, at least partially, resistant to predicted future sea surface temperature increases, and observed negative fitness consequences may be mitigated by artificial structures; population restoration is therefore worthwhile in the context of climate change. Exploration of an isolated population boom then identifies a dearth of predation refugia, created by region-wide reef flattening, as the major barrier to recovery, and deployment of experimental artificial reefs demonstrates that augmentation of reef complexity is a viable strategy for increasing population size and reversing phase shifts. Restoration of D. antillarum will undoubtedly contribute to long-term ecosystem persistence, and insights contained within this thesis may help facilitate the difficult transition of Caribbean coral reefs to their future stable state

Be My Little Teddy Bear

https://digitalcommons.library.umaine.edu/mmb-vp/5094/thumbnail.jp

Compressibility anomalies in stretched water and their interplay with density anomalies

Water keeps puzzling scientists because of its numerous properties which behave oppositely to usual liquids: for instance, water expands upon cooling, and liquid water is denser than ice. To explain this anomalous behaviour, several theories have been proposed, with different predictions for the properties of supercooled water (liquid at conditions where ice is more stable). However, discriminating between those theories with experiments has remained elusive because of spontaneous ice nucleation. Here we measure the sound velocity in liquid water stretched to negative pressure, and derive an experimental equation of state, which reveals compressibility anomalies. We show by rigorous thermodynamic relations how these anomalies are intricately linked with the density anomaly. Some features we observe are necessary conditions for the validity of two theories of water.Comment: 17 pages, 3 figures, 24 reference

An investigation of susceptibility to porcine reproductive and respiratory syndrome virus between two genetically diverse commercial lines of pigs

The objective of this study was to determine whether host genetics play a role in susceptibility to the respiratory disease in growing pigs caused by the porcine reproductive and respiratory syndrome virus (PRRSV). Based on a previous study, 2 genetically diverse commercial lines of pigs that also were divergent in the susceptibility of monocyte-derived macrophages to PRRSV infection in vitro were selected for an in vivo challenge study. Based on the average percentage of infected macrophages for each line, a line derived from the Large White breed was characterized as fluorescence-activated cell sortinghi (FACShi), and a line derived from Duroc and Pietrain breeds was characterized as FACSlo. Pigs from each line were challenged at 6 wk of age with PRRSV VR-2385 and necropsied at 10 or 21 d after infection. Data collected included clinical evaluation of disease, virus titration in serum and lung lavage fluid, macroscopic lung lesion scores, and microscopic lung lesion scores. The FACSlo line had consistently more severe clinical disease compared with the FACShi line in the early stages of infection. Differences between line means were significant (P \u3c 0.05) at 10 d after infection for all variables just described, and the FACSlo line showed more severe signs of disease. By 21 d after infection, clinical signs and lesions were resolving, and the differences between lines were significant (P \u3c 0.04) only for microscopic lung lesion scores but approached significance (P \u3c 0.08) for virus titer in serum. At 21 d after infection, the relationship between the lines reversed; the FACShi line had higher serum virus titers than the FACSlo line. This report provides evidence that strongly suggests the existence of a host genetic component in disease susceptibility to PRRSV and indicates that further study is warranted to define the cellular mechanisms that affect disease susceptibility

Heat conduction in the cable insulation of force-cooled underground electrical power transmission systems

Forced cooling of underground electric power transmission lines, pt.2Forced-cooled systems for oil-filled pipe-type cable circuits have recently been considered. In such systems the conduction resistance through the paper insulation of the cables is the limiting thermal resistance. Assuming bilateral symmetry, steady-state conditions, and two-dimensional heat transfer, a FORTRAN IV computer program was written to solve the heat conduction problem in the cable insulation for arbitrary configurations of a three-cable system. For a steel pipe, a cable system is most susceptible to overheating in the equilateral configuration with the three cables touching. Proximity effects are very significant in forced cooling, especially when cables are not provided with a copper tape under the insulation moisture seal assembly, accounting for as much as 21% of the total oil temperature rise between refrigeration stations. This figure, however, is reduced to 8% when 0.005 inch thick copper tape is present.Consolidated Edison Co. of New Yor