The closed circuit rebreather (CCR) is not a new diving technology. From the late 1990s CCR units were commercially available in Europe, and increasingly more divers, and among them scientific divers, have been trained to use them. Even if many benefits exist for using CCR for all diving depth ranges, it is in the deep diving zone ranging from 50 m to 100 m of sea water where the main advantages to using this equipment exist. Using rebreathers does carry additional risks, and these must be mitigated to ensure safe usage. A standard for CCR scientific diving has existed for many years in the USA, and the levels of expertise within the European scientific diving community are now sufficient for a European standard to be established. National legislation for occupational scientific diving in many cases excludes CCR diving, which can limit its use for scientific purposes. This paper suggests that, where possible, legislations should be allowed to evolve in order to include this type of equipment where and when its use has direct advantages for both the safety and the efficiency of scientific diving. This paper provides a brief description of the fundamentals of closed circuit rebreather diving and outlines the benefits that its use offers diving scientists. Special attention is given to safety issues with the assertion that the CCR concept is, if strictly applied, the safest available technique today for autonomous deep scientific diving purposes.
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RBINS Staff Publications 2016
The common non-marine ostracod Cypridopsis vidua (O.F. Müller, 1776) is used as a proxy in various biological disciplines, such as (palaeo-)ecology, evolutionary biology, ecotoxicology and parasitology. This morphospecies was considered to be an obligate parthenogen. We report on the discovery of the first population of C. vidua with males from Woods Hole (MA, USA) and determine that it is a population with mixed reproduction. We describe the morphology of the males and of the sexual and asexual females. We illustrate a copula of a male and a sexual female as well insemination in a sexual female, showing that males are functional. Therefore, Cypridopsis vidua is a morphospecies with mixed reproduction, not a full apomictic parthenogen. We use, for the first time, polychromatic polarization microscope technology to illustrate soft parts of ostracods. In addition, we compare the sexual species C. bisexualis, C. okeechobei, C. howei and C. schwartzi and conclude that these species, especially the latter three, are morphologically very close to C. vidua.
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RBINS Staff Publications 2023
Compressional tectonic inversions are classically represented in 2D brittle failure mode (BFM) plots that illustrate the change in differential stress (σ1−σ3) versus the pore-fluid pressure during orogenic shortening. In these BFM plots, the tectonic switch between extension and compression occurs at a differential stress state of zero. However, mostly anisotropic conditions are present in the Earth's crust, making isotropic stress conditions highly questionable. In this study, theoretical 3D stress-state reconstructions are proposed to illustrate the complexity of triaxial stress transitions during compressional inversion of Andersonian stress regimes. These reconstructions are based on successive late burial and early tectonic quartz veins which reflect early Variscan tectonic inversion in the Rhenohercynian foreland fold-and-thrust belt (High-Ardenne Slate Belt, Belgium, Germany). This theoretical exercise predicts that, no matter the geometry of the basin or the orientation of shortening, a transitional ‘wrench’ tectonic regime should always occur between extension and compression. To date, this intermediate regime has never been observed in structures in a shortened basin affected by tectonic inversion. Our study implies that stress transitions are therefore more complex than classically represented in 2D. Ideally, a transitional ‘wrench’ regime should be implemented in BFM plots at the switch between the extensional and compressional regimes.
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