RONE POSITIONING WAS ADVOcated 30 years ago 1 to improve oxygenation in patients with hypoxemic acute respiratory failure (ARF) receiving mechanical ventilation. Dramatic oxygenation improvement using prone positioning was reported in severely hypoxemic patients. 2 The mechanism of how the prone position improves oxygenation in this setting is still unclear. Postulated hypotheses in humans include alveolar recruitment, 3 redistribution of ventilation 4 toward dorsal areas that remain well Author Affiliations are listed at the end of this article.

In this paper, the absolute calibration of photostimulable image plates (IPs) used as proton detectors is presented. The calibration is performed in a wide range of proton energies (0.5-20 MeV) by exposing simultaneously the IP and calibrated detectors (radiochromic films and solid state detector CR39) to a source of broadband laser-accelerated protons, which are spectrally resolved. The final result is a calibration curve that enables retrieving the proton number from the IP signal.

ABSTRACT1. Grouper are of considerable economic value in tropical and subtropical regions and most particularly in south-east Asia. Moreover, it is in Asia, where this fish is highly prized, that the grouper farming began in the 1980s.2. The organoleptic qualities of the groupers are not the only characteristics to be appreciated; in culture, their robustness in heavily populated conditions, as well as their rapid growth at elevated temperatures makes them a good species for aquaculture. However, it is, above all, market demand that is outstripping the supply of fish, which is motivating the expansion of grouper aquaculture.3. At the present time, aquaculture is unable to satisfy demand. The chronic shortage of broodstock means that the alevins, destined for aquaculture, are taken mainly from natural habitats with the aid of fish traps, nets and cyanide, thus contributing to the destruction of south-east Asian reefs. Nevertheless, research is progressing and the number of species whose reproduction is totally controlled is increasing. It is in Taiwan that grouper aquaculture is at its most advanced with a total of five species being raised. 4. Aquaculture is divided into four stages, carried out by different farmers, allowing a more rapid turnover for each farmer and therefore a better financial return. On the other hand, in the Mediterranean at present time, there are no completely controlled grouper captive-breeding programmes. The first attempts at controlled breeding have been carried out since 1995 in Italy, Croatia and Greece. However, farming groupers in captivity, and in particular the control of their reproduction, poses numerous problems.

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Manuscript total length = 4461 words 14 15What is already known: Telomeres shorten with age in most endotherm species, but the 16 picture in other vertebrate species and especially in fish remains less clear. In endotherms, 17 telomeres shorten more rapidly when facing stressful environmental conditions, but this has 18 never been tested in fish species. 19What this study adds: We first review the results of the 14 studies investigating age-related 20 changes in telomere length in fish species (Table 1) and then provide new data showing 21 telomere shortening with age in a very long-lived fish, both at the intra-and at the inter-22 individual levels. In addition, we showed that a chronic sublethal heat stress could accelerate 23 telomere erosion, suggesting that stressful environmental conditions could also accelerate 24 telomere shortening in fish species. 25 Abstract 26Telomeres shorten at each cell division due to the "end-replication problem", but also in 27 response to oxidative stress. Consequently telomeres shorten with age in many endotherms, 28 and this shortening is accelerated under stressful environmental conditions. Data in 29 ectotherm vertebrates remain scarce so far, so our goal was to review existing data for fish, 30and to test the influence of age and stress on telomere length in a very long-lived fish, the 31 Siberian sturgeon (Acipenser baerii). 32Our review of the literature revealed age-related telomere shortening in approximately half 33 of the published studies. In the Siberian sturgeon, we found a significant telomere 34 shortening with age, both at the intra-individual level using red blood cells (-12.5% in 16 35 months) and at the inter-individual level using cross-sectional samples of fin over an age-36 range of 8 years. We also found that heat stress (30°C) significantly reduced telomere length 37 by 15.0% after only 1 month of exposure. Our results highlight that both age and stressful 38 environmental conditions might be important determinants of telomere length in fish. 39 40