Cold Physiology: Postprandial Blood Flow Dynamics and Metabolism in the Antarctic Fish Pagothenia borchgrevinki

Previous studies on metabolic responses to feeding (i.e. the specific dynamic action, SDA) in Antarctic fishes living at temperatures below zero have reported long-lasting increases and small peak responses. We therefore hypothesized that the postprandial hyperemia also would be limited in the Antarctic fish Pagothenia borchgrevinki. The proportion of cardiac output directed to the splanchnic circulation in unfed fish was 18%, which is similar to temperate fish species. Contrary to our prediction, however, gastrointestinal blood flow had increased by 88% at twenty four hours after feeding due to a significant increase in cardiac output and a significant decrease in gastrointestinal vascular resistance. While gastric evacuation time appeared to be longer than in comparable temperate species, digestion had clearly commenced twenty four hours after feeding as judged by a reduction in mass of the administered feed. Even so, oxygen consumption did not increase suggesting an unusually slowly developing SDA. Adrenaline and angiotensin II was injected into unfed fish to investigate neuro-humoral control mechanisms of gastrointestinal blood flow. Both agonists increased gastrointestinal vascular resistance and arterial blood pressure, while systemic vascular resistance was largely unaffected. The hypertension was mainly due to increased cardiac output revealing that the heart and the gastrointestinal vasculature, but not the somatic vasculature, are important targets for these agonists. It is suggested that the apparently reduced SDA in P. borchgrevinki is due to a depressant effect of the low temperature on protein assimilation processes occurring outside of the gastrointestinal tract, while the gastrointestinal blood flow responses to feeding and vasoactive substances resemble those previously observed in temperate species

Improved Stress-Anisotropy Characterization Through Casing in a 43-Year-Old Well Using Sonic and Cement/Borehole Imaging Data

Abstract The RSE-1 well operated by Total is located within the Rousse field in the southwest of France. The 43 year old, depleted gas well has undergone extensive research in order to determine its suitability for CO2 storage. The main objective, in terms of containment, is to avoid the injected CO2 migrating back to the atmosphere or reaching potable aquifers, either through the well or the caprock itself. Openhole data from 43 years ago consisted only of 1-arm caliper and compressional sonic data. In order to predict geomechanical effects on the formation from production or CO2 injection, sonic shear data was acquired to compute elastic properties and the direction of maximum horizontal stresses in anisotropic zones. Breakout orientations from multi-arm/finger-calipers, corresponding to the minimum horizontal stress direction are used to improve the geomechanical analysis, especially in areas of strong stress anisotropy. This paper focuses on the acquisition of good quality stress data through casing essential for a geomechanical analysis of the caprock using sonic and cement/borehole imaging tools. Since azimuthal sonic data is very sensitive to acoustic anisotropy, the available log was processed together with directional survey data to reveal a 75m-thick stress-induced anisotropic zone in the lower part of the caprock. The fast shear azimuth, which is associated with maximum horizontal stress direction as dispersion curves show the sonic anisotropy being the result of a horizontal stress imbalance, suggested a ENE-WSW compression. Evaluation of 3-D cement imaging data showed borehole breakouts along most of the annulus. The cement thickness map is equivalent to a 36-arm caliper through casing and the computed maximum hole diameter correlates well with the 1-arm openhole caliper data acquired 43 years ago. The associated breakout direction within the zone of anisotropy was determined to vary between NNW-SSE and NNE-SSW. The fast shear azimuth computed during sonic processing is approximately perpendicular to the breakout direction acquired from the borehole images within the 75m-thick anisotropic zone. The overall NNE-SSW compression was confirmed by other well geometry data from the region. These results suggest that both measurements complement each other very well in a cased-hole environment and could be further used for geomechanical modeling.</jats:p

Effects of Modern Primary Flight Display Clutter

Many complex domains, including aviation, experience a continued increase in the amount of information that is needed and available to operators. One example of this trend is modern primary flight displays (PFD), some of which now include weather, terrain, and navigation data. The addition of information to already busy displays has raised concerns about clutter. In this experiment, our goal was to investigate the performance and attentional costs associated with PFD clutter during a simulated flight and to determine to what extent pilots are aware of clutter and its effects. Low-, medium-, and high-clutter PFDs were created, and pilots flew a simulated flight scenario containing periods of high and low workload using one of the three PFDs. Pilots were asked to detect various visual alerts and notifications that appeared on the PFD throughout the flight. Performance, eye tracking, and subjective measures were recorded. Clutter significantly increased the response time to alerts, and high workload resulted in more alerts being missed. The eye tracking data provided insight into pilots’ monitoring strategies and efficiency in the different clutter conditions. Spatial density and the number of transitions were found to be larger in the case of higher clutter, whereas the number of fixations on flight mode annunciators was higher in the low-clutter condition. Importantly, pilots rated clutter as being relatively low even in the high-clutter condition. In combination, these results suggest that pilots may benefit from real-time clutter detection and reduction techniques that are based on eye tracking metrics. </jats:p