[1] Long-term alkenone-based pCO2 records are widely applied in paleoclimate evaluations. These pCO2 estimates are based on records of the carbon isotope fractionation that occurs during marine haptophyte photosynthesis (ep37:2). In addition to the concentration of aqueous CO2 (CO2(aq)) the magnitude of ep37:2 is also influenced by algal growth rates and cell geometry. To date, the influence of...

The arterial to end-tidal PCO2 difference (PaCO2-PE'CO2) was measured in five anaesthetized dogs during controlled ventilation at 0.25 Hz (15 b.p.m.) and during high frequency jet ventilation at 1, 3 and 5 Hz. Because of the slow response of the infra-red carbon dioxide analyser, satisfactory recordings of end-tidal carbon dioxide could not be obtained at frequencies greater than 1 Hz. The inte...

Hazards of carbon dioxide insufflation during thoracoscopy Editor,—I read with interest the review article on the anaesthetic implications of thoracoscopic sympathectomy. 1 When endobronchial anaesthesia is used, carbon dioxide may be insufflated only initially into the ipsilateral pleural space to augment lung collapse. In contrast , when a tracheal tube is used, carbon dioxide is insufflated ...

Arterialized ear lobe blood samples have been described as adequate to gauge gas exchange in acute and chronically ill patients. It is a safe procedure, usually performed by medical technicians. We have conducted a prospective study to verify the validity of this method. One hundred and fifteen consecutive adult patients were studied. Blood samples were drawn simultaneously from arterialized ea...

A bstract. A supernatant fraction, free of plstids, was prepared by centrifugation from Euglena gracilis and used to ascertain whether or not the inhibition of carbon dioxide fixation by oxygen, known as the Warburg effect, is entirely independent of the light-driven phase of photosyn-thesis. This fraction exhibited in the dark the main features of the Werburg effect; namely, an inverse relatio...

In the tropical fresh water fish, Synbranchus marmoratus, transition from water breathing to air breathing, induced by reduction of oxygen partial pressure (PO2) in the environmental water below 16 mmHg, causes a considerable rise in the arterial partial pressure of carbon dioxide (PCO2), from 5.6 to 26 mmHg on the average (half time of the rise between 2 and 6.5 h). The associated fall in arte...

We hypothesized that the acute ventilatory response to carbon dioxide in the presence of low and high levels of oxygen would increase to a greater extent in men compared with women after exposure to episodic hypoxia. Eleven healthy men and women of similar race, age, and body mass index completed a series of rebreathing trials before and after exposure to eight 4-min episodes of hypoxia. During...

In densely populated communities, such as coral reefs, organisms can modify the physical and chemical environment for neighbouring individuals. We tested the hypothesis that colony density (12 colonies each placed ∼0.5 cm apart versus ∼8 cm apart) can modulate the physiological response (measured through rates of calcification, photosynthesis and respiration in the light and dark) of the coral ...

In the first comparative consideration of the metabolism of avian embryos, Rahn et al. (1974) made several important assumptions and offered a number of interesting predictions. One of their assumptions was that the relation between metabolic rate and incubation age (days incubated) is the same in all avian species as it is in the chicken (Gallus gallus). A second important assumption was that ...

Leaf structure has been shown to be an important determinant of leaf photosynthetic characteristics, yet the nature of this relationship remains ambiguous. It has been suggested that intra-leaf shading of chloroplasts may explain the negative influence of increasing leaf thickness/density on mass-based photosynthesis. To explore further the importance of light-mediated functional limitations co...