Niedrige Ei- und Körpertemperatur („Hypothermie“) bei brütenden Gelbschnabelsturmtauchern (Calonectris diomedea)
Body and egg temperatures of Cory's Shearwater were recorded in an Aegean colony. Body temperatures of breeding birds were 2 ° C lower than those of non-breeding, resting adults and accounted for 36.7±0.41 ° C in ♂ and 37.6±0.59 ° C in ♀. Incubation temperature, determined telemetrically inside incubated eggs, was 29.6±0.6° C.
Surface temperatures of albatross eggs and nests
ABSTRACT Knowledge of thermal traits is essential for understanding and modelling physiological responses to environmental change. Egg temperatures are poorly studied in most tubenose species. We employed a contactless infrared thermometer to measure egg and nest surface temperatures throughout the incubation period for four albatross species at Bird Island, South Georgia. The observed mean warm-side temperature of 33.4°C for Wandering Albatross (Diomedea exulans) was similar to measurements obtained from this species using dummy eggs elsewhere. Observed mean warm-side temperatures for Black-browed Albatross (Thalassarche melanophris), Grey-headed Albatross (Thalassarche chrysostoma), and Light-mantled Albatross (Phoebetria palpebrata), reported here for the first time, were 30.7–31.5°C, which is lower than the egg temperatures reported for most Procellariiformes. Temperature gradients across viable eggs declined by up to 9°C during incubation, reflecting increased embryonic circulation and metabolic heat production. This suggests that bioenergetic models should not assume constant egg temperatures during embryo development. Non-viable (addled) eggs could be identified by large temperature gradients in late incubation, indicating that infrared thermometry can be used to determine whether the embryo has died or the egg is infertile in monitoring and managed breeding (e.g. translocation) programmes. Egg temperatures were correlated with ground temperatures, indicating that incubated eggs are vulnerable to environmental variability.
Modelling of Mooney viscosity relaxation in natural rubber
Abstract Better assessment of natural rubber (NR) quality and processability, through the identification of new attributes, is still a major challenge. With this scope, 12 model samples of natural polyisoprene and two of synthetic polyisoprene were characterized in terms of Mooney torque relaxation, using the standardized ISO289 method (ML(1+4)100, explained later in the Section 1 ). The main purpose of this study was to identify a model that gave a better fit for the experimental decay of Mooney torque over time (ML(t)=f(t)) than the usual power law model used before (Y=at−b, [G.M. Bristow, A.G. Sears, The use of novel parameters in the assessment of natural rubber processability, NR Technol. 18 (1987); H.G. Burhin, W. Spreutels, J.M. Campbell, MV2000 Mooney viscometer: Mooney relaxation measurements on raw polymers and compounded rubber stocks, Kautsch. Gummi Kunstst. 43 (1990) 431]). The results showed that a generalized Maxwell model, and the Wu–Abbott empirical model ( Y = 1 − a Ln ( t ) − ( b t / ( c + t ) ) ) [T. Wu, J.A. Abbott, Firmness and force relaxation characteristics of tomatoes stored intact or as slices, Postharvest Biol. Technol. 24 (2002) 59–68], recently used for describing stress relaxation of tomato flesh, allowed a better description of the relaxation curve for the samples studied than the power law or stretched exponential traditionally used. Moreover, the total relaxation time (τm) given by the generalized Maxwell model showed good correlation with the total gel content of the samples studied.