Pattern Of Heat Loss Research Articles

Heat flow in Triton: Implications for heat sources powering recent geologic activity

Triton's surface shows clear evidences of resurfacing processes such as volcanism, tectonic structures and a very low presence of impact basins, which indicates that Triton's interior could remain active currently. It is generally assumed in icy satellites that the depth of faulting associated with large faults corresponds to the brittle-ductile transition (BDT), and the properties of large faults penetrating to the BDT depth can be used to obtain information on the mechanical behavior of the lithosphere, and potentially can contribute to constrain the thermal state of a planetary body. Here we present a detailed study of Raz Fossae, suggesting that this structure is not only limited to the graben originally described in previous works. Our study shows that north of the classical Raz Fossae there is another trough set with similar structural characteristics that can be interpreted as part of the same system of faults. We have calculated surface heat flows for Triton from the depth of the BDT under both structures: Raz Fossae and the new northern trough set from a detailed analysis of the troughs widths, taking into account the possible composition of the ice shell (H2O and NH3·2H2O). Our results show surface heat flows values much higher than those estimated in previous studies by modeling radiogenic production and tidal dissipation for fixed orbital eccentricities. Furthermore, our results suggest regional differences in the pattern of heat loss throughout Triton's lithosphere.

Thermoregulation in polar seals: Profiling surface heat in Weddell seals

Our understanding of thermoregulation in marine mammals is ambiguous at best, due to the conflicting needs of homeostasis in air and water. Infrared imaging (IRT) has become increasingly applied to wildlife research given the non‐invasive nature of the technology, which is particularly desirable for work with species that are at risk and/or difficult to handle. Our prior work identified species‐specific patterns of heat loss by season and body condition under controlled conditions. As part of a larger study, we are assessing the use of IRT under extreme Antarctic field conditions to determine baseline and variation in thermal profiles in animals of known condition and physiological state. Weddell seals show consistent hot spots around the poorly insulated head and well‐insulated but active axilla. The trunk and neck are typically cool, whereas flippers are variable. Best fit LME showed ambient temperature, relative humidity and blubber depth to be the primary predictors of IRT signatures. Animal, body site and wind speed were not significant. Profiles were similar between wet and dry seals, however, dry animals can have surface temperatures that are only marginally above ambient, greatly minimizing heat loss. Funded by NSF.

A new device to remotely measure heat flux and skin temperature from free-swimming dolphins

To enhance our understanding of how aquatic endotherms respond thermally to their environment, we present two new designs for recording heat flux (HF) and skin temperature ( T s) from the dorsal fins of free-ranging dolphins. The first package, held on by a series of small suction cups, was designed for short-term deployments on the order of hours. The second package, a long-term attachment, was held on via two 5.0-mm -Delrin® pins and was designed for deployments on the order of days. The former version was configured to release remotely, by way of a galvanic linkage, removing the need to re-capture tagged dolphins. The latter was designed to be removed after re-capture of the individual but also included a fail–safe galvanic release. One of the major advances of our approach is that it allows both convective and conductive pathways of heat loss to be dynamically recorded from free-swimming wild dolphins, whereas previous approaches have recorded primarily conductive heat loss from trained captive or restrained wild dolphins. The short-term, re-usable package has been field-tested on 55 bottlenose dolphins ( Tursiops truncatus) in Sarasota Bay, Florida and the long-term device on two spotted dolphins ( Stenella attenuata) in the eastern tropical Pacific Ocean. By also incorporating into each package a time–depth–velocity recorder we were able to examine patterns of heat flux in relation to changing behavioural states of the tagged individual. Heat flux recorded at the dorsal fin was found to be individually variable and dynamic. Water temperature ( T w) had a profound effect on patterns of heat loss in both species with HF increasing with even minor decreases in T w. This device significantly improves our ability to understand the thermal biology of dolphins as they move about in their natural environment.

Changes in pattern of heat loss at high ambient temperature caused by water deprivation in a large flightless bird, the emu.

When exposed to high ambient temperatures, birds defend body temperature by increasing evaporative water loss, via either respiratory or cutaneous water loss. Water deprivation can lead to changes in thermal responses and lower levels of water use for thermoregulation. We have studied the effect of 2-3 wk of water deprivation on the physiological responses of emus during exposure to an ambient temperature of 45 degrees C. Water deprivation led to a delay in the onset of panting (54 vs. 24 min after start of exposure) and to higher body temperatures (38.7 degrees vs. 38.3 degrees C) at the end of exposure to 45 degrees C. After panting was initiated and body temperature stabilised, the water-deprived emus had a lower total evaporative water loss (77 vs. 101 g/h), the same respiratory water loss (70 vs. 72 g/h), and a lower cutaneous water loss (7 vs. 29 g/h) than they did when hydrated. The factor contributing most to the lower total evaporative water loss in the dehydrated emus was a 47% reduction in dry thermal conductance, which led to a decrease in the exogenous environmental heat load and therefore the level of evaporation needed to defend body temperature. We suggest that the decrease in dry thermal conductance follows from the lower level of cutaneous water loss.

Temperature Regulation of the Pyrrhuloxia and the Arizona Cardinal

Temperature Regulation of the Pyrrhuloxia and the Arizona Cardinal