Cold stress adaptation

Very litde research on the biochemistry or physiology of brown adipose tissue has been done in humans. Most of the work on both obesity and adaptation to cold stress has been done on small mammals, such as rats, mice, and hamsters. What role, if any, brown fat deposits play in the development or prevention of obesity in humans is an open question for researchers. Recently, researchers have devoted much energy toward identifying the... 

In similar stress experiments following therapy with orally administered vitamin B12, no significant differences were observed in the determinations before and after therapy. Consequently, adaptation to the stress was not the cause of the changes which occurred following pantothenate therapy. The decrease in the eosinopenia and in uric acid/ creatinine ratio after pantothenate treatment suggests that the same environmental stress constituted a less severe stimulus to the adrenal cortex under these conditions. It may be that the increased level of pantothenate in the tissue cells contributed to their capacity to carry out the oxidative reactions which are part of the total physiological response to cold stress. It is possible that under these conditions the demand for adrenocortical hormones might be somewhat reduced. 

The high freezing tolerance of many lichens cannot be the reason for their restricted distribution over the world. As is evident from their photosynthetic activity, the phycobionts have a wide range of adaptation to cold environments. The metabolic nature of the mycobionts is probably a decisive reason for the distribution and adjustment of lichen species in extreme environments. Our knowledge about the response of lichens to cold stress is, however, based on a selected list of tested species. It may be that fastgrowing species with a short life cycle (like some terricolous lichens or even... 

Plants that do resist such stresses must have developed particular strategies of adaptation eolleetively known as eold hardiness or cold resistance. In general, plants become resistant to freezing by various meehanisms, the most important of whieh are ... 

Figure 5.12 Thermomechanical behavior of SMPFs by both cold and hot tension programmings, (a) Stress-strain-time diagram for Sample 2. Steps 1 to 5 complete programming and Step 6 completes stress recovery, where step 1 is to stretch the fiber bundle to 100% strain at a rate of200 ram/min at 100 °C step 2 is to hold the strain constant for 1 hour step 3 is to cool the fiber to room temperature slowly while holding the pre-strain constant step 4 is to release the fiber bundle from tbe fixture (unloading) step 5 is to relax the fiber in the stress-free condition until the shape is fixed and step 6 is to recover the fiber at 150 °C in the fully constrained condition (adapted from Reference [20]) (b) Stress-strain-time diagram for Sample 3. Steps 1-4 complete programming and step 5 completes stress recovery, where step 1 is to stretch the fiber bundle to 100% strain at a rate of 200 mm/min at room temperature step 2 is to hold the strain constant for 1 hour step 3 is to release the fiber bundle from fixtures (unloading) step 4 is to relax the fiber in the stress-free condition until the shape is fixed and step 5 is to recover the fiber at 150 °C in the fully constrained condition (adapted from Reference [20]) (c) Stress evolution with time for Sample 2 (d) Stress evolution with time for Sample 3.

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