scholarly journals Effects of temperature on growth and development of amphibian larvae across an altitudinal gradient in the Tibetan Plateau

2020 ◽  
Vol 70 (3) ◽  
pp. 239-250
Author(s):  
Li Qing Peng ◽  
Min Tang ◽  
Jia Hong Liao ◽  
Shi Yuan Liang ◽  
Li Tao Gan ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Low Temperatures ◽  
Growth And Development ◽  
Extreme Environments ◽  
Early Growth ◽  
Temperature Treatment ◽  
Temperature Adaptation ◽  
High Temperature Treatment ◽  
The Tibetan Plateau ◽  
Amphibian Larvae

Abstract Organisms living in extreme environments, such as amphibians inhabiting the Tibetan plateau, are faced with a magnitude of potentially strong selection pressures. With an average elevation exceeding 4500 m, the Tibetan plateau is mainly characterized by low temperatures, but little is known about the influence of this factor on the growth, development, and behaviour of amphibian larvae living in this environment. Using a common garden experiment, we studied the influence of temperatures on the early growth and development of tadpoles of the Tibetan brown frog (Rana kukunoris) endemic to the eastern Tibetan plateau. We discovered that temperature had a significant influence on early growth and development of the tadpoles, with those undergoing high-temperature treatment growing and developing faster than their siblings from a low-temperature treatment. However, high-altitude individuals grew faster than low-altitude individuals at low temperatures, while the opposite was true at high temperatures. These results support the temperature adaptation hypothesis, as tadpoles’ growth and developmental rates were maximized at the temperatures experienced in their native environments. These results suggest that variation in ambient temperature, combined with evolutionary adaptation to temperature of local environments, is probably one of the most critical environmental factors shaping altitudinal differences in the growth and development of amphibian larvae on the Tibetan plateau.

Passcal instrument performance during the Tibetan Plateau Passive Seismic Experiment

1993 ◽  
Vol 83 (6) ◽  
pp. 1959-1970
Author(s):  
Thomas J. Owens ◽  
George E. Randall ◽  
Francis T. Wu ◽  
Rongsheng Zeng
Keyword(s):  
Tibetan Plateau ◽  
Extreme Environments ◽  
Low Frequency ◽  
Rocky Mountain ◽  
Spatial Density ◽  
Frequency Noise ◽  
The Tibetan Plateau ◽  
Seismic Experiment ◽  
Deep Earth Structure ◽  
Passive Seismic

Summary The PASSCAL instrumentation performed very well in the Tibetan Plateau Seismic Experiment. This experiment has demonstrated the viability of recording high-quality broadband data at temporary sites in extreme environments. It also highlights some areas where further development is needed. Primarily, more effort is needed to develop more versatile triggering options for the PASSCAL instruments. Such developments could both increase the instrument's success at recording low magnitude teleseismic events for travel-time studies and save disk space when recording local events, thus further increasing the feasibility of long deployments in remote regions. Although the use of the PASSCAL instrument's calibration circuitry for sensor recentering is a valuable technique, more experience is needed in the construction of sensor pads to minimize tilt problems that require site visits to relevel the seismometer such as we experienced at a few sites in the winter. This may also lead to improved low-frequency noise levels, although signals with periods greater than 200 sec can be recovered from these sites. The most exciting aspect of the data we have collected is its broad frequency content and spatial density. We anticipate that this type of experiment will be increasingly useful in the study of lithospheric interactions as well as deep Earth structure. This data was delivered to the IRIS Data Management Center in early September 1993 and is available to the community. Two other broadband passive-seismic experiments, the Baikal Rift experiment (Gao et al. 1992) and the Rocky Mountain Front experiment (Sheehan et al. 1992) should be delivered to the IRIS DMC in the Fall of 1993 as well. Temporary broadband seismic experiments represent an extension of the permanent Global Seismic Network (GSN). We encourage the seismological community to incorporate these data into any research using GSN data in order to maximize the potential utility of this new mode of seismic recording.

scholarly journals Methanogenesis from Methanol at Low Temperatures by a Novel Psychrophilic Methanogen, “Methanolobus psychrophilus” sp. nov., Prevalent in Zoige Wetland of the Tibetan Plateau

2008 ◽  
Vol 74 (19) ◽  
pp. 6114-6120 ◽  
Author(s):  
Guishan Zhang ◽  
Na Jiang ◽  
Xiaoli Liu ◽  
Xiuzhu Dong
Keyword(s):  
Tibetan Plateau ◽  
Methane Emission ◽  
Low Temperatures ◽  
Methanol Conversion ◽  
Wetland Soil ◽  
The Tibetan Plateau ◽  
Hydrogenotrophic Methanogenesis ◽  
Efficient Type ◽  
Zoige Wetland ◽  
A New Species

ABSTRACT The Zoige wetland of the Tibetan plateau is at permanent low temperatures and is a methane emission heartland of the plateau; however, cold-adaptive methanogens in the soil are poorly understood. In this study, a variety of methanogenic enrichments at 15�C and 30�C were obtained from the wetland soil. It was demonstrated that hydrogenotrophic methanogenesis was the most efficient type at 30�C, while methanol supported the highest methanogenesis rate at 15�C. Moreover, methanol was the only substrate to produce methane more efficiently at 15�C than at 30�C. A novel psychrophilic methanogen, strain R15, was isolated from the methanol enrichment at 15�C. Phylogenetic analysis placed strain R15 within the genus Methanolobus, loosely clustered with Methanolobus taylorii (96.7% 16S rRNA similarity). R15 produced methane from methanol, trimethylamine, and methyl sulfide and differed from other Methanolobus species by growing and producing methane optimally at 18�C (specific growth rate of 0.063 � 0.001 h−1) and even at 0�C. Based on these characteristics, R15 was proposed to be a new species and named “Methanolobus psychrophilus” sp. nov. The Km and V max of R15 for methanol conversion were determined to be 87.5 � 0.4 μM and 0.39 � 0.04 mM h−1 at 18�C, respectively, indicating a high affinity and conversion efficiency for methanol. The proportion of R15 in the soil was determined by quantitative PCR, and it accounted for 17.2% � 2.1% of the total archaea, enumerated as 107 per gram of soil; the proportion was increased to 42.4% � 2.3% in the methanol enrichment at 15�C. This study suggests that the psychrophilic methanogens in the Zoige wetland are likely to be methylotrophic and to play a role in methane emission of the wetland.

scholarly journals Continental subductions and Tibetan plateau growth

2013 ◽  
Vol 46 ◽  
Author(s):  
Stephane Guillot ◽  
Anne Replumaz
Keyword(s):  
Tibetan Plateau ◽  
Early Growth ◽  
The Tibetan Plateau ◽  
Upper Crust ◽  
Metamorphic Petrology ◽  
Continental Lithosphere ◽  
Southern Tibet ◽  
Northern Tibetan Plateau ◽  
Northern Portion ◽  
Cenozoic Magmatism

How and when the Tibetan plateau developed has long been a puzzling question with implications for the current understanding of the behaviour of the continental lithosphere in convergent zones. We present and discuss recent data acquired in geology and geophysics and through igneous and metamorphic petrology and palaeo-altitude estimates. This research indicates that Tibet initiated from the accretion of the Gondwana continental blocks to the southern Asian margin during the Palaeozoic and Mesozoic eras. These successive accretions have potentially favoured the creation of local landforms, particularly in southern Tibet, no evidence exists in favour of the existence of a proto-Tibetan plateau prior to the Cenozoic. By the time the India-Asian collision began it was cold enough to transfer stress but that does not mean there was not a proto-plateau prior to collision. Depending on the types of Paleozoic and Mesozoic collisions, the sutures terranes could be cool enough to transfer stress, especially in the upper crust. However, these successive accretions associated with subductions have metasomatized the Tibetan lithospheric mantle and largely explain the potassium- and sodium-rich Cenozoic magmatism. Another consequence of this contamination by fluids is the softening of the Tibetan lithosphere, which favoured intra­continental subductions. The timing and the geochemical signatures of the magmatism and the palaeo-altitudes suggest the early growth of the Tibetan plateau. By Eocene time, the southern plateau and the northern portion of Himalaya were at an altitude of approximately 4000 metres, while the central and northern Tibetan plateau was at altitudes of approximately 2000 to 3000 meters at the Eocene-Oligocene transition. From all of these data, we propose a model of the formation of the Tibetan plateau coupled with the formation of Himalaya, which accounts for more than 2500 km of convergence accommodated by the deformation of the continental lithosphere.

Phase Formation at Pd/Si1−xGex Interfaces

1991 ◽  
Vol 238 ◽  
Author(s):  
A. Buxbaum ◽  
M. Eizenberg ◽  
A. Raizman ◽  
F. Schäffler
Keyword(s):  
Low Temperatures ◽  
Molecular Beam ◽  
Ternary Phase ◽  
Strain Relaxation ◽  
Electrical Characterization ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Treatment Results ◽  
Barrier Heights

ABSTRACTIn this work we describe the interaction of Pd with Si1−xGex layers in terms of structure, composition and electrical properties. Strained epitaxial layers of Si1−xGex with x=0.09 and 0.18 were grown on Si (100) by Molecular Beam Epitaxy (MBE) at a growth temperature of 550°C, to a thickness of 3300Å and 2300Å, respectively, and then capped with a 100Å Si layer. At low temperatures (around 250°C), the formation of a ternary phase Pd2Si1−xGex along with small amounts of PdGe takes place. At high temperatures (around 550°C), the interaction is characterized by the formation of a double layered structure, where a Ge rich Si1−xGex region is formed between the Pd2Si1−xGex compound and the unreacted Si1−xGex. The high temperature treatment results in strain relaxation in the epilayer below the compound region. Electrical characterization of diodes formed from these layers clearly shows they are rectifying, with Schottky barrier heights around 0.65 eV.

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