scholarly journals Operant conditioning in antlion larvae and its impairment following exposure to elevated temperatures

2021 ◽  
Author(s):  
Krzysztof Miler ◽  
Inon Scharf
Keyword(s):  
Climate Change ◽  
Body Size ◽  
Elevated Temperature ◽  
Operant Conditioning ◽  
Cognitive Abilities ◽  
Elevated Temperatures ◽  
Rare Events ◽  
The Third ◽  
Ambush Predators ◽  
Antlion Larvae

AbstractAlthough ambush predators were previously considered limited in their cognitive abilities compared to their widely foraging relatives, there is accumulating evidence it does not hold true. Pit-building antlions are already known to associate vibrations in the sand with the arrival of prey. We used a T-maze and successfully trained antlions to turn right or left against their initial turning bias, leading to a suitable substrate for digging traps. We present here the first evidence for operant conditioning and T-maze solving in antlions. Furthermore, we show that exposure of second instar larvae to an elevated temperature led to impaired retention of what was learned in a T-maze when tested after moulting into the third instar, compared to larvae raised under a more benign temperature. We suggest that climate change, involving an increase in mean temperatures as well as rare events (e.g., heatwaves) might negatively affect the retention of operant conditioning in antlions, alongside known, more frequently studied effects, such as changes in body size and distribution.

scholarly journals Flowering season of vernal herbs is shortened at elevated temperatures with reduced precipitation in early spring

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bo Eun Nam ◽  
Jae Geun Kim
Keyword(s):  
Climate Change ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Early Spring ◽  
Spring Frost ◽  
Flowering Season ◽  
Phenological Shifts ◽  
Higher Temperature ◽  
Herb Species ◽  
Two Temperature

Abstract Vernal herbs are exposed to the risk of climate change under spring frost and canopy closure. Although vernal herbs contribute to the biodiversity of the understorey layer in temperate forests, few studies assessed the effect of climate change on the phenology of the herbs. To examine phenological shifts in flowering seasons of vernal herb species caused by climate change, a greenhouse experiment was conducted using four species (Adonis amurensis, Hepatica nobilis var. japonica, Viola phalacrocarpa, and Pulsatilla cernua) under two temperature conditions (ambient or elevated temperature) and two precipitation conditions (convective or reduced precipitation). Experimental warming advanced overall aspects of the flowering timing including the first and last day of flowering. The growth of flowering stalk was also promoted by elevated temperature. Effects of decreased precipitation varied among species, which advanced the last day of the flowering of the later flowering species. Consequently, a decrease in overall flowering period length was observed. These results indicate that overall, climate change results in a shortening of the flowering season of vernal herb species, specifically at a higher temperature and under conditions of less precipitation.

scholarly journals A Farewell to the Encephalization Quotient: A New Brain Size Measure for Comparative Primate Cognition

2021 ◽  
pp. 1-12
Author(s):  
Carel P. van Schaik ◽  
Zegni Triki ◽  
Redouan Bshary ◽  
Sandra A. Heldstab
Keyword(s):  
Body Size ◽  
Cognitive Abilities ◽  
Brain Size ◽  
Estimation Error ◽  
Primate Species ◽  
Mammal Species ◽  
Mean Values ◽  
Encephalization Quotient ◽  
Body Sizes ◽  
Size Measure

Both absolute and relative brain sizes vary greatly among and within the major vertebrate lineages. Scientists have long debated how larger brains in primates and hominins translate into greater cognitive performance, and in particular how to control for the relationship between the noncognitive functions of the brain and body size. One solution to this problem is to establish the slope of cognitive equivalence, i.e., the line connecting organisms with an identical bauplan but different body sizes. The original approach to estimate this slope through intraspecific regressions was abandoned after it became clear that it generated slopes that were too low by an unknown margin due to estimation error. Here, we revisit this method. We control for the error problem by focusing on highly dimorphic primate species with large sample sizes and fitting a line through the mean values for adult females and males. We obtain the best estimate for the slope of circa 0.27, a value much lower than those constructed using all mammal species and close to the value expected based on the genetic correlation between brain size and body size. We also find that the estimate of cognitive brain size based on cognitive equivalence fits empirical cognitive studies better than the encephalization quotient, which should therefore be avoided in future studies on primates and presumably mammals and birds in general. The use of residuals from the line of cognitive equivalence may change conclusions concerning the cognitive abilities of extant and extinct primate species, including hominins.

scholarly journals Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1473
Author(s):  
Jun Zhao ◽  
Kang Wang ◽  
Shuaibin Wang ◽  
Zike Wang ◽  
Zhaohui Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
High Volume ◽  
Sem Analysis ◽  
Geopolymer Concrete ◽  
Ordinary Concrete ◽  
Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

Climate change and security in Canada

2021 ◽  
Vol 76 (2) ◽  
pp. 183-203
Author(s):  
Wilfrid Greaves
Keyword(s):  
Climate Change ◽  
National Security ◽  
Human Security ◽  
Climate Change Impacts ◽  
Future Research ◽  
National Interests ◽  
Domestic Conflict ◽  
The Third ◽  
Current State ◽  
Humanitarian Crises

This article examines the implications of human-caused climate change for security in Canada. The first section outlines the current state of climate change, the second discusses climate change impacts on human security in Canada, and the third outlines four other areas of Canada’s national interests threatened by climate change: economic threats; Arctic threats; humanitarian crises at home and abroad; and the threat of domestic conflict. In the conclusion, I argue that climate change has clearly not been successfully “securitized” in Canada, despite the material threats it poses to human and national security, and outline directions for future research.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Microstructure Evolution and Mechanical Properties of an Al-Cu-Mg Alloy at Elevated Temperature

2014 ◽  
Vol 1004-1005 ◽  
pp. 148-153
Author(s):  
Min Hao ◽  
Ji Gang Ru ◽  
Ming Liu ◽  
Kun Zhang ◽  
Liang Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Shear Fracture ◽  
S Phase ◽  
Mg Alloy ◽  
Transmission Electron ◽  
Fracture Features ◽  
Scanning Electron

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to study the microstructure and mechanical behavior of an Al-Cu-Mg alloy after tensile test at 125°C, 150°C, 175°C and 200 °C, respectively. The yield strength and ultimate tensile strength decreased with the increase of temperature, while the elongation increased firstly and then decreased. The S and S′ precipitate after tension at elevated temperatures. When the temperature was higher than 175°C, the precipitate coarsens rapidly. The alloys displayed a shear fracture features at elevated temperature. The larger S′ and S phase coarsened and dropped which forming crack in the grain boundaries and precipitate interfaces, resulting in the decrease of the elongation of the alloy.

Study on the Formability of Aluminium Alloy Sheets at Room and Elevated Temperatures

2016 ◽  
Vol 877 ◽  
pp. 393-399
Author(s):  
Jia Zhou ◽  
Jun Ping Zhang ◽  
Ming Tu Ma
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Elevated Temperature ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Elevated Temperatures ◽  
Hot Stamping ◽  
Natural Aging ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet

This paper presents the main achievements of a research project aimed at investigating the applicability of the hot stamping technology to non heat treatable aluminium alloys of the 5052 H32 and heat treatable aluminium alloys of the 6016 T4P after six months natural aging. The formability and mechanical properties of 5052 H32 and 6016 T4P aluminum alloy sheets after six months natural aging under different temperature conditions were studied, the processing characteristics and potential of the two aluminium alloy at room and elevated temperature were investigated. The results indicated that the 6016 aluminum alloy sheet exhibit better mechanical properties at room temperature. 5052 H32 aluminum alloy sheet shows better formability at elevated temperature, and it has higher potential to increase formability by raising the temperature.

Experimental Investigation of Ti-6Al-4V with a Biaxial Tensile Test Setup at Elevated Temperature

2014 ◽  
Vol 622-623 ◽  
pp. 273-278 ◽  
Author(s):  
Marion Merklein ◽  
Sebastian Suttner ◽  
Adam Schaub
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Plastic Yielding ◽  
Characterization Methods ◽  
Specific Strength ◽  
Biaxial Tensile ◽  
Stress States

The requirement for products to reduce weight while maintaining strength is a major challenge to the development of new advanced materials. Especially in the field of human medicine or aviation and aeronautics new materials are needed to satisfy increasing demands. Therefore the titanium alloy Ti-6Al-4V with its high specific strength and an outstanding corrosion resistance is used for high and reliable performance in sheet metal forming processes as well as in medical applications. Due to a meaningful and accurate numerical process design and to improve the prediction accuracy of the numerical model, advanced material characterization methods are required. To expand the formability and to skillfully use the advantage of Ti-6Al-4V, forming processes are performed at elevated temperatures. Thus the investigation of plastic yielding at different stress states and at an elevated temperature of 400°C is presented in this paper. For this reason biaxial tensile tests with a cruciform shaped specimen are realized at 400°C in addition to uniaxial tensile tests. Moreover the beginning of plastic yielding is analyzed in the first quadrant of the stress space with regard to complex material modeling.

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