scholarly journals Impacts of Low Temperatures on Wolbachia (Rickettsiales: Rickettsiaceae)-Infected Aedes aegypti (Diptera: Culicidae)

2020 ◽  
Vol 57 (5) ◽  
pp. 1567-1574 ◽  
Author(s):  
Meng-Jia Lau ◽  
Perran A Ross ◽  
Nancy M Endersby-Harshman ◽  
Ary A Hoffmann
Keyword(s):  
Life History ◽  
Low Temperature ◽  
Aedes Aegypti ◽  
Disease Transmission ◽  
Low Temperatures ◽  
Temperature Effects ◽  
Life Stage ◽  
Temperature Cycles ◽  
The Impact ◽  
Wolbachia Density

Abstract In recent decades, the occurrence and distribution of arboviral diseases transmitted by Aedes aegypti mosquitoes has increased. In a new control strategy, populations of mosquitoes infected with Wolbachia are being released to replace existing populations and suppress arboviral disease transmission. The success of this strategy can be affected by high temperature exposure, but the impact of low temperatures on Wolbachia-infected Ae. aegypti is unclear, even though low temperatures restrict the abundance and distribution of this species. In this study, we considered low temperature cycles relevant to the spring season that are close to the distribution limits of Ae. aegypti, and tested the effects of these temperature cycles on Ae. aegypti, Wolbachia strains wMel and wAlbB, and Wolbachia phage WO. Low temperatures influenced Ae. aegypti life-history traits, including pupation, adult eclosion, and fertility. The Wolbachia-infected mosquitoes, especially wAlbB, performed better than uninfected mosquitoes. Temperature shift experiments revealed that low temperature effects on life history and Wolbachia density depended on the life stage of exposure. Wolbachia density was suppressed at low temperatures but densities recovered with adult age. In wMel Wolbachia there were no low temperature effects specific to Wolbachia phage WO. The findings suggest that Wolbachia-infected Ae. aegypti are not adversely affected by low temperatures, indicating that the Wolbachia replacement strategy is suitable for areas experiencing cool temperatures seasonally.

An eco-physiological model of the impact of temperature on Aedes aegypti life history traits

2012 ◽  
Vol 58 (12) ◽  
pp. 1597-1608 ◽  
Author(s):  
Harish Padmanabha ◽  
Fabio Correa ◽  
Mathieu Legros ◽  
H. Fredrick Nijhout ◽  
Cynthia Lord ◽  
...  
Keyword(s):  
Life History ◽  
Aedes Aegypti ◽  
Life History Traits ◽  
Physiological Model ◽  
The Impact

Study on Shortcut and Simultaneous Nitrification and Denitrification under Low Temperatures

2012 ◽  
Vol 610-613 ◽  
pp. 2047-2052
Author(s):  
Jin Xiang Fu ◽  
Xin Chun Zhang ◽  
Peng Fei Yu
Keyword(s):  
Low Temperature ◽  
Adverse Effects ◽  
Treatment Effect ◽  
Low Temperatures ◽  
Accumulation Rate ◽  
Heating Process ◽  
Nitrite Accumulation ◽  
Simultaneous Nitrification And Denitrification ◽  
Nitrification And Denitrification ◽  
The Impact

This paper studies the impact of cooling and warming on shortcut and simultaneous nitrification and denitrification under low temperature. The results show that the effluent concentration of NH4+-N and TN gradually increased, the nitrite accumulation rate decreased when DO was 0.3~0.5 mg•L-1, sludge return ratio was 300%, PH was 7.5~8.5, temperature dropped from 15 °Cto 8°C. From 10°C to 8°C in cooling, the average nitrite accumulation rate was 58.17% in A (HRT=24h) reactor. During the system heating process, treatment effect of the system gradually changed for the better. From 12°C to 15°Cin heating process, the average nitrite accumulation rate was 74.39% in B (HRT=48h) reactor. The system treatment effect in B reactor was better by contrasting A and B reactors, therefore, we can increase HRT to reduce the adverse effects on the system due to the temperature decreases to enhance TN removal effect of system.

scholarly journals Cross-Generational Effects of Heat Stress on Fitness and Wolbachia Density in Aedes aegypti Mosquitoes

2019 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Isabelle Jia-Hui Foo ◽  
Ary A. Hoffmann ◽  
Perran A. Ross
Keyword(s):  
Heat Stress ◽  
Aedes Aegypti ◽  
Disease Transmission ◽  
Wing Length ◽  
Wolbachia Infection ◽  
Female Offspring ◽  
Starvation Tolerance ◽  
Generational Effects ◽  
Infection Types ◽  
Wolbachia Density

Aedes aegypti mosquitoes infected with Wolbachia symbionts are now being released into the field to control the spread of pathogenic human arboviruses. Wolbachia can spread throughout vector populations by inducing cytoplasmic incompatibility and can reduce disease transmission by interfering with virus replication. The success of this strategy depends on the effects of Wolbachia on mosquito fitness and the stability of Wolbachia infections across generations. Wolbachia infections are vulnerable to heat stress, and sustained periods of hot weather in the field may influence their utility as disease control agents, particularly if temperature effects persist across generations. To investigate the cross-generational effects of heat stress on Wolbachia density and mosquito fitness, we subjected Ae. aegypti with two different Wolbachia infection types (wMel, wAlbB) and uninfected controls to cyclical heat stress during larval development over two generations. We then tested adult starvation tolerance and wing length as measures of fitness and measured the density of wMel in adults. Both heat stress and Wolbachia infection reduced adult starvation tolerance. wMel Wolbachia density in female offspring was lower when mothers experienced heat stress, but male Wolbachia density did not depend on the rearing temperature of the previous generation. We also found cross-generational effects of heat stress on female starvation tolerance, but there was no cross-generational effect on wing length. Fitness costs of Wolbachia infections and cross-generational effects of heat stress on Wolbachia density may reduce the ability of Wolbachia to invade populations and control arbovirus transmission under specific environmental conditions.

The impact of low temperatures in controlling the geographical distribution of plants

1990 ◽  
Vol 326 (1237) ◽  
pp. 585-593 ◽  
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
Low Temperatures ◽  
Marked Change ◽  
Tilia Cordata ◽  
Natural Range ◽  
Distribution Limits ◽  
The Impact ◽  
Temperature Responses

The distribution limits of three species, in the British Isles are discussed. For Verbena officinalis and Tilia cordata low temperatures are shown to influence distribution, by limiting the capacity either to flower or to fertilize ovules, respectively. In the case of Umbilicus rupestris , a long-term transplant population beyond the natural geographical limit of the species has evolved new low-temperature responses of seed germination and winter survival. The effect is a marked change of phenology, compared with populations of the species within its natural range, which enhances the capacity of the population to survive in a colder environment.

scholarly journals Effect of protein and carbohydrate feed concentrations on the growth and composition of black soldier fly (Hermetia illucens) larvae

2019 ◽  
Vol 5 (3) ◽  
pp. 193-199 ◽  
Author(s):  
J.J.A. Beniers ◽  
R.I. Graham
Keyword(s):  
Life History ◽  
Dietary Protein ◽  
Life Stage ◽  
Dry Weight ◽  
Nutritional Composition ◽  
Dietary Carbohydrate ◽  
Black Soldier Fly ◽  
Hermetia Illucens ◽  
Wide Range ◽  
The Impact

Black soldier flies (Hermetia illucens) can be used for a wide range of applications, from screening their anti-microbial properties, entomophagy through to waste management. Although the use of black soldier flies for these purposes has been widely studied, mass-rearing black soldier flies is still in the preliminary phase. This study focussed on the nutritional composition of black soldier fly larvae over the course of their life history, and the impact of manipulating dietary protein and carbohydrate on the growth and composition (protein and fat) of the larvae. Larvae were collected every 24 h over the course of this life-stage to test for differences in composition. To test the effect of dietary protein and carbohydrate differences, larvae were fed 25 diets with varying concentrations of protein and carbohydrates. Overall, the composition of larvae changed very little over their life history, with the higher concentration of protein mostly observed in the earlier instars of the larvae. The pre-pupal stage reduced the fresh and dry weight of the larvae, whereas the ash concentration was very stable throughout their life history. Both dietary protein and dietary carbohydrate had a significant effect on the fresh and dry weight of the larvae, but dietary protein was a stronger indicator of larval fresh and dry weight than dietary carbohydrate. Larval composition was also influenced by the feed-type, with heavier larvae producing significantly more fat than the lighter ones.

scholarly journals Retrospective Network Imputation from Life History Data: The Impact of Designs

2020 ◽  
Vol 50 (1) ◽  
pp. 131-167
Author(s):  
Yue Yu ◽  
Emily J. Smith ◽  
Carter T. Butts
Keyword(s):  
Life History ◽  
Disease Transmission ◽  
Survey Design ◽  
Ground Truth ◽  
Design Parameters ◽  
Network Information ◽  
The Past ◽  
Large Populations ◽  
Partnership Network ◽  
The Impact

Retrospective life history designs are among the few practical approaches for collecting longitudinal network information from large populations, particularly in the context of relationships like sexual partnerships that cannot be measured via digital traces or documentary evidence. While all such designs afford the ability to “peer into the past” vis-à-vis the point of data collection, little is known about the impact of the specific design parameters on the time horizon over which such information is useful. In this article, we investigate the effect of two different survey designs on retrospective network imputation: (1) intervalN, where subjects are asked to provide information on all partners within the past [Formula: see text] time units; and (2) lastK, where subjects are asked to provide information about their [Formula: see text] most recent partners. We simulate a “ground truth” sexual partnership network using a published model of Krivitsky (2012), and we then sample this data using the two retrospective designs under various choices of [Formula: see text] and [Formula: see text]. We examine the accumulation of missingness as a function of time prior to interview, and we investigate the impact of this missingness on model-based imputation of the state of the network at prior time points via conditional ERGM prediction. We quantitatively show that—even setting aside problems of alter identification and informant accuracy—choice of survey design and parameters used can drastically change the amount of missingness in the dataset. These differences in missingness have a large impact on the quality of retrospective parameter estimation and network imputation, including important effects on properties related to disease transmission.

scholarly journals Optimisation of Direct Battery Thermal Management for EVs Operating in Low-Temperature Climates

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5980 ◽  
Author(s):  
James Jeffs ◽  
Truong Quang Dinh ◽  
Widanalage Dhammika Widanage ◽  
Andrew McGordon ◽  
Alessandro Picarelli
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Thermal Management ◽  
Electric Vehicles ◽  
Low Temperatures ◽  
Air Conditioning ◽  
Lithium Ion ◽  
Battery Thermal Management ◽  
Temperature Performance ◽  
The Impact

Electric vehicles (EVs) experience a range reduction at low temperatures caused by the impact of cabin heating and a reduction in lithium ion performance. Heat pump equipped vehicles have been shown to reduce heating ventilation and air conditioning (HVAC) consumption and improve low ambient temperature range. Heating the electric battery, to improve its low temperature performance, leads to a reduction in heat availability for the cabin. In this paper, dynamic programming is used to find the optimal battery heating trajectory which can optimise the vehicle’s control for either cabin comfort or battery performance and, therefore, range. Using the strategy proposed in this research, a 6.2% increase in range compared to no battery heating and 5.5% increase in thermal comfort compared to full battery heating was achieved at an ambient temperature at −7 °C.

scholarly journals Low-temperature effects on docosahexaenoic acid biosynthesis in Schizochytrium sp. TIO01 and its proposed underlying mechanism

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Fan Hu ◽  
April L. Clevenger ◽  
Peng Zheng ◽  
Qiongye Huang ◽  
Zhaokai Wang
Keyword(s):  
Fatty Acid ◽  
Low Temperature ◽  
Fatty Acid Synthesis ◽  
Low Temperatures ◽  
Temperature Effects ◽  
Fatty Acid Biosynthesis ◽  
Underlying Mechanism ◽  
Acid Synthesis ◽  
Acid Biosynthesis ◽  
Fas Pathway

Abstract Background Schizochytrium species are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids (PUFAs) in many species. This study investigates low-temperature effects on DHA biosynthesis in Schizochytrium sp. TIO01 and its underlying mechanism. Results The Schizochytrium fatty acid biosynthesis pathway was evaluated based on de novo genome assembly (contig N50 = 2.86 Mb) and iTRAQ-based protein identification. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are, respectively, responsible for DHA and saturated fatty acid synthesis in Schizochytrium. Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium, increasing the DHA content from 43 to 65% of total fatty acids. However, the expression levels of PKS pathway genes were not significantly regulated as the DHA content increased. Further, gene expression analysis showed that pathways related to the production of substrates (acetyl-CoA and NADPH) for fatty acid synthesis (the branched-chain amino acid degradation pathway and the pentose phosphate pathway) and genes related to saturated fatty acid biosynthesis (the FAS pathway genes and malic enzyme) were, respectively, upregulated and downregulated. These results indicate that low temperatures increase the DHA content by likely promoting the entry of relatively large amounts of substrates into the PKS pathway. Conclusions In this study, we provide genomic, proteomic, and transcriptomic evidence for the fatty acid synthesis pathway in Schizochytrium and propose a mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium. The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for investigating the regulation of polyunsaturated fatty acid biosynthesis and the evolutionary characteristics of Thraustochytriidae species.

scholarly journals Investigation on the Effect of Low Temperature on Impact Properties of Ti-6Al-4V Titanium Alloy

2020 ◽  
Author(s):  
wei zhao ◽  
WenJia Su ◽  
Liang Li ◽  
Ding Fang ◽  
Ni Chen
Keyword(s):  
Titanium Alloy ◽  
Low Temperature ◽  
Low Temperatures ◽  
Research Result ◽  
Cutting Mechanism ◽  
Impact Properties ◽  
Fiber Area ◽  
The Impact ◽  
Cryogenic Cutting ◽  
Radiation Area

Abstract Cryogenic cutting is becoming an attractive machining method for difficult-to-cut materials. However, it’s very difficult to analyze directly their cutting mechanism at low temperature. In order to better understand the various physical phenomena in the cryogenic cutting of titanium alloy, the Charpy impact test of Ti-6Al-4V titanium alloy at low temperatures (as low as -196 °C) was undertaken in this work. The Charpy absorbed energy of Ti-6Al-4V titanium alloy at low temperatures was investigated firstly. Then, by observing the microscopic and macroscopic morphology of the fracture, the impact properties and fracture modes of Ti-6Al-4V titanium alloy at low temperatures were analyzed. It was found that the impact toughness of Ti-6Al-4V titanium alloy reduces when the temperature decreases from 20 °C to -196 °C, and the fracture appears a tendency to become brittle. Meanwhile, three kinds of areas, i.e. shear lip area, fiber area, and radiation area, were found on the fracture morphology at each temperature. Those areas correspond to the shear fracture zone, crack initiation zone, and crack extension zone, respectively. With the decrease in temperature, the proportion of fiber area decreases, and the radiation area appears and increases gradually. However, fiber areas were still observed on the macroscopic morphology of the fracture under − 196 °C, which suggests that Ti-6Al-4V titanium alloy still has the ability to deform plastically at such low temperatures. The research result in this work provide a fundamental support for analyzing the cutting mechanism of Ti-6Al-4V titanium alloy at low temperatures.

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