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Journal of Thermal Biology May 2018To investigate inter-individual variance in adaptive responses to heat acclimation (HA).
AIM
To investigate inter-individual variance in adaptive responses to heat acclimation (HA).
METHODS
17 males (VO=58.8(8.4) mL·kg·min) undertook 10-days (exercise + heat-stress [40 °C, 50%RH]) HA. Adaptation was assessed by heat stress tests (HST; 60-minutes cycling, 35% peak power output) pre- and post-HA.
RESULTS
Inter-individual variability was evident in adaptive responses e.g. mean(range) reduction in end-exercise T= -0.70(-0.20 to -1.32)°C, but, in the main, the variance in adaptation was unrelated across indices (thermal, sudomotor, cardiovascular, haematological), indicating independence between adaptation indices. Variance in adaptive responses was not correlated with aerobic capacity, history of previous HA, or the accrued thermal-dose. Some responses to the initial HST were related to the subsequent adaptations e.g. ∆T̅ during the initial HST and the reduction in the within HST ΔT after HA (r = -0.676), but responses to the initial HST may also have been influenced by HST design e.g. ΔT correlated with metabolic heat production (r = 0.609). Metabolic heat production also correlated with the reduction in the within HST ΔT after HA (r = -0.514).
SUMMARY
HA indices are mainly independent; 'low', or 'high', responders on one index do not necessarily demonstrate similar response across other indices. Variance in HA responses was not related to aerobic capacity, previous HA, or thermal-dose. Thermo-physiological responses to a HST might identify individuals who will benefit from HA. However, some initial responses are influenced by HST design, which may also affect the scope for demonstrating adaption.
CONCLUSION
Variance in the HA response remains largely unaccounted for and future studies should identify factors contributing to this variance.
Topics: Adult; Body Temperature Regulation; Exercise Test; Humans; Male; Thermotolerance; Young Adult
PubMed: 29801640
DOI: 10.1016/j.jtherbio.2018.03.002 -
Journal of Science and Medicine in Sport Sep 2000Exposure to altitude results in a reduction in partial pressure of oxygen in the arterial blood and a reduction in oxygen content. In an attempt to maintain aerobic... (Review)
Review
Exposure to altitude results in a reduction in partial pressure of oxygen in the arterial blood and a reduction in oxygen content. In an attempt to maintain aerobic metabolism during increased effort, a series of acclimatization responses occur. Among the most conspicuous of these responses is an increase in hemoglobin (Hb) concentration. The increase in Hb has been construed as the fundamental adaptation enabling increases in aerobic power and performance to occur on return to sea-level. However, the use of altitude to boost training adaptations and improve elite sea-level performance, although tantalizing, is largely unproven. The reasons appear to be many, ranging from the poor experimental designs employed, to the numerous strategies designed to manipulate the altitude experience and the large inter-individual differences in response patterns. However, other factors may also be important. Acclimatization has also been shown to induce alteration in selected properties of the muscle cell, some of which may be counterproductive. The processes involved in cation cycling, as an example, appear to be down-regulated. Changes in these processes could impair certain types of performance.
Topics: Acclimatization; Altitude; Humans; Physical Education and Training
PubMed: 11101269
DOI: 10.1016/s1440-2440(00)80039-0 -
Human Factors Jun 2018We investigated adapting the interaction style of intelligent tutoring system (ITS) feedback based on human-automation etiquette strategies.
OBJECTIVE
We investigated adapting the interaction style of intelligent tutoring system (ITS) feedback based on human-automation etiquette strategies.
BACKGROUND
Most ITSs adapt the content difficulty level, adapt the feedback timing, or provide extra content when they detect cognitive or affective decrements. Our previous work demonstrated that changing the interaction style via different feedback etiquette strategies has differential effects on students' motivation, confidence, satisfaction, and performance. The best etiquette strategy was also determined by user frustration.
METHOD
Based on these findings, a rule set was developed that systemically selected the proper etiquette strategy to address one of four learning factors (motivation, confidence, satisfaction, and performance) under two different levels of user frustration. We explored whether etiquette strategy selection based on this rule set (systematic) or random changes in etiquette strategy for a given level of frustration affected the four learning factors. Participants solved mathematics problems under different frustration conditions with feedback that adapted dynamic changes in etiquette strategies either systematically or randomly.
RESULTS
The results demonstrated that feedback with etiquette strategies chosen systematically via the rule set could selectively target and improve motivation, confidence, satisfaction, and performance more than changing etiquette strategies randomly. The systematic adaptation was effective no matter the level of frustration for the participant.
CONCLUSION
If computer tutors can vary the interaction style to effectively mitigate negative emotions, then ITS designers would have one more mechanism in which to design affect-aware adaptations that provide the proper responses in situations where human emotions affect the ability to learn.
Topics: Adult; Affect; Automation; Educational Technology; Feedback; Female; Humans; Male; Man-Machine Systems; User-Computer Interface; Young Adult
PubMed: 29589967
DOI: 10.1177/0018720818765266 -
Global Change Biology Jun 2020Climate change is increasingly impacting marine protected areas (MPAs) and MPA networks, yet adaptation strategies are rarely incorporated into MPA design and management... (Review)
Review
Climate change is increasingly impacting marine protected areas (MPAs) and MPA networks, yet adaptation strategies are rarely incorporated into MPA design and management plans according to the primary scientific literature. Here we review the state of knowledge for adapting existing and future MPAs to climate change and synthesize case studies (n = 27) of how marine conservation planning can respond to shifting environmental conditions. First, we derive a generalized conservation planning framework based on five published frameworks that incorporate climate change adaptation to inform MPA design. We then summarize examples from the scientific literature to assess how conservation goals were defined, vulnerability assessments performed and adaptation strategies incorporated into the design and management of existing or new MPAs. Our analysis revealed that 82% of real-world examples of climate change adaptation in MPA planning derive from tropical reefs, highlighting the need for research in other ecosystems and habitat types. We found contrasting recommendations for adaptation strategies at the planning stage, either focusing only on climate refugia, or aiming for representative protection of areas encompassing the full range of expected climate change impacts. Recommendations for MPA management were more unified and focused on adaptative management approaches. Lastly, we evaluate common barriers to adopting climate change adaptation strategies based on reviewing studies which conducted interviews with MPA managers and other conservation practitioners. This highlights a lack of scientific studies evaluating different adaptation strategies and shortcomings in current governance structures as two major barriers, and we discuss how these could be overcome. Our review provides a comprehensive synthesis of planning frameworks, case studies, adaptation strategies and management actions which can inform a more coordinated global effort to adapt existing and future MPA networks to continued climate change.
Topics: Acclimatization; Biodiversity; Climate Change; Conservation of Natural Resources; Ecosystem; Refugium
PubMed: 32222010
DOI: 10.1111/gcb.15094 -
Scientific Reports Aug 2021All homoiothermic organisms are capable of maintaining a stable body temperature using various negative feedback mechanisms. However, current models cannot...
All homoiothermic organisms are capable of maintaining a stable body temperature using various negative feedback mechanisms. However, current models cannot satisfactorily describe the thermal adaptation of homoiothermic living systems in a physiologically meaningful way. Previously, we introduced stress entropic load, a novel variable designed to quantify adaptation costs, i.e. the stress of the organism, using a thermodynamic approach. In this study, we use stress entropic load as a starting point for the construction of a novel dynamical model of human thermoregulation. This model exhibits bi-stable mechanisms, a physiologically plausible features which has thus far not been demonstrated using a mathematical model. This finding allows us to predict critical points at which a living system, in this case a human body, may proceed towards two stabilities, only one of which is compatible with being alive. In the future, this may allow us to quantify not only the direction but rather the extent of therapeutic intervention in critical care patients.
Topics: Acclimatization; Adaptation, Physiological; Animals; Body Temperature; Body Temperature Regulation; Homeostasis; Humans; Male; Models, Biological; Models, Theoretical; Thermodynamics
PubMed: 34462454
DOI: 10.1038/s41598-021-96280-0 -
The Science of the Total Environment Dec 2020Demographic trends will play a role in determining the magnitude of climate disruption and the ability of societies to adapt to it. Yet policy makers largely ignore the... (Review)
Review
Demographic trends will play a role in determining the magnitude of climate disruption and the ability of societies to adapt to it. Yet policy makers largely ignore the potential of fertility changes and population growth when designing policies to limit climate disruption and lessen its impacts. Here we argue that rights-based policy interventions could decrease fertility rates to levels consistent with low population pathways. We review country and global level studies that explore the effects of low population pathways on climate change mitigation and adaptation. We then provide rights-based policy recommendations, such as the expansion of voluntary family planning programs that incorporate elements from successful past programs, and highlight current research gaps. In concert with policies that end fossil fuel use and incentivize sustainable consumption, humane policies that slow population growth should be part of a multifaceted climate response. These policies require attention from scientists, policy analysts and politicians.
Topics: Acclimatization; Birth Rate; Climate Change; Fertility; Population Growth
PubMed: 33113687
DOI: 10.1016/j.scitotenv.2020.141346 -
Current Opinion in Plant Biology Aug 2020In the context of the global challenge of climate change, mitigation strategies are needed to adapt crops to novel environments. The main goal to address this is an... (Review)
Review
In the context of the global challenge of climate change, mitigation strategies are needed to adapt crops to novel environments. The main goal to address this is an understanding of the genetic basis of crop adaptation to different agro-ecological conditions. The movement of crops during the Colombian Exchange that started with the travels of Columbus in 1492 is an example of rapid adaptation to novel environments. Many diversification-related traits have been characterised in multiple crop species, and association-mapping analyses have identified loci involved in these. Here, we present an overview of current knowledge regarding the molecular basis related to the complex patterns of crop adaptation and dissemination, particularly outside their centres of origin. Investigation of the genomic basis of crop expansion offers a powerful contribution to the development of tools to identify and exploit valuable genetic diversity and to improve and design novel resilient crop varieties.
Topics: Acclimatization; Adaptation, Physiological; Climate Change; Crops, Agricultural; Phenotype
PubMed: 32057695
DOI: 10.1016/j.pbi.2019.12.011 -
Advances in Experimental Medicine and... 2018Under low nonfreezing temperature conditions, plants from temperate climates undergo physiological and biochemical adjustments that increase their tolerance to freezing... (Review)
Review
Under low nonfreezing temperature conditions, plants from temperate climates undergo physiological and biochemical adjustments that increase their tolerance to freezing temperatures. This response, termed cold acclimation, is largely regulated by changes in gene expression. Molecular and genetic studies have identified a small family of transcription factors, called C-repeat binding factors (CBFs), as key regulators of the transcriptomic rearrangement that leads to cold acclimation. The function of these proteins is tightly controlled, and an inadequate supply of CBF activity may be detrimental to the plant. Accumulated evidence has revealed an extremely intricate network of positive and negative regulators of cold acclimation that coalesce at the level of CBF promoters constituting a central hub where multiple internal and external signals are integrated. Moreover, CBF expression is also controlled at posttranscriptional and posttranslational levels further refining CBF regulation. Recently, natural variation studies in Arabidopsis have demonstrated that mutations resulting in changes in CBF expression have an adaptive value for wild populations. Intriguingly, CBF genes are also present in plant species that do not cold acclimate, which suggest that they may also have additional functions. For instance, CBFs are required for some cold-related abiotic stress responses. In addition, their involvement in plant development deserves further study. Although more studies are necessary to fully harness CBF biotechnological potential, these transcription factors are meant to be key for a rational design of crops with enhanced tolerance to abiotic stress.
Topics: Acclimatization; Arabidopsis; Arabidopsis Proteins; Cold Temperature; Cold-Shock Response; Core Binding Factors; Gene Expression Regulation, Plant; Gene Regulatory Networks; Genes, Plant; Genotype; Phenotype; Promoter Regions, Genetic; Signal Transduction
PubMed: 30288701
DOI: 10.1007/978-981-13-1244-1_1 -
Sports Medicine (Auckland, N.Z.) 2001Recently, endurance athletes have used several novel approaches and modalities for altitude training including: (i) normobaric hypoxia via nitrogen dilution (hypoxic... (Review)
Review
Recently, endurance athletes have used several novel approaches and modalities for altitude training including: (i) normobaric hypoxia via nitrogen dilution (hypoxic apartment); (ii) supplemental oxygen; (iii) hypoxic sleeping devices; and (iv) intermittent hypoxic exposure (IHE). A normobaric hypoxic apartment simulates an altitude environment equivalent to approximately 2000 to 3000m (6560 to 9840ft). Athletes who use a hypoxic apartment typically 'live and sleep high' in the hypoxic apartment for 8 to 18 hours a day, but complete their training at sea level, or approximate sea level conditions. Several studies suggest that using a hypoxic apartment in this manner produces beneficial changes in serum erythropoietin (EPO) levels, reticulocyte count and red blood cell (RBC) mass, which in turn may lead to improvements in postaltitude endurance performance. However, other studies failed to demonstrate significant changes in haematological indices as a result of using a hypoxic apartment. These discrepancies may be caused by differences in methodology, the hypoxic stimulus that athletes were exposed to and/or the training status of the athletes. Supplemental oxygen is used to simulate either normoxic (sea level) or hyperoxic conditions during high-intensity workouts at altitude. This method is a modification of the 'high-low' strategy, since athletes live in a natural terrestrial altitude environment but train at 'sea level' with the aid of supplemental oxygen. Limited data regarding the efficacy of hyperoxic training suggests that high-intensity workouts at moderate altitude (1860m/6100ft) and endurance perfor- mance at sea level may be enhanced when supplemental oxygen training is utilised at altitude over a duration of several weeks. Hypoxic sleeping devices include the Colorado Altitude Training (CAT) Hatch (hypobaric chamber) and Hypoxico Tent System (normobaric hypoxic system), both of which are designed to allow athletes to sleep high and train low. These devices simulate altitudes up to approximately 4575 m/15006 ft and 4270 m/14005 ft, respectively. Currently, no studies have been published on the efficacy of these devices on RBC production, maximal oxygen uptake and/or performance in elite athletes. IHE is based on the assumption that brief exposures to hypoxia (1.5 to 2.0 hours) are sufficient to stimulate the release of EPO, and ultimately bring about an increase in RBC concentration. Athletes typically use IHE while at rest, or in conjunction with a training session. Data regarding the effect of IHE on haematological indices and athletic performance are minimal and inconclusive.
Topics: Acclimatization; Altitude; Erythrocytes; Erythropoietin; Female; Humans; Hypoxia; Male; Nitrogen; Oxygen; Oxygen Consumption; Physical Fitness; Reticulocyte Count; Sports
PubMed: 11310547
DOI: 10.2165/00007256-200131040-00002 -
Cellular and Molecular Life Sciences :... Nov 2014The innate immune system recognizes deviation from homeostasis caused by infectious or non-infectious assaults. The threshold for its activation seems to be established... (Review)
Review
The innate immune system recognizes deviation from homeostasis caused by infectious or non-infectious assaults. The threshold for its activation seems to be established by a calibration process that includes sensing of microbial molecular patterns from commensal bacteria and of endogenous signals. It is becoming increasingly clear that adaptive features, a hallmark of the adaptive immune system, can also be identified in the innate immune system. Such adaptations can result in the manifestation of a primed state of immune and tissue cells with a decreased activation threshold. This keeps the system poised to react quickly. Moreover, the fact that the innate immune system recognizes a wide variety of danger signals via pattern recognition receptors that often activate the same signaling pathways allows for heterologous innate immune stimulation. This implies that, for example, the innate immune response to an infection can be modified by co-infections or other innate stimuli. This "design feature" of the innate immune system has many implications for our understanding of individual susceptibility to diseases or responsiveness to therapies and vaccinations. In this article, adaptive features of the innate immune system as well as heterologous innate immunity and their implications are discussed.
Topics: Acclimatization; Adaptation, Physiological; Animals; Calibration; Dendritic Cells; Dermatitis, Contact; Disease Susceptibility; Homeostasis; Humans; Hypersensitivity; Immune System; Immunity, Innate; Receptors, Pattern Recognition; Signal Transduction; Toll-Like Receptors
PubMed: 24997561
DOI: 10.1007/s00018-014-1676-2