Temperature variability
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Úvod: Počítačem asistované stanovení termického prahu je psychofyzikální semikvantitativní metoda testování funkce tenkých nervových vláken. V současnosti není k dispozici dostatek údajů o vlii^,, fyziologických proměnných na hodnotu prahu a na intraindividuální variabilitu testu. Metodika: Termický práh pro teplo a chlad byl stanoven ve skupině 50 zdravých dobrovolníků (25 žen a 25 mužů). a to ve dvou lokalizacích (thenar LHK a dorzum PDK). Každý jedinec byl vyšetřen třemi různými algoritmy: dvěma metodami reakčního času (reaction time inclusive - nerandomizovaná a randomizovaná varianta metody Limity) a jednou metodou konstantního stimulu - randomizovaná varianta metody Úrovně). Pro stanovení intraindividuální variability byly u 30 jedinců všechny testy zopakovány v průběhu jednoho týdne a byl stanoven horní normální limit pro fyziologickou intraindividuální změnu každého testu. Výsledky: Hodnoty termického prahu pro chlad se významně snižovaly a hodnoty pro teplo naopak zvyšovaly při vyšetření DKK, u mužů a při použití metod reakčního času. Vliv věku na hodnoty termického prahu nebyl statisticky významný. Intraindividuální variabilita hodnot prahu vyjádřená jako medián koeficientů intraindividuální variability se pohybovala mezi 15 a 30 % a nebyla závislá na typu testu, vyšetřované oblasti, věku ani pohlaví. Závěry: Normální limity je nutno stanovit s ohledem na pohlaví, typ algoritmu a lokalizaci termosondy. Intraindividuální variabilita hodnot prahu je přijatelná s ohledem na psychofyzikální charakter testu, srovnatelná s dalšími kvantitativními testy senzitivního čití a není významně ovlivněna typem provedeného testu ani fyziologickými proměnnými.
Computer-assisted thermal threshold testing is a psychophysical semi-quantitative method of testing the function of small nerve fibres. At present, there is not enough data available on the effect of physiological variables on the threshold value and on the intra-individual variability of the test. Methods: Thermal threshold for heat and cold was determined in a group of 50 healthy volunteers (2 males and 25 females) in two localizations (thenar of the left upper extremity and dorsum of the right lower extremity). Each individual was examined with three different algorithms: two reaction time methods (reaction time inclusive - non-randomised and randomised variant of the Limits method) and one constant stimulus method (reaction time exclusive - randomised variant of the Levels method). To determine intra-individual variability, all tests were repeated in 30 individuals within one week and the upper normal limit of physiological intra-individual change of each test was determined. Results: Values of thermal threshold for cold decreased significantly whereas values for heat increased in examination of lower extremities, in men, and when using reaction time. The effect of age on thermal threshold was not significant. Intra-individual variability of threshold values expressed as the median of coefficients of intra-individual variability fell between 15 and 30% and was independent of test type, examined location, age or gender. Conclusions: Normal limits have to be determined with respect to gender, algorithm type and localization of the thermal element. Intra-individual variability of threshold values is acceptable, considering the psychophysical character of the test, is comparable to other quantitative tests of sensory perception and is not significantly influenced by test type or by physiological variables.
- MeSH
- algoritmy MeSH
- diferenční práh MeSH
- dospělí MeSH
- finanční podpora výzkumu jako téma MeSH
- fyzikální stimulace MeSH
- lidé středního věku MeSH
- lidé MeSH
- nervová vlákna fyziologie MeSH
- nízká teplota MeSH
- reakční čas MeSH
- senioři MeSH
- teplota MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- přehledy MeSH
- srovnávací studie MeSH
- MeSH
- cirkadiánní rytmus MeSH
- hladovění MeSH
- lidé MeSH
- srdeční frekvence fyziologie MeSH
- tělesná teplota fyziologie MeSH
- tropické klima MeSH
- venkovské obyvatelstvo MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Senegal MeSH
Whereas temporal variability of plant phenology in response to climate change has already been well studied, the spatial variability of phenology is not well understood. Given that phenological shifts may affect biotic interactions, there is a need to investigate how the variability in environmental factors relates to the spatial variability in herbaceous species' phenology by at the same time considering their functional traits to predict their general and species-specific responses to future climate change. In this project, we analysed phenology records of 148 herbaceous species, which were observed for a single year by the PhenObs network in 15 botanical gardens. For each species, we characterised the spatial variability in six different phenological stages across gardens. We used boosted regression trees to link these variabilities in phenology to the variability in environmental parameters (temperature, latitude and local habitat conditions) as well as species traits (seed mass, vegetative height, specific leaf area and temporal niche) hypothesised to be related to phenology variability. We found that spatial variability in the phenology of herbaceous species was mainly driven by the variability in temperature but also photoperiod was an important driving factor for some phenological stages. In addition, we found that early-flowering and less competitive species characterised by small specific leaf area and vegetative height were more variable in their phenology. Our findings contribute to the field of phenology by showing that besides temperature, photoperiod and functional traits are important to be included when spatial variability of herbaceous species is investigated.
- MeSH
- fenotyp MeSH
- fotoperioda * MeSH
- klimatické změny MeSH
- listy rostlin * fyziologie MeSH
- roční období MeSH
- rostliny MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: Dysglycemia and glycemic variability are associated with poor outcomes in critically ill patients. Targeted temperature management alters blood glucose homeostasis. We investigated the association between blood glucose concentrations and glycemic variability and the neurologic outcomes of patients randomized to targeted temperature management at 33°C or 36°C after cardiac arrest. DESIGN: Post hoc analysis of the multicenter TTM-trial. Primary outcome of this analysis was neurologic outcome after 6 months, referred to as "Cerebral Performance Category." SETTING: Thirty-six sites in Europe and Australia. PATIENTS: All 939 patients with out-of-hospital cardiac arrest of presumed cardiac cause that had been included in the TTM-trial. INTERVENTIONS: Targeted temperature management at 33°C or 36°C. MEASUREMENTS AND MAIN RESULTS: Nonparametric tests as well as multiple logistic regression and mixed effects logistic regression models were used. Median glucose concentrations on hospital admission differed significantly between Cerebral Performance Category outcomes (p < 0.0001). Hyper- and hypoglycemia were associated with poor neurologic outcome (p = 0.001 and p = 0.054). In the multiple logistic regression models, the median glycemic level was an independent predictor of poor Cerebral Performance Category (Cerebral Performance Category, 3-5) with an odds ratio (OR) of 1.13 in the adjusted model (p = 0.008; 95% CI, 1.03-1.24). It was also a predictor in the mixed model, which served as a sensitivity analysis to adjust for the multiple time points. The proportion of hyperglycemia was higher in the 33°C group compared with the 36°C group. CONCLUSION: Higher blood glucose levels at admission and during the first 36 hours, and higher glycemic variability, were associated with poor neurologic outcome and death. More patients in the 33°C treatment arm had hyperglycemia.
- MeSH
- časové faktory MeSH
- Glasgowská stupnice následků MeSH
- hyperglykemie patofyziologie MeSH
- hypoglykemie patofyziologie MeSH
- kardiopulmonální resuscitace metody MeSH
- krevní glukóza fyziologie MeSH
- lidé MeSH
- tělesná teplota * MeSH
- terapeutická hypotermie metody MeSH
- zástava srdce mimo nemocnici mortalita patofyziologie terapie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- randomizované kontrolované studie MeSH
An increase in the global health burden of temperature was projected for 459 locations in 28 countries worldwide under four representative concentration pathway scenarios until 2099. We determined that the amount of temperature increase for each 100 ppm increase in global CO2 concentrations is nearly constant, regardless of climate scenarios. The overall average temperature increase during 2010-2099 is largest in Canada (1.16 °C/100 ppm) and Finland (1.14 °C/100 ppm), while it is smallest in Ireland (0.62 °C/100 ppm) and Argentina (0.63 °C/100 ppm). In addition, for each 1 °C temperature increase, the amount of excess mortality is increased largely in tropical countries such as Vietnam (10.34%p/°C) and the Philippines (8.18%p/°C), while it is decreased in Ireland (-0.92%p/°C) and Australia (-0.32%p/°C). To understand the regional variability in temperature increase and mortality, we performed a regression-based modeling. We observed that the projected temperature increase is highly correlated with daily temperature range at the location and vulnerability to temperature increase is affected by health expenditure, and proportions of obese and elderly population.
- MeSH
- celosvětové zdraví * MeSH
- globální oteplování * MeSH
- lidé MeSH
- mortalita trendy MeSH
- předpověď MeSH
- teplota MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The climatic variability hypothesis was applied to the thermal tolerance of edaphic and cave Collembola occupying contrasting environments. Collembola belonged to four categories - trogloxene, subtroglophile, eutroglophile and troglobiont - with a different degree of affinity to subterranean habitats. Altogether, specimens of 17 species were exposed to a one-hour laboratory survival test. The impact of temperature, species and species-temperature interaction on cold and heat survival was statistically significant. There was a decrease trend in cold and heat tolerance from trogloxenes, over subtroglophiles and eutroglophiles to troglobionts. It was shown that obligate cave species, restricted to climatic-stable cave conditions, retain a functional thermal resistance, i.e. the genetically determined ability to tolerate relatively broader temperature ranges. Our results outlined the direct relationship between the thermal tolerances of species and the size of their geographic distributions. It was also observed that cold resistance of Collembola decreased significantly with increasing species body length, indicating that body size plays an important role in temperature tolerances of arthropods inhabiting soil and subterranean habitats.
- MeSH
- aklimatizace MeSH
- členovci fyziologie MeSH
- jeskyně MeSH
- nízká teplota * MeSH
- podnebí MeSH
- tělesná teplota * MeSH
- velikost těla * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The effect of temperature, light and nutrient composition on morphological traits was determined in seven nostocacean cyanobacteria (Anabaena planctonica, A. sphaerica var. conoidea, A. spiroides, Aphanizomenon gracile, Nostoc sp., Scytonema sp., and Tolypothrix sp.). Their morphological variability was high but only some of the features showed changes reflecting varied growth conditions. The frequency of heterocyst occurrence decreased with increasing nitrogen concentration. Within the range studied, the effect of temperature on heterocyst frequency of Tolypothrix sp. and planktonic Anabaena strains could be fitted by a normal curve with a clear optimum while linear correlation was found in Aphanizomenon gracile. T-and S-type branching was observed in both Scytonema sp. and Tolypothrix sp. strains. T-type branching was found to be markedly dependent on nitrogen concentration. The abundance of necridic cells of Tolypothrix sp. increased linearly with temperature and light intensity. Regularity of trichome coiling of A. spiroides depended on culture medium, suggesting that nutrient composition may be the main controlling factor. In contrast, the effect of the experimental conditions on the dimensions of vegetative cells and heterocysts was weak. Their variability was markedly higher within each experimental treatment than between treatments.
BACKGROUND: Increased mortality risk is associated with short-term temperature variability. However, to our knowledge, there has been no comprehensive assessment of the temperature variability-related mortality burden worldwide. In this study, using data from the MCC Collaborative Research Network, we first explored the association between temperature variability and mortality across 43 countries or regions. Then, to provide a more comprehensive picture of the global burden of mortality associated with temperature variability, global gridded temperature data with a resolution of 0·5° × 0·5° were used to assess the temperature variability-related mortality burden at the global, regional, and national levels. Furthermore, temporal trends in temperature variability-related mortality burden were also explored from 2000-19. METHODS: In this modelling study, we applied a three-stage meta-analytical approach to assess the global temperature variability-related mortality burden at a spatial resolution of 0·5° × 0·5° from 2000-19. Temperature variability was calculated as the SD of the average of the same and previous days' minimum and maximum temperatures. We first obtained location-specific temperature variability related-mortality associations based on a daily time series of 750 locations from the Multi-country Multi-city Collaborative Research Network. We subsequently constructed a multivariable meta-regression model with five predictors to estimate grid-specific temperature variability related-mortality associations across the globe. Finally, percentage excess in mortality and excess mortality rate were calculated to quantify the temperature variability-related mortality burden and to further explore its temporal trend over two decades. FINDINGS: An increasing trend in temperature variability was identified at the global level from 2000 to 2019. Globally, 1 753 392 deaths (95% CI 1 159 901-2 357 718) were associated with temperature variability per year, accounting for 3·4% (2·2-4·6) of all deaths. Most of Asia, Australia, and New Zealand were observed to have a higher percentage excess in mortality than the global mean. Globally, the percentage excess in mortality increased by about 4·6% (3·7-5·3) per decade. The largest increase occurred in Australia and New Zealand (7·3%, 95% CI 4·3-10·4), followed by Europe (4·4%, 2·2-5·6) and Africa (3·3, 1·9-4·6). INTERPRETATION: Globally, a substantial mortality burden was associated with temperature variability, showing geographical heterogeneity and a slightly increasing temporal trend. Our findings could assist in raising public awareness and improving the understanding of the health impacts of temperature variability. FUNDING: Australian Research Council, Australian National Health & Medical Research Council.
- MeSH
- biodiverzita * MeSH
- celosvětové zdraví * MeSH
- lidé MeSH
- těhotenství MeSH
- teplota MeSH
- velkoměsta MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Geografické názvy
- Austrálie MeSH
- velkoměsta MeSH
The cardiovascular system is primarily controlled by the autonomic nervous system, and any changes in sympathetic or parasympathetic activity also have an impact on myocardial activity. Heart rate variability (HRV) is a readily available metric used to assess heart rate control by the autonomic nervous system. HRV can provide information about neural (parasympathetic, sympathetic, reflex) and humoral (hormones, thermoregulation) control of myocardial activity. Because there are no relevant reference values for HRV parameters in rats in the scientific literature, all experimental results are only interpreted on the basis of changes from currently measured control or baseline HRV values, which are, however, significantly different in individual studies. Considering the significant variability of published HRV data, the present study focused primarily on comparing control or baseline HRV values under different conditions in in vivo experiments involving rats. The aim of the study was therefore to assess whether there are differences in the starting values before the experiment itself.
