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Academic literature on the topic 'Respiration variations'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Respiration variations"

1

Liu, Yanchun, Qing Shang, Lei Wang, and Shirong Liu. "Effects of Understory Shrub Biomass on Variation of Soil Respiration in a Temperate-Subtropical Transitional Oak Forest." Forests 10, no. 2 (January 23, 2019): 88. http://dx.doi.org/10.3390/f10020088.

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Quantification of the temporal and spatial variations of soil respiration is an essential step in modeling soil carbon (C) emission associated with the spatial distribution of plants. To examine the temporal and spatial variations of soil respiration and its driving factors, we investigated soil respiration, microclimate, and understory vegetation in a 50 m × 70 m plot in a climatic transitional zone oak forest in Central China. The temporal variation of soil respiration based on the 21 measurements ranged from 15.01% to 30.21% across the 48 subplots. Structural equation modeling showed that soil temperature and understory shrub biomass had greater positive effects on the seasonal variability of soil respiration. The spatial variation of soil respiration of the 48 subplots varied from 3.61% to 6.99% during the 21 measurement campaigns. Understory shrub biomass and belowground fine root biomass positively regulated the spatial variation of soil respiration. Soil respiration displayed strong spatial autocorrelation, with an average spatial correlation length of 20.1 m. The findings highlight the importance of understory shrub and belowground biomass in regulating the temporal and spatial heterogeneity of soil respiration in forest ecosystems, and the need to carefully address it to robustly estimate the contribution of soil C emission in terrestrial C cycling.
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Wang, Dandan, Xinxiao Yu, Guodong Jia, Wei Qin, and Zhijie Shan. "Variations in Soil Respiration at Different Soil Depths and Its Influencing Factors in Forest Ecosystems in the Mountainous Area of North China." Forests 10, no. 12 (November 27, 2019): 1081. http://dx.doi.org/10.3390/f10121081.

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An in-depth understanding of the dominant factors controlling soil respiration is important to accurately estimate carbon cycling in forest ecosystems. However, information on variations in soil respiration at different soil depths and the influencing factors in forest is limited. This study examined the variations in soil respiration at two soil depths (0–10 and 10–20 cm) as well as the effects of soil temperature, soil water content, litter removal, and root cutting on soil respiration in three typical forest types (i.e., Pinus tabulaeformis Carrière, Platycladus orientalis (L.) Franco, and Quercus variabilis Bl.) in the mountainous area of north China from March 2013 to October 2014. The obtained results show that soil respiration exhibited strong seasonal variation and decreased with soil depth. Soil respiration was exponentially correlated to soil temperature, and soil respiration increased with soil water content until reaching threshold values (19.97% for P. tabulaeformis, 16.65% for P. orientalis, and 16.90% for Q. variabilis), followed by a decrease. Furthermore, interactions of soil temperature and water content significantly affected soil respiration at different soil depths of forest types, accounting for 68.9% to 82.6% of the seasonal variation in soil respiration. In addition to soil temperature and water content, aboveground litter and plant roots affected soil respiration differently. In the three forest types, soil respiration at two soil depths decreased by 22.97% to 29.76% after litter removal, and by 44.84% to 53.76% after root cutting. The differences in soil respiration reduction between the two soil depths are largely attributed to variations in substrate availability (e.g., soil organic content) and soil carbon input (e.g., litter and fine root biomass). The obtained findings indicate that soil respiration varies at different soil depths, and suggest that in addition to soil temperature and water content, soil carbon input and dissolved organic substances may exert a strong effect on forest soil respiration.
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Cheng, Xiang Rong, Mu Kui Yu, Tong Gui Wu, and Zong Xing Wang. "Soil Respiration and its Controlling Factors in Six Coastal Young Monoculture Plantations." Advanced Materials Research 726-731 (August 2013): 3751–56. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3751.

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Biotic and abiotic factors how to influence soil respiration in different young monoculture plantations are not clearly understood. Soil respiration and its controlling factors were studied in six monoculture plantations in the coastal area of Shanghai, China. Soil respiration was significant difference among six stands. Variations of soil respiration in six plots were not directly related to changes in soil water content, but significant relationship was observed between soil respiration and soil temperature. The variation of soil respiration was firmly correlated to the variation of leaf area index (LAI) or gap fraction (GF), soil respiration enhanced with the increase of GF (or decreasing LAI). The microclimate within forest and soil temperature also had positively correlation with soil respiration, but which mainly were affected by GF or LAI. There was no significant relationship between soil respiration and either root biomass or soil nutrients.
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Adachi, Minaco, Atsushi Ishida, Sarayudh Bunyavejchewin, Toshinori Okuda, and Hiroshi Koizumi. "Spatial and temporal variation in soil respiration in a seasonally dry tropical forest, Thailand." Journal of Tropical Ecology 25, no. 5 (September 2009): 531–39. http://dx.doi.org/10.1017/s026646740999006x.

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Abstract:Spatial and seasonal variation in soil respiration rates were investigated in a tropical dry forest in Thailand. The spatial variation was examined at 50 points within a 2-ha plot in the forest floor during the dry and wet seasons. The seasonal and diurnal variations in soil respiration were measured at 16 and 5 points, respectively. The mean soil respiration rate during the wet season was 1041 ± 542 mg CO2 m−2 h−1 (mean ± SD), which is about twice that during the dry season. Soil respiration rate was negatively correlated with soil water content during the wet season. A polynomial equation using seasonal data describes soil respiration and water content: soil respiration rate increased with soil water content, but started to drop when soil water content exceeded 21%. The diurnal variation in soil respiration rate during the wet season was positively correlated with soil temperature, whereas during the wet season it was not correlated with soil temperature. The diurnal variation in soil respiration rate during the dry season showed a midday depression. The estimation of soil carbon flux with polynomial equations should incorporate different functions for the wet and dry seasons in tropical dry forests.
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Talasila, P. Chowdary, Arthur C. Cameron, and Dennis W. Joles. "236 RESPIRATION AND TEMPERATURE VARIATION EFFECTS ON MA PACKAGING OF STRAWBERRIES AND RASPBERRIES." HortScience 29, no. 5 (May 1994): 463c—463. http://dx.doi.org/10.21273/hortsci.29.5.463c.

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Natural variation of product respiration rate and temperature variation during shipping and marketing influence the atmosphere inside MA packages. Respiration rate variation data was collected at 0C and 5.5C for `Allstar' and `Honeoye' strawberries and at 5.5C for `Heritage' raspberries. Coefficient of variation was 8% for raspberries and ranged from 6.5% to 12.5% for strawberries. To determine package-to-package variations, steady-state O2 partial pressures were measured in 100 similarly designed packages and frequency distributions were constructed. For `Honeoye' variety, `O2 partial pressures ranged from 3.5 kPa to 13.7 kPa with a median of 7.5 kPa in one set of packages and from 0.4 to 1.65 kPa with a median of 0.6 kPa in another set of packages with different design. Large variations were also observed for `Allstar' variety and raspberries. The results compared well with package O2 distributions predicted by a mathematical model that was constructed based on respiration rate variation. A modeling approach was used to predict frequency distributions and changes in gas levels in strawberry and raspberry packages for several possible temperature variation situations and for different types of package designs.
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Liu, Ying, and Shi Jie Han. "Diurnal and Seasonal Variations in Soil Respiration in a Temperate Broad-Leaved Korean Pine Forest, China." Applied Mechanics and Materials 295-298 (February 2013): 2318–23. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.2318.

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LI-6400-09 soil CO2 flux chamber (LI-COR, NE USA) and Subtraction method were used to investigate the diurnal and seasonal variations of soil respiration and the contribution of root respiration to total soil respiration in a temperate broad-leaved Korean Pine forest ecosystem, China. Soil temperatures at 5 cm depth were recorded by Hobo thermal recorder (at 1 h interval) and year-round soil respiration and the contribution of root could be calculated based the Q10 relationship. The results indicated that: Diurnal variations of total soil respiration (TRs) and root-severed soil respiration (RRs) were highly associated with variations of soil temperature at 5 cm depth in a day. total soil respiration, root-severed soil respiration (RRs) and root respiration (Rs) followed a similar seasonal trend that varied markedly during the growing season with high rates in summer and low rates in spring and autumn, coinciding with summer wet and high temperature, and in spring and autumn, with the lower temperature. The mean rates of TRs, RRs and Rs was 3.68, 2.02 and 1.63 µmol m-2 s-1, which were 1392.63, 764.43 and 616.84 g C m-2 y-1 respectively from May to September in 2004. TRs, RRs and Rs were exponentially correlated with temperature during growing season. However, there were no correlations between soil respiration and soil volumetric moisture. The Q10 values for TRs, RRs and Rs were 2.40, 2.42 and 2.50 respectively. The root was a major component of soil respiration, accounting for from 29.3 to 58.7% of the total soil respiration from May to September in 2004. The year-round mean of TRs, RRs and Rs were 1.95, 1.07 and 0.81 µmol m-2 s-1, which were 737.94, 404.92 and 306.53 g C m-2 y-1 respectively. Root respiration contributed 41.0% to the annual total soil respiration.
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Francioni, Matteo, Paride D’Ottavio, Roberto Lai, Laura Trozzo, Katarina Budimir, Lucia Foresi, Ayaka Wenhong Kishimoto-Mo, et al. "Seasonal Soil Respiration Dynamics and Carbon-Stock Variations in Mountain Permanent Grasslands Compared to Arable Lands." Agriculture 9, no. 8 (July 27, 2019): 165. http://dx.doi.org/10.3390/agriculture9080165.

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Permanent grasslands provide a wide array of ecosystem services. Despite this, few studies have investigated grassland carbon (C) dynamics, and especially those related to the effects of land-use changes. This study aimed to determine whether the land-use change from permanent grassland to arable lands resulted in variations in the soil C stock, and whether such variations were due to increased soil respiration or to management practices. To address this, seasonal variations of soil respiration, sensitivity of soil respiration to soil temperature (Q10), and soil C stock variations generated by land-use changes were analyzed in a temperate mountain area of central Italy. The comparisons were performed for a permanent grassland and two adjacent fields, one cultivated with lentil and the other with emmer, during the 2015 crop year. Soil respiration and its heterotrophic component showed different spatial and temporal dynamics. Annual cumulative soil respiration rates were 6.05, 5.05 and 3.99 t C ha−1 year−1 for grassland, lentil and emmer, respectively. Both soil respiration and heterotrophic soil respiration were positively correlated with soil temperature at 10 cm depth. Derived Q10 values were from 2.23 to 6.05 for soil respiration, and from 1.82 to 4.06 for heterotrophic respiration. Soil C stock at over 0.2 m in depth was 93.56, 48.74 and 46.80 t C ha−1 for grassland, lentil and emmer, respectively. The land-use changes from permanent grassland to arable land lead to depletion in terms of the soil C stock due to water soil erosion. A more general evaluation appears necessary to determine the multiple effects of this land-use change at the landscape scale.
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Liu, Gang, Rei Sonobe, and Quan Wang. "Spatial Variations of Soil Respiration in Arid Ecosystems." Open Journal of Ecology 06, no. 04 (2016): 192–205. http://dx.doi.org/10.4236/oje.2016.64020.

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Chi, Yonggang, Qingpeng Yang, Lei Zhou, Ruichang Shen, Shuxia Zheng, Zhaoyang Zhang, Zhenzhen Zhang, et al. "Temperature Sensitivity in Individual Components of Ecosystem Respiration Increases along the Vertical Gradient of Leaf–Stem–Soil in Three Subtropical Forests." Forests 11, no. 2 (January 25, 2020): 140. http://dx.doi.org/10.3390/f11020140.

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Temperature sensitivity (Q10) of ecosystem respiration (ER) is a crucial parameter for predicting the fate of CO2 in terrestrial e cosystems under global warming. Most studies focus their attention in the variation of Q10 in one or two components of ER, but not in the integration or comparison among Q10 in major components of ER. Vertical and seasonal variations in individual components, including leaf respiration, stem respiration and soil respiration, of ER were observed synchronously along the gradient of leaf–stem–soil over a 2 year period in three forest stands dominated by masson pine, loblolly pine and oak, respectively, in a subtropical forest ecosystem of central China. We found that Q10 in individual components of ER increased along the vertical gradient of leaf–stem–soil. The vertical pattern of Q10 in individual components of ER was ascribed to variations of diurnal temperature range (DTR) and activation energy (ΔHa). These results suggest that a vertical pattern of Q10 in individual components of ER along the gradient of leaf–stem–soil should be taken into consideration in process-based models that simulate respiratory carbon flux in terrestrial ecosystems.
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Xu, Ming, Terry A. DeBiase, and Ye Qi. "A simple technique to measure stem respiration using a horizontally oriented soil chamber." Canadian Journal of Forest Research 30, no. 10 (October 1, 2000): 1555–60. http://dx.doi.org/10.1139/x00-083.

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This paper introduces a simple technique, the horizontally oriented soil chamber (HOSC), to measure stem and branch respiration easily and accurately. We extend the function of the LI-6400-09 soil CO2 flux chamber by attaching a custom-built polyvinyl chloride (PVC) collar to the stem surface. For small trees and branches we use pipe bushings to connect the chamber to stem surface. Using this technique we measured stem respiration in a young ponderosa pine (Pinus ponderosa Dougl. ex Laws.) plantation in the Sierra Nevada Mountains near Georgetown, Calif., from June to December 1998. The diurnal and seasonal variations in respiration rate correlate well with the corresponding stem temperature variation. The Q10 values varied from 1.9 to 2.8, which are within the range of Q10 values (1.3-3.3) reported in previous studies. The range of our stem respiration results (3.5-7.2 µmol·m-2·s-1) compares favorably with previous studies on young ponderosa pine trees. This technique provides an alternative to measure stem respiration, which employs widely used, commercially available, portable respiration measurement equipment and requires almost no additional equipment, especially for current owners of LI-6400 systems. Thus, the HOSC technique is appropriate for examining spatial variation of stem respiration.
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Dissertations / Theses on the topic "Respiration variations"

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Dhervillez, Catherine. "Contribution à l'étude des mécanismes des variations respiratoires du rythme cardiaque chez le rat." Lille 1, 1987. http://www.theses.fr/1987LIL10092.

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Il existerait trois types de mécanismes : un mécanisme central consistant en une irradiation des centres respiratoires sur les centres cardio-régulateurs ; un mécanisme réflexe ayant son origine au niveau soit du cœur, des poumons, du thorax, soit au niveau vasculaire ; un mécanisme ayant plusieurs origines
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2

Mavrogiannis, Apostolos. "Variations in the ventilatory and lactate thresholds with prolonged aerobic exercise." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25127.

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The purpose of this study was to examine the changes in the ventilatory (VT) and lactate (LT) thresholds and VO₂max following prolonged aerobic exercise. Six well-trained distance runners (T:age=25.2 yrs, Ht=170.0 cm, Wt=65.0 kg, VO₂max=59.6 ml •kg⁻¹•min⁻¹) and six untrained (UT:age=25.3 yrs, Ht=180.3 cm, Wt=79.2 kg, VO₂max=46.8 ml•kg⁻¹•min⁻¹) males were studied on two occasions seven days apart. The initial evaluation involved a continuous horizontal treadmill test with a starting velocity of 2.22 m•s⁻¹, which was increased by 0.22 m•s⁻¹ each minute until fatigue. Expired gases were continuously sampled and analyzed by a Beckman Metabolic Measurement Cart. Measurements were processed by a data acquisition system (HP 3052A), which determined respiratory gas exchange variables every 15 seconds. Blood lactate measurements were taken via an indwelling catheter during the last 10 sec of each minute of work. VT and LT were determined by visual inspection of the excess CO₂ elimination and lactate curves, respectively. Seven days later the subjects repeated the treadmill test preceded by a 60 minute treadmill run at a heart rate corresponding to their LT. The physiological measurements recorded during the first session were repeated. There were significant (p<0.10) reductions in VO₂max, LT, VT, and total treadmill time on the VO₂max test (TTT) in the T group (59.6 to 56.9 ml •kg⁻¹•min⁻¹, 9.6 to 9.3 mph , 8.9 to 8.2 mph , and 925.0 to 882.5 sec, respectively). VO₂max, LT, VT, and TTT were reduced in the UT group (46.8 to 45.0 ml•kg⁻¹•min⁻¹ 7.7 to 7.6 mph, 8.0 to 7.2 mph, and 730.0 to 652.5 sec, respectively), however, only VT and TTT were reduced significantly (p<0.10). Although the groups were significantly different (p<0.05) in the initial physiological measures due to training status, there was no change in the rate of decline in VO₂max, LT, VT, or TTT when the UT group was compared to T. As LT and VT are affected by prolonged aerobic exercise it is questionable whether these thresholds can be used with confidence to predict endurance performance in events up to 60 min duration for well-trained and recreational athletes.
Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
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3

Comstedt, Daniel. "Explaining temporal variations in soil respiration rates and delta13C in coniferous forest ecosystems." Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2055.

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Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.
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Ceschia, Eric. "Environmental effects on spatial and seasonal variations of stem respiration in European beech and Norway spruce /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6303-3.pdf.

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Ceschia, Eric. "Effets environnementaux sur les variations spatiales et saisonnières de la respiration ligneuse chez le hêtre et l'épicéa." Paris 11, 2001. http://www.theses.fr/2001PA112349.

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Cette thèse discute des facteurs environnementaux et biologiques contrôlant la respiration ligneuse chez le Hêtre et l'Epicéa. Les résultats sont issus de mesures sur le terrain en France et en Suède entre 1997-2000. Les effets de la fertilisation et des fortes [CO2] sur la croissance et la respiration des tiges furent étudiés. La respiration ligneuse variait avec les changements saisonniers de température et de croissance secondaire. Les variations spatiales de la respiration étaient dues à des gradients de température, distributions inégales de cellules vivantes, différences de croissance radiale, et différences de vitalité le long des axes. Les plus forts taux de respiration étaient enregistrés au sommet des troncs ou dans la couronne. Négliger ces variations spatiales de respiration causeraient des erreurs de 30-110% dans l'estimation de la respiration annuelle des parties ligneuses aériennes (Rag). Rag représentait près de 30% de la respiration totale annuelle pour la forêt de Hêtre. Rag était de 245-289 g C m-2 a-1 pour le Hêtre et de 64 et 134 g C m-2 a-1 pour les couverts d'Epicéa non-traités et fertilisés, respectivement. L'efficience d'utilisation du carbone était de 0. 58, 0. 71, et 0. 72 pour le Hêtre et les Epicéas non-traités et fertilisés, respectivement. La respiration de croissance représentait près de 40% de la respiration totale. Le coût moyen de construction du bois (rG) était de 0. 2 et 0. 16 g C respiré g-1 C fixé dans le nouveau cerne pour le Hêtre et l'Epicéa mais rG augmentait dans la couronne par rapport à la base du tronc. La fertilisation accroissait rG pour l'Epicéa mais la respiration d'entretient (R_M) n'était pas affectée. En forte [CO2], rG augmentait légèrement pour l'Epicéa mais pas pour le Hêtre. RM n'était pas affecté par les [CO2] pour les arbres fertilisés, mais en absence de fertilisation, Rm augmentait d'un facteur 2. 5 pour l'Epicéa. Des changements de composition du bois pourraient expliquer les augmentations de rG et Rm
This thesis discusses the environmental and biological factors controlling stem respiration in beech and Norway spruce trees. The results are based on field experiments in France and Sweden in 1997-2000. Effects of fertilization and high atmospheric [CO2] on stem growth and respiration were studied. Woody respiration varied with seasonal changes in temperature and secondary growth. Spatial variation in respiration was explained by temperature gradients, uneven distribution of living cells, differences in diameter increment along the axis and variations in tissue vitality. Higher respiration rates usually were found in the upper stem or in the crown. Neglect of spatial variation in respiration led to errors in estimating annual aboveground woody respiration (Rag) of 30-110%. Rag represented 30% of annual respiration in the beech forest. Rag was 245-289 g C m-2a-1 in beech, 64 and 134 g C m-2 a-1 in control and fertilized stands of Norway spruce, respectively. Carbon use efficiency was 0. 58, 0. 71, and 0. 72 for beech trees, control and fertilized spruce trees, respectively. Growth respiration represented ca. 40% of total stem respiration. The wood construction cost (rG) was on average 0. 2 and 0. 16 g C respired g-1 C fixed in the new wood of beech and spruce trees. For both species, rG was higher in the crown than at breast height. Fertilization increased rG in spruce, but maintenance respiration (RM) was not affected. High [CO2] had little effect on rG in spruce and none in beech. [CO2] had no effect on Rm when fertilization was applied but Rm increased by a factor of 2. 5 for spruce in absence of fertilization. A change in wood composition of trees grown in high [CO2] without fertilization, apparently caused the increase in rG and Rm. In perspective of global warming, Rag would increase by 25% and 14% in young beech and Norway spruce forests, respectively, and the combined effect of high [C02] and global, warming would increase Rag by a factor of 2. 3 in spruce stands
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6

Comstedt, Daniel. "Explaining temporal variations in soil respiration rates and delta13C in coniferous forest ecosystems." Doctoral thesis, Örebro University, Institutionen för naturvetenskap Department of Natural Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2055.

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Soils of Northern Hemisphere forests contain a large part of the global terrestrial carbon (C) pool. Even small changes in this pool can have large impact on atmospheric [CO2] and the global climate. Soil respiration is the largest terrestrial C flux to the atmosphere and can be divided into autotrophic (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic (from decomposers of organic material) respiration. It is therefore crucial to establish how the two components will respond to changing environmental factors. In this thesis I studied the effect of elevated atmospheric [CO2] (+340 ppm, 13C-depleted) and elevated air temperature (2.8-3.5 oC) on soil respiration in a whole-tree chamber (WTC) experiment conducted in a boreal Norway spruce forest. In another spruce forest I used multivariate modelling to establish the link between day-to-day variations in soil respiration rates and its δ13C, and above and below ground abiotic conditions. In both forests, variation in δ13C was used as a marker for autotrophic respiration. A trenching experiment was conducted in the latter forest in order to separate the two components of soil respiration. The potential problems associated with the trenching, increased root decomposition and changed soil moisture conditions were handled by empirical modelling. The WTC experiment showed that elevated [CO2] but not temperature resulted in 48 to 62% increased soil respiration rates. The CO2-induced increase was in absolute numbers relatively insensitive to seasonal changes in soil temperature and data on δ13C suggest it mostly resulted from increased autotrophic respiration. From the multivariate modelling we observed a strong link between weather (air temperature and vapour pressure deficit) and the day-to-day variation of soil respiration rate and its δ13C. However, the tightness of the link was dependent on good weather for up to a week before the respiration sampling. Changes in soil respiration rates showed a lag to weather conditions of 2-4 days, which was 1-3 days shorter than for the δ13C signal. We hypothesised to be due to pressure concentration waves moving in the phloem at higher rates than the solute itself (i.e., the δ13C–label). Results from the empirical modelling in the trenching experiment show that autotrophic respiration contributed to about 50% of total soil respiration, had a great day-to-day variation and was correlated to total soil respiration while not to soil temperature or soil moisture. Over the first five months after the trenching, an estimated 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root decomposition. In conclusion, elevated [CO2] caused an increased C flux to the roots but this C was rapidly respired and has probably not caused changes in the C stored in root biomass or in soil organic matter in this N-limited forest. Autotrophic respiration seems to be strongly influenced by the availability of newly produced substrates and rather insensitive to changes in soil temperature. Root trenching artefacts can be compensated for by empirical modelling, an alternative to the sequential root harvesting technique.

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Thomachot, Laurent. "Effet des variations de température et d'humidification des gaz inspires sur la mécanique pulmonaire chez le sujet en ventilation contrôlée." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX20844.

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Maxime, Valérie. "Contribution à l'étude de la physiologie respiratoire du saumon atlantique (Salmo salar L. ) aux différentes étapes critiques de son cycle biologique : influence des variations de salinité ambiante." Brest, 1990. http://www.theses.fr/1990BRES2013.

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Le metabolisme energetique a ete etudie chez les juveniles de saumon atlantique (parrs et smolts), simultanement en conditions de metabolisme standard et de routine. Les modifications qui surviennent au cours de la smoltification ont ete interpretees en fonction des variations du facteur thermique (isoenzymes) et des facteurs endocriniens qui sous-tendent ce processus. L'action stimulante majeure du metabolisme energetique apparait resulter d'une potentialisation de l'effet de l'hormone de croissance par la triiodothyronine. Il a pu etre etabli que les modifications du metabolisme standard, consecutives a des transferts d'eau douce en eau de mer, etaient differentes selon le niveau d'adaptation au milieu marin acquis par les smolts: diminution chez les presmolts, amplification au terme de la smoltification. Ces effets resultent essentiellement des modifications du metabolisme intermediaire induites par l'augmentation de salinite ambiante. De plus, le surcout energetique de l'osmoregulation serait plus faible que ce qui etait admis jusqu'alors. Parallelement, a ete mise en evidence une diminution du metabolisme de routine, interpretable comme une adaptation comportementale a une limitation des possibilites d'approvisionnement tissulaire en oxygene. Chez le saumon adulte, le transfert inverse d'eau de mer en eau douce induit une diminution du metabolisme energetique, une augmentation de la capacite de diffusion gazeuse des branchies, ainsi que des modifications des concentrations ioniques plasmatiques entrainant une alcalose du compartiment extracellulaire et une augmentation de l'affinite de l'hemoglobine pour l'oxygene. Ces effets pourraient constituer des processus adaptatifs pour la migration anadrome
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Courtiol, Emmanuelle. "L'inextricable relation olfaction-respiration chez le rat : études de l'impact des variations de flairages sur l'activité du bulbe olfactif et sur la discrimination des odeurs." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-01070877.

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Chez les mamifères terrestres, l'échantillonnage des odeurs (flairage) est inextricablement lié à la respiration. Le flairage contraint à la fois le décours temporel et l'intensité de l'input olfactif. Or le flaireage est un acte dynamique, il peut varier aussi bien en fréquence qu'en débit. Dans une 1ère partie de mon travail de thèse, nous avoins souhaité caractériser l'impact des variations de fréquence et de débit respiratiore sur l'activité du bulbe olfactif. Pour cela, nous avons mis au point une méthode de double trachéotomie chez le rat anesthésié nous permettant de contrôler précisément les flux d'air ans la cavité nasale. En paralèlle, nous avons enregistrer l'acitivité unitaire et de réseau du bulbe olfactif. Nous montrons que les variations de flairage modulent la représentation neuronale bulbaire des odeurs en modifiant à la fois l'activité de décharge des cellules principales et l'occurence des oscillaations du potentiel de champ local. Dans une 2e partie de ma thèse, nous avons souhaitécomprendre quel pouvait être le rôle du flairage chez un animal qui se comporte. Nous avons posé l'hypothèse qu'un animal pouvait adapter sa façon de flaireer en fonction de la qualité des molécules odorantes. Pour tester cette hypothèse, nous avons mis au point un système d'enregeistrement non invasif de la respiration couplé à une tâche de discrimination olfactive chez le rat. Nous montrons non seulement que les animaux peuvent adapter leur flairage en fonction des molécules odorantes masi également en focntion du contexte dans lequel l'odeur est présentée. L'ensemble de ces résultats s'intègre donc dans la problématique plus générale de l'intégration sensori-motrice.
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Courtiol, Emmanuelle. "L’inextricable relation olfaction-respiration chez le rat : études de l’impact des variations de flairages sur l’activité du bulbe olfactif et sur la discrimination des odeurs." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10309/document.

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Chez les mamifères terrestres, l’échantillonnage des odeurs (flairage) est inextricablement lié à la respiration. Le flairage contraint à la fois le décours temporel et l’intensité de l’input olfactif. Or le flaireage est un acte dynamique, il peut varier aussi bien en fréquence qu’en débit. Dans une 1ère partie de mon travail de thèse, nous avoins souhaité caractériser l’impact des variations de fréquence et de débit respiratiore sur l’activité du bulbe olfactif. Pour cela, nous avons mis au point une méthode de double trachéotomie chez le rat anesthésié nous permettant de contrôler précisément les flux d’air ans la cavité nasale. En paralèlle, nous avons enregistrer l’acitivité unitaire et de réseau du bulbe olfactif. Nous montrons que les variations de flairage modulent la représentation neuronale bulbaire des odeurs en modifiant à la fois l’activité de décharge des cellules principales et l’occurence des oscillaations du potentiel de champ local. Dans une 2e partie de ma thèse, nous avons souhaitécomprendre quel pouvait être le rôle du flairage chez un animal qui se comporte. Nous avons posé l’hypothèse qu’un animal pouvait adapter sa façon de flaireer en fonction de la qualité des molécules odorantes. Pour tester cette hypothèse, nous avons mis au point un système d’enregeistrement non invasif de la respiration couplé à une tâche de discrimination olfactive chez le rat. Nous montrons non seulement que les animaux peuvent adapter leur flairage en fonction des molécules odorantes masi également en focntion du contexte dans lequel l’odeur est présentée. L’ensemble de ces résultats s’intègre donc dans la problématique plus générale de l’intégration sensori-motrice
In terrestrial mammals, an inextricable link between olfaction and respiration exists due to the periodic sampling of odorant molecules by inhalation. The features of sniffing (or breathing) constrain both the timing and the intensity of the input to the olfactory structures. But rather than being fixed, sniffing in the bahavingrodent is highly dynamic and varies both in frequency and flow rate. During the firs stage of my PhD, I asked to what extent sniffing parameters (frequency and flow rate) variations could affect the olfactory bulb activity. To address this question, I developped a double tracheotomy protocol in anesthetized rats to precisely control and modify the nasal airflow. In parallel, I recorded oldfactory bulbactivities, single-unit activity and local field potentials. We showed that, at the olfactory bulb level, the neutral representation of an odor is highly modified by sampling variations. In fact both the mitral/tufted cell discharge patterns and local field potentials oscilliations were affected by sniffing variations. In the second stage, we wanted to understand the role of sniffing variations in behaving animals. We hypothesized tha t an animal could adapt its sniffing strategy relative to the quality of the odorant molecules. To test this hypothesis, we developped a tool to record sniffing in a non invasive way, and combined it to an olfactory discrimination task in the rat. We showed that animals not only adapted their sniffing relative to the odorant quality but also to the odorant context. Taken together, these results fit into the broader context of sensory-motor integration
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Books on the topic "Respiration variations"

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Variations in the ventilatory and lactate thresholds with prolonged aerobic exercise. 1985.

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Variations in the ventilatory and lactate thresholds with prolonged aerobic exercise. 1986.

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Givnish, Thomas J., K. William Sparks, Steven J. Hunter, and Andrej Pavlovič. Why are plants carnivorous? Cost/benefit analysis, whole-plant growth, and the context-specific advantages of botanical carnivory. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198779841.003.0018.

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The 1984 cost/benefit model for the evolution of carnivorous plants addresses their potential energetic and ecological advantages. It has provided a conceptual framework for research on distribution, variation in trap allocation and mechanisms, association with low rates of photosynthesis and whole-plant growth, and ecology of carnivorous plants relative to noncarnivorous ones. We re-assess this model, its potential extensions, and the validity of its assumptions and predictions. We review what is known about photosynthesis, respiration, relative growth rates, and resource allocation in carnivorous and noncarnivorous plants, and growth, nutrient limitation and stoichiometry, adaptation to different prey, and optimal trap allocation of carnivorous plants. We propose explanations for six ecological and evolutionary paradoxes involving carnivorous plants. Future advances will hinge on better quantification of the cost/benefit model and comparing model predictions with data.
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Hill, Geoffrey E. Mitonuclear Ecology. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198818250.001.0001.

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Eukaryotes were born of a chimeric union of two prokaryotes. The legacy of this fusion is organisms with both a nuclear and mitochondrial genome that must work in a coordinated fashion to enable cellular respiration. The coexistence of two genomes in a single organism requires tight coadaptation to enable function. The need for coadaptation, the challenge of co-transmission, and the possibility of genomic conflict between mitochondrial and nuclear genes have profound consequences for the ecology and evolution of eukaryotic life. This book defines mitonuclear ecology as an emerging field that reassesses core concepts in evolutionary ecology in light of the necessity of mitonuclear coadaptation. I discuss and summarize research that tests new mitonuclear-based theories for the evolution of sex, two sexes, senescence, a sequestered germ line, speciation, sexual selection, and adaptation. The ideas presented in this book represent a paradigm shift for evolutionary ecology. Through the twentieth century, mitochondrial genomes were dismissed as unimportant to the evolution of complex life because variation within mitochondrial genomes was proposed to be functionally neutral. These conceptions about mitochondrial genomes and mitonuclear genomic interactions have been changing rapidly, and a growing literature in top journals is making it increasingly clear that the interactions of the mitochondrial and nuclear genomes over the past 2 billion years have played a major role in shaping the evolution of eukaryotes. These new hypotheses for the evolution of quintessential characteristics of complex life hold the potential to fundamentally reshape the field of evolutionary ecology and to inform the emerging fields of mitochondrial medicine and mitochondrial-based reproductive therapies.
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Book chapters on the topic "Respiration variations"

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Goncharova, O. Yu, G. V. Matyshak, M. M. Udovenko, A. A. Bobrik, and O. V. Semenyuk. "Seasonal and Annual Variations in Soil Respiration of the Artificial Landscapes (Moscow Botanical Garden)." In Springer Geography, 112–22. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-89602-1_15.

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Shigemi, Akita. "Respiration: Variation and Potential for Manipulation." In International Crop Science I, 799–805. Madison, WI, USA: Crop Science Society of America, 2015. http://dx.doi.org/10.2135/1993.internationalcropscience.c127.

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Aspinwall, Michael J., Thomas E. Juenger, Paul D. Rymer, Alexis Rodgers, and David T. Tissue. "Chapter 6 Intraspecific Variation in Plant Responses to Atmospheric CO2, Temperature, and Water Availability." In Advances in Photosynthesis and Respiration, 133–69. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64926-5_6.

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Zhuang, Ziqing, Dennis Slice, Stacey Benson, Douglas Landsittel, and Dennis Viscusi. "Facial Shape Variation of U.S. Respirator Users." In Digital Human Modeling, 578–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02809-0_61.

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Davidson, Eric A., and N. Michele Holbrook. "Is Temporal Variation of Soil Respiration Linked to the Phenology of Photosynthesis?" In Phenology of Ecosystem Processes, 187–99. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-1-4419-0026-5_8.

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Gessler, Arthur, and Juan Pedro Ferrio. "Postphotosynthetic Fractionation in Leaves, Phloem and Stem." In Stable Isotopes in Tree Rings, 381–96. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_13.

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AbstractStable carbon isotope ratios (δ13C) in organic matter convey important integrated and (if assessed in the tree ring archive) dateable information on plant physiology and related environmental drivers. While the generation of the δ13C signal in the primary assimilates in the leaves via photosynthetic carbon isotope fractionation is well understood, we still lack detailed knowledge of the processes that determine the isotopic fractionation in downstream processes in the leaves and during the transport in the stem, which in turn affect δ13C in the tree-ring archive. We here provide an update on processes that drive post-carboxylationcarbon isotope fractionation in the leaves, on potential changes in δ13C related to phloem loading and transport and we also discuss the role of stem CO2 fluxes (bark photosynthesis, stem respiration and CO2 fixation by phosphoenol pyruvate carboxylase). Moreover, we address the impact of carbon storage and remobilization on the intra-annual variation of δ13C in tree rings. Finally, we point to the potential importance of the intra-molecularcarbon isotope distribution in carbohydrates for tree ring δ13C and its relation to shifts in metabolic pathways.
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Lambers, Hans, and Adrie Van Der Werf. "Variation in the rate of root respiration of two Carex species: A comparison of four related methods to determine the energy requirements for growth, maintenance and ion uptake." In Structural and Functional Aspects of Transport in Roots, 131–35. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0891-8_26.

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Luo, Yiqi, and Xuhui Zhou. "Temporal and Spatial Variations in Soil Respiration." In Soil Respiration and the Environment, 107–31. Elsevier, 2006. http://dx.doi.org/10.1016/b978-012088782-8/50006-1.

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Urooj, Shabana, M. Khan, and A. Q. Ansari. "Thorax." In Advanced Instrument Engineering, 127–33. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4165-5.ch009.

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In this paper, the authors prove that variations in thoracic volumes are greatly responsive to the act of breathing (i.e., inspiration and expiration). These variations may be adopted for diagnosing various respiration related diseases and pulmonary edema. In this study, the authors present a method to estimate the thoracic volume non-invasively using anthropometric dimensions. The change in the geometry of thorax with the act of breathe is recorded by measuring the anthropometric parameters for nine healthy human subjects. The model based approach shows the extent of its sensitivity in terms of volumetric variations with the state of inspiration and expiration. Many deaths occur due to unavailability of health care and monitoring systems in rural areas and developing countries. The technique presented in this paper takes care of these situations and the volumetric estimation of thorax is independent of any instrumentation, expensive equipment, and clinical environment.
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Post, Eric. "Ecosystem Function and Dynamics." In Ecology of Climate Change. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691148472.003.0008.

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This chapter focuses on the distinction between ecosystem function and ecosystem dynamics. Ecosystem function refers to the manner in which the ecosystem of interest works, and interactions among its component parts and fluxes, including biotic and abiotic compartments. Meanwhile, ecosystem dynamics refers to variation in ecosystem function through time in response to perturbations that are continuous or stochastic in nature, or in relation to changes in ecosystem components. Therefore, the study of ecosystem dynamics derives from an understanding of ecosystem function, and this, in turn, depends critically on successful identification of the important drivers within the ecosystem. Inevitably, a discussion of ecosystem function and dynamics boils down to the factors that influence and contribute to variation in net ecosystem production—the result of net primary productivity and ecosystem respiration.
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Conference papers on the topic "Respiration variations"

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Porta, Alberto, Beatrice Cairo, Beatrice De Maria, and Vlasta Bari. "Complexity of Spontaneous QT Variability Unrelated to RR Variations and Respiration During Graded Orthostatic Challenge." In 2020 Computing in Cardiology Conference. Computing in Cardiology, 2020. http://dx.doi.org/10.22489/cinc.2020.009.

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Hahm, ChanYoung, SeungMin Lee, and HyunSoon Shin. "Analysis of irregular breathing using respiration-induced intensity variations (RIIV) from photoplethysmography signals for sleep apnea." In 2016 International Conference on Information and Communication Technology Convergence (ICTC). IEEE, 2016. http://dx.doi.org/10.1109/ictc.2016.7763433.

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Abraham, John P., Eph M. Sparrow, and Ryan D. Lovik. "Pulsating Fluid Flows Undergoing Transitions Between Laminar, Transitional, and Turbulent Regimes." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206683.

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The two major fluid flow systems of the human body, blood circulation and respiration, experience timewise pulsations. The variations of the fluid velocity during a pulsation/respiration cycle give rise to transitions in the flow regime during the course of a cycle. At the lowest fluid velocity encountered in the cycle, it is likely that the flow is laminar. As the velocity increases, the laminar regime may transist into a regime called transitional intermittent. Further increases in velocity may lead either to the fully developed intermittent regime or to the fully developed turbulent regime. Once the velocity attains a maximum and begins to decrease, the process of laminarization may be initiated wherein a succession of flow regimes may occur in opposite order to that described in the foregoing. The current capabilities of numerical simulation are limited to a single, user-specified flow regime, either laminar or turbulent. Consequently, the successive spontaneous flow regime transitions encountered in human-body fluid flows have been heretofore beyond the reach of biomedical investigators. Indeed, a thoroughgoing literature review failed to unearth any biomedical-oriented publications in which flow regime transitions have been taken into account. The present investigation is aimed at applying, for the first time, a flow transition model previously developed for steady flows to unsteady flows. The flows to be considered are timewise periodic, with amplitudes, periods, and mean values appropriate to blood flows in large arteries. Special consideration will be given to the magnitudes of the wall shear stresses that are created by such flows, since the accumulation of plaque depends decisively on the shear. The work will also take account of variations in the flow geometry.
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Xi Liu, Qingxi Guo, and Jingwei Liu. "Notice of Retraction: Factors causing temporal variations of soil respiration and its components in northeast of China using IBIS model." In 2011 2nd International Conference on Artificial Intelligence, Management Science and Electronic Commerce (AIMSEC 2011). IEEE, 2011. http://dx.doi.org/10.1109/aimsec.2011.6010566.

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Huang, Ni, Zheng Niu, and Li Wang. "Application of HJ-1 CCD data to analyze the growing-season variations of soil respiration in two irrigated cropland ecosystems." In IGARSS 2016 - 2016 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2016. http://dx.doi.org/10.1109/igarss.2016.7729775.

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Rawat, Monika. "Soil Respiration Variation under the Canopy of Dominant Tree Species across different seasons in Temperate Forest." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0021.

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Soil respiration is defined as the production of carbon dioxide when soil organisms are active. It is an important process in the ecosystem and has direct influence on climate change. Therefore understanding it under different vegetation types is an essential goal in soil science. The major sources which effect the soil respiration rate are plant roots, the rhizosphere, microbes and soil fauna and these sources are control by various factors like temperature, moisture, nutreint content and oxygen in the soil. Soil respiration rate is important for understanding soil biological activity, nutrient cycling, soil microbial biomass, soil organic matter and its decomposition.Therefore soil respiration was studied under the canopy of ten dominant tree species of temperate forest. Our study determined that highest soil respiration was under the canopy of Eunonymous pendulus (EP) i.e. 20.01 μmolm−2 s−1 and across season it was high during the rains.
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Giorges, Aklilu T. G., and John A. Pierson. "The Cooling Process of Agricultural Products After Boxing and Palletizing." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87788.

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Assuring that food products have acceptable quality and are safe to consume requires maintaining adequate nutrition levels and fulfilling consumer expectations. Quality losses can lead to food waste, resulting in increased economic costs and low consumer confidence. Therefore, quality expectations should be maintained at an acceptable level for consumer purchase and consumption. It is well known that a cold environment reduces the respiratory activities and kinematics of nutritional degradation. The cooling temperature is critical since lower than recommended cold temperatures may cause chill damage. Therefore, the food industry intensively employs cold storage methods to slow respiration rates, inhibit harmful bacterial growth, reduce water loss, and prolong shelf life in order to maintain product nutritional value and quality. Improving product cooling efficiency will reduce energy costs that are a significant expense for fruit and vegetable processors. Understanding the cooling process is key to the development of new technology and processes. However, most natural food products are not conformed to simple geometric shapes or uniform properties and distributions. Thus, the cooling process of an agricultural product (cucumbers) was investigated in this study. The study was conducted in a packing house, where the cooling temperature of the cucumbers was recorded by placing multiple thermocouples in the produce after boxing and palletizing as well as cold storage. The test results showed that individual produce cooling was relatively easy to predict. However, boxed and palletized cucumber cooling showed significant variations. For example, the temperature of the cucumbers changed depending on their location in the box in addition to the box location on the stack. In the case of boxed produce cooled by natural convection cooling, the temperature changed from 25 to 18 °C after three hours. However, in the case of palletized tunnel cooled, the temperature change ranged from 25 to 11 °C and 25 to 18 °C after nearly three hours of cooling. Indeed, the temperature differences indicated that the cooling rate has significant variations depending on the location of the produce. Some parts of the pallet received more direct contact with the forced cold air than other parts. Thus, it is very important for produce processors to understand cooling system performance. The study emphasized that efficient use of energy is one of the areas that can have not only significant cost savings but can also improve produce shelf life, reduce food waste, and maintain consumer confidence.
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Lei, Zhipeng, and James Yang. "Computing Carbon Dioxide and Humidity in Filtering Facepiece Respirator Cavity During Breathing Cycles." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34660.

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Carbon dioxide (CO2) and humidity are two factors that affect respirator comfort. Whenever one uses a respirator, CO2 is reinhaled from the previous exhalation and the humidity inside the respirator cavity increases. The CO2 reinhalation causes respirator discomfort with symptoms like headache, dizziness, and etc. The increased humidity causes respirator thermal discomfort. Experimental researches focused on measuring the CO2 and humidity values in the respirator cavity during a long period of time (over 1 hour). However, these experiments ignored CO2 and humidity value variation during a breathing cycle within the respirator cavity. The objective of this study was to use computational fluid dynamics (CFD) method to calculate the CO2 and humidity values inside the respirator cavity during four breathing cycles (19.2s). In our previous work the contact between a headform and a filtering facepiece respirator (FFR) was simulated by the using finite element modeling. In this work a meshed domain was generated including the FFR cavity, the FFR and the region outside of the FFR. A breathing cycle, having both exhalation and inhalation, was then defined as a time-dependent flow rate through a breathing opening (nasal breathing, mouth breathing, and nasal-mouth breathing). Using CFD method, the breathing air flow and the species transport of CO2 and water vapor (H2O) in the domain were simulated for 4 breathing cycles. Totally 5 tests with different breathing openings and different breathing flow rates were conducted: nasal breathing with base, 2 and 3 times flow rate, mouth breathing with base flow rate, and nasal-mouth breathing with base flow rate. The simulation results showed that there were large CO2 and H2O value variations (CO2 mass fraction from 0 to 0.074 and H2O mass fraction 0.0077 and 0.0151) in the FFR cavity during a breathing cycle. The inhaled CO2 mole fraction decreased with increasing breathing flow rate. With the base flow rate, during inhalation the middle point between the nostrils and mouth had higher relative humidity than other probing positions did.
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Holman, Beverley F., Vesna Cuplov, Ottavia Bertolli, Ashley M. Groves, Brian F. Hutton, and Kris Thielemans. "Density variation during respiration affects PET quantitation in the lung." In 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). IEEE, 2015. http://dx.doi.org/10.1109/nssmic.2015.7582029.

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Leier, Mairo, Gert Jervan, and Wilhelm Stork. "Respiration signal extraction from photoplethysmogram using pulse wave amplitude variation." In ICC 2014 - 2014 IEEE International Conference on Communications. IEEE, 2014. http://dx.doi.org/10.1109/icc.2014.6883869.

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Reports on the topic "Respiration variations"

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Cameron, Arthur, Shimshon Ben-Yehoshua, and Rebecca Hernandez. Design and Function of Modified Atmosphere Packaging Systems for Fresh Produce: a Unified Approach for Optimizing Oxygen, Carbon Dioxide and Relative Humidity. United States Department of Agriculture, January 1996. http://dx.doi.org/10.32747/1996.7613019.bard.

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Oxygen uptake, CO2 production and respiratory quotient (RQ) of strawberry, raspberry and cherry were measured as functions of temperature and oxygen level. The effect of cultivar was studied in strawberry ('Honey' and 'Allstar'). The effect of harvest date was studied for raspberry. The lower O2 limit increased markedly with incraqsing temperature for all fruits studied. Red bell pepper O2 uptake was measured as a function of O2 at 20o C. Lowering the inpackage humidity using NaCl reduced decay of bell pepper sealed in low-density polyethylene packages when stored at 8o C. Analyses of a model developed for MA-packaged red bell pepper fruit demonstrated that when RQ was near one and when CO2 exceeded O2 permeability, transient CO2 levels increased to a maximum before dropping to steady-state levels. An isothermal model of O2, CO2 and water vapor exchange in MA packages was developed for red bell pepper and tested empirically. A comprehensive model was developed for small fruits that also incorporated water vapor and the effects of changing temperature. Variation in package O2 levels was measured and modeled as a function of variation in respiration and film permeability.
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