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Measuring basal soil respiration across Europe: Do incubation temperature and incubation period matter?

Creamer, R.E.; Schulte, R.P.O.; Stone, D.; Gal, A.; Krogh, P.H.; Lo Papa, G.; Murray, P.J.; Pérès, G.; Foerster, B.; Rutgers, M.; Sousa, J.P.; Winding, A.
Fonte: Elsevier Ltd. Publicador: Elsevier Ltd.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.81%
The European Commission recognises the essential role of soil biology in soil functioning and delivery of ecosystem services, but information is currently lacking evaluate of how these vary across soil and land-use types at a European scale. This study evaluated the measurement of the initial rate of soil basal respiration (BR) as a potential biological indicator of ecosystem service provision. The purpose of this study was to test ISO 16072:2002 (Soil Quality: Laboratory methods for the determining of microbial soil respiration). In the literature a range of pre-incubation temperatures (pre-inc) and experimental incubation temperatures (exp-inc) have been applied when using the ISO method for the establishment of basal respiration. This study evaluated whether the range of temperatures applied during pre- and exp- incubation had a significant effect on the rate of respiration determined when following the protocol established in ISO 16072:2002. The evaluation was carried out on a pedo-climatic gradient spanning ten countries across Europe and covering four biogeographical regions. Three sites were sampled in each country providing a range of soil and land-use parameters. Our results suggest that experimental incubation temperatures of 20 ◦C or above should be used in the application of the methodology ISO 16072:2002 (incubation at 15 ◦C resulted in erratic variation between replicates). However...

Modeling the effect of oxygen availability and storage temperature on fresh-cut strawberry respiration rate

Amaro, Ana Luísa; Pereira, Maria João; Carvalho, Susana; Vasconcelos, Marta; Pintado, Maria Manuela
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Artigo de Revista Científica
Publicado em //2014 ENG
Relevância na Pesquisa
36.86%
Fresh-cut commodities shelf-life is limited by minimal processing operations and storage conditions. Wound damage is sensed by sensors/receptors that recognize increased concentrations of endogenous molecules or their fragments, and tissue response involves an increase in respiration rate. Respiration behavior of fresh-cut strawberries is affected by wounding, storage temperature and oxygen availability. Modified atmosphere packaging and refrigerated storage are frequently used to reduce the respiration rate without negatively affecting the physiology of the fruit and to increase shelf life. Mathematical models have been proposed to correlate the respiration rate with different storage parameters such as gas composition and temperature, but the two factors have rarely been considered simultaneously and the systematic approach to modified atmospheres packaging design involves the knowledge of respiration rate kinetics at different temperatures. The objectives of this study were to determine respiration rate of fresh-cut strawberries as a function of oxygen and temperature conditions during storage and to develop and validate mathematical models for predicting respiration rate. Freshly harvested strawberries were processed into wedges and placed in 750 mL glass jars. The glass jars containing fresh-cut strawberries were then flushed with different oxygen concentrations (2.5; 5; 10 and 20% O2) and stored in three different temperatures (0...

Microbial respiration and chemical composition of different sediment fractions in waterbodies of the upper Paraná River floodplain, Brazil

THOMAZ,S. M.; PEREIRA,G.; PAGIORO,T. A.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2001 EN
Relevância na Pesquisa
36.81%
Four size fractions of the sediment of six environments of the upper Paraná River floodplain were analyzed for carbon, nitrogen, and phosphorus contents and microbial respiration (oxygen consumption). Particle size did not affect nitrogen and phosphorus content or microbial activity, but did affect carbon content (F = 4.274, df = 3; 20, p = 0.020). The carbon concentration of ultra-fine particles was significantly lower than that of other sizes of sediment particles. Microbial respiration values were well predicted by sediment chemical composition, as shown by multiple regression (microbial respiration = -0.39 - 0.210C + 0.108N + 0.796P; F = 7.0495, p = 0.0022). However, phosphorus was the element which best explained the microbial respiration (partial coefficient = 0.796, p = 0.0039, n = 23). Considering that i) phosphorus was the best predictor of microbial respiration; ii) phosphorus is trapped in the series of reservoirs located upstream from the section of the floodplain studied; and iii) microbial respiration is a measure of decomposition rates and nutrient cycling, we hypothesize that the long-term accumulation of litter detritus and reduction of nutrient cycling in environments of the upper Paraná River floodplain are probable impacts of this decrease in phosphorus caused by the upstream reservoirs.

Influence of light regimes on respiration, activity of alternative respiratory pathway and carbohydrates content in mature leaves of Ajuga reptans L.

PYSTINA,NATALIA V.; DANILOV,ROMAN A.
Fonte: Sociedade Brasileira de Fisiologia Vegetal Publicador: Sociedade Brasileira de Fisiologia Vegetal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2001 EN
Relevância na Pesquisa
36.87%
Influence of different light regimes (plants grown in shade and in the sun) on respiration, activity of alternative respiratory pathway and carbohydrates content in mature leaves of Ajuga reptans L. was investigated. All experiments were carried out under natural conditions. Sun plants had higher respiration, activity of the alternative pathway and carbohydrates content compared to the shade plants. Additional experiments were performed in order to study effects of darkening as well as evolution of respiration and carbohydrates concentrations in leaves of A. reptans during the day. Darkening led to a decline in total respiration in all types of plants investigated. Activity of the alternative pathway remained unchanged by 20 % in the leaves of the shade plants. On the other hand, darkness led to a twofold decrease in the activity of the alternative pathway in the leaves of the sun plants. Content of soluble carbohydrates in the darkness did not change in the leaves of the shade plants while significantly decreased in the leaves of the sun plants. Total respiration in the mature leaves of the shade plants studied did not change significantly during the day. However, a significant increase in the total respiration was detected in the mature leaves of the sun plants in the evening and in the night. Activity of the alternative respiratory pathway did not change significantly in the leaves of the shade plants during the day and corresponds to ca 20 % of the total respiration. The sun plants examined exhibited significantly higher activity of the alternative pathway during the period of active photosynthesis. In general...

Cheyne-Stokes respiration in patients with congestive heart failure: causes and consequences

Lorenzi-Filho,Geraldo; Genta,Pedro R; Figueiredo,Adelaide C.; Inoue,Daniel
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2005 EN
Relevância na Pesquisa
36.81%
Cheyne-Stokes respiration is a form of periodic breathing in which central apneas and hypopneas alternate with periods of hyperventilation, producing a waxing and waning pattern of tidal volume. This review focuses on the causes and consequences of Cheyne-Stokes respiration in patients with congestive heart failure, in whom the prevalence is strikingly high and ranges from 30% to 50%. Several factors have been implicated in the genesis of Cheyne-Stokes respiration, including low cardiac output and recurrent hypoxia. The key pathophysiological mechanism triggering Cheyne-Stokes respiration is hyperventilation and low arterial CO2 (PaCO2) that when below the apneic threshold triggers a central apnea. Hyperventilation is associated with pulmonary congestion, and Cheyne-Stokes respiration is more prone to occur during sleep, when the respiratory system is mainly dependent on chemical control. It is associated with recurrent dips in oxygen saturation and arousals from sleep, with oscillations in blood pressure and heart rate, sympathetic activation and increased risk of ventricular tachycardia. Cheyne-Stokes respiration is an independent marker of poor prognosis and may participate in a vicious cycle, further stressing the failing heart.

Soil Respiration in a Northeastern US Temperate Forest: A 22-Year Synthesis

Giasson, M.-A.; Ellison, Aaron M.; Bowden, R. D.; Crill, P. M.; Davidson, E. A.; Drake, J. E.; Frey, S. D.; Hadley, J; Lavine, M.; Melillo, J. M.; Munger, J. W.; Nadelhoffer, K. J.; Nicoll, L.; Ollinger, S. V.; Savage, K. E.; Steudler, P. A.; Tang, J.; Va
Fonte: Ecological Society of America Publicador: Ecological Society of America
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.91%
To better understand how forest management, phenology, vegetation type, and actual and simulated climatic change affect seasonal and inter-annual variations in soil respiration (R(_{s})), we analyzed more than 100,000 individual measurements of soil respiration from 23 studies conducted over 22 years at the Harvard Forest in Petersham, Massachusetts, USA. We also used 24 site-years of eddy-covariance measurements from two Harvard Forest sites to examine the relationship between soil and ecosystem respiration (R(_{e})). R(_{s}) was highly variable at all spatial (respiration collar to forest stand) and temporal (minutes to years) scales of measurement. The response of R(_{s}) to experimental manipulations mimicking aspects of global change or aimed at partitioning R(_{s}) into component fluxes ranged from −70% to +52%. The response appears to arise from variations in substrate availability induced by changes in the size of soil C pools and of belowground C fluxes or in environmental conditions. In some cases (e.g., logging, warming), the effect of experimental manipulations on R(_{s}) was transient, but in other cases the time series were not long enough to rule out long-term changes in respiration rates. Inter-annual variations in weather and phenology induced variation among annual R(_{s}) estimates of a magnitude similar to that of other drivers of global change (i.e....

Étude des mécanismes psychophysiologiques de la modulation volontaire de la douleur par le biofeedback et la respiration.

Arsenault, Marianne
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
36.9%
Bien que la douleur soit une expérience subjective universelle, la façon de la percevoir et de l’interpréter est modulée par une multitude de facteurs. Plusieurs interventions cognitives se sont montrées efficaces pour réduire la douleur dans des conditions cliniques et expérimentales. Cette thèse s’intéressera particulièrement aux mécanismes psychophysiologiques impliqués dans les stratégies de modulation volontaire de la douleur. Ces stratégies sont intéressantes puisqu’elles encouragent une prise en charge par l’individu, lui permettant de jouer un rôle actif dans la régulation de sa douleur. La première étude s’intéresse à l’efficacité du biofeedback comme moyen de modulation volontaire de la douleur. Il s’agissait de déterminer si le fait de présenter une rétroaction de l’amplitude du réflex RIII (évoqué par une stimulation électrique du nerf sural) au cours d’un entraînement de plusieurs essais permettrait au participant d’adopter des stratégies de modulation de la douleur et d’activer volontairement des mécanismes de contrôle descendant de la douleur. De façon à évaluer spécifiquement les changements induits par le biofeedback, la modulation du réflexe RIII et de la douleur était comparée dans trois groupes (biofeedback valide...

Respiration rate of zooplankton across oxygen and temperature gradients for individuals raised at high and low quality food

Jeffery, Jonathan C
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
36.86%
Daphnia pulicaria travel through strong environmental gradients during vertical migration. Predation pressure and abiotic conditions will influence the physiological performance and behavior of D. pulicaria according to depth. Regardless of environmental condition, individuals must meet the basic metabolic requirements of maintenance processes in order to survive. Energy available for maintenance is directly affected by the quality of food available, whereas the physiological capacity to supply energy for maintenance processes is influenced by abiotic factors such as temperature and oxygen. Maintenance processes are supplied by anaerobic and aerobic metabolism whose activities are directly related to oxygen consumption. In this study we investigate how D. pulicaria respiration rates are influenced by strong environmental gradients in oxygen and temperature for individuals raised at high and low food quality. We expected that temperature would increase respiration rates and that temperature would improve an individual’s hypoxic tolerance for high and low food quality individuals. We measured respiration rates of individual D. pulicaria in a micro-respiration chamber designed from scratch to assess the rate of metabolic processes associated with maintenance. D. pulicaria respiration rates were constant until very low oxygen concentrations when they would change abruptly...

Partitioning of soil respiration in a beech forest using a trenching experiment.

Brosnan, Stephanie
Fonte: University of Limerick Publicador: University of Limerick
Tipo: Master thesis (Research); all_ul_research; ul_published_reviewed; ul_theses_dissertations; none
ENG
Relevância na Pesquisa
36.89%
peer-reviewed; Total soil respiration (RTOT) has two components; heterotrophic (RH) and autotrophic (RA) respiration. We aim to partition the components of RTOT in a beech (Fagus sylvatica L.) forest using a trenching experiment. The study plots were set up in December 2009. Four plots were surrounded by trenches and four other plots were left untrenched. Measurements of CO2 were measured using a closed system chamber attached to a portable infrared gas analyser. Soil temperature and soil moisture content at 5 cm depth were also measured at each plot. Total soil respiration was measured in untrenched plots and RH in plots that were trenched. Soil respiration showed a clear seasonal trend with high levels recorded during the summer and low levels in winter and early spring. Total soil respiration and RH were related individually to soil temperature using exponential relationships and the relationship with soil moisture content was described using a peak relationship, these were found to be key factors affecting soil respiration. The Q10 value for total soil respiration was calculated to be 1.7 and Q10 value of 1.5 was calculated for heterotrophic respiration. A sudden increase in soil moisture after a dry period led to high CO2 levels. There was significant difference found between soil respiration rates in the untrenched and trenched plots (p < 0.05)...

Investigation of respiration of individual bovine embryos produced in vivo and in vitro and correlation with viability following transfer

Sousa Lopes, Ana Sofia Jordao De; Madsen, S. E.; Ramsing, N. B.; Lovendahl, P.; Greve, T.; Callesen, H.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
36.83%
BACKGROUND: Quantification of oxygen consumption by individual preimplantation embryos has the potential to improve embryo selection. This study investigated whether respiration rates of individual embryos are useful indicators of embryo viability. The effect of the Nanorespirometer on embryo viability was also evaluated. METHODS: The respiration rates of individual day 7 bovine in vivo- (n = 44) and in vitro-produced (n = 156) embryos were measured using the Nanorespirometer. In vivo-produced embryos were individually transferred to recipients. RESULTS: The respiration rates of in vivo-produced embryos increased with increasing morphological quality and stage of development (P < 0.05). Pregnancy rates on days 35 and 60 were 65 and 60%, respectively. The mean respiration rate did not differ significantly between embryos producing and not producing a pregnancy, but the transfer of embryos with respiration rates <0.78 nl/h, between 0.78 and 1.10 nl/h, and >1.10 nl/h resulted in 48, 100 and 25% pregnancy rate, respectively. The mean respiration rate of in vitro-produced embryos was higher than that of in vivo-produced embryos because of differences in the morphological quality and stage of development. CONCLUSION: The Nanorespirometer does not adversely influence embryo viability...

Growth, nutrition, and soil respiration of a mycorrhiza-defective tomato mutant and its mycorrhizal wild-type progenitor

Cavagnaro, T.; Langley, A.; Jackson, L.; Smukler, S.; Koch, G.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
36.86%
The effects of colonisation of roots by arbuscular mycorrhizal fungi (AMF) on soil respiration, plant growth, nutrition, and soil microbial communities were assessed using a mycorrhiza-defective tomato (Solanum lycopersicum L.) mutant and its mycorrhizal wild-type progenitor. Plants were grown in rhizocosms in an automated respiration monitoring system over the course of the experiment (79 days). Soil respiration was similar in the two tomato genotypes, and between P treatments with plants. Mycorrhizal colonisation increased P and Zn content and decreased root biomass, but did not affect aboveground plant biomass. Soil microbial biomass C and soil microbial communities based on phospholipid fatty acid (PLFA) analysis were similar across all treatments, suggesting that the two genotypes differed little in their effect on soil activity. Although approximately similar amounts of C may have been expended belowground in both genotypes, they may have differed in the relative C allocation to root construction v. respiration. Further, net soil respiration did not differ between the two tomato genotypes, but root dry weight was lower in mycorrhizal roots, and respiration of mycorrhizal roots per unit dry weight was higher than nonmycorrhizal roots. This indicates that the AM contribution to soil respiration may indeed be significant...

Previous water content influences the response of soil respiration to changes in water content in non-saline and saline soils

Yan, N.; Marschner, P.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.83%
Three incubation experiments were carried out with a non-saline soil (electrical conductivity in a saturation paste (ECe) 1 dS m−1) to which NaCl was added to achieve ECe 10 and 30 dS m−1; pea straw was added at 20 g kg−1 as a nutrient source. Experiment 1 showed that cumulative respiration was highest in soil EC 1 and lowest in soil EC 30. The optimal water content for respiration was 60–70 % of WHC in all soils. There were two periods (days 1–7 and days 8–17) in Experiment 2. In the treatments with the same water content in both periods [optimal (O-O) and medium (M-M)], respiration rates decreased over time and were lower in M-M than in O-O. Cumulative respiration at medium water content did not differ between slow (L-SM) or rapid rewetting (L-RM) from low to medium water content. There were two periods in Experiment 3 with the water content in the first period 50, 40 or 30 % of WHC adjusted from 60 % during pre-incubation either slowly or rapidly. The water content in the second period was maintained or adjusted slowly to 30–60 %. Cumulative respiration differed between water contents but was not consistently different between rapid and slow drying in the first period. We conclude that the response of microbial activity to a certain water content is influenced by the previous water content whereas the speed at which the water content is adjusted had little effect on respiration at target water content.; Nan Yan...

The effect of residue mixing, clay content and drying and rewetting on soil respiration and microbial biomass.

Shi, Andong
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015
Relevância na Pesquisa
37.03%
Organic matter decomposition in terrestrial system is of vital importance for nutrient cycling and ecosystem function. Soil microorganisms are the key drivers of decomposition which regulates the availability of inorganic nutrients through immobilisation and mineralisation. The size of the soil organic C pool is twice that of C in the atmosphere and more than twice of that in vegetation. Thus, organic matter decomposition in soil greatly influences the C flux between soil and the atmosphere. Therefore understanding factors influencing organic matter decomposition is important for climate change mitigation and soil fertility. In this thesis, the effects of residue mixing, removal of water-extractable organic C, clay subsoil addition to sandy soil and drying and rewetting on decomposition were investigated. Organic matter decomposition is influenced by both internal and environmental factors. Plant residues are an important source of soil organic C and decomposition of plant residues has been studied extensively. However, residues from different species or above- and below-ground residues are often mixed and less is known about factors influencing decomposition of residue mixtures. Shoot and root residues of three Australian native perennial grass species [Wallaby grass (Danthonia sp); Stipa sp and Kangaroo grass (Themeda triandra)] and barley (Hordeum vulgare L.) were mixed to create nine different residue mixtures (1:1 mixture). Soil respiration was measured over 18 days. Cumulative respiration in residue mixtures differed from the expected value (average of cumulative respiration of individual residues) in most cases with synergistic interactions occurring in 56 % of the mixtures (expected < measured value)...

Soil respiration fluxes and controlling factors in temperate forest and cropland ecosystems; Bodenatmungsflüsse und deren beeinflussende Faktoren in temperaten Wäldern und Agrarökosysteme

Moyano, Fernando
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
37%
Soils are main components of natural ecosystems, central for the growth of plants and the recycling of organic matter through the activity of microorganisms and soil fauna. As such, they exert a large influence on the cycling of carbon between different reservoirs, storing more carbon at the global scale than either the atmosphere or the live vegetation. The flux of carbon between different global reservoirs is being actively studied in the present largely as a result of its implications for climate change but also in an effort to understand the functioning of ecosystems and living organisms. The flux of carbon dioxide from soils to the atmosphere, also termed soil respiration, is the result of belowground plant activity combined with the decomposition of soil organic matter. To understand this flux it is necessary to study the factors driving the activity of roots as well as the dynamics of soil microorganisms and their use of soil organic matter or root-derived carbon. Tightly related to biological processes are physical and chemical conditions in soils which determine the availability of carbon compounds to microbes. This study was carried out in agricultural, broad-leaf forest and needle-leaf forest temperate ecosystems with the objective of studying the effect of vegetation and soil factors on root...

24-h variation in soil respiration after a long dry season in a Sudano-Sahelian region

Yemadje,Pierrot Lionel; Guibert,Hervé; Blavet,Didier; Olina,Jean-Paul; Chevallier,Tiphaine; Deleporte,Philippe; Bernoux,Martial
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2015 EN
Relevância na Pesquisa
36.83%
Soil respiration is a major component of the global carbon cycle which links ecosystems and the atmosphere. To evaluate the reaction of soil respiration after wetting, during a dry period, soil respiration and associated environmental factors were measured over a 24-h period, during the dry season in North Cameroon after wetting the soil. Over 24-h, soil respiration rates followed a quadratic curve during the day coming close to linear at night, while soil temperature and moisture together explained at least 73 % of the variations during the 24-h observed. These soil respiration rates increased during the morning, peaked between 11h00 and 13h00 and then decreased gradually to the minimum around 06h00. These observations were used to propose a method for estimating mean daytime and nighttime soil respiration after wetting the soil. The method proposed in this study has the advantage of being based on a small number of measurements and is, therefore, easier to implement for monitoring 24-h soil respiration after the first rains following a long dry period.

The number of moist days determines respiration in drying and rewetting cycles

Shi, A.; Marschner, P.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
36.91%
The respiration flush upon rapid rewetting of dry soil has been studied extensively, but with inconsistent differences in cumulative respiration between drying and rewetting (DRW) treatments and the constantly moist (CM) control. Therefore, factors influencing respiration in DRW require further research. Three incubation experiments were carried out to assess the relationship between cumulative respiration and the number of moist or dry days in two soils of similar texture but different long-term management: permanent pasture and wheat-fallow soil with organic C content of 39 and 19 g kg⁻¹. In the first experiment, the CM and DRW treatments had the same total length (10 days) with different proportions of moist and dry days in the DRW treatments. The second and third experiment had DRW cycles in which dry and moist periods were of equal length with one cycle in experiment 2 and two cycles in experiment 3. Total cumulative respiration per gram TOC was greater in wheat than in pasture soil. Total cumulative respiration in DRW treatments was lower than in CM except when the moist period was more than 50% of the total length in pasture soil in experiment 1. In the first experiment, cumulative respiration in the dry period was not influenced by the number of dry days...

Respiration rates of worker honeybees of different ages and at different temperatures

Allen, M. Delia
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
EN; ENGLISH
Relevância na Pesquisa
36.81%
1. The respiration rates of individual adult worker bees confined in small gauze cages were determined over a range of temperatures between 7 and 46° C. The respiration rates usually remained constant over a period of 1 hr., although at 7, 12° C., and possibly at 17° C. there were indications of a decrease with time, and at 42 and 46° C. indications of an increase with time. Fluctuations which would have reflected variable activity during any of the experiments were rare. 2. At each temperature studied the respiration rates increased progressively from the youngest adults (newly emerged) to the oldest measured (24-33 days). The increase was particularly marked during the first few days of adult life. 3. The respiration rates of newly emerged and 18 hr. old adults increased progressively between 7 and 46° C., but 4-33-day-old bees showed two peaks (at 17 and 46° C.) with a depression having a minimum value at 32° C. lying between. 2-day-old bees had similar peaks at 22 and 46° C. 4. It is suggested that the first peak in the respiration rate of the older bees occurred at the lowest temperature at which free movements were possible, and that it indicated an increased body temperature maintained by the bees to combat the effects of the low environmental temperature. The lack of this first peak in the case of the youngest bees is thought to mean that they were unable to raise their temperature above that of the environment. The information obtainable from the literature supported these conclusions; their implications in relation to the regulation of temperature within the colony are discussed. 5. Numerical values for the oxygen consumptions of adult bees are discussed in relation to those found by other workers.

A Multisite Study of Initial Respiration Rate and Heart Rate as Predictors of Posttraumatic Stress Disorder

Bryant, R.; Creamer, M.; O'Donnell, M.; Silove, D.; McFarlane, A.
Fonte: Physicians Postgraduate Press Publicador: Physicians Postgraduate Press
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
36.81%
OBJECTIVE: Fear-conditioning models posit that increased arousal at the time of trauma predicts subsequent posttraumatic stress disorder (PTSD). This multisite study evaluated the extent to which acute heart rate and respiration rate predict subsequent chronic PTSD. METHOD: Traumatically injured patients admitted to 4 hospitals across Australia between April 2004 and February 2006 were initially assessed during hospital admission (N = 1105) and were reassessed 3 months later for PTSD by using the Clinician-Administered PTSD Scale-IV and for major depressive disorder (MDD) by using the Mini-International Neuropsychiatric Interview (English version 5.0.0) (N = 955). Heart rate, respiration rate, and blood pressure were assessed on the initial day of traumatic injury. RESULTS: Ninety patients (10%) met criteria for PTSD and 159 patients (17%) met criteria for MDD at the 3-month assessment. Patients with PTSD compared to those without PTSD had higher heart rate (90.16 +/- 18.66 vs. 84.84 +/-17.41, t = 2.74, p < .01) and respiration rate (20.24 +/- 5.16 vs. 18.58 +/- 4.29, t = 3.43, p < .001) immediately after injury. There were no heart rate or respiration rate differences between patients who did and did not develop MDD. Patients were more likely to develop PTSD at 3 months if they had a heart rate of at least 96 beats per minute (15% vs. 8%...

The hot and the cold: unravelling the variable response of plant respiration to temperature

Atkin, Owen Kenneth; Bruhn, Dan; Hurry, Vaughan; Tjoelker, Mark G
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.87%
When predicting the effects of climate change, global carbon circulation models that include a positive feedback effect of climate warming on the carbon cycle often assume that (1) plant respiration increases exponentially with temperature (with a constant Q10) and (2) that there is no acclimation of respiration to long-term changes in temperature. In this review, we show that these two assumptions are incorrect. While Q10 does not respond systematically to elevated atmospheric CO2 concentrations, other factors such as temperature, light, and water availability all have the potential to influence the temperature sensitivity of respiratory CO2 efflux. Roots and leaves can also differ in their Q10 values, as can upper and lower canopy leaves. The consequences of such variable Q10 values need to be fully explored in carbon modelling. Here, we consider the extent of variability in the degree of thermal acclimation of respiration, and discuss in detail the biochemical mechanisms underpinning this variability; the response of respiration to long-term changes in temperature is highly dependent on the effect of temperature on plant development, and on interactive effects of temperature and other abiotic factors (e.g. irradiance, drought and nutrient availability). Rather than acclimating to the daily mean temperature...

Acclimation of snow gum (Eucalyptus pauciflora) leaf respiration to seasonal and diurnal variations in temperature: the importance of changes in the capacity and temperature sensitivity of respiration

Holly, Chris; Atkin, Owen; Ball, Marilyn
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.89%
We investigated the relationship between daily and seasonal temperature variation and dark respiratory CO2 release by leaves of snow gum (Eucalyptus pauciflora Sieb. ex Spreng) that were grown in their natural habitat or under controlled-environment conditions. The open grassland field site in SE Australia was characterized by large seasonal and diurnal changes in air temperature. On each measurement day, leaf respiration rates in darkness were measured in situ at 2-3 h intervals over a 24 h period, with measurements being conducted at the ambient leaf temperature. The rate of respiration at a set measuring temperature (i.e. apparent 'respiratory capacity') was greater in seedlings grown under low average daily temperatures (i.e. acclimation occurred), both in the field and under controlled-environment conditions. The sensitivity of leaf respiration to diurnal changes in temperature (i.e. the Q10 of leaf respiration) exhibited little seasonal variation over much of the year. However. Q10 values were significantly greater on cold winter days (i.e. when daily average and minimum air temperatures were below 6°and -1 °C, respectively). These differences in Q10 values were not due to bias arizing from the contrasting daily temperature amplitudes in winter and summer...