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Sample records for dark respiration rate

  1. Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

    KAUST Repository

    Mesa, Elena; Delgado-Huertas, Antonio; Carrillo-de-Albornoz, Paloma; Garcí a-Corral, Lara S.; Sanz-Martí n, Marina; Wassmann, Paul; Reigstad, Marit; Sejr, Mikael; Dalsgaard, Tage; Duarte, Carlos M.

    2017-01-01

    Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton

  2. Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

    KAUST Repository

    Mesa, Elena

    2017-04-21

    Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring and summer. Here we demonstrate that plankton community respiration evaluated under the continuous daylight conditions present in situ, tends to be higher than that evaluated in the dark. The ratio between community respiration measured in the light (Rlight) and in the dark (Rdark) increased as the 2/3 power of Rlight so that the Rlight:Rdark ratio increased from an average value of 1.37 at the median Rlight measured here (3.62 µmol O2 L-1 d-1) to an average value of 17.56 at the highest Rlight measured here (15.8 µmol O2 L-1 d-1). The role of respiratory processes as a source of CO2 in the Arctic has, therefore, been underestimated and is far more important than previously believed, particularly in the late spring, with 24 h photoperiods, when community respiration rates are highest.

  3. Estimating Canopy Dark Respiration for Crop Models

    Science.gov (United States)

    Monje Mejia, Oscar Alberto

    2014-01-01

    Crop production is obtained from accurate estimates of daily carbon gain.Canopy gross photosynthesis (Pgross) can be estimated from biochemical models of photosynthesis using sun and shaded leaf portions and the amount of intercepted photosyntheticallyactive radiation (PAR).In turn, canopy daily net carbon gain can be estimated from canopy daily gross photosynthesis when canopy dark respiration (Rd) is known.

  4. Response of needle dark respiration of Pinus koraiensis and Pinus sylvestriformis to elevated CO2 concentrations for four growing seasons' exposure

    Institute of Scientific and Technical Information of China (English)

    ZHOU YuMei; HAN ShiJie; ZHANG HaiSen; XIN LiHua; ZHENG JunQiang

    2007-01-01

    The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous species-Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. Koraiensis and P. Sylvestriformis were exposed to 700,500μmol·mol-1 CO2 and ambient CO2(approx.350 μmol·mol-1)for four growing seasons. Needle dark respiration was measurd during the second, third and fourth growing seasons' exposure to elevated CO2.The results showed that needle dark respiration rate increased for P. Koraiensis and P. Sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. Koraiensis was stimulated and that of P. Sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. Koraiensis and P. Sylvestriformis during the fourth growing season. There was consistent trend between the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. Sylvestriformis during the third growing season by changing measurement CO2 concentrations. However, the short-term effect was different from the long-term effect for P. Koraiensis. Response of dark respiration of P. Koraiensis and P. Sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.

  5. Effects of low concentrations of sulfur dioxide on net photosynthesis and dark respiration of Vicia faba

    Energy Technology Data Exchange (ETDEWEB)

    Black, V J; Unsworth, M H

    1979-01-01

    Rates of net photosynthesis, P/sub N/, and dark respiration of Vicia faba plants were measured in the laboratory in clean air and in air containing up to 175 parts 10/sup -9/ (500 ..mu..g m/sup -3/) SO/sub 2/. At all SO/sub 2/ concentrations exceeding 35 parts 10/sup -9/, P/sub N/ was inhibited compared with clean air. At light saturation, the magnitude of inhibition depended on SO/sub 2/ concentration but at low irradiances the inhibition was independent of concentration. Dark respiration rates increased substantially, independent of concentration. When exposures continued for up to 3 days, P/sub N/ returned to clean air values about 1 h after fumigation ceased: dark respiration recovered after one photoperiod. There were no visible injuries. Reviewing possible mechanisms responsible for the inhibition of P/sub N/, it is suggested that SO/sub 2/ competes with CO/sub 2/ for binding sites in RuBP carboxylase. Analysis of resistance analogues demonstrates that SO/sub 2/ altered both stomatal and internal (residual) resistances. A model of crop photosynthesis shows the implications of the observed responses for the growth of field crops in which plants are assumed to respond like laboratory plants. Photosynthesis of the crop would be less sensitive than that of individual plants to SO/sub 2/ concentration. Daily dry matter accumulation of hypothetical polluted crops would be substantially less than clean air values but would vary relatively little with SO/sub 2/ concentration. It is concluded that physiological bases exist to account for observed reductions in growth of plants at very low SO/sub 2/ concentrations, and that thresholds for plant responses to SO/sub 2/ require reassessment. 30 references, 5 figures, 1 table.

  6. What controls respiration rate in stored sugarbeet roots

    Science.gov (United States)

    Although respiration is estimated to be responsible for 60 to 80% of the sucrose lost during storage, the mechanisms by which sugarbeet roots regulate their respiration rate are unknown. In plants, respiration rate is regulated by (1) available respiratory capacity, (2) cellular energy status, (3) ...

  7. Redefinition and global estimation of basal ecosystem respiration rate

    DEFF Research Database (Denmark)

    Yuan, Wenping; Luo, Yiqi; Li, Xianglan

    2011-01-01

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models sti...

  8. Diatoms respire nitrate to survive dark and anoxic conditions

    DEFF Research Database (Denmark)

    Kamp, Anja; de Beer, Dirk; Nitsch, Jana L.

    2011-01-01

    +, indicating dissimilatory nitrate reduction to ammo- nium (DNRA). DNRA is an anaerobic respiration process that is known mainly from prokaryotic organisms, and here shown as dis- similatory nitrate reduction pathway used by a eukaryotic photo- troph. Similar to large sulfur bacteria and benthic foraminifera...

  9. Response of needle dark respiration of Pinus koraiensis and Pinus sylvestriformis to elevated CO2 concentra-tions for four growing seasons’ exposure

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous spe- cies—Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. koraiensis and P. sylvestriformis were exposed to 700, 500 μmol·mol-1 CO2 and ambient CO2 (approx. 350 μmol·mol-1) for four growing seasons. Needle dark respiration was meas- ured during the second, third and fourth growing seasons’ exposure to elevated CO2. The results showed that needle dark respiration rate increased for P. koraiensis and P. sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. koraiensis was stimu- lated and that of P. sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. koraiensis and P. sylvestriformis during the fourth growing season. There was consistent trend be- tween the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. sylvestriformis during the third growing season by changing measurement CO2 concentrations. How- ever, the short-term effect was different from the long-term effect for P. koraiensis. Response of dark respiration of P. koraiensis and P. sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.

  10. Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

    Science.gov (United States)

    Wang, X; Lewis, J D; Tissue, D T; Seemann, J R; Griffin, K L

    2001-02-27

    Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants.

  11. Redefinition and global estimation of basal ecosystem respiration rate

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Wenping [College of Global Change and Earth System Science, Beijing Normal University, Beijing, China; Luo, Yiqi [Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, USA; Li, Xianglan [College of Global Change and Earth System Science, Beijing Normal University, Beijing, China; Liu, Shuguang; Yu, Guirui [Key Laboratory of Ecosystem Network Observation and Modeling, Synthesis Research Center of Chinese Ecosystem Research Network, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; Zhou, Tao [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Bahn, Michael [Institute of Ecology, University of Innsbruck, Innsbruck, Austria; Black, Andy [Faculty of Land and Food Systems, University of British Columbia, Vancouver, B. C., Canada; Desai, Ankur R. [Atmospheric and Oceanic Sciences Department, Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, Wisconsin, USA; Cescatti, Alessandro [Institute for Environment and Sustainability, Joint Research Centre, European Commission, Ispra, Italy; Marcolla, Barbara [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Jacobs, Cor [Alterra, Earth System Science-Climate Change, Wageningen University, Wageningen, Netherlands; Chen, Jiquan [Department of Earth, Ecological, and Environmental Sciences, University of Toledo, Toledo, Ohio, USA; Aurela, Mika [Climate and Global Change Research, Finnish Meteorological Institute, Helsinki, Finland; Bernhofer, Christian [Chair of Meteorology, Institute of Hydrology and Meteorology, Technische Universität Dresden, Dresden, Germany; Gielen, Bert [Department of Biology, University of Antwerp, Wilrijk, Belgium; Bohrer, Gil [Department of Civil, Environmental, and Geodetic Engineering, Ohio State University, Columbus, Ohio, USA; Cook, David R. [Climate Research Section, Environmental Science Division, Argonne National Laboratory, Argonne, Illinois, USA; Dragoni, Danilo [Department of Geography, Indiana University, Bloomington, Indiana, USA; Dunn, Allison L. [Department of Physical and Earth Sciences, Worcester State College, Worcester, Massachusetts, USA; Gianelle, Damiano [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Grünwald, Thomas [Chair of Meteorology, Institute of Hydrology and Meteorology, Technische Universität Dresden, Dresden, Germany; Ibrom, Andreas [Risø DTU National Laboratory for Sustainable Energy, Biosystems Division, Technical University of Denmark, Roskilde, Denmark; Leclerc, Monique Y. [Department of Crop and Soil Sciences, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, Georgia, USA; Lindroth, Anders [Geobiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Lund, Sweden; Liu, Heping [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, Washington, USA; Marchesini, Luca Belelli [Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Viterbo, Italy; Montagnani, Leonardo; Pita, Gabriel [Department of Mechanical Engineering, Instituto Superior Técnico, Lisbon, Portugal; Rodeghiero, Mirco [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Rodrigues, Abel [Unidade de Silvicultura e Produtos Florestais, Instituto Nacional dos Recursos Biológicos, Oeiras, Portugal; Starr, Gregory [Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA; Stoy, Paul C. [Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana, USA

    2011-10-13

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still use a global constant BR largely due to the lack of a functional description for BR. In this study, we redefined BR to be ecosystem respiration rate at the mean annual temperature. To test the validity of this concept, we conducted a synthesis analysis using 276 site-years of eddy covariance data, from 79 research sites located at latitudes ranging from ~3°S to ~70°N. Results showed that mean annual ER rate closely matches ER rate at mean annual temperature. Incorporation of site-specific BR into global ER model substantially improved simulated ER compared to an invariant BR at all sites. These results confirm that ER at the mean annual

  12. The Arabidopsis thaliana natriuretic peptide AtPNP-A is a systemic regulator of leaf dark respiration and signals via the phloem

    KAUST Repository

    Ruzvidzo, Oziniel; Donaldson, Lara Elizabeth; Valentine, Alex J.; Gehring, Christoph A

    2011-01-01

    -molar concentrations. Here we show that a recombinant Arabidopsis thaliana PNP (AtPNP-A) rapidly increased the rate of dark respiration in treated leaves after 5 min. In addition, we observed increases in lower leaves, and with a lag time of 10 min, the effect spread

  13. Two Proximal Skin Electrodes — A Respiration Rate Body Sensor

    Directory of Open Access Journals (Sweden)

    Viktor Avbelj

    2012-10-01

    Full Text Available We propose a new body sensor for extracting the respiration rate based on the amplitude changes in the body surface potential differences between two proximal body electrodes. The sensor could be designed as a plaster-like reusable unit that can be easily fixed onto the surface of the body. It could be equipped either with a sufficiently large memory for storing the measured data or with a low-power radio system that can transmit the measured data to a gateway for further processing. We explore the influence of the sensor’s position on the quality of the extracted results using multi-channel ECG measurements and considering all the pairs of two neighboring electrodes as potential respiration-rate sensors. The analysis of the clinical measurements, which also include reference thermistor-based respiration signals, shows that the proposed approach is a viable option for monitoring the respiration frequency and for a rough classification of breathing types. The obtained results were evaluated on a wireless prototype of a respiration body sensor. We indicate the best positions for the respiration body sensor and prove that a single sensor for body surface potential difference on proximal skin electrodes can be used for combined measurements of respiratory and cardiac activities.

  14. Redefinition and global estimation of basal ecosystem respiration rate

    Science.gov (United States)

    Yuan, W.; Luo, Y.; Li, X.; Liu, S.; Yu, G.; Zhou, T.; Bahn, M.; Black, A.; Desai, A.R.; Cescatti, A.; Marcolla, B.; Jacobs, C.; Chen, J.; Aurela, M.; Bernhofer, C.; Gielen, B.; Bohrer, G.; Cook, D.R.; Dragoni, D.; Dunn, A.L.; Gianelle, D.; Grnwald, T.; Ibrom, A.; Leclerc, M.Y.; Lindroth, A.; Liu, H.; Marchesini, L.B.; Montagnani, L.; Pita, G.; Rodeghiero, M.; Rodrigues, A.; Starr, G.; Stoy, Paul C.

    2011-01-01

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still use a global constant BR largely due to the lack of a functional description for BR. In this study, we redefined BR to be ecosystem respiration rate at the mean annual temperature. To test the validity of this concept, we conducted a synthesis analysis using 276 site-years of eddy covariance data, from 79 research sites located at latitudes ranging from ∼3°S to ∼70°N. Results showed that mean annual ER rate closely matches ER rate at mean annual temperature. Incorporation of site-specific BR into global ER model substantially improved simulated ER compared to an invariant BR at all sites. These results confirm that ER at the mean annual temperature can be considered as BR in empirical models. A strong correlation was found between the mean annual ER and mean annual gross primary production (GPP). Consequently, GPP, which is typically more accurately modeled, can be used to estimate BR. A light use efficiency GPP model (i.e., EC-LUE) was applied to estimate global GPP, BR and ER with input data from MERRA (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate resolution Imaging Spectroradiometer). The global ER was 103 Pg C yr −1, with the highest respiration rate over tropical forests and the lowest value in dry and high-latitude areas.

  15. Variety of DNA Replication Activity Among Cyanobacteria Correlates with Distinct Respiration Activity in the Dark.

    Science.gov (United States)

    Ohbayashi, Ryudo; Yamamoto, Jun-Ya; Watanabe, Satoru; Kanesaki, Yu; Chibazakura, Taku; Miyagishima, Shin-Ya; Yoshikawa, Hirofumi

    2017-02-01

    Cyanobacteria exhibit light-dependent cell growth since most of their cellular energy is obtained by photosynthesis. In Synechococcus elongatus PCC 7942, one of the model cyanobacteria, DNA replication depends on photosynthetic electron transport. However, the critical signal for the regulatory mechanism of DNA replication has not been identified. In addition, conservation of this regulatory mechanism has not been investigated among cyanobacteria. To understand this regulatory signal and its dependence on light, we examined the regulation of DNA replication under both light and dark conditions among three model cyanobacteria, S. elongatus PCC 7942, Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120. Interestingly, DNA replication activity in Synechocystis and Anabaena was retained when cells were transferred to the dark, although it was drastically decreased in S. elongatus. Glycogen metabolism and respiration were higher in Synechocystis and Anabaena than in S. elongatus in the dark. Moreover, DNA replication activity in Synechocystis and Anabaena was reduced to the same level as that in S. elongatus by inhibition of respiratory electron transport after transfer to the dark. These results demonstrate that there is disparity in DNA replication occurring in the dark among cyanobacteria, which is caused by the difference in activity of respiratory electron transport. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  16. Aquatic respiration rate measurements at low oxygen concentrations.

    Directory of Open Access Journals (Sweden)

    Moritz Holtappels

    Full Text Available Despite its huge ecological importance, microbial oxygen respiration in pelagic waters is little studied, primarily due to methodological difficulties. Respiration measurements are challenging because of the required high resolution of oxygen concentration measurements. Recent improvements in oxygen sensing techniques bear great potential to overcome these limitations. Here we compare 3 different methods to measure oxygen consumption rates at low oxygen concentrations, utilizing amperometric Clark type sensors (STOX, optical sensors (optodes, and mass spectrometry in combination with (18-18O2 labeling. Oxygen concentrations and consumption rates agreed well between the different methods when applied in the same experimental setting. Oxygen consumption rates between 30 and 400 nmol L(-1 h(-1 were measured with high precision and relative standard errors of less than 3%. Rate detection limits in the range of 1 nmol L(-1 h(-1 were suitable for rate determinations in open ocean water and were lowest at the lowest applied O2 concentration.

  17. Variations in dark respiration and mitochondrial numbers within needles of Pinus radiata grown in ambient or elevated CO2 partial pressure

    International Nuclear Information System (INIS)

    Griffin, K. L.; Anderson, O. R.; Tissue, D. T.; Turnbull, M. H.; Whitehead, D.

    2004-01-01

    An experiment involving comparison of within-leaf variations in cell size, mitochondrial numbers and dark respiration in the most recently expanded tip, the mid-section and the base of needles of Pinus radiata grown for four years at ambient and elevated carbon dioxide partial pressure, is described. Results showed variation in mitochondrial numbers and respiration along the length of the needle, with the highest number of mitochondria per unit cytoplasm and the highest rate of respiration per unit leaf area at the base of the needle. Elevated carbon dioxide pressure caused the number of mitochondria per unit cytoplasm to double regardless of location (tip, basal or mid sections). Under these conditions, greatest mitochondrial density was observed at the tip. The mean size of mitochondria was not affected by either growth at elevated carbon dioxide pressure or by position on the needle. Respiration per unit leaf area at elevated carbon dioxide pressure was highest at the tip of needles, decreasing towards the middle and basal sections. The observed data supports the hypothesis that the highest number of mitochondria per unit area of cytoplasm occurs at the base of the needle, but does not support the hypothesis that the lowest rate of respiration also occurs at the base. It is suggested that the relationship that determines the association between structure and function in these needles is more complex than previously thought. 33 refs., 4 tabs., 1 fig

  18. Accuracy of acoustic respiration rate monitoring in pediatric patients.

    Science.gov (United States)

    Patino, Mario; Redford, Daniel T; Quigley, Thomas W; Mahmoud, Mohamed; Kurth, C Dean; Szmuk, Peter

    2013-12-01

    Rainbow acoustic monitoring (RRa) utilizes acoustic technology to continuously and noninvasively determine respiratory rate from an adhesive sensor located on the neck. We sought to validate the accuracy of RRa, by comparing it to capnography, impedance pneumography, and to a reference method of counting breaths in postsurgical children. Continuous respiration rate data were recorded from RRa and capnography. In a subset of patients, intermittent respiration rate from thoracic impedance pneumography was also recorded. The reference method, counted respiratory rate by the retrospective analysis of the RRa, and capnographic waveforms while listening to recorded breath sounds were used to compare respiration rate of both capnography and RRa. Bias, precision, and limits of agreement of RRa compared with capnography and RRa and capnography compared with the reference method were calculated. Tolerance and reliability to the acoustic sensor and nasal cannula were also assessed. Thirty-nine of 40 patients (97.5%) demonstrated good tolerance of the acoustic sensor, whereas 25 of 40 patients (62.5%) demonstrated good tolerance of the nasal cannula. Intermittent thoracic impedance produced erroneous respiratory rates (>50 b·min(-1) from the other methods) on 47% of occasions. The bias ± SD and limits of agreement were -0.30 ± 3.5 b·min(-1) and -7.3 to 6.6 b·min(-1) for RRa compared with capnography; -0.1 ± 2.5 b·min(-1) and -5.0 to 5.0 b·min(-1) for RRa compared with the reference method; and 0.2 ± 3.4 b·min(-1) and -6.8 to 6.7 b·min(-1) for capnography compared with the reference method. When compared to nasal capnography, RRa showed good agreement and similar accuracy and precision but was better tolerated in postsurgical pediatric patients. © 2013 John Wiley & Sons Ltd.

  19. Can we relate respiration rates of bark and wood with tissue nitrogen concentrations and branch-level CO2 fluxes across woody species?

    Science.gov (United States)

    Eller, A. S.; Wright, I.; Cernusak, L. A.

    2013-12-01

    Respiration from above-ground woody tissue is generally responsible for 5-15% of ecosystem respiration (~ 30% of total above-ground respiration). The CO2 respired by branches comes from both the sapwood and the living layers within the bark, but because there is considerable movement of respired CO2 within woody tissues (e.g. in the transpiration stream), and because the bark can present a considerable barrier to CO2 diffusion, it can be difficult to interpret measured CO2 efflux from intact branches in relation to the respiration rates of the component tissues, and to relative mass allocation to each. In this study we investigated these issues in 15 evergreen tree and shrub species native to the Sydney area in eastern Australia. We measured CO2 efflux and light-dependent refixation of respired CO2 in photosynthetic bark from the exterior surfaces of branches (0.5-1.5 cm in diameter), and measured the tissue-specific respiration rates of the bark and wood from those same branches. We also measured the nitrogen content and tissue density of the wood and bark to determine: 1) Among species, what is the relationship between %N and tissue respiration? 2) How is photosynthetic refixation of CO2 related to respiration and %N in the bark and underlying wood? and 3) What is the relationship between branch CO2 efflux and the respiration rates of the underlying wood and bark that make up the branch? Across the 15 species %N was a better predictor of respiration in wood than in bark. CO2 efflux measured from the exterior of the stem in the dark was positively correlated with photosynthetic refixation and explained ~40% of the variation in rates of refixation. Refixation rates were not strongly related to bark or wood %N. Differences among species in CO2 efflux rates were not well explained by differences in bark or wood %N and there was a stronger relationship between bark respiration and CO2 efflux than between wood respiration and CO2 efflux. These results suggest that the

  20. Δ14CO2 from dark respiration in plants and its impact on the estimation of atmospheric fossil fuel CO2.

    Science.gov (United States)

    Xiong, Xiaohu; Zhou, Weijian; Cheng, Peng; Wu, Shugang; Niu, Zhenchuan; Du, Hua; Lu, Xuefeng; Fu, Yunchong; Burr, George S

    2017-04-01

    Radiocarbon ( 14 C) has been widely used for quantification of fossil fuel CO 2 (CO 2ff ) in the atmosphere and for ecosystem source partitioning studies. The strength of the technique lies in the intrinsic differences between the 14 C signature of fossil fuels and other sources. In past studies, the 14 C content of CO 2 derived from plants has been equated with the 14 C content of the atmosphere. Carbon isotopic fractionation mechanisms vary among plants however, and experimental study on fractionation associated with dark respiration is lacking. Here we present accelerator mass spectrometry (AMS) radiocarbon results of CO 2 respired from 21 plants using a lab-incubation method and associated bulk organic matter. From the respired CO 2 we determine Δ 14 C res values, and from the bulk organic matter we determine Δ 14 C bom values. A significant difference between Δ 14 C res and Δ 14 C bom (P < 0.01) was observed for all investigated plants, ranging from -42.3‰ to 10.1‰. The results show that Δ 14 C res values are in agreement with mean atmospheric Δ 14 CO 2 for several days leading up to the sampling date, but are significantly different from corresponding bulk organic Δ 14 C values. We find that although dark respiration is unlikely to significantly influence the estimation of CO 2ff , an additional bias associated with the respiration rate during a plant's growth period should be considered when using Δ 14 C in plants to quantify atmospheric CO 2ff . Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. A novel hardware implementation for detecting respiration rate using photoplethysmography.

    Science.gov (United States)

    Prinable, Joseph; Jones, Peter; Thamrin, Cindy; McEwan, Alistair

    2017-07-01

    Asthma is a serious public health problem. Continuous monitoring of breathing may offer an alternative way to assess disease status. In this paper we present a novel hardware implementation for the capture and storage of a photoplethysmography (PPG) signal. The LED duty cycle was altered to determine the effect on respiratory rate accuracy. The oximeter was mounted to the left index finger of ten healthy volunteers. The breathing rate derived from the oximeter was validated against a nasal airflow sensor. The duty cycle of a pulse oximeter was changed between 5%, 10% and 25% at a sample rate of 500 Hz. A PPG signal and reference signal was captured for each duty cycle. The PPG signals were post processed in Matlab to derive a respiration rate using an existing Matlab toolbox. At a 25% duty cycle the RMSE was <;2 breaths per minute for the top performing algorithm. The RMSE increased to over 5 breaths per minute when the duty cycle was reduced to 5%. The power consumed by the hardware for a 5%, 10% and 25% duty cycle was 5.4 mW, 7.8 mW, and 15 mW respectively. For clinical assessment of respiratory rate, a RSME of <;2 breaths per minute is recommended. Further work is required to determine utility in asthma management. However for non-clinical applications such as fitness tracking, lower accuracy may be sufficient to allow a reduced duty cycle setting.

  2. Physiological constrains on Sverdrup's Critical-Depth-Hypothesis: the influences of dark respiration and sinking

    DEFF Research Database (Denmark)

    Lindemann, Christian; Backhaus, Jan O.; St. John, Michael

    2015-01-01

    of the spring bloom. However, they neglect the cells ability to modify vital rates in response to changes in the external environment. In this study, we use a non-hydrostatic convection model coupled to an Individual-Based-Model to simulate changes phytoplankton cells during the transition from winter...... conditions as driven by convective mixing, and the onset of thermal stratification resulting in the spring bloom. The comparison between a simulation using a standard fixed rate approach in line with the original Sverdrup hypothesis and a simulation parameterized to include variable respiration and sinking...... replicate field observations when employing unrealistic parameter values. These results highlight the necessity to consider not only the physical and biological external controls determining phytoplankton dynamics but also the cells ability to modify critical physiological rates in response to external...

  3. Effects of elevated CO2 concentrations on photosynthesis, dark res-piration and RuBPcase activity of three species seedlings in Changbai Mountain

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two-year-old seedlings of Pinus koraiensis, Pinus sylvestriformis and Fraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L-1, 500 μL·L-1) and ambient CO2 concentrations (350 μL·L-1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species except P. sylvestriformis grown under 500 μL·L-1 CO2 concentration. The dark respiration rates of P. koraiensis and P. sylvestriformis increased under concentration of 700 μL·L-1 CO2, but that of F. mandshurica decreased under both concentrations 700 μL·L-1 and 500 μL·L-1 CO2. The seedlings of F. mandshurica decreased in chlorophyll contents at elevat-ed CO2 concentrations.

  4. Glycolysis Is Dynamic and Relates Closely to Respiration Rate in Stored Sugarbeet Roots

    Directory of Open Access Journals (Sweden)

    Clarice A. Megguer

    2017-05-01

    Full Text Available Although respiration is the principal cause of the loss of sucrose in postharvest sugarbeet (Beta vulgaris L., the internal mechanisms that control root respiration rate are unknown. Available evidence, however, indicates that respiration rate is likely to be controlled by the availability of respiratory substrates, and glycolysis has a central role in generating these substrates. To determine glycolytic changes that occur in sugarbeet roots after harvest and to elucidate relationships between glycolysis and respiration, sugarbeet roots were stored for up to 60 days, during which activities of glycolytic enzymes and concentrations of glycolytic substrates, intermediates, cofactors, and products were determined. Respiration rate was also determined, and relationships between respiration rate and glycolytic enzymes and metabolites were evaluated. Glycolysis was highly variable during storage, with 10 of 14 glycolytic activities and 14 of 17 glycolytic metabolites significantly altered during storage. Changes in glycolytic enzyme activities and metabolites occurred throughout the 60 day storage period, but were greatest in the first 4 days after harvest. Positive relationships between changes in glycolytic enzyme activities and root respiration rate were abundant, with 10 of 14 enzyme activities elevated when root respiration was elevated and 9 glycolytic activities static during periods of unchanging respiration rate. Major roles for pyruvate kinase and phosphofructokinase in the regulation of postharvest sugarbeet root glycolysis were indicated based on changes in enzymatic activities and concentrations of their substrates and products. Additionally, a strong positive relationship between respiration rate and pyruvate kinase activity was found indicating that downstream TCA cycle enzymes were unlikely to regulate or restrict root respiration in a major way. Overall, these results establish that glycolysis is not static during sugarbeet root

  5. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

  6. Estimation of microbial respiration rates in groundwater by geochemical modeling constrained with stable isotopes

    International Nuclear Information System (INIS)

    Murphy, E.M.

    1998-01-01

    Changes in geochemistry and stable isotopes along a well-established groundwater flow path were used to estimate in situ microbial respiration rates in the Middendorf aquifer in the southeastern United States. Respiration rates were determined for individual terminal electron acceptors including O 2 , MnO 2 , Fe 3+ , and SO 4 2- . The extent of biotic reactions were constrained by the fractionation of stable isotopes of carbon and sulfur. Sulfur isotopes and the presence of sulfur-oxidizing microorganisms indicated that sulfate is produced through the oxidation of reduced sulfur species in the aquifer and not by the dissolution of gypsum, as previously reported. The respiration rates varied along the flow path as the groundwater transitioned between primarily oxic to anoxic conditions. Iron-reducing microorganisms were the largest contributors to the oxidation of organic matter along the portion of the groundwater flow path investigated in this study. The transition zone between oxic and anoxic groundwater contained a wide range of terminal electron acceptors and showed the greatest diversity and numbers of culturable microorganisms and the highest respiration rates. A comparison of respiration rates measured from core samples and pumped groundwater suggests that variability in respiration rates may often reflect the measurement scales, both in the sample volume and the time-frame over which the respiration measurement is averaged. Chemical heterogeneity may create a wide range of respiration rates when the scale of the observation is below the scale of the heterogeneity

  7. Thermal effects on growth and respiration rates of the mayfly, Dolania americana (ephemeroptera)

    International Nuclear Information System (INIS)

    Harvey, R.S.

    1975-01-01

    The mayfly Dolania Americana, common in the sand of Upper Three Runs Creek, Savannah River Plant, was studied to determine the effects of seasonal changes in temperature on population growth rates and to determine the effects of slight elevations in water temperature on respiration rates of this benthic species. Growth of the population increased with stream temperature until peak emergence of adults in June and July. There was a strong inverse correlation between body weight and respiration rates of immature nymphs. Respiration rates at 2.5, 5, and 10 0 C above ambient creekwater temperatures were not significantly higher than those measured at ambient creekwater temperatures. (auth)

  8. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    Science.gov (United States)

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module.

  9. Measurement and Modeling of Respiration Rate of Tomato (Cultivar Roma) for Modified Atmosphere Storage.

    Science.gov (United States)

    Kandasamy, Palani; Moitra, Ranabir; Mukherjee, Souti

    2015-01-01

    Experiments were conducted to determine the respiration rate of tomato at 10, 20 and 30 °C using closed respiration system. Oxygen depletion and carbon dioxide accumulation in the system containing tomato was monitored. Respiration rate was found to decrease with increasing CO2 and decreasing O2 concentration. Michaelis-Menten type model based on enzyme kinetics was evaluated using experimental data generated for predicting the respiration rate. The model parameters that obtained from the respiration rate at different O2 and CO2 concentration levels were used to fit the model against the storage temperatures. The fitting was fair (R2 = 0.923 to 0.970) when the respiration rate was expressed as O2 concentation. Since inhibition constant for CO2 concentration tended towards negetive, the model was modified as a function of O2 concentration only. The modified model was fitted to the experimental data and showed good agreement (R2 = 0.998) with experimentally estimated respiration rate.

  10. Does an elevated CO2 concentration decrease dark respiration in trees? Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Long, Stephen [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2003-12-31

    Averaged across many previous investigations, doubling the CO2 concentration ([CO2]) has frequently been reported to cause an instantaneous reduction of leaf dark respiration measured as CO2 efflux. No known mechanism accounts for this effect. While four recent studies have shown that the measurement of respiratory CO2 efflux is prone to experimental artifacts that could account for the reported response, papers published since the start of the current research continue to report an instantaneous depression of respiratory CO2 efflux by elevation of [CO2]. Here, these artifacts are avoided by use of a high-resolution dual channel oxygen analyzer within an open gas exchange system to measure respiratory 02 uptake in normal air. Leaf 02 uptake was determined in response to instantaneous elevation of [CO2] in nine contrasting species and to long-term elevation in seven species from four of the DOE-sponsored long-term elevated [CO2] field experiments. Over one thousand separate measurements of respiration failed to reveal any decrease in respiratory 02 uptake with an instantaneous increase in [CO2]. Respiration was found insensitive not only to doubling [CO2], but also to a five-fold increase and to decrease to zero.

  11. Influence of forced respiration on nonlinear dynamics in heart rate variability

    DEFF Research Database (Denmark)

    Kanters, J K; Højgaard, M V; Agner, E

    1997-01-01

    Although it is doubtful whether the normal sinus rhythm can be described as low-dimensional chaos, there is evidence for inherent nonlinear dynamics and determinism in time series of consecutive R-R intervals. However, the physiological origin for these nonlinearities is unknown. The aim...... with a metronome set to 12 min(-1). Nonlinear dynamics were measured as the correlation dimension and the nonlinear prediction error. Complexity expressed as correlation dimension was unchanged from normal respiration, 9.1 +/- 0.5, compared with forced respiration, 9.3 +/- 0.6. Also, nonlinear determinism...... expressed as the nonlinear prediction error did not differ between spontaneous respiration, 32.3 +/- 3.4 ms, and forced respiration, 31.9 +/- 5.7. It is concluded that the origin of the nonlinear dynamics in heart rate variability is not a nonlinear input from the respiration into the cardiovascular...

  12. Airborne release fractions/rates and respirable fractions for nonreactor nuclear facilities. Volume 2, Appendices

    International Nuclear Information System (INIS)

    1994-12-01

    This document contains compiled data from the DOE Handbook on Airborne Release Fractions/Rates and Respirable Fractions for Nonreactor Nuclear facilities. Source data and example facilities utilized, such as the Plutonium Recovery Facility, are included

  13. Landscape Influences on Potential Soil Respiration Rates in a Forested Watershed of Southeastern Kentucky

    Science.gov (United States)

    Amanda C. Abnee; James A. Thompson; Randall K. Kolka; Elisa M. D' Angelo; Mark S. Coyne

    2004-01-01

    Soil respiration measurements conducted in the laboratory have been shown to be related to temperature and moisture, with maximum rates at soil temperatures between 25 and 40°C and soil moisture between -0.01 and -0.10 MPa. A preliminary study using forest soils from eastern Kentucky supported the previous research with soil respiration rates greater at 25°C than at 15...

  14. Respiration rate of stream insects measured in situ along a large altitude range

    DEFF Research Database (Denmark)

    Rostgaard, S.; Jacobsen, D.

    2005-01-01

    Field studies of respiration in stream insects are few in comparison with laboratory studies. To evaluate the influence of temperature and oxygen along altitudinal gradients we measured the respiration rate of fully acclimatized larval Trichoptera, Plecoptera and Ephemeroptera under similar field...... at 100 and 50% oxygen saturation indicated that highland animals reduced their oxygen uptake more than their counterparts in the lowland when oxygen availability decreased. The temperature response of respiration calculated between the insect assemblages at different altitudes showed a mean assemblage Q...

  15. Influence of gamma irradiation, cold storage and pulsing on post harvest life and respiration rate of 'golden gate' cut roses

    International Nuclear Information System (INIS)

    Palanikumar, S.; Vinod Kumar; Bhattacharjee, S.K.; Pal, Madan

    2003-01-01

    Gamma irradiation at 0.025 kGy increased the respiration rate of 'Golden Gate' cut roses. The irradiation followed by cold storage (at 4 deg C) brought down the respiration rate after storage duration of 3 days. The respiration rate was found maximum in the sucrose (3% ) pulsed flowers immediately after pulsing. However, the rate of respiration is decreased in all the treatments. The irradiated flowers recorded lowest amount of respiration at senescence and the vase life was maximum in these flowers. (author)

  16. Data compilation of respiration, feeding, and growth rates of marine pelagic organisms

    DEFF Research Database (Denmark)

    2013-01-01

    's adaptation to the environment, with consequently less universal mass scaling properties. Data on body mass, maximum ingestion and clearance rates, respiration rates and maximum growth rates of animals living in the ocean epipelagic were compiled from the literature, mainly from original papers but also from...

  17. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf,Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    X.Z.WANG; P.S.CURTIS; 等

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston,Michigan,USA,to study the effects of soil fertility and CO2 on leaf,sdtem and root dark respiration (Rd) of Populus tremuloides.Overall,area-based daytime leaf Rd(Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil,but not in low-fertility soil.Mass-based leaf Rd(Rdm) was overall greater for high-than for low-fertility soil grown trees at elevated,but not at ambient CO2 .Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2,nor was stem Rda ,which ranged from 1.0 to 1.4μmol m-2s-1 in the spring and 3.5 to 4.5μmol m-2s-1 in the summer.Root Rda was significantly higher in high-than in low-fertiliy soil,but was unaffected by CO2.Since biomass production of P.tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged,we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2.Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  18. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf, Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based daytime leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elevated, but not at ambient CO2. Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 μmol m-2 s-1 in the spring and 3.5 to 4.5 μmol m-2 s-1 in the summer. Root Rda was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  19. Soil respiration patterns and rates at three Taiwanese forest plantations: dependence on elevation, temperature, precipitation, and litterfall

    OpenAIRE

    Huang, Yu-Hsuan; Hung, Chih-Yu; Lin, I-Rhy; Kume, Tomonori; Menyailo, Oleg V.; Cheng, Chih-Hsin

    2017-01-01

    Background Soil respiration contributes to a large quantity of carbon emissions in the forest ecosystem. In this study, the soil respiration rates at three Taiwanese forest plantations (two lowland and one mid-elevation) were investigated. We aimed to determine how soil respiration varies between lowland and mid-elevation forest plantations and identify the relative importance of biotic and abiotic factors affecting soil respiration. Results The results showed that the temporal patterns of so...

  20. No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest

    International Nuclear Information System (INIS)

    Betson, N.R.; Gottlicher, S.G.; Hogberg, P.; Hall, M.; Wallin, G.; Richter, A.

    2007-01-01

    This study evaluated the diurnal variability in the rate and stable carbon isotope ratio ((delta) 13 C) of soil respiration in a northern boreal forest, measured with opaque chambers after the removal of understory vegetation. The experiment was conducted in June and August 2004 at the Picea abies L. Karst-dominated Flakaliden Research Forest in northern Sweden, using unfertilized girdled-tree plots and unfertilized non-girdled tree plots. Soil respiration and (delta) 13 C of soil-respired carbon dioxide (CO 2 ) were measured every 4 hours on 6 plots, with a total of 11 sampling times over each 48 hour period. The purpose was to clarify an earlier study regarding the origin of diurnal patterns of soil CO 2 flux. This study explored whether the diurnal patterns were the result of photosynthetic CO 2 uptake during the day by the understory or whether there were underlying trends in soil respiration driven by plant root allocation. The sampling campaigns undertaken in this study investigated whether diurnal variations in soil respiration rate and (delta) 13 C exist in this ecosystem when no understory vegetation is present. Shoot photosynthesis and environmental parameters were measured simultaneously. Despite significant variations in climatic conditions and shoot photosynthetic rates in non-girdled trees, no diurnal patterns in soil respiration rates and (delta) 13 C were noted in either treatment. The lack of detectable diurnal changes in both treatments indicates that modeling of daily boreal forest carbon balances based on single instantaneous measurements are unlikely to be misconstrued by substantial diurnal trends. However, it was suggested that spatial variable should be accounted for, given the large standard errors. The impact of tree girdling on soil respiration rates also emphasized the significance of canopy photosynthesis in driving soil processes. 37 refs., 2 figs

  1. A Medical Cloud-Based Platform for Respiration Rate Measurement and Hierarchical Classification of Breath Disorders

    Directory of Open Access Journals (Sweden)

    Atena Roshan Fekr

    2014-06-01

    Full Text Available The measurement of human respiratory signals is crucial in cyberbiological systems. A disordered breathing pattern can be the first symptom of different physiological, mechanical, or psychological dysfunctions. Therefore, a real-time monitoring of the respiration patterns, as well as respiration rate is a critical need in medical applications. There are several methods for respiration rate measurement. However, despite their accuracy, these methods are expensive and could not be integrated in a body sensor network. In this work, we present a real-time cloud-based platform for both monitoring the respiration rate and breath pattern classification, remotely. The proposed system is designed particularly for patients with breathing problems (e.g., respiratory complications after surgery or sleep disorders. Our system includes calibrated accelerometer sensor, Bluetooth Low Energy (BLE and cloud-computing model. We also suggest a procedure to improve the accuracy of respiration rate for patients at rest positions. The overall error in the respiration rate calculation is obtained 0.53% considering SPR-BTA spirometer as the reference. Five types of respiration disorders, Bradapnea, Tachypnea, Cheyn-stokes, Kaussmal, and Biot’s breathing are classified based on hierarchical Support Vector Machine (SVM with seven different features. We have evaluated the performance of the proposed classification while it is individualized to every subject (case 1 as well as considering all subjects (case 2. Since the selection of kernel function is a key factor to decide SVM’s performance, in this paper three different kernel functions are evaluated. The experiments are conducted with 11 subjects and the average accuracy of 94.52% for case 1 and the accuracy of 81.29% for case 2 are achieved based on Radial Basis Function (RBF. Finally, a performance evaluation has been done for normal and impaired subjects considering sensitivity, specificity and G-mean parameters

  2. Separating the effect of respiration from the heart rate variability for cases of constant harmonic breathing

    Directory of Open Access Journals (Sweden)

    Kircher Michael

    2015-09-01

    Full Text Available Heart Rate Variability studies are a known measure for the autonomous control of the heart rate. In special situations, its interpretation can be ambiguous, since the respiration has a major influence on the heart rate variability. For this reason it has often been proposed to measure Heart Rate Variability, while the subjects are breathing at a constant respiration rate. That way the spectral influence of the respiration is known. In this work we propose to remove this constant respiratory influence from the heart rate and the Heart Rate Variability parameters to gain respiration free autonomous controlled heart rate signal. The spectral respiratory component in the heart rate signal is detected and characterized. Subsequently the respiratory effect on Heart Rate Variability is removed using spectral filtering approaches, such as the Notch filter or the Raised Cosine filter. As a result new decoupled Heart Variability parameters are gained, which could lead to new additional interpretations of the autonomous control of the heart rate.

  3. Soil respiration patterns and rates at three Taiwanese forest plantations: dependence on elevation, temperature, precipitation, and litterfall.

    Science.gov (United States)

    Huang, Yu-Hsuan; Hung, Chih-Yu; Lin, I-Rhy; Kume, Tomonori; Menyailo, Oleg V; Cheng, Chih-Hsin

    2017-11-15

    Soil respiration contributes to a large quantity of carbon emissions in the forest ecosystem. In this study, the soil respiration rates at three Taiwanese forest plantations (two lowland and one mid-elevation) were investigated. We aimed to determine how soil respiration varies between lowland and mid-elevation forest plantations and identify the relative importance of biotic and abiotic factors affecting soil respiration. The results showed that the temporal patterns of soil respiration rates were mainly influenced by soil temperature and soil water content, and a combined soil temperature and soil water content model explained 54-80% of the variation. However, these two factors affected soil respiration differently. Soil temperature positively contributed to soil respiration, but a bidirectional relationship between soil respiration and soil water content was revealed. Higher soil moisture content resulted in higher soil respiration rates at the lowland plantations but led to adverse effects at the mid-elevation plantation. The annual soil respiration rates were estimated as 14.3-20.0 Mg C ha -1  year -1 at the lowland plantations and 7.0-12.2 Mg C ha -1  year -1 at the mid-elevation plantation. When assembled with the findings of previous studies, the annual soil respiration rates increased with the mean annual temperature and litterfall but decreased with elevation and the mean annual precipitation. A conceptual model of the biotic and abiotic factors affecting the spatial and temporal patterns of the soil respiration rate was developed. Three determinant factors were proposed: (i) elevation, (ii) stand characteristics, and (iii) soil temperature and soil moisture. The results indicated that changes in temperature and precipitation significantly affect soil respiration. Because of the high variability of soil respiration, more studies and data syntheses are required to accurately predict soil respiration in Taiwanese forests.

  4. Estimate of respiration rate and physicochemical changes of fresh-cut apples stored under different temperatures

    Directory of Open Access Journals (Sweden)

    Cristiane Fagundes

    2013-03-01

    Full Text Available In this study, the influence of storage temperature and passive modified packaging (PMP on the respiration rate and physicochemical properties of fresh-cut Gala apples (Malus domestica B. was investigated. The samples were packed in flexible multilayer bags and stored at 2 °C, 5 °C, and 7 °C for eleven days. Respiration rate as a function of CO2 and O2 concentrations was determined using gas chromatography. The inhibition parameters were estimated using a mathematical model based on Michaelis-Menten equation. The following physicochemical properties were evaluated: total soluble solids, pH, titratable acidity, and reducing sugars. At 2 °C, the maximum respiration rate was observed after 150 hours. At 5 °C and 7 °C the maximum respiration rates were observed after 100 and 50 hours of storage, respectively. The inhibition model results obtained showed a clear effect of CO2 on O2 consumption. The soluble solids decreased, although not significantly, during storage at the three temperatures studied. Reducing sugars and titratable acidity decreased during storage and the pH increased. These results indicate that the respiration rate influenced the physicochemical properties.

  5. Effective dark count rate reduction by modified SPAD gating circuit

    Energy Technology Data Exchange (ETDEWEB)

    Prochazka, Ivan; Blazej, Josef, E-mail: blazej@fjfi.cvut.cz; Kodet, Jan

    2015-07-01

    For our main application of single photon counting avalanche detectors in focus – laser ranging of space objects and laser time transfer – the ultimate requirements are relatively large and homogeneous active area having a diameter of 100 to 200 µm and a sub-picosecond stability of timing. The detector dark count rate and after-pulsing probability are parameters of relatively lower, but not negligible importance. In presented paper we will focused on them. We have developed a new active quenching and gating scheme which can reduce afterpulsing effect and hence also effective dark count rate at lower temperature. In satellite laser ranging system the effective dark count rate was reduced more than 35 times. This improvement will contribute in increasing the data yield and hence to increase precision and productivity. - Highlights: • Signal and quenching path in a control circuit stayed unaffected by gating. • The detector package optimized for laser time transfer systems is considered. • After-pulsing effect is reduced by a modification of the use of gate signal. • The dark count rate is reduced for gate rates of the order of units of kHz.

  6. Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

    Science.gov (United States)

    Tang, Baojun; Riisgård, Hans Ulrik

    2018-03-01

    The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposed to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

  7. Effects of elevated CO2 leaf diets on gypsy moth (Lepidoptera: Lymantriidae) respiration rates.

    Science.gov (United States)

    Foss, Anita R; Mattson, William J; Trier, Terry M

    2013-06-01

    Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (Betula papyrifera Marshall) in 2004-2005, and trembling aspen (Populus tremuloides Michaux) in 2006-2007, and measured consequent effects on larval respiration. Leaves were collected for diet and leaf chemistry (nutritional and secondary compound proxies) from trees grown under ambient (average 380 ppm) and elevated CO2 (average 560 ppm) conditions. Elevated CO2 did not significantly alter birch or aspen leaf chemistry compared with ambient levels with the exception that birch percent carbon in 2004 and aspen moisture content in 2006 were significantly lowered. Respiration rates were significantly higher (15-59%) for larvae reared on birch grown under elevated CO2 compared with ambient conditions, but were not different on two aspen clones, until larvae reached the fifth instar, when those consuming elevated CO2 leaves on clone 271 had lower (26%) respiration rates, and those consuming elevated CO2 leaves on clone 216 had higher (36%) respiration rates. However, elevated CO2 had no apparent effect on the respiration rates of pupae derived from larvae fed either birch or aspen leaves. Higher respiration rates for larvae fed diets grown under ambient or elevated CO2 demonstrates their lower efficiency of converting chemical energy of digested food stuffs extracted from such leaves into their biosynthetic processes.

  8. The effects of operational conditions on the respiration rate of Tubificidae.

    Directory of Open Access Journals (Sweden)

    Juqing Lou

    Full Text Available Tubificidae is often used in the wastewater treatment systems to minimize the sludge production because it can be fed on the activated sludge. The process conditions have effect on the growth, reproduction, and sludge reduction efficiency of Tubificidae. The effects of the water quality, density of worms, pH, temperature and dissolved oxygen (DO concentration on the respiration rate of Tubificidae were investigated to determine the optimal conditions for the growth and metabolism of the worms and reveal the mechanisms involving the efficient sludge reduction in terms of these conditions. It was observed that the respiration rate was highest in the water discharged from an ecosystem that included symbiotic Tubificidae and microbes and was lowest in distilled water. Considering density of the worms, the highest rate was 81.72±5.12 mg O2/g(dry weight·h·L with 0.25 g (wet weight of worms in 1 L test flask. The maximum Tubificidae respiration rate was observed at a pH of 8.0±0.05, a rate that was more than twice as high as those observed at other pH values. The respiration rate increased in the temperature range of ∼8°C-22°C, whereas the rate declined in the temperature range of ∼22°C-30°C. The respiration rate of Tubificidae was very high for DO range of ∼3.5-4.5 mg/L, and the rates were relatively low for out of this DO range. The results of this study revealed the process conditions which influenced the growth, and reproduction of Tubificidae and sludge reduction at a microscopic level, which could be a theoretical basis for the cultivation and application of Tubificidae in wastewater treatment plants.

  9. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    International Nuclear Information System (INIS)

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-01-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions

  10. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces.

    Science.gov (United States)

    Gross, Benjamin J; El-Naggar, Mohamed Y

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  11. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Benjamin J. [Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Los Angeles, California 90089-0484 (United States); El-Naggar, Mohamed Y., E-mail: mnaggar@usc.edu [Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Los Angeles, California 90089-0484 (United States); Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0484 (United States); Department of Chemistry, University of Southern California, Los Angeles, California 90089-0484 (United States)

    2015-06-15

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  12. Analyses of Heart Rate, Respiration and Cardiorespiratory Coupling in Patients with Schizophrenia

    Directory of Open Access Journals (Sweden)

    Steffen Schulz

    2015-01-01

    Full Text Available Schizophrenia is a severe mental disorder associated with a significantly increased cardiovascular mortality rate. However, the underlying mechanisms leading to this cardiovascular disease (CVD are not fully known. Therefore, the objective of this study was to characterize the cardiorespiratory influence by investigating heart rate, respiration and the causal strength and direction of cardiorespiratory coupling (CRC, based mainly on entropy measures. We investigated 23 non-medicated patients with schizophrenia (SZ, comparing them to 23 age- and gender-matched healthy controls (CO. A significantly reduced complexity was found for the heart rate and a significantly increased complexity in respiration and CRC in SZ patients when compared to corresponding measurements from CO (p < 0.001. CRC analyses revealed a clear coupling, with a driver-responder relationship from respiration to heart rate in SZ patients. Moreover, a slight driver-responder relationship from heart rate to respiration could be recognized. These findings lead to the assumption that SZ should be considered to be a high-risk group for CVD. We hypothesize that the varying cardiorespiratory regulation contributes to the increased risk for cardiac mortality. Therefore, regular monitoring of the cardiorespiratory status of SZ is suggested to identify autonomic regulation impairment at an early stage—to develop timely and effective treatment and intervention strategies.

  13. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    Science.gov (United States)

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil.

  14. Growth rate in the dynamical dark energy models

    International Nuclear Information System (INIS)

    Avsajanishvili, Olga; Arkhipova, Natalia A.; Samushia, Lado; Kahniashvili, Tina

    2014-01-01

    Dark energy models with a slowly rolling cosmological scalar field provide a popular alternative to the standard, time-independent cosmological constant model. We study the simultaneous evolution of background expansion and growth in the scalar field model with the Ratra-Peebles self-interaction potential. We use recent measurements of the linear growth rate and the baryon acoustic oscillation peak positions to constrain the model parameter α that describes the steepness of the scalar field potential. (orig.)

  15. Growth rate in the dynamical dark energy models.

    Science.gov (United States)

    Avsajanishvili, Olga; Arkhipova, Natalia A; Samushia, Lado; Kahniashvili, Tina

    Dark energy models with a slowly rolling cosmological scalar field provide a popular alternative to the standard, time-independent cosmological constant model. We study the simultaneous evolution of background expansion and growth in the scalar field model with the Ratra-Peebles self-interaction potential. We use recent measurements of the linear growth rate and the baryon acoustic oscillation peak positions to constrain the model parameter [Formula: see text] that describes the steepness of the scalar field potential.

  16. Respiration rate detection based on intensity modulation using plastic optical fiber

    Science.gov (United States)

    Anwar, Zawawi Mohd; Ziran Nurul Sufia, Nor; Hadi, Manap

    2017-11-01

    This paper presents the implementation of respiration rate measurement via a simple intensity-based optical fiber sensor using optical fiber technology. The breathing rate is measured based on the light intensity variation due to the longitudinal gap changes between two separated fibers. In order to monitor the breathing rate continuously, the output from the photodetector conditioning circuit is connected to a low-cost Arduino kit. At the sensing point, two optical fiber cables are positioned in series with a small gap and fitted inside a transparent plastic tube. To ensure smooth movement of the fiber during inhale and exhale processes as well as to maintain the gap of the fiber during idle condition, the fiber is attached firmly to a stretchable bandage. This study shows that this simple fiber arrangement can be applied to detect respiration activity which might be critical for patient monitoring.

  17. Respiration rate detection based on intensity modulation using plastic optical fiber

    Directory of Open Access Journals (Sweden)

    Mohd Anwar Zawawi

    2017-01-01

    Full Text Available This paper presents the implementation of respiration rate measurement via a simple intensity-based optical fiber sensor using optical fiber technology. The breathing rate is measured based on the light intensity variation due to the longitudinal gap changes between two separated fibers. In order to monitor the breathing rate continuously, the output from the photodetector conditioning circuit is connected to a low-cost Arduino kit. At the sensing point, two optical fiber cables are positioned in series with a small gap and fitted inside a transparent plastic tube. To ensure smooth movement of the fiber during inhale and exhale processes as well as to maintain the gap of the fiber during idle condition, the fiber is attached firmly to a stretchable bandage. This study shows that this simple fiber arrangement can be applied to detect respiration activity which might be critical for patient monitoring.

  18. The Arabidopsis thaliana natriuretic peptide AtPNP-A is a systemic regulator of leaf dark respiration and signals via the phloem

    KAUST Repository

    Ruzvidzo, Oziniel

    2011-09-01

    Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. Here we show that a recombinant Arabidopsis thaliana PNP (AtPNP-A) rapidly increased the rate of dark respiration in treated leaves after 5 min. In addition, we observed increases in lower leaves, and with a lag time of 10 min, the effect spread to the upper leaves and subsequently (after 15 min) to the opposite leaves. This response signature is indicative of phloem mobility of the signal, a hypothesis that was further strengthened by the fact that cold girdling, which affects phloem but not xylem or apoplastic processes, delayed the long distance AtPNP-A effect. We conclude that locally applied AtPNP-A can induce a phloem-mobile signal that rapidly modifies plant homeostasis in distal parts. © 2011 Elsevier GmbH.

  19. Microbiopsies versus Bergström needle for skeletal muscle sampling: impact on maximal mitochondrial respiration rate.

    Science.gov (United States)

    Isner-Horobeti, M E; Charton, A; Daussin, F; Geny, B; Dufour, S P; Richard, R

    2014-05-01

    Microbiopsies are increasingly used as an alternative to the standard Bergström technique for skeletal muscle sampling. The potential impact of these two different procedures on mitochondrial respiration rate is unknown. The objective of this work was to compare microbiopsies versus Bergström procedure on mitochondrial respiration in skeletal muscle. 52 vastus lateralis muscle samples were obtained from 13 anesthetized pigs, either with a Bergström [6 gauges (G)] needle or with microbiopsy needles (12, 14, 18G). Maximal mitochondrial respiration (V GM-ADP) was assessed using an oxygraphic method on permeabilized fibers. The weight of the muscle samples and V GM-ADP decreased with the increasing gauge of the needles. A positive nonlinear relationship was observed between the weight of the muscle sample and the level of maximal mitochondrial respiration (r = 0.99, p respiration (r = 0.99, p respiration compared to the standard Bergström needle.Therefore, the higher the gauge (i.e. the smaller the size) of the microbiopsy needle, the lower is the maximal rate of respiration. Microbiopsies of skeletal muscle underestimate the maximal mitochondrial respiration rate, and this finding needs to be highlighted for adequate interpretation and comparison with literature data.

  20. Respiration rate and ethylene production of fresh cut lettuce as affected by cutting grade

    Directory of Open Access Journals (Sweden)

    J. MARTÍNEZ

    2008-12-01

    Full Text Available For designing optimal polymeric films for modified atmosphere packaging of whole heads as well as for minimally fresh processed (fresh-cut Iceberg lettuce ‘Coolguard’, the effect of several cutting grades on respiration rate (RR and ethylene production at 5ºC was studied. According to common industrial practices cutting grades less than 0.5 cm, between 0.5 and 1 cm, and 2 cm length were selected. Results from four experiments were compared to those obtained for whole heads in which a homogenous range of 6 to 8 ml CO2 kg-1 h-1 in RR was found. Compared to whole heads, in fresh-cut lettuce the RR was 2-fold higher. The lowest cutting grade showed the highest respiration rate, and no significant differences in RR among lettuce pieces of intermediate and the highest grades were found. No ethylene production was detected in whole heads, while in minimally processed lettuce pieces only traces were found. For avoiding risks of anaerobic respiration and excessive CO2 levels within packages containing fresh-cut lettuce pieces lower than 0.5 cm length, films with relatively high O2 permeability like standard polypropylene or low-density polyethylene must be selected.;

  1. Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

    Science.gov (United States)

    Anderson, I. C.; Levine, J. S.

    1986-01-01

    An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

  2. Changes in respiration rates and biomass attributes of epilithon due to extended exposure to zinc

    International Nuclear Information System (INIS)

    Colwell, F.S.

    1986-01-01

    The purpose of this research was to determine the influence of extended dosing of zinc on the carbon cycling and biomass characteristics of freshwater epilithon. Experiments were conducted in artificial streams continuously dosed with 0.00, 0.05, or 1.00 mg Zn liter -1 for 20 to 30 days during summer and fall, 1984 and 1985. Repeated measurement of epilithon structure and function included estimates of 14 C-glucose respiration, 14 C-glutamate respiration, O 2 and CO 2 flux rates, ash-free dry weight (AFDW), protein, carbohydrate, and algal pigment concentrations, and total and zinc-tolerant colony forming units. An increase in epilithic glucose respiration per unit biomass consistently occurred 5 to 10 days after dosing with 1.0 mg Zn liter -1 was started. At the same time significantly lower epilithon biomass occurred in the high dosed streams relative to controls in 3 out of 4 studies. Although algal pigment concentrations were lowest in the high dose streams at the midpoint of the studies, the chlorophyll a-to-pheophytin a ratio remained high, indicating that the minimal algal population was not senescing in situ. After 30 days, the epilithon dosed with 1.0 mg Zn liter -1 had higher AFDW, protein, and carbohydrate concentrations than the other treatments. The development of unique epilithon communities that are acclimated to prolonged zinc exposure is evident in the eventual recolonization of the artificial surfaces, glucose respiration rates that are comparable to controls, and presence of zinc-tolerant heterotrophs

  3. Dark noise rates in irradiated silicon photomultiplier arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, Sebastian; Comerma, Albert; Gerick, David; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Kecke, Matthieu; Leverington, Blake; Mazorra de Cos, Jose; Mitzel, Dominik; Neuner, Max; Uwer, Ulrich [Physikalisches Institut, Universitaet Heidelberg (Germany); Collaboration: LHCb-Collaboration

    2016-07-01

    The planned downstream tracking system - the Scintillating Fibre Tracker - for the LHCb upgrade uses silicon photomultiplier (SiPM) arrays of 128 channels to read out mats made of 250 μm diameter scintillating fibres. In the LHCb environment the neutron flux degrades the silicon detectors to the edge of an acceptable performance in terms of DCR. Studies have shown that the dark count rate (DCR) of the SiPMs increases linearly with the neutron flux. Towards the end of the designed lifetime of the experiment the DCR per SiPM channel operated at T = -40 C is expected to reach a few MHz after partial annealing. To reduce the impact of the DCR - while at the same time provide efficient hit reconstruction - a clustering algorithm is developed to separate signal from noise. A brief introduction into the custom designed read-out ASIC and the cluster algorithm are presented along with the studies of the dark count cluster rate dependency on the neutron flux, the DCR per channel and the effects of the applied signal thresholds for the clustering algorithm.

  4. Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups.

    Science.gov (United States)

    Reich, Peter B; Walters, Michael B; Ellsworth, David S; Vose, James M; Volin, John C; Gresham, Charles; Bowman, William D

    1998-05-01

    Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf dark respiration rate (R d ) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (A max ). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types. We tested this idea by examining the interspecific relationships between R d measured at a standard temperature and leaf life-span, N, SLA and A max for 69 species from four functional groups (forbs, broad-leafed trees and shrubs, and needle-leafed conifers) in six biomes traversing the Americas: alpine tundra/subalpine forest, Colorado; cold temperate forest/grassland, Wisconsin; cool temperate forest, North Carolina; desert/shrubland, New Mexico; subtropical forest, South Carolina; and tropical rain forest, Amazonas, Venezuela. Area-based R d was positively related to area-based leaf N within functional groups and for all species pooled, but not when comparing among species within any site. At all sites, mass-based R d (R d-mass ) decreased sharply with increasing leaf life-span and was positively related to SLA and mass-based A max and leaf N (leaf N mass ). These intra-biome relationships were similar in shape and slope among sites, where in each case we compared species belonging to different plant functional groups. Significant R d-mass -N mass relationships were observed in all functional groups (pooled across sites), but the relationships differed, with higher R d at any given leaf N in functional groups (such as forbs) with higher SLA and shorter leaf life-span. Regardless of biome or functional group, R d-mass was well predicted by all combinations of leaf life-span, N mass and/or SLA (r 2 ≥ 0.79, P morphological, chemical and metabolic traits.

  5. Effect of thermal treatment on the body temperature, respiration and pulse rate in dogs chronically irradiated with γ-rays

    International Nuclear Information System (INIS)

    Popova, N.A.; Petrovnin, M.G.

    1975-01-01

    Male dogs were chronically gamma-irradiated at different dose rates (0.06, 0.17, 0.34 rad/day) and subjected to heat treatment (raising of temperature from 22 0 C to 40 0 C) during winter and summer. Internal (rectal) temperature, respiration rate and heart rate were recorded. The respiration rate changed appreciably in all groups during all periods of temperature rise and fall in the chamber, but the variations were more pronounced in all groups during the winter experiment than during the summer experiment; no significant differences were found between the groups of animals while the respiration rate was changing, either in the winter or in the summer experiment. In both experiments, there were considerable heart rate variations only in the control group and in the group exposed to a dose rate of 0.06 rad/day. (V.A.P.)

  6. Does cypermethrin affect enzyme activity, respiration rate and walking behavior of the maize weevil (Sitophilus zeamais)?

    Institute of Scientific and Technical Information of China (English)

    Ronnie Von Santos Veloso; Eliseu José G.Pereira; Raul Narciso C.Guedes; Maria Goreti A.Oliveira

    2013-01-01

    Insecticides cause a range of sub-lethal effects on targeted insects,which are frequently detrimental to them.However,targeted insects are able to cope with insecticides within sub-lethal ranges,which vary with their susceptibility.Here we assessed the response of three strains of the maize weevil Sitophilus zeamais Motschulsky (Coleoptera:Curculionidae) to sub-lethal exposure to the pyrethoid insecticide cypermethrin.We expected enzyme induction associated with cypermethrin resistance since it would aid the resistant insects in surviving such exposure.Lower respiration rate and lower activity were also expected in insecticide-resistant insects since these traits are also likely to favor survivorship under insecticide exposure.Curiously though,cypermethrin did not affect activity of digestive and energy metabolism enzymes,and even reduced the activity of some enzymes (particularly for cellulase and cysteine-proteinase activity in this case).There was strain variation in response,which may be (partially) related to insecticide resistance in some strains.Sub-lethal exposure to cypermethrin depressed proteolytic and mainly cellulolytic activity in the exposed insects,which is likely to impair their fitness.However,such exposure did not affect respiration rate and walking behavior of the insects (except for the susceptible strain where walking activity was reduced).Walking activity varies with strain and may minimize insecticide exposure,which should be a concern,particularly if associated with (physiological) insecticide resistance.

  7. A regulated response to impaired respiration slows behavioral rates and increases lifespan in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    David Cristina

    2009-04-01

    Full Text Available When mitochondrial respiration or ubiquinone production is inhibited in Caenorhabditis elegans, behavioral rates are slowed and lifespan is extended. Here, we show that these perturbations increase the expression of cell-protective and metabolic genes and the abundance of mitochondrial DNA. This response is similar to the response triggered by inhibiting respiration in yeast and mammalian cells, termed the "retrograde response". As in yeast, genes switched on in C. elegans mitochondrial mutants extend lifespan, suggesting an underlying evolutionary conservation of mechanism. Inhibition of fstr-1, a potential signaling gene that is up-regulated in clk-1 (ubiquinone-defective mutants, and its close homolog fstr-2 prevents the expression of many retrograde-response genes and accelerates clk-1 behavioral and aging rates. Thus, clk-1 mutants live in "slow motion" because of a fstr-1/2-dependent pathway that responds to ubiquinone. Loss of fstr-1/2 does not suppress the phenotypes of all long-lived mitochondrial mutants. Thus, although different mitochondrial perturbations activate similar transcriptional and physiological responses, they do so in different ways.

  8. Forest floor and mineral soil respiration rates in a northern Minnesota red pine chronosequence

    Science.gov (United States)

    Powers, Matthew; Kolka, Randall; Bradford, John B.; Palik, Brian J.; Jurgensen, Martin

    2018-01-01

    We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosaAit.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123) stands. This pattern was most apparent during warm summer months, but there were no consistent differences in RFF among different-aged stands. RFF represented an average of 4–13% of total soil respiration, and forest floor removal increased moisture content in the mineral soil. We found no evidence of an age effect on the temperature sensitivity of RS, but respiration rates in Y61 and Y123 were less sensitive to low soil moisture than RS in Y9 and Y31. Our results suggest that soil respiration’s sensitivity to soil moisture may change more over the course of stand development than its sensitivity to soil temperature in red pine, and that management activities that alter landscape-scale age distributions in red pine forests could have significant impacts on rates of soil CO2 efflux from this forest type.

  9. [Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

    Science.gov (United States)

    Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

    2009-10-15

    To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

  10. Stress level in wild harbour porpoises (Phocoena phocoena) during satellite tagging measured by respiration, heart rate and cortisol

    DEFF Research Database (Denmark)

    Eskesen, Ida Grønborg; Teilmann, J.; Geertsen, B. M.

    2009-01-01

    During satellite tagging of harbour porpoises (Phocoena phocoena), heart rate, respiration rate and cortisol value were measured to evaluate stress effects during handling and tagging. Respiration rates were obtained using video recordings, heart rates were recorded and serum cortisol levels were...... between cortisol and month of year, sex and body length. As high individual variations occurred in response to tagging of harbour porpoises, it is not possible to give general advice based oil the factors investigated, on how to reduce stress during handling. However, pouring water over the animal...

  11. Soil respiration and rates of soil carbon turnover differ among six common European tree species

    DEFF Research Database (Denmark)

    Vesterdal, Lars; Elberling, Bo; Christiansen, Jesper Riis

    2012-01-01

    replicated at six sites in Denmark. The studied tree species were the broadleaves beech (Fagus sylvatica L.), pedunculate oak (Quercus robur L.), lime (Tilia cordata L.), sycamore maple (Acer pseudoplatanus L.) and ash (Fraxinus excelsior L.) and the conifer Norway spruce (Picea abies (L.) Karst.). Rates....... Soil respiration differed significantly among several species and increased in the order beechmaple... moisture. Carbon turnover rates based on the ratio between R h and C stock were significantly higher in ash than in all other species except maple, and maple also had higher C turnover than spruce. A similar influence of tree species on C turnover was indicated by the litterfall C to forest floor C ratio...

  12. A method of detection of respiration rate on Android using UWB Impulse Radar

    Directory of Open Access Journals (Sweden)

    Young-Jin Park

    2016-12-01

    Full Text Available Monitoring respiration rate is important because it can help to detect and prevent abnormal respiratory rates that can lead to cardiac arrest and chronic obstructive pulmonary disease. Nowadays, most medical measurement and monitoring devices are either invasive or wired but people are hesitant to attach physiological sensors to their body. In this study, we investigated whether real-time medical measurement of breathing using Novelda’s Ultra-Wideband Impulse Radio (IR-UWB–which does not need to be attached to the human body and is also non-invasive–is possible on Android. Experimental results obtained were found to be comparable to those of a commercial healthcare device.

  13. The effect of food on the respiration rates of Daphnia magna using a flow-through system

    Directory of Open Access Journals (Sweden)

    Claire Schmoker

    2003-09-01

    Full Text Available Respiration rates and gut fluorescence of the cladoceran Daphnia magna were studied using a flow-through system. This open system has the advantage of introducing food or producing a starvation effect during the course of the experiment. Severe variations in respiratory rates were observed in relation to the presence or absence of food, indicating short-term variability. Organisms kept starved or at low food for a long period (15-20 h responded to a sudden increase in food by increasing their respiration rates three- to four-fold in parallel with their gut content. A significant relationship between gut fluorescence and respiration rates was observed, suggesting that feeding and the related swimming activity were responsible for the observed metabolic variability.

  14. Dark respiration of leaves and traps of terrestrial carnivorous plants: are there greater energetic costs in traps?

    Czech Academy of Sciences Publication Activity Database

    Adamec, Lubomír

    2010-01-01

    Roč. 5, č. 1 (2010), s. 121-124 ISSN 1895-104X Institutional research plan: CEZ:AV0Z60050516 Keywords : Aerobic respiration * metabolic costs * trap specialization Subject RIV: EF - Botanics Impact factor: 0.685, year: 2010

  15. Spectral analysis of time series of events: effect of respiration on heart rate in neonates

    International Nuclear Information System (INIS)

    Van Drongelen, Wim; Williams, Amber L; Lasky, Robert E

    2009-01-01

    Certain types of biomedical processes such as the heart rate generator can be considered as signals that are sampled by the occurring events, i.e. QRS complexes. This sampling property generates problems for the evaluation of spectral parameters of such signals. First, the irregular occurrence of heart beats creates an unevenly sampled data set which must either be pre-processed (e.g. by using trace binning or interpolation) prior to spectral analysis, or analyzed with specialized methods (e.g. Lomb's algorithm). Second, the average occurrence of events determines the Nyquist limit for the sampled time series. Here we evaluate different types of spectral analysis of recordings of neonatal heart rate. Coupling between respiration and heart rate and the detection of heart rate itself are emphasized. We examine both standard and data adaptive frequency bands of heart rate signals generated by models of coupled oscillators and recorded data sets from neonates. We find that an important spectral artifact occurs due to a mirror effect around the Nyquist limit of half the average heart rate. Further we conclude that the presence of respiratory coupling can only be detected under low noise conditions and if a data-adaptive respiratory band is used

  16. Variation in foliar respiration and wood CO2 efflux rates among species and canopy layers in a wet tropical forest.

    Science.gov (United States)

    Asao, Shinichi; Bedoya-Arrieta, Ricardo; Ryan, Michael G

    2015-02-01

    As tropical forests respond to environmental change, autotrophic respiration may consume a greater proportion of carbon fixed in photosynthesis at the expense of growth, potentially turning the forests into a carbon source. Predicting such a response requires that we measure and place autotrophic respiration in a complete carbon budget, but extrapolating measurements of autotrophic respiration from chambers to ecosystem remains a challenge. High plant species diversity and complex canopy structure may cause respiration rates to vary and measurements that do not account for this complexity may introduce bias in extrapolation more detrimental than uncertainty. Using experimental plantations of four native tree species with two canopy layers, we examined whether species and canopy layers vary in foliar respiration and wood CO2 efflux and whether the variation relates to commonly used scalars of mass, nitrogen (N), photosynthetic capacity and wood size. Foliar respiration rate varied threefold between canopy layers, ∼0.74 μmol m(-2) s(-1) in the overstory and ∼0.25 μmol m(-2) s(-1) in the understory, but little among species. Leaf mass per area, N and photosynthetic capacity explained some of the variation, but height explained more. Chamber measurements of foliar respiration thus can be extrapolated to the canopy with rates and leaf area specific to each canopy layer or height class. If area-based rates are sampled across canopy layers, the area-based rate may be regressed against leaf mass per area to derive the slope (per mass rate) to extrapolate to the canopy using the total leaf mass. Wood CO2 efflux varied 1.0-1.6 μmol m(-2) s(-1) for overstory trees and 0.6-0.9 μmol m(-2) s(-1) for understory species. The variation in wood CO2 efflux rate was mostly related to wood size, and little to species, canopy layer or height. Mean wood CO2 efflux rate per surface area, derived by regressing CO2 efflux per mass against the ratio of surface

  17. Bacterial Respiration and Growth Rates Affect the Feeding Preferences, Brood Size and Lifespan of Caenorhabditis elegans

    Science.gov (United States)

    Yu, Li; Yan, Xiaomei; Ye, Chenglong; Zhao, Haiyan; Chen, Xiaoyun; Hu, Feng; Li, Huixin

    2015-01-01

    Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. PMID:26222828

  18. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis and C4 (Chloris virgata and Hemarthria altissima Grasses in Northeast China

    Directory of Open Access Journals (Sweden)

    Shangzhi Zhong

    2017-12-01

    Full Text Available Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO2 (δ13Cl and respiratory apparent isotope fractionation relative to biomass (ΔR,biomass in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C3-C4 mixed ecosystem C fluxes. We measured δ13Cl, the δ13C of biomass and of potential respiratory substrates and leaf gas exchange in one C3 (Leymus chinensis and two C4 (Chloris virgata and Hemarthria altissima grasses during a manipulated drought period. For all studied grasses, δ13Cl decreased from 21:00 to 03:00 h. The magnitude of the nighttime shift in δ13Cl decreased with increasing drought stress. The δ13Cl values were correlated with the δ13C of respiratory substrates, whereas the magnitude of the nighttime shift in δ13Cl strongly depended on the daytime carbon assimilation rate and the range of nighttime variations in the respiratory substrate content. The ΔR,biomass in the C3 and C4 grasses varied in opposite directions with the intensification of the drought stress. The contribution of C4 plant-associated carbon flux is likely to be overestimated if carbon isotope signatures are used for the partitioning of ecosystem carbon exchange and the δ13C of biomass is used as a substitute for leaf dark-respired CO2. The detected drought sensitivities in δ13Cl and differences in respiratory apparent isotope fractionation between C3 and C4 grasses have marked implications for isotope partitioning studies at the ecosystem level.

  19. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis) and C4 (Chloris virgata and Hemarthria altissima) Grasses in Northeast China.

    Science.gov (United States)

    Zhong, Shangzhi; Chai, Hua; Xu, Yueqiao; Li, Yan; Ma, Jian-Ying; Sun, Wei

    2017-01-01

    Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO 2 (δ 13 C l ) and respiratory apparent isotope fractionation relative to biomass (Δ R,biomass ) in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C 3 -C 4 mixed ecosystem C fluxes. We measured δ 13 C l , the δ 13 C of biomass and of potential respiratory substrates and leaf gas exchange in one C 3 ( Leymus chinensis ) and two C 4 ( Chloris virgata and Hemarthria altissima ) grasses during a manipulated drought period. For all studied grasses, δ 13 C l decreased from 21:00 to 03:00 h. The magnitude of the nighttime shift in δ 13 C l decreased with increasing drought stress. The δ 13 C l values were correlated with the δ 13 C of respiratory substrates, whereas the magnitude of the nighttime shift in δ 13 C l strongly depended on the daytime carbon assimilation rate and the range of nighttime variations in the respiratory substrate content. The Δ R,biomass in the C 3 and C 4 grasses varied in opposite directions with the intensification of the drought stress. The contribution of C 4 plant-associated carbon flux is likely to be overestimated if carbon isotope signatures are used for the partitioning of ecosystem carbon exchange and the δ 13 C of biomass is used as a substitute for leaf dark-respired CO 2 . The detected drought sensitivities in δ 13 C l and differences in respiratory apparent isotope fractionation between C 3 and C 4 grasses have marked implications for isotope partitioning studies at the ecosystem level.

  20. Non-contact acquisition of respiration and heart rates using Doppler radar with time domain peak-detection algorithm.

    Science.gov (United States)

    Xiaofeng Yang; Guanghao Sun; Ishibashi, Koichiro

    2017-07-01

    The non-contact measurement of the respiration rate (RR) and heart rate (HR) using a Doppler radar has attracted more attention in the field of home healthcare monitoring, due to the extremely low burden on patients, unconsciousness and unconstraint. Most of the previous studies have performed the frequency-domain analysis of radar signals to detect the respiration and heartbeat frequency. However, these procedures required long period time (approximately 30 s) windows to obtain a high-resolution spectrum. In this study, we propose a time-domain peak detection algorithm for the fast acquisition of the RR and HR within a breathing cycle (approximately 5 s), including inhalation and exhalation. Signal pre-processing using an analog band-pass filter (BPF) that extracts respiration and heartbeat signals was performed. Thereafter, the HR and RR were calculated using a peak position detection method, which was carried out via LABVIEW. To evaluate the measurement accuracy, we measured the HR and RR of seven subjects in the laboratory. As a reference of HR and RR, the persons wore contact sensors i.e., an electrocardiograph (ECG) and a respiration band. The time domain peak-detection algorithm, based on the Doppler radar, exhibited a significant correlation coefficient of HR of 0.92 and a correlation coefficient of RR of 0.99, between the ECG and respiration band, respectively.

  1. General Theory of Decoy-State Quantum Cryptography with Dark Count Rate Fluctuation

    International Nuclear Information System (INIS)

    Xiang, Gao; Shi-Hai, Sun; Lin-Mei, Liang

    2009-01-01

    The existing theory of decoy-state quantum cryptography assumes that the dark count rate is a constant, but in practice there exists fluctuation. We develop a new scheme of the decoy state, achieve a more practical key generation rate in the presence of fluctuation of the dark count rate, and compare the result with the result of the decoy-state without fluctuation. It is found that the key generation rate and maximal secure distance will be decreased under the influence of the fluctuation of the dark count rate

  2. Non-Invasive Detection of Respiration and Heart Rate with a Vehicle Seat Sensor.

    Science.gov (United States)

    Wusk, Grace; Gabler, Hampton

    2018-05-08

    This study demonstrates the feasibility of using a seat sensor designed for occupant classification from a production passenger vehicle to measure an occupant’s respiration rate (RR) and heart rate (HR) in a laboratory setting. Relaying occupant vital signs after a crash could improve emergency response by adding a direct measure of the occupant state to an Advanced Automatic Collision Notification (AACN) system. Data was collected from eleven participants with body weights ranging from 42 to 91 kg using a Ford Mustang passenger seat and seat sensor. Using a ballistocardiography (BCG) approach, the data was processed by time domain filtering and frequency domain analysis using the fast Fourier transform to yield RR and HR in a 1-min sliding window. Resting rates over the 30-min data collection and continuous RR and HR signals were compared to laboratory physiological instruments using the Bland-Altman approach. Differences between the seat sensor and reference sensor were within 5 breaths per minute for resting RR and within 15 beats per minute for resting HR. The time series comparisons for RR and HR were promising with the frequency analysis technique outperforming the peak detection technique. However, future work is necessary for more accurate and reliable real-time monitoring of RR and HR outside the laboratory setting.

  3. Comparison of primary production and pelagic community respiration rates in the coastal zone of the Gulf of Gdansk

    Directory of Open Access Journals (Sweden)

    Joanna K. York

    2001-09-01

    Full Text Available The organic matter production/respiration balance in the coastal water column was examined, both the primary production and community respiration being measured with the oxygen light-and-dark bottle method. Community respiration (CR was always lower than the gross primary production (GPP measured at a standard light intensity of 390 µE m-2 s-1, which amounted, on average, to 30% of GPP. During most of the in situ sampling period, the coastal system (6-7 m depth was found to be autotrophic, with depth-integrated GPP ranging from 6.7 mmoles O2 m-2 d-1 in December to 214.2 mmoles O2 m-2 d-1 in August, and CR ranging correspondingly from 6.0 to 177.7 mmoles O2 m-2 d-1. However, on some occasions heterotrophic conditions were recorded: depth-integrated GPP

  4. Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica.

    Science.gov (United States)

    Jia, Shuxia; McLaughlin, Neil B; Gu, Jiacun; Li, Xingpeng; Wang, Zhengquan

    2013-06-01

    Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the

  5. Production, oxygen respiration rates, and sinking velocity of copepod fecal pellets: Direct measurements of ballasting by opal and calcite

    DEFF Research Database (Denmark)

    Ploug, H.; Iversen, M.H.; Koski, Marja

    2008-01-01

    sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d(-1) independent on diet (range: 0.08-0.21 d(-1)). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 +/- 169 m d...

  6. Macromolecular Rate Theory (MMRT) Provides a Thermodynamics Rationale to Underpin the Convergent Temperature Response in Plant Leaf Respiration

    Science.gov (United States)

    Liang, L. L.; Arcus, V. L.; Heskel, M.; O'Sullivan, O. S.; Weerasinghe, L. K.; Creek, D.; Egerton, J. J. G.; Tjoelker, M. G.; Atkin, O. K.; Schipper, L. A.

    2017-12-01

    Temperature is a crucial factor in determining the rates of ecosystem processes such as leaf respiration (R) - the flux of plant respired carbon dioxide (CO2) from leaves to the atmosphere. Generally, respiration rate increases exponentially with temperature as modelled by the Arrhenius equation, but a recent study (Heskel et al., 2016) showed a universally convergent temperature response of R using an empirical exponential/polynomial model whereby the exponent in the Arrhenius model is replaced by a quadratic function of temperature. The exponential/polynomial model has been used elsewhere to describe shoot respiration and plant respiration. What are the principles that underlie these empirical observations? Here, we demonstrate that macromolecular rate theory (MMRT), based on transition state theory for chemical kinetics, is equivalent to the exponential/polynomial model. We re-analyse the data from Heskel et al. 2016 using MMRT to show this equivalence and thus, provide an explanation based on thermodynamics, for the convergent temperature response of R. Using statistical tools, we also show the equivalent explanatory power of MMRT when compared to the exponential/polynomial model and the superiority of both of these models over the Arrhenius function. Three meaningful parameters emerge from MMRT analysis: the temperature at which the rate of respiration is maximum (the so called optimum temperature, Topt), the temperature at which the respiration rate is most sensitive to changes in temperature (the inflection temperature, Tinf) and the overall curvature of the log(rate) versus temperature plot (the so called change in heat capacity for the system, ). The latter term originates from the change in heat capacity between an enzyme-substrate complex and an enzyme transition state complex in enzyme-catalysed metabolic reactions. From MMRT, we find the average Topt and Tinf of R are 67.0±1.2 °C and 41.4±0.7 °C across global sites. The average curvature (average

  7. Soil respiration rate on the contrasting north- and south-facing slopes of a larch forest in central Siberia

    International Nuclear Information System (INIS)

    Yanagihara, Y.; Koike, T.; Matsuura, Y.; Mori, S.; Shibata, H.; Satoh, F.; Masuyagina, O.V.; Zyryanova, O.A.; Prokushkin, A.S.; Prokushkin, S.G.; Abaimov, A.P.

    2000-01-01

    In an attempt to evaluate global warming effects, we measured the soil respiration of the contrasting north- and south- facing slopes of a larch forest in central Siberia, located at Tura City in the Krasnoyarsk District, Russia. The north-facing slope is assumed to be the present condition while the south-facing slope may stand for the future warm condition. As a result of differences in solar radiation, there were clear differences between the north- and south- facing slopes in terms, for example, of the active layer as the growth rate of larch trees. The soil respiration rate was higher on the south-facing slope than on the north-facing slope. At the temperature of 15°C, soil respiration rate of the south-facing slope was ca. 6.2 μ mol CO 2 * m -2 s -1 , which was about 0.6 times lower than that of broad-leaved forests in Hokkaido. There was an exponential correlation between soil temperature at 10 cm depth and the efflux of CO 2 from the soil surface. Various conditions (soil temperature,. nitrogen content and soil water content) seemed to be more favorable for soil respiration on the south-facing slope. (author)

  8. Influence of cell detachment on the respiration rate of tumor and endothelial cells.

    Science.gov (United States)

    Danhier, Pierre; Copetti, Tamara; De Preter, Géraldine; Leveque, Philippe; Feron, Olivier; Jordan, Bénédicte F; Sonveaux, Pierre; Gallez, Bernard

    2013-01-01

    Cell detachment is a procedure routinely performed in cell culture and a necessary step in many biochemical assays including the determination of oxygen consumption rates (OCR) in vitro. In vivo, cell detachment has been shown to exert profound metabolic influences notably in cancer but also in other pathologies, such as retinal detachment for example. In the present study, we developed and validated a new technique combining electron paramagnetic resonance (EPR) oximetry and the use of cytodex 1 and collagen-coated cytodex 3 dextran microbeads, which allowed the unprecedented comparison of the OCR of adherent and detached cells with high sensitivity. Hence, we demonstrated that both B16F10 melanoma cells and human umbilical vein endothelial cells (HUVEC) experience strong OCR decrease upon trypsin or collagenase treatments. The reduction of cell oxygen consumption was more pronounced with a trypsin compared to a collagenase treatment. Cells remaining in suspension also encounter a marked intracellular ATP depletion and an increase in the lactate production/glucose uptake ratio. These findings highlight the important influence exerted by cell adhesion/detachment on cell respiration, which can be probed with the unprecedented experimental assay that was developed and validated in this study.

  9. Influence of Cell Detachment on the Respiration Rate of Tumor and Endothelial Cells

    Science.gov (United States)

    Danhier, Pierre; Copetti, Tamara; De Preter, Géraldine; Leveque, Philippe; Feron, Olivier; Jordan, Bénédicte F.; Sonveaux, Pierre; Gallez, Bernard

    2013-01-01

    Cell detachment is a procedure routinely performed in cell culture and a necessary step in many biochemical assays including the determination of oxygen consumption rates (OCR) in vitro. In vivo, cell detachment has been shown to exert profound metabolic influences notably in cancer but also in other pathologies, such as retinal detachment for example. In the present study, we developed and validated a new technique combining electron paramagnetic resonance (EPR) oximetry and the use of cytodex 1 and collagen-coated cytodex 3 dextran microbeads, which allowed the unprecedented comparison of the OCR of adherent and detached cells with high sensitivity. Hence, we demonstrated that both B16F10 melanoma cells and human umbilical vein endothelial cells (HUVEC) experience strong OCR decrease upon trypsin or collagenase treatments. The reduction of cell oxygen consumption was more pronounced with a trypsin compared to a collagenase treatment. Cells remaining in suspension also encounter a marked intracellular ATP depletion and an increase in the lactate production/glucose uptake ratio. These findings highlight the important influence exerted by cell adhesion/detachment on cell respiration, which can be probed with the unprecedented experimental assay that was developed and validated in this study. PMID:23382841

  10. Ocean-scale patterns in community respiration rates along continuous transects across the Pacific Ocean.

    Science.gov (United States)

    Wilson, Jesse M; Severson, Rodney; Beman, J Michael

    2014-01-01

    Community respiration (CR) of organic material to carbon dioxide plays a fundamental role in ecosystems and ocean biogeochemical cycles, as it dictates the amount of production available to higher trophic levels and for export to the deep ocean. Yet how CR varies across large oceanographic gradients is not well-known: CR is measured infrequently and cannot be easily sensed from space. We used continuous oxygen measurements collected by autonomous gliders to quantify surface CR rates across the Pacific Ocean. CR rates were calculated from changes in apparent oxygen utilization and six different estimates of oxygen flux based on wind speed. CR showed substantial spatial variation: rates were lowest in ocean gyres (mean of 6.93 mmol m(-3) d(-1)±8.0 mmol m(-3) d(-1) standard deviation in the North Pacific Subtropical Gyre) and were more rapid and more variable near the equator (8.69 mmol m(-3) d(-1)±7.32 mmol m(-3) d(-1) between 10°N and 10°S) and near shore (e.g., 5.62 mmol m(-3) d(-1)±45.6 mmol m(-3) d(-1) between the coast of California and 124°W, and 17.0 mmol m(-3) d(-1)±13.9 mmol m(-3) d(-1) between 156°E and the Australian coast). We examined how CR varied with coincident measurements of temperature, turbidity, and chlorophyll concentrations (a proxy for phytoplankton biomass), and found that CR was weakly related to different explanatory variables across the Pacific, but more strongly related to particular variables in different biogeographical areas. Our results indicate that CR is not a simple linear function of chlorophyll or temperature, and that at the scale of the Pacific, the coupling between primary production, ocean warming, and CR is complex and variable. We suggest that this stems from substantial spatial variation in CR captured by high-resolution autonomous measurements.

  11. Insights Gained from the Dehalococcoides ethenogenes Strain 195’s Transcriptome Responding to a Wide Range of Respiration Rates and Substrate Types

    Science.gov (United States)

    2012-04-01

    fermented yeast , pure hydrogen, or endogenous biomass decay). When similarly respiring (~120 ?eeq PCE/(L-hr)) batch and PSS cultures were contrasted, the...REPORT Insights gained from the “Dehalococcoides ethenogenes” strain 195?s transcriptome responding to a wide range of respiration rates and substrate...types. 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Bacteria of the group “Dehalococcoides” display the ability to respire recalcitrant chlorinated

  12. Temperature sensitivity of soil respiration rates enhanced by microbial community response.

    Science.gov (United States)

    Karhu, Kristiina; Auffret, Marc D; Dungait, Jennifer A J; Hopkins, David W; Prosser, James I; Singh, Brajesh K; Subke, Jens-Arne; Wookey, Philip A; Agren, Göran I; Sebastià, Maria-Teresa; Gouriveau, Fabrice; Bergkvist, Göran; Meir, Patrick; Nottingham, Andrew T; Salinas, Norma; Hartley, Iain P

    2014-09-04

    Soils store about four times as much carbon as plant biomass, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide. Short-term experiments have shown that soil microbial respiration increases exponentially with temperature. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing temperatures has the potential to either decrease or increase warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the temperature sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) temperature sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the temperature sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted.

  13. Exploration of Elastic Scattering Rates for Supersymmetric Dark Matter

    CERN Document Server

    Ellis, Jonathan Richard; Olive, Keith A; Ellis, John

    2001-01-01

    We explore the possible cross sections for the elastic scattering of neutralinos chi on nucleons p,n in the minimal supersymmetric extension of the standard model (MSSM). Universality of the soft supersymmetry-breaking scalar masses for the Higgs multiplets is not assumed, but the MSSM parameters are nevertheless required to lead consistently to an electroweak vacuum. We explore systematically the region of MSSM parameter space where LEP and other accelerator constraints are respected, and the relic neutralino density lies in the range 0.1 < Omega_chi h^2 < 0.3 preferred by cosmology. We also discuss models with Omega_chi h^2 < 0.1, in which case we scale the density of supersymmetric dark matter in our galactic halo by Omega_chi h^2 / 0.1, allowing for the possible existence of some complementary form of cold dark matter. We find values of the cross sections that are considerably lower than the present experimental sensitivities. At low neutralino masses, m_chi < 100 GeV, the cross sections may b...

  14. Ocean-scale patterns in community respiration rates along continuous transects across the Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Jesse M Wilson

    Full Text Available Community respiration (CR of organic material to carbon dioxide plays a fundamental role in ecosystems and ocean biogeochemical cycles, as it dictates the amount of production available to higher trophic levels and for export to the deep ocean. Yet how CR varies across large oceanographic gradients is not well-known: CR is measured infrequently and cannot be easily sensed from space. We used continuous oxygen measurements collected by autonomous gliders to quantify surface CR rates across the Pacific Ocean. CR rates were calculated from changes in apparent oxygen utilization and six different estimates of oxygen flux based on wind speed. CR showed substantial spatial variation: rates were lowest in ocean gyres (mean of 6.93 mmol m(-3 d(-1±8.0 mmol m(-3 d(-1 standard deviation in the North Pacific Subtropical Gyre and were more rapid and more variable near the equator (8.69 mmol m(-3 d(-1±7.32 mmol m(-3 d(-1 between 10°N and 10°S and near shore (e.g., 5.62 mmol m(-3 d(-1±45.6 mmol m(-3 d(-1 between the coast of California and 124°W, and 17.0 mmol m(-3 d(-1±13.9 mmol m(-3 d(-1 between 156°E and the Australian coast. We examined how CR varied with coincident measurements of temperature, turbidity, and chlorophyll concentrations (a proxy for phytoplankton biomass, and found that CR was weakly related to different explanatory variables across the Pacific, but more strongly related to particular variables in different biogeographical areas. Our results indicate that CR is not a simple linear function of chlorophyll or temperature, and that at the scale of the Pacific, the coupling between primary production, ocean warming, and CR is complex and variable. We suggest that this stems from substantial spatial variation in CR captured by high-resolution autonomous measurements.

  15. Heat stress of two tropical seagrass species during low tides - impact on underwater net photosynthesis, dark respiration and diel in situ internal aeration

    DEFF Research Database (Denmark)

    Pedersen, Ole; Colmer, Timothy D.; Borum, Jens

    2016-01-01

    Seagrasses grow submerged in aerated seawater but often in low O2 sediments. Elevated temperatures and low O2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides, growing with extreme tides and diel temperature amplitudes....... Temperature effects on net photosynthesis (PN) and dark respiration (RD) of leaves were evaluated. Daytime low tide was characterized by high pO2 (54 kPa), pH (8.8) and temperature (38°C) in shallow pools. As PN was maximum at 33°C (9.1 and 7.2 μmol O2 m-2 s-1 in T. hemprichii and E. acoroides, respectively......), the high temperatures and reduced CO2 would have diminished PN, whereas RD increased (Q10 of 2.0-2.7) above that at 33°C (0.45 and 0.33 μmol O2 m-2 s-1, respectively). During night-time low tides, O2 declined resulting in shoot base anoxia in both species, but incoming water containing c. 20 kPa O2...

  16. Relict Mountain Permafrost Area (Loess Plateau, China) Exhibits High Ecosystem Respiration Rates and Accelerating Rates in Response to Warming

    Science.gov (United States)

    Mu, Cuicui; Wu, Xiaodong; Zhao, Qian; Smoak, Joseph M.; Yang, Yulong; Hu, Lian; Zhong, Wen; Liu, Guimin; Xu, Haiyan; Zhang, Tingjun

    2017-10-01

    Relict permafrost regions are characterized by thin permafrost and relatively high temperatures. Understanding the ecosystem respiration rate (ERR) and its relationship with soil hydrothermal conditions in these areas can provide knowledge regarding the permafrost carbon cycle in a warming world. In this study, we examined a permafrost area, a boundary area, and a seasonally frozen ground area within a relict permafrost region on the east edge of the Qinghai-Tibetan Plateau, China. Measurements from July 2015 to September 2016 showed that the mean annual ecosystem CO2 emissions for the boundary area were greater than the permafrost area. The Q10 value of the ERRs in the seasonally frozen ground area was greater than the permafrost area, indicating that the carbon emissions in the nonpermafrost areas were more sensitive to warming. The 1 year open-top chamber (OTC) warming increased soil temperatures in both the permafrost and seasonally frozen ground areas throughout the year, and the warming increased the ERRs by 1.18 (0.99-1.38, with interquartile range) and 1.13 (0.75-1.54, with interquartile range) μmol CO2 m-2 s-1 in permafrost and seasonally frozen ground areas, respectively. The OTC warming increased annual ERRs by approximately 50% for both permafrost and seasonally frozen ground areas with half the increase occurring during the nongrowing seasons. These results suggest that the ERRs in relict permafrost are high in comparison with arctic regions, and the carbon balance in relict permafrost areas could be greatly changed by climate warming.

  17. A pilot study of the nocturnal respiration rates in COPD patients in the home environment using a non-contact biomotion sensor

    International Nuclear Information System (INIS)

    Ballal, Tarig; Zaffaroni, Alberto; Heneghan, Conor; Shouldice, Redmond; Boyle, Patricia; McNicholas, Walter T; De Chazal, Philip; Donnelly, Seamas C

    2014-01-01

    Nocturnal respiration rate parameters were collected from 20 COPD subjects over an 8 week period, to determine if changes in respiration rate were associated with exacerbations of COPD. These subjects were primarily GOLD Class 2 to 4, and had been recently discharged from hospital following a recent exacerbation. The respiration rates were collected using a non-contact radio-frequency biomotion sensor which senses respiratory effort and body movement using a short-range radio-frequency sensor. An adaptive notch filter was applied to the measured signal to determine respiratory rate over rolling 15 s segments. The accuracy of the algorithm was initially verified using ten manually-scored 15 min segments of respiration extracted from overnight polysomnograms. The calculated respiration rates were within 1 breath min −1 for >98% of the estimates. For the 20 subjects monitored, 11 experienced one or more subsequent exacerbation of COPD (ECOPD) events during the 8 week monitoring period (19 events total). Analysis of the data revealed a significant increase in nocturnal respiration rate (e.g. >2 breath min −1 ) prior to many ECOPD events. Using a simple classifier of a change of 1 breath min −1 in the mode of the nocturnal respiration rate, a predictive rule showed a sensitivity of 63% and specificity of 85% for predicting an exacerbation within a 5 d window. We conclude that it is possible to collect respiration rates reliably in the home environment, and that the respiration rate may be a potential indicator of change in clinical status. (paper)

  18. Rates of Litter Decomposition and Soil Respiration in Relation to Soil Temperature and Water in Different-Aged Pinus massoniana Forests in the Three Gorges Reservoir Area, China

    Science.gov (United States)

    Zeng, Lixiong; Huang, Zhilin; Lei, Jingpin; Zhou, Benzhi; Li, Maihe

    2014-01-01

    To better understand the soil carbon dynamics and cycling in terrestrial ecosystems in response to environmental changes, we studied soil respiration, litter decomposition, and their relations to soil temperature and soil water content for 18-months (Aug. 2010–Jan. 2012) in three different-aged Pinus massoniana forests in the Three Gorges Reservoir Area, China. Across the experimental period, the mean total soil respiration and litter respiration were 1.94 and 0.81, 2.00 and 0.60, 2.19 and 0.71 µmol CO2 m−2 s−1, and the litter dry mass remaining was 57.6%, 56.2% and 61.3% in the 20-, 30-, and 46-year-old forests, respectively. We found that the temporal variations of soil respiration and litter decomposition rates can be well explained by soil temperature at 5 cm depth. Both the total soil respiration and litter respiration were significantly positively correlated with the litter decomposition rates. The mean contribution of the litter respiration to the total soil respiration was 31.0%–45.9% for the three different-aged forests. The present study found that the total soil respiration was not significantly affected by forest age when P. masonniana stands exceed a certain age (e.g. >20 years old), but it increased significantly with increased soil temperature. Hence, forest management strategies need to protect the understory vegetation to limit soil warming, in order to reduce the CO2 emission under the currently rapid global warming. The contribution of litter decomposition to the total soil respiration varies across spatial and temporal scales. This indicates the need for separate consideration of soil and litter respiration when assessing the climate impacts on forest carbon cycling. PMID:25004164

  19. Heat stress of two tropical seagrass species during low tides - impact on underwater net photosynthesis, dark respiration and diel in situ internal aeration.

    Science.gov (United States)

    Pedersen, Ole; Colmer, Timothy D; Borum, Jens; Zavala-Perez, Andrea; Kendrick, Gary A

    2016-06-01

    Seagrasses grow submerged in aerated seawater but often in low O2 sediments. Elevated temperatures and low O2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides, growing with extreme tides and diel temperature amplitudes. Temperature effects on net photosynthesis (PN ) and dark respiration (RD ) of leaves were evaluated. Daytime low tide was characterized by high pO2 (54 kPa), pH (8.8) and temperature (38°C) in shallow pools. As PN was maximum at 33°C (9.1 and 7.2 μmol O2  m(-2) s(-1) in T. hemprichii and E. acoroides, respectively), the high temperatures and reduced CO2 would have diminished PN , whereas RD increased (Q10 of 2.0-2.7) above that at 33°C (0.45 and 0.33 μmol O2  m(-2)  s(-1) , respectively). During night-time low tides, O2 declined resulting in shoot base anoxia in both species, but incoming water containing c. 20 kPa O2 relieved the anoxia. Shoots exposed to 40°C for 4 h showed recovery of PN and RD , whereas 45°C resulted in leaf damage. These seagrasses are 'living near the edge', tolerant of current diel O2 and temperature extremes, but if temperatures rise both species may be threatened in this habitat. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  20. Effects of minimal processing on the respiration rate and quality of rambutan cv. ‘Rong-Rien’

    Directory of Open Access Journals (Sweden)

    Buncha Ooraikul

    2008-04-01

    Full Text Available Respiration rate at 4oC and minimal processing of rambutan cv. ‘Rong-Rien’ were investigated. Rambutan was harvested from Amphur Ban Na San, Surat Thani Province, at the stage when its skin was turning into a combination of red, green and yellow. After harvesting, the fruits were size-graded to 27-30 fruits/kg, hydrocooled to 14oC, packed with ice in Styrofoam boxes and transported to the laboratory at Prince of Songkla University within 6 h. The respiration rate of fresh rambutan fruits was monitored. For minimal processing, the fruits were soaked in warm solution (55oC of 100 ppm sodium hypochlorite for one min and immediately cooled in cold water until their internal temperature reached 14oC. The minimal process included peeling, with and without coring. The peeled and peeled and cored rambutan samples were immersed in a solution of 0.5% citric acid + 0.5% CaCl2 at 4oC for 2 min. The average respiration rates (within 6 h at 4oC of whole fruit, peeled, and peeled and cored rambutan samples were measured and found to be 122, 134 and 143 mg CO2/kg/h, respectively. These findings indicated that a preparation style as peeled rambutan without coring, nylon/LLDPE bag, storage temperature of 4.0±1oC, were suitably applied for processed rambutans. To obtain a longer extended shelf life (>12 days of minimally processed peeled rambutans, further study on food additives, including acidulants and preservative used and gas composition in modified atmosphere packaging (MAP is needed.

  1. Fluctuations and dark count rates in superconducting NbN single-photon detectors

    International Nuclear Information System (INIS)

    Engel, Andreas; Semenov, Alexei; Huebers, Heinz-Wilhelm; Il'in, Kostya; Siegel, Michael

    2005-01-01

    We measured the temperature- and current-dependence of dark count rates of a superconducting singlephoton detector. The detector's key element is a 84 nm wide meander strip line fabricated from a 5 nm thick NbN film. Due to its reduced dimensions various types of fluctuations can cause temporal and localized transitions into a resistive state leading to dark count events. Adopting a recent refinement of the hotspot model we achieve a satisfying description of the experimental dark count rates taking into account fluctuations of the Cooper-pair density and current-assisted unbinding of vortex-antivortex pairs. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Dark matter relics and the expansion rate in scalar-tensor theories

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Bhaskar; Jimenez, Esteban [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Zavala, Ivonne, E-mail: dutta@physics.tamu.edu, E-mail: este1985@physics.tamu.edu, E-mail: e.i.zavalacarrasco@swansea.ac.uk [Department of Physics, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2017-06-01

    We study the impact of a modified expansion rate on the dark matter relic abundance in a class of scalar-tensor theories. The scalar-tensor theories we consider are motivated from string theory constructions, which have conformal as well as disformally coupled matter to the scalar. We investigate the effects of such a conformal coupling to the dark matter relic abundance for a wide range of initial conditions, masses and cross-sections. We find that exploiting all possible initial conditions, the annihilation cross-section required to satisfy the dark matter content can differ from the thermal average cross-section in the standard case. We also study the expansion rate in the disformal case and find that physically relevant solutions require a nontrivial relation between the conformal and disformal functions. We study the effects of the disformal coupling in an explicit example where the disformal function is quadratic.

  3. A single dose of dark chocolate increases parasympathetic modulation and heart rate variability in healthy subjects

    Directory of Open Access Journals (Sweden)

    Ana Amélia Machado DUARTE

    Full Text Available ABSTRACT Objective: The aim of this study was to investigate the acute effect of a single dose of dark chocolate (70% cocoa on blood pressure and heart rate variability. Methods: Thirty-one healthy subjects (aged 18-25 years; both sexes were divided into two groups: 10 subjects in the white chocolate (7.4 g group and 21 in the dark chocolate (10 g group; measurements were performed at the university's physiology lab. An electrocardiogram measured the sympathovagal balance by spectral and symbolic analysis. Results: A single dose of dark chocolate significantly reduced systolic blood pressure and heart rate. After consuming 10 g of dark chocolate, significant increases were observed for heart rate variability, standard deviation of RR intervals standard deviation of all NN intervals, square root of the mean squared differences between adjacent normal RR intervals root mean square of successive differences, and an increase in the high frequency component in absolute values, representing the parasympathetic modulation. Conclusion: In conclusion the importance of our results lies in the magnitude of the response provoked by a single dose of cocoa. Just 10 g of cocoa triggered a significant increase in parasympathetic modulation and heart rate variability. These combined effects can potentially increase life expectancy because a reduction in heart rate variability is associated with several cardiovascular diseases and higher mortality.

  4. Dependence of wheat and rice respiration on tissue nitrogen and the corresponding net carbon fixation efficiency under different rates of nitrogen application

    Science.gov (United States)

    Sun, Wenjuan; Huang, Yao; Chen, Shutao; Zou, Jianwen; Zheng, Xunhua

    2007-02-01

    To quantitatively address the role of tissue N in crop respiration under various agricultural practices, and to consequently evaluate the impact of synthetic fertilizer N application on biomass production and respiration, and hence net carbon fixation efficiency ( E ncf), pot and field experiments were carried out for an annual rotation of a rice-wheat cropping system from 2001 to 2003. The treatments of the pot experiments included fertilizer N application, sowing date and planting density. Different rates of N application were tested in the field experiments. Static opaque chambers were used for sampling the gas. The respiration as CO2 emission was detected by a gas chromatograph. A successive biomass clipping method was employed to determine the crop autotrophic respiration coefficient ( R a). Results from the pot experiments revealed a linear relationship between R a and tissue N content as R a = 4.74N-1.45 ( R 2 = 0.85, P < 0.001). Measurements and calculations from the field experiments indicated that fertilizer N application promoted not only biomass production but also increased the respiration of crops. A further investigation showed that the increase of carbon loss in terms of respiration owing to fertilizer N application exceeded that of net carbon gain in terms of aboveground biomass when fertilizer N was applied over a certain rate. Consequently, the E ncf declined as the N application rate increased.

  5. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis) and C4 (Chloris virgata and Hemarthria altissima) Grasses in Northeast China

    OpenAIRE

    Zhong, Shangzhi; Chai, Hua; Xu, Yueqiao; Li, Yan; Ma, Jian-Ying; Sun, Wei

    2017-01-01

    Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO2 (δ13Cl) and respiratory apparent isotope fractionation relative to biomass (ΔR,biomass) in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C3-C4 mixed ecosystem C fluxes. We measured δ13Cl, the δ13C of biomass and of potential respiratory substrates and leaf gas exchange in one C3 ...

  6. Changes in δ(13)C of dark respired CO2 and organic matter of different organs during early ontogeny in peanut plants.

    Science.gov (United States)

    Ghashghaie, Jaleh; Badeck, Franz W; Girardin, Cyril; Sketriené, Diana; Lamothe-Sibold, Marlène; Werner, Roland A

    2015-01-01

    Carbon isotope composition in respired CO2 and organic matter of individual organs were measured on peanut seedlings during early ontogeny in order to compare fractionation during heterotrophic growth and transition to autotrophy in a species with lipid seed reserves with earlier results obtained on beans. Despite a high lipid content in peanut seeds (48%) compared with bean seeds (1.5%), the isotope composition of leaf- and root-respired CO2 as well as its changes during ontogeny were similar to already published data on bean seedlings: leaf-respired CO2 became (13)C-enriched reaching -21.5‰, while root-respired CO2 became (13)C-depleted reaching around -31‰ at the four-leaf stage. The opposite respiratory fractionation in leaves vs. roots already reported for C3 herbs was thus confirmed for peanuts. However, contrarily to beans, the peanut cotyledon-respired CO2 was markedly (13)C-enriched, and its (13)C-depletion was noted from the two-leaf stage onwards only. Carbohydrate amounts being very low in peanut seeds, this cannot be attributed solely to their use as respiratory substrate. The potential role of isotope fractionation during glyoxylate cycle and/or gluconeogenesis on the (13)C-enriched cotyledon-respired CO2 is discussed.

  7. High dark inorganic carbon fixation rates by specific microbial groups in the Atlantic off the Galician coast (NW Iberian margin)

    NARCIS (Netherlands)

    Guerrero-Feijóo, E.; Sintes, E.; Herndl, G.J.; Varela, M.M.

    2018-01-01

    Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production

  8. Toward the definition of a carbon budget model: seasonal variation and temperature effect on respiration rate of vegetative and reproductive organs of pistachio trees (Pistacia vera).

    Science.gov (United States)

    Marra, Francesco P; Barone, Ettore; La Mantia, Michele; Caruso, Tiziano

    2009-09-01

    This study, as a preliminary step toward the definition of a carbon budget model for pistachio trees (Pistacia vera L.), aimed at estimating and evaluating the dynamics of respiration of vegetative and reproductive organs of pistachio tree. Trials were performed in 2005 in a commercial orchard located in Sicily (370 m a.s.l.) on five bearing 20-year-old pistachio trees of cv. Bianca grafted onto Pistachio terebinthus L. Growth analyses and respiration measurements were done on vegetative (leaf) and reproductive (infructescence) organs during the entire growing season (April-September) at biweekly intervals. Results suggested that the respiration rates of pistachio reproductive and vegetative organs were related to their developmental stage. Both for leaf and for infructescence, the highest values were observed during the earlier stages of growth corresponding to the phases of most intense organ growth. The sensitivity of respiration activity to temperature changes, measured by Q(10), showed an increase throughout the transition from immature to mature leaves, as well as during fruit development. The data collected were also used to estimate the seasonal carbon loss by respiration activity for a single leaf and a single infructescence. The amount of carbon lost by respiration was affected by short-term temperature patterns, organ developmental stage and tissue function.

  9. Adaptive radiation along a thermal gradient: preliminary results of habitat use and respiration rate divergence among whitefish morphs.

    Directory of Open Access Journals (Sweden)

    Kimmo Kalevi Kahilainen

    Full Text Available Adaptive radiation is considered an important mechanism for the development of new species, but very little is known about the role of thermal adaptation during this process. Such adaptation should be especially important in poikilothermic animals that are often subjected to pronounced seasonal temperature variation that directly affects metabolic function. We conducted a preliminary study of individual lifetime thermal habitat use and respiration rates of four whitefish (Coregonus lavaretus (L. morphs (two pelagic, one littoral and one profundal using stable carbon and oxygen isotope values of otolith carbonate. These morphs, two of which utilized pelagic habitats, one littoral and one profundal recently diverged via adaptive radiation to exploit different major niches in a deep and thermally stratified subarctic lake. We found evidence that the morphs used different thermal niches. The profundal morph had the most distinct thermal niche and consistently occupied the coldest thermal habitat of the lake, whereas differences were less pronounced among the shallow water pelagic and littoral morphs. Our results indicated ontogenetic shifts in thermal niches: juveniles of all whitefish morphs inhabited warmer ambient temperatures than adults. According to sampling of the otolith nucleus, hatching temperatures were higher for benthic compared to pelagic morphs. Estimated respiration rate was the lowest for benthivorous profundal morph, contrasting with the higher values estimated for the other morphs that inhabited shallower and warmer water. These preliminary results suggest that physiological adaptation to different thermal habitats shown by the sympatric morphs may play a significant role in maintaining or strengthening niche segregation and divergence in life-history traits, potentially contributing to reproductive isolation and incipient speciation.

  10. Predawn respiration rates during flowering are highly predictive of yield response in Gossypium hirsutum when yield variability is water-induced

    Science.gov (United States)

    Respiratory carbon evolution by leaves under abiotic stress is implicated as a major limitation to crop productivity; however, respiration rates of fully expanded leaves are positively associated with plant growth rates. Given the substantial sensitivity of plant growth to drought, it was hypothesiz...

  11. Gaseous elemental mercury emissions and CO2 respiration rates in terrestrial soils under controlled aerobic and anaerobic laboratory conditions

    International Nuclear Information System (INIS)

    Obrist, Daniel; Fain, Xavier; Berger, Carsen

    2010-01-01

    Mercury (Hg) levels in terrestrial soils are linked to the presence of organic carbon (C). Carbon pools are highly dynamic and subject to mineralization processes, but little is known about the fate of Hg during decomposition. This study evaluated relationships between gaseous Hg emissions from soils and carbon dioxide (CO 2 ) respiration under controlled laboratory conditions to assess potential losses of Hg to the atmosphere during C mineralization. Results showed a linear correlation (r 2 = 0.49) between Hg and CO 2 emissions in 41 soil samples, an effect unlikely to be caused by temperature, radiation, different Hg contents, or soil moisture. Stoichiometric comparisons of Hg/C ratios of emissions and underlying soil substrates suggest that 3% of soil Hg was subject to evasion. Even minute emissions of Hg upon mineralization, however, may be important on a global scale given the large Hg pools sequestered in terrestrial soils and C stocks. We induced changes in CO 2 respiration rates and observed Hg flux responses, including inducement of anaerobic conditions by changing chamber air supply from N 2 /O 2 (80% and 20%, respectively) to pure N 2 . Unexpectedly, Hg emissions almost quadrupled after O 2 deprivation while oxidative mineralization (i.e., CO 2 emissions) was greatly reduced. This Hg flux response to anaerobic conditions was lacking when repeated with sterilized soils, possibly due to involvement of microbial reduction of Hg 2+ by anaerobes or indirect abiotic effects such as alterations in soil redox conditions. This study provides experimental evidence that Hg volatilization, and possibly Hg 2+ reduction, is related to O 2 availability in soils from two Sierra Nevada forests. If this result is confirmed in soils from other areas, the implication is that Hg volatilization from terrestrial soils is partially controlled by soil aeration and that low soil O 2 levels and possibly low soil redox potentials lead to increased Hg volatilization from soils.

  12. Respirator Filter Efficiency Testing Against Particulate and Biological Aerosols Under Moderate to High Flow Rates

    Science.gov (United States)

    2006-08-01

    flow rate through the test filter. The flow rate was measured using a mass flow meter (Series 4000, TSI, Shoreview, MN). Several modifications were made...operating conditions. This included assessing the effect of non- isokinetic sampling, flow calibrations, and characterization of the challenge...sampling bias on the measured penetrations due to the non- isokinetic sampling downstream. 3.3.2.2 System Characterization. Shakedown tests were

  13. Net CO2 exchange rates in three different successional stages of the 'Dark Taiga' of central Siberia

    International Nuclear Information System (INIS)

    Roeser, C.; Schulze, E.D.; Montagnani, L.

    2002-01-01

    The net ecosystem exchange (NEE) of successional stages of the Abies-dominated dark taiga was measured in central Siberia (61 deg N, 90 deg E) during the growing season of the year 2000 using the eddy covariance technique. Measurements started before snow melt and canopy activity in spring on day of year (DOY) 99 and lasted until a permanent snow cover had developed and respiration had ceased in autumn DOY 299. Three stands growing in close vicinity were investigated: 50 yr-old Betula pubescens ('Betula stand', an early successional stage after fire), 250 yr-old mixed boreal forest, representing the transition from Betula-dominated to Abies-dominated canopies, and 200-yr-old Abies sibirica ('Abies stand', representing a late successional stage following the mixed boreal forest). The mixed boreal forest had a multi-layered canopy with dense under story and trees of variable height and age below the main canopy, which was dominated by Abies sibirica, Picea obovata and few old Betula pubescens and Populus tremula trees. The Abies stand had a uniform canopy dominated by Abies sibirica. This stand appears to have established not after fire but after wind break or insect damage in a later successional stage. The stands differed with respect to the number of days with net CO 2 uptake (Betula stand 89 days, mixed boreal forest 109 days, and Abies stand 135 days), maximum measured LAI (Betula 2.6 m 2 /m 2 , mixed boreal forest 3.5 m 2 /m 2 and Abies stand 4.1 m 2 /m 2 ) and basal area (Betula stand 30.2 m 2 /ha, mixed boreal forest 35.7 m 2 /ha, and Abies stand 46.5 m 2 /ha). In the mixed boreal forest, many days with net daytime CO 2 release were observed in summer. Both other sites were almost permanent sinks in summer. Mean daytime CO 2 exchange rates in July were 8.45 mol/m 2 /s in the Betula stand, 4.65 mol/m 2 /s in the mixed boreal forest and 6.31 mol/m 2 /s in the Abies stand. Measured uptake for the growing season was 247.2 g C/m 2 in the Betula stand, 99.7 g C/m 2

  14. Determination of respiration rates in water with sub-micromolar oxygen concentrations

    Directory of Open Access Journals (Sweden)

    Emilio Garcia-Robledo

    2016-11-01

    Full Text Available It is crucial for our study and understanding of element transformations in low-oxygen waters that we are able to reproduce the in situ conditions during laboratory incubations to an extent that does not result in unacceptable artefacts. In this study we have explored how experimental conditions affect measured rates of O2 consumption in low-O2 waters from the anoxic basin of Golfo Dulce (Costa Rica and oceanic waters off Chile-Peru. High-sensitivity optode dots placed within all-glass incubation containers allowed for high resolution O2 concentration measurements in the nanomolar and low µmolar range and thus also for the determination of rates of oxygen consumption by microbial communities. Consumption rates increased dramatically (from 3 and up to 60 times by prolonged incubations, and started to increase after 4-5 hours in surface waters and after 10-15 h in water from below the upper mixed layer. Estimated maximum growth rates during the incubations suggest the growth of opportunistic microorganism with doubling times as low as 2.8 and 4.6 h for the coastal waters of Golfo Dulce (Costa Rica and oceanic waters off Chile and Peru, respectively. Deoxygenation by inert gas bubbling led to increases in subsequently determined rates, possibly by liberation of organics from lysis of sensitive organisms, particle or aggregate alterations or other processes mediated by the strong turbulence. Stirring of the water during the incubation led to an about 50% increase in samples previously deoxygenated by bubbling, but had no effect in untreated samples. Our data indicate that data for microbial activity obtained by short incubations of minimally manipulated water are most reliable, but deoxygenation is a prerequisite for many laboratory experiments, such as determination of denitrification rates, as O2 contamination by sampling is practically impossible to avoid.

  15. Direct SUSY dark matter detection-theoretical rates due to the spin

    International Nuclear Information System (INIS)

    Vergados, J D

    2004-01-01

    The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Thus direct dark matter detection, consisting of detecting the recoiling nucleus, is central to particle physics and cosmology. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). The relevant cross sections arise out of two mechanisms: (i) the coherent mode, due to the scalar interaction and (ii) the spin contribution arising from the axial current. In this paper we will focus on the spin contribution, which is expected to dominate for light targets. For both modes it is possible to obtain detectable rates, but in most models the expected rates are much lower than the present experimental goals. So one should exploit two characteristic signatures of the reaction, namely the modulation effect and in directional experiments the correlation of the event rates with the sun's motion. In standard non-directional experiments the modulation is small, less than 2 per cent. In the case of the directional event rates we would like to suggest that the experiments exploit two features of the process, which are essentially independent of the SUSY model employed, namely: (1) the forward-backward asymmetry, with respect to the sun's direction of motion, is very large and (2) the modulation is much larger, especially if the observation is made in a plane perpendicular to the sun's velocity. In this case the difference between maximum and minimum can be larger than 40 per cent and the phase of the earth at the maximum is direction dependent

  16. Effect of the Storage Temperature, Duration and Gamma Irradiation on the Respiration Rate and Sugar Content of Minituber 'Superior'

    International Nuclear Information System (INIS)

    Lim, J.H.; Hwangbo, J.K.; Baek, M.H.; Kim, J.H.; Kim, J.S.; Lee, M.C.

    2005-01-01

    This study was to evaluate whether ionizing gamma radiation could be applied to break the dormancy of a potato minituber. The respiration rate of the minitubers was significantly affected by the storage temperature and a low dose gamma radiation. Ionizing radiation of 8 Gy enhanced the respiration rate of the potato tuber stored at 10°C for 20 days. The potato tuber subjected to 4 and 8 Gy after 40 days storage at 10 and 10°C exhibited higher respiration rates compared to the control (non-irradiated), but not at st. However, the ionizing radiation did not exhibit on significant effect on the respiration rate of the potato tuber stored for 60 days. It was observed that minitubers stored for 20 days had significant response to the storage temperature in terms of the total sugar content the higher the storage temperature, the lower the total sugar content. It was measured that the reducing sugar content was increased under the storage conditions both 5 and 10°C for 40 days, but not to 20°C. The total sugar contents in the minituber stored for 60 days were similar to those stored for 40 days. The data was discussed on the relationships among the storage duration, temperature and ionizing radiation. (author)

  17. Evaluating a new method to estimate the rate of leaf respiration in the light by analysis of combined gas exchange and chlorophyll fluorescence measurements

    NARCIS (Netherlands)

    Yin, X.; Sun, Z.; Struik, P.C.; Gu, J.

    2011-01-01

    Day respiration (R(d)) is an important parameter in leaf ecophysiology. It is difficult to measure directly and is indirectly estimated from gas exchange (GE) measurements of the net photosynthetic rate (A), commonly using the Laisk method or the Kok method. Recently a new method was proposed to

  18. Ecosystem function in oil sands wetlands : rates of detrital decomposition, moss growth, and microbial respiration in oilsands wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Wytrykush, C. [Windsor Univ., ON (Canada); Hornung, J. [Petro-Canada, Calgary, AB (Canada)

    2007-07-01

    A study was conducted in which leaf litter breakdown and biomass accrual in 31 reference and oilsands affected (OSPM) wetlands in Northeastern Alberta was examined. The purpose was to determine how the decomposition of dead plant matter controls the primary productivity in wetlands. The data collected from this study will provide information about carbon flow and dynamics in oilsands affected wetlands. The study involved the investigation of wetlands that contrasted in water origin (OSPM vs. reference), sediment origin (OSPM vs. natural), sediment organic content and age. Mesh bags containing 5 g of dried Typha (cattail) or 20 g of damp moss were placed into 31 wetlands in order to monitor the rate at which biomass was lost to decomposition, as measured by changes in dry mass. After 1 year, moss growth was found to be greatest in younger wetlands with natural sediments. Cattail decomposition was found to be slower in wetlands containing OSPM water than that in reference wetlands. Preliminary analysis of respiration rates of biota associated with decomposing cattail indicate that the amount of oxygen consumed is not affected by wetland water source, sediment source, level of initial sediment organic content, or age.

  19. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

    Directory of Open Access Journals (Sweden)

    M. H. Iversen

    2010-09-01

    Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d−1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d−1 and 0.20 d−1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m−1 and 0.0030 m−1, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

  20. The effect of airflow rates and aeration mode on the respiration activity of four organic wastes: Implications on the composting process.

    Science.gov (United States)

    Mejias, Laura; Komilis, Dimitrios; Gea, Teresa; Sánchez, Antoni

    2017-07-01

    The aim of this study was to assess the effect of the airflow and of the aeration mode on the composting process of non-urban organic wastes that are found in large quantities worldwide, namely: (i) a fresh, non-digested, sewage sludge (FSS), (ii) an anaerobically digested sewage sludge (ADSS), (iii) cow manure (CM) and (iv) pig sludge (PS). This assessment was done using respirometric indices. Two aeration modes were tested, namely: (a) a constant air flowrate set at three different initial fixed airflow rates, and (b) an oxygen uptake rate (OUR)-controlled airflow rate. The four wastes displayed the same behaviour namely a limited biological activity at low aeration, while, beyond a threshold value, the increase of the airflow did not significantly increase the dynamic respiration indices (DRI 1 max , DRI 24 max and AT 4 ). The threshold airflow rate varied among wastes and ranged from 42NL air kg -1 DMh -1 for CM and from 67 to 77NL air kg -1 DMh -1 for FSS, ADSS and PS. Comparing the two aeration modes tested (constant air flow, OUR controlled air flow), no statistically significant differences were calculated between the respiration activity indices obtained at those two aeration modes. The results can be considered representative for urban and non-urban organic wastes and establish a general procedure to measure the respiration activity without limitations by airflow. This will permit other researchers to provide consistent results during the measurement of the respiration activity. Results indicate that high airflows are not required to establish the maximum respiration activity. This can result in energy savings and the prevention of off-gas treatment problems due to the excessive aeration rate in full scale composting plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Respiration rates in forest soil organic horizon materials treated with simulated acid rain

    Energy Technology Data Exchange (ETDEWEB)

    Salonius, P O

    1990-01-01

    The entire organic horizon above the mineral soil was collected under a mature black spruce (Picea mariana) stand in central New Brunswick. The organic horizon consisted of litter, fermentation, and humus layers of 1.5, 4.0, and 1.0 cm depths respectively. In concert with a series of simulated rain experiments, which dealt with the effects of acid precipitation of pH 4.6, 3.6, and 2.6 compared with controls at pH 5.6 on germination and early growth of forest tree seedlings, 30 randomly distributed, unplanted tubes in each rain chamber were exposed to treatment during each of the 5-week treatments of the various tree species. During the experiments, ca 315 mm of simulated rain was deposited on the soil surfaces in the tube containers. Marked decreases in soil microbial activity were found only with pH 2.6 rain, but responsiveness to increasing temperature was lower as rain of greater acidity was applied to the soil. Ammonium nitrogen mineralization rates were not affected by treatment of soil with acidified precipitation. 26 refs., 3 figs., 1 tab.

  2. A mechanical breathing simulator for respirator test

    International Nuclear Information System (INIS)

    Murata, Mikio; Ikezawa, Yoshio; Yoshida, Yoshikazu

    1976-01-01

    A mechanical breathing simulator has been developed to produce the human respiration for use in respirator test. The respirations were produced through the strokes of piston controlled by a rockerarm with adjustable fulcrum. The respiration rate was governed by motor-speed control, independent of the tidal volume achieved by adjustment of the piston stroke. By the breather, the simulated respirations for work rate 0, 208, 415, 622 and 830 kg-m/min could be produced through the typical dummy head. (auth.)

  3. Monitoring oral temperature, heart rate, and respiration rate of West Indian manatees (Trichechus manatus) during capture and handling in the field

    Science.gov (United States)

    Wong, Arthur W.; Bonde, Robert K.; Siegal-Willott, Jessica; Stamper, M. Andrew; Colee, James; Powell, James A.; Reid, James P.; Deutsch, Charles J.; Harr, Kendal E.

    2012-01-01

    West Indian manatees (Trichechus manatus) are captured, handled, and transported to facilitate conservation, research, and rehabilitation efforts. Monitoring manatee oral temperature (OT), heart rate (HR), and respiration rate (RR) during out-of-water handling can assist efforts to maintain animal well-being and improve medical response to evidence of declining health. To determine effects of capture on manatee vital signs, we monitored OT, HR, and RR continuously for a 50-min period in 38 healthy, awake, juvenile and adult Florida manatees (T. m. latirostris) and 48 similar Antillean manatees (T. m. manatus). We examined creatine kinase (CK), potassium (K+), serum amyloid A (SAA), and lactate values for each animal to assess possible systemic inflammation and muscular trauma. OT range was 29.5 to 36.2° C, HR range was 32 to 88 beats/min, and RR range was 0 to 17 breaths/5 min. Antillean manatees had higher initial OT, HR, and RR than Florida manatees (p capture and handling in the field or in a captive care setting.

  4. Airborne release fractions/rates and respirable fractions for nonreactor nuclear facilities. Volume 1, Analysis of experimental data

    International Nuclear Information System (INIS)

    1994-12-01

    This handbook contains (1) a systematic compilation of airborne release and respirable fraction experimental data for nonreactor nuclear facilities, (2) assessments of the data, and (3) values derived from assessing the data that may be used in safety analyses when the data are applicable. To assist in consistent and effective use of this information, the handbook provides: identification of a consequence determination methodology in which the information can be used; discussion of the applicability of the information and its general technical limits; identification of specific accident phenomena of interest for which the information is applicable; and examples of use of the consequence determination methodology and airborne release and respirable fraction information

  5. High dark inorganic carbon fixation rates by specific microbial groups in the Atlantic off the Galician coast (NW Iberian margin).

    Science.gov (United States)

    Guerrero-Feijóo, Elisa; Sintes, Eva; Herndl, Gerhard J; Varela, Marta M

    2018-02-01

    Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production throughout the water column, however, more prominently in the bathypelagic waters. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) allowed us to identify several microbial groups involved in dark DIC uptake. The contribution of SAR406 (Marinimicrobia), SAR324 (Deltaproteobacteria) and Alteromonas (Gammaproteobacteria) to the dark DIC fixation was significantly higher than that of SAR202 (Chloroflexi) and Thaumarchaeota, in agreement with their contribution to microbial abundance. Q-PCR on the gene encoding for the ammonia monooxygenase subunit A (amoA) from the putatively high versus low ammonia concentration ecotypes revealed their depth-stratified distribution pattern. Taken together, our results indicate that chemoautotrophy is widespread among microbes in the dark ocean, particularly in bathypelagic waters. This chemolithoautotrophic biomass production in the dark ocean, depleted in bio-available organic matter, might play a substantial role in sustaining the dark ocean's food web. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  6. Estimation of soil respiration rates and soil gas isotopic composition for the different land use of Ultisols from Calhoun CZO.

    Science.gov (United States)

    Cherkinsky, A.; Brecheisen, Z.; Richter, D. D., Jr.; Sheng, H.

    2017-12-01

    CO2 flux from soil is significant in most ecosystems and can account for more than 2/3 of total ecosystem respiration. In many cases CO2 fluxes from soil are estimated using eddy covariance techniques or the classical chamber method with measures of bulk concentrations and isotope composition of CO2. Whereas most of these studies estimate flux from the soil surface, we analyzed its concentration and isotope composition directly in soil profiles down to 8.5m depth. This experiment was conducted in Sumter National Forest in summer of 2016. The samples were collected from 3 different land use history sites: a) reference hardwood stands, mainly of oak and hickory that are taken to be never cultivated; b) cultivated plots, which were also used growing cotton prior to the 1950's but for the last 50 years for growing corn, wheat, legume, sorghum, and sunflowers; c) pine stands, which had been used for growing cotton from beginning of the 19th century and then was abandoned in 1920s and planted with loblolly pine. We have analyzed 3 replicates of each land use. There were measured in the field CO2 and O2 concentration and collected gas samples were analyzed for Δ14C, δ13C and δ18O. CO2 concentration in all types of land use has a maximum about 3m depth, approximately the same depth as the minimum of O2 concentration. Isotope analyses revealed that carbon isotopic composition tend to become lighter with the depth for all three types of land use: in cultivated site it changes from -18%o at 0.5m to -21%o at 5m; in pine site from -22%o to -25%o and in hardwood from-21.5 -24.5%o correspondently, the O2 isotopic composition does not change significantly. Based on analysis of Δ14C the turnover rate of CO2 is getting slower as depth increases. At the first 50 cm the exchange rate is the fastest on cultivated site, likely due to annual tilling, and concentration of 14C is actually equal to atmospheric. However, the turnover rate of Δ14C in soil CO2 slows down significantly as

  7. Scaling leaf respiration with nitrogen and phosphorus in tropical forests across two continents.

    Science.gov (United States)

    Rowland, Lucy; Zaragoza-Castells, Joana; Bloomfield, Keith J; Turnbull, Matthew H; Bonal, Damien; Burban, Benoit; Salinas, Norma; Cosio, Eric; Metcalfe, Daniel J; Ford, Andrew; Phillips, Oliver L; Atkin, Owen K; Meir, Patrick

    2017-05-01

    Leaf dark respiration (R dark ) represents an important component controlling the carbon balance in tropical forests. Here, we test how nitrogen (N) and phosphorus (P) affect R dark and its relationship with photosynthesis using three widely separated tropical forests which differ in soil fertility. R dark was measured on 431 rainforest canopy trees, from 182 species, in French Guiana, Peru and Australia. The variation in R dark was examined in relation to leaf N and P content, leaf structure and maximum photosynthetic rates at ambient and saturating atmospheric CO 2 concentration. We found that the site with the lowest fertility (French Guiana) exhibited greater rates of R dark per unit leaf N, P and photosynthesis. The data from Australia, for which there were no phylogenetic overlaps with the samples from the South American sites, yielded the most distinct relationships of R dark with the measured leaf traits. Our data indicate that no single universal scaling relationship accounts for variation in R dark across this large biogeographical space. Variability between sites in the absolute rates of R dark and the R dark  : photosynthesis ratio were driven by variations in N- and P-use efficiency, which were related to both taxonomic and environmental variability. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  8. The activity of ascorbic acid and catechol oxidase, the rate of photosynthesis and respiration as related to plant organs, stage of development and copper supply

    Directory of Open Access Journals (Sweden)

    St. Łyszcz

    2015-06-01

    Full Text Available Some experiments were performed to investigate the physiological role of copper in oat and sunflower and to recognize some effects of copper deficiency. Oat and sunflower plants were grown in pots on a peat soil under copper deficiency conditions (–Cu or with the optimal copper supply (+Cu. In plants the following measurements were carried out: 1 the activity of ascorbic acid oxidase (AAO and of catechol oxidase (PPO in different plant organs and at different stages of plant development, 2 the activity and the rate of photosynthesis, 3 the activity of RuDP-carboxylase, 4 the intensity of plant respiration. The activity of AAO and of PPO, and also the rate and the activity of photosynthesis were significantly lower under conditions of copper deficiency. The activity of both discussed oxidases depended on: 1 the plant species, 2 plant organs, 3 stage of plant development. Copper deficiency caused decrease of the respiration intensity of sunflower leaves but it increased to some extent the respiration of oat tops. Obtained results are consistent with the earlier suggestion of the authors that the PPO activity in sunflower leaves could be a sensitive indicator of copper supply of the plants, farther experiments are in progress.

  9. High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms

    DEFF Research Database (Denmark)

    Dillon, Jesse G; Fishbain, Susan; Miller, Scott R

    2007-01-01

    The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community...... was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesulfovibrio-like population. Reduced activity at greater depths...... was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most likely due to both sulfate and carbon limitation....

  10. Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

    Science.gov (United States)

    García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

    2017-11-01

    Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth integrated community respiration was

  11. Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis

    NARCIS (Netherlands)

    Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A.J.

    2017-01-01

    Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and

  12. Contribution of Root Respiration to Soil Respiration in Sugarcane Plantation in Thailand

    OpenAIRE

    Wilaiwan Sornpoon; Sebastien Bonnet; Poonpipope Kasemsap; Savitri Garivait

    2013-01-01

    The understanding on the contribution of root respiration to total soil respiration is still very limited, especially for sugarcane. In this study, trenching experiments in sugarcane plantations were conducted to separate and investigate soil respiration for this crop. The measurements were performed for the whole growing period of 344 days to quantify root respiration. The obtained monitoring data showed that the respiration rate is increasing with the age of the plant, accounting for up to ...

  13. Astrophysical limitations to the identification of dark matter: Indirect neutrino signals vis-a-vis direct detection recoil rates

    International Nuclear Information System (INIS)

    Serpico, Pasquale D.; Bertone, Gianfranco

    2010-01-01

    A convincing identification of dark matter (DM) particles can probably be achieved only through a combined analysis of different detections strategies, which provides an effective way of removing degeneracies in the parameter space of DM models. In practice, however, this program is made complicated by the fact that different strategies depend on different physical quantities, or on the same quantities but in a different way, making the treatment of systematic errors rather tricky. We discuss here the uncertainties on the recoil rate in direct-detection experiments and on the muon rate induced by neutrinos from dark matter annihilations in the Sun, and we show that, contrarily to the local DM density or overall cross section scale, irreducible astrophysical uncertainties affect the two rates in a different fashion, therefore limiting our ability to reconstruct the parameters of the dark matter particles. By varying within their respective errors astrophysical parameters such as the escape velocity and the velocity dispersion of dark matter particles, we show that the uncertainty on the relative strength of the neutrino and direct-detection signal is as large as a factor of 2 for typical values of the parameters, but can be even larger in some circumstances.

  14. Cattle respiration facility

    DEFF Research Database (Denmark)

    Hellwing, Anne Louise Frydendahl; Lund, Peter; Weisbjerg, Martin Riis

    2012-01-01

    In Denmark, the emission rate of methane from dairy cows has been calculated using the IPCC standard values for dairy cows in Western countries, due to the lack of national data. Therefore, four respiration chambers for dairy cows were built with the main purpose of measuring methane, but also...

  15. Taxa de respiração de cenouras minimamente processadas e armazenadas em diferentes temperaturas Respiration rate of storage processed carrots at different temperatures

    Directory of Open Access Journals (Sweden)

    Wigberto Antonio Spagnol

    2006-09-01

    Full Text Available Entre as hortaliças minimamente processadas, a cenoura é uma das mais populares, sendo comercializada de várias maneiras: raladas, cortadas em fatias, palitos, e ainda apresentadas na forma de mini-cenoura (baby carrot. O objetivo deste estudo foi determinar as taxas respiratórias de cenouras (Daucus carota da cultivar Nantes minimamente processadas. O armazenamento foi realizado nas temperaturas de 1 °C, 5 °C e 11 °C, e 90% UR. A taxa respiratória foi determinada usando um fluxo contínuo de ar. O teor de CO2 e etileno foi medido por um cromatógrafo a gás. A taxa de respiração para as cenouras fatiadas foi mais alta do que para os produtos inteiros. Os valores da energia de ativação obtidos para as cenouras fatiadas e inteiras foi de 69,82 kJmol-1 e 54,60 kJmol-1, respectivamente. A produção de etileno foi insignificante para as cenouras durante os 14 dias de armazenamento.The carrot is one of the most popular vegetables from minimally processed vegetables. It is commercialized in many different ways: shreds, slices, sticks and baby carrots. The aim of this work is to determine the respiration rate of minimally processed carrots. They were in storage at temperatures of 1 °C, 5 °C and 11 °C, and 90% RH. The respiration rate was determined using continuous humidification airflow and measuring the CO2 concentration using a gas chromatograph connected to a microcomputer. The respiration rates of the minimally processed carrots showed a higher respiration rate than for the whole products. The activation energy values calculated for the minimally processed carrots corresponded to 69.82 kJmol-1 for the whole products. The ethylene production for the carrots remained insignificant throughout the 14 days of storage.

  16. Respiration and substrate transport rates as well as reactive oxygen species production distinguish mitochondria from brain and liver.

    Science.gov (United States)

    Gusdon, Aaron M; Fernandez-Bueno, Gabriel A; Wohlgemuth, Stephanie; Fernandez, Jenelle; Chen, Jing; Mathews, Clayton E

    2015-09-10

    Aberrant mitochondrial function, including excessive reactive oxygen species (ROS) production, has been implicated in the pathogenesis of human diseases. The use of mitochondrial inhibitors to ascertain the sites in the electron transport chain (ETC) resulting in altered ROS production can be an important tool. However, the response of mouse mitochondria to ETC inhibitors has not been thoroughly assessed. Here we set out to characterize the differences in phenotypic response to ETC inhibitors between the more energetically demanding brain mitochondria and less energetically demanding liver mitochondria in commonly utilized C57BL/6J mice. We show that in contrast to brain mitochondria, inhibiting distally within complex I or within complex III does not increase liver mitochondrial ROS production supported by complex I substrates, and liver mitochondrial ROS production supported by complex II substrates occurred primarily independent of membrane potential. Complex I, II, and III enzymatic activities and membrane potential were equivalent between liver and brain and responded to ETC. inhibitors similarly. Brain mitochondria exhibited an approximately two-fold increase in complex I and II supported respiration compared with liver mitochondria while exhibiting similar responses to inhibitors. Elevated NADH transport and heightened complex II-III coupled activity accounted for increased complex I and II supported respiration, respectively in brain mitochondria. We conclude that important mechanistic differences exist between mouse liver and brain mitochondria and that mouse mitochondria exhibit phenotypic differences compared with mitochondria from other species.

  17. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean

    DEFF Research Database (Denmark)

    Ploug, Helle; Grossart, Hans-Peter; Azam, F.

    1999-01-01

    Photosynthesis and respiration were measured in 1 to 6 mm large aggregates (marine snow) collected in the Southern Californian Eight, USA. The aggregates were freely sinking in a vertical flow system with an upward flow velocity which opposed the sinking velocity of individual aggregates during...... techniques. Both the respiration rate per aggregate volume and the bacterial densities decreased with increasing aggregate size. The respiration rates normalized to the number of bacteria in single aggregates were 7.4 to 70 fmol C cell(-1) d(-1). The aggregate community respired 433 to 984 ng C d(-1) per...... aggregate in darkness, which yielded a turnover time of 8 to 9 d for the total organic carbon in aggregates. Thus, marine snow is not only a vehicle for vertical flux of organic matter; the aggregates are also hotspots of microbial respiration which cause a fast and efficient respiratory turnover...

  18. Shifts in mass-scaling of respiration, feeding, and growth rates across life-form transitions in marine pelagic organisms

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Hirst, Andrew G.

    2014-01-01

    The metabolic rate of organisms may be viewed as a basic property from which other vital rates and many ecological patterns emerge and that follows a universal allometric mass scaling law, or it may be considered a property of the organism that emerges as a result of the adaptation to the environ...... and be the result of the optimization of trade-offs that allow sufficient feeding and growth rates to balance mortality...

  19. [Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

    Science.gov (United States)

    Lu, Xing-li; Liao, Yun-cheng

    2015-06-01

    To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

  20. Growth response of Douglas-fir seedlings to nitrogen fertilization: importance of Rubisco activation state and respiration rates.

    Science.gov (United States)

    Daniel K. Manter; Kathleen L. Kavanagh; Cathy L. Rose

    2005-01-01

    High foliar nitrogen concentration ([N]) is associated with high rates of photosynthesis and thus high tree productivity; however, at excessive [N], tree productivity is reduced. Reports of excessive [N] in the Douglas-fir forests of the Oregon Coast Range prompted this investigation of growth and needle physiological responses to increasing foliar N concentrations in...

  1. Activity of the respiratory electron transport system and respiration rates within the oxygen minimum layer of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Shailaja, M.S.

    rates. The depth profiles representing observations off Peru and Mexico are also shown. It may be noted that the measurements off Mexico were made with a method similar to that followed by us (GARFIELD et al., 1983). On the other hand, the Peruvian... judging from the nitrate deficit, nitrite and nitrous oxide distributions (NAQvI and NORONHA, 1991). OXYGEN CONSUMPTION (nl./t/h) 0 q 20 40 60 80 , n i I i I00 Off Mexico • • /~ "f~ Off Peru o o / 200 ,o ~ ~ - o o I • " e o //-o-./ - - 400 tR~•7...

  2. Effect of Anoxia on Respiration Rate (Fermentative Index and Ethanol Production of Onion Bulbs (Allium cepa L.

    Directory of Open Access Journals (Sweden)

    N. Benkeblia

    2003-01-01

    Full Text Available The physiological behavior, including carbon dioxide production, fermentative index (FI and ethanolic production of onion bulbs kept under total anoxia (l00% N2 was investigated. During the first 24 hours, carbon dioxide production increased from 0.01 to 1.56 kPa Co2, and the average rate of the increase in CO2; production between 0 and 24 hours was 0.09 kPa/h. The Q10, of the fermentative index was l.9. Ethanol produced by onion bulbs kept under anoxia during 6 hours was temperature dependent, and was 0.563 and 0.760 pmol kg-1h-1 at 10 and 20°C respectively, while at 4°C the quantity produced was not detected. It is concluded that onion seems to be less tolerant to anoxia than other vegetables such as artichoke, cauliflower, tomato, potato and asparagus.

  3. Gaseous elemental mercury emissions and CO{sub 2} respiration rates in terrestrial soils under controlled aerobic and anaerobic laboratory conditions

    Energy Technology Data Exchange (ETDEWEB)

    Obrist, Daniel, E-mail: daniel.obrist@dri.edu [Desert Research Institute, Division of Atmospheric Sciences, 2215 Raggio Parkway, Reno, Nevada, 89512 (United States); Fain, Xavier; Berger, Carsen [Desert Research Institute, Division of Atmospheric Sciences, 2215 Raggio Parkway, Reno, Nevada, 89512 (United States)

    2010-03-01

    Mercury (Hg) levels in terrestrial soils are linked to the presence of organic carbon (C). Carbon pools are highly dynamic and subject to mineralization processes, but little is known about the fate of Hg during decomposition. This study evaluated relationships between gaseous Hg emissions from soils and carbon dioxide (CO{sub 2}) respiration under controlled laboratory conditions to assess potential losses of Hg to the atmosphere during C mineralization. Results showed a linear correlation (r{sup 2} = 0.49) between Hg and CO{sub 2} emissions in 41 soil samples, an effect unlikely to be caused by temperature, radiation, different Hg contents, or soil moisture. Stoichiometric comparisons of Hg/C ratios of emissions and underlying soil substrates suggest that 3% of soil Hg was subject to evasion. Even minute emissions of Hg upon mineralization, however, may be important on a global scale given the large Hg pools sequestered in terrestrial soils and C stocks. We induced changes in CO{sub 2} respiration rates and observed Hg flux responses, including inducement of anaerobic conditions by changing chamber air supply from N{sub 2}/O{sub 2} (80% and 20%, respectively) to pure N{sub 2}. Unexpectedly, Hg emissions almost quadrupled after O{sub 2} deprivation while oxidative mineralization (i.e., CO{sub 2} emissions) was greatly reduced. This Hg flux response to anaerobic conditions was lacking when repeated with sterilized soils, possibly due to involvement of microbial reduction of Hg{sup 2+} by anaerobes or indirect abiotic effects such as alterations in soil redox conditions. This study provides experimental evidence that Hg volatilization, and possibly Hg{sup 2+} reduction, is related to O{sub 2} availability in soils from two Sierra Nevada forests. If this result is confirmed in soils from other areas, the implication is that Hg volatilization from terrestrial soils is partially controlled by soil aeration and that low soil O{sub 2} levels and possibly low soil redox

  4. Secretly asymmetric dark matter

    Science.gov (United States)

    Agrawal, Prateek; Kilic, Can; Swaminathan, Sivaramakrishnan; Trendafilova, Cynthia

    2017-01-01

    We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early Universe, even though the total dark matter number remains zero throughout the history of the Universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal weakly interacting massive particles. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.

  5. Management effects on European cropland respiration

    DEFF Research Database (Denmark)

    Eugster, Werner; Moffat, Antje M.; Ceschia, Eric

    2010-01-01

    Increases in respiration rates following management activities in croplands are considered a relevant anthropogenic source of CO2. In this paper, we quantify the impact of management events on cropland respiration fluxes of CO2 as they occur under current climate and management conditions. Our....... This allowed us to address the question of how management activities influence ecosystem respiration. This was done by comparing respiration fluxes during 7, 14, and 28 days after the management with those observed during the matching time period before management. Median increases in respiration ranged from...... than management alone are also important at a given site. Temperature is the climatic factor that showed best correlation with site-specific respiration fluxes. Therefore, the effect of temperature changes between the time periods before and after management were taken into account for a subset of 13...

  6. Cardiac, Skeletal, and smooth muscle mitochondrial respiration

    DEFF Research Database (Denmark)

    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I

    2014-01-01

    , skeletal, and smooth muscle was harvested from a total of 22 subjects (53±6 yrs) and mitochondrial respiration assessed in permeabilized fibers. Complex I+II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac, skeletal, to smooth muscle (54±1; 39±4; 15......±1 pmol•s(-1)•mg (-1), prespiration rates were normalized by CS (respiration...... per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, Complex I state 2 normalized for CS activity, an index of non-phosphorylating respiration per mitochondrial content, increased progressively from cardiac, skeletal...

  7. DIGITAL FLOOD INSURANCE RATE MAP DATABASE, DARKE COUNTY, OHIO (AND INCORPORATED AREAS)

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk...

  8. Dark Dark Wood

    DEFF Research Database (Denmark)

    2017-01-01

    2017 student Bachelor film. Synopsis: Young princess Maria has had about enough of her royal life – it’s all lesson, responsibilities and duties on top of each other, every hour of every day. Overwhelmed Maria is swept away on an adventure into the monster-filled dark, dark woods. During 2017...

  9. Respirator field performance factors

    International Nuclear Information System (INIS)

    Skaggs, B.J.; DeField, J.D.; Strandberg, S.W.; Sutcliffe, C.R.

    1985-01-01

    The Industrial Hygiene Group assisted OSHA and the NRC in measurements of respirator performance under field conditions. They reviewed problems associated with sampling aerosols within the respirator in order to determine fit factors (FFs) or field performance factor (FPF). In addition, they designed an environmental chamber study to determine the effects of temperature and humidity on a respirator wearer

  10. Response of Respiration of Soybean Leaves Grown at Ambient and Elevated Carbon Dioxide Concentrations to Day-to-day Variation in Light and Temperature under Field Conditions

    Science.gov (United States)

    BUNCE, JAMES A.

    2005-01-01

    • Background and Aims Respiration is an important component of plant carbon balance, but it remains uncertain how respiration will respond to increases in atmospheric carbon dioxide concentration, and there are few measurements of respiration for crop plants grown at elevated [CO2] under field conditions. The hypothesis that respiration of leaves of soybeans grown at elevated [CO2] is increased is tested; and the effects of photosynthesis and acclimation to temperature examined. • Methods Net rates of carbon dioxide exchange were recorded every 10 min, 24 h per day for mature upper canopy leaves of soybeans grown in field plots at the current ambient [CO2] and at ambient plus 350 µmol mol−1 [CO2] in open top chambers. Measurements were made on pairs of leaves from both [CO2] treatments on a total of 16 d during the middle of the growing seasons of two years. • Key Results Elevated [CO2] increased daytime net carbon dioxide fixation rates per unit of leaf area by an average of 48 %, but had no effect on night-time respiration expressed per unit of area, which averaged 53 mmol m−2 d−1 (1·4 µmol m−2 s−1) for both the ambient and elevated [CO2] treatments. Leaf dry mass per unit of area was increased on average by 23 % by elevated [CO2], and respiration per unit of mass was significantly lower at elevated [CO2]. Respiration increased by a factor of 2·5 between 18 and 26 °C average night temperature, for both [CO2] treatments. • Conclusions These results do not support predictions that elevated [CO2] would increase respiration per unit of area by increasing photosynthesis or by increasing leaf mass per unit of area, nor the idea that acclimation of respiration to temperature would be rapid enough to make dark respiration insensitive to variation in temperature between nights. PMID:15781437

  11. Respiration rates in subsurface waters of the northern Indian Ocean: Evidence for low decomposition rates of organic matter within the water column in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Shailaja, M.S.; DileepKumar, M.; Sengupta, R.

    measured in the Arabian Sea. Lower respiratin rates in the Bay of Bengal are corroborated by the much weaker north-south gradients in oxygen and total carbon dioxide. These are, however, in conflict with the higher sinking fluxes of organic carbon measured...

  12. The 'dark side' of social capital: trust and self-rated health in European countries.

    Science.gov (United States)

    Campos-Matos, Inês; Subramanian, S V; Kawachi, Ichiro

    2016-02-01

    Generalized interpersonal trust (as an indicator of social capital) has been linked to health status at both the individual and ecological level. We sought to examine how changes in contextual and individual trust are associated with changes in self-rated health in the European Social Surveys 2002-12. A multilevel analysis using a variance components model was performed on 203 452 individuals nested within 145 country cohorts covering 35 countries. Conditional on sociodemographic covariates, we sought to examine the association between self-rated health and individual trust, country average trust and a cross-level interaction between the two. Although individual trust perceptions were significantly correlated with self-rated health [OR = 0.95, 95% confidence interval (0.94-0.96)], country-level trust was not associated [OR = 1.12, 95% confidence interval (0.95-1.32)]. There was, however, a strong crosslevel interaction between contextual and individual trust (P < 0.001), such that individuals with high interpersonal trust reported better health in contexts in which other individuals expressed high average interpersonal trust. Conversely, low trust individuals reported worse health in high trust contexts. Our findings suggest that contexts with increasing average trust can be harmful for low trust individuals, which might reflect the negative impact that social capital can have in certain groups. These findings suggest that contextual trust has a complex role in explaining health inequalities and individual self-rated health. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

  13. 2D dark-count-rate modeling of PureB single-photon avalanche diodes in a TCAD environment

    Science.gov (United States)

    Knežević, Tihomir; Nanver, Lis K.; Suligoj, Tomislav

    2018-02-01

    PureB silicon photodiodes have nm-shallow p+n junctions with which photons/electrons with penetration-depths of a few nanometer can be detected. PureB Single-Photon Avalanche Diodes (SPADs) were fabricated and analysed by 2D numerical modeling as an extension to TCAD software. The very shallow p+ -anode has high perimeter curvature that enhances the electric field. In SPADs, noise is quantified by the dark count rate (DCR) that is a measure for the number of false counts triggered by unwanted processes in the non-illuminated device. Just like for desired events, the probability a dark count increases with increasing electric field and the perimeter conditions are critical. In this work, the DCR was studied by two 2D methods of analysis: the "quasi-2D" (Q-2D) method where vertical 1D cross-sections were assumed for calculating the electron/hole avalanche-probabilities, and the "ionization-integral 2D" (II-2D) method where crosssections were placed where the maximum ionization-integrals were calculated. The Q-2D method gave satisfactory results in structures where the peripheral regions had a small contribution to the DCR, such as in devices with conventional deepjunction guard rings (GRs). Otherwise, the II-2D method proved to be much more precise. The results show that the DCR simulation methods are useful for optimizing the compromise between fill-factor and p-/n-doping profile design in SPAD devices. For the experimentally investigated PureB SPADs, excellent agreement of the measured and simulated DCR was achieved. This shows that although an implicit GR is attractively compact, the very shallow pn-junction gives a risk of having such a low breakdown voltage at the perimeter that the DCR of the device may be negatively impacted.

  14. Codecaying Dark Matter.

    Science.gov (United States)

    Dror, Jeff Asaf; Kuflik, Eric; Ng, Wee Hao

    2016-11-18

    We propose a new mechanism for thermal dark matter freeze-out, called codecaying dark matter. Multicomponent dark sectors with degenerate particles and out-of-equilibrium decays can codecay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes codecaying dark matter.

  15. Temperature response of respiration across heterogeneous microtopography in the Arctic tundra, Utqiaġvik, Alaska

    Science.gov (United States)

    Wilkman, E.; Zona, D.; Tang, Y.; Gioli, B.; Lipson, D.; Oechel, W. C.

    2017-12-01

    The response of ecosystem respiration to warming in the Arctic is not well constrained, partly due to the presence of ice-wedge polygons in continuous permafrost areas. These formations lead to substantial variation in vegetation, soil moisture, water table, and active layer depth over the meter scale that can drive respiratory carbon loss. Accurate calculations of in-situ temperature sensitivities (Q10) are vital for the prediction of future Arctic emissions, and while the eddy covariance technique has commonly been used to determine the diurnal and season patterns of net ecosystem exchange (NEE) of CO2, the lack of suitable dark periods in the Arctic summer has limited our ability to estimate and interpret ecosystem respiration. To therefore improve our understanding of and define controls on ecosystem respiration, we directly compared CO2 fluxes measured from automated chambers across the main local polygonised landscape forms (high and low centers, polygon rims, and polygon troughs) to estimates from an adjacent eddy covariance tower. Low-centered polygons and polygon troughs had the greatest cumulative respiration rates, and ecosystem type appeared to be the most important explanatory variable for these rates. Despite the difference in absolute respiration rates, Q10 was surprisingly similar across all microtopographic features, despite contrasting water levels and vegetation types. Conversely, Q10 varied temporally, with higher values during the early and late summer and lower values during the peak growing season. Finally, good agreement was found between chamber and tower based Q10 estimates during the peak growing season. Overall, this study suggests that it is possible to simplify estimates of the temperature sensitivity of respiration across heterogeneous landscapes, but that seasonal changes in Q10 should be incorporated into current and future model simulations.

  16. Complexity in pH-Dependent Ribozyme Kinetics: Dark pKa Shifts and Wavy Rate-pH Profiles.

    Science.gov (United States)

    Frankel, Erica A; Bevilacqua, Philip C

    2018-02-06

    Charged bases occur in RNA enzymes, or ribozymes, where they play key roles in catalysis. Cationic bases donate protons and perform electrostatic catalysis, while anionic bases accept protons. We previously published simulations of rate-pH profiles for ribozymes in terms of species plots for the general acid and general base that have been useful for understanding how ribozymes respond to pH. In that study, we did not consider interaction between the general acid and general base or interaction with other species on the RNA. Since that report, diverse small ribozyme classes have been discovered, many of which have charged nucleobases or metal ions in the active site that can either directly interact and participate in catalysis or indirectly interact as "influencers". Herein, we simulate experimental rate-pH profiles in terms of species plots in which reverse protonated charged nucleobases interact. These analyses uncover two surprising features of pH-dependent enzyme kinetics. (1) Cooperativity between the general acid and general base enhances population of the functional forms of a ribozyme and manifests itself as hidden or "dark" pK a shifts, real pK a shifts that accelerate the reaction but are not readily observed by standard experimental approaches, and (2) influencers favorably shift the pK a s of proton-transferring nucleobases and manifest themselves as "wavy" rate-pH profiles. We identify parallels with the protein enzyme literature, including reverse protonation and wavelike behavior, while pointing out that RNA is more prone to reverse protonation. The complexities uncovered, which arise from simple pairwise interactions, should aid deconvolution of complex rate-pH profiles for RNA and protein enzymes and suggest veiled catalytic devices for promoting catalysis that can be tested by experiment and calculation.

  17. Nutrients and temperature additively increase stream microbial respiration

    Science.gov (United States)

    David W. P. Manning; Amy D. Rosemond; Vladislav Gulis; Jonathan P. Benstead; John S. Kominoski

    2017-01-01

    Rising temperatures and nutrient enrichment are co‐occurring global‐change drivers that stimulate microbial respiration of detrital carbon, but nutrient effects on the temperature dependence of respiration in aquatic ecosystems remain uncertain. We measured respiration rates associated with leaf litter, wood, and fine benthic organic matter (FBOM) across...

  18. Quantifying soil respiration at landscape scales. Chapter 11

    Science.gov (United States)

    John B. Bradford; Michael G. Ryan

    2008-01-01

    Soil CO2, efflux, or soil respiration, represents a substantial component of carbon cycling in terrestrial ecosystems. Consequently, quantifying soil respiration over large areas and long time periods is an increasingly important goal. However, soil respiration rates vary dramatically in space and time in response to both environmental conditions...

  19. Tropical rainforest carbon sink declines during El Niño as a result of reduced photosynthesis and increased respiration rates.

    Science.gov (United States)

    Cavaleri, Molly A; Coble, Adam P; Ryan, Michael G; Bauerle, William L; Loescher, Henry W; Oberbauer, Steven F

    2017-10-01

    Changes in tropical forest carbon sink strength during El Niño Southern Oscillation (ENSO) events can indicate future behavior under climate change. Previous studies revealed ˜6 Mg C ha -1  yr -1 lower net ecosystem production (NEP) during ENSO year 1998 compared with non-ENSO year 2000 in a Costa Rican tropical rainforest. We explored environmental drivers of this change and examined the contributions of ecosystem respiration (RE) and gross primary production (GPP) to this weakened carbon sink. For 1998-2000, we estimated RE using chamber-based respiration measurements, and we estimated GPP in two ways: using (1) the canopy process model MAESTRA, and (2) combined eddy covariance and chamber respiration data. MAESTRA-estimated GPP did not statistically differ from GPP estimated using approach 2, but was ˜ 28% greater than published GPP estimates for the same site and years using eddy covariance data only. A 7% increase in RE (primarily increased soil respiration) and a 10% reduction in GPP contributed equally to the difference in NEP between ENSO year 1998 and non-ENSO year 2000. A warming and drying climate for tropical forests may yield a weakened carbon sink from both decreased GPP and increased RE. Understanding physiological acclimation will be critical for the large carbon stores in these ecosystems. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  20. Dark group: dark energy and dark matter

    International Nuclear Information System (INIS)

    Macorra, A. de la

    2004-01-01

    We study the possibility that a dark group, a gauge group with particles interacting with the standard model particles only via gravity, is responsible for containing the dark energy and dark matter required by present day observations. We show that it is indeed possible and we determine the constrains for the dark group. The non-perturbative effects generated by a strong gauge coupling constant can de determined and a inverse power law scalar potential IPL for the dark meson fields is generated parameterizing the dark energy. On the other hand it is the massive particles, e.g., dark baryons, of the dark gauge group that give the corresponding dark matter. The mass of the dark particles is of the order of the condensation scale Λ c and the temperature is smaller then the photon's temperature. The dark matter is of the warm matter type. The only parameters of the model are the number of particles of the dark group. The allowed values of the different parameters are severely restricted. The dark group energy density at Λ c must be Ω DGc ≤0.17 and the evolution and acceptable values of dark matter and dark energy leads to a constrain of Λ c and the IPL parameter n giving Λ c =O(1-10 3 ) eV and 0.28≤n≤1.04

  1. Respiration in spiders (Araneae).

    Science.gov (United States)

    Schmitz, Anke

    2016-05-01

    Spiders (Araneae) are unique regarding their respiratory system: they are the only animal group that breathe simultaneously with lungs and tracheae. Looking at the physiology of respiration the existence of tracheae plays an important role in spiders with a well-developed tracheal system. Other factors as sex, life time, type of prey capture and the high ability to gain energy anaerobically influence the resting and the active metabolic rate intensely. Most spiders have metabolic rates that are much lower than expected from body mass; but especially those with two pairs of lungs. Males normally have higher resting rates than females; spiders that are less evolved and possess a cribellum have lower metabolic rates than higher evolved species. Freely hunting spiders show a higher energy turnover than spiders hunting with a web. Spiders that live longer than 1 year will have lower metabolic rates than those species that die after 1 year in which development and reproduction must be completed. Lower temperatures and starvation, which most spiders can cope with, will decrease the metabolic rate as well.

  2. The Path of Carbon in Photosynthesis VII. Respiration and Photosynthesis

    Science.gov (United States)

    Benson, A. A.; Calvin, M.

    1949-07-21

    The relationship of respiration to photosynthesis in barley seedling leaves and the algae, Chlorella and Scenedesmus, has been investigated using radioactive carbon dioxide and the techniques of paper chromatography and radioautography. The plants are allowed to photosynthesize normally for thirty seconds in c{sup 14}O{sub 2} after which they are allowed to respire in air or helium in the light or dark. Respiration of photosynthetic intermediates as evidenced by the appearance of labeled glutomic, isocitric, fumaric and succinic acids is slower in the light than in the dark. Labeled glycolic acid is observed in barley and algae. It disappears rapidly in the dark and is maintained and increased in quantity in the light in C0{sub 2}-free air.

  3. Organic fuels for respiration in tropical river systems

    Science.gov (United States)

    Ward, N.; Keil, R. G.; Richey, J. E.; Krusche, A. V.; Medeiros, P. M.

    2011-12-01

    Watershed-derived organic matter is thought to provide anywhere from 30-90% of the organic matter in rivers (e.g. Hernes et al 2008; Spencer et al 2010). The most abundant biochemicals on land are cellulose, hemicelluloses, and lignin. Combined, they represent as much as 80% of the biomass in a typical forest and as much as 60% of the biomass in a typical field (natural or crop)(Bose et al 2009; Bridgeman et al., 2007; Hu and Zu 2006; Martens et al 2004). They are often assumed to be refractory and hard to degrade, but this assumption is at odds with virtually all observations: soils and marine sediments are not accumulating vast amounts of these compounds (Hedges and Oades, 1997), and degradation experiments suggest that cellulose, hemicelluloses and lignin are reactive and likely to be important fuels for respiration (Benner, 1991; Haddad et al, 1992; Dittmar et al, 2001; Otto and Simpson, 2006). During several trips to the lower Amazon River, incubation experiments were performed in which the biological degradation of lignin phenols was observed in order to assess the contribution of microbial respiration of terrestrially-derived macromolecules to gross respiration and CO2 gas evasion rates. Both particulate and dissolved lignin concentrations decreased by ~40% after being incubated in the dark for 5-7 days, indicating a turnover time of the entire lignin pool of 12-18 days. These results shift the paradigm that lignocellulose derived OM is highly recalcitrant, and indicate that microbial respiration of lignocellulose may play a larger role in total respiration rates/CO2 outgassing than previously thought. A simple mass balance calculation was done to test whether microbial degradation alone could explain the lignin data observed in the field. First, a theoretical particulate lignin concentration for Macapa was calculated based on the observed data at Obidos. The measured rate of particulate lignin degradation was multiplied by the transit time of water from

  4. Oocytes with a dark zona pellucida demonstrate lower fertilization, implantation and clinical pregnancy rates in IVF/ICSI cycles.

    Directory of Open Access Journals (Sweden)

    Wei Shi

    Full Text Available The morphological assessment of oocytes is important for embryologists to identify and select MII oocytes in IVF/ICSI cycles. Dysmorphism of oocytes decreases viability and the developmental potential of oocytes as well as the clinical pregnancy rate. Several reports have suggested that oocytes with a dark zona pellucida (DZP correlate with the outcome of IVF treatment. However, the effect of DZP on oocyte quality, fertilization, implantation, and pregnancy outcome were not investigated in detail. In this study, a retrospective analysis was performed in 268 infertile patients with fallopian tube obstruction and/or male factor infertility. In 204 of these patients, all oocytes were surrounded by a normal zona pellucida (NZP, control group, whereas 46 patients were found to have part of their retrieved oocytes enclosed by NZP and the other by DZP (Group A. In addition, all oocytes enclosed by DZP were retrieved from 18 patients (Group B. No differences were detected between the control and group A. Compared to the control group, the rates of fertilization, good quality embryos, implantation and clinical pregnancy were significantly decreased in group B. Furthermore, mitochondria in oocytes with a DZP in both of the two study groups (A and B were severely damaged with several ultrastructural alterations, which were associated with an increased density of the zona pellucida and vacuolization. Briefly, oocytes with a DZP affected the clinical outcome in IVF/ICSI cycles and appeared to contain more ultrastructural alterations. Thus, DZP could be used as a potential selective marker for embryologists during daily laboratory work.

  5. Improving respiration measurements with gas exchange analyzers.

    Science.gov (United States)

    Montero, R; Ribas-Carbó, M; Del Saz, N F; El Aou-Ouad, H; Berry, J A; Flexas, J; Bota, J

    2016-12-01

    Dark respiration measurements with open-flow gas exchange analyzers are often questioned for their low accuracy as their low values often reach the precision limit of the instrument. Respiration was measured in five species, two hypostomatous (Vitis Vinifera L. and Acanthus mollis) and three amphistomatous, one with similar amount of stomata in both sides (Eucalyptus citriodora) and two with different stomata density (Brassica oleracea and Vicia faba). CO 2 differential (ΔCO 2 ) increased two-fold with no change in apparent R d , when the two leaves with higher stomatal density faced outside. These results showed a clear effect of the position of stomata on ΔCO 2 . Therefore, it can be concluded that leaf position is important to guarantee the improvement of respiration measurements increasing ΔCO 2 without affecting the respiration results by leaf or mass units. This method will help to increase the accuracy of leaf respiration measurements using gas exchange analyzers. Copyright © 2016 Elsevier GmbH. All rights reserved.

  6. Plant Respiration and Climate Change Effects

    International Nuclear Information System (INIS)

    Bruhn, D.

    2002-04-01

    Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Short- and long-term effects of temperature and CO 2 on plant respiration were investigated in a number of plant species. The experiments tested effects of either temperature and/or CO 2 from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue, and up to the whole canopy level. The short-term effects of elevated atmospheric CO 2 on plant respiration appeared to be less than suggested so far in the literature. This was true both at the tissue level and for intact mitochondria. Respiratory enzymes can, however, be affected already at low CO 2 . These effects did not manifest itself at the tissue level, though, due to low degrees of control on the whole respiratory process exerted by the particular enzymes. Plant respiration on the other hand was affected by long-term growth at elevated atmospheric CO 2 . The findings of the reduced plant respiration at the leaf level were consistent with the literature and potential causes are discussed. Short-term effects of temperature on plant respiration were demonstrated to be dependent on the actual measurement temperature. Further, it is shown that mitochondrial leaf respiration in darkness and light differ substantially in the temperature sensitivity with the former being the far most sensitive. This has implications for modelling CO 2 exchange between vegetation and atmosphere as demonstrated here, since this has so far been neglected. Long-term effects of temperature resulted in respiratory acclimation in a number of species. Respiratory acclimation appeared not to occur to any one single type of growth temperature. The implications of this finding in combination with the timing of acclimation are discussed for modelling respiratory CO 2 release. (au)

  7. Plant Respiration and Climate Change Effects

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, D

    2002-04-01

    Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Short- and long-term effects of temperature and CO{sub 2} on plant respiration were investigated in a number of plant species. The experiments tested effects of either temperature and/or CO{sub 2} from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue, and up to the whole canopy level. The short-term effects of elevated atmospheric CO{sub 2} on plant respiration appeared to be less than suggested so far in the literature. This was true both at the tissue level and for intact mitochondria. Respiratory enzymes can, however, be affected already at low CO{sub 2}. These effects did not manifest itself at the tissue level, though, due to low degrees of control on the whole respiratory process exerted by the particular enzymes. Plant respiration on the other hand was affected by long-term growth at elevated atmospheric CO{sub 2}. The findings of the reduced plant respiration at the leaf level were consistent with the literature and potential causes are discussed. Short-term effects of temperature on plant respiration were demonstrated to be dependent on the actual measurement temperature. Further, it is shown that mitochondrial leaf respiration in darkness and light differ substantially in the temperature sensitivity with the former being the far most sensitive. This has implications for modelling CO{sub 2} exchange between vegetation and atmosphere as demonstrated here, since this has so far been neglected. Long-term effects of temperature resulted in respiratory acclimation in a number of species. Respiratory acclimation appeared not to occur to any one single type of growth temperature. The implications of this finding in combination with the timing of acclimation are discussed for modelling respiratory CO{sub 2} release. (au)

  8. Linking the distribution of carbon isotope ratios in soil carbonates and speleothems to climate conditions in the past: A model for the dependence of respiration rate on soil moisture

    Science.gov (United States)

    Liu, Y.; Ibarra, D. E.; Winnick, M.; Caves Rugenstein, J. K.; Oster, J. L.; Druhan, J. L.

    2017-12-01

    The carbon isotope compositions (δ13C) of atmospheric CO2, C3-origin organic carbon, and limestone epikarst differ substantially, resulting in variable δ13C signatures recorded in secondary soil carbonates and speleothems which represent a mixture of these sources. Even though this signal has been widely used in paleoclimate studies, the extent to which carbonate δ13C is influenced by the dynamic response of organic carbon respiration rates to soil moisture variations has yet to be fully evaluated [1]. Soils that are rewetted after a prolonged drought commonly display a peak in respiration rate followed by relaxation to a lower steady state in both lab incubation experiments and field observations. This transient behavior, known as the Birch effect, has been extensively observed across a broad range of locations and soil types, and may generate more than 50% of the total respired CO2 in some ecosystems [2]. Here, we seek to identify the influence of the Birch effect on carbonate δ13C records based on a moisture-dependent modeling approach. We report compiled respiration rates of soils from the literature and fit these data as a function of soil moisture, before imposing exponential dampening with depth and applying the resulting function in a production-diffusion equation [3]. We then implement a mass balance calculation for the δ13C value of carbonate precipitated from a mixture of atmospheric and respired CO2, including mass-dependent fractionation associated with diffusive transport. Our results offer a novel prediction for depth-resolved carbonate δ13C as a function of soil moisture, and suggest that Birch effect signals may be recorded in soil carbonates and influence the magnitude of carbonate δ13C variations in speleothems. Thus, we illustrate a prediction for the range of carbonate δ13C recorded in terrestrial carbonates and suggest that differences in the range of carbonate δ13C may indicate changes in soil moisture variability, providing a new

  9. The WiggleZ Dark Energy Survey: constraining the evolution of Newton's constant using the growth rate of structure

    International Nuclear Information System (INIS)

    Nesseris, Savvas; Blake, Chris; Davis, Tamara; Parkinson, David

    2011-01-01

    We constrain the evolution of Newton's constant using the growth rate of large-scale structure measured by the WiggleZ Dark Energy Survey in the redshift range 0.1 m (assuming General Relativity), and use this to construct a diagnostic to detect the presence of an evolving Newton's constant. Secondly we directly measure the evolution of Newton's constant, G eff , that appears in Modified Gravity theories, without assuming General Relativity to be true. The novelty of these approaches are that, contrary to other methods, they do not require knowledge of the expansion history of the Universe, H(z), making them model independent tests. Our constraints for the second derivative of Newton's constant at the present day, assuming it is slowly evolving as suggested by Big Bang Nucleosynthesis constraints, using the WiggleZ data is G double-dot eff (t 0 ) = −1.19 ± 0.95·10 −20 h 2 yr −2 , where h is defined via H 0 = 100 h km s −1 Mpc −1 , while using both the WiggleZ and the Sloan Digital Sky Survey Luminous Red Galaxy (SDSS LRG) data is G double-dot eff (t 0 ) = −3.6 ± 6.8·10 −21 h 2 yr −2 , both being consistent with General Relativity. Finally, our constraint for the rms mass fluctuation σ 8 using the WiggleZ data is σ 8 = 0.75 ± 0.08, while using both the WiggleZ and the SDSS LRG data σ 8 = 0.77 ± 0.07, both in good agreement with the latest measurements from the Cosmic Microwave Background radiation

  10. Determination of respirable-sized crystalline silica in different ambient environments in the United Kingdom with a mobile high flow rate sampler utilising porous foams to achieve the required particle size selection

    Science.gov (United States)

    Stacey, Peter; Thorpe, Andrew; Roberts, Paul; Butler, Owen

    2018-06-01

    Inhalation of respirable crystalline silica (RCS) can cause diseases including silicosis and cancer. Levels of RCS close to an emission source are measured but little is known about the wider ambient exposure from industry emissions or natural sources. The aim of this work is to report the RCS concentrations obtained from a variety of ambient environments using a new mobile respirable (PM4) sampler. A mobile battery powered high flow rate (52 L min-1) sampler was developed and evaluated for particulate aerosol sampling employing foams to select the respirable particle size fraction. Sampling was conducted in the United Kingdom at site boundaries surrounding seven urban construction and demolition and five sand quarry sites. These are compared with data from twelve urban aerosol samples and from repeat measurements from a base line study at a single rural site. The 50% particle size penetration (d50) through the foam was 4.3 μm. Over 85% of predict bias values were with ±10% of the respirable convention, which is based on a log normal curve. Results for RCS from all construction and quarry activities are generally low with a 95 th percentile of 11 μg m-3. Eighty percent of results were less than the health benchmark value of 3 μg m-3 used in some states in America for ambient concentrations. The power cutting of brick and the largest demolition activities gave the highest construction levels. Measured urban background RCS levels were typically below 0.3 μg m-3 and the median RCS level, at a rural background location, was 0.02 μg m-3. These reported ambient RCS concentrations may provide useful baseline values to assess the wider impact of fugitive, RCS containing, dust emissions into the wider environment.

  11. Choosing the right respirator

    International Nuclear Information System (INIS)

    Bidwell, J.

    1997-01-01

    Selecting respirators to help protect workers from airborne contaminants can be a confusing process. The consequences of selecting the incorrect respirator can be intimidating, and worker safety and health may be dramatically and irreparably affected if an inappropriate respirator is chosen. When used in the workplace, a formal respiratory protection program must be established covering the basic requirements outlined in the OSHA Respiratory Protection Standard (29 CFR 1910.134). Education and training must be properly emphasized and conducted periodically. Maintenance, cleaning, and storage programs must be established and routinely followed for reusable respirators. The process of establishing a respiratory protection program can be broken down into four basic steps: Identify respiratory hazards and concentrations; understand the contaminants effects on workers' health; select appropriate respiratory protection; and train in proper respirator use and maintenance. These four steps are the foundation for establishing a basic respirator protection program. Be sure to consult state and federal OSHA requirements to ensure that the program complies. Leading industrial respirator manufacturers should be able to assist with on-site training and education in this four-step process, in addition to helping employers train their workers and conduct respirator fit testing

  12. Regulation of respiration and the oxygen diffusion barrier in soybean protect symbiotic nitrogen fixation from chilling-induced inhibition and shoots from premature senescence.

    Science.gov (United States)

    van Heerden, Philippus D R; Kiddle, Guy; Pellny, Till K; Mokwala, Phatlane W; Jordaan, Anine; Strauss, Abram J; de Beer, Misha; Schlüter, Urte; Kunert, Karl J; Foyer, Christine H

    2008-09-01

    Symbiotic nitrogen fixation is sensitive to dark chilling (7 degrees C-15 degrees C)-induced inhibition in soybean (Glycine max). To characterize the mechanisms that cause the stress-induced loss of nodule function, we examined nodule structure, carbon-nitrogen interactions, and respiration in two soybean genotypes that differ in chilling sensitivity: PAN809 (PAN), which is chilling sensitive, and Highveld Top (HT), which is more chilling resistant. Nodule numbers were unaffected by dark chilling, as was the abundance of the nitrogenase and leghemoglobin proteins. However, dark chilling decreased nodule respiration rates, nitrogenase activities, and NifH and NifK mRNAs and increased nodule starch, sucrose, and glucose in both genotypes. Ureide and fructose contents decreased only in PAN nodules. While the chilling-induced decreases in nodule respiration persisted in PAN even after return to optimal temperatures, respiration started to recover in HT by the end of the chilling period. The area of the intercellular spaces in the nodule cortex and infected zone was greatly decreased in HT after three nights of chilling, an acclimatory response that was absent from PAN. These data show that HT nodules are able to regulate both respiration and the area of the intercellular spaces during chilling and in this way control the oxygen diffusion barrier, which is a key component of the nodule stress response. We conclude that chilling-induced loss of symbiotic nitrogen fixation in PAN is caused by the inhibition of respiration coupled to the failure to regulate the oxygen diffusion barrier effectively. The resultant limitations on nitrogen availability contribute to the greater chilling-induced inhibition of photosynthesis in PAN than in HT.

  13. BOREAS TE-5 Soil Respiration Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. Soil respiration data were collected from 26-May-94 to 07-Sep-94 in the BOREAS NSA and SSA to compare the soil respiration rates in different forest sites using a LI-COR 6200 soil respiration chamber (model 6299). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  14. Effects of regionally applied heating on the respiration of wild type ...

    African Journals Online (AJOL)

    Nocturnal dark respiration (Rn) in wild type and transgenic soybean plants ... Illinois, USA under ambient and elevated CO2 conditions was examined in this study. ... Experimental plants were transferred to a controlled growth chamber at V4 ...

  15. Respiration in Aquatic Insects.

    Science.gov (United States)

    MacFarland, John

    1985-01-01

    This article: (1) explains the respiratory patterns of several freshwater insects; (2) describes the differences and mechanisms of spiracular cutaneous, and gill respiration; and (3) discusses behavioral aspects of selected aquatic insects. (ML)

  16. Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature

    Science.gov (United States)

    Gauthier, Paul P. G.; Crous, Kristine Y.; Ayub, Gohar; Duan, Honglang; Weerasinghe, Lasantha K.; Ellsworth, David S.; Tjoelker, Mark G.; Evans, John R.; Tissue, David T.; Atkin, Owen K.

    2014-01-01

    Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R dark), and the short-term T response of R dark were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T–response curves of R dark measured over the 15–65 °C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R dark measured at T CO2], growth T, and drought on T response of R dark. However, drought increased R dark at high leaf T typical of heatwave events (35–45 °C), and increased the measuring T at which maximal rates of R dark occurred (T max) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q 10 of R dark (i.e. proportional rise in R dark per 10 °C) over the 15–35 °C range, while drought increased Q 10 values between 35 °C and 45 °C. Collectively, the study highlights the dynamic nature of the T dependence of R dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2]. PMID:25205579

  17. How much work is expended for respiration?

    Science.gov (United States)

    Johnson, A T

    1993-01-01

    The rate of work expended to move air in the respiratory system has been determined for five different airflow waveshapes, a non-linear respiratory model and five exercise levels. As expected, the rectangular waveshape was the most efficient. Model conditions were then changed one a time: (i) starting lung volume was allowed to vary, (ii) exhalation flow limitation was added, (iii) respiration was considered to be a metabolic burden determining part of the ventilation requirement and (iv) a respirator mask was added. Although there is no direct work advantage to varying initial lung volume, such volume changes appear to be dictated by the asymmetry of lung recoil pressure about the lung relaxation volume; allowing the work of respiration to become a metabolic burden clearly shows why respiratory waveforms change from rest to exercise; and, adding a respirator imposes a severe respiratory burden on the wearer engaging in moderate, heavy and very heavy exercise.

  18. Dark energy and dark matter

    International Nuclear Information System (INIS)

    Comelli, D.; Pietroni, M.; Riotto, A.

    2003-01-01

    It is a puzzle why the densities of dark matter and dark energy are nearly equal today when they scale so differently during the expansion of the universe. This conundrum may be solved if there is a coupling between the two dark sectors. In this Letter we assume that dark matter is made of cold relics with masses depending exponentially on the scalar field associated to dark energy. Since the dynamics of the system is dominated by an attractor solution, the dark matter particle mass is forced to change with time as to ensure that the ratio between the energy densities of dark matter and dark energy become a constant at late times and one readily realizes that the present-day dark matter abundance is not very sensitive to its value when dark matter particles decouple from the thermal bath. We show that the dependence of the present abundance of cold dark matter on the parameters of the model differs drastically from the familiar results where no connection between dark energy and dark matter is present. In particular, we analyze the case in which the cold dark matter particle is the lightest supersymmetric particle

  19. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Directory of Open Access Journals (Sweden)

    Or Sperling

    Full Text Available Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq. cm(-3 yr(-1 on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  20. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Science.gov (United States)

    Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  1. Dark matters

    International Nuclear Information System (INIS)

    Silk, Joseph

    2010-01-01

    One of the greatest mysteries in the cosmos is that it is mostly dark. That is, not only is the night sky dark, but also most of the matter and the energy in the universe is dark. For every atom visible in planets, stars and galaxies today there exists at least five or six times as much 'Dark Matter' in the universe. Astronomers and particle physicists today are seeking to unravel the nature of this mysterious but pervasive dark matter, which has profoundly influenced the formation of structure in the universe. Dark energy remains even more elusive, as we lack candidate fields that emerge from well established physics. I will describe various attempts to measure dark matter by direct and indirect means, and discuss the prospects for progress in unravelling dark energy.

  2. Interacting warm dark matter

    International Nuclear Information System (INIS)

    Cruz, Norman; Palma, Guillermo; Zambrano, David; Avelino, Arturo

    2013-01-01

    We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ m α ρ e β form, where ρ m and ρ e are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ,α,β) as well as w m and w e of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ,α,β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used

  3. The role of alternative cyanide-insensitive respiration in plants. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Raskin, Ilya

    1997-09-29

    This DOE funded research concentrated on the investigation of the role of respiration and oxidative stress in plant biology. Initially the authors concentrated on the possible role of cyanide-insensitive respiration in counteracting the deleterious effects of chilling stress. Although plants are considered to be poikilotherms, there are a few examples of thermogenesis, in which the tissue temperature increases well above ambient. They suggested that differences between thermogenic and non-thermogenic plants may be quantitative rather than qualitative, and that heat from increased respiration may have a local protective effect on the mitochondria, slowing or reducing the effects of chilling. They proposed that this is accomplished by a large increase in respiration, predominantly via the alternative pathway. They measured the increases in respiration, particularly via the alternative pathway, in response to chilling. They have also quantified the associated increases in heat evolution in response to chilling in a number of plant species using a microcalorimeter. For example, after 8 h exposure to 8 C, heat evolution in chilling-sensitive species increased 47--98%, compared to 7--22% for the chilling-resistant species. No increase in heat evolution was observed in the extremely chilling-sensitive ornamental Episcka cupreata (Hook). Increases in heat evolution were observed when plants were chilled in constant light or in the dark, but not when plants were chilled at high humidity. Heat evolution by mitochondria isolated from potato tuber slices were also measured. These values, together with measurements of the heat capacity of isolated mitochondria and counting of the mitochondria by flow cytometry, allow calculation of theoretical maximal rates of heating and the heat produced per mitochondrion. The obtained data was consistent with the protective role of respiratory heat production in cold-stressed plants.

  4. Dark Matter

    Directory of Open Access Journals (Sweden)

    Einasto J.

    2011-06-01

    Full Text Available I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic web.

  5. Dark stars

    DEFF Research Database (Denmark)

    Maselli, Andrea; Pnigouras, Pantelis; Nielsen, Niklas Grønlund

    2017-01-01

    to the formation of compact objects predominantly made of dark matter. Considering both fermionic and bosonic (scalar φ4) equations of state, we construct the equilibrium structure of rotating dark stars, focusing on their bulk properties and comparing them with baryonic neutron stars. We also show that these dark......Theoretical models of self-interacting dark matter represent a promising answer to a series of open problems within the so-called collisionless cold dark matter paradigm. In case of asymmetric dark matter, self-interactions might facilitate gravitational collapse and potentially lead...... objects admit the I-Love-Q universal relations, which link their moments of inertia, tidal deformabilities, and quadrupole moments. Finally, we prove that stars built with a dark matter equation of state are not compact enough to mimic black holes in general relativity, thus making them distinguishable...

  6. Soil Respiration under Different Land Uses in Eastern China

    Science.gov (United States)

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  7. Dark energy and dark matter in galaxy halos

    International Nuclear Information System (INIS)

    Tetradis, N.

    2006-01-01

    We consider the possibility that the dark matter is coupled through its mass to a scalar field associated with the dark energy of the Universe. In order for such a field to play a role at the present cosmological distances, it must be effectively massless at galactic length scales. We discuss the effect of the field on the distribution of dark matter in galaxy halos. We show that the profile of the distribution outside the galaxy core remains largely unaffected and the approximately flat rotation curves persist. The dispersion of the dark matter velocity is enhanced by a potentially large factor relative to the case of zero coupling between dark energy and dark matter. The counting rates in terrestrial dark matter detectors are similarly enhanced. Existing bounds on the properties of dark matter candidates can be extended to the coupled case, by taking into account the enhancement factor

  8. The dark energy survey Y1 supernova search: Survey strategy compared to forecasts and the photometric type Is SN volumetric rate

    Science.gov (United States)

    Fischer, John Arthur

    For 70 years, the physics community operated under the assumption that the expansion of the Universe must be slowing due to gravitational attraction. Then, in 1998, two teams of scientists used Type Ia supernovae to discover that cosmic expansion was actually acceler- ating due to a mysterious "dark energy." As a result, Type Ia supernovae have become the most cosmologically important transient events in the last 20 years, with a large amount of effort going into their discovery as well as understanding their progenitor systems. One such probe for understanding Type Ia supernovae is to use rate measurements to de- termine the time delay between star formation and supernova explosion. For the last 30 years, the discovery of individual Type Ia supernova events has been accelerating. How- ever, those discoveries were happening in time-domain surveys that probed only a portion of the redshift range where expansion was impacted by dark energy. The Dark Energy Survey (DES) is the first project in the "next generation" of time-domain surveys that will discovery thousands of Type Ia supernovae out to a redshift of 1.2 (where dark energy be- comes subdominant) and DES will have better systematic uncertainties over that redshift range than any survey to date. In order to gauge the discovery effectiveness of this survey, we will use the first season's 469 photometrically typed supernovee and compare it with simulations in order to update the full survey Type Ia projections from 3500 to 2250. We will then use 165 of the 469 supernovae out to a redshift of 0.6 to measure the supernovae rate both as a function of comoving volume and of the star formation rate as it evolves with redshift. We find the most statistically significant prompt fraction of any survey to date (with a 3.9? prompt fraction detection). We will also reinforce the already existing tension in the measurement of the delayed fraction between high (z > 1.2) and low red- shift rate measurements, where we find no

  9. Stimulation of mitochondrial respiration induced by laser irradiation in the presence of rhodamine dyes

    International Nuclear Information System (INIS)

    Krasnikov, B.F.; Zorov, D.B.

    1996-01-01

    The effect of micromolar concentration of rhodamine 123 (methylrhodamine) and ethyl and amyl esters of unsubstituted rhodamine on oxygen consumption by rat liver mitochondria was studied under irradiation by an argon laser (488 and 514 nm). Irradiation of mitochondria in the presence of rhodamine stimulates their respiration. Light-induced stimulation of respiration is not inhibited by free radical scavenger ionol and by inhibitor of the permeability transition pore cyclosporine A. Stimulation of respiration by moderate doses of radiation is reversed in the dark. Increase in radiation dose resulted in only partial reversal of stimulated respiration in the dark. Rhodamine efficacy in stimulation of mitochondrial respiration depends on its structure (amyl > ethyl > methylrhodamine). 22 refs.; 4 figs

  10. Partitioning of ecosystem respiration in a beech forest

    DEFF Research Database (Denmark)

    Brændholt, Andreas; Ibrom, Andreas; Larsen, Klaus Steenberg

    2018-01-01

    Terrestrial ecosystem respiration (Reco) represents a major component of the global carbon cycle. It consists of many sub-components, such as aboveground plant respiration and belowground root and microbial respiration, each of which may respond differently to abiotic factors, and thus to global...... of Reco in a temperate beech forest at diel, seasonal and annual time scales. Reco was measured by eddy covariance while respiration rates from soil, tree stems and isolated coarse tree roots were measured bi-hourly by an automated closed-chamber system. Soil respiration (Rsoil) was measured in intact...... plots, and heterotrophic Rsoil was measured in trenched plots. Tree stem (Rstem) and coarse root (Rroot) respiration were measured by custom made closed-chambers. We found that the contribution of Rstem to total Reco varied across the year, by only accounting for 6% of Reco during winter and 16% during...

  11. Dark Matter

    International Nuclear Information System (INIS)

    Holt, S. S.; Bennett, C. L.

    1995-01-01

    These proceedings represent papers presented at the Astrophysics conference in Maryland, organized by NASA Goddard Space Flight Center and the University of Maryland. The topics covered included low mass stars as dark matter, dark matter in galaxies and clusters, cosmic microwave background anisotropy, cold and hot dark matter, and the large scale distribution and motions of galaxies. There were eighty five papers presented. Out of these, 10 have been abstracted for the Energy Science and Technology database

  12. Dark energy

    International Nuclear Information System (INIS)

    Wang, Yun

    2010-01-01

    Dark energy research aims to illuminate the mystery of the observed cosmic acceleration, one of the fundamental problems in physics and astronomy today. This book presents a systematic and detailed review of the current state of dark energy research, with the focus on the examination of the major observational techniques for probing dark energy. It can be used as a textbook to train students and others who wish to enter this extremely active field in cosmology.

  13. Dark Matter

    International Nuclear Information System (INIS)

    Bashir, A.; Cotti, U.; De Leon, C. L.; Raya, A; Villasenor, L.

    2008-01-01

    One of the biggest scientific mysteries of our time resides in the identification of the particles that constitute a large fraction of the mass of our Universe, generically known as dark matter. We review the observations and the experimental data that imply the existence of dark matter. We briefly discuss the properties of the two best dark-matter candidate particles and the experimental techniques presently used to try to discover them. Finally, we mention a proposed project that has recently emerged within the Mexican community to look for dark matter

  14. Effect of organic loading rate on dark fermentative hydrogen production in the continuous stirred tank reactor and continuous mixed immobilized sludge reactor from waste pastry hydrolysate.

    Science.gov (United States)

    Han, Wei; Hu, Yunyi; Li, Shiyi; Nie, Qiulin; Zhao, Hongting; Tang, Junhong

    2016-12-01

    Waste pastry (6%, w/v) was hydrolyzed by the produced glucoamylase and protease to obtain the glucose (19.8g/L) and free amino nitrogen (179mg/L) solution. Then, the effect of organic loading rate (OLR) (8-40kgCOD/(m 3 d)) on dark fermentative hydrogen production in the continuous stirred tank reactor (CSTR) and continuous mixed immobilized sludge reactor (CMISR) from waste pastry hydrolysate was investigated and compared. The maximum hydrogen production rate of CSTR (277.76mL/(hL)) and CMISR (320.2mL/(hL)) were achieved at OLR of 24kgCOD/(m 3 d) and 32kgCOD/(m 3 d), respectively. Carbon recovery ranged from 75.2-84.1% in the CSTR and CMISR with the balance assumed to be converted to biomass. One gram waste pastry could produce 0.33g (1.83mmol) glucose which could be further converted to 79.24mL (3.54mmol) hydrogen in the CMISR or 91.66mL (4.09mmol) hydrogen in the CSTR. This is the first study which reports dark fermentative hydrogen production from waste pastry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. [Dynamic changes in soil respiration components and their regulating factors in the Moso bamboo plantation in subtropical China].

    Science.gov (United States)

    Yang, Wen-jia; Li, Yong-fu; Jiang, Pei-kun; Zhou, Guo-mo; Liu, Juan

    2015-10-01

    Dynamic changes (from April 2013 to March 2014) in soil respiration components were investigated by Li-8100 in the Moso bamboo plantation in Lin' an City, Zhejiang Province. Results showed that the average annual values for the soil total respiration rate, heterotrophic respiration rate, and autotrophic respiration rate in the Moso bamboo plantation were 2.93, 1.92 and 1.01 imol CO2 . m-2 . s-1, respectively. The soil respiration rate and its components exhibited strongly a seasonal dynamic pattern. The maximum appeared in July 2013, and the minimum appeared in January 2014. The annual cumulative CO2 emissions through soil respiration, heterotrophic respiration, and autotrophic respiration were 37.25, 24.61 and 12.64 t CO2 . hm-2 . a-1, respectively. The soil respiration and its components showed a close relation with soil temperature of 5 cm depth, and the corresponding Q10, values at 5 cm depth were 2.05, 1.95 and 2.34, respectively. Both the soil respiration and heterotrophic respiration were correlated to soil water soluble organic C (WSOC) content, but no significant relationship between autotrophic respiration and WSOC was observed. There were no significant relationships between soil respiration components and soil moisture content or microbial biomass C. The seasonal changes in soil respiration components in the Moso bamboo plantation were predominantly controlled by the soil temperature, and the soil WSOC content was an important environmental factor controlling total soil respiration and soil heterotrophic respiration.

  16. Dark matter and dark radiation

    International Nuclear Information System (INIS)

    Ackerman, Lotty; Buckley, Matthew R.; Carroll, Sean M.; Kamionkowski, Marc

    2009-01-01

    We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ('dark electromagnetism') that couples only to dark matter, not to the standard model. The dark matter consists of an equal number of positive and negative charges under the new force, but annihilations are suppressed if the dark-matter mass is sufficiently high and the dark fine-structure constant α-circumflex is sufficiently small. The correct relic abundance can be obtained if the dark matter also couples to the conventional weak interactions, and we verify that this is consistent with particle-physics constraints. The primary limit on α-circumflex comes from the demand that the dark matter be effectively collisionless in galactic dynamics, which implies α-circumflex -3 for TeV-scale dark matter. These values are easily compatible with constraints from structure formation and primordial nucleosynthesis. We raise the prospect of interesting new plasma effects in dark-matter dynamics, which remain to be explored.

  17. Dark Matter

    Indian Academy of Sciences (India)

    What You See Ain't What. You Got, Resonance, Vol.4,. No.9,1999. Dark Matter. 2. Dark Matter in the Universe. Bikram Phookun and Biman Nath. In Part 11 of this article we learnt that there are compelling evidences from dynamics of spiral galaxies, like our own, that there must be non-luminous matter in them. In this.

  18. Geochemical importance of isotopic fractionation during respiration

    International Nuclear Information System (INIS)

    Schleser, G.; Foerstel, H.

    1975-01-01

    In 1935 it was found that atmospheric oxygen contained a relatively greater abundance of the 18 O isotope than did the oxygen bound in water (Dole effect). A major contribution to the fractionation of the stable oxygen isotopes should result from the respiration of microorganisms. In this respect our interest centers on the soil because nearly all organic material produced on land is decomposed within the soil. The oceans are less important because the primary productivity on land is twice the value for the oceans. In a first approach we measured the oxygen isotope fractionation during the respiration of E. coli K12 for different respiration rates. These results, accomplished with a chemostat, indicate that the fractionation factor α of the oxygen isotopes increases with the increasing respiratory activity, measured as Q/sub O 2 /. At low dilution rates or growth rates respectively of about 0.05 h -1 , the fractionation factor amounts to 1.006 increasing to 1.017 at dilution rates of about 1.0 h -1 . The results are interpreted as a kinetic mass fractionation due to the slightly different diffusion coefficients of 16 O 2 and 18 O 16 O. The respiration rates in conjunction with the corresponding fractionation data are compared with the respiration rates of typical soil microorganisms such as Azotobacter, in order to deduce fractionation data for these organisms. This is necessary to calculate a mean global fractionation factor. Understanding the Dole effect with these fractionation processes should finally give us the opportunity to calculate gas-exchange rates between the atmosphere and the oceans, on the basis of the behavior of the stable oxygen isotopes

  19. Carbon dioxide efflux from leaves in light and darkness

    Energy Technology Data Exchange (ETDEWEB)

    Holmgren, P; Jarvis, P G

    1967-01-01

    The efflux of carbon dioxide in light and darkness was measured at low ambient CO/sub 2/ concentrations in leaves of Rumex acetosa. Light carbon dioxide production (photorespiration) was found to depend on irradiance and to differ from dark production as to the response to temperature and ambient concentrations of O/sub 2/ and CO/sub 2/. These observations support previously made suggestions that photorespiration follows a different metabolic pathway to dark respiration.

  20. Exothermic dark matter

    International Nuclear Information System (INIS)

    Graham, Peter W.; Saraswat, Prashant; Harnik, Roni; Rajendran, Surjeet

    2010-01-01

    We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10. The dark matter consists of at least two light states with mass ∼few GeV and splittings ∼5 keV. It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter. Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state downscatters off of a nucleus, becoming a lower energy state. In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.

  1. Simplified pressure method for respirator fit testing.

    Science.gov (United States)

    Han, D; Xu, M; Foo, S; Pilacinski, W; Willeke, K

    1991-08-01

    A simplified pressure method has been developed for fit testing air-purifying respirators. In this method, the air-purifying cartridges are replaced by a pressure-sensing attachment and a valve. While wearers hold their breath, a small pump extracts air from the respirator cavity until a steady-state pressure is reached in 1 to 2 sec. The flow rate through the face seal leak is a unique function of this pressure, which is determined once for all respirators, regardless of the respirator's cavity volume or deformation because of pliability. The contaminant concentration inside the respirator depends on the degree of dilution by the flow through the cartridges. The cartridge flow varies among different brands and is measured once for each brand. The ratio of cartridge to leakflow is a measure of fit. This flow ratio has been measured on human subjects and has been compared to fit factors determined on the same subjects by means of photometric and particle count tests. The aerosol tests gave higher values of fit.

  2. Effects of long-term microgravitation exposure on cell respiration of the rat musculus soleus fibers.

    Science.gov (United States)

    Veselova, O M; Ogneva, I V; Larina, I M

    2011-07-01

    Cell respiration of the m. soleus fibers was studied in Wistar rats treated with succinic acid and exposed to microgravitation for 35 days. The results indicated that respiration rates during utilization of endogenous and exogenous substrates and the maximum respiration rate decreased in animals subjected to microgravitation without succinate treatment. The respiration rate during utilization of exogenous substrate did not increase in comparison with that on endogenous substrates. Succinic acid prevented the decrease in respiration rate on endogenous substrates and the maximum respiration rate. On the other hand, the respiration rate on exogenous substrates was reduced in vivarium control rats receiving succinate in comparison with intact control group. That could indicate changed efficiency of complex I of the respiratory chain due to reciprocal regulation of the tricarbonic acid cycle.

  3. Development of dark-striped field mice, Apodemus agrarius coreae, as a biological dosimeter in a radio-ecological monitoring system: 2. Survival rates and hematology

    International Nuclear Information System (INIS)

    Kim, Hee Sun; Kim, Chong Soon; Nishmura, Y.

    2005-01-01

    Regarding the management of nuclear power plants and the installation of facilities for radiation waste storage: social concerns over radiation safety are increasing. To understand how environmental radiation affects on human beings, the development of an reasonable monitoring system is required. The existing radio-environmental surveillance systems can be classified into physical and biological monitoring systems. The wild small animals and livestocks were reported to be effective biological indicators of environmental radiation This study investigated the possibility of using dark-striped field mice as a biological dosimetric model to assess the effect of radiation on the human environments. For this study, the criteria for the biological dosimeters of environmental radiation were established as the following: first, it should be an animal from a clear background of species; second, it should inhabit a broad range of areas and in considerable numbers; third, it should maintain identical ecological characteristics; fourth, it should be cohabitating with humans; fifth, it should have been consuming food found in their habitat; and finally, it should indicate a clear doseresponse relationship with high sensitivity. Based on such criteria, this study investigated the possibility of using dark-striped field mice as an effective biological dosimeter. Primarily, their species were classified based on their morphological external characteristics and isoenzymic patterns. The taxonomically classified darkstriped field mice, A. agrarius coreae, were then irradiated to investigate their radiation sensitivity based on the survival rate and hematology in this study

  4. Development of dark-striped field mice, Apodemus agrarius coreae, as a biological dosimeter in a radio-ecological monitoring system: 2. Survival rates and hematology

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee Sun; Kim, Chong Soon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of); Nishmura, Y. [National Institute of Radiological Sciences, Chiba (Japan)

    2005-07-01

    Regarding the management of nuclear power plants and the installation of facilities for radiation waste storage: social concerns over radiation safety are increasing. To understand how environmental radiation affects on human beings, the development of an reasonable monitoring system is required. The existing radio-environmental surveillance systems can be classified into physical and biological monitoring systems. The wild small animals and livestocks were reported to be effective biological indicators of environmental radiation This study investigated the possibility of using dark-striped field mice as a biological dosimetric model to assess the effect of radiation on the human environments. For this study, the criteria for the biological dosimeters of environmental radiation were established as the following: first, it should be an animal from a clear background of species; second, it should inhabit a broad range of areas and in considerable numbers; third, it should maintain identical ecological characteristics; fourth, it should be cohabitating with humans; fifth, it should have been consuming food found in their habitat; and finally, it should indicate a clear doseresponse relationship with high sensitivity. Based on such criteria, this study investigated the possibility of using dark-striped field mice as an effective biological dosimeter. Primarily, their species were classified based on their morphological external characteristics and isoenzymic patterns. The taxonomically classified darkstriped field mice, A. agrarius coreae, were then irradiated to investigate their radiation sensitivity based on the survival rate and hematology in this study.

  5. Respirators. Does your face fit

    Energy Technology Data Exchange (ETDEWEB)

    Caro, N M; Else, D

    1981-04-01

    The authors carried out a survey of face sizes of men and women of four different ethnic origins and carried out face-seal leakage trials on four corresponding test panels. No single respirator design is likely to fit all members of the workforce, and it may be necessary to stock respirators from more than one manufacturers.Three or four different respirators or size of respirator may be needed. However, the use of lossely-fitting respirators such as Airsteam helmets could remove the necessity for exhaustive fitting procedures.

  6. Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis.

    Science.gov (United States)

    Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A J

    2017-06-15

    Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 µmol l -1 ) and water flow (1-1.6 versus 4-13 cm s -1 ) in a repeated measures design. Dark respiration was enhanced by increased flow and increased oxygen saturation in an interactive way, which relates to improved oxygen influx into the coral tissue. Oxygen saturation did not influence net photosynthesis: neither hypoxia nor hyperoxia affected net photosynthesis, irrespective of flow and pH, which suggests that hyperoxia does not induce high rates of photorespiration in this coral. Flow and pH had a synergistic effect on net photosynthesis: at high flow, a decrease in pH stimulated net photosynthesis by 14%. These results indicate that for this individual of G. fascicularis , increased uptake of carbon dioxide rather than increased efflux of oxygen explains the beneficial effect of water flow on photosynthesis. Rates of net photosynthesis measured in this study are among the highest ever recorded for scleractinian corals and confirm a strong scope for growth. © 2017. Published by The Company of Biologists Ltd.

  7. Abnormal mitochondrial respiration in failed human myocardium.

    Science.gov (United States)

    Sharov, V G; Todor, A V; Silverman, N; Goldstein, S; Sabbah, H N

    2000-12-01

    Chronic heart failure (HF) is associated with morphologic abnormalities of cardiac mitochondria including hyperplasia, reduced organelle size and compromised structural integrity. In this study, we examined whether functional abnormalities of mitochondrial respiration are also present in myocardium of patients with advanced HF. Mitochondrial respiration was examined using a Clark electrode in an oxygraph cell containing saponin-skinned muscle bundles obtained from myocardium of failed explanted human hearts due to ischemic (ICM, n=9) or idiopathic dilated (IDC, n=9) cardiomyopathy. Myocardial specimens from five normal donor hearts served as controls (CON). Basal respiratory rate, respiratory rate after addition of the substrates glutamate and malate (V(SUB)), state 3 respiration (after addition of ADP, V(ADP)) and respiration after the addition of atractyloside (V(AT)) were measured in scar-free muscle bundles obtained from the subendocardial (ENDO) and subepicardial (EPI) thirds of the left ventricular (LV) free wall, interventricular septum and right ventricular (RV) free wall. There were no differences in basal and substrate-supported respiration between CON and HF regardless of etiology. V(ADP)was significantly depressed both in ICM and IDC compared to CON in all the regions studied. The respiratory control ratio, V(ADP)/V(AT), was also significantly decreased in HF compared to CON. In both ICM and IDC, V(ADP)was significantly lower in ENDO compared to EPI. The results indicate that mitochondrial respiration is abnormal in the failing human heart. The findings support the concept of low myocardial energy production in HF via oxidative phosphorylation, an abnormality with a potentially impact on global cardiac performance. Copyright 2000 Academic Press.

  8. [Temperature sensitivity of wheat plant respiration and soil respiration influenced by increased UV-B radiation from elongation to flowering periods].

    Science.gov (United States)

    Chen, Shu-Tao; Hu, Zheng-Hua; Li, Han-Mao; Ji, Yu-Hong; Yang, Yan-Ping

    2009-05-15

    Field experiment was carried out in the spring of 2008 in order to investigate the effects of increased UV-B radiation on the temperature sensitivity of wheat plant respiration and soil respiration from elongation to flowering periods. Static chamber-gas chromatography method was used to measure ecosystem respiration and soil respiration under 20% UV-B radiation increase and control. Environmental factors such as temperature and moisture were also measured. Results indicated that supplemental UV-B radiation inhibited the ecosystem respiration and soil respiration from wheat elongation to flowering periods, and the inhibition effect was more obvious for soil respiration than for ecosystem respiration. Ecosystem respiration rates, on daily average, were 9%, 9%, 3%, 16% and 30% higher for control than for UV-B treatment forthe five measurement days, while soil respiration rates were 99%, 93%, 106%, 38% and 10% higher for control than for UV-B treatment. The Q10s (temperature sensitivity coefficients) for plant respiration under control and UV-B treatments were 1.79 and 1.59, respectively, while the Q10s for soil respiration were 1.38 and 1.76, respectively. The Q10s for ecosystem respiration were 1.65 and 1.63 under CK and UV-B treatments, respectively. Supplemental UV-B radiation caused a lower Q10 for plant respiration and a higher Q10 for soil respiration, although no significant effect of supplemental UV-B radiation on the Q10 for ecosystem respiration was found.

  9. Planktonic production and respiration in a subtropical lake dominated by Cyanobacteria.

    Science.gov (United States)

    Tonetta, D; Laudares-Silva, R; Petrucio, M M

    2015-05-01

    Planktonic primary production and respiration rates were estimated in a subtropical coastal lake dominated by Cyanobacteria in order to investigate the temporal and vertical variation in this lake and to evaluate its relationships with limnological variables and phytoplankton. Light and dark bottles were incubated at four different depths in the central part of the lake and were performed bimonthly from June/2009 to December/2010. No significant difference was evident among depths in relation to phytoplankton, limnological variables and metabolic rates. However, the highest production rates were recorded at the surface, and decreased towards the bottom, coupled with phytoplanktonic photosynthetic capacity. Wind induced mixing in Peri Lake played an important role in nutrient and phytoplankton redistribution, characterizing this lake as polymictic. According to density and biovolume, the phytoplankton community was dominated by filamentous Cyanobacteria, especially Cylindrospermopsis raciborskii (Woloszynska) Seenayya and Subba-Raju. This study has shown that both water temperature and nutrient availability drive phytoplankton growth and consequently the temporal variation in metabolic rates, where respiration is higher than primary production.

  10. Planktonic production and respiration in a subtropical lake dominated by Cyanobacteria

    Directory of Open Access Journals (Sweden)

    D. Tonetta

    Full Text Available Planktonic primary production and respiration rates were estimated in a subtropical coastal lake dominated by Cyanobacteria in order to investigate the temporal and vertical variation in this lake and to evaluate its relationships with limnological variables and phytoplankton. Light and dark bottles were incubated at four different depths in the central part of the lake and were performed bimonthly from June/2009 to December/2010. No significant difference was evident among depths in relation to phytoplankton, limnological variables and metabolic rates. However, the highest production rates were recorded at the surface, and decreased towards the bottom, coupled with phytoplanktonic photosynthetic capacity. Wind induced mixing in Peri Lake played an important role in nutrient and phytoplankton redistribution, characterizing this lake as polymictic. According to density and biovolume, the phytoplankton community was dominated by filamentous Cyanobacteria, especially Cylindrospermopsis raciborskii (Woloszynska Seenayya and Subba-Raju. This study has shown that both water temperature and nutrient availability drive phytoplankton growth and consequently the temporal variation in metabolic rates, where respiration is higher than primary production.

  11. Can we distinguish autotrophic respiration from heterotrophic respiration in a field site using high temporal resolution CO2 flux measurements?

    Science.gov (United States)

    Biro, Beatrice; Berger, Sina; Praetzel, Leandra; Blodau, Christian

    2016-04-01

    The processes behind C-cycling in peatlands are important to understand for assessing the vulnerability of peatlands as carbon sinks under changing climate conditions. Especially boreal peatlands are likely to underlie strong alterations in the future. It is expected that C-pools that are directly influenced by vegetation and water table fluctuations can be easily destabilized. The CO2 efflux through respiration underlies autotrophic and heterotrophic processes that show different feedbacks on changing environmental conditions. In order to understand the respiration fluxes better for more accurate modelling and prognoses, the determination of the relative importance of different respiration sources is necessary. Earlier studies used e.g. exfoliation experiments, incubation experiments or modelling approaches to estimate the different respiration sources for the total ecosystem respiration (Reco). To further the understanding in this topic, I want to distinguish autotrophic and heterotrophic respiration using high temporal resolution measurements. The study site was selected along a hydrological gradient in a peatland in southern Ontario (Canada) and measurements were conducted from May to September 2015 once per month. Environmental controls (water table, soil temperature and soil moisture) that effect the respiration sources were recorded. In my study I used a Li-COR 6400XT and a Los Gatos greenhouse gas analyzer (GGA). Reco was determined by chamber flux measurements with the GGA, while simultaneously CO2 respiration measurements on different vegetation compartments like roots, leaves and mosses were conducted using the Li-COR 6400XT. The difference between Reco and autotrophic respiration equals heterotrophic respiration. After the measurements, the vegetation plots were harvested and separated for all compartments (leaves, roots, mosses, soil organic matter), dried and weighed. The weighted respiration rates from all vegetation compartments sum up to

  12. Dark catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Prateek; Cyr-Racine, Francis-Yan; Randall, Lisa; Scholtz, Jakub, E-mail: prateekagrawal@fas.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: randall@physics.harvard.edu, E-mail: jscholtz@physics.harvard.edu [Department of Physics, Harvard University, 17 Oxford St., Cambridge, MA 02138 (United States)

    2017-08-01

    Recently it was shown that dark matter with mass of order the weak scale can be charged under a new long-range force, decoupled from the Standard Model, with only weak constraints from early Universe cosmology. Here we consider the implications of an additional charged particle C that is light enough to lead to significant dissipative dynamics on galactic times scales. We highlight several novel features of this model, which can be relevant even when the C particle constitutes only a small fraction of the number density (and energy density). We assume a small asymmetric abundance of the C particle whose charge is compensated by a heavy X particle so that the relic abundance of dark matter consists mostly of symmetric X and X-bar , with a small asymmetric component made up of X and C . As the universe cools, it undergoes asymmetric recombination binding the free C s into ( XC ) dark atoms efficiently. Even with a tiny asymmetric component, the presence of C particles catalyzes tight coupling between the heavy dark matter X and the dark photon plasma that can lead to a significant suppression of the matter power spectrum on small scales and lead to some of the strongest bounds on such dark matter theories. We find a viable parameter space where structure formation constraints are satisfied and significant dissipative dynamics can occur in galactic haloes but show a large region is excluded. Our model shows that subdominant components in the dark sector can dramatically affect structure formation.

  13. Production of Purely Gravitational Dark Matter

    OpenAIRE

    Ema, Yohei; Nakayama, Kazunori; Tang, Yong

    2018-01-01

    In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflati...

  14. Inelastic dark matter

    International Nuclear Information System (INIS)

    Smith, David; Weiner, Neal

    2001-01-01

    Many observations suggest that much of the matter of the universe is nonbaryonic. Recently, the DAMA NaI dark matter direct detection experiment reported an annual modulation in their event rate consistent with a WIMP relic. However, the Cryogenic Dark Matter Search (CDMS) Ge experiment excludes most of the region preferred by DAMA. We demonstrate that if the dark matter can only scatter by making a transition to a slightly heavier state (Δm∼100 keV), the experiments are no longer in conflict. Moreover, differences in the energy spectrum of nuclear recoil events could distinguish such a scenario from the standard WIMP scenario. Finally, we discuss the sneutrino as a candidate for inelastic dark matter in supersymmetric theories

  15. Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

    DEFF Research Database (Denmark)

    Hancke, Kasper; Glud, R.N.

    2004-01-01

    ABSTRACT: Short-term temperature effects on respiration and photosynthesis were investigated in intact diatom-dominated benthic communities, collected at 2 temperate and 1 high-arctic subtidal sites. Areal rates of total (TOE) and diffusive (DOE) O2 exchange were determined from O2-microsensor....... This can be ascribed to changes in physical and biological controls during resuspension. Gross photosynthesis was measured with the light-dark shift method at the 2 temperate sites. Both areal (Pgross) and volumetric (Pgross,vol) rates increased with temperature to an optimum temperature at 12 and 15°C......, with a Q10 for Pgross of 2.2 and 2.6 for the 2 sites, respectively. The gross photosynthesis response could be categorised as psychrotrophic for both sites and no temperature adaptation was observed between the 2 sites. Our measurements document that temperature stimulates heterotrophic activity more than...

  16. Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

    Science.gov (United States)

    Soler-Crespo, R. A.; Monje, O. A.

    2010-01-01

    Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

  17. Modeling respiration from snags and coarse woody debris before and after an invasive gypsy moth disturbance

    Science.gov (United States)

    Heidi J. Renninger; Nicholas Carlo; Kenneth L. Clark; Karina V.R. Schäfer

    2014-01-01

    Although snags and coarse woody debris are a small component of ecosystem respiration, disturbances can significantly increase the mass and respiration from these carbon (C) pools. The objectives of this study were to (1) measure respiration rates of snags and coarse woody debris throughout the year in a forest previously defoliated by gypsy moths, (2) develop models...

  18. Dark coupling

    International Nuclear Information System (INIS)

    Gavela, M.B.; Hernández, D.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

    2009-01-01

    The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ''phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed

  19. Dark Matter

    Science.gov (United States)

    Lincoln, Don

    2013-01-01

    It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of…

  20. Respirable dust and respirable silica exposure in Ontario gold mines.

    Science.gov (United States)

    Verma, Dave K; Rajhans, Gyan S; Malik, Om P; des Tombe, Karen

    2014-01-01

    A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978-1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7-8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978-1979, the industry wide mean respirable dust was about 1 mg/m(3), and the mean respirable silica was 0.08 mg/m(3.)The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers' compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis.

  1. Combination of On-line pH and Oxygen Transfer Rate Measurement in Shake Flasks by Fiber Optical Technique and Respiration Activity MOnitoring System (RAMOS

    Directory of Open Access Journals (Sweden)

    Jochen Büchs

    2007-12-01

    Full Text Available Shake flasks are commonly used for process development in biotechnologyindustry. For this purpose a lot of information is required from the growth conditions duringthe fermentation experiments. Therefore, Anderlei et al. developed the RAMOS technology[1, 2], which proviedes on-line oxygen and carbondioxide transfer rates in shake flasks.Besides oxygen consumption, the pH in the medium also plays an important role for thesuccessful cultivation of micro-organisms and for process development. For online pHmeasurement fiber optical methods based on fluorophores are available. Here a combinationof the on-line Oxygen Transfer Rate (OTR measurements in the RAMOS device with anon-line, fiber optical pH measurement is presented. To demonstrate the application of thecombined measurement techniques, Escherichia coli cultivations were performed and on-line pH measurements were compared with off-line samples. The combination of on-lineOTR and pH measurements gives a lot of information about the cultivation and, therefore, itis a powerful technique for monitoring shake flask experiments as well as for processdevelopment.

  2. respiration and transpiration characteristics of selected fresh fruits

    African Journals Online (AJOL)

    AISA

    were higher in optimal atmospheres. The Q10 values ... High respiration rates increase tissue aging and decrease the ability of the product to repel ... Two types of containers were used for the ..... availability of oxygen around the product also.

  3. Photosynthesis and dark respiration of leaves of terrestrial carnivorous plants

    Czech Academy of Sciences Publication Activity Database

    Hájek, Tomáš; Adamec, Lubomír

    2010-01-01

    Roč. 65, č. 1 (2010), s. 69-74 ISSN 0006-3088 Institutional research plan: CEZ:AV0Z60050516 Keywords : CO2 gasometry * light photosynthetic curves * costs of carnivory Subject RIV: EF - Botanics Impact factor: 0.609, year: 2010

  4. The dark universe dark matter and dark energy

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    According to the standard cosmological model, 95% of the present mass density of the universe is dark: roughly 70% of the total in the form of dark energy and 25% in the form of dark matter. In a series of four lectures, I will begin by presenting a brief review of cosmology, and then I will review the observational evidence for dark matter and dark energy. I will discuss some of the proposals for dark matter and dark energy, and connect them to high-energy physics. I will also present an overview of an observational program to quantify the properties of dark energy.

  5. [Effects of management regime on soil respiration from agroecosystems].

    Science.gov (United States)

    Chen, Shu-tao; Zhu, Da-wei; Niu, Chuan-po; Zou, Jian-wen; Wang, Chao; Sun, Wen-juan

    2009-10-15

    In order to examine the effects of management regime, such as nitrogen application and plowing method, on soil respiration from farmland, the static opaque chamber-gas chromatograph method was used to measure soil CO2 fluxes in situ. The field measurement was carried out for 5 growing seasons, which were the 2002-2003 wheat, 2003 maize and soybean, 2003-2004 wheat, 2004 maize and 2004-2005 wheat seasons. Our results showed that soil respiration increased in fertilizer-applied treatments compared with no fertilizer treatment after 3 times of fertilizer application on 9 November 2002, 14 February and 26 March 2003. And the most obvious increase appeared following the third fertilizer application. No significant difference in soil respiration was found among several fertilizer application treatments. The effect of plowing depth on soil respiration was contingent on preceding cropping practice. Over the 2003-2004 wheat-growing seasons (its preceding cropping practice was rice paddy), mean soil respiration rates were not significant different (p > 0.05) between no plowing treatment and shallow plowing treatment. The shallow plowing treatment CT2 led to higher soil CO2 losses compared with no plowing treatment of NT2 in the 2004 maize-growing season, however, the significant higher (p soil respiration rates occurred with no plowing treatment of NT3 in the following 2004-2005 wheat-growing season. Intensive plowing (25 cm depth), compared with no plowing practice (NT4), increased soil respiration significantly during the 2004-2005 wheat-growing season. Regression analysis showed that the exponential function could be employed to fit the relationship between soil respiration and temperature. The exponential relationship yielded the Q10 values which were varied from 1.26 to 3.60, with a mean value of 2.08. To evaluate the effect of temperature on soil respiration, the CO2 emission fluxes were normalized for each treatment and each crop growing season. Plotting the

  6. Temperature response of soil respiration largely unaltered with experimental warming

    Science.gov (United States)

    Carey, Joanna C.; Tang, Jianwu; Templer, Pamela H.; Kroeger, Kevin D.; Crowther, Thomas W.; Burton, Andrew J.; Dukes, Jeffrey S.; Emmett, Bridget; Frey, Serita D.; Heskel, Mary A.; Jiang, Lifen; Machmuller, Megan B.; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B.; Reinsch, Sabine; Wang, Xin; Allison, Steven D.; Bamminger, Chris; Bridgham, Scott; Collins, Scott L.; de Dato, Giovanbattista; Eddy, William C.; Enquist, Brian J.; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R.; Steenberg Larsen, Klaus; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M.; Penuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward B.; Reinmann, Andrew B.; Reynolds, Lorien L.; Schmidt, Inger K.; Shaver, Gaius R.; Strong, Aaron L.; Suseela, Vidya; Tietema, Albert

    2016-01-01

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

  7. Community respiration/production and bacterial activity in the upper water column of the central Arctic Ocean

    Science.gov (United States)

    Sherr, Barry F.; Sherr, Evelyn B.

    2003-04-01

    Community metabolism (respiration and production) and bacterial activity were assessed in the upper water column of the central Arctic Ocean during the SHEBA/JOIS ice camp experiment, October 1997-September 1998. In the upper 50 m, decrease in integrated dissolved oxygen (DO) stocks over a period of 124 d in mid-winter suggested a respiration rate of ˜3.3 nM O 2 h -1 and a carbon demand of ˜4.5 gC m -2. Increase in 0-50 m integrated stocks of DO during summer implied a net community production of ˜20 gC m -2. Community respiration rates were directly measured via rate of decrease in DO in whole seawater during 72-h dark incubation experiments. Incubation-based respiration rates were on average 3-fold lower during winter (11.0±10.6 nM O 2 h -1) compared to summer (35.3±24.8 nM O 2 h -1). Bacterial heterotrophic activity responded strongly, without noticeable lag, to phytoplankton growth. Rate of leucine incorporation by bacteria (a proxy for protein synthesis and cell growth) increased ˜10-fold, and the cell-specific rate of leucine incorporation ˜5-fold, from winter to summer. Rates of production of bacterial biomass in the upper 50 m were, however, low compared to other oceanic regions, averaging 0.52±0.47 ngC l -1 h -1 during winter and 5.1±3.1 ngC l -1 h -1 during summer. Total carbon demand based on respiration experiments averaged 2.4±2.3 mgC m -3 d -1 in winter and 7.8±5.5 mgC m -3 d -1 in summer. Estimated bacterial carbon demand based on bacterial productivity and an assumed 10% gross growth efficiency was much lower, averaging about 0.12±0.12 mgC m -3 d -1 in winter and 1.3±0.7 mgC m -3 d -1 in summer. Our estimates of bacterial activity during summer were an order of magnitude less than rates reported from a summer 1994 study in the central Arctic Ocean, implying significant inter-annual variability of microbial processes in this region.

  8. A MEMS turbine prototype for respiration harvesting

    Science.gov (United States)

    Goreke, U.; Habibiabad, S.; Azgin, K.; Beyaz, M. I.

    2015-12-01

    The design, manufacturing, and performance characterization of a MEMS-scale turbine prototype is reported. The turbine is designed for integration into a respiration harvester that can convert normal human breathing into electrical power through electromagnetic induction. The device measures 10 mm in radius, and employs 12 blades located around the turbine periphery along with ball bearings around the center. Finite element simulations showed that an average torque of 3.07 μNm is induced at 12 lpm airflow rate, which lies in normal breathing levels. The turbine and a test package were manufactured using CNC milling on PMMA. Tests were performed at respiration flow rates between 5-25 lpm. The highest rotational speed was measured to be 9.84 krpm at 25 lpm, resulting in 8.96 mbar pressure drop across the device and 370 mW actuation power.

  9. Dark Matter

    Indian Academy of Sciences (India)

    As if this was not enough, it turns out that if our knowledge of ... are thought to contain dark matter, although the evidences from them are the .... protons, electrons, neutrons ... ratio of protons to neutrons was close to unity then as they were in ...

  10. Dark Matter

    Indian Academy of Sciences (India)

    The study of gas clouds orbiting in the outer regions of spiral galaxies has revealed that their gravitational at- traction is much larger than the stars alone can provide. Over the last twenty years, astronomers have been forced to postulate the presence of large quantities of 'dark matter' to explain their observations. They are ...

  11. Herd protection effect of N95 respirators in healthcare workers.

    Science.gov (United States)

    Chen, Xin; Chughtai, Abrar Ahmad; MacIntyre, Chandini Raina

    2017-12-01

    Objective To determine if there was herd protection conferred to unprotected healthcare workers (HCWs) by N95 respirators worn by colleagues. Methods Data were analysed from a prospective cluster randomized clinical trial conducted in Beijing, China between 1 December 2008 and 15 January 2009. A minimum compliance level (MCL) of N95 respirators for prevention of clinical respiratory illness (CRI) was set based on various compliance cut-offs. The CRI rates were compared between compliant (≥MCL) and non-compliant (protection from use of N95 respirators by colleagues within a hospital ward.

  12. Dark Matter

    International Nuclear Information System (INIS)

    Audouze, J.; Tran Thanh Van, J.

    1988-01-01

    The book begins with the papers devoted to the experimental search of signatures of the dark matter which governs the evolution of the Universe as a whole. A series of contributions describe the presently considered experimental techniques (cryogenic detectors, supraconducting detectors...). A real dialogue concerning these techniques has been instaured between particle physicists and astrophysicists. After the progress report of the particle physicists, the book provides the reader with an updated situation concerning the research in cosmology. The second part of the book is devoted to the analysis of the backgrounds at different energies such as the possible role of the cooling flows in the constitution of massive galactic halos. Any search of dark matter implies necessarily the analysis of the spatial distributions of the large scale structures of the Universe. This report is followed by a series of statistical analyses of these distributions. These analyses concern mainly universes filled up with cold dark matter. The last paper of this third part concerns the search of clustering in the spatial distribution of QSOs. The presence of dark matter should affect the solar neighborhood and related to the existence of galactic haloes. The contributions are devoted to the search of such local dark matter. Primordial nucleosynthesis provides a very powerful tool to set up quite constraining limitations on the overall baryonic density. Even if on takes into account the inhomogeneities in density possibly induced by the Quark-Hadron transition, this baryonic density should be much lower than the overall density deduced from the dynamical models of Universe or the inflationary theories

  13. Global spatiotemporal distribution of soil respiration modeled using a global database

    Science.gov (United States)

    Hashimoto, S.; Carvalhais, N.; Ito, A.; Migliavacca, M.; Nishina, K.; Reichstein, M.

    2015-07-01

    The flux of carbon dioxide from the soil to the atmosphere (soil respiration) is one of the major fluxes in the global carbon cycle. At present, the accumulated field observation data cover a wide range of geographical locations and climate conditions. However, there are still large uncertainties in the magnitude and spatiotemporal variation of global soil respiration. Using a global soil respiration data set, we developed a climate-driven model of soil respiration by modifying and updating Raich's model, and the global spatiotemporal distribution of soil respiration was examined using this model. The model was applied at a spatial resolution of 0.5°and a monthly time step. Soil respiration was divided into the heterotrophic and autotrophic components of respiration using an empirical model. The estimated mean annual global soil respiration was 91 Pg C yr-1 (between 1965 and 2012; Monte Carlo 95 % confidence interval: 87-95 Pg C yr-1) and increased at the rate of 0.09 Pg C yr-2. The contribution of soil respiration from boreal regions to the total increase in global soil respiration was on the same order of magnitude as that of tropical and temperate regions, despite a lower absolute magnitude of soil respiration in boreal regions. The estimated annual global heterotrophic respiration and global autotrophic respiration were 51 and 40 Pg C yr-1, respectively. The global soil respiration responded to the increase in air temperature at the rate of 3.3 Pg C yr-1 °C-1, and Q10 = 1.4. Our study scaled up observed soil respiration values from field measurements to estimate global soil respiration and provide a data-oriented estimate of global soil respiration. The estimates are based on a semi-empirical model parameterized with over one thousand data points. Our analysis indicates that the climate controls on soil respiration may translate into an increasing trend in global soil respiration and our analysis emphasizes the relevance of the soil carbon flux from soil to

  14. Weak lensing: Dark Matter, Dark Energy and Dark Gravity

    International Nuclear Information System (INIS)

    Heavens, Alan

    2009-01-01

    In this non-specialist review I look at how weak lensing can provide information on the dark sector of the Universe. The review concentrates on what can be learned about Dark Matter, Dark Energy and Dark Gravity, and why. On Dark Matter, results on the confrontation of theoretical profiles with observation are reviewed, and measurements of neutrino masses discussed. On Dark Energy, the interest is whether this could be Einstein's cosmological constant, and prospects for high-precision studies of the equation of state are considered. On Dark Gravity, we consider the exciting prospects for future weak lensing surveys to distinguish General Relativity from extra-dimensional or other gravity theories.

  15. Autophagy Deficiency Compromises Alternative Pathways of Respiration following Energy Deprivation in Arabidopsis thaliana.

    Science.gov (United States)

    Barros, Jessica A S; Cavalcanti, João Henrique F; Medeiros, David B; Nunes-Nesi, Adriano; Avin-Wittenberg, Tamar; Fernie, Alisdair R; Araújo, Wagner L

    2017-09-01

    Under heterotrophic conditions, carbohydrate oxidation inside the mitochondrion is the primary energy source for cellular metabolism. However, during energy-limited conditions, alternative substrates are required to support respiration. Amino acid oxidation in plant cells plays a key role in this by generating electrons that can be transferred to the mitochondrial electron transport chain via the electron transfer flavoprotein/ubiquinone oxidoreductase system. Autophagy, a catabolic mechanism for macromolecule and protein recycling, allows the maintenance of amino acid pools and nutrient remobilization. Although the association between autophagy and alternative respiratory substrates has been suggested, the extent to which autophagy and primary metabolism interact to support plant respiration remains unclear. To investigate the metabolic importance of autophagy during development and under extended darkness, Arabidopsis ( Arabidopsis thaliana ) mutants with disruption of autophagy ( atg mutants) were used. Under normal growth conditions, atg mutants showed lower growth and seed production with no impact on photosynthesis. Following extended darkness, atg mutants were characterized by signatures of early senescence, including decreased chlorophyll content and maximum photochemical efficiency of photosystem II coupled with increases in dark respiration. Transcript levels of genes involved in alternative pathways of respiration and amino acid catabolism were up-regulated in atg mutants. The metabolite profiles of dark-treated leaves revealed an extensive metabolic reprogramming in which increases in amino acid levels were partially compromised in atg mutants. Although an enhanced respiration in atg mutants was observed during extended darkness, autophagy deficiency compromises protein degradation and the generation of amino acids used as alternative substrates to the respiration. © 2017 American Society of Plant Biologists. All Rights Reserved.

  16. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    Full Text Available Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2.s(-1 and clipping (2.06 μmol.m(-2.s(-1 than under grazing (1.65 μmol.m-(2.s(-1 over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP. Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content and biotic (ANPP and BNPP factors regulate soil respiration in the semiarid temperate grassland of northern China.

  17. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Science.gov (United States)

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  18. Fuzzy Control of Tidal volume, Respiration number and Pressure value

    OpenAIRE

    Hasan Guler; Fikret Ata

    2010-01-01

    In this study, control of tidal volume, respiration number and pressure value which are arrived to patient at mechanical ventilator device which is used in intensive care units were performed with fuzzy logic controller. The aim of this system is to reduce workload of aneshesiologist. By calculating tidal volume, respiration number and pressure value, the error Pe(k) between reference pressure value (Pref) and pressure of gas given ill person (Phasta) and error change rate ;#948;Pe(k) were co...

  19. New Spectral Features from Bound Dark Matter

    DEFF Research Database (Denmark)

    Catena, Riccardo; Kouvaris, Chris

    2016-01-01

    We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments...... with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section....

  20. Short-term effects of carbon dioxide on carnation callus cell respiration

    International Nuclear Information System (INIS)

    Palet, A.; Ribas-Carbo, M.; Argiles, J.M.; Azcon-Bieto, J.

    1991-01-01

    The addition of potassium bicarbonate to the electrode cuvette immediately stimulated the rate of dark O 2 uptake of photomixotrophic and heterotrophic carnation (Dianthus caryophyllus L.) callus, of Elodea canadensis (Minchx) leaves, and of other plant tissues. This phenomenon occurred at pH values lower than 7.2 to 7.8, and the stimulation depended on the concentration of gaseous CO 2 in the solution. These stimulatory responses lasted several minutes and then decreased, but additional bicarbonate or gaseous CO 2 again stimulated respiration, suggesting a reversible effect. Carbonic anhydrase in the solution increased the stimulatory effect of potassium bicarbonate. The CO 2 /bicarbonate dependent stimulation of respiration did not occur in animal tissues such as rat diaphragm and isolated hepatocytes, and was inhibited by salicylhydroxamic acid in carnation callus cells and E. canadensis leaves. This suggested that the alternative oxidase was engaged during the stimulation in plant tissues. The cytochrome pathway was severely inhibited by CO 2 /bicarbonate either in the absence or in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydrazone. The activity of cytochrome c oxidase of callus tissue homogenates was also inhibited by CO 2 /bicarbonate. The results suggested that high carbon dioxide levels (mainly free CO 2 ) partially inhibited the cytochrome pathway (apparently at the oxidase level), and this block in electron transport elicited a large transient engagement of the alternative oxidase when present uninhibited

  1. Effects of simulated warming on soil respiration to XiaoPo lake

    Science.gov (United States)

    Zhao, Shuangkai; Chen, Kelong; Wu, Chengyong; Mao, Yahui

    2018-02-01

    The main flux of carbon cycling in terrestrial and atmospheric ecosystems is soil respiration, and soil respiration is one of the main ways of soil carbon output. This is of great significance to explore the dynamic changes of soil respiration rate and its effect on temperature rise, and the correlation between environmental factors and soil respiration. In this study, we used the open soil carbon flux measurement system (LI-8100, LI-COR, NE) in the experimental area of the XiaoPo Lake wetland in the Qinghai Lake Basin, and the Kobresia (Rs) were measured, and the soil respiration was simulated by simulated temperature (OTC) and natural state. The results showed that the temperature of 5 cm soil was 1.37 °C higher than that of the control during the experiment, and the effect of warming was obvious. The respiration rate of soil under warming and natural conditions showed obvious diurnal variation and monthly variation. The effect of warming on soil respiration rate was promoted and the effect of precipitation on soil respiration rate was inhibited. Further studies have shown that the relationship between soil respiration and 5 cm soil temperature under the control and warming treatments can be described by the exponential equation, and the correlation analysis between the two plots shows a very significant exponential relationship (p main influencing factor of soil respiration in this region.

  2. The effect of respiration buffer composition on mitochondrial metabolism and function

    OpenAIRE

    Wollenman, Lucas C.; Vander Ploeg, Matthew R.; Miller, Mackinzie L.; Zhang, Yizhu; Bazil, Jason N.

    2017-01-01

    Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffer...

  3. Thermal Acclimation of Photosynthesis and Respiration Differ Across Mature Conifer Species in a Boreal Forest Peatland

    Science.gov (United States)

    Dusenge, M. E.; Stinziano, J. R.; Warren, J.; Ward, E. J.; Wullschleger, S.; Hanson, P. J.; Way, D.

    2017-12-01

    Boreal forests are often assumed to be temperature-limited, and warming is therefore expected to stimulate their carbon uptake. However, much of our information on the ability of boreal conifers to acclimate photosynthesis and respiration to rising temperatures comes from seedlings. We measured net CO2 assimilation rates (A) and dark respiration (R) at 25 °C (A25 and R25) and at prevailing growth temperatures (Ag and Rg) in mature Picea mariana (spruce) and Larix laricina (tamarack) exposed to ambient, +2.25, +4.5, +6.75 and +9 °C warming treatments in open top chambers in the field at the SPRUCE experiment (MN, USA). In spruce, A25 and Ag were similar across plots in May and June. In August, spruce in warmer treatments had higher A25, an effect that was offset by warmer leaf temperatures in the Ag data. In tamarack, A25 was stimulated by warming in both June and August, an effect that was mainly offset by higher leaf temperatures when Ag was assessed in June, while in August, Ag was still slightly higher in the warmest treatments (+6.75 and +9) compared to the ambient plots. In spruce, R25 was enhanced in warm-grown trees in May, but was similar across treatments in June and August, indicating little acclimation of R. Rg slightly increased with warming treatments across the season in spruce. In contrast, R in tamarack thermally acclimated, as R25 decreased with warming. But while this acclimation generated homeostatic Rg in June, Rg in August was still highest in the warmest treatments. Our work suggests that the capacity for thermal acclimation in both photosynthesis and respiration varies among boreal tree species, which may lead to shifts in the performance of these species as the climate warms.

  4. Interacting agegraphic dark energy

    International Nuclear Information System (INIS)

    Wei, Hao; Cai, Rong-Gen

    2009-01-01

    A new dark energy model, named ''agegraphic dark energy'', has been proposed recently, based on the so-called Karolyhazy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegraphic dark energy model and holographic dark energy model. The similarity and difference between agegraphic dark energy and holographic dark energy are also discussed. (orig.)

  5. Temperature response of soil respiration largely unaltered with experimental warming

    DEFF Research Database (Denmark)

    Carey, Joanna C; Tang, Jianwu; Templer, Pamela H

    2016-01-01

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific...... attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies......, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation...

  6. Global variability in leaf respiration in relation to climate and leaf traits

    Science.gov (United States)

    Atkin, Owen K.

    2015-04-01

    Leaf respiration plays a vital role in regulating ecosystem functioning and the Earth's climate. Because of this, it is imperative that that Earth-system, climate and ecosystem-level models be able to accurately predict variations in rates of leaf respiration. In the field of photosynthesis research, the F/vC/B model has enabled modellers to accurately predict variations in photosynthesis through time and space. By contrast, we lack an equivalent biochemical model to predict variations in leaf respiration. Consequently, we need to rely on phenomenological approaches to model variations in respiration across the Earth's surface. Such approaches require that we develop a thorough understanding of how rates of respiration vary among species and whether global environmental gradients play a role in determining variations in leaf respiration. Dealing with these issues requires that data sets be assembled on rates of leaf respiration in biomes across the Earth's surface. In this talk, I will use a newly-assembled global database on leaf respiration and associated traits (including photosynthesis) to highlight variation in leaf respiration (and the balance between respiration and photosynthesis) across global gradients in growth temperature and aridity.

  7. Mitochondrial Respiration and Oxygen Tension.

    Science.gov (United States)

    Shaw, Daniel S; Meitha, Karlia; Considine, Michael J; Foyer, Christine H

    2017-01-01

    Measurements of respiration and oxygen tension in plant organs allow a precise understanding of mitochondrial capacity and function within the context of cellular oxygen metabolism. Here we describe methods that can be routinely used for the isolation of intact mitochondria, and the determination of respiratory electron transport, together with techniques for in vivo determination of oxygen tension and measurement of respiration by both CO 2 production and O 2 consumption that enables calculation of the respiratory quotient [CO 2 ]/[O 2 ].

  8. Respirable versus inhalable dust sampling

    International Nuclear Information System (INIS)

    Hondros, J.

    1987-01-01

    The ICRP uses a total inhalable dust figure as the basis of calculations on employee lung dose. This paper was written to look at one aspect of the Olympic Dam dust situation, namely, the inhalable versus respirable fraction of the dust cloud. The results of this study will determine whether it is possible to use respirable dust figures, as obtained during routine monitoring to help in the calculations of employee exposure to internal radioactive contaminants

  9. Interpreting, measuring, and modeling soil respiration

    Science.gov (United States)

    Michael G. Ryan; Beverly E. Law

    2005-01-01

    This paper reviews the role of soil respiration in determining ecosystem carbon balance, and the conceptual basis for measuring and modeling soil respiration. We developed it to provide background and context for this special issue on soil respiration and to synthesize the presentations and discussions at the workshop. Soil respiration is the largest component of...

  10. Stimulation of respiration in rat thymocytes induced by ionizing radiation

    International Nuclear Information System (INIS)

    Gudz, T.I.; Pandelova, I.G.; Novgorodov, S.A.

    1994-01-01

    The effect of X irradiation on the respiration of rat thymocytes was studied. An increase in the rate of O 2 uptake was observed 1 h after cells were irradiated with doses of 6-10 Gy. The radiation-induced increase in respiration could be blocked by oligomycin, an inhibitor of mitochondrial ATP synthase, suggesting control by increased cytoplasmic ATP turnover. The stimulation of respiration was not associated with changes in the activity of mitochondrial electron transfer enzymes or permeability of the inner membrane. Several inhibitors of processes which used ATP were screened for their effects on the basal respiration rate and on the radiation response. In irradiated thymocytes, an enhancement of inhibition of respiration by ouabain, La 3+ and cycloheximide was observed. These results indicate that the radiation-induced stimulation of respiration is due to changes in ion homeostasis and protein synthesis. The effect of X irradiation was shown to be independent of the redox status of nonprotein thiols and was not associated with detectable changes in some products of lipid peroxidation. The radiation-induced decrease in activity of superoxide dismutase suggests free radical involvement in deleterious effects of radiation. 43 refs., 2 figs., 3 tabs

  11. Controls on Ecosystem and Root Respiration in an Alaskan Peatland

    Science.gov (United States)

    McConnell, N. A.; McGuire, A. D.; Harden, J. W.; Kane, E. S.; Turetsky, M. R.

    2010-12-01

    Boreal ecosystems cover 14% of the vegetated surface on earth and account for 25-30% of the world’s soil carbon (C), mainly due to large carbon stocks in deep peat and frozen soil layers. While peatlands have served as historical sinks of carbon, global climate change may trigger re-release of C to the atmosphere and may turn these ecosystems into net C sources. Rates of C release from a peatland are determined by regional climate and local biotic and abiotic factors such as vegetation cover, thaw depth, and peat thickness. Soil CO2 fluxes are driven by both autotrophic (plant) respiration and heterotrophic (microbial) respiration. Thus, changes in plant and microbial activity in the soil will impact CO2 emissions from peatlands. In this study, we explored environmental and vegetation controls on ecosystem respiration and root respiration in a variety of wetland sites. The study was conducted at the Alaskan Peatland Experiment (APEX; www.uoguelph.ca/APEX) sites in the Bonanza Creek Experimental Forest located 35 km southwest of Fairbanks Alaska. We measured ecosystem respiration, root respiration, and monitored a suite of environmental variables along a vegetation and soil moisture gradient including a black spruce stand with permafrost, a shrubby site with permafrost, a tussock grass site, and a herbaceous open rich fen. Within the rich fen, we have been conducting water table manipulations including a control, lowered, and raised water table treatment. In each of our sites, we measured total ecosystem respiration using static chambers and root respiration by harvesting roots from the uppermost 20 cm and placing them in a root cuvette to obtain a root flux. Ecosystem respiration (ER) on a μmol/m2/sec basis varied across sites. Water table was a significant predictor of ER at the lowered manipulation site and temperature was a strong predictor at the control site in the rich fen. Water table and temperature were both significant predictors of ER at the raised

  12. Biophysical controls on soil respiration in the dominant patch types of an old-growth, mixed-conifer forest

    Science.gov (United States)

    Siyan Ma; Jiquan Chen; John R. Butnor; Malcolm North; Eugénie S. Euskirchen; Brian Oakley

    2005-01-01

    Little is known about biophysical controls on soil respiration in California's Sierra Nevada old-growth, mixed-conifer forests. Using portable and automated soil respiration sampling units, we measured soil respiration rate (SRR) in three dominant patch types: closed canopy (CC), ceanothus-dominated patches (CECO), and open canopy (OC). SRR varied significantly...

  13. Dark Tourism

    OpenAIRE

    Bali-Hudáková, Lenka

    2008-01-01

    This thesis is focused on the variability of the demand and the development of new trends in the fields of the tourism industry. Special attention is devoted to a new arising trend of the Dark Tourism. This trend has appeared in the end of the 20th century and it has gained the attraction of media, tourists, tourism specialists and other stakeholders. First part of the thesis is concerned with the variety of the tourism industry and the ethic question of the tourism development. The other par...

  14. Respiration and carbon dynamics of free-living and particle-attached bacteria in coastal waters of NE Pacific

    Science.gov (United States)

    Guo, C.; Ke, Y.; Liu, H.

    2016-02-01

    Bacterial respiration (BR) rates are fundamental to understand the role of bacteria in carbon flow in aquatic ecosystem, and therefore it is critical to obtain reliable measurements. Prefiltration- (mostly 1-3μm) and dark-incubation- (mostly 24 h) based direct measurements of oxygen consumption have been the most commonly used method for BR. However, the prefiltration procedure and long incubation time may cause change of the bacterial abundance and structure, leading to inaccurate measurements. In this study, by measuring bacterial abundance, production and respiration of both particle-attached (PA) and free-living (FL) bacteria at two contrasting site in coastal NE Pacific from Nov 2014 to Mar 2015, we found that the 24 h growth rate of FL bacteria in the traditional BR incubations were significantly higher for 30% and 54% than those obtained for FL and total (FL+PA) bacteria in unfiltered incubations respectively, suggesting removal of protist grazers could cause a significant biomass accumulation during 24 h incubation than the in situ condition. This biomass overestimation resulted in 40% (±12%) overestimation of measured FL BR rates compared with the corrected in situ FL BR. Nevertheless, for the corrected in situ total BR, the rates were overestimated by traditional method in three measurements over nine for 6-46%, and were underestimated in the rest six measurements for 7-67%. Interestingly, those underestimations were attributed to the ignorance of PA bacteria due to prefiltration, which had larger cell size than the FL bacteria, accounted for 19% (±16%) in total bacterial abundance, and contributed to 50% (±19%) of total bacterial production. The average bacterial growth efficiency calculated by comparable 24 h integrated bacterial production and respiration was 0.42 (±0.24). Our results confirmed two major flaws in the current BR methodology, i.e., 1) it only measures the respiration of FL bacteria, and 2) the removal of grazers causing dramatic

  15. Studies on photosynthesis and respiration in some marine macroalgae of the Goa coast

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    Primary production and respiration rates were measured in 14 marine macroalgal species from the Goa coast. The highest production rate was observed in Hypnea musciformis and the lowest in Laurencia papillosa. Net production rates in these 14 species...

  16. Dark coupling and gauge invariance

    International Nuclear Information System (INIS)

    Gavela, M.B.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

    2010-01-01

    We study a coupled dark energy-dark matter model in which the energy-momentum exchange is proportional to the Hubble expansion rate. The inclusion of its perturbation is required by gauge invariance. We derive the linear perturbation equations for the gauge invariant energy density contrast and velocity of the coupled fluids, and we determine the initial conditions. The latter turn out to be adiabatic for dark energy, when assuming adiabatic initial conditions for all the standard fluids. We perform a full Monte Carlo Markov Chain likelihood analysis of the model, using WMAP 7-year data

  17. Dark Coupling and Gauge Invariance

    CERN Document Server

    Gavela, M B; Mena, O; Rigolin, S

    2010-01-01

    We study a coupled dark energy-dark matter model in which the energy-momentum exchange is proportional to the Hubble expansion rate. The inclusion of its perturbation is required by gauge invariance. We derive the linear perturbation equations for the gauge invariant energy density contrast and velocity of the coupled fluids, and we determine the initial conditions. The latter turn out to be adiabatic for dark energy, when assuming adiabatic initial conditions for all the standard fluids. We perform a full Monte Carlo Markov Chain likelihood analysis of the model, using WMAP 7-year data.

  18. Superconducting Detectors for Superlight Dark Matter.

    Science.gov (United States)

    Hochberg, Yonit; Zhao, Yue; Zurek, Kathryn M

    2016-01-08

    We propose and study a new class of superconducting detectors that are sensitive to O(meV) electron recoils from dark matter-electron scattering. Such devices could detect dark matter as light as the warm dark-matter limit, m(X)≳1  keV. We compute the rate of dark-matter scattering off of free electrons in a (superconducting) metal, including the relevant Pauli blocking factors. We demonstrate that classes of dark matter consistent with terrestrial and cosmological or astrophysical constraints could be detected by such detectors with a moderate size exposure.

  19. Evaluation of growth and gas exchange rates of two local saudi wheat cultivars grown under heat stress conditions

    International Nuclear Information System (INIS)

    Boutraa, T.; Akhkha, A.; Shoaibi, A.K.

    2015-01-01

    The present study investigated the effects of three temperature regimes, low (20 degree C), moderate (25 degree C) and high (30 degree C), on growth and physiological parameters of two local Saudi wheat (Triticum durum) cultivars, Hab-Ahmar and Algaimi. Plants were grown under controlled environment in growth chambers. After four weeks plants were harvested and the following growth parameters were measured; plant height, number of tillers, leaf area, root length, fresh and dry weight. Physiological traits include chlorophyll content, photosynthesis rates, stomatal conductance, dark respiration and chlorophyll fluorescence parameters; Fo, Fm and Fv/Fm. In cultivar Hab-Ahmar, moderate and high temperatures caused significant decrease in most growth and physiological parameters such as plant height, number of tillers, leaf area, fresh and dry weight, chlorophyll content, photosynthesis rates, stomatal conductance, dark respiration and the maximum quantum yield of photosystem II (Fv/Fm). In contrast, cv. Algaimi was shown to be more thermotolerant to moderate and high temperatures, with the exception of some growth parameters that were decreased. Unlike cultivar Hab-Ahmar, cultivar Algaimi had an increased rate of dark respiration when temperature was high (30 degree C). Stomatal behavior is shown to be positively correlated with the rates of photosynthesis in both cultivars; however, in cultivar Hab-Ahmar such correlation decreased as temperature increased. (author)

  20. Decaying dark matter from dark instantons

    International Nuclear Information System (INIS)

    Carone, Christopher D.; Erlich, Joshua; Primulando, Reinard

    2010-01-01

    We construct an explicit, TeV-scale model of decaying dark matter in which the approximate stability of the dark matter candidate is a consequence of a global symmetry that is broken only by instanton-induced operators generated by a non-Abelian dark gauge group. The dominant dark matter decay channels are to standard model leptons. Annihilation of the dark matter to standard model states occurs primarily through the Higgs portal. We show that the mass and lifetime of the dark matter candidate in this model can be chosen to be consistent with the values favored by fits to data from the PAMELA and Fermi-LAT experiments.

  1. Elucidating PID Degradation Mechanisms and In Situ Dark I-V Monitoring for Modeling Degradation Rate in CdTe Thin-Film Modules

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu; Johnston, Steve

    2016-01-01

    A progression of potential-induced degradation (PID) mechanisms are observed in CdTe modules, including shunting/junction degradation and two different manifestations of series resistance depending on the stress level and water ingress. The dark I-V method for in-situ characterization of Pmax bas...

  2. Tai Chi training reduced coupling between respiration and postural control.

    Science.gov (United States)

    Holmes, Matthew L; Manor, Brad; Hsieh, Wan-hsin; Hu, Kun; Lipsitz, Lewis A; Li, Li

    2016-01-01

    In order to maintain stable upright stance, the postural control system must account for the continuous perturbations to the body's center-of-mass including those caused by spontaneous respiration. Both aging and disease increase "posturo-respiratory synchronization;" which reflects the degree to which respiration affects postural sway fluctuations over time. Tai Chi training emphasizes the coordination of respiration and bodily movements and may therefore optimize the functional interaction between these two systems. The purpose of the project was to examine the effect of Tai Chi training on the interaction between respiration and postural control in older adults. We hypothesized that Tai Chi training would improve the ability of the postural control system to compensate for respiratory perturbations and thus, reduce posturo-respiratory synchronization. Participants were recruited from supportive housing facilities and randomized to a 12-week Tai Chi intervention (n=28; 86 ± 5 yrs) or educational-control program (n=34, 85 ± 6 yrs). Standing postural sway and respiration were simultaneously recorded with a force plate and respiratory belt under eyes-open and eyes-closed conditions. Posturo-respiratory synchronization was determined by quantifying the variation of the phase relationship between the dominant oscillatory mode of respiration and corresponding oscillations within postural sway. Groups were similar in age, gender distribution, height, body mass, and intervention compliance. Neither intervention altered average sway speed, sway magnitude or respiratory rate. As compared to the education-control group, however, Tai Chi training reduced posturo-respiratory synchronization when standing with eyes open or closed (ppostural control or respiration, yet reduced the coupling between respiration and postural control. The beneficial effects of Tai Chi training may therefore stem in part from optimization of this multi-system interaction. Copyright © 2015

  3. Dynamic characteristics of soil respiration in Yellow River Delta wetlands, China

    Science.gov (United States)

    Wang, Xiao; Luo, Xianxiang; Jia, Hongli; Zheng, Hao

    2018-02-01

    The stable soil carbon (C) pool in coastal wetlands, referred to as "blue C", which has been extensively damaged by climate change and soil degradation, is of importance to maintain global C cycle. Therefore, to investigate the dynamic characteristics of soil respiration rate and evaluate C budgets in coastal wetlands are urgently. In this study, the diurnal and seasonal variation of soil respiration rate in the reed wetland land (RL) and the bare wetland land (BL) was measured in situ with the dynamic gas-infrared CO2 method in four seasons, and the factors impacted on the dynamic characteristics of soil respiration were investigated. The results showed that the diurnal variation of soil respiration rate consistently presented a "U" curve pattern in April, July, and September, with the maximum values at 12:00 a.m. and the minimum values at 6:00 a.m. In the same season, the diurnal soil respiration rate in RL was significantly greater than those in BL (P respiration rate was 0.14, 0.42, and 0.39 μmol m-2 s-1 in RL, 0.05, 0.22, 0.13, and 0.01 μmol m-2 s-1 in BL, respectively. Soil surface temperature was the primary factor that influenced soil respiration, which was confirmed by the exponential positive correlation between the soil respiration rate and soil surface temperature in BL and RL (P respiration, confirming by the significantly negative correlation between soil respiration rate and the content of soluble salt. These results will be useful for understanding the mechanisms underlying soil respiration and elevating C sequestration potential in the coastal wetlands.

  4. Plant growth and respiration re-visited: maintenance respiration defined – it is an emergent property of, not a separate process within, the system – and why the respiration : photosynthesis ratio is conservative

    Science.gov (United States)

    Thornley, John H. M.

    2011-01-01

    Background and Aims Plant growth and respiration still has unresolved issues, examined here using a model. The aims of this work are to compare the model's predictions with McCree's observation-based respiration equation which led to the ‘growth respiration/maintenance respiration paradigm’ (GMRP) – this is required to give the model credibility; to clarify the nature of maintenance respiration (MR) using a model which does not represent MR explicitly; and to examine algebraic and numerical predictions for the respiration:photosynthesis ratio. Methods A two-state variable growth model is constructed, with structure and substrate, applicable on plant to ecosystem scales. Four processes are represented: photosynthesis, growth with growth respiration (GR), senescence giving a flux towards litter, and a recycling of some of this flux. There are four significant parameters: growth efficiency, rate constants for substrate utilization and structure senescence, and fraction of structure returned to the substrate pool. Key Results The model can simulate McCree's data on respiration, providing an alternative interpretation to the GMRP. The model's parameters are related to parameters used in this paradigm. MR is defined and calculated in terms of the model's parameters in two ways: first during exponential growth at zero growth rate; and secondly at equilibrium. The approaches concur. The equilibrium respiration:photosynthesis ratio has the value of 0·4, depending only on growth efficiency and recycling fraction. Conclusions McCree's equation is an approximation that the model can describe; it is mistaken to interpret his second coefficient as a maintenance requirement. An MR rate is defined and extracted algebraically from the model. MR as a specific process is not required and may be replaced with an approach from which an MR rate emerges. The model suggests that the respiration:photosynthesis ratio is conservative because it depends on two parameters only whose

  5. Phases of cannibal dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Marco [New High Energy Theory Center, Department of Physics, Rutgers University,136 Frelinghuisen Road, Piscataway, NJ 08854 (United States); Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele [Center for Cosmology and Particle Physics, Department of Physics, New York University,New York, NY 10003 (United States)

    2016-12-13

    A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

  6. Interacting Agegraphic Dark Energy

    OpenAIRE

    Wei, Hao; Cai, Rong-Gen

    2007-01-01

    A new dark energy model, named "agegraphic dark energy", has been proposed recently, based on the so-called K\\'{a}rolyh\\'{a}zy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegrap...

  7. Facepiece leakage and fitting of respirators

    International Nuclear Information System (INIS)

    White, J.M.

    1978-05-01

    The ways in which airborne contaminants can penetrate respirators and the factors which affect the fit of respirators are discussed. The fit of the respirator to the face is shown to be the most critical factor affecting the protection achieved by the user. Qualitative and quantitative fit testing techniques are described and their application to industrial respirator programs is examined. Quantitative measurement of the leakage of a respirator while worn can be used to numerically indicate the protection achieved. These numbers, often referred to as protection factors, are sometimes used as the basis for selecting suitable respirators and this practice is reviewed. (author)

  8. Unification of dark energy and dark matter

    International Nuclear Information System (INIS)

    Takahashi, Fuminobu; Yanagida, T.T.

    2006-01-01

    We propose a scenario in which dark energy and dark matter are described in a unified manner. The ultralight pseudo-Nambu-Goldstone (pNG) boson, A, naturally explains the observed magnitude of dark energy, while the bosonic supersymmetry partner of the pNG boson, B, can be a dominant component of dark matter. The decay of B into a pair of electron and positron may explain the 511 keV γ ray from the Galactic Center

  9. Acclimation of foliar respiration and photosynthesis in response to experimental warming in a temperate steppe in northern China.

    Directory of Open Access Journals (Sweden)

    Yonggang Chi

    Full Text Available BACKGROUND: Thermal acclimation of foliar respiration and photosynthesis is critical for projection of changes in carbon exchange of terrestrial ecosystems under global warming. METHODOLOGY/PRINCIPAL FINDINGS: A field manipulative experiment was conducted to elevate foliar temperature (Tleaf by 2.07°C in a temperate steppe in northern China. Rd/Tleaf curves (responses of dark respiration to Tleaf, An/Tleaf curves (responses of light-saturated net CO2 assimilation rates to Tleaf, responses of biochemical limitations and diffusion limitations in gross CO2 assimilation rates (Ag to Tleaf, and foliar nitrogen (N concentration in Stipa krylovii Roshev. were measured in 2010 (a dry year and 2011 (a wet year. Significant thermal acclimation of Rd to 6-year experimental warming was found. However, An had a limited ability to acclimate to a warmer climate regime. Thermal acclimation of Rd was associated with not only the direct effects of warming, but also the changes in foliar N concentration induced by warming. CONCLUSIONS/SIGNIFICANCE: Warming decreased the temperature sensitivity (Q10 of the response of Rd/Ag ratio to Tleaf. Our findings may have important implications for improving ecosystem models in simulating carbon cycles and advancing understanding on the interactions between climate change and ecosystem functions.

  10. Dark matter that can form dark stars

    International Nuclear Information System (INIS)

    Gondolo, Paolo; Huh, Ji-Haeng; Kim, Hyung Do; Scopel, Stefano

    2010-01-01

    The first stars to form in the Universe may be powered by the annihilation of weakly interacting dark matter particles. These so-called dark stars, if observed, may give us a clue about the nature of dark matter. Here we examine which models for particle dark matter satisfy the conditions for the formation of dark stars. We find that in general models with thermal dark matter lead to the formation of dark stars, with few notable exceptions: heavy neutralinos in the presence of coannihilations, annihilations that are resonant at dark matter freeze-out but not in dark stars, some models of neutrinophilic dark matter annihilating into neutrinos only and lighter than about 50 GeV. In particular, we find that a thermal DM candidate in standard Cosmology always forms a dark star as long as its mass is heavier than ≅ 50 GeV and the thermal average of its annihilation cross section is the same at the decoupling temperature and during the dark star formation, as for instance in the case of an annihilation cross section with a non-vanishing s-wave contribution

  11. Dark Matter Annihilation at the Galactic Center

    Energy Technology Data Exchange (ETDEWEB)

    Linden, Timothy Ryan [Univ. of California, Santa Cruz, CA (United States)

    2013-06-01

    Observations by the WMAP and PLANCK satellites have provided extraordinarily accurate observations on the densities of baryonic matter, dark matter, and dark energy in the universe. These observations indicate that our universe is composed of approximately ve times as much dark matter as baryonic matter. However, e orts to detect a particle responsible for the energy density of dark matter have been unsuccessful. Theoretical models have indicated that a leading candidate for the dark matter is the lightest supersymmetric particle, which may be stable due to a conserved R-parity. This dark matter particle would still be capable of interacting with baryons via weak-force interactions in the early universe, a process which was found to naturally explain the observed relic abundance of dark matter today. These residual annihilations can persist, albeit at a much lower rate, in the present universe, providing a detectable signal from dark matter annihilation events which occur throughout the universe. Simulations calculating the distribution of dark matter in our galaxy almost universally predict the galactic center of the Milky Way Galaxy (GC) to provide the brightest signal from dark matter annihilation due to its relative proximity and large simulated dark matter density. Recent advances in telescope technology have allowed for the rst multiwavelength analysis of the GC, with suitable e ective exposure, angular resolution, and energy resolution in order to detect dark matter particles with properties similar to those predicted by the WIMP miracle. In this work, I describe ongoing e orts which have successfully detected an excess in -ray emission from the region immediately surrounding the GC, which is di cult to describe in terms of standard di use emission predicted in the GC region. While the jury is still out on any dark matter interpretation of this excess, I describe several related observations which may indicate a dark matter origin. Finally, I discuss the

  12. The Dark Matter of Biology.

    Science.gov (United States)

    Ross, Jennifer L

    2016-09-06

    The inside of the cell is full of important, yet invisible species of molecules and proteins that interact weakly but couple together to have huge and important effects in many biological processes. Such "dark matter" inside cells remains mostly hidden, because our tools were developed to investigate strongly interacting species and folded proteins. Example dark-matter species include intrinsically disordered proteins, posttranslational states, ion species, and rare, transient, and weak interactions undetectable by biochemical assays. The dark matter of biology is likely to have multiple, vital roles to regulate signaling, rates of reactions, water structure and viscosity, crowding, and other cellular activities. We need to create new tools to image, detect, and understand these dark-matter species if we are to truly understand fundamental physical principles of biology. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  13. Diel hysteresis between soil respiration and soil temperature in a biological soil crust covered desert ecosystem.

    Science.gov (United States)

    Guan, Chao; Li, Xinrong; Zhang, Peng; Chen, Yongle

    2018-01-01

    Soil respiration induced by biological soil crusts (BSCs) is an important process in the carbon (C) cycle in arid and semi-arid ecosystems, where vascular plants are restricted by the harsh environment, particularly the limited soil moisture. However, the interaction between temperature and soil respiration remains uncertain because of the number of factors that control soil respiration, including temperature and soil moisture, especially in BSC-dominated areas. In this study, the soil respiration in moss-dominated crusts and lichen-dominated crusts was continuously measured using an automated soil respiration system over a one-year period from November 2015 to October 2016 in the Shapotou region of the Tengger Desert, northern China. The results indicated that over daily cycles, the half-hourly soil respiration rates in both types of BSC-covered areas were commonly related to the soil temperature. The observed diel hysteresis between the half-hourly soil respiration rates and soil temperature in the BSC-covered areas was limited by nonlinearity loops with semielliptical shapes, and soil temperature often peaked later than the half-hourly soil respiration rates in the BSC-covered areas. The average lag times between the half-hourly soil respiration rates and soil temperature for both types of BSC-covered areas were two hours over the diel cycles, and they were negatively and linearly related to the volumetric soil water content. Our results highlight the diel hysteresis phenomenon that occurs between soil respiration rates and soil temperatures in BSC-covered areas and the negative response of this phenomenon to soil moisture, which may influence total C budget evaluations. Therefore, the interactive effects of soil temperature and moisture on soil respiration in BSC-covered areas should be considered in global carbon cycle models of desert ecosystems.

  14. Dependence of Soil Respiration on Soil Temperature and Soil Moisture in Successional Forests in Southern China

    Institute of Scientific and Technical Information of China (English)

    Xu-Li Tang; Guo-Yi Zhou; Shu-Guang Liu; De-Qiang Zhang; Shi-Zhong Liu; Jiong Li; Cun-Yu Zhou

    2006-01-01

    The spatial and temporal variations in soil respiration and its relationship with biophysical factors in forests near the Tropic of Cancer remain highly uncertain. To contribute towards an improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured in three successional subtropical forests at the Dinghushan Nature Reserve (DNR) in southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared in successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season (April-September) and with low rates in the cool dry season (October-March). Soil respiration measured at these forests showed a clear increasing trend with the progressive succession. Annual mean (± SD) soil respiration rate in the DNR forests was (9.0±4.6) Mg CO2-C/hm2 per year, ranging from (6.1±3.2) Mg CO2-C/hm2 per year in early successional forests to (10.7±4.9) Mg CO2-C/hm2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation in DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture increased with progressive succession processes. This increase is caused, in part, by abundant respirators in advanced-successional forest, where more soil moisture is needed to maintain their activities.

  15. Dependence of soil respiration on soil temperature and soil moisture in successional forests in Southern China

    Science.gov (United States)

    Tang, X.-L.; Zhou, G.-Y.; Liu, S.-G.; Zhang, D.-Q.; Liu, S.-Z.; Li, Ji; Zhou, C.-Y.

    2006-01-01

    The spatial and temporal variations in soil respiration and its relationship with biophysical factors in forests near the Tropic of Cancer remain highly uncertain. To contribute towards an improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured in three successional subtropical forests at the Dinghushan Nature Reserve (DNR) in southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared in successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season (April-September) and with low rates in the cool dry season (October-March). Soil respiration measured at these forests showed a clear increasing trend with the progressive succession. Annual mean (±SD) soil respiration rate in the DNR forests was (9.0 ± 4.6) Mg CO2-C/hm2per year, ranging from (6.1 ± 3.2) Mg CO2-C/hm2per year in early successional forests to (10.7 ± 4.9) Mg CO2-C/hm2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation in DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture increased with progressive succession processes. This increase is caused, in part, by abundant respirators in advanced-successional forest, where more soil moisture is needed to maintain their activities.

  16. Effective dark energy equation of state in interacting dark energy models

    Energy Technology Data Exchange (ETDEWEB)

    Avelino, P.P., E-mail: ppavelin@fc.up.pt [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Silva, H.M.R. da, E-mail: hilberto.silva@gmail.com [Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

    2012-07-24

    In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

  17. Effective dark energy equation of state in interacting dark energy models

    International Nuclear Information System (INIS)

    Avelino, P.P.; Silva, H.M.R. da

    2012-01-01

    In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

  18. Glycolysis-respiration relationships in a neuroblastoma cell line.

    Science.gov (United States)

    Swerdlow, Russell H; E, Lezi; Aires, Daniel; Lu, Jianghua

    2013-04-01

    Although some reciprocal glycolysis-respiration relationships are well recognized, the relationship between reduced glycolysis flux and mitochondrial respiration has not been critically characterized. We concomitantly measured the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of SH-SY5Y neuroblastoma cells under free and restricted glycolysis flux conditions. Under conditions of fixed energy demand ECAR and OCR values showed a reciprocal relationship. In addition to observing an expected Crabtree effect in which increasing glucose availability raised the ECAR and reduced the OCR, a novel reciprocal relationship was documented in which reducing the ECAR via glucose deprivation or glycolysis inhibition increased the OCR. Substituting galactose for glucose, which reduces net glycolysis ATP yield without blocking glycolysis flux, similarly reduced the ECAR and increased the OCR. We further determined how reduced ECAR conditions affect proteins that associate with energy sensing and energy response pathways. ERK phosphorylation, SIRT1, and HIF1a decreased while AKT, p38, and AMPK phosphorylation increased. These data document a novel intracellular glycolysis-respiration effect in which restricting glycolysis flux increases mitochondrial respiration. Since this effect can be used to manipulate cell bioenergetic infrastructures, this particular glycolysis-respiration effect can practically inform the development of new mitochondrial medicine approaches. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Pore-scale investigation on the response of heterotrophic respiration to moisture conditions in heterogeneous soils

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhifeng; Liu, Chongxuan; Todd-Brown, Katherine E.; Liu, Yuanyuan; Bond-Lamberty, Ben; Bailey, Vanessa L.

    2016-11-15

    The relationship between microbial respiration rate and soil moisture content is an important property for understanding and predicting soil organic carbon degradation, CO2 production and emission, and their subsequent effects on climate change. This paper reports a pore-scale modeling study to investigate the response of heterotrophic respiration to moisture conditions in soils and to evaluate various factors that affect this response. X-ray computed tomography was used to derive soil pore structures, which were then used for pore-scale model investigation. The pore-scale results were then averaged to calculate the effective respiration rates as a function of water content in soils. The calculated effective respiration rate first increases and then decreases with increasing soil water content, showing a maximum respiration rate at water saturation degree of 0.75 that is consistent with field and laboratory observations. The relationship between the respiration rate and moisture content is affected by various factors, including pore-scale organic carbon bioavailability, the rate of oxygen delivery, soil pore structure and physical heterogeneity, soil clay content, and microbial drought resistivity. Simulations also illustrates that a larger fraction of CO2 produced from microbial respiration can be accumulated inside soil cores under higher saturation conditions, implying that CO2 flux measured on the top of soil cores may underestimate or overestimate true soil respiration rates under dynamic moisture conditions. Overall, this study provides mechanistic insights into the soil respiration response to the change in moisture conditions, and reveals a complex relationship between heterotrophic microbial respiration rate and moisture content in soils that is affected by various hydrological, geochemical, and biophysical factors.

  20. General Instructions for Disposable Respirators

    Centers for Disease Control (CDC) Podcasts

    2009-04-09

    This podcast, intended for the general public, demonstrates how to put on and take off disposable respirators that are to be used in areas affected by the influenza outbreak.  Created: 4/9/2009 by CDC, National Institute for Occupational Safety and Health (NIOSH).   Date Released: 4/29/2009.

  1. Use of Facemasks and Respirators

    Centers for Disease Control (CDC) Podcasts

    2007-05-15

    This program demonstrates the differences of facemasks and respirators that are to be used in public settings during an influenza pandemic.  Created: 5/15/2007 by CDC, National Institute for Occupational Safety and Health (NIOSH).   Date Released: 5/25/2007.

  2. Control of mitochondrial respiration

    NARCIS (Netherlands)

    Tager, J. M.; Wanders, R. J.; Groen, A. K.; Kunz, W.; Bohnensack, R.; Küster, U.; Letko, G.; Böhme, G.; Duszynski, J.; Wojtczak, L.

    1983-01-01

    The control theory of Kacser and Burns [in: Rate Control of Biological Processes (Davies, D.D. ed) pp. 65-104, Cambridge University Press, London, 1973] and Heinrich and Rapoport [Eur. J. Biochem. (1974) 42, 97-105] has been used to quantify the amount of control exerted by different steps on

  3. CELL RESPIRATION STUDIES

    Science.gov (United States)

    Daland, Geneva A.; Isaacs, Raphael

    1927-01-01

    1. The oxygen consumption of blood of normal individuals, when the hemoglobin is saturated with oxygen, is practically zero within the limits of experimental error of the microspirometer used. 2. The oxygen consumed in a microspirometer by the blood of patients with chronic myelogenous leucemia with a high white blood cell count, and of one with leucocytosis from sepsis, was proportional to the number of adult polymorphonuclear neutrophils in the blood. 3. No correlation could be made between the rate of oxygen absorption and the total number of white blood cells in the blood, or the total number of immature cells, or the number of red blood cells, or the amount of oxyhemoglobin. 4. The blood of patients with chronic myelogenous leucemia continued to use oxygen in the microspirometer longer than that of normal individuals, and the hemoglobin, in the leucemic bloods, became desaturated even though exposed to air. 5. In blood in which the bulk. of the cells were immature and the mature cells few, the oxygen consumption was lower than in blood in which the mature cells predominated. The rate of oxygen consumption of the immature cells was relatively low as compared to the mature. 6. The slower rate of oxygen absorption by the immature leucocytes in chronic myelogenous leucemia as compared to the mature cells, places them, in accord with Warburg's reports, in the class of the malignant tissues in this respect rather than in the group of young or embryonic cells. PMID:19869329

  4. Video-based respiration monitoring with automatic region of interest detection

    NARCIS (Netherlands)

    Janssen, R.J.M.; Wang, Wenjin; Moço, A.; de Haan, G.

    2016-01-01

    Vital signs monitoring is ubiquitous in clinical environments and emerging in home-based healthcare applications. Still, since current monitoring methods require uncomfortable sensors, respiration rate remains the least measured vital sign. In this paper, we propose a video-based respiration

  5. Soil respiration is not limited by reductions in microbial biomass during long-term soil incubations

    Science.gov (United States)

    Declining rates of soil respiration are reliably observed during long-term laboratory incubations, but the cause is uncertain. We explored different controls on soil respiration during long-term soil incubations. Following a 707 day incubation (30 C) of soils from cultivated and forested plots at Ke...

  6. Soil CO2 concentration does not affect growth or root respiration in bean or citrus

    NARCIS (Netherlands)

    Bouma, T.J.; Nielsen, K.F.; Eissenstat, D.M.; Lynch, J.P.

    1997-01-01

    Contrasting effects of soil CO2 concentration on root respiration rates during short-term CO2 exposure, and on plant growth during long-term CO2 exposure, have been reported, Here we examine the effects of both short-and long-term exposure to soil CO2 on the root respiration of intact plants and on

  7. Penetration of asbestos fibers in respirator filters

    International Nuclear Information System (INIS)

    Cheng, Yung-Sung; Pearson, S.D.; Rohrbacher, K.D.; Yeh, Hsu-Chi.

    1994-01-01

    Currently, the health risks associated with asbestos have restricted its use and created a growing asbestos abatement industry with a need for respirator filters that are effective for worker protection. The main purpose of this project is to determine the influence of fiber size, electrostatic charge, and flow rate on the penetration of asbestos fibers in respirator filter cartridges. The study includes four types of filters each tested at two flow rates: the AO-R57A, a dual cartridge HEPA filter tested at 16 and 42.5 L/min; the MSA-S, a dust and mist filter tested at 16 and 42.5 L/min; the MSA-A power filter tested at 32 and 85 L/min; and the 3M-8710, a low-efficiency disposable face mask filter tested at 32 and 85 L/min. The three types of asbestos fibers used (amosite, crocidolite, and chrysotile) ranged in length from 0.04-0.5 μm and in aspect ratio (ratio of length to diameter) from 3 to 60. The fibers were used in both charged and neutralized forms. The results from amosite fibers are reported here

  8. 78 FR 18535 - Respirator Certification Fees

    Science.gov (United States)

    2013-03-27

    ... facepiece respirators. The North American respiratory protection market generated revenues around $1,830 million in 2007, the most recent data available.\\4\\ A summary of market segmentation, by respirator type... management. Of the U.S. respirator market of products approved by NIOSH, approximately 35 percent of approval...

  9. Dark Tourism in Budapest

    OpenAIRE

    Shen, Cen; Li, Jin

    2011-01-01

    A new trend is developing in the tourism market nowadays – dark tourism. The main purpose of the study was to explore the marketing strategies of dark tourism sites in Budapest based on the theoretical overview of dark tourism and data gathering of quantitative research. The study started with a theoretical overview of dark tourism in Budapest. Then, the authors focused on the case study of House of Terror, one of the most important dark tourism sites in Budapest. Last, the research has ...

  10. Discrete dark matter

    CERN Document Server

    Hirsch, M; Peinado, E; Valle, J W F

    2010-01-01

    We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z2 subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while reactor angle equal to zero gives no CP violation in neutrino oscillations.

  11. Inverted dipole feature in directional detection of exothermic dark matter

    International Nuclear Information System (INIS)

    Bozorgnia, Nassim; Gelmini, Graciela B.; Gondolo, Paolo

    2017-01-01

    Directional dark matter detection attempts to measure the direction of motion of nuclei recoiling after having interacted with dark matter particles in the halo of our Galaxy. Due to Earth's motion with respect to the Galaxy, the dark matter flux is concentrated around a preferential direction. An anisotropy in the recoil direction rate is expected as an unmistakable signature of dark matter. The average nuclear recoil direction is expected to coincide with the average direction of dark matter particles arriving to Earth. Here we point out that for a particular type of dark matter, inelastic exothermic dark matter, the mean recoil direction as well as a secondary feature, a ring of maximum recoil rate around the mean recoil direction, could instead be opposite to the average dark matter arrival direction. Thus, the detection of an average nuclear recoil direction opposite to the usually expected direction would constitute a spectacular experimental confirmation of this type of dark matter.

  12. Effect of nitrogen on the seasonal course of growth and maintenance respiration in stems of Norway spruce trees.

    Science.gov (United States)

    Stockfors, Jan; Linder, Sune

    1998-03-01

    To determine effects of stem nitrogen concentration ([N]) on the seasonal course of respiration, rates of stem respiration of ten control and ten irrigated-fertilized (IL), 30-year-old Norway spruce trees (Picea abies (L.) Karst.), growing in northern Sweden, were measured on seven occasions from June 1993 to April 1994. To explore sources of seasonal variation and mechanisms of fertilization effects on respiration, we separated total respiration into growth and maintenance respiration for both xylem and phloem bark. Stem respiration increased in response to the IL treatment and was positively correlated with growth rate, volume of living cells and stem nitrogen content. However, no significant effect of IL treatment or [N] in the living cells was found for respiration per unit volume of live cells. Total stem respiration during the growing season (June to September) was estimated to be 16.7 and 29.7 mol CO(2) m(-2) for control and IL-treated trees, respectively. Respiration during the growing season accounted for approximately 64% of total annual respiration. Depending on the method, estimated growth respiration varied between 40 and 60% of total respiration during the growing season. Between 75 and 80% of the live cell volume in the stems was in the phloem, and phloem maintenance accounted for about 70% of maintenance respiration. Because most of the living cells were found in the phloem, and the living xylem cells were concentrated in the outer growth rings, we concluded that the best base for expressing rates of stem growth and maintenance respiration in young Norway spruce trees is stem surface area.

  13. Temperature response of soil respiration largely unaltered with experimental warming

    NARCIS (Netherlands)

    Carey, J.C.; Tang, J.; Templer, P.H.; Kroeger, K.D.; Crowther, T.W.; Burton, A.J.; Dukes, J.S.; Emmett, B.; Frey, S.D.; Heskel, M.A.; Jiang, L.; Machmuller, M.B.; Mohan, J.; Panetta, A.M.; Reich, P.B.; Reinsch, S.; Wang, X.; Allison, S.D.; Bamminger, C.; Bridgham, S.; Collins, S.L.; de Dato, G.; Eddy, W.C.; Enquist, B.J.; Estiarte, M.; Harte, J.; Henderson, A.; Johnson, B.R.; Larsen, K.S.; Luo, Y.; Marhan, S.; Melillo, J.M.; Peñuelas, J.; Pfeifer-Meister, L.; Poll, C.; Rastetter, E.; Reinmann, A.B.; Reynolds, L.L.; Schmidt, I.K.; Shaver, G.R.; Strong, A.L.; Suseela, V.; Tietema, A.

    2016-01-01

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific

  14. Hydrological controls on heterotrophic soil respiration across an agricultural landscape

    Science.gov (United States)

    Water availability is an important determinant of variation in soil respiration, but a consistent relationship between soil water and the relative flux rate of carbon dioxide across different soil types remains elusive. Using large undisturbed soil columns (N = 12), we evaluated soil water controls...

  15. Effect of Simvastatin, Coenzyme Q10, Resveratrol, Acetylcysteine and Acetylcarnitine on Mitochondrial Respiration.

    Science.gov (United States)

    Fišar, Z; Hroudová, J; Singh, N; Kopřivová, A; Macečková, D

    2016-01-01

    Some therapeutic and/or adverse effects of drugs may be related to their effects on mitochondrial function. The effects of simvastatin, resveratrol, coenzyme Q10, acetylcysteine, and acetylcarnitine on Complex I-, Complex II-, or Complex IV-linked respiratory rate were determined in isolated brain mitochondria. The protective effects of these biologically active compounds on the calcium-induced decrease of the respiratory rate were also studied. We observed a significant inhibitory effect of simvastatin on mitochondrial respiration (IC50 = 24.0 μM for Complex I-linked respiration, IC50 = 31.3 μM for Complex II-linked respiration, and IC50 = 42.9 μM for Complex IV-linked respiration); the inhibitory effect of resveratrol was found at very high concentrations (IC50 = 162 μM for Complex I-linked respiration, IC50 = 564 μM for Complex II-linked respiration, and IC50 = 1454 μM for Complex IV-linked respiration). Concentrations required for effective simvastatin- or resveratrol-induced inhibition of mitochondrial respiration were found much higher than concentrations achieved under standard dosing of these drugs. Acetylcysteine and acetylcarnitine did not affect the oxygen consumption rate of mitochondria. Coenzyme Q10 induced an increase of Complex I-linked respiration. The increase of free calcium ions induced partial inhibition of the Complex I+II-linked mitochondrial respiration, and all tested drugs counteracted this inhibition. None of the tested drugs showed mitochondrial toxicity (characterized by respiratory rate inhibition) at drug concentrations achieved at therapeutic drug intake. Resveratrol, simvastatin, and acetylcarnitine had the greatest neuroprotective potential (characterized by protective effects against calcium-induced reduction of the respiratory rate).

  16. Action of γ-rays on the respiration and growth of perilla

    International Nuclear Information System (INIS)

    Sergeeva, E.A.

    1976-01-01

    The respiration rate of leaves of different stroyes and the growth rate of the main steam of perilla plants have been studied after irradiation with γ-rays (3 and 6 kR). Three periods have been distinguished in the rate of the processes under study. The growth and respiration were inhibited in the initial post-irradiation period, then their rate increased till it exceeded the control values at the end of the restoration period. During the subsequent third period, the rate of growth and respiration processes decreased reaching the values observed in unirradiated plants. Changes in the radiosensitive process of growth of irradiated plants are suggested to be the cause for changes in the respiration rate

  17. Dark Matter Coannihilation with a Lighter Species.

    Science.gov (United States)

    Berlin, Asher

    2017-09-22

    We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, M_{GUT}∼10^{16}  GeV.

  18. Axion mediated photon to dark photon mixing

    Energy Technology Data Exchange (ETDEWEB)

    Ejlli, Damian [Novosibirsk State University, Department of Physics, Novosibirsk (Russian Federation); Laboratori Nazionali del Gran Sasso, Theory Group, Assergi, L' Aquila (Italy)

    2018-01-15

    The interaction between the dark/mirror sector and the ordinary sector is considered, where the two sectors interact with each other by sharing the same QCD axion field. This feature makes the mixing between ordinary and dark/mirror photons in ordinary and dark electromagnetic fields possible. Perturbative solutions of the equations of motion describing the evolution of fields in ordinary and dark external magnetic fields are found. User-friendly quantities such as transition probability rates and Stokes parameters are derived. Possible astrophysical and cosmological applications of this model are suggested. (orig.)

  19. Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

    DEFF Research Database (Denmark)

    Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine

    2006-01-01

    The soil fauna communities were described for three dominant vegetation types in a high arctic site at Zackenberg, Northeast Greenland. Soil samples were extracted to quantify the densities of mites, collembolans, enchytraeids, diptera larvae, nematodes and protozoa. Rates of microbial respiration...... densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...

  20. Conformal Gravity: Dark Matter and Dark Energy

    Directory of Open Access Journals (Sweden)

    Robert K. Nesbet

    2013-01-01

    Full Text Available This short review examines recent progress in understanding dark matter, dark energy, and galactic halos using theory that departs minimally from standard particle physics and cosmology. Strict conformal symmetry (local Weyl scaling covariance, postulated for all elementary massless fields, retains standard fermion and gauge boson theory but modifies Einstein–Hilbert general relativity and the Higgs scalar field model, with no new physical fields. Subgalactic phenomenology is retained. Without invoking dark matter, conformal gravity and a conformal Higgs model fit empirical data on galactic rotational velocities, galactic halos, and Hubble expansion including dark energy.

  1. Lichens show that fungi can acclimate their respiration to seasonal changes in temperature.

    Science.gov (United States)

    Lange, Otto L; Green, T G Allan

    2005-01-01

    Five species of lichens, the majority members of a soil-crust community ( Cladonia convoluta, Diploschistes muscorum, Fulgensia fulgens, Lecanora muralis, Squamarina lentigera) showed seasonal changes of temperature sensitivity of their dark respiration (DR) to such an extent that several substantially met the definition of full acclimation, i.e. near identical DR under different nocturnal temperature conditions during the course of the year. C. convoluta, for example, had maximal DR at 5 degrees C of -0.42, -1.11 and -0.09 nmol CO(2) g(-1) s(-1) in autumn, winter, and summer, respectively, a tenfold range. However, at the mean night temperatures for the same three seasons, 9.7 degrees C, 4.2 degrees C and 13.6 degrees C, maximal DR were almost identical at -1.11, -0.93, and -1.45 nmol CO(2) g(-1) s(-1). The information was extracted from measurements using automatic cuvettes that continuously recorded a sample lichen's gas exchange every 30 min under near-natural conditions. The longest period (for L. muralis) covered 15 months and 22,000 data sets whilst, for the other species studied, data blocks were available throughout the calendar year. The acclimation of DR means that maximal net carbon fixation rates remain substantially similar throughout the year and are not depressed by increased carbon loss by respiration in warmer seasons. This is especially important for lichens because of their normally high rate of DR compared to net photosynthesis. We suggest that lichens, especially soil-crust species, could be a suitable model for fungi generally, a group of organisms for which little is known about temperature acclimation because of the great difficulty in separating the organism from its growth medium. Fungi, whether saprophytic, symbiotic or parasitic, including soil lichens, are important components of soil ecosystems and contribute much of the respired CO(2) from these systems. Temperature acclimation by fungi would mean that expected increases in carbon

  2. Strategies for dark matter detection

    International Nuclear Information System (INIS)

    Silk, J.

    1988-01-01

    The present status of alternative forms of dark matter, both baryonic and nonbaryonic, is reviewed. Alternative arguments are presented for the predominance of either cold dark matter (CDM) or of baryonic dark matter (BDM). Strategies are described for dark matter detection, both for dark matter that consists of weakly interacting relic particles and for dark matter that consists of dark stellar remnants

  3. Dark matter from decaying topological defects

    International Nuclear Information System (INIS)

    Hindmarsh, Mark; Kirk, Russell; West, Stephen M.

    2014-01-01

    We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or ''top-down'' (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p−4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large ''boost factor'' enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on Gμ for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits

  4. THE DARK DISK OF THE MILKY WAY

    International Nuclear Information System (INIS)

    Purcell, Chris W.; Bullock, James S.; Kaplinghat, Manoj

    2009-01-01

    Massive satellite accretions onto early galactic disks can lead to the deposition of dark matter in disk-like configurations that co-rotate with the galaxy. This phenomenon has potentially dramatic consequences for dark matter detection experiments. We utilize focused, high-resolution simulations of accretion events onto disks designed to be Galaxy analogues, and compare the resultant disks to the morphological and kinematic properties of the Milky Way's thick disk in order to bracket the range of co-rotating accreted dark matter. In agreement with previous results, we find that the Milky Way's merger history must have been unusually quiescent compared to median Λ cold dark matter expectations and, therefore, its dark disk must be relatively small: the fraction of accreted dark disk material near the Sun is about 20% of the host halo density or smaller and the co-rotating dark matter fraction near the Sun, defined as particles moving with a rotational velocity lag less than 50 km s -1 , is enhanced by about 30% or less compared to a standard halo model. Such a dark disk could contribute dominantly to the low energy (of order keV for a dark matter particle with mass 100 GeV) nuclear recoil event rate of direct detection experiments, but it will not change the likelihood of detection significantly. These dark disks provide testable predictions of weakly interacting massive particle dark matter models and should be considered in detailed comparisons to experimental data. Our findings suggest that the dark disk of the Milky Way may provide a detectable signal for indirect detection experiments, contributing up to about 25% of the dark matter self-annihilation signal in the direction of the center of the Galaxy, lending the signal a noticeably oblate morphology.

  5. Temperature and substrate controls on intra-annual variation in ecosystem respiration in two subarctic vegetation types

    DEFF Research Database (Denmark)

    Grogan, Paul; Jonasson, Sven Evert

    2005-01-01

    significantly to ecosystem respiration during most phases of winter and summer in the two vegetation types. Ecosystem respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76...... contributions of bulk soil organic matter and plant-associated carbon pools to ecosystem respiration is critical to predicting the response of arctic ecosystem net carbon balance to climate change. In this study, we determined the variation in ecosystem respiration rates from birch forest understory and heath......-92%) of the intra-annual variation in ecosystem respiration rates from these two common mesic subarctic ecosystems was explained using a first-order exponential equation relating respiration to substrate chemical quality and soil temperature. Removal of plants and their current year's litter significantly reduced...

  6. Cardiac, skeletal, and smooth muscle mitochondrial respiration: are all mitochondria created equal?

    Science.gov (United States)

    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I; Trinity, Joel D; Hyngstrom, John R; Garten, Ryan S; Diakos, Nikolaos A; Ives, Stephen J; Dela, Flemming; Larsen, Steen; Drakos, Stavros; Richardson, Russell S

    2014-08-01

    Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s(-1)·mg(-1), P respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, complex I state 2 normalized for CS activity, an index of nonphosphorylating respiration per mitochondrial content, increased progressively from cardiac to skeletal to smooth muscles, such that the respiratory control ratio, state 3/state 2 respiration, fell progressively from cardiac to skeletal to smooth muscles (5.3 ± 0.7, 3.2 ± 0.4, and 1.6 ± 0.3 pmol·s(-1)·mg(-1), P respiration highlight the existence of intrinsic functional differences between these muscle mitochondria. This likely influences the efficiency of oxidative phosphorylation and could potentially alter ROS production.

  7. Estimate of respiration rate and physicochemical changes of fresh-cut apples stored under different temperatures Estimativa da taxa de respiração e das mudanças físico-químicas de maçãs minimamente processadas e estocadas sob diferentes temperaturas

    Directory of Open Access Journals (Sweden)

    Cristiane Fagundes

    2013-03-01

    Full Text Available In this study, the influence of storage temperature and passive modified packaging (PMP on the respiration rate and physicochemical properties of fresh-cut Gala apples (Malus domestica B. was investigated. The samples were packed in flexible multilayer bags and stored at 2 °C, 5 °C, and 7 °C for eleven days. Respiration rate as a function of CO2 and O2 concentrations was determined using gas chromatography. The inhibition parameters were estimated using a mathematical model based on Michaelis-Menten equation. The following physicochemical properties were evaluated: total soluble solids, pH, titratable acidity, and reducing sugars. At 2 °C, the maximum respiration rate was observed after 150 hours. At 5 °C and 7 °C the maximum respiration rates were observed after 100 and 50 hours of storage, respectively. The inhibition model results obtained showed a clear effect of CO2 on O2 consumption. The soluble solids decreased, although not significantly, during storage at the three temperatures studied. Reducing sugars and titratable acidity decreased during storage and the pH increased. These results indicate that the respiration rate influenced the physicochemical properties.Neste estudo, a influência da temperatura de armazenamento e da embalagem com atmosfera modificada passiva (AMP na taxa respiratória e nas propriedades físico-químicas de maçãs da variedade Gala (Malus domestica, B. minimamente processadas foi investigada. As amostras foram acondicionadas em embalagens flexíveis e armazenados a 2 °C, 5 °C e 7 °C, durante 11 dias. A taxa de respiração foi gerada para diferentes concentrações de O2 e CO2, obtidas por cromatografia gasosa. Os parâmetros de inibição foram estimados por um modelo matemático baseado na equação de Michaelis-Menten. Foram avaliadas as seguintes propriedades físico-químicas: sólidos solúveis totais, pH, acidez titulável e açúcares redutores. A 2 °C, a taxa de respiração máxima foi

  8. Lymphocyte respiration in children with Trisomy 21

    Directory of Open Access Journals (Sweden)

    Aburawi Elhadi H

    2012-12-01

    Full Text Available Abstract Background This study measured lymphocyte mitochondrial O2 consumption (cellular respiration in children with trisomy 21. Methods Peripheral blood mononuclear cells were isolated from whole blood of trisomy 21 and control children and these cells were immediately used to measure cellular respiration rate. [O2] was determined as a function of time from the phosphorescence decay rates (1/τ of Pd (II-meso-tetra-(4-sulfonatophenyl-tetrabenzoporphyrin. In sealed vials containing lymphocytes and glucose as a respiratory substrate, [O2] declined linearly with time, confirming the zero-order kinetics of O2 conversion to H2O by cytochrome oxidase. The rate of respiration (k, in μM O2 min-1, thus, was the negative of the slope of [O2] vs. time. Cyanide inhibited O2 consumption, confirming that oxidation occurred in the mitochondrial respiratory chain. Results For control children (age = 8.8 ± 5.6 years, n = 26, the mean (± SD value of kc (in μM O2 per min per 107 cells was 1.36 ± 0.79 (coefficient of variation, Cv = 58%; median = 1.17; range = 0.60 to 3.12; -2SD = 0.61. For children with trisomy 21 (age = 7.2 ± 4.6 years, n = 26, the values of kc were 0.82 ± 0.62 (Cv = 76%; median = 0.60; range = 0.20 to 2.80, pp6.1 mU/L. Fourteen of 26 (54% children with trisomy 21 had kc values of 0.20 to 0.60 (i.e., kc positively correlated with body-mass index (BMI, R >0.302, serum creatinine (R >0.507, blood urea nitrogen (BUN, R >0.535 and albumin (R >0.446. Conclusions Children with trisomy 21 in this study have reduced lymphocyte bioenergetics. The clinical importance of this finding requires further studies.

  9. Impeded Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Joachim; Liu, Jia [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Slatyer, Tracy R. [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Wang, Xiao-Ping [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics,Johannes Gutenberg University,Staudingerweg 7, 55099 Mainz (Germany); Xue, Wei [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

    2016-12-12

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  10. Impeded Dark Matter

    International Nuclear Information System (INIS)

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider dark matter models in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. To emphasize this modification, we dub our scenario “Impeded Dark Matter”. We demonstrate that Impeded Dark Matter can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppressed by the small mass splitting, which helps light dark matter to survive increasingly stringent constraints from indirect searches. As specific realizations for Impeded Dark Matter, we introduce a model of vector dark matter from a hidden SU(2) sector, and a composite dark matter scenario based on a QCD-like dark sector.

  11. DarkSide search for dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T.; Alton, D.; Arisaka, K.; Back, H. O.; Beltrame, P.; Benziger, J.; Bonfini, G.; Brigatti, A.; Brodsky, J.; Bussino, S.; Cadonati, L.; Calaprice, F.; Candela, A.; Cao, H.; Cavalcante, P.; Chepurnov, A.; Chidzik, S.; Cocco, A. G.; Condon, C.; D' Angelo, D.; Davini, S.; Vincenzi, M. De; Haas, E. De; Derbin, A.; Pietro, G. Di; Dratchnev, I.; Durben, D.; Empl, A.; Etenko, A.; Fan, A.; Fiorillo, G.; Franco, D.; Fomenko, K.; Forster, G.; Gabriele, F.; Galbiati, C.; Gazzana, S.; Ghiano, C.; Goretti, A.; Grandi, L.; Gromov, M.; Guan, M.; Guo, C.; Guray, G.; Hungerford, E. V.; Ianni, Al; Ianni, An; Joliet, C.; Kayunov, A.; Keeter, K.; Kendziora, C.; Kidner, S.; Klemmer, R.; Kobychev, V.; Koh, G.; Komor, M.; Korablev, D.; Korga, G.; Li, P.; Loer, B.; Lombardi, P.; Love, C.; Ludhova, L.; Luitz, S.; Lukyanchenko, L.; Lund, A.; Lung, K.; Ma, Y.; Machulin, I.; Mari, S.; Maricic, J.; Martoff, C. J.; Meregaglia, A.; Meroni, E.; Meyers, P.; Mohayai, T.; Montanari, D.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B.; Muratova, V.; Nelson, A.; Nemtzow, A.; Nurakhov, N.; Orsini, M.; Ortica, F.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Parsells, R.; Pelliccia, N.; Perasso, L.; Perasso, S.; Perfetto, F.; Pinsky, L.; Pocar, A.; Pordes, S.; Randle, K.; Ranucci, G.; Razeto, A.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Saggese, P.; Saldanha, R.; Salvo, C.; Sands, W.; Seigar, M.; Semenov, D.; Shields, E.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Sukhotin, S.; Suvarov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Thompson, J.; Tonazzo, A.; Unzhakov, E.; Vogelaar, R. B.; Wang, H.; Westerdale, S.; Wojcik, M.; Wright, A.; Xu, J.; Yang, C.; Zavatarelli, S.; Zehfus, M.; Zhong, W.; Zuzel, G.

    2013-11-22

    The DarkSide staged program utilizes a two-phase time projection chamber (TPC) with liquid argon as the target material for the scattering of dark matter particles. Efficient background reduction is achieved using low radioactivity underground argon as well as several experimental handles such as pulse shape, ratio of ionization over scintillation signal, 3D event reconstruction, and active neutron and muon vetos. The DarkSide-10 prototype detector has proven high scintillation light yield, which is a particularly important parameter as it sets the energy threshold for the pulse shape discrimination technique. The DarkSide-50 detector system, currently in commissioning phase at the Gran Sasso Underground Laboratory, will reach a sensitivity to dark matter spin-independent scattering cross section of 10-45 cm2 within 3 years of operation.

  12. Very heavy dark Skyrmions

    International Nuclear Information System (INIS)

    Dick, Rainer

    2017-01-01

    A dark sector with a solitonic component provides a means to circumvent the problem of generically low annihilation cross sections of very heavy dark matter particles. At the same time, enhanced annihilation cross sections are necessary for indirect detection of very heavy dark matter components beyond 100 TeV. Non-thermally produced dark matter in this mass range could therefore contribute to the cosmic γ-ray and neutrino flux above 100 TeV, and massive Skyrmions provide an interesting framework for the discussion of these scenarios. Therefore a Higgs portal and a neutrino portal for very heavy Skyrmion dark matter are discussed. The Higgs portal model demonstrates a dark mediator bottleneck, where limitations on particle annihilation cross sections will prevent a signal from the potentially large soliton annihilation cross sections. This problem can be avoided in models where the dark mediator decays. This is illustrated by the neutrino portal for Skyrmion dark matter. (orig.)

  13. Collapsed Dark Matter Structures.

    Science.gov (United States)

    Buckley, Matthew R; DiFranzo, Anthony

    2018-02-02

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  14. Collapsed Dark Matter Structures

    Science.gov (United States)

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-02-01

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  15. Baryonic Dark Matter

    OpenAIRE

    Silk, Joseph

    1994-01-01

    In the first two of these lectures, I present the evidence for baryonic dark matter and describe possible forms that it may take. The final lecture discusses formation of baryonic dark matter, and sets the cosmological context.

  16. Dark matter detectors

    International Nuclear Information System (INIS)

    Forster, G.

    1995-01-01

    A fundamental question of astrophysics and cosmology is the nature of dark matter. Astrophysical observations show clearly the existence of some kind of dark matter, though they cannot yet reveal its nature. Dark matter can consist of baryonic particles, or of other (known or unknown) elementary particles. Baryonic dark matter probably exists in the form of dust, gas, or small stars. Other elementary particles constituting the dark matter can possibly be measured in terrestrial experiments. Possibilities for dark matter particles are neutrinos, axions and weakly interacting massive particles (WIMPs). While a direct detection of relic neutrinos seems at the moment impossible, there are experiments looking for baryonic dark matter in the form of Massive Compact Halo Objects, and for particle dark matter in the form of axions and WIMPS. (orig.)

  17. Very heavy dark Skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Dick, Rainer [University of Saskatchewan, Department of Physics and Engineering Physics, Saskatoon, SK (Canada)

    2017-12-15

    A dark sector with a solitonic component provides a means to circumvent the problem of generically low annihilation cross sections of very heavy dark matter particles. At the same time, enhanced annihilation cross sections are necessary for indirect detection of very heavy dark matter components beyond 100 TeV. Non-thermally produced dark matter in this mass range could therefore contribute to the cosmic γ-ray and neutrino flux above 100 TeV, and massive Skyrmions provide an interesting framework for the discussion of these scenarios. Therefore a Higgs portal and a neutrino portal for very heavy Skyrmion dark matter are discussed. The Higgs portal model demonstrates a dark mediator bottleneck, where limitations on particle annihilation cross sections will prevent a signal from the potentially large soliton annihilation cross sections. This problem can be avoided in models where the dark mediator decays. This is illustrated by the neutrino portal for Skyrmion dark matter. (orig.)

  18. The dark side of cosmology: dark matter and dark energy.

    Science.gov (United States)

    Spergel, David N

    2015-03-06

    A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of "dark matter," a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of "dark energy," energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales. Copyright © 2015, American Association for the Advancement of Science.

  19. Dark Sky Education | CTIO

    Science.gov (United States)

    Calendar Activities NOAO-S EPO Programs CADIAS Astro Chile Hugo E. Schwarz Telescope Dark Sky Education ‹› You are here CTIO Home » Outreach » NOAO-S EPO Programs » Dark Sky Education Dark Sky Education Dark Sky Education (in progress) Is an EPO Program. It runs Globe at Night, an annual program to

  20. Dark Matter Effective Theory

    DEFF Research Database (Denmark)

    Del Nobile, Eugenio; Sannino, Francesco

    2012-01-01

    We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff...... scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties....

  1. Copepod swimming behavior, respiration, and expression of stress-related genes in response to high stocking densities

    DEFF Research Database (Denmark)

    Nilsson, Birgitte; Jakobsen, Hans H.; Stief, Peter

    2017-01-01

    ,000 ind. L−1. Three biological/physiological end-points were studied: swimming behavior, respiration rate and expression level of stress-related genes. None of the elevated densities caused any significant change in swimming behavior, respiration rate or gene expression level. This study suggests...

  2. Photosynthesis and respiration in the needles of Pinus sibirica and Pinus pumila and their putative hybrids

    Directory of Open Access Journals (Sweden)

    A.P. Zotikova

    2013-12-01

    Full Text Available A putative interspecific hybridization in Pinaceae family was investigated. Very rarely the physiological methods were involved in hybridization processes that occurs in the hybrid zones. It is well known that in most gymnosperms, the plastid genome is inherited from the paternal component while the mitochondrion is inherited from the maternal one. Therefore functioning pattern of organelles in the hybrid plant can suggest parent, from which they were inherited. The aim of this study was to indirectly establish the inheritance energy-transducing organelles (mitochondria, chloroplast according to their functioning. Current year needles from Siberian Stone Pine (Pinus sibirica Du Tour and Japanese Stone Pine (Pinus pumila (Pall. Regel as parent species and their putative hybrids were collected from Baikal Region. The photosynthesis rate was determined by using the spectrophotometer. The study of emission CO2 under dark respiration of needle was conducted with laser optical-acoustic gasanalyzer. The quantity was measured at 1, 2 and 3 hour after experiment start. The rate of the photoreduction ferricyanide potassium was characterized by the primary photochemical processes activity at the level of photosystem II. Comparison of pure species was shown that Japanese Stone Pine had higher functional activity of chloroplast as compared with SiberianStone Pine in spite of the fact that they are growing in similar environment conditions. Two of three analyzed hybrids had decreasedactivity of their chloroplasts. Unfortunately, in this case we can't conclude if the chloroplasts were inherited from Siberian Stone Pine orfrom Japanese Stone Pine. Chloroplast activity of the third hybrid was approximately similar to that of Japanese Stone Pine suggesting thatits chloroplasts were inherited from this parent. Consequently, the Siberian Stone Pine and the Japanese Stone Pine were maternal and paternal, respectively parents of

  3. Effects of respirator use on worker performance

    Energy Technology Data Exchange (ETDEWEB)

    Cardarelli, R. [Yankee Atomic Electric Co., Bolton, MA (United States)

    1995-03-01

    In 1993, EPRI funded Yankee Atomic Electric Company to examine the effects of respirator use on worker efficiency. Phase I of Yankee`s effort was to develop a study design to determine respirator effects. Given success in Phase I, a larger population will be tested to determine if a stasitically significant respirator effect on performance can be measured. This paper summarizes the 1993 EPRI/Yankee Respirator Effects of Pilot Study, and describes the study design for the 1994 EPRI/Yankee Respirator Study to be conducted at the Oyster Creek Nuclear Power Plant. Also described is a summary of respirator effect studies that have been conducted during the last ten (10) years.

  4. Nonthermal Supermassive Dark Matter

    Science.gov (United States)

    Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

    1999-01-01

    We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may he elementary particles of mass much greater than the weak scale. Searches for dark matter should ma be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

  5. Nonthermal Supermassive Dark Matter

    International Nuclear Information System (INIS)

    Chung, D.J.; Chung, D.J.; Kolb, E.W.; Kolb, E.W.; Riotto, A.

    1998-01-01

    We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well. copyright 1998 The American Physical Society

  6. Nonthermal Supermassive Dark Matter

    OpenAIRE

    Chung, Daniel J. H.; Kolb, Edward W.; Riotto, Antonio

    1998-01-01

    We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting particles with mass of the order of the weak scale, but should extend into the supermassive range as well.

  7. Dark Mass Creation During EWPT Via Dark Energy Interaction

    OpenAIRE

    Kisslinger, Leonard S.; Casper, Steven

    2013-01-01

    We add Dark Matter Dark Energy terms with a quintessence field interacting with a Dark Matter field to a MSSM EW Lagrangian previously used to calculate the magnetic field created during the EWPT. From the expectation value of the quintessence field we estimate the Dark Matter mass for parameters used in previous work on Dark Matter-Dark Energy interactions.

  8. The fate of Nissl-stained dark neurons following traumatic brain injury in rats: difference between neocortex and hippocampus regarding survival rate.

    Science.gov (United States)

    Ooigawa, Hidetoshi; Nawashiro, Hiroshi; Fukui, Shinji; Otani, Naoki; Osumi, Atsushi; Toyooka, Terushige; Shima, Katsuji

    2006-10-01

    We studied the fate of Nissl-stained dark neurons (N-DNs) following traumatic brain injury (TBI). N-DNs were investigated in the cerebral neocortex and the hippocampus using a rat lateral fluid percussion injury model. Nissl stain, acid fuchsin stain and immunohistochemistry with phosphorylated extracellular signal-regulated protein kinase (pERK) antibody were used in order to assess posttraumatic neurons. In the neocortex, the number of dead neurons at 24 h postinjury was significantly less than that of the observed N-DNs in the earlier phase. Only a few N-DNs increased their pERK immunoreactivity. On the other hand, in the hippocampus the number of dead neurons was approximately the same number as that of the N-DNs, and most N-DNs showed an increased pERK immunoreactivity. These data suggest that not all N-DNs inevitably die especially in the neocortex after TBI. The fate of N-DNs is thus considered to differ depending on brain subfields.

  9. Respirators: Supervisors Self-Study #43442

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-20

    This course, Respirators: Supervisors Self-Study (#43442), addresses training requirements for supervisors of respirator wearers as specified by the American National Standard Institute (ANSI) Standard for Respiratory Protection, ANSI Z88.2, and as incorporated by reference in the Department of Energy (DOE) Worker Health and Safety Rule, 10 Code of Federal Regulations (CFR) 851. This course also presents the responsibilities of supervisors of respirator wearers at Los Alamos National Laboratory (LANL).

  10. Underwater photosynthesis and respiration in leaves of submerged wetland plants: gas films improve CO2 and O2 exchange

    DEFF Research Database (Denmark)

    Colmer, Timothy David; Pedersen, Ole

    2007-01-01

    (N) was enhanced up to sixfold. Gas films on submerged leaves enable continued gas exchange via stomata and thus bypassing of cuticle resistance, enhancing exchange of O(2) and CO(2) with the surrounding water, and therefore underwater P(N) and respiration.......Many wetland plants have gas films on submerged leaf surfaces. We tested the hypotheses that leaf gas films enhance CO(2) uptake for net photosynthesis (P(N)) during light periods, and enhance O(2) uptake for respiration during dark periods. Leaves of four wetland species that form gas films......, and two species that do not, were used. Gas films were also experimentally removed by brushing with 0.05% (v/v) Triton X. Net O(2) production in light, or O(2) consumption in darkness, was measured at various CO(2) and O(2) concentrations. When gas films were removed, O(2) uptake in darkness was already...

  11. Soil respiration fluxes in a temperate mixed forest: seasonality and temperature sensitivities differ among microbial and root-rhizosphere respiration.

    Science.gov (United States)

    Ruehr, Nadine K; Buchmann, Nina

    2010-02-01

    Although soil respiration, a major CO(2) flux in terrestrial ecosystems, is known to be highly variable with time, the response of its component fluxes to temperature and phenology is less clear. Therefore, we partitioned soil respiration (SR) into microbial (MR) and root-rhizosphere respiration (RR) using small root exclusion treatments in a mixed mountain forest in Switzerland. In addition, fine root respiration (FRR) was determined with measurements of excised roots. RR and FRR were strongly related to each other (R(2) = 0.92, n = 7), with RR contributing about 46% and FRR about 32% to total SR. RR rates increased more strongly with temperature (Q(10) = 3.2) than MR rates (Q(10) = 2.3). Since the contribution of RR to SR was found to be higher during growing (50%) than during dormant periods (40%), we separated the 2-year data set into phenophases. During the growing period of 2007, the temperature sensitivity of RR (Q(10) = 2.5, R(2) = 0.62) was similar to that of MR (Q(10) = 2.2, R(2) = 0.57). However, during the dormant period of 2006/2007, RR was not related to soil temperature (R(2) = 0.44, n.s.), in contrast to MR (Q(10) = 7.2; R(2) = 0.92). To better understand the influence of plant activity on root respiration, we related RR and FRR rates to photosynthetic active radiation (both R(2) = 0.67, n = 7, P = 0.025), suggesting increased root respiration rates during times with high photosynthesis. During foliage green-up in spring 2008, i.e., from bud break to full leaf expansion, RR increased by a factor of 5, while soil temperature increased only by about 5 degrees C, leading to an extraordinary high Q(10) of 10.6; meanwhile, the contribution of RR to SR increased from 29 to 47%. This clearly shows that root respiration and its apparent temperature sensitivity highly depend on plant phenology and thus on canopy assimilation and carbon allocation belowground.

  12. [Soil respiration dynamics and its controlling factors of typical vegetation communities on meadow steppes in the western Songnen Plain].

    Science.gov (United States)

    Wang, Ming; Liu, Xing-Tu; Li, Xiu-Jun; Zhang, Ji-Tao; Wang, Guo-Dong; Lu, Xin-Rui; Li, Xiao-Yu

    2014-01-01

    In order to accurately explore the soil respiration dynamics and its controlling factors of typical vegetation types in the western Songnen Plain, soil respiration rates of Chloris virgata, Puccinellia distans, Phragmites australis and Leymus chinensis communities were measured. The results showed that the diurnal curves of soil respiration rates of the four vegetation communities had simple peak values, which appeared at 11:00-15:00, and the valley values occurred at 21:00-1:00 or 3:00-5:00. The seasonal dynamic patterns of their soil respiration rates were similar, with the maximum (3.21-4.84 micromol CO2 x m(-2) x s(-1)) occurring in July and August and the minimum (0.46-1.51 micromol CO2 x m(-2) x s(-1)) in October. The soil respiration rates of the four vegetation communities had significant exponential correlations with ambient air temperature and soil temperature. Soil moisture, however, only played an important role in affecting the soil respiration rate of C. virgata community while air humidity near the soil surface was significantly correlated with the soil respiration rates of P. australis and L. chinensis communities. The soil salt contents seriously constrained the CO2 dioxide emission, and the soil pH, electrical conductivity (EC), exchangeable sodium percentage (ESP) could explain 87%-91% spatial variations of the soil respiration rate.

  13. Interactions between dark energy and dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Marco

    2009-03-20

    We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with {lambda}{sub CDM}. Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the {lambda}{sub CDM} model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter

  14. Interactions between dark energy and dark matter

    International Nuclear Information System (INIS)

    Baldi, Marco

    2009-01-01

    We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with Λ CDM . Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the Λ CDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios

  15. Effects of environmental factors and soil properties on topographic variations of soil respiration

    OpenAIRE

    Tamai, K.

    2010-01-01

    Soil respiration rates were measured along different parts of a slope in (a) an evergreen forest with common brown forest soil and (b) a deciduous forest with immature soil. The effects of soil temperature, soil moisture and soil properties were estimated individually, and the magnitudes of these effects in the deciduous and evergreen forests were compared. In the evergreen forest with common brown forest soil, soil properties had the greatest effect on soil respiration rates, followed by soi...

  16. Dark Matter Caustics

    International Nuclear Information System (INIS)

    Natarajan, Aravind

    2010-01-01

    The continuous infall of dark matter with low velocity dispersion in galactic halos leads to the formation of high density structures called caustics. Dark matter caustics are of two kinds : outer and inner. Outer caustics are thin spherical shells surrounding galaxies while inner caustics have a more complicated structure that depends on the dark matter angular momentum distribution. The presence of a dark matter caustic in the plane of the galaxy modifies the gas density in its neighborhood which may lead to observable effects. Caustics are also relevant to direct and indirect dark matter searches.

  17. Dark Matter Searches

    International Nuclear Information System (INIS)

    Moriyama, Shigetaka

    2008-01-01

    Recent cosmological as well as historical observations of rotational curves of galaxies strongly suggest the existence of dark matter. It is also widely believed that dark matter consists of unknown elementary particles. However, astrophysical observations based on gravitational effects alone do not provide sufficient information on the properties of dark matter. In this study, the status of dark matter searches is investigated by observing high-energy neutrinos from the sun and the earth and by observing nuclear recoils in laboratory targets. The successful detection of dark matter by these methods facilitates systematic studies of its properties. Finally, the XMASS experiment, which is due to start at the Kamioka Observatory, is introduced

  18. Hunting the dark Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Michael; Grohsjean, Alexander; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwanenberger, Christian [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Penning, Bjoern [Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.

    2017-05-15

    We discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. We present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.

  19. Hunting the dark Higgs

    International Nuclear Information System (INIS)

    Duerr, Michael; Grohsjean, Alexander; Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwanenberger, Christian; Penning, Bjoern

    2017-05-01

    We discuss a novel signature of dark matter production at the LHC resulting from the emission of an additional Higgs boson in the dark sector. The presence of such a dark Higgs boson is motivated simultaneously by the need to generate the masses of the particles in the dark sector and the possibility to relax constraints from the dark matter relic abundance by opening up a new annihilation channel. If the dark Higgs boson decays into Standard Model states via a small mixing with the Standard Model Higgs boson, one obtains characteristic large-radius jets in association with missing transverse momentum that can be used to efficiently discriminate signal from backgrounds. We present the sensitivities achievable in LHC searches for dark Higgs bosons with already collected data and demonstrate that such searches can probe large regions of parameter space that are inaccessible to conventional mono-jet or di-jet searches.

  20. EDITORIAL: Focus on Dark Matter and Particle Physics

    Science.gov (United States)

    Aprile, Elena; Profumo, Stefano

    2009-10-01

    Doetinchem, H Gast, T Kirn and S Schael Axion searches with helioscopes and astrophysical signatures for axion(-like) particles K Zioutas, M Tsagri, Y Semertzidis, T Papaevangelou, T Dafni and V Anastassopoulos The indirect search for dark matter with IceCube Francis Halzen and Dan Hooper DIRECT DARK MATTER SEARCHES:EXPERIMENTS Gaseous dark matter detectors G Sciolla and C J Martoff Search for dark matter with CRESST Rafael F Lang and Wolfgang Seidel DIRECT AND INDIRECT PARTICLE DARK MATTER SEARCHES:THEORY Dark matter annihilation around intermediate mass black holes: an update Gianfranco Bertone, Mattia Fornasa, Marco Taoso and Andrew R Zentner Update on the direct detection of dark matter in MSSM models with non-universal Higgs masses John Ellis, Keith A Olive and Pearl Sandick Dark stars: a new study of the first stars in the Universe Katherine Freese, Peter Bodenheimer, Paolo Gondolo and Douglas Spolyar Determining the mass of dark matter particles with direct detection experiments Chung-Lin Shan The detection of subsolar mass dark matter halos Savvas M Koushiappas Neutrino coherent scattering rates at direct dark matter detectors Louis E Strigari Gamma rays from dark matter annihilation in the central region of the Galaxy Pasquale Dario Serpico and Dan Hooper DARK MATTER MODELS The dark matter interpretation of the 511 keV line Céline Boehm Axions as dark matter particles Leanne D Duffy and Karl van Bibber Sterile neutrinos Alexander Kusenko Dark matter candidates Lars Bergström Minimal dark matter: model and results Marco Cirelli and Alessandro Strumia Shedding light on the dark sector with direct WIMP production Partha Konar, Kyoungchul Kong, Konstantin T Matchev and Maxim Perelstein Axinos as dark matter particles Laura Covi and Jihn E Kim

  1. Global convergence in leaf respiration from estimates of thermal acclimation across time and space.

    Science.gov (United States)

    Vanderwel, Mark C; Slot, Martijn; Lichstein, Jeremy W; Reich, Peter B; Kattge, Jens; Atkin, Owen K; Bloomfield, Keith J; Tjoelker, Mark G; Kitajima, Kaoru

    2015-09-01

    Recent compilations of experimental and observational data have documented global temperature-dependent patterns of variation in leaf dark respiration (R), but it remains unclear whether local adjustments in respiration over time (through thermal acclimation) are consistent with the patterns in R found across geographical temperature gradients. We integrated results from two global empirical syntheses into a simple temperature-dependent respiration framework to compare the measured effects of respiration acclimation-over-time and variation-across-space to one another, and to a null model in which acclimation is ignored. Using these models, we projected the influence of thermal acclimation on: seasonal variation in R; spatial variation in mean annual R across a global temperature gradient; and future increases in R under climate change. The measured strength of acclimation-over-time produces differences in annual R across spatial temperature gradients that agree well with global variation-across-space. Our models further project that acclimation effects could potentially halve increases in R (compared with the null model) as the climate warms over the 21st Century. Convergence in global temperature-dependent patterns of R indicates that physiological adjustments arising from thermal acclimation are capable of explaining observed variation in leaf respiration at ambient growth temperatures across the globe. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  2. Phenomenological introduction to direct dark matter detection

    International Nuclear Information System (INIS)

    Gondolo, P.

    1996-01-01

    The dark matter of our galactic halo may be constituted by elementary particles that interact weakly with with ordinary matter (WIMPs). In spite of the very low counting rates expected for these dark matter particle to scatter off nuclei in a laboratory detector, such direct WIMP searches are possible and are experimentally carried out at present. An introduction to the theoretical ingredients entering the counting rates predictions, together with a short discussion of the major theoretical uncertainties, is here presented. (author)

  3. [Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

    Science.gov (United States)

    Chen, Shu-tao; Sang, Lin; Zhang, Xu; Hu, Zheng-hua

    2016-02-15

    In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured. Urease, invertase, and catalase activities for different treatments were measured at the elongation, booting, and anthesis stages. The results showed that soil respiration in different treatments had similar seasonal variation patterns. Seasonal mean soil respiration rates for the CK, warming, straw application, and warming and straw application treatments were 1.46, 1.96, 1.92, and 2.45 micromol x (m2 x s)(-1), respectively. ANOVA indicated that both warming and straw applications significantly (P soil respiration compared to the control treatment. The relationship between soil respiration and soil temperature in different treatments fitted with the exponential regression function. The exponential regression functions explained 34.3%, 28.1%, 24.6%, and 32.0% variations of soil respiration for CK, warming, straw application, and warming and straw application treatments, respectively. Warming and straw applications significantly (P soil respiration and urease activity fitted with a linear regression function, with the P value of 0.061. The relationship between soil respiration and invertase (P = 0.013), and between soil respiration and catalase activity (P = 0.002) fitted well with linear regression functions.

  4. Did LIGO Detect Dark Matter?

    Science.gov (United States)

    Bird, Simeon; Cholis, Ilias; Muñoz, Julian B; Ali-Haïmoud, Yacine; Kamionkowski, Marc; Kovetz, Ely D; Raccanelli, Alvise; Riess, Adam G

    2016-05-20

    We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20M_{⊙}≲M_{bh}≲100M_{⊙} where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2-53  Gpc^{-3} yr^{-1} rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next-generation experiments will be invaluable in performing these tests.

  5. Partially acoustic dark matter, interacting dark radiation, and large scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Chacko, Zackaria [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Cui, Yanou [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Department of Physics and Astronomy, University of California-Riverside,University Ave, Riverside, CA 92521 (United States); Perimeter Institute, 31 Caroline Street, North Waterloo, Ontario N2L 2Y5 (Canada); Hong, Sungwoo [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States); Okui, Takemichi [Department of Physics, Florida State University,College Avenue, Tallahassee, FL 32306 (United States); Tsai, Yuhsinz [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland,Stadium Dr., College Park, MD 20742 (United States)

    2016-12-21

    The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H{sub 0} and the matter density perturbation σ{sub 8} inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ{sub 8} problem, while the presence of tightly coupled dark radiation ameliorates the H{sub 0} problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

  6. Partially acoustic dark matter, interacting dark radiation, and large scale structure

    International Nuclear Information System (INIS)

    Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi; Tsai, Yuhsinz

    2016-01-01

    The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

  7. Experimental warming does not enhance soil respiration in a semiarid temperate forest-steppe ecosystem

    DEFF Research Database (Denmark)

    Lellei-Kovacs, E.; Kovacs-Lang, E.; Kalapos, T.

    2008-01-01

    are still limited. Soil respiration rate-measured monthly between April and November from 2003 to 2006-remained very low (0.09 - 1.53 mu mol CO2 m(-2) s(-1))in accordance with the moderate biological activity and low humus content of the nutrient poor, coarse sandy soil. Specific soil respiration rate...... ( calculated for unit soil organic matter content), however, was relatively high (0.36 - 7.92 mu mol CO g(-1) C(org)h(-1)) suggesting substrate limitation for soil biological activity. During the day, soil respiration rate was significantly lower at dawn than at midday, while seasonally clear temperature......The influence of simulated climate change on soil respiration was studied in a field experiment on 4 m x 5 m plots in the semiarid temperate Pannonian sand forest-steppe. This ecosystem type has low productivity and soil organic matter content, and covers large areas, yet data on soil carbon fluxes...

  8. Interacting dark sector and precision cosmology

    Science.gov (United States)

    Buen-Abad, Manuel A.; Schmaltz, Martin; Lesgourgues, Julien; Brinckmann, Thejs

    2018-01-01

    We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data (H0-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between ΛCDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (σ8-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full k-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over ΛCDM at 3–4 σ. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.

  9. Dark nebulae, dark lanes, and dust belts

    CERN Document Server

    Cooke, Antony

    2012-01-01

    As probably the only book of its type, this work is aimed at the observer who wants to spend time with something less conventional than the usual fare. Because we usually see objects in space by means of illumination of one kind or another, it has become routine to see them only in these terms. However, part of almost everything that we see is the defining dimension of dark shading, or even the complete obscuration of entire regions in space. Thus this book is focused on everything dark in space: those dark voids in the stellar fabric that mystified astronomers of old; the dark lanes reported in many star clusters; the magical dust belts or dusty regions that have given so many galaxies their identities; the great swirling 'folds' that we associate with bright nebulae; the small dark feature detectable even in some planetary nebulae; and more. Many observers pay scant attention to dark objects and details. Perhaps they are insufficiently aware of them or of the viewing potential they hold, but also it may be...

  10. Soil respiration in the cold desert environment of the Colorado Plateau (USA): Abiotic regulators and thresholds

    Science.gov (United States)

    Fernandez, D.P.; Neff, J.C.; Belnap, J.; Reynolds, R.L.

    2006-01-01

    Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems, which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature, organic carbon, and nitrogen influence soil respiration and examined whether the inverse-texture hypothesis applies to decomposition. Within our study site, the effect of texture on moisture, as described by the inverse texture hypothesis, was evident, but its effect on decomposition was not. Our results show temperature and moisture to be the dominant abiotic controls of soil respiration. Specifically, temporal offsets in temperature and moisture conditions appear to have a strong control on soil respiration, with the highest fluxes occurring in spring when temperature and moisture were favorable. These temporal offsets resulted in decomposition rates that were controlled by soil moisture and temperature thresholds. The highest fluxes of CO2 occurred when soil temperature was between 10 and 16??C and volumetric soil moisture was greater than 10%. Decomposition-cloth results, which integrate decomposition processes across several months, support the soil-respiration results and further illustrate the seasonal patterns of high respiration rates during spring and low rates during summer and fall. Results from this study suggest that the parameters used to predict soil respiration in mesic ecosystems likely do not apply in cold-desert environments. ?? Springer 2006.

  11. Significance of heme-based respiration in meat spoilage caused by Leuconostoc gasicomitatum.

    Science.gov (United States)

    Jääskeläinen, Elina; Johansson, Per; Kostiainen, Olli; Nieminen, Timo; Schmidt, Georg; Somervuo, Panu; Mohsina, Marzia; Vanninen, Paula; Auvinen, Petri; Björkroth, Johanna

    2013-02-01

    Leuconostoc gasicomitatum is a psychrotrophic lactic acid bacterium (LAB) which causes spoilage in cold-stored modified-atmosphere-packaged (MAP) meat products. In addition to the fermentative metabolism, L. gasicomitatum is able to respire when exogenous heme and oxygen are available. In this study, we investigated the respiration effects on growth rate, biomass, gene expression, and volatile organic compound (VOC) production in laboratory media and pork loin. The meat samples were evaluated by a sensory panel every second or third day for 29 days. We observed that functional respiration increased the growth (rate and yield) of L. gasicomitatum in laboratory media with added heme and in situ meat with endogenous heme. Respiration increased enormously (up to 2,600-fold) the accumulation of acetoin and diacetyl, which are buttery off-odor compounds in meat. Our transcriptome analyses showed that the gene expression patterns were quite similar, irrespective of whether respiration was turned off by excluding heme from the medium or mutating the cydB gene, which is essential in the respiratory chain. The respiration-based growth of L. gasicomitatum in meat was obtained in terms of population development and subsequent development of sensory characteristics. Respiration is thus a key factor explaining why L. gasicomitatum is so well adapted in high-oxygen packed meat.

  12. Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

    Science.gov (United States)

    Jarvi, Mickey P; Burton, Andrew J

    2013-09-01

    The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

  13. Dark photons from the center of the Earth: Smoking-gun signals of dark matter

    Science.gov (United States)

    Feng, Jonathan L.; Smolinsky, Jordan; Tanedo, Philip

    2016-01-01

    Dark matter may be charged under dark electromagnetism with a dark photon that kinetically mixes with the Standard Model photon. In this framework, dark matter will collect at the center of the Earth and annihilate into dark photons, which may reach the surface of the Earth and decay into observable particles. We determine the resulting signal rates, including Sommerfeld enhancements, which play an important role in bringing the Earth's dark matter population to their maximal, equilibrium value. For dark matter masses mX˜100 GeV - 10 TeV , dark photon masses mA'˜MeV -GeV , and kinetic mixing parameters ɛ ˜1 0-9- 1 0-7 , the resulting electrons, muons, photons, and hadrons that point back to the center of the Earth are a smoking-gun signal of dark matter that may be detected by a variety of experiments, including neutrino telescopes, such as IceCube, and space-based cosmic ray detectors, such as Fermi-LAT and AMS. We determine the signal rates and characteristics and show that large and striking signals—such as parallel muon tracks—are possible in regions of the (mA',ɛ ) plane that are not probed by direct detection, accelerator experiments, or astrophysical observations.

  14. Mitochondrial Respiration Is Reduced in Atherosclerosis, Promoting Necrotic Core Formation and Reducing Relative Fibrous Cap Thickness.

    Science.gov (United States)

    Yu, Emma P K; Reinhold, Johannes; Yu, Haixiang; Starks, Lakshi; Uryga, Anna K; Foote, Kirsty; Finigan, Alison; Figg, Nichola; Pung, Yuh-Fen; Logan, Angela; Murphy, Michael P; Bennett, Martin

    2017-12-01

    Mitochondrial DNA (mtDNA) damage is present in murine and human atherosclerotic plaques. However, whether endogenous levels of mtDNA damage are sufficient to cause mitochondrial dysfunction and whether decreasing mtDNA damage and improving mitochondrial respiration affects plaque burden or composition are unclear. We examined mitochondrial respiration in human atherosclerotic plaques and whether augmenting mitochondrial respiration affects atherogenesis. Human atherosclerotic plaques showed marked mitochondrial dysfunction, manifested as reduced mtDNA copy number and oxygen consumption rate in fibrous cap and core regions. Vascular smooth muscle cells derived from plaques showed impaired mitochondrial respiration, reduced complex I expression, and increased mitophagy, which was induced by oxidized low-density lipoprotein. Apolipoprotein E-deficient (ApoE -/- ) mice showed decreased mtDNA integrity and mitochondrial respiration, associated with increased mitochondrial reactive oxygen species. To determine whether alleviating mtDNA damage and increasing mitochondrial respiration affects atherogenesis, we studied ApoE -/- mice overexpressing the mitochondrial helicase Twinkle (Tw + /ApoE -/- ). Tw + /ApoE -/- mice showed increased mtDNA integrity, copy number, respiratory complex abundance, and respiration. Tw + /ApoE -/- mice had decreased necrotic core and increased fibrous cap areas, and Tw + /ApoE -/- bone marrow transplantation also reduced core areas. Twinkle increased vascular smooth muscle cell mtDNA integrity and respiration. Twinkle also promoted vascular smooth muscle cell proliferation and protected both vascular smooth muscle cells and macrophages from oxidative stress-induced apoptosis. Endogenous mtDNA damage in mouse and human atherosclerosis is associated with significantly reduced mitochondrial respiration. Reducing mtDNA damage and increasing mitochondrial respiration decrease necrotic core and increase fibrous cap areas independently of changes in

  15. Boreal and temperate trees show strong acclimation of respiration to warming.

    Science.gov (United States)

    Reich, Peter B; Sendall, Kerrie M; Stefanski, Artur; Wei, Xiaorong; Rich, Roy L; Montgomery, Rebecca A

    2016-03-31

    Plant respiration results in an annual flux of carbon dioxide (CO2) to the atmosphere that is six times as large as that due to the emissions from fossil fuel burning, so changes in either will impact future climate. As plant respiration responds positively to temperature, a warming world may result in additional respiratory CO2 release, and hence further atmospheric warming. Plant respiration can acclimate to altered temperatures, however, weakening the positive feedback of plant respiration to rising global air temperature, but a lack of evidence on long-term (weeks to years) acclimation to climate warming in field settings currently hinders realistic predictions of respiratory release of CO2 under future climatic conditions. Here we demonstrate strong acclimation of leaf respiration to both experimental warming and seasonal temperature variation for juveniles of ten North American tree species growing for several years in forest conditions. Plants grown and measured at 3.4 °C above ambient temperature increased leaf respiration by an average of 5% compared to plants grown and measured at ambient temperature; without acclimation, these increases would have been 23%. Thus, acclimation eliminated 80% of the expected increase in leaf respiration of non-acclimated plants. Acclimation of leaf respiration per degree temperature change was similar for experimental warming and seasonal temperature variation. Moreover, the observed increase in leaf respiration per degree increase in temperature was less than half as large as the average reported for previous studies, which were conducted largely over shorter time scales in laboratory settings. If such dampening effects of leaf thermal acclimation occur generally, the increase in respiration rates of terrestrial plants in response to climate warming may be less than predicted, and thus may not raise atmospheric CO2 concentrations as much as anticipated.

  16. Shrub encroachment alters sensitivity of soil respiration to temperature and moisture

    Science.gov (United States)

    Cable, Jessica M.; Barron-Gafford, Greg A.; Ogle, Kiona; Pavao-Zuckerman, Mitchell; Scott, Russell L.; Williams, David G.; Huxman, Travis E.

    2012-03-01

    A greater abundance of shrubs in semiarid grasslands affects the spatial patterns of soil temperature, moisture, and litter, resulting in fertile islands with potentially enhanced soil metabolic activity. The goal of this study was to quantify the microsite specificity of soil respiration in a semiarid riparian ecosystem experiencing shrub encroachment. We quantified the response of soil respiration to different microsite conditions created by big mesquite shrubs (near the trunk and the canopy edge), medium-sized mesquite, sacaton bunchgrasses, and open spaces. We hypothesized that soil respiration would be more temperature sensitive and less moisture sensitive and have a greater magnitude in shrub microsites compared with grass and open microsites. Field and incubation soil respiration data were simultaneously analyzed in a Bayesian framework to quantify the microsite-specific temperature and moisture sensitivities and magnitude of respiration. The analysis showed that shrub expansion increases the heterogeneity of respiration. Respiration has greater temperature sensitivity near the shrub canopy edge, and respiration rates are higher overall under big mesquite compared with those of the other microsites. Respiration in the microsites beneath medium-sized mesquites does not behave like a downscaled version of big mesquite microsites. The grass microsites show more similarity to big mesquite microsites than medium-sized shrubs. This study shows there can be a great deal of fine-scale spatial heterogeneity that accompanies shifts in vegetation structure. Such complexity presents a challenge in scaling soil respiration fluxes to the landscape for systems experiencing shrub encroachment, but quantifying this complexity is significantly important in determining overall ecosystem metabolic behavior.

  17. Mitochondrial respiration is sensitive to cytoarchitectural breakdown.

    Science.gov (United States)

    Kandel, Judith; Angelin, Alessia A; Wallace, Douglas C; Eckmann, David M

    2016-11-07

    An abundance of research suggests that cellular mitochondrial and cytoskeletal disruption are related, but few studies have directly investigated causative connections between the two. We previously demonstrated that inhibiting microtubule and microfilament polymerization affects mitochondrial motility on the whole-cell level in fibroblasts. Since mitochondrial motility can be indicative of mitochondrial function, we now further characterize the effects of these cytoskeletal inhibitors on mitochondrial potential, morphology and respiration. We found that although they did not reduce mitochondrial inner membrane potential, cytoskeletal toxins induced significant decreases in basal mitochondrial respiration. In some cases, basal respiration was only affected after cells were pretreated with the calcium ionophore A23187 in order to stress mitochondrial function. In most cases, mitochondrial morphology remained unaffected, but extreme microfilament depolymerization or combined intermediate doses of microtubule and microfilament toxins resulted in decreased mitochondrial lengths. Interestingly, these two particular exposures did not affect mitochondrial respiration in cells not sensitized with A23187, indicating an interplay between mitochondrial morphology and respiration. In all cases, inducing maximal respiration diminished differences between control and experimental groups, suggesting that reduced basal respiration originates as a largely elective rather than pathological symptom of cytoskeletal impairment. However, viability experiments suggest that even this type of respiration decrease may be associated with cell death.

  18. Elemental Concentration of Inhalable and Respirable Particulate ...

    African Journals Online (AJOL)

    20537 and respirable foam for I.O.M sampler. The elemental composition (Co, Ni, Zn, Cu, Fe, Pb, Cr, Mn and Cd) were analyzed by using Atomic Absorption Spectrophotometric (AAS). The data generated were subjected to descriptive analysis. In inhalable fraction,the enrichment factor ranged from 1-73.3 while in respirable ...

  19. Respirators: APR Issuer Self Study 33461

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Laboratory

    2016-07-13

    Respirators: APR Issuer Self-Study (course 33461) is designed to introduce and familiarize employees selected as air-purifying respirator (APR) issuers at Los Alamos National Laboratory (LANL) with the responsibilities, limitations, procedures, and resources for issuing APRs at LANL. The goal is to enable these issuers to consistently provide proper, functioning APRs to authorized users

  20. Hidden charged dark matter

    International Nuclear Information System (INIS)

    Feng, Jonathan L.; Kaplinghat, Manoj; Tu, Huitzu; Yu, Hai-Bo

    2009-01-01

    Can dark matter be stabilized by charge conservation, just as the electron is in the standard model? We examine the possibility that dark matter is hidden, that is, neutral under all standard model gauge interactions, but charged under an exact (\\rm U)(1) gauge symmetry of the hidden sector. Such candidates are predicted in WIMPless models, supersymmetric models in which hidden dark matter has the desired thermal relic density for a wide range of masses. Hidden charged dark matter has many novel properties not shared by neutral dark matter: (1) bound state formation and Sommerfeld-enhanced annihilation after chemical freeze out may reduce its relic density, (2) similar effects greatly enhance dark matter annihilation in protohalos at redshifts of z ∼ 30, (3) Compton scattering off hidden photons delays kinetic decoupling, suppressing small scale structure, and (4) Rutherford scattering makes such dark matter self-interacting and collisional, potentially impacting properties of the Bullet Cluster and the observed morphology of galactic halos. We analyze all of these effects in a WIMPless model in which the hidden sector is a simplified version of the minimal supersymmetric standard model and the dark matter is a hidden sector stau. We find that charged hidden dark matter is viable and consistent with the correct relic density for reasonable model parameters and dark matter masses in the range 1 GeV ∼ X ∼< 10 TeV. At the same time, in the preferred range of parameters, this model predicts cores in the dark matter halos of small galaxies and other halo properties that may be within the reach of future observations. These models therefore provide a viable and well-motivated framework for collisional dark matter with Sommerfeld enhancement, with novel implications for astrophysics and dark matter searches

  1. Instabilities in dark coupled models and constraints from cosmological data

    CERN Document Server

    Honorez, L Lopez

    2010-01-01

    Coupled dark matter-dark energy systems can suffer from non-adiabatic instabilities at early times and large scales. In these proceedings, we consider two parameterizations of the dark sector interaction. In the first one the energy-momentum transfer 4-vector is parallel to the dark matter 4-velocity and in the second one to the dark energy 4-velocity. In these cases, coupled models which suffer from non-adiabatic instabilities can be identified as a function of a generic coupling Q and of the dark energy equation of state. In our analysis, we do not refer to any particular cosmic field. We confront then a viable class of models in which the interaction is directly proportional to the dark energy density and to the Hubble rate parameter to recent cosmological data. In that framework, we show that correlations between the dark coupling and several cosmological parameters allow for a larger neutrino mass than in uncoupled models.

  2. Effects of cadmium, zinc, lead, and mercury on respiration and fermentation of Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Grafl, H J; Schwantes, H O

    1983-01-01

    Zinc and lead did not affect the rate of respiration and fermentation. Concentrations of cadmium higher than 10/sup -7/ M and concentrations of mercury higher than 5 x 10/sup -5/ M significantly reduced the O/sub 2/ consumption and the CO/sub 2/ production. 10/sup -2/ M cadmium and 10/sup -3/ M mercury completely inhibited respiration and fermentation. Low concentrations of mercury inhibited respiration irreversibly and fermentation reversibly. High concentrations of zinc reduced the toxicity of low concentrations of cadmium but they enhanced the effects of high concentrations of cadmium and mercury. No interactions between lead and the other tested heavy metals were observed.

  3. Chilling effect on soluble sugars, respiration rate, total phenolics, peroxidase activity and dormancy of onion bulbs Efeito do resfriamento sobre açúcares solúveis, taxa de respiração, fenóis totais, atividade de peroxidase e dormência de bulbos de cebola

    Directory of Open Access Journals (Sweden)

    Noureddine Benkeblia

    2004-06-01

    Full Text Available Besides onions being one of the most cultivated and consumed vegetables, during storage onion bulbs are still affected by many physiological, biochemical and technological factors which can influence their quality. Respiration rate (RR O2, soluble sugars (SS, total phenolics (TP, and peroxidase (POD activity were measured in inner bud tissues during a dormancy break of onion bulbs treated four weeks at 0ºC and stored in the dark at 20ºC. Control bulbs were stored simultaneously in the same condition. Breakage of dormancy was checked by the appearance of first green internal leaves by cutting longitudinally 30 bulbs. After eight weeks, RR O2 of sprouted onions was 52% higher than that of freshly harvested and dormant bulbs. One week after cooling SS decreased from 15 to 9 mg g-1 fresh weight, and then peaked from 9 to 19 mg g-1 after three weeks. For control bulbs, a similar peak was observed after six weeks. For inner buds of cold-treated onions, a slight increase of TP (from 0.17 to 0.2 mg g-1; fresh weight was observed during the first two weeks of cooling, and then a decrease to 0.11 mg g-1 was observed after eight weeks. For inner buds of control bulbs, TP also increased slightly from 0.17 to 0.2 mg g-1 after five weeks, and decreased to 0.15 mg g-1 after seven weeks when bulbs began to sprout. POD activity showed a similar pattern in relation to TP. For cold-treated bulbs, POD activity increased to 1.7 U g-1 fresh weight after two weeks, and decreased to 1.1 U g-1 during the last four weeks. For control samples, POD activity was stable during 4 weeks and decreased progressively by 29% during the last four weeks. This decrease in POD activity coincided with the decrease in TP, and coincided with onset of sprouting. With cold treatment, first sprouts were observed during the third week, while total sprouting was observed after eight weeks. In comparison, only 20% of the control bulbs sprouted after the period of 8 weeks.Além de ser uma das

  4. Contributions of ectomycorrhizal fungal mats to forest soil respiration

    Science.gov (United States)

    C. Phillips; L.A. Kluber; J.P. Martin; B.A. Caldwell; B.J. Bond

    2012-01-01

    Distinct aggregations of fungal hyphae and rhizomorphs, or “mats”, formed by some genera of ectomycorrhizal (EcM) fungi are common features of soils in coniferous forests of the Pacific Northwest. We measured in situ respiration rates of Piloderma mats and neighboring non-mat soils in an old-growth Douglas-fir forest in western Oregon to investigate whether there was...

  5. Oxygen dependence of respiration in rat spinotrapezius muscle in situ

    OpenAIRE

    Golub, Aleksander S.; Pittman, Roland N.

    2012-01-01

    The oxygen dependence of respiration in striated muscle in situ was studied by measuring the rate of decrease of interstitial Po2 [oxygen disappearance curve (ODC)] following rapid arrest of blood flow by pneumatic tissue compression, which ejected red blood cells from the muscle vessels and made the ODC independent from oxygen bound to hemoglobin. After the contribution of photo-consumption of oxygen by the method was evaluated and accounted for, the corrected ODCs were converted into the Po...

  6. Influence of vestibular activation on respiration in humans

    Science.gov (United States)

    Monahan, Kevin D.; Sharpe, Melissa K.; Drury, Daniel; Ertl, Andrew C.; Ray, Chester A.

    2002-01-01

    The purpose of this study was to determine the effects of the semicircular canals and otolith organs on respiration in humans. On the basis of animal studies, we hypothesized that vestibular activation would elicit a vestibulorespiratory reflex. To test this hypothesis, respiratory measures, arterial blood pressure, and heart rate were measured during engagement of semicircular canals and/or otolith organs. Dynamic upright pitch and roll (15 cycles/min), which activate the otolith organs and semicircular canals, increased respiratory rate (Delta2 +/- 1 and Delta3 +/- 1 breaths/min, respectively; P < 0.05). Dynamic yaw and lateral pitch (15 cycles/min), which activate the semicircular canals, increased respiration similarly (Delta3 +/- 1 and Delta2 +/- 1, respectively; P < 0.05). Dynamic chair rotation (15 cycles/min), which mimics dynamic yaw but eliminates neck muscle afferent, increased respiration (Delta3 +/- 1; P < 0.05) comparable to dynamic yaw (15 cycles/min). Increases in respiratory rate were graded as greater responses occurred during upright (Delta5 +/- 2 breaths/min) and lateral pitch (Delta4 +/- 1) and roll (Delta5 +/- 1) performed at 30 cycles/min. Increases in breathing frequency resulted in increases in minute ventilation during most interventions. Static head-down rotation, which activates otolith organs, did not alter respiratory rate (Delta1 +/- 1 breaths/min). Collectively, these data indicate that semicircular canals, but not otolith organs or neck muscle afferents, mediate increased ventilation in humans and support the concept that vestibular activation alters respiration in humans.

  7. Dark discrete gauge symmetries

    International Nuclear Information System (INIS)

    Batell, Brian

    2011-01-01

    We investigate scenarios in which dark matter is stabilized by an Abelian Z N discrete gauge symmetry. Models are surveyed according to symmetries and matter content. Multicomponent dark matter arises when N is not prime and Z N contains one or more subgroups. The dark sector interacts with the visible sector through the renormalizable kinetic mixing and Higgs portal operators, and we highlight the basic phenomenology in these scenarios. In particular, multiple species of dark matter can lead to an unconventional nuclear recoil spectrum in direct detection experiments, while the presence of new light states in the dark sector can dramatically affect the decays of the Higgs at the Tevatron and LHC, thus providing a window into the gauge origin of the stability of dark matter.

  8. Detecting dark matter

    International Nuclear Information System (INIS)

    Dixon, Roger L.

    2000-01-01

    Dark matter is one of the most pressing problems in modern cosmology and particle physic research. This talk will motivate the existence of dark matter by reviewing the main experimental evidence for its existence, the rotation curves of galaxies and the motions of galaxies about one another. It will then go on to review the corroborating theoretical motivations before combining all the supporting evidence to explore some of the possibilities for dark matter along with its expected properties. This will lay the ground work for dark matter detection. A number of differing techniques are being developed and used to detect dark matter. These will be briefly discussed before the focus turns to cryogenic detection techniques. Finally, some preliminary results and expectations will be given for the Cryogenic Dark Matter Search (CDMS) experiment

  9. Constraint on dark matter annihilation with dark star formation using Fermi extragalactic diffuse gamma-ray background data

    International Nuclear Information System (INIS)

    Yuan, Qiang; Yue, Bin; Chen, Xuelei; Zhang, Bing

    2011-01-01

    It has been proposed that during the formation of the first generation stars there might be a ''dark star'' phase in which the power of the star comes from dark matter annihilation. The adiabatic contraction process to form the dark star would result in a highly concentrated density profile of the host halo at the same time, which may give enhanced indirect detection signals of dark matter. In this work we investigate the extragalactic γ-ray background from dark matter annihilation with such a dark star formation scenario, and employ the isotropic γ-ray data from Fermi-LAT to constrain the model parameters of dark matter. The results suffer from large uncertainties of both the formation rate of the first generation stars and the subsequent evolution effects of the host halos of the dark stars. We find, in the most optimistic case for γ-ray production via dark matter annihilation, the expected extragalactic γ-ray flux will be enhanced by 1-2 orders of magnitude. In such a case, the annihilation cross section of the supersymmetric dark matter can be constrained to the thermal production level, and the leptonic dark matter model which is proposed to explain the positron/electron excesses can be well excluded. Conversely, if the positron/electron excesses are of a dark matter annihilation origin, then the early Universe environment is such that no dark star can form

  10. Clumpy cold dark matter

    Science.gov (United States)

    Silk, Joseph; Stebbins, Albert

    1993-01-01

    A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

  11. Charming dark matter

    Science.gov (United States)

    Jubb, Thomas; Kirk, Matthew; Lenz, Alexander

    2017-12-01

    We have considered a model of Dark Minimal Flavour Violation (DMFV), in which a triplet of dark matter particles couple to right-handed up-type quarks via a heavy colour-charged scalar mediator. By studying a large spectrum of possible constraints, and assessing the entire parameter space using a Markov Chain Monte Carlo (MCMC), we can place strong restrictions on the allowed parameter space for dark matter models of this type.

  12. Soil Respiration of Three Mangrove Forests on Sanibel Island, Florida

    Science.gov (United States)

    Cartwright, F.; Bovard, B. D.

    2011-12-01

    Carbon cycling studies conducted in mangrove forests have typically focused on aboveground processes. Our understanding of carbon storage in these systems is therefore limited by the lack information on belowground processes such as fine root production and soil respiration. To our knowledge there exist no studies investigating temporal patterns in and environmental controls on soil respiration in multiple types of mangrove ecosystems concurrently. This study is part of a larger study on carbon storage in three mangrove forests on Sanibel Island, Florida. Here we report on eight months of soil respiration data within these forests that will ultimately be incorporated into an annual carbon budget for each habitat type. Soil respiration was monitored in the following three mangrove habitat types: a fringe mangrove forest dominated by Rhizophora mangle, a basin mangrove forest dominated by Avicennia germinans, and a higher elevation forest comprised of a mix of Avicennia germinans and Laguncularia racemosa, and non-woody salt marsh species. Beginning in June of 2010, we measured soil emissions of carbon dioxide at 5 random locations within three-100 m2 plots within each habitat type. Sampling was performed at monthly intervals and conducted over the course of three days. For each day, one plot from each habitat type was measured. In addition to soil respiration, soil temperature, salinity and gravimetric moisture content were also measured. Our data indicate the Black mangrove forest, dominated by Avicennia germinans, experiences the highest rates of soil respiration with a mean rate of 4.61 ± 0.60 μmol CO2 m-2 s-1. The mixed mangrove and salt marsh habitat has the lowest soil carbon emission rates with a mean of 2.78 ± 0.40 μmol CO2 m-2 s-1. Soil carbon effluxes appear to peak in the early part of the wet season around May to June and are lower and relatively constant the remainder of the year. Our data also suggest there are important but brief periods where

  13. Estimating respiration of roots in soil: interactions with soil CO2, soil temperature and soil water content

    NARCIS (Netherlands)

    Bouma, T.J.; Nielsen, K.F.; Eissenstat, D.M.; Lynch, J.P.

    1997-01-01

    Little information is available on the variability of the dynamics of the actual and observed root respiration rate in relation to abiotic factors. In this study, we describe I) interactions between soil CO2 concentration, temperature, soil water content and root respiration, and II) the effect of

  14. Respiration of midges (Diptera; Chironomidae) in British Columbian lakes: oxy-regulation, temperature and their role as palaeo-indicators

    DEFF Research Database (Denmark)

    Brodersen, Klaus Peter; Pedersen, Ole; Walker, Ian R.

    2008-01-01

    1. The specific respiration rate of 13 chironomid taxa and Chaoborus were measured to test the hypothesis of the relation between a species' ability to regulate their oxygen uptake and their distributional patterns among nine study lakes in British Columbia, Canada. 2. Respiration patterns of ind...

  15. Dark energy and extended dark matter halos

    Science.gov (United States)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2012-03-01

    The cosmological mean matter (dark and baryonic) density measured in the units of the critical density is Ωm = 0.27. Independently, the local mean density is estimated to be Ωloc = 0.08-0.23 from recent data on galaxy groups at redshifts up to z = 0.01-0.03 (as published by Crook et al. 2007, ApJ, 655, 790 and Makarov & Karachentsev 2011, MNRAS, 412, 2498). If the lower values of Ωloc are reliable, as Makarov & Karachentsev and some other observers prefer, does this mean that the Local Universe of 100-300 Mpc across is an underdensity in the cosmic matter distribution? Or could it nevertheless be representative of the mean cosmic density or even be an overdensity due to the Local Supercluster therein. We focus on dark matter halos of groups of galaxies and check how much dark mass the invisible outer layers of the halos are able to host. The outer layers are usually devoid of bright galaxies and cannot be seen at large distances. The key factor which bounds the size of an isolated halo is the local antigravity produced by the omnipresent background of dark energy. A gravitationally bound halo does not extend beyond the zero-gravity surface where the gravity of matter and the antigravity of dark energy balance, thus defining a natural upper size of a system. We use our theory of local dynamical effects of dark energy to estimate the maximal sizes and masses of the extended dark halos. Using data from three recent catalogs of galaxy groups, we show that the calculated mass bounds conform with the assumption that a significant amount of dark matter is located in the invisible outer parts of the extended halos, sufficient to fill the gap between the observed and expected local matter density. Nearby groups of galaxies and the Virgo cluster have dark halos which seem to extend up to their zero-gravity surfaces. If the extended halo is a common feature of gravitationally bound systems on scales of galaxy groups and clusters, the Local Universe could be typical or even

  16. Dark matter and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  17. Dark matter and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

  18. Metastable dark energy

    Directory of Open Access Journals (Sweden)

    Ricardo G. Landim

    2017-01-01

    Full Text Available We build a model of metastable dark energy, in which the observed vacuum energy is the value of the scalar potential at the false vacuum. The scalar potential is given by a sum of even self-interactions up to order six. The deviation from the Minkowski vacuum is due to a term suppressed by the Planck scale. The decay time of the metastable vacuum can easily accommodate a mean life time compatible with the age of the universe. The metastable dark energy is also embedded into a model with SU(2R symmetry. The dark energy doublet and the dark matter doublet naturally interact with each other. A three-body decay of the dark energy particle into (cold and warm dark matter can be as long as large fraction of the age of the universe, if the mediator is massive enough, the lower bound being at intermediate energy level some orders below the grand unification scale. Such a decay shows a different form of interaction between dark matter and dark energy, and the model opens a new window to investigate the dark sector from the point-of-view of particle physics.

  19. Hybrid Dark Matter

    OpenAIRE

    Chao, Wei

    2018-01-01

    Dark matter can be produced in the early universe via the freeze-in or freeze-out mechanisms. Both scenarios were investigated in references, but the production of dark matters via the combination of these two mechanisms are not addressed. In this paper we propose a hybrid dark matter model where dark matters have two components with one component produced thermally and the other one produced non-thermally. We present for the first time the analytical calculation for the relic abundance of th...

  20. Dark matter and cosmology

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1992-03-01

    The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the Ω = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ''cold'' and ''hot'' non-baryonic candidates is shown to depend on the assumed ''seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed

  1. Dark U (1)

    International Nuclear Information System (INIS)

    Chang, Chia-Feng; Ma, Ernest; Yuan, Tzu-Chiang

    2015-01-01

    In this talk we will explore the possibility of adding a local U(1) dark sector to the standard model with the Higgs boson as a portal connecting the visible standard model sector and the dark one. We will discuss existing experimental constraint on the model parameters from the invisible width of Higgs decay. Implications of such a dark U(1) sector on phenomenology at the Large Hardon Collider will be addressed. In particular, detailed results for the non-standard signals of multi-lepton-jets that arise from this simple dark sector will be presented. (paper)

  2. Searching for dark matter

    Science.gov (United States)

    Mateo, Mario

    1994-01-01

    Three teams of astronomers believe they have independently found evidence for dark matter in our galaxy. A brief history of the search for dark matter is presented. The use of microlensing-event observation for spotting dark matter is described. The equipment required to observe microlensing events and three groups working on dark matter detection are discussed. The three groups are the Massive Compact Halo Objects (MACHO) Project team, the Experience de Recherche d'Objets Sombres (EROS) team, and the Optical Gravitational Lensing Experiment (OGLE) team. The first apparent detections of microlensing events by the three teams are briefly reported.

  3. Chaplygin dark star

    International Nuclear Information System (INIS)

    Bertolami, O.; Paramos, J.

    2005-01-01

    We study the general properties of a spherically symmetric body described through the generalized Chaplygin equation of state. We conclude that such an object, dubbed generalized Chaplygin dark star, should exist within the context of the generalized Chaplygin gas (GCG) model of unification of dark energy and dark matter, and derive expressions for its size and expansion velocity. A criteria for the survival of the perturbations in the GCG background that give origin to the dark star are developed, and its main features are analyzed

  4. Soil respiration in northern forests exposed to elevated atmospheric carbon dioxide and ozone.

    Science.gov (United States)

    Pregitzer, Kurt; Loya, Wendy; Kubiske, Mark; Zak, Donald

    2006-06-01

    The aspen free-air CO2 and O3 enrichment (FACTS II-FACE) study in Rhinelander, Wisconsin, USA, is designed to understand the mechanisms by which young northern deciduous forest ecosystems respond to elevated atmospheric carbon dioxide (CO2) and elevated tropospheric ozone (O3) in a replicated, factorial, field experiment. Soil respiration is the second largest flux of carbon (C) in these ecosystems, and the objective of this study was to understand how soil respiration responded to the experimental treatments as these fast-growing stands of pure aspen and birch + aspen approached maximum leaf area. Rates of soil respiration were typically lowest in the elevated O3 treatment. Elevated CO2 significantly stimulated soil respiration (8-26%) compared to the control treatment in both community types over all three growing seasons. In years 6-7 of the experiment, the greatest rates of soil respiration occurred in the interaction treatment (CO2 + O3), and rates of soil respiration were 15-25% greater in this treatment than in the elevated CO2 treatment, depending on year and community type. Two of the treatments, elevated CO2 and elevated CO2 + O3, were fumigated with 13C-depleted CO2, and in these two treatments we used standard isotope mixing models to understand the proportions of new and old C in soil respiration. During the peak of the growing season, C fixed since the initiation of the experiment in 1998 (new C) accounted for 60-80% of total soil respiration. The isotope measurements independently confirmed that more new C was respired from the interaction treatment compared to the elevated CO2 treatment. A period of low soil moisture late in the 2003 growing season resulted in soil respiration with an isotopic signature 4-6 per thousand enriched in 13C compared to sample dates when the percentage soil moisture was higher. In 2004, an extended period of low soil moisture during August and early September, punctuated by a significant rainfall event, resulted in soil

  5. Asymmetric Dark Matter and Dark Radiation

    International Nuclear Information System (INIS)

    Blennow, Mattias; Martinez, Enrique Fernandez; Mena, Olga; Redondo, Javier; Serra, Paolo

    2012-01-01

    Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, precise measurements of the number of relativistic species, such as those expected from the Planck satellite, can provide information on the structure of the dark sector. We also discuss the constraints of the interactions between DM and Dark Radiation from their imprint in the matter power spectrum

  6. Gravitational effects of condensate dark matter on compact stellar objects

    International Nuclear Information System (INIS)

    Li, X.Y.; Wang, F.Y.; Cheng, K.S.

    2012-01-01

    We study the gravitational effect of non-self-annihilating dark matter on compact stellar objects. The self-interaction of condensate dark matter can give high accretion rate of dark matter onto stars. Phase transition to condensation state takes place when the dark matter density exceeds the critical value. A compact degenerate dark matter core is developed and alter the structure and stability of the stellar objects. Condensate dark matter admixed neutron stars is studied through the two-fluid TOV equation. The existence of condensate dark matter deforms the mass-radius relation of neutron stars and lower their maximum baryonic masses and radii. The possible effects on the Gamma-ray Burst rate in high redshift are discussed

  7. Charged mediators in dark matter scattering

    Science.gov (United States)

    Stengel, Patrick

    2017-11-01

    We consider a scenario, within the framework of the MSSM, in which dark matter is bino-like and dark matter-nucleon spin-independent scattering occurs via the exchange of light squarks which exhibit left-right mixing. We show that direct detection experiments such as LUX and SuperCDMS will be sensitive to a wide class of such models through spin-independent scattering. The dominant nuclear physics uncertainty is the quark content of the nucleon, particularly the strangeness content. We also investigate parameter space with nearly degenerate neutralino and squark masses, thus enhancing dark matter annihilation and nucleon scattering event rates.

  8. Soil respiration in different agricultural and natural ecosystems in an arid region.

    Directory of Open Access Journals (Sweden)

    Liming Lai

    Full Text Available The variation of different ecosystems on the terrestrial carbon balance is predicted to be large. We investigated a typical arid region with widespread saline/alkaline soils, and evaluated soil respiration of different agricultural and natural ecosystems. Soil respiration for five ecosystems together with soil temperature, soil moisture, soil pH, soil electric conductivity and soil organic carbon content were investigated in the field. Comparing with the natural ecosystems, the mean seasonal soil respiration rates of the agricultural ecosystems were 96%-386% higher and agricultural ecosystems exhibited lower CO(2 absorption by the saline/alkaline soil. Soil temperature and moisture together explained 48%, 86%, 84%, 54% and 54% of the seasonal variations of soil respiration in the five ecosystems, respectively. There was a significant negative relationship between soil respiration and soil electrical conductivity, but a weak correlation between soil respiration and soil pH or soil organic carbon content. Our results showed that soil CO(2 emissions were significantly different among different agricultural and natural ecosystems, although we caution that this was an observational, not manipulative, study. Temperature at the soil surface and electric conductivity were the main driving factors of soil respiration across the five ecosystems. Care should be taken when converting native vegetation into cropland from the point of view of greenhouse gas emissions.

  9. Respiration Gates Sensory Input Responses in the Mitral Cell Layer of the Olfactory Bulb

    Science.gov (United States)

    Short, Shaina M.; Morse, Thomas M.; McTavish, Thomas S.; Shepherd, Gordon M.; Verhagen, Justus V.

    2016-01-01

    Respiration plays an essential role in odor processing. Even in the absence of odors, oscillating excitatory and inhibitory activity in the olfactory bulb synchronizes with respiration, commonly resulting in a burst of action potentials in mammalian mitral/tufted cells (MTCs) during the transition from inhalation to exhalation. This excitation is followed by inhibition that quiets MTC activity in both the glomerular and granule cell layers. Odor processing is hypothesized to be modulated by and may even rely on respiration-mediated activity, yet exactly how respiration influences sensory processing by MTCs is still not well understood. By using optogenetics to stimulate discrete sensory inputs in vivo, it was possible to temporally vary the stimulus to occur at unique phases of each respiration. Single unit recordings obtained from the mitral cell layer were used to map spatiotemporal patterns of glomerular evoked responses that were unique to stimulations occurring during periods of inhalation or exhalation. Sensory evoked activity in MTCs was gated to periods outside phasic respiratory mediated firing, causing net shifts in MTC activity across the cycle. In contrast, odor evoked inhibitory responses appear to be permitted throughout the respiratory cycle. Computational models were used to further explore mechanisms of inhibition that can be activated by respiratory activity and influence MTC responses. In silico results indicate that both periglomerular and granule cell inhibition can be activated by respiration to internally gate sensory responses in the olfactory bulb. Both the respiration rate and strength of lateral connectivity influenced inhibitory mechanisms that gate sensory evoked responses. PMID:28005923

  10. Soil respiration in different agricultural and natural ecosystems in an arid region.

    Science.gov (United States)

    Lai, Liming; Zhao, Xuechun; Jiang, Lianhe; Wang, Yongji; Luo, Liangguo; Zheng, Yuanrun; Chen, Xi; Rimmington, Glyn M

    2012-01-01

    The variation of different ecosystems on the terrestrial carbon balance is predicted to be large. We investigated a typical arid region with widespread saline/alkaline soils, and evaluated soil respiration of different agricultural and natural ecosystems. Soil respiration for five ecosystems together with soil temperature, soil moisture, soil pH, soil electric conductivity and soil organic carbon content were investigated in the field. Comparing with the natural ecosystems, the mean seasonal soil respiration rates of the agricultural ecosystems were 96%-386% higher and agricultural ecosystems exhibited lower CO(2) absorption by the saline/alkaline soil. Soil temperature and moisture together explained 48%, 86%, 84%, 54% and 54% of the seasonal variations of soil respiration in the five ecosystems, respectively. There was a significant negative relationship between soil respiration and soil electrical conductivity, but a weak correlation between soil respiration and soil pH or soil organic carbon content. Our results showed that soil CO(2) emissions were significantly different among different agricultural and natural ecosystems, although we caution that this was an observational, not manipulative, study. Temperature at the soil surface and electric conductivity were the main driving factors of soil respiration across the five ecosystems. Care should be taken when converting native vegetation into cropland from the point of view of greenhouse gas emissions.

  11. Arbuscular mycorrhizal fungi regulate soil respiration and its response to precipitation change in a semiarid steppe.

    Science.gov (United States)

    Zhang, Bingwei; Li, Shan; Chen, Shiping; Ren, Tingting; Yang, Zhiqiang; Zhao, Hanlin; Liang, Yu; Han, Xingguo

    2016-01-28

    Arbuscular mycorrhizal fungi (AMF) are critical links in plant-soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010-2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m(-2) across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons.

  12. Arbuscular mycorrhizal fungi regulate soil respiration and its response to precipitation change in a semiarid steppe

    Science.gov (United States)

    Zhang, Bingwei; Li, Shan; Chen, Shiping; Ren, Tingting; Yang, Zhiqiang; Zhao, Hanlin; Liang, Yu; Han, Xingguo

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) are critical links in plant-soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010-2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m-2 across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons.

  13. EXPERIMENTAL SUBSTANTIATION OF PERMEABILIZED HEPATOCYTES MODEL FOR INVESTIGATION OF MITOCHONDRIA IN SITU RESPIRATION.

    Science.gov (United States)

    Merlavsky, V M; Manko, B O; Ikkert, O V; Manko, V V

    2015-01-01

    To verify experimentally the model of permeabilized hepatocytes, the degree of cell permeability was assessed using trypan blue and polarographycally determined cell respiration rate upon succinate (0.35 mM) and a-ketoglutarate (1 mM) oxidation. Oxidative phosphorylation was stimulated by ADP (750 μM). Hepatocyte permeabilization depends on digitonin concentraion in medium and on the number of cells in suspension. Thus, the permeabilization of 0.9-1.7 million cells/ml was completed by 25 μg/ml of digitonin, permeabilization of 2.0-3.0 million cells/ml--by 50 μg/ml of digitonin and permeabilization of 4.0-5.6 million cells/ml--by 100 μg/ml. Thus, the higher is the suspension density, the higher digitonin concentration is required. Treatment of hepatocytes with digitonin resulted in a decrease of endogenous respiration rate to a minimum upon 20-22 μg of digitonin per 1 million cells. Supplementation of permeabilized hepatocytes with α-ketoglutarate maintained stable respiration rate, on the level higher than endogenous respiration at the corresponding digitonin concentration, unlike the intact cells. Respiration rate of permeabilized hepatocytes at the simultaneous addition of α-ketoglutarate and ADP increased to the level of intact cell respiration, irrespective of digitonin concentration. Addition of solely succinate and especially succinate plus ADP markedly intensified the respiration of permeabilized hepatocytes to the level higher than that of intact cells. The dependence of succinate-stimulated respiration on digitonin concentration reached maximum at 20-22 αg of digitonin per 1 million cells. Optimal ratio of digitonin amount and the cell number in suspension is expected to be different in various tissues.

  14. Dark shadow of the long white cloud: Neighborhood safety is associated with self-rated health and cortisol during pregnancy in Auckland, Aotearoa/New Zealand

    Directory of Open Access Journals (Sweden)

    Zaneta M. Thayer

    2017-12-01

    Full Text Available Auckland, Aotearoa/New Zealand is a culturally and ethnically diverse city. Despite popular global conceptions regarding its utopian nature, the lived experience for many individuals in Auckland attests to the substantial social, economic, and health inequalities that exist there. In particular, rapidly rising home prices constrain housing decisions and force individuals to live in less desirable neighborhoods, with potential impacts on individual health. One of the pathways through which adverse neighborhood conditions could impact health is through alterations in the functioning of the hypothalamic pituitary adrenal (HPA-axis, which regulates the physiological stress response. This paper evaluates the relationship between perceived neighborhood safety, self-rated health, and cortisol, an end product of HPA-axis activation, among women in late pregnancy. Pregnant women living in neighborhoods where they were concerned about safety of their property had poorer self-rated health and elevated morning cortisol, even after adjusting for maternal age, material deprivation, and ethnicity. However, fear of personal safety was unrelated to self-rated health and cortisol. These results suggest that maternal health in pregnancy is sensitive to perceptions regarding neighborhood safety. Such findings are important since higher cortisol levels in pregnancy could not only influence maternal health, but also the health and development of women's children.

  15. Dark shadow of the long white cloud: Neighborhood safety is associated with self-rated health and cortisol during pregnancy in Auckland, Aotearoa/New Zealand.

    Science.gov (United States)

    Thayer, Zaneta M

    2017-12-01

    Auckland, Aotearoa /New Zealand is a culturally and ethnically diverse city. Despite popular global conceptions regarding its utopian nature, the lived experience for many individuals in Auckland attests to the substantial social, economic, and health inequalities that exist there. In particular, rapidly rising home prices constrain housing decisions and force individuals to live in less desirable neighborhoods, with potential impacts on individual health. One of the pathways through which adverse neighborhood conditions could impact health is through alterations in the functioning of the hypothalamic pituitary adrenal (HPA)-axis, which regulates the physiological stress response. This paper evaluates the relationship between perceived neighborhood safety, self-rated health, and cortisol, an end product of HPA-axis activation, among women in late pregnancy. Pregnant women living in neighborhoods where they were concerned about safety of their property had poorer self-rated health and elevated morning cortisol, even after adjusting for maternal age, material deprivation, and ethnicity. However, fear of personal safety was unrelated to self-rated health and cortisol. These results suggest that maternal health in pregnancy is sensitive to perceptions regarding neighborhood safety. Such findings are important since higher cortisol levels in pregnancy could not only influence maternal health, but also the health and development of women's children.

  16. [Soil respiration characteristics in winter wheat field in North China Plain].

    Science.gov (United States)

    Chen, Shuyue; Li, Jun; Lu, Peiling; Wang, Yinghong; Yu, Qiang

    2004-09-01

    Experiments were conducted at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during 2002-2003 to investigate the respiration of a pulverous sandstone soil under cultivation of winter wheat over a growth season. The effluent CO2 was collected and analyzed by the static-chamber/gas chromatography (GC) method at a frequency of once a week in spring and autumn, once two weeks in winter, twice a week for straw manure treatment, once a week for no straw manure treatment and nitrogen fertilization treatment in summer. The results indicated that diurnal variation of soil respiration rate showed a single peak in typical winter wheat farmlands in the North China Plain, and reached the highest at about 13 o'clock, and the lowest at about 4 o'clock in the early morning. In winter wheat growth season, the soil respiration rate was 31.23-606.85 mg x m(-2) x h(-1) under straw manure, 28.99-549.66 x m(-2) x h(-1) under no straw manure, 10.46-590.86 mg x m(-2) x h(-1) in N0, 16.11-349.88 mg x m(-2) x h(-1) in N100, 12.25-415.00 mg x m(-2) x h(-1) in N200, and 23.01-410.58 mg x m(-2) x h(-1) in N300, showing a similar seasonal variation tendency with soil temperature. Among all treatments, the straw manure had the most distinct soil respiration, though the soil respiration also increased slightly with increasing nitrogen fertilization. Soil respiration increased exponentially with increasing soil temperature, and the correlation of soil temperature at the depth of 5 cm was the best. This relationship was usually described with the Q10 model, which represented the sensitivity of soil respiration to temperature. Q10 was not a fixed value, which varied with the depth at which the temperature was measured and the depth of the active soil layer and soil temperature. At same time, the Q10 value decreased with increasing soil temperature. Soil water content was another important factor affecting soil respiration rate, but in this region, the relationship

  17. Covariant generalized holographic dark energy and accelerating universe

    Science.gov (United States)

    Nojiri, Shin'ichi; Odintsov, S. D.

    2017-08-01

    We propose the generalized holographic dark energy model where the infrared cutoff is identified with the combination of the FRW universe parameters: the Hubble rate, particle and future horizons, cosmological constant, the universe lifetime (if finite) and their derivatives. It is demonstrated that with the corresponding choice of the cutoff one can map such holographic dark energy to modified gravity or gravity with a general fluid. Explicitly, F( R) gravity and the general perfect fluid are worked out in detail and the corresponding infrared cutoff is found. Using this correspondence, we get realistic inflation or viable dark energy or a unified inflationary-dark energy universe in terms of covariant holographic dark energy.

  18. Asymmetric Dark Matter and Dark Radiation

    CERN Document Server

    Blennow, Mattias; Mena, Olga; Redondo, Javier; Serra, Paolo

    2012-01-01

    Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry, similar to the one observed in the Baryon sector, to account for the Dark Matter (DM) abundance. Both asymmetries are usually generated by the same mechanism and generally related, thus predicting DM masses around 5 GeV in order to obtain the correct density. The main challenge for successful models is to ensure efficient annihilation of the thermally produced symmetric component of such a light DM candidate without violating constraints from collider or direct searches. A common way to overcome this involves a light mediator, into which DM can efficiently annihilate and which subsequently decays into Standard Model particles. Here we explore the scenario where the light mediator decays instead into lighter degrees of freedom in the dark sector that act as radiation in the early Universe. While this assumption makes indirect DM searches challenging, it leads to signals of extra radiation at BBN and CMB. Under certain conditions, pre...

  19. On the relative roles of hydrology, salinity, temperature, and root productivity in controlling soil respiration from coastal swamps (freshwater)

    Science.gov (United States)

    Krauss, Ken W.; Whitbeck, Julie L.; Howard, Rebecca J.

    2012-01-01

    Background and aims Soil CO2 emissions can dominate gaseous carbon losses from forested wetlands (swamps), especially those positioned in coastal environments. Understanding the varied roles of hydroperiod, salinity, temperature, and root productivity on soil respiration is important in discerning how carbon balances may shift as freshwater swamps retreat inland with sea-level rise and salinity incursion, and convert to mixed communities with marsh plants. Methods We exposed soil mesocosms to combinations of permanent flooding, tide, and salinity, and tracked soil respiration over 2 1/2 growing seasons. We also related these measurements to rates from field sites along the lower Savannah River, Georgia, USA. Soil temperature and root productivity were assessed simultaneously for both experiments. Results Soil respiration from mesocosms (22.7-1678.2 mg CO2 m-2 h-1) differed significantly among treatments during four of the seven sampling intervals, where permanently flooded treatments contributed to low rates of soil respiration and tidally flooded treatments sometimes contributed to higher rates. Permanent flooding reduced the overall capacity for soil respiration as soils warmed. Salinity did reduce soil respiration at times in tidal treatments, indicating that salinity may affect the amount of CO2 respired with tide more strongly than under permanent flooding. However, soil respiration related greatest to root biomass (mesocosm) and standing root length (field); any stress reducing root productivity (incl. salinity and permanent flooding) therefore reduces soil respiration. Conclusions Overall, we hypothesized a stronger, direct role for salinity on soil respiration, and found that salinity effects were being masked by varied capacities for increases in respiration with soil warming as dictated by hydrology, and the indirect influence that salinity can have on plant productivity.

  20. Vegetation types alter soil respiration and its temperature sensitivity at the field scale in an estuary wetland.

    Directory of Open Access Journals (Sweden)

    Guangxuan Han

    Full Text Available Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively. During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m(-2 s(-1, followed by the Suaeda salsa site (0.77 µmol CO2 m(-2 s(-1 and the bare soil site (0.41 µmol CO2 m(-2 s(-1. The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland.

  1. Vegetation Types Alter Soil Respiration and Its Temperature Sensitivity at the Field Scale in an Estuary Wetland

    Science.gov (United States)

    Han, Guangxuan; Xing, Qinghui; Luo, Yiqi; Rafique, Rashad; Yu, Junbao; Mikle, Nate

    2014-01-01

    Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil) in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q 10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively). During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m−2 s−1), followed by the Suaeda salsa site (0.77 µmol CO2 m−2 s−1) and the bare soil site (0.41 µmol CO2 m−2 s−1). The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland. PMID:24608636

  2. DLHA: Dark Matter Les Houches Agreement

    International Nuclear Information System (INIS)

    Balazs, C.; Cerdeno, D.G.; Leane, R.; Kakizaki, M.; Kraml, S.; Savage, C.; Scott, P.; Sekmen, S.

    2012-01-01

    This work presents a set of conventions and numerical structures that aim to provide a universal interface between computer programs calculating dark matter related observables. It specifies input and output parameters for the calculation of observables such as abundance, direct and various indirect detection rates. These parameters range from cosmological to astrophysical to nuclear observables. The present conventions lay the foundations for defining a future Les Houches Dark Matter Accord. (authors)

  3. Candidates for non-baryonic dark matter

    International Nuclear Information System (INIS)

    Fornengo, Nicolao

    2002-01-01

    This report is a brief review of the efforts to explain the nature of non-baryonic dark matter and of the studies devoted to the search for relic particles. Among the different dark matter candidates, special attention is devoted to relic neutralinos, by giving an overview of the recent calculations of its relic abundance and detection rates in a wide variety of supersymmetric schemes

  4. Candidates for non-baryonic dark matter

    OpenAIRE

    Fornengo, Nicolao

    2002-01-01

    This report is a brief review of the efforts to explain the nature of non-baryonic dark matter and of the studies devoted to the search for relic particles. Among the different dark matter candidates, special attention is devoted to relic neutralinos, by giving an overview of the recent calculations of its relic abundance and detection rates in a wide variety of supersymmetric schemes.

  5. Dark Energy vs. Dark Matter: Towards a Unifying Scalar Field?

    OpenAIRE

    Arbey, A.

    2008-01-01

    The standard model of cosmology suggests the existence of two components, "dark matter" and "dark energy", which determine the fate of the Universe. Their nature is still under investigation, and no direct proof of their existences has emerged yet. There exist alternative models which reinterpret the cosmological observations, for example by replacing the dark energy/dark matter hypothesis by the existence of a unique dark component, the dark fluid, which is able to mimic the behaviour of bot...

  6. Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field

    International Nuclear Information System (INIS)

    Tissue, D. T.; Lewis, J. D.; Wullschleger, S. D.; Amthro, J. S.; Griffin, K. L.; Anderson, O. R.

    2002-01-01

    The effects of elevated carbon dioxide and canopy position on leaf respiration in sweetgum trees in a closed canopy forest were measured in an effort to determine if, and why, enriched atmospheric carbon dioxide might affect leaf respiration in sweetgum. To account for the dark respiratory response to growth in elevated carbon dioxide, cell ultrastructure and cytochrome c oxidase activity in leaves were measured at different seasonal growth periods. Leaf respiration under light conditions was also estimated to determine whether elevated carbon dioxide affected daytime respiration. Results showed that long-term exposure to elevated carbon dioxide did not effect night-time or day- time respiration in trees grown in a plantation in the field. Canopy position affected night-time respiration partially, through the effects on leaf soluble sugar, starch, nitrogen and leaf mass per unit area. In carbon dioxide partial pressure the effects of canopy position were insignificant. It was concluded that elevated carbon dioxide does not directly impact leaf respiration in sweetgum and assuming no changes in leaf nitrogen or leaf chemical composition, the long-term effects on respiration in this species will be minimal. 50 refs., 4 tabs., 3 figs

  7. Internal respiration of Amazon tree stems greatly exceeds external CO2 efflux

    Directory of Open Access Journals (Sweden)

    J. Q. Chambers

    2012-12-01

    Full Text Available Respiration in tree stems is an important component of forest carbon balance. The rate of CO2 efflux from the stem has often been assumed to be a measure of stem respiration. However, recent work in temperate forests has demonstrated that stem CO2 efflux can either overestimate or underestimate respiration rate because of emission or removal of CO2 by transport in xylem water. Here, we studied gas exchange from stems of tropical forest trees using a new approach to better understand respiration in an ecosystem that plays a key role in the global carbon cycle. Our main questions were (1 is internal CO2 transport important in tropical trees, and, if so, (2 does this transport result in net release of CO2 respired in the roots at the stem, or does it cause the opposite effect of net removal of stem-respired CO2? To answer these questions, we measured the ratio of stem CO2 efflux to O2 influx. This ratio, defined here as apparent respiratory quotient (ARQ, is expected to equal 1.0 if carbohydrates are the substrate for respiration, and the net transport of CO2 in the xylem water is negligible. Using a stem chamber approach to quantifying ARQ, we found values of 0.66 ± 0.18. These low ARQ values indicate that a large portion of respired CO2 (~ 35% is not emitted locally, and is probably transported upward in the stem. ARQ values of 0.21 ± 0.10 were found for the steady-state gas concentration within the stem, sampled by in-stem equilibration probes. These lower values may result from the proximity to the xylem water stream. In contrast, we found ARQ values of 1.00 ± 0.13 for soil respiration. Our results indicate the existence of a considerable internal flux of CO2 in the stems of tropical trees. If the transported CO2 is used in the canopy as a substrate for photosynthesis, it could account for up to 10% of the C fixed by the tree, and perhaps serve as a mechanism that buffers the response of the tree to changing CO2 levels. Our results also

  8. Superball dark matter

    CERN Document Server

    Kusenko, A

    1999-01-01

    Supersymmetric models predict a natural dark-matter candidate, stable baryonic Q-balls. They could be copiously produced in the early Universe as a by-product of the Affleck-Dine baryogenesis. I review the cosmological and astrophysical implications, methods of detection, and the present limits on this form of dark matter.

  9. Baryonic Dark Matter

    OpenAIRE

    De Paolis, F.; Jetzer, Ph.; Ingrosso, G.; Roncadelli, M.

    1997-01-01

    Reasons supporting the idea that most of the dark matter in galaxies and clusters of galaxies is baryonic are discussed. Moreover, it is argued that most of the dark matter in galactic halos should be in the form of MACHOs and cold molecular clouds.

  10. Asymptotically Safe Dark Matter

    DEFF Research Database (Denmark)

    Sannino, Francesco; Shoemaker, Ian M.

    2015-01-01

    We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting...... searches are the primary ways to constrain or discover asymptotically safe dark matter....

  11. The Dark Matter Problem

    NARCIS (Netherlands)

    Sanders, Robert H.

    1. Introduction; 2. Early history of the dark matter hypothesis; 3. The stability of disk galaxies: the dark halo solutions; 4. Direct evidence: extended rotation curves of spiral galaxies; 5. The maximum disk: light traces mass; 6. Cosmology and the birth of astroparticle physics; 7. Clusters

  12. Asymmetric dark matter

    International Nuclear Information System (INIS)

    Kaplan, David E.; Luty, Markus A.; Zurek, Kathryn M.

    2009-01-01

    We consider a simple class of models in which the relic density of dark matter is determined by the baryon asymmetry of the Universe. In these models a B-L asymmetry generated at high temperatures is transferred to the dark matter, which is charged under B-L. The interactions that transfer the asymmetry decouple at temperatures above the dark matter mass, freezing in a dark matter asymmetry of order the baryon asymmetry. This explains the observed relation between the baryon and dark matter densities for the dark matter mass in the range 5-15 GeV. The symmetric component of the dark matter can annihilate efficiently to light pseudoscalar Higgs particles a or via t-channel exchange of new scalar doublets. The first possibility allows for h 0 →aa decays, while the second predicts a light charged Higgs-like scalar decaying to τν. Direct detection can arise from Higgs exchange in the first model or a nonzero magnetic moment in the second. In supersymmetric models, the would-be lightest supersymmetric partner can decay into pairs of dark matter particles plus standard model particles, possibly with displaced vertices.

  13. Effect of biochar produced at different pyrolysis temperature on the soil respiration of abandoned mine soil

    Science.gov (United States)

    Kim, Yong Seong; Kim, Juhee; Hwang, Wonjae; Hyun, Seunghun

    2015-04-01

    Contaminated soils near an abandoned mine site included the high acidic mine tailing have received great interest due to potential risk to human health, because leachable elements in low pH continuously release from mine site soil with ground water and precipitation event. Biochar, which is the obtained pyrolysis process of biomass, is used as a soil amendments and carbon storage. Especially, many researchers report that the biochar application to soil show increasing soil pH, CEC, adsorption capacity of various elements, as well as, enhanced microbial activity. Therefore, biochar application to contaminated soil near abandoned mine site is expected to have a positive effects on management of these site and soils through the decreased leachability of contaminants. However, effects of biochar application to these site on the soil respiration, as a common measure of soil health, are poorly understood. The objective of this study is to evaluate the effects of biochar application to abandoned mine site soil on the microbial activity with soil respiration test. Biochar was obtained from giant Miscanthus in a slow pyrolysis process (heating rate of 10° C min-1 and N2 gas flow rate of 1.2 L min-1) at the temperature of 400° C (BC4) and 700° C (BC7), respectively. All biochar samples were prepared with grinding and sieving for particle size control (150~500μm). Soil sample was collected from abandoned mine site at Korea (36° 58'N, 128° 10'E). Main contaminants of this soil were As (12.5 g kg-1), Pb (7.3 g kg-1), and Zn (1.1 g kg-1). Biochars were applied (5% by dry weight) to the soil (final mixture weight were 800g), and then moisture contents were adjusted to 100% field capacity (-0.33 bar) in the respirometer with vacuum pump. CO2 efflux of each samples was continuously assessed using continuous aeration system (air flow rate 25 cc min-1) using air cylinder during 130hr (at 20° C and darkness condition). The CO2 emitted from the samples were carried to the

  14. Coordinate regulation of cytochrome and alternative pathway respiration in tobacco.

    Science.gov (United States)

    Vanlerberghe, G C; McIntosh, L

    1992-12-01

    In suspension cells of NT1 tobacco (Nicotiana tabacum L. cv bright yellow), inhibition of the cytochrome pathway of respiration with antimycin A induced a large increase in the capacity of the alternative pathway over a period of approximately 12 h, as confirmed in both whole cells and isolated mitochondria. The increase in alternative pathway capacity required de novo RNA and protein synthesis and correlated closely with the increase of a 35-kD alternative oxidase protein. When the cytochrome pathway of intact cells was inhibited by antimycin A, respiration proceeded exclusively through the alternative pathway, reached rates significantly higher than before antimycin A addition, and was not stimulated by p-trifluoromethoxycarbonylcyanide (FCCP). When inhibition of the cytochrome pathway was relieved, alternative pathway capacity and the level of the 35-kD alternative oxidase protein declined. Respiration rate also declined and could once again be stimulated by FCCP. These observations show that the capacities of the mitochondrial electron transport pathways can be regulated in a coordinate fashion.

  15. [Effects of antimicrobial drugs on soil microbial respiration].

    Science.gov (United States)

    Liu, Feng; Ying, Guang-Guo; Zhou, Qi-Xing; Tao, Ran; Su, Hao-Chang; Li, Xu

    2009-05-15

    The effects on soil microbial respiration of sulfonamides, tetracyclines, macrolides and so on were studied using the direct absorption method. The results show sulfamethazine, sulfamethoxazole, chlortetracycline, tetracycline, tylosin and trimethoprim inhibit soil respiration 34.33%, 34.43%, 2.71%, 3.08%, 7.13%, 38.08% respectively. Sulfamethoxazole and trimethoprim have the highest inhibition rates among all the antibiotics. In early incubation period (0-2 d), the concentrations above 10 mg x kg(-1) of sulfamethazine, sulfamethoxazole and trimethoprim remarkably decrease soil CO2 emission. The effects of these antibiotics vary with their concentrations too. Sulfamethoxazole and trimethoprim show good dose-response relationships. According to the standard of pesticide safety evaluation protocol, the six antibiotics pose a little risk to soil microbial environment.

  16. Annual ecosystem respiration budget for a Pinus sylvestris stand in central Siberia

    International Nuclear Information System (INIS)

    Shibistova, O.; Zrazhevskaya, G.; Astrakhantceva, N.; Shijneva, I.; Lloyd, J.; Arneth, A.; Kolle, J.; Knohl, A.; Schmerler, J.

    2002-01-01

    Using a ground-based and an above-canopy eddy covariance system in addition to stem respiration measurements, the annual respiratory fluxes attributable to soil, stems and foliage were determined for a Scots pine (Pinus sylvestris L.) forest growing in central Siberia. Night-time foliar respiration was estimated on the basis of the difference between fluxes measured below and above the canopy and the stem respiration measurements. Comparison of the effects of night-time turbulence on measured CO 2 fluxes showed flux loss above the canopy at low wind speeds, but no such effect was observed for the ground-based eddy system. This suggests that problems with flow homogeneity or flux divergence (both of which would be expected to be greater above the canopy than below) were responsible for above-canopy losses under these conditions. After correcting for this, a strong seasonality in foliar respiration was observed. This was not solely attributable to temperature variations, with intrinsic foliar respiratory capacities being much greater in spring and autumn. The opposite pattern was observed for stem respiration, with the intrinsic respiratory capacity being lower from autumn through early spring. Maximum respiratory activity was observed in early summer. This was not simply associated with a response to higher temperatures but seemed closely linked with cambial activity and the development of new xylem elements. Soil respiration rates exhibited an apparent high sensitivity to temperature, with seasonal data implying a Q 10 of about 7. We interpret this as reflecting covarying changes in soil microbial activity and soil temperatures throughout the snow-free season. Averaged over the two study years (1999 and 2000), the annual respiratory flux was estimated at 38.3 mol C/m 2 /a. Of this 0.61 was attributable to soil respiration, with stem respiration accounting for 0.21 and foliar respiration 0.18

  17. A Time-Frequency Respiration Tracking System using Non-Contact Bed Sensors with Harmonic Artifact Rejection

    Science.gov (United States)

    Beattie, Zachary T.; Jacobs, Peter G.; Riley, Thomas C.; Hagen, Chad C.

    2015-01-01

    Sleep apnea is a serious health condition that affects many individuals and has been associated with serious health conditions such as cardiovascular disease. Clinical diagnosis of sleep apnea requires that a patient spend the night in a sleep clinic while being wired up to numerous obtrusive sensors. We are developing a system that utilizes respiration rate and breathing amplitude inferred from non-contact bed sensors (i.e. load cells placed under bed supports) to detect sleep apnea. Multi-harmonic artifacts generated either biologically or as a result of the impulse response of the bed have made it challenging to track respiration rate and amplitude with high resolution in time. In this paper, we present an algorithm that can accurately track respiration on a second-by-second basis while removing noise harmonics. The algorithm is tested using data collected from 5 patients during overnight sleep studies. Respiration rate is compared with polysomnography estimations of respiration rate estimated by a technician following clinical standards. Results indicate that certain subjects exhibit a large harmonic component of their breathing signal that can be removed by our algorithm. When compared with technician transcribed respiration rates using polysomnography signals, we demonstrate improved accuracy of respiration rate tracking using harmonic artifact rejection (mean error: 0.18 breaths/minute) over tracking not using harmonic artifact rejection (mean error: −2.74 breaths/minute). PMID:26738176

  18. Dissipative dark matter halos: The steady state solution

    Science.gov (United States)

    Foot, R.

    2018-02-01

    Dissipative dark matter, where dark matter particle properties closely resemble familiar baryonic matter, is considered. Mirror dark matter, which arises from an isomorphic hidden sector, is a specific and theoretically constrained scenario. Other possibilities include models with more generic hidden sectors that contain massless dark photons [unbroken U (1 ) gauge interactions]. Such dark matter not only features dissipative cooling processes but also is assumed to have nontrivial heating sourced by ordinary supernovae (facilitated by the kinetic mixing interaction). The dynamics of dissipative dark matter halos around rotationally supported galaxies, influenced by heating as well as cooling processes, can be modeled by fluid equations. For a sufficiently isolated galaxy with a stable star formation rate, the dissipative dark matter halos are expected to evolve to a steady state configuration which is in hydrostatic equilibrium and where heating and cooling rates locally balance. Here, we take into account the major cooling and heating processes, and numerically solve for the steady state solution under the assumptions of spherical symmetry, negligible dark magnetic fields, and that supernova sourced energy is transported to the halo via dark radiation. For the parameters considered, and assumptions made, we were unable to find a physically realistic solution for the constrained case of mirror dark matter halos. Halo cooling generally exceeds heating at realistic halo mass densities. This problem can be rectified in more generic dissipative dark matter models, and we discuss a specific example in some detail.

  19. Resonant SIMP dark matter

    Directory of Open Access Journals (Sweden)

    Soo-Min Choi

    2016-07-01

    Full Text Available We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark U(1D. After the U(1D is broken down to a Z5 discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced 3→2 annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.

  20. Sterile neutrino dark matter

    CERN Document Server

    Merle, Alexander

    2017-01-01

    This book is a new look at one of the hottest topics in contemporary science, Dark Matter. It is the pioneering text dedicated to sterile neutrinos as candidate particles for Dark Matter, challenging some of the standard assumptions which may be true for some Dark Matter candidates but not for all. So, this can be seen either as an introduction to a specialized topic or an out-of-the-box introduction to the field of Dark Matter in general. No matter if you are a theoretical particle physicist, an observational astronomer, or a ground based experimentalist, no matter if you are a grad student or an active researcher, you can benefit from this text, for a simple reason: a non-standard candidate for Dark Matter can teach you a lot about what we truly know about our standard picture of how the Universe works.

  1. Macro Dark Matter

    CERN Document Server

    Jacobs, David M; Lynn, Bryan W.

    2015-01-01

    Dark matter is a vital component of the current best model of our universe, $\\Lambda$CDM. There are leading candidates for what the dark matter could be (e.g. weakly-interacting massive particles, or axions), but no compelling observational or experimental evidence exists to support these particular candidates, nor any beyond-the-Standard-Model physics that might produce such candidates. This suggests that other dark matter candidates, including ones that might arise in the Standard Model, should receive increased attention. Here we consider a general class of dark matter candidates with characteristic masses and interaction cross-sections characterized in units of grams and cm$^2$, respectively -- we therefore dub these macroscopic objects as Macros. Such dark matter candidates could potentially be assembled out of Standard Model particles (quarks and leptons) in the early universe. A combination of earth-based, astrophysical, and cosmological observations constrain a portion of the Macro parameter space; ho...

  2. Systemic response of Korean dark-striped field mice, Apodenmus agrarius coreae after high-dose- rate γ-irradiation: Organ weights, hemato-chemistry, apoptosis of splenocytes and sperm

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kwang Hee; Choi, Hoon; Joo, Hyun Jin; Kim, Hee Sun [Radiation Health Research Institute, KHNP, Gyeongju (Korea, Republic of); Keum, Dong Kwon [Nuclear Environment Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-11-15

    Since the territory of the radio-contaminated area is in homeogenous in radiation level and spectrum, investigation of the genetical mutation process in the natural animal populations inhabiting the radioontaminated areas will be provide a realistic picture of genetic effects for radiation exposure. However, little is known about the basic data such as systemic responses after ionizing radiation exposures in wild small rodents. Taking into account different radio-sensitivity of dark-striped field mice (A. a. coreae, THOMAS), the objective of the study is focus on investigate the level of systemic responses, included organ weights, hemato-chemistry and apoptosis in splenocytes and sperm of caudal epididymis after high-dose-rate irradiation especially as a potential biological dosimeter in radio-ecology. Figure 1 summarizes the results of the apoptotic events in spleen (data not shown at here) and in sperm of caudal epididymis at 24hrs after a single high-dose-rate γ-irradiation. The results of apoptosis in spleen and sperm caused by exposure to different doses of γ-irradiation are displayed. The data show that the field striped mice after irradiated with more than high dose of 0.5 Gy induces an significantly increased apoptosis. Results also shown that for exposure to 0.5 Gy, the apoptosis of both organs ware decreased compared to those of other γ-irradiated mice.

  3. Origin of ΔNeff as a result of an interaction between dark radiation and dark matter

    International Nuclear Information System (INIS)

    Bjaelde, Ole Eggers; Das, Subinoy; Moss, Adam

    2012-01-01

    Results from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology Telescope (ACT) and recently from the South Pole Telescope (SPT) have indicated the possible existence of an extra radiation component in addition to the well known three neutrino species predicted by the Standard Model of particle physics. In this paper, we explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decaying into dark radiation. At an early epoch when the dark matter density is negligible, as an obvious consequence, the density of dark radiation is also very small. As the Universe approaches matter radiation equality, the dark matter density starts to dominate thereby increasing the content of dark radiation and changing the expansion rate of the Universe. As this increase in dark radiation content happens naturally after Big Bang Nucleosynthesis (BBN), it can relax the possible tension with lower values of radiation degrees of freedom measured from light element abundances compared to that of the CMB. We numerically confront this scenario with WMAP+ACT and WMAP+SPT data and derive an upper limit on the allowed fraction of dark matter decaying into dark radiation

  4. Linear programming model can explain respiration of fermentation products

    Science.gov (United States)

    Möller, Philip; Liu, Xiaochen; Schuster, Stefan

    2018-01-01

    Many differentiated cells rely primarily on mitochondrial oxidative phosphorylation for generating energy in the form of ATP needed for cellular metabolism. In contrast most tumor cells instead rely on aerobic glycolysis leading to lactate to about the same extent as on respiration. Warburg found that cancer cells to support oxidative phosphorylation, tend to ferment glucose or other energy source into lactate even in the presence of sufficient oxygen, which is an inefficient way to generate ATP. This effect also occurs in striated muscle cells, activated lymphocytes and microglia, endothelial cells and several mammalian cell types, a phenomenon termed the “Warburg effect”. The effect is paradoxical at first glance because the ATP production rate of aerobic glycolysis is much slower than that of respiration and the energy demands are better to be met by pure oxidative phosphorylation. We tackle this question by building a minimal model including three combined reactions. The new aspect in extension to earlier models is that we take into account the possible uptake and oxidation of the fermentation products. We examine the case where the cell can allocate protein on several enzymes in a varying distribution and model this by a linear programming problem in which the objective is to maximize the ATP production rate under different combinations of constraints on enzymes. Depending on the cost of reactions and limitation of the substrates, this leads to pure respiration, pure fermentation, and a mixture of respiration and fermentation. The model predicts that fermentation products are only oxidized when glucose is scarce or its uptake is severely limited. PMID:29415045

  5. Linear programming model can explain respiration of fermentation products.

    Science.gov (United States)

    Möller, Philip; Liu, Xiaochen; Schuster, Stefan; Boley, Daniel

    2018-01-01

    Many differentiated cells rely primarily on mitochondrial oxidative phosphorylation for generating energy in the form of ATP needed for cellular metabolism. In contrast most tumor cells instead rely on aerobic glycolysis leading to lactate to about the same extent as on respiration. Warburg found that cancer cells to support oxidative phosphorylation, tend to ferment glucose or other energy source into lactate even in the presence of sufficient oxygen, which is an inefficient way to generate ATP. This effect also occurs in striated muscle cells, activated lymphocytes and microglia, endothelial cells and several mammalian cell types, a phenomenon termed the "Warburg effect". The effect is paradoxical at first glance because the ATP production rate of aerobic glycolysis is much slower than that of respiration and the energy demands are better to be met by pure oxidative phosphorylation. We tackle this question by building a minimal model including three combined reactions. The new aspect in extension to earlier models is that we take into account the possible uptake and oxidation of the fermentation products. We examine the case where the cell can allocate protein on several enzymes in a varying distribution and model this by a linear programming problem in which the objective is to maximize the ATP production rate under different combinations of constraints on enzymes. Depending on the cost of reactions and limitation of the substrates, this leads to pure respiration, pure fermentation, and a mixture of respiration and fermentation. The model predicts that fermentation products are only oxidized when glucose is scarce or its uptake is severely limited.

  6. Inter-relationships between light and respiration in the control of ascorbic acid synthesis and accumulation in Arabidopsis thaliana leaves.

    Science.gov (United States)

    Bartoli, Carlos G; Yu, Jianping; Gómez, Facundo; Fernández, Laura; McIntosh, Lee; Foyer, Christine H

    2006-01-01

    The effects of growth irradiance and respiration on ascorbic acid (AA) synthesis and accumulation were studied in the leaves of wild-type and transformed Arabidopsis thaliana with modified amounts of the mitochondrial alternative oxidase (AOX) protein. Plants were grown under low (LL; 50 micromol photons m(-2) s(-1)), intermediate (IL; 100 micromol photons m(-2) s(-1)), or high (HL; 250 micromol photons m(-2) s(-1)) light. Increasing growth irradiance progressively elevated leaf AA content and hence the values of dark-induced disappearance of leaf AA, which were 11, 55, and 89 nmol AA lost g(-1) fresh weight h(-1), from LL-, IL-, and HL-grown leaves, respectively. When HL leaves were supplied with L-galactone-1,4-lactone (L-GalL; the precursor of AA), they accumulated twice as much AA and had double the maximal L-galactone-1,4-lactone dehydrogenase (L-GalLDH) activities of LL leaves. Growth under HL enhanced dehydroascorbate reductase and monodehydroascorbate reductase activities. Leaf respiration rates were highest in the HL leaves, which also had higher amounts of cytochrome c and cytochrome c oxidase (CCO) activities, as well as enhanced capacity of the AOX and CCO electron transport pathways. Leaves of the AOX-overexpressing lines accumulated more AA than wild-type or antisense leaves, particularly at HL. Intact mitochondria from AOX-overexpressing lines had higher AA synthesis capacities than those from the wild-type or antisense lines even though they had similar L-GalLDH activities. AOX antisense lines had more cytochrome c protein than wild-type or AOX-overexpressing lines. It is concluded that regardless of limitations on L-GalL synthesis by regulation of early steps in the AA synthesis pathway, the regulation of L-GalLDH activity via the interaction of light and respiratory controls is a crucial determinant of the overall ability of leaves to produce and accumulate AA.

  7. Significance of cold-season respiration and photosynthesis in a subarctic heath ecosystem in Northern Sweden

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Ibrom, Andreas; Jonasson, S.

    2007-01-01

    While substantial cold-season respiration has been documented in most arctic and alpine ecosystems in recent years, the significance of cold-season photosynthesis in these biomes is still believed to be small. In a mesic, subartic heath during both the cold and warm season, we measured in situ...... ecosystem respiration and photosynthesis with a chamber technique at ambient conditions and at artificially, increased frequency of freeze-thaw (FT) cycles during fall and spring. We fitted the measured ecosystem exchange rates to respiration and photosynthesis models with R-2-values ranging from 0.81 to 0.......85. As expected, estimated cold-season (October, November, April and May) respiration was significant and accounted for at least 22% of the annual respiratory CO2 flux. More surprisingly, estimated photosynthesis during this period accounted for up to 19% of the annual gross CO2 uptake, suggesting that cold...

  8. Serendipity in dark photon searches

    Science.gov (United States)

    Ilten, Philip; Soreq, Yotam; Williams, Mike; Xue, Wei

    2018-06-01

    Searches for dark photons provide serendipitous discovery potential for other types of vector particles. We develop a framework for recasting dark photon searches to obtain constraints on more general theories, which includes a data-driven method for determining hadronic decay rates. We demonstrate our approach by deriving constraints on a vector that couples to the B-L current, a leptophobic B boson that couples directly to baryon number and to leptons via B- γ kinetic mixing, and on a vector that mediates a protophobic force. Our approach can easily be generalized to any massive gauge boson with vector couplings to the Standard Model fermions, and software to perform any such recasting is provided at https://gitlab.com/philten/darkcast https://gitlab.com/philten/darkcast" TargetType="URL"/> .

  9. Natural SUSY dark matter model

    International Nuclear Information System (INIS)

    Mohanty, Subhendra; Rao, Soumya; Roy, D.P.

    2013-01-01

    The most natural region of cosmologically compatible dark matter relic density in terms of low fine-tuning in a minimal supersymmetric standard model with nonuniversal gaugino masses is the so called bulk annihilation region. We study this region in a simple and predictive SUSY- GUT model of nonuniversal gaugino masses, where the latter transform as a combination of singlet plus a nonsinglet representation of the GUTgroup SU(5). The model prediction for the direct dark matter detection rates is well below the present CDMS and XENON100 limits, but within the reach of a future 1Ton XENON experiment. The most interesting and robust model prediction is an indirect detection signal of hard positron events, which resembles closely the shape of the observed positron spectrum from the PAMELA experiment. (author)

  10. Separating rhizosphere respiration from total soil respiration in two larch plantations in northeastern China.

    Science.gov (United States)

    Jiang, Lifen; Shi, Fuchen; Li, Bo; Luo, Yiqi; Chen, Jiquan; Chen, Jiakuan

    2005-09-01

    The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 micromol m(-2) s(-1) in winter to 6.0 micromol m(-2) s(-1) in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 micromol m(-2) s(-1) in the old forest and from 0.3 to 4.0 micromol m(-2) s(-1) in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.

  11. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean

    DEFF Research Database (Denmark)

    Ploug, H.; Grossart, HP; Azam, F.

    1999-01-01

    aggregate in darkness, which yielded a turnover time of 8 to 9 d for the total organic carbon in aggregates. Thus, marine snow is not only a vehicle for vertical flux of organic matter; the aggregates are also hotspots of microbial respiration which cause a fast and efficient respiratory turnover...... of particulate organic carbon in the sea....

  12. Dark matter: the astrophysical case

    International Nuclear Information System (INIS)

    Silk, J.

    2012-01-01

    The identification of dark matter is one of the most urgent problems in cosmology. I describe the astrophysical case for dark matter, from both an observational and a theoretical perspective. This overview will therefore focus on the observational motivations rather than the particle physics aspects of dark matter constraints on specific dark matter candidates. First, however, I summarize the astronomical evidence for dark matter, then I highlight the weaknesses of the standard cold dark matter model (LCDM) to provide a robust explanation of some observations. The greatest weakness in the dark matter saga is that we have not yet identified the nature of dark matter itself

  13. 42 CFR 84.134 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.134... Respirators § 84.134 Respirator containers; minimum requirements. Supplied-air respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type and...

  14. 42 CFR 84.197 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.197... Cartridge Respirators § 84.197 Respirator containers; minimum requirements. Respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type and...

  15. 42 CFR 84.174 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.174... Air-Purifying Particulate Respirators § 84.174 Respirator containers; minimum requirements. (a) Except..., durable container bearing markings which show the applicant's name, the type of respirator it contains...

  16. Respiration in heterotrophic unicellular eukaryotic organisms.

    Science.gov (United States)

    Fenchel, Tom

    2014-08-01

    Surface:volume quotient, mitochondrial volume fraction, and their distribution within cells were investigated and oxygen gradients within and outside cells were modelled. Cell surface increases allometrically with cell size. Mitochondrial volume fraction is invariant with cell size and constitutes about 10% and mitochondria are predominantly found close to the outer membrane. The results predict that for small and medium sized protozoa maximum respiration rates should be proportional to cell volume (scaling exponent ≈1) and access to intracellular O2 is not limiting except at very low ambient O2-tensions. Available data do not contradict this and some evidence supports this interpretation. Cell size is ultimately limited because an increasing fraction of the mitochondria becomes exposed to near anoxic conditions with increasing cell size. The fact that mitochondria cluster close to the cell surface and the allometric change in cell shape with increasing cell size alleviates the limitation of aerobic life at low ambient O2-tension and for large cell size. Copyright © 2014 Elsevier GmbH. All rights reserved.

  17. Forest harvesting effects on soil temperature, moisture, and respiration in a bottomland hardwood forest

    International Nuclear Information System (INIS)

    Londo, A.J.; Messina, M.G.; Schoenholtz, S.H.

    1999-01-01

    The effect of forest disturbance on C cycling has become an issue, given concerns about escalating atmospheric C content. The authors examined the effects of harvest intensity on in situ and laboratory mineral soil respiration in an East Texas bottomland hardwood forest between 6 and 22 mo after harvesting. Treatments included a clearcut, a partial cut wherein approximately 58% of the basal area was removed, and an unharvested control. The soda-lime absorption technique was used for in situ respiration (CO 2 efflux) and the wet alkali method (NaOH) was used for laboratory mineral soil respiration. Soil temperature and moisture content were also measured. Harvesting significantly increased in situ respiration during most sampling periods. This effect was attributed to an increase in live root and microflora activity associated with postharvesting revegetation. In situ respiration increased exponentially (Q 10 relationship) as treatment soil temperatures increased, but followed a parabolic-type pattern through the range of soil moisture measured (mean range 10.4--31.5%). Mean rates of laboratory mineral soil respiration measured during the study were unaffected by cutting treatment for most sampling sessions. Overall, the mean rate of CO 2 efflux in the clearcuts was significantly higher than that in the partial cuts, which in turn was significantly higher than that in the controls. Mass balance estimates indicate that these treatment differences will have little or no long-term effect on C sequestration of these managed forests

  18. Low-Mass Dark Matter Search with the DarkSide-50 Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P.; et al.

    2018-02-20

    We present the results of a search for dark matter WIMPs in the mass range below 20 GeV/c^2 using a target of low-radioactivity argon. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso (LNGS). The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 events/keVee/kg/day and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^2 for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^2.

  19. Soil respiration in typical plant communities in the wetland surrounding the high-salinity Ebinur Lake

    Science.gov (United States)

    Li, Yanhong; Zhao, Mingliang; Li, Fadong

    2018-03-01

    Soil respiration in wetlands surrounding lakes is a vital component of the soil carbon cycle in arid regions. However, information remains limited on the soil respiration around highly saline lakes during the plant growing season. Here, we aimed to evaluate diurnal and seasonal variation in soil respiration to elucidate the controlling factors in the wetland of Ebinur Lake, Xinjiang Uygur Autonomous Region, western China. We used a soil carbon flux automatic analyzer (LI-840A) to measure soil respiration rates during the growing season (April to November) in two fields covered by reeds and tamarisk and one field with no vegetation (bare soil) from 2015 to 2016. The results showed a single peak in the diurnal pattern of soil respiration from 11:00 to 17:00 for plots covered in reeds, tamarisk, and bare soil, with minimum values being detected from 03:00 to 07:00. During the growing season, the soil respiration of reeds and tamarisk peaked during the thriving period (4.16 and 3.75 mmol•m-2•s-1, respectively), while that of bare soil peaked during the intermediate growth period (0.74 mmol•m-2•s-1). The soil respiration in all three plots was lowest during the wintering period (0.08, 0.09, and-0.87 mmol•m-2•s-1, respectively). Air temperature and relative humidity significantly influenced soil respiration. A significant linear relationship was detected between soil respiration and soil temperature for reeds, tamarisk, and bare soil. The average Q10 of reeds and tamarisk were larger than that of bare soil. However, soil moisture content was not the main factor controlling soil respiration. Soil respiration was negatively correlated with soil pH and soil salinity in all three plot types. In contrast, soil respiration was positively correlated with organic carbon. Overall, CO2 emissions and greenhouse gases had a relatively weak effect on the wetlands surrounding the highly saline Ebinur Lake.

  20. [A comparative study on soil respiration between grazing and fenced typical Leymus chinensis steppe, Inner Mongolia].

    Science.gov (United States)

    Jia, Bingrui; Zhou, Guangsheng; Wang, Fengyu; Wang, Yuhui

    2004-09-01

    With enclosed chamber Method, this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes, Inner Mongolia, and its relationships with environmental factors. The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve, and the highest values appeared at 13:00-15:00 in the fenced and grazing plots. The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots. In June and July, the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots, while the difference was not distinct in August and September, which was similar with the change of the belowground biomass. The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors. It showed that human activity may not result in the increase of soil respiration rate. The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0-10 cm depth at the fenced and grazing sites, and the maximum R2 was 0.853 and 0.741, respectively. The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots. The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.

  1. Respiration of Nitrate and Nitrite.

    Science.gov (United States)

    Cole, Jeffrey A; Richardson, David J

    2008-09-01

    Nitrate reduction to ammonia via nitrite occurs widely as an anabolic process through which bacteria, archaea, and plants can assimilate nitrate into cellular biomass. Escherichia coli and related enteric bacteria can couple the eight-electron reduction of nitrate to ammonium to growth by coupling the nitrate and nitrite reductases involved to energy-conserving respiratory electron transport systems. In global terms, the respiratory reduction of nitrate to ammonium dominates nitrate and nitrite reduction in many electron-rich environments such as anoxic marine sediments and sulfide-rich thermal vents, the human gastrointestinal tract, and the bodies of warm-blooded animals. This review reviews the regulation and enzymology of this process in E. coli and, where relevant detail is available, also in Salmonella and draws comparisons with and implications for the process in other bacteria where it is pertinent to do so. Fatty acids may be present in high levels in many of the natural environments of E. coli and Salmonella in which oxygen is limited but nitrate is available to support respiration. In E. coli, nitrate reduction in the periplasm involves the products of two seven-gene operons, napFDAGHBC, encoding the periplasmic nitrate reductase, and nrfABCDEFG, encoding the periplasmic nitrite reductase. No bacterium has yet been shown to couple a periplasmic nitrate reductase solely to the cytoplasmic nitrite reductase NirB. The cytoplasmic pathway for nitrate reduction to ammonia is restricted almost exclusively to a few groups of facultative anaerobic bacteria that encounter high concentrations of environmental nitrate.

  2. Review on Dark Photon

    Directory of Open Access Journals (Sweden)

    Curciarello Francesca

    2016-01-01

    Full Text Available e+e− collider experiments at the intensity frontier are naturally suited to probe the existence of a force beyond the Standard Model between WIMPs, the most viable dark matter candidates. The mediator of this new force, known as dark photon, should be a new vector gauge boson very weakly coupled to the Standard Model photon. No significant signal has been observed so far. I will report on current limits set on the coupling factor ε2 between the photon and the dark photon by e+e− collider experiments.

  3. Working the Dark Side

    DEFF Research Database (Denmark)

    Bjering, Jens Christian Borrebye

    A few days after the terror attacks of 9/11, then Vice President Dick Cheney appeared on television with a call for “working the dark side.” While still unclear what this expression entailed at the time, Cheney's comment appears in retrospect to almost have been prophetic for the years to come....... By analyzing official reports and testimonies from soldiers partaking in the War On Terror, the dissertation's second part—dark arts—focuses on the transformation of the dark side into a productive space in which “information” and the hunt for said information overshadowed all legal, ethical, or political...

  4. Films and dark room

    International Nuclear Information System (INIS)

    Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail

    2008-01-01

    After we know where the radiographic come from, then we must know about the film and also dark room. So, this chapter 5 discusses the two main components for radiography work that is film and dark room, places to process the film. Film are structured with three structured that are basic structured, emulsion and protection structured. So, this film can be classified either with their speed, screen and standard that used. The process to wash the film must be done in dark room otherwise the radiographer cannot get what are they inspected. The processing of film will be discussed briefly in next chapter.

  5. Auschwitz dark tourism -kohteena

    OpenAIRE

    Kuusimäki, Karita

    2015-01-01

    Dark tourism eli synkkä matkailu on matkustamista kohteisiin, jotka liittyvät jollain tavalla kuolemaan, kauhuun, kärsimykseen tai katastrofeihin. Dark tourism on ilmiönä suhteellisen tuore, mutta sen historia juontaa juurensa jo antiikin ajan gladiaattoritaisteluihin. Ilmiötä on tutkittu jonkin verran ja siitä on tehty muutamia opinnäytetöitä. Yksi tunnetuimmista ja eniten vierailluista dark tourism -kohteista on Auschwitzin keskitysleiri. Auschwitz aloitti toimintansa vuonna 1940 ja le...

  6. Diffusive boundary layers, photosynthesis, and respiration of the colony-forming plankton algae, Phaeocystis sp

    DEFF Research Database (Denmark)

    Ploug, Helle; Stolte, W.; Epping, E.H.G.

    1999-01-01

    H increased up to 0.4 units when measured in light at saturating intensities (>90 mu mol photons m(-2) s(-1)). The respiration in the dark was low, resulting in a 6% lowering in oxygen concentration and 0.04 units lowering in pH inside colonies, compared to the bulk water phase. Such colonies were net...... heterotrophic communities at light intensities up to 10 mu mol photons m(-2) s(-1). A week later, colonies were net heterotrophic at light intensities up to 80 mu mol photons m(-2) s(-1). The effective diffusion coefficient for oxygen in the gelatinous colonies was not significantly different from that in sea......Diffusive boundary layers, photosynthesis, and respiration in Phaeocystis colonies were studied by the use of microelectrodes for oxygen and pH during a bloom in the Barents Sea, 1993, and in the Marsdiep, Dutch North Sea, 1994. The oxygen microenvironment of a Phaeocystis colony with a mean...

  7. Betaine is a positive regulator of mitochondrial respiration

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Icksoo, E-mail: icksoolee@dankook.ac.kr

    2015-01-09

    Highlights: • Betaine enhances cytochrome c oxidase activity and mitochondrial respiration. • Betaine increases mitochondrial membrane potential and cellular energy levels. • Betaine’s anti-tumorigenic effect might be due to a reversal of the Warburg effect. - Abstract: Betaine protects cells from environmental stress and serves as a methyl donor in several biochemical pathways. It reduces cardiovascular disease risk and protects liver cells from alcoholic liver damage and nonalcoholic steatohepatitis. Its pretreatment can rescue cells exposed to toxins such as rotenone, chloroform, and LiCl. Furthermore, it has been suggested that betaine can suppress cancer cell growth in vivo and in vitro. Mitochondrial electron transport chain (ETC) complexes generate the mitochondrial membrane potential, which is essential to produce cellular energy, ATP. Reduced mitochondrial respiration and energy status have been found in many human pathological conditions including aging, cancer, and neurodegenerative disease. In this study we investigated whether betaine directly targets mitochondria. We show that betaine treatment leads to an upregulation of mitochondrial respiration and cytochrome c oxidase activity in H2.35 cells, the proposed rate limiting enzyme of ETC in vivo. Following treatment, the mitochondrial membrane potential was increased and cellular energy levels were elevated. We propose that the anti-proliferative effects of betaine on cancer cells might be due to enhanced mitochondrial function contributing to a reversal of the Warburg effect.

  8. Cisplatin cytotoxicity is dependent on mitochondrial respiration in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Santhipriya Inapurapu

    2017-01-01

    Full Text Available Objective(s: To understand the role of mitochondrial respiration in cisplatin sensitivity, we have employed wild-type and mitochondrial DNA depleted Rho0 yeast cells. Materials and Methods: Wild type and Rho0 yeast cultured in fermentable and non-fermentable sugar containing media, were studied for their sensitivity against cisplatin by monitoring growth curves, oxygen consumption, pH changes in cytosol/mitochondrial compartments, reactive oxygen species production and respiratory control ratio. Results: Wild-type yeast grown on glycerol exhibited heightened sensitivity to cisplatin than yeast grown on glucose. Cisplatin (100 μM, although significantly reduced the growth of wild- type cells, only slightly altered the growth rate of Rho0 cells. Cisplatin treatment decreased both pHcyt and pHmit to a similar extent without affecting the pH difference. Cisplatin dose-dependently increased the oxidative stress in wild-type, but not in respiration-deficient Rho0 strain. Cisplatin decreased the respiratory control ratio. Conclusion: These results suggest that cisplatin toxicity is influenced by the respiratory capacity of the cells and the intracellular oxidative burden. Although cisplatin per se slightly decreased the respiration of yeast cells grown in glucose, it did not disturb the mitochondrial chemiosmotic gradient.

  9. A dynamic soil chamber system coupled with a tunable diode laser for online measurements of delta-13C, delta-18O, and efflux rate of soil respired CO2

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Heath H [Los Alamos National Laboratory; Mcdowell, Nate [Los Alamos National Laboratory; Hanson, David [UNM; Hunt, John [LANDCARE RESEARCH

    2009-01-01

    High frequency observations of the stable isotopic composition of CO(2) effluxes from soil have been sparse due in part to measurement challenges. We have developed an open-system method that utilizes a flow-through chamber coupled to a tunable diode laser (TDL) to quantify the rate of soil CO(2) efflux and its delta(13)C and delta(18)O values (delta(13)C(R) and delta(18)O(R), respectively). We tested the method first in the laboratory using an artificial soil test column and then in a semi-arid woodland. We found that the CO(2) efflux rates of 1.2 to 7.3 micromol m(-2) s(-1) measured by the chamber-TDL system were similar to measurements made using the chamber and an infrared gas analyzer (IRGA) (R(2) = 0.99) and compared well with efflux rates generated from the soil test column (R(2) = 0.94). Measured delta(13)C and delta(18)O values of CO(2) efflux using the chamber-TDL system at 2 min intervals were not significantly different from source air values across all efflux rates after accounting for diffusive enrichment. Field measurements during drought demonstrated a strong dependency of CO(2) efflux and isotopic composition on soil water content. Addition of water to the soil beneath the chamber resulted in average changes of +6.9 micromol m(-2) s(-1), -5.0 per thousand, and -55.0 per thousand for soil CO(2) efflux, delta(13)C(R) and delta(18)O(R), respectively. All three variables initiated responses within 2 min of water addition, with peak responses observed within 10 min for isotopes and 20 min for efflux. The observed delta(18)O(R) was more enriched than predicted from temperature-dependent H(2)O-CO(2) equilibration theory, similar to other recent observations of delta(18)O(R) from dry soils (Wingate L, Seibt U, Maseyk K, Ogee J, Almeida P, Yakir D, Pereira JS, Mencuccini M. Global Change Biol. 2008; 14: 2178). The soil chamber coupled with the TDL was found to be an effective method for capturing soil CO(2) efflux and its stable isotope composition at high

  10. Soil Respiration And Respiration Partitioning In An Oak-Savannah With A History Of Fertilization

    Science.gov (United States)

    Morris, K. A.; Nair, R.; Schrumpf, M.; Migliavacca, M.

    2017-12-01

    Soil respiration is a combination of autotrophic and heterotrophic components. These components have different controls and structurally complex ecosystems such as oak-savannahs offer an opportunity to study strongly contrasting conditions (ie., soil from under trees versus open areas) in an environment with similar soil mineralogy and climatic patterns. To measure respiration coming from plant roots, fungal hyphae, and free-living microbes we established stations of soil cores comprised of three selectively permeable meshes under tree canopies and in open grassy areas of a Holm Oak (Quercus ilex) savannah in Extremadura, Spain. Large plots of this ecosystem had previously been fertilized as part of a stoichiometeric imbalance study (in 2015). Stations were installed in Dec. 2016 within four plots; control, N added, P added, and N+P added. Respiration from cores was measured in campaigns at key phenological stages with a portable Li-Cor 8100A unit. Six months after installation > 50% of soil respiration was attributable to free-living microbes. There is a persistent effect of the prior fertilization, resulting in increased soil respiration in open areas regardless of fertilizer type, while respiration from under tree canopies had a varied response. Soil under tree canopies showed distinct sensitivity to stoichiometric imbalance, meaning that addition of N or P alone either did not change respiration or decreased it slightly, while N+P stimulated respiration. We determined that respiration from free-living microbes is a major component of soil respiration even in the most active plant growing season. However, because of the lag between the time of fertilization and the time of measurement, it not possible to say whether treatment responses are due solely to nutrient status of the soil or whether changes in plant biomass and species composition also play a role. Additional work planned at the site will shed light on this uncertainty as well as the contribution of

  11. [Research progress on photosynthesis regulating and controlling soil respiration].

    Science.gov (United States)

    Jing, Yan-Li; Guan, De-Xin; Wu, Jia-Bing; Wang, An-Zhi; Yuan, Feng-Hui

    2013-01-01

    To understand the mechanisms of soil respiration and accurately estimate its magnitude are the crucial basis of evaluating global carbon balance. However, the previously built soil respiration forecast models usually neglect the physiological processes that photosynthesis supplies substrates for rhizospheric respiration, leading to the defect in evaluating the mechanisms of soil respiration. This paper summarized the research progress on the mechanisms of photosynthetic regulation and control of soil respiration, introduced the related main research methods, and discussed the existing problems and research hotspots.

  12. Cold dark matter plus not-so-clumpy dark relics

    NARCIS (Netherlands)

    Diamanti, R.; Ando, S.; Gariazzo, S.; Mena, O.; Weniger, C.

    Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark

  13. Inflation, Dark Matter, and Dark Energy in the String Landscape

    OpenAIRE

    Liddle, Andrew R; Ureña-López, L Arturo

    2006-01-01

    We consider the conditions needed to unify the description of dark matter, dark energy and inflation in the context of the string landscape. We find that incomplete decay of the inflaton field gives the possibility that a single field is responsible for all three phenomena. By contrast, unifying dark matter and dark energy into a single field, separate from the inflaton, appears rather difficult.

  14. Evidence for dark matter interactions in cosmological precision data?

    International Nuclear Information System (INIS)

    Lesgourgues, Julien; Marques-Tavares, Gustavo; Schmaltz, Martin

    2016-01-01

    We study a two-parameter extension of the cosmological standard model ΛCDM in which cold dark matter interacts with a new form of dark radiation. The two parameters correspond to the energy density in the dark radiation fluid ΔN fluid and the interaction strength between dark matter and dark radiation. The interactions give rise to a very weak ''dark matter drag'' which damps the growth of matter density perturbations throughout radiation domination, allowing to reconcile the tension between predictions of large scale structure from the CMB and direct measurements of σ 8 . We perform a precision fit to Planck CMB data, BAO, large scale structure, and direct measurements of the expansion rate of the universe today. Our model lowers the χ-squared relative to ΛCDM by about 12, corresponding to a preference for non-zero dark matter drag by more than 3σ. Particle physics models which naturally produce a dark matter drag of the required form include the recently proposed non-Abelian dark matter model in which the dark radiation corresponds to massless dark gluons

  15. Short Communication: HIV Patient Systemic Mitochondrial Respiration Improves with Exercise.

    Science.gov (United States)

    Kocher, Morgan; McDermott, Mindy; Lindsey, Rachel; Shikuma, Cecilia M; Gerschenson, Mariana; Chow, Dominic C; Kohorn, Lindsay B; Hetzler, Ronald K; Kimura, Iris F

    2017-10-01

    In HIV-infected individuals, impaired mitochondrial function may contribute to cardiometabolic disease as well as to fatigue and frailty. Aerobic exercise improves total body energy reserves; however, its impact at the cellular level is unknown. We assessed alterations in cellular bioenergetics in peripheral blood mononuclear cells (PBMC) before and after a 12-week aerobic exercise study in sedentary HIV-infected subjects on stable antiretroviral therapy who successfully completed a 12-week aerobic exercise program. In this prospective study, participants underwent supervised 20-40 min of light aerobic exercise (walking or jogging) performed three times per week for 12 weeks, gradually increasing to maintain an intensity of 50%-80% of heart rate reserve. Maximal aerobic capacity (VO 2MAX ) was assessed by a graded exercise test on a cycle ergometer before and after completion of the study. PBMC from compliant subjects (attended at least 70% of exercise sessions) were assessed for mitochondrial respiration using the Seahorse XF24 Bio-Analyzer. Seven of 24 enrolled subjects were compliant with the exercise regimen. In these individuals, a significant increase (p = .04) in VO 2MAX over 12 weeks was found with a median increase of 14%. During the same interval, a 2.45-fold increase in PBMC mitochondrial respiratory capacity (p = .04), a 5.65-fold increase in spare respiratory capacity (p = .01), and a 3.15-fold (p = .04) increase in nonmitochondrial respiration was observed. Aerobic exercise improves respiration at the cellular level. The diagnostic and prognostic value of such improved cellular respiration in the setting of chronic HIV warrants further investigation.

  16. Impacts of temperature on primary productivity and respiration in naturally structured macroalgal assemblages.

    Directory of Open Access Journals (Sweden)

    Leigh W Tait

    Full Text Available Rising global temperatures caused by human-mediated change has already triggered significant responses in organismal physiology, distribution and ecosystem functioning. Although the effects of rising temperature on the physiology of individual organisms are well understood, the effect on community-wide processes has remained elusive. The fixation of carbon via primary productivity is an essential ecosystem function and any shifts in the balance of primary productivity and respiration could alter the carbon balance of ecosystems. Here we show through a series of tests that respiration of naturally structured algal assemblages in southern New Zealand greatly increases with rising temperature, with implications for net primary productivity (NPP. The NPP of in situ macroalgal assemblages was minimally affected by natural temperature variation, possibly through photo-acclimation or temperature acclimation responses, but respiration rates and compensating irradiance were negatively affected. However, laboratory experiments testing the impacts of rising temperature on several photosynthetic parameters showed a decline in NPP, increasing respiration rates and increasing compensating irradiance. The respiration Q10 of laboratory assemblages (the difference in metabolic rates over 10°C averaged 2.9 compared to a Q10 of 2 often seen in other autotrophs. However, gross primary productivity (GPP Q10 averaged 2, indicating that respiration was more severely affected by rising temperature. Furthermore, combined high irradiance and high temperature caused photoinhibition in the laboratory, and resulted in 50% lower NPP at high irradiance. Our study shows that communities may be more severely affected by rising global temperatures than would be expected by responses of individual species. In particular, enhanced respiration rates and rising compensation points have the potential to greatly affect the carbon balance of macroalgal assemblages through declines in

  17. Little composite dark matter.

    Science.gov (United States)

    Balkin, Reuven; Perez, Gilad; Weiler, Andreas

    2018-01-01

    We examine the dark matter phenomenology of a composite electroweak singlet state. This singlet belongs to the Goldstone sector of a well-motivated extension of the Littlest Higgs with T -parity. A viable parameter space, consistent with the observed dark matter relic abundance as well as with the various collider, electroweak precision and dark matter direct detection experimental constraints is found for this scenario. T -parity implies a rich LHC phenomenology, which forms an interesting interplay between conventional natural SUSY type of signals involving third generation quarks and missing energy, from stop-like particle production and decay, and composite Higgs type of signals involving third generation quarks associated with Higgs and electroweak gauge boson, from vector-like top-partners production and decay. The composite features of the dark matter phenomenology allows the composite singlet to produce the correct relic abundance while interacting weakly with the Higgs via the usual Higgs portal coupling [Formula: see text], thus evading direct detection.

  18. Inflatable Dark Matter.

    Science.gov (United States)

    Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D

    2016-01-22

    We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ∼MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.

  19. Dark matter search

    International Nuclear Information System (INIS)

    Bernabei, R.

    2003-01-01

    Some general arguments on the particle Dark Matter search are addressed. The WIMP direct detection technique is mainly considered and recent results obtained by exploiting the annual modulation signature are summarized. (author)

  20. Baryonic dark matter

    International Nuclear Information System (INIS)

    Uson, Juan M.

    2000-01-01

    Many searches for baryonic dark matter have been conducted but, so far, all have been unsuccessful. Indeed, no more than 1% of the dark matter can be in the form of hydrogen burning stars. It has recently been suggested that most of the baryons in the universe are still in the form of ionized gas so that it is possible that there is no baryonic dark matter. Although it is likely that a significant fraction of the dark matter in the Milky Way is in a halo of non-baryonic matter, the data do not exclude the possibility that a considerable amount, perhaps most of it, could be in a tenuous halo of diffuse ionized gas

  1. Lectures on dark matter

    International Nuclear Information System (INIS)

    Seljak, U.

    2001-01-01

    These lectures concentrate on evolution and generation of dark matter perturbations. The purpose of the lectures is to present, in a systematic way, a comprehensive review of the cosmological parameters that can lead to observable effects in the dark matter clustering properties. We begin by reviewing the relativistic linear perturbation theory formalism. We discuss the gauge issue and derive Einstein's and continuity equations for several popular gauge choices. We continue by developing fluid equations for cold dark matter and baryons and Boltzmann equations for photons, massive and massless neutrinos. We then discuss the generation of initial perturbations by the process of inflation and the parameters of that process that can be extracted from the observations. Finally we discuss evolution of perturbations in various regimes and the imprint of the evolution on the dark matter power spectrum both in the linear and in the nonlinear regime. (author)

  2. Lectures on dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Seljak, U [Department of Physics, Princeton University, Princeton, NJ (United States)

    2001-11-15

    These lectures concentrate on evolution and generation of dark matter perturbations. The purpose of the lectures is to present, in a systematic way, a comprehensive review of the cosmological parameters that can lead to observable effects in the dark matter clustering properties. We begin by reviewing the relativistic linear perturbation theory formalism. We discuss the gauge issue and derive Einstein's and continuity equations for several popular gauge choices. We continue by developing fluid equations for cold dark matter and baryons and Boltzmann equations for photons, massive and massless neutrinos. We then discuss the generation of initial perturbations by the process of inflation and the parameters of that process that can be extracted from the observations. Finally we discuss evolution of perturbations in various regimes and the imprint of the evolution on the dark matter power spectrum both in the linear and in the nonlinear regime. (author)

  3. Dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Bernabei, R [Dipto. di Fisica, Universita di Roma ' Tor Vergata' and INFN, sez. Roma2, Rome (Italy)

    2003-08-15

    Some general arguments on the particle Dark Matter search are addressed. The WIMP direct detection technique is mainly considered and recent results obtained by exploiting the annual modulation signature are summarized. (author)

  4. Astronomical Signatures of Dark Matter

    Directory of Open Access Journals (Sweden)

    Paul Gorenstein

    2014-01-01

    Full Text Available Several independent astronomical observations in different wavelength bands reveal the existence of much larger quantities of matter than what we would deduce from assuming a solar mass to light ratio. They are very high velocities of individual galaxies within clusters of galaxies, higher than expected rotation rates of stars in the outer regions of galaxies, 21 cm line studies indicative of increasing mass to light ratios with radius in the halos of spiral galaxies, hot gaseous X-ray emitting halos around many elliptical galaxies, and clusters of galaxies requiring a much larger component of unseen mass for the hot gas to be bound. The level of gravitational attraction needed for the spatial distribution of galaxies to evolve from the small perturbations implied by the very slightly anisotropic cosmic microwave background radiation to its current web-like configuration requires much more mass than is observed across the entire electromagnetic spectrum. Distorted shapes of galaxies and other features created by gravitational lensing in the images of many astronomical objects require an amount of dark matter consistent with other estimates. The unambiguous detection of dark matter and more recently evidence for dark energy has positioned astronomy at the frontier of fundamental physics as it was in the 17th century.

  5. Dark gamma-ray bursts

    Science.gov (United States)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p -wave process than for s -wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to standard model particles later, the annihilation burst results in a flash of gamma rays accompanying the supernova. For a galactic supernova, this "dark gamma-ray burst" may be observable in the Čerenkov Telescope Array.

  6. Gravity's dark side: Doing without dark matte

    International Nuclear Information System (INIS)

    Chalmers, M.

    2006-01-01

    Despite decades of searching, the 'dark matter' thought to hold galaxies together is still nowhere to be found. Matthew Chalmers describes how some physicists think it makes more sense to change our theory of gravity instead. Einstein's general theory of relativity is part of the bedrock of modern physics. It describes in elegant mathematical terms how matter causes space-time to curve, and therefore how objects move in a gravitational field. Since it was published in 1916, general relativity has passed every test asked of it with flying colours, and to many physicists the notion that it is wrong is sacrilege. But the motivation for developing an alternative theory of gravity is compelling. Over the last few years cosmologists have arrived at a simple yet extraordinarily successful model of universe. The trouble is that it requires most of the cosmos to be filled with mysterious stuff that we cannot see. In particular, general relativity - or rather its non-relativistic limit otherwise known as Newtonian gravity - can only correctly describe the dynamics of galaxies if we invoke huge quantities of 'dark matter'. Furthermore, an exotic entity called dark energy is necessary to account for the recent discovery that the expansion of the universe is accelerating. Indeed, in the standard model of cosmology, visible matter such as stars, planets and physics textbooks accounts for just 4% of the total universe. (U.K.)

  7. Dark matter universe

    Science.gov (United States)

    Bahcall, Neta A.

    2015-01-01

    Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle. PMID:26417091

  8. Dark matter universe.

    Science.gov (United States)

    Bahcall, Neta A

    2015-10-06

    Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

  9. Oxygen dependence of respiration in rat spinotrapezius muscle in situ

    Science.gov (United States)

    Pittman, Roland N.

    2012-01-01

    The oxygen dependence of respiration in striated muscle in situ was studied by measuring the rate of decrease of interstitial Po2 [oxygen disappearance curve (ODC)] following rapid arrest of blood flow by pneumatic tissue compression, which ejected red blood cells from the muscle vessels and made the ODC independent from oxygen bound to hemoglobin. After the contribution of photo-consumption of oxygen by the method was evaluated and accounted for, the corrected ODCs were converted into the Po2 dependence of oxygen consumption, V̇o2, proportional to the rate of Po2 decrease. Fitting equations obtained from a model of heterogeneous intracellular Po2 were applied to recover the parameters describing respiration in muscle fibers, with a predicted sigmoidal shape for the dependence of V̇o2 on Po2. This curve consists of two regions connected by the point for critical Po2 of the cell (i.e., Po2 at the sarcolemma when the center of the cell becomes anoxic). The critical Po2 was below the Po2 for half-maximal respiratory rate (P50) for the cells. In six muscles at rest, the rate of oxygen consumption was 139 ± 6 nl O2/cm3·s and mitochondrial P50 was k = 10.5 ± 0.8 mmHg. The range of Po2 values inside the muscle fibers was found to be 4–5 mmHg at the critical Po2. The oxygen dependence of respiration can be studied in thin muscles under different experimental conditions. In resting muscle, the critical Po2 was substantially lower than the interstitial Po2 of 53 ± 2 mmHg, a finding that indicates that V̇o2 under this circumstance is independent of oxygen supply and is discordant with the conventional hypothesis of metabolic regulation of the oxygen supply to tissue. PMID:22523254

  10. Plankton community respiration, net ecosystem metabolism, and oxygen dynamics on the Louisiana continental shelf: implications for hypoxia

    Science.gov (United States)

    We conducted a multi-year study of the Louisiana continental shelf (LCS) to better understand the linkages between water column metabolism and the formation of hypoxia (dissolved oxygen respiration rates (WR) were measured on 10 cr...

  11. Dark matter: Theoretical perspectives

    International Nuclear Information System (INIS)

    Turner, M.S.

    1993-01-01

    The author both reviews and makes the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that (i) there are no dark-matter candidates within the open-quotes standard modelclose quotes of particle physics, (ii) there are several compelling candidates within attractive extensions of the standard model of particle physics, and (iii) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for open-quotes new physics.close quotes The compelling candidates are a very light axion (10 -6 --10 -4 eV), a light neutrino (20--90 eV), and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. The author briefly mentions more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos. 119 refs

  12. Dark matter: Theoretical perspectives

    International Nuclear Information System (INIS)

    Turner, M.S.

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ''new physics.'' The compelling candidates are: a very light axion ( 10 -6 eV--10 -4 eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos

  13. Dark matter: Theoretical perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Turner, M.S. (Chicago Univ., IL (United States). Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL (United States))

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for new physics.'' The compelling candidates are: a very light axion ( 10[sup [minus]6] eV--10[sup [minus]4] eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  14. Dark matter: Theoretical perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)

    1993-01-01

    I both review and make the case for the current theoretical prejudice: a flat Universe whose dominant constituent is nonbaryonic dark matter, emphasizing that this is still a prejudice and not yet fact. The theoretical motivation for nonbaryonic dark matter is discussed in the context of current elementary-particle theory, stressing that: (1) there are no dark matter candidates within the standard model of particle physics; (2) there are several compelling candidates within attractive extensions of the standard model of particle physics; and (3) the motivation for these compelling candidates comes first and foremost from particle physics. The dark-matter problem is now a pressing issue in both cosmology and particle physics, and the detection of particle dark matter would provide evidence for ``new physics.`` The compelling candidates are: a very light axion ( 10{sup {minus}6} eV--10{sup {minus}4} eV); a light neutrino (20 eV--90 eV); and a heavy neutralino (10 GeV--2 TeV). The production of these particles in the early Universe and the prospects for their detection are also discussed. I briefly mention more exotic possibilities for the dark matter, including a nonzero cosmological constant, superheavy magnetic monopoles, and decaying neutrinos.

  15. Flexible Coupling of Respiration and Vocalizations with Locomotion and Head Movements in the Freely Behaving Rat

    Directory of Open Access Journals (Sweden)

    Joseph Andrews Alves

    2016-01-01

    Full Text Available Quadrupedal mammals typically synchronize their respiration with body movements during rhythmic locomotion. In the rat, fast respiration is coupled to head movements during sniffing behavior, but whether respiration is entrained by stride dynamics is not known. We recorded intranasal pressure, head acceleration, instantaneous speed, and ultrasonic vocalizations from male and female adult rats while freely behaving in a social environment. We used high-speed video recordings of stride to understand how head acceleration signals relate to locomotion and developed techniques to identify episodes of sniffing, walking, trotting, and galloping from the recorded variables. Quantitative analysis of synchrony between respiration and head acceleration rhythms revealed that respiration and locomotion movements were coordinated but with a weaker coupling than expected from previous work in other mammals. We have recently shown that rats behaving in social settings produce high rates of ultrasonic vocalizations during locomotion bouts. Accordingly, rats emitted vocalizations in over half of the respiratory cycles during fast displacements. We present evidence suggesting that emission of these calls disrupts the entrainment of respiration by stride. The coupling between these two variables is thus flexible, such that it can be overridden by other behavioral demands.

  16. Temperature dependence of bulk respiration of crop stands. Measurement and model fitting

    International Nuclear Information System (INIS)

    Tani, Takashi; Arai, Ryuji; Tako, Yasuhiro

    2007-01-01

    The objective of the present study was to examine whether the temperature dependence of respiration at a crop-stand scale could be directly represented by an Arrhenius function that was widely used for representing the temperature dependence of leaf respiration. We determined temperature dependences of bulk respiration of monospecific stands of rice and soybean within a range of the air temperature from 15 to 30degC using large closed chambers. Measured responses of respiration rates of the two stands were well fitted by the Arrhenius function (R 2 =0.99). In the existing model to assess the local radiological impact of the anthropogenic carbon-14, effects of the physical environmental factors on photosynthesis and respiration of crop stands are not taken into account for the calculation of the net amount of carbon per cultivation area in crops at harvest which is the crucial parameter for the estimation of the activity concentration of carbon-14 in crops. Our result indicates that the Arrhenius function is useful for incorporating the effect of the temperature on respiration of crop stands into the model which is expected to contribute to a more realistic estimate of the activity concentration of carbon-14 in crops. (author)

  17. Ecosystem warming does not affect photosynthesis or aboveground autotrophic respiration for boreal black spruce

    Energy Technology Data Exchange (ETDEWEB)

    Bronson, D.R. [Wyoming Univ., Laramie, WY (United States). Dept. of Renewable Resources; Gower, S.T. [Wisconsin Univ., Madison, WI (United States). Dept. of Forest Ecology and Management

    2010-04-15

    Substantial increases in climatic temperatures may cause boreal forests to become a carbon source. An improved understanding of the effect of climatic warming on photosynthesis and autotrophic respiration is needed in order to determine the impact of temperature increases on net carbon balances. This study measured the light-saturated photosynthesis foliage respiration and stem respiration of black spruce in heated and control plots during a 3-year period at a site located in Thompson, Manitoba. Greenhouses and soil-heating cables were used to maintain air and soil temperatures at 5 degrees C above ambient air and soil temperatures. Studies were conducted to determine the influence of soil and air warming; soil-only warming; and greenhouses maintained at ambient temperatures. The study showed that treatment differences for photosynthesis, foliage respiration, and stem respiration were not significant over the 3-year period. Results suggested that black spruce may not have significant changes in photosynthesis or respiration rates in warmer climates. 38 refs., 3 tabs., 4 figs.

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

    Science.gov (United States)

    Lorenzi-Filho, Geraldo; Genta, Pedro R; Figueiredo, Adelaide C; Inoue, Daniel

    2005-08-01

    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.

  19. Olfactory Bulb Field Potentials and Respiration in Sleep-Wake States of Mice.

    Science.gov (United States)

    Jessberger, Jakob; Zhong, Weiwei; Brankačk, Jurij; Draguhn, Andreas

    2016-01-01

    It is well established that local field potentials (LFP) in the rodent olfactory bulb (OB) follow respiration. This respiration-related rhythm (RR) in OB depends on nasal air flow, indicating that it is conveyed by sensory inputs from the nasal epithelium. Recently RR was found outside the olfactory system, suggesting that it plays a role in organizing distributed network activity. It is therefore important to measure RR and to delineate it from endogenous electrical rhythms like theta which cover similar frequency bands in small rodents. In order to validate such measurements in freely behaving mice, we compared rhythmic LFP in the OB with two respiration-related biophysical parameters: whole-body plethysmography (PG) and nasal temperature (thermocouple; TC). During waking, all three signals reflected respiration with similar reliability. Peak power of RR in OB decreased with increasing respiration rate whereas power of PG increased. During NREM sleep, respiration-related TC signals disappeared and large amplitude slow waves frequently concealed RR in OB. In this situation, PG provided a reliable signal while breathing-related rhythms in TC and OB returned only during microarousals. In summary, local field potentials in the olfactory bulb do reliably reflect respiratory rhythm during wakefulness and REM sleep but not during NREM sleep.

  20. Olfactory Bulb Field Potentials and Respiration in Sleep-Wake States of Mice

    Directory of Open Access Journals (Sweden)

    Jakob Jessberger

    2016-01-01

    Full Text Available It is well established that local field potentials (LFP in the rodent olfactory bulb (OB follow respiration. This respiration-related rhythm (RR in OB depends on nasal air flow, indicating that it is conveyed by sensory inputs from the nasal epithelium. Recently RR was found outside the olfactory system, suggesting that it plays a role in organizing distributed network activity. It is therefore important to measure RR and to delineate it from endogenous electrical rhythms like theta which cover similar frequency bands in small rodents. In order to validate such measurements in freely behaving mice, we compared rhythmic LFP in the OB with two respiration-related biophysical parameters: whole-body plethysmography (PG and nasal temperature (thermocouple; TC. During waking, all three signals reflected respiration with similar reliability. Peak power of RR in OB decreased with increasing respiration rate whereas power of PG increased. During NREM sleep, respiration-related TC signals disappeared and large amplitude slow waves frequently concealed RR in OB. In this situation, PG provided a reliable signal while breathing-related rhythms in TC and OB returned only during microarousals. In summary, local field potentials in the olfactory bulb do reliably reflect respiratory rhythm during wakefulness and REM sleep but not during NREM sleep.

  1. Effect of typhoon disturbance on soil respiration dynamic in a tropical broadleaves plantation in southern Taiwan

    Science.gov (United States)

    Chiang, Po-Neng; Yu, Jui-Chu; Lai, Yen-Jen

    2017-04-01

    Global forests contain 69% of total carbon stored in forest soil and litter. But the carbon storage ability and release rate of warming gases of forest soil also affect global climate change. Reforestation is one of the best solutions to mitigate warming gases release and to store in soil. Typhoon is one of the most hazards to disturb forest ecosystem and change carbon cycle. Typhoon disturbance is also affect soil carbon cycle such as soil respiration, carbon storage. Therefore, the objective of this study is to clarify the effect of typhoon disturbance on soil respiration dynamic in a tropical broadleaves plantation in southern Taiwan. Fourteen broadleaved tree species were planted in 2002-2005. Twelves continuous soil respiration chambers was divided two treatments (trench and non-trench) and observed since 2011 to 2014. The soil belongs to Entisol with over 60% of sandstone. The soil pH is 5.5 with low base cations because of high sand percentage. Forest biometric such as tree high, DBH, litterfall was measured in 2011-2014. Data showed that the accumulation amount of litterfall was highest in December to February and lowest in June. Soil respiration was related with season variation in research site. Soil temperature showed significantly exponential related with soil respiration in research site (p<0.001).However, soil respiration showed significantly negative relationship with total amount of litterfall (p<0.001), suggesting that the tree was still young and did not reach crown closure.

  2. Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

    DEFF Research Database (Denmark)

    Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine

    2006-01-01

    The soil fauna communities were described for three dominant vegetation types in a high arctic site at Zackenberg, Northeast Greenland. Soil samples were extracted to quantify the densities of mites, collembolans, enchytraeids, diptera larvae, nematodes and protozoa. Rates of microbial respiration...... densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...... were also assessed. Collembolans were found in highest densities in dry heath soil, about 130,000 individuals m-2, more than twice as high as in mesic heath soils. Enchytraeids, diptera larvae and nematodes were also more abundant in the dry heath soil than in mesic heath soils, whereas protozoan...

  3. Decaying dark matter and the PAMELA anomaly

    International Nuclear Information System (INIS)

    Ibarra, Alejandro; Tran, David

    2009-01-01

    Astrophysical and cosmological observations do not require the dark matter particles to be absolutely stable. If they are indeed unstable, their decay into positrons might occur at a sufficiently large rate to allow the indirect detection of dark matter through an anomalous contribution to the cosmic positron flux. In this paper we discuss the implications of the excess in the positron fraction recently reported by the PAMELA collaboration for the scenario of decaying dark matter. To this end, we have performed a model-independent analysis of possible signatures by studying various decay channels in the case of both a fermionic and a scalar dark matter particle. We find that the steep rise in the positron fraction measured by PAMELA at energies larger than 10 GeV can naturally be accommodated in several realizations of the decaying dark matter scenario. The data point toward a rather heavy dark matter particle, m DM ∼> 300 GeV, which preferentially decays directly into first or second generation charged leptons with a lifetime τ DM ∼ 10 26 s

  4. Dark Tourism and Destination Marketing

    OpenAIRE

    Jahnke, Daniela

    2013-01-01

    This thesis is about the dark tourism and destination marketing. The aim of the thesis is to display how these two terms can be combined. The term dark tourism is a relatively new research area; therefore the thesis will provide an outlook of the current situation of dark tourism. It starts with the beginning of dark tourism and continuous to the managerial aspects of dark tourism sites. The second part of the theoretical background is about destination marketing. It provides an overvie...

  5. MICROBIAL COLONIZATION, RESPIRATION, AND BREAKDOWN OF MAPLE LEAVES ALONG A STREAM-MARSH CONTINUUM

    Science.gov (United States)

    Breakdown rates, macroinvertebrate and bacterial colonization, and microbial respiration were measured on decaying maple (Acer saccharum) leaves at three sites along a stream-marsh continuum. Breakdown rates (-k+-SE) were 0.0284+-0.0045 d-1 for leaves in a high-gradient, non-tida...

  6. Curvature force and dark energy

    International Nuclear Information System (INIS)

    Balakin, Alexander B; Pavon, Diego; Schwarz, Dominik J; Zimdahl, Winfried

    2003-01-01

    A curvature self-interaction of the cosmic gas is shown to mimic a cosmological constant or other forms of dark energy, such as a rolling tachyon condensate or a Chaplygin gas. Any given Hubble rate and deceleration parameter can be traced back to the action of an effective curvature force on the gas particles. This force self-consistently reacts back on the cosmological dynamics. The links between an imperfect fluid description, a kinetic description with effective antifriction forces and curvature forces, which represent a non-minimal coupling of gravity to matter, are established

  7. Testing the Interacting Dark Energy Model with Cosmic Microwave Background Anisotropy and Observational Hubble Data

    Directory of Open Access Journals (Sweden)

    Weiqiang Yang

    2017-07-01

    Full Text Available The coupling between dark energy and dark matter provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, we assumed the interacting term was related to the Hubble parameter, energy density of dark energy, and equation of state of dark energy. The interaction rate between dark energy and dark matter was a constant parameter, which was, Q = 3 H ξ ( 1 + w x ρ x . Based on the Markov chain Monte Carlo method, we made a global fitting on the interacting dark energy model from Planck 2015 cosmic microwave background anisotropy and observational Hubble data. We found that the observational data sets slightly favored a small interaction rate between dark energy and dark matter; however, there was not obvious evidence of interaction at the 1 σ level.

  8. Ocean acidification alters early successional coral reef communities and their rates of community metabolism.

    Directory of Open Access Journals (Sweden)

    Sam H C Noonan

    Full Text Available Ocean acidification is expected to alter community composition on coral reefs, but its effects on reef community metabolism are poorly understood. Here we document how early successional benthic coral reef communities change in situ along gradients of carbon dioxide (CO2, and the consequences of these changes on rates of community photosynthesis, respiration, and light and dark calcification. Ninety standardised benthic communities were grown on PVC tiles deployed at two shallow-water volcanic CO2 seeps and two adjacent control sites in Papua New Guinea. Along the CO2 gradient, both the upward facing phototrophic and the downward facing cryptic communities changed in their composition. Under ambient CO2, both communities were dominated by calcifying algae, but with increasing CO2 they were gradually replaced by non-calcifying algae (predominantly green filamentous algae, cyanobacteria and macroalgae, which increased from ~30% to ~80% cover. Responses were weaker in the invertebrate communities, however ascidians and tube-forming polychaetes declined with increasing CO2. Differences in the carbonate chemistry explained a far greater amount of change in communities than differences between the two reefs and successional changes from five to 13 months, suggesting community successions are established early and are under strong chemical control. As pH declined from 8.0 to 7.8, rates of gross photosynthesis and dark respiration of the 13-month old reef communities (upper and cryptic surfaces combined significantly increased by 10% and 20%, respectively, in response to altered community composition. As a consequence, net production remained constant. Light and dark calcification rates both gradually declined by 20%, and low or negative daily net calcification rates were observed at an aragonite saturation state of <2.3. The study demonstrates that ocean acidification as predicted for the end of this century will strongly alter reef communities, and

  9. Dark matter detection - II

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the mysterious missing mass of the universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world-wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  10. Stable dark energy stars

    International Nuclear Information System (INIS)

    Lobo, Francisco S N

    2006-01-01

    The gravastar picture is an alternative model to the concept of a black hole, where there is an effective phase transition at or near where the event horizon is expected to form, and the interior is replaced by a de Sitter condensate. In this work a generalization of the gravastar picture is explored by considering matching of an interior solution governed by the dark energy equation of state, ω ≡ p/ρ < -1/3, to an exterior Schwarzschild vacuum solution at a junction interface. The motivation for implementing this generalization arises from the fact that recent observations have confirmed an accelerated cosmic expansion, for which dark energy is a possible candidate. Several relativistic dark energy stellar configurations are analysed by imposing specific choices for the mass function. The first case considered is that of a constant energy density, and the second choice that of a monotonic decreasing energy density in the star's interior. The dynamical stability of the transition layer of these dark energy stars to linearized spherically symmetric radial perturbations about static equilibrium solutions is also explored. It is found that large stability regions exist that are sufficiently close to where the event horizon is expected to form, so that it would be difficult to distinguish the exterior geometry of the dark energy stars, analysed in this work, from an astrophysical black hole

  11. Levitating dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Kaloper, Nemanja [Department of Physics, University of California, Davis, CA 95616 (United States); Padilla, Antonio, E-mail: kaloper@physics.ucdavis.edu, E-mail: antonio.padilla@nottingham.ac.uk [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2009-10-01

    A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark U(1)' charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra 'antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic w < −1. They can also lead to a local variation of galaxy-galaxy forces, yielding a larger 'Hubble Flow' in those regions of space that could be taken for a dynamical dark energy, or superhorizon effects.

  12. Levitating dark matter

    Science.gov (United States)

    Kaloper, Nemanja; Padilla, Antonio

    2009-10-01

    A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark U(1)' charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra `antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic w < -1. They can also lead to a local variation of galaxy-galaxy forces, yielding a larger `Hubble Flow' in those regions of space that could be taken for a dynamical dark energy, or superhorizon effects.

  13. Dark matter detection - I

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the mysterious missing mass of the universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world-wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  14. Dark matter detection - III

    International Nuclear Information System (INIS)

    Zacek, Viktor

    2015-01-01

    The quest for the missing mass of the universe has become one of the big challenges of todays particle physics and cosmology. Astronomical observations show that only 1% of the matter of the Universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the Universe is of a new exotic kind, different from the 'ordinary' matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world- wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called 'direct detection' techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the 'indirect detection' of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative nonparticle searches and future prospects. (author)

  15. Revival of the unified dark energy-dark matter model?

    International Nuclear Information System (INIS)

    Bento, M.C.; Bertolami, O.; Sen, A.A.

    2004-01-01

    We consider the generalized Chaplygin gas (GCG) proposal for unification of dark energy and dark matter and show that it admits an unique decomposition into dark energy and dark matter components once phantomlike dark energy is excluded. Within this framework, we study structure formation and show that difficulties associated to unphysical oscillations or blowup in the matter power spectrum can be circumvented. Furthermore, we show that the dominance of dark energy is related to the time when energy density fluctuations start deviating from the linear δ∼a behavior

  16. Dark matter as a weakly coupled dark baryon

    Science.gov (United States)

    Mitridate, Andrea; Redi, Michele; Smirnov, Juri; Strumia, Alessandro

    2017-10-01

    Dark Matter might be an accidentally stable baryon of a new confining gauge interaction. We extend previous studies exploring the possibility that the DM is made of dark quarks heavier than the dark confinement scale. The resulting phenomenology contains new unusual elements: a two-stage DM cosmology (freeze-out followed by dark condensation), a large DM annihilation cross section through recombination of dark quarks (allowing to fit the positron excess). Light dark glue-balls are relatively long lived and give extra cosmological effects; DM itself can remain radioactive.

  17. THE MAGIC OF DARK TOURISM

    Directory of Open Access Journals (Sweden)

    Erika KULCSÁR

    2015-10-01

    Full Text Available The dark tourism is a form of tourism that is not unanimously accepted by the whole society, but in spite of this fact, the practitioners of dark tourism is a viable segment. Indeed the concept that defines dark tourism is none other than death, and perhaps this is why it will always be a segment that will not be attracted by this form of tourism. Many questions about dark tourism arise. Among them: (1 is dark tourism an area of science attractive for researches? (2 which is the typology of dark tourism? (3 what are the motivating factors that determine practicing dark tourism? This paper provides a detailed analysis of publication behaviour in the field of dark tourism. The article also includes the main results obtained by achieving a quantitative marketing research among students of Sfantu Gheorghe University Extension in order to know their opinion, attitude towards dark tourism.

  18. Estimation of fractional contribution of root respiration to a forest-floor CO2 flux using carbon isotopes

    International Nuclear Information System (INIS)

    Hachiya, Masashi; Moriizumi, Jun; Yamazawa, Hiromi

    2010-01-01

    Efflux of soil respired carbon dioxide(CO 2 ) is very important component for the global carbon cycle and dynamics of 14 C in environment, and to predict the global climate changes caused by increasing CO 2 concentrations in the atmosphere. There are two components that generate CO 2 in soil, soil organic matter decomposition and root respiration. Although the former is relatively well understood, the root-derived CO 2 efflux has not been evaluated sufficiently. The objective of our research is to estimate depth profile of the root respiration rate. Thus we developed a box model which calculates the depth profile. In this paper, we discussed about (1) the adequacy of calculated result by comparing it to the to observed soil respired CO 2 flux with trenching method and (2) sensitivity of the box model to uncertainty in the input data. The result showed that the depth profile of root respiration rate decreased with soil depth. This is attributed to the distribution of fine roots which dominate root respiration. The model results reasonable agreed with the measurement results and characteristics of root respiration. The output of the model was robust to the variation of the input data. (author)

  19. Condensate cosmology: Dark energy from dark matter

    International Nuclear Information System (INIS)

    Bassett, Bruce A.; Parkinson, David; Kunz, Martin; Ungarelli, Carlo

    2003-01-01

    Imagine a scenario in which the dark energy forms via the condensation of dark matter at some low redshift. The Compton wavelength therefore changes from small to very large at the transition, unlike quintessence or metamorphosis. We study cosmic microwave background (CMB), large scale structure, supernova and radio galaxy constraints on condensation by performing a four parameter likelihood analysis over the Hubble constant and the three parameters associated with Q, the condensate field: Ω Q , w f and z t (energy density and equation of state today, and redshift of transition). Condensation roughly interpolates between ΛCDM (for large z t ) and SCDM (low z t ) and provides a slightly better fit to the data than ΛCDM. We confirm that there is no degeneracy in the CMB between H and z t and discuss the implications of late-time transitions for the Lyman-α forest. Finally we discuss the nonlinear phase of both condensation and metamorphosis, which is much more interesting than in standard quintessence models

  20. WISPy cold dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Arias, Paola [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Cadamuro, Davide; Redondo, Javier [Max-Planck-Institut fuer Physik, Muenchen (Germany); Goodsell, Mark [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-01-15

    Very weakly interacting slim particles (WISPs), such as axion-like particles (ALPs) or hidden photons (HPs), may be non-thermally produced via the misalignment mechanism in the early universe and survive as a cold dark matter population until today. We find that, both for ALPs and HPs whose dominant interactions with the standard model arise from couplings to photons, a huge region in the parameter spaces spanned by photon coupling and ALP or HP mass can give rise to the observed cold dark matter. Remarkably, a large region of this parameter space coincides with that predicted in well motivated models of fundamental physics. A wide range of experimental searches - exploiting haloscopes (direct dark matter searches exploiting microwave cavities), helioscopes (searches for solar ALPs or HPs), or light-shining-through-a-wall techniques - can probe large parts of this parameter space in the foreseeable future. (orig.)