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Sample records for acquisition isotope discrimination

  1. Trophic experiments to estimate isotope discrimination factors

    Caut, Stéphane; Angulo, Elena; Courchamp, Franck; Figuerola, Jordi

    2010-01-01

    : 1. In Caut, Angulo & Courchamp (2008a) rats were fed with experimental diets of distinct isotopic values (_13C and _15N) in order to infer the discrimination factors. We showed negative relationships between discrimination factors and diet isotopic values. In Caut, Angulo & Courchamp (2009), our aim was to generalise these relationships to other taxonomic groups with a view to providing ecologists with a general and flexible method to obtain discrimination factors for diet reconstruction st...

  2. Zinc isotope discrimination effect in inductively coupled plasma mass spectrometer

    Inductively coupled plasma mass spectrometry (ICPMS) has recently been used for isotope ratio analysis. The isotope discrimination effect in the mass spectrometer is a primary factor contributing to loss of precision and accuracy in isotope ratio analysis. The discrimination effect of zinc isotopes was investigated by comparing the results obtained using a quadrupole type ICPMS with those obtained using a thermal ionization mass spectrometer

  3. Substitutability between conditioned and primary reinforcers in discrimination acquisition.

    Williams, B A; Dunn, R

    1991-01-01

    Rats and pigeons were trained on a series of reversals of a conditional simultaneous discrimination. The percentage of reinforcement for correct trials was varied across reversals. When nonreinforced correct trials produced the same feedback as incorrect trials, the number of errors to reach an acquisition criterion was greater for smaller percentages of reinforcement, but the number of reinforcers required was either approximately constant or smaller for the smaller percentages. When a stimu...

  4. Isotopic incorporation rates and discrimination factors in mantis shrimp crustaceans.

    Maya S deVries

    Full Text Available Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 ± 0.6 ‰ and 0.9 ± 0.3 ‰ for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0-1 ‰ and 3-4 ‰, respectively. Surprisingly, the average residence time of nitrogen in hemolymph (28.9 ± 8.3 days was over 8 times longer than that of carbon (3.4 ± 1.4 days. In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 ± 44.4 and 72.8 ± 18.8 days, respectively. We compared the mantis shrimps' incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals.

  5. Data mining for isotope discrimination in atom probe tomography

    Ions with similar time-of-flights (TOF) can be discriminated by mapping their kinetic energy. While current generation position-sensitive detectors have been considered insufficient for capturing the isotope kinetic energy, we demonstrate in this paper that statistical learning methodologies can be used to capture the kinetic energy from all of the parameters currently measured by mathematically transforming the signal. This approach works because the kinetic energy is sufficiently described by the descriptors on the potential, the material, and the evaporation process within atom probe tomography (APT). We discriminate the isotopes for Mg and Al by capturing the kinetic energy, and then decompose the TOF spectrum into its isotope components and identify the isotope for each individual atom measured. This work demonstrates the value of advanced data mining methods to help enhance the information resolution of the atom probe. - Highlights: ► Atom probe tomography and statistical learning were combined for data enhancement. ► Multiple eigenvalue decompositions decomposed a spectrum with overlapping peaks. ► The isotope of each atom was determined by kinetic energy discrimination. ► Eigenspectra were identified and new chemical information was identified

  6. Isotopic Discrimination in the Double-Crested Cormorant (Phalacrocorax auritus.

    Elizabeth C Craig

    Full Text Available The diet-tissue discrimination factor is the amount by which a consumer's tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured discrimination factors in blood (whole blood, red blood cells and plasma, liver, muscle and feathers of Double-crested Cormorants (Phalacrocorax auritus for stable isotope ratios of carbon, nitrogen and sulfur. Cormorants exhibited discrimination factors that differed significantly among tissue types (for carbon and nitrogen, and differed substantially (in the context of the isotopic variation among relevant prey species from those observed in congeneric species. The Double-crested Cormorant has undergone rapid population expansion throughout much of its historic range over the past three decades, leading to both real and perceived conflicts with fisheries throughout North America, and this study provides an essential link for the use of stable isotope analysis in researching foraging ecology, diet, and resource use of this widespread and controversial species.

  7. Special calibrations and multi-isotopes acquisitions in scintillation cameras

    Aim: Our experience has been demonstrating that in the multi-isotopes procedures practiced in Nuclear Medicine, the quality of the images tends to be below the mono-isotopes acquisitions. Investigating the problem, we verified that its origin resides in the presence of the scattering radiation, which falls in windows of lower energy isotopes, and it is not considered in calibration procedures. Methodology: We performed a quantitative analysis using multi-isotopes sources, 18F - 99mTc and 131I - 99mTc, a dual head Elscint Helix scintillation camera with a capacity to acquire positrons emission collimated images and several evaluation with and without special calibration. We analyzed spectra to evaluate the behavior of the scattering radiation and adopted the protocol IAEA-TECDOC 602 /1992 and NEMA Standards Publication NU 1-1994 for the quantification of the intrinsic integral and differential uniformity. Special calibrations, energy (if available) and flood correction, were made with multi-isotopes sources in similar proportion to clinical procedures. Results: The results shows degradation in the lower energy isotopes images (99mTc) produced by scattering radiation of high energy isotope when standards calibration was performed. When special calibrations were made a better performance of the integral and differential uniformity coefficient occurred. Conclusions: The use of special calibrations, energy (if available) and flood correction, accomplished with multi-isotopes sources in similar proportions to clinical procedures, allows recovery of the existent quality patterns in mono-isotope acquisitions

  8. Discrimination Acquisition in Children with Developmental Disabilities under Immediate and Delayed Reinforcement

    Sy, Jolene R.; Vollmer, Timothy R.

    2012-01-01

    We evaluated the discrimination acquisition of individuals with developmental disabilities under immediate and delayed reinforcement. In Experiment 1, discrimination between two alternatives was examined when reinforcement was immediate or delayed by 20 s, 30 s, or 40 s. In Experiment 2, discrimination between 2 alternatives was compared across an…

  9. Improving crop water use efficiency using carbon isotope discrimination

    Water scarcity, drought and salinity are among the most important environmental constraints challenging crop productivity in the arid and semi-arid regions of the world, especially the rain-fed production systems. The current challenge is to enhance food security in water-limited and/or salt-affected areas for the benefit of resource-poor farmers in developing countries. There is also an increasing need that water use in agriculture should focus on improvement in the management of existing water resources and enhancing crop water productivity. The method based on carbon-13 discrimination in plant tissues has a potentially important role in the selection and breeding of some crop species for increased water use efficiency in some specific environments. Under various water-limited environments, low delta in the plants, indicating low carbon isotope discrimination has been generally associated with high transpiration efficiency (TE). In contrast, for well-watered environments many positive genotypic correlations have been reported between delta and grain yield indicating potential value in selecting for greater delta in these environments. Few studies have been reported on the impact of selection for delta on adaptation and grain yield in saline environments. Studies of the impact of genetic selection for greater and lower delta are currently coordinated by the Soil and water Management and Crop Nutrition Section (SWMCN) of the Joint FAO/IAEA Division. A Coordinated Research Project (CRP) is currently on-going on the Selection for Greater Agronomic Water-Use Efficiency in Wheat and Rice using Carbon Isotope Discrimination (D1-20 08). The overall objective of this project is to contribute to increasing the agronomic water-use efficiency of wheat and rice production, where agronomic water-use efficiency is defined as grain yield/total water use including both transpiration and evaporation. The CRP is also aiming at increasing wheat productivity under drought and rice

  10. Acquisition of Social Referencing via Discrimination Training in Infants

    Pelaez, Martha; Virues-Ortega, Javier; Gewirtz, Jacob L.

    2012-01-01

    This experiment investigated social referencing as a form of discriminative learning in which maternal facial expressions signaled the consequences of the infant's behavior in an ambiguous context. Eleven 4- and 5-month-old infants and their mothers participated in a discrimination-training procedure using an ABAB design. Different consequences…

  11. Inheritance of carbon isotope discrimination and water-use efficiency in cowpea

    Theory has been developed predicting an association between water-use efficiency (WUE = total biomass/transpiration) and leaf discrimination against 13C carbon isotope discrimination which could be used to indirectly select for WUE in C3 plants. Previous studies indicated variation in WUE and carbon isotope discrimination among genotypes of cowpea [Vigna unguiculata (L.) Walp.] and due to drought. Moreover, a highly significant negative correlation between WUE and carbon isotope discrimination was observed for both genotypic and drought effects, as expected based on theory. Present studies were conducted to investigate whether the inheritance of WUE and carbon isotope discrimination is nuclear or maternal, and whether any dominance is present. Contrasting cowpea accessions and hybrids were grown over 2 yr in two outdoor pot experiments, subjected to wet or dry treatments, and under full irrigation in natural soil conditions in 1 yr. Highly significant differences in WUE were observed among cowpea parents and hybrids, and due to drought, which were strongly and negatively correlated with carbon isotope discrimination as expected based on theory. Data from reciprocal crosses indicated that both WUE and carbon isotope discrimination are controlled by nuclear genes. High WUE and low carbon isotope discrimination exhibited partial dominance under pot conditions. In contrast, high carbon isotope discrimination was partially dominant for plants grown under natural soil conditions but in a similar aerial environment as in the pot studies. We speculate that differences in rooting conditions were responsible for the differences in extent of dominance for carbon isotope discrimination of plants growing under pot conditions compared with natural soil conditions in a similar field aerial environment

  12. Pb and Sr isotopic compositions of ancient pottery: a method to discriminate production sites

    The discriminating of production sites of ancient pottery samples using multi-isotopic systematics was described. Previous work has proven that Pb isotopic ratios can be used for discriminating the production sites of ancient pottery under certain conditions. The present work suggests that although Nd isotopic ratios are not sensitive to the production sites of ancient pottery, Sr isotopic ratios are important for the purpose. Pb isotopic ratios are indistinguishable for the pottery excavated from the Jiahu relict, Wuyang, Henan Province and for famous Qin Terra-cotta Figures. But, the 87Sr/86Sr ratios for the former (about 0.715) are significantly lower than that of the latter (0.717-0.718). The authors concluded that a combined use of Pb and Sr isotopes would be a more powerful method for discriminating the production site of ancient pottery. (authors)

  13. Isotope discrimination and partitioning exercises at the scale of the atmospheric boundary layer

    Berry, J.; Helliker, B.; Bakwin, P.; Davis, K.; Torn, M.

    2003-12-01

    During the daytime the atmospheric boundary layer (ABL) is typically well mixed by convection up to about 1.5 km and moves across the land about 500 km per day. Underlying ecosystems modify carbon dioxide in the ABL through photosynthesis and respiration, and ABL air is ultimately replaced by air from the overlying free troposphere. Hence, measurements of carbon dioxide and isotopes in the ABL and the free troposphere offer the potential for regionally integrated estimates of isotope discrimination. We use tall-tower and airplane measurements of carbon dioxide and carbon and oxygen isotopes to develop estimates of ABL-scale isotope discrimination. We then utilize ecosystem-level measurements of the isotope ratio of respiration and land surface model estimates of photosynthetic discrimination to deconvolve net carbon dioxide fluxes into the gross components of photosynthesis and respiration at the regional scale.

  14. Development of radon isotopes discrimination device by software delayed coincidence method based on ARM

    The software delayed coincidence counting technology was researched based on embedded system. The device based on ARM processor was constructed to record time serials information of nuclear pulse. According to the different half-life of Po short-life daughters of radon isotopes, a method of software delayed coincidence counting was used to discriminate radon isotopes. Experiment results of 220Rn and 219Rn standard source measurement show that the software delayed coincidence counting method is practical for discrimination measurement of low level activity of radon isotopes. The software method is an alternative to hardware one, and it can offer better convenience and flexibility. (authors)

  15. Carbon Isotope Discrimination and Salinity Tolerance in Rice

    The relationship between carbon isotope discrimination (CID, Δ13C, Δ) and salinity tolerance in rice was investigated in six experiments during 2004-09. In Experiment 1, quantitative trait loci (QTLs) for Δ were analyzed in an IR29 / Pokkali mapping population of 79 recombinant inbred lines (RILs) grown under salt stress imposed at the seedling stage. Three QTLs for flag leaf-Δ were detected on chromosomes 1, 3, and 11 with R2 values ranging from 18 to 33%, and all three co-located with mapped QTLs for salinity tolerance and Na+: K+ ratio. In Experiment 2, a set of 80 breeding lines and varieties were evaluated at the seedling stage for Δ and salinity tolerance using visual standard evaluation system (SES) scores, growth, salt uptake, and δ13C composition of leaves. While the first experiment using a mixture of sensitive and tolerant RILs showed strong correlations between Δ and salt-stress traits, the data from the breeding lines showed relatively weaker correlation, possibly due to the low genetic variability within this set and the high tolerance level of most of the lines. The correlation between Δ and salinity tolerance at the reproductive stage was tested in Experiment 3 using flag leaf and grain samples across a set of 80 tolerant and sensitive lines, including 46 breeding lines and 34 varieties and landraces. The flag leaf-Δ values correlated well with grain-Δ, and both correlated positively with grain yield of single plants, suggesting that flag leaf-Δ can potentially be used to select for salinity tolerance during the reproductive stage, which agreed with results obtained at the early vegetative stage. While the varieties and landraces showed larger variation across the different traits, the breeding lines were much more uniform. This data was found useful to select contrasting parental lines used for the development of new populations for subsequent studies. In Experiment 4, the same set of 80 tolerant and sensitive lines were evaluated at the

  16. Isotopic Incorporation and the Effects of Fasting and Dietary Lipid Content on Isotopic Discrimination in Large Carnivorous Mammals.

    Rode, K D; Stricker, C A; Erlenbach, J; Robbins, C T; Cherry, S G; Newsome, S D; Cutting, A; Jensen, S; Stenhouse, G; Brooks, M; Hash, A; Nicassio, N

    2016-01-01

    There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast for weeks to months. We conducted feeding trials with captive brown bears (Ursus arctos) and polar bears (Ursus maritimus). As dietary lipid content increased to ∼90%, we observed increasing differences between blood plasma and diets that had not been lipid extracted (∆(13)Ctissue-bulk diet) and slightly decreasing differences between plasma δ(13)C and lipid-extracted diet. Plasma Δ(15)Ntissue-bulk diet increased with increasing protein content for the four polar bears in this study and data for other mammals from previous studies that were fed purely carnivorous diets. Four adult and four yearling brown bears that fasted 120 d had plasma δ(15)N values that changed by carnivores has minimal effects on δ(13)C and δ(15)N discrimination between predators and their prey but that dietary lipid content is an important factor directly affecting δ(13)C discrimination and indirectly affecting δ(15)N discrimination via the inverse relationship with dietary protein content. PMID:27153128

  17. The atmospheric signal of terrestrial carbon isotopic discrimination and its implication for partitioning carbon fluxes

    The 13C/12C ratio in atmospheric carbon dioxide has been measured in samples taken in the NOAA/CMDL network since 1991. By examining the relationship between weekly anomalies in 13C and CO2 at continental sites in the network, we infer temporal and spatial values for the isotopic signature of terrestrial CO2 fluxes. We can convert these isotopic signatures to values of discrimination if we assume the atmospheric starting point for photosynthesis. The average discrimination in the Northern Hemisphere between 30 and 50 deg N is calculated to be 16.6 ± 0.2 per mil. In contrast to some earlier modeling studies, we find no strong latitudinal gradient in discrimination. However, we do observe that discrimination in Eurasia is larger than in North America, which is consistent with two modeling studies. We also observe a possible trend in the North American average of discrimination toward less discrimination. There is no apparent trend in the Eurasian average or at any individual sites. However, there is interannual variability on the order of 2 per mil at several sites and regions. Finally, we calculate the northern temperate terrestrial CO2 flux replacing our previous discrimination values of about 18 per mil with the average value of 16.6 calculated in this study. We find this enhances the terrestrial sink by about 0.4 GtC/yr

  18. Discrimination of the production sites of ancient pottery by using lead isotopic composition

    Discrimination of the production sites of ancient pottery by using lead isotopic composition is discussed in this paper. The authors have determined the lead isotopic compositions of ancient pottery from the Jiahu and Xishan sites, Henan Province. Most of Jiahu pottery show 206Pb/204Pb of 18.0 to 18.4 and 208Pb/204Pb of 38.4 to 38.8, while most of Xishan pottery show 20'6Pb/204Pb of 18.6 to 18.8 and 208Pb/204Pb of 38.7 to 39.1. Therefore, the lead isotopes are useful in discriminating the production sites of the ancient pottery in some cases

  19. Hyperspectral image acquisition and analysis of cultured bacteria for the discrimination of urinary tract infections.

    Turra, Giovanni; Conti, Nicola; Signoroni, Alberto

    2015-08-01

    Because of their widespread diffusion and impact on human health, early identification of pathogens responsible for urinary tract infections (UTI) is one of the main challenges of clinical microbiology. Currently, bacteria culturing on Chromogenic plates is widely adopted for UTI detection for its readily interpretable visual outcomes. However, the search of alternate solutions can be highly attractive, especially in the rapidly developing context of bacteriology laboratory automation and digitization, as long as they can improve cost-effectiveness or allow early discrimination. In this work, we consider and develop hyperspectral image acquisition and analysis solutions to verify the feasibility of a "virtual chromogenic agar" approach, based on the acquisition of spectral signatures from bacterial colonies growing on blood agar plates, and their interpretation by means of machine learning solutions. We implemented and tested two classification approaches (PCA+SVM and RSIMCA) that evidenced good capability to discriminate among five selected UTI bacteria. For its better performance, robustness and attitude to work with an expanding set of pathogens, we conclude that the RSIMCA-based approach is worth to be further investigated in a clinical usage perspective. PMID:26736373

  20. Discrimination of the Cigarettes Geographical Origin by DRC-ICP-MS Measurements of Pb Isotope Compositions

    Guo, W.; Hu, S.; Jin, L.

    2014-12-01

    Trace Pb are taken up with the same isotopic ratios as is present in the source soil, and the isotopic composition of Pb could used to reflect these sources and provide powerful indicators of the geographic origin of agriculture products derived from vegetative matter. We developed a simple and high throughput method, which based on DRC-ICP-MS for determination of Pb isotope ratios for discriminating the geographic origin of cigarettes. After acid digestion procedure, the cigarette digested solutions were directly analyzed by ICP-QMS with a DRC pressurized by the non-reactive gas Ne. In the DRC, Ne molecules collision with Pb ions and improves Pb isotope ratios precision 3-fold, which may be due to the collisional dampling smoothes out the ion beam fluctuations. Under the optimum DRC rejection parameter Q (RPq = 0.45), the main matrix components (K, Na, Ca, Mg, Al, Fe etc.) originating from cigarettes were filtered out. Mass discrimination of 208Pb/206Pb ratio in Ne DRC mode increased 0.3% compared to the standard mode, the mass bias due to the in-cell Ne gas collision can be accurately corrected by NIST 981 Pb isotope standard. This method was verified by a tobacco reference material CTV-OTL-2. Results of 208Pb/206Pb and 207Pb/206Pb were 2.0848 ± 0.0028 (2δ) and 0.8452 ± 0.0011 (2δ) for CTA-VTL-2, which were agreed with the literature values (208Pb/206Pb = 2.0884 ± 0.0090 and 207Pb/206Pb = 0.8442 ± 0.0032). The precision of Pb isotope ratios (208Pb/206Pb and 207Pb/206Pb) for the cigarette samples are ranged from 0.01 to 0.08% (N = 5). It has sufficient precision to discriminate 91 different brand cigarettes originated from four different geographic regions (Shown in Fig).

  1. Stable carbon isotope discrimination in the smut fungus Ustilago violacea

    Haploid strains 15.10, I.C429, and I.C2y and diploid strain JK2 of Ustilago Piolacea were grown on one or more of the following carbon sources: glucose, sucrose, maltose, inulin, starch, inositol, glycerol, casein, and yeast extract. The media, both before and after fungal growth, and the fungal cells were analyzed for 13C/12C content (δ13 values) using an isotope ratio mass spectrometer after combustion to CO2. In all cases, the used and unused media had identical δ13C values. Strain 15.10 had significantly less 13C than the media when grown on glucose, sucrose, maltose, and inositol; significantly more 13C when grown on inulin, starch, and glycerol; and no significant difference in δ13C values when grown on casein and yeast extract media. Other haploid strains responded similarly to 15.10. Diploid strain JK2 was also depleted in 13C when grown on glucose and enriched in 13C when grown on glycerol; however, JK2 was slightly depleted in 13C when grown on casein, whereas all the tested haploid strains were enriched in 13C

  2. Application of isotope discrimination techniques to evaluate the functional response of Mediterranean coppices to high-forest conversion cut

    2005-01-01

    Full Text Available Discrimination of stable isotopes of carbon and hydrogen provides an effective tool for interpreting time-integrated responses of plants to environmental conditions and delineate sources of plant water uptake. In this work, isotopic analyses were carried out in two Mediterranean oak forests in which a thinning experiment on replicated plots has been performed. Changes in carbon isotope discrimination suggests an increase of water use efficiency soon after thinning. Together with changes in the hydrogen isotopic composition in xylem sap, this may suggest that trees are able of a rather prompt physiological acclimation to cope effectively to new environmental conditions and changes in resource availability.

  3. Discrimination of spent nuclear fuels in nuclear forensics through isotopic fingerprinting

    Highlights: • Discrimination of spent fuel with forensic importance. • Isotopic fingerprinting method on the basis of U and/or Pu isotopic compositions. • Compositions from the OECD/NEA SFCOMPO databank with commercial nuclear reactors. • Method sensitive enough to resolve spent fuels from different reactors. • Dependence of discrimination on core position of fuel. - Abstract: Isotopic fingerprinting in nuclear forensics, developed through a simulation study to resolve spent nuclear fuels from different reactors, has been applied on real samples from fuels irradiated in nuclear reactors. The U and Pu isotopics of the real samples, used as fingerprints, have been retrieved from the OECD/NEA SFCOMPO databank comprising compositions of spent nuclear fuels from their Post-Irradiation Examination at the End of their Irradiation (EOI). The method has grouped together nuclear spent fuels from the same reactor, resolving distinctly those with similar 235U enrichment. Furthermore, spent fuel pins of the same enrichment, from different positions within a reactor core, are resolved. Differentiating of the spent fuels has been achieved, whether (U, Pu) or Pu are used as fingerprints

  4. Evaluation of salt tolerance in wheat genotypes using growth and carbon isotopes discrimination technique

    Studies were conducted in green house to select suitable salt tolerant wheat genotypes on the basis of growth performance and carbon isotopes discrimination (CID) technique. Nine newly developed double haploids (DH) wheat genotypes were tested under gravel culture, along with salt tolerant (LU-26s) and high yielding (Sarsabz) checks. The crop was irrigated by non-saline (control) and saline (12dS/m) water and raised up to maturity, growth parameters (i.e. plant height, plant biomass, productive tillers, spike length, number of spiklets/spike, number of grains / spike, grain weight/ spike and grain yield/ 15 plants) were recorded after harvesting. Plant samples (straw) were collected and were analyzed for carbon isotopic ratio (C12/ C13) from IAEA laboratories Vienna Austria. The data showed that there was significant decrease in all the growth parameters due to salinity. On the basis of performance in different growth parameters it was found that wheat genotypes V3-DH, V9-DH, V10-DH, V13-DH, and LU-26s had good response at 12dSm-1, thus can be categorized as better performing genotypes. Studies on carbon isotopes discrimination (CID) showed a decreasing trend under salinity. Mean CID values were 20.86 and 17.49 under two environments (non saline and saline, respectively), showing an overall 19% decrease under salinity. Generally the wheat genotypes having higher grain yield also had high carbon isotopes discrimination (CID). The relationship between grain yield and CID was positive (R2 = 0.695). The genotypes V10-DH, V13-DH with lower decrease in CID (i.e. 1.2 and 11.0%, respectively), also had high grain yield under salinity. Therefore the studies suggest that we can include CID technique as one of the selection criteria for salt tolerance. (author)

  5. Genetic Association between Grain Yield of Bread Wheat and Carbon Isotope Discrimination under Drought in Morocco

    The capacity of the wheat plant to discriminate against the carbon-13 isotope during photosynthesis, in favor of the lighter carbon-12 isotope, has been found to correlate with grain yield in many studies. This hypothesis was tested under four contrasting environments in Morocco during 2003-2006 using three sets of elite wheat genotypes. Significant positive correlations were found between carbon isotope discrimination (CID, Δ13C or Δ) and grain yield, and were higher under more water stressed environments at Douyet and Jemaa Sahim, indicating that high Δ is associated with high yield under drought stress. Selection based on yield appeared to have indirectly acted on Δ as well, since the correlation was significant and remained relatively unchanged across years of selection. This indicates a possible genetic linkage between yield and Δ. Also, transgressive segregation occurred for most agronomic and physiological traits, including Δ, offering a potential genetic variation for selection. At the molecular level, CID was found to be linked to a molecular marker at the gwm095 region of chromosome 2A, and to a thousand kernel weight marker at the gwm071 region, distant by 20-30 cent Morgan (cM). A poor QTL associated with grain yield was detected at chromosome 5A, similar to the one detected at CIMMYT in Obregon (Mexico) and northern Australia. From these results, it can be concluded that CID may be used as a new selection criterion to enhance wheat grain yield potential under drought in Morocco. (author)

  6. Temporal Dynamics and Environmental Controls on Carbon Isotope Discrimination at the Canopy Scale

    Billmark, K. A.; Griffis, T. J.; Lee, X.; Welp, L. R.; Baker, J. M.

    2007-12-01

    Much is currently known about 13C isotopic discrimination by C3 plants at the leaf scale. Multidisciplinary techniques from micrometeorology and the stable isotope community have exploited this knowledge to better understand the dynamic processes and environmental controls on atmosphere/biosphere exchange. Unfortunately, there remains a dearth of measurements relating carbon isotope discrimination at the canopy scale (Δcanopy) with the net carbon ecosystem flux. Our goals here are to evaluate temporal fluctuations in Δcanopy as a result of variable environmental conditions and to critically assess the efficacy of leaf-level assumptions applied at the canopy scale. At the University of Minnesota's Rosemount Research and Outreach Center (RROC), the exchange of 12CO2 and 13CO2 isotopologues are continuously measured using tunable diode laser (TDL) and micrometeorological techniques (eddy covariance-TDL and gradient-TDL methods). We utilize these data in conjunction with eddy flux and ancillary meteorological measurements to estimate Δcanopy, a key parameter for understanding ecosystem carbon source/sink behavior. Traditionally, Δcanopy is estimated using stomatal conductance models and leaf level isotopic discrimination parameters. In this study, we similarly calculated Δcanopy (Big-Leaf approach), where stomatal conductance was obtained through inversion of the Penman-Monteith equation. Additionally, given the high resolution of eddy flux and isoflux measurements at the RROC site, we were able to calculate Δcanopy using an inverse flux approach. For this approach, we partitioned the net ecosystem flux using eddy covariance measurements and a nighttime temperature regression method, and then calculated Δcanopy from the isoflux mass balance. Both calculations of Δcanopy emphasized the diurnal, daily and seasonal variability of this important parameter. In particular, atypically hot weather strongly influenced canopy isotope discrimination. Trends in the two

  7. Isotope discrimination and photosynthesis of vegetation growing in the Bossoleto CO2 spring

    The Bossoleto CO2 spring emits CO2 which has a stable carbon isotopic ration (δ13C = -8%). We determined δ13C on leaves of several individual species growing in Bossoleto and in a nearby control site at ambient CO2. δ13C was 6% more negative in leaves of species collected from the grassland community of Bossoleto, indicating discrimination (Δ) against the heavy carbon isotope. No such changes were found in ruderal species growing in the same spring, suggesting that photosynthetic capacity was much less affected. Δ was substantially increased under elevated CO2 in leaves of Quercus pubescens but not in Quercus ilex, which also did not show any increase in non-structural carbohydrates. Gas-exchange measurements made on Plantago lanceolata, supported the view that photosynthetic capacity is decreased in plants grown under elevated CO2 and on poor soils. (author)

  8. Tunable Diode Laser Measurements of Leaf-scale Carbon Isotope Discrimination and Ecosystem Respired Carbon and Oxygen Isotope Ratios in a Semi-arid Woodland

    McDowell, N.; Chris, B.; Hanson, D.; Kern, S.; Meyer, C.; Pockman, W.; Powers, H.

    2005-12-01

    We present results and speculative interpretation of leaf-level carbon isotope discrimination and ecosystem respired carbon and oxygen isotope ratios from a semi-arid, C3/C4 woodland located in northern New Mexico, USA. Overstory leaf area index (LAI) is dominated by live juniper (Juniperus monosperma) trees with an LAI value of approximately 1.0 m2 per m2 ground area, and has a seasonally dynamic understory of mixed C3 forbs and C4 grasses and cacti, with a maximum LAI of 0.30 m2 per m2 ground area. Ecosystem respired carbon isotope ratios showed values characteristic of C3 dominated photosynthesis (Keeling plot intercepts of -35 to -22 per mil). Seasonal variation was typical of that found in wetter, C3 dominated forests, as was the dependence on climate (e.g. relationships with vapor pressure deficit, soil water content, and canopy conductance). Leaf-level carbon isotope discrimination of the junipers, measured by coupling a Li-Cor 6400 photosynthesis system to the TDL, provided discrimination-Ci and discrimination-vpd relationships consistent with measured ecosystem respired carbon isotope ratios. The oxygen isotope ratio of ecosystem respiration was dependent on rain water isotope composition, but was correlated with soil water content during rain-free periods. The cumulative effect of vapor pressure deficit after a rain event was tightly correlated with the oxygen isotope ratio of ecosystem respiration, suggesting the primary drivers are evaporative enrichment of soil water and perhaps nocturnal leaf enrichment. Instrument precision for carbon and oxygen isotope ratios of carbon dioxide is 0.06 to 0.18 per mil; however, overall precision is somewhat lower due to pressure and sampling effects.

  9. The IAEA programme on the acquisition of data for the fallout isotopic composition

    The IAEA, in collaboration with the World Meteorogical Organization, has been working since 1961 on a long-term project for acquistion, processing and publication of data for the isotopic composition (T,D, 180) of the fallout on a global scale. At present, IAEA has data, compiled from 347 hydrometeorogical stations in 79 countries. The analysis of isotope data, obtained from the global station network for more than 20 years, allows the following conclusions: (i)The global trends of forming the isotope composition of atmospheric fallout, which are one of the maior links of the hydrogeological cycle, are clarified; (ii)These regularities enabled the use of hydrogen and oxygen isotopes in scientific research and the practice; (iii)Extensive studies of the resourses of surface and ground water and of their genesis and dynamics have been carried out, using the fallout isotopic composition as an input function; (iv)The effectiveness of further efforts in isotope composition data acquisition is limited by the lack of analyses using models of the global atmospheric circulation; (v)Further regular observations of the variations in fallout isotope composition are needed for some large regions of Eurasia, Africa and the polar region

  10. Temperature response of carbon isotope discrimination and mesophyll conductance in tobacco.

    Evans, John R; von Caemmerer, Susanne

    2013-04-01

    The partial pressure of CO2 at the sites of carboxylation within chloroplasts depends on the conductance to CO2 diffusion from intercellular airspace to the sites of carboxylation, termed mesophyll conductance (gm ). We investigated the temperature response of gm in tobacco (Nicotiana tabacum) by combining gas exchange in high light, ambient CO2 in either 2 or 21% O2 with carbon isotope measurements using tuneable diode laser spectroscopy. The gm increased linearly with temperature in 2 or 21% O2 . In 21% O2 , isotope discrimination associated with gm decreased from 5.0 ± 0.2 to 1.8 ± 0.2‰ as temperature increased from 15 to 40 °C, but the photorespiratory contribution to the isotopic signal is significant. While the fractionation factor for photorespiration (f = 16.2 ± 0.7‰) was independent of temperature between 20 and 35 °C, discrimination associated with photorespiration increased from 1.1 ± 0.01 to 2.7 ± 0.02‰ from 15 to 40 °C. Other mitochondrial respiration contributed around 0.2 ± 0.03‰. The drawdown in CO2 partial pressure from ambient air to intercellular airspaces was nearly independent of leaf temperature. By contrast, the increase in gm with increasing leaf temperature resulted in the drawdown in CO2 partial pressure between intercellular airspaces and the sites of carboxylation decreasing substantially at high temperature. PMID:22882584

  11. Discrimination between ginseng from Korea and China by light stable isotope analysis

    Ginseng is a health food and traditional medicine highly valued in Asia. Ginseng from certain origins is higher valued than from other origins, so that a reliable method for differentiation of geographical origin is important for the economics of ginseng production. To discriminate between ginseng samples from South Korea and PR China, 29 samples have been analyzed for the isotopic composition of the elements H, C and N. The results showed δ2H values between -94 and -79 per mille , for δ13C -27.9 to -23.7 per mille and for δ15N 1.3-5.4 per mille for Chinese ginseng. Korean ginseng gave δ2H ratios between -91 and -69 per mille , δ13C ratios between -31.2 and -22.4 per mille and δ15N ratios between -2.4 and +7 per mille . Despite the overlap between the values for individual isotopes, a combination of the isotope systems gave a reasonable differentiation between the two geographic origins. Especially the statistically significant difference in δ2H ratios facilitated the differentiation between Korean and Chinese ginseng samples.

  12. Studies on 13C isotope discrimination for identifying tree provenances efficient in water use under water deficit conditions in Kenya

    Screening for drought resistance traits was conducted in a semi-arid site in Machakos using 11 provenances of Acacia tortilis, 6 provenances of Prosopis juliflora and 4 provenances of Casuarina equisetifolia. Tolerance to drought was assessed by the 13C isotope discrimination (Δ) technique as well as by determining the waster use efficiency (WUE). Measurements of dry matter and early growth performance were also taken as indicators of drought resistance. The results showed significant differences in the 13C Isotope discrimination, water use efficiency and dry matter yields by the different provenances tested. Generally, the results indicated that there were significant linear negative relationships between 13C discrimination with water use efficiency as well as dry matter yield. The results further showed highly significant positive relationship between dry matter yield and water use efficiency. Acacia tortilis provenances from middle East and neighbouring North Eastern Africa region appear to possess the greatest abilities for drought resistance in comparison with those from sub-saharan Africa as indicated by their 13C Isotope discrimination levels, dry matter yield and water use efficiency. However, Acacia provenance from Israel had the highest drought resistance trail. Prosopis provenance from Costa Rica and Casuarina from Dakar region in Senegal also emerged as the best provenances in terms of drought tolerance as shown by the 13C isotope discrimination and dry matter traits. (author). 8 refs, 4 figs, 3 tabs

  13. Application of the isotopic ratio based method for discrimination between nuclear tests and nuclear reactors on various data sets

    The monitoring of atmospheric radioxenon is a crucial element in the verification of the comprehensive nuclear-test-ban treaty (CTBT). In order to discriminate between legitimate nuclear reactor emissions and nuclear explosions, the isotopic activity ratios can be used. Various data sets are used to demonstrate the discrimination capability of the isotopic radio method. These include daily and annual emission reports from nuclear power plants and atmospheric observations at various sites. Five air samples are of special interest. They were measured a few days after the North Korean nuclear test in October 2006

  14. Sequential and simultaneous dual-isotope brain SPECT: Comparison with PET for estimation and discrimination tasks in early Parkinson disease

    Trott, Cathryn M.; El Fakhri, Georges

    2008-01-01

    Parkinson disease (PD) is the second most frequently occurring cerebral degenerative disease, after Alzheimer disease. Treatments are available, but their efficacy is diminished unless they are administered in the early stages. Therefore, early identification of PD is crucial. In addition to providing perfectly registered studies, simultaneous 99mTc∕123I imaging makes possible the assessment of pre- and postsynaptic neurotransmission functions under identical physiological conditions, while doubling the number of counts for the same total imaging time. These advantages are limited, however, by cross talk between the two radionuclides due to the close emission energies of 99mTc (140 keV) and 123I (159 keV). PET, on the other hand, provides good temporal and spatial resolution and sensitivity but usually requires the use of a single radionuclide. In the present work, the authors compared brain PET with sequential and simultaneous dual-isotope SPECT for the task of estimating striatal activity concentration and striatal size for a normal brain and two stages of early PD. Realistic Monte Carlo simulations of a time-of-flight PET scanner and gamma cameras were performed while modeling all interactions in the brain, collimator (gamma camera) and crystal (detector block in PET), as well as population biological variability of pre- and postsynaptic uptake. For SPECT imaging, we considered two values of system energy resolution and scanners with two and three camera heads. The authors used the Cramer–Rao bound, as a surrogate for the best theoretical performance, to optimize the SPECT acquisition energy windows and objectively compare PET and SPECT. The authors determined the discrimination performance between 500 simulated subjects in every disease stage as measured by the area under the ROC curve (AUC). The discrimination accuracy between a normal subject and a subject in the prodromal disease stage was AUC=0.924 with PET, compared to 0.863 and 0.831 with simultaneous

  15. Is it really organic? - multi-isotopic analysis as a tool to discriminate between organic and conventional plants

    Laursen, K. H.; Mihailova, A.; Kelly , S.D.; Epov, V.N.; Berail, S.; J. K. Schjoerring; O. F. X. Donard; Larsen, E. H.; Pedentchouck, N.; Marca-Bell, A.D.; Halekoh, U.; Olesen, Jørgen E.; Husted, S

    2013-01-01

    Novel procedures for analytical authentication of organic plant products are urgently needed. Here we present the first study encompassing stable isotopes of hydrogen, carbon, nitrogen, oxygen, magnesium and sulphur as well as compound-specific nitrogen and oxygen isotope analysis of nitrate for discrimination of organically and conventionally grown plants. The study was based on wheat, barley, faba bean and potato produced in rigorously controlled long-term field trials comprising 144 experi...

  16. Effect of N and P Availability on 13C Isotope Discrimination in Wheat and Rice

    Nutrient deficiencies (particularly N and P) contribute to low yields of wheat and rice in drought-prone (semi-arid and arid) environments. Although carbon isotope discrimination (CID, Δ13C or Δ) has been proposed as a useful trait for selecting C3 cereal crops in drought and salinity stressed environments, the effect of plant nutrition on the efficacy of using Δ as a selection tool for high yield in nutrient-stressed environments is unknown. Two greenhouse pot experiments were conducted to assess the effect of N and P supply and their combined effects on Δ in shoots (ΔSh) and in spikes (ΔSp) of wheat grown under well-watered conditions, and of rice grown under saline and non-saline conditions. ΔSp and ΔSh of wheat significantly decreased (P3 cereals. (author)

  17. Conditional discrimination in mentally retarded subjects: programming acquisition and learning set.

    Saunders, K J; Spradlin, J E

    1993-01-01

    In Experiment 1, 3 subjects with retardation were exposed to two visual-visual arbitrary matching-to-sample problems each day. One conditional discrimination was presented under trial-and-error conditions, and the other was presented under a component training procedure. The latter began by establishing the comparison discrimination and its rapid reversal. The successive discrimination between the sample stimuli was established through differential naming. Then, sample naming was maintained i...

  18. Carbon isotope discrimination in leaf juice of Acacia mangium and its relationship to water-use efficiency

    lvliu ZOU; Guchou SUN; Ping ZHAO; Xian CAI; Xiaoping ZENG; Xiaojing LIU

    2009-01-01

    Using the PMS pressure chamber and isotope mass spectrometer (MAT-252), the leaf juice of Acacia mangium was obtained, and the carbon isotope discrimination (△) representing the most recently fixed carbon in the juice was determined. At the same time, the water-use efficiency of A. mangium was estimated. The results indicated that the carbon isotope ratio in the air of forest canopy (δa), 10m high above ground averaged -7.57 1.41‰ in cloudy days, and - 8.54±0.67 ‰ in sunny days, respectively. The diurnal change of the carbon isotope ratio in the photosynthetic products of the leaf juice (δp) was of saddle type in cloudy days, but dropped down from morning to later afternoon in sunny days. A strong negative correlation betweenδp and leaf-to-air vapor pressure deficit (D) was observed in sunny days, but a slight change inδp, was found in cloudy days. Theδp also decreased with decreasing leaf water potential (ψ), reflecting that water stress could cause the decrease ofδp. The carbon isotope discrimination of the leaf juice was positively correlated with the ratio between intercellular (Pi) and atmospheric (Pa) partial pressure of CO2. For A. mangium, the isotope effect on diffusion of atmospheric CO2 via stomata was denoted by a = 4.6 %>, and that in net C3 diffusion with respect to Pi was indicated by b = 28.2 ‰. The results were in reasonable accord with the theoretically diffusive and biochemical fractionation of carbon isotope. It was defined that carbon isotope discrimination of photosynthetic products in A. mangium leaf juice was in proportion to that from photosynthetic products in dry material. The water-use efficiency estimated by the carbon isotope discrimination in leaf juice, fit well with that measured by gas exchange system (R2 = 0.86, p< 0.0001). The application of leaf juice in measuring the stable carbon isotope discrimination would reduce the effects of fluctuating environmental factors during the synthesis of dry matter, and improve

  19. Effects of trophic level and metamorphosis on discrimination of hydrogen isotopes in a plant-herbivore system

    Peters, Jacob M.; Wolf, Nathan; Stricker, Craig A.; Collier, Timothy R.; del Rio, Martinez Carlos

    2012-01-01

    The use of stable isotopes in ecological studies requires that we know the magnitude of discrimination factors between consumer and element sources. The causes of variation in discrimination factors for carbon and nitrogen have been relatively well studied. In contrast, the discrimination factors for hydrogen have rarely been measured. We grew cabbage looper caterpillars (Trichoplusia ni) on cabbage (Brassica oleracea) plants irrigated with four treatments of deuterium-enriched water (δD = -131, -88, -48, and -2‰, respectively), allowing some of them to reach adulthood as moths. Tissue δD values of plants, caterpillars, and moths were linearly correlated with the isotopic composition of irrigation water. However, the slope of these relationships was less than 1, and hence, discrimination factors depended on the δD value of irrigation water. We hypothesize that this dependence is an artifact of growing plants in an environment with a common atmospheric δD value. Both caterpillars and moths were significantly enriched in deuterium relative to plants by ~45‰ and 23‰ respectively, but the moths had lower tissue to plant discrimination factors than did the caterpillars. If the trophic enrichment documented here is universal, δD values must be accounted for in geographic assignment studies. The isotopic value of carbon was transferred more or less faithfully across trophic levels, but δ15N values increased from plants to insects and we observed significant non-trophic 15N enrichment in the metamorphosis from larvae to adult.

  20. Tissue turnover rates and isotopic trophic discrimination factors in the endothermic teleost, pacific bluefin tuna (Thunnus orientalis.

    Daniel J Madigan

    Full Text Available Stable isotope analysis (SIA of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver and isotope- (nitrogen and carbon specific turnover rates and trophic discrimination factors (TDFs using archived tissues from captive Pacific bluefin tuna (PBFT, Thunnus orientalis, 1-2914 days after a diet shift in captivity. Half-life values for (15N turnover in white muscle and liver were 167 and 86 days, and for (13C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ(15N and 1.8 and 1.2‰ for δ(13C, respectively. Our results demonstrate that turnover of (15N and (13C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. (15N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ(15N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology.

  1. Range-Image Acquisition for Discriminated Objects in a Range-gated Robot Vision System

    Park, Seung-Kyu; Ahn, Yong-Jin; Park, Nak-Kyu; Baik, Sung-Hoon; Choi, Young-Soo; Jeong, Kyung-Min [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    demonstrated 3D imaging based on range-gated imaging. Robot vision is a key technology to remotely monitor structural safety in radiation area of nuclear industry. Especially, visualization technique in low-visibility areas, such as smoking and fog areas, is essential to monitor structural safety in emergency smoking areas. In this paper, a range acquisition technique to discriminate objects is developed. The developed technique to acquire object range images is adapted to a range-gated vision system. Visualization experiments are carried out to detect objects in low-visibility fog environment. The experimental result of this newly approach vision system is described in this paper.

  2. Range-Image Acquisition for Discriminated Objects in a Range-gated Robot Vision System

    demonstrated 3D imaging based on range-gated imaging. Robot vision is a key technology to remotely monitor structural safety in radiation area of nuclear industry. Especially, visualization technique in low-visibility areas, such as smoking and fog areas, is essential to monitor structural safety in emergency smoking areas. In this paper, a range acquisition technique to discriminate objects is developed. The developed technique to acquire object range images is adapted to a range-gated vision system. Visualization experiments are carried out to detect objects in low-visibility fog environment. The experimental result of this newly approach vision system is described in this paper

  3. Carbon isotope discrimination as a selection tool for high water use efficiency and high crop yields

    Results of back-up research conducted at the FAO/IAEA Agriculture and Biotechnology Laboratory in support of the FAO/IAEA Co-ordinated Research Programme on the Use of Isotope Studies on Increasing and Stabilizing Plant Productivity in Low Phosphate and Semi-arid and Sub-humid Soils of the Tropics and Sub-tropics, are presented here. Neutron probe measurements confirmed the earlier reports of a strong correlation of Δ with grain yield and water use efficiency of wheat. High soil gypsum content and soil salinity, a wide spread problem in soils of arid and semi-arid climatic zones, do not interfere with the association of Δ with crop yields, provided plants are grown in similar soil water status and soil fertility level. Results of a glasshouse experiment using selected cowpea genotypes showed that Δ values measured at flowering stage positively correlated with total dry matter production and percent N2 derived from atmosphere (%Ndfa), contributing to an earlier report from the laboratory that it may be possible to use Δ values for screening of leguminous crops for high N2 fixation potential. 13C isotope discrimination in the leaves of Gliricidia sepium was measured to examine if the technique could be extended to studies with trees. Results of a glasshouse experiment with 18 provenances of Gliricidia sepium showed highly significant correlations of Δ with total dry matter production, water use efficiency and total N accumulated through biological nitrogen fixation. Although the correlation of Δ with water use efficiency and dry matter yield are relatively clear and better understood, the correlation with nitrogen fixation still needs a closer examination under different environmental conditions and with different species. While 13C isotope discrimination may be a valuable tool for identifying annual crops with high water use efficiency and high yield potential, it may be more attractive for tree species considering the long growth periods taken for trees to

  4. Discrimination of geographical origin of lentils (Lens culinaris Medik.) using isotope ratio mass spectrometry combined with chemometrics.

    Longobardi, F; Casiello, G; Cortese, M; Perini, M; Camin, F; Catucci, L; Agostiano, A

    2015-12-01

    The aim of this study was to predict the geographic origin of lentils by using isotope ratio mass spectrometry (IRMS) in combination with chemometrics. Lentil samples from two origins, i.e. Italy and Canada, were analysed obtaining the stable isotope ratios of δ(13)C, δ(15)N, δ(2)H, δ(18)O, and δ(34)S. A comparison between median values (U-test) highlighted statistically significant differences (plentils produced in these two different geographic areas, except for δ(15)N. Applying principal component analysis, grouping of samples was observed on the basis of origin but with overlapping zones; consequently, two supervised discriminant techniques, i.e. partial least squares discriminant analysis and k-nearest neighbours algorithm were used. Both models showed good performances with external prediction abilities of about 93% demonstrating the suitability of the methods developed. Subsequently, isotopic determinations were also performed on the protein and starch fractions and the relevant results are reported. PMID:26041202

  5. Optimization and comparison of simultaneous and separate acquisition protocols for dual isotope myocardial perfusion SPECT

    Dual-isotope simultaneous-acquisition (DISA) rest-stress myocardial perfusion SPECT (MPS) protocols offer a number of advantages over separate acquisition. However, crosstalk contamination due to scatter in the patient and interactions in the collimator degrade image quality. Compensation can reduce the effects of crosstalk, but does not entirely eliminate image degradations. Optimizing acquisition parameters could further reduce the impact of crosstalk. In this paper we investigate the optimization of the rest Tl-201 energy window width and relative injected activities using the ideal observer (IO), a realistic digital phantom population and Monte Carlo (MC) simulated Tc-99m and Tl-201 projections as a means to improve image quality. We compared performance on a perfusion defect detection task for Tl-201 acquisition energy window widths varying from 4 to 40 keV centered at 72 keV for a camera with a 9% energy resolution. We also investigated 7 different relative injected activities, defined as the ratio of Tc-99m and Tl-201 activities, while keeping the total effective dose constant at 13.5 mSv. For each energy window and relative injected activity, we computed the IO test statistics using a Markov chain Monte Carlo (MCMC) method for an ensemble of 1,620 triplets of fixed and reversible defect-present, and defect-absent noisy images modeling realistic background variations. The volume under the 3-class receiver operating characteristic (ROC) surface (VUS) was estimated and served as the figure of merit. For simultaneous acquisition, the IO suggested that relative Tc-to-Tl injected activity ratios of 2.6–5 and acquisition energy window widths of 16–22% were optimal. For separate acquisition, we observed a broad range of optimal relative injected activities from 2.6 to 12.1 and acquisition energy window of widths 16–22%. A negative correlation between Tl-201 injected activity and the width of the Tl-201 energy window was observed in these ranges. The

  6. Comparative Evaluation of Oxygen Isotope Composition and Carbon Isotope Discrimination in Selecting for Greater Agronomic Water Use Efficiency in Wheat

    The efficacy of using oxygen isotope composition (δ18O) and carbon isotope discrimination (Δ13C, CID or Δ) in selecting for greater agronomic water-use efficiency in wheat was studied. The objective was to determine whether natural-abundance measurements of Δ13C or δ18O of crop dry matter can be used to separate differences in access to soil water during grain filling from differences in assimilate re-translocation to the grain. The study consisted of carefully-controlled irrigation and rainfall-exclusion, which established two treatments with different soil-water availability at depth when they entered the post-anthesis (p-A) phase. Values of Δ13C and δ18O were measured on green leaves, senesced leaves, stem, non-grain ear parts (chaff) and grain from samples taken several times p-A from a field trial grown in SE Australia in 2004. Soil water content was measured from sowing to maturity using a neutron moisture meter, while roots were extracted from soil cores. Leaf porosity was also measured p-A using a Thermoline viscous-flow porometer and the values were related to stomatal conductance; in addition, canopy temperature was measured using a hand-held Mikron M-120 infrared thermometer. Substantial variation was observed in Δ13C and δ18O among plant parts, with the grain having the smallest values of Δ13C and the largest values of δ18O. There were large changes in grain Δ13C and grain δ18O with time p-A. Grain-Δ13C was smallest and grain δ18O largest at 12 d p-A. At 27, 34 and 48 d p-A, the value of grain Δ13C had increased by up to 1.5 per mille and grain δ18O had decreased by up to 2 per mille. The magnitudes of these changes with time p-A were consistent with observed contributions to grain dry weight from re-translocation of stored assimilates. No treatment differences were observed for grain δ18O. Small treatment differences found for grain Δ13C late in grain filling may have been due to the small treatment difference in sub-soil water use

  7. Lead isotopic analyses of NIST standard reference materials using multiple collector inductively coupled plasma mass spectrometry coupled with a modified external correction method for mass discrimination effect

    A correction method for the mass discrimination effect was developed for isotopic analyses using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). For Pb isotopic analysis using MC-ICP-MS, the correction factor for the mass discrimination effect on Pb is based on the addition of Tl to the sample solution and measurement of Tl isotopic ratios; the correction factor obtained using Tl is directly applied to the Pb isotopes (conventional external correction). However, the series of measurements of discrimination factors for several elements, including Rb, Sr, Ru, Nd, Hf, Re, Os, Tl and Pb (mass range 80-210 u), clearly reveal that the mass discrimination factors observed using MC-ICP-MS were a linear function of mass, suggesting that the correction factors observed using Tl isotopes were not exactly identical with those for Pb isotopes. Therefore, the correction factors obtained with Tl isotopes should be corrected for mass, and then applied to the Pb isotopes. The resultant Pb isotopic ratios for NIST Standard Reference Materials show excellent agreement (within 0.3% for 206Pb/204Pb and 20 ppm for 207Pb/206Pb) with the data obtained by the thermal ionization mass spectrometry. The correction method presented clearly demonstrates the wide versatility of the external correction technique for the precise isotopic analysis using MC-ICP-MS. The possible cause of the 'exceptionally large' mass discrimination effect observed for Ru and Os is discussed. (author)

  8. Discriminant and criterion-related validity of a relative deprivation scale in a merger and acquisition context.

    Lee, Dongseop; Cho, Bongsoon; Seo, Jeongil; Lee, Khan-Pyo; Choi, Jang-Ho

    2014-02-01

    This study examined the discriminant and criterion-related validity of the Relative Deprivation Scale. The data were collected from 151 Korean employees who had recently experienced a merger and acquisition. The results of confirmatory factor analysis revealed that the two dimensions of relative deprivation (egoistic and fraternal relative deprivation) are clearly distinguishable from other conceptually related variables, such as negative affectivity, resistance to change, overall job dissatisfaction, and distributive justice. In addition, egoistic relative deprivation made a unique incremental contribution to explaining employee turnover intention beyond the contribution of conceptually related variables, while fraternal relative deprivation did not. PMID:24765711

  9. Responses of carbon isotope discrimination in C4 plant to variable N and water supply

    Yang, Hao; Li, Shenggong

    2016-04-01

    Understanding variations and underlying mechanisms of carbon isotope discrimination (Δ) in C4 species is critical for predicting the effects of change in C3/C4 ratio of plant community on ecosystem processes and functionning. However, little is known about the effects of soil resource gradients on Δ of C4 plants. To address Δ responses to drought and nitrogen supply, the leaf carbon isotope composition, bundle sheath leakiness (BLS), and leaf gas exchange (A, gs, Ci/Ca) were measured on Cleistogenes squarrosa, a dominant C4 species in the Inner Mongolia grassland. C. squarrosa were grown in controlled-environment pots from seed under a combination of water and N supply. High N availability and drought stimulated photosynthetic rate (A) and further decreased the ratio of internal and ambient CO2 concentrations (Ci/Ca) through increasing leaf N content. BLS was higher under high N supply and was unchanged by drought. There was significant interaction between N and water supply to affect BLS and Ci/Ca. Δ was negatively related to Ci/Ca and was positively related to BLS. Tradeoff between the responses of BLS and Ci/Ca to changing environmental conditions kept leaf Δ relatively stable, which was also supported by a field N addition experiment. Our results suggested leaf Δ of C4 plant was unchanged under variable water and N environment conditions although the operating efficiency of C4 pathway and CO2 concentration in photosynthesis were changed. Our findings have implications for predicting the change of C3/C4 ratio of plant community and understanding ecosystem processes and functionning.

  10. Isotopic discrimination of nitrogen associated with biological nitrogen fixation on the system Rhizobium versus beans (Phaseolus vulgaris L.)

    Two experiments were carried out in the greenhouse using a complete randomized experimental design. The first experiments was designed to assess the effect of three bean cultivars, inoculated with a mixture of efficient Rhizobium strains on the isotopic N discrimination at four development stages of beans plants. The second experiment was carried out to verify if there is any discrimination caused by the Rhizobium strains used. The plants of both experiments were grown in a N free medium, with 5 replicates. At the harvesting, δN-15% was determined in the following parts of the bean plants: nodules, roots, shoots, cotyledons and pods. (author)

  11. Embedding an identity-matching task within a prompting hierarchy to facilitate acquisition of conditional discriminations in children with autism.

    Fisher, Wayne W; Kodak, Tiffany; Moore, James W

    2007-01-01

    Least-to-most prompting hierarchies (e.g., progressing from verbal to modeled to physical prompts until the target response occurs) may be ineffective when the prompts do not cue the individual to attend to the relevant stimulus dimensions. In such cases, emission of the target response persistently requires one or more of the higher level prompts, a condition called prompt dependence (Clark & Green, 2004). Reinforcement of differential observing responses (DORs) has sometimes been used to ensure that participants attend to the relevant stimulus dimensions in matching-to-sample (MTS) tasks (e.g., Dube & McIlvane, 1999). For 2 participants with autism, we embedded an identity-matching task within a prompting hierarchy as a DOR to increase the likelihood that the participants attended to and discriminated the relevant features of the comparison stimuli in an MTS task. This procedure was compared with a traditional least-to-most prompting hierarchy and a no-reinforcement control condition in a multielement design. Results for both participants indicated that mastery-level acquisition of spoken-word-to-picture relations occurred only under the identity-matching condition. Findings are discussed relative to the use of DORs to facilitate acquisition of conditional discriminations in persons with autism or other conditions who do not attend to the comparison stimuli. PMID:17970262

  12. Discrimination of carbon and nitrogen isotopes from milk to serum and vibrissae in Alaska Steller sea lions (Eumetopias jubatus)

    Stegall, V.K.; Farley, Sean D.; Rea, Lorrie D.; Pitcher, K.W.; Rye, R.O.; Kester, C.L.; Stricker, C.A.; Bern, C.R.

    2008-01-01

    Knowledge of diet-tissue stable isotope discrimination is required to properly interpret stable isotope values and to identify possible diet shifts, such as might be expected from nursing through weaning. This study compared ??13C and ??15N of paired serum and vibrissal roots with those of ingested milk (n = 52) from free-ranging Steller sea lion (Eumetopias jubatus (Schreber, 1776)) pups (1-11 months) and juveniles (14-27 months) to estimate diet-tissue discrimination. Mean 15N enrichment from ingested milk to serum was 2.1??? ?? 0.6%??? and ??15N at the root of the vibrissae (representing current growth) were not significantly different from serum values. Milk was enriched for mean 13C by 5.0??? ?? 1.0%??? and 7.3??? ?? 1.2??? relative to serum and vibrissal roots, respectively, which was due to the presence of 13C-depleted lipids in milk. This was confirmed by lipid extraction from a subset of milk and serum samples, resulting in a 5.8??? ?? 1.0??? change only in milk. This study established that vibrissal roots and serum are reflective of a milk diet with approximately 2.0??? 15N enrichment, and vibrissal roots reflect serum and lipid-extracted milk values with approximately 2.0??? 13C enrichment. These discrimination factors are important to establish for stable isotope studies assessing diet shifts. ?? 2008 NRC.

  13. Altered Carbon Isotope Discrimination of C3 Plants Under Very High pCO2 Levels

    Panetta, R. J.; Schubert, B.; Jahren, H.

    2009-12-01

    Various modeling and proxy-based reconstructions of atmospheric pCO2 levels for the last 120 Ma have estimated RCO2 as high as 12x for the Early Cretaceous, generally decreasing into the Cenozoic, and decreasing further into the Quaternary. Multiple ecological studies to assess the effect of elevated CO2 on plant biomass and δ13C value have been spurred on by recent increases in greenhouse gases, however these studies typically grow plants under only slightly elevated CO2 levels (i.e., the twenty foremost studies published since 1990 involved 550 to 750 ppm pCO2, which equals RCO2 = 1.4 to 1.9x). In order to recreate the highest pCO2 environments of the last 120 Ma, we grew radish (Raphanus sativus L.) in growth chambers that maintained controlled environmental conditions and pCO2 levels ranging from ~5 to 11x that of today’s atmosphere (1791 to 4200 ppm); upon harvest we measured total biomass and stable carbon isotope ratio (δ13Cplant) in both above and below ground plant tissue. Unlike the 1:1 relationship between stable isotopes of atmospheric CO2 (δ13Catm) and δ13Cplant observed at lower pCO2 levels (i.e., RCO2 = 1x to 3x; Jahren et al., 2008), the δ13Cplant of biomass grown at more elevated RCO2 was dependent upon δ13Catm according to the linear relationship: δ13Cplant = 1.9(δ13Cplant) - 12.2 ‰ (r2 = 0.71). Concomitantly, we see a highly significant (p sativus L. from -27.0 to -28.0 ‰ at RCO2 = 5x to 11x, respectively. We will discuss possible mechanisms for changing isotope discrimination at very high pCO2 levels that may not be operative at lower concentrations. For example, we noted a striking reduction in the variability of biomass between plants grown at the same (very high) level of pCO2. This variability (calculated as the standard deviation of the log-transformed biomass data after Poorter and Garnier, 1996) decreased by 37 % (above-ground) and 48 % (below-ground) for plants grown at RCO2 > 5x compared to plants grown at RCO2 = 1x to 3x

  14. Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris).

    Alves-Stanley, Christy D; Worthy, Graham A J

    2009-08-01

    The Florida manatee (Trichechus manatus latirostris) is a herbivorous marine mammal that occupies freshwater, estuarine and marine habitats. Despite being considered endangered, relatively little is known about its feeding ecology. The present study expands on previous work on manatee feeding ecology by providing critical baseline parameters for accurate isotopic data interpretation. Stable carbon and nitrogen isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). The mean half-life for (13)C turnover was 53 and 59 days for skin from manatees rescued from coastal and riverine regions, respectively. The mean half-life for (15)N turnover was 27 and 58 days, respectively. Because of these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8 per thousand for (13)C was calculated for long-term captive manatees on a lettuce diet. Determining both turnover rate and diet-tissue discrimination is essential in order to accurately interpret stable isotope data. PMID:19617427

  15. Greater Agronomic Water Use Efficiency in Wheat and Rice using Carbon Isotope Discrimination

    Wheat and rice are the two most important cereal crops worldwide. The potential yield of a cereal crop may be constrained by many factors, both biotic and abiotic, which may be related to the physical, chemical and biological properties of the soil itself (edaphic factors) or to the environmental conditions pertaining during the growth of the crop. Foremost among the abiotic factors is the availability of water, which is governed by climatic conditions and the ability of the soil to store available water. Together with drought, soil salinity is becoming a major stress factor limiting cereal yields globally. Soil salinization is accelerated by anthropogenic activities, including various forms of land and water mismanagement, which allow salts in geological strata to rise to the surface soil or seawater to encroach on low-lying coastal paddy soils. National programmes in crop improvement generally focus on local production problems through selection of stress resistant germplasm and traditional breeding methods, aided by modern molecular techniques. Traditional approaches are labour intensive and time consuming, with grain yield being the final arbiter of success or failure. Thus any technique that can predict yield well in advance of harvest has the potential to save considerable time, effort and money. The objective of this coordinated research project (CRP) was to evaluate carbon isotope discrimination (CID, or Δ13C) as a selection tool for yield and biomass of wheat under drought stress and rice under salt stress. This CRP was implemented following the recommendations of a consultants meeting of international experts. The research network included 11 contract holders from Algeria, Australia, Bangladesh, China (2), India, Morocco, Pakistan, Philippines, Syrian Arab Republic and Yemen, and two agreement holders from Mexico and the United States of America. The CRP was conducted in collaboration with national agricultural research systems (NARS) in Africa and Asia

  16. Selection for Greater Agronomic Water Use Efficiency in Wheat using Carbon Isotope Discrimination in Algeria

    A set of eight durum wheat genotypes was used to evaluate the relationship between carbon isotope discrimination (Δ) and grain yield under different rainfall regimes during the 2002-03 and 2003-04 seasons. The study included two old Algerian cultivars (Polonicum, Oued Zenati) and six advanced lines from the CIMMYT/ICARDA durum wheat breeding programme. The same set of genotypes was used in 2004-05 and 2005-06 to evaluate the influence of inter-annual climatic variation. These cultivars represent a wide range of agronomic characteristics. The Δ values allowed the selection of three parents to analyze the genetics of grain Δ: Waha and Mexicali (high Δ and Oued Zenati (low Δ). In 2003-04, two crosses were made, Mexicali/Waha (high Δ/high Δ and Oued Zenati/Mexicali (low Δ/high Δ). The parental cultivars and the F2 and F3 populations were then grown in 2004-05 and 2005-06 seasons. For the 2006-07 season, three categories of plants were chosen and sown from the F4 population based on their similar heading date and plant height. Estimates of realized heritability were obtained, and the degree of correlation between Δ and grain yield was estimated. At the same time, two field experiments were carried out at Ain Abessa located in the north of the high plateau, and at Beni Fouda located in the east. Data generated by the water balance model 'Budget' were used to estimate the water use efficiency of the crops. The relative yield decline expected under specific levels of water stress at different growth stages was estimated using the FAO Ky approach. (author)

  17. Carbon isotope discrimination and indirect selection for seed yield in lentil

    Carbon isotope discrimination (CID) has been proposed as a secondary trait to indirectly select for improved seed yield and water-use efficiency. To determine the effectiveness of CID to indirectly select for seed yield, 10 diverse lentil (Lens culinaris Medikus) genotypes were grown at four locations in Saskatchewan in 1992 and 1993. Samples were collected for CID determination from leaves at flowering (CIDLF), leaves at maturity (CIDML) and seed at maturity (CIDMS). Variability for CID was present, but no crossover G x E interactions were observed. A significant crossover genotype by sampling date interaction for CID resulted from a change in ranking of genotypes for CIDLF and CIDML. Seed yield was positively correlated with CIDLF and CIDML. The phenotypic correlation between seed yield and CIDLF was 0.82** (df = 8). However, this highly significant relationship was an artifact resulting from the fact that samples for CIDLF were collected for all genotypes on the same day, although PI 244026, an early maturing genotype, flowered about 15 d earlier than the other lentil lines. When PI244026 was removed from the analysis, variability in CID was greatly reduced and the correlation between CIDLF and seed yield approached zero (r = 0.22, df = 7). The correlation between seed yield and CIDML remained positive and significant, but was inconsistent across locations and years. The broad sense heritability for CIDML (0.73 +/- 0.16) was lower than the broad sense heritability for seed yield (0.98 +/- 0.029). These results suggest that under the conditions tested CID should not be used to indirectly select for seed yield in lentil

  18. Relationship between Carbon Isotope Discrimination and Grain Yield in Spring Wheat Cultivated under Different Water Regimes

    2007-01-01

    In C3 plants, carbon isotope discrimination (△) has been proposed as an indirect selection criterion for grain yield. Reported correlations between △ and grain yield however, differ highly according to the analyzed organ or tissue, the stage of sampling, and the environment and water regime. In a first experiment carried out in spring wheat during two consecutive seasons in the dry conditions of northwest Mexico (Ciudad Obregon, Sonora), different water treatments were applied,corresponding to the main water regimes available to spring wheat worldwide, and the relationships between △ values of different organs and grain yield were examined. Under terminal (post-anthesis) water stress, grain yield was positively associated with △ in grain at maturity and in leaf at anthesis, confirming results previously obtained under Mediterranean environments. Under early (pre-anthesis) water stress and residual moisture stress, the association between grain △ and yield was weaker and highly depended on the quantity of water stored in the soil at sowing. No correlation was found between △ and grain yield under optimal irrigation. The relationship between △ and grain yield was also studied during two consecutive seasons in 20 bread wheat cultivars in the Ningxia region (Northern China), characterized by winter drought(pre-anthesis water stress). Wheat was grown under rainfed conditions in two locations (Guyuan and Pengyang) and under irrigated conditions in another two (Yinchuan and Huinong). In Huinong, the crop was also exposed to salt stress.Highly significant positive associations were found between leaf and grain △ and grain yields across the environments.The relationship between △ and yield within environments highly depended on the quantity of water stored in the soil at sowing, the quantity and distribution of rainfall during the growth cycle, the presence of salt in the soil, and the occurrence of irrigation before anthesis. These two experiments

  19. Growth, Nitrogen Uptake and Carbon Isotope Discrimination in Barley Genotypes Grown under Saline Conditions

    Kurdali Fawaz

    2012-08-01

    Full Text Available The effect of different salinity levels of irrigation water (ECw range 1-12 dS/m on dry matter yield, nitrogen uptake, fertilizer nitrogen use efficiency (%NUE, stomatal conductance and carbon isotope discrimination (Δ13C‰ in three barley genotypes originating from different geographic areas (Arabi.Abiad, Syria; Pk-30-136, Pakistan and WI-2291, Australia was investigated in a pot experiment. An increase in salinity resulted in a decrease in Δ13C in all the genotypes. Increasing salinity reduced leaf stomatal conductance which was less pronounced in WI-2291 comparing to other genotypes. At high salinity level, the reduction in Δ13C corresponded to a considerable decrease in the ratio (Ci/Ca of intercellular (Ci and atmospheric (Ca partial pressures of CO2 in all the genotypes indicating that such a decrease was mainly due to the stomatal closure. Moreover, since the reduction in dry matter yield in all the genotypes grown at 12 dS/m did not exceed 50% in comparison with their controls, the photosynthetic apparatus of all studied genotypes seemed to be quit tolerant to salinity. At the moderate salinity level (8 dS/m, the enhancement of leaf dry matter yield in the WI2291 genotype might have been due to positive nutritional effects of the salt as indicated by a significant increase in nitrogen uptake and NUE. Thus, the lower Ci/Ca ratio could result mainly from higher rates of photosynthetic capacity rather than stomatal closure. On the other hand, relationships between dry matter yield or NUE and Δ13C seemed to be depending on plant genotype, plant organ and salinity level. Based on growth, nutritional and Δ13C data, selection of barley genotypes for saline environments was affected by salinity level. Therefore, such a selection must be achieved for each salinity level under which the plants have been grown.

  20. Isotope discrimination of carbon in humus of Latosols and Podzols from the Amazon region, Brazil

    Variation of 13C/12C (Δ13C) and humus composition was studied in two Podzol profiles and three Latosols of Manaus region. The relative proportions of the humic fractions were determined using a selective dissolution method. Humus of Podzols was of the same nature, with over 50% carbon in the alkaline-soluble fractions of horizons A. Sodium hydroxide extractable fractions are predominant in the upper part, and decrease in A, when pirophosplate extractable fractions become more expressive. Δ13C in Podzols is low: - 28 a 30 per mille at top of A, - 27 per mille in A2. Latosol humus is greatly different from Podzol humus; it is poor in alkaline-soluble fractions and rich in free fulvic acids and humine. The Δ13C is in average - 28 per mille in the first/upper centimeters of soil, poor in free fulvic acids and showing a small concentration of alkaline-solubles. With depth it can reach values close to - 25 per mille. Both in Podzols and Latosols, a 13C enrichment is observed when alkaline-solubles decrease and free fulvic acids concentrate, which is related to alterations in the composition of the alkaline-soluble fractions and disappearance of plant material not totally humified in horizons A. A higher concentration of 13C is noted in sub-superficial horizons of Latosols. For Podzols there is lixiviation of free fulvic acids at depth. There is an isotopic discrimination of carbon in soils, which is a consequence of the selective distribution of 13C in the different humic substances and of the humus dynamics. (M.A.)

  1. Use of Carbon Isotope Discrimination as Tool for Improving Drought Tolerance of Wheat

    As in many countries of the region, agriculture in Yemen has been strongly affected by drought conditions, and cereal production is the most concerned. So to this regard, two approaches could be adopted to solve this problem; enhancement of irrigated areas, but negative effects can also be noted as salinity (e.g. Marib, area) and development of foliar diseases. The second approaches is improvement of water use and drought resistance of wheat cultivars: this long-term strategy, which is a part of a general approach giving more attention to the sustainability of farming systems, is at the basis of the present study. Several morphophysiological mechanisms of drought tolerance involved in dehydration tolerance, As for other morphophysiological traits, the possibility of using carbon isotope discrimination (Δ) in breeding for water use efficiency (WUE) in drought prone environments is related to i) the facility of measurement, ii) the existence of variability, iii) high values of heritability, and iv) a good knowledge of eventual associations between Δ and other phenological or morphophysiological traits. The use of stable isotopes has until recently been limited because of the cost of mass spectrometers designed and the requirements for sample preparation. However, the recent linkage of an automatic gas sample preparation apparatus with a dual-inlet mass spectrometer has made the technique more convenient for fast and accurate analysis of stable isotope composition of the most important elements. The present study has been conducted to evaluate the interest of (Δ) in mature kernels as a criterion for the improvement of water use efficiency and yield under drought in tetraploid wheat species. For this purpose, T. durum Om Rabi 5 was crossed by T. polonicum 9 (Tp9) which had been found to be more droughts tolerant and to have a lower □ value of the grain. The F2 population showed a wide segregation for this last trait. Further, divergent selections were made among

  2. Isotopic discrimination and kinetic parameters of RubisCO from the marine bloom-forming diatom, Skeletonema costatum.

    Boller, A J; Thomas, P J; Cavanaugh, C M; Scott, K M

    2015-01-01

    The cosmopolitan, bloom-forming diatom, Skeletonema costatum, is a prominent primary producer in coastal oceans, fixing CO2 with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) that is phylogenetically distinct from terrestrial plant RubisCO. RubisCOs are subdivided into groups based on sequence similarity of their large subunits (IA-ID, II, and III). ID is present in several major oceanic primary producers, including diatoms such as S. costatum, coccolithophores, and some dinoflagellates, and differs substantially in amino acid sequence from the well-studied IB enzymes present in most cyanobacteria and in green algae and plants. Despite this sequence divergence, and differences in isotopic discrimination apparent in other RubisCO enzymes, stable carbon isotope compositions of diatoms and other marine phytoplankton are generally interpreted assuming enzymatic isotopic discrimination similar to spinach RubisCO (IB). To interpret phytoplankton δ(13) C values, S. costatum RubisCO was characterized via sequence analysis, and measurement of its KCO2 and Vmax , and degree of isotopic discrimination. The sequence of this enzyme placed it among other diatom ID RubisCOs. Michaelis-Menten parameters were similar to other ID enzymes (KCO2 = 48.9 ± 2.8 μm; Vmax = 165.1 ± 6.3 nmol min(-1 ) mg(-1) ). However, isotopic discrimination (ε = [(12) k/(13) k - 1] × 1000) was low (18.5‰; 17.0-19.9, 95% CI) when compared to IA and IB RubisCOs (22-29‰), though not as low as ID from coccolithophore, Emiliania huxleyi (11.1‰). Variability in ε-values among RubisCOs from primary producers is likely reflected in δ(13) C values of oceanic biomass. Currently, δ(13) C variability is ascribed to physical or chemical factors (e.g. illumination, nutrient availability) and physiological responses to these factors (e.g. carbon-concentrating mechanisms). Estimating the importance of these factors from δ(13) C measurements requires an accurate ε-value, and a mass

  3. Data acquisition electronics for gamma ray emission tomography using width-modulated leading-edge discriminators

    We present a new high-performance and low-cost approach for implementing radiation detection acquisition systems. The basic elements used are charge-integrating ADCs and a set of components encapsulated in an HDL (hardware definition language) library which makes it possible to implement several acquisition tasks such as time pickoff and coincidence detection using a new and simple trigger technique that we name WMLET (width-modulated leading-edge timing). As proof of concept, a 32-channel hybrid PET/SPECT acquisition system based on these elements was developed and tested. This demonstrator consists of a master module responsible for the generation and distribution of trigger signals, 2 x 16-channel ADC cards (12-bit resolution) for data digitization and a 32-bit digital I/O PCI card for handling data transmission to a personal computer. System characteristics such as linearity, maximum transmission rates or timing resolution in coincidence mode were evaluated with test and real detector signals. Imaging capabilities of the prototype were also evaluated using different detector configurations. The performance tests showed that this implementation is able to handle data rates in excess of 600k events s-1 when acquiring simultaneously 32 channels (96-byte events). ADC channel linearity is >98.5% in energy quantification. Time resolution in PET mode for the tested configurations ranges from 3.64 ns FWHM to 7.88 ns FWHM when signals from LYSO-based detectors are used. The measured energy resolution matched the expected values for the detectors evaluated and single elements of crystal matrices can be neatly separated in the acquired flood histograms.

  4. Data acquisition electronics for gamma ray emission tomography using width-modulated leading-edge discriminators

    Lage, E; Tapias, G; Villena, J; Desco, M; Vaquero, J J, E-mail: desco@mce.hggm.e [Unidad de Medicina y CirugIa Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain)

    2010-08-07

    We present a new high-performance and low-cost approach for implementing radiation detection acquisition systems. The basic elements used are charge-integrating ADCs and a set of components encapsulated in an HDL (hardware definition language) library which makes it possible to implement several acquisition tasks such as time pickoff and coincidence detection using a new and simple trigger technique that we name WMLET (width-modulated leading-edge timing). As proof of concept, a 32-channel hybrid PET/SPECT acquisition system based on these elements was developed and tested. This demonstrator consists of a master module responsible for the generation and distribution of trigger signals, 2 x 16-channel ADC cards (12-bit resolution) for data digitization and a 32-bit digital I/O PCI card for handling data transmission to a personal computer. System characteristics such as linearity, maximum transmission rates or timing resolution in coincidence mode were evaluated with test and real detector signals. Imaging capabilities of the prototype were also evaluated using different detector configurations. The performance tests showed that this implementation is able to handle data rates in excess of 600k events s{sup -1} when acquiring simultaneously 32 channels (96-byte events). ADC channel linearity is >98.5% in energy quantification. Time resolution in PET mode for the tested configurations ranges from 3.64 ns FWHM to 7.88 ns FWHM when signals from LYSO-based detectors are used. The measured energy resolution matched the expected values for the detectors evaluated and single elements of crystal matrices can be neatly separated in the acquired flood histograms.

  5. Relationships between transpiration efficiency and carbon isotope discrimination in chickpea (C. arietinum L

    J Kashiwagi

    2006-08-01

    Full Text Available Greenhouse pot experiments were carried out in 2004 to check if there are any variations available for carbon isotope discrimination (d13C, to investigate the relationship between d13C and transpiration efficiency (TE, and to ascertain the possibility of using d13C as a surrogate for TE measurements. Ten chickpea genotypes (Annigeri, ICC 10448, ICC 13219, ICC 14199, ICC 1882, ICC 283, ICC 4958, ICC 5337, ICC 5680 and ICC 8261 with contrasting growth duration, type (desi or kabuli, growth habit and root system were used. In the well-watered pots (control, the water lost in a day was added back, whereas in the water stress-imposed pots the water, which is equivalent to 70-90% of daily transpiration, was given to avoid the rapid build up of soil water stress. There were significant differences in d13C among the 10 genotypes and the d13C in stress condition was significantly higher than that in the well-wateredcontrol. Genotype ICC 5337 showed the highest d13C (-26.0% in the stress condition. ICC 4958, a well-known drought-resistant cultivar, had superior d13C value than the other genotypes. ICC 4958 ranked second (-27.2% under stress condition and the first (-28.4% in the well-watered control condition. The genotype by irrigation (G x I interaction was significant for d13C. Among 10 genotypes, a significant difference in TE was observed in both irrigated and stress conditions. Genotype ICC 5337 showed the highest TE irrespective of irrigations of 3.9 g/kg under stress and 2.8 g/kg under well-watered control. The TE under stress was significantly higher than the TE under the control. There was a significant correlation in TE between the stress and control conditions and there was no G x I interaction observed. A significant positive correlation between d13C and TE was observed under the stress condition. However, no significant correlation was observed between d13C and TE when the plants were grown under well-watered conditions. The results shows

  6. Carbon isotope discrimination is positively correlated with grain yield and dry matter production in field-grown wheat

    Carbon isotope discrimination (Δ) is a measure of the ratio of the intercellular and atmospheric partial pressures of CO2. Variation in Δ within some C3 species, including wheat (Triticum aestivum L.), has recently been correlated with variation in water use efficiency of droughted plants grown in the glasshouse. The objectives of this study were to assess genotypic variation in a larger group of wheat genotypes grown at three locations, and to determine the relationship between yield of field-grown plants and Δ when water was not a limitation to growth. Twenty-four bread wheat genotypes, one durum (Triticum turgidum L. durum), and two triticale genotypes (x Triticosecale rimpaui Wittm.) were grown in replicated plots at two locations in southern New South Wales, Australia, in 1984. The growing season had above average rainfall, especially in the period preceding antbesis. Carbon isotope discrimination was measured on stem material for each plot. Final aboveground biological yield and grain yield were also measured. There was substantial genotypic variation in Δ. Genotypic ranking for Δ was consistent across field sites and between field-grown plants and plants grown in pots at another location. A potential source of variation in Δ is variation in stomatal conductance. For pot-grown plants, the relationship between Δ and total leaf conductance was poor. However, Δ and conductance of the abaxial leaf surface were positively correlated. Under field conditions of nonlimiting water, biological yield and grain yield were both positively correlated with Δ. This latter result indicates that carbon isotope discrimination may be used to select for increased yield in wheat. (author)

  7. Regional variations in the lead isotopic composition of galena from southern Korea with implications for the discrimination of lead provenance

    Jeong, Youn-Joong; Cheong, Chang-sik; Shin, Dongbok; Lee, Kwang-Sik; Jo, Hui Je; Gautam, Mukesh Kumar; Lee, Insung

    2012-11-01

    This study presents a comprehensive database (n = 215) of lead isotopes in galena from the southern Korean peninsula using new and published data. Of the 69 metal mines examined, predominantly skarn- and hydrothermal-type Pb-Zn-Au-Ag-Cu deposits were observed and were associated with Mesozoic magmatic activities. Galena samples from each geotectonic unit showed discrete lead isotopic signatures. The Gyeongsang basin samples were characteristically unradiogenic and had restricted variations in lead isotopic composition (206Pb/204Pb = 18.16-18.59, 207Pb/204Pb = 15.48-15.64, 208Pb/204Pb = 37.87-38.77). Their 208Pb/204Pb range indicated an involvement of source materials less thorogenic than the associated granites. The galena samples from Cambro-Ordovician carbonate rocks of the northeastern Yeongnam massif and eastern Taebaeksan basin had the most radiogenic 206Pb/204Pb (19.28 ± 0.14) and 207Pb/204Pb (15.833 ± 0.027) ratios. Their lead isotopic trend indicated a combined contribution of ore lead from granitic magmas, Precambrian basements, and overlain host rocks. Less radiogenic galena samples from the middle to southwestern parts of the Yeongnam massif and Okcheon belt showed limited lead isotopic variations (206Pb/204Pb = 18.332 ± 0.065, 207Pb/204Pb = 15.693 ± 0.012, 208Pb/204Pb = 38.93 ± 0.07 on average), probably resulted from mixing with a common crustal basement. The differences in lead isotopes between the radiogenic and unradiogenic groups from the Yeongnam massif and Okcheon belt may reflect the spatial dissimilarity of involved crustal rocks. The old crust appears to have significantly contributed ore lead to galenas from the western Gyeonggi massif, but the geochronological meaning of their steep 207Pb/204Pb-206Pb/204Pb trend is not clear. The comprehensive database constructed by the present study suggests that lead province in the southern Korean peninsula may be subdivided into four discrete zones. Linear discriminant analysis showed that more

  8. The use of carbon-isotope discrimination to screen wheat cultivars for tolerance of salinity and drought

    Stable carbon isotope determinations provide time-integrated measures of plant physiological activities and plant interactions with the environment. In these experiments the effects of soil salinity on carbon isotope discrimination were studied. The classical method of selection of wheat cultivars based on yield performance under saline conditions has been largely unsuccessful. Also, physiological traits such as dry matter (DM), water use efficiency (WUE), and harvest index (HI) have been used as alternatives to screening for yield. Carbon-13 discrimination (Δ) is an integrated measure of the response of photosynthetic gas exchange to environmental variables such as water availability, light, humidity, and salinity, and has been shown to be a useful tool in the selection of cultivars for drought tolerance. Despite similarities between the effects of water and salt stresses on plant growth, few attempts have been made to quantify the effect of salinity on Δ, and its potential as a breeding selection characteristic, aimed at increasing grain yield under saline conditions. The objectives of this experiment were to study the effect of soil salinity on Δ in salt- and drought-tolerant wheat cultivars under well watered and water-limiting conditions, and to evaluate the relationship between DM, WUE, and HI under the two levels of moisture

  9. Evaluation of the Use of Carbon Isotope Discrimination as a Selection Tool of Perennial Fodder Species for Temporary Pastures

    Nicusor Flavius SIMA

    2011-11-01

    Full Text Available Estimation of the relationship between carbon isotope discrimination (Δ13C in perennial fodder plants and various factors such as climate, fertilization and soil could contribute to a better selection and/or improvement of genotype of fodder species. Theoretical models of carbon isotope discrimination in plants indicate a linear relationship between Δ13C and CO2 partial pressures ratio (pi/pa from the intercellular spaces (pi of CO2 in leaves and from the atmosphere (pa. It is also known that between pi parameter and water-use efficiency (WUE there is a negative correlation. Eight perennial fodder legume and grass mixtures were cultivated on three levels of fertilization in order to assess mixtures for pastures that can provide sustainable quantitative and qualitative yields. The species, which composed the mixtures, were also cultivated as pure crops on the same fertilization conditions. The results of this study indicated that in five of the six species, which composed the mixture with the highest yield, pi/pa values decreased while fertilization doses increased, most likely as a result of variation in water-use efficiency.

  10. Discriminative study of a potato (Solanum tuberosum L.) cultivation region by measuring the stable isotope ratios of bio-elements.

    Chung, Ill-Min; Kim, Jae-Kwang; Jin, Yong-Ik; Oh, Yong-Taek; Prabakaran, Mayakrishnan; Youn, Kyoung-Jin; Kim, Seung-Hyun

    2016-12-01

    Compared to other foods, the use of common bio-elements to identify the geographical origin of potato remains limited. Thus, this study aimed to verify whether the cultivation regions of raw potato tubers could be determined by the stable isotope composition analysis of bio-elements. δ(13)CVPDB and δ(15)NAIR in potato were influenced by region and cultivar, whereas δ(18)OVSMOW and δ(34)SVCDT were only influenced by region (p<0.0001). A two-dimensional plot of δ(18)OVSMOW and δ(34)SVCDT effectively distinguished between high and low altitude regions, and also reliably discriminated Wanju, Haenam, and Boseong cultivars in low altitude regions. δ(34)SVCDT was the main component that was responsible for the separation of samples in the principal component analysis (eigenvector of -0.6209) and orthogonal projection to latent structure-discriminant analysis (VIP value of 1.0566). In conclusion, this study improves our understanding of how the isotope composition of potato tubers varies with respect to cultivation regions and cultivars. PMID:27374505

  11. Application of carbon isotope discrimination for improving crop performance in water-limited and saline environments

    Full text: The work of a breeding program aimed at improving the water-use efficiency and yield of wheat varieties grown in Australia's rainfed cropping systems is described. The work could be divided into three main themes covering traits associated with: (1) Pushing more of the available water through the crop rather than have it wasted as evaporation from the soil surface or drainage beyond the root-zone. (2) Acquiring more carbon (biomass) in exchange for the water that is transpired by the crop. (3) Partitioning more of the achieved biomass into the desired product, marketable grain. To increase the amount of water transpired by the crop, research is focussed on developing wheats with a faster rate of leaf area growth. This can be achieved by breeding wheats with longer coleoptiles, to ensure a dense plant stand, and by breeding wheats with greater early vigour, to restrict loss of water by direct evaporation from the soil surface. Another important component of crop water-use efficiency is transpiration efficiency (TE), i.e. the amount of biomass produced per unit water transpired. High crop TE is favoured by vigorous growth during those periods of the growing season when evaporative demand is low. High crop TE may also be favoured by selecting genotypes with high leaf-level TE. Carbon isotope discrimination (Δ) provides a measure of relative variation in leaf-level TE among genotypes of C3 species. This variation in TE may contribute to greater water-use efficiency and yield of C3 crop species grown in water-limited environments. A summary is provided of studies investigating the relationship between grain yield and Δ in bread wheat in Australia. These studies have revealed that there is large variation in Δ among Australian bread wheat cultivars. When measured on leaves sampled from well-watered plants at full tillering, variation in Δ among Australian wheats exceeds 2 per mille. Among wheat genotypes, variation in . is negatively correlated with water

  12. Carbon Isotope Discrimination as a Selection Tool for High Yielding Wheat Genotypes for Water Limited Environments

    130 bread wheat (Triticum aestivum L.) lines obtained from CIMMYT and local sources were grown to maturity during the 2004-2005 and 2005-2006 seasons under irrigated conditions without water stress. Carbon isotope discrimination (CID, Δ13C or Δ) was determined on early leaf and grain samples. 111 genotypes were well adapted. Grain yield was positively and significantly correlated with harvest index. Six genotypes with leaf Δ values 18-18.99 per mille were ranked low, 55 with Δ values 19-20.99 per mille were ranked medium, 10 genotypes with Δ values 22-22.99 per mille were ranked high, and one with a Δ value of 23.01 per mille was ranked very high. Due to insufficient variability in Δ among these genotypes, a crossing and generation programme was initiated to evolve new genotypes with a larger variation in Δ. The advancement phase is in progress. Meanwhile, eight genotypes were selected from the 111 adapted varieties based upon grain yield and variation in Δ, for testing under four soil moisture regimes, including well-, medium-, low watered and stored soil moisture conditions. The aim was to identify promising lines for target environments and to establish relationships between grain yield and Δ, water use efficiency (WUE) and other plant parameters. All 8 genotypes exhibited higher leaf than grain Δ under the four water regimes, with a variation of 1.35 and 0.91 per mille, respectively. Water stress reduced both leaf and grain Δ, which were significantly and positively correlated. An increase in soil moisture stress decreased grain yield in all genotypes. Grain yield and grain WUE were positively correlated with leaf and grain Δ, harvest index, spike length and 1000 grain weight, and were negatively correlated with number of tillers and time to heading. Sitta and FD-83 genotypes had high yields with greater increases in WUE under water stress. e.g. Sitta produced the highest grain yield of 4.4 t ha-1 with the highest grain WUE of 16.99 kg ha-1 mm-1

  13. Measurement of isotopic uranium in water for compliance monitoring by liquid scintillation counting with alpha/beta discrimination

    A simple and inexpensive method is described for analysis of uranium (U) activity and mass in water by liquid scintillation counting using α/β discrimination. This method appears to offer a solution to the need for an inexpensive protocol for monitoring U activity and mass simultaneously and an alternative to the potential inaccuracy involved when depending on the mass-to-activity conversion factor or activity screen. U is extracted virtually quantitatively into 20 ml extractive scintillator from a 1-ell aliquot of water acidified to less than pH 2. After phase separation, the sample is counted for a 20-minute screening count with a minimum detection level of 0.27 pCi ell -1. α-particle emissions from the extracted U are counted with close to 100% efficiency with a Beckman LS6000 LL liquid scintillation counter equipped with pulse-shape discrimination electronics. Samples with activities higher than 10 pCi ell -1 are recounted for 500-1000 minutes for isotopic analysis. Isotopic analysis uses events that are automatically stored in spectral files and transferred to a computer during assay. The data can be transferred to a commercially available spreadsheet and retrieved for examination or data manipulation. Values for three readily observable spectral features can be rapidly identified by data examination and substituted into a simple formula to obtain 234U/238U ratio for most samples. U mass is calculated by substituting the isotopic ratio value into a simple equation. The utility of this method for the proposed compliance monitoring of U in public drinking water supplies was field tested with a survey of drinking water from Texas supplies that had previously been known to contain elevated levels of gross α activity. U concentrations in 32 samples from 27 drinking water supplies ranged from 0.26 to 65.5 pCi ell -1, with seven samples exceeding the proposed Maximum Contaminant Level

  14. Carbon isotope composition of latex does not reflect temporal variations of photosynthetic carbon isotope discrimination in rubber trees (Hevea brasiliensis).

    Kanpanon, Nicha; Kasemsap, Poonpipope; Thaler, Philippe; Kositsup, Boonthida; Gay, Frédéric; Lacote, Régis; Epron, Daniel

    2015-11-01

    Latex, the cytoplasm of laticiferous cells localized in the inner bark of rubber trees (Hevea brasiliensis Müll. Arg.), is collected by tapping the bark. Following tapping, latex flows out of the trunk and is regenerated, whereas in untapped trees, there is no natural exudation. It is still unknown whether the carbohydrates used for latex regeneration in tapped trees is coming from recent photosynthates or from stored carbohydrates, and in the former case, it is expected that latex carbon isotope composition of tapped trees will vary seasonally, whereas latex isotope composition of untapped trees will be more stable. Temporal variations of carbon isotope composition of trunk latex (δ(13)C-L), leaf soluble compounds (δ(13)C-S) and bulk leaf material (δ(13)C-B) collected from tapped and untapped 20-year-old trees were compared. A marked difference in δ(13)C-L was observed between tapped and untapped trees whatever the season. Trunk latex from tapped trees was more depleted (1.6‰ on average) with more variable δ(13)C values than those of untapped trees. δ(13)C-L was higher and more stable across seasons than δ(13)C-S and δ(13)C-B, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. δ(13)C-B was lower in tapped than in untapped trees, increasing from August (middle of the rainy season) to April (end of the dry season). Differences in δ(13)C-L and δ(13)C-B between tapped and untapped trees indicated that tapping affects the metabolism of both laticiferous cells and leaves. The lack of correlation between δ(13)C-L and δ(13)C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping. PMID:26358051

  15. The key factor limiting plant growth in cold and humid alpine areas also plays a dominant role in plant carbon isotope discrimination

    Xu, Meng; Wang, Guoan; Li, Xiaoliang; Cai, Xiaobu; Li, Xiaolin; Christie, Peter; Zhang, Junling

    2015-01-01

    Many environmental factors affect carbon isotope discrimination in plants, yet the predominant factor influencing this process is generally assumed to be the key growth-limiting factor. However, to our knowledge this hypothesis has not been confirmed. We therefore determined the carbon isotope composition (δ13C) of plants growing in two cold and humid mountain regions where temperature is considered to be the key growth-limiting factor. Mean annual temperature (MAT) showed a significant impact on variation in carbon isotope discrimination value (Δ) irrespective of study area or plant functional type with either partial correlation or regression analysis, but the correlation between Δ and soil water content (SWC) was usually not significant. In multiple stepwise regression analysis, MAT was either the first or the only variable selected into the prediction model of Δ against MAT and SWC, indicating that the effect of temperature on carbon isotope discrimination was predominant. The results therefore provide evidence that the key growth-limiting factor is also crucial for plant carbon isotope discrimination. Changes in leaf morphology, water viscosity and carboxylation efficiency with temperature may be responsible for the observed positive correlation between Δ and temperature. PMID:26579188

  16. Carbon isotope discrimination and water-use efficiency in native plants of the north-central Rockies

    Stable carbon isotope composition was determined on leaves of woody plants sampled along an 800—km transect on the western flank of the Rocky Mountains at altitudes ranging from 610 to 2650 m above mean sea level. Discrimination decreased by 1.20 ± 0.11% (mean ± 1 se) per km of altitude (n = 15, F1,13 = 127.8, P < 0.0001). The change in discrimination was just sufficient to maintain a constant CO2 partial pressure gradient from ambient air to the intercellular spaces within the leaf for both deciduous (P = 0.60) and evergreen (P = 0.90) species. However, the CO2 gradient so maintained was significantly steeper among evergreen (11.31 ± 0.14 Pa) than among deciduous (9.64 ± 0.14 Pa) species (t = 8.4, 27 df, P < 00001). As a consequence, the evergreens had lower discrimination than the deciduous species at any given altitude. After the data were corrected for altitude, further analysis revealed significant differences in discrimination and in CO2 partial pressure gradient among species. Thuja plicata (western red—cedar), a scale—leaved evergreen, had lowest mean discrimination (16.67 ± 0.50%, n = 4) and the steepest CO2 gradient from ambient to intercellular spaces (14.5 ± 0.5 Pa). Larix occidentalis (western larch), a deciduous conifer, had the highest discrimination (20.95 ± 0.34%, n = 9) and the flattest CO2 gradient (8.3 ± 0.4 Pa). A simple model of water—use efficiency predicted that evergreen species would average 18 ± 2% higher in water—use efficiency at any given altitude and that mean water—use efficiency would triple across a 2000—m altitude gradient. The difference between evergreen and deciduous species is attributable to variation in the CO2 partial pressure gradient, but the tripling with altitude was almost exclusively a consequence of reduced evaporative demand. (author)

  17. Oxygen isotope composition of evapotranspiration and its relation to C4 photosynthetic discrimination

    The oxygen isotope ratio of water (18 O-H2O) and carbon dioxide (18 O-CO2) is an important signal of global change and can provide constraints on the coupled carbon-water cycle. Here, simultaneous observations of 18O-H2O (liquid and vapor phases) and 18 O-CO2 were used to investigate the relation be...

  18. CO2 uptake of a mature Acacia mangium plantation estimated from sap flow measurements and stable carbon isotope discrimination

    Wang, H.; Zhao, P.; Zou, L. L.; McCarthy, H. R.; Zeng, X. P.; Ni, G. Y.; Rao, X. Q.

    2014-03-01

    A simple, nondestructive method for the estimation of canopy CO2 uptake is important for understanding the CO2 exchange between forest and atmosphere. Canopy CO2 uptake (FCO2) of a subtropical mature A. mangium plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ) in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow-based canopy stomatal conductance (Gs) was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca), although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, we obtained an acceptable estimate of FCO2 compared to other estimates. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapor pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 gC m-2 d-1) approached the lower range of values for subtropical mixed forests, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or carbon allocation studies, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches likely reflected variability due to leaf position and age, which should be reduced for the combined sap flux and isotope technique, as it uses canopy average values of Gs and Ci/Ca.

  19. CO2 uptake of a mature Acacia mangium plantation estimated from sap flow measurements and stable carbon isotope discrimination

    H. Wang

    2013-07-01

    Full Text Available Canopy CO2 uptake (FCO2 of a subtropical mature extit{A. mangium} plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow based canopy stomatal conductance (Gs was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca, although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, an acceptable estimate of FCO2 was obtained. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapour pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 g C m−2 day−1 approached the lower range of values for subtropical mixed forest, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or component carbon analysis, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches reflected variability due to leaf position and age, which could be reduced for sap flux/stable isotope, which uses canopy average values of Gs and Ci/Ca.

  20. From food to offspring down: tissue-specific discrimination and turn-over of stable isotopes in herbivorous waterbirds and other avian foraging guilds.

    Hahn, Steffen; Hoye, Bethany J; Korthals, Harry; Klaassen, Marcel

    2012-01-01

    Isotopic discrimination and turn-over are fundamental to the application of stable isotope ecology in animals. However, detailed information for specific tissues and species are widely lacking, notably for herbivorous species. We provide details on tissue-specific carbon and nitrogen discrimination and turn-over times from food to blood, feathers, claws, egg tissues and offspring down feathers in four species of herbivorous waterbirds. Source-to-tissue discrimination factors for carbon (δ¹³C) and nitrogen stable isotope ratios (δ¹⁵N) showed little variation across species but varied between tissues. Apparent discrimination factors ranged between -0.5 to 2.5‰ for δ¹³C and 2.8 to 5.2‰ for δ¹⁵N, and were more similar between blood components than between keratinous tissues or egg tissue. Comparing these results with published data from other species we found no effect of foraging guild on discrimination factors for carbon but a significant foraging-guild effect for nitrogen discrimination factors.Turn-over of δ¹³C in tissues was most rapid in blood plasma, with a half-life of 4.3 d, whereas δ¹³C in blood cells had a half-life of approximately 32 d. Turn-over times for albumen and yolk in laying females were similar to those of blood plasma, at 3.2 and 6.0 d respectively. Within yolk, we found decreasing half-life times of δ¹³C from inner yolk (13.3 d) to outer yolk (3.1 d), related to the temporal pattern of tissue formation.We found similarities in tissue-specific turn-over times across all avian species studied to date. Yet, while generalities regarding discrimination factors and tissue turn-over times can be made, a large amount of variation remains unexplained. PMID:22312422

  1. Isotopic Tracking to Discriminate Contaminants Accumulation in Sediment Profiles in El-Manzala Lake

    Monitoring of Egyptian coastal area is an important issue with respect to contaminants transport process and susceptibility for accumulation and settlement in bottom lakes sediment. Studying long record of organic matter (OM) and trace elements as proxy indicator for past changes along sedimentary profiles with carbon and nitrogen isotopes have been applied on the highest polluted wetland-Manzala Lake. Nine sediment cores within 45-100 cm depth were collected and analyzed. High depositions of major and trace elements were found at the central, southeastern, and northeastern sectors particularly within the shallow layers of the sediment cores. These high increments in metals and OM concentration are strongly correlated with the high flux of pollution, mass sedimentation rate, and circulation pattern in these sectors of the lake. The results, also, point to the recent increase of the industrial waste input from Port- Said City, where clay minerals in sediment profiles act as traps for trace metals. In addition, there is a large area of the lake in the west and southwestern sectors, where there is virtually slow depositional process as indicated by δ13C and δ15N. This emphasizes high retention time of suspended matter and different stages of di genesis process. The isotopic signals reflect the dominance of terrestrial deposits as a source of organic matter with minor marine input as presented in the central and northern sector of the lake. The higher isotopic variations in sedimentary profiles in the western and southwestern sectors than those observed in the southern and eastern sectors reflect temporal and spatial alterations under oxic-anoxic conditions. Microbial decomposition processes during the breakdown and preservation of organic matter are the reasons for isotopic variations in sedimentary profiles. These variations reflect heterogeneities in depositional process and the difference in sedimentation rate along the lake. These results are considered as a

  2. Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

    A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip

  3. Data acquisition system for optimization and control of the processes in isotopic exchange columns

    The increase of tritium level concentration in heavy water raises problems in operation of nuclear reactors as well as for the environment. Therefore, most owners of Candu reactors are making researches and develop technologies for heavy water detritiation. As it is well known after several years of functioning the level radioactivity in the moderator attains a value that imposes heavy water detritiation. The technology developed at the Institute of Cryogenics and Isotope Separations is based on catalytic isotope exchange between water and hydrogen gas both carrying various isotopes of hydrogen: normal hydrogen, deuterium, and tritium. This isotope exchange is followed by cryogenic distillation separating the various isotopes of hydrogen gas. The detritiation process was simulated using as working fluids water with a small content of deuterium and a gaseous mixture of hydrogen and deuterium. The experimental data obtained on catalyst isotopic exchange column on tritium or deuterium transfer from water to gas and the mathematical model to simulate the column behavior allowed to determine the performance of isotopic exchange column. After interpreting the experimental data, we determined the reaction rate constants, which characterize the isotopic exchange for distillation, and catalytic process, respectively, as a function of the experimental conditions: tritium or deuterium concentration in the feed water of the system, distillation and catalyst isotope exchange. The reactions governing the isotopic exchange between tritiated heavy water and deuterium (DTO-D2), and deuterated -water and hydrogen, respectively are given. The experimental dates obtained in the tritium isotopic exchange process proved that the reaction rate constants are half of the deuterium reaction rate constants. These experimental data and the computed values of the reaction rate constants represent the features of catalyst performances of deuterium and tritium isotopic exchange. The mathematical

  4. Carbon isotope discrimination by photosynthesis: implications for the bio- and geosciences

    Land plants are depleted in the heavy isotopes of natural carbon 14C (radioactive) and 13C (stable) compared with the isotope composition of atmospheric CO2. These depletions can be assayed on milligram quantities of organic matter converted to CO2 and analyzed in a double inlet-double collector mass spectrometer, the ratio 13C/12C usually being expressed as delta 13C vs. PDB, in per mil (0/00). The delta value in higher plants ranges between -39 and -9 0/00. The variations of this delta value are mainly determined by the type of carbon fixation reaction, e.g., the delta value allows us to distinguish between C3 (Calvin-Benson) plants typically -28 0/00, and C4 (Hatch-Slack) plants typically -13 0/00. These corrections are important for archaeologic and groundwater dating. Since the carbon delta values persist in dead and ancient plant remains such as wood, pollen, peat, soil, coal and oil, it is possible to investigate previous environmental conditions, past climate, paleoecology, plant interaction with the environment and evolution of photosynthetic mechanisms. The delta value also tags the commercial products derived from plants and animals allowing their origin to be traced in investigations of fraud. Some of these naturally labeled products have medical applications

  5. Effects of soil strength on the relation of water-use efficiency and growth to carbon isotope discrimination in wheat seedlings

    The ratio of carbon accumulation to transpiration, W, of wheat (Triticum aestivum L.) seedlings increased with increasing soil strength, measured as soil penetrometer resistance, and this was already apparent at the two leaf stage. The ratio was negatively correlated with carbon isotope discrimination, in accord with theory. This means that decrease in intercellular partial pressure of CO2 accounted for an important part of the increase in W with increasing soil strength. Despite a lower CO2 concentration in the leaves at high soil strength, assimilation rate per unit leaf area was enhanced. Greater ribulose 1,5-bisphosphate carboxylase activity confirmed that photosynthetic capacity was actually increased. This pattern of opposite variation of assimilation rate and of stomatal conductance is unusual. The ratio of plant carbon mass to leaf area increased markedly with increasing soil strength, mainly because of a greater investment of carbon into roots than into shoots. A strong negative correlation was found between this ratio and carbon isotope discrimination. For a given increase in discrimination, decrease in carbon mass per leaf area was proportionally larger than decrease in assimilation rate, so that relative growth rate was positively correlated to carbon isotope discrimination

  6. Application of carbon isotope for discriminating sources of soil CO2 in karst area, Guizhou

    黎廷宇; 王世杰

    2001-01-01

    Using carbon isotope of soil CO2 this paper discussed the sources of soil CO2 in karst area, Guizhou Province, China. Oxidation-decomposition of organic matter, respiration of plant root and activity of microbe are thought to be the major sources of soil CO2. However, in karst area, the contribution of dissolution of underlying carbonate rock to soil CO2 should be considered as in acidic environment. Atmospheric CO2 is the major composition of soil CO2 in surface layer of soil profiles and its proportion in soil CO2 decreases with increase of soil depth. CO2 produced by dissolution of carbonate rock contributes 34%-46% to soil CO2 below the depth of 10cm in the studied soil profiles covered by grass.

  7. Complex Physiological Response of Norway Spruce to Atmospheric Pollution - Decreased Carbon Isotope Discrimination and Unchanged Tree Biomass Increment.

    Čada, Vojtěch; Šantrůčková, Hana; Šantrůček, Jiří; Kubištová, Lenka; Seedre, Meelis; Svoboda, Miroslav

    2016-01-01

    Atmospheric pollution critically affects forest ecosystems around the world by directly impacting the assimilation apparatus of trees and indirectly by altering soil conditions, which subsequently also leads to changes in carbon cycling. To evaluate the extent of the physiological effect of moderate level sulfate and reactive nitrogen acidic deposition, we performed a retrospective dendrochronological analysis of several physiological parameters derived from periodic measurements of carbon stable isotope composition ((13)C discrimination, intercellular CO2 concentration and intrinsic water use efficiency) and annual diameter increments (tree biomass increment, its inter-annual variability and correlation with temperature, cloud cover, precipitation and Palmer drought severity index). The analysis was performed in two mountain Norway spruce (Picea abies) stands of the Bohemian Forest (Czech Republic, central Europe), where moderate levels of pollution peaked in the 1970s and 1980s and no evident impact on tree growth or link to mortality has been reported. The significant influence of pollution on trees was expressed most sensitively by a 1.88‰ reduction of carbon isotope discrimination (Δ(13)C). The effects of atmospheric pollution interacted with increasing atmospheric CO2 concentration and temperature. As a result, we observed no change in intercellular CO2 concentrations (Ci), an abrupt increase in water use efficiency (iWUE) and no change in biomass increment, which could also partly result from changes in carbon partitioning (e.g., from below- to above-ground). The biomass increment was significantly related to Δ(13)C on an individual tree level, but the relationship was lost during the pollution period. We suggest that this was caused by a shift from the dominant influence of the photosynthetic rate to stomatal conductance on Δ(13)C during the pollution period. Using biomass increment-climate correlation analyses, we did not identify any clear pollution

  8. Complex Physiological Response of Norway Spruce to Atmospheric Pollution – Decreased Carbon Isotope Discrimination and Unchanged Tree Biomass Increment

    Čada, Vojtěch; Šantrůčková, Hana; Šantrůček, Jiří; Kubištová, Lenka; Seedre, Meelis; Svoboda, Miroslav

    2016-01-01

    Atmospheric pollution critically affects forest ecosystems around the world by directly impacting the assimilation apparatus of trees and indirectly by altering soil conditions, which subsequently also leads to changes in carbon cycling. To evaluate the extent of the physiological effect of moderate level sulfate and reactive nitrogen acidic deposition, we performed a retrospective dendrochronological analysis of several physiological parameters derived from periodic measurements of carbon stable isotope composition (13C discrimination, intercellular CO2 concentration and intrinsic water use efficiency) and annual diameter increments (tree biomass increment, its inter-annual variability and correlation with temperature, cloud cover, precipitation and Palmer drought severity index). The analysis was performed in two mountain Norway spruce (Picea abies) stands of the Bohemian Forest (Czech Republic, central Europe), where moderate levels of pollution peaked in the 1970s and 1980s and no evident impact on tree growth or link to mortality has been reported. The significant influence of pollution on trees was expressed most sensitively by a 1.88‰ reduction of carbon isotope discrimination (Δ13C). The effects of atmospheric pollution interacted with increasing atmospheric CO2 concentration and temperature. As a result, we observed no change in intercellular CO2 concentrations (Ci), an abrupt increase in water use efficiency (iWUE) and no change in biomass increment, which could also partly result from changes in carbon partitioning (e.g., from below- to above-ground). The biomass increment was significantly related to Δ13C on an individual tree level, but the relationship was lost during the pollution period. We suggest that this was caused by a shift from the dominant influence of the photosynthetic rate to stomatal conductance on Δ13C during the pollution period. Using biomass increment-climate correlation analyses, we did not identify any clear pollution

  9. Applications of optical spectroscopy and stable isotope analyses to organic aerosol source discrimination in an urban area

    Mladenov, N.; Alados-Arboledas, L.; Olmo, F. J.; Lyamani, H.; Delgado, A.; Molina, A.; Reche, I.

    2011-02-01

    Understanding the chemical character of organic aerosols is extremely important for evaluating their role in climate forcing and human respiratory health. Aerosol columnar properties retrieved by sun photometry represent a large dataset of information about the physical and light absorbing and scattering properties of the total aerosol, but lack more detailed chemical information about the organic fraction of atmospheric particulate matter. To obtain additional information about relationships between organic aerosol sources and columnar properties, we simultaneously examined stable isotope properties of PM 10 aerosols from urban (Granada, Spain) and remote (Sierra Nevada, Spain) sites and diesel exhaust, spectroscopic properties of water soluble organic carbon (WSOC) of PM 10 aerosols, and sun photometry measurements. We demonstrated that C and N stable isotopes and parameters from UV-vis and fluorescence spectroscopy are able to discriminate between aerosols receiving substantial fossil fuel pollution and those influenced by Saharan dust in an urban area. More depleted δ 13C was associated with low asymmetry parameter, g λ, and high values of the spectral slope ratio, S R, were associated with high effective radius, typical of pollution situations. The humification index (HIX), used predominantly to evaluate the degree of organic matter humification, was significantly related to g λ and the radius of fine mode particles, r f, and may reflect aging of the Saharan dust-influenced aerosols. Parallel factor analysis (PARAFAC) modeling identified a fluorescent component (C3) with a spectrum similar to that of naphthalene, which was significantly related to g λ and r f. The diesel exhaust sample represented a pollution end-member, with the lightest δ 13C value (-26.4‰), lowest S R (0.95), lowest HIX (2.77) and highest %C3 (20%) of all samples.

  10. Discrimination against C18O16O during photosynthesis and the oxygen isotope ratio of respired CO2 in boreal forest ecosystems

    Flanagan, Lawrence B.; Brooks, J. Renee; Varney, Gregory T.; Ehleringer, James R.

    1997-03-01

    Our objective was to analyze factors that influence changes in the oxygen isotope ratio (δ18O) of atmospheric CO2 within boreal forest ecosystems. We made measurements in the three major forest types (black spruce, jack pine, and aspen) at the southern and northern ends of the boreal forest in central Canada. This research was part of a larger study, the Boreal Ecosystem-Atmosphere Study (BOREAS). In terrestrial ecosystems the δ18O value of atmospheric CO2 is strongly influenced by isotope effects that occur during photosynthesis and respiration. Of primary importance is an equilibrium isotope effect that occurs between oxygen in CO2 and oxygen in soil water and plant chloroplast water. During the equilibrium reaction the oxygen isotope ratio of CO2 becomes enriched in 18O relative to that of water. We measured seasonal changes in the oxygen isotope ratio of (1) water input to the ecosystems (precipitation), (2) water taken up by the major plant species from the soil (plant stem water), and (3) water in plant leaves. We used this information in calculations of isotope discrimination during photosynthesis and soil respiration. Discrimination against C18O16O during photosynthetic gas exchange (ΔA) (influenced by equilibration with chloroplast water) averaged approximately 21‰ at midday and was similar for all forest types. In contrast, CO2 released during plant and soil respiration had an average δ18O value of -14.4‰ but was less depleted in 18O than would be expected for respired CO2 in isotopic equilibrium with soil water. This effect was most pronounced in black spruce sites because of the extensive coverage of moss on the ground surface and the observation that water in the upper moss layers can have an oxygen isotope ratio substantially different from water in deeper soil layers.

  11. Discrimination against C18O16O during photosynthesis and the oxygen isotope ratio of respired CO2 in boreal forest ecosystems

    Our objective was to analyze factors that influence changes in the oxygen isotope ratio (δ18O) of atmospheric CO2 within boreal forest ecosystems. We made measurements in the three major forest types (black spruce, jack pine, and aspen) at the southern and northern ends of the boreal forest in central Canada. This research was part of a larger study, the Boreal Ecosystem-Atmosphere Study (BOREAS). In terrestrial ecosystems the δ18O value of atmospheric CO2 is strongly influenced by isotope effects that occur during photosynthesis and respiration. Of primary importance is an equilibrium isotope effect that occurs between oxygen in CO2 and oxygen in soil water and plant chloroplast water. During the equilibrium reaction the oxygen isotope ratio of CO2 becomes enriched in 18O relative to that of water. We measured seasonal changes in the oxygen isotope ratio of (1) water input to the ecosystems (precipitation), (2) water taken up by the major plant species from the soil (plant stem water), and (3) water in plant leaves. We used this information in calculations of isotope discrimination during photosynthesis and soil respiration. Discrimination against C18O16O during photosynthetic gas exchange (ΔA) (influenced by equilibration with chloroplast water) averaged approximately 21‰ at midday and was similar for all forest types. In contrast, CO2 released during plant and soil respiration had an average δ18O value of −14.4‰ but was less depleted in 18O than would be expected for respired CO2 in isotopic equilibrium with soil water. This effect was most pronounced in black spruce sites because of the extensive coverage of moss on the ground surface and the observation that water in the upper moss layers can have an oxygen isotope ratio substantially different from water in deeper soil layers. (author)

  12. DISCRIMINATOR CREDIBILITY DIMENSIONS OF AN ONLINE ACQUISITION WEBSITE – AN ANALYSIS OF AN INTERNATIONAL CONSTRUCT ON A SPECIFIC ROMANIAN TARGET

    Oana TUGULEA (CIOBANU)

    2014-01-01

    The purpose of this study is to identify credibility dimensions that predict the level of credibility of an online sales clothes Website in Romania. The objectives of this research are: (1) identifying the online sales clothes Websites’ credibility dimensions that better discriminate between students to evaluate an online sales clothes Website to be credible or not credible; (2) creating a discriminant function to predict to which of the two analysed groups one user better fits; (3) identifyi...

  13. ASTROPHYSICAL SHRAPNEL: DISCRIMINATING AMONG NEAR-EARTH STELLAR EXPLOSION SOURCES OF LIVE RADIOACTIVE ISOTOPES

    Fry, Brian J.; Fields, Brian D. [Department of Astronomy, University of Illinois, Urbana, IL 61801 (United States); Ellis, John R. [Theoretical Physics and Cosmology Group, Department of Physics, King' s College London, London WC2R 2LS (United Kingdom)

    2015-02-10

    We consider the production and deposition on Earth of isotopes with half-lives in the range 10{sup 5}-10{sup 8} yr that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGB) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the {sup 60}Fe and {sup 26}Al signatures, and extend these estimates to include {sup 244}Pu and {sup 53}Mn. We discuss interpretations of the {sup 60}Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ∼2.2 Myr ago, showing that (1) the {sup 60}Fe yield rules out the TNSN and KN interpretations, (2) the {sup 60}Fe signals highly constrain SAGB interpretations but do not completely them rule out, (3) are consistent with a CCSN origin, and (4) are highly compatible with an ECSN interpretation. Future measurements could resolve the radioisotope deposition over time, and we use the Sedov blast wave solution to illustrate possible time-resolved profiles. Measuring such profiles would independently probe the blast properties including distance, and would provide additional constraints for the nature of the explosion.

  14. ASTROPHYSICAL SHRAPNEL: DISCRIMINATING AMONG NEAR-EARTH STELLAR EXPLOSION SOURCES OF LIVE RADIOACTIVE ISOTOPES

    We consider the production and deposition on Earth of isotopes with half-lives in the range 105-108 yr that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGB) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the 60Fe and 26Al signatures, and extend these estimates to include 244Pu and 53Mn. We discuss interpretations of the 60Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ∼2.2 Myr ago, showing that (1) the 60Fe yield rules out the TNSN and KN interpretations, (2) the 60Fe signals highly constrain SAGB interpretations but do not completely them rule out, (3) are consistent with a CCSN origin, and (4) are highly compatible with an ECSN interpretation. Future measurements could resolve the radioisotope deposition over time, and we use the Sedov blast wave solution to illustrate possible time-resolved profiles. Measuring such profiles would independently probe the blast properties including distance, and would provide additional constraints for the nature of the explosion

  15. Astrophysical Shrapnel: Discriminating Among Near-Earth Stellar Explosion Sources of Live Radioactive Isotopes

    Fry, Brian J; Ellis, John R

    2015-01-01

    We consider the production and deposition on Earth of isotopes with half-lives in the range 10$^{5}$ to 10$^{8}$ years that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGBs) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the $^{60}$Fe and $^{26}$Al signatures, and extend these estimates to include $^{244}$Pu and $^{53}$Mn. We discuss interpretations of the $^{60}$Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ~2.2 Myr ago, showing that (i) the $^{60}$Fe yield rules out the TNSN and KN interpretations, (ii) the $^{60}$Fe signals highly constrain a SAGB interpretation but do not completely them rule out, (iii) are consistent with a CCSN origin, and (iv) are highly compatible with an ECSN interpretation. Future measurements could resolve the radio...

  16. Genotypic variation in transpiration efficiency, carbon-isotope discrimination and carbon allocation during early growth in sunflower

    Transpiration efficiency of dry matter production (W), carbon-isotope discrimination (Δ) and dry matter partitioning were measured on six sunflower (Helianthus annuus L.) genotypes grown for 32 days in a glasshouse. Two watering regimes, one well watered (HW) and the other delivering half the water used by the HW plants (LW), were imposed. Four major results emerged from this study: Three was significant genotypic variation in W in sunflower and this was closely reflected in Δ for both watering treatments; the low watering regime caused a decrease in Δ but no change in W; nonetheless the genotypic ranking for either Δ or W was not significantly altered by water stress; a positive correlation between W and biomass accumulation occurred among genotypes of HW plants; ρ, the ratio of total plant carbon content to leaf area, was positively correlated with W and negatively correlated with Δ. These results are discussed with reference to the connection between transpiration efficiency and plant growth, indicating that Δ can be used to select for W among young sunflower plants. However, selection for W may be accompanied by changes in other important plant growth characteristics such as ρ. 19 refs., 4 figs

  17. Selection of drought tolerant and high water use efficient rice cultivars through /sup 13/C isotope discrimination technique

    Carbon isotope discrimination ('A') has been suggested as an indirect tool for selecting plants having higher water use efficiency (WUE) and yield potential. Enhancing WUE is an important breeding objective as water scarcity is increasing with every passing day. This study was undertaken to assess the genotypic variation and relationship between leaf, straw, grain 'A', grain yield and WUE in eight aromatic rice cultivars grown in lysimeters under three water regimes, in absence of drainage and runoff. Highly significant positive correlations were found between aboveground biomass and WUEB, and grain yield and WUEG, due to the low variation in water consumed by different cultivars. Leaf, straw and grain A showed a consistent variation across treatments and cultivars. Under water stress conditions, both leaf and straw 'A' were positively correlated to grain yield and WUEG. In all the water treatments, WUEG was positively correlated to harvest index and negatively to plant height. All the mutants from Basmati 385 had significantly higher 'A' values as compared to the mutants from Basmati 370. It was concluded that the new cultivar, Basmati 385, represents a better genetic source for 'A' improvement than the old cultivar, Basmati 370. (author)

  18. Carbon isotope discrimination as a diagnostic tool for C4 photosynthesis in C3-C4 intermediate species

    Alonso-Cantabrana, Hugo; von Caemmerer, Susanne

    2016-01-01

    The presence and activity of the C4 cycle in C3-C4 intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C4 activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO2 responses of CO2 assimilation (A) and carbon isotope discrimination (Δ) under low O2 partial pressure. Mathematical models of C3-C4 photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C3 and C4 controls, respectively. Our results support the presence of a functional C4 cycle in F. floridana, that can fix 12–21% of carbon. In F. brownii, 75–100% of carbon is fixed via the C4 cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO2 partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C4 photosynthesis. PMID:26862154

  19. Genetic Analysis of Carbon Isotope Discrimination and its Relation to Yield in a Wheat Doubled Haploid Population

    Xianshan Wu; Xiaoping Chang; Ruilian Jing

    2011-01-01

    Carbon isotope discrimination (△13C) is considered a useful indicator for indirect selection of grain yield (GY) in cereals.Therefore,it is important to evaluate the genetic variation in △13C and its relationship with GY.A doubled haploid (DH) population derived from a cross of two common wheat varieties,Hanxuan 10 (H10) and Lumai 14 (L14),was phenotyped for △13C in the flag leaf,GY and yield associated traits in two trials contrasted by water availability,specifically,rain-fed and irrigated.Quantitative trait loci (QTLs) were identified by single locus and two locus QTL analyses.QTLs for △13C were located on chromosomes 1A,2B,3B,5A,7A and 7B,and QTLs for other traits on all chromosomes except 1A,4D,5A,5B and 6D.The population selected for high △13C had an increased frequency of QTL for high △13C,GY and number of spikes per plant (NSP) when grown under rain-fed conditions and only for high △13C and NSP when grown under irrigated conditions,which was consistent with agronomic performance of the corresponding trait values in the high △13C progeny; that is,significantly greater than that in the low △13C.Therefore,selection for △13C was beneficial in increasing grain yield in rain-fed environments.

  20. Carbon isotope discrimination as a diagnostic tool for C4 photosynthesis in C3-C4 intermediate species.

    Alonso-Cantabrana, Hugo; von Caemmerer, Susanne

    2016-05-01

    The presence and activity of the C4 cycle in C3-C4 intermediate species have proven difficult to analyze, especially when such activity is low. This study proposes a strategy to detect C4 activity and estimate its contribution to overall photosynthesis in intermediate plants, by using tunable diode laser absorption spectroscopy (TDLAS) coupled to gas exchange systems to simultaneously measure the CO2 responses of CO2 assimilation (A) and carbon isotope discrimination (Δ) under low O2 partial pressure. Mathematical models of C3-C4 photosynthesis and Δ are then fitted concurrently to both responses using the same set of constants. This strategy was applied to the intermediate species Flaveria floridana and F. brownii, and to F. pringlei and F. bidentis as C3 and C4 controls, respectively. Our results support the presence of a functional C4 cycle in F. floridana, that can fix 12-21% of carbon. In F. brownii, 75-100% of carbon is fixed via the C4 cycle, and the contribution of mesophyll Rubisco to overall carbon assimilation increases with CO2 partial pressure in both intermediate plants. Combined gas exchange and Δ measurement and modeling is a powerful diagnostic tool for C4 photosynthesis. PMID:26862154

  1. Carbon Isotope Discrimination is not Correlated with Transpiration Efficiency in Three Cool-Season Grain Legumes (Pulses)

    2007-01-01

    The carbon Isotope discrimination (δ13C) of leaves has been shown to be correlated with the transpiration efficiency of leaves in a wide range of species. This has led to δ13C being used in breeding programs to select for improved transpiration efficiency. The correlation between δ13C and transpiration efficiency was determined under well-watered conditions during the vegetative phase In six genotypes of lentil (Lens culinaris Medikus), six genotypes of chickpea (Cicer arietinum L.) and 10 cultivars of narrow-leafed lupin (Lupinus angustifolius L.). Biomass (dry matter) accumulation and water use (transpiration)varied among the genotypes in all three species and transpiration efficiency was 40% to 75% higher In the most efficient compared with the least efficient genotypes. However, δ13C and transpiration efficiency were not significantly correlated in any of the species. This suggests that the δ13C technique cannot be used In selection for transpiration efficiency in the three grain legumes (pulses) studied.

  2. Frequency discriminator/phase detector

    Crow, R. B.

    1974-01-01

    Circuit provides dual function of frequency discriminator/phase detector which reduces frequency acquisition time without adding to circuit complexity. Both frequency discriminators, in evaluated frequency discriminator/phase detector circuits, are effective two decades above and below center frequency.

  3. Discrimination of two geographically distinct populations of sea bass Dicentrarchus labrax, using stable isotopic signatures of mercury (δ202Hg, Δ199Hg)

    Cransveld, Alice; Amouroux, David; Koutrakis, Emmanuil; Bérail, Sylvain; Caiyan, Feng; Barre, Julien P. G.; Schnitzler, Joseph; Das, Krishna

    2014-01-01

    Despite the reduction of mercury (Hg) emissions in Europe in the last decades, Hg emissions are increasing worldwide and concentrations found in some marine predators remain high. This raises questions on mercury's biogeochemical cycle at both local and global scale. In the present work, we investigate the possibility to use mercury isotopic signature in fish as a tool to discriminate different polluted areas and potential pollution sources. Indeed, Hg can exhibit both mass-dependent (MDF) an...

  4. Relationship between Water Use Efficiency and Î"13C Isotope Discrimination of Safflower (Carthamus tinctorius L.) under Drought Stress

    Canavar, Öner; GÖTZ, Klaus-Peter; Koca, Yakup Onur; Ellmer, Frank

    2014-01-01

    Drought stress is one of the most limiting factors in agricultural productivity because of its highly negative effect on photosynthesis and growth of plants. The main objectives of this study were to determine the performance of four selected safflower genotypes (Remzibey, Dinçer, Balcı and TRE-ASL09/14) against drought stress. The relationship between water use efficiency (WUE) and δ13C (isotope discrimination) was investigated under well watered (60%) and drought stress (30%) irrigation in ...

  5. Estimates of regional surface carbon dioxide exchange and carbon and oxygen isotope discrimination during photosynthesis from concentration profiles in the atmospheric boundary layer

    The integrating properties of the atmospheric boundary layer allow the influence of surface exchange processes on the atmosphere to be quantified and estimates of large-scale fluxes of trace gases and plant isotopic discrimination to be made. Five flights were undertaken over two days in and above the convective boundary layer (CBL) in a vegetated region in central Siberia. Vertical profiles of CO2 and H2O concentrations, temperature and pressure were obtained during each flight. Air flask samples were taken at various heights for carbon and oxygen isotopic analysis of CO2. Two CBL budget methods were compared to estimate regional surface fluxes of CO2 and plant isotopic discrimination against 13CO2 and C18O16O. Flux estimates were compared to ground-based eddy covariance measurements. The fluxes obtained for CO2 using the first method agreed to within 10% of fluxes measured in the forest at the study site by eddy covariance. Those obtained from the second method agreed to within 35% when a correction was applied for air loss out of the integrating column and for subsidence. The values for 13C discrimination were within the range expected from knowledge of C3 plant discriminations during photosynthesis, while the inferred 18O discrimination varied considerably over the two-day period. This variation may in part be explained by the enrichment of chloroplast water during the day due to evaporation from an initial signature in the morning close to source water. Additional potential complications arising from the heterogeneous nature of the landscape are discussed

  6. On line data acquisition and processing system for isotope abundance measurements using a spectrometer

    A system built using a TDC-312 computer for the automation of the Varian MAT CH-5 mass spectrometer for isotopic analysis is described. Salient feature of this automation is that software forms a major part of the system. A versatile computer program has been developed which can be used for the isotope abundance measurements of any element without interfering with the software of the system. The adjustment of ranges (gains) in between the peaks and updating of ranges, if required, is also performed by the computerised system. This has reduced the human intervention and the results are less prone to human error. Incidentally, this has also relieved the personnel of the strenuous manual work involved in the spectrum analysis. (auth.)

  7. Use of carbon isotope discrimination (δ) as a potential tool for salt tolerance selection in plant breeding

    Δ value of the wheat grown in the green house at 16 dSm-1 and field yield of cultivars grown under saline conditions, suggesting that the simple early-non-destructive hole punch technique and carbon isotope discrimination could be used as screening tools for salinity tolerance. Work is being performed to develop plant sample preparation techniques for 13C analysis using the FANci breath test analyser. This is a low cost, simple apparatus, which requires minimal training and expertise. Initial results from the tests are promising suggesting that the FANci could be used in discrimination type studies, however, further development and testing is required. In conclusion there was a significant correlation between Δ and the field yields δ decreased with increasing salinity concentration. It appears that salinity tolerance is a trait that is correlated to Δ and thus Δ could be used as a screening tool for plant breeding. Sampling techniques using the soil water samplers allowed simple monitoring and adjustment of salinity levels. Plant sap analysis could provide us with a rapid tool for determining plant tolerance to short term drought stress. The hole punch techniques proved to be a simple and effective non-destructive sampling strategy. With some development the FANci apparatus may be used as a simple method for 13C analysis. (author)

  8. Use of carbon isotope discrimination technique to sustain rice productivity under stressed and low land irrigated ecosystem of Pakistan

    Carbon Isotope Discrimination (delta) is an indirect screening tool for breeding cultivars against water stressed conditions. Previous studies exhibited that leaf and straw delta), under water stress, have positive and significant association with grain yield in rice genotypes. Current study was performed to assess the efficiency of delta technique at farmers field level. Five rice genotypes (RSP-1, RSP-2, RSP-3, RSP-4 and RSP-5), grown in lysimeters under well, medium and low water conditions, were subjected to delta analysis for selection of high yielding water use efficient genotypes. RSP-1 and RSP-2 were identified as the high yielding (4.22 and 4.23 tons ha-/sup 1/ respectively) and water use efficient genotypes (9.48 and 8.87 gm/m2/mm respectively) under lysimeters. For field study, three yield trials were conducted. In preliminary yield trial, under curtained water supply of 900 mm for a complete crop cycle), RSP-1 and RSP-2 produced 6.73 and 7.27 tons ha/sup -1/ paddy yields respectively. A multi location yield trial, to test the yield stability, indicated above average and average stability of RSP-1 and RSP-2 respectively. Yield performance of RSP-2 (4.1 tons ha/sup -1/) under highly saline field conditions (EC: 10 d Sm/sup -1/) opened the prospects for simultaneous selection of rice genotypes against water limited and saline conditions. According to our knowledge, this is the first report depicting the utility of delta technique to select the rice cultivar for water limited and saline soil conditions of low land irrigated rice ecology of Pakistan. (author)

  9. The Effects of Live Music as the Discriminative Stimulus and Reinforcer on the Skill Acquisition of Learners with Neurodevelopmental Disorders

    Harms, Melanie D.

    2013-01-01

    Individuals with neurodevelopmental disorders are challenged with memory and language deficits that impact their skills acquisition (Martin, Klusek, Estigarriba, & Roberts, 2009; Turner & Alborz, 2003). The value of music when applied as an antecedent and a reinforcer has long been established to address such memory and language deficits…

  10. Empirical assessment of visceral self-perception: individual and sex differences in the acquisition of heartbeat discrimination.

    Katkin, E S; Blascovich, J; Goldband, S

    1981-06-01

    This study had two aims: (a) to test precisely the degree to which subjects can learn to discriminate their own heartbeats and (b) to pursue preliminary data suggesting that males and females differ in their ability to learn such discriminations. A new methodology, based on the theory of signal detection, was employed to evaluate objectively and quantitatively the performance of nine male and nine female subjects. The results confirmed the validity of the new methodology for assessing heartbeat detection and also confirmed earlier observations that males are able to learn to detect their own heartbeats but females are not. The results are discussed with particular reference to implications for viscerally based theories of emotion. PMID:7264877

  11. Development of a computer systems for operational data acquisition of uranium isotopic enrichment pilot plant

    A pilot plant for uranium enrichment using the jet nozzle process was transfered from Federal Republic of Germany to Brazil, to train Brazilian technicist in its operation and to improve the process. This pilot plant is monitored by a data acquisition system and the possibility of faulty events would cause serious dificulties, as far as maintenance is concerned (for instance, unvailable special components). It is described the development of a new system, which is proposed in order to minimize difficulties with maintenance that utilizes in the assembling integrated circuits of large scale of integration. It is controlled by a microcomputer. (Author)

  12. Carbon Isotope discrimination in acacia auriculiformis - can it be used to select for higher water-use-efficiency in trees?

    Full text: Determining the water-use-efficiency of trees in relation lo wood production is problematic due to the sheer size of the plant and the number of years taken to produce the wood. Indirect measures of water-use-efficiency, such as carbon isotope discrimination (Δ), are therefore attractive to tree breeders wishing to select for increased water-use-efficiency. To begin to evaluate the usefulness of Δ as a selection parameter for the tropical tree Acacia auriculiformis we addressed the following questions: 1. Within the tree canopy, how variable is Δ? 2. Is there any genotypic variation in Δ? and 3. Does water availability affect genotypic variation? To address these questions we sampled foliage from pot trials and field trials of A. auriculiformis ranging in age from 3 months lo 8 years in Australia and Thailand. In 16-18m high 8-year-old trees, canopy variation in Δ was large (P>0.01). Foliage Δ values increased down the tree from 22.0 %o at the top to 24.7 %o at the base. The decrease was rapid in the lop 3 m of the canopy thus considerable care must be taken to sampling foliage from the same position in the canopy. Genotype variations in Δ was observed in seedlings and 2 year-old trees (P>0.01) but not in 8 year-old trees (P=0.60). Where genotypic variation were observed the differences between the lowest and highest values were 2.2 - 3.6 %o. Reduced water availability decreased Δ values in both pot and field studies but not in a consistent way across seedlots. Thus it would appear that the Δ of trees grown under favourable conditions does not give an indication of the Δ value which will be obtained under water-limited conditions. This complicates the use of Δ as a screening method. We have clearly shown that genotype variation occurs in A. auriculiformis in both seedlings and young field-grown trees. Considerable care is required when sampling large trees, as variation in Δ within the tree can be as large as between genotypes. The challenge

  13. Use of Carbon Isotope Discrimination as a Selection Tool in Wheat Breeding for Drought Tolerance in Yemen

    The objectives of the present investigation was to determine the potential of carbon isotope discrimination (CID, Δ) as an indirect selection criterion for the tolerance of wheat to drought, heat and low soil fertility under Yemeni field conditions. From the results of kernel-Δ of 63 wheat accessions (local and improved lines) obtained in the first year of the project, several parents were selected for a crossing programme. More than 120 crossbreds were obtained and planted in the field as the F1 generation (July-November 2005). The harvested plants were planted in the F2 population during the season December 2005-April 2006. Spike-Δ was analyzed for parents and 328 F2 individual plants of the cross between the local Triticum dicoccum var. Arabi47 and the advanced line No . 4 issued from the cross T. polonicum x T. durum. Results obtained for spike-Δ permitted heritability in the F2 population to be calculated (0.70), and high variability for this trait was observed (14.03- 18.91 per mille). Relationships between drought tolerance traits such as Δ, plant development or morphological attributes such as plant height, tiller number, number of spikes per plant and number of days from sowing to heading and maturity were evaluated. The seeds of 287 individual plants in the F2 population were planted in F3 rows under field conditions during the 2006 season (July-November). Phenological and morphological traits and grain yield were measured, and the correlations between Δ and these parameters were determined. During the December 2006-May 2007 season, 83 F4 lines divergent for Δ were evaluated under field conditions and grain was analyzed for Δ. There was no correlation between spike-Δ in the F2 plants and grain Δ in F4. F5 adapted lines were selected and planted in the July-November 2007 season at three sites for production and adaptation measurements. Twenty F6 lines were evaluated at several rain fed sites in Yemen. (author)

  14. Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

    Touzeau, Alexandra; Landais, Amaëlle; Stenni, Barbara; Uemura, Ryu; Fukui, Kotaro; Fujita, Shuji; Guilbaud, Sarah; Ekaykin, Alexey; Casado, Mathieu; Barkan, Eugeni; Luz, Boaz; Magand, Olivier; Teste, Grégory; Le Meur, Emmanuel; Baroni, Mélanie; Savarino, Joël; Bourgeois, Ilann; Risi, Camille

    2016-04-01

    The isotopic compositions of oxygen and hydrogen in ice cores are invaluable tools for the reconstruction of past climate variations. Used alone, they give insights into the variations of the local temperature, whereas taken together they can provide information on the climatic conditions at the point of origin of the moisture. However, recent analyses of snow from shallow pits indicate that the climatic signal can become erased in very low accumulation regions, due to local processes of snow reworking. The signal-to-noise ratio decreases and the climatic signal can then only be retrieved using stacks of several snow pits. Obviously, the signal is not completely lost at this stage, otherwise it would be impossible to extract valuable climate information from ice cores as has been done, for instance, for the last glaciation. To better understand how the climatic signal is passed from the precipitation to the snow, we present here results from varied snow samples from East Antarctica. First, we look at the relationship between isotopes and temperature from a geographical point of view, using results from three traverses across Antarctica, to see how the relationship is built up through the distillation process. We also take advantage of these measures to see how second-order parameters (d-excess and 17O-excess) are related to δ18O and how they are controlled. d-excess increases in the interior of the continent (i.e., when δ18O decreases), due to the distillation process, whereas 17O-excess decreases in remote areas, due to kinetic fractionation at low temperature. In both cases, these changes are associated with the loss of original information regarding the source. Then, we look at the same relationships in precipitation samples collected over 1 year at Dome C and Vostok, as well as in surface snow at Dome C. We note that the slope of the δ18O vs. temperature (T) relationship decreases in these samples compared to those from the traverses, and thus caution is

  15. Acquisition of isotopic composition for surface snow in East Antarctica and the links to climatic parameters

    A. Touzeau

    2015-11-01

    Full Text Available The isotopic composition of oxygen and hydrogen in ice cores are invaluable tools for the reconstruction of past climate variations. Used alone, they give insights into the variations of the local temperature, whereas taken together they can provide information on the climatic conditions at the point of origin of the moisture. However, recent analyses of snow from shallow pits indicate that the climatic signal can become erased in very low accumulation regions, due to local processes of snow reworking. The signal to noise ratio decreases and the climatic signal can then only be retrieved using stacks of several snow pits. Obviously, the signal is not completely lost at this stage, otherwise it would be impossible to extract valuable climate information from ice cores as has been done, for instance, for the last glaciation. To better understand how the climatic signal is passed from the precipitation to the snow, we present here results from varied snow samples from East Antarctica. First, we look at the relationship between isotopes and temperature from a geographical point of view, using results from three traverses across Antarctica, to see how the relationship is built up through the distillation process. We also take advantage of these measures to see how second order parameters (d-excess and 17O-excess are related to δ18O and how they are controlled. d-excess increases in the interior of the continent (i.e. when δ18O decreases, due to the distillation process, whereas 17O-excess decreases in remote areas, due to kinetic fractionation at low temperature. In both cases, these changes are associated with the loss of original information regarding the source. Then, we look at the same relationships in precipitation samples collected over one year at Dome C and Vostok, as well as in surface snow at Dome C. We note that the slope of the δ18O / T relationship decreases in these samples compared to those from the traverses, and thus advocate

  16. Is it really organic? – Multi-isotopic analysis as a tool to discriminate between organic and conventional plants

    Laursen, K.H.; Mihailova, A.; Kelly, S.D.;

    2013-01-01

    Novel procedures for analytical authentication of organic plant products are urgently needed. Here we present the first study encompassing stable isotopes of hydrogen, carbon, nitrogen, oxygen, magnesium and sulphur as well as compound-specific nitrogen and oxygen isotope analysis of nitrate for...

  17. Factorial optimization of data acquisition factors for lead isotope ratio determination by inductively coupled plasma mass spectrometry

    A factorial optimization of data acquisition factors was performed to minimize non-random instrumental noise on an inductively coupled plasma mass spectrometer. Results have identified instrumental and analytical operating conditions under which lead isotope ratios can be measured precisely and accurately in natural samples. Precision was checked periodically over weeks and ranged 0.10-0.30, 0.15-0.35, 0.15-0.35, 0.10-0.30 and 0.10-0.20 (%) for 206/204, 207/204, 208/204, 206/207 and 208/206 ratios respectively. Mass bias was minimized and the correction factors were typically of 0.6% for 206/204, 1.5% for 207/204, 1.8% for 208/204, 0.8% for 206/207 and 1.2% for 208/206. These results were performed with a dwell time of 20 ms, 40 sweeps per replicate, 8 replicates by analysis, a time factor of 15 applied on mass 204 and three points per peak in the low resolution mode. The total duration time of an analysis was 10:50 min and it was found that optimum concentration of lead in solution was 50 ng ml-1 on our instrument. (Author)

  18. 99Tcm-MIBI and 18F-FDG dual isotope simultaneous acquisition SPECT in determination of myocardial viability

    Objective: Viable myocardium is important to patients with coronary artery disease. The objective of this study was to evaluate the value of dual-isotope simultaneous acquisition SPECT (DISA-SPECT) with 99Tcm-methoxyisobutylisonitrile (MIBI) and 18F-fluorodeoxyglucose (FDG) in detecting viable myocardium (VM). Methods: Twenty-one patients with regional wall motion abnormalities (RWMA) based on routine echocardiography underwent DISA-SPECT, coronary angiography and percutaneous coronary intervention (PCI). Imaging and analysis of the left ventricular myocardial perfusion status were performed according to the 16-segment models proposed by American Society of Echocardiography. The wall motion of every LV segment was observed by echocardiography after 1, 3, 6 months. The images of DISA-SPECT were analyzed semi-quantitatively. The 'gold standard' for true viability was improvement of wall motion of the ventricular segment after PCI. Results: There were 105 viable myocardial segments and 51 non-viable myocardial segments according to the 'gold standard' criterion. The sensitivity, specificity, positive predict value, negative predict value and accuracy of DISA-SPECT in detecting viable myocardium were 93.3% (98/105), 82.4% (42/51), 91.6% (98/107), 85.7% (42/49), 89.7% (140/156), respectively. Conclusion: DISA-SPECT is a valuable technique to detect viable myocardium in patients with coronary artery disease. (authors)

  19. Influence of Reproduction on Stable-Isotope Ratios: Nitrogen and Carbon Isotope Discrimination between Mothers, Fetuses, and Milk in the Fin Whale, a Capital Breeder.

    Borrell, A; Gómez-Campos, E; Aguilar, A

    2016-01-01

    In mammals, the influence of gestation and lactation on the tissue stable-isotope ratios of females, fetuses, and milk remains poorly understood. Here we investigate the incidence of these events on δ(13)C and δ(15)N values in fin whales sampled off northwestern Spain between 1983 and 1985. The effect of gestation on tissue stable-isotope ratios was examined in the muscle of pregnant females (n = 13) and their fetuses (n = 10) and that of lactation in the muscle of nursing females (n = 21) and their milk (n = 25). Results suggest that fetuses are enriched compared to their mothers in both (15)N (Δ(15)N = 1.5‰) and (13)C (Δ(13)C =1.1‰), while, compared to muscle, milk is enriched in (15)N (Δ(15)N = 0.3‰) but depleted in (13)C (Δ(13)C = -0.62‰). This pattern is consistent with that previously observed for other species that, like the fin whale, rely on endogenous energy during reproduction, and it substantiates a general difference in the physiological processing of nitrogen and carbon balances between income and capital breeders. These findings are relevant to the understanding of the energetic balance of mammals during gestation and lactation and are central when inferences on trophic ecology are drawn from isotopic values of reproductive females. PMID:27082523

  20. Comparative performance of carbon isotope discrimination and canopy temperature depression as predictors of genotype differences in durum wheat yield in Spain

    The relationships between carbon isotope discrimination (Δ ) in mature kernels, canopy temperature depression (CTD) during anthesis and grain filling, 1000-kernel weight (TKW), total carbon content of mature kernels, and yield were studied in durum wheat (Triticum turgidum L. var. durum) grown in Spain (western Mediterranean basin). Twenty-five durum wheat genotypes were grown in 2 regions (NE and SE Spain) and under 2 water regimes (rainfed versus support irrigation) from 1997 to 1999, in a total of 12 trials. Principal component analysis placed yield and Δ on the same axis. Pearson's correlation and stepwise analysis confirmed that Δ was the trait that best assessed genotype differences in yield within trials, and was followed, at a considerable distance, by TKW. Our results also demonstrated the extremely poor performance of CTD throughout the wide range of growing conditions in this study. Copyright (2002) CSIRO Publishing

  1. Genetic variation in seedling water-use efficiency of Patagonian Cypress populations from contrasting precipitation regimes assessed through carbon isotope discrimination

    Pastorino, M. J.; Aparicio, A. G.; Marchelli, P.; Gallo, L. A.

    2012-11-01

    Water-use efficiency (WUE) is a physiological parameter that plays a significant role in the evolutionary dynamics of many forest tree species. It can be estimated indirectly through carbon isotope discrimination (A). In general, plants of more arid origins have lower values of A. In order to study the degree of genetic control of this parameter and the genetic variation in A of Patagonian Cypress seedlings, three Argentinean natural populations chosen to represent two contrasting precipitation regimes were sampled in a common garden trial. The dry situation was represented by two neighboring marginal forest patches from the steppe, while the humid condition was represented by a population with 1,200 mm higher mean annual precipitation. Height (H) and A were measured in 246 five-year-old seedlings from 41 open-pollinated families. The factor family had a significant effect on both variables; however heritability for A was found not to be significant in two out of the three populations. This could be explained by low sample size in one of them and by a real evolutionary effect in the other. An inverse association between H and A was verified, which is interpreted as evidence of an adaptation process at the intra-population level. The studied populations were not shown to discriminate carbon isotopes differently; hence evidence of adaptation to current environmental conditions could not be obtained. On the other hand, the arid populations proved to be quite different in terms of genetic variation, which seems to be the consequence of genetic drift and isolation. (Author) 49 refs.

  2. Bringing hope to marginal and harsh environments: The use of carbon-13 isotope discrimination technique to evaluate and select food crops adapted to water and salt stress environments

    Many countries have weather patterns and soil characteristics that place major constraints on food production systems over large tracts of land. Thus a major challenge for making better use of these marginal lands is not only to select appropriate crops but also to evaluate and optimize their adaptability and crop productivity under extreme climatic conditions (high temperatures and low rainfall) or where soils suffer from salinity, acidity or low plant nutrient status. The carbon isotope discrimination technique (using the ratios of different carbon isotopes [12C/13C] in plants) commonly referred to as CID, has been proposed as a possible selection criterion for greater water use efficiency in breeding programmes for water limited and salt stress environments because it provides an integrative assessment of genotypic variation in leaf transpiration efficiency. Although the relationship between CID and water and/or salt stress have been well studied and documented for many crop plants, few studies have looked at the combined effects of salt, water and nutrient stresses on the potential use of this technique to select and evaluate crop plants adapted to harsh environments

  3. Land-use and Erosion Source Discrimination of Soil and Carbon Sources to the Logan and Albert Rivers in Australia using Compound Specific Isotope Analysis

    Full text: The compound specific isotope analysis (CSIA) technique has been used to identify the sources of soil erosion contributing sediment to the Logan-Albert catchment. Soil samples were collected in January 2010 and used to assess the ability of the CSIA technique to discriminate probable sources of soil erosion. Fatty acid and bulk carbon isotope signature (δ13C) were measured. This study has built on a previous sediment tracing study undertaken in 2008 using fallout radionuclides and major/minor element geochemistry. It was found that surface soils from forest, pasture and cultivated land uses are well discriminated using CSIA. Furthermore, sub-surface soil sources associated with channel bank erosion and exposed subsoils (gullies and hillslope scalds) occurring specifically in the mid-western Logan catchment could also be discriminated. The CSIA and bulk carbon δ13C data were used in the IsoSource mixing model to estimate the erosion sources of sediment collected during the January 2008 flood. The results of this analysis were compared with results obtained using other sediment tracers. For the lower Logan River, the CSIA tracing results are consistent with fallout and element geochemistry tracing, with channel bank erosion being confirmed as the major sediment source. However, the significant contribution to Logan River sediment of exposed subsoils originating on hillslopes and drainage lines from the mid-western region of the Logan catchment has also been confirmed by CSIA. This erosion source was not quantified by catchment modelling. In the Albert River catchment about 50% of soil comes from forest land use, although more than half of this soil comes from sub-surface sources. These results have demonstrated that the CSIA technique has the potential to significantly enhance the ability of CSIRO Land and Water sediment tracing studies to determine the extent that different land uses are contributing eroded soil to rivers, thus providing a check on

  4. Investigations on the influence of ion kinetic energy on mass discrimination in isotope ratio measurements using MC-ICPMS

    Full text: Systematic dependence of mass discrimination on ICP operating parameters was investigated for two MCICPMS instruments, a Nu Plasma HR and a Nu Plasma 1700, which differ both in acceleration voltage and spectrometer geometry. Gas temperature variations were determined by absolute pressure measurements at the vacuum interface. Their influence on ion kinetic energy as monitored by means of a retardation filter fitted in front of an ion counting detector will be discussed and compared to effects resulting from variations in acceleration voltage. (author)

  5. Utilisation of carbon isotope discrimination in the genetic improvement of drought tolerance and yield potential in wheat

    Improvement of drought tolerance in cereals is an important aim for cereal breeders. Drought tolerance related traits have been extensively described in cereals. Their study, however, is based on instantaneous measurements (e.g., gas exchange, fluorescence or water status parameters) which association with yield highly depends on the environmental conditions at the moment of assessment. Realizing these measurements on high numbers of plants, what is a prerequisite for genetic or molecular studies, is tedious and often unrealistic. As a consequence, little is known about the genetics of these traits, and they are not used or even taken into serious consideration in breeding programs. The emergence of isotopic methods may substantially modify the situation. The tremendous advantages of this criterion in breeding programs are related to i) its integrative value, ii) its low genotype x environment interactions and high heritability values, and iii) the easiness of sample preparation and automatization of isotopic analysis. Researches carried out at ENSA-INRA Montpellier (1993-2000) have essentially concerned durum wheat adaptation to Mediterranean conditions. They were carried out in closed collaboration with the CIMMYT/ICARDA Durum Wheat Program and breeding programs of Algeria, Tunisia and Yemen. Studies realized at CIMMYT mainly concerned yield potential and bread wheat

  6. Isotopic discrimination during nitrous oxide loss processes: An important piece of the N2O global atmospheric budget

    Nitrous oxide plays an important role in greenhouse forcing and stratospheric ozone regulation. It is destructed in the stratosphere mainly by UV photolysis. Laboratory studies of N2O-N2 mixtures irradiated at 193 and 207 nm reveal a significant enrichment of the residual heavy nitrous oxide isotopomers. The isotopic signatures are well described by an irreversible Rayleigh distillation process, with large enrichment factors of ε15,18 (193 nm) = -18.4, -14.5 per mil and ε15,18(207 nm) = -48.7, -46.0 per mil. These results, when combined with diffusive mixing processes might help to explain the stratospheric enrichments previously observed. (author)

  7. Can 13C isotopic discrimination become the basis for a tool to quantify the dynamics of water stress in maize under field conditions?

    The relationships between 13C isotopic discrimination and water stress are well documented for C3 and C4 plants. However, the application in the field is hampered by complex interaction patterns with other common stress factors, such as nutrient deficiency. In addition, questions arise if temporal reductions in water availability during crop growth can be traced back using δ13C data in the field. The objective of this study therefore was to critically assess the potential use of δ13C observations to quantify water stress and its dynamics in maize (Zea mays L.) grown under low to high nitrogen availability, and to develop tools based on δ13C values for its diagnosis in the field. Two pot experiments were carried out in a screen house in Ibadan, Nigeria, and one researcher-managed field trial was conducted at Sekou, Benin. In the first pot experiment, we grew maize for 60 days under four watering regimes, (i) optimum (at field capacity) during 60 days, (ii) optimum from 0 to 30 days and stressed (50% field capacity) from 30 to 60 days, (iii) stressed from 0 to 30 days and optimum from 30 to 60 days, and (iv) stressed throughout the 60 days. Nitrogen was applied at three rates (none, moderate (45 kg N ha-1) and high (120 kg N ha-1)). Plants were sampled after 30 and 60 days. At 60 days, leaves developed during the first 30 days were sampled separately from those developed between 30 and 60 days. In the second pot experiment, we grew maize for 120 days under five watering regimes, (i) optimum (at field capacity), (ii) stressed (50% field capacity), (iii) stressed (30% field capacity), (iv) optimum from 0 to 20 days, stressed (no water) from 20 to 35 days and optimum from 35 to 120 days, and (iv) optimum from 0 to 50 days, stressed from 50 to 65 days (no water) and optimum from 65 to 120 days. Nitrogen was applied at three rates (none, moderate (45 kg N ha-1), high (90 kg N ha-1)) in the form of urea, leaves from Senna siamea trees (incorporated in the soil), or in a

  8. Comparative physiology of allopatric Populus species: geographic clines in photosynthesis, height growth, and carbon isotope discrimination in common gardens.

    Soolanayakanahally, Raju Y; Guy, Robert D; Street, Nathaniel R; Robinson, Kathryn M; Silim, Salim N; Albrectsen, Benedicte R; Jansson, Stefan

    2015-01-01

    Populus species with wide geographic ranges display strong adaptation to local environments. We studied the clinal patterns in phenology and ecophysiology in allopatric Populus species adapted to similar environments on different continents under common garden settings. As a result of climatic adaptation, both Populus tremula L. and Populus balsamifera L. display latitudinal clines in photosynthetic rates (A), whereby high-latitude trees of P. tremula had higher A compared to low-latitude trees and nearly so in P. balsamifera (p = 0.06). Stomatal conductance (g s) and chlorophyll content index (CCI) follow similar latitudinal trends. However, foliar nitrogen was positively correlated with latitude in P. balsamifera and negatively correlated in P. tremula. No significant trends in carbon isotope composition of the leaf tissue (δ(13)C) were observed for both species; but, intrinsic water-use efficiency (WUEi) was negatively correlated with the latitude of origin in P. balsamifera. In spite of intrinsically higher A, high-latitude trees in both common gardens accomplished less height gain as a result of early bud set. Thus, shoot biomass was determined by height elongation duration (HED), which was well approximated by the number of days available for free growth between bud flush and bud set. We highlight the shortcoming of unreplicated outdoor common gardens for tree improvement and the crucial role of photoperiod in limiting height growth, further complicating interpretation of other secondary effects. PMID:26236324

  9. Comparative physiology of allopatric Populus species: Geographic clines in photosynthesis, height growth and carbon isotope discrimination in common gardens

    Raju Yaranna Soolanayakanahally

    2015-07-01

    Full Text Available Populus species with wide geographic ranges display strong adaptation to local environments. We studied the clinal patterns in phenology and ecophysiology in allopatric Populus species adapted to similar environments on different continents under common garden settings. As a result of climatic adaptation, both P. tremula L. and Populus balsamifera L. display latitudinal clines in photosynthetic rates (A, whereby high-latitude trees of P. tremula had higher A compared to low-latitude trees and nearly so in P. balsamifera (p = 0.06. Stomatal conductance (gs and chlorophyll content index (CCI follow similar latitudinal trends. However, foliar nitrogen was positively correlated with latitude in P. balsamifera and negatively correlated in P. tremula. No significant trends in carbon isotope composition of the leaf tissue (δ13C were observed for both species; but, intrinsic water-use efficiency (WUEi was negatively correlated with the latitude of origin in P. balsamifera. In spite of intrinsically higher A, high-latitude trees in both common gardens accomplished less height gain as a result of early bud set. Thus, shoot biomass was determined by height elongation duration (HED, which was well approximated by the number of days available for free growth between bud flush and bud set. In doing so, we highlight the shortcoming of unreplicated outdoor common gardens for tree improvement and the crucial role of photoperiod in limiting height growth, further complicating interpretation of other secondary effects.

  10. Relationship between Yield, Carbon Isotope Discrimination (Δ13C) and Water Use Efficiency of Durum Wheat in the Syrian Arab Republic. 3. Simulation Modelling

    Six durum wheat genotypes were grown at Tel Hadya during the three seasons 2004-2005, 2005-2006 and 2006-2007, and the data were used to calibrate and validate the simulation model SIMWASER. Simulated and measured soil water status and yield production showed very good conformity, and therefore SIMWASER was able to reproduce the water balance of the site in a realistic manner, as well as yield production throughout the season. The validated model was run for the period between 1980 and 2007 for the Tel Hadya site using daily weather data. Also, different genetic scenarios were used regarding different transpiration values. Carbon isotope discrimination (Δ13C) was used as a closely-related surrogate for transpiration at the plant level. The simulated yields showed weak relationships with measured rainfall. However, closer relationships (higher R2) were found between simulated yield and plant transpiration. Moreover, when years were grouped according to rainfall, dry years (rainfall 175 mm), stronger relationships were evident between simulated yield and measured rainfall. The dry years produced much higher yields per unit of rainfall (rainfall use efficiency) compared with the wetter years, ranging between 13 and 90 kg ha-1 mm-1 for the wet and dry years, respectively. The high Δ cultivars transpired more water, had higher yields and therefore had higher water use efficiencies compared with low Δ cultivars. (author)

  11. Wood anatomy and carbon-isotope discrimination support long-term hydraulic deterioration as a major cause of drought-induced dieback.

    Pellizzari, Elena; Camarero, J Julio; Gazol, Antonio; Sangüesa-Barreda, Gabriel; Carrer, Marco

    2016-06-01

    Hydraulic impairment due to xylem embolism and carbon starvation are the two proposed mechanisms explaining drought-induced forest dieback and tree death. Here, we evaluate the relative role played by these two mechanisms in the long-term by quantifying wood-anatomical traits (tracheid size and area of parenchyma rays) and estimating the intrinsic water-use efficiency (iWUE) from carbon isotopic discrimination. We selected silver fir and Scots pine stands in NE Spain with ongoing dieback processes and compared trees showing contrasting vigour (declining vs nondeclining trees). In both species earlywood tracheids in declining trees showed smaller lumen area with thicker cell wall, inducing a lower theoretical hydraulic conductivity. Parenchyma ray area was similar between the two vigour classes. Wet spring and summer conditions promoted the formation of larger lumen areas, particularly in the case of nondeclining trees. Declining silver firs presented a lower iWUE than conspecific nondeclining trees, but the reverse pattern was observed in Scots pine. The described patterns in wood anatomical traits and iWUE are coherent with a long-lasting deterioration of the hydraulic system in declining trees prior to their dieback. Retrospective quantifications of lumen area permit to forecast dieback in declining trees 2-5 decades before growth decline started. Wood anatomical traits provide a robust tool to reconstruct the long-term capacity of trees to withstand drought-induced dieback. PMID:26790660

  12. Using stable isotopes to trace resource acquisition and trophic position in four Afrotropical birds with different diets

    Procházka, Petr; Reif, J.; Hořák, D.; Klvaňa, P.; Lee, R. W.; Yohannes, E.

    2010-01-01

    Roč. 81, č. 3 (2010), s. 273-275. ISSN 0030-6525 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60930519 Keywords : stable isotope analysis * dietary niche * Cameroon Mountains Subject RIV: EG - Zoology Impact factor: 0.338, year: 2010

  13. Growth, Carbon Isotope Discrimination and Nitrogen Uptake in Silicon and/or Potassium Fed barley Grown under Two Watering Regimes

    Kurdali, Fawaz

    2013-02-01

    Full Text Available The present pot experiment was an attempt to monitor the beneficial effects of silicon (Si and/or potassium (K applications on growth and nitrogen uptake in barley plants grown under water (FC1 and non water (FC2 stress conditions using 15N and 13C isotopes. Three fertilizer rates of Si (Si50, Si100 and Si200 and one fertilizer rate of K were used. Dry matter (DM and N yield (NY in different plant parts of barley plants was affected by Si and/ or K fertilization as well as by the watering regime level under which the plants have been grown. Solely added K or in combination with adequate rate of Si (Si 100 were more effective in alleviating water stress and producing higher yield in barley plants than solely added Si. However, the latter nutrient was found to be more effective than the former in producing higher spike's N yield. Solely added Si or in combination with K significantly reduced leaves ∆13 C reflecting their bifacial effects on water use efficiency (WUE, particularly in plants grown under well watering regime. This result indicated that Si might be involved in saving water loss through reducing transpiration rate and facilitating water uptake; consequently, increasing WUE. Although the rising of soil humidity generally increased fertilizer nitrogen uptake (Ndff and its use efficiency (%NUE in barley plants, applications of K or Si fertilizers to water stressed plants resulted in significant increments of these parameters as compared with the control. Our results highlight that Si or K is not only involved in amelioration of growth of barley plants, but can also improve nitrogen uptake and fertilizer nitrogen use efficiency particularly under water deficit conditions.

  14. Relationships among Water Use Efficiency, Grain Yield, Carbon Isotope Discrimination and Ash Content in Wheat under Different Mega-Environments and Water Regimes in China and India

    Positive correlations have been repeatedly reported between grain yield, carbon isotope discrimination (CID, Δ13C or Δ) and ash content in wheat cultivated under Mediterranean-type environments (characterized by post-anthesis water stress). The relationships among these traits have been much less analyzed under other wheat mega-environments. The present study examined the relationships between grain yield, Δ13C and ash content in wheat in Northern China (characterized by pre-anthesis water stress) and in the Peninsular Zone of India (characterized by residual moisture stress). In both mega-environments, wheat was grown under rain fed and irrigated conditions. The relationships between grain yield, Δ and ash content were less stable than under post-anthesis water stress, and were highly dependent on the quantity of water stored in the soil at sowing, which in turn depends on out-of-season rainfall. This considerably limits the use of Δ and ash content as indirect selection criteria for yield in these mega-environments. In India, the relationships between Δ, ash content and components of water use efficiency (WUE) (the latter were estimated from a soil water balance model) were also investigated. Significant correlations were found across environments between ash content in leaf and grain and the model estimates of the quantity of water transpired during the growth cycle. WUE was significantly negatively correlated with ash content in leaf and grain. Additional analyses of the relationships among grain yield, Δ and ash content, including soil moisture measurements over the growing period and/or estimation of water balance components, are needed in these mega-environments to define precisely the range of conditions leading to significant correlations and allowing the use of Δ and ash content as indirect selection criteria for yield. (author)

  15. Relationship between Carbon Isotope Discrimination (Δ13C) and Water Use Efficiency of Durum Wheat in the Syrian Arab Republic. 1. Field Evaluation

    Field experiments were conducted over three seasons (2004-2005, 2005-2006 and 2006-2007) using six durum wheat genotypes, similar in phenology, to minimize the genotype x environment (G*E) interaction, but varying in grain carbon isotope discrimination (CID, Δ13C or Δ). The four field sites at Tel Hadya, Breda, Muslmieh and Yahmoul were fully characterized according to environment and soil classification. Plant growth and development were monitored throughout the growing season. Δ was measured for every plot using grain or the 4th fully-expanded leaf. Also, ash and protein contents of grain were analyzed. Radiation use efficiency was measured at Tel Hadya only. Stomatal conductance and resistant as well as canopy temperature was also measured for the different sites and years. Soil water content throughout the growing season was measured at some sites to calculate water use. Variability between sites was mostly related to rainfall, with variability within a site being related to season. Δ was lower at the drier sites and higher at the wettest site, ranging from 12.88 to 16.62 per mille for grain, and 19.97 to 22.57 per mille for the 4th fully-expanded leaf. Positive correlations were found between grain Δ and yields of grain and biomass. The stronger correlations were at the drier sites, whilst at the wettest site (Yahmoul) there was no significant relationship. Δ was also related to ash and protein content. The genotypic variation in Δ (grain and leaf) was substantially independent of season or site. (author)

  16. Relationship between Carbon Isotope Discrimination (Δ13C) and Water Use Efficiency of Durum Wheat int the Syrian Arab Republic. 2. Glasshouse Evaluation

    A greenhouse pot experiment was conducted to compare transpiration rates of six durum wheat genotypes grown in two soil types, a clay (Tel Hadya) and a sandy clay loam (Breda). Six durum wheat genotypes varying in grain carbon isotope discrimination (Δ), an index to transpiration efficiency, were used. Pots were subjected to controlled and gradual dehydration, with a wet treatment as a control. The transpiration ratio (TR) was calculated as the ratio between daily water loss for each of the pots undergoing gradual dehydration, and the average daily water loss in the wet pots. Then the data were further normalized. The daily fraction of transpirable soil water (FTSW) for each pot was calculated by dividing the difference between daily pot weight and final weight by the overall transpirable soil water (difference between initial and final pot weight). The data were analyzed by plotting normalized transpiration ratio (NTR) against the FTSW using logistic, linear plateau and exponential models. Genotypes differed in transpiration rates during gradual dehydration and between the two soil types for pooled data. A significant relationship was found between dry matter production and threshold values (the point when the transpiration rate starts to be less in the gradual dehydration treatment than in the control treatment). The cultivar Brachoua (which had low grain Δ) recorded the highest dry matter production and the highest threshold value. Significant differences in threshold values were evident between the two soil types. The lowest threshold value was for the cultivar Waha (which had high grain Δ, and consequently had a potentially high transpiration efficiency), indicating a superior ability to extract water at high soil water potentials (when soil is dry). On the other hand, the genotype Brachoua was very sensitive to low soil moisture, and transpiration rates decreased at the beginning of the gradual dehydration. (author)

  17. Isotopic discrimination of soil depth profile under long term cultivated land with sludge sewage effluent at El-Gabal El-Asfar area, Egypt Key words: Stable isotopes, Soil organic carbon, Soil moisture, Heavy metals

    Two core profiles of different texture sizes (coarse sand and clay fine grains) were selected to study the long term behaviour of pollutant dynamic in relation with the potential load of soil organic matter (SOM) within about 1m depth. Soil depth profile analyses showed marked differences in SOM and δ13C in sand with respect to clay particles. On the top sand surface (0-5 cm), SOM was twice as that detected in clay horizons, whereas an inverse trend was obtained in δ13C with enrichment by about 2.3% in clay more than sand particles. This enrichment reflects the difference in kinetic fractionation during humification of SOM in the initial stage due to preferential accumulation of δ13C in association with fine texture particles, where fractionation of SOM to particle size yields organo-mineral fractionation's. The significant variations in sand core lie between 20-50 cm depth from the soil surface where humification and decomposition of SOM is followed by separation and accumulation at lower depth due to higher bio-diffusivity in coarse particles. Slight increment observed in SOM at 60 cm depth, as soil texture changed to fine sand and clayey minerals, represented an accumulation of residual fragment depleted in δ13C, which further attained progressive enrichment by 6% down the depth profile (110 cm). This sharp enrichment in δ13C could be attained from a methanogenic process in moist soil or mixing with another organic pool enriched in isotopes (C4 biomass). In clay soil within the first layers (0-15 cm depth), SOM and δ13C were relatively constant due to soil tillage, while the major change along depth was occurred within 20-40 cm depth where the processes of SOM decomposition and mobilization proceed in fine texture particles. These processes led to δ13C enrichment down the profile in terms of organic matter turnover. Soil moisture profiles were discriminated by δ18O and δD isotopes, where the δ18O enrichment reached about 1.6% and 2.36% in clay and sand

  18. Analytical developments in the measurements of boron, nitrate, phosphate and sulphate isotopes and case examples of discrimination of nitrogen and sulphur sources in pollution studies

    Methods are documented for the analysis of B isotopes, O and N isotopes in nitrates. B isotopes can be measured by negative ion thermal ionisation mass spectrometry. Nitrate is recovered from groundwaters by ion exchange and the resulting silver nitrate combusted for stable isotope gas analysis. Oxygen isotope analysis of phosphates can be determined by generating and analysing CO2 gas from the combustion of silver phosphate produced from aqueous samples. Sulphate in ground and surface waters can be separated and concentrated by ion exchange and precipitated as barium sulphate. This is reacted with graphite to yield CO2 and CO, the latter being spark discharged to CO2 and the total CO2 measured for oxygen isotope analysis. Barium sulphide from this reaction is converted to silver sulphide which is reacted with cuprous oxide to give SO2 gas for sulphur isotope measurements. A case study of the semi-rural Manakau area in New Zealand was conducted to see if nitrate isotopes could be used to detect the source of nitrate contamination (groundwater nitrate -3-N). Nitrogen isotope (+4 to +12 per mille) coupled with oxygen isotope measurements (+5 to +9 per mille) demonstrated that the nitrogen is not sources from fertilisers but from some combination of septic tank and animal waste. For the case study of sulphate isotope use, sulphur and oxygen isotopic compositions of sulphate in river and lake water from seven major catchments of New Zealand were determined. The isotope analyses have allowed the distinction between natural (geological, geothermal and volcanic) and anthropogenic (fertiliser) sulphur sources. (author)

  19. Utilization of Carbon Isotope Discrimination and Ash Content to Select Wheat for Tolerance to Water Limitation in the Peninsular Zone of India

    Relationships between grain yield, ash content (ma) and carbon isotope discrimination (CID, Δ13C or Δ) were studied in 30 wheat genotypes (14 durum and 16 aestivum) during 2003-2004, and 20 durum genotypes during two successive seasons (2004-2005 and 2005-2006) under three water regimes, i.e., residual soil moisture stress (RSMS), post-anthesis water stress (PAWS) and well watered (WW) conditions. Correlations between grain yield, ash content and Δ depended greatly on the environmental conditions and the drought scenario. Grain yield, biomass, Δ and ma decreased significantly with the reduction in water availability. Yield was significantly and positively correlated with ΔLa and ΔGm for each water regime only in 2005-2006, but the relationships were significant under WW across seasons. Strong negative correlations were observed between yield and maGm for each water regime only in 2004-2005, but the relationships were significant across seasons under WW conditions. Several significant and negative correlations were observed between yield and canopy temperature depression, but the relationships were significant only under PAWS across seasons. Results obtained during 2004-2005 and 2005-2006 show that Δ and maGm could consistently predict yield only under WW conditions. ΔGm and ΔLa were consistently and significantly correlated with maLa only under RSMS. In RIL population studies a major QTL was detected on chromosome 4B, responsible for around 15% of the variation in Δ. Major QTLs for canopy temperature depression (CTD) were identified on chromosomes 2A and 6A, and major QTLs for ash content were detected on chromosomes 5A and 6A, under PAWS and full irrigation, respectively. Near Infra-red transmittance (NIT) was used to speed up the determination of grain ash content. The overall range for wheat samples analyzed by the reference and NIT methods were 1.2 - 2.3 % and 1.22 - 1.99% (dry weight basis), respectively. The slope of the regression was 1.000 with an

  20. Dry matter yield, carbon isotope discrimination and nitrogen uptake in silicon and/ or potassium fed chickpea and barley plants grown under water and non-water stress conditions

    A pot experiment was conducted to study the effects of silicon (Si) and/or potassium (K) on dry matter yield, nitrogen uptake and carbon isotope discrimination Δ 13C in water stressed (FC1) and well watered (FC2) chickpea plants using 15N and 13C isotopes. Three fertilizer rates of Si (Si50, Si100 and Si200) and one fertilizer rate of K were used. The results showed that: In chickpeas, it was found, for most of the growth parameters, that Si either alone or in combination with K was more effective to alleviate water stress than K alone. Increasing soil water level from FC1 to FC2 often had a positive impact on values of most studied parameters. The Si100K+ (FC1) and Si50K+ (FC2) treatments gave high enough amounts of N2-fixation, higher dry matter production and greater nitrogen yield. The percent increments of total N2-fixed in the above mentioned treatments were 51 and 47% over their controls, respectively. On the other hand, increasing leaves dry matter in response to the solely added Si (Si50K- and Si100K-) is associated with lower Δ13C under both watering regimes. This may indicate that Si fertilization had a beneficial effect on water use efficiency (WUE). Hence, Δ13C could be an adequate indicator of WUE in response to the exogenous supply of silicon to chickpea plants. Our results highlight that Si is not only involved in amelioration of growth and in maintaining of water status but it can be considered as an important element for the symbiotic performance of chickpea plants. It can be concluded that synergistic effect of silicon and potassium fertilization with adequate irrigation improves growth and nitrogen fixation in chickpea plants.In barley plants, solely added K or in combination with adequate rate of Si (Si100) were more effective in alleviating water stress and producing higher yield in barley plants than solely added Si. However, the latter nutrient was found to be more effective than the former in producing higher spike's N yield. Solely

  1. The effect of soil fertility, crop management on carbon-isotope discrimination and their relationships with yield and water-use efficiency of crops in semi-arid and arid environments

    A synthesis of data on carbon-isotope discrimination (Δ), yield and water-use efficiency (WUE) of various plant organs was carried out to determine if relationships exist among these traits for a range of C3 and C4 crops, and if Δ is a suitable selection tool for yield and WUE under different levels of applied nitrogen (N) and diverse cropping systems. The samples were from the co-ordinated research project on 'Management of Nutrients and Water in Rainfed Arid and Semi-Arid Areas for Increasing Crop Production', with Members States covering a wide range of arid and semi-arid regions. The results showed that genotypic variation in carbon-isotope discrimination exists within plant organs in all crops, with Δ values lowest in the grain component. Genotypic variation in Δ also exists in different environments; in the case of wheat, the lowest Δ was found in the driest regions (Jordan compared with China, the latter having a higher growing-season rainfall). There were strong correlations between wheat grain Δ and grain yield in all studies; however, the correlations were negative in two (China and India) and positive in the other three countries (Jordan, Morocco and Pakistan). While various factors may influence Δ, these contrasting results showed that it is difficult to predict outcome in a particular environment and hence in using Δ as a tool for selecting yield; however, breeders could argue that yield in these two environments could be chosen based on lower Δ in relatively wet years in the negative cases, and high Δ in wet years in the positive cases. Correlation between Δ and WUE was less strong, and cropping system had little effect on the variation of Δ values within plant organs for most crops. The level of N applied affected Δ value in wheat, except in China. In all cases, Δ decreased with increasing leaf-N content. Nitrogen deficiency reduces photosynthetic capacity, and hence an inverse relationship between %N and Δ should exist. This

  2. The effect of viable myocardium on left ventricular function after elective revascularization in patients with myocardial infarction by dual-isotope simultaneous acquisition myocardial perfusion-metabolic imaging

    Objective: To evaluate the effect of myocardial viability on left ventricular function after elective revascularization in patients with myocardial infarction by 99Tcm-MIBI and 18F-FDG dual-isotope simultaneous acquisition (DISA) myocardial perfusion-metabolic imaging. Methods: Ninety-one patients clinically confirmed of myocardial infarction underwent DISA imaging. Based on the results of echocardiography, the patients were divided into heart failure group (group A) and normal cardiac function group (group B). After PCI, left ventricular function was measured by echocardiography in 1, 3 and 6 months. The t-test and χ2-test were used to compare the difference between the two groups using SPSS 13.0. Results: The average number of diseased segments by myocardial perfusion imaging was 9.8±3.5 and 5.4±2.6 in groups A and B, respectively (t=6.87, P2=40.61, P<0.001). The summed perfusion score (SPS), summed metabolism score (SMS) and summed difference score (SDS=SMS-SPS) were 28.43±11.86 vs 21.36±9.54, 20.17±8.52 vs 15.19±5.74 and 0.39±3.17 vs -12.72±4.55, respectively in groups A and B (t=3.15, P<0.01; t=3.32, P<0.01; t=15.59, P<0.01). The mean change of LVEF (ΔLVEF) and the mean change of left ventricular end-diastole dimension (ΔLVEDd) of the patients with more than 4 viable myocardial segments in group A were significantly more than those in group B((12.81±2.62)% vs (5.90±1.91)%, t=16.33, P<0.001; (-13.13±4.20) mm vs (-7.75±2.31) mm, t=6.86, P<0.001). However, the ΔLVEF and ΔLVEDd of the patients with less than 4 viable myocardial segments in group A were significantly less than those in group B (t=3.25, P<0.01; t=4.92, P<0.001). Conclusion: The amount of viable myocardium in infarct myocardium is an important factor for left ventricular function recovery after elective revascularization. (authors)

  3. Report on the consultants meeting on identification of crop species/cultivars for drought and salinity tolerance for sustained crop yields by using nuclear techniques, in particular the carbon isotope discrimination

    A Consultants Meeting on Identification of Crop Species/Cultivars for Drought and Salinity Tolerance for Sustained Crop Yields by Using Nuclear Techniques, in Particular the Carbon Isotope Discrimination. was held in Vienna at the IAEA Headquarters from 12-16 November 2001. This meeting was conducted in conjunction with a Group Meeting on Novel Approaches for Improving Crop Tolerance to Salinity and Drought. Five consultants from Australia, Mexico, Pakistan, UK and the USA and one representative from FAO attended the Consultant Meeting and nine participants from Australia, Canada, China, Germany, India, Israel, Pakistan, South Africa and the USA attended the Group Meeting. First two days of the meeting consisted of five technical sessions during which the participants presented papers on various approaches for improving crop tolerance to salinity and drought and the role of nuclear techniques in identification of plants tolerant to the above abiotic stresses. After the presentations, two working groups were formed: one consisting of the participants of the Consultants Meeting and the other the participants of the Group Meeting. The consultants proposed various strategies for using the carbon isotope discrimination technique as a selection tool for identifying higher yielding crop genotypes especially in wheat and rice cropping systems under drought and saline conditions. A proposal was formulated to address the above issues in a framework of a CRP. The participants of the Group Meeting reviewed conventional and molecular approaches for improving crop tolerance to salinity and drought and research priorities were identified for future work on crop productivity improvement under the above stress factors. Recommendations of both working groups were presented at the final session of the meeting. This report provides the details of the proposal formulated by the consultants. Refs

  4. Spatial discrimination and visual discrimination

    Haagensen, Annika M. J.; Grand, Nanna; Klastrup, Signe;

    2013-01-01

    visual discrimination test. The juvenile minipigs were able to learn the spatial hole-board discrimination test and showed improved working and reference memory during the learning phase. Performance in the memory phases was affected by the retention intervals, but the minipigs were able to remember the...... concept of the test in both memory phases. Working memory and reference memory were significantly improved in the last trials of the memory phases. In the visual discrimination test, the minipigs learned to discriminate between the three figures presented to them within 9-14 sessions. For the memory test......, all minipigs performed 9/12 correct choices or better. Juvenile Gottingen minipigs are able to learn to perform in a spatial hole-board discrimination test as well as in a visual discrimination test, showing an increase in performance over time. Both tests have considerable scope to assess learning...

  5. Military Discrimination.

    Hunter, Richard W.

    1981-01-01

    Argues that while a certain level of fairness is necessary in considering the equity of compulsory military service, the most important issue is that of "winning the war." Also asserts that sex, age, and race discrimination are more important than social class discrimination in military service. (Author/GC)

  6. Discrimination model of account sale decision-making risk degrees on the basis of different information acquisition degrees%基于不同信息获取量的赊销决策风险度判别模型

    孙庆文; 张琼琼; 仇静莉; 王晓军

    2012-01-01

    面对随时可能灭失的商机,如何在既定的时间内选用最佳的调研方法,从而做出相对正确的赊销决策并有效控制赊销风险,对企业意义重大.将不完全信息状态下企业赊销客户的赊销决策问题视为一个时间离散、状态连续的随机过程.在充分考虑有限调研时间内调研方法选择对赊销客户信用等级判别精确度影响的基础上,结合空间分析方法构建了基于不同信息获取完备程度的客户信用评估模型,引用判别分析思想判别不完全信息下的客户信用评估精确度,并借鉴风险性决策思想计算不同赊销风险程度下的赊销期望收益.最后以一则算例展示模型的实用性.%Market economy presented a kind of phenomenon that the opportunities may be lost at any time. Enterprises need to choose the best investigation method in limited time, in order to acquire more information to make credit decisions more accurately. It is of great significance for enterprise in the situation. This article regards the problem of account sale decision-making in incomplete information state as a discrete time, continuous state stochastic process. The article establishes a model of customer credit evaluation on the basis of different information acquisition degrees. The model borrows some ideas from the method of spatial analysis. Then the article references the thought of discriminatory analysis to discriminate the accuracy of the customer credit evaluation in incomplete information state. At last, the article works out the expected profit of account sale by borrowing the thought of risk decision. The whole process is based on taking full account of the effect of different investigation methods on discrimination accuracy of customer credit rating within the limited time. At the end of the article, an example is given to show the practicality of the model.

  7. Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using 238U-230Th disequilibria and Os isotopes

    Jicha, B.R.; Johnson, C.M.; Hildreth, W.; Beard, B.L.; Hart, G.L.; Shirey, S.B.; Singer, B.S.

    2009-01-01

    A suite of 23 basaltic to dacitic lavas erupted over the last 350??kyr from the Mount Adams volcanic field has been analyzed for U-Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have (230Th/238U) > 1 and span a large range in (230Th/232Th) ratios, and most basalts have higher (230Th/232Th) ratios than andesites and dacites. Several of the lavas contain antecrysts (crystals of pre-existing material), yet internal U-Th mineral isochrons from six of seven lavas are indistinguishable from their eruption ages. This indicates a relatively brief period of time between crystal growth and eruption for most of the phenocrysts (olivine, clinopyroxene, plagioclase, magnetite) prior to eruption. One isochron gave a crystallization age that is ~ 20-25??ka older than its corresponding eruptive age, and is interpreted to reflect mixing of older and juvenile crystals or a protracted period of magma storage in the crust. Much of the eruptive volume since 350??ka consists of lavas that have small to moderate 230Th excesses (2-16%), which are likely inherited from melting of a garnet-bearing intraplate ("OIB-like") mantle source. Following melt generation and subsequent migration through the upper mantle, most Mt. Adams magmas interacted with young, mafic lower crust, as indicated by 187Os/188Os ratios that are substantially more radiogenic than the mantle or those expected via mixing of subducted material and the mantle wedge. Moreover, Os-Th isotope variations suggest that unusually large 230Th excesses (25-48%) and high 187Os/188Os ratios in some peripheral lavas reflect assimilation of small degree partial melts of pre-Quaternary basement that had residual garnet or Al-rich clinopyroxene. Despite the isotopic evidence for lower crustal assimilation, these processes are not generally recorded in the erupted phenocrysts, indicating that the crystal record of the deep-level 'cryptic' processes has been

  8. Food and Environmental Protection Laboratory, Seibersdorf: Discrimination of honey of different floral origins by a combination of various chemical parameters; Stable Isotopes Applied to Authenticating Honey; The use of analyte protectants in pesticide residue analytical work

    In the previous newsletter, we reported on research into methodology for the classification of honey of various floral and geographical origins using UPLC-QToF MS and MVA.The research on honey authenticity was expanded using multivariate data analysis of data generated by a number of different analytical techniques to discriminate honeys of different floral origins. The feasibility of a multivariate approach, including various chemical parameters and multivariate data analysis, for the discrimination of various honeys originating from one region, was explored. One of the earliest applications of nuclear techniques for food authenticity was the use of carbon isotopes to detect the addition of cheap sugars in honey in the 1970s. The principle is that the cheap sugar (fructose) is derived from corn and has a higher 13C/12C that the fructose from honey. This difference is due to the different photosynthetic pathways; corn is a C4 plant and that mechanism does not discriminate against the 13C as much as the C3 pathway used by most honey-producing plants. Consequently the two plant types have quite different carbon isotope ratios. Thus measurements of the carbon isotope ratios can distinguish between the two sources of fructose. However, within each plant population there is natural variability in isotope ratios. This makes detecting the addition of small amounts of corn syrup difficult. The test was further refined by its developers to use 13C/12C measurements on protein purified from the honey as an internal reference, based on the fact that if the sugar and protein are from the same plant then they should be closely related in isotopic ratio. This refined method was adopted by the Association of Analytical Chemists as an official method (AOAC 998.12) and is part of the Codex Alimentarius standard for testing authenticity of honey. This test is generally reliable. However, some honey, notably New Zealand manuka, has a frequent fail rate. Manuka is a premium honey

  9. Diet-consumer nitrogen isotope fractionation for prolonged fasting arthropods.

    Mizota, Chitoshi; Yamanaka, Toshiro

    2011-12-01

    Nitrogen acquisition for cellular metabolism during diapause is a primary concern for herbivorous arthropods. Analyses of naturally occurring stable isotopes of nitrogen help elucidate the mechanism. Relevant articles have cited (58 times up to mid-June 2011) anomalously elevated δ(15)N (per mil deviation of (15)N/(14)N, relative to atmospheric nitrogen=0 ‰) values (diet-consumer nitrogen isotope fractionation; up to 12 ‰) for a prolonged fasting raspberry beetle (Byturus tomentosus Degeer (Coleoptera: Byturidae)), which feeds on red raspberries (Rubus idaeus: δ(15)N= ~ +2 ‰). Biologists have hypothesised that extensive recycling of amino acid nitrogen is responsible for the prolonged fasting. Since this hypothesis was proposed in 1995, scientists have integrated biochemical and molecular knowledge to support the mechanism of prolonged diapausing of animals. To test the validity of the recycling hypothesis, we analysed tissue nitrogen isotope ratios for four Japanese arthropods: the shield bug Parastrachia japonensis Scott (Hemiptera: Cydnidae), the burrower bug Canthophorus niveimarginatus Scott (Hemiptera: Cydnidae), leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) and the Japanese oak silkworm Antheraea yamamai (Lepidoptera: Saturniidae), all of which fast for more than 6 months as part of their life-history strategy. Resulting diet-consumer nitrogen isotope discrimination during fasting ranged from 0 to 7‰, as in many commonly known terrestrial arthropods. We conclude that prolonged fasting of arthropods does not always result in anomalous diet-consumer nitrogen isotope fractionation, since the recycling process is closed or nearly closed with respect to nitrogen isotopes. PMID:22166153

  10. Quantitative evaluation of simultaneous reconstruction with model-based crosstalk compensation for 99mTc∕123I dual-isotope simultaneous acquisition brain SPECT

    Du, Yong; Frey, Eric C.

    2009-01-01

    A model-based method has been previously developed to estimate and compensate for the crosstalk and downscatter contamination in simultaneous 123I∕99mTc dual-isotope SPECT imaging. In this method, photon scatter in the object is modeled using the effective source scatter estimate technique. Photon interactions with the collimator-detector are estimated using precalculated Monte Carlo simulated point response functions. Two different approaches, simultaneous and alternating model-based compens...

  11. Development, optimisation, and application of ICP-SFMS methods for the measurement of isotope ratios

    Stuerup, S

    2000-07-01

    The measurement of isotopic composition and isotope ratios in biological and environmental samples requires sensitive, precise, and accurate analytical techniques. The analytical techniques used are traditionally based on mass spectrometry, among these techniques is the ICP-SFMS technique, which became commercially available in the mid 1990s. This technique is characterised by high sensitivity, low background, and the ability to separate analyte signals from spectral interferences. These features are beneficial for the measurement of isotope ratios and enable the measurement of isotope ratios of elements, which it has not previously been possible to measure due to either spectral interferences or poor sensitivity. The overall purpose of the project was to investigate the potential of the single detector ICP-SFMS technique for the measurement of isotope ratios in biological and environmental samples. One part of the work has focused on the fundamental aspects of the ICP-SFMS technique with special emphasize on the features important to the measurement of isotope ratios, while another part has focused on the development, optimisation and application of specific methods for the measurement of isotope ratios of elements of nutritional interest and radionuclides. The fundamental aspects of the ICP-SFMS technique were investigated theoretically and experimentally by the measurement of isotope ratios applying different experimental conditions. It was demonstrated that isotope ratios could be measured reliably using ICP-SFMS by educated choice of acquisition parameters, scanning mode, mass discrimination correction, and by eliminating the influence of detector dead time. Applying the knowledge gained through the fundamental study, ICP-SFMS methods for the measurement of isotope ratios of calcium, zinc, molybdenum and iron in human samples and a method for the measurement of plutonium isotope ratios and ultratrace levels of plutonium and neptunium in environmental samples

  12. Development, optimisation, and application of ICP-SFMS methods for the measurement of isotope ratios

    The measurement of isotopic composition and isotope ratios in biological and environmental samples requires sensitive, precise, and accurate analytical techniques. The analytical techniques used are traditionally based on mass spectrometry, among these techniques is the ICP-SFMS technique, which became commercially available in the mid 1990s. This technique is characterised by high sensitivity, low background, and the ability to separate analyte signals from spectral interferences. These features are beneficial for the measurement of isotope ratios and enable the measurement of isotope ratios of elements, which it has not previously been possible to measure due to either spectral interferences or poor sensitivity. The overall purpose of the project was to investigate the potential of the single detector ICP-SFMS technique for the measurement of isotope ratios in biological and environmental samples. One part of the work has focused on the fundamental aspects of the ICP-SFMS technique with special emphasize on the features important to the measurement of isotope ratios, while another part has focused on the development, optimisation and application of specific methods for the measurement of isotope ratios of elements of nutritional interest and radionuclides. The fundamental aspects of the ICP-SFMS technique were investigated theoretically and experimentally by the measurement of isotope ratios applying different experimental conditions. It was demonstrated that isotope ratios could be measured reliably using ICP-SFMS by educated choice of acquisition parameters, scanning mode, mass discrimination correction, and by eliminating the influence of detector dead time. Applying the knowledge gained through the fundamental study, ICP-SFMS methods for the measurement of isotope ratios of calcium, zinc, molybdenum and iron in human samples and a method for the measurement of plutonium isotope ratios and ultratrace levels of plutonium and neptunium in environmental samples

  13. Discrimination alleged.

    1998-12-25

    The Massachusetts Commission Against Discrimination found probable cause to believe that Dr. [name removed] denied [name removed] reproductive services because [name removed] is gay, which [name removed] associates with being at high risk for HIV. [Name removed] claimed that the doctor refused to bank and transport his semen for artificial insemination. [Name removed], the father of one, tested negative and possesses no risk of infecting the would-be mother. The Commission will hold a conciliation session to try and resolve the dispute. If the session is not successful, the Commission will conduct an evidentiary hearing. PMID:11366047

  14. Mass discrimination

    The pertinent and well-known problem of the discriminative effect produced by small orifices used in mass-spectrometric ion sampling from gas discharges is one which is unfortunately not well understood. The problem has been investigated experimentally by Kingsman and Rees and by Milloy and Elford for particular experimental conditions. Parkes has investigated the problem theoretically for high-pressure discharges, where convective flow through the hole dominates. The present communication seeks to provide a simple method for calculating ion transmission coefficients through such orifices for the special case where the gas mean free path is greater than the orifice diameter and the ions have ab imposed additional axial velocity component due either to an electric-field drift velocity or to a flow velocity (flowing afterglows). (orig.)

  15. Quantitative evaluation of simultaneous reconstruction with model-based crosstalk compensation for 99mTc/123I dual-isotope simultaneous acquisition brain SPECT.

    Du, Yong; Frey, Eric C

    2009-06-01

    A model-based method has been previously developed to estimate and compensate for the crosstalk and downscatter contamination in simultaneous 123I/99mTc dual-isotope SPECT imaging. In this method, photon scatter in the object is modeled using the effective source scatter estimate technique. Photon interactions with the collimator-detector are estimated using precalculated Monte Carlo simulated point response functions. Two different approaches, simultaneous and alternating model-based compensations, have been proposed for iterative reconstruction-based crosstalk and downscatter contamination compensation. In this work, both model-based approaches were evaluated in the context of quantitative accuracy when imaging the dopaminergic system using both Monte Carlo simulated and experimentally acquired data. Results indicate that mddel-based estimates of the crosstalk and downscatter contamination in both energy windows were in good agreement with the truth for the simulated data. The effects of the contamination reduced image contrast and overestimated absolute activity in all structures by up to 66%. Compensation using both model-based approaches improved image contrast. Errors in absolute activity quantitation were also reduced to less than +/-5% for most brain structures. The accuracy of striatal specific binding potentials, calculated as the ratio of activity in various striatal structures to the background, was also greatly improved after model-based compensation. In conclusion, model-based compensation of simultaneously acquired images of 99mTc and 123I labeled brain imaging agents provided image quality and quantitative accuracy that were comparable to the image without crosstalk. Both proposed compensation approaches can potentially be applied clinically, but when reconstruction time is a limiting factor, the alternating model-based compensation may be preferable. PMID:19610291

  16. Electrocardiographic-gated dual-isotope simultaneous acquisition SPECT using 18F-FDG and 99mTc-sestamibi to assess myocardial viability and function in a single study

    Dual-isotope simultaneous acquisition single-photon emission computed tomography (DISA SPECT) with 18F-fluorodeoxyglucose (FDG) and 99mTc-sestamibi appears attractive for the detection of viable myocardium because it permits simultaneous assessment of glucose utilisation and perfusion. Another potential benefit of this approach is that the measurement of left ventricular (LV) function may be possible by ECG gating. The aim of this study was to test the hypothesis that both myocardial viability and LV function can be assessed by a single ECG-gated 18F-FDG/99mTc-sestamibi DISA SPECT study, based on comparison with 18F-FDG/13N-ammonia positron emission tomography (PET) and magnetic resonance imaging (MRI) as reference techniques. Thirty-three patients with prior myocardial infarction underwent ECG-gated 18F-FDG/99mTc-sestamibi DISA SPECT and 18F-FDG/13N-ammonia PET on a single day. Of these, 25 patients also underwent cine-MRI to assess LV function. The LV myocardium was divided into nine regions, and each region was classified as viable or scar using a semiquantitative visual scoring system as well as quantitative analysis. The global and regional LV function measured by gated SPECT was compared with the results of MRI. There was good agreement in respect of viability (90-96%, κ0.74-0.85) between DISA SPECT and PET by either visual or quantitative analysis. Furthermore, although both global and regional LV function measured by gated SPECT agreed with those by MRI, 99mTc-sestamibi showed a closer correlation with MRI than did 18F-FDG. In conclusion, ECG-gated DISA SPECT provides information on myocardial viability, as well as global and regional LV function, similar to that obtained by PET and MRI. (orig.)

  17. Socially-Tolerable Discrimination

    J. Atsu Amegashie

    2008-01-01

    History is replete with overt discrimination of various forms. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race or gender is much less acceptable. Why? I develop a simple model of conflict which is driven by either racial (gender) discrimination or generational discrimination (i.e., young versus old). I show that there exist parameters of the model where racial (gender) di...

  18. Carbon isotope effects in plants related to photosynthesis

    Plants contain less 13C than the atmosphere due to both enzymatic and physical processes that discriminate against the heavier isotope in favour of the lighter one. These differences have allowed us to use isotopic signature to identify photosynthetic pathways of many plant species. The purpose of this study is to present a method for measuring the carbon isotope discrimination in the leaf of the plant. We carried out conversion of organic sample from two species (Prunus amygdalus and Rosa) to CO2 by dry combustion in an excess of oxygen. The stable carbon isotope ratio (13C/12C) was measured with high precision by a mass spectrometer. This isotopic discrimination was used to assess the ratio of intercellular to atmospheric CO2 concentration, ci/ca. We plan to use the isotopic discrimination to estimate plant water-use efficiency, a relevant parameter for conferring tolerance of the plant to environmental stress. (authors)

  19. An in-depth evaluation of accuracy and precision in Hg isotopic analysis via pneumatic nebulization and cold vapor generation multi-collector ICP-mass spectrometry.

    Rua-Ibarz, Ana; Bolea-Fernandez, Eduardo; Vanhaecke, Frank

    2016-01-01

    Mercury (Hg) isotopic analysis via multi-collector inductively coupled plasma (ICP)-mass spectrometry (MC-ICP-MS) can provide relevant biogeochemical information by revealing sources, pathways, and sinks of this highly toxic metal. In this work, the capabilities and limitations of two different sample introduction systems, based on pneumatic nebulization (PN) and cold vapor generation (CVG), respectively, were evaluated in the context of Hg isotopic analysis via MC-ICP-MS. The effect of (i) instrument settings and acquisition parameters, (ii) concentration of analyte element (Hg), and internal standard (Tl)-used for mass discrimination correction purposes-and (iii) different mass bias correction approaches on the accuracy and precision of Hg isotope ratio results was evaluated. The extent and stability of mass bias were assessed in a long-term study (18 months, n = 250), demonstrating a precision ≤0.006% relative standard deviation (RSD). CVG-MC-ICP-MS showed an approximately 20-fold enhancement in Hg signal intensity compared with PN-MC-ICP-MS. For CVG-MC-ICP-MS, the mass bias induced by instrumental mass discrimination was accurately corrected for by using either external correction in a sample-standard bracketing approach (SSB) or double correction, consisting of the use of Tl as internal standard in a revised version of the Russell law (Baxter approach), followed by SSB. Concomitant matrix elements did not affect CVG-ICP-MS results. Neither with PN, nor with CVG, any evidence for mass-independent discrimination effects in the instrument was observed within the experimental precision obtained. CVG-MC-ICP-MS was finally used for Hg isotopic analysis of reference materials (RMs) of relevant environmental origin. The isotopic composition of Hg in RMs of marine biological origin testified of mass-independent fractionation that affected the odd-numbered Hg isotopes. While older RMs were used for validation purposes, novel Hg isotopic data are provided for the

  20. Auditory Phoneme Discrimination in Illiterates: Mismatch Negativity--A Question of Literacy?

    Schaadt, Gesa; Pannekamp, Ann; van der Meer, Elke

    2013-01-01

    These days, illiteracy is still a major problem. There is empirical evidence that auditory phoneme discrimination is one of the factors contributing to written language acquisition. The current study investigated auditory phoneme discrimination in participants who did not acquire written language sufficiently. Auditory phoneme discrimination was…

  1. Mergers & Acquisitions

    Fomcenco, Alex

    This dissertation is a legal dogmatic thesis, the goal of which is to describe and analyze the current state of law in Europe in regard to some relevant selected elements related to mergers and acquisitions, and the adviser’s counsel in this regard. Having regard to the topic of the dissertation...

  2. Gender Discrimination in English

    廖敏慧

    2014-01-01

    Gender discrimination in language is usually defined as discrimination based on sex, especially discrimination against women. With the rise of women’s liberation movement in the 1960s and 1970s, and the improvement of women’s social status in recent years, gender discrimination in English attracts more and more attention. Based on previous studies, this thesis first dis⁃cusses the manifestations of gender discrimination in English vocabulary and address terms, then analyzes the factors of gender dis⁃crimination in English from social and cultural perspectives, finally puts forward some methods that are good for avoiding or elim⁃inating gender discrimination in English.

  3. Unsupervised Linear Discriminant Analysis

    2006-01-01

    An algorithm for unsupervised linear discriminant analysis was presented. Optimal unsupervised discriminant vectors are obtained through maximizing covariance of all samples and minimizing covariance of local k-nearest neighbor samples. The experimental results show our algorithm is effective.

  4. Airline Price Discrimination

    Stacey, Brian

    2015-01-01

    Price discrimination enjoys a long history in the airline industry. Borenstein (1989) discusses price discrimination through frequent flyer programs from 1985 as related to the Piedmont-US Air merger, price discrimination strategies have grown in size and scope since then. From Saturday stay over requirements to varying costs based on time of purchase, the airline industry is uniquely situated to enjoy the fruits of price discrimination.

  5. Isotopic Biogeochemistry

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  6. The Badness of Discrimination

    Lippert-Rasmussen, Kasper

    2006-01-01

    . In this paper I address these issues. First, I offer a taxonomy of discrimination. I then argue that discrimination is bad, when it is, because it harms people. Finally, I criticize a rival, disrespect-based account according to which discrimination is bad regardless of whether it causes harm....

  7. Dissimilar cannabinoid substitution patterns in mice trained to discriminate Δ9-tetrahydrocannabinol or methanandamide from vehicle

    Wiley, Jenny L.; Walentiny, D. Matthew; Vann, Robert E.; Baskfield, Cassandra Y.

    2011-01-01

    Δ9-Tetrahydrocannabinol (THC) discrimination in rodents is a behavioral assay that has been used to probe differences among classes of cannabinoids in rats. The purpose of this study was to determine whether traditional and anandamide-like cannabinoids were distinguishable in cannabinoid discrimination procedures in mice. Male mice were trained to discriminate 30 mg/kg THC or 70 mg/kg methanandamide from vehicle in a two-lever milk-reinforced drug discrimination procedure. After acquisition, ...

  8. Discriminately Decreasing Discriminability with Learned Image Filters

    Whitehill, Jacob

    2011-01-01

    In machine learning and computer vision, input images are often filtered to increase data discriminability. In some situations, however, one may wish to purposely decrease discriminability of one classification task (a "distractor" task), while simultaneously preserving information relevant to another (the task-of-interest): For example, it may be important to mask the identity of persons contained in face images before submitting them to a crowdsourcing site (e.g., Mechanical Turk) when labeling them for certain facial attributes. Another example is inter-dataset generalization: when training on a dataset with a particular covariance structure among multiple attributes, it may be useful to suppress one attribute while preserving another so that a trained classifier does not learn spurious correlations between attributes. In this paper we present an algorithm that finds optimal filters to give high discriminability to one task while simultaneously giving low discriminability to a distractor task. We present r...

  9. Using Questions To Facilitate Motor Skill Acquisition.

    Knight, G. William; And Others

    1997-01-01

    Describes a dental teaching strategy that promotes acquisition of psychomotor skills through use of metacognition and problem-solving. In five steps, questions are asked to guide the learner through a sequence of discriminations leading to recognition of problems and solutions. Clearly defined criteria in a sequence reflecting procedure are…

  10. The economics of sex discrimination

    Dagmar Brožová

    2006-01-01

    Paper outlines economic connections of labor market discrimination. It is intended on discrimination based upon gender, because this type of discrimination is on the point of our social background. In the introductory part are defined discrimination and delineated the various types of discrimination. Further there are presented data to suggest the possibility of discrimination. The major part of paper presents four important labor market models of discrimination: taste for discrimination mode...

  11. Recent development in isotope ratio mass spectrometry

    Within the limited of this review the following topics will be briefly discussed: a) Accuracy, precision, internal relative standard deviation (RISD) and external relative standard deviation (RESD) of isotope ratio measurements. With advanced instrumentation and use of standard reference materials, high accuracy and RESD = 0.002% (or better) may be achieved; b) The advantages of modern automatic isotope ratio mass spectrometer are briefly described. Computer controlled operation and data acquisition, and multiple ion collection are the recent important improvement; c) The isotopic fractionation during the course of isotope ratio measurement is considered as a major source of errors in thermal ionization of metallic elements. The phenomenon in strontium, neodymium, uranium, lead and calcium and methods to correct the measured data are discussed; d) Applications of isotope ratio mass spectrometry in atomic weight determinations, the isotope dilution technique, isotope geology, and isotope effects in biological systems are described together with specific applications in various research and technology area. (author)

  12. 用于气候分析的树木年轮稳定同位素资料获取方法与质量控制%Method of Tree-ring Stable Isotope Data Acquisition and Its Quality Control for Dendroclimatological Research

    尚华明; 刘晓宏; 张瑞波; 魏文寿; 袁玉江; 喻树龙; 张同文; 陈峰

    2012-01-01

    With the development of plant physiology and mass spectrometry analysis technique, stable isotope played a more and more important role in dendroclimatology. This paper summarized the method of tree ring stable isotope data acquisition and its quality control for dendroclimatological research. It included the requirement for the tree ring sample, extracting procedure of tree ring cellulose, the mass spectrograph analysis method for tree ring stable isotope and the data treatment method. It would provide the references for tree ring stable isotope research, enhance the data comparability between laboratories, and establish the foundation of tree ring stable isotope network.%随着稳定同位素分析技术的进步和植物生理学研究的发展,稳定同位素在树轮气候研究中扮演着日益重要的角色。本文总结了用于气候分析的树木年轮稳定同位素资料获取与质量控制方法。包括对分析树轮样品的要求、树轮纤维素提取实验流程、树轮同位素的质谱分析方法和稳定碳同位素数据的处理方法等。为树轮稳定同位素实验分析提供参考,便于获得可靠的树轮同位素数据,且能够进行不同实验室之间数据结果的对比,为建立树木年轮同位素网络奠定基础。

  13. Short course on St-02 applications of isotope dilutions and isotopic measurements

    Miller, P.

    1998-01-05

    This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological.

  14. Isotopic clusters

    Spectra of isotopically mixed clusters (dimers of SF6) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

  15. Isotopic geology

    Born from the application to geology of nuclear physics techniques, the isotopic geology has revolutionized the Earth's sciences. Beyond the dating of rocks, the tracer techniques have permitted to reconstruct the Earth's dynamics, to measure the temperatures of the past (giving birth to paleoclimatology) and to understand the history of chemical elements thanks to the analysis of meteorites. Today, all domains of Earth sciences appeal more or less to the methods of isotopic geology. In this book, the author explains the principles, methods and recent advances of this science: 1 - isotopes and radioactivity; 2 - principles of isotope dating; 3 - radio-chronological methods; 4 - cosmogenic isotope chronologies; 5 - uncertainties and radio-chronological results; 6 - geochemistry of radiogenic isotopes; 7 - geochemistry of stable isotopes; 8 - isotopic geology and dynamical analysis of reservoirs. (J.S.)

  16. Socially-Tolerable Discrimination

    Amegashie, J. Atsu

    2008-01-01

    History is replete with overt discrimination on the basis of race, gender, age, citizenship, ethnicity, marital status, academic performance, health status, volume of market transactions, religion, sexual orientation, etc. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race, gender, or ethnicity is much less acceptable. Why? I develop a simple rent-seeking model of conflict w...

  17. Socially-Tolerable Discrimination

    Amegashie, J. Atsu

    2008-01-01

    History is replete with overt discrimination on the basis of race, gender, age, citizenship, ethnicity, marital status, academic performance, health status, volume of market transactions, religion, sexual orientation, etc. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race, gender, or ethnicity is much less acceptable. Why? I develop a simple model of conflict which is drive...

  18. Socially-tolerable discrimination

    Amegashie, J. Atsu

    2008-01-01

    History is replete with overt discrimination on the basis of race, gender, age, citizenship, ethnicity, marital status, academic performance, health status, volume of market transactions, religion, sexual orientation, etc. However, these forms of discrimination are not equally tolerable. For example, discrimination based on immutable or prohibitively unalterable characteristics such as race, gender, or ethnicity is much less acceptable. Why? I develop a simple rent-seeking model of conflict w...

  19. Age Discrimination in Italy

    Olga Rymkevitch; Claudia Villosio

    2007-01-01

    The Framework Directive on Equal Treatment in Employment and Occupation (2000/78/EC) included age as one of its prohibited grounds of discrimination. Member States were required to transpose this Directive by December 2003. In Italy age discrimination was explicitly regulated by means of Legislative Decree no. 216, 9 July 2003. The Decree introduced the new specific prohibition of discrimination, defining its application, exceptions and remedies. The purpose of this paper is to explore, in a ...

  20. INTERSECTIONAL DISCRIMINATION AGAINST CHILDREN

    Ravnbøl, Camilla Ida

    This paper adds a perspective to existing research on child protection by engaging in a debate on intersectional discrimination and its relationship to child protection. The paper has a twofold objective, (1) to further establish intersectionality as a concept to address discrimination against...

  1. Discriminants of multilinear systems

    Emiris, Ioannis Z.; Vidunas, Raimundas

    2016-01-01

    We study well-constrained bilinear algebraic systems in order to formulate their discriminant. We derive a new determinantal formula for the discriminant of a multilinear system that appears in the study of Nash equilibria of multiplayer games with mixed strategies.

  2. Flash-Type Discrimination

    Koshak, William J.

    2010-01-01

    This viewgraph presentation describes the significant progress made in the flash-type discrimination algorithm development. The contents include: 1) Highlights of Progress for GLM-R3 Flash-Type discrimination Algorithm Development; 2) Maximum Group Area (MGA) Data; 3) Retrieval Errors from Simulations; and 4) Preliminary Global-scale Retrieval.

  3. Measuring SNM Isotopic Distributions using FRAM

    Geist, William H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  4. 2015 NAIP Acquisition Map

    Farm Service Agency, Department of Agriculture — Planned States for 2015 NAIP acquisition and acquisition status layer (updated daily). Updates to the acquisition seasons may be made during the season to...

  5. 2016 NAIP Acquisition Map

    Farm Service Agency, Department of Agriculture — Planned States for 2016 NAIP acquisition and acquisition status layer (updated daily). Updates to the acquisition seasons may be made during the season to...

  6. 超高产杂交稻剑叶中C4途径酶活性和稳定碳同位素分异作用的变化%Changes in the Activities of C4 Pathway Enzymes and Stable Carbon Isotope Discrimination in Flag Leaves of Super High-yield Hybrid Rice

    阳成伟; 林桂珠; 彭长连; 陈贻竹; 欧志英

    2003-01-01

    以超高产杂交水稻(Oryza sativa L.)"培矮64S/E32"和多年来大面积推广的杂交稻"汕优63"为材料,研究孕穗后剑叶中C4途径酶和对稳定碳同位素分异作用的变化.结果表明,籽粒灌浆期(移栽后68~75 d)的两个品种剑叶中NADP-MDH活性最高,随后下降;超高产杂交水稻"培矮64S/E32"的NADP-MDH的活性明显高于"汕优63";PEPCase和NADP-ME活性在黄熟期之前的叶片中持续上升.不同生育期的叶片与籽粒的△1aC值相近(19.49‰~19.82‰),在成熟期时较高.超高产水稻"培矮64S/E32"叶片的平均△13C值比"汕优63"高0.43‰.%Activities of several key enzymes of C4 photosynthesis pathway and stable carbon isotope discrimination were investigated in flag leaves of a super high-yield hybrid rice (Oryza sativa L.) cv. Peiai 64S/E32 and a traditional hybrid rice cv. Shanyou 63 at different developing stages. Results show that the activity of PEP carboxylase (PEPCase) increased with age of flag leave; the activity of NADP-malate dehydrogenase (NADP-MDH) increased and reached to a peak value at grain filling stage (68-75 d after transplanting), then fell down; the activity of NADP-MDH in cv. Peiai 64S/E32 was much higher than that in cv. Shanyou 63. Before ripening stage (95 d after transplanting), NADP-malic enzyme activity rose gradually. The level of stable carbon isotope discrimination (△13C) in flag leaves and grains at different developing stages were similar and exhibited a comparative high value at ripening stage. The average △13C in leaf of cv. Peiai 64S/E32 during different developing stages was 0.43‰ more than that in cv. Shanyou 63.

  7. Acquisition of chemical recognition cues facilitates integration into ant societies

    von Beeren Christoph

    2011-12-01

    Full Text Available Abstract Background Social insects maintain the integrity of their societies by discriminating between colony members and foreigners through cuticular hydrocarbon (CHC signatures. Nevertheless, parasites frequently get access to social resources, for example through mimicry of host CHCs among other mechanisms. The origin of mimetic compounds, however, remains unknown in the majority of studies (biosynthesis vs. acquisition. Additionally, direct evidence is scarce that chemical mimicry is indeed beneficial to the parasites (e.g., by improving social acceptance. Results In the present study we demonstrated that the kleptoparasitic silverfish Malayatelura ponerophila most likely acquires CHCs directly from its host ant Leptogenys distinguenda by evaluating the transfer of a stable-isotope label from the cuticle of workers to the silverfish. In a second experiment, we prevented CHC pilfering by separating silverfish from their host for six or nine days. Chemical host resemblance as well as aggressive rejection behaviour by host ants was then quantified for unmanipulated and previously separated individuals. Separated individuals showed reduced chemical host resemblance and they received significantly more aggressive rejection behaviour than unmanipulated individuals. Conclusion Our study clarifies the mechanism of chemical mimicry in a social insect parasite in great detail. It shows empirically for the first time that social insect parasites are able to acquire CHCs from their host. Furthermore, it demonstrates that the accuracy of chemical mimicry can be crucial for social insect parasites by enhancing social acceptance and, thus, allowing successful exploitation. We discuss the results in the light of coevolutionary arms races between parasites and hosts.

  8. Quantum state discrimination

    Recently it has been shown that two pure quantum states can be discriminated by using the concept of PT- invariant non- Hermitian system. Here we demonstrate how to discriminate two non-orthogonal, entangled quantum state which are slightly different from each other by using pseudo-Hermitian system. The positive definite metric operator which makes the pseudo-Hermitian systems fully consistent quantum theory is used for such a state discrimination. We further show that non- orthogonal states can evolve through a suitably constructed pseudo-Hermitian Hamiltonian to orthogonal states. Such an evolution ceases at exceptional points of the pseudo-Hermitian system. (author)

  9. Harassment, Bias, and Discrimination.

    Welliver, Paul W.

    1995-01-01

    Discusses a new principle which has been added to the AECT (Association for Educational Communications and Technology) Code of Professional Ethics regarding discrimination, harassment, and bias. An example is presented which illustrates a violation of a professional colleague's rights. (LRW)

  10. Multiplicities of dihedral discriminants

    Mayer, Daniel C.

    1992-04-01

    Given the discriminant {d_k} of a quadratic field k, the number of cyclic relative extensions N\\vert k of fixed odd prime degree p with dihedral absolute Galois group of order 2p, which share a common conductor f, is called the multiplicity of the dihedral discriminant {d_N} = {f^{2(p - 1)}}d_k^p . In this paper, general formulas for multiplicities of dihedral discriminants are derived by analyzing the p-rank of the ring class group mod f of k. For the special case p = 3,{d_k} = - 3 , an elementary proof is given additionally. The theory is illustrated by a discussion of all known discriminants of multiplicity ≥ 5 of totally real and complex cubic fields.

  11. Angular velocity discrimination

    Kaiser, Mary K.

    1990-01-01

    Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

  12. Analytic boosted boson discrimination

    Andrew J. Larkoski; Moult, Ian; Neill, Duff

    2015-01-01

    Observables which discriminate boosted topologies from massive QCD jets are of great importance for the success of the jet substructure program at the Large Hadron Collider. Such observables, while both widely and successfully used, have been studied almost exclusively with Monte Carlo simulations. In this paper we present the first all-orders factorization theorem for a two-prong discriminant based on a jet shape variable, $D_2$, valid for both signal and background jets. Our factorization t...

  13. Workplace Discrimination Outcomes and Their Predictive Factors for Adults with Multiple Sclerosis

    Roessler, Richard T.; Neath, Jeanne; McMahon, Brian T.; Rumrill, Phillip D.

    2007-01-01

    Because employment is a significant predictor of the quality of life of people with disabilities (Rumrill, Roessler, & Fitzgerald, 2004; Viermo & Krause, 1998), discrimination in the workplace that interferes with successful job acquisition or retention is a serious matter. Unfortunately, this type of discrimination is all too prevalent. In a…

  14. Impaired Discrimination Learning in Mice Lacking the NMDA Receptor NR2A Subunit

    Brigman, Jonathan L.; Feyder, Michael; Saksida, Lisa M.; Bussey, Timothy J.; Mishina, Masayoshi; Holmes, Andrew

    2008-01-01

    N-Methyl-D-aspartate receptors (NMDARs) mediate certain forms of synaptic plasticity and learning. We used a touchscreen system to assess NR2A subunit knockout mice (KO) for (1) pairwise visual discrimination and reversal learning and (2) acquisition and extinction of an instrumental response requiring no pairwise discrimination. NR2A KO mice…

  15. Alpha-beta discrimination in LENA

    Alpha emitting isotopes, mainly 210Po, provide a background for the detection of 7Be neutrinos in LENA (Low Energy Neutrino Astronomy). This background can be reduced by a pulse shape analysis, as alpha particles and electrons have a different typical pulse shape, caused by the different energy deposition per unit path length ((dE)/(dx)). Thus, the efficiency of this method was analyzed by a detailed Monte Carlo study. Several scintillators as well as the influence of the photomultiplier performance on the discrimination efficiency were investigated.

  16. Arrhythmia discrimination using a smart phone.

    Chong, Jo Woon; Esa, Nada; McManus, David D; Chon, Ki H

    2015-05-01

    We hypothesize that our smartphone-based arrhythmia discrimination algorithm with data acquisition approach reliably differentiates between normal sinus rhythm (NSR), atrial fibrillation (AF), premature ventricular contractions (PVCs) and premature atrial contraction (PACs) in a diverse group of patients having these common arrhythmias. We combine root mean square of successive RR differences and Shannon entropy with Poincare plot (or turning point ratio method) and pulse rise and fall times to increase the sensitivity of AF discrimination and add new capabilities of PVC and PAC identification. To investigate the capability of the smartphone-based algorithm for arrhythmia discrimination, 99 subjects, including 88 study participants with AF at baseline and in NSR after electrical cardioversion, as well as seven participants with PACs and four with PVCs were recruited. Using a smartphone, we collected 2-min pulsatile time series from each recruited subject. This clinical application results show that the proposed method detects NSR with specificity of 0.9886, and discriminates PVCs and PACs from AF with sensitivities of 0.9684 and 0.9783, respectively. PMID:25838530

  17. Towards robust speech acquisition using sensor arrays

    Maganti, Hari Krishna

    2007-01-01

    An integrated system approach was developed to address the problem of distant speech acquisition in multi-party meetings, using multiple microphones and cameras. Microphone array processing techniques have presented a potential alternative to close-talking microphones by providing speech enhancement through spatial filtering and directional discrimination. These techniques relied on accurate speaker locations for optimal performance. Tracking accurate speaker locations solely based on audio w...

  18. Learning discriminant face descriptor.

    Lei, Zhen; Pietikäinen, Matti; Li, Stan Z

    2014-02-01

    Local feature descriptor is an important module for face recognition and those like Gabor and local binary patterns (LBP) have proven effective face descriptors. Traditionally, the form of such local descriptors is predefined in a handcrafted way. In this paper, we propose a method to learn a discriminant face descriptor (DFD) in a data-driven way. The idea is to learn the most discriminant local features that minimize the difference of the features between images of the same person and maximize that between images from different people. In particular, we propose to enhance the discriminative ability of face representation in three aspects. First, the discriminant image filters are learned. Second, the optimal neighborhood sampling strategy is soft determined. Third, the dominant patterns are statistically constructed. Discriminative learning is incorporated to extract effective and robust features. We further apply the proposed method to the heterogeneous (cross-modality) face recognition problem and learn DFD in a coupled way (coupled DFD or C-DFD) to reduce the gap between features of heterogeneous face images to improve the performance of this challenging problem. Extensive experiments on FERET, CAS-PEAL-R1, LFW, and HFB face databases validate the effectiveness of the proposed DFD learning on both homogeneous and heterogeneous face recognition problems. The DFD improves POEM and LQP by about 4.5 percent on LFW database and the C-DFD enhances the heterogeneous face recognition performance of LBP by over 25 percent. PMID:24356350

  19. Stable isotopes of captive Cetaceans (Killer Whales and Bottlenose dolphins)

    Caut, Stéphane; Laran, Sophie; Garcia-Hartmann, Emmanuel; Das, Krishna

    2011-01-01

    There is currently a great deal of interest in using stable-isotope methods to investigate diet, trophic level and migration movement in wild cetaceans. Fundamental to the interpretation of these methods is the need to understand how diet isotopic values are reflected in consumer tissues. In this study, we investigated patterns of isotopic discrimination between diet and blood constituents of two species of cetaceans (killer whale, Orcinus orca and 19 bottlenose dolphin, Tursiops truncutus) f...

  20. Analytic Boosted Boson Discrimination

    Larkoski, Andrew J; Neill, Duff

    2015-01-01

    Observables which discriminate boosted topologies from massive QCD jets are of great importance for the success of the jet substructure program at the Large Hadron Collider. Such observables, while both widely and successfully used, have been studied almost exclusively with Monte Carlo simulations. In this paper we present the first all-orders factorization theorem for a two-prong discriminant based on a jet shape variable, $D_2$, valid for both signal and background jets. Our factorization theorem simultaneously describes the production of both collinear and soft subjets, and we introduce a novel zero-bin procedure to correctly describe the transition region between these limits. By proving an all orders factorization theorem, we enable a systematically improvable description, and allow for precision comparisons between data, Monte Carlo, and first principles QCD calculations for jet substructure observables. Using our factorization theorem, we present numerical results for the discrimination of a boosted $Z...

  1. Leatherback Isotopes

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  2. Language Acquisition without an Acquisition Device

    O'Grady, William

    2012-01-01

    Most explanatory work on first and second language learning assumes the primacy of the acquisition phenomenon itself, and a good deal of work has been devoted to the search for an "acquisition device" that is specific to humans, and perhaps even to language. I will consider the possibility that this strategy is misguided and that language…

  3. Isotopic chirality

    Floss, H.G. [Univ. of Washington, Seattle, WA (United States)

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  4. Discriminative Shape Alignment

    Loog, M.; de Bruijne, M.

    taking into account that eventually the shapes are to be assigned to two or more different classes. This work introduces a discriminative variation to well-known Procrustes alignment and demonstrates its benefit over this classical method in shape classification tasks. The focus is on two...

  5. Immunological self, nonself discrimination

    Guillet, J G; Lai, M Z; Briner, T J;

    1987-01-01

    The ability of immunodominant peptides derived from several antigen systems to compete with each other for T cell activation was studied. Only peptides restricted by a given transplantation antigen are mutually competitive. There is a correlation between haplotype restriction, ability to bind to ...... that provides a basis for explaining self, nonself discrimination as well as alloreactivity....

  6. Education and Gender Discrimination

    Sumi, V. S.

    2012-01-01

    This paper discusses the status of women education in present education system and some measures to overcome the lags existing. Discrimination against girls and women in the developing world is a devastating reality. It results in millions of individual tragedies, which add up to lost potential for entire countries. Gender bias in education is an…

  7. Analytic boosted boson discrimination

    Larkoski, Andrew J.; Moult, Ian; Neill, Duff

    2016-05-01

    Observables which discriminate boosted topologies from massive QCD jets are of great importance for the success of the jet substructure program at the Large Hadron Collider. Such observables, while both widely and successfully used, have been studied almost exclusively with Monte Carlo simulations. In this paper we present the first all-orders factorization theorem for a two-prong discriminant based on a jet shape variable, D 2, valid for both signal and background jets. Our factorization theorem simultaneously describes the production of both collinear and soft subjets, and we introduce a novel zero-bin procedure to correctly describe the transition region between these limits. By proving an all orders factorization theorem, we enable a systematically improvable description, and allow for precision comparisons between data, Monte Carlo, and first principles QCD calculations for jet substructure observables. Using our factorization theorem, we present numerical results for the discrimination of a boosted Z boson from massive QCD background jets. We compare our results with Monte Carlo predictions which allows for a detailed understanding of the extent to which these generators accurately describe the formation of two-prong QCD jets, and informs their usage in substructure analyses. Our calculation also provides considerable insight into the discrimination power and calculability of jet substructure observables in general.

  8. Calo trigger acquisition system

    Franchini, Matteo

    2016-01-01

    Calo trigger acquisition system - Evolution of the acquisition system from a multiple boards system (upper, orange cables) to a single board one (below, light blue cables) where all the channels are collected in a single board.

  9. Examining Workplace Discrimination in a Discrimination-Free Environment

    Braxton, Shawn Lamont

    2010-01-01

    Examining Workplace Discrimination in a Discrimination-Free Environment Shawn L. Braxton Abstract The purpose of this study is to explore how racial and gender discrimination is reproduced in concrete workplace settings even when anti-discrimination policies are present, and to understand the various reactions utilized by those who commonly experience it. I have selected a particular medical center, henceforth referred to by a pseudonym, â The Bliley Medical Centerâ as my case ...

  10. Employment Age Discrimination on Women

    黄捧

    2015-01-01

    Employment age discrimination against women is not an unusual phenomenon in China.Through describing the present situation and negative effect of this phenomenon,this paper claims laws are very important weapon to eliminate age discrimination against women.

  11. Multisensory interaction in vibrotactile detection and discrimination of amplitude modulation

    Teodorescu, Kinneret; Bouchigny, Sylvain; Hoffmann, Pablo F.;

    2011-01-01

    selectively sensitive to combination of modality and previous experience. In the domain of discrimination, our results suggest that bi-modal performance is always better than uni-modal performance regardless of order of experience. Second, experiments with expert surgeons revealed that expertise in complex...... skill of maxilla-facial surgery strongly relies on enhanced touch perception, as measured in reaction times and discrimination ability in bi-modal vibro-auditory conditions. These observations suggest that acquisition of mandibular surgery skill has brought to an enhanced representation of vibro...

  12. Discrimination of abiogenic and biogenic alkane gases

    2008-01-01

    We have combined the analytical data of the carbon isotope distribution pattern, R/Ra and CH4/3He values of abiogenic and biogenic (referring to the thermogenic and bacterial or microbial) alkane gases in China with those of alkane gases from USA, Russia, Germany, Australia and other countries. Four discrimination criteria are derived from this comparative study: 1) Carbon isotopic composition is generally greater than -30‰ for abiogenic methane and less than -30‰ for biogenic methane; 2) Abiogenic alkane gases have a carbon isotopic reversal trend (δ 13C1> δ 13C2> δ 13C3> δ 13C4) with δ 13C1>-30‰ in general; 3) Gases with R/Ra >0.5 and δ 13C11 δ 13C2>0 are of abiogenic origin; 4) Gases (meth- ane) with CH4/3He≤106 are of abiogenic origin, whereas gases with CH4/3He≥1011 are of biogenic origin.

  13. Gender wage discrimination in Galicia

    Pena-Boquete, Yolanda

    2005-01-01

    The wage discrimination by gender in the Galician region is one of the highest in Spain, although it presents one of the smallest wage gaps between men and women. The aim of this paper is to extend wage discrimination analysis in Galicia through two complementary theories. First, we approximate global discrimination with the Oaxaca decomposition. This method calculates the discrimination using women and men median characteristics, providing a measure based on the wage distribution average. Af...

  14. The relative merits of discriminating and non-discriminating dosemeters

    Marshal, T. O.; Christensen, Palle; Julius, H. W.; Smith, J. W.

    1986-01-01

    The need for discriminating and non-discriminating personal dosemeters in the field of radiological protection is examined. The ability of various types of dosemeter to meet these needs is also discussed. It is concluded that there is a need for discriminating dosemeters but in the majority of...... cases a simple two element non-discriminating dosemeter will suffice. In cases where the use of discriminating dosemeters is justified, thermoluminescence dosemeters can be designed to provided information on radiation type and energy, but if further information is required the photographic film...

  15. Transgender Discrimination and the Law

    Trotter, Richard

    2010-01-01

    An emerging area of law is developing regarding sex/gender identity discrimination, also referred to as transgender discrimination, as distinguished from discrimination based on sexual orientation. A transgendered individual is defined as "a person who has a gender-identity disorder which is a persistent discomfort about one?s assigned sex or…

  16. Price Discrimination: A Classroom Experiment

    Aguiló, Paula; Sard, Maria; Tugores, Maria

    2016-01-01

    In this article, the authors describe a classroom experiment aimed at familiarizing students with different types of price discrimination (first-, second-, and third-degree price discrimination). During the experiment, the students were asked to decide what tariffs to set as monopolists for each of the price discrimination scenarios under…

  17. Gaussian Discriminating Strength

    Rigovacca, Luca; Farace, Alessandro; De Pasquale, Antonella; Giovannetti, Vittorio

    2015-01-01

    We present a quantifier of non-classical correlations for bipartite, multi-mode Gaussian states. It is derived from the Discriminating Strength measure, introduced for finite dimensional systems in A. Farace et al., New. J. Phys. 16, 073010 (2014). As the latter the new measure exploits the Quantum Chernoff Bound to gauge the susceptibility of the composite system with respect to local perturbations induced by unitary gates extracted from a suitable set of allowed transformations (the latter ...

  18. Diversity, Discrimination, and Performance

    Jonathan S. Leonard; Levine, David I.

    2006-01-01

    Employee diversity may affect business performance both as a result of customer discrimination and as a result of how members of a group work with each other in teams. We test for both channels with data from more than 800 retail stores employing over 70,000 individuals matched to Census data on the demographics of the community. We find little payoff to matching employee demographics to those of potential customers except when the customers do not speak English. Although age diversity doe...

  19. Introduction to multivariate discrimination

    Kégl Balázs

    2013-01-01

    ISBN:978-2-7598-1032-1 International audience Multivariate discrimination or classification is one of the best-studied problem in machine learning, with a plethora of well-tested and well-performing algorithms. There are also several good general textbooks [1-9] on the subject written to an average engineering, computer science, or statistics graduate student; most of them are also accessible for an average physics student with some background on computer science and statistics. Hence, ...

  20. Optimal time discrimination

    Coşkun, Filiz; Sayalı, Zeynep Ceyda; Gürbüz, Emine; Balcı, Fuat

    2015-01-01

    Optimal Time Discrimination Journal: Quarterly Journal of Experimental Psychology Manuscript ID: QJE-STD 14-039.R1 Manuscript Type: Standard Article Date Submitted by the Author: n/a Complete List of Authors: Çoskun, Filiz; Koç University, Psychology Sayalı Ungerer, Zeynep; Koç University, Psychology Gürbüz, Emine; Koç University, Psychology Balcı, Fuat; Koç University, Psychology Keywords: Decision making, Interval Timing, Optimality, Response Times, Temporal ...

  1. Deep Linear Discriminant Analysis

    Dorfer, Matthias; Kelz, Rainer; WIDMER, Gerhard

    2015-01-01

    We introduce Deep Linear Discriminant Analysis (DeepLDA) which learns linearly separable latent representations in an end-to-end fashion. Classic LDA extracts features which preserve class separability and is used for dimensionality reduction for many classification problems. The central idea of this paper is to put LDA on top of a deep neural network. This can be seen as a non-linear extension of classic LDA. Instead of maximizing the likelihood of target labels for individual samples, we pr...

  2. Measuring Discrimination in Education

    Rema Hanna; Leigh Linden

    2009-01-01

    In this paper, we illustrate a methodology to measure discrimination in educational contexts. In India, we ran an exam competition through which children compete for a large financial prize. We recruited teachers to grade the exams. We then randomly assigned child "characteristics" (age, gender, and caste) to the cover sheets of the exams to ensure that there is no systematic relationship between the characteristics observed by the teachers and the quality of the exams. We find that teachers ...

  3. Reproducible high-resolution multispectral image acquisition in dermatology

    Duliu, Alexandru; Gardiazabal, José; Lasser, Tobias; Navab, Nassir

    2015-07-01

    Multispectral image acquisitions are increasingly popular in dermatology, due to their improved spectral resolution which enables better tissue discrimination. Most applications however focus on restricted regions of interest, imaging only small lesions. In this work we present and discuss an imaging framework for high-resolution multispectral imaging on large regions of interest.

  4. Isotope Spectroscopy

    Caffau, E; Bonifacio, P; Ludwig, H -G; Monaco, L; Curto, G Lo; Kamp, I

    2013-01-01

    The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high-resolution, high-quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of 6Li in the stellar atmospheres causes a subtle extra depression in the red wing of the 7Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived $^6$Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non-LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced ...

  5. Statistical Discrimination with Peer Effects: Can Integration Eliminate Negative Stereotypes?

    Chaudhuri, Shubham; Sethi, Rajiv

    2008-01-01

    We introduce peer effects in the costs of human capital acquisition into a model of statistical discrimination in labour markets. This creates a link between the level of segregation in social networks and racial disparities in job assignment and wages. We show that this relationship is characterized by discontinuities: there is a threshold level of segregation below which negative stereotypes become unsustainable, and steady-state skill levels can change dramatically. This change can work in...

  6. Evaluation and Selection of Common Bean (Phaseolus Vulgaris L.) Genotypes for Root Traits Associated with Phosphorus (P) Acquisition Efficiency and the Use of 32P Isotope in Studies on P Uptake by Root Hairs

    Low phosphorus (P) availability is one of the main edaphic constraints limiting crop production and productivity in most of the tropical agro-ecosystems. Several root traits are known to be associated with P acquisition efficiency in low P soils. These root traits include root hairs. Computer modeling, laboratory and field studies show the depletion of 32P-phosphate around roots and that the depletion zone is influenced by the length and density of root hairs. We conducted a study involving a series of experiments with the objective of evaluating the variability of root traits associated with P uptake efficiency among common bean (Phaseolus vulgaris L.) genotypes, and to understand the mechanisms of long root hairs leading to the increase in P uptake in common bean. The study included (a) the screening of common bean genotypes in the laboratory and in the field for root traits, and (b) the use of radioactive phosphorus (32P) in the experiments conducted in the greenhouse. For laboratory screening, seedlings were germinated in paper rolls in a growth media for 3 days before evaluation for basal root whorl number (BRWN), basal root number (BRN), basal root growth angle (BRGA) and root hair length (RHL). Common bean genotypes were planted in the field with low P for 45 days after planting (DAP) before evaluation. For the 32P study four contrasting genotypes for root hairs were grown for 28 DAP in the greenhouse using 15-20 liter pots filled with a mixture of sand and vermiculate as the growth media. The radioactive P was incorporated in the growth medium in the form of alumina-P fertilizer. Normal phosphorus (non-radioactive 31P) was included in the nutrient solution in the form of calcium phosphate, Ca3(PO4)2, and supplied through irrigation. Screened genotypes exhibited different root traits associated with P uptake efficiency, and that a given genotype can have one or more root traits responsible for it P uptake efficiency. Data analysis of radioactivity present in

  7. Fission Fragments Discriminator

    Nuclear fission reaction between Uranium-235 nucleus and thermal neutron caused the high energy fission fragments with uncertainly direction. The particle direction discrimination was determined. The 2.5 x 3.0 mm2 polyethylene gratings with 1-6 mm thickness were used. The grating was placed between uranium screen that fabricated from ammonium-diurinate compound and polycarbonate nuclear track film recorder irradiated by neutron from Thai Research Reactor (TRR-1/M1) facility. The nuclear track density was inversely with grating thickness. It's only fission fragments normal to uranium screen pass through film recorder when grating thickness was 4-6 mm

  8. Discrimination in Grading

    Hanna, Rema N.; Linden, Leigh L.

    2012-01-01

    We report the results of an experiment that was designed to test for discrimination in grading in India. We recruited teachers to grade exams. We randomly assigned child "characteristics" (age, gender, and caste) to the cover sheets of the exams to ensure that there is no relationship between these observed characteristics and the exam quality. We find that teachers give exams that are assigned to be lower caste scores that are about 0.03 to 0.08 standard deviations lower than those that are ...

  9. Evaluation of correction method for mass discrimination effect in multiple collector inductively coupled plasma mass spectrometry

    This paper describes advances in isotopic measurements that have been made with an inductively coupled plasma source magnetic sector multiple collector mass spectrometer (MC-ICP-MS) and presents results of new experiments aimed at further evaluating the instrumental capability as well as the correction technique for the mass discrimination effects. The ability to correct for the mass discrimination effect using a second element of similar mass and very high sensitivity for elements that are otherwise difficult to ionize gives this instrument major advantages over other conventional techniques for isotopic measurements. The isotopic data obtained by MC-ICP-MS clearly demonstrate potential as a new technique to produce precise and reproducible isotopic data for the elements that are difficult to measure by thermal ionization mass spectrometry (TIMS). (author)

  10. Deconstructing nitrate isotope dynamics in aquifers

    Granger, J.

    2012-12-01

    The natural abundance N and O stable isotope ratios of nitrate provide an invaluable tool to differentiate N sources to the environment, track their dispersal, and monitor their attenuation by biological transformations. The interpretation of patterns in isotope abundances relies on knowledge of the isotope ratios of the source end-members, as well as on constraints on the isotope discrimination imposed on nitrate by respective biological processes. Emergent observations from mono-culture experiments of denitrifying bacteria reveal nitrate fractionation trends that appear at odds with trends ascribed to denitrification in soils and aquifers. This discrepancy raises the possibility that additional biological N transformations may be acting in tandem with denitrification. Here, the N and O isotope enrichments associated with nitrate removal by denitrification in aquifers are posited to bear evidence of coincident biological nitrate production - from nitrification and/or from anammox. Simulations are presented from a simple time-dependent one-box model of a groundwater mass ageing that is subject to net nitrate loss by denitrification with coincident nitrate production by nitrification or anammox. Within boundary conditions characteristic of freshwater aquifers, the apparent slope of the parallel enrichments in nitrate N and O isotopes associated with net N loss to denitrification can vary in proportion to the nitrate added simultaneous by oxidative processes. Pertinent observations from nitrate plumes in suboxic to anoxic aquifers are examined to validate this premise. In this perspective, nitrate isotope distributions suggest that we may be missing important N fluxes inherent to most aquifers.

  11. Women Status and their Discrimination

    PEŠKOVÁ, Pavlína

    2008-01-01

    My work deal with women status and their discrimination. Chapter one contains women status in different historical periods and development of their status to bigger equal with men. There is also written about present feminist trends. Chapter two is about women discrimination. There is about women´ job discrimination, job segregation according to gender and inequality in payment. There is also written about women status at home and unequal duties at home among family mates. Chapter three is ab...

  12. Unambiguous discrimination among oracle operators

    Chefles, Anthony; Kitagawa, Akira; Takeoka, Masahiro; Sasaki, Masahide; Twamley, Jason

    2007-01-01

    We address the problem of unambiguous discrimination among oracle operators. The general theory of unambiguous discrimination among unitary operators is extended with this application in mind. We prove that entanglement with an ancilla cannot assist any discrimination strategy for commuting unitary operators. We also obtain a simple, practical test for the unambiguous distinguishability of an arbitrary set of unitary operators on a given system. Using this result, we prove that the unambiguou...

  13. When Is Price Discrimination Profitable?

    Eric T. Anderson; James D. Dana

    2009-01-01

    We analyze a model of a quality-constrained monopolist's product line decision that encompasses a variety of important examples of second-degree price discrimination, including intertemporal price discrimination, coupons, advance purchase discounts, versioning of information goods, and damaged goods. We derive necessary and sufficient conditions for price discrimination to be profitable that generalize existing results in the literature. Specifically, we show that when a continuum of product ...

  14. Asymmetry in the discrimination of quantity by rats: The role of the intertrial interval.

    Inman, R A; Honey, R C; Eccles, G L; Pearce, J M

    2016-03-01

    In three experiments, rats were trained to discriminate between 20 and five (Exps. 1 and 2), or between 40 and five (Exp. 3), black squares. The squares were randomly distributed in the center of a white background and displayed on a computer screen. For one group, the patterns containing the higher quantity of squares signaled the delivery of sucrose (+), whilst patterns with the lower quantity of squares did not (-). For the second group, sucrose was signaled by the lower, but not by the higher, quantity of squares. In Experiment 1, the intertrial interval (ITI) was a white screen, and the 20+/5- discrimination was acquired more readily than the 5+/20- discrimination. For Experiment 2, the ITI was made up of 80 black squares on a white background. In this instance, the 5+/20- discrimination was acquired more successfully than the 20+/5- discrimination. In Experiment 3, two groups were trained with a 40+/5- discrimination, and two with a 5+/40- discrimination. For one group from each of these pairs, the training trials were separated by a white ITI, and the 40+/5- discrimination was acquired more readily than the 5+/40- discrimination. For the remaining two groups, the training trials were not separated by an ITI, and the two groups acquired the task at approximately the same rate. The results indicate that the cues present during the ITI play a role in the asymmetrical acquisition of magnitude discriminations based on quantity. PMID:26205179

  15. Robotization in Seismic Acquisition

    Blacquière, G.; Berkhout, A.J.

    2013-01-01

    The amount of sources and detectors in the seismic method follows "Moore’s Law of seismic data acquisition", i.e., it increases approximately by a factor of 10 every 10 years. Therefore automation is unavoidable, leading to robotization of seismic data acquisition. Recently, we introduced a new sour

  16. Firm Acquisitions Strategy

    Conf.univ.dr.ec. Adrian SIMON,

    2010-01-01

    We analyze the intents of acquiring firms and target in the firms in the case of thirty recent M$A deals involving at least one firm. The findings indicate that horizontal acquisitions help retain or gain market leadership. Market entry may be a dominant motive for MNCs acquiring domestic firms, and MNCs may offer higher premiums than domestic acquirers for the acquisition

  17. Acquisition of teleological descriptions

    Franke, David W.

    1992-03-01

    Teleology descriptions capture the purpose of an entity, mechanism, or activity with which they are associated. These descriptions can be used in explanation, diagnosis, and design reuse. We describe a technique for acquiring teleological descriptions expressed in the teleology language TeD. Acquisition occurs during design by observing design modifications and design verification. We demonstrate the acquisition technique in an electronic circuit design.

  18. Racial discrimination & health: pathways & evidence.

    Ahmed, Ameena T; Mohammed, Selina A; Williams, David R

    2007-10-01

    This review provides an overview of the existing empirical research of the multiple ways by which discrimination can affect health. Institutional mechanisms of discrimination such as restricting marginalized groups to live in undesirable residential areas can have deleterious health consequences by limiting socio-economic status (SES) and creating health-damaging conditions in residential environments. Discrimination can also adversely affect health through restricting access to desirable services such as medical care and creating elevated exposure to traditional stressors such as unemployment and financial strain. Central to racism is an ideology of inferiority that can adversely affect non-dominant groups because some members of marginalized populations will accept as true the dominant society's ideology of their group's inferiority. Limited empirical research indicates that internalized racism is inversely related to health. In addition, the existence of these negative stereotypes can lead dominant group members to consciously and unconsciously discriminate against the stigmatized. An overview of the growing body of research examining the ways in which psychosocial stress generated by subjective experiences of discrimination can affect health is also provided. We review the evidence from the United States and other societies that suggest that the subjective experience of discrimination can adversely affect health and health enhancing behaviours. Advancing our understanding of the relationship between discrimination and health requires improved assessment of the phenomenon of discrimination and increased attention to identifying the psychosocial and biological pathways that may link exposure to discrimination to health status. PMID:18032807

  19. Large Number Discrimination by Mosquitofish

    Agrillo, Christian; Piffer, Laura; Bisazza, Angelo

    2010-01-01

    Background Recent studies have demonstrated that fish display rudimentary numerical abilities similar to those observed in mammals and birds. The mechanisms underlying the discrimination of small quantities (

  20. Data acquisition system

    The topic of this paper deals with a multi parametric acquisition system developed around a four input Analog to Digital Converter working in CAMAC Standard. The acquisition software is built in MS Visual C++ on a standard PC with a USB interface. It has a visual interface which permits Start/Stop of the acquisition, setting the type of acquisition (True/Live time), the time and various menus for primary data acquisition. The spectrum is dynamically visualized with a moving cursor indicating the content and position. The microcontroller PIC16C765 is used for data transfer from ADC to PC; The microcontroller and the software create an embedded system which emulates the CAMAC protocol programming, the 4 input ADC for operating modes ('zero suppression', 'addressed' and 'sequential') and handling the data transfers from ADC to its internal memory. From its memory the data is transferred into the PC by the USB interface. The work is in progress. (authors)

  1. Weight discrimination and bullying.

    Puhl, Rebecca M; King, Kelly M

    2013-04-01

    Despite significant attention to the medical impacts of obesity, often ignored are the negative outcomes that obese children and adults experience as a result of stigma, bias, and discrimination. Obese individuals are frequently stigmatized because of their weight in many domains of daily life. Research spanning several decades has documented consistent weight bias and stigmatization in employment, health care, schools, the media, and interpersonal relationships. For overweight and obese youth, weight stigmatization translates into pervasive victimization, teasing, and bullying. Multiple adverse outcomes are associated with exposure to weight stigmatization, including depression, anxiety, low self-esteem, body dissatisfaction, suicidal ideation, poor academic performance, lower physical activity, maladaptive eating behaviors, and avoidance of health care. This review summarizes the nature and extent of weight stigmatization against overweight and obese individuals, as well as the resulting consequences that these experiences create for social, psychological, and physical health for children and adults who are targeted. PMID:23731874

  2. Gaussian discriminating strength

    Rigovacca, L.; Farace, A.; De Pasquale, A.; Giovannetti, V.

    2015-10-01

    We present a quantifier of nonclassical correlations for bipartite, multimode Gaussian states. It is derived from the Discriminating Strength measure, introduced for finite dimensional systems in Farace et al., [New J. Phys. 16, 073010 (2014), 10.1088/1367-2630/16/7/073010]. As the latter the new measure exploits the quantum Chernoff bound to gauge the susceptibility of the composite system with respect to local perturbations induced by unitary gates extracted from a suitable set of allowed transformations (the latter being identified by posing some general requirements). Closed expressions are provided for the case of two-mode Gaussian states obtained by squeezing or by linearly mixing via a beam splitter a factorized two-mode thermal state. For these density matrices, we study how nonclassical correlations are related with the entanglement present in the system and with its total photon number.

  3. Introduction to multivariate discrimination

    Kégl, Balázs

    2013-07-01

    Multivariate discrimination or classification is one of the best-studied problem in machine learning, with a plethora of well-tested and well-performing algorithms. There are also several good general textbooks [1-9] on the subject written to an average engineering, computer science, or statistics graduate student; most of them are also accessible for an average physics student with some background on computer science and statistics. Hence, instead of writing a generic introduction, we concentrate here on relating the subject to a practitioner experimental physicist. After a short introduction on the basic setup (Section 1) we delve into the practical issues of complexity regularization, model selection, and hyperparameter optimization (Section 2), since it is this step that makes high-complexity non-parametric fitting so different from low-dimensional parametric fitting. To emphasize that this issue is not restricted to classification, we illustrate the concept on a low-dimensional but non-parametric regression example (Section 2.1). Section 3 describes the common algorithmic-statistical formal framework that unifies the main families of multivariate classification algorithms. We explain here the large-margin principle that partly explains why these algorithms work. Section 4 is devoted to the description of the three main (families of) classification algorithms, neural networks, the support vector machine, and AdaBoost. We do not go into the algorithmic details; the goal is to give an overview on the form of the functions these methods learn and on the objective functions they optimize. Besides their technical description, we also make an attempt to put these algorithm into a socio-historical context. We then briefly describe some rather heterogeneous applications to illustrate the pattern recognition pipeline and to show how widespread the use of these methods is (Section 5). We conclude the chapter with three essentially open research problems that are either

  4. Introduction to multivariate discrimination

    Kégl Balázs

    2013-07-01

    Full Text Available Multivariate discrimination or classification is one of the best-studied problem in machine learning, with a plethora of well-tested and well-performing algorithms. There are also several good general textbooks [1–9] on the subject written to an average engineering, computer science, or statistics graduate student; most of them are also accessible for an average physics student with some background on computer science and statistics. Hence, instead of writing a generic introduction, we concentrate here on relating the subject to a practitioner experimental physicist. After a short introduction on the basic setup (Section 1 we delve into the practical issues of complexity regularization, model selection, and hyperparameter optimization (Section 2, since it is this step that makes high-complexity non-parametric fitting so different from low-dimensional parametric fitting. To emphasize that this issue is not restricted to classification, we illustrate the concept on a low-dimensional but non-parametric regression example (Section 2.1. Section 3 describes the common algorithmic-statistical formal framework that unifies the main families of multivariate classification algorithms. We explain here the large-margin principle that partly explains why these algorithms work. Section 4 is devoted to the description of the three main (families of classification algorithms, neural networks, the support vector machine, and AdaBoost. We do not go into the algorithmic details; the goal is to give an overview on the form of the functions these methods learn and on the objective functions they optimize. Besides their technical description, we also make an attempt to put these algorithm into a socio-historical context. We then briefly describe some rather heterogeneous applications to illustrate the pattern recognition pipeline and to show how widespread the use of these methods is (Section 5. We conclude the chapter with three essentially open research problems

  5. Introduction to multivariate discrimination

    Multivariate discrimination or classification is one of the best-studied problem in machine learning, with a plethora of well-tested and well-performing algorithms. There are also several good general textbooks [1-9] on the subject written to an average engineering, computer science, or statistics graduate student; most of them are also accessible for an average physics student with some background on computer science and statistics. Hence, instead of writing a generic introduction, we concentrate here on relating the subject to a practitioner experimental physicist. After a short introduction on the basic setup (Section 1) we delve into the practical issues of complexity regularization, model selection, and hyper-parameter optimization (Section 2), since it is this step that makes high-complexity non-parametric fitting so different from low-dimensional parametric fitting. To emphasize that this issue is not restricted to classification, we illustrate the concept on a low-dimensional but non-parametric regression example (Section 2.1). Section 3 describes the common algorithmic-statistical formal framework that unifies the main families of multivariate classification algorithms. We explain here the large-margin principle that partly explains why these algorithms work. Section 4 is devoted to the description of the three main (families of) classification algorithms, neural networks, the support vector machine, and AdaBoost. We do not go into the algorithmic details; the goal is to give an overview on the form of the functions these methods learn and on the objective functions they optimize. Besides their technical description, we also make an attempt to put these algorithm into a socio-historical context. We then briefly describe some rather heterogeneous applications to illustrate the pattern recognition pipeline and to show how widespread the use of these methods is (Section 5). We conclude the chapter with three essentially open research problems that are either

  6. Perceived weight discrimination and obesity.

    Angelina R Sutin

    Full Text Available Weight discrimination is prevalent in American society. Although associated consistently with psychological and economic outcomes, less is known about whether weight discrimination is associated with longitudinal changes in obesity. The objectives of this research are (1 to test whether weight discrimination is associated with risk of becoming obese (Body Mass Index≥30; BMI by follow-up among those not obese at baseline, and (2 to test whether weight discrimination is associated with risk of remaining obese at follow-up among those already obese at baseline. Participants were drawn from the Health and Retirement Study, a nationally representative longitudinal survey of community-dwelling US residents. A total of 6,157 participants (58.6% female completed the discrimination measure and had weight and height available from the 2006 and 2010 assessments. Participants who experienced weight discrimination were approximately 2.5 times more likely to become obese by follow-up (OR = 2.54, 95% CI = 1.58-4.08 and participants who were obese at baseline were three times more likely to remain obese at follow up (OR = 3.20, 95% CI = 2.06-4.97 than those who had not experienced such discrimination. These effects held when controlling for demographic factors (age, sex, ethnicity, education and when baseline BMI was included as a covariate. These effects were also specific to weight discrimination; other forms of discrimination (e.g., sex, race were unrelated to risk of obesity at follow-up. The present research demonstrates that, in addition to poorer mental health outcomes, weight discrimination has implications for obesity. Rather than motivating individuals to lose weight, weight discrimination increases risk for obesity.

  7. Racial/Ethnic Workplace Discrimination

    Chavez, Laura J.; Ornelas, India J.; Lyles, Courtney R.; Williams, Emily C.

    2014-01-01

    Background Experiences of discrimination are associated with tobacco and alcohol use, and work is a common setting where individuals experience racial/ethnic discrimination. Few studies have evaluated the association between workplace discrimination and these behaviors, and none have described associations across race/ethnicity. Purpose To examine the association between workplace discrimination and tobacco and alcohol use in a large, multistate sample of U.S. adult respondents to the Behavioral Risk Factor Surveillance System survey Reactions to Race Module (2004–2010). Methods Multivariable logistic regression analyses evaluated cross-sectional associations between self-reported workplace discrimination and tobacco (current and daily smoking) and alcohol use (any and heavy use, and binge drinking) among all participants and stratified by race/ethnicity, adjusting for relevant covariates. Data were analyzed in 2013. Results Among respondents, 70,080 completed the workplace discrimination measure. Discrimination was more common among black non-Hispanic (21%), Hispanic (12%), and other race respondents (11%) than white non-Hispanics (4%) (p<0.001). In the total sample, discrimination was associated with current smoking (risk ratio [RR]=1.32, 95% CI=1.19, 1.47), daily smoking (RR=1.41, 95% CI=1.24, 1.61), and heavy drinking (RR=1.11, 95% CI=1.01, 1.22), but not binge or any drinking. Among Hispanics, workplace discrimination was associated with increased heavy and binge drinking, but not any alcohol use or smoking. Workplace discrimination among black non-Hispanics and white Non-Hispanics was associated with increased current and daily smoking, but not alcohol outcomes. Conclusions Workplace discrimination is common, associated with smoking and alcohol use, and merits further policy attention given the impact of these behaviors on morbidity and mortality. PMID:25441232

  8. Calculation of uncertainties of U-Pb isotope data

    Ludwig, K. R.

    1980-01-01

    Equations are derived for the estimation of errors and error correlations for various types of U-Pb isotope data, taking into account ion-beam instabilities, run-to-run variability in mass-discrimination, uncertainties in Pb and U concentrations, and uncertainties in initial-Pb and blank-Pb amount and isotopic composition. Equations are also given for the calculation of concordia intercept errors. ?? 1980.

  9. Perceived Discrimination in LGBTIQ Discourse: A Typology of Verbal Discrimination

    Sol Rojas Lizana

    2014-08-01

    Full Text Available New within the field of Discourse Analysis, Perceived Discrimination (PD is the study of discourse that focuses on the perspective of the victims of discrimination. This article explores the experiences of verbal discrimination as reported by eighteen LGBTIQ participants during semi-structured, co-constructed interviews. Data were classified in order to develop a taxonomy of discrimination based on Mellor’s (2003, 2004. This taxonomy foregrounds two types of discrimination: verbal and behavioural. In this paper, I exemplify the forms of verbal discrimination encountered and offer an analysis of the discourse used in the construction of the experiences and of the effects reported. The results show that verbal discrimination is an overt phenomenon and that participants are stressed by the ever present possibility of facing it. Verbal discrimination is mainly triggered by a perceived transgression to the normalised standards of people’s behaviour, movements and look in a heterosexist society. It presents three subtypes: name calling, abuse and remarks. These subtypes are described through the analysis of keywords, effects and expressions (such as faggot, gay, dyke, queer, the pronoun ‘it’, religious comments and other remarks. The type of discrimination used was associated with the level of acquaintance perpetrators have with the experiencers; that is, name calling was used by people unknown to the victims while abuse and remarks by acquaintances and family members. Participants resorted to several discursive strategies to convey their intentions. They used mitigation strategies when wanting to minimize the experience, hedging and repetition were used for emphasis, and to convey urgency and pervasiveness. Metaphorical expressions related to internal or external injuries were also used to express the powerful effect of verbal discrimination on people.

  10. Standardized Discriminant Coefficients: A Rejoinder.

    Mueller, Ralph O.; Cozad, James B.

    1993-01-01

    Although comments of D.J. Nordlund and R. Nagel are welcomed, their arguments are not sufficient to accept the recommendation of using total variance estimates to standardize canonical discriminant function coefficients. If standardized coefficients are used to help interpret a discriminant analysis, pooled within-group variance estimates should…