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Sample records for tracer transit predicts

  1. Diuretic renography in hydronephrosis: renal tissue tracer transit predicts functional course and thereby need for surgery

    Energy Technology Data Exchange (ETDEWEB)

    Schlotmann, Andreas [University Hospital Freiburg, Department of Nuclear Medicine and Department of Radiation Oncology, Freiburg (Germany); Clorius, John H. [German Cancer Research Center, Heidelberg (Germany); Clorius, Sandra N. [University Hospital Basel, Department of Internal Medicine, Basel (Switzerland)

    2009-10-15

    The recognition of those hydronephrotic kidneys which require therapy to preserve renal function remains difficult. We retrospectively compared the 'tissue tracer transit' (TTT) of {sup 99m}Tc-mercaptoacetyltriglycine ({sup 99m}Tc-MAG{sub 3}) with 'response to furosemide stimulation' (RFS) and with 'single kidney function < 40%' (SKF < 40%) to predict functional course and thereby need for surgery. Fifty patients with suspected unilateral obstruction and normal contralateral kidney had 115 paired (baseline/follow-up) {sup 99m}Tc-MAG{sub 3} scintirenographies. Three predictions of the functional development were derived from each baseline examination: the first based on TTT (visually assessed), the second on RFS and the third on SKF < 40%. Each prediction also considered whether the patient had surgery. Possible predictions were 'better', 'worse' or 'stable' function. A comparison of SKF at baseline and follow-up verified the predictions. The frequency of correct predictions for functional improvement following surgery was 8 of 10 kidneys with delayed TTT, 9 of 22 kidneys with obstructive RFS and 9 of 21 kidneys with SKF < 40%; for functional deterioration without surgery it was 2 of 3 kidneys with delayed TTT, 3 of 20 kidneys with obstructive RFS and 3 of 23 kidneys with SKF < 40%. Without surgery 67 of 70 kidneys with timely TTT maintained function. Without surgery 0 of 9 kidneys with timely TTT but obstructive RFS and only 1 of 16 kidneys with timely TTT but SKF < 40% lost function. Delayed TTT appears to identify the need for therapy to preserve function of hydronephrotic kidneys, while timely TTT may exclude risk even in the presence of an obstructive RFS or SKF < 40%. (orig.)

  2. Diuretic renography in hydronephrosis: renal tissue tracer transit predicts functional course and thereby need for surgery.

    Science.gov (United States)

    Schlotmann, Andreas; Clorius, John H; Clorius, Sandra N

    2009-10-01

    The recognition of those hydronephrotic kidneys which require therapy to preserve renal function remains difficult. We retrospectively compared the 'tissue tracer transit' (TTT) of (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG(3)) with 'response to furosemide stimulation' (RFS) and with 'single kidney function timely TTT maintained function. Without surgery 0 of 9 kidneys with timely TTT but obstructive RFS and only 1 of 16 kidneys with timely TTT but SKF timely TTT may exclude risk even in the presence of an obstructive RFS or SKF < 40%.

  3. Discrete fracture modelling for the Stripa tracer validation experiment predictions

    International Nuclear Information System (INIS)

    Dershowitz, W.; Wallmann, P.

    1992-02-01

    Groundwater flow and transport through three-dimensional networks of discrete fractures was modeled to predict the recovery of tracer from tracer injection experiments conducted during phase 3 of the Stripa site characterization and validation protect. Predictions were made on the basis of an updated version of the site scale discrete fracture conceptual model used for flow predictions and preliminary transport modelling. In this model, individual fractures were treated as stochastic features described by probability distributions of geometric and hydrologic properties. Fractures were divided into three populations: Fractures in fracture zones near the drift, non-fracture zone fractures within 31 m of the drift, and fractures in fracture zones over 31 meters from the drift axis. Fractures outside fracture zones are not modelled beyond 31 meters from the drift axis. Transport predictions were produced using the FracMan discrete fracture modelling package for each of five tracer experiments. Output was produced in the seven formats specified by the Stripa task force on fracture flow modelling. (au)

  4. Flow-rate measurement using radioactive tracers and transit time method

    International Nuclear Information System (INIS)

    Turtiainen, Heikki

    1986-08-01

    The transit time method is a flow measurement method based on tracer techniques. Measurement is done by injecting to the flow a pulse of tracer and measuring its transit time between two detection positions. From the transit time the mean flow velosity and - using the pipe cross section area - the volume flow rate can be calculated. When a radioisotope tracer is used the measurement can be done from outside the pipe and without disturbing the process (excluding the tracer injection). The use of the transit time method has been limited because of difficulties associated with handling and availability of radioactive tracers and lack of equipment suitable for routine use in industrial environments. The purpose of this study was to find out if these difficulties may be overcome by using a portable isotope generator as a tracer source and automating the measurement. In the study a test rig and measuring equipment based on the use of a ''1''3''7Cs/''1''3''7''''mBa isotope generator were constructed. They were used to study the accuracy and error sources of the method and to compare different algorithms to calculate the transit time. The usability of the method and the equipment in industrial environments were studied by carrying out over 20 flow measurements in paper and pulp mills. On the basis of the results of the study, a project for constructing a compact radiatracer flowmeter for industrial use has been started. The application range of this kind of meter is very large. The most obvious applications are in situ calibration of flowmeters, material and energy balance studies, process equipment analyses (e.g. pump efficiency analyses). At the moment tracer techniques are the only methods applicable to these measurements on-line and with sufficient accuracy

  5. Aggregation in environmental systems - Part 1: Seasonal tracer cycles quantify young water fractions, but not mean transit times, in spatially heterogeneous catchments

    Science.gov (United States)

    Kirchner, J. W.

    2016-01-01

    Environmental heterogeneity is ubiquitous, but environmental systems are often analyzed as if they were homogeneous instead, resulting in aggregation errors that are rarely explored and almost never quantified. Here I use simple benchmark tests to explore this general problem in one specific context: the use of seasonal cycles in chemical or isotopic tracers (such as Cl-, δ18O, or δ2H) to estimate timescales of storage in catchments. Timescales of catchment storage are typically quantified by the mean transit time, meaning the average time that elapses between parcels of water entering as precipitation and leaving again as streamflow. Longer mean transit times imply greater damping of seasonal tracer cycles. Thus, the amplitudes of tracer cycles in precipitation and streamflow are commonly used to calculate catchment mean transit times. Here I show that these calculations will typically be wrong by several hundred percent, when applied to catchments with realistic degrees of spatial heterogeneity. This aggregation bias arises from the strong nonlinearity in the relationship between tracer cycle amplitude and mean travel time. I propose an alternative storage metric, the young water fraction in streamflow, defined as the fraction of runoff with transit times of less than roughly 0.2 years. I show that this young water fraction (not to be confused with event-based "new water" in hydrograph separations) is accurately predicted by seasonal tracer cycles within a precision of a few percent, across the entire range of mean transit times from almost zero to almost infinity. Importantly, this relationship is also virtually free from aggregation error. That is, seasonal tracer cycles also accurately predict the young water fraction in runoff from highly heterogeneous mixtures of subcatchments with strongly contrasting transit-time distributions. Thus, although tracer cycle amplitudes yield biased and unreliable estimates of catchment mean travel times in heterogeneous

  6. Predictions of PuO2 and tracer compound release from ISV melts

    International Nuclear Information System (INIS)

    Cronenberg, A.W.; Callow, R.A.

    1992-04-01

    Two field tests were conducted at the Idaho National Engineering Laboratory (INEL) to assess in situ vitrification (ISV) suitability for long-term stabilization of buried radioactive waste. Both tests contained rare-earth oxide tracers (DY 2 O 3 , Yb 2 O 3 , and Tb 4 O 7 ) to simulate the presence of plutonium in the form of PuO 2 . In the first test, Intermediate Field Test (IFT)-l, approximately 4-% release of tracer material occurred during soil melting and associated off-gassing, while essentially nil release was observed for the second experiment (IFT-2) for which off-gassing was much reduced. This report presents an evaluation of the IFT test data in terms of governing release processes. Prediction of tracer release during ISV melting centered on an assessment of three potential transport mechanisms, (a) tracer diffusion through stagnant pool, (b) tracer transport by convective currents, and (c) tracer carry-off by escaping gas bubbles. Analysis indicates that tracer release by escaping gas is the dominant release mechanism, which is consistent with video records of gas bubble escape from the ISV melt surface. Quantitative mass transport predictions were also made for the IFT-I test conditions, indicating similarity between the 4-% release data and calculational results at viscosities of ∼ poise and tracer diffusivities of ∼10 -6 CM 2 /s. Since PuO 2 has similar chemical and transport (diffusivity) properties as the rare-earth tracers used in the rare earth tracers used in the IFT experiments, release of PuO 2 is predicted for similar off-gassing conditions. Reduced off-gassing during ISV would thus be expected to improve the overall retention of heavy-oxides within vitrified soil

  7. The Use of Stable Isotope Tracers to Quantify the Transit Time Distribution of Water

    Science.gov (United States)

    Gray, T. M.; Troch, P. A. A.

    2016-12-01

    Water pollution is an important societal problem because it can have harmful effects on human and ecological health. In order to improve water quality, scientists must develop land management methods that can avoid or mitigate environmental pollution. State of the art tools to develop such methods are flow and transport models that trace water and other solutes through the landscape. These models deliver important information that can lead to remediation efforts, and improve the quality of water for humans, plants, and animals. However, these models may be difficult to apply since many details about the catchment may not be available. Instead, a lumped approach is often used to find the water transit time using stable isotope tracers such as 18O and 2H that are naturally applied by precipitation to a catchment. The transit time distribution of water is an important indicator for the amount of solutes soil water and groundwater can contain, and thus a predictor of water quality. We conducted a 2-week long experiment using a tilted weighing lysimeter at Biosphere 2 to observe the breakthrough curves of deuterium and specific artificial DNA particles. We show that hydrological parameters can be computed in order to provide an estimate for the transit time distribution of deuterium. The convolution integral is then used to determine the distribution of the water transit time in the system. Unfortunately, stable isotopes such as deuterium make it difficult to pinpoint a specific flowpath since they naturally occur in the environment. Recent studies have shown that DNA tracers are able to trace water through the landscape. We found that DNA has a similar breakthrough curve happening at similar timescales as the deuterium. Therefore, DNA tracers may be able to identify sources of nonpoint source pollution in the future.

  8. Predictive value of tracer studies for 131I treatment in hyperthyroid cats

    International Nuclear Information System (INIS)

    Broome, M.R.; Turrel, J.M.; Hays, M.T.

    1988-01-01

    In 76 cats with hyperthyroidism, peak thyroidal radioiodine ( 131 I) uptakes and effective half-lives were determined after administration of tracer and therapeutic activities of 131 I. In 6 additional hyperthyroid cats, only peak thyroidal uptakes after administration of tracer and therapeutic activities of 131 I were determined. Good correlation was found between peak thyroidal uptakes of tracer and therapeutic 131 I; however, only fair correlation was observed between effective half-lives. In 79% of the cats, the effective half-life for therapeutic 131 I was longer than that for tracer 131 I. After administration of therapeutic activity of 131 I, monoexponential and biphasic decay curves were observed in 51 and 16 cats, respectively. Using therapeutic kinetic data, radiation doses to the thyroid gland were calculated retrospectively on the basis of 2 methods for determining the activity of 131 I administered: (1) actual administration of tracer-compensated activity and (2) hypothetic administration of uniform activity (3 mCi). Because of the good predictive ability of tracer kinetic data for the therapeutic kinetic data, the tracer-compensated radiation doses came significantly (P = 0.008) closer to the therapeutic goal than did the uniform-activity doses. In addition, the use of tracer kinetic information reduced the extent of the tendency for consistently high uniform-activity doses. A manual method for acquiring tracer kinetic data was developed and was an acceptable alternative to computerized techniques. Adoption of this method gives individuals and institutions with limited finances the opportunity to characterize the iodine kinetics in cats before proceeding with administration of therapeutic activities of 131 I

  9. Stable isotopes of transition and post-transition metals as tracers in environmental studies

    Science.gov (United States)

    Bullen, Tomas D.; Baskaran, Mark

    2011-01-01

    The transition and post-transition metals, which include the elements in Groups 3–12 of the Periodic Table, have a broad range of geological and biological roles as well as industrial applications and thus are widespread in the environment. Interdisciplinary research over the past decade has resulted in a broad understanding of the isotope systematics of this important group of elements and revealed largely unexpected variability in isotope composition for natural materials. Significant kinetic and equilibrium isotope fractionation has been observed for redox sensitive metals such as iron, chromium, copper, molybdenum and mercury, and for metals that are not redox sensitive in nature such as cadmium and zinc. In the environmental sciences, the isotopes are increasingly being used to understand important issues such as tracing of metal contaminant sources and fates, unraveling metal redox cycles, deciphering metal nutrient pathways and cycles, and developing isotope biosignatures that can indicate the role of biological activity in ancient and modern planetary systems.

  10. Mental models accurately predict emotion transitions.

    Science.gov (United States)

    Thornton, Mark A; Tamir, Diana I

    2017-06-06

    Successful social interactions depend on people's ability to predict others' future actions and emotions. People possess many mechanisms for perceiving others' current emotional states, but how might they use this information to predict others' future states? We hypothesized that people might capitalize on an overlooked aspect of affective experience: current emotions predict future emotions. By attending to regularities in emotion transitions, perceivers might develop accurate mental models of others' emotional dynamics. People could then use these mental models of emotion transitions to predict others' future emotions from currently observable emotions. To test this hypothesis, studies 1-3 used data from three extant experience-sampling datasets to establish the actual rates of emotional transitions. We then collected three parallel datasets in which participants rated the transition likelihoods between the same set of emotions. Participants' ratings of emotion transitions predicted others' experienced transitional likelihoods with high accuracy. Study 4 demonstrated that four conceptual dimensions of mental state representation-valence, social impact, rationality, and human mind-inform participants' mental models. Study 5 used 2 million emotion reports on the Experience Project to replicate both of these findings: again people reported accurate models of emotion transitions, and these models were informed by the same four conceptual dimensions. Importantly, neither these conceptual dimensions nor holistic similarity could fully explain participants' accuracy, suggesting that their mental models contain accurate information about emotion dynamics above and beyond what might be predicted by static emotion knowledge alone.

  11. Mental models accurately predict emotion transitions

    Science.gov (United States)

    Thornton, Mark A.; Tamir, Diana I.

    2017-01-01

    Successful social interactions depend on people’s ability to predict others’ future actions and emotions. People possess many mechanisms for perceiving others’ current emotional states, but how might they use this information to predict others’ future states? We hypothesized that people might capitalize on an overlooked aspect of affective experience: current emotions predict future emotions. By attending to regularities in emotion transitions, perceivers might develop accurate mental models of others’ emotional dynamics. People could then use these mental models of emotion transitions to predict others’ future emotions from currently observable emotions. To test this hypothesis, studies 1–3 used data from three extant experience-sampling datasets to establish the actual rates of emotional transitions. We then collected three parallel datasets in which participants rated the transition likelihoods between the same set of emotions. Participants’ ratings of emotion transitions predicted others’ experienced transitional likelihoods with high accuracy. Study 4 demonstrated that four conceptual dimensions of mental state representation—valence, social impact, rationality, and human mind—inform participants’ mental models. Study 5 used 2 million emotion reports on the Experience Project to replicate both of these findings: again people reported accurate models of emotion transitions, and these models were informed by the same four conceptual dimensions. Importantly, neither these conceptual dimensions nor holistic similarity could fully explain participants’ accuracy, suggesting that their mental models contain accurate information about emotion dynamics above and beyond what might be predicted by static emotion knowledge alone. PMID:28533373

  12. Using predictive uncertainty analysis to optimise tracer test design and data acquisition

    Science.gov (United States)

    Wallis, Ilka; Moore, Catherine; Post, Vincent; Wolf, Leif; Martens, Evelien; Prommer, Henning

    2014-07-01

    Tracer injection tests are regularly-used tools to identify and characterise flow and transport mechanisms in aquifers. Examples of practical applications are manifold and include, among others, managed aquifer recharge schemes, aquifer thermal energy storage systems and, increasingly important, the disposal of produced water from oil and shale gas wells. The hydrogeological and geochemical data collected during the injection tests are often employed to assess the potential impacts of injection on receptors such as drinking water wells and regularly serve as a basis for the development of conceptual and numerical models that underpin the prediction of potential impacts. As all field tracer injection tests impose substantial logistical and financial efforts, it is crucial to develop a solid a-priori understanding of the value of the various monitoring data to select monitoring strategies which provide the greatest return on investment. In this study, we demonstrate the ability of linear predictive uncertainty analysis (i.e. “data worth analysis”) to quantify the usefulness of different tracer types (bromide, temperature, methane and chloride as examples) and head measurements in the context of a field-scale aquifer injection trial of coal seam gas (CSG) co-produced water. Data worth was evaluated in terms of tracer type, in terms of tracer test design (e.g., injection rate, duration of test and the applied measurement frequency) and monitoring disposition to increase the reliability of injection impact assessments. This was followed by an uncertainty targeted Pareto analysis, which allowed the interdependencies of cost and predictive reliability for alternative monitoring campaigns to be compared directly. For the evaluated injection test, the data worth analysis assessed bromide as superior to head data and all other tracers during early sampling times. However, with time, chloride became a more suitable tracer to constrain simulations of physical transport

  13. Predictions of tracer transport in interwell tracer tests at the C-Hole complex. Yucca Mountain site characterization project report milestone 4077

    International Nuclear Information System (INIS)

    Reimus, P.W.

    1996-09-01

    This report presents predictions of tracer transport in interwell tracer tests that are to be conducted at the C-Hole complex at the Nevada Test Site on behalf of the Yucca Mountain Site Characterization Project. The predictions are used to make specific recommendations about the manner in which the tracer test should be conducted to best satisfy the needs of the Project. The objective of he tracer tests is to study flow and species transport under saturated conditions in the fractured tuffs near Yucca Mountain, Nevada, the site of a potential high-level nuclear waste repository. The potential repository will be located in the unsaturated zone within Yucca Mountain. The saturated zone beneath and around the mountain represents the final barrier to transport to the accessible environment that radionuclides will encounter if they breach the engineered barriers within the repository and the barriers to flow and transport provided by the unsaturated zone. Background information on the C-Holes is provided in Section 1.1, and the planned tracer testing program is discussed in Section 1.2

  14. Comparison of oral iodine-131-cellulose and indium-111-DTPA as tracers for colon transit scintigraphy: Analysis by colon activity profiles

    International Nuclear Information System (INIS)

    Smart, R.C.; McLean, R.G.; Gaston-Parry, D.; Barbagallo, S.; Bruck, C.E.; King, D.W.; Lubowski, D.Z.; Talley, N.A.

    1991-01-01

    In 11 normal subjects and 11 patients with a clinical diagnosis of constipation, oral 131I-cellulose and 111In-DTPA were compared simultaneously as tracers for radionuclide colon transit scintigraphy. Visual assessment of the images revealed no differences between tracers. Quantitation was performed using total and segmental percent retention and the derived value of clearance half-time. In addition, profiles of the activity distribution along the length of the colon were generated and the mean position of the activity in the colon calculated. For all indices, the results were similar in both normal subjects and constipated patients when comparing tracers, although marked differences were present between normal subjects and constipated patients for each tracer. Indium-111-DTPA was easy to administer and dosimetry was more acceptable than for 131I-cellulose, especially in constipated patients. It is concluded that 111In-DTPA is the preferred tracer for oral colon transit scintigraphy

  15. Towards predictive models for transitionally rough surfaces

    Science.gov (United States)

    Abderrahaman-Elena, Nabil; Garcia-Mayoral, Ricardo

    2017-11-01

    We analyze and model the previously presented decomposition for flow variables in DNS of turbulence over transitionally rough surfaces. The flow is decomposed into two contributions: one produced by the overlying turbulence, which has no footprint of the surface texture, and one induced by the roughness, which is essentially the time-averaged flow around the surface obstacles, but modulated in amplitude by the first component. The roughness-induced component closely resembles the laminar steady flow around the roughness elements at the same non-dimensional roughness size. For small - yet transitionally rough - textures, the roughness-free component is essentially the same as over a smooth wall. Based on these findings, we propose predictive models for the onset of the transitionally rough regime. Project supported by the Engineering and Physical Sciences Research Council (EPSRC).

  16. In situ gaseous tracer diffusion experiments and predictive modeling at the Greater Confinement Disposal Test

    International Nuclear Information System (INIS)

    Olson, M.C.

    1985-07-01

    The Greater Confinement Disposal Test (GCDT) at the Nevada Test Site is a research project investigating the feasibility of augered shaft disposal of low-level radioactive waste considered unsuitable for shallow land burial. The GCDT contains environmentally mobile and high-specific-activity sources. Research is focused on providing a set of analytically derived hydrogeologic parameters and an empirical database for application in a multiphase, two-dimensional, transient, predictive performance model. Potential contaminant transport processes at the GCDT are identified and their level of significance is detailed. Nonisothermal gaseous diffusion through alluvial sediments is considered the primary waste migration process. Volatile organic tracers are released in the subsurface and their migration is monitored in situ to determine media effective diffusion coefficients, tortuosity, and sorption-corrected porosity terms. The theoretical basis for volatile tracer experiments is presented. Treatment of thermal and liquid flow components is discussed, as is the basis for eliminating several negligible transport processes. Interpretive techniques include correlation, power spectra, and least squares analysis, a graphical analytical solution, and inverse numerical modeling. Model design and application to the GCDT are discussed. GCDT structural, analytical, and computer facilities are detailed. The status of the current research program is reviewed, and temperature and soil moisture profiles are presented along with results of operational tests on the analytical system. 72 refs., 39 figs., 2 tabs

  17. Simplified Approach to Predicting Rough Surface Transition

    Science.gov (United States)

    Boyle, Robert J.; Stripf, Matthias

    2009-01-01

    Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consiste nt with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparison s are presented with published experimental data. Some of the data ar e for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach ta ken in this analysis is to treat the roughness in a statistical sense , consistent with what would be obtained from blades measured after e xposure to actual engine environments. An approach is given to determ ine the equivalent sand grain roughness from the statistics of the re gular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test co nditions. Additional comparisons are made with experimental heat tran sfer data, where the roughness geometries are both regular as well a s statistical. Using the developed analysis, heat transfer calculatio ns are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

  18. Ecological transition predictably associated with gene degeneration.

    Science.gov (United States)

    Wessinger, Carolyn A; Rausher, Mark D

    2015-02-01

    Gene degeneration or loss can significantly contribute to phenotypic diversification, but may generate genetic constraints on future evolutionary trajectories, potentially restricting phenotypic reversal. Such constraints may manifest as directional evolutionary trends when parallel phenotypic shifts consistently involve gene degeneration or loss. Here, we demonstrate that widespread parallel evolution in Penstemon from blue to red flowers predictably involves the functional inactivation and degeneration of the enzyme flavonoid 3',5'-hydroxylase (F3'5'H), an anthocyanin pathway enzyme required for the production of blue floral pigments. Other types of genetic mutations do not consistently accompany this phenotypic shift. This pattern may be driven by the relatively large mutational target size of degenerative mutations to this locus and the apparent lack of associated pleiotropic effects. The consistent degeneration of F3'5'H may provide a mechanistic explanation for the observed asymmetry in the direction of flower color evolution in Penstemon: Blue to red transitions are common, but reverse transitions have not been observed. Although phenotypic shifts in this system are likely driven by natural selection, internal constraints may generate predictable genetic outcomes and may restrict future evolutionary trajectories. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Estimation of transit times in a Karst Aquifer system using environmental tracers: Application on the Jeita Aquifer system-Lebanon.

    Science.gov (United States)

    Doummar, Joanna; Hamdan, Ahmad

    2016-04-01

    Estimating transit times is essential for the assessment of aquifer vulnerability to contaminants. Groundwater in karst aquifer is assumed to be relatively young due to fast preferential pathways; slow flow components are present in water stored in the fissured matrix. Furthermore, transit times are site specific as they depend on recharge rates, temperatures, elevation, and flow media; saturated and unsaturated zones. These differences create significant variation in the groundwater age in karst systems as the water sampled will be a mix of different water that has been transported through different flow pathways (fissured matrix and conduits). Several methods can be applied to estimate water transit time of an aquifer such as artificial tracers, which provide an estimate for fast flow velocities. In this study, groundwater residence times in the Jeita spring aquifer (Lebanon) were estimated using several environmental tracers such as Chlorofluorocarbons (CFCs), Sulfur Hexafluoride (SF6), Helium-Tritium (3H, 3H- 3He). Additional stable isotope and major ion analysis was performed to characterize water types. Groundwater samples were collected from six different wells in the Jeita catchment area (Jurassic Kesrouane aquifer) as well as from the spring and cave itself. The results are reproducible for the Tritium-Helium method, unlike for the CFC/SF6 methods that yielded poor results due to sampling problems. Tritium concentrations in all groundwater samples show nearly the same concentration (~2.73 TU) except for one sample with relatively lower tritium concentration (~2.26 TU). Ages ranging from 0.07 ± 0.07 years to 23.59 ± 0.00 years were obtained. The youngest age is attributed to the spring/ cave while the oldest ages were obtained in wells tapping the fissured matrix. Neon in these samples showed considerable variations and high delta Ne in some samples indicating high excess air. Four (4) samples showed extreme excess air (Delta-Ne is greater than 70 %) and

  20. Predicted fate of tritium residuum from groundwater tracer experiments in the Amargosa Desert, southern Nevada

    International Nuclear Information System (INIS)

    Brikowski, T.

    1993-07-01

    Analytic solutions are used in this study to evaluate potential groundwater transport of tritium used in goundwater tracer tests southwest of the Nevada Test Site. Possible transport from this site is of interest because initial radionuclide concentrations were high and the site is close to goundwater discharge points (12 km). Anecdotal evidence indicates that 90 percent of these tracers were removed by pumping at the completion of the tests; this study examines the probable transport of the tracers with and without the removal. Classical dispersive transport analytic solutions are used, treating the tracer test as a point slug injection. Input parameters for the solutions were measured at the site, and consideration of parameter uncertainty is incorporated in the results. With removal of the tracer, the maximum expected region with above-Safe Drinking Water Act (40 CFR 121) concentrations of tritium extends 5 km from the injection point, and does not reach any sites of public access. Detectable tritium from the tests is likely to have reached the Ash Meadows fault zone, but flow along the fault probably diluted the tracer to below detection limits before arrival at springs along the fault. Arrival at the springs would have occurred 20 to 25 years after the tests. Without removal of the tracer, the solutions indicate that tritium concentrations just above Safe Drinking Water Act standards would have reached the Ash Meadows fault zone. In this case, detectable tritium might have been found in Devil's Hole or Longstreet Spring, the nearest points of possible public exposure

  1. TRACER: an ‘eye-opener’ to the patient experience across the transition of care in an internal medicine resident program

    Directory of Open Access Journals (Sweden)

    Lauren B. Meade

    2015-04-01

    Full Text Available Background: A safe patient transition requires a complex set of physician skills within the interprofessional practice. Objective: To evaluate a rotation which applies self-reflection and workplace learning in a TRAnsition of CarE Rotation (TRACER for internal medicine (IM residents. TRACER is a 2-week required IM resident rotation where trainees join a ward team as a quality officer and follow patients into postacute care. Methods: In 2010, residents participated in semistructured, one-on-one interviews as part of ongoing program evaluation. They were asked what they had learned on TRACER, the year prior, and how they used those skills in their practice. Using transcripts, the authors reviewed and coded each transcript to develop themes. Results: Five themes emerged from a qualitative, grounded theory analysis: seeing things from the other side, the ‘ah ha’ moment of fragmented care, team collaboration including understanding nursing scope of practice in different settings, patient understanding, and passing the learning on. TRACER gives residents a moment to breathe and open their eyes to the interprofessional practice setting and the patient's experience of care in transition. Conclusions: Residents learn about transitions of care through self-reflection. This learning is sustained over time and is valued enough to teach to their junior colleagues.

  2. Analysis of tracer transit in rat brain after carotid artery and femoral vein administrations using linear system theory.

    Science.gov (United States)

    Rudin, M; Beckmann, N; Sauter, A

    1997-01-01

    Determination of tissue perfusion rates by MRI bolus tracking methods relies on the central volume principle which states that tissue blood flow is given by the tissue blood volume divided by the mean tracer transit time (MTT). Accurate determination of the MTT requires knowledge of the arterial input function which in MRI experiments is usually not known, especially when using small animals. The problem of unknown arterial input can be circumvented in animal experiments by directly injecting the contrast agent into a feeding artery of the tissue of interest. In the present article the passage of magnetite nanoparticles through the rat cerebral cortex is analyzed after injection into the internal carotid artery. The results are discussed in the framework of linear system theory using a one-compartment model for brain tissue and by using the well characterized gamma-variate function to describe the tissue concentration profile of the contrast agent. The results obtained from the intra-arterial tracer administration experiments are then compared with the commonly used intra-venous injection of the contrast agent in order to estimate the contribution of the peripheral circulation to the MTT values in the latter case. The experiments were analyzed using a two-compartment model and the gamma-variate function. As an application perfusion rates in normal and ischemic cerebral cortex of hypertensive rats were estimated in a model of focal cerebral ischemia. The results indicate that peripheral circulation has a significant influence on the MTT values and thus on the perfusion rates, which cannot be neglected.

  3. Improving Transit Predictions of Known Exoplanets with TERMS

    Directory of Open Access Journals (Sweden)

    Mahadevan S.

    2011-02-01

    Full Text Available Transiting planet discoveries have largely been restricted to the short-period or low-periastron distance regimes due to the bias inherent in the geometric transit probability. Through the refinement of planetary orbital parameters, and hence reducing the size of transit windows, long-period planets become feasible targets for photometric follow-up. Here we describe the TERMS project that is monitoring these host stars at predicted transit times.

  4. Flight Experiment Verification of Shuttle Boundary Layer Transition Prediction Tool

    Science.gov (United States)

    Berry, Scott A.; Berger, Karen T.; Horvath, Thomas J.; Wood, William A.

    2016-01-01

    Boundary layer transition at hypersonic conditions is critical to the design of future high-speed aircraft and spacecraft. Accurate methods to predict transition would directly impact the aerothermodynamic environments used to size a hypersonic vehicle's thermal protection system. A transition prediction tool, based on wind tunnel derived discrete roughness correlations, was developed and implemented for the Space Shuttle return-to-flight program. This tool was also used to design a boundary layer transition flight experiment in order to assess correlation uncertainties, particularly with regard to high Mach-number transition and tunnel-to-flight scaling. A review is provided of the results obtained from the flight experiment in order to evaluate the transition prediction tool implemented for the Shuttle program.

  5. Statistical Prediction of Laminar-turbulent Transition

    National Research Council Canada - National Science Library

    Rubinstein, Robert

    2000-01-01

    ... on representative stability theories including the resonant triad model and the parabolized stability equations. The first type of model can describe the effect of initial phase differences among disturbance modes on transition location...

  6. High-pressure phase transitions - Examples of classical predictability

    Science.gov (United States)

    Celebonovic, Vladan

    1992-09-01

    The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.

  7. Tumoral tracers

    International Nuclear Information System (INIS)

    Camargo, E.E.

    1979-01-01

    Direct tumor tracers are subdivided in the following categories:metabolite tracers, antitumoral tracers, radioactive proteins and cations. Use of 67 Ga-citrate as a clinically important tumoral tracer is emphasized and gallium-67 whole-body scintigraphy is discussed in detail. (M.A.) [pt

  8. An intermittency model for predicting roughness induced transition

    Science.gov (United States)

    Ge, Xuan; Durbin, Paul

    2014-11-01

    An extended model for roughness-induced transition is proposed based on an intermittency transport equation for RANS modeling formulated in local variables. To predict roughness effects in the fully turbulent boundary layer, published boundary conditions for k and ω are used, which depend on the equivalent sand grain roughness height, and account for the effective displacement of wall distance origin. Similarly in our approach, wall distance in the transition model for smooth surfaces is modified by an effective origin, which depends on roughness. Flat plate test cases are computed to show that the proposed model is able to predict the transition onset in agreement with a data correlation of transition location versus roughness height, Reynolds number, and inlet turbulence intensity. Experimental data for a turbine cascade are compared with the predicted results to validate the applicability of the proposed model. Supported by NSF Award Number 1228195.

  9. Prediction of boundary-layer transition caused by crossflow disturbances

    OpenAIRE

    Nomura, Toshiyuki; 野村 聡幸

    1999-01-01

    A prediction system for boundary layer transition is developed which consists of the Navier-Stokes code computing a compressible boundary layer, the linear PSE (Parabolized Stability Equations) code computing the spatial growth of a disturbance, and the N-factor code integrating the growth rate. The system is applied to the case that the transition of the compressible boundary layer on a swept cylinder is caused by cross flow disturbances which have the same spanwise wavelength as observed in...

  10. Empirical prediction of optical transitions in metallic armchair SWCNTs

    Directory of Open Access Journals (Sweden)

    G. R. Ahmed Jamal

    2015-12-01

    Full Text Available In this work, a quick and effective method to calculate the second and third optical transition energies of metallic armchair single-wall carbon nanotubes (SWCNT is presented. In this proposed method, the transition energy of any armchair SWCNT can be predicted directly by knowing its one chiral index as both of its chiral indices are same. The predicted results are compared with recent experimental data and found to be accurate over a wide diameter range from 2 to 4.8 nm. The empirical equation proposed here is also compared with that proposed in earlier works. The proposed way may help the research works or applications where information of optical transitions of armchair metallic nanotubes is needed.

  11. Standardisation of tracer and type of meal in the evaluation of gastric emptying and colon transit rates in normal Beagle dogs

    International Nuclear Information System (INIS)

    Dormehl, I.C.; Jordaan, J.H.; Jacobs, D.J.; Plessis, M. du; Pilloy, W.

    1984-01-01

    The transit of 111 In-labelled polymer beads of different particle sizes in the stomach and colon of five healthy Beagle dogs was monitored after intake of different kinds of meal by a gamma camera and data processor system. The various meals studied were a solid balanced type of dog food mixed with molk, pure milk, and finally a metal of raw meat. The polymer beads carried triethylenetetramine type functions which efficiently chelated 111 In +3 from an aqueous solution of InCl 3 . These labelled beads were well mixed into the food before being offered to the dogs. Gastric emptying curves from which half-times of emptying (Tsub(1/2)) could be obtained are presented and statistically compared. Good quality images with quantification of the colon transit rate also became possible. It appeared that standardisation of the tracer and of the metal is compulsory for relevant and reproducible results. (orig.)

  12. Standardisation of tracer and type of meal in the evaluation of gastric emptying and colon transit rates in normal Beagle dogs

    Energy Technology Data Exchange (ETDEWEB)

    Dormehl, I.C.; Jordaan, J.H.; Jacobs, D.J.; Plessis, M. du; Pilloy, W.

    1984-01-01

    The transit of /sup 111/In-labelled polymer beads of different particle sizes in the stomach and colon of five healthy Beagle dogs was monitored after intake of different kinds of meal by a gamma camera and data processor system. The various meals studied were a solid balanced type of dog food mixed with molk, pure milk, and finally a meal of raw meat. The polymer beads carried triethylenetetramine type functions which efficiently chelated /sup 111/In/sup +3/ from an aqueous solution of InCl/sub 3/. These labelled beads were well mixed into the food before being offered to the dogs. Gastric emptying curves from which half-times of emptying (Tsub(1/2)) could be obtained are presented and statistically compared. Good quality images with quantification of the colon transit rate also became possible. It appeared that standardisation of the tracer and of the metal is compulsory for relevant and reproducible results.

  13. (18)F-alfatide II and (18)F-FDG dual-tracer dynamic PET for parametric, early prediction of tumor response to therapy.

    Science.gov (United States)

    Guo, Jinxia; Guo, Ning; Lang, Lixin; Kiesewetter, Dale O; Xie, Qingguo; Li, Quanzheng; Eden, Henry S; Niu, Gang; Chen, Xiaoyuan

    2014-01-01

    or (18)F-FDG were observed, both (18)F-alfatide II Bp and (18)F-FDG influx from kinetic analysis in tumors showed significant decreases. For therapy of MDA-MB-435 tumors with paclitaxel protein-bound particles, a significant decrease was observed only with (18)F-alfatide II Bp value from kinetic analysis but not (18)F-FDG influx. The parameters fitted with compartmental modeling from the dual-tracer dynamic imaging are consistent with those from single-tracer imaging, substantiating the feasibility of this methodology. Even though no significant differences in tumor size were found until 5 d after doxorubicin treatment started, at day 3 there were already substantial differences in (18)F-alfatide II Bp and (18)F-FDG influx rate. Dual-tracer imaging can measure (18)F-alfatide II Bp value and (18)F-FDG influx simultaneously to evaluate tumor angiogenesis and metabolism. Such changes are known to precede anatomic changes, and thus parametric imaging may offer the promise of early prediction of therapy response.

  14. Tracer theory

    International Nuclear Information System (INIS)

    Margrita, R.

    1988-09-01

    Tracers are used in many fields of science to investigate mass transfer. The scope of tracers applications in Service of Applications Radioisotopes (S.A.R.-France) is large and concerns natural and industrial systems such as Sciences of earth: hydrology - civil engineering - Sedimentology - environmental studies. Industrial field: chemical engineering - mechanical engineering. A general tracer methodology has been developed in our laboratories from these different applications fields and this paper shows these different points of view in using tracers; our wish is that the methods used in an experimental field can be employed in an another one

  15. Predicting weather regime transitions in Northern Hemisphere datasets

    Energy Technology Data Exchange (ETDEWEB)

    Kondrashov, D. [University of California, Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, Los Angeles, CA (United States); Shen, J. [UCLA, Department of Statistics, Los Angeles, CA (United States); Berk, R. [UCLA, Department of Statistics, Los Angeles, CA (United States); University of Pennsylvania, Department of Criminology, Philadelphia, PA (United States); D' Andrea, F.; Ghil, M. [Ecole Normale Superieure, Departement Terre-Atmosphere-Ocean and Laboratoire de Meteorologie Dynamique (CNRS and IPSL), Paris Cedex 05 (France)

    2007-10-15

    A statistical learning method called random forests is applied to the prediction of transitions between weather regimes of wintertime Northern Hemisphere (NH) atmospheric low-frequency variability. A dataset composed of 55 winters of NH 700-mb geopotential height anomalies is used in the present study. A mixture model finds that the three Gaussian components that were statistically significant in earlier work are robust; they are the Pacific-North American (PNA) regime, its approximate reverse (the reverse PNA, or RNA), and the blocked phase of the North Atlantic Oscillation (BNAO). The most significant and robust transitions in the Markov chain generated by these regimes are PNA {yields} BNAO, PNA {yields} RNA and BNAO {yields} PNA. The break of a regime and subsequent onset of another one is forecast for these three transitions. Taking the relative costs of false positives and false negatives into account, the random-forests method shows useful forecasting skill. The calculations are carried out in the phase space spanned by a few leading empirical orthogonal functions of dataset variability. Plots of estimated response functions to a given predictor confirm the crucial influence of the exit angle on a preferred transition path. This result points to the dynamic origin of the transitions. (orig.)

  16. Prediction of iodine-131 biokinetics and radiation doses from therapy on the basis of tracer studies: an important question for therapy planning in nuclear medicine.

    Science.gov (United States)

    Willegaignon, José; Pelissoni, Rogério A; Lima, Beatriz C G D; Sapienza, Marcelo T; Coura-Filho, George B; Buchpiguel, Carlos A

    2016-05-01

    This study aimed to present a comparison of iodine-131 (I) biokinetics and radiation doses to red-marrow (rm) and whole-body (wb), following the administration of tracer and therapeutic activities, as a means of confirming whether I clearance and radiation doses for therapy procedures can be predicted by tracer activities. Eleven differentiated thyroid cancer patients were followed after receiving tracer and therapeutic I activity. Whole-body I clearance was estimated using radiation detectors and OLINDA/EXM software was used to calculate radiation doses to rm and wb. Tracer I activity of 86 (±14) MBq and therapeutic activity of 8.04 (±1.18) GBq were administered to patients, thereby producing an average wb I effective half-time and residence time of, respectively, 13.51 (±4.05) and 23.13 (±5.98) h for tracer activities and 13.32 (±3.38) and 19.63 (±4.77) h for therapy. Radiation doses to rm and wb were, respectively, 0.0467 (±0.0208) and 0.0589 (±0.0207) mGy/MBq in tracer studies and 0.0396 (±0.0169) and 0.0500 (±0.0163) mGy/MBq in therapy. Although the differences were not considered statistically significant between averages, those between the values of effective half-times (P=0.906), residence times (P=0.145), and radiation doses to rm (P=0.393) and to wb (P=0.272), from tracer and therapy procedures, large differences of up to 80% in wb I clearance, and up to 50% in radiation doses were observed when patients were analyzed individually, thus impacting on the total amount of I activity calculated to be safe for application in individual therapy. I biokinetics and radiation doses to rm and wb in therapy procedures are well predicted by diagnostic activities when average values of a group of patients are compared. Nonetheless, when patients are analyzed individually, significant differences may be encountered, thus implying that nuclear medicine therapy-planning requires due consideration of changes in individual patient-body status from

  17. Predicting transition in two- and three-dimensional separated flows

    International Nuclear Information System (INIS)

    Cutrone, L.; De Palma, P.; Pascazio, G.; Napolitano, M.

    2008-01-01

    This paper is concerned with the numerical prediction of two- and three-dimensional transitional separated flows of turbomachinery interest. The recently proposed single-point transition model based on the use of a laminar kinetic energy transport equation is considered, insofar as it does not require to evaluate any integral parameter, such as boundary-layer thickness, and is thus directly applicable to three-dimensional flows. A well established model, combining a transition-onset correlation with an intermittency transport equation, is also used for comparison. Both models are implemented within a Reynolds-averaged Navier-Stokes solver employing a low-Reynolds-number k-ω turbulence model. The performance of the transition models have been evaluated and tested versus well-documented incompressible flows past a flat plate with semi-circular leading edge, namely: tests T3L2, T3L3, T3L5, and T3LA1 of ERCOFTAC, with different Reynolds numbers and free-stream conditions, the last one being characterized by a non-zero pressure gradient. In all computations, the first model has proven as adequate as or superior to the second one and has been then applied with success to two more complex test cases, for which detailed experimental data are available in the literature, namely: the two- and three-dimensional flows through the T106 linear turbine cascade

  18. Transitioning a Chesapeake Bay Ecological Prediction System to Operations

    Science.gov (United States)

    Brown, C.; Green, D. S.; Eco Forecasters

    2011-12-01

    Ecological prediction of the impacts of physical, chemical, biological, and human-induced change on ecosystems and their components, encompass a wide range of space and time scales, and subject matter. They vary from predicting the occurrence and/or transport of certain species, such harmful algal blooms, or biogeochemical constituents, such as dissolved oxygen concentrations, to large-scale ecosystem responses and higher trophic levels. The timescales of ecological prediction, including guidance and forecasts, range from nowcasts and short-term forecasts (days), to intraseasonal and interannual outlooks (weeks to months), to decadal and century projections in climate change scenarios. The spatial scales range from small coastal inlets to basin and global scale biogeochemical and ecological forecasts. The types of models that have been used include conceptual, empirical, mechanistic, and hybrid approaches. This presentation will identify the challenges and progress toward transitioning experimental model-based ecological prediction into operational guidance and forecasting. Recent efforts are targeting integration of regional ocean, hydrodynamic and hydrological models and leveraging weather and water service infrastructure to enable the prototyping of an operational ecological forecast capability for the Chesapeake Bay and its tidal tributaries. A path finder demonstration predicts the probability of encountering sea nettles (Chrysaora quinquecirrha), a stinging jellyfish. These jellyfish can negatively impact safety and economic activities in the bay and an impact-based forecast that predicts where and when this biotic nuisance occurs may help management effects. The issuance of bay-wide nowcasts and three-day forecasts of sea nettle probability are generated daily by forcing an empirical habitat model (that predicts the probability of sea nettles) with real-time and 3-day forecasts of sea-surface temperature (SST) and salinity (SSS). In the first demonstration

  19. Experimental and computational prediction of glass transition temperature of drugs.

    Science.gov (United States)

    Alzghoul, Ahmad; Alhalaweh, Amjad; Mahlin, Denny; Bergström, Christel A S

    2014-12-22

    Glass transition temperature (Tg) is an important inherent property of an amorphous solid material which is usually determined experimentally. In this study, the relation between Tg and melting temperature (Tm) was evaluated using a data set of 71 structurally diverse druglike compounds. Further, in silico models for prediction of Tg were developed based on calculated molecular descriptors and linear (multilinear regression, partial least-squares, principal component regression) and nonlinear (neural network, support vector regression) modeling techniques. The models based on Tm predicted Tg with an RMSE of 19.5 K for the test set. Among the five computational models developed herein the support vector regression gave the best result with RMSE of 18.7 K for the test set using only four chemical descriptors. Hence, two different models that predict Tg of drug-like molecules with high accuracy were developed. If Tm is available, a simple linear regression can be used to predict Tg. However, the results also suggest that support vector regression and calculated molecular descriptors can predict Tg with equal accuracy, already before compound synthesis.

  20. Environmental Tracers

    Directory of Open Access Journals (Sweden)

    Trevor Elliot

    2014-10-01

    Full Text Available Environmental tracers continue to provide an important tool for understanding the source, flow and mixing dynamics of water resource systems through their imprint on the system or their sensitivity to alteration within it. However, 60 years or so after the first isotopic tracer studies were applied to hydrology, the use of isotopes and other environmental tracers are still not routinely necessarily applied in hydrogeological and water resources investigations where appropriate. There is therefore a continuing need to promote their use for developing sustainable management policies for the protection of water resources and the aquatic environment. This Special Issue focuses on the robustness or fitness-for-purpose of the application and use of environmental tracers in addressing problems and opportunities scientifically, to promote their wider use and to address substantive issues of vulnerability, sustainability, and uncertainty in (groundwater resources systems and their management.

  1. Journal: Efficient Hydrologic Tracer-Test Design for Tracer ...

    Science.gov (United States)

    Hydrological tracer testing is the most reliable diagnostic technique available for the determination of basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowledge of the basic hydraulic and geometric parameters desired and the appropriate tracer mass to release. A new efficient hydrologic tracer-test design (EHTD) methodology has been developed to facilitate the design of tracer tests by root determination of the one-dimensional advection-dispersion equation (ADE) using a preset average tracer concentration which provides a theoretical basis for an estimate of necessary tracer mass. The method uses basic measured field parameters (e.g., discharge, distance, cross-sectional area) that are combined in functional relatipnships that descrive solute-transport processes related to flow velocity and time of travel. These initial estimates for time of travel and velocity are then applied to a hypothetical continuous stirred tank reactor (CSTR) as an analog for the hydrological-flow system to develop initial estimates for tracer concentration, tracer mass, and axial dispersion. Application of the predicted tracer mass with the hydraulic and geometric parameters in the ADE allows for an approximation of initial sample-collection time and subsequent sample-collection frequency where a maximum of 65 samples were determined to be necessary for descri

  2. Tracer simulation using a global general circulation model: Results from a midlatitude instantaneous source experiment

    International Nuclear Information System (INIS)

    Mahlman, J.D.; Moxim, W.J.

    1978-01-01

    An 11-level general circulation model with seasonal variation is used to perform an experiment on the dispersion of passive tracers. Specially constructed time-dependent winds from this model are used as input to a separate tracer model. The methodologies employed to construct the tracer model are described.The experiment presented is the evolution of a hypothetical instantaneous source of tracer on 1 Janaury with maximum initial concentration at 65 mb, 36 0 N, 180 0 E. The tracer is assumed to have no sources or sinks in the stratosphere, but is subject to removal processes in the lower troposphere.The experimental results reveal a number of similarities to observed tracer behavior, including the average poleward-downward slope of mixing ratio isopleths, strong tracer gradients across the tropopause, intrusion of tracer into the Southern Hemisphere lower stratosphere, and the long-term interhemispheric exchange rate. The model residence times show behavior intermediate to those exhibited for particulate radioactive debris and gaseous C 14 O 2 . This suggests that caution should be employed when either radioactive debris or C 14 O 2 data are used to develop empirical models for prediction of gaseous tracers which are efficiently removed in the troposphere.In this experiment, the tracer mixing ratio and potential vorticity evolve to very high correlations. Mechanisms for this correlation are discussed. The zonal mean tracer balances exhibit complex behavior among the various transport terms. At early stages, the tracer evolution is dominated by eddy effects. Later, a very large degree of self-cancellation between mean cell and eddy effects is observed. During seasonal transitions, however, this self-cancellation diminishes markedly, leading to significant changes in the zonal mean tracer distribution. A possible theoretical explanation is presented

  3. Improving Prediction of Large-scale Regime Transitions

    Science.gov (United States)

    Gyakum, J. R.; Roebber, P.; Bosart, L. F.; Honor, A.; Bunker, E.; Low, Y.; Hart, J.; Bliankinshtein, N.; Kolly, A.; Atallah, E.; Huang, Y.

    2017-12-01

    Cool season atmospheric predictability over the CONUS on subseasonal times scales (1-4 weeks) is critically dependent upon the structure, configuration, and evolution of the North Pacific jet stream (NPJ). The NPJ can be perturbed on its tropical side on synoptic time scales by recurving and transitioning tropical cyclones (TCs) and on subseasonal time scales by longitudinally varying convection associated with the Madden-Julian Oscillation (MJO). Likewise, the NPJ can be perturbed on its poleward side on synoptic time scales by midlatitude and polar disturbances that originate over the Asian continent. These midlatitude and polar disturbances can often trigger downstream Rossby wave propagation across the North Pacific, North America, and the North Atlantic. The project team is investigating the following multiscale processes and features: the spatiotemporal distribution of cyclone clustering over the Northern Hemisphere; cyclone clustering as influenced by atmospheric blocking and the phases and amplitudes of the major teleconnection indices, ENSO and the MJO; composite and case study analyses of representative cyclone clustering events to establish the governing dynamics; regime change predictability horizons associated with cyclone clustering events; Arctic air mass generation and modification; life cycles of the MJO; and poleward heat and moisture transports of subtropical air masses. A critical component of the study is weather regime classification. These classifications are defined through: the spatiotemporal clustering of surface cyclogenesis; a general circulation metric combining data at 500-hPa and the dynamic tropopause; Self Organizing Maps (SOM), constructed from dynamic tropopause and 850 hPa equivalent potential temperature data. The resultant lattice of nodes is used to categorize synoptic classes and their predictability, as well as to determine the robustness of the CFSv2 model climate relative to observations. Transition pathways between these

  4. Short-Term Prediction Research and Transition (SPoRT) Center: Transitioning Satellite Data to Operations

    Science.gov (United States)

    Zavodsky, Bradley

    2012-01-01

    The Short-term Prediction Research and Transition (SPoRT) Center located at NASA Marshall Space Flight Center has been conducting testbed activities aimed at transitioning satellite products to National Weather Service operational end users for the last 10 years. SPoRT is a NASA/NOAA funded project that has set the bar for transition of products to operational end users through a paradigm of understanding forecast challenges and forecaster needs, displaying products in end users decision support systems, actively assessing the operational impact of these products, and improving products based on forecaster feedback. Aiming for quality partnerships rather than a large quantity of data users, SPoRT has become a community leader in training operational forecasters on the use of up-and-coming satellite data through the use of legacy instruments and proxy data. Traditionally, SPoRT has supplied satellite imagery and products from NASA instruments such as the Moderate-resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS). However, recently, SPoRT has been funded by the GOES-R and Joint Polar Satellite System (JPSS) Proving Grounds to accelerate the transition of selected imagery and products to help improve forecaster awareness of upcoming operational data from the Visible Infrared Imager Radiometer Suite (VIIRS), Cross-track Infrared Sounder (CrIS), Advanced Baseline Imager (ABI), and Geostationary Lightning Mapper (GLM). This presentation provides background on the SPoRT Center, the SPoRT paradigm, and some example products that SPoRT is excited to work with forecasters to evaluate.

  5. Towards Bridging the Gaps in Holistic Transition Prediction via Numerical Simulations

    Science.gov (United States)

    Choudhari, Meelan M.; Li, Fei; Duan, Lian; Chang, Chau-Lyan; Carpenter, Mark H.; Streett, Craig L.; Malik, Mujeeb R.

    2013-01-01

    The economic and environmental benefits of laminar flow technology via reduced fuel burn of subsonic and supersonic aircraft cannot be realized without minimizing the uncertainty in drag prediction in general and transition prediction in particular. Transition research under NASA's Aeronautical Sciences Project seeks to develop a validated set of variable fidelity prediction tools with known strengths and limitations, so as to enable "sufficiently" accurate transition prediction and practical transition control for future vehicle concepts. This paper provides a summary of selected research activities targeting the current gaps in high-fidelity transition prediction, specifically those related to the receptivity and laminar breakdown phases of crossflow induced transition in a subsonic swept-wing boundary layer. The results of direct numerical simulations are used to obtain an enhanced understanding of the laminar breakdown region as well as to validate reduced order prediction methods.

  6. Using tracer-derived groundwater transit times to assess storage within a high-elevation watershed of the upper Colorado River Basin, USA

    Science.gov (United States)

    Georgek, Jennifer L.; Kip Solomon, D.; Heilweil, Victor M.; Miller, Matthew P.

    2018-03-01

    Previous watershed assessments have relied on annual baseflow to evaluate the groundwater contribution to streams. To quantify the volume of groundwater in storage, additional information such as groundwater mean transit time (MTT) is needed. This study determined the groundwater MTT in the West Fork Duchesne watershed in Utah (USA) with lumped-parameter modeling of environmental tracers (SF6, CFCs, and 3H/3He) from 21 springs. Approximately 30% of the springs exhibited an exponential transit time distribution (TTD); the remaining 70% were best characterized by a piston-flow TTD. The flow-weighted groundwater MTT for the West Fork watershed is about 40 years with approximately 20 years in the unsaturated zone. A cumulative distribution of these ages revealed that most of the groundwater is between 30 and 50 years old, suggesting that declining recharge associated with 5-10-year droughts is less likely to have a profound effect on this watershed compared with systems with shorter MTTs. The estimated annual baseflow of West Fork stream flow based on chemical hydrograph separation is 1.7 × 107 m3/year, a proxy for groundwater discharge. Using both MTT and groundwater discharge, the volume of mobile groundwater stored in the watershed was calculated to be 6.5 × 108 m3, or 20 m thickness of active groundwater storage and recharge of 0.09 m/year (assuming porosity = 15%). Future watershed-scale assessments should evaluate groundwater MTT, in addition to annual baseflow, to quantify groundwater storage and more accurately assess watershed susceptibility to drought, groundwater extraction, and land-use change.

  7. Transition-state theory predicts clogging at the microscale

    Science.gov (United States)

    Laar, T. Van De; Klooster, S. Ten; Schroën, K.; Sprakel, J.

    2016-06-01

    Clogging is one of the main failure mechanisms encountered in industrial processes such as membrane filtration. Our understanding of the factors that govern the build-up of fouling layers and the emergence of clogs is largely incomplete, so that prevention of clogging remains an immense and costly challenge. In this paper we use a microfluidic model combined with quantitative real-time imaging to explore the influence of pore geometry and particle interactions on suspension clogging in constrictions, two crucial factors which remain relatively unexplored. We find a distinct dependence of the clogging rate on the entrance angle to a membrane pore which we explain quantitatively by deriving a model, based on transition-state theory, which describes the effect of viscous forces on the rate with which particles accumulate at the channel walls. With the same model we can also predict the effect of the particle interaction potential on the clogging rate. In both cases we find excellent agreement between our experimental data and theory. A better understanding of these clogging mechanisms and the influence of design parameters could form a stepping stone to delay or prevent clogging by rational membrane design.

  8. Ages and transit times as important diagnostics of model performance for predicting carbon dynamics in terrestrial vegetation models

    Science.gov (United States)

    Ceballos-Núñez, Verónika; Richardson, Andrew D.; Sierra, Carlos A.

    2018-03-01

    The global carbon cycle is strongly controlled by the source/sink strength of vegetation as well as the capacity of terrestrial ecosystems to retain this carbon. These dynamics, as well as processes such as the mixing of old and newly fixed carbon, have been studied using ecosystem models, but different assumptions regarding the carbon allocation strategies and other model structures may result in highly divergent model predictions. We assessed the influence of three different carbon allocation schemes on the C cycling in vegetation. First, we described each model with a set of ordinary differential equations. Second, we used published measurements of ecosystem C compartments from the Harvard Forest Environmental Measurement Site to find suitable parameters for the different model structures. And third, we calculated C stocks, release fluxes, radiocarbon values (based on the bomb spike), ages, and transit times. We obtained model simulations in accordance with the available data, but the time series of C in foliage and wood need to be complemented with other ecosystem compartments in order to reduce the high parameter collinearity that we observed, and reduce model equifinality. Although the simulated C stocks in ecosystem compartments were similar, the different model structures resulted in very different predictions of age and transit time distributions. In particular, the inclusion of two storage compartments resulted in the prediction of a system mean age that was 12-20 years older than in the models with one or no storage compartments. The age of carbon in the wood compartment of this model was also distributed towards older ages, whereas fast cycling compartments had an age distribution that did not exceed 5 years. As expected, models with C distributed towards older ages also had longer transit times. These results suggest that ages and transit times, which can be indirectly measured using isotope tracers, serve as important diagnostics of model structure

  9. Using Diffusion Tractography to Predict Cortical Connection Strength and Distance: A Quantitative Comparison with Tracers in the Monkey

    DEFF Research Database (Denmark)

    Donahue, Chad J.; Sotiropoulos, Stamatios N.; Jbabdi, Saad

    2016-01-01

    of tractography for analyzing interareal corticocortical connectivity in nonhuman primates and a framework for assessing future tractography methodological refinements objectively. SIGNIFICANCE STATEMENT Tractography based on diffusion MRI has great potential for a variety of applications, including estimation......Tractography based on diffusion MRI offers the promise of characterizing many aspects of long-distance connectivity in the brain, but requires quantitative validation to assess its strengths and limitations. Here, we evaluate tractography's ability to estimate the presence and strength...... of connections between areas of macaque neocortex by comparing its results with published data from retrograde tracer injections. Probabilistic tractography was performed on high-quality postmortem diffusion imaging scans from two Old World monkey brains. Tractography connection weights were estimated using...

  10. Transition prediction on the NORDTANK 500/41 turbine rotor

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, N.N.

    2002-09-01

    A new simplified transition model for wind turbine blades is described along with the implementation in the EllipSys3D code. The method is based on a sectional treatment of the turbine blade under the assumption of chordwise flow, and lookup tables of transition point location computed by external 2D programs. The coupling of the 2D transition point location and the 3D sectional flow is performed through the stagnation point location. The method is applied to a single rotor case, the NORDTANK 500/41 rotor with LM19.1 blades. The transitional computations show improved agreement with measurements for wind speeds between 11 and 15 m/s. For higher wind speeds, the validity of the transition location computed by the 2D XFOIL code is questionable, and the results cannot be trusted. Analysis of the results comparing fully turbulent and transitional spanwise distributions of tangential forces, reveal that the decrease in power production when applying the transition model is mainly a consequence of the decrease in driving force on the inboard part of the blade between 5 and 12 meter radius. The results are very encouraging, and further studies of other rotors are needed for further validation. (au)

  11. Climate Prediction Center (CPC) Pacific Transition Teleconnection Pattern Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly tabulated index of the Pacific Transition teleconnection pattern. The data spans the period 1950 to present. The index is derived from a rotated principal...

  12. High-Fidelity Aerodynamic Design with Transition Prediction, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To enhance aerodynamic design capabilities, Desktop Aeronautics proposes to combine a new sweep/taper integrated-boundary-layer (IBL) code that includes transition...

  13. An Ordered Regression Model to Predict Transit Passengers’ Behavioural Intentions

    Energy Technology Data Exchange (ETDEWEB)

    Oña, J. de; Oña, R. de; Eboli, L.; Forciniti, C.; Mazzulla, G.

    2016-07-01

    Passengers’ behavioural intentions after experiencing transit services can be viewed as signals that show if a customer continues to utilise a company’s service. Users’ behavioural intentions can depend on a series of aspects that are difficult to measure directly. More recently, transit passengers’ behavioural intentions have been just considered together with the concepts of service quality and customer satisfaction. Due to the characteristics of the ways for evaluating passengers’ behavioural intentions, service quality and customer satisfaction, we retain that this kind of issue could be analysed also by applying ordered regression models. This work aims to propose just an ordered probit model for analysing service quality factors that can influence passengers’ behavioural intentions towards the use of transit services. The case study is the LRT of Seville (Spain), where a survey was conducted in order to collect the opinions of the passengers about the existing transit service, and to have a measure of the aspects that can influence the intentions of the users to continue using the transit service in the future. (Author)

  14. Predictions of glass transition temperature for hydrogen bonding biomaterials.

    Science.gov (United States)

    van der Sman, R G M

    2013-12-19

    We show that the glass transition of a multitude of mixtures containing hydrogen bonding materials correlates strongly with the effective number of hydroxyl groups per molecule, which are available for intermolecular hydrogen bonding. This correlation is in compliance with the topological constraint theory, wherein the intermolecular hydrogen bonds constrain the mobility of the hydrogen bonded network. The finding that the glass transition relates to hydrogen bonding rather than free volume agrees with our recent finding that there is little difference in free volume among carbohydrates and polysaccharides. For binary and ternary mixtures of sugars, polyols, or biopolymers with water, our correlation states that the glass transition temperature is linear with the inverse of the number of effective hydroxyl groups per molecule. Only for dry biopolymer/sugar or sugar/polyol mixtures do we find deviations due to nonideal mixing, imposed by microheterogeneity.

  15. Tracer a application in marine outfall studies

    International Nuclear Information System (INIS)

    Genders, S.

    1979-01-01

    The applicability of radioactive and fluorescent tracers for field studies to predict or investigate waste water transport and dispersion from marine outfalls is evaluated. The application of either instantaneous or continuous tracer release, 'in situ' detection of tracers and data processing are considered. The necessity of a combined use of tracer techniques and conventional hydrographic methods for a statistical prediction of transport and dillution of waste water are pointed out. A procedure to determine an outlet distance from the coast, which satisfy bathing water criteria is outlined. (M.A.) [pt

  16. Predicting landscape vegetation dynamics using state-and-transition simulation models

    Science.gov (United States)

    Colin J. Daniel; Leonardo. Frid

    2012-01-01

    This paper outlines how state-and-transition simulation models (STSMs) can be used to project changes in vegetation over time across a landscape. STSMs are stochastic, empirical simulation models that use an adapted Markov chain approach to predict how vegetation will transition between states over time, typically in response to interactions between succession,...

  17. Prospective prediction of children's smoking transitions: role of parents' and older siblings' smoking.

    Science.gov (United States)

    Bricker, Jonathan B; Peterson, Arthur V; Leroux, Brian G; Andersen, M Robyn; Rajan, K Bharat; Sarason, Irwin G

    2006-01-01

    To use a novel social epidemic probability model to investigate longitudinally the extent to which parents' and older siblings' smoking predict children's smoking transitions. Parents' and older siblings' smoking status was assessed when children were in 3rd grade (baseline). Three smoking transitions were assessed over the period of child/adolescent smoking acquisition (up to 12th grade): (1) transition from never smoking to trying smoking, (2) transition from trying to monthly smoking and (3) transition from monthly to daily smoking. Forty Washington State school districts participating in the long term Hutchinson Smoking Prevention Project (HSPP). Participants were the 5520 families for whom data on both parents' and older siblings' baseline smoking status, as well as on children's smoking transitions, were available. The probability that a smoking parent influenced their child to make the first transition to trying smoking was 32% (95% CI: 27%, 36%); to make the second transition from trying to monthly smoking, 15% (95% CI: 10%, 19%); and to make the third transition from monthly to daily smoking, 28% (95% CI: 21%, 34%). The probability that an older sibling influenced a child to make the first transition to trying smoking was 29% (95% CI: 17%, 39%); to make the second transition from trying to monthly smoking, 0% (95% CI: 0%, 8%); and to make the third transition from monthly to daily smoking, 20% (95% CI: 4%, 33%). In contrast to previous research, the results provide new evidence suggesting that family smoking influences both initiation and escalation of children's smoking. Results also quantify, in terms of probabilities, the importance of parents' and older siblings' smoking on children's three major smoking transitions. Parents' smoking, as well as older siblings' smoking, are important behaviors to target in preventing adolescents from making smoking transitions.

  18. Detecting, anticipating, and predicting critical transitions in spatially extended systems.

    Science.gov (United States)

    Kwasniok, Frank

    2018-03-01

    A data-driven linear framework for detecting, anticipating, and predicting incipient bifurcations in spatially extended systems based on principal oscillation pattern (POP) analysis is discussed. The dynamics are assumed to be governed by a system of linear stochastic differential equations which is estimated from the data. The principal modes of the system together with corresponding decay or growth rates and oscillation frequencies are extracted as the eigenvectors and eigenvalues of the system matrix. The method can be applied to stationary datasets to identify the least stable modes and assess the proximity to instability; it can also be applied to nonstationary datasets using a sliding window approach to track the changing eigenvalues and eigenvectors of the system. As a further step, a genuinely nonstationary POP analysis is introduced. Here, the system matrix of the linear stochastic model is time-dependent, allowing for extrapolation and prediction of instabilities beyond the learning data window. The methods are demonstrated and explored using the one-dimensional Swift-Hohenberg equation as an example, focusing on the dynamics of stochastic fluctuations around the homogeneous stable state prior to the first bifurcation. The POP-based techniques are able to extract and track the least stable eigenvalues and eigenvectors of the system; the nonstationary POP analysis successfully predicts the timing of the first instability and the unstable mode well beyond the learning data window.

  19. Fluctuation theorem for an optically trapped tracer in dense colloids. A simulation study

    Directory of Open Access Journals (Sweden)

    Puertas Antonio M.

    2013-03-01

    Full Text Available The work supplied by an external parabolic potential that traps one tracer in a colloidal system is studied in this work by computer simulations. The density of the bath is changed from zero up to values close to the glass transition, and the velocity varies over several decades from the linear behaviour in the low Peclet limit to the high Peclet limit. The work distributions are analyzed using the model for the isolated Brownian partice, where the friction coefficient and temperature of the medium have been fitted to reproduce the position distribution of the tracer in the trap. The overall agreement is good but not perfect. The region of negative works is studied in more detail using the predictions of the fluctuation theorem, finding good qualitative agreement with the model of the isolated Brownian particle. The present results indicate that the fluctuation theorem is of application in cases where the tracer dynamics is complex, as predicted by theoretical works.

  20. A Tracer Experiment to Understand Dispersion Characteristics at a Nuclear Power Plant Site-Focusing on the Comparison with Predictive Results using Reg. Guide 1.145 model

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyojoon; Kim, Eunhan; Jeong, Haesun; Hwang, Wontae; Han, Moonhee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    There remains disagreement regarding the application of a Gaussian plume model in PAVAN, as it relates to the complicated geographical features of a coastal area. Therefore, this study was performed in order to figure out the characteristics of the PAVAN program that was developed based on the equations of Gaussian Plume Model, which reflected the actual measured concentration of radioactive materials released to the air. It also evaluated the appropriateness of using a Gaussian plume model for assessing the environmental impact of radiation from a nuclear power plant. In order to analyze the dispersion characteristics of radioactive materials released into the air from the Wolsong nuclear power plant, SF{sub 6} gas was released from the site at night for one hour under stable atmospheric conditions disadvantageous to dilute a tracer gas in this study. The measured concentrations were compared with theoretical estimates derived from meteorological data observed during the experiment period to evaluate the prediction capabilities of the Gaussian plume model. This study conducted a tracer dispersion experiment at the site of Wolsong Nuclear Power Plant site in Korea to analyze the atmospheric dispersion characteristics of radioactive materials. It compared the experimental value with the calculated value using the Gaussian Plume Model as suggested in Reg. 1.145, based on the meteorological data observed in the experiment time period, and evaluated the conservative estimate of the calculated value. In the area where the calculated value is relatively high, the calculated value tends to show higher than the experimental value, which confirmed the conservative manner of the estimating of the calculated value using the Gaussian Plume Model. The short-term exposure of radiation to a human body caused by a nuclear accident would be higher in the area where the atmospheric concentration of radiation is high. Therefore, it is a sufficiently conservative manner to use the

  1. A Tracer Experiment to Understand Dispersion Characteristics at a Nuclear Power Plant Site-Focusing on the Comparison with Predictive Results using Reg. Guide 1.145 model

    International Nuclear Information System (INIS)

    Jeong, Hyojoon; Kim, Eunhan; Jeong, Haesun; Hwang, Wontae; Han, Moonhee

    2014-01-01

    There remains disagreement regarding the application of a Gaussian plume model in PAVAN, as it relates to the complicated geographical features of a coastal area. Therefore, this study was performed in order to figure out the characteristics of the PAVAN program that was developed based on the equations of Gaussian Plume Model, which reflected the actual measured concentration of radioactive materials released to the air. It also evaluated the appropriateness of using a Gaussian plume model for assessing the environmental impact of radiation from a nuclear power plant. In order to analyze the dispersion characteristics of radioactive materials released into the air from the Wolsong nuclear power plant, SF 6 gas was released from the site at night for one hour under stable atmospheric conditions disadvantageous to dilute a tracer gas in this study. The measured concentrations were compared with theoretical estimates derived from meteorological data observed during the experiment period to evaluate the prediction capabilities of the Gaussian plume model. This study conducted a tracer dispersion experiment at the site of Wolsong Nuclear Power Plant site in Korea to analyze the atmospheric dispersion characteristics of radioactive materials. It compared the experimental value with the calculated value using the Gaussian Plume Model as suggested in Reg. 1.145, based on the meteorological data observed in the experiment time period, and evaluated the conservative estimate of the calculated value. In the area where the calculated value is relatively high, the calculated value tends to show higher than the experimental value, which confirmed the conservative manner of the estimating of the calculated value using the Gaussian Plume Model. The short-term exposure of radiation to a human body caused by a nuclear accident would be higher in the area where the atmospheric concentration of radiation is high. Therefore, it is a sufficiently conservative manner to use the Gaussian

  2. Transitioning from interpretive to predictive in thermal hydraulic codes

    International Nuclear Information System (INIS)

    Mousseau, V.A.

    2004-01-01

    The current thermal hydraulic codes in use in the US, RELAP and TRAC, where originally written in the mid to late 1970's. At that time computers were slow, expensive, and had small memories. Because of these constraints, sacrifices had to be made, both in physics and numerical methods, which resulted in limitations on the accuracy of the solutions. Significant changes have occurred that induce very different requirements for the thermal hydraulic codes to be used for the future GEN-IV nuclear reactors. First, computers speed and memory grow at an exponential rate while the costs hold constant or decrease. Second, passive safety systems in modern designs stretch the length of relevant transients to many days. Finally, costs of experiments have grown very rapidly. Because of these new constraints, modern thermal hydraulic codes will be relied on for a significantly larger portion of bringing a nuclear reactor on line. Simulation codes will have to define in which part of state space experiments will be run. They will then have to be able to extend the small number of experiments to cover the large state space in which the reactors will operate. This data extrapolation mode will be referred to as 'predictive'. One of the keys to analyzing the accuracy of a simulation is to consider the entire domain being simulated. For example, in a reactor design where the containment is coupled to the reactor cooling system through radiative heat transfer, the accuracy of a transient includes the containment, the radiation heat transfer, the fluid flow in the cooling system, the thermal conduction in the solid, and the neutron transport in the reactor. All of this physics is coupled together in one nonlinear system through material properties, cross sections, heat transfer coefficients, and other mechanisms that exchange mass, momentum, and energy. Traditionally, these different physical domains, (containment, cooling system, nuclear fuel, etc.) have been solved in different

  3. Trip time prediction in mass transit companies. A machine learning approach

    OpenAIRE

    João M. Moreira; Alípio Jorge; Jorge Freire de Sousa; Carlos Soares

    2005-01-01

    In this paper we discuss how trip time prediction can be useful foroperational optimization in mass transit companies and which machine learningtechniques can be used to improve results. Firstly, we analyze which departmentsneed trip time prediction and when. Secondly, we review related work and thirdlywe present the analysis of trip time over a particular path. We proceed by presentingexperimental results conducted on real data with the forecasting techniques wefound most adequate, and concl...

  4. Transition Prediction in Hypersonic Boundary Layers Using Receptivity and Freestream Spectra

    Science.gov (United States)

    Balakumar, P.; Chou, Amanda

    2016-01-01

    Boundary-layer transition in hypersonic flows over a straight cone can be predicted using measured freestream spectra, receptivity, and threshold values for the wall pressure fluctuations at the transition onset points. Simulations are performed for hypersonic boundary-layer flows over a 7-degree half-angle straight cone with varying bluntness at a freestream Mach number of 10. The steady and the unsteady flow fields are obtained by solving the two-dimensional Navier-Stokes equations in axisymmetric coordinates using a 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using a third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The calculated N-factors at the transition onset location increase gradually with increasing unit Reynolds numbers for flow over a sharp cone and remain almost the same for flow over a blunt cone. The receptivity coefficient increases slightly with increasing unit Reynolds numbers. They are on the order of 4 for a sharp cone and are on the order of 1 for a blunt cone. The location of transition onset predicted from the simulation including the freestream spectrum, receptivity, and the linear and the weakly nonlinear evolutions yields a solution close to the measured onset location for the sharp cone. The simulations over-predict transition onset by about twenty percent for the blunt cone.

  5. Ecological Factors Predict Transition Readiness/Self-Management in Youth With Chronic Conditions.

    Science.gov (United States)

    Javalkar, Karina; Johnson, Meredith; Kshirsagar, Abhijit V; Ocegueda, Sofia; Detwiler, Randal K; Ferris, Maria

    2016-01-01

    Health care transition readiness or self-management among adolescents and young adults (AYA) with chronic conditions may be influenced by factors related to their surrounding environment. Study participants were AYA diagnosed with a chronic condition and evaluated at pediatric- and adult-focused subspecialty clinics at the University of North Carolina Hospital Systems. All participants were administered a provider-administered self-management/transition-readiness tool, the UNC TRxANSITION Scale. Geographic area and associated characteristics (ecological factors) were identified for each participant's ZIP code using the published U.S. Census data. The Level 1 model of the hierarchical linear regression used individual-level predictors of transition readiness/self-management. The Level 2 model incorporated the ecological factors. We enrolled 511 AYA with different chronic conditions aged 12-31 years with the following characteristics: mean age of 20± 4 years, 45% white, 42% black, and 54% female. Participants represented 214 ZIP codes in or around North Carolina, USA. The Level 1 model showed that age, gender, and race were significant predictors of transition readiness/self-management. On adding the ecological factors in the Level 2 model, race was no longer significant. Participants from a geographic area with a greater percentage of females (β = .114, p = .005) and a higher median income (β = .126, p = .002) had greater overall transition readiness. Ecological factors also predicted subdomains of transition readiness/self-management. In this cohort of adolescents and young adults with different chronic conditions, ecological disparities such as sex composition, median income, and language predict self-management/transition readiness. It is important to take ecological risk factors into consideration when preparing patients for health self-management or transition. Copyright © 2016 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All

  6. In Situ Tracer method for establishing the presence and predicting the activity of heavy metal-reducing microbes in the subsurface. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hatfield, K.

    2003-07-01

    Tracer method to establish presence and distribution of chromium reducing microbes. The primary objective of this research was to establish an in situ tracer method for detecting the presence. distribution. and activity of subsurface heavy metal-reducing microorganisms. Research focused on microbial systems responsible for the reduction of chromium and a suite of biotracers coupled to the reduction process. The tracer method developed may be used to characterize sites contaminated with chromium or expedite bioremediation: and although research focused on chromium. the method can be easily extended to other metals, organics, and radionuclides. This brief final report contains three major sections. The first identifies specific products of the research effort such as students supported and publications. The second section briefly presents major research findings, while the last section summarizes the overall research effort.

  7. Delivery Mode and the Transition of Pioneering Gut-Microbiota Structure, Composition and Predicted Metabolic Function

    Directory of Open Access Journals (Sweden)

    Noel T. Mueller

    2017-12-01

    Full Text Available Cesarean (C-section delivery, recently shown to cause excess weight gain in mice, perturbs human neonatal gut microbiota development due to the lack of natural mother-to-newborn transfer of microbes. Neonates excrete first the in-utero intestinal content (referred to as meconium hours after birth, followed by intestinal contents reflective of extra-uterine exposure (referred to as transition stool 2 to 3 days after birth. It is not clear when the effect of C-section on the neonatal gut microbiota emerges. We examined bacterial DNA in carefully-collected meconium, and the subsequent transitional stool, from 59 neonates [13 born by scheduled C-section and 46 born by vaginal delivery] in a private hospital in Brazil. Bacterial DNA was extracted, and the V4 region of the 16S rRNA gene was sequenced using the Illumina MiSeq (San Diego, CA, USA platform. We found evidence of bacterial DNA in the majority of meconium samples in our study. The bacterial DNA structure (i.e., beta diversity of meconium differed significantly from that of the transitional stool microbiota. There was a significant reduction in bacterial alpha diversity (e.g., number of observed bacterial species and change in bacterial composition (e.g., reduced Proteobacteria in the transition from meconium to stool. However, changes in predicted microbiota metabolic function from meconium to transitional stool were only observed in vaginally-delivered neonates. Within sample comparisons showed that delivery mode was significantly associated with bacterial structure, composition and predicted microbiota metabolic function in transitional-stool samples, but not in meconium samples. Specifically, compared to vaginally delivered neonates, the transitional stool of C-section delivered neonates had lower proportions of the genera Bacteroides, Parabacteroides and Clostridium. These differences led to C-section neonates having lower predicted abundance of microbial genes related to metabolism of

  8. A two-parameter model to predict fracture in the transition

    International Nuclear Information System (INIS)

    DeAquino, C.T.; Landes, J.D.; McCabe, D.E.

    1995-01-01

    A model is proposed that uses a numerical characterization of the crack tip stress field modified by the J - Q constraint theory and a weak link assumption to predict fracture behavior in the transition for reactor vessel steels. This model predicts the toughness scatter band for a component model from a toughness scatter band measured on a test specimen geometry. The model has been applied previously to two-dimensional through cracks. Many applications to actual components structures involve three-dimensional surface flaws. These cases require a more difficult level of analysis and need additional information. In this paper, both the current model for two-dimensional cracks and an approach needed to extend the model for the prediction of transition fracture behavior in three-dimensional surface flaws are discussed. Examples are presented to show how the model can be applied and in some cases to compare with other test results. (author). 13 refs., 7 figs

  9. Prediction and Analysis of the Nonsteady Transition and Separation Processes on an Oscillating Wind Turbine Airfoil using the \\gamma-Re_\\theta Transition Model.

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Taraj; Brasseur, James; Vijayakumar, Ganesh

    2016-01-04

    This study is aimed at gaining insight into the nonsteady transitional boundary layer dynamics of wind turbine blades and the predictive capabilities of URANS based transition and turbulence models for similar physics through the analysis of a controlled flow with similar nonsteady parameters.

  10. Mixing as a driver of temporal variations in river hydrochemistry: 1. Insights from conservative tracers in the Andes-Amazon transition

    Science.gov (United States)

    Torres, Mark A.; Baronas, J. Jotautas; Clark, Kathryn E.; Feakins, Sarah J.; West, A. Joshua

    2017-04-01

    The response of hillslope processes to changes in precipitation may drive the observed changes in the solute geochemistry of rivers with discharge. This conjecture is most robust when variations in the key environmental factors that affect hillslope processes (e.g., lithology, erosion rate, and climate) are minimal across a river's catchment area. For rivers with heterogenous catchments, temporal variations in the relative contributions of different tributary subcatchments may modulate variations in solute geochemistry with runoff. In the absence of a dense network of hydrologic gauging stations, alternative approaches are required to distinguish between the different drivers of temporal variability in river solute concentrations. In this contribution, we apportion the water and solute fluxes of a reach of the Madre de Dios River (Peru) between its four major tributary subcatchments during two sampling campaigns (wet and dry seasons) using spatial variations in conservative tracers. Guided by the results of a mixing model, we identify temporal variations in solute concentrations of the main stem Madre de Dios that are due to changes in the relative contributions of each tributary. Our results suggest that variations in tributary mixing are, in part, responsible for the observed concentration-discharge (C-Q) relationships. The implications of these results are further explored by reanalyzing previously published C-Q data from this region, developing a theoretical model of tributary mixing, and, in a companion paper, comparing the C-Q behavior of a suite of major and trace elements in the Madre de Dios River system.

  11. An auxiliary optimization method for complex public transit route network based on link prediction

    Science.gov (United States)

    Zhang, Lin; Lu, Jian; Yue, Xianfei; Zhou, Jialin; Li, Yunxuan; Wan, Qian

    2018-02-01

    Inspired by the missing (new) link prediction and the spurious existing link identification in link prediction theory, this paper establishes an auxiliary optimization method for public transit route network (PTRN) based on link prediction. First, link prediction applied to PTRN is described, and based on reviewing the previous studies, the summary indices set and its algorithms set are collected for the link prediction experiment. Second, through analyzing the topological properties of Jinan’s PTRN established by the Space R method, we found that this is a typical small-world network with a relatively large average clustering coefficient. This phenomenon indicates that the structural similarity-based link prediction will show a good performance in this network. Then, based on the link prediction experiment of the summary indices set, three indices with maximum accuracy are selected for auxiliary optimization of Jinan’s PTRN. Furthermore, these link prediction results show that the overall layout of Jinan’s PTRN is stable and orderly, except for a partial area that requires optimization and reconstruction. The above pattern conforms to the general pattern of the optimal development stage of PTRN in China. Finally, based on the missing (new) link prediction and the spurious existing link identification, we propose optimization schemes that can be used not only to optimize current PTRN but also to evaluate PTRN planning.

  12. Predicting the Disorder–Order Transition of Solvent-Free Nanoparticle–Organic Hybrid Materials

    KAUST Repository

    Yu, Hsiu-Yu

    2013-07-02

    The transition from a disordered to a face-centered-cubic phase in solvent-free oligomer-tethered nanoparticles is predicted using a density-functional theory for model hard spheres with tethered bead-spring oligomers. The transition occurs without a difference of volume fraction for the two phases, and the phase boundary is influenced by the loss of oligomer configurational entropy relative to an ideal random system in one phase compared with the other. When the particles are localized in the ordered phase, the cooperation of the oligomers in filling the space is hindered. Therefore, shorter oligomers feel a stronger entropic penalty in the ordered solid and favor the disordered phase. Strikingly, we found that the solvent-free system has a later transition than hard spheres for all investigated ratios of oligomer radius of gyration to particle radius. © 2013 American Chemical Society.

  13. Prediction of pressure induced structural phase transitions and internal mode frequency changes in solid N2+

    International Nuclear Information System (INIS)

    Etters, R.D.; Kobashi, K.; Chandrasekharan, V.

    1983-01-01

    A rhombohedral distortion of the Pm3n structure is introduced which shows that a low temperature phase transition occurs from P4 2 /mnm into the R3c calcite structure at P approx. = 19.2 kbar with a volume change of 0.125 cm 3 /mole. This transition agrees with recent Raman scattering measurements. Another transition from R3c into R3m is predicted at P approx. = 67.5 kbar, with a volume change of 0.1 cm 3 /mole. The pressure dependence of the intramolecular mode frequencies for the R3c structure is in reasonably good agreement with the two main branches observed experimentally

  14. Prediction of the oscillator strengths for the electric dipole transitions in Th II

    Energy Technology Data Exchange (ETDEWEB)

    Dembczynski, Jerzy [Institute of Control and Information Engineering, Faculty of Electrical Engineering, Poznan University of Technology, Piotrowo 3A, 60-965 Poznan (Poland); Ruczkowski, Jaroslaw; Elantkowska, Magdalena [Laboratory of Quantum Engineering and Metrology, Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13B, 60-965 Poznan (Poland)

    2014-07-01

    In order to parametrize the oscillator strength, the matrix of angular coefficients of the possible transitions in multiconfiguration system were calculated. In the odd and even configuration systems, the fine structure eigenvectors for both parities were obtained, using our semiempirical method, which taken into account also the second order effects, resulting from the excitations from electronic closed shells to open shells and from open shells to empty shell. The correctness of the fine structure wave functions was verified by the comparison of calculated and experimental hyperfine structure constants for Th II available in the literature. The least square fit to experimental values for some transitions allow to obtain the values of radial parameters and predict the oscillator strengths values for all possible transitions from the levels under consideration. These calculations are necessary for the design of the nuclear frequency standard based on the thorium ion.

  15. Packet Tracer network simulator

    CERN Document Server

    Jesin, A

    2014-01-01

    A practical, fast-paced guide that gives you all the information you need to successfully create networks and simulate them using Packet Tracer.Packet Tracer Network Simulator is aimed at students, instructors, and network administrators who wish to use this simulator to learn how to perform networking instead of investing in expensive, specialized hardware. This book assumes that you have a good amount of Cisco networking knowledge, and it will focus more on Packet Tracer rather than networking.

  16. Resistive transition for two-dimensional superconductors: Comparison between experiments and Coulomb-gas-model predictions

    International Nuclear Information System (INIS)

    Minnhagen, P.

    1983-01-01

    The Coulomb-gas model of vortex fluctuations leads to scaling relations for the resistive transition which can be directly tested by experiments. By analyzing published resistance data, it is shown that there is experimental evidence for the Coulomb-gas scaling relation in the absence of a perpendicular magnetic field. It is also shown that there exists some suggestive support for the Coulomb-gas predictions in the presence of a magnetic field

  17. Predicting critical transitions in dynamical systems from time series using nonstationary probability density modeling.

    Science.gov (United States)

    Kwasniok, Frank

    2013-11-01

    A time series analysis method for predicting the probability density of a dynamical system is proposed. A nonstationary parametric model of the probability density is estimated from data within a maximum likelihood framework and then extrapolated to forecast the future probability density and explore the system for critical transitions or tipping points. A full systematic account of parameter uncertainty is taken. The technique is generic, independent of the underlying dynamics of the system. The method is verified on simulated data and then applied to prediction of Arctic sea-ice extent.

  18. Prediction of wall shear stresses in transitional boundary layers using near-wall mean velocity profiles

    International Nuclear Information System (INIS)

    Jeon, Woo Pyung; Shin, Sung Ho; Kang, Shin Hyoung

    2000-01-01

    The local wall shear stress in transitional boundary layer was estimated from the near-wall mean velocity data using the principle of Computational Preston tube Method(CPM). The previous DNS and experimental databases of transitional boundary layers were used to demonstrate the accuracy of the method and to provide the applicable range of wall unit y + . The skin friction coefficients predicted by the CPM agreed well with those from previous studies. To reexamine the applicability of the CPM, near-wall hot-wire measurements were conducted in developing transitional boundary layers on a flat plate with different freestream turbulence intensities. The intermittency profiles across the transitional boundary layers were reasonably obtained from the conditional sampling technique. An empirical correlation between the representative intermittency near the wall and the free parameter K 1 of the extended wall function of CPM has been newly proposed using the present and other experimental data. The CPM has been verified as a useful tool to measure the wall shear stress in transitional boundary layer with reasonable accuracy

  19. Characterization of the glass transition of water predicted by molecular dynamics simulations using nonpolarizable intermolecular potentials.

    Science.gov (United States)

    Kreck, Cara A; Mancera, Ricardo L

    2014-02-20

    Molecular dynamics simulations allow detailed study of the experimentally inaccessible liquid state of supercooled water below its homogeneous nucleation temperature and the characterization of the glass transition. Simple, nonpolarizable intermolecular potentials are commonly used in classical molecular dynamics simulations of water and aqueous systems due to their lower computational cost and their ability to reproduce a wide range of properties. Because the quality of these predictions varies between the potentials, the predicted glass transition of water is likely to be influenced by the choice of potential. We have thus conducted an extensive comparative investigation of various three-, four-, five-, and six-point water potentials in both the NPT and NVT ensembles. The T(g) predicted from NPT simulations is strongly correlated with the temperature of minimum density, whereas the maximum in the heat capacity plot corresponds to the minimum in the thermal expansion coefficient. In the NVT ensemble, these points are instead related to the maximum in the internal pressure and the minimum of its derivative, respectively. A detailed analysis of the hydrogen-bonding properties at the glass transition reveals that the extent of hydrogen-bonds lost upon the melting of the glassy state is related to the height of the heat capacity peak and varies between water potentials.

  20. Effects of the infectious period distribution on predicted transitions in childhood disease dynamics.

    Science.gov (United States)

    Krylova, Olga; Earn, David J D

    2013-07-06

    The population dynamics of infectious diseases occasionally undergo rapid qualitative changes, such as transitions from annual to biennial cycles or to irregular dynamics. Previous work, based on the standard seasonally forced 'susceptible-exposed-infectious-removed' (SEIR) model has found that transitions in the dynamics of many childhood diseases result from bifurcations induced by slow changes in birth and vaccination rates. However, the standard SEIR formulation assumes that the stage durations (latent and infectious periods) are exponentially distributed, whereas real distributions are narrower and centred around the mean. Much recent work has indicated that realistically distributed stage durations strongly affect the dynamical structure of seasonally forced epidemic models. We investigate whether inferences drawn from previous analyses of transitions in patterns of measles dynamics are robust to the shapes of the stage duration distributions. As an illustrative example, we analyse measles dynamics in New York City from 1928 to 1972. We find that with a fixed mean infectious period in the susceptible-infectious-removed (SIR) model, the dynamical structure and predicted transitions vary substantially as a function of the shape of the infectious period distribution. By contrast, with fixed mean latent and infectious periods in the SEIR model, the shapes of the stage duration distributions have a less dramatic effect on model dynamical structure and predicted transitions. All these results can be understood more easily by considering the distribution of the disease generation time as opposed to the distributions of individual disease stages. Numerical bifurcation analysis reveals that for a given mean generation time the dynamics of the SIR and SEIR models for measles are nearly equivalent and are insensitive to the shapes of the disease stage distributions.

  1. Hard-Wired Dopant Networks and the Prediction of High Transition Temperatures in Ceramic Superconductors

    International Nuclear Information System (INIS)

    Phillips, J.C.

    2010-01-01

    The review multiple successes of the discrete hard-wired dopant network model ZZIP, and comment on the equally numerous failures of continuum models, in describing and predicting the properties of ceramic superconductors. The prediction of transition temperatures can be regarded in several ways, either as an exacting test of theory, or as a tool for identifying theoretical rules for defining new homology models. Popular first principle methods for predicting transition temperatures in conventional crystalline superconductors have failed for cuprate HTSC, as have parameterized models based on CuO2 planes (with or without apical oxygen). Following a path suggested by Bayesian probability, it was found that the glassy, self-organized dopant network percolative model is so successful that it defines a new homology class appropriate to ceramic superconductors. The reasons for this success in an exponentially complex (non-polynomial complete, NPC) problem are discussed, and a critical comparison is made with previous polynomial (PC) theories. The predictions are successful for the superfamily of all ceramics, including new non-cuprates based on FeAs in place of CuO2.

  2. Transitioning to adolescence: how changes in child personality and overreactive parenting predict adolescent adjustment problems.

    Science.gov (United States)

    van den Akker, Alithe L; Deković, Maja; Prinzie, Peter

    2010-01-01

    The present study examined how changes in child Big Five personality characteristics and overreactive parenting during the transition from childhood to adolescence predict adolescent adjustment problems. The sample included 290 children, aged 8-9 years. At three moments, with 2-year intervals, mothers, fathers, and a teacher reported on the child's personality, and mothers and fathers reported on their parenting behavior. At the third measurement moment, mothers, fathers, and children reported on the child's adjustment problems. Rank-order stability of the personality dimensions and overreactive parenting were high. Univariate latent growth models revealed mean-level decreases for extraversion, conscientiousness, and imagination. Mean levels of benevolence, emotional stability, and overreactive parenting were stable. Multivariate latent growth models revealed that decreases in extraversion and emotional stability predicted internalizing problems, whereas decreases in benevolence, conscientiousness, and emotional stability predicted externalizing problems. Increases in overreactive parenting predicted externalizing, but not internalizing problems. The associations were similar for boys and girls. The results indicate that changes in child personality and overreactive parenting during the transition to adolescence are associated with adolescent adjustment problems. Overall, child personality was more important than overreactive parenting, and children were more likely to "act out" than to "withdraw" in reaction to overreactive parenting.

  3. Using Combined Computational Techniques to Predict the Glass Transition Temperatures of Aromatic Polybenzoxazines

    Science.gov (United States)

    Mhlanga, Phumzile; Wan Hassan, Wan Aminah; Hamerton, Ian; Howlin, Brendan J.

    2013-01-01

    The Molecular Operating Environment software (MOE) is used to construct a series of benzoxazine monomers for which a variety of parameters relating to the structures (e.g. water accessible surface area, negative van der Waals surface area, hydrophobic volume and the sum of atomic polarizabilities, etc.) are obtained and quantitative structure property relationships (QSPR) models are formulated. Three QSPR models (formulated using up to 5 descriptors) are first used to make predictions for the initiator data set (n = 9) and compared to published thermal data; in all of the QSPR models there is a high level of agreement between the actual data and the predicted data (within 0.63–1.86 K of the entire dataset). The water accessible surface area is found to be the most important descriptor in the prediction of Tg. Molecular modelling simulations of the benzoxazine polymer (minus initiator) carried out at the same time using the Materials Studio software suite provide an independent prediction of Tg. Predicted Tg values from molecular modelling fall in the middle of the range of the experimentally determined Tg values, indicating that the structure of the network is influenced by the nature of the initiator used. Hence both techniques can provide predictions of glass transition temperatures and provide complementary data for polymer design. PMID:23326419

  4. Using combined computational techniques to predict the glass transition temperatures of aromatic polybenzoxazines.

    Directory of Open Access Journals (Sweden)

    Phumzile Mhlanga

    Full Text Available The Molecular Operating Environment software (MOE is used to construct a series of benzoxazine monomers for which a variety of parameters relating to the structures (e.g. water accessible surface area, negative van der Waals surface area, hydrophobic volume and the sum of atomic polarizabilities, etc. are obtained and quantitative structure property relationships (QSPR models are formulated. Three QSPR models (formulated using up to 5 descriptors are first used to make predictions for the initiator data set (n = 9 and compared to published thermal data; in all of the QSPR models there is a high level of agreement between the actual data and the predicted data (within 0.63-1.86 K of the entire dataset. The water accessible surface area is found to be the most important descriptor in the prediction of T(g. Molecular modelling simulations of the benzoxazine polymer (minus initiator carried out at the same time using the Materials Studio software suite provide an independent prediction of T(g. Predicted T(g values from molecular modelling fall in the middle of the range of the experimentally determined T(g values, indicating that the structure of the network is influenced by the nature of the initiator used. Hence both techniques can provide predictions of glass transition temperatures and provide complementary data for polymer design.

  5. Systematic prediction of high-pressure melting curves of transition metals

    International Nuclear Information System (INIS)

    Hieu, Ho Khac

    2014-01-01

    The pressure effects on melting temperatures of transition metals have been studied based on the combination of the modified Lindemann criterion with statistical moment method in quantum statistical mechanics. Numerical calculations have been performed for five transition metals including Cu, Pd, Pt, Ni, and Mn up to pressure 100 GPa. Our results are in good and reasonable agreements with available experimental data. This approach gives us a relatively simple method for qualitatively calculating high-pressure melting temperature. Moreover, it can be used to verify future experimental and theoretical works. This research proposes the potential of the combination of statistical moment method and the modified Lindemann criterion on predicting high-pressure melting of materials.

  6. TRANSIT

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. TRANSIT. SYSTEM: DETERMINE 2D-POSITION GLOBALLY BUT INTERMITTENT (POST-FACTO). IMPROVED ACCURACY. PRINCIPLE: POLAR SATELLITES WITH INNOVATIONS OF: GRAVITY-GRADIENT ATTITUDE CONTROL; DRAG COMPENSATION. WORKS ...

  7. A longitudinal examination of factors predicting anxiety during the transition to middle school

    Science.gov (United States)

    Grills-Taquechel, Amie E.; Norton, Peter; Ollendick, Thomas H.

    2010-01-01

    The transition from elementary to middle or junior high school is commonly regarded as a period of stress and turmoil for young adolescents, and has been associated with changes in anxiety and other psychological problems. However, less is known about risk and resilience factors that may predict these changes. This study examined changes in anxiety, as well as predictors of these changes among 77, predominantly Caucasian (88%), male and female (52%) adolescents from Grades 6 to 8. Repeated measures analysis of variance was conducted to examine the predicted grade and gender differences. Multiple regression analyses were conducted to examine the prediction of eighth grade anxiety symptoms by sixth grade self-worth, perceived social acceptance, and social support, as well as the potential moderating role of gender in these relations. Results suggested a significant decrease in anxiety, particularly social anxiety, over this period for boys but not girls. Examination of predictors of changes in anxiety suggested that, in general, global self-worth, social acceptance, and gender were each associated with overall and social anxiety. Findings are integrated with extant literature on developmental changes associated with anxiety and school transitions and clinical implications of these findings are discussed. PMID:20711893

  8. Tracer attenuation in groundwater

    Science.gov (United States)

    Cvetkovic, Vladimir

    2011-12-01

    The self-purifying capacity of aquifers strongly depends on the attenuation of waterborne contaminants, i.e., irreversible loss of contaminant mass on a given scale as a result of coupled transport and transformation processes. A general formulation of tracer attenuation in groundwater is presented. Basic sensitivities of attenuation to macrodispersion and retention are illustrated for a few typical retention mechanisms. Tracer recovery is suggested as an experimental proxy for attenuation. Unique experimental data of tracer recovery in crystalline rock compare favorably with the theoretical model that is based on diffusion-controlled retention. Non-Fickian hydrodynamic transport has potentially a large impact on field-scale attenuation of dissolved contaminants.

  9. Isotopic marking and tracers

    International Nuclear Information System (INIS)

    Morel, F.

    1997-01-01

    The use of radioactive isotopes as tracers in biology has been developed thanks to the economic generation of the required isotopes in accelerators and nuclear reactors, and to the multiple applications of tracers in the life domain; the most usual isotopes employed in biology are carbon, hydrogen, phosphorus and sulfur isotopes, because these elements are present in most of organic molecules. Most of the life science knowledge appears to be dependent to the extensive use of nuclear tools and radioactive tracers; the example of the utilization of radioactive phosphorus marked ATP to study the multiple reactions with proteins, nucleic acids, etc., is given

  10. Suitability of tracers

    International Nuclear Information System (INIS)

    Klotz, D.

    1999-01-01

    Hydrological tracer techniques are a means of making statements on the direction and speed of underground water. One of the simpler tasks is to find out whether there is hydrological communication between two given points. This requires a determination of the direction of flow, which places less exacting demands on the properties of the tracer than does the task of determining the flow velocity of underground water. Tracer methods can serve to infer from flow velocity the distance (flow) velocity, which is defined as the ratio between the distance between two points located in flow direction and the actual time it takes water to flow from one to the other [de

  11. Location Prediction Based on Transition Probability Matrices Constructing from Sequential Rules for Spatial-Temporal K-Anonymity Dataset

    Science.gov (United States)

    Liu, Zhao; Zhu, Yunhong; Wu, Chenxue

    2016-01-01

    Spatial-temporal k-anonymity has become a mainstream approach among techniques for protection of users’ privacy in location-based services (LBS) applications, and has been applied to several variants such as LBS snapshot queries and continuous queries. Analyzing large-scale spatial-temporal anonymity sets may benefit several LBS applications. In this paper, we propose two location prediction methods based on transition probability matrices constructing from sequential rules for spatial-temporal k-anonymity dataset. First, we define single-step sequential rules mined from sequential spatial-temporal k-anonymity datasets generated from continuous LBS queries for multiple users. We then construct transition probability matrices from mined single-step sequential rules, and normalize the transition probabilities in the transition matrices. Next, we regard a mobility model for an LBS requester as a stationary stochastic process and compute the n-step transition probability matrices by raising the normalized transition probability matrices to the power n. Furthermore, we propose two location prediction methods: rough prediction and accurate prediction. The former achieves the probabilities of arriving at target locations along simple paths those include only current locations, target locations and transition steps. By iteratively combining the probabilities for simple paths with n steps and the probabilities for detailed paths with n-1 steps, the latter method calculates transition probabilities for detailed paths with n steps from current locations to target locations. Finally, we conduct extensive experiments, and correctness and flexibility of our proposed algorithm have been verified. PMID:27508502

  12. Acute Pancreatitis as a Model to Predict Transition of Systemic Inflammation to Organ Failure in Trauma and Critical Illness

    Science.gov (United States)

    2017-10-01

    models ); • clinical interventions; • new business creation; and • other. Nothing to report. Nothing to report. Nothing to report. 17...AWARD NUMBER: W81XWH-14-1-0376 TITLE: Acute Pancreatitis as a Model to Predict Transition of Systemic Inflammation to Organ Failgure in Trauma...COVERED 22 Sep 2016 - 21 Sep 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Acute Pancreatitis as a Model to Predict Transition of Systemic

  13. Stability theory and transition prediction applied to a general aviation fuselage

    Science.gov (United States)

    Spall, R. E.; Wie, Y.-S.

    1993-01-01

    The linear stability of a fully three-dimensional boundary layer formed over a general aviation fuselage was investigated. The location of the onset of transition was estimated using the N-factor method. The results were compared with existing experimental data and indicate N-factors of approximately 8.5 on the side of the fuselage and 3.0 near the top. Considerable crossflow existed along the side of the body, which significantly affected the unstable modes present in the boundary layer. Fair agreement was found between the predicted frequency range of linear instability modes and available experimental data concerning the spectral content of the boundary layer.

  14. Tracers Detect Aquifer Contamination

    National Research Council Canada - National Science Library

    Enfield, Carl

    1995-01-01

    The EPA's National Laboratory (NRMRL) at Ada, OK, along with the University of Florida and the University of Texas, have developed a tracer procedure to detect the amount of contamination in aquifer formations...

  15. Radio-isotopic tracers

    International Nuclear Information System (INIS)

    Wolfangel, R.G.

    1976-01-01

    The invention concerns the dispersions that may be used for preparing radio-isotopic tracers, technetium labelled dispersions, processes for preparing these dispersions and their use as tracers. Technetium 99m sulphur colloids are utilized as scintillation tracers to give a picture of the reticulo-endothelial system, particularly the liver and spleen. A dispersion is provided which only requires the addition of a radioactive nuclide to form a radioactively labelled dispersion that can be injected as a tracer. It is formed of a colloid of tin sulphur dispersed in an aqueous buffer solution. Such a reagent has the advantage of being safe and reliable and is easier to use. The colloid can be prepared more quickly since additions of several different reagents are avoided. There is no need to heat up and no sulphuretted hydrogen, which is a toxic gas, is used [fr

  16. Hybrid system prediction for the stock market: The case of transitional markets

    Directory of Open Access Journals (Sweden)

    Ralević Nebojša

    2017-01-01

    Full Text Available The subject of this paper is the creation and testing of an enhanced fuzzy neural network backpropagation model for the prediction of stock market indexes, including the comparison with the traditional neural network backpropagation model. The objective of the research is to gather information concerning the possibilities of using the enhanced fuzzy neural network backpropagation model for the prediction of stock market indexes focusing on transitional markets. The methodology used involves the integration of fuzzified weights into the neural network. The research results will be beneficial both for the broader investment community and the academia, in terms of the application of the enhanced model in the investment decision-making, as well as in improving the knowledge in this subject matter.

  17. Tracer techniques in microelectronics

    International Nuclear Information System (INIS)

    Flachowsky, J.; Freyer, K.

    1981-01-01

    Tracer technique and neutron activation analysis are capable of measuring impurities in semiconductor material or on the semiconductor surface in a very low concentration range. The methods, combined with autoradiography, are also suitable to determine dopant distributions in silicon. However, both techniques suffer from certain inherent experimental difficulties and/or limitations which are discussed. Methods of tracer technique practicable in the semiconductor field are described. (author)

  18. Prediction of monomer reactivity in radical copolymerizations from transition state quantum chemical descriptors

    Directory of Open Access Journals (Sweden)

    Zhengde Tan

    2013-01-01

    Full Text Available In comparison with the Q-e scheme, the Revised Patterns Scheme: the U, V Version (the U-V scheme has greatly improved both its accessibility and its accuracy in interpreting and predicting the reactivity of a monomer in free-radical copolymerizations. Quantitative structure-activity relationship (QSAR models were developed to predict the reactivity parameters u and v of the U-V scheme, by applying genetic algorithm (GA and support vector machine (SVM techniques. Quantum chemical descriptors used for QSAR models were calculated from transition state species with structures C¹H3 - C²HR³• or •C¹H2 - C²H2R³ (formed from vinyl monomers C¹H²=C²HR³ + H•, using density functional theory (DFT, at the UB3LYP level of theory with 6-31G(d basis set. The optimum support vector regression (SVR model of the reactivity parameter u based on Gaussian radial basis function (RBF kernel (C = 10, ε = 10- 5 and γ = 1.0 produced root-mean-square (rms errors for the training, validation and prediction sets being 0.220, 0.326 and 0.345, respectively. The optimal SVR model for v with the RBF kernel (C = 20, ε = 10- 4 and γ = 1.2 produced rms errors for the training set of 0.123, the validation set of 0.206 and the prediction set of 0.238. The feasibility of applying the transition state quantum chemical descriptors to develop SVM models for reactivity parameters u and v in the U-V scheme has been demonstrated.

  19. Tracers and tracing methods

    International Nuclear Information System (INIS)

    Leclerc, J.P.

    2001-01-01

    The first international congress on 'Tracers and tracing methods' took place in Nancy in May 2001. The objective of this second congress was to present the current status and trends on tracing methods and their applications. It has given the opportunity to people from different fields to exchange scientific information and knowledge about tracer methodologies and applications. The target participants were the researchers, engineers and technologists of various industrial and research sectors: chemical engineering, environment, food engineering, bio-engineering, geology, hydrology, civil engineering, iron and steel production... Two sessions have been planned to cover both fundamental and industrial aspects: 1)fundamental development (tomography, tracer camera visualization and particles tracking; validation of computational fluid dynamics simulations by tracer experiments and numerical residence time distribution; new tracers and detectors or improvement and development of existing tracing methods; data treatments and modeling; reactive tracer experiments and interpretation) 2)industrial applications (geology, hydrogeology and oil field applications; civil engineering, mineral engineering and metallurgy applications; chemical engineering; environment; food engineering and bio-engineering). The program included 5 plenary lectures, 23 oral communications and around 50 posters. Only 9 presentations are interested for the INIS database

  20. A Predictive Metabolic Signature for the Transition From Gestational Diabetes Mellitus to Type 2 Diabetes.

    Science.gov (United States)

    Allalou, Amina; Nalla, Amarnadh; Prentice, Kacey J; Liu, Ying; Zhang, Ming; Dai, Feihan F; Ning, Xian; Osborne, Lucy R; Cox, Brian J; Gunderson, Erica P; Wheeler, Michael B

    2016-09-01

    Gestational diabetes mellitus (GDM) affects 3-14% of pregnancies, with 20-50% of these women progressing to type 2 diabetes (T2D) within 5 years. This study sought to develop a metabolomics signature to predict the transition from GDM to T2D. A prospective cohort of 1,035 women with GDM pregnancy were enrolled at 6-9 weeks postpartum (baseline) and were screened for T2D annually for 2 years. Of 1,010 women without T2D at baseline, 113 progressed to T2D within 2 years. T2D developed in another 17 women between 2 and 4 years. A nested case-control design used 122 incident case patients matched to non-case patients by age, prepregnancy BMI, and race/ethnicity. We conducted metabolomics with baseline fasting plasma and identified 21 metabolites that significantly differed by incident T2D status. Machine learning optimization resulted in a decision tree modeling that predicted T2D incidence with a discriminative power of 83.0% in the training set and 76.9% in an independent testing set, which is far superior to measuring fasting plasma glucose levels alone. The American Diabetes Association recommends T2D screening in the early postpartum period via oral glucose tolerance testing after GDM, which is a time-consuming and inconvenient procedure. Our metabolomics signature predicted T2D incidence from a single fasting blood sample. This study represents the first metabolomics study of the transition from GDM to T2D validated in an independent testing set, facilitating early interventions. © 2016 by the American Diabetes Association.

  1. Financial Distress Prediction Using Discrete-time Hazard Model and Rating Transition Matrix Approach

    Science.gov (United States)

    Tsai, Bi-Huei; Chang, Chih-Huei

    2009-08-01

    Previous studies used constant cut-off indicator to distinguish distressed firms from non-distressed ones in the one-stage prediction models. However, distressed cut-off indicator must shift according to economic prosperity, rather than remains fixed all the time. This study focuses on Taiwanese listed firms and develops financial distress prediction models based upon the two-stage method. First, this study employs the firm-specific financial ratio and market factors to measure the probability of financial distress based on the discrete-time hazard models. Second, this paper further focuses on macroeconomic factors and applies rating transition matrix approach to determine the distressed cut-off indicator. The prediction models are developed by using the training sample from 1987 to 2004, and their levels of accuracy are compared with the test sample from 2005 to 2007. As for the one-stage prediction model, the model in incorporation with macroeconomic factors does not perform better than that without macroeconomic factors. This suggests that the accuracy is not improved for one-stage models which pool the firm-specific and macroeconomic factors together. In regards to the two stage models, the negative credit cycle index implies the worse economic status during the test period, so the distressed cut-off point is adjusted to increase based on such negative credit cycle index. After the two-stage models employ such adjusted cut-off point to discriminate the distressed firms from non-distressed ones, their error of misclassification becomes lower than that of one-stage ones. The two-stage models presented in this paper have incremental usefulness in predicting financial distress.

  2. Tracer dispersion in planar multipole flows

    International Nuclear Information System (INIS)

    Koplik, J.; Redner, S.; Hinch, E.J.

    1994-01-01

    We study the motion of passive Brownian tracer particles in steady two-dimensional potential flows between sources and sinks. Our primary focus is understanding the long-time properties of the transit time probability distribution for the tracer to reach the sink p(t) and the influence of the flow geometry on this probability. A variety of illustrative case studies is considered. For radial potential flow in an annular region, competition between convection and diffusion leads to nonuniversal decay of the transit time probability. Dipolar and higher multipole flows are found to exhibit generic features, such as a power-law decay in p(t) with an exponent determined by the multipole moment, an exponential cutoff related to stagnation points, and a ''shoulder'' in p(t) that is related to reflection from the system boundaries. For spatially extended sinks, it is also shown that the spatial distribution of the collected tracer is independent of the overall magnitude of the flow field and that p(t) decays as a power law with a geometry-dependent exponent. Our results may offer the possibility of using tracer measurements to characterize the flow geometry of porous media

  3. Role of Transition Zone Index in the Prediction of Clinical Benign Prostatic Hyperplasia

    Directory of Open Access Journals (Sweden)

    Muhammet Güzelsoy

    2016-12-01

    Full Text Available Objective The objective of this study was to determine the role of the transition zone (TZ index (TZI in the prediction of clinical benign prostatic hyperplasia (BPH in patients who underwent transurethral prostatectomy (TUR-P and to analyze the correlation between the amount of resected tissue and TZ volume (TZV. Materials and Methods Twenty-six male clinical BPH patients with obstructive complaints and 17 male benign prostate enlargement (BPE patients without any complaints were included in the study. Both the groups were over the age of 50. Clinical BPH patients underwent complete TUR-P. Statistical analysis was done with SPSS. Sensitivity, specificity, positive and negative predictive values of TZI-as a method of assessing clinical BPH-were measured. Results There was a statistically significant difference in prostate volume, uroflowmetry patterns, prostate-specific antigen (PSA, International prostate symptom score (IPSS, TZV and TZI between the two groups. There was a correlation between TZV and the amount of resected tissue (r=0.97; p0.40 has a high level of sensitivity and specificity in the prediction of clinical BPH among patients who undergo TUR-P due to obstructive symptoms and reported as BPH. There is a strong correlation between the amount of resected tissue and TZV. TZI is a valuable tool in diagnosis, and TZV gives valuable information about the patient to the surgeon.

  4. Wairakei tracer tests 1983

    International Nuclear Information System (INIS)

    McCabe, W.J.; Barry, B.J.

    1984-05-01

    Tracer tests, with and without, hot water reinjection into WK213 showed returns of tracer iodine-131; in wells in both the Waiora Valley and the eastern end of the field. The effect of reinjection at a rate of 200 cu. m/h was to reduce the arrived time from 15 to 7 days. Increasing the rate of reinjection into WK62 from 30 cu. m/h to 200 cu. m/h seemed to increase the initial velocity of the tracer wave and the distance it moved. However, returns were recorded only in the adjacent wells WK61 and WK63 with a very small, and three days delayed, response in WK43

  5. Transition point prediction in a multicomponent lattice Boltzmann model: Forcing scheme dependencies

    Science.gov (United States)

    Küllmer, Knut; Krämer, Andreas; Joppich, Wolfgang; Reith, Dirk; Foysi, Holger

    2018-02-01

    Pseudopotential-based lattice Boltzmann models are widely used for numerical simulations of multiphase flows. In the special case of multicomponent systems, the overall dynamics are characterized by the conservation equations for mass and momentum as well as an additional advection diffusion equation for each component. In the present study, we investigate how the latter is affected by the forcing scheme, i.e., by the way the underlying interparticle forces are incorporated into the lattice Boltzmann equation. By comparing two model formulations for pure multicomponent systems, namely the standard model [X. Shan and G. D. Doolen, J. Stat. Phys. 81, 379 (1995), 10.1007/BF02179985] and the explicit forcing model [M. L. Porter et al., Phys. Rev. E 86, 036701 (2012), 10.1103/PhysRevE.86.036701], we reveal that the diffusion characteristics drastically change. We derive a generalized, potential function-dependent expression for the transition point from the miscible to the immiscible regime and demonstrate that it is shifted between the models. The theoretical predictions for both the transition point and the mutual diffusion coefficient are validated in simulations of static droplets and decaying sinusoidal concentration waves, respectively. To show the universality of our analysis, two common and one new potential function are investigated. As the shift in the diffusion characteristics directly affects the interfacial properties, we additionally show that phenomena related to the interfacial tension such as the modeling of contact angles are influenced as well.

  6. First-Principles Petascale Simulations for Predicting Deflagration to Detonation Transition in Hydrogen-Oxygen Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Khokhlov, Alexei [Univ. of Chicago, IL (United States). Dept. of Astronomy and Astrophysics. Enrico Fermi Inst.; Austin, Joanna [Argonne National Lab. (ANL), Argonne, IL (United States). Argonne Leadership Computing Facility; Bacon, C. [Univ. of Illinois, Urbana, IL (United States). Dept. of Aerospace Engineering

    2015-03-02

    Hydrogen has emerged as an important fuel across a range of industries as a means of achieving energy independence and to reduce emissions. DDT and the resulting detonation waves in hydrogen-oxygen can have especially catastrophic consequences in a variety of industrial and energy producing settings related to hydrogen. First-principles numerical simulations of flame acceleration and DDT are required for an in-depth understanding of the phenomena and facilitating design of safe hydrogen systems. The goals of this project were (1) to develop first-principles petascale reactive flow Navier-Stokes simulation code for predicting gaseous high-speed combustion and detonation (HSCD) phenomena and (2) demonstrate feasibility of first-principles simulations of rapid flame acceleration and deflagration-to-detonation transition (DDT) in stoichiometric hydrogen-oxygen mixture (2H2 + O2). The goals of the project have been accomplished. We have developed a novel numerical simulation code, named HSCD, for performing first-principles direct numerical simulations of high-speed hydrogen combustion. We carried out a series of validating numerical simulations of inert and reactive shock reflection experiments in shock tubes. We then performed a pilot numerical simulation of flame acceleration in a long pipe. The simulation showed the transition of the rapidly accelerating flame into a detonation. The DDT simulations were performed using BG/Q Mira at the Argonne National Laboratory, currently the fourth fastest super-computer in the world.

  7. Transition point prediction in a multicomponent lattice Boltzmann model: Forcing scheme dependencies.

    Science.gov (United States)

    Küllmer, Knut; Krämer, Andreas; Joppich, Wolfgang; Reith, Dirk; Foysi, Holger

    2018-02-01

    Pseudopotential-based lattice Boltzmann models are widely used for numerical simulations of multiphase flows. In the special case of multicomponent systems, the overall dynamics are characterized by the conservation equations for mass and momentum as well as an additional advection diffusion equation for each component. In the present study, we investigate how the latter is affected by the forcing scheme, i.e., by the way the underlying interparticle forces are incorporated into the lattice Boltzmann equation. By comparing two model formulations for pure multicomponent systems, namely the standard model [X. Shan and G. D. Doolen, J. Stat. Phys. 81, 379 (1995)JSTPBS0022-471510.1007/BF02179985] and the explicit forcing model [M. L. Porter et al., Phys. Rev. E 86, 036701 (2012)PLEEE81539-375510.1103/PhysRevE.86.036701], we reveal that the diffusion characteristics drastically change. We derive a generalized, potential function-dependent expression for the transition point from the miscible to the immiscible regime and demonstrate that it is shifted between the models. The theoretical predictions for both the transition point and the mutual diffusion coefficient are validated in simulations of static droplets and decaying sinusoidal concentration waves, respectively. To show the universality of our analysis, two common and one new potential function are investigated. As the shift in the diffusion characteristics directly affects the interfacial properties, we additionally show that phenomena related to the interfacial tension such as the modeling of contact angles are influenced as well.

  8. Vulnerability analysis and passenger source prediction in urban rail transit networks.

    Directory of Open Access Journals (Sweden)

    Junjie Wang

    Full Text Available Based on large-scale human mobility data collected in San Francisco and Boston, the morning peak urban rail transit (URT ODs (origin-destination matrix were estimated and the most vulnerable URT segments, those capable of causing the largest service interruptions, were identified. In both URT networks, a few highly vulnerable segments were observed. For this small group of vital segments, the impact of failure must be carefully evaluated. A bipartite URT usage network was developed and used to determine the inherent connections between urban rail transits and their passengers' travel demands. Although passengers' origins and destinations were easy to locate for a large number of URT segments, a few show very complicated spatial distributions. Based on the bipartite URT usage network, a new layer of the understanding of a URT segment's vulnerability can be achieved by taking the difficulty of addressing the failure of a given segment into account. Two proof-of-concept cases are described here: Possible transfer of passenger flow to the road network is here predicted in the cases of failures of two representative URT segments in San Francisco.

  9. A predictive model for steam generator degradation through PW SCC in roll transitions

    International Nuclear Information System (INIS)

    Hernalsteen, P.

    1989-01-01

    The tubebundle of pressurized water reactors steam generators (SG) has been affected by numerous corrosion damages, in various nuclear plants, all over the world. One of the main problems is primary water stress corrosion cracking (PWSCC) in the roll transitions of mill annealed Inconel 600 tubes mechanically expanded in the SG tubesheet. Multiple axial cracks are initiated from the primary side and grow rapidly through water; they further grow in length and propagate outside of the roll transition. In most plants, both in Europe and in the USA, short penning has been performed on the inside diameter of the expanded section of susceptible tubing. While the compressive surface layer induced by peening is considered to be efficient in preventing crack initiation, field experience showed that it did not prevent preexisting cracks from further propagation. For the usual case of SG peened after crack initiation, there is thus a remaining concern about the long term evolution of the population of cracked tubes. This paper presents a model to predict the SG degradation process in order to support both the maintenance policy and the longer term repair/replacement strategy

  10. Hypoxia-induced alteration of tracer accumulation in cultured cancer cells and xenografts in mice: implications for pre-therapeutic prediction of treatment outcomes with 99mTc-sestamibi, 201Tl chloride and 99mTc-HL91

    International Nuclear Information System (INIS)

    Kinuya, Seigo; Yokoyama, Kunihiko; Li, Xiao-Feng; Bai, Jingming; Michigishi, Takatoshi; Tonami, Norihisa; Watanabe, Naoto; Shuke, Noriyuki; Takayama, Teruhiko; Bunko, Hisashi

    2002-01-01

    Weak visualization of tumours in pre-therapeutic scintigrams with technetium-99m sestamibi (MIBI) is likely a predictive sign of unfavourable tumour response to radiotherapy and chemotherapy. However, factors relating to this scintigraphic finding are not well understood. The presence of hypoxic tumour cells is one of the major reasons for therapeutic failure; consequently, we attempted to determine whether oxygenation status affects 99m Tc-MIBI accumulation in tumour cells. LS180 human colon cancer and T24 human bladder cancer cells were incubated in air or N 2 gas at 37 C. Cellular uptake of 99m Tc-MIBI was subsequently determined at 15, 60 and 120 min. Uptake of thallium-201 chloride was also assessed. Uptake of 99m Tc-HL91 was assessed as a hypoxic marker. Accumulation of the tracers in LS180 xenografts was observed in mice treated with 5 mg/kg hydralazine and compared with that in untreated mice. pO 2 in the medium and tumours was measured with O 2 microelectrodes. N 2 gas flow gradually reduced pO 2 in the cell suspension to 1-2 mmHg in 60 min. Cellular uptake of 99m Tc-MIBI in LS180 cells decreased by approximately 30% in N 2 gas in comparison to that in air throughout the study. Hypoxia had a more prominent influence on 201 Tl uptake, which displayed a reduction of approximately 60% in N 2 gas at 120 min, than on 99m Tc-MIBI uptake. On the other hand, N 2 gas induced an increase of 170% in 99m Tc-HL91 uptake at 120 min, indicating the hypoxic condition of cells. The results of in vitro assays employing the T24 cell line were similar to those obtained with the LS180 cell line. Hydralazine treatment markedly reduced 99m Tc-MIBI and 201 Tl accumulation in LS180 xenografts; moreover, intratumoural pO 2 decreased from 14.5±6.6 mmHg to 7.6±6.2 mmHg. 99m Tc-HL91 accumulation in xenografts was markedly increased by hydralazine. In conclusion, hypoxia reduced accumulation of 99m Tc-MIBI and 201 Tl in tumour cells. Accordingly, hypoxia may be an important factor in

  11. Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

    Directory of Open Access Journals (Sweden)

    W.-S. W. DeRieux

    2018-05-01

    Full Text Available Secondary organic aerosol (SOA accounts for a large fraction of submicron particles in the atmosphere. SOA can occur in amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH, and temperature. The phase transition between amorphous solid and semi-solid states occurs at the glass transition temperature (Tg. We have recently developed a method to estimate Tg of pure compounds containing carbon, hydrogen, and oxygen atoms (CHO compounds with molar mass less than 450 g mol−1 based on their molar mass and atomic O : C ratio. In this study, we refine and extend this method for CH and CHO compounds with molar mass up to ∼ 1100 g mol−1 using the number of carbon, hydrogen, and oxygen atoms. We predict viscosity from the Tg-scaled Arrhenius plot of fragility (viscosity vs. Tg∕T as a function of the fragility parameter D. We compiled D values of organic compounds from the literature and found that D approaches a lower limit of ∼ 10 (±1.7 as the molar mass increases. We estimated the viscosity of α-pinene and isoprene SOA as a function of RH by accounting for the hygroscopic growth of SOA and applying the Gordon–Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted to evaluate impacts of Tg, D, the hygroscopicity parameter (κ, and the Gordon–Taylor constant on viscosity predictions. The viscosity of toluene SOA was predicted using the elemental composition obtained by high-resolution mass spectrometry (HRMS, resulting in a good agreement with the measured viscosity. We also estimated the viscosity of biomass burning particles using the chemical composition measured by HRMS with two different ionization techniques: electrospray ionization (ESI and atmospheric pressure photoionization (APPI. Due to differences in detected organic compounds and signal intensity, predicted viscosities at low RH based on ESI and

  12. Identification of predictive biomarkers of disease state in transition dairy cows.

    Science.gov (United States)

    Hailemariam, D; Mandal, R; Saleem, F; Dunn, S M; Wishart, D S; Ametaj, B N

    2014-05-01

    In dairy cows, periparturient disease states, such as metritis, mastitis, and laminitis, are leading to increasingly significant economic losses for the dairy industry. Treatments for these pathologies are often expensive, ineffective, or not cost-efficient, leading to production losses, high veterinary bills, or early culling of the cows. Early diagnosis or detection of these conditions before they manifest themselves could lower their incidence, level of morbidity, and the associated economic losses. In an effort to identify predictive biomarkers for postpartum or periparturient disease states in dairy cows, we undertook a cross-sectional and longitudinal metabolomics study to look at plasma metabolite levels of dairy cows during the transition period, before and after becoming ill with postpartum diseases. Specifically we employed a targeted quantitative metabolomics approach that uses direct flow injection mass spectrometry to track the metabolite changes in 120 different plasma metabolites. Blood plasma samples were collected from 12 dairy cows at 4 time points during the transition period (-4 and -1 wk before and 1 and 4 wk after parturition). Out of the 12 cows studied, 6 developed multiple periparturient disorders in the postcalving period, whereas the other 6 remained healthy during the entire experimental period. Multivariate data analysis (principal component analysis and partial least squares discriminant analysis) revealed a clear separation between healthy controls and diseased cows at all 4 time points. This analysis allowed us to identify several metabolites most responsible for separating the 2 groups, especially before parturition and the start of any postpartum disease. Three metabolites, carnitine, propionyl carnitine, and lysophosphatidylcholine acyl C14:0, were significantly elevated in diseased cows as compared with healthy controls as early as 4 wk before parturition, whereas 2 metabolites, phosphatidylcholine acyl-alkyl C42:4 and

  13. Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

    Science.gov (United States)

    Wong DeRieux, Wing-Sy; Li, Ying; Lin, Peng; Laskin, Julia; Laskin, Alexander; Bertram, Allan K.; Nizkorodov, Sergey A.; Shiraiwa, Manabu

    2018-05-01

    Secondary organic aerosol (SOA) accounts for a large fraction of submicron particles in the atmosphere. SOA can occur in amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH), and temperature. The phase transition between amorphous solid and semi-solid states occurs at the glass transition temperature (Tg). We have recently developed a method to estimate Tg of pure compounds containing carbon, hydrogen, and oxygen atoms (CHO compounds) with molar mass less than 450 g mol-1 based on their molar mass and atomic O : C ratio. In this study, we refine and extend this method for CH and CHO compounds with molar mass up to ˜ 1100 g mol-1 using the number of carbon, hydrogen, and oxygen atoms. We predict viscosity from the Tg-scaled Arrhenius plot of fragility (viscosity vs. Tg/T) as a function of the fragility parameter D. We compiled D values of organic compounds from the literature and found that D approaches a lower limit of ˜ 10 (±1.7) as the molar mass increases. We estimated the viscosity of α-pinene and isoprene SOA as a function of RH by accounting for the hygroscopic growth of SOA and applying the Gordon-Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted to evaluate impacts of Tg, D, the hygroscopicity parameter (κ), and the Gordon-Taylor constant on viscosity predictions. The viscosity of toluene SOA was predicted using the elemental composition obtained by high-resolution mass spectrometry (HRMS), resulting in a good agreement with the measured viscosity. We also estimated the viscosity of biomass burning particles using the chemical composition measured by HRMS with two different ionization techniques: electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Due to differences in detected organic compounds and signal intensity, predicted viscosities at low RH based on ESI and APPI measurements differ by 2-5 orders

  14. Systems approach to tracer data in groundwater hydrology

    International Nuclear Information System (INIS)

    Saxena, R.K.

    1977-01-01

    A brief review of current mathematical methods for the analysis of tracer data in groundwater hydrology has been given. The description of the hydrological cycle as a whole or in part, by a system (compartment) or sub-system under linear and stationary conditions is discussed. Basic concepts of transit time, residence time, their distributions in time and response characteristics of a system are outlined. From the knowledge of tracer input, output and systems response function for a generalised system, reservoir capacity and storage for given period can be estimated. Use of a time series model for environmental tracer data in discreet time scale aimed at the solution of hydrological problems e.g. mean transit time and reservoir capacity is also explored. It is concluded that the combination of tracer data with systems approach can go a long way in the study of some complex hydrological problems. (author)

  15. A molecular dynamics approach for predicting the glass transition temperature and plasticization effect in amorphous pharmaceuticals.

    Science.gov (United States)

    Gupta, Jasmine; Nunes, Cletus; Jonnalagadda, Sriramakamal

    2013-11-04

    The objectives of this study were as follows: (i) To develop an in silico technique, based on molecular dynamics (MD) simulations, to predict glass transition temperatures (Tg) of amorphous pharmaceuticals. (ii) To computationally study the effect of plasticizer on Tg. (iii) To investigate the intermolecular interactions using radial distribution function (RDF). Amorphous sucrose and water were selected as the model compound and plasticizer, respectively. MD simulations were performed using COMPASS force field and isothermal-isobaric ensembles. The specific volumes of amorphous cells were computed in the temperature range of 440-265 K. The characteristic "kink" observed in volume-temperature curves, in conjunction with regression analysis, defined the Tg. The MD computed Tg values were 367 K, 352 K and 343 K for amorphous sucrose containing 0%, 3% and 5% w/w water, respectively. The MD technique thus effectively simulated the plasticization effect of water; and the corresponding Tg values were in reasonable agreement with theoretical models and literature reports. The RDF measurements revealed strong hydrogen bond interactions between sucrose hydroxyl oxygens and water oxygen. Steric effects led to weak interactions between sucrose acetal oxygens and water oxygen. MD is thus a powerful predictive tool for probing temperature and water effects on the stability of amorphous systems during drug development.

  16. Predicting bioactive glass properties from the molecular chemical composition: glass transition temperature.

    Science.gov (United States)

    O'Donnell, Matthew D

    2011-05-01

    The glass transition temperature (T(g)) of inorganic glasses is an important parameter than can be used to correlate with other glass properties, such as dissolution rate, which governs in vitro and in vivo bioactivity. Seven bioactive glass compositional series reported in the literature (77 in total) were analysed here with T(g) values obtained by a number of different methods: differential thermal analysis, differential scanning calorimetry and dilatometry. An iterative least-squares fitting method was used to correlate T(g) from thermal analysis of these compositions with the levels of individual oxide and fluoride components in the glasses. When all seven series were fitted a reasonable correlation was found between calculated and experimental values (R(2)=0.89). When the two compositional series that were designed in weight percentages (the remaining five were designed in molar percentage) were removed from the model an improved fit was achieved (R(2)=0.97). This study shows that T(g) for a wide range in compositions (e.g. SiO(2) content of 37.3-68.4 mol.%) can be predicted to reasonable accuracy enabling processing parameters to be predicted such as annealing, fibre-drawing and sintering temperatures. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Models for tracer flow

    International Nuclear Information System (INIS)

    Zuber, A.

    1983-01-01

    A review and discussion is given of mathematical models used for interpretation of tracer experiments in hydrology. For dispersion model, different initial and boundary conditions are related to different injection and detection modes. Examples of applications of various models are described and commented. (author)

  18. Predictive Validity and Adjustment of Ideal Partner Preferences Across the Transition Into Romantic Relationships.

    Science.gov (United States)

    Gerlach, Tanja M; Arslan, Ruben C; Schultze, Thomas; Reinhard, Selina K; Penke, Lars

    2017-09-18

    Although empirical research has investigated what we ideally seek in a romantic partner for decades, the crucial question of whether ideal partner preferences actually guide our mating decisions in real life has remained largely unanswered. One reason for this is the lack of designs that assess individuals' ideal partner preferences before entering a relationship and then follow up on them over an extended period. In the Göttingen Mate Choice Study (GMCS), a preregistered, large-scale online study, we used such a naturalistic prospective design. We investigated partner preferences across 4 preference domains in a large sample of predominantly heterosexual singles (N = 763, aged 18-40 years) and tracked these individuals across a period of 5 months upon a possible transition into romantic relationships. Attesting to their predictive validity, partner preferences prospectively predicted the characteristics of later partners. This was equally true for both sexes, except for vitality-attractiveness where men's preferences were more predictive of their later partners' standing on this dimension than women's. Self-perceived mate value did not moderate the preference-partner characteristics relations. Preferences proved to be relatively stable across the 5 months interval, yet were less stable for those who entered a relationship. Subgroup analyses using a newly developed indicator of preference adjustment toward (vs. away from) partner characteristics revealed that participants adjusted their preferences downward when partners fell short of initial preferences, but showed no consistent adjustment when partners exceeded them. Results and implications are discussed against the background of ongoing controversies in mate choice and romantic relationship research. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  19. Xanthine tracers and their preparation

    International Nuclear Information System (INIS)

    Groman, E.V.; Cabelli, M.D.

    1980-01-01

    Compounds useful as tracers in the radioimmunoassay of xanthine derivatives such as theophylline and pharmacologically related drugs are described. They are substituted xanthines in which at least one substituted radical contains radioiodine. The tracers are made by linking radioiodinatable or preradioiodinated radicals to the xanthine derivative which is to be assayed. The tracers may be employed in known radioimmunoassay techniques. (author)

  20. USA National Phenology Network’s volunteer-contributed observations yield predictive models of phenological transitions

    Science.gov (United States)

    Crimmins, Theresa M.; Crimmins, Michael A.; Gerst, Katherine L.; Rosemartin, Alyssa H.; Weltzin, Jake

    2017-01-01

    In support of science and society, the USA National Phenology Network (USA-NPN) maintains a rapidly growing, continental-scale, species-rich dataset of plant and animal phenology observations that with over 10 million records is the largest such database in the United States. Contributed voluntarily by professional and citizen scientists, these opportunistically collected observations are characterized by spatial clustering, inconsistent spatial and temporal sampling, and short temporal depth. We explore the potential for developing models of phenophase transitions suitable for use at the continental scale, which could be applied to a wide range of resource management contexts. We constructed predictive models of the onset of breaking leaf buds, leaves, open flowers, and ripe fruits – phenophases that are the most abundant in the database and also relevant to management applications – for all species with available data, regardless of plant growth habit, location, geographic extent, or temporal depth of the observations. We implemented a very basic model formulation - thermal time models with a fixed start date. Sufficient data were available to construct 107 individual species × phenophase models. Of these, fifteen models (14%) met our criteria for model fit and error and were suitable for use across the majority of the species’ geographic ranges. These findings indicate that the USA-NPN dataset holds promise for further and more refined modeling efforts. Further, the candidate models that emerged could be used to produce real-time and short-term forecast maps of the timing of such transitions to directly support natural resource management.

  1. Complex dynamics induced by strong confinement - From tracer diffusion in strongly heterogeneous media to glassy relaxation of dense fluids in narrow slits

    Science.gov (United States)

    Mandal, Suvendu; Spanner-Denzer, Markus; Leitmann, Sebastian; Franosch, Thomas

    2017-08-01

    We provide an overview of recent advances of the complex dynamics of particles in strong confinements. The first paradigm is the Lorentz model where tracers explore a quenched disordered host structure. Such systems naturally occur as limiting cases of binary glass-forming systems if the dynamics of one component is much faster than the other. For a certain critical density of the host structure the tracers undergo a localization transition which constitutes a critical phenomenon. A series of predictions in the vicinity of the transition have been elaborated and tested versus computer simulations. Analytical progress is achieved for small obstacle densities. The second paradigm is a dense strongly interacting liquid confined to a narrow slab. Then the glass transition depends nonmonotonically on the separation of the plates due to an interplay of local packing and layering. Very small slab widths allow to address certain features of the statics and dynamics analytically.

  2. Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Sabag, Jetzabeth

    1988-02-01

    The proposed model has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The idealized system of the reservoir is made up of two regions: A movable region, where diffusion and convection mechanisms are present and a stagnant or immovable region where the diffusion and adsorption mechanisms are considered: in both regions the loss of mass by radioactive decay is considered. The solutions of the basic flow equations are in the Laplace space and for its numerical inversion the Stehfest algorithm was used. In spite of the numerical dispersion that these solutions involve, a well defined tendency to infer the system behavior under different flow conditions was found. It was found that, for practical purposes, the size of the matrix blocks does not have an influence on the concentration response, and the solution is reduced to the one presented by Tang and associates. Under these conditions, the system behavior can be described by two non-dimensional parameters: The Peclet number in fractures, P{sub e1}, and a parameter. The tracer response for the peak solution was also derived. An analytical solution limit was found for the case in which {alpha} tends to zero, which corresponds to the case of a homogenous system. It was verified that this limit solution is valid, for {alpha}<0.01. For the case of continuous injection, this solution is reduced to the one presented by Coasts and Smith. For the peak solution, it was found that the irruption time corresponding to the maximum concentration is directly related to the non-dimensional group. Therefore, it is possible to obtain the value of P{sub e1} for a given X{sub D}, or vice versa. A group of graphs of non-dimensional concentration in the fracture versus non-dimensional time, was developed. It was found that if P{sub e1} remains constant whereas {alpha} changes, the limit solution is the envelope of a family of curves in a graph of C{sub D} versus t{sub D}. In this figure P

  3. Rainfall and Extratropical Transition of Tropical Cyclones: Simulation, Prediction, and Projection

    Science.gov (United States)

    Liu, Maofeng

    Rainfall and associated flood hazards are one of the major threats of tropical cyclones (TCs) to coastal and inland regions. The interaction of TCs with extratropical systems can lead to enhanced precipitation over enlarged areas through extratropical transition (ET). To achieve a comprehensive understanding of rainfall and ET associated with TCs, this thesis conducts weather-scale analyses by focusing on individual storms and climate-scale analyses by focusing on seasonal predictability and changing properties of climatology under global warming. The temporal and spatial rainfall evolution of individual storms, including Hurricane Irene (2011), Hurricane Hanna (2008), and Hurricane Sandy (2012), is explored using the Weather Research and Forecast (WRF) model and a variety of hydrometeorological datasets. ET and Orographic mechanism are two key players in the rainfall distribution of Irene over regions experiencing most severe flooding. The change of TC rainfall under global warming is explored with the Forecast-oriented Low Ocean Resolution (FLOR) climate model under representative concentration pathway (RCP) 4.5 scenario. Despite decreased TC frequency, FLOR projects increased landfalling TC rainfall over most regions of eastern United States, highlighting the risk of increased flood hazards. Increased storm rain rate is an important player of increased landfalling TC rainfall. A higher atmospheric resolution version of FLOR (HiFLOR) model projects increased TC rainfall at global scales. The increase of TC intensity and environmental water vapor content scaled by the Clausius-Clapeyron relation are two key factors that explain the projected increase of TC rainfall. Analyses on the simulation, prediction, and projection of the ET activity with FLOR are conducted in the North Atlantic. FLOR model exhibits good skills in simulating many aspects of present-day ET climatology. The 21st-century-projection under RCP4.5 scenario demonstrates the dominant role of ET

  4. Prediction of rainfall anomalies during the dry to wet transition season over the Southern Amazonia using machine learning tools

    Science.gov (United States)

    Shan, X.; Zhang, K.; Zhuang, Y.; Fu, R.; Hong, Y.

    2017-12-01

    Seasonal prediction of rainfall during the dry-to-wet transition season in austral spring (September-November) over southern Amazonia is central for improving planting crops and fire mitigation in that region. Previous studies have identified the key large-scale atmospheric dynamic and thermodynamics pre-conditions during the dry season (June-August) that influence the rainfall anomalies during the dry to wet transition season over Southern Amazonia. Based on these key pre-conditions during dry season, we have evaluated several statistical models and developed a Neural Network based statistical prediction system to predict rainfall during the dry to wet transition for Southern Amazonia (5-15°S, 50-70°W). Multivariate Empirical Orthogonal Function (EOF) Analysis is applied to the following four fields during JJA from the ECMWF Reanalysis (ERA-Interim) spanning from year 1979 to 2015: geopotential height at 200 hPa, surface relative humidity, convective inhibition energy (CIN) index and convective available potential energy (CAPE), to filter out noise and highlight the most coherent spatial and temporal variations. The first 10 EOF modes are retained for inputs to the statistical models, accounting for at least 70% of the total variance in the predictor fields. We have tested several linear and non-linear statistical methods. While the regularized Ridge Regression and Lasso Regression can generally capture the spatial pattern and magnitude of rainfall anomalies, we found that that Neural Network performs best with an accuracy greater than 80%, as expected from the non-linear dependence of the rainfall on the large-scale atmospheric thermodynamic conditions and circulation. Further tests of various prediction skill metrics and hindcasts also suggest this Neural Network prediction approach can significantly improve seasonal prediction skill than the dynamic predictions and regression based statistical predictions. Thus, this statistical prediction system could have

  5. Stages of Change or Changes of Stage? Predicting Transitions in Transtheoretical Model Stages in Relation to Healthy Food Choice

    Science.gov (United States)

    Armitage, Christopher J.; Sheeran, Paschal; Conner, Mark; Arden, Madelynne A.

    2004-01-01

    Relatively little research has examined factors that account for transitions between transtheoretical model (TTM) stages of change. The present study (N=787) used sociodemographic, TTM, and theory of planned behavior (TPB) variables, as well as theory-driven interventions to predict changes in stage. Longitudinal analyses revealed that…

  6. Prediction of flow rates through an orifice at pressures corresponding to the transition between molecular and isentropic flow

    International Nuclear Information System (INIS)

    DeMuth, S.F.; Watson, J.S.

    1985-01-01

    A model of compressible flow through an orifice, in the region of transition from free molecular to isentropic expansion flow, has been developed and tested for accuracy. The transitional or slip regime is defined as the conditions where molecular interactions are too many for free molecular flow modeling, yet not great enough for isentropic expansion flow modeling. Due to a lack of literature establishing a well-accepted model for predicting transitional flow, it was felt such work would be beneficial. The model is nonlinear and cannot be satisfactorily linearized for a linear regression analysis. Consequently, a computer routine was developed which minimized the sum of the squares of the residual flow for the nonlinear model. The results indicate an average accuracy within 15% of the measured flow throughout the range of test conditions. Furthermore, the results of the regression analysis indicate that the transitional regime lies between Knudsen numbers of approximately 2 and 45. 4 refs., 3 figs., 1 tab

  7. Introducing ab initio based neural networks for transition-rate prediction in kinetic Monte Carlo simulations

    Science.gov (United States)

    Messina, Luca; Castin, Nicolas; Domain, Christophe; Olsson, Pär

    2017-02-01

    The quality of kinetic Monte Carlo (KMC) simulations of microstructure evolution in alloys relies on the parametrization of point-defect migration rates, which are complex functions of the local chemical composition and can be calculated accurately with ab initio methods. However, constructing reliable models that ensure the best possible transfer of physical information from ab initio to KMC is a challenging task. This work presents an innovative approach, where the transition rates are predicted by artificial neural networks trained on a database of 2000 migration barriers, obtained with density functional theory (DFT) in place of interatomic potentials. The method is tested on copper precipitation in thermally aged iron alloys, by means of a hybrid atomistic-object KMC model. For the object part of the model, the stability and mobility properties of copper-vacancy clusters are analyzed by means of independent atomistic KMC simulations, driven by the same neural networks. The cluster diffusion coefficients and mean free paths are found to increase with size, confirming the dominant role of coarsening of medium- and large-sized clusters in the precipitation kinetics. The evolution under thermal aging is in better agreement with experiments with respect to a previous interatomic-potential model, especially concerning the experiment time scales. However, the model underestimates the solubility of copper in iron due to the excessively high solution energy predicted by the chosen DFT method. Nevertheless, this work proves the capability of neural networks to transfer complex ab initio physical properties to higher-scale models, and facilitates the extension to systems with increasing chemical complexity, setting the ground for reliable microstructure evolution simulations in a wide range of alloys and applications.

  8. Tracer tests Wairakei

    International Nuclear Information System (INIS)

    McCabe, W.J.; Manning, M.R.; Barry, B.J.

    1980-07-01

    The report summarises the radioactive tracer tests, using iodine-131 and bromine-82, made in the Wairakei geothermal field over the period 1978-80. Injection of tracer into three wells with strong cool water downflows at about 300-400m below ground level, produced strong rapid responses from the only deep wells feeding from about 800-1000m and lying in the south-westerly direction from the injection wells, i.e. parallel to the fault planes. Shallower wells, even though in some cases much closer to the injection well, reacted much more slowly. Velocities, as measured by peak arrival times, as high as 22m/h over 200m and 11m/h over 650m, were found. The flow patterns for the cool water feeds to the production area are discussed

  9. Radioactive tracers in Sedimentology

    International Nuclear Information System (INIS)

    Rodrigues, H.T.

    1973-01-01

    First is given a broad description of the uses of radioactive tracers in Sedimentology. The general method is established, including determinations of probability and standard deviation. Following are determined: the response law of the detector, the minimum mass for statistical detection, and the minimum mass for dynamic detection. The granularity is an important variable in these calculations. Final conclusions are given, and results are compared with existing theories

  10. Tracers and Tracer Testing: Design, Implementation, Tracer Selection, and Interpretation Methods

    Energy Technology Data Exchange (ETDEWEB)

    G. Michael Shook; Shannon L.; Allan Wylie

    2004-01-01

    Conducting a successful tracer test requires adhering to a set of steps. The steps include identifying appropriate and achievable test goals, identifying tracers with the appropriate properties, and implementing the test as designed. When these steps are taken correctly, a host of tracer test analysis methods are available to the practitioner. This report discusses the individual steps required for a successful tracer test and presents methods for analysis. The report is an overview of tracer technology; the Suggested Reading section offers references to the specifics of test design and interpretation.

  11. Heat tracer methods

    Science.gov (United States)

    Healy, Richard W.; Scanlon, Bridget R.

    2010-01-01

    The flow of heat in the subsurface is closely linked to the movement of water (Ingebritsen et al., 2006). As such, heat has been used as a tracer in groundwater studies for more than 100 years (Anderson, 2005). As with chemical and isotopic tracers (Chapter 7), spatial or temporal trends in surface and subsurface temperatures can be used to infer rates of water movement. Temperature can be measured accurately, economically, at high frequencies, and without the need to obtain water samples, facts that make heat an attractive tracer. Temperature measurements made over space and time can be used to infer rates of recharge from a stream or other surface water body (Lapham, 1989; Stonestrom and Constantz, 2003); measurements can also be used to estimate rates of steady drainage through depth intervals within thick unsaturated zones (Constantz et al., 2003; Shan and Bodvarsson, 2004). Several thorough reviews of heat as a tracer in hydrologic studies have recently been published (Constantz et al., 2003; Stonestrom and Constantz, 2003; Anderson, 2005; Blasch et al., 2007; Constantz et al., 2008). This chapter summarizes heat-tracer approaches that have been used to estimate recharge.Some clarification in terminology is presented here to avoid confusion in descriptions of the various approaches that follow. Diffuse recharge is that which occurs more or less uniformly across large areas in response to precipitation, infiltration, and drainage through the unsaturated zone. Estimates of diffuse recharge determined using measured temperatures in the unsaturated zone are referred to as potential recharge because it is possible that not all of the water moving through the unsaturated zone will recharge the aquifer; some may be lost to the atmosphere by evaporation or plant transpiration. Estimated fluxes across confining units in the saturated zone are referred to as interaquifer flow (Chapter 1). Focused recharge is that which occurs directly from a point or line source, such

  12. Transitional Probabilities Are Prioritized over Stimulus/Pattern Probabilities in Auditory Deviance Detection: Memory Basis for Predictive Sound Processing.

    Science.gov (United States)

    Mittag, Maria; Takegata, Rika; Winkler, István

    2016-09-14

    Representations encoding the probabilities of auditory events do not directly support predictive processing. In contrast, information about the probability with which a given sound follows another (transitional probability) allows predictions of upcoming sounds. We tested whether behavioral and cortical auditory deviance detection (the latter indexed by the mismatch negativity event-related potential) relies on probabilities of sound patterns or on transitional probabilities. We presented healthy adult volunteers with three types of rare tone-triplets among frequent standard triplets of high-low-high (H-L-H) or L-H-L pitch structure: proximity deviant (H-H-H/L-L-L), reversal deviant (L-H-L/H-L-H), and first-tone deviant (L-L-H/H-H-L). If deviance detection was based on pattern probability, reversal and first-tone deviants should be detected with similar latency because both differ from the standard at the first pattern position. If deviance detection was based on transitional probabilities, then reversal deviants should be the most difficult to detect because, unlike the other two deviants, they contain no low-probability pitch transitions. The data clearly showed that both behavioral and cortical auditory deviance detection uses transitional probabilities. Thus, the memory traces underlying cortical deviance detection may provide a link between stimulus probability-based change/novelty detectors operating at lower levels of the auditory system and higher auditory cognitive functions that involve predictive processing. Our research presents the first definite evidence for the auditory system prioritizing transitional probabilities over probabilities of individual sensory events. Forming representations for transitional probabilities paves the way for predictions of upcoming sounds. Several recent theories suggest that predictive processing provides the general basis of human perception, including important auditory functions, such as auditory scene analysis. Our

  13. Development of radioisotope tracer technology

    International Nuclear Information System (INIS)

    Jin, Joon Ha; Lee, Myun Joo; Jung, Sung Hee; Park, Soon Chul; Lim, Dong Soon; Kim, Jae Ho; Lee, Jae Choon; Lee, Doo Sung; Cho, Yong Suk; Shin, Sung Kuan

    2000-04-01

    The purpose of this study is to develop the radioisotope tracer technology, which can be used in solving industrial and environmental problems and to build a strong tracer group to support the local industries. In relation to the tracer technology in 1999, experiments to estimate the efficiencies of a sludge digester of a waste water treatment plant and a submerged biological reactor of a dye industry were conducted. As a result, the tracer technology for optimization of facilities related to wastewater treatment has been developed and is believed to contribute to improve their operation efficiency. The quantification of the experimental result was attempted to improve the confidence of tracer technology by ECRIN program which basically uses the MCNP simulation principle. Using thin layer activation technique, wear of tappet shim was estimated. Thin layer surface of a tappet shim was irradiated by proton beam and the correlation between the measured activity loss and the amount of wear was established. The equipment was developed to adjust the energy of proton which collides with the surface of tappet. The tracer project team has participated into the tracer test for estimating the efficiency of RFCC system in SK cooperation. From the experiment the tracer team has obtained the primary elements to be considered for judging the efficiency of RFCC unit. By developing the tracer techniques to test huge industrial units like RFCC, the tracer team will be able to support the local industries that require technical services to solve any urgent trouble. (author)

  14. Chemical Tracer Methods: Chapter 7

    Science.gov (United States)

    Healy, Richard W.

    2017-01-01

    Tracers have a wide variety of uses in hydrologic studies: providing quantitative or qualitative estimates of recharge, identifying sources of recharge, providing information on velocities and travel times of water movement, assessing the importance of preferential flow paths, providing information on hydrodynamic dispersion, and providing data for calibration of water flow and solute-transport models (Walker, 1998; Cook and Herczeg, 2000; Scanlon et al., 2002b). Tracers generally are ions, isotopes, or gases that move with water and that can be detected in the atmosphere, in surface waters, and in the subsurface. Heat also is transported by water; therefore, temperatures can be used to trace water movement. This chapter focuses on the use of chemical and isotopic tracers in the subsurface to estimate recharge. Tracer use in surface-water studies to determine groundwater discharge to streams is addressed in Chapter 4; the use of temperature as a tracer is described in Chapter 8.Following the nomenclature of Scanlon et al. (2002b), tracers are grouped into three categories: natural environmental tracers, historical tracers, and applied tracers. Natural environmental tracers are those that are transported to or created within the atmosphere under natural processes; these tracers are carried to the Earth’s surface as wet or dry atmospheric deposition. The most commonly used natural environmental tracer is chloride (Cl) (Allison and Hughes, 1978). Ocean water, through the process of evaporation, is the primary source of atmospheric Cl. Other tracers in this category include chlorine-36 (36Cl) and tritium (3H); these two isotopes are produced naturally in the Earth’s atmosphere; however, there are additional anthropogenic sources of them.

  15. Predicted stability, structures, and magnetism of 3d transition metal nitrides: the M4N phases

    NARCIS (Netherlands)

    Fang, C.M.; Koster, R.S.; Li, W.F.; van Huis, M.A.

    2014-01-01

    The 3d transition metal nitrides M4N (Sc4N, Ti4N, V4N, Cr4N, Mn4N, Fe4N, Co4N, Ni4N, and Cu4N) have unique phase relationships, crystal structures, and electronic and magnetic properties. Here we present a systematic density functional theory (DFT) study on these transition metal nitrides, assessing

  16. Radionuclides as tracers

    International Nuclear Information System (INIS)

    Ganatra, R.D.

    1992-01-01

    Importance of radioisotopes in medicine is because of their two characteristics: their biological behaviour is identical to their stable counterparts, and because they are radioactive their emissions can be detected by a suitable instrument. All isotopes of iodine will behave in the same way and will concentrate in the thyroid gland. There is no way of detecting the stable, natural iodine in the thyroid gland, but the presence of radioactive iodine can be detected externally in vivo by a detector. Thus, the radioactive iodine becomes a tracer, a sport of a spy, which mimics the behaviour of natural iodine and relays information to a detector. The radioactive tracers are popular because of the ease with which they can be detected in vivo and the fact that the measurement of their presence in the body can be in quantitative terms. The measurement can be very accurate and sensitive. Whenever the measurements can be done in vivo, the information is obtained in dynamic terms, as it is happening, as if the physiological events become transparent

  17. Prediction of B1 to B10 phase transition in LuN under pressure: An ab-initio investigation

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, B. D., E-mail: bdsahoo@barc.gov.in; Mukherjee, D.; Joshi, K. D.; Kaushik, T. C.; Gupta, Satish C. [Applied Physics Division, Bhabha Atomic Research Centre, Mumbai, India 400085 (India)

    2016-05-23

    Ab-initio total energy calculations have been performed in lutetium nitride (LuN) as a function of hydrostatic compression to understand the high pressure behavior of this compound. Our calculations predict a phase transition from ambient rocksalt type structure (B1 phase) to a tetragonal structure (B10 phase) at ~ 240 GPa. The phase transition has been identified as first order in nature with volume discontinuity of ~ 6%. The predicted high pressure phase has been found to be stable up to at least 400 GPa, the maximum pressure up to which calculations have been performed.Further, to substantiate the results of static lattice calculations analysis of lattice dynamic stability of B1 and B10 phase has been carried out at different pressures. Apart from this, we have analyzed the lattice dynamic stability CsCl type (B2) phase around the 240 GPa, the pressure reported for B1 to B2 transition in previous all-electron calculations by Gupta et al. 2013. We find that the B2 structure is lattice dynamically unstable at this pressure and remains unstable up to ~ 400 GPa, ruling out the possibility of B1 to B2 phase transition at least up to ~ 400 GPa. Further, the theoretically determined equation of state has been utilized to derive various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus of B1 phase at ambient conditions.

  18. Forced convective transition boiling: review of literature and comparison of prediction methods

    International Nuclear Information System (INIS)

    Groeneveld, D.C.; Fung, K.K.

    1976-06-01

    This report reviews the published information on transition boiling heat transfer under forced convective conditions. It was found that transition boiling data have been obtained only within a limited range of conditions and many data are considered unreliable. The data do not permit the derivation of a correlation; however the parametric trends can be isolated from the data. Several authors have proposed correlations valid in the transition boiling region. Most of the correlations are valid only within a narrow range of conditions. A comparison with the data shows that in general agreement is poor. Hsu's correlation is tentatively recommended for low flows and pressures. (author)

  19. A New Approach for Accurate Prediction of Liquid Loading of Directional Gas Wells in Transition Flow or Turbulent Flow

    Directory of Open Access Journals (Sweden)

    Ruiqing Ming

    2017-01-01

    Full Text Available Current common models for calculating continuous liquid-carrying critical gas velocity are established based on vertical wells and laminar flow without considering the influence of deviation angle and Reynolds number on liquid-carrying. With the increase of the directional well in transition flow or turbulent flow, the current common models cannot accurately predict the critical gas velocity of these wells. So we built a new model to predict continuous liquid-carrying critical gas velocity for directional well in transition flow or turbulent flow. It is shown from sensitivity analysis that the correction coefficient is mainly influenced by Reynolds number and deviation angle. With the increase of Reynolds number, the critical liquid-carrying gas velocity increases first and then decreases. And with the increase of deviation angle, the critical liquid-carrying gas velocity gradually decreases. It is indicated from the case calculation analysis that the calculation error of this new model is less than 10%, where accuracy is much higher than those of current common models. It is demonstrated that the continuous liquid-carrying critical gas velocity of directional well in transition flow or turbulent flow can be predicted accurately by using this new model.

  20. Assessment of key transport parameters in a karst system under different dynamic conditions based on tracer experiments: the Jeita karst system, Lebanon

    Science.gov (United States)

    Doummar, Joanna; Margane, Armin; Geyer, Tobias; Sauter, Martin

    2018-03-01

    Artificial tracer experiments were conducted in the mature karst system of Jeita (Lebanon) under various flow conditions using surface and subsurface tracer injection points, to determine the variation of transport parameters (attenuation of peak concentration, velocity, transit times, dispersivity, and proportion of immobile and mobile regions) along fast and slow flow pathways. Tracer breakthrough curves (TBCs) observed at the karst spring were interpreted using a two-region nonequilibrium approach (2RNEM) to account for the skewness in the TBCs' long tailings. The conduit test results revealed a discharge threshold in the system dynamics, beyond which the transport parameters vary significantly. The polynomial relationship between transport velocity and discharge can be related to the variation of the conduit's cross-sectional area. Longitudinal dispersivity in the conduit system is not a constant value (α = 7-10 m) and decreases linearly with increasing flow rate because of dilution effects. Additionally, the proportion of immobile regions (arising from conduit irregularities) increases with decreasing water level in the conduit system. From tracer tests with injection at the surface, longitudinal dispersivity values are found to be large (8-27 m). The tailing observed in some TBCs is generated in the unsaturated zone before the tracer actually arrives at the major subsurface conduit draining the system. This work allows the estimation and prediction of the key transport parameters in karst aquifers. It shows that these parameters vary with time and flow dynamics, and they reflect the geometry of the flow pathway and the origin of infiltrating (potentially contaminated) recharge.

  1. Enthalpy of phase transition and prediction of phase Equilibria in systems of glycols and glycol ethers

    OpenAIRE

    Esina, Zoya; Miroshnikov, Aleksandr; Korchuganova, Margarita

    2014-01-01

    The PCEAS model was used to study the liquid-solid and liquid-vapor phase transitions at constant pressure in systems containing glycols and glycol ethers. This method is based on minimizing the excess Gibbs energy over the solvation parameter, which takes into account the processes of association of molecules in various phases. To compute the diagrams, the data on enthalpy and phase transition temperatures of pure components are required, while the information about the interactions in the b...

  2. Boundary-layer transition prediction using a simplified correlation-based model

    Directory of Open Access Journals (Sweden)

    Xia Chenchao

    2016-02-01

    Full Text Available This paper describes a simplified transition model based on the recently developed correlation-based γ-Reθt transition model. The transport equation of transition momentum thickness Reynolds number is eliminated for simplicity, and new transition length function and critical Reynolds number correlation are proposed. The new model is implemented into an in-house computational fluid dynamics (CFD code and validated for low and high-speed flow cases, including the zero pressure flat plate, airfoils, hypersonic flat plate and double wedge. Comparisons between the simulation results and experimental data show that the boundary-layer transition phenomena can be reasonably illustrated by the new model, which gives rise to significant improvements over the fully laminar and fully turbulent results. Moreover, the new model has comparable features of accuracy and applicability when compared with the original γ-Reθt model. In the meantime, the newly proposed model takes only one transport equation of intermittency factor and requires fewer correlations, which simplifies the original model greatly. Further studies, especially on separation-induced transition flows, are required for the improvement of the new model.

  3. Radon as geological tracer

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, T.; Anjos, R.M. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Fisica; Valladares, D.L.; Rizzotto, M.; Velasco, H.; Ayub, J. Juri [Universidad Nacional de San Luis (Argentina). Inst. de Matematica Aplicada San Luis (IMASL); Silva, A.A.R. da; Yoshimura, E.M. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica

    2012-07-01

    Full text: This work presents measurements of {sup 222}Rn levels performed in La Carolina gold mine and Los Condores tungsten mine at the province of San Luis, Argentina, today used for tourist visitation, and can evaluate the potential use of such radioactive noble gas as tracer or marker for geological processes in underground environments. By concentrations of {sup 40}K, {sup 232}Th and {sup 23}'8U were also measured in the walls of tunnels were determined the rocks mineral composition, what indicated that the mines have the same composition. In this sense, we used nuclear trace plastic detectors CR-39, gamma spectrometry of rock samples and Geiger-Muller (GM) monitors The patterns of radon gas transportation processes revealed that La Carolina could be interpreted through a model based on a radioactive gas confined into a single entrance tube, with constant cross section and air velocity. Los Condores, which has a second main entrance, could be interpreted through a model based on a radioactive gas confined into a two entrance tube, allowing a chimney effect for air circulation. The results showed the high potential of using {sup 222}Rn as a geological tracer. In what concerns the occupational hazard, in summer (time of more intense tourist activity in the mine) La Carolina presented a mean concentration of the radioactive noble gas that exceeds in four times the action level of 1,5 kBq m{sup -3} recommended by the International Commission of Radiological Protection (ICRP). The chimney effect shows the low mean concentration of radon in Los Condores. (author)

  4. Radon as geological tracer

    International Nuclear Information System (INIS)

    Lacerda, T.; Anjos, R.M.; Silva, A.A.R. da; Yoshimura, E.M.

    2012-01-01

    Full text: This work presents measurements of 222 Rn levels performed in La Carolina gold mine and Los Condores tungsten mine at the province of San Luis, Argentina, today used for tourist visitation, and can evaluate the potential use of such radioactive noble gas as tracer or marker for geological processes in underground environments. By concentrations of 40 K, 232 Th and 23 '8U were also measured in the walls of tunnels were determined the rocks mineral composition, what indicated that the mines have the same composition. In this sense, we used nuclear trace plastic detectors CR-39, gamma spectrometry of rock samples and Geiger-Muller (GM) monitors The patterns of radon gas transportation processes revealed that La Carolina could be interpreted through a model based on a radioactive gas confined into a single entrance tube, with constant cross section and air velocity. Los Condores, which has a second main entrance, could be interpreted through a model based on a radioactive gas confined into a two entrance tube, allowing a chimney effect for air circulation. The results showed the high potential of using 222 Rn as a geological tracer. In what concerns the occupational hazard, in summer (time of more intense tourist activity in the mine) La Carolina presented a mean concentration of the radioactive noble gas that exceeds in four times the action level of 1,5 kBq m -3 recommended by the International Commission of Radiological Protection (ICRP). The chimney effect shows the low mean concentration of radon in Los Condores. (author)

  5. Root zone effects on tracer migration in arid zones

    International Nuclear Information System (INIS)

    Tyler, S.W.; Walker, G.R.

    1994-01-01

    The study of groundwater recharge and soil water movement in arid regions has received increased attention in the search for safe disposal sites for hazardous wastes. In passing through the upper 1 to 2 m of most soil profiles, tracers indicative of recharge such as Cl, 2 H, 18 O, Br, 3 H, and 56 Cl are subjected to a wide range of processes not encountered deeper in the profile. This transition zone, where water enters as precipitation and leaves as recharge, is often ignored when environmental tracers are used to estimate deep soil water flux and recharge, yet its effect may be profound. In this work, we reexamine the processes of root extraction and its effect on the velocity and distribution of tracers. Examples are presented for idealized conditions, which show clearly the relation between the root zone processes and the deep drainage or recharge. The results indicate that, when recharge is small and root zone processes are not accounted for, tracer techniques can significantly overestimate recharge until the tracer has moved well below the root zone. By incorporating simple models of root zone processes, a clearer understanding of tracer distributions and a more accurate estimate of recharge can then be made. 11 refs., 9 figs

  6. Prediction of transition from common adolescent bipolar experiences to bipolar disorder: 10-year study.

    Science.gov (United States)

    Tijssen, Marijn J A; van Os, Jim; Wittchen, Hans-Ulrich; Lieb, Roselind; Beesdo, Katja; Mengelers, Ron; Wichers, Marieke

    2010-02-01

    Although (hypo)manic symptoms are common in adolescence, transition to adult bipolar disorder is infrequent. To examine whether the risk of transition to bipolar disorder is conditional on the extent of persistence of subthreshold affective phenotypes. In a 10-year prospective community cohort study of 3021 adolescents and young adults, the association between persistence of affective symptoms over 3 years and the 10-year clinical outcomes of incident DSM-IV (hypo)manic episodes and incident use of mental healthcare was assessed. Transition to clinical outcome was associated with persistence of symptoms in a dose-dependent manner. Around 30-40% of clinical outcomes could be traced to prior persistence of affective symptoms. In a substantial proportion of individuals, onset of clinical bipolar disorder may be seen as the poor outcome of a developmentally common and usually transitory non-clinical bipolar phenotype.

  7. Can the care transitions measure predict rehospitalization risk or home health nursing use of home healthcare patients?

    Science.gov (United States)

    Ryvicker, Miriam; McDonald, Margaret V; Trachtenberg, Melissa; Peng, Timothy R; Sridharan, Sridevi; Feldman, Penny H

    2013-01-01

    The Care Transitions Measure (CTM) was designed to assess the quality of patient transitions from the hospital. Many hospitals are using the measure to inform their efforts to improve transitional care. We sought to determine if the measure would have utility for home healthcare providers by predicting newly admitted patients at heightened risk for emergency department use, rehospitalization, or increased home health nursing visits. The CTM was administered to 495 home healthcare patients shortly after hospital discharge and home healthcare admission. Follow-up interviews were completed 30 and 60 days post hospital discharge. Interview data were supplemented with agency assessment and service use data. We did not find evidence that the CTM could predict home healthcare patients having an elevated risk for emergent care, rehospitalization, or higher home health nursing use. Because Medicare/Medicaid-certified home healthcare providers already use a comprehensive, mandated start of care assessment, the CTM may not provide them additional crucial information. Process and outcome measurement is increasingly becoming part of usual care. Selection of measures appropriate for each service setting requires thorough site-specific evaluation. In light of our findings, we cannot recommend the CTM as an additional measure in the home healthcare setting. © 2013 National Association for Healthcare Quality.

  8. A Predictive Coexpression Network Identifies Novel Genes Controlling the Seed-to-Seedling Phase Transition in Arabidopsis thaliana.

    Science.gov (United States)

    Silva, Anderson Tadeu; Ribone, Pamela A; Chan, Raquel L; Ligterink, Wilco; Hilhorst, Henk W M

    2016-04-01

    The transition from a quiescent dry seed to an actively growing photoautotrophic seedling is a complex and crucial trait for plant propagation. This study provides a detailed description of global gene expression in seven successive developmental stages of seedling establishment in Arabidopsis (Arabidopsis thaliana). Using the transcriptome signature from these developmental stages, we obtained a coexpression gene network that highlights interactions between known regulators of the seed-to-seedling transition and predicts the functions of uncharacterized genes in seedling establishment. The coexpressed gene data sets together with the transcriptional module indicate biological functions related to seedling establishment. Characterization of the homeodomain leucine zipper I transcription factor AtHB13, which is expressed during the seed-to-seedling transition, demonstrated that this gene regulates some of the network nodes and affects late seedling establishment. Knockout mutants for athb13 showed increased primary root length as compared with wild-type (Columbia-0) seedlings, suggesting that this transcription factor is a negative regulator of early root growth, possibly repressing cell division and/or cell elongation or the length of time that cells elongate. The signal transduction pathways present during the early phases of the seed-to-seedling transition anticipate the control of important events for a vigorous seedling, such as root growth. This study demonstrates that a gene coexpression network together with transcriptional modules can provide insights that are not derived from comparative transcript profiling alone. © 2016 American Society of Plant Biologists. All Rights Reserved.

  9. Predicting Postsecondary Education and Employment Outcomes Using Results from the Transition Assessment and Goal Generator

    Science.gov (United States)

    Burnes, Jennifer J.; Martin, James E.; Terry, Robert; McConnell, Amber E.; Hennessey, Maeghan N.

    2018-01-01

    We conducted an exploratory study to investigate the relation between nonacademic behavior constructs measured by the "Transition Assessment and Goal Generator" (TAGG) and postsecondary education and employment outcomes for 297 high school leavers who completed the TAGG during their high school years. Four of eight TAGG constructs…

  10. Tracer dating and ocean ventilation

    International Nuclear Information System (INIS)

    Thiele, G.; Sarmiento, J.L.

    1990-01-01

    The interpretation of transient tracer observations depends on difficult to obtain information on the evolution in time of the tracer boundary conditions and interior distributions. Recent studies have attempted to circumvent this problem by making use of a derived quantity, age, based on the simultaneous distribution of two complementary tracers, such as tritium and its daughter, helium 3. The age is defined with reference to the surface such that the boundary condition takes on a constant value of zero. The authors use a two-dimensional model to explore the circumstances under which such a combination of conservation equations for two complementary tracers can lead to a cancellation of the time derivative terms. An interesting aspect of this approach is that mixing can serve as a source or sink of tracer based age. The authors define an idealized ventilation age tracer that is conservative with respect to mixing, and they explore how its behavior compares with that of the tracer-based ages over a range of advective and diffusive parameters

  11. Advection and dispersion of bed load tracers

    Science.gov (United States)

    Lajeunesse, Eric; Devauchelle, Olivier; James, François

    2018-05-01

    We use the erosion-deposition model introduced by Charru et al. (2004) to numerically simulate the evolution of a plume of bed load tracers entrained by a steady flow. In this model, the propagation of the plume results from the stochastic exchange of particles between the bed and the bed load layer. We find a transition between two asymptotic regimes. The tracers, initially at rest, are gradually set into motion by the flow. During this entrainment regime, the plume is strongly skewed in the direction of propagation and continuously accelerates while spreading nonlinearly. With time, the skewness of the plume eventually reaches a maximum value before decreasing. This marks the transition to an advection-diffusion regime in which the plume becomes increasingly symmetrical, spreads linearly, and advances at constant velocity. We analytically derive the expressions of the position, the variance, and the skewness of the plume and investigate their asymptotic regimes. Our model assumes steady state. In the field, however, bed load transport is intermittent. We show that the asymptotic regimes become insensitive to this intermittency when expressed in terms of the distance traveled by the plume. If this finding applies to the field, it might provide an estimate for the average bed load transport rate.

  12. Predicting animal home-range structure and transitions using a multistate Ornstein-Uhlenbeck biased random walk

    Science.gov (United States)

    Breed, Greg A.; Golson, Emily A.; Tinker, M. Tim

    2017-01-01

    The home‐range concept is central in animal ecology and behavior, and numerous mechanistic models have been developed to understand home range formation and maintenance. These mechanistic models usually assume a single, contiguous home range. Here we describe and implement a simple home‐range model that can accommodate multiple home‐range centers, form complex shapes, allow discontinuities in use patterns, and infer how external and internal variables affect movement and use patterns. The model assumes individuals associate with two or more home‐range centers and move among them with some estimable probability. Movement in and around home‐range centers is governed by a two‐dimensional Ornstein‐Uhlenbeck process, while transitions between centers are modeled as a stochastic state‐switching process. We augmented this base model by introducing environmental and demographic covariates that modify transition probabilities between home‐range centers and can be estimated to provide insight into the movement process. We demonstrate the model using telemetry data from sea otters (Enhydra lutris) in California. The model was fit using a Bayesian Markov Chain Monte Carlo method, which estimated transition probabilities, as well as unique Ornstein‐Uhlenbeck diffusion and centralizing tendency parameters. Estimated parameters could then be used to simulate movement and space use that was virtually indistinguishable from real data. We used Deviance Information Criterion (DIC) scores to assess model fit and determined that both wind and reproductive status were predictive of transitions between home‐range centers. Females were less likely to move between home‐range centers on windy days, less likely to move between centers when tending pups, and much more likely to move between centers just after weaning a pup. These tendencies are predicted by theoretical movement rules but were not previously known and show that our model can extract meaningful

  13. Predicting animal home-range structure and transitions using a multistate Ornstein-Uhlenbeck biased random walk.

    Science.gov (United States)

    Breed, Greg A; Golson, Emily A; Tinker, M Tim

    2017-01-01

    The home-range concept is central in animal ecology and behavior, and numerous mechanistic models have been developed to understand home range formation and maintenance. These mechanistic models usually assume a single, contiguous home range. Here we describe and implement a simple home-range model that can accommodate multiple home-range centers, form complex shapes, allow discontinuities in use patterns, and infer how external and internal variables affect movement and use patterns. The model assumes individuals associate with two or more home-range centers and move among them with some estimable probability. Movement in and around home-range centers is governed by a two-dimensional Ornstein-Uhlenbeck process, while transitions between centers are modeled as a stochastic state-switching process. We augmented this base model by introducing environmental and demographic covariates that modify transition probabilities between home-range centers and can be estimated to provide insight into the movement process. We demonstrate the model using telemetry data from sea otters (Enhydra lutris) in California. The model was fit using a Bayesian Markov Chain Monte Carlo method, which estimated transition probabilities, as well as unique Ornstein-Uhlenbeck diffusion and centralizing tendency parameters. Estimated parameters could then be used to simulate movement and space use that was virtually indistinguishable from real data. We used Deviance Information Criterion (DIC) scores to assess model fit and determined that both wind and reproductive status were predictive of transitions between home-range centers. Females were less likely to move between home-range centers on windy days, less likely to move between centers when tending pups, and much more likely to move between centers just after weaning a pup. These tendencies are predicted by theoretical movement rules but were not previously known and show that our model can extract meaningful behavioral insight from complex

  14. A phenomenological prediction of dryout based on the churn-to-annular flow transition criterion in uniformly heated vertical tubes

    International Nuclear Information System (INIS)

    Hong, Sung-Deok; Chun, Se-Young; Yang, Sun-Kyu; Chung, Moon-Ki; Lashgari, Farbod

    2000-01-01

    A phenomenological model is proposed to predict dryout in uniformly heated vertical tubes. The major point of the study was refining the initial conditions at the onset of annular flow location that starts the liquid film dryout process. The void fraction at the onset of the annular flow location has been derived from the vapor superficial velocity obtained by the churn-to-annular flow criterion with the help of the void-quality relationship. The thermodynamic equilibrium quality calculated through the iteration of flow quality using the profile-fit model to find the accurate starting point of the annular-flow in a tube. The present method was validated by worldwide data covering wide parametric ranges, a diameter of 5.1-37.5, exit quality over 10%, a flow rate of 183-5261 kg/m 2 -s and a system pressure of 0.5-17.7 MPa. The churn-to-annular flow transition criterion of Taitel et al.'s shows better prediction results than the other transition criteria. The present model improved the CHF prediction capability as a mean of 0.97 and root mean square error of 11% for the 3883 experimental data and extended the applicable range to the relatively low quality region. (author)

  15. Assessing Uncertainties in Boundary Layer Transition Predictions for HIFiRE-1 at Non-zero Angles of Attack

    Science.gov (United States)

    Marek, Lindsay C.

    2011-01-01

    Boundary layer stability was analyzed for the HIFiRE-1 flight vehicle geometry for ground tests conducted at the CUBRC LENS I hypersonic shock test facility and the Langley Research Center (LaRC) 20- inch Mach 6 Tunnel. Boundary layer stability results were compared to transition onset location obtained from discrete heat transfer measurements from thin film gauges during the CUBRC test and spatially continuous heat transfer measurements from thermal phosphor paint data during the LaRC test. The focus of this analysis was on conditions at non-zero angles of attack as stability analysis has already been performed at zero degrees angle of attack. Also, the transition onset data obtained during flight testing was at nonzero angles of attack, so this analysis could be expanded in the future to include the results of the flight test data. Stability analysis was performed using the 2D parabolized stability software suite STABL (Stability and Transition Analysis for Hypersonic Boundary Layers) developed at the University of Minnesota and the mean flow solutions were computed using the DPLR finite volume Navier-Stokes computational fluid dynamics (CFD) solver. A center line slice of the 3D mean flow solution was used for the stability analysis to incorporate the angle of attack effects while still taking advantage of the 2D STABL software suite. The N-factors at transition onset and the value of Re(sub theta)/M(sub e), commonly used to predict boundary layer transition onset, were compared for all conditions analyzed. Ground test data was analyzed at Mach 7.2 and Mach 6.0 and angles of attack of 1deg, 3deg and 5deg. At these conditions, the flow was found to be second mode dominant for the HIFiRE-1 slender cone geometry. On the leeward side of the vehicle, a strong trend of transition onset location with angle of attack was observed as the boundary layer on the leeward side of the vehicle developed inflection points at streamwise positions on the vehicle that correlated to

  16. Tracer research in process engineering

    International Nuclear Information System (INIS)

    Iller, E.

    1992-01-01

    The book is a review of modern applications of tracer techniques in chemical and process engineering studies. The next topics have been extensively presented: 1) media flow through apparatus; 2) the tracers in the study of media flow dynamics through apparatus; 3) mathematical interpretation of experimental data from impulse-response method; 4) the models of media flow through chemical reactors and apparatus; 5) radiotracers in mass transport study; 6) examples of practical applications of tracer methods in industrial objects. 84 refs, 96 figs, 31 tabs

  17. Tracer dispersion - experiment and CFD

    International Nuclear Information System (INIS)

    Zitny, R.

    2004-01-01

    Description of tracer distribution by means of dispersion models is a method successfully used in process engineering for fifty years. Application of dispersion models in reactor engineering for characterization of flows in column apparatus, heat exchangers, etc. is summarized and experimental tracer techniques as well as CFD methods for dispersion coefficients evaluation are discussed. Possible extensions of thermal axial dispersion model (ADM) and a core-wall ADM model suitable for description of tracer dispersion in laminar flows are suggested as well as CFD implementation as 1D finite elements. (author)

  18. Meteorological tracers in regional planning

    International Nuclear Information System (INIS)

    Mueller, K.H.

    1974-11-01

    Atmospheric tracers can be used as indicators to study both the ventilation of an urban region and its dispersion meteorology for air pollutants. A correlation analysis applied to the space-time dependent tracer concentrations is able to give transfer functions, the structure and characteristic parameters of which describe the meteorological and topographical situation of the urban region and its surroundings in an integral manner. To reduce the number of persons usually involved in a tracer experiment an automatic air sampling system had to be developed

  19. Proceedings of the atmospheric tracers and tracer application workshop

    International Nuclear Information System (INIS)

    Barr, S.; Gedayloo, T.

    1979-12-01

    In addition to presentations by participating members a general discussion was held in order to summarize and outline the goals and objectives of the workshop. A number of new low level background tracers such as heavy methanes, perfluorocarbons, multiply labeled isotopes such as 13 C 18 O 2 , helium 3, in addition to sample collection techniques and analytical methods for various tracers were discussed. This report is a summary of discussions and papers presented at this workshop

  20. Prediction of the Formulation Dependence of the Glass Transition Temperature for Amine-Epoxy Copolymers Using a Quantitative Structure-Property Relationship Based on the AM1 Method

    National Research Council Canada - National Science Library

    Morrill, Jason

    2004-01-01

    A designer Quantitative Structure-Property Relationsbip (QSPR) based upon molecular properties calculated using the AM1 semi-empirical quantum mechanical metbod was developed to predict the glass transition temperature (Tg...

  1. Predicting early transition from sub-syndromal presentations to major mental disorders.

    Science.gov (United States)

    Cross, Shane P M; Scott, Jan; Hickie, Ian B

    2017-09-01

    Transition from at-risk state to full syndromal mental disorders is underexplored for unipolar and bipolar disorders compared with psychosis. Prospective, trans-diagnostic study of rates and predictors of early transition from sub-threshold to full syndromal mental disorder. One-year outcome of 243 consenting youth aged 15-25 years with a sub-syndromal presentation of a potentially severe mental disorder. Survival analysis and odds ratio (OR) for predictors of transition identified from baseline clinical and demographic ratings. About 17% ( n =36) experienced transition to a major mental disorder. Independent of syndromal diagnosis, transition was significantly more likely in individuals who were NEET (not in education, employment or training), in females and in those with more negative psychological symptoms (e.g. social withdrawal). NEET status and negative symptoms are modifiable predictors of illness trajectory across diagnostic categories and are not specific to transition to psychosis. I.B.H. has been a Commissioner in Australia's National Mental Health Commission since 2012. He was a board member of headspace: National Youth Mental Health Foundation until January 2012. He has led a range of community-based and pharmaceutical industry-supported depression awareness and education and training programmes. He has led projects for health professionals and the community supported by governmental, community agency and pharmaceutical industry partners (Wyeth, Eli Lilly, Servier, Pfizer, AstraZeneca) for the identification and management of depression and anxiety. He has received honoraria for presentations of his own work at educational seminars supported by a number of non-government organisations and the pharmaceutical industry (including Servier, Pfizer, AstraZeneca and Eli Lilly). He is a member of the Medical Advisory Panel for Medibank Private and also a board member of Psychosis Australia Trust. He leads an investigator-initiated study of the effects of

  2. Tracer studies with aortic infusion result in improper tracer distribution

    International Nuclear Information System (INIS)

    Wisneski, J.A.; Brooks, G.A.; Neese, R.A.; Stanley, W.C.; Morris, D.L.; Gertz, E.W.

    1986-01-01

    It has been suggested that lactate turnover can be accurately assessed by infusing radioactive lactate tracer into the aorta and sampling blood in the vena cava. However, there may be streaming of newly infused tracer in the aorta, resulting in a nonuniform arterial specific activity (SA). Furthermore vena caval blood may not be representative of mixed venous blood. The authors examined this problem in 7 anesthetized dogs with sampling catheters in the pulmonary (PA), carotid (CA), and femoral (FA) arteries, and the superior (SVC) and inferior (IVC) vena cavi. [1- 14 C]lactate was continuously infused into the left ventricle through a catheter introduced through the femoral artery. The same SA (dpm/μmol) was found in the CA and FA, indicating adequate mixing of newly infused tracer with trace. Three dogs showed differences between SVC, IVC and PA, suggesting a mixed venous sample can not be obtained from the VC. When the catheter was moved into the aorta, wide differences in SA appeared between the CA and FA, clearly reflecting streaming of tracer. These differences also appeared in the SVC and IVC. In conclusion, adequate mixing does not occur between tracer and trace in arterial blood with aortic infusion. Further, VC sampling will not give a consistent mixed venous SA. Therefore, for practical reasons, aortic tracer infusion with vena caval sampling will lead to erroneous turnover values

  3. Predicting the glass transition temperature of bioactive glasses from their molecular chemical composition.

    Science.gov (United States)

    Hill, Robert G; Brauer, Delia S

    2011-10-01

    A recently published paper (M.D. O'Donnell, Acta Biomaterialia 7 (2011) 2264-2269) suggests that it is possible to correlate the glass transition temperature (T(g)) of bioactive glasses with their molar composition, based on iterative least-squares fitting of published T(g) data. However, we show that the glass structure is an important parameter in determining T(g). Phase separation, local structural effects and components (intermediate oxides) which can switch their structural role in the glass network need to be taken into consideration, as they are likely to influence the glass transition temperature of bioactive glasses. Although the model suggested by O'Donnell works reasonably well for glasses within the composition range presented, it is oversimplified and fails for glasses outside certain compositional boundaries. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  4. Analysis of the development and prediction of the rate of unemployment in selected countries with market and transitive economy

    Directory of Open Access Journals (Sweden)

    Erich Maca

    2004-01-01

    Full Text Available The paper is aimed at the presentation of findings achieved in the study of the dynamics and trends of the rate of unemployment in selected countries with market and transitive economy in the reference period 1995–2001. In addition to the description of developmental trends of analysed time series by means of trend functions of linear, quadratic, exponential, logarithmic, power and inverse types their informative ability was verified as a starting base for the realization of point prediction of investigated events for 2005. With given 95% probability, minimum and maximum values are determined of the evaluated macroeconomic indicator for a defined time horizon.

  5. Multiple nano elements of SCC--transition from phenomenology to predictive mechanistics

    International Nuclear Information System (INIS)

    Staehle, R.W.

    2009-01-01

    Full text of publication follows: Predicting the occurrence and rate of stress corrosion cracking in materials of construction is one of the most critical pathways for assuring the reliability of light water nuclear reactor plants. It is the general intention of operators of nuclear plants that they continue performing satisfactorily for times of 60 to 80 years at least. Such times are beyond existing experience, and there are no bases for choosing credible predictions. Present bases for predicting SCC rely on anecdotal experience for predicting what materials sustain SCC in specified environments and on phenomenological correlations using such parameters as K (stress intensity), 1/T (temperature), E(corr) (corrosion potential), pH, [x] a (concentration), other established quantities, and statistical correlations. While these phenomenological correlations have served the industry well in the past, they have also allowed grievous mistakes. Further, such correlations are flawed in their fundamental credibility. Predicting SCC in aqueous solutions means to predict its dependence upon the seven primary variables: potential, pH, species, alloy composition, alloy structure, stress and temperature. A serious prediction of SCC upon these seven primary variables can only be achieved by moving to fundamental nano elements. Unfortunately, useful predictability from the nano approach cannot be achieved quickly or easily; thus, it will continue to be necessary to rely on existing phenomenology. However, as the nano approach evolves, it can contribute increasingly to the quantitative capacity of the phenomenological approach. The nano approach will require quite different talents and thinking than are now applied to the prediction of SCC; while some of the boundary conditions of phenomenology must continue to be applied, elements of the nano approach will include accounting for at least, typically, the following multiple elements as they apply at the sites of initiation and at

  6. Tracer transport in fractured rocks

    International Nuclear Information System (INIS)

    Tsang, C.F.; Tsang, Y.W.; Hale, F.V.

    1988-07-01

    Recent interest in the safety of toxic waste underground disposal and nuclear waste geologic repositories has motivated many studies of tracer transport in fractured media. Fractures occur in most geologic formations and introduce a high degree of heterogeneity. Within each fracture, the aperture is not constant in value but strongly varying. Thus for such media, tracer tends to flow through preferred flowpaths or channels within the fractures. Along each of these channels, the aperture is also strongly varying. A detailed analysis is carried out on a 2D single fracture with variable apertures and the flow through channels is demonstrated. The channels defined this way are not rigidly set pathways for tracer transport, but are the preferred flow paths in the sense of stream-tubes in the potential theory. It is shown that such variable-aperture channels can be characterized by an aperture probability distribution function, and not by the exact deterministic geometric locations. We also demonstrate that the 2D tracer transport in a fracture can be calculated by a model of a system of 1D channels characterized by this distribution function only. Due to the channeling character of tracer transport in fractured rock, random point measurements of tracer breakthrough curves may give results with a wide spread in value due to statistical fluctuations. The present paper suggests that such a wide spread can probably be greatly reduced by making line/areal (or multiple) measurements covering a few spatial correlation lengths. 13 refs., 11 figs., 1 tab

  7. Predicting glass-to-glass and liquid-to-liquid phase transitions in supercooled water using classical nucleation theory

    Science.gov (United States)

    Tournier, Robert F.

    2018-01-01

    Glass-to-glass and liquid-to-liquid phase transitions are observed in bulk and confined water, with or without applied pressure. They result from the competition of two liquid phases separated by an enthalpy difference depending on temperature. The classical nucleation equation of these phases is completed by this quantity existing at all temperatures, a pressure contribution, and an enthalpy excess. This equation leads to two homogeneous nucleation temperatures in each liquid phase; the first one (Tn- below Tm) being the formation temperature of an "ordered" liquid phase and the second one corresponding to the overheating temperature (Tn+ above Tm). Thermodynamic properties, double glass transition temperatures, sharp enthalpy and volume changes are predicted in agreement with experimental results. The first-order transition line at TLL = 0.833 × Tm between fragile and strong liquids joins two critical points. Glass phase above Tg becomes "ordered" liquid phase disappearing at TLL at low pressure and at Tn+ = 1.302 × Tm at high pressure.

  8. Interpretation of Water Tracer Simulation in the H-1 Segment of the Gullfaks Field

    Energy Technology Data Exchange (ETDEWEB)

    Moid, Farrukh

    2000-07-01

    This thesis describes the water tracer simulation in the H-1 segment of the Gullfaks field. Three passive water tracer slugs were injected from the two producing wells during water flooding, pressure maintenance and reservoir monitoring program in the Gullfaks field. The same program is considered in this thesis. Computer Modelling Group's (CMG) simulator STARS is used for the general reservoir simulation and a separate module for tracer flow (ITRC-SIM) which is incorporated in the STARS and developed at Institute For Energy (IFE) is used for the tracer simulation. Water cut and tracer concentration data are used in history matching of the field. History matching is performed by changing the transmissibility and permeability of different layers; also the effect of changing saturations near the well bore on history matching is examined. It is noted that water cut is sensitive to transmissibility of the layers and the saturation around the well bore. Tracers are found to be moving in the most permeable layers. The corresponding history matching of water and tracer production shows a severe loss of first tracer injected because of imbibition process. Water phase velocity and areal communication between different wells are determined. Advance numerical features of tracer module ITRC-SIM such as flux limiting scheme and grid refinement scheme are evaluated and are found to be an important tool for reducing the numerical smearing. The effects of dispersion and diffusion on tracer response curve are also evaluated. Dispersion makes the tracer concentration curve smeared. Simulation results of water cut and tracer concentration show a good history match for this reservoir. The improved simulation model and the tracer module for this reservoir can be used for the prediction of future performance of the reservoir and interpretation of the tracer behaviour in the reservoir. (author)

  9. Prediction of the transition energies of atomic No and Lr by the intermediate Hamiltonian coupled cluster method

    International Nuclear Information System (INIS)

    Borschevsky, A.; Eliav, E.; Kaldor, U.; Vilkas, M.J.; Ishikawa, Y.

    2007-01-01

    Complete text of publication follows: Measurements of the spectroscopic properties of the superheavy elements present a serious challenge to the experimentalist. Their short lifetimes and the low quantities of their production necessitate reliable prediction of transition energies to avoid the need for broad wavelength scans and to assist in identifying the lines. Thus, reliable high-accuracy calculations are necessary prior and parallel to experimental research. Nobelium and Lawrencium are at present the two most likely candidates for spectroscopic measurements, with the first experiments planned at GSI, Darmstadt. The intermediate Hamiltonian (IH) coupled cluster method is applied to the ionization potentials, electron affinities, and excitation energies of atomic nobelium and lawrencium. Large basis sets are used (37s31p26d21f16g11h6i). All levels of a particular atom are obtained simultaneously by diagonalizing the IH matrix. The matrix elements correspond to all excitations from correlated occupied orbitals to virtual orbitals in a large P space, and are 'dressed' by folding in excitations to higher virtual orbitals (Q space) at the coupled cluster singles-and-doubles level. Lamb-shift corrections are included. The same approach was applied to the lighter homologues of Lr and No, lutetium and ytterbium, for which many transition energies are experimentally known, in order to assess the accuracy of the calculation. The average absolute error of 20 excitation energies of Lu is 423 cm -1 , and the error limits for Lr are therefore put at 700 cm -1 . Predicted Lr excitations with large transition moments in the prime range for the planned experiment, 20,000-30,000 cm -1 , are 7p → 8s at 20,100 cm -1 and 7p →p 7d at 28,100 cm -1 . In case of Yb, the calculated ionization potential was within 20 cm -1 of the experiment, and the average error of the 20 lowest calculated excitations was about 300 cm -1 . Hence, the error limits of nobelium are set to 800 cm -1

  10. Predictive Power of Primary and Secondary School Success Criterion on Transition to Higher Education Examination Scores

    OpenAIRE

    Atilla ÖZDEMİR; Selahattin GELBAL

    2016-01-01

    It is seen that education has a significant effect that changes an individual’s life in our country in which education is a way of moving up the social ladder. In order to continue to a higher education program after graduating from high school, students have to succeed in transition to higher education examination. Thus, the entrance exam is an important factor to determine the future of the students. In our country, middle school grades and high school grade point average that is added to u...

  11. Density crosslink study of gamma irradiated LDPE predicted by gel-fraction, swelling and glass transition temperature characterization

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Moraes, Guilherme F.; Ono, Lilian S.; Parra, D.F.; Lugao, Ademar B.

    2011-01-01

    Experimental results showed that the crosslink density of polymeric stocks may be predicted from values of gel content based on the reactive portion of the stocks, that is, exclusive of plasticizers and fillers. Where entanglements may be neglected, the crosslink density is directly proportional to functions of the gel and sol contents. In order to predict the behavior of carbon-chain polymers exposed to ionizing radiation, an empirical rule can be used. According to this rule, polymers containing a hydrogen atom at each carbon atom predominantly undergo crosslinking. During irradiation, chain scission occurs simultaneously and competitively with crosslinking, the end result being determined by the ratio of the yields of the two reactions. The ratio of crosslinking to scission depends basically on factors including total irradiation dose, dose rate and the presence of oxygen. The glass transition temperature (Tg), temperature below which the polymer segments do not have sufficient energy to move past one another, marks the onset of segmental mobility for a polymer. Properties such as melt index, melt strength, crystallinity, glass transition, gel fraction, swelling ratio and elasticity modulus were assessed in LDPE (2.6 g.10 min -1 melt index) gamma irradiated within a 10, 15, 20 and 30 kGy and results obtained were further discussed prior conclusion. (author)

  12. Network-based model for predicting the effect of fuel price on transit ridership and greenhouse gas emissions

    Directory of Open Access Journals (Sweden)

    Michael W. Levin

    2017-12-01

    Full Text Available As fuel prices increase, drivers may make travel choices to minimize not only travel time, but also fuel consumption. Consideration of fuel consumption would affect route choice and influence trip frequency and mode choice. For instance, travelers may elect to live closer to their workplace, or use public transit to avoid fuel consumption and the associated costs. To incorporate network characteristics into predictions of the effects of fuel prices, we develop a multi-class combined elastic demand, mode choice, and user equilibrium model using a generalized cost function of travel time and fuel consumption with a combined solution algorithm. The algorithm is implemented in a custom software package, and a case study application on the Austin, Texas network is presented. We evaluate the fuel-price sensitivity of key variables such as drive-alone and transit class proportions, person-miles traveled, link-level traffic flow and per capita fuel consumption and emissions. These effects are examined across a heterogeneous demand set, with multiple user-classes categorized based on their value of travel time. The highest relative transit elasticities against fuel price are observed among low value of time classes, as expected. Although total personal vehicle travel decreases, congestion increases on some roads due to the generalized cost function. Reductions in system-wide fuel consumption and greenhouse gas emissions are observed as well. The study uncovers the combined interactions among fuel prices, multi-modal choice behavior, travel performance, and resultant environmental impacts, all of which dictate the urban travel market. It also equips agencies with motivation to tailor emissions reduction and transit-ridership stimulus policies around the most responsive user classes.

  13. Predicting the Transition From Acute Stress Disorder to Posttraumatic Stress Disorder in Children With Severe Injuries.

    Science.gov (United States)

    Brown, Ruth C; Nugent, Nicole R; Hawn, Sage E; Koenen, Karestan C; Miller, Alisa; Amstadter, Ananda B; Saxe, Glenn

    The purpose of this study was to examine predictors of risk for and the transition between acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) in a longitudinal sample of youth with severe injuries admitted to the hospital. These data would assist with treatment and discharge planning. Youth were assessed for ASD during the initial hospital stay and were followed-up over an 18-month period for PTSD (n = 151). Youth were classified into four groups, including Resilient (ASD-, PTSD-), ASD Only (ASD+, PTSD-), PTSD Only (ASD-, PTSD+), and Chronic (ASD+, PTSD+). Demographic, psychiatric, social context, and injury-related factors were examined as predictors of diagnostic transition. The results of multivariate analysis of variance and pairwise comparisons found that peritraumatic dissociation, gender, and socioeconomic status were significant predictors after controlling for multiple testing. Results suggest that both within-child and contextual factors contribute to the longitudinal response to trauma in children. Clinicians should consider early screening and discharge planning, particularly for children most at risk. Copyright © 2016 National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved.

  14. Consumer-resource theory predicts dynamic transitions between outcomes of interspecific interactions

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.

    2009-01-01

    Interactions between two populations are often defined by their interaction outcomes; that is, the positive, neutral, or negative effects of species on one another. Yet, signs of outcomes are not absolute, but vary with the biotic and abiotic contexts of interactions. Here, we develop a general theory for transitions between outcomes based on consumer-resource (C-R) interactions in which one or both species exploit the other as a resource. Simple models of C-R interactions revealed multiple equilibria, including one for species coexistence and others for extinction of one or both species, indicating that species densities alone could determine the fate of interactions. All possible outcomes (+ +), (+ -), (- -), (+ 0), (- 0), (0 0) of species coexistence emerged merely through changes in parameter values of C-R interactions, indicating that variation in C-R interactions resulting from biotic and abiotic conditions could determine shifts in outcomes. These results suggest that C-R interactions can provide a broad mechanism for understanding context- and density-dependent transitions between interaction outcomes.

  15. Compilation and analyses of results from cross-hole tracer tests with conservative tracers

    Energy Technology Data Exchange (ETDEWEB)

    Hjerne, Calle; Nordqvist, Rune; Harrstroem, Johan (Geosigma AB (Sweden))

    2010-09-15

    Radionuclide transport in hydrogeological formations is one of the key factors for the safety analysis of a future repository of nuclear waste. Tracer tests have therefore been an important field method within the SKB investigation programmes at several sites since the late 1970's. This report presents a compilation and analyses of results from cross-hole tracer tests with conservative tracers performed within various SKB investigations. The objectives of the study are to facilitate, improve and reduce uncertainties in predictive tracer modelling and to provide supporting information for SKB's safety assessment of a final repository of nuclear waste. More specifically, the focus of the report is the relationship between the tracer mean residence time and fracture hydraulic parameters, i.e. the relationship between mass balance aperture and fracture transmissivity, hydraulic diffusivity and apparent storativity. For 74 different combinations of pumping and injection section at six different test sites (Studsvik, Stripa, Finnsjoen, Aespoe, Forsmark, Laxemar), estimates of mass balance aperture from cross-hole tracer tests as well as transmissivity were extracted from reports or in the SKB database Sicada. For 28 of these combinations of pumping and injection section, estimates of hydraulic diffusivity and apparent storativity from hydraulic interference tests were also found. An empirical relationship between mass balance aperture and transmissivity was estimated, although some uncertainties for individual data exist. The empirical relationship between mass balance aperture and transmissivity presented in this study deviates considerably from other previously suggested relationships, such as the cubic law and transport aperture as suggested by /Dershowitz and Klise 2002/, /Dershowitz et al. 2002/ and /Dershowitz et al. 2003/, which also is discussed in this report. No clear and direct empirical relationship between mass balance aperture and hydraulic

  16. Field measurements of tracer gas transport by barometric pumping

    International Nuclear Information System (INIS)

    Lagus, P.L.; McKinnis, W.B.; Hearst, J.R.; Burkhard, N.R.; Smith, C.F.

    1994-01-01

    Vertical gas motions induced by barometric pressure variations can carry radioactive gases out of the rubblized region produced by an underground nuclear explosion, through overburden rock, into the atmosphere. To better quantify transit time and amount of transport, field experiments were conducted at two sites on Pahute Mesa, Kapelli and Tierra, where radioactive gases had been earlier detected in surface cracks. At each site, two tracer gases were injected into the rubblized chimney 300-400 m beneath the surface and their arrival was monitored by concentration measurements in gas samples extracted from shallow collection holes. The first ''active'' tracer was driven by a large quantity of injected air; the second ''passive'' tracer was introduced with minimal gas drive to observe the natural transport by barometric pumping. Kapelli was injected in the fall of 1990, followed by Tierra in the fall of 1991. Data was collected at both sites through the summer of 1993. At both sites, no surface arrival of tracer was observed during the active phase of the experiment despite the injection of several million cubic feet of air, suggesting that cavity pressurization is likely to induce horizontal transport along high permeability layers rather than vertical transport to the surface. In contrast, the vertical pressure gradients associated with barometric pumping brought both tracers to the surface in comparable concentrations within three months at Kapelli, whereas 15 months elapsed before surface arrival at Tierra. At Kapelli, a quasisteady pumping regime was established, with tracer concentrations in effluent gases 1000 times smaller than concentrations thought to exist in the chimney. Tracer concentrations observed at Tierra were typically an order of magnitude smaller. Comparisons with theoretical calculations suggest that the gases are traveling through ∼1 millimeter vertical fractures spaced 2 to 4 meters apart. 6 refs., 18 figs., 3 tabs

  17. Assessing preferential flow by simultaneously injecting nanoparticle and chemical tracers

    KAUST Repository

    Subramanian, S. K.; Li, Yan; Cathles, L. M.

    2013-01-01

    The exact manner in which preferential (e.g., much faster than average) flow occurs in the subsurface through small fractures or permeable connected pathways of other kinds is important to many processes but is difficult to determine, because most chemical tracers diffuse quickly enough from small flow channels that they appear to move more uniformly through the rock than they actually do. We show how preferential flow can be assessed by injecting 2 to 5 nm carbon particles (C-Dots) and an inert KBr chemical tracer at different flow rates into a permeable core channel that is surrounded by a less permeable matrix in laboratory apparatus of three different designs. When the KBr tracer has a long enough transit through the system to diffuse into the matrix, but the C-Dot tracer does not, the C-Dot tracer arrives first and the KBr tracer later, and the separation measures the degree of preferential flow. Tracer sequestration in the matrix can be estimated with a Peclet number, and this is useful for experiment design. A model is used to determine the best fitting core and matrix dispersion parameters and refine estimates of the core and matrix porosities. Almost the same parameter values explain all experiments. The methods demonstrated in the laboratory can be applied to field tests. If nanoparticles can be designed that do not stick while flowing through the subsurface, the methods presented here could be used to determine the degree of fracture control in natural environments, and this capability would have very wide ranging value and applicability.

  18. Measurement of open streams by using tracers

    International Nuclear Information System (INIS)

    Ramos, German F.; Tarquino, W.; Curcuy, H.; Orozco, C.

    1999-01-01

    This paper presents an intercomparison study to be carried out between flux measurements by using tracers and moulinet. This intercomparison is scheduled to be performed at the measurement station belonging to the National Service of Meteorology and Hydrology (SENAMHI). Two techniques of tracer dilution are outstanded: total evaluation with tracer punctual injection and punctual evaluation with tracer continuous injection. Total evaluation with tracer punctual injection has been used since this technique is considered to be more suitable for hydrology purposes

  19. A Predictive Metabolic Signature for the Transition From Gestational Diabetes Mellitus to Type 2 Diabetes

    DEFF Research Database (Denmark)

    Allalou, Amina; Nalla, Amarnadh; Prentice, Kacey J

    2016-01-01

    to non-case patients by age, prepregnancy BMI, and race/ethnicity. We conducted metabolomics with baseline fasting plasma and identified 21 metabolites that significantly differed by incident T2D status. Machine learning optimization resulted in a decision tree modeling that predicted T2D incidence...

  20. Prediction error demarcates the transition from retrieval, to reconsolidation, to new learning

    NARCIS (Netherlands)

    Sevenster, Dieuwke|info:eu-repo/dai/nl/375491104; Beckers, Tom; Kindt, Merel

    2014-01-01

    Although disrupting reconsolidation is promising in targeting emotional memories, the conditions under which memory becomes labile are still unclear. The current study showed that post-retrieval changes in expectancy as an index for prediction error may serve as a read-out for the underlying

  1. Colorectal cancer intrinsic subtypes predict chemotherapy benefit, deficient mismatch repair and epithelial-to-mesenchymal transition

    NARCIS (Netherlands)

    Roepman, P.; Schlicker, A.; Tabernero, J.; Majewski, I.; Tian, S.; Moreno, V.; Snel, M.H.; Chresta, C.M.; Rosenberg, R.; Nitsche, U.; Macarulla, T.; Capella, G.; Salazar, R.; Orphanides, G.; Wessels, L.F.A.; Bernards, R.; Simon, I.M.

    2013-01-01

    In most colorectal cancer (CRC) patients, outcome cannot be predicted because tumors with similar clinicopathological features can have differences in disease progression and treatment response. Therefore, a better understanding of the CRC biology is required to identify those patients who will

  2. The use of synthetic colloids in tracer transport experiments in saturated rock fractures

    International Nuclear Information System (INIS)

    Reimus, P.W.

    1995-08-01

    Studies of groundwater flow and contaminant transport in saturated, fractured geologic media are of great interest to researchers studying the potential long-term storage of hazardous wastes in or near such media. A popular technique for conducting such studies is to introduce tracers having different chemical and physical properties into a system and then observe the tracers at one or more downstream locations, inferring flow and transport mechanisms from the breakthrough characteristics of the different tracers. Many tracer studies have been conducted in saturated, fractured media to help develop and/or refine models capable of predicting contaminant transport over large scales in such media

  3. Possible User-Dependent CFD Predictions of Transitional Flow in Building Ventilation

    DEFF Research Database (Denmark)

    Peng, Lei; Nielsen, Peter Vilhelm; Wang, Xiaoxue

    2016-01-01

    A modified backward-facing step flow with a large expansion ratio of five (5) was modelled by 19 teams without benchmark solutions or experimental data for validation in an ISHVAC-COBEE July 2015 Tianjin Workshop, entitled as “to predict low turbulent flow”. Different computational fluid dynamics...... (CFD) codes/software, turbulence models, boundary conditions, numerical schemes and convergent criteria were adopted based on the own CFD experience of each participating team. The largest coefficient of variation is larger than 50% and the largest relative maximum difference of penetration length......, is shown to be still a very challenging task. This calls for a solid approach of validation and uncertainty assessment in CFD “experiments”. The users are recommended to follow an existing guideline of uncertainty assessment of CFD predictions to minimize the errors and uncertainties in the future....

  4. Development and Validation of Water Vapor Tracers as Diagnostics for the Atmospheric Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. The formulation of the sources and sinks of tracer water is generally proportional to the prognostic water vapor variable. Because all water has been accounted for in tracers, the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The tracers have been implemented in a GEOS General Circulation Model (GCM) simulation consisting of several summer periods to determine the source regions of precipitation for the United States and India. The recycling of water and interannual variability of the sources of water will be examined. Potential uses in GCM sensitivity studies, predictability studies and data assimilation will be discussed.

  5. Radioactive tracers in the sea

    International Nuclear Information System (INIS)

    Jenkins, W.J.; Livingston, H.D.

    1980-01-01

    Artificial radionuclides introduced to the oceans during the last four decades have proved invaluable tools for study of many processes in marine water columns and sediments. Both global and close-in fallout of radioactivity from atmospheric nuclear weapons testing have distributed these radionuclides widely, and in amounts sufficient to be useful as tracers. An additional source of considerable significance and tracer potential comes from coastal discharges of European nuclear fuel reprocessing wastes. The nature of these sources, types and amounts of radionuclides introduced and the time histories of their introduction generate a variety of tracer distributions which illuminate a broad spectrum of physical and chemical processes active over a wide range of timescales. Depending on their respective chemistries, artificial radionuclides have been demonstrated to exhibit both conservative and non-conservative properties in the oceans. Some examples are given of the uses made of soluble, conservative tracers for the study of oceanic transport processes and of non-conservative tracers for studies of processes which move them to, and mix them within, marine sediments. Sampling and measurement techniques which have been used in these studies are described

  6. In silico prediction of nematic transition temperature for liquid crystals using quantitative structure-property relationship approaches.

    Science.gov (United States)

    Fatemi, Mohammad Hossein; Ghorbanzad'e, Mehdi

    2009-11-01

    Quantitative structure-property relationship models for the prediction of the nematic transition temperature (T (N)) were developed by using multilinear regression analysis and a feedforward artificial neural network (ANN). A collection of 42 thermotropic liquid crystals was chosen as the data set. The data set was divided into three sets: for training, and an internal and external test set. Training and internal test sets were used for ANN model development, and the external test set was used for evaluation of the predictive power of the model. In order to build the models, a set of six descriptors were selected by the best multilinear regression procedure of the CODESSA program. These descriptors were: atomic charge weighted partial negatively charged surface area, relative negative charged surface area, polarity parameter/square distance, minimum most negative atomic partial charge, molecular volume, and the A component of moment of inertia, which encode geometrical and electronic characteristics of molecules. These descriptors were used as inputs to ANN. The optimized ANN model had 6:6:1 topology. The standard errors in the calculation of T (N) for the training, internal, and external test sets using the ANN model were 1.012, 4.910, and 4.070, respectively. To further evaluate the ANN model, a crossvalidation test was performed, which produced the statistic Q (2) = 0.9796 and standard deviation of 2.67 based on predicted residual sum of square. Also, the diversity test was performed to ensure the model's stability and prove its predictive capability. The obtained results reveal the suitability of ANN for the prediction of T (N) for liquid crystals using molecular structural descriptors.

  7. Predicting change in symptoms of depression during the transition to university: the roles of BDNF and working memory capacity.

    Science.gov (United States)

    LeMoult, Joelle; Carver, Charles S; Johnson, Sheri L; Joormann, Jutta

    2015-03-01

    Studies on depression risk emphasize the importance of both cognitive and genetic vulnerability factors. The present study has provided the first examination of whether working memory capacity, the BDNF Val66Met polymorphism, and their interaction predict changes in symptoms of depression during the transition to university. Early in the semester, students completed a self-report measure of depressive symptoms and a modified version of the reading span task to assess working memory capacity in the presence of both neutral and negative distractors. Whole blood was genotyped for the BDNF Val66Met polymorphism. Students returned at the end of the semester to complete additional self-report questionnaires. Neither working memory capacity nor the BDNF Val66Met polymorphism predicted change in depressive symptoms either independently or in interaction with self-reported semester difficulty. The BDNF Val66Met polymorphism, however, moderated the association between working memory capacity and symptom change. Among met carriers, lower working memory capacity in the presence of negative-but not neutral-distractors was associated with increased symptoms of depression over the semester. For the val/val group, working memory capacity did not predict symptom change. These findings contribute directly to biological and cognitive models of depression and highlight the importance of examining Gene × Cognition interactions when investigating risk for depression.

  8. Pulse Rate and Transit Time Analysis to Predict Hypotension Events After Spinal Anesthesia During Programmed Cesarean Labor.

    Science.gov (United States)

    Bolea, Juan; Lázaro, Jesús; Gil, Eduardo; Rovira, Eva; Remartínez, José M; Laguna, Pablo; Pueyo, Esther; Navarro, Augusto; Bailón, Raquel

    2017-09-01

    Prophylactic treatment has been proved to reduce hypotension incidence after spinal anesthesia during cesarean labor. However, the use of pharmacological prophylaxis could carry out undesirable side-effects on mother and fetus. Thus, the prediction of hypotension becomes an important challenge. Hypotension events are hypothesized to be related to a malfunctioning of autonomic nervous system (ANS) regulation of blood pressure. In this work, ANS responses to positional changes of 51 pregnant women programmed for a cesarean labor were explored for hypotension prediction. Lateral and supine decubitus, and sitting position were considered while electrocardiographic and pulse photoplethysmographic signals were recorded. Features based on heart rate variability, pulse rate variability (PRV) and pulse transit time (PTT) analysis were used in a logistic regression classifier. The results showed that PRV irregularity changes, assessed by approximate entropy, from supine to lateral decubitus, and standard deviation of PTT in supine decubitus were found as the combination of features that achieved the best classification results sensitivity of 76%, specificity of 70% and accuracy of 72%, being normotensive the positive class. Peripheral regulation and blood pressure changes, measured by PRV and PTT analysis, could help to predict hypotension events reducing prophylactic side-effects in the low-risk population.

  9. A comparison of measurements and calculations for the Stripa tracer experiments

    International Nuclear Information System (INIS)

    Hodgkinson, D.P.; Copper, N.S.

    1992-03-01

    This paper presents a comparison of measurements and predictions for migration of tracers from boreholes to the validation drift and to other boreholes in the Site Characterisation and Validation (SCV) block. The comparison was carried out on behalf of the Stripa task force on fracture flow modelling. The paper summarises the radar/saline tracer experiments, the tracer migration experiment observations and reviews the fracture flow and tracer transport modelling approaches and predictions made by AEA Technology, Fracflow Consultants, Golder Associates and Lawrence Berkeley Laboratory. The predictions are compared with the observed breakthrough curves on the basis of the validation process and criteria defined by the task force. The results of all four modelling groups met the validation criteria, with the predictions of the tracer breakthrough concentrations and times being within an order of magnitude of the observations. Also the AEA and Golder approaches allow the spatial distribution of tracer breakthrough into the validation drift to be predicted and these predictions also showed reasonable accuracy. The successful completion of this project demonstrates the feasibility of discrete fracture flow and tracer transport modelling. (36 refs.) (au)

  10. Application of Semiempirical Methods to Transition Metal Complexes: Fast Results but Hard-to-Predict Accuracy.

    KAUST Repository

    Minenkov, Yury

    2018-05-22

    A series of semiempirical PM6* and PM7 methods has been tested in reproducing of relative conformational energies of 27 realistic-size complexes of 16 different transition metals (TMs). An analysis of relative energies derived from single-point energy evaluations on density functional theory (DFT) optimized conformers revealed pronounced deviations between semiempirical and DFT methods indicating fundamental difference in potential energy surfaces (PES). To identify the origin of the deviation, we compared fully optimized PM7 and respective DFT conformers. For many complexes, differences in PM7 and DFT conformational energies have been confirmed often manifesting themselves in false coordination of some atoms (H, O) to TMs and chemical transformations/distortion of coordination center geometry in PM7 structures. Despite geometry optimization with fixed coordination center geometry leads to some improvements in conformational energies, the resulting accuracy is still too low to recommend explored semiempirical methods for out-of-the-box conformational search/sampling: careful testing is always needed.

  11. STEADY STATE DUST DISTRIBUTIONS IN DISK VORTICES: OBSERVATIONAL PREDICTIONS AND APPLICATIONS TO TRANSITIONAL DISKS

    International Nuclear Information System (INIS)

    Lyra, Wladimir; Lin, Min-Kai

    2013-01-01

    The Atacama Large Millimeter Array has returned images of transitional disks in which large asymmetries are seen in the distribution of millimeter sized dust in the outer disk. The explanation in vogue borrows from the vortex literature and suggests that these asymmetries are the result of dust trapping in giant vortices, excited via Rossby wave instabilities at planetary gap edges. Due to the drag force, dust trapped in vortices will accumulate in the center and diffusion is needed to maintain a steady state over the lifetime of the disk. While previous work derived semi-analytical models of the process, in this paper we provide analytical steady-steady solutions. Exact solutions exist for certain vortex models. The solution is determined by the vortex rotation profile, the gas scale height, the vortex aspect ratio, and the ratio of dust diffusion to gas-dust friction. In principle, all of these quantities can be derived from observations, which would validate the model and also provide constrains on the strength of the turbulence inside the vortex core. Based on our solution, we derive quantities such as the gas-dust contrast, the trapped dust mass, and the dust contrast at the same orbital location. We apply our model to the recently imaged Oph IRS 48 system, finding values within the range of the observational uncertainties

  12. Prediction of Intrinsic Ferromagnetic Ferroelectricity in a Transition-Metal Halide Monolayer

    Science.gov (United States)

    Huang, Chengxi; Du, Yongping; Wu, Haiping; Xiang, Hongjun; Deng, Kaiming; Kan, Erjun

    2018-04-01

    The realization of multiferroics in nanostructures, combined with a large electric dipole and ferromagnetic ordering, could lead to new applications, such as high-density multistate data storage. Although multiferroics have been broadly studied for decades, ferromagnetic ferroelectricity is rarely explored, especially in two-dimensional (2D) systems. Here we report the discovery of 2D ferromagnetic ferroelectricity in layered transition-metal halide systems. On the basis of first-principles calculations, we reveal that a charged CrBr3 monolayer exhibits in-plane multiferroicity, which is ensured by the combination of orbital and charge ordering as realized by the asymmetric Jahn-Teller distortions of octahedral Cr - Br6 units. As an example, we further show that (CrBr3)2Li is a ferromagnetic ferroelectric multiferroic. The explored phenomena and mechanism of multiferroics in this 2D system not only are useful for fundamental research in multiferroics but also enable a wide range of applications in nanodevices.

  13. The role of the dendritic growth model dimensionality in predicting the Columnar to Equiaxed Transition (CET)

    Science.gov (United States)

    Seredyński, M.; Rebow, M.; Banaszek, J.

    2017-06-01

    The dendrite tip kinetics model accuracy relies on the reliability of the stability constant used, which is usually experimentally determined for 3D situations and applied to 2D models. The paper reports authors` attempts to cure the situation by deriving 2D dendritic tip scaling parameter for aluminium-based alloy: Al-4wt%Cu. The obtained parameter is then incorporated into the KGT dendritic growth model in order to compare it with the original 3D KGT counterpart and to derive two-dimensional and three-dimensional versions of the modified Hunt's analytical model for the columnar-to-equiaxed transition (CET). The conclusions drawn from the above analysis are further confirmed through numerical calculations of the two cases of Al-4wt%Cu metallic alloy solidification using the front tracking technique. Results, including the porous zone-under-cooled liquid front position, the calculated solutal under-cooling, the average temperature gradient at a front of the dendrite tip envelope and a new predictor of the relative tendency to form an equiaxed zone, are shown, compared and discussed for two numerical cases. The necessity to calculate sufficiently precise values of the tip scaling parameter in 2D and 3D is stressed.

  14. Radiochemical tracers in marine biology

    International Nuclear Information System (INIS)

    Petrocelli, S.R.; Anderson, J.W.; Neff, J.M.

    1977-01-01

    Tracers have been used in a great variety of experimentation. More recently, labeled materials have been applied in marine biological research. Some of the existing tracer techniques have been utilized directly, while others have been modified to suit the specific needs of marine biologists. This chapter describes some of the uses of tracers in marine biological research. It also mentions the problems encountered as well as offering possible solutions and discusses further applications of these techniques. Only pertinent references are cited and additional information may be obtained by consulting these references. Due to their relative ease of maintenance, freshwater species are also utilized in studies which involve radiotracer techniques. Since most of these techniques e directly applicable to marine species, some of these studies will also be included

  15. Radioisotope tracer applications in industry

    International Nuclear Information System (INIS)

    Rao, S.M.

    1987-01-01

    Radioisotope tracers have many advantages in industrial trouble-shooting and studies on process kinetics. The applications are mainly of two types: one leading to qualitative (Yes or No type) information and the other to quantitative characterisation of flow processes through mass balance considerations and flow models. ''Yes or No'' type methods are mainly used for leakage and blockage locations in pipelines and in other industrial systems and also for location of water seepage zones in oil wells. Flow measurements in pipelines and mercury inventory in electrolytic cells are good examples of tracer methods using the mass balance approach. Axial dispersion model and Tanks-in-Series model are the two basic flow models commonly used with tracer methods for the characterisation of kinetic processes. Examples include studies on flow processes in sugar crystallisers as well as in a precalcinator in a cement plant. (author). 18 figs

  16. Standard Guide for Predicting Radiation-Induced Transition Temperature Shift in Reactor Vessel Materials, E706 (IIF)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This guide presents a method for predicting reference transition temperature adjustments for irradiated light-water cooled power reactor pressure vessel materials based on Charpy V-notch 30-ftlbf (41-J) data. Radiation damage calculative procedures have been developed from a statistical analysis of an irradiated material database that was available as of May 2000. The embrittlement correlation used in this guide was developed using the following variables: copper and nickel contents, irradiation temperature, and neutron fluence. The form of the model was based on current understanding for two mechanisms of embrittlement: stable matrix damage (SMD) and copper-rich precipitation (CRP); saturation of copper effects (for different weld materials) was included. This guide is applicable for the following specific materials, copper, nickel, and phosphorus contents, range of irradiation temperature, and neutron fluence based on the overall database: 1.1.1 MaterialsA 533 Type B Class 1 and 2, A302 Grade B, A302 G...

  17. Efficacy of obesity indices and age in predicting diabetes: study on a transitional tribe of Northeast India.

    Science.gov (United States)

    Mungreiphy, N K; Kapoor, Satwanti

    2014-01-01

    To evaluate the association between blood sugar level and obesity, and the interplay of socioeconomic change, and to investigate the efficacy of different obesity indices and age in predicting diabetes. Cross-sectional study was carried out among 603 adult Tangkhul Nagas of NE India. Anthropometric measurements, random blood sugar level, general and regional obesity indices were evaluated along with their information on socioeconomic and lifestyle factors. Socioeconomic change observed among the Tangkhuls influence the rise of overweight/obesity and blood sugar level. Obesity and elevated blood sugar level were highly prevalent and interrelated. Diabetes and obesity were also found to be associated with age. Central obesity indices were highly associated with blood sugar level. Odds ratio showed the likelihood of developing prediabetes/diabetes among centrally obese participants. Correlation between blood sugar level, age and obesity indices showed that waist hip ratio had the highest correlation with blood sugar. It implies the higher reliability of central obesity than general obesity or age in determining blood sugar level. The transition of the Tangkhul Naga tribe in terms of socioeconomic and lifestyle factors contributes to the escalating prevalence of overweight/obesity and diabetes. The rising epidemic is not restricted to highly urbanized societies but now has penetrated even to traditional and transitional tribes owing to their changing lifestyle. Different facets of the complex associations between obesity, age, diabetes and socioeconomic change were observed. Central obesity indicator, waist hip ratio emerge as the paramount predictors of prediabetes/diabetes.

  18. Effect of tracer particles-quantized vortices interaction on PIV measurement result

    Science.gov (United States)

    Murakami, Masahide

    2014-01-01

    PIV (Particle Image Velocimeter) was applied to the measurement of He II thermal counterflow jet. However, the velocity measured with a PIV was smaller than the theoretical velocity of the normal component. Sergeev et al. explained that this was caused by the interaction between tracer particles and tangled mass of quantized vortices, and presented phenomenological formulae for the deceleration of particle motions in the two limiting cases of the vortex density. It is seen the present PIV experimental results qualitatively agree with the phenomenological formulae in the linear case of small or moderate values of heat input. The critical heat flux experimentally derived for the transition from the linear to non-linear regimes is found to be in fair agreement with the prediction.

  19. PChopper: high throughput peptide prediction for MRM/SRM transition design

    Directory of Open Access Journals (Sweden)

    Huang Jeffrey T-J

    2011-08-01

    Full Text Available Abstract Background The use of selective reaction monitoring (SRM based LC-MS/MS analysis for the quantification of phosphorylation stoichiometry has been rapidly increasing. At the same time, the number of sites that can be monitored in a single LC-MS/MS experiment is also increasing. The manual processes associated with running these experiments have highlighted the need for computational assistance to quickly design MRM/SRM candidates. Results PChopper has been developed to predict peptides that can be produced via enzymatic protein digest; this includes single enzyme digests, and combinations of enzymes. It also allows digests to be simulated in 'batch' mode and can combine information from these simulated digests to suggest the most appropriate enzyme(s to use. PChopper also allows users to define the characteristic of their target peptides, and can automatically identify phosphorylation sites that may be of interest. Two application end points are available for interacting with the system; the first is a web based graphical tool, and the second is an API endpoint based on HTTP REST. Conclusions Service oriented architecture was used to rapidly develop a system that can consume and expose several services. A graphical tool was built to provide an easy to follow workflow that allows scientists to quickly and easily identify the enzymes required to produce multiple peptides in parallel via enzymatic digests in a high throughput manner.

  20. Inelastic behavior of a dissimilar-metal-welded pipe transition joint: comparison of experimental measurements and analytical prediction

    International Nuclear Information System (INIS)

    Yang, T.M.; Dalcher, A.W.

    1979-06-01

    The subject study involved the prediction and observed behavior of a dissimilar metal pipe joint made from 2 1/4 Cr-1Mo steel welded to Type 316 austenitic stainless steel using a nickel-base filler metal, ERNiCr-3. A two-dimensional axi-symmetric finite element model was employed in the analysis, with certain assumptions made relative to the initial stress state of the joint. Internal pressure and thermal loadings which simulated the test conditions experienced by the joint, were used as inputs. Uni-axial stress-strain relationships and creep equations were applied to the multi-axial stress state through the concept of effective stress and equivalent strain. The analysis indicated that the loading history during the preparatory period (before acutal service) has a significant effect on the behavior of the transition joint in its early service life. The magnitudes of the stresses created at the vicinity of the dissimilar metal interfaces, mainly due to the differences in thermal expansions of the metals, are sufficient to yield the metals, and fast thermal down transients during service will induce more yielding of the metals before shakedown occurs. Calculated plastic ratchetting and creep responses of the joint metals were compared with ORNL strain measurements of the test joint. Very good agreement was shown to exist between the predictions and measurements

  1. Numerical prediction of local transitional features of turbulent forced gas flows in circular tubes with strong heating

    International Nuclear Information System (INIS)

    Ezato, Koichiro; Kunugi, Tomoaki; Shehata, A.M.; McEligot, D.M.

    1997-03-01

    Previous numerical simulation for the laminarization due to heating of the turbulent flow in pipe were assessed by comparison with only macroscopic characteristics such as heat transfer coefficient and pressure drop, since no experimental data on the local distributions of the velocity and temperature in such flow situation was available. Recently, Shehata and McEligot reported the first measurements of local distributions of velocity and temperature for turbulent forced air flow in a vertical circular tube with strongly heating. They carried out the experiments in three situations from turbulent flow to laminarizing flow according to the heating rate. In the present study, we analyzed numerically the local transitional features of turbulent flow evolving laminarizing due to strong heating in their experiments by using the advanced low-Re two-equation turbulence model. As the result, we successfully predicted the local distributions of velocity and temperature as well as macroscopic characteristics in three turbulent flow conditions. By the present study, a numerical procedure has been established to predict the local characteristics such as velocity distribution of the turbulent flow with large thermal-property variation and laminarizing flow due to strong heating with enough accuracy. (author). 60 refs

  2. Analysis of some laboratory tracer runs in natural fissures

    International Nuclear Information System (INIS)

    Moreno, L.; Neretnieks, I.

    1984-01-01

    Tracer tests in natural fissures performed in the laboratory are analysed by means of fitting two different models. In the experiments, sorbing and non-sorbing tracers were injected into a natural fissure running parallel to the axis of a drill core. The models take into account advection, diffusion into the rock matrix, sorption onto the rock surface and dispersion. For the last mechanism, one of the models considers hydrodynamic dispersion while the other model assumes channeling dispersion. The models take into account time delays in the inlet and outlet channels. The dispersion characteristics and water residence time were determined from the experiments with non-sorbing tracers. Surface and volume sorption coefficients and data on diffusion into the rock matrix were determined for the sorbing tracers. The results are compared with values independently determined in the laboratory. Good agreement was obtained using either model. When these models are used for prediction of tracer transport over larger distances, the results will depend on the model. The model with channeling dispersion will show a greater dispersion than the model with hydrodynamic dispersion. (author)

  3. Magnitude of the Suess Effect in North Atlantic - a Study of Foraminifera and Transient Tracer Simulations

    Science.gov (United States)

    Zhou, Y.; Oppo, D.; Gebbie, G.; Thornalley, D. J.

    2016-02-01

    The Suess Effect is the decrease of δ 13C in the atmosphere due to the burning of fossil fuels. The recent decrease in δ 13C in the deep sea due to uptake of carbon has been measured in samples taken on hydrographic surveys, although these surveys only provide snapshots of deep sea δ 13C. The long-term decrease in δ 13C has been estimated using modern hydrographic properties, but there are no direct measurements. Here we present records of δ 13C from benthic and planktonic foraminifera, collected south of Iceland in the North Atlantic Ocean. The cores have high accumulation rates and, based on radiocarbon, modern core tops. We find a monotonic decreasing trend since 1850 that is significant in two out of the three benthic records we have generated. A tracer simulation, with Transit Time Distribution and Equilibrium Time Distribution generated from previous tracer modeling studies, predicts a trend that is similar to our observations at the core sites. The presence of the Suess Effect in some of the cores is consistent with previous estimates on the uptake of anthropogenic CO{}2 in the newly formed North Atlantic Deep Water.

  4. CH{sup +} and SH{sup +} in the diffuse interstellar medium: Tracers of turbulent dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Edith, Falgarone; Maryvonne, Gerin; Massimo, De Luca [Observatoire de Paris and Ecole Normale Supérieure, Paris (France); Benjamin, Godard [Centro de Astrobiologia, CSIC-INTA, Madrid (Spain)

    2015-01-22

    Absorption spectroscopy performed with Herschel/HIFI against the dust continuum emission of bright galactic star-forming regions has allowed the detection of the ground-state transitions of several hydride cations, CH{sup +}, OH{sup +}, H{sub 2}O{sup +}, and SH{sup +} in the intervening diffuse medium. These hydrides, that need H{sub 2} to form but are also destroyed by H{sub 2}, appear to be most sensitive tracers of a poorly known component of the interstellar medium (ISM): molecular gas weakly shielded from UV radiation. Among them, because their formation routes are so highly endoenergic, the CH{sup +} and SH{sup +} cations are proposed to be specific tracers of turbulent dissipation occurring in diffuse gas. Their elusive origin in the diffuse ISM is therefore much more than a chemical riddle: it is rooted in the physics of the diffuse ISM, its turbulent dissipation rate and connects with the far broader issue of galaxy evolution. The Herschel/HIFI observations of CH{sup +} and SH{sup +} are compared with the predictions of chemical models that include the non-equilibrium effects of turbulent dissipation.

  5. CH+ and SH+ in the diffuse interstellar medium: Tracers of turbulent dissipation

    International Nuclear Information System (INIS)

    Edith, Falgarone; Maryvonne, Gerin; Massimo, De Luca; Benjamin, Godard

    2015-01-01

    Absorption spectroscopy performed with Herschel/HIFI against the dust continuum emission of bright galactic star-forming regions has allowed the detection of the ground-state transitions of several hydride cations, CH + , OH + , H 2 O + , and SH + in the intervening diffuse medium. These hydrides, that need H 2 to form but are also destroyed by H 2 , appear to be most sensitive tracers of a poorly known component of the interstellar medium (ISM): molecular gas weakly shielded from UV radiation. Among them, because their formation routes are so highly endoenergic, the CH + and SH + cations are proposed to be specific tracers of turbulent dissipation occurring in diffuse gas. Their elusive origin in the diffuse ISM is therefore much more than a chemical riddle: it is rooted in the physics of the diffuse ISM, its turbulent dissipation rate and connects with the far broader issue of galaxy evolution. The Herschel/HIFI observations of CH + and SH + are compared with the predictions of chemical models that include the non-equilibrium effects of turbulent dissipation

  6. Tracers of cancer cells in nuclear oncology

    International Nuclear Information System (INIS)

    Tamgac, F.; Baillet, G.; Moretti, J.L.; Safi, N.; Weinmann, P.; Beco, V. de

    1997-01-01

    Evaluating the extent of disease is important in planning cancer treatment. Different types of tracers are used in vivo to diagnose tumors and these tracers can give supplementary information on the differentiation degree of tumors and response to therapy. (authors)

  7. Applications of NASA and NOAA Satellite Observations by NASA's Short-term Prediction Research and Transition (SPoRT) Center in Response to Natural Disasters

    Science.gov (United States)

    Molthan, Andrew L.; Burks, Jason E.; McGrath, Kevin M.; Jedlovec, Gary J.

    2012-01-01

    NASA s Short-term Prediction Research and Transition (SPoRT) Center supports the transition of unique NASA and NOAA research activities to the operational weather forecasting community. SPoRT emphasizes real-time analysis and prediction out to 48 hours. SPoRT partners with NOAA s National Weather Service (NWS) Weather Forecast Offices (WFOs) and National Centers to improve current products, demonstrate future satellite capabilities and explore new data assimilation techniques. Recently, the SPoRT Center has been involved in several activities related to disaster response, in collaboration with NOAA s National Weather Service, NASA s Applied Sciences Disasters Program, and other partners.

  8. A volatile tracer-assisted headspace analytical technique for determining the swelling capacity of superabsorbent polymers.

    Science.gov (United States)

    Zhang, Shu-Xin; Jiang, Ran; Chai, Xin-Sheng

    2017-09-01

    This paper reports on a new method for the determination of swelling capacity of superabsorbent polymers by a volatile tracer-assisted headspace gas chromatography (HS-GC). Toluene was used as a tracer and added to the solution for polymers swelling test. Based on the differences of the tracer partitioned between the vapor and hydrogel phase before and after the polymer's swelling capacity, a transition point (corresponding to the material swelling capacity) can be observed when plotting the GC signal of toluene vs. the ratio of solution added to polymers. The present method has good precision (RSDpolymers at the elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. NASA's Earth Observing System: The Transition from Climate Monitoring to Climate Change Prediction

    Science.gov (United States)

    King, Michael D.; Herring, David D.

    1998-01-01

    Earth's 4.5 billion year history is a study in change. Natural geological forces have been rearranging the surface features and climatic conditions of our planet since its beginning. There is scientific evidence that some of these natural changes have not only led to mass extinctions of species (e.g., dinosaurs), but have also severely impacted human civilizations. For instance, there is evidence that a relatively sudden climate change caused a 300-year drought that contributed to the downfall of Akkadia, one of the most powerful empires in the Middle-East region around 2200 BC. More recently, the "little ice age" from 1200-1400 AD forced the Vikings to abandon Greenland when temperatures there dropped by about 1.5 C, rendering it too difficult to grow enough crops to sustain the population. Today, there is compelling scientific evidence that human activities have attained the magnitude of a geological force and are speeding up the rate of global change. For example, carbon dioxide levels have risen 30 percent since the industrial revolution and about 40 percent of the world's land surface has been transformed by humans. We don't understand the cause-and-effect relationships among Earth's land, ocean, and atmosphere well enough to predict what, if any, impacts these rapid changes will have on future climate conditions. We need to make many measurements all over the world, over a long period of time, in order to assemble the information needed to construct accurate computer models that will enable us to forecast climate change. In 1988, the Earth System Sciences Committee, sponsored by NASA, issued a report calling for an integrated, long-term strategy for measuring the vital signs of Earth's climate system. The report urged that the measurements must all be intimately coupled with focused process studies, they must facilitate development of Earth system models, and they must be stored in an information system that ensures open access to consistent, long-term data

  10. Precalving and early lactation factors that predict milk casein and fertility in the transition dairy cow.

    Science.gov (United States)

    Rodney, Rachael M; Hall, Jenianne K; Westwood, Charlotte T; Celi, Pietro; Lean, Ian J

    2016-09-01

    Multiparous Holstein cows (n=82) of either high or low genetic merit (GM) (for milk fat + protein yield) were allocated to 1 of 2 diets in a 2×2 factorial design. Diets differed in the ratio of rumen-undegradable protein (RUP) to rumen-degradable protein (37% RUP vs. 15% RUP) and were fed from 21 d precalving to 150 days in milk. This study evaluated the effects of these diets and GM on concentrations of milk casein (CN) variants and aimed to identify precalving and early lactation variables that predict milk CN and protein yield and composition and fertility of dairy cows. It explored the hypothesis that low milk protein content is associated with lower fertility and extended this hypothesis to also evaluate the association of CN contents with fertility. Yields (kg/d) for CN variants were 0.49 and 0.45 of α-CN, 0.38 and 0.34 of β-CN, 0.07 and 0.06 for κ-CN, and 0.10 and 0.09 of γ-CN for high- and low-RUP diets, respectively. Increased RUP increased milk, CN, and milk protein yields. Increased GM increased milk protein and γ-CN yields and tended to increase milk CN yield. The effects of indicator variables on CN variant yields and concentrations were largely consistent, with higher body weight and α-amino nitrogen resulting in higher yields, but lower concentrations. An increase in cholesterol was associated with decreased CN variant concentrations, and disease lowered CN variant yield. A diet high in RUP increased proportion of first services that resulted in pregnancy from 41 to 58%. Increased precalving metabolizable protein (MP) balance decreased the proportion of first services that resulted in pregnancy when evaluated in a model containing CN percentage, milk protein yield, diet, and GM. This finding suggests that the positive effects of increasing dietary RUP on fertility may be curvilinear because cows with a very positive MP balance before calving were less fertile than those with a lower, but positive, MP balance. Prepartum MP balance was important

  11. Variational predictions of transition energies and electron affinities: He and Li ground states and Li, Be, and Mg core-excited states

    International Nuclear Information System (INIS)

    Fischer, C.F.

    1990-01-01

    Variational procedures for predicting energy differences of many-electron systems are investigated. Several different calculations for few-electron systems are considered that illustrate the problems encountered when a many-electron system is modeled as a core plus outer electrons. It is shown that sequences of increasingly more accurate calculations for outer correlation may converge yielding wrong transition energies. At the same time, accurate core-polarization calculations overestimate the binding energy, requiring a core-valence correction. For the high-spin, core-excited states of Li, it was found that outer correlation only predicted electron affinities as accurately as full-correlation studies. This observation suggested a prediction of the core-excited 4 P endash 4 S transition in Be - , based on observed 3 P 0 endash 3 P transition energies of the neutral species, predicted electron affinities including only outer correlation, and a core-valence correction, that is shown to be in good agreement with experiment. A similar calculation for Mg - predicts a wavelength of 2895.1 A for this transition

  12. PREDICTING NORMATIVE AND PROBLEMATIC FAMILY PATHWAYS TO THE TRANSITION TO SIBLINGHOOD: COMMENTARY ON VOLLING ET AL.'S MONOGRAPH.

    Science.gov (United States)

    Howe, Nina

    2017-09-01

    Volling et al.'s monograph provides a rich, thoughtful, and rigorous account of how the transition to siblinghood is experienced by the first-born child and the family. In their comprehensive longitudinal study, they followed 241 families from the prenatal period before the second-born's birth until this child was 12-months old. Siblings are a critical, but understudied, relationship in children's development; the challenges posed in researching sibling dynamics in the context of the family are discussed. Prior psychodynamic and developmental research literature is critiqued, which places the current study into perspective and indicates the important theoretical frameworks (i.e., developmental psychopathology and developmental ecological systems) employed by Volling et al. to advance our understanding of this critical transition in the life of the family. The longitudinal study design, sample characteristics, identification of possible trajectories of adjustment (or not) to the birth of the sibling, and selection of family and child variables are addressed. The sophisticated statistical methods (Growth Mixture Modeling and data mining procedures) employed to predict child adjustment in association with parenting variables over time and sibling relationship quality at 12 months identified low- and high-risk trajectories on the seven subscales of the Child Behavior Check List (CBCL). This afforded a nuanced investigation of a variety of potentially problematic child behaviors (e.g., aggression, withdrawal, negative emotionality, somatic problems) in association with parenting behaviors. A final discussion included study limitations, significant strengths, and implications for clinicians and other professionals. The study's conclusion is that most children and families are resilient, take the birth of a sibling in their stride, and do not exhibit empirical evidence of a developmental crisis, as argued by earlier psychodynamic authors. © 2017 The Society for Research

  13. Troubles in the systematic prediction of transition metal thermochemistry with contemporary out-of-the-box methods

    KAUST Repository

    Minenkov, Yury

    2016-03-22

    The recently developed DLPNO-CCSD(T) method and 7 popular DFT functionals (B3LYP, M06, M06L, PBE, PBE0, TPSS and TPSSh) with and without an empirical dispersion term have been tested to reproduce 111 gas phase reaction enthalpies involving 11 different transition metals. Our calculations, corrected for both relativistic effects and basis set incompleteness, indicate that most of the methods applied with default settings perform with acceptable accuracy on average. Nevertheless, our calculations also evidenced unexpected and non systematic large deviations for specific cases. For group 12 metals (Zn, Cd, Hg) most of the methods provided mean unsigned errors (MUE) less than 5.0 kcal/mol, with DLPNO-CCSD(T) and PBE methods performing excellently (MUE lower 2.0 kcal/mol). Problems started with group 4 metals (Ti and Zr). Best performer for Zr complexes with a MUE of 1.8 kcal/mol, PBE0-D3, provides a MUE larger than 8 kcal/mol for Ti. DLPNO-CCSD(T) provides a reasonable MUE of 3.3 kcal/mol for Ti reactions, but gives MUE a larger than 14.4 kcal/mol for Zr complexes, with all the larger deviations for reactions involving ZrF4. Large and non-systematic errors have been obtained for group 6 metals (Mo and W), for 8 reactions containing Fe, Cu, Nb and Re complexes. Finally, for the whole set of 111 reactions, the DLPNO-CCSD(T), B3LYP-D3 and PBE0-D3 methods turned out to be the best performers, both providing MUE below 5.0 kcal/mol. Since DFT results cannot be systematically improved and large non-systematic deviations of 20-30 kcal/mol were obtained even for best performers, our results indicates that current DFT methods are still unable to provide robust predictions in transition metal thermochemistry, at least for the functionals explored in this work. The same conclusion holds for both DLPNO-CCSD(T) and canonical CCSD(T) methods when used entirely as out-of-the-box. However if careful investigation core correlation is performed, relativistic effects are properly included

  14. Tracer-tracer relations as a tool for research on polar ozone loss

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Rolf

    2010-07-01

    The report includes the following chapters: (1) Introduction: ozone in the atmosphere, anthropogenic influence on the ozone layer, polar stratospheric ozone loss; (2) Tracer-tracer relations in the stratosphere: tracer-tracer relations as a tool in atmospheric research; impact of cosmic-ray-induced heterogeneous chemistry on polar ozone; (3) quantifying polar ozone loss from ozone-tracer relations: principles of tracer-tracer correlation techniques; reference ozone-tracer relations in the early polar vortex; impact of mixing on ozone-tracer relations in the polar vortex; impact of mesospheric intrusions on ozone-tracer relations in the stratospheric polar vortex calculation of chemical ozone loss in the arctic in March 2003 based on ILAS-II measurements; (4) epilogue.

  15. New SPECT tracers: Example of tracers of proteoglycans and melanin

    International Nuclear Information System (INIS)

    Cachin, F.; Mestas, D.; Kelly, A.; Merlin, C.; Veyre, A.; Maublant, J.; Cachin, F.; Chezal, J.M.; Miot-Noirault, E.; Moins, N.; Auzeloux, P.; Vidal, A.; Bonnet-Duquennoy, M.; Boisgard, S.; D'Incan, M.; Madelmont, J.C.; Maublant, J.; Boisgard, S.; D'Incan, M.; Redini, F.; Filaire, M.

    2009-01-01

    The majority of research program on new radiopharmaceuticals turn to tracers used for positron emission tomography (PET). Only a few teams work on new non fluorine labeled tracers. However, the coming of SPECT/CT gamma cameras, the arrival of semi-conductors gamma cameras should boost the development of non-PET tracers. We exhibit in this article the experience acquired by our laboratory in the conception and design of two new non fluorine labelled compounds. The 99m Tc-N.T.P. 15-5 (N.T.P. 15-5 for N-[tri-ethyl-ammonium]-3-propyl-[15]ane-N5) which binds to proteoglycans could be used for the diagnosis and staging of osteoarthritis and chondrosarcoma. The iodo benzamides, specific to the melanin, are nowadays compared to 18 F-fluorodeoxyglucose in a phase III clinical trial for the diagnosis and detection of melanoma metastasis. Our last development focus on N-[2-(diethyl-amino)ethyl]-4 and 2-iodo benzamides respectively B.Z.A. and B.Z.A.2 hetero-aromatic analogues usable for melanoma treatment. (authors)

  16. Predicting a new phase (T'') of two-dimensional transition metal di-chalcogenides and strain-controlled topological phase transition

    Science.gov (United States)

    Ma, Fengxian; Gao, Guoping; Jiao, Yalong; Gu, Yuantong; Bilic, Ante; Zhang, Haijun; Chen, Zhongfang; Du, Aijun

    2016-02-01

    Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological phase transitions. Our findings greatly enrich the 2D families of transition metal dichalcogenides and offer a feasible way to control the electronic states of 2D topological insulators for the fabrication of high-speed spintronics devices.Single layered transition metal dichalcogenides have attracted tremendous research interest due to their structural phase diversities. By using a global optimization approach, we have discovered a new phase of transition metal dichalcogenides (labelled as T''), which is confirmed to be energetically, dynamically and kinetically stable by our first-principles calculations. The new T'' MoS2 phase exhibits an intrinsic quantum spin Hall (QSH) effect with a nontrivial gap as large as 0.42 eV, suggesting that a two-dimensional (2D) topological insulator can be achieved at room temperature. Most interestingly, there is a topological phase transition simply driven by a small tensile strain of up to 2%. Furthermore, all the known MX2 (M = Mo or W; X = S, Se or Te) monolayers in the new T'' phase unambiguously display similar band topologies and strain controlled topological

  17. Modelling tracer transport in fractured rock at Stripa

    International Nuclear Information System (INIS)

    Herbert, A.

    1992-01-01

    We present the results of a modelling study, making predictions for tracer transport experiments carried out within the H-zone feature in the Stripa mine. We use a direct fracture network approach to represent the system of interconnected flow-conducting fractures comprising this zone. It is a highly fractured granite, and our fracture-network models include up to 60000 fractures. We have had to develop efficient algorithms to calculate the flow and transport through these networks; these techniques are described and justified. The first stage of modelling addressed two saline injection experiments. The results of these were known to us and so in addition to 'predicting' the results of these experiments, we used them to calibrate a flow model of the experimental site. This model was then used to make true 'blind' predictions for a set of tracer experiments carried out in the natural head-field, caused by an open drift. Where our flow model was good, our predictions were found to be very accurate, explaining the dispersion in the tracer breakthrough in terms of the fracture network geometry. Discrepancies for experiments in less well characterised regions of the H-zone are presented, and we suggest that the errors in these predictions are a consequence of the inaccuracies of the flow-field. We have demonstrated the use of large-scale fracture network modelling. It has proved very successful, and made very accurate predictions of field experiments carried out at the Stripa mine. The measured dispersion of tracers can be accounted for by the geometry of the fracture network flow system. (14 refs.) (au)

  18. Fifty years of radiochemical tracers

    International Nuclear Information System (INIS)

    Evans, E.A.

    1992-01-01

    During the past 50 years radiochemical tracers, usually in the form of isotopically labelled organic compounds, have been essential tools to further advance our knowledge at the frontiers of a great variety of scientific developments in the life sciences. This plenary lecture reviews necessarily selected highlights in the synthesis and applications of such radiochemical tracers. Included are examples where important advances, made possible by using radiochemicals, have contributed to improving the quality of life on this planet. The principal radioisotopes involved, 14 C, 3 H, 35 S, 32 P, 125 I, are all relatively safe to handle and are commercially available at maximum theoretical specific activity (carrier free). The compounds labeled with these radioisotopes are used in many fields of research which include biosynthesis and biotechnology studies, cell biology, drug metabolism, clinical research and environmental applications, and are briefly reviewed. (author). 55 refs

  19. Tracer techniques in food industry

    International Nuclear Information System (INIS)

    Pertsovskij, E.S.; Sakharov, Eh.V.; Dolinin, V.A.

    1980-01-01

    The appicability of radioactive tracer techniques to process control in food industry are considered. Investigations in the field of food industry carried out using the above method are classified. The 1 class included investigations with preliminary preparation of a radioactive indicator and its following introduction in the system studied. The 2 class includes investigations based on the introduction in the system studied of a non-active indicator which is activated in a neutron flux being in samples selected in or after the process investigated. The 3 class includes studies based on investigations of natural radioactivity of certain nuclides in food stuff. The application of tracer techniques to the above classes of investigations in various fields of food industry and the equipment applied are considered in detail [ru

  20. JPSS Proving Ground Activities with NASA's Short-term Prediction Research and Transition (SPoRT) Center

    Science.gov (United States)

    Schultz, L. A.; Smith, M. R.; Fuell, K.; Stano, G. T.; LeRoy, A.; Berndt, E.

    2015-12-01

    Instruments aboard the Joint Polar Satellite System (JPSS) series of satellites will provide imagery and other data sets relevant to operational weather forecasts. To prepare current and future weather forecasters in application of these data sets, Proving Ground activities have been established that demonstrate future JPSS capabilities through use of similar sensors aboard NASA's Terra and Aqua satellites, and the S-NPP mission. As part of these efforts, NASA's Short-term Prediction Research and Transition (SPoRT) Center in Huntsville, Alabama partners with near real-time providers of S-NPP products (e.g., NASA, UW/CIMSS, UAF/GINA, etc.) to demonstrate future capabilities of JPSS. This includes training materials and product distribution of multi-spectral false color composites of the visible, near-infrared, and infrared bands of MODIS and VIIRS. These are designed to highlight phenomena of interest to help forecasters digest the multispectral data provided by the VIIRS sensor. In addition, forecasters have been trained on the use of the VIIRS day-night band, which provides imagery of moonlit clouds, surface, and lights emitted by human activities. Hyperspectral information from the S-NPP/CrIS instrument provides thermodynamic profiles that aid in the detection of extremely cold air aloft, helping to map specific aviation hazards at high latitudes. Hyperspectral data also support the estimation of ozone concentration, which can highlight the presence of much drier stratospheric air, and map its interaction with mid-latitude or tropical cyclones to improve predictions of their strengthening or decay. Proving Ground activities are reviewed, including training materials and methods that have been provided to forecasters, and forecaster feedback on these products that has been acquired through formal, detailed assessment of their applicability to a given forecast threat or task. Future opportunities for collaborations around the delivery of training are proposed

  1. The Accurate Particle Tracer Code

    OpenAIRE

    Wang, Yulei; Liu, Jian; Qin, Hong; Yu, Zhi

    2016-01-01

    The Accurate Particle Tracer (APT) code is designed for large-scale particle simulations on dynamical systems. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and non-linear problems. Under the well-designed integrated and modularized framework, APT serves as a universal platform for researchers from different fields, such as plasma physics, accelerator physics, space science, fusio...

  2. Dynamics and mechanics of bed-load tracer particles

    Directory of Open Access Journals (Sweden)

    C. B. Phillips

    2014-12-01

    Full Text Available Understanding the mechanics of bed load at the flood scale is necessary to link hydrology to landscape evolution. Here we report on observations of the transport of coarse sediment tracer particles in a cobble-bedded alluvial river and a step-pool bedrock tributary, at the individual flood and multi-annual timescales. Tracer particle data for each survey are composed of measured displacement lengths for individual particles, and the number of tagged particles mobilized. For single floods we find that measured tracer particle displacement lengths are exponentially distributed; the number of mobile particles increases linearly with peak flood Shields stress, indicating partial bed load transport for all observed floods; and modal displacement distances scale linearly with excess shear velocity. These findings provide quantitative field support for a recently proposed modeling framework based on momentum conservation at the grain scale. Tracer displacement is weakly negatively correlated with particle size at the individual flood scale; however cumulative travel distance begins to show a stronger inverse relation to grain size when measured over many transport events. The observed spatial sorting of tracers approaches that of the river bed, and is consistent with size-selective deposition models and laboratory experiments. Tracer displacement data for the bedrock and alluvial channels collapse onto a single curve – despite more than an order of magnitude difference in channel slope – when variations of critical Shields stress and flow resistance between the two are accounted for. Results show how bed load dynamics may be predicted from a record of river stage, providing a direct link between climate and sediment transport.

  3. Use of sulfur hexafluoride and perfluorocarbon tracers in plutonium storage containers for leak detection

    International Nuclear Information System (INIS)

    Kung, J.K.

    1998-05-01

    This study involves an investigation of the feasibility of a tracer-based leak detection system for long-term interim plutonium storage. In particular, a protocol has been developed based on the use of inert tracers with varying concentrations in order to open-quotes fingerprintclose quotes or open-quotes tagclose quotes specific containers. A particular combination of tracers at specific ratios could be injected into the free volume of each container, allowing for the detection of leaks as well as determination of the location of leaking containers. Based on plutonium storage considerations, sulfur hexafluoride and four perfluorocarbon tracers were selected and should allow a wide range of viable fingerprinting combinations. A open-quotes high-lowclose quotes protocol which uses two distinct chromatographic peak areas or concentration levels, is recommended. Combinations of air exchange rates, detection durations, and detectability limits are examined in order to predict minimum tracer concentrations required for injection in storage containers

  4. Complex functionality with minimal computation: Promise and pitfalls of reduced-tracer ocean biogeochemistry models

    Science.gov (United States)

    Galbraith, Eric D.; Dunne, John P.; Gnanadesikan, Anand; Slater, Richard D.; Sarmiento, Jorge L.; Dufour, Carolina O.; de Souza, Gregory F.; Bianchi, Daniele; Claret, Mariona; Rodgers, Keith B.; Marvasti, Seyedehsafoura Sedigh

    2015-12-01

    Earth System Models increasingly include ocean biogeochemistry models in order to predict changes in ocean carbon storage, hypoxia, and biological productivity under climate change. However, state-of-the-art ocean biogeochemical models include many advected tracers, that significantly increase the computational resources required, forcing a trade-off with spatial resolution. Here, we compare a state-of-the art model with 30 prognostic tracers (TOPAZ) with two reduced-tracer models, one with 6 tracers (BLING), and the other with 3 tracers (miniBLING). The reduced-tracer models employ parameterized, implicit biological functions, which nonetheless capture many of the most important processes resolved by TOPAZ. All three are embedded in the same coupled climate model. Despite the large difference in tracer number, the absence of tracers for living organic matter is shown to have a minimal impact on the transport of nutrient elements, and the three models produce similar mean annual preindustrial distributions of macronutrients, oxygen, and carbon. Significant differences do exist among the models, in particular the seasonal cycle of biomass and export production, but it does not appear that these are necessary consequences of the reduced tracer number. With increasing CO2, changes in dissolved oxygen and anthropogenic carbon uptake are very similar across the different models. Thus, while the reduced-tracer models do not explicitly resolve the diversity and internal dynamics of marine ecosystems, we demonstrate that such models are applicable to a broad suite of major biogeochemical concerns, including anthropogenic change. These results are very promising for the further development and application of reduced-tracer biogeochemical models that incorporate "sub-ecosystem-scale" parameterizations.

  5. {sup 68}Ga-PSMA-11 PET/CT in primary staging of prostate cancer: PSA and Gleason score predict the intensity of tracer accumulation in the primary tumour

    Energy Technology Data Exchange (ETDEWEB)

    Uprimny, Christian; Kroiss, Alexander Stephan; Decristoforo, Clemens; Guggenberg, Elisabeth von; Kendler, Dorota; Scarpa, Lorenza; Di Santo, Gianpaolo; Roig, Llanos Geraldo; Maffey-Steffan, Johanna; Virgolini, Irene Johanna [Medical University Innsbruck, Department of Nuclear Medicine, Innsbruck (Austria); Fritz, Josef [Medical University Innsbruck, Department of Medical Statistics, Informatics and Health Economics, Innsbruck (Austria); Horninger, Wolfgang [Medical University Innsbruck, Department of Urology, Innsbruck (Austria)

    2017-06-15

    Prostate cancer (PC) cells typically show increased expression of prostate-specific membrane antigen (PSMA), which can be visualized by {sup 68}Ga-PSMA-11 PET/CT. The aim of this study was to assess the intensity of {sup 68}Ga-PSMA-11 uptake in the primary tumour and metastases in patients with biopsy-proven PC prior to therapy, and to determine whether a correlation exists between the primary tumour-related {sup 68}Ga-PSMA-11 accumulation and the Gleason score (GS) or prostate-specific antigen (PSA) level. Ninety patients with transrectal ultrasound biopsy-proven PC (GS 6-10; median PSA: 9.7 ng/ml) referred for {sup 68}Ga-PSMA-11 PET/CT were retrospectively analysed. PET images were analysed visually and semiquantitatively by measuring the maximum standardized uptake value (SUV{sub max}). The SUV{sub max} of the primary tumour and pathologic lesions suspicious for lymphatic or distant metastases were then compared to the physiologic background activity of normal prostate tissue and gluteal muscle. The SUV{sub max} of the primary tumour was assessed in relation to both PSA level and GS. Eighty-two patients (91.1%) demonstrated pathologic tracer accumulation in the primary tumour that exceeded physiologic tracer uptake in normal prostate tissue (median SUV{sub max}: 12.5 vs. 3.9). Tumours with GS of 6, 7a (3+4) and 7b (4+3) showed significantly lower {sup 68}Ga-PSMA-11 uptake, with median SUV{sub max} of 5.9, 8.3 and 8.2, respectively, compared to patients with GS >7 (median SUV{sub max}: 21.2; p < 0.001). PC patients with PSA ≥10.0 ng/ml exhibited significantly higher uptake than those with PSA levels <10.0 ng/ml (median SUV{sub max}: 17.6 versus 7.7; p < 0.001). In 24 patients (26.7%), 82 lymph nodes with pathologic tracer accumulation consistent with metastases were detected (median SUV{sub max}: 10.6). Eleven patients (12.2%) revealed 55 pathologic osseous lesions suspicious for bone metastases (median SUV{sub max}: 11.6). The GS and PSA level correlated with

  6. In-EDTA as activable tracer in hydrogeological investigations

    International Nuclear Information System (INIS)

    Stanescu, S.P.; Gaspar, E.; Spiridon, S.; Farcasiu, O.M.; Catilina, R.

    1982-12-01

    Two experiments are presented, on the possibilities of the use of indium in the form of the In-EDTA complex, as an activable tracer for hydrogeological studies. The determination of indium concentrations in the sampled water has been carried out by using the coprecipitation of indium with bismuth hydroxide, the neutron activation at the VVR-S reactor of the Institute for Nuclear Physics and Engineering - Bucharest and the measurement on the 417.0 keV line of sup(116m)In with the Ge(Li) spectrometric device. The advantages of the utilization of In-EDTA as a tracer for marking large volumes of water and of some long transit waters (of the order of months) have resulted. (authors)

  7. Slew-rate dependence of tracer magnetization response in magnetic particle imaging

    Science.gov (United States)

    Shah, Saqlain A.; Ferguson, R. M.; Krishnan, K. M.

    2014-10-01

    Magnetic Particle Imaging (MPI) is a new biomedical imaging technique that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide nanoparticle tracers. Currently, 25 kHz and 20 mT/μ0 excitation fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. Here, we address fundamental questions about MPI tracer magnetization dynamics and predict tracer performance in future scanners that employ new combinations of excitation field amplitude (Ho) and frequency (ω). Using an optimized, monodisperse MPI tracer, we studied how several combinations of drive field frequencies and amplitudes affect the tracer's response, using Magnetic Particle Spectrometry and AC hysteresis, for drive field conditions at 15.5, 26, and 40.2 kHz, with field amplitudes ranging from 7 to 52 mT/μ0. For both fluid and immobilized nanoparticle samples, we determined that magnetic response was dominated by Néel reversal. Furthermore, we observed that the peak slew-rate (ωHo) determined the tracer magnetic response. Smaller amplitudes provided correspondingly smaller field of view, sometimes resulting in excitation of minor hysteresis loops. Changing the drive field conditions but keeping the peak slew-rate constant kept the tracer response almost the same. Higher peak slew-rates led to reduced maximum signal intensity and greater coercivity in the tracer response. Our experimental results were in reasonable agreement with Stoner-Wohlfarth model based theories.

  8. Key aspects of stratospheric tracer modeling using assimilated winds

    Directory of Open Access Journals (Sweden)

    B. Bregman

    2006-01-01

    Full Text Available This study describes key aspects of global chemistry-transport models and their impact on stratospheric tracer transport. We concentrate on global models that use assimilated winds from numerical weather predictions, but the results also apply to tracer transport in general circulation models. We examined grid resolution, numerical diffusion, air parcel dispersion, the wind or mass flux update frequency, and time interpolation. The evaluation is performed with assimilated meteorology from the "operational analyses or operational data" (OD from the European Centre for Medium-Range Weather Forecasts (ECMWF. We also show the effect of the mass flux update frequency using the ECMWF 40-year re-analyses (ERA40. We applied the three-dimensional chemistry-transport Tracer Model version 5 (TM5 and a trajectory model and performed several diagnoses focusing on different transport regimes. Covering different time and spatial scales, we examined (1 polar vortex dynamics during the Arctic winter, (2 the large-scale stratospheric meridional circulation, and (3 air parcel dispersion in the tropical lower stratosphere. Tracer distributions inside the Arctic polar vortex show considerably worse agreement with observations when the model grid resolution in the polar region is reduced to avoid numerical instability. The results are sensitive to the diffusivity of the advection. Nevertheless, the use of a computational cheaper but diffusive advection scheme is feasible for tracer transport when the horizontal grid resolution is equal or smaller than 1 degree. The use of time interpolated winds improves the tracer distributions, particularly in the middle and upper stratosphere. Considerable improvement is found both in the large-scale tracer distribution and in the polar regions when the update frequency of the assimilated winds is increased from 6 to 3 h. It considerably reduces the vertical dispersion of air parcels in the tropical lower stratosphere. Strong

  9. Radiation dose estimates for carbon-11-labelled PET tracers

    International Nuclear Information System (INIS)

    Aart, Jasper van der; Hallett, William A.; Rabiner, Eugenii A.; Passchier, Jan; Comley, Robert A.

    2012-01-01

    Introduction: Carbon-11-labelled positron emission tomography (PET) tracers commonly used in biomedical research expose subjects to ionising radiation. Dosimetry is the measurement of radiation dose, but also commonly refers to the estimation of health risk associated with ionising radiation. This review describes radiation dosimetry of carbon-11-labelled molecules in the context of current PET research and the most widely used regulatory guidelines. Methods: A MEDLINE literature search returned 42 articles; 32 of these were based on human PET data dealing with radiation dosimetry of carbon-11 molecules. Radiation burden expressed as effective dose and maximum absorbed organ dose was compared between tracers. Results: All but one of the carbon-11-labelled PET tracers have an effective dose under 9 μSv/MBq, with a mean of 5.9 μSv/MBq. Data show that serial PET scans in a single subject are feasible for the majority of radiotracers. Conclusion: Although differing in approach, the two most widely used regulatory frameworks (those in the USA and the EU) do not differ substantially with regard to the maximum allowable injected activity per PET study. The predictive validity of animal dosimetry models is critically discussed in relation to human dosimetry. Finally, empirical PET data are related to human dose estimates based on homogenous distribution, generic models and maximum cumulated activities. Despite the contribution of these models to general risk estimation, human dosimetry studies are recommended where continued use of a new PET tracer is foreseen.

  10. Development of in-vessel source term analysis code, tracer

    International Nuclear Information System (INIS)

    Miyagi, K.; Miyahara, S.

    1996-01-01

    Analyses of radionuclide transport in fuel failure accidents (generally referred to source terms) are considered to be important especially in the severe accident evaluation. The TRACER code has been developed to realistically predict the time dependent behavior of FPs and aerosols within the primary cooling system for wide range of fuel failure events. This paper presents the model description, results of validation study, the recent model advancement status of the code, and results of check out calculations under reactor conditions. (author)

  11. Impulsive Stimulated Light Scattering Studies of the Liquid-Glass Transition: on the Experimental Verification of Mode-Coupling Theory Predictions.

    Science.gov (United States)

    Halalay, Ion C.

    A study of the structural glass transition trough impulsive stimulated light scattering experiments has been carried out in concentrated aqueous lithium chloride solutions, at temperatures ranging from ambient to cryogenic. A specially designed sample cell made it possible to cover the whole temperature interval from simple liquid, to viscoelastic supercooled liquid, to glass. It is shown that a phenomenological description of the results of these experiments in terms of a spectrum of relaxation times through the use of a Kohlrausch-Williams-Watts relaxation function is inadequate. Based on predictions of mode-coupling theory of the liquid-glass transition, an alternative approach to data interpretation is proposed. It is shown that for an aqueous lithium chloride solution, the prediction of simple scaling and identical scaling for mechanical and electrical susceptibilities seems to be valid. However, another prediction of theory is called into question: instead of a power-law behavior on temperature difference, it is found experimentally that the behavior of the susceptibility spectrum minimum is exponential. Similar disagreements are found for other two materials, triphenyl phosphite and polypropylene oxide. The causes for these discrepancies are discussed and it is concluded that additional experimentation is necessary to verify theoretical claims. Experiments are proposed which can test these predictions and serve as guide for the construction of theoretical models for the glass transition in real systems. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

  12. A new top boundary condition for modeling surface diffusive exchange of a generic volatile tracer: theoretical analysis and application to soil evaporation

    Directory of Open Access Journals (Sweden)

    J. Y. Tang

    2013-02-01

    Full Text Available We describe a new top boundary condition (TBC for representing the air–soil diffusive exchange of a generic volatile tracer. This new TBC (1 accounts for the multi-phase flow of a generic tracer; (2 accounts for effects of soil temperature, pH, solubility, sorption, and desorption processes; (3 enables a smooth transition between wet and dry soil conditions; (4 is compatible with the conductance formulation for modeling air–water volatile tracer exchange; and (5 is applicable to site, regional, and global land models.

    Based on the new TBC, we developed new formulations for bare-soil resistance and corresponding soil evaporation efficiency. The new soil resistance is predicted as the reciprocal of the harmonic sum of two resistances: (1 gaseous and aqueous molecular diffusion and (2 liquid mass flow resulting from the hydraulic pressure gradient between the soil surface and center of the topsoil control volume. We compared the predicted soil evaporation efficiency with those from several field and laboratory soil evaporation measurements and found good agreement with the typically observed two-stage soil evaporation curves. Comparison with the soil evaporation efficiency equation of Lee and Pielke (1992; hereafter LP92 indicates that their equation can overestimate soil evaporation when the atmospheric resistance is low and underestimate soil evaporation when the soil is dry. Using a synthetic inversion experiment, we demonstrated that using inverted soil resistance data from field measurements to derive empirical soil resistance formulations resulted in large uncertainty because (1 the inverted soil resistance data are always severely impacted by measurement error and (2 the derived empirical equation is very sensitive to the number of data points and the assumed functional form of the resistance.

    We expect the application of our new TBC in land models will provide a consistent representation for the diffusive tracer

  13. Simulation of tracer transport for the site characterization and validation site in the Stripa Mine

    International Nuclear Information System (INIS)

    Long, J.C.S.; Karasaki, K.

    1992-01-01

    This report describes a series of numerical simulations of tracer tests that were performed in a fracture zone (the H-zone) at the Stripa Mine in Sweden. The tracer simulations are bases on Equivalent Discontinuum models which were developed bases on geophysical measurements and hydraulic interference data (Long et al., 1992). The transport simulations are calibrated to one set of saline tracer breakthrough curves (from the first radar/saline experiment, RSI) and these calibrated models are used to predict another series of breakthrough curves. Predicted breakthrough curves can be compared to the actual data and simulated ''snapshots'' of concentration in the plan of the fracture zone can be compared to radar difference tomograms made during the saline tracer experiments

  14. Direct Observation of Heavy-Tailed Storage Times of Bed Load Tracer Particles Causing Anomalous Superdiffusion

    Science.gov (United States)

    Bradley, D. Nathan

    2017-12-01

    A consensus has formed that the step length distribution of fluvial bed load is thin tailed and that the observed anomalous superdiffusion of bed load tracer particles must arise from heavy-tailed resting times. However, heavy-tailed resting times have never been directly observed in the field over multiple floods. Using 9 years of data from a large bed load tracer experiment, I show that the spatial variance of the tracer plume scales faster than linearly with integrated excess stream power, indicating anomalous superdiffusion. The superdiffusion is caused by a heavy-tailed distribution of observed storage times that is fit with a truncated Pareto distribution with a tail parameter that is predicted by anomalous diffusion theory. The heavy-tailed distribution of storage times causes the tracer virtual velocity to slow over time, indicated by a sublinear increase in the mean displacement that is predicted by the storage time distribution tail parameter.

  15. Doublet Tracer Testing in Klamath Falls, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J.S.; Johnson, S.E.; Horne, R.N.; Jackson, P. B. [Pet. Eng. Dept., Stanford University; Culver, G.G. [Geo-Heat Center, Oregon Institute of Technology, Klamath Falls, OR

    0001-01-01

    A tracer test was carried out in a geothermal doublet system to study the injection behavior of a developed reservoir known to be fractured. The doublet produces about 320 gpm of 160 degrees Fahrenheit water that is used for space heating and then injected; the wells are spaced 250 ft apart. Tracer breakthrough was observed in 2 hours and 45 minutes in the production well, indicating fracture flow. However, the tracer concentrations were low and indicated porous media flow; the tracers mixed with a reservoir volume much larger than a fracture.

  16. Doublet Tracer Testing in Klamath Falls, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J S; Johnson, S E; Horne, R N; Jackson, P B [Pet. Eng. Dept., Stanford University; Culver, G G [Geo-Heat Center, Oregon Institute of Technology, Klamath Falls, OR

    0000-12-30

    A tracer test was carried out in a geothermal doublet system to study the injection behavior of a developed reservoir known to be fractured. The doublet produces about 320 gpm of 160 degrees Fahrenheit water that is used for space heating and then injected; the wells are spaced 250 ft apart. Tracer breakthrough was observed in 2 hours and 45 minutes in the production well, indicating fracture flow. However, the tracer concentrations were low and indicated porous media flow; the tracers mixed with a reservoir volume much larger than a fracture.

  17. Principles and techniques of gamma ray tracers

    International Nuclear Information System (INIS)

    Claxton, K.T.

    1978-01-01

    Radioactive tracer techniques provide a very sensitive means of studying physical and chemical processes in a whole variety of different media. Some of the techniques and principles of radioactive tracers and their application to practical engineering systems are discussed. Information which has been found useful in the design of high temperature liquid sodium facilities employing radio-tracers, is presented. The report deals solely with the use of gamma-emitting species as the tracer. These find particular application for in-situ studies on engineering systems where the highly penetrating properties of gamma rays are needed for detection through strongly absorbent media such as stainless steel pepe walls. (author)

  18. Use of artificial tracers in hydrology

    International Nuclear Information System (INIS)

    1991-05-01

    The IAEA has convened an Advisory Group Meeting with the following objectives: To define the role of artificial radioactive tracers for water tracing in comparison with other non-radioactive tracers. To evaluate the real needs of artificial radioactive tracers in hydrology. To identify the fields for which artificial radioactive tracers are useful as well as those in which they can be substituted by other tracers. To discuss the strategy to be adopted to overcome the difficulties derived from the restrictions on the use of radioactive tracers in hydrology. The meeting was held at IAEA Headquarters from 19 to 22 March 1990, and was attended by 30 participants from 15 Member States. The conclusions and recommendations are that the use of artificial radioactive tracers should be restricted to cases where other tracers cannot be used or do not provide the same quality of information. Tritium, iodine-131, bromine-82, chromium-51 in the form of Cr-EDTA, technetium-99m obtained from 99 Mo-generators and gold-198 as an adsorbable tracer are, practically, the only radionuclides used for water tracing. The use of other radionuclides for this purpose does not appear to be necessary, possible and/or convenient. Refs, figs and tabs

  19. Quadratic tracer dynamical models tobacco growth

    International Nuclear Information System (INIS)

    Qiang Jiyi; Hua Cuncai; Wang Shaohua

    2011-01-01

    In order to study the non-uniformly transferring process of some tracer dosages, we assume that the absorption of some tracer by tobacco is a quadratic function of the tracer quantity of the tracer in the case of fast absorption, whereas the exclusion of the tracer from tobacco is a linear function of the tracer quantity in the case of slow exclusion, after the tracer is introduced into tobacco once at zero time. A single-compartment quadratic dynamical model of Logistic type is established for the leaves of tobacco. Then, a two-compartment quadratic dynamical model is established for leaves and calms of the tobacco. Qualitative analysis of the models shows that the tracer applied to the leaves of the tobacco is excluded finally; however, the tracer stays at the tobacco for finite time. Two methods are also given for computing the parameters in the models. Finally, the results of the models are verified by the 32 P experiment for the absorption of tobacco. (authors)

  20. Marine chemistry and tracer applications of radiocaesium

    International Nuclear Information System (INIS)

    McKay, W.A.

    1983-03-01

    The general aims of this project were to study the marine chemistry of Windscale-derived radiocaesium and to continue previous research at Glasgow University on its tracer application in Scottish waters and sediments. It was found that a considerable percentage of sediment-associated 137 Cs (approximately 12 to 50%) may be contained by carbonate, oxide and organic coatings which appear to be relatively stable under a wide range of redox conditions. Whilst the partitioning of 137 Cs is related to the concentration of these oxides, organics and, to a much lesser extent, carbonates, their function is predominantly to prevent 137 Cs release from clay mineral exchange sites. 137 Cs activities per unit sediment weight were highest in the clay fraction with its uptake by coarse sediments appearing to be controlled by clay minerals coatings formed in the marine environment and cemented partly by oxides and organics. Though the sites sampled (Clyde Sea Area (C.S.A.) and L. Etive) encompassed a wide range of sediment types, the range of estimated 137 Cs distribution coefficients (K D ) was relatively small (360 to 890). Coatings may thus have more influence on K d s in the coastal marine environment than particle size distributions. Apparent concentration factors (C F s) of X325, X2800 and X1910 were determined for the associated carbonate, oxide and organic coatings, for a site off Greenock. Use of 'dry' sediments appeared to produce considerably overestimated values for the degree of 137 Cs fixation. Thus 'wet' sediments were used in these studies. Over the 1978-1981 period, approximately 35% of Windscale output passed through the C.S.A., diluted 26 times during transit. An estimated 0.3% of this water-borne inventory was removed into the sediments. Windscale to C.S.A. transit and residence times of 4 and 12 months respectively were derived. Monitoring the deeper levels of L. Etive allowed 137 Cs to be used to trace patterns of w

  1. Projected Applications of a "Weather in a Box" Computing System at the NASA Short-Term Prediction Research and Transition (SPoRT) Center

    Science.gov (United States)

    Jedlovec, Gary J.; Molthan, Andrew; Zavodsky, Bradley T.; Case, Jonathan L.; LaFontaine, Frank J.; Srikishen, Jayanthi

    2010-01-01

    The NASA Short-term Prediction Research and Transition Center (SPoRT)'s new "Weather in a Box" resources will provide weather research and forecast modeling capabilities for real-time application. Model output will provide additional forecast guidance and research into the impacts of new NASA satellite data sets and software capabilities. By combining several research tools and satellite products, SPoRT can generate model guidance that is strongly influenced by unique NASA contributions.

  2. Sub-Seasonal Prediction of the Maritime Continent Rainfall of Wet-Dry Transitional Seasons in the NCEP Climate Forecast Version 2

    Directory of Open Access Journals (Sweden)

    Tuantuan Zhang

    2016-02-01

    Full Text Available This study investigates the characteristics and prediction of the Maritime Continent (MC rainfall for the transitional periods between wet and dry seasons. Several observational data sets and the output from the 45-day hindcast by the U.S. National Centers for Environmental Prediction (NCEP Climate Forecast System version 2 (CFSv2 are used. Results show that the MC experiences a sudden transition from wet season to dry season (WTD around the 27th pentad, and a gradual transition from dry season to wet season (DTW around the 59th pentad. Correspondingly, the westerlies over the equatorial Indian Ocean, the easterlies over the equatorial Pacific Ocean, and the Australia High become weaker, contributing to weakening of the convergence over the MC. The subtropical western Pacific high intensifies and extends northeastward during the WTD. The Mascarene High becomes weaker, an anomalous anticyclonic circulation forms over the northeast of the Philippines, and an anomalous low-level convergence occurs over the western MC during the DTW. The NCEP CFSv2 captures the major features of rainfall and related atmospheric circulation when forecast lead time is less than three weeks for WTD and two weeks for DTW. The model predicts a weaker amplitude of the changes in rainfall and related atmospheric circulation for both WTD and DTW as lead time increases.

  3. Electronic computer prediction of properties of binary refractory transition metal compounds on the base of their simplificated electronic structure

    International Nuclear Information System (INIS)

    Kutolin, S.A.; Kotyukov, V.I.

    1979-01-01

    An attempt is made to obtain calculation equations of macroscopic physico-chemical properties of transition metal refractory compounds (density, melting temperature, Debye characteristic temperature, microhardness, standard formation enthalpy, thermo-emf) using the method of the regression analysis. Apart from the compound composition the argument of the regression equation is the distribution of electron bands of d-transition metals, created by the energy electron distribution in the simplified zone structure of transition metals and approximated by Chebishev polynoms, by the position of Fermi energy on the map of distribution of electron band energy depending upon the value of quasi-impulse, multiple to the first, second and third Brillouin zone for transition metals. The maximum relative error of the regressions obtained as compared with the literary data is 15-20 rel.%

  4. Use of Helium-3 and Tritium tracers in oceanography

    International Nuclear Information System (INIS)

    Andrie, Chantal

    1987-01-01

    As tritium considered as a transient tracer has become one of the most promising tool for the study of oceanic circulation and of the ocean capacity to absorb anthropogenic carbon, and as the simultaneous use of its radioactive descendant, Helium-3, brings an additional information (together, these tracers build up a clock in the study of water masses), and as all helium-3 and tritium measurements are made by mass spectroscopy, this research thesis addresses the analytical process, the detection limit, and the method reproducibility associated with this use of both tracers. The author reports and discusses helium-3 data obtained during a measurement campaign which allowed the localisation of an active source and the evidence of an intermediate back current, and tritium data obtained during another measurement campaign which allowed the description of the high time variability of convection processes, and an assessment of water renewal delays and of some deep water circulations. He also reports and discusses the simultaneous use of helium-3 data and tritium data to localize areas where convection processes occur. A theoretical approach to this simultaneous use is proposed which uses a mixing model which distinguishes the venting transit time. Measurement campaigns were performed in Red Sea, western Mediterranean Sea, and north-eastern Atlantic Ocean [fr

  5. Phase transitions

    CERN Document Server

    Sole, Ricard V; Solé, Ricard V; Solé, Ricard V; Sol, Ricard V; Solé, Ricard V

    2011-01-01

    Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation of diverse ecosystems, the book illustrates the power of simple models to reveal how phase transitions occur. Introductory chapters provide the critical concepts and the simplest mathematical techniques required to study phase transitions. In a series of example-driven chapters, Ricard Solé shows how such concepts and techniques can be applied to the analysis and prediction of complex system behavior, including the origins of ...

  6. Nanoparticle tracers in calcium carbonate porous media

    KAUST Repository

    Li, Yan Vivian; Cathles, Lawrence M.; Archer, Lynden A.

    2014-01-01

    the fractures or channels where flow occurs and thus take much less time to travel between two points. In combination with a chemical tracer they can measure the degree of flow concentration. A prerequisite for tracer applications is that the particles

  7. Tracer filamentation at an unstable ocean front

    Science.gov (United States)

    Feng, Yen Chia; Mahadevan, Amala; Thiffeault, Jean-Luc; Yecko, Philip

    2017-11-01

    A front, where two bodies of ocean water with different physical properties meet, can become unstable and lead to a flow with high strain rate and vorticity. Phytoplankton and other oceanic tracers are stirred into filaments by such flow fields, as can often be seen in satellite imagery. The stretching and folding of a tracer by a two-dimensional flow field has been well studied. In the ocean, however, the vertical shear of horizontal velocity is typically two orders of magnitude larger than the horizontal velocity gradient. Theoretical calculations show that vertical shear alters the way in which horizontal strain affects the tracer, resulting in thin, sloping structures in the tracer field. Using a non-hydrostatic ocean model of an unstable ocean front, we simulate tracer filamentation to identify the effect of vertical shear on the deformation of the tracer. In a complementary laboratory experiment, we generate a simple, vertically sheared strain flow and use dye and particle image velocimetry to quantify the filamentary structures in terms of the strain and shear. We identify how vertical shear alters the tracer filaments and infer how the evolution of tracers in the ocean will differ from the idealized two-dimensional paradigm. Support of NSF DMS-1418956 is acknowledged.

  8. Dynamic dual-tracer PET reconstruction.

    Science.gov (United States)

    Gao, Fei; Liu, Huafeng; Jian, Yiqiang; Shi, Pengcheng

    2009-01-01

    Although of important medical implications, simultaneous dual-tracer positron emission tomography reconstruction remains a challenging problem, primarily because the photon measurements from dual tracers are overlapped. In this paper, we propose a simultaneous dynamic dual-tracer reconstruction of tissue activity maps based on guidance from tracer kinetics. The dual-tracer reconstruction problem is formulated in a state-space representation, where parallel compartment models serve as continuous-time system equation describing the tracer kinetic processes of dual tracers, and the imaging data is expressed as discrete sampling of the system states in measurement equation. The image reconstruction problem has therefore become a state estimation problem in a continuous-discrete hybrid paradigm, and H infinity filtering is adopted as the estimation strategy. As H infinity filtering makes no assumptions on the system and measurement statistics, robust reconstruction results can be obtained for the dual-tracer PET imaging system where the statistical properties of measurement data and system uncertainty are not available a priori, even when there are disturbances in the kinetic parameters. Experimental results on digital phantoms, Monte Carlo simulations and physical phantoms have demonstrated the superior performance.

  9. Tracer diffusion in ternary alloys

    International Nuclear Information System (INIS)

    Tahir-Kheli, R.A.

    1985-07-01

    An intuitive extension of the theory for diffusion in dynamic binary alloys given in the preceding paper is presented. This theory has also received an independent derivation, based on more formal procedures, by Holdsworth and Elliott. We present Monte Carlo estimates for diffusion correlation factors, fsup(A), fsup(B), and fsup(C) and compare them with the theory. The agreement between the theoretical results and the Monte Carlo estimates for the correlation factors of the slow particles, i.e., fsup(C) and fsup(B), is found to be generally good. In contrast, for the correlation factor, fsup(A), referring to the diffusion coefficient of fast particles in the system, the theoretical results are found to be systematically lower by a small but resolvable margin. It is suggested that this is occasioned by the neglect of spatial constraints on the scattering of coupled tracer-background particle field pairs. (author)

  10. Transuranic and tracer simulant resuspension

    International Nuclear Information System (INIS)

    Sehmel, G.A.

    1977-07-01

    Plutonium resuspension results are summarized for experiments conducted at Rocky Flats, onsite on the Hanford reservation, and for winds blowing from offsite onto the Hanford reservation near the Prosser barricade boundary. In each case, plutonium resuspension was shown by increased airborne plutonium concentrations as a function of either wind speed or as compared to fallout levels. All measured airborne concentrations were below maximum permissible concentrations (MPC). Both plutonium and cesium concentrations on airborne soil were normalized by the quantity of airborne soil sampled. Airborne radionuclide concentrations in μCi/g were related to published values for radionuclide concentrations on surface soils. For this ratio of radionuclide concentration per gram on airborne soil divided by that for ground surface soil, there are eight orders of magnitude uncertainty from 10 -4 to 10 4 . Horizontal plutonium fluxes on airborne nonrespirable soils at all three sites were bracketed within the same three to four orders of magnitude from 10 -7 to 10 -3 μCi/(m 2 day) for plutonium-239 and 10 -8 to 10 -5 μCi/(m 2 day) for plutonium-238. These are the entire experimental base for nonrespirable airborne plutonium transport. Airborne respirable plutonium-239 concentrations increased with wind speed for a southeast wind direction coming from offsite near the Hanford reservation Prosser barricade. Airborne plutonium fluxes on nonrespirable particles had isotopic ratios, 240 Pu/ 239+240 Pu, similar to weapons grade plutonium rather than fallout plutonium. Resuspension rates were summarized for controlled inert particle tracer simulant experiments. Wind resuspension rates for tracers increased with wind speed to about the fifth power

  11. Quantifying postfire aeolian sediment transport using rare earth element tracers

    Science.gov (United States)

    Dukes, David; Gonzales, Howell B.; Ravi, Sujith; Grandstaff, David E.; Van Pelt, R. Scott; Li, Junran; Wang, Guan; Sankey, Joel B.

    2018-01-01

    Grasslands, which provide fundamental ecosystem services in many arid and semiarid regions of the world, are undergoing rapid increases in fire activity and are highly susceptible to postfire-accelerated soil erosion by wind. A quantitative assessment of physical processes that integrates fire-wind erosion feedbacks is therefore needed relative to vegetation change, soil biogeochemical cycling, air quality, and landscape evolution. We investigated the applicability of a novel tracer technique—the use of multiple rare earth elements (REE)—to quantify soil transport by wind and to identify sources and sinks of wind-blown sediments in both burned and unburned shrub-grass transition zone in the Chihuahuan Desert, NM, USA. Results indicate that the horizontal mass flux of wind-borne sediment increased approximately threefold following the fire. The REE tracer analysis of wind-borne sediments shows that the source of the horizontal mass flux in the unburned site was derived from bare microsites (88.5%), while in the burned site it was primarily sourced from shrub (42.3%) and bare (39.1%) microsites. Vegetated microsites which were predominantly sinks of aeolian sediments in the unburned areas became sediment sources following the fire. The burned areas showed a spatial homogenization of sediment tracers, highlighting a potential negative feedback on landscape heterogeneity induced by shrub encroachment into grasslands. Though fires are known to increase aeolian sediment transport, accompanying changes in the sources and sinks of wind-borne sediments may influence biogeochemical cycling and land degradation dynamics. Furthermore, our experiment demonstrated that REEs can be used as reliable tracers for field-scale aeolian studies.

  12. DI/LC-MS/MS-Based Metabolic Profiling for Identification of Early Predictive Serum Biomarkers of Metritis in Transition Dairy Cows.

    Science.gov (United States)

    Zhang, Guanshi; Deng, Qilan; Mandal, Rupasri; Wishart, David S; Ametaj, Burim N

    2017-09-27

    The objectives of this study were to evaluate alterations of metabolites in the blood of dairy cows before, during, and after diagnosis of metritis and identify predictive serum metabolite biomarkers for metritis. DI/LC-MS/MS was used to analyze serum samples collected from both healthy and metritic cows during -8, -4, disease diagnosis, +4, and +8 wks relative to parturition. Results indicated that cows with metritis experienced altered concentrations of serum amino acids, glycerophospholipids, sphingolipids, acylcarnitines, and biogenic amines during the entire experimental period. Moreover, two sets of predictive biomarker models and one set of diagnostic biomarker models for metritis were developed, and all of them showed high sensitivity and specificity (e.g., high AUC values by the ROC curve evaluation), which indicate that serum metabolites identified have pretty accurate predictive, diagnostic, and prognostic abilities for metritis in transition dairy cows.

  13. The Use of OXYGEN-18 in the Development of Methods for Controlled Sputter Deposition of High Critical Transition Temperature Material Thin Films of Predicted Composition and Good Uniformity

    Science.gov (United States)

    Tidrow, Steven Clay

    Two primary concerns, in the sputter deposition of high T_{c} material films, are the prevention of oxygen deficiency in the films and the elimination of the negative ion effect. "Oxygen deficiency" occurs when the amount of oxygen incorporated into the film is less than the amount of oxygen required to form the superconducting material lattice. Oxygen deficiency is due to the volatile nature of oxygen. The negative ion effect occurs when an atom or molecule (typically oxygen) gains an extra electron, is accelerated away from the target and impinges upon a film being grown directly in front of the sputtering target. The impinging particle has enough energy to cause resputtering of the deposited film. The presence of Sr and to a greater extent Ba, may enhance the negative ion effect in these materials. However, it is oxygen which readily forms negative ions that is primarily responsible for the negative ion effect. Thus, oxygen must be given special attention in the sputter deposition of high T_{c} material films. A specially designed sputtering system is used to demonstrate that the negative ion effect can be reduced such that large uniform high T_{c} material films possessing predicted and repeated composition can be grown in an on-axis arrangement. Utilizing this same sputtering system and the volatile nature of oxygen, it is demonstrated that oxygen processes occurring in the chamber during growth of high T_ {c} material films can be investigated using the tracer ^{18}O. In particular, it is shown that ^{18}O can be utilized as a tool for (1) investigating the negative ion effect, (2) investigating oxygen incorporation into high T_{c} material films, (3) investigating oxygen incorporation into the target, (4) tailoring films for oxygen migration and interface investigations and (5) tailoring films for the other specific oxygen investigations. Such sputtering systems that utilize the tracer ^{18}O are necessary for systematic growth of high T_ {c} material films

  14. Tracer disposition kinetics in the determination of local cerebral blood flow by a venous equilibrium model, tube model, and distributed model

    International Nuclear Information System (INIS)

    Sawada, Y.; Sugiyama, Y.; Iga, T.; Hanano, M.

    1987-01-01

    Tracer distribution kinetics in the determination of local cerebral blood flow (LCBF) were examined by using three models, i.e., venous equilibrium, tube, and distributed models. The technique most commonly used for measuring LCBF is the tissue uptake method, which was first developed and applied by Kety. The measurement of LCBF with the 14 C-iodoantipyrine (IAP) method is calculated by using an equation derived by Kety based on the Fick's principle and a two-compartment model of blood-tissue exchange and tissue concentration at a single data point. The procedure, in which the tissue is to be in equilibrium with venous blood, will be referred to as the tissue equilibration model. In this article, effects of the concentration gradient of tracer along the length of the capillary (tube model) and the transverse heterogeneity in the capillary transit time (distributed model) on the determination of LCBF were theoretically analyzed for the tissue sampling method. Similarities and differences among these models are explored. The rank order of the LCBF calculated by using arterial blood concentration time courses and the tissue concentration of tracer based on each model were tube model (model II) less than distributed model (model III) less than venous equilibrium model (model I). Data on 14 C-IAP kinetics reported by Ohno et al. were employed. The LCBFs calculated based on model I were 45-260% larger than those in models II or III. To discriminate among three models, we propose to examine the effect of altering the venous infusion time of tracer on the apparent tissue-to-blood concentration ratio (lambda app). A range of the ratio of the predicted lambda app in models II or III to that in model I was from 0.6 to 1.3

  15. Using Tracer Technology to Characterize Contaminated Pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Maresca, Joseph, W., Jr., Ph.D.; Bratton, Wesley, L., Ph.D., P.E.; Dickerson, Wilhelmina; Hales, Rochelle

    2005-12-30

    The Pipeline Characterization Using Tracers (PCUT) technique uses conservative and partitioning, reactive or other interactive tracers to remotely determine the amount of contaminant within a run of piping or ductwork. The PCUT system was motivated by a method that has been successfully used to characterize subsurface soil contaminants and is similar in operation to that of a gas chromatography column. By injecting a ?slug? of both conservative and partitioning tracers at one end (or section) of the piping and measuring the time history of the concentration of the tracers at the other end (or another section) of the pipe, the presence, location, and amount of contaminant within the pipe or duct can be determined. The tracers are transported along the pipe or duct by a gas flow field, typically air or nitrogen, which has a velocity that is slow enough so that the partitioning tracer has time to interact with the contaminant before the tracer slug completely passes over the contaminate region. PCUT not only identifies the presence of contamination, it also can locate the contamination along the pipeline and quantify the amount of residual. PCUT can be used in support of deactivation and decommissioning (D&D) of piping and ducts that may have been contaminated with hazardous chemicals such as chlorinated solvents, petroleum products, radioactive materials, or heavy metals, such as mercury.

  16. A predictive coexpression network identifies novel genes controlling the seed-to-seedling phase transition in arabidopsis Thaliana

    NARCIS (Netherlands)

    Silva, Anderson Tadeu; Ribone, Pamela A.; Chan, Raquel L.; Ligterink, Wilco; Hilhorst, Henk W.M.

    2016-01-01

    The transition from a quiescent dry seed to an actively growing photoautotrophic seedling is a complex and crucial trait for plant propagation. This study provides a detailed description of global gene expression in seven successive developmental stages of seedling establishment in Arabidopsis

  17. The Role of Student Burnout in Predicting Future Burnout: Exploring the Transition from University to the Workplace

    Science.gov (United States)

    Robins, Tamara G.; Roberts, Rachel M.; Sarris, Aspa

    2018-01-01

    Burnout is a significant problem in the workplace and recent research suggests burnout is also a growing concern for students. This study aimed to explore the transition from study to work, including exploring the impact of student burnout on work burnout. Australian health profession students (T1, n = 86; T2, n = 86; T3, n = 57) from the…

  18. Elevated source SF6-tracer dispersion experiments in the Copenhagen area. Preliminary results II

    International Nuclear Information System (INIS)

    Gryning, S.E.; Lyck, E.

    1980-01-01

    The results from 10 experiments, performed in neutral to unstable meteorological conditions, are reported from an ongoing series of elevated-source, urban-scale tracer dispersion experiments in the Copenhagen area. The tracer is released at a height of 115 m from the TV-tower in GLADSAXE, a suburb of Copenhagen, with tracer sampling units positioned at ground-level in 1 to 3 crosswind series, 2 to 6 km downwind of the tower. The lateral dispersion parameter, sigma(y), was estimated from the measured tracer concentration distribution and compared with values of sigma(y), computed by 1) methods based on wind variance measured during the experiments and 2) methods based on a stability classification of the atmospheric conditions. The wind-variance based methods proved superior in predicting the variation of sigma(y) compared with the stability based methods. Moreover, some of the former methods produced significantly biased estimates of sigma(y). The measured tracer concentration distributions were also crosswind integrated, chi(CWI). Estimates of chi(CWI) were computed using sigma (z) -values derived from the aforementioned computations assuming a Gaussian-type vertical tracer concentration distribution. A comparison is measured and calculated values of chi(CWI) showed no significant differences in the ability of the methods to predict the variation of chi(CWI). Only one method, the EPA, came out with a mean fractional error outside the range +-20% which constitutes the uncertainty in the absolute tracer concentration associated with the calibration of the gas chromatograph for tracer analysis

  19. Tracers vs. trajectories in a coastal region

    Science.gov (United States)

    Engqvist, A.; Döös, K.

    2008-12-01

    Two different methods of estimating the water exchange through a Baltic coastal region have been used, consisting of particle trajectories and passive tracers. Water is traced from and to a small discharge region near the coast. The discharge material in this region is treated as zero dimensional particles or tracers with neutral buoyancy. The real discharge material could be a leakage of radio-nuclides through the sea floor from an underground repository of nuclear waste. Water exchange rates between the discharge region and the model domain are estimated using both forward and backward trajectories as well as passive tracers. The Lagrangian trajectories can account for the time evolution of the water exchange while the tracers give one average age per model grid box. Water exchange times such as residence time, age and transient times have been calculated with trajectories but only the average age (AvA) for tracers. The trajectory calculations provide a more detailed time evolution than the tracers. On the other hand the tracers are integrated "on-line" simultaneously in the sea circulation model with the same time step while the Lagrangian trajectories are integrated "off-line" from the stored model velocities with its inherent temporal resolution, presently one hour. The sub-grid turbulence is parameterised as a Laplacian diffusion for the passive tracers and with an extra stochastic velocity for trajectories. The importance of the parameterised sub-grid turbulence for the trajectories is estimated to give an extra diffusion of the same order as the Laplacian diffusion by comparing the Lagrangian dispersions with and without parameterisation. The results of the different methods are similar but depend on the chosen diffusivity coefficient with a slightly higher correlation between trajectories and tracers when integrated with a lower diffusivity coefficient.

  20. Statistically Based Morphodynamic Modeling of Tracer Slowdown

    Science.gov (United States)

    Borhani, S.; Ghasemi, A.; Hill, K. M.; Viparelli, E.

    2017-12-01

    Tracer particles are used to study bedload transport in gravel-bed rivers. One of the advantages associated with using of tracer particles is that they allow for direct measures of the entrainment rates and their size distributions. The main issue in large scale studies with tracer particles is the difference between tracer stone short term and long term behavior. This difference is due to the fact that particles undergo vertical mixing or move to less active locations such as bars or even floodplains. For these reasons the average virtual velocity of tracer particle decreases in time, i.e. the tracer slowdown. In summary, tracer slowdown can have a significant impact on the estimation of bedload transport rate or long term dispersal of contaminated sediment. The vast majority of the morphodynamic models that account for the non-uniformity of the bed material (tracer and not tracer, in this case) are based on a discrete description of the alluvial deposit. The deposit is divided in two different regions; the active layer and the substrate. The active layer is a thin layer in the topmost part of the deposit whose particles can interact with the bed material transport. The substrate is the part of the deposit below the active layer. Due to the discrete representation of the alluvial deposit, active layer models are not able to reproduce tracer slowdown. In this study we try to model the slowdown of tracer particles with the continuous Parker-Paola-Leclair morphodynamic framework. This continuous, i.e. not layer-based, framework is based on a stochastic description of the temporal variation of bed surface elevation, and of the elevation specific particle entrainment and deposition. Particle entrainment rates are computed as a function of the flow and sediment characteristics, while particle deposition is estimated with a step length formulation. Here we present one of the first implementation of the continuum framework at laboratory scale, its validation against

  1. Particle integrity, sampling, and application of a DNA-tagged tracer for aerosol transport studies

    Energy Technology Data Exchange (ETDEWEB)

    Kaeser, Cynthia Jeanne [Michigan State Univ., East Lansing, MI (United States)

    2017-07-21

    Aerosols are an ever-present part of our daily environment and have extensive effects on both human and environmental health. Particles in the inhalable range (1-10 μm diameter) are of particular concern because their deposition in the lung can lead to a variety of illnesses including allergic reactions, viral or bacterial infections, and cancer. Understanding the transport of inhalable aerosols across both short and long distances is necessary to predict human exposures to aerosols. To assess the transport of hazardous aerosols, surrogate tracer particles are required to measure their transport through occupied spaces. These tracer particles must not only possess similar transport characteristics to those of interest but also be easily distinguished from the background at low levels and survive the environmental conditions of the testing environment. A previously-developed DNA-tagged particle (DNATrax), composed of food-grade sugar and a DNA oligonucleotide as a “barcode” label, shows promise as a new aerosol tracer. Herein, the use of DNATrax material is validated for use in both indoor and outdoor environments. Utilizing passive samplers made of materials commonly found in indoor environments followed by quantitative polymerase chain reaction (qPCR) assay for endpoint particle detection, particles detection was achieved up to 90 m from the aerosolization location and across shorter distances with high spatial resolution. The unique DNA label and PCR assay specificity were leveraged to perform multiple simultaneous experiments. This allowed the assessment of experimental reproducibility, a rare occurrence among aerosol field tests. To transition to outdoor testing, the solid material provides some protection of the DNA label when exposed to ultraviolet (UV) radiation, with 60% of the DNA remaining intact after 60 minutes under a germicidal lamp and the rate of degradation declining with irradiation time. Additionally, exposure of the DNATrax material using

  2. Polymer adhesion predictions for oral dosage forms to enhance drug administration safety. Part 3: Review of in vitro and in vivo methods used to predict esophageal adhesion and transit time.

    Science.gov (United States)

    Drumond, Nélio; Stegemann, Sven

    2018-05-01

    The oral cavity is frequently used to administer pharmaceutical drug products. This route of administration is seen as the most accessible for the majority of patients and supports an independent therapy management. For current oral dosage forms under development, the prediction of their unintended mucoadhesive properties and esophageal transit profiles would contribute for future administration safety, as concerns regarding unintended adhesion of solid oral dosage forms (SODF) during oro-esophageal transit still remain. Different in vitro methods that access mucoadhesion of polymers and pharmaceutical preparations have been proposed over the years. The same methods might be used to test non-adhesive systems and contribute for developing safe-to-swallow technologies. Previous works have already investigated the suitability of non-animal derived in vitro methods to assess such properties. The aim of this work was to review the in vitro methodology available in the scientific literature that used animal esophageal tissue to evaluate mucoadhesion and esophageal transit of pharmaceutical preparations. Furthermore, in vivo methodology is also discussed. Since none of the in vitro methods developed are able to mimic the complex swallowing process and oro-esophageal transit, in vivo studies in humans remain as the gold standard. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. The accurate particle tracer code

    Science.gov (United States)

    Wang, Yulei; Liu, Jian; Qin, Hong; Yu, Zhi; Yao, Yicun

    2017-11-01

    The Accurate Particle Tracer (APT) code is designed for systematic large-scale applications of geometric algorithms for particle dynamical simulations. Based on a large variety of advanced geometric algorithms, APT possesses long-term numerical accuracy and stability, which are critical for solving multi-scale and nonlinear problems. To provide a flexible and convenient I/O interface, the libraries of Lua and Hdf5 are used. Following a three-step procedure, users can efficiently extend the libraries of electromagnetic configurations, external non-electromagnetic forces, particle pushers, and initialization approaches by use of the extendible module. APT has been used in simulations of key physical problems, such as runaway electrons in tokamaks and energetic particles in Van Allen belt. As an important realization, the APT-SW version has been successfully distributed on the world's fastest computer, the Sunway TaihuLight supercomputer, by supporting master-slave architecture of Sunway many-core processors. Based on large-scale simulations of a runaway beam under parameters of the ITER tokamak, it is revealed that the magnetic ripple field can disperse the pitch-angle distribution significantly and improve the confinement of energetic runaway beam on the same time.

  4. Development of Radioisotope Tracer Technology

    International Nuclear Information System (INIS)

    Jung, Sung Hee; Jin, Joon Ha; Kim, Jong Bum; Kim, Jin Seop; Kim, Jae Jo; Park, Soon Chul; Lim, Don Soon; Choi, Byung Jong; Jang, Dong Soon; Kim, Hye Sook

    2007-06-01

    The project is aimed to develop the radiotracer technology for process optimization and trouble-shooting to establish the environmental and industrial application of radiation and radioisotopes. The advanced equipment and software such as high speed data acquisition system, RTD model and high pressure injection tool have developed. Based on the various field application to the refinery/petrochemical industries, the developed technology was transfer to NDT company for commercial service. For the environmental application of radiotracer technology, injector, detector sled, core sampler, RI and GPS data logging system are developed and field tests were implemented successfully at Wolsung and Haeundae beach. Additionally tracer technology were also used for the performance test of the clarifier in a wastewater treatment plant and for the leak detection in reservoirs. From the experience of case studies on radiotracer experiment in waste water treatment facilities, 'The New Excellent Technology' is granted from the ministry of environment. For future technology, preliminary research for industrial gamma transmission and emission tomography which are new technology combined with radioisotope and image reconstruction are carried out

  5. Compartmental modeling and tracer kinetics

    CERN Document Server

    Anderson, David H

    1983-01-01

    This monograph is concerned with mathematical aspects of compartmental an­ alysis. In particular, linear models are closely analyzed since they are fully justifiable as an investigative tool in tracer experiments. The objective of the monograph is to bring the reader up to date on some of the current mathematical prob­ lems of interest in compartmental analysis. This is accomplished by reviewing mathematical developments in the literature, especially over the last 10-15 years, and by presenting some new thoughts and directions for future mathematical research. These notes started as a series of lectures that I gave while visiting with the Division of Applied ~1athematics, Brown University, 1979, and have developed in­ to this collection of articles aimed at the reader with a beginning graduate level background in mathematics. The text can be used as a self-paced reading course. With this in mind, exercises have been appropriately placed throughout the notes. As an aid in reading the material, the e~d of a ...

  6. Studies of Tracer Dispersion and Fluid Flow in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Rage, T.

    1996-12-31

    This doctoral thesis explores the connection between the topology of a porous medium and its macroscopic transport properties and is based on computerized simulation. In porous media, both diffusion and convection contribute to the dispersion of a tracer and their combined effect is emphasized. The governing equations are solved numerically, using finite differences and Monte Carlo technique. The influence of finite Reynolds number on the outcome of echo-experiments is discussed. Comparing experiments and simulations it is found that nonlinear inertial forces lead to a visible deformation of a returned tracer at surprisingly small Reynolds numbers. In a study of tracer dispersion and fluid flow in periodic arrays of discs it is demonstrated that the mechanisms of mechanical dispersion in periodic media and in natural (non-periodic) porous media are essentially different. Measurements of the percolation probability distribution of a sandstone sample is presented. Local porosity theory predicts that this simple geometric function of a porous medium is of dominant importance for its macroscopic transport properties. It is demonstrated that many aspects of transport through fractures can be studied by using simple but realistic models and readily available computer resources. An example may be the transport of hydrocarbon fluids from the source rock to a reservoir. 165 refs., 44 figs., 1 table

  7. The protection motivation theory within the stages of the transtheoretical model - stage-specific interplay of variables and prediction of exercise stage transitions.

    Science.gov (United States)

    Lippke, Sonia; Plotnikoff, Ronald C

    2009-05-01

    Two different theories of health behaviour have been chosen with the aim of theory integration: a continuous theory (protection motivation theory, PMT) and a stage model (transtheoretical model, TTM). This is the first study to test whether the stages of the TTM moderate the interrelation of PMT-variables and the mediation of motivation, as well as PMT-variables' interactions in predicting stage transitions. Hypotheses were tested regarding (1) mean patterns, stage pair-comparisons and nonlinear trends using ANOVAs; (2) prediction-patterns for the different stage groups employing multi-group structural equation modelling (MSEM) and nested model analyses; and (3) stage transitions using binary logistic regression analyses. Adults (N=1,602) were assessed over a 6 month period on their physical activity stages, PMT-variables and subsequent behaviour. (1) Particular mean differences and nonlinear trends in all test variables were found. (2) The PMT adequately fitted the five stage groups. The MSEM revealed that covariances within threat appraisal and coping appraisal were invariant and all other constrains were stage-specific, i.e. stage was a moderator. Except for self-efficacy, motivation fully mediated the relationship between the social-cognitive variables and behaviour. (3) Predicting stage transitions with the PMT-variables underscored the importance of self-efficacy. Only when threat appraisal and coping appraisal were high, stage movement was more likely in the preparation stage. Results emphasize stage-specific differences of the PMT mechanisms, and hence, support the stage construct. The findings may guide further theory building and research integrating different theoretical approaches.

  8. A study on the predictability of the transition day from the dry to the rainy season over South Korea

    Science.gov (United States)

    Lee, Sang-Min; Nam, Ji-Eun; Choi, Hee-Wook; Ha, Jong-Chul; Lee, Yong Hee; Kim, Yeon-Hee; Kang, Hyun-Suk; Cho, ChunHo

    2016-08-01

    This study was conducted to evaluate the prediction accuracies of THe Observing system Research and Predictability EXperiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) data at six operational forecast centers using the root-mean square difference (RMSD) and Brier score (BS) from April to July 2012. And it was performed to test the precipitation predictability of ensemble prediction systems (EPS) on the onset of the summer rainy season, the day of withdrawal in spring drought over South Korea on 29 June 2012 with use of the ensemble mean precipitation, ensemble probability precipitation, 10-day lag ensemble forecasts (ensemble mean and probability precipitation), and effective drought index (EDI). The RMSD analysis of atmospheric variables (geopotential-height at 500 hPa, temperature at 850 hPa, sea-level pressure and specific humidity at 850 hPa) showed that the prediction accuracies of the EPS at the Meteorological Service of Canada (CMC) and China Meteorological Administration (CMA) were poor and those at the European Center for Medium-Range Weather Forecasts (ECMWF) and Korea Meteorological Administration (KMA) were good. Also, ECMWF and KMA showed better results than other EPSs for predicting precipitation in the BS distributions. It is also evaluated that the onset of the summer rainy season could be predicted using ensemble-mean precipitation from 4-day leading time at all forecast centers. In addition, the spatial distributions of predicted precipitation of the EPS at KMA and the Met Office of the United Kingdom (UKMO) were similar to those of observed precipitation; thus, the predictability showed good performance. The precipitation probability forecasts of EPS at CMA, the National Centers for Environmental Prediction (NCEP), and UKMO (ECMWF and KMA) at 1-day lead time produced over-forecasting (under-forecasting) in the reliability diagram. And all the ones at 2˜4-day lead time showed under-forecasting. Also, the precipitation on onset day of

  9. [Hepatic transit times and liver elasticity compared with meld in predicting a 1 year adverse clinical outcome of a clinically diagnosed cirrhosis].

    Science.gov (United States)

    Koller, Tomáš; Piešťanská, Zuzana; Hlavatý, Tibor; Holomáň, Jozef; Glasa, Jozef; Payer, Juraj

    Hepatic transit times measured by the contrast enhanced ultrasonography and liver elasticity were found to predict a clinically significant portal hypertension. However, these modalities we not yet sufficiently evaluated in predicting adverse clinical outcome in patients with clinically diagnosed cirrhosis (D´Amico stages > 1), having a clinically significant portal hypertension. The aim of our study was to assess the predictive power of the liver transit times and the liver elasticity on an adverse clinical outcome of clinically diagnosed cirrhosis compared with the MELD score. The study group included 48 consecutive outpatients with cirrhosis in the 2., 3. and 4. DAmico stages. Patients with stage 4 could have jaundice, patients with other complications of portal hypertension were excluded. Transit times were measured from the time of intravenous administration of contrast agent (Sonovue) to a signal appearance in a hepatic vein (hepatic vein arrival time, HVAT) or time difference between the contrast signal in the hepatic artery and hepatic vein (hepatic transit time, HTT) in seconds. Elasticity was measured using the transient elastography (Fibroscan). The transit times and elasticity were measured at baseline and patients were followed for up for 1 year. Adverse outcome of cirrhosis was defined as the appearance of clinically apparent ascites and/or hospitalization for liver disease and/or death within 1 year. The mean age was 61 years, with female/male ratio 23/25. At baseline, the median Child-Pugh score was 5 (IQR 5.0-6.0), MELD 9.5 (IQR 7.6 to 12.1), median HVAT was 22 s (IQR 19-25) and HTT 6 (IQR 5-9). HTT and HVAT negatively correlated with Child-Pugh (-0.351 and -0.441, p = 0.002) and MELD (-0.479 and -0.388, p = 0.006) scores. The adverse outcome at 1-year was observed in 11 cases (22.9 %), including 6 deaths and 5 hospitalizations. Median HVAT in those with/without the adverse outcome was 20 seconds (IQR 19.3-23.5) compared with 22 s (IQR 19-26, p

  10. Tracer surface diffusion on UO2

    International Nuclear Information System (INIS)

    Zhou, S.Y.; Olander, D.R.

    1983-06-01

    Surface diffusion on UO 2 was measured by the spreading of U-234 tracer on the surface of a duplex diffusion couple consisting of wafers of depleted and enriched UO 2 joined by a bond of uranium metal

  11. Development of a tracer transport option for the NAPSAC fracture network computer code

    International Nuclear Information System (INIS)

    Herbert, A.W.

    1990-06-01

    The Napsac computer code predicts groundwater flow through fractured rock using a direct fracture network approach. This paper describes the development of a tracer transport algorithm for the NAPSAC code. A very efficient particle-following approach is used enabling tracer transport to be predicted through large fracture networks. The new algorithm is tested against three test examples. These demonstrations confirm the accuracy of the code for simple networks, where there is an analytical solution to the transport problem, and illustrates the use of the computer code on a more realistic problem. (author)

  12. Elliptic random-walk equation for suspension and tracer transport in porous media

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Bedrikovetsky, P. G.

    2008-01-01

    . The new theory predicts delay of the maximum of the tracer, compared to the velocity of the flow, while its forward "tail" contains much more particles than in the solution of the classical parabolic (advection-dispersion) equation. This is in agreement with the experimental observations and predictions......We propose a new approach to transport of the suspensions and tracers in porous media. The approach is based on a modified version of the continuous time random walk (CTRW) theory. In the framework of this theory we derive an elliptic transport equation. The new equation contains the time...... of the CTRW theory. (C) 2008 Elsevier B.V. All rights reserved....

  13. Exploring Hydrofluorocarbons as Groundwater Age Tracers (Invited)

    Science.gov (United States)

    Haase, K. B.; Busenberg, E.; Plummer, L. N.; Casile, G.; Sanford, W. E.

    2013-12-01

    Groundwater dating tracers are an essential tool for analyzing hydrologic conditions in groundwater systems. Commonly used tracers for dating post-1940's groundwater include sulfur hexafluoride (SF6), chlorofluorocarbons (CFCs), 3H-3He, and other isotopic tracers (85Kr, δ2H and δ18O isotopes, etc.). Each tracer carries a corresponding set of advantages and limitations imposed by field, analytical, and interpretive methods. Increasing the number available tracers is appealing, particularly if they possess inert chemical properties and unique temporal emission histories from other tracers. Atmospherically derived halogenated trace gases continue to hold untapped potential for new tracers, as they are generally inert and their emission histories are well documented. SF5CF3, and CFC-13 were previously shown to have application as dating tracers, though their low mixing ratios and low solubility require large amounts of water to be degassed for their quantification. Two related groups of compounds, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are hypothesized to be potential age tracers, having similar mixing ratios to the CFCs and relatively high solubility. However, these compounds yield gas chromatography electron capture detector (GC-ECD) responses that are 10-2 -10-5 less than CFC-12, making purge and trap or field stripping GC-ECD approaches impractical. Therefore, in order to use dissolved HCFCs and HFCs as age tracers, different approaches are needed. To solve this problem, we developed an analytical method that uses an atomic emission detector (GC-AED) in place of an ECD to detect fluorinated compounds. In contrast to the ECD, the AED is a universally sensitive, highly linear, elementally specific detector. The new GC-AED system is being used to measure chlorodifluoromethane (HCFC-22), 1,1,1,2-tetrafluoroethane (HFC-134a), and other fluorinated compounds in one liter water samples to study their potential as age dating tracers. HCFC-22 is a

  14. Development of standardized component\\0x2010based equipment specifications and transition plan into a predictive maintenance strategy.

    Science.gov (United States)

    2015-12-01

    This project investigated INDOT equipment records and equipment industry standards to produce standard equipment specifications : and a predictive maintenance schedule for the more than 1100 single and tandem axle trucks in use at INDOT. The research...

  15. Development of standardized component\\0x2010based equipment specifications and transition plan into a predictive maintenance strategy : final report.

    Science.gov (United States)

    2015-12-01

    This project investigated INDOT equipment records and equipment industry standards to produce standard equipment specifications : and a predictive maintenance schedule for the more than 1100 single and tandem axle trucks in use at INDOT. The research...

  16. Radioisotope tracers in industrial flow studies

    International Nuclear Information System (INIS)

    Easey, J.F.

    1987-01-01

    The scope of radioisotope tracer work carried out by ANSTO has involved most sectors of Australian industry including iron and steel coal, chemical, petrochemical, natural gas, metallurgical, mineral, power generation, liquified air plant, as well as port authorities, water and sewerage instrumentalities, and environmental agencies. A major class of such studies concerns itself with flow and wear studies involving industrial equipment. Some examples are discussed which illustrate the utility of radioisotope tracer techniques in these applications

  17. Improving Marine Ecosystem Models with Biochemical Tracers

    Science.gov (United States)

    Pethybridge, Heidi R.; Choy, C. Anela; Polovina, Jeffrey J.; Fulton, Elizabeth A.

    2018-01-01

    Empirical data on food web dynamics and predator-prey interactions underpin ecosystem models, which are increasingly used to support strategic management of marine resources. These data have traditionally derived from stomach content analysis, but new and complementary forms of ecological data are increasingly available from biochemical tracer techniques. Extensive opportunities exist to improve the empirical robustness of ecosystem models through the incorporation of biochemical tracer data and derived indices, an area that is rapidly expanding because of advances in analytical developments and sophisticated statistical techniques. Here, we explore the trophic information required by ecosystem model frameworks (species, individual, and size based) and match them to the most commonly used biochemical tracers (bulk tissue and compound-specific stable isotopes, fatty acids, and trace elements). Key quantitative parameters derived from biochemical tracers include estimates of diet composition, niche width, and trophic position. Biochemical tracers also provide powerful insight into the spatial and temporal variability of food web structure and the characterization of dominant basal and microbial food web groups. A major challenge in incorporating biochemical tracer data into ecosystem models is scale and data type mismatches, which can be overcome with greater knowledge exchange and numerical approaches that transform, integrate, and visualize data.

  18. Tracer monitoring of enhanced oil recovery projects

    Directory of Open Access Journals (Sweden)

    Kleven R.

    2013-05-01

    Full Text Available In enhanced oil recovery (EOR, chemicals are injected into the oil reservoir, either to increase macroscopic sweep efficiency, or to reduce remaining oil saturation in swept zones. Tracers can be used to identify reservoirs that are specifically suited for EOR operations. Injection of a selection of partitioning tracers, combined with frequent sample analysis of produced fluids, provides information suited for estimation of residual oil saturation. Tracers can also be used to evaluate and optimize the application of EOR chemicals in the reservoir. Suitable tracers will follow the EOR chemicals and assist in evaluation of retention, degradation or trapping. In addition to field applications, tracers also have a large potential as a tool to perform mechanistic studies of EOR chemicals in laboratory experiments. By labelling EOR chemicals with radioactive isotopes of elements such as H, C and S, detailed studies of transport mechanisms can be carried out. Co-injection of labelled compounds in dynamic flooding experiments in porous media will give information about retention or separation of the unique compounds constituting the chemical formulation. Separation of such compounds may be detrimental to obtaining the EOR effect expected. The paper gives new information of specific methods, and discusses current status for use of tracers in EOR operations.

  19. Doublet tracer tests to determine the contaminant flushing properties of a municipal solid waste landfill.

    Science.gov (United States)

    Woodman, N D; Rees-White, T C; Beaven, R P; Stringfellow, A M; Barker, J A

    2017-08-01

    This paper describes a programme of research investigating horizontal fluid flow and solute transport through saturated municipal solid waste (MSW) landfill. The purpose is to inform engineering strategies for future contaminant flushing. Solute transport between injection/abstraction well pairs (doublets) is investigated using three tracers over five separate tests at well separations between 5m and 20m. Two inorganic tracers (lithium and bromide) were used, plus the fluorescent dye tracer, rhodamine-WT. There was no evidence for persistent preferential horizons or pathways at the inter-well scale. The time for tracer movement to the abstraction wells varied with well spacing as predicted for a homogeneous isotropic continuum. The time for tracer movement to remote observation wells was also as expected. Mobile porosity was estimated as ~0.02 (~4% of total porosity). Good fits to the tracer breakthrough data were achieved using a dual-porosity model, with immobile regions characterised by block diffusion timescales in the range of about one to ten years. This implies that diffusional exchanges are likely to be very significant for engineering of whole-site contaminant flushing and possibly rate-limiting. Copyright © 2017. Published by Elsevier B.V.

  20. Prediction of non-brittle fracture in the welded joint of C-Mn steel in the brittle-ductile transition domain

    International Nuclear Information System (INIS)

    Nguyen, Thai Ha

    2009-11-01

    This work concerns the nuclear safety, specifically the secondary circuit integrity of pressurized water reactors (PWR). The problem is that of the fracture of a thin tubular structure in ferritic steel with many welded joints. The ferritic steel and weld present a brittle/ductile tenacity transition. Moreover, the welds present geometry propitious to the appearance of fatigue cracks, due to vibrations and expansions. These cracks may cause the complete fracture of the structure. The objectives of this work are to establish a criterion of non-fracture by cleavage of thin welded structures in ferritic steel, applicable to actual structures. Therefore, the present study focuses on the fracture behaviour of welded thin structures in brittle/ductile transition. It aims at developing the threshold stress model initially proposed by Chapuliot, to predict the non-brittle-fracture of this welded structure. The model is identified for the welded joint in C-Mn steel for nuclear construction, specifically in the upper part of the transition. A threshold stress, below which the cleavage cannot take place, is identified using tensile tests at low temperature on axis-symmetrical notched specimens taken in welded joint. This threshold stress is used to define the threshold volume where the maximum principal stress exceeds the threshold stress during the test. The analysis by SEM of specimen fracture surfaces shows that the gross solidification molten zone in the weld is the most likely to cleave. The relation between the brittle fracture probability and the threshold volume in the gross solidification molten zone is established via a sensitivity function, using multi-materials simulations. The model thus identified is tested for the prediction of non-brittle-fracture of SENT specimens taken in the welded joint and tested in tension. The results obtained are encouraging with regards to the transferability of the model to the actual structure. (author)

  1. Keeping the secret: Insights from repeated catchment-scale tracer experiments under transient conditions

    Science.gov (United States)

    Bogner, Christina; Hauhs, Michael; Lange, Holger

    2016-04-01

    Catchment-level tracer experiments are generally performed to identify site-specific hydrological response functions of the catchment. The existence and uniqueness of these response functions are hardly ever questioned. Here, we report on a series of replicated tracer experiments in two small first-order catchments, G1 (0.6 ha, roofed) and F4 (2.3 ha, without roof) at Gårdsjön in SW Sweden. The soils in both catchments are shallow (500 m2) the experiments were done without a roof mostly at transient conditions. The catchment F4 was equipped with a sprinkler system with a watering capacity of around 38-45 m3 day-1. Natural rainfall comes in addition. A bromide tracer solution was injected to groundwater at a single location about 40 m upstream the weir over a period of less than an hour, and was monitored using a set of groundwater tubes and the weir at the outlet over the following 4 days. In addition, discharge was measured. The experiments were repeated each summer from 2007 to 2015. While steady state conditions were guaranteed in G1, steady runoff has been achieved only four times in F4. We investigated tracer recovery rates against cumulated runoff since tracer application. Substantially different transit times and qualitatively different behaviour of the breakthrough curves were observed, even under steady state conditions. In G1, no single system response function could be identified in 5 replicates. Similarly, the catchment response functions in F4 under steady state differed between experiments. However, they remained in a similar range as in G1. Based on these results, we question the identifiability of flow paths and system properties, such as saturated water content or hydrologic transmissivity, at the catchment scale using tracer experiments. Rather, the series demonstrate the utter importance of the initial and boundary conditions which largely determine the response of the system to inert tracer pulses.

  2. Effluent dispersion in natural water receivers (tracer examination)

    International Nuclear Information System (INIS)

    Szpilowski, S.; Owczarczyk, A.; Chmielewski, A.G.

    1993-01-01

    Tracer methods constitute very convenient means for observation and examination of effluent dispersion and dilution processes in natural water receivers. In the report there are presented methods developed and used by the Institute of Nuclear Chemistry and Technology (INCT) to measure mixing parameters in natural streams to determine distances of complete transverse mixing as well as to assess and predict dispersion of sewage in large water reservoirs. There are also presented the methods of predicting initial stage of dispersion of sewage discharged into large water reservoirs through underwater out falls and the method for determining the decomposition rates of effluent entering a natural water receiver. The methods presented can be used in analysis of pollution in a given water region, in selection of optimal sewage out fall locations as well as in prediction of effluent dilution intensity at different hydro- and meteorological conditions. (author). 27 refs, 15 figs, 2 tabs

  3. Design and utilisation of protocols to characterise dynamic PET uptake of two tracers using basis pursuit

    Science.gov (United States)

    Bell, Christopher; Puttick, Simon; Rose, Stephen; Smith, Jye; Thomas, Paul; Dowson, Nicholas

    2017-06-01

    Imaging using more than one biological process using PET could be of great utility, but despite previously proposed approaches to dual-tracer imaging, it is seldom performed. The alternative of performing multiple scans is often infeasible for clinical practice or even in research studies. Dual-tracer PET scanning allows for multiple PET radiotracers to be imaged within the same imaging session. In this paper we describe our approach to utilise the basis pursuit method to aid in the design of dual-tracer PET imaging experiments, and later in separation of the signals. The advantage of this approach is that it does not require a compartment model architecture to be specified or even that both signals are distinguishable in all cases. This means the method for separating dual-tracer signals can be used for many feasible and useful combinations of biology or radiotracer, once an appropriate scanning protocol has been decided upon. Following a demonstration in separating the signals from two consecutively injected radionuclides in a controlled experiment, phantom and list-mode mouse experiments demonstrated the ability to test the feasibility of dual-tracer imaging protocols for multiple injection delays. Increases in variances predicted for kinetic macro-parameters V D and K I in brain and tumoral tissue were obtained when separating the synthetically combined data. These experiments confirmed previous work using other approaches that injections delays of 10-20 min ensured increases in variance were kept minimal for the test tracers used. On this basis, an actual dual-tracer experiment using a 20 min delay was performed using these radio tracers, with the kinetic parameters (V D and K I) extracted for each tracer in agreement with the literature. This study supports previous work that dual-tracer PET imaging can be accomplished provided certain constraints are adhered to. The utilisation of basis pursuit techniques, with its removed need to specify a model

  4. Tropical and Subtropical Cloud Transitions in Weather and Climate Prediction Models: The GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI)

    Science.gov (United States)

    Teixeira, J.; Cardoso, S.; Bonazzola, M.; Cole, J.; DeGenio, A.; DeMott, C.; Franklin, C.; Hannay, C.; Jakob, C.; Jiao, Y.; hide

    2011-01-01

    A model evaluation approach is proposed in which weather and climate prediction models are analyzed along a Pacific Ocean cross section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade winds, to the deep convection regions of the ITCZ the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/ WGNE) Pacific Cross-Section Intercomparison (GPCI). The main goal of GPCI is to evaluate and help understand and improve the representation of tropical and subtropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross section from the subtropics to the tropics for the season June July August of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the 40-yr ECMWF Re-Analysis (ERA-40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical cross sections of cloud properties (in particular), vertical velocity, and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA-40 in the stratocumulus regions [as compared to the first International Satellite Cloud Climatology Project (ISCCP)] is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too

  5. Stable isotopes as tracers for radionuclides

    International Nuclear Information System (INIS)

    Giussani, A.; Bartolo, D. de; Cantone, M.C.; Zilker, T.; Greim, H.; Roth, P.; Werner, E.

    2000-01-01

    The assessment of internal dose after incorporation of radionuclides requires as input data the knowledge of the uptake into the systemic circulation, the distribution and retention in selected organs, the excretion pathways. Realistic biokinetic models are needed for reliable estimates, correct interpretation of bioassay measurements, appropriate decision-making in radiological emergencies. For many radionuclides, however, the biokinetic models currently recommended are often generic, with very few specific parameters, due to the lack of experimental human data. The use of stable isotopes as tracers enables to determine important biokinetic parameters such as the fractional uptake, the clearance from the transfer compartment, the excretion patterns under experimentally controlled conditions. The subjects investigated are not exposed to any radiation risk, so this technique enables to obtain biokinetic information also for sensitive groups of the population, such as children or pregnant women, and to determine age- and gender-specific model parameters. Sophisticated analytical method, able to discriminate and quantitate different isotopes of the same element in complex matrices such as biological fluids, have to be purposely developed and optimized. Activation analysis and mass spectrometry are the most proper techniques of choice. Experiments were conducted with molybdenum, tellurium, ruthenium and zirconium. Activation analysis with protons, thermal ionization mass spectrometry and inductively coupled mass spectrometry were employed for the determination of stable isotopes of these elements in blood plasma and urine samples. Several deviations from the predictions of the ICRP models were observed. For example, modifications to the current model for molybdenum have been suggested on the basis of these results. The dose coefficients to the target regions calculated with this proposed model are even of one order of magnitude different than the ICRP estimates

  6. Proceedings of Tracer 3. International Conference on Tracers and Tracing Methods

    International Nuclear Information System (INIS)

    2004-01-01

    Tracer 3 conference is a continuation of former Tracer 1 (1998) and Tracer 2 (2001) conferences organized by CNRS - Nancy France. The objective of this 3rd conference is presentation of different aspects of tracer method applications and development of tracer methodology.The new field of activity presented at the Conference was application of stable isotopes as natural tracers for investigations of environmental processes. The conference gave the possibility for scientific information exchange between specialists from different fields of activity such as chemical engineering, chemistry, bioengineering, environmental engineering, hydrology, civil engineering, metallurgy, etc. The presentations were divided into groups covering the principal items of Conference. Section A. Fundamental development - RTD and tracer methodology, - RTD methodology and Computational Fluid Dynamics (CFD), - New tracers and detectors. Section B. Industrial applications - Environment, - Geology, hydrogeology and oil field applications, - Civil engineering, mineral engineering and metallurgy applications, - Food engineering and bioengineering, - Material engineering, - Chemical engineering. During the Conference INIS promotion materials were exposed by INIS liaison officer for Poland

  7. Proceedings of Tracer 3. International Conference on Tracers and Tracing Methods

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Tracer 3 conference is a continuation of former Tracer 1 (1998) and Tracer 2 (2001) conferences organized by CNRS - Nancy France. The objective of this 3rd conference is presentation of different aspects of tracer method applications and development of tracer methodology.The new field of activity presented at the Conference was application of stable isotopes as natural tracers for investigations of environmental processes. The conference gave the possibility for scientific information exchange between specialists from different fields of activity such as chemical engineering, chemistry, bioengineering, environmental engineering, hydrology, civil engineering, metallurgy, etc. The presentations were divided into groups covering the principal items of Conference. Section A. Fundamental development - RTD and tracer methodology, - RTD methodology and Computational Fluid Dynamics (CFD), - New tracers and detectors. Section B. Industrial applications - Environment, - Geology, hydrogeology and oil field applications, - Civil engineering, mineral engineering and metallurgy applications, - Food engineering and bioengineering, - Material engineering, - Chemical engineering. During the Conference INIS promotion materials were exposed by INIS liaison officer for Poland.

  8. Long residence times - bad tracer tests?

    Science.gov (United States)

    Ghergut, Julia; Behrens, Horst; Sauter, Martin

    2015-04-01

    Tracer tests conducted at geothermal well doublets or triplets in the Upper Rhine Rift Valley [1] all face, with very few exceptions so far, one common issue: lack of conclusive tracer test results, or tracer signals still undetectable for longer than one or two years after tracer injection. While the reasons for this surely differ from site to site (Riehen, Landau, Insheim, Bruchsal, ...), its effects on how the usefulness of tracer tests is perceived by the non-tracer community are pretty much the same. The 'poor-signal' frustration keeps nourishing two major 'alternative' endeavours : (I) design and execute tracer tests in single-well injection-withdrawal (push-pull), 'instead of' inter-well flow-path tracing configurations; (II) use 'novel' tracer substances instead of the 'old' ones which have 'obviously failed'. Frustration experienced with most inter-well tracer tests in the Upper Rhine Rift Valley has also made them be regarded as 'maybe useful for EGS' ('enhanced', or 'engineered' geothermal systems, whose fluid RTD typically include a major share of values below one year), but 'no longer worthwhile a follow-up sampling' in natural, large-scale hydrothermal reservoirs. We illustrate some of these arguments with the ongoing Bruchsal case [2]. The inter-well tracer test conducted at Bruchsal was (and still is!) aimed at assessing inter-well connectivity, fluid residence times, and characterizing the reservoir structure [3]. Fluid samples taken at the geothermal production well after reaching a fluid turnover of about 700,000 m3 showed tracer concentrations in the range of 10-8 Minj per m3, in the liquid phase of each sample (Minj being the total quantity of tracer injected as a short pulse at the geothermal re-injection well). Tracer signals might actually be higher, owing to tracer amounts co-precipitated and/or adsorbed onto the solid phase whose accumulation in the samples was unavoidable (due to pressure relief and degassing during the very sampling

  9. Predict the glass transition temperature and plasticization of β-cyclodextrin/water binary system by molecular dynamics simulation.

    Science.gov (United States)

    Zhou, Guohui; Zhao, Tianhai; Wan, Jie; Liu, Chengmei; Liu, Wei; Wang, Risi

    2015-01-12

    The glass transition temperature, diffusion behavior and plasticization of β-cyclodextrin (β-CD), and three amorphous β-CD/water mixtures (3%, 5% and 10% [w/w] water, respectively) were investigated by molecular dynamics simulation, which were performed using Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field and isothermal-isobaric ensembles. The specific volumes of four amorphous cells were obtained as a function of temperature. The glass transition temperatures (T(g)) were estimated to be 334.25 K, 325.12 K, 317.32 K, and 305.41 K for amorphous β-CD containing 0%, 3%, 5% and 10% w/w water, respectively, which compares well with the values observed in published literature. The radial distribution function was computed to elucidate the intermolecular interactions between amorphous β-CD and water, which acts as a plasticizer. These results indicate that the hydrogen bond interactions of oxygen in hydroxyl ions was higher than oxygen in acetal groups in β-CD amorphous mixtures with that in water, due to less accessibility of ring oxygens to the surrounding water molecules. The mobility of water molecules was investigated over various temperature ranges, including the rubbery and glassy phases of the β-CD/water mixtures, by calculating the diffusion coefficients and the fractional free volume. In β-CD amorphous models, the higher mobility of water molecules was observed at temperatures above Tg, and almost no change was observed at temperatures below T(g). Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. TRACER - TRACING AND CONTROL OF ENGINEERING REQUIREMENTS

    Science.gov (United States)

    Turner, P. R.

    1994-01-01

    TRACER (Tracing and Control of Engineering Requirements) is a database/word processing system created to document and maintain the order of both requirements and descriptive material associated with an engineering project. A set of hierarchical documents are normally generated for a project whereby the requirements of the higher level documents levy requirements on the same level or lower level documents. Traditionally, the requirements are handled almost entirely by manual paper methods. The problem with a typical paper system, however, is that requirements written and changed continuously in different areas lead to misunderstandings and noncompliance. The purpose of TRACER is to automate the capture, tracing, reviewing, and managing of requirements for an engineering project. The engineering project still requires communications, negotiations, interactions, and iterations among people and organizations, but TRACER promotes succinct and precise identification and treatment of real requirements separate from the descriptive prose in a document. TRACER permits the documentation of an engineering project's requirements and progress in a logical, controllable, traceable manner. TRACER's attributes include the presentation of current requirements and status from any linked computer terminal and the ability to differentiate headers and descriptive material from the requirements. Related requirements can be linked and traced. The program also enables portions of documents to be printed, individual approval and release of requirements, and the tracing of requirements down into the equipment specification. Requirement "links" can be made "pending" and invisible to others until the pending link is made "binding". Individuals affected by linked requirements can be notified of significant changes with acknowledgement of the changes required. An unlimited number of documents can be created for a project and an ASCII import feature permits existing documents to be incorporated

  11. Tracers of air-sea gas exchange

    International Nuclear Information System (INIS)

    Liss, P.S.

    1988-01-01

    The flux of gas across the air-sea interface is determined by the product of the interfacial concentration difference driving the exchange and a rate constant, often termed the transfer velocity. The concentration-difference term is generally obtained by direct measurement, whereas more indirect approaches are required to estimate the transfer velocity and its variation as a function of controlling parameters such as wind and sea state. Radioactive tracers have proved particularly useful in the estimation of air-sea transfer velocities and, recently, stable purposeful tracers have also started to be used. In this paper the use of the following tracers to determine transfer velocities at the sea surface is discussed: natural and bomb-produced 14 C, dissolved oxygen, 222 Rn and sulphur hexafluoride. Other topics covered include the relation between transfer velocity and wind speed as deduced from tracer and wind-tunnel studies, and the discrepancy between transfer velocities determined by using tracers and from eddy correlation measurements in the atmosphere. (author)

  12. Evaluation of single- and dual-porosity models for reproducing the release of external and internal tracers from heterogeneous waste-rock piles.

    Science.gov (United States)

    Blackmore, S; Pedretti, D; Mayer, K U; Smith, L; Beckie, R D

    2018-05-30

    Accurate predictions of solute release from waste-rock piles (WRPs) are paramount for decision making in mining-related environmental processes. Tracers provide information that can be used to estimate effective transport parameters and understand mechanisms controlling the hydraulic and geochemical behavior of WRPs. It is shown that internal tracers (i.e. initially present) together with external (i.e. applied) tracers provide complementary and quantitative information to identify transport mechanisms. The analysis focuses on two experimental WRPs, Piles 4 and Pile 5 at the Antamina Mine site (Peru), where both an internal chloride tracer and externally applied bromide tracer were monitored in discharge over three years. The results suggest that external tracers provide insight into transport associated with relatively fast flow regions that are activated during higher-rate recharge events. In contrast, internal tracers provide insight into mechanisms controlling solutes release from lower-permeability zones within the piles. Rate-limited diffusive processes, which can be mimicked by nonlocal mass-transfer models, affect both internal and external tracers. The sensitivity of the mass-transfer parameters to heterogeneity is higher for external tracers than for internal tracers, as indicated by the different mean residence times characterizing the flow paths associated with each tracer. The joint use of internal and external tracers provides a more comprehensive understanding of the transport mechanisms in WRPs. In particular, the tracer tests support the notion that a multi-porosity conceptualization of WRPs is more adequate for capturing key mechanisms than a dual-porosity conceptualization. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Soil homogeneity evaluation by radionuclide tracer breakthrough curve interpretation

    International Nuclear Information System (INIS)

    Brenizer, J.S. Jr.; Jarrett, A.R.; Jester, W.A.

    1980-01-01

    Increasing concern about the environmental impact of hazardous waste disposal has made site evaluation and site selection difficult and expensive. Pollutants, assumed to be absorbed by the soil immediately surrounding the burial trench, have been detected far from sites. Discrepancies between predicted migration distances based on indirect methods such as laboratory and computer modeling and those observed at the field site are often significant. The homogeneity of subsurface media, often assumed in laboratory and modeling studies, is seldom found in the field. The use of tracers to determine the flow characteristics of a potential disposal site involves time and expense, but offers a direct evaluation of solute transport and eliminates the assumptions inherent in indirect methods. Current modeling of solute transport in nonhomogeneous porous media is limited by the quantification of input parameters. Several general models can predict solute transport in saturated-unsaturated media from low-level disposal sites if the hydraulic characteristics and chemical reactions expected in each unique water-solute-media system can be defined. The objective of this research was to develop a method of evaluating potential shallow-land burial waste disposal sites by interpreting tracer breakthrough curve structure with respect to the hydrologic properties of the media at the potential disposal site. This methodology will be helpful in evaluating the potential performance of many types of shallow-land waste burial sites such as low-level radioactive waste disposal, surface disposal of flyash, chemical waste disposal, waste sedimentation ponds, and sanitary landfills

  14. Coefficients of tracer transfer through membranes. Pt. 7

    Energy Technology Data Exchange (ETDEWEB)

    Dorabialska, A; Hawlicka, E; Plonka, A [Politechnika Lodzka (Poland)

    1974-01-01

    The doubled value of the tracer transfer coefficient in the self-diffusion process is equal to the sum of tracer transfer coefficients in the diffusion and interfusion processes. The fundamental phenomenological relation can be deduced for the coefficients of tracer transfer between two phases of electrolyte solutions spearated by a virtual boundary. Indeed, the doubled value of the tracer mobility in the self-diffusion experiment (no concentration gradient of the traced substance) is equal to the sum of the tracer mobilities in the diffusion (tracer movement along with the concentration gradient of the traced substance) and interfusion experiments (tracer movement against the concentration gradient of the traced substance). Thus the doubled value of the tracer transfer coefficient in the self-diffusion process should be equal to the sum of tracer transfer coefficients in the diffusion and interfusion processes. The experimental verification of that fundamental relation is presented.

  15. Simulation and interpretation of inter-well tracer tests

    Directory of Open Access Journals (Sweden)

    Dugstad Øyvind

    2013-05-01

    Full Text Available In inter-well tracer tests (IWTT, chemical compounds or radioactive isotopes are used to label injection water and gas to establish well connections and fluid patterns in petroleum reservoirs. Tracer simulation is an invaluable tool to ease the interpretation of IWTT results and is also required for assisted history matching application of tracer data. In this paper we present a new simulation technique to analyse and interpret tracer results. Laboratory results are used to establish and test formulations of the tracer conservation equations, and the technique is used to provide simulated tracer responses that are compared with observed tracer data from an extensive tracer program. The implemented tracer simulation methodology use a fast post-processing of previously simulated reservoir simulation runs. This provides a fast, flexible and powerful method for analysing gas tracer behaviour in reservoirs. We show that simulation time for tracers can be reduced by factor 100 compared to solving the tracer flow equations simultaneously with the reservoir fluid flow equations. The post-processing technique, combined with a flexible built-in local tracer-grid refinement is exploited to reduce numerical smearing, particularly severe for narrow tracer pulses.

  16. Enhanced Oil Recovery: Aqueous Flow Tracer Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Rovani; John Schabron

    2009-02-01

    A low detection limit analytical method was developed to measure a suite of benzoic acid and fluorinated benzoic acid compounds intended for use as tracers for enhanced oil recovery operations. Although the new high performance liquid chromatography separation successfully measured the tracers in an aqueous matrix at low part per billion levels, the low detection limits could not be achieved in oil field water due to interference problems with the hydrocarbon-saturated water using the system's UV detector. Commercial instrument vendors were contacted in an effort to determine if mass spectrometry could be used as an alternate detection technique. The results of their work demonstrate that low part per billion analysis of the tracer compounds in oil field water could be achieved using ultra performance liquid chromatography mass spectrometry.

  17. Biological tracer for waste site characterization

    International Nuclear Information System (INIS)

    Strong-Gunderson, J.

    1995-01-01

    Remediating hazardous waste sites requires detailed site characterization. In groundwater remediation, characterizing the flow paths and velocity is a major objective. Various tracers have been used for measuring groundwater velocity and transport of contaminants, colloidal particles, and bacteria and nutrients. The conventional techniques use dissolved solutes, dyes. and gases to estimate subsurface transport pathways. These tracers can provide information on transport and diffusion into the matrix, but their estimates for groundwater flow through fractured regions are very conservative. Also, they do not have the same transport characteristics as bacteria and suspended colloid tracers, both of which must be characterized for effective in-place remediation. Bioremediation requires understanding bacterial transport and nutrient distribution throughout the acquifer, knowledge of contaminants s mobile colloidal particles is just essential

  18. Bioenergetic model predictions of actual growth and allometric transitions during ontogeny of juvenile blue mussels Mytilus edulis

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Lundgreen, Kim; Riisgård, Hans Ulrik

    2013-01-01

    > 10 mm followed a power-law (W = 2.15L3.40) which supplemented an existing power-law for L ... with predictions based on a previously developed bioenergetic growth model (BEG) for W> 10 mg (μ =aWb, a = 0.871× C – 0.986; b = –0.34, with μ in % d−1 and W in g) which explicitly takes into account the prevailing chla concentration C (μg L−1). Results for Wpower-law (μ =a...

  19. Mass distribution and multiple fragmentation events in high energy cluster-cluster collisions: evidence for a predicted phase transition

    International Nuclear Information System (INIS)

    Farizon, B.; Farizon, M.; Gaillard, M.J.; Genre, R.; Louc, S.; Martin, J.; Senn, G.; Scheier, P.; Maerk, T.D.

    1996-09-01

    Fragment size distributions including multiple fragmentation events have been measured for high energy H 25 + cluster ions (60 keV/amu) colliding with a neutral C 60 target. In contrast to earlier collision experiments with a helium target the present studies do not show a U-shaped fragment mass distribution, but a single power-law falloff with increasing fragment mass. This behaviour is similar to what is known for the intermediate regime in nuclear collision physics and thus confirms a recently predicted scaling from nuclear to molecular collisions

  20. Use of radioactive tracers in dynamic sedimentology

    International Nuclear Information System (INIS)

    Tola, Francois.

    1982-01-01

    In the first part, developments in the use of radioactive tracers in sedimentology are recalled together with the corresponding fields of application and the identities of the main users. The state-of-the-art in France is also discussed; The main characteristics of the method are then described and compared with those of more classical methods. The results that can be obtained with tracer methods are then outlined. The criteria employed to establish the granulometry characteristics of the tracer, the particular radioisotope to be used, and the masses and activities involved, are treated. A list is then given of the main isotopes available in France and their characteristics. The various different labelling techniques employed are studied together with their respective advantages and disadvantages. The special case of pelitic sediments is mentioned. The use of reduced model isotope generators, double labelling and applications to studies of the mud plug in the Gironde Estuary are also discussed. The methods and materials used for injecting and detecting tracers are described, emphasis being given to the economic factors associated with the use of radioactive tracers in sedimentology. The second part of the report contains two chapters: - studies of transport by driftage: presentation and analysis of results and the application of the Count Rate Balance method to obtain quantitative information on transport; - studies of in-suspension transport of fine sediments in the sea: the procedures adopted from the moment when the tracer is introduced up to the time when the results are analyzed and interpreted, enables the trajectories and mean velocities of the transported sediments to be determined together with their degree of dilution and their settling speeds and rates; it is also possible to investigate the evolution and horizontal dispersion of the sediments in this way. Results from recent experiments are presented in both parts of the report

  1. Tracer applications in oil reservoirs in Brazil

    International Nuclear Information System (INIS)

    Moreira, R.M.; Ferreira Pinto, A.M.

    2004-01-01

    Radiotracer applications in oil reservoirs in Brazil started in 1997 at the request of the State Oil Company (Petrobras) at the Carmoplois oilfield. 1 Ci of HTO was injected in a regular five-spot plot and the results obtained were quite satisfactory. Shortly after this test one other request asked for distinguishing the contribution of different injection wells to a production well. It was then realized that other tracers should be available. As a first choice 35 SCN - has been selected since it could be produced at CDTN. An alternative synthesis path was defined which shortened post-irradiation manipulations. The tracer was tested in core samples and a field injection, simultaneously with HTO, was carried out at the Buracica field; again the HTO performed well but 35 SCN - showed up well ahead. Presently the HTO applications are being done on a routine basis. All in all, four tests were performed (some are still ongoing), and the detection limits for both 3 H and 35 S were optimized by refining the sample preparation stage. Lanthanide complexes used as activable tracers are also an appealing option, however core tests performed so far with La-, Ce- and Eu-EDTA indicated some delay of the tracer, so other complexants such as DOTA are to be tried in further laboratory tests and in a field application. Thus, a deeper understanding of their complexation chemistry and carefully conducted tests must be performed before lanthanide complexes can be qualified as reliable oil reservoir tracers. More recently, Petrobras has been asking for partitioning tracers intended for SOR measurement

  2. Geologic flow characterization using tracer techniques

    International Nuclear Information System (INIS)

    Klett, R.D.; Tyner, C.E.; Hertel, E.S. Jr.

    1981-04-01

    A new tracer flow-test system has been developed for in situ characterization of geologic formations. This report describes two sets of test equipment: one portable and one for testing in deep formations. Equations are derived for in situ detector calibration, raw data reduction, and flow logging. Data analysis techniques are presented for computing porosity and permeability in unconfined isotropic media, and porosity, permeability and fracture characteristics in media with confined or unconfined two-dimensional flow. The effects of tracer pulse spreading due to divergence, dispersion, and porous formations are also included

  3. SIMULASI JARINGAN KOMPUTER MENGGUNAKAN CISCO PACKET TRACER

    Directory of Open Access Journals (Sweden)

    M Mufadhol

    2012-01-01

    Full Text Available Perkembangan jaringan komputer saat ini begitu pesat, monitoring jaringan komputer akan menjadi suatu hal yang sulit dan rumit. Koneksi jaringan komputer merupakan suatu hal yang mendasar dalam suatu jaringan, karena bila koneksi itu bermasalah maka semua jenis aplikasi yang dijalankan melalui jaringan komputer tidak dapat digunakan. Cisco packet tracer dapat digunakan untuk simulasi yang mencerminkan arsitektur dan juga model dari jaringan komputer pada sistem jaringan yang digunakan. Dengan menggunakan aplikasi cisco packet tracer, simulasi mengenai jaringan dapat dimanfaatkan menjadi informasi tentang keadaan koneksi komputer dalam suatu jaringan.

  4. Employee Turnover Prediction Based on State-transition and Semi-Markov- A Case Study of Chinese State-owned Enterprise

    Directory of Open Access Journals (Sweden)

    Fang Ming

    2017-01-01

    Full Text Available As a main direction of Human Resource Management, employee turnover can provide decision support for managers. In this paper, we aim at predicting the turnover amount of employee on condition of different variable values. The properties of employee and job position are formulated as two variables, where the value of variable varies according to the the state of properties. Additionally, state-transition model is applied to describing employee’s job-state as well as the turnover type. Subsequently, we proposed a semi-Markov model to calculate the conditional turnover amount of employee. Then, we provide a dataset of employee records to illustrate how these models work in reality. Finally, it is proven that the proposed method in this paper is with great significance for managers to develop recruitment plans, promote rules, and retire regulations

  5. Models and criteria for prediction of Deflagration-to-Detonation Transition (DDT) in hydrogen-air-steam systems under severe accident conditions. Final report

    International Nuclear Information System (INIS)

    Klein, R.; Rehm, W.

    1999-01-01

    The European Commission in Brussels supported a joint project on Deflagration-to-Detonation Transition (DDT) studies for hydrogen safety within the framework programme on nuclear fission safety. The project was initiated by the Forschungszentrum Juelich based on the results of a pilot project. The following main project was coordinated by the Freie Universitaet Berlin involving seven european partners. The partners came from universities, research centers and industry, as follows: FU-Berlin, RWTH-Aachen, CNRS-Marseille, IPSN-Saclay, FZ-Juelich, FZ-Karlsruhe, and NNC-Knutsford, which worked closely together. The working period was two years (1997-1998). The aim of the project was to develop models and criteria for prediction of deflagration-to-detonation transition (DDT) in hydrogen-air-steam systems under severe accident conditions. The results obtained are documented in this final report, which was finished in 1999. The report consists of seven chapters, concerning: - Introduction - Experimental Investigations - Modelling and Numerics - Validation - Mitigation - Further Deliverables - Summary and Conclusion. The final report presents special experimental, theoretical, and computational aspects of the complex DDT phenomena for hydrogen safety studies, and it should be a solid basis for end user applications and further developments. (orig.)

  6. Theoretical prediction of morphotropic compositions in Na1/2Bi1/2TiO3-based solid solutions from transition pressures

    Science.gov (United States)

    Gröting, Melanie; Albe, Karsten

    2014-02-01

    In this article we present a method based on ab initio calculations to predict compositions at morphotropic phase boundaries in lead-free perovskite solid solutions. This method utilizes the concept of flat free energy surfaces and involves the monitoring of pressure-induced phase transitions as a function of composition. As model systems, solid solutions of Na1/2Bi1/2TiO3 with the alkali substituted Li1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 and the alkaline earth substituted CaTiO3 and BaTiO3 are chosen. The morphotropic compositions are identified by determining the composition at which the phase transition pressure equals zero. In addition, we discuss the different effects of hydrostatic pressure (compression and tension) and chemical substitution on the antiphase tilts about the [111] axis (a-a-a-) present in pure Na1/2Bi1/2TiO3 and how they develop in the two solid solutions Na1/2Bi1/2TiO3-CaTiO3 and Na1/2Bi1/2TiO3-BaTiO3. Finally, we discuss the advantages and shortcomings of this simple computational approach.

  7. Selection of tracers for oil and gas evaluation

    International Nuclear Information System (INIS)

    Bjoernstad, T.

    1991-08-01

    The importance of tracer tests in reservoir descriptions is increasingly acknowledged by reservoir engineers as a method to obtain valuable dynamic information from the reservoir. The report describes the ''state-of-the art'' on tracer technology for interwell investigations. Experiences gained from a number of reported field tracer tests are reviewed, and results from detailed laboratory investigations on the static and dynamic behavior of various tracer molecules are discussed. A critical evaluation of the applicability of the various identified tracers is provided. Present and future trends in the development of tracer technology for reservoir description are sketched. 64 refs., 12 figs., 2 tabs

  8. Rac1 overexpression is correlated with epithelial mesenchymal transition and predicts poor prognosis in non-small cell lung cancer.

    Science.gov (United States)

    Zhou, Yujuan; Liao, Qianjin; Han, Yaqian; Chen, Jie; Liu, Zhigang; Ling, Hang; Zhang, Jing; Yang, Wenjuan; Oyang, Linda; Xia, Longzheng; Wang, Li; Wang, Heran; Xue, Lei; Wang, Hui; Hu, Bingqiang

    2016-01-01

    Objective: Ras-related C3 botulinum toxin substrate1(Rac1) and epithelial mesenchymal transition (EMT) are key therapeutic targets in cancer. We investigated the clinical significance of Rac1 and markers of EMT expression in non-small cell lung cancer (NSCLC), and their possible correlation with EMT phenotype. Methods: Immunohistochemistry was used to assess the expression of Rac1, Snail1, Twist1, N-cadherin (N-cad), Vimentin (Vim), and E-cadherin (E-cad) in 153 NSCLC paraffin-embedded specimens and 45 normal specimens adjacent to tumors. The correlation of Rac1 and EMT markers with clinicopathological characteristics and the relationship between the protein levels and progression-free survival (PFS) and overall survival (OS) were analyzed. Results: Compared with non-tumor tissues, the NSCLC tissues showed marked elevation in the levels of Rac1, Snail1, Twist1, N-cad, and Vim levels, whereas the E-cad levels were significantly decreased (P Rac1 and EMT markers was significantly associated with TNM stage and metastasis (P Rac1 may be associated with poor OS and PFS compared with low expression (PRac1, Snail1, Twist1, N-cad, Vim, and E-cad was an independent prognostic factor in NSCLC. Interestingly, Rac1 expression was positively correlated with Snail1, Twist1, N-cad, and Vim levels (r=0.563, r=0.440, r=0.247 r=0.536, PRac1, Twist, Snail1, Vim and N-cad were highly expressed in lung cancer patients resistant to radiotherapy, while E-cad was poorly expressed. Conclusion: Rac1 may promote NSCLC progression and metastasis via EMT, which may be considered as a potential therapeutic target.

  9. Simulating and Predicting the Impacts of Light Rail Transit Systems on Urban Land Use by Using Cellular Automata: A Case Study of Dongguan, China

    Directory of Open Access Journals (Sweden)

    Jinyao Lin

    2018-04-01

    Full Text Available The emergence of Light Rail Transit systems (LRTs could exert considerable impacts on sustainable urban development. It is crucial to predict the potential land use changes since LRTs are being increasingly built throughout the world. While various land use and land cover change (LUCC models have been developed during the past two decades, the basic assumption for LUCC prediction is the continuation of present trends in land use development. It is therefore unreasonable to predict potential urban land use changes associated with LRTs simply based on earlier trends because the impacts of LRT investment may vary greatly over time. To tackle this challenge, our study aims to share the experiences from previous lines with newly planned lines. Dongguan, whose government decided to build LRTs around 2008, was selected as the study area. First, we assessed the impacts of this city’s first LRT (Line R2 on three urban land use types (i.e., industrial development, commercial and residential development, and rural development at different periods. The results indicate that Line R2 exerted a negative impact on industrial development and rural development, but a positive impact on commercial and residential development during the planning stage of this line. Second, such spatial impacts (the consequent land use changes during this stage were simulated by using artificial neural network cellular automata. More importantly, we further predicted the potential impacts of Line R1, which is assumed to be a newly planned line, based on the above calibrated model and a traditional method respectively. The comparisons between them demonstrate the effectiveness of our method, which can easily take advantage of the experiences from other LRTs. The proposed method is expected to provide technical support for sustainable urban and transportation planning.

  10. Granular controls on the dispersion of bed load tracers

    Science.gov (United States)

    Jerolmack, D. J.; Martin, R. L.; Phillips, C. B.

    2014-12-01

    Coarse particles are transported in a river as bed load, i.e., they move in frequent contact with and are supported by the granular bed. This movement is typically intermittent and may be described by a series of steps are rests, the distributions of which determine particle dispersion. Laboratory and field studies of bed load tracer dispersion have reported sub- and super-diffusive behavior, both of which have been successfully reproduced with stochastic transport models. Although researchers have invoked heavy-tailed step lengths as the cause of anomalous dispersion, most observations report thin-tailed distributions. Little attention has been paid to rest periods, and stochastic transport models have not been connected to the underlying mechanics of particle motion. Based on theoretical and experimental evidence, we argue that step lengths are thin-tailed and do not control the longterm dispersion of bed load tracers; they are determined by momentum balance between the fluid and solid. Using laboratory experiments with both marbles and natural sediments, we demonstrate that the rest time distribution is power law, and argue that this distribution controls asymptotic dispersion. Observed rest times far exceed any hydrodynamic timescale. Experiments reveal that rest times of deposited particles are governed by fluctuations in river bed elevation; in particular, the return time for the bed to scour to the base of a deposited particle. Stochastic fluctuations in bed elevation are describable by an Ornstein-Uhlenbeck (mean-reverting random walk) model that contains two parameters, which we show are directly related to the granular shear rate and range of bed elevation fluctuations, respectively. Combining these results with the theory of asymmetric random walks (particles only move downstream), we predict superdiffusive behavior that is in quantitative agreement with our observations of tracer dispersion in a natural river.

  11. Modelling and tracer studies of atmospheric dispersion and deposition in regions of complex topography

    International Nuclear Information System (INIS)

    Norden, C.E.

    1981-11-01

    An indium tracer aerosol generating apparatus based on an alcohol/oxygen burner, and an analytical procedure by which filter samples containing tracer material could be analysed quantitatively by means of neutron activation analysis, were developed for use in atmospheric dispersion and deposition studies. A number of series of atmospheric dispersion experiments were conducted in the Richards Bay and Koeberg- Cape Town areas. The results are given, comparing the airbone tracer concentrations measured at ground level with values predicted by means of a numerical model, utilising two to three schemes, varying in sophistication, for calculating the dispersion coefficients. Recommendations are given regarding a dispersion model and dispersion coefficients for regular use in the Koeberg area, and ways for estimating plume trajectories

  12. Tracer gas diffusion sampling test plan

    International Nuclear Information System (INIS)

    Rohay, V.J.

    1993-01-01

    Efforts are under way to employ active and passive vapor extraction to remove carbon tetrachloride from the soil in the 200 West Area an the Hanford Site as part of the 200 West Area Carbon Tetrachloride Expedited Response Action. In the active approach, a vacuum is applied to a well, which causes soil gas surrounding the well to be drawn up to the surface. The contaminated air is cleaned by passage through a granular activated carbon bed. There are questions concerning the radius of influence associated with application of the vacuum system and related uncertainties about the soil-gas diffusion rates with and without the vacuum system present. To address these questions, a series of tracer gas diffusion sampling tests is proposed in which an inert, nontoxic tracer gas, sulfur hexafluoride (SF 6 ), will be injected into a well, and the rates of SF 6 diffusion through the surrounding soil horizon will be measured by sampling in nearby wells. Tracer gas tests will be conducted at sites very near the active vacuum extraction system and also at sites beyond the radius of influence of the active vacuum system. In the passive vapor extraction approach, barometric pressure fluctuations cause soil gas to be drawn to the surface through the well. At the passive sites, the effects of barometric ''pumping'' due to changes in atmospheric pressure will be investigated. Application of tracer gas testing to both the active and passive vapor extraction methods is described in the wellfield enhancement work plan (Rohay and Cameron 1993)

  13. Use of labeled compounds in tracer experiments

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    The use of radiotracers in research has become common. This chapter looks at some of the underlying assumptions and advantages of labeled compounds: advantages of radiotracers; availability of suitable tracers and labeled compounds; purity of labeled compounds; autoradiolysis; storage of labeled compounds; detection systems for chromatography and electrophoretic methods. 14 refs., 2 figs

  14. Rate tracer studies of heterogeneous catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Happel, J; Kiang, S

    1977-10-01

    An analysis is presented of the extent to which parameters involved in transient tracing of isotopic species in heterogeneous catalysis can be determined by experiments in which tracer concentrations are measured as a function of time. Different treatments for open and closed systems with the over-all reaction at equilibrium or irreversible were developed.

  15. Nanoparticle tracers in calcium carbonate porous media

    KAUST Repository

    Li, Yan Vivian

    2014-07-15

    Tracers are perhaps the most direct way of diagnosing subsurface fluid flow pathways for ground water decontamination and for natural gas and oil production. Nanoparticle tracers could be particularly effective because they do not diffuse away from the fractures or channels where flow occurs and thus take much less time to travel between two points. In combination with a chemical tracer they can measure the degree of flow concentration. A prerequisite for tracer applications is that the particles are not retained in the porous media as the result of aggregation or sticking to mineral surfaces. By screening eight nanoparticles (3-100 nm in diameter) for retention when passed through calcium carbonate packed laboratory columns in artificial oil field brine solutions of variable ionic strength we show that the nanoparticles with the least retention are 3 nm in diameter, nearly uncharged, and decorated with highly hydrophilic polymeric ligands. The details of these column experiments and the tri-modal distribution of zeta potential of the calcite sand particles in the brine used in our tests suggests that parts of the calcite surface have positive zeta potential and the retention of negatively charged nanoparticles occurs at these sites. Only neutral nanoparticles are immune to at least some retention. © 2014 Springer Science+Business Media.

  16. Using neural networks to describe tracer correlations

    Directory of Open Access Journals (Sweden)

    D. J. Lary

    2004-01-01

    Full Text Available Neural networks are ideally suited to describe the spatial and temporal dependence of tracer-tracer correlations. The neural network performs well even in regions where the correlations are less compact and normally a family of correlation curves would be required. For example, the CH4-N2O correlation can be well described using a neural network trained with the latitude, pressure, time of year, and methane volume mixing ratio (v.m.r.. In this study a neural network using Quickprop learning and one hidden layer with eight nodes was able to reproduce the CH4-N2O correlation with a correlation coefficient between simulated and training values of 0.9995. Such an accurate representation of tracer-tracer correlations allows more use to be made of long-term datasets to constrain chemical models. Such as the dataset from the Halogen Occultation Experiment (HALOE which has continuously observed CH4  (but not N2O from 1991 till the present. The neural network Fortran code used is available for download.

  17. Using radioactive tracer technique in municipal hygiene

    International Nuclear Information System (INIS)

    Yurasova, O.I.

    1974-01-01

    Work of the A. N. Syrsin Institute of General and Municiapl Hygiene using raidoactive tracers is reviewed. The studies include research on protein metabolism in the living organism following action of unfavorable factors of the environment; determination of the paths of introduction into the organism of substances with an alien composition; and study of the rate of resorption of subcutaneous papuli. Results are shown of radioactive-tracer studies on the mechanism of action of poisonous substances on the living organism and of migration of alien chemical compounds in the organism and in objects in the environment. It is concluded that the radioactive tracer method has wide application in municipal hygiene and sanitary microbiology. The absence of laborious operations, economy of time, precision of the experiments, and the possibility of obtaining additional information on the mechanism of action of poisonous substances on the organism and the low cost of such studies compared with other methods makes the radioactive tracer method economically attractive. The studies made show the various types of use of the method in municipal hygiene and sanitary microbiology

  18. Hybrid tracers for sentinel node biopsy

    International Nuclear Information System (INIS)

    Van Den Berg, N. S.; Kleinjan, G. I.; Valdés-Olmos, R. A.; Buckle, T.; Van Leeuwen, F. I.; Klop, W. M.; Horenblas, S.; Van Der Poel, H. G.

    2014-01-01

    Conventional sentinel node (SN) mapping is performed by injection of a radiocolloid followed by lymphoscintigraphy to identify the number and location of the primary tumor draining lymph node(s), the so-called SN(s). Over the last decade research has focused on the introduction of new imaging agents that can further aid (surgical) SN identification. Different tracers for SN mapping, with varying sizes and isotopes have been reported, most of which have proven their value in a clinical setting. A major challenge lies in transferring this diagnostic information obtained at the nuclear medicine department to the operating theatre thereby providing the surgeon with (image) guidance. Conventionally, an intraoperative injection of vital blue dye or a fluorescence dye is given to allow intraoperative optical SN identification. However, for some indications, the radiotracer-based approach remains crucial. More recently, hybrid tracers, that contain both a radioactive and fluorescent label, were introduced to allow for direct integration of pre- and intraoperative guidance technologies. Their potential is especially high when they are used in combination with new surgical imaging modalities and navigation tools. Next to a description of the known tracers for SN mapping, this review discusses the application of hybrid tracers during SN biopsy and how the introduction of these new techniques can further aid in translation of nuclear medicine information into the operating theatre.

  19. Fractal tracer distributions in turbulent field theories

    DEFF Research Database (Denmark)

    Hansen, J. Lundbek; Bohr, Tomas

    1998-01-01

    We study the motion of passive tracers in a two-dimensional turbulent velocity field generated by the Kuramoto-Sivashinsky equation. By varying the direction of the velocity-vector with respect to the field-gradient we can continuously vary the two Lyapunov exponents for the particle motion and t...

  20. Suitability of tracers; Eignung von Tracern

    Energy Technology Data Exchange (ETDEWEB)

    Klotz, D. [GSF - Forschungszentrum fuer Umwelt und Gesundheit GmbH, Neuherberg (Germany). Inst. fuer Hydrologie

    1999-02-01

    Hydrological tracer techniques are a means of making statements on the direction and speed of underground water. One of the simpler tasks is to find out whether there is hydrological communication between two given points. This requires a determination of the direction of flow, which places less exacting demands on the properties of the tracer than does the task of determining the flow velocity of underground water. Tracer methods can serve to infer from flow velocity the distance (flow) velocity, which is defined as the ratio between the distance between two points located in flow direction and the actual time it takes water to flow from one to the other. [Deutsch] Mit Hilfe der hydrologischen Markierungstechniken koennen Aussagen ueber die Richtung und die Geschwindigkeit von Bewegungen des unterirdischen Wassers gemacht werden. Der einfachere Fall liegt vor, wenn festgestellt werden soll, ob zwischen zwei Punkten eine hydrologische Verbindung besteht. Bei dieser Fliessrichtungsbestimmung sind die Forderungen an die Eigenschaften der einzusetzenden Tracer geringer als bei der Bestimmung der Geschwindigkeit des unterirdischen Wassers. Von den Geschwindigkeiten des unterirdischen Wassers ist die Abstands-(Fliess)geschwindigkeit, die definiert ist durch das Verhaeltnis aus dem Abstand und der wahren Fliesszeit zwischen zwei in Bewegungsrichtung gelegenen Punkten, durch Tracermethoden zu bestimmen. (orig.)

  1. Using radioactive tracer technique in municipal hygiene

    Energy Technology Data Exchange (ETDEWEB)

    Yurasova, O I [Institut Obshchej i Kommunal' noj Gigieny, Moscow (USSR)

    1974-01-01

    Work of the A. N. Syrsin Institute of General and Municiapl Hygiene using raidoactive tracers is reviewed. The studies include research on protein metabolism in the living organism following action of unfavorable factors of the environment; determination of the paths of introduction into the organism of substances with an alien composition; and study of the rate of resorption of subcutaneous papuli. Results are shown of radioactive-tracer studies on the mechanism of action of poisonous substances on the living organism and of migration of alien chemical compounds in the organism and in objects in the environment. It is concluded that the radioactive tracer method has wide application in municipal hygiene and sanitary microbiology. The absence of laborious operations, economy of time, precision of the experiments, and the possibility of obtaining additional information on the mechanism of action of poisonous substances on the organism and the low cost of such studies compared with other methods makes the radioactive tracer method economically attractive. The studies made show the various types of use of the method in municipal hygiene and sanitary microbiology.

  2. Pipeline leak detection using volatile tracers

    International Nuclear Information System (INIS)

    Thompson, G.M.; Golding, R.D.

    1993-01-01

    A method of leak detection for underground storage tanks and pipelines adds volatile tracers to the products in the tanks and analyzes the surrounding shallow soil gases for tracer vapors. This method has several advantages: the success of the test is not limited by the size and structural design of the vessels, tanks can be tested at any fill level without taking the tank out of service, the location of a leak along a pipeline is clearly marked by the location of the tracer, and liquid leaks as small as 0.2 liters per hour (lph) can be detected. A limitation is: the backfill material must have some degree of air permeability in the zone above the water table. Several field tests document the success achieved using this method. A tracer leak detection system was installed at Homestead AFB after several other testing methods failed to locate a leak at a valve pit location along approximately 4 kilometers of fuel transfer piping. The leak was detected to the side of the valve pit at a depth of approximately 2.5 meters below the ground surface. Another installation of Edwards AFB involved the collection of 415 soil gas samples along approximately 3,050 meters of 15.25-centimeter fiberglass pipeline. Fourteen separate leaks were detected

  3. Combining Empirical Relationships with Data Based Mechanistic Modeling to Inform Solute Tracer Investigations across Stream Orders

    Science.gov (United States)

    Herrington, C.; Gonzalez-Pinzon, R.; Covino, T. P.; Mortensen, J.

    2015-12-01

    Solute transport studies in streams and rivers often begin with the introduction of conservative and reactive tracers into the water column. Information on the transport of these substances is then captured within tracer breakthrough curves (BTCs) and used to estimate, for instance, travel times and dissolved nutrient and carbon dynamics. Traditionally, these investigations have been limited to systems with small discharges (turbidity (e.g., nitrate signals with SUNA instruments or fluorescence measures) and/or high total dissolved solids (e.g., making prohibitively expensive the use of salt tracers such as NaCl) in larger systems. Additionally, a successful time-of-travel study is valuable for only a single discharge and river stage. We have developed a method to predict tracer BTCs to inform sampling frequencies at small and large stream orders using empirical relationships developed from multiple tracer injections spanning several orders of magnitude in discharge and reach length. This method was successfully tested in 1st to 8th order systems along the Middle Rio Grande River Basin in New Mexico, USA.

  4. Use of thermodynamic coupling between antibody-antigen binding and phospholipid acyl chain phase transition energetics to predict immunoliposome targeting affinity.

    Science.gov (United States)

    Klegerman, Melvin E; Zou, Yuejiao; Golunski, Eva; Peng, Tao; Huang, Shao-Ling; McPherson, David D

    2014-09-01

    Thermodynamic analysis of ligand-target binding has been a useful tool for dissecting the nature of the binding mechanism and, therefore, potentially can provide valuable information regarding the utility of targeted formulations. Based on a consistent coupling of antibody-antigen binding and gel-liquid crystal transition energetics observed for antibody-phosphatidylethanolamine (Ab-PE) conjugates, we hypothesized that the thermodynamic parameters and the affinity for antigen of the Ab-PE conjugates could be effectively predicted once the corresponding information for the unconjugated antibody is determined. This hypothesis has now been tested in nine different antibody-targeted echogenic liposome (ELIP) preparations, where antibody is conjugated to dipalmitoylphosphatidylethanolamine (DPPE) head groups through a thioether linkage. Predictions were satisfactory (affinity not significantly different from the population of values found) in five cases (55.6%), but the affinity of the unconjugated antibody was not significantly different from the population of values found in six cases (66.7%), indicating that the affinities of the conjugated antibody tended not to deviate appreciably from those of the free antibody. While knowledge of the affinities of free antibodies may be sufficient to judge their suitability as targeting agents, thermodynamic analysis may still provide valuable information regarding their usefulness for specific applications.

  5. A 2.5-dimensional method for the prediction of structure-borne low-frequency noise from concrete rail transit bridges.

    Science.gov (United States)

    Li, Qi; Song, Xiaodong; Wu, Dingjun

    2014-05-01

    Predicting structure-borne noise from bridges subjected to moving trains using the three-dimensional (3D) boundary element method (BEM) is a time consuming process. This paper presents a two-and-a-half dimensional (2.5D) BEM-based procedure for simulating bridge-borne low-frequency noise with higher efficiency, yet no loss of accuracy. The two-dimensional (2D) BEM of a bridge with a constant cross section along the track direction is adopted to calculate the spatial modal acoustic transfer vectors (MATVs) of the bridge using the space-wave number transforms of its 3D modal shapes. The MATVs calculated using the 2.5D method are then validated by those computed using the 3D BEM. The bridge-borne noise is finally obtained through the MATVs and modal coordinate responses of the bridge, considering time-varying vehicle-track-bridge dynamic interaction. The presented procedure is applied to predict the sound pressure radiating from a U-shaped concrete bridge, and the computed results are compared with those obtained from field tests on Shanghai rail transit line 8. The numerical results match well with the measured results in both time and frequency domains at near-field points. Nevertheless, the computed results are smaller than the measured ones for far-field points, mainly due to the sound radiation from adjacent spans neglected in the current model.

  6. Halon-1301, a new Groundwater Age Tracer

    Science.gov (United States)

    Beyer, Monique; van der Raaij, Rob; Morgenstern, Uwe; Jackson, Bethanna

    2015-04-01

    Groundwater dating is an important tool to assess groundwater resources in regards to direction and time scale of groundwater flow and recharge and to assess contamination risks and manage remediation. To infer groundwater age information, a combination of different environmental tracers, such as tritium and SF6, are commonly used. However ambiguous age interpretations are often faced, due to a limited set of available tracers and limitations of each tracer method when applied alone. There is a need for additional, complementary groundwater age tracers. We recently discovered that Halon-1301, a water soluble and entirely anthropogenic gaseous substance, may be a promising candidate [Beyer et al, 2014]. Halon-1301 can be determined along with SF6, SF5CF3 and CFC-12 in groundwater using a gas chromatography setup with attached electron capture detector developed by Busenberg and Plummer [2008]. Halon-1301 has not been assessed in groundwater. This study assesses the behaviour of Halon-1301 in water and its suitability as a groundwater age tracer. We determined Halon-1301 in 17 groundwater and various modern (river) waters sites located in 3 different groundwater systems in the Wellington Region, New Zealand. These waters have been previously dated with tritium, CFC-12, CFC-11 and SF6 with mean residence times ranging from 0.5 to over 100 years. The waters range from oxic to anoxic and some show evidence of CFC contamination or degradation. This allows us to assess the different properties affecting the suitability of Halon-1301 as groundwater age tracer, such as its conservativeness in water and local contamination potential. The samples are analysed for Halon-1301 and SF6simultaneously, which allows identification of issues commonly faced when using gaseous tracers such as contamination with modern air during sampling. Overall we found in the assessed groundwater samples Halon-1301 is a feasible new groundwater tracer. No sample indicated significantly elevated

  7. Methods for conduct of atmospheric tracer studies at ANSTO

    Energy Technology Data Exchange (ETDEWEB)

    Clark, G H; Stone, D J.M.; Pascoe, J H [Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia). Environment Division

    2000-07-01

    A perfluorocarbon atmospheric tracer system has been developed to investigate atmospheric dispersion processes in the region surrounding the Lucas Heights Science and Technology Centre. This report discusses the tracer release, sampling and analysis methods.

  8. Benchmarking of RESRAD-OFFSITE : transition from RESRAD (onsite) to RESRAD-OFFSITE and comparison of the RESRAD-OFFSITE predictions with peercodes

    International Nuclear Information System (INIS)

    Yu, C.; Gnanapragasam, E.; Cheng, J.-J.; Biwer, B.

    2006-01-01

    The main purpose of this report is to document the benchmarking results and verification of the RESRAD-OFFSITE code as part of the quality assurance requirements of the RESRAD development program. This documentation will enable the U.S. Department of Energy (DOE) and its contractors, and the U.S. Nuclear Regulatory Commission (NRC) and its licensees and other stakeholders to use the quality-assured version of the code to perform dose analysis in a risk-informed and technically defensible manner to demonstrate compliance with the NRC's License Termination Rule, Title 10, Part 20, Subpart E, of the Code of Federal Regulations (10 CFR Part 20, Subpart E); DOE's 10 CFR Part 834, Order 5400.5, ''Radiation Protection of the Public and the Environment''; and other Federal and State regulatory requirements as appropriate. The other purpose of this report is to document the differences and similarities between the RESRAD (onsite) and RESRAD-OFFSITE codes so that users (dose analysts and risk assessors) can make a smooth transition from use of the RESRAD (onsite) code to use of the RESRAD-OFFSITE code for performing both onsite and offsite dose analyses. The evolution of the RESRAD-OFFSITE code from the RESRAD (onsite) code is described in Chapter 1 to help the dose analyst and risk assessor make a smooth conceptual transition from the use of one code to that of the other. Chapter 2 provides a comparison of the predictions of RESRAD (onsite) and RESRAD-OFFSITE for an onsite exposure scenario. Chapter 3 documents the results of benchmarking RESRAD-OFFSITE's atmospheric transport and dispersion submodel against the U.S. Environmental Protection Agency's (EPA's) CAP88-PC (Clean Air Act Assessment Package-1988) and ISCLT3 (Industrial Source Complex-Long Term) models. Chapter 4 documents the comparison results of the predictions of the RESRAD-OFFSITE code and its submodels with the predictions of peer models. This report was prepared by Argonne National Laboratory's (Argonne

  9. Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

    International Nuclear Information System (INIS)

    Woodman, N.D.; Rees-White, T.C.; Stringfellow, A.M.; Beaven, R.P.; Hudson, A.P.

    2015-01-01

    Highlights: • Multiple tracers were applied to saturated MSW to test dual-porosity properties. • Lithium demonstrated to be non-conservative as a tracer. • 260 mm diameter column too small to test transport properties of MSW. • The classical advection-dispersion mode was rejected due to high dispersivity. • Characteristic diffusion times did not vary with the tracer. - Abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD–DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study

  10. Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

    Energy Technology Data Exchange (ETDEWEB)

    Woodman, N.D., E-mail: n.d.woodman@soton.ac.uk; Rees-White, T.C.; Stringfellow, A.M.; Beaven, R.P.; Hudson, A.P.

    2015-04-15

    Highlights: • Multiple tracers were applied to saturated MSW to test dual-porosity properties. • Lithium demonstrated to be non-conservative as a tracer. • 260 mm diameter column too small to test transport properties of MSW. • The classical advection-dispersion mode was rejected due to high dispersivity. • Characteristic diffusion times did not vary with the tracer. - Abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD–DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study.

  11. Laplace transform in tracer kinetic modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Eliete B., E-mail: eliete@pucrs.br [Instituto do Cerebro (InsCer/FAMAT/PUC-RS), Porto Alegre, RS, (Brazil). Faculdade de Matematica

    2013-07-01

    The main objective this paper is to quantify the pharmacokinetic processes: absorption, distribution and elimination of radiopharmaceutical(tracer), using Laplace transform method. When the drug is administered intravenously absorption is complete and is available in the bloodstream to be distributed throughout the whole body in all tissues and fluids, and to be eliminated. Mathematical modeling seeks to describe the processes of distribution and elimination through compartments, where distinct pools of tracer (spatial location or chemical state) are assigned to different compartments. A compartment model is described by a system of differential equations, where each equation represents the sum of all the transfer rates to and from a specific compartment. In this work a two-tissue irreversible compartment model is used for description of tracer, [{sup 18}F]2-fluor-2deoxy-D-glucose. In order to determine the parameters of the model, it is necessary to have information about the tracer delivery in the form of an input function representing the time-course of tracer concentration in arterial blood or plasma. We estimate the arterial input function in two stages and apply the Levenberg-Marquardt Method to solve nonlinear regressions. The transport of FDG across de arterial blood is very fast in the first ten minutes and then decreases slowly. We use de Heaviside function to represent this situation and this is the main contribution of this study. We apply the Laplace transform and the analytical solution for two-tissue irreversible compartment model is obtained. The only approach is to determinate de arterial input function. (author)

  12. Guidebook on radioisotope tracers in industry

    International Nuclear Information System (INIS)

    1990-01-01

    The idea of using tracers (chemical, dyes, etc.) in the investigation of complex physical phenomena has always attracted the attention of scientists and engineers. When radioactive isotopes became available it was immediately recognized that they offered an almost ideal solution to tracer selection. This book is devoted to reviewing the present status of the tracer method as such and to its applications to those branches of industry which have derived large benefits from the use of this modern technology. The main objectives of the IAEA's Industrial Applications and Chemistry Section is to help Member States in introducing to their own industries the different isotope and radiation techniques which have become available as a result of developments in the nuclear sciences. This section proposed the preparation of this guidebook, putting together various radiotracer methods and the experience obtained so far in their industrial use. Chapters 2 to 4 cover the general concept of tracers, technology and safety aspects, as well as data evaluation and interpretation. In chapter 5, therefore, general applications are discussed. In chapter 6, specialists in selected fields discuss their experience in radiotracer applications in various types of industrial activity. Most case studies are illustrated by at least one detailed example of an experiment carried out at an industrial installation. Current trends in the development of radiotracer methods are discussed in chapter 7, from both a theoretical and a practical viewpoint. Some possible new RTT applications in the future are also discussed here. Sealed radioactive sources are used almost as often as radioisotope tracers in industrial measurements. Annex I gives a short review of these techniques. Readers who are interested in the basic principles of radioisotope production will find the necessary information in Annex II. Annexes III, V and VI provide a demonstration of fundamental relations and properties; useful

  13. Can radiocaesium be used as a tracer for vegetal nutrients?

    International Nuclear Information System (INIS)

    Anjos, R. M.; Mosquera, B.; Carvalho, C.; Sanches, N.; Bastos, J.; Macario, K.; Vezzone, M.; Gomes, P.R.S.

    2007-01-01

    In recent years, there has been a growing interest in the evaluation of nutrient fluxes and radioactive contaminants in forest and agricultural ecosystems. Several studies on forest ecosystems have been carried out, mostly in Europe, after the Chernobyl accident. These studies have been performed mainly in the development of models for predicting the radiocaesium behavior in the soil and plant compartments of forest systems. However, research on the use of radiocaesium as a tracer for vegetal nutrients has shown that, despite the fact that caesium is a weakly hydrated alkaline metal and has chemical similarities to potassium and ammonium, this is still a complex problem requiring, then, more experimental results. Additionally, very little is known about the mechanisms involved in the radionuclide uptake and retention by tropical plants. In order to contribute to the understanding of the relative behavior of caesium, potassium and ammonium and to investigate whether radiocaesium can be used as a tracer for vegetal nutrients, the Laboratory of Radioecology (LARA) of the Federal Fluminense University has been performing analysis of 137 Cs, 40 K and NH 4 concentrations in several vegetal compartments of agricultural tropical plants, such as guava (Psidium guajava), mango (Mangifera indica), avocado (Persea americana), pomegranate (Punica granatum), papaya (Carica Papaya), banana (Musa paradisiaca), manioc (Manihot Esculenta), and chili pepper (Capsicum fructescens) trees. Measurements of 137 Cs, 40 K and NH 4 concentrations show that these elements can be very mobile within a plant, exhibiting the highest values of concentration in the growing parts of the trees: fruits, leaves, twigs, barks and the outer growth layers. On the other hand, our results indicate that for wood trees (such as guava, mango, avocado, pomegranate and chili pepper trees) do both caesium and the vegetal nutrients have simultaneously higher concentrations in the youngest rather than in the oldest

  14. Water Vapor Tracers as Diagnostics of the Regional Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Numerous studies suggest that local feedback of surface evaporation on precipitation, or recycling, is a significant source of water for precipitation. Quantitative results on the exact amount of recycling have been difficult to obtain in view of the inherent limitations of diagnostic recycling calculations. The current study describes a calculation of the amount of local and remote geographic sources of surface evaporation for precipitation, based on the implementation of three-dimensional constituent tracers of regional water vapor sources (termed water vapor tracers, WVT) in a general circulation model. The major limitation on the accuracy of the recycling estimates is the veracity of the numerically simulated hydrological cycle, though we note that this approach can also be implemented within the context of a data assimilation system. In the WVT approach, each tracer is associated with an evaporative source region for a prognostic three-dimensional variable that represents a partial amount of the total atmospheric water vapor. The physical processes that act on a WVT are determined in proportion to those that act on the model's prognostic water vapor. In this way, the local and remote sources of water for precipitation can be predicted within the model simulation, and can be validated against the model's prognostic water vapor. As a demonstration of the method, the regional hydrologic cycles for North America and India are evaluated for six summers (June, July and August) of model simulation. More than 50% of the precipitation in the Midwestern United States came from continental regional sources, and the local source was the largest of the regional tracers (14%). The Gulf of Mexico and Atlantic regions contributed 18% of the water for Midwestern precipitation, but further analysis suggests that the greater region of the Tropical Atlantic Ocean may also contribute significantly. In most North American continental regions, the local source of precipitation is

  15. Atlantic Coast Unique Regional Atmospheric Tracer Experiment (ACURATE)

    International Nuclear Information System (INIS)

    Schubert, J.F.; Heffter, J.L.; Mead, G.A.

    1983-05-01

    The Atlantic Coast Unique Regional Atmospheric Tracer Experiment (ACURATE) is a program designed to obtain data necessary to evaluate atmospheric transport and diffusion models used to calculate regional population doses caused by nuclear facility emissions to the atmosphere. This experiment will significantly improve the basis for evaluating the cost effectiveness of different methods of managing airborne nuclear wastes. During the period from March 1982 through September 1982, twice daily air samples have been collected at each of five sampling stations located on a radial from the SRP to Murray Hill, NJ (1000 km). Kr-85 emitted from the F and H area chemical separations facilities is being used as a tracer to determine the transport and diffusion of atmospheric releases from the SRP. The Kr-85 concentrations in the air samples will be compared with the calculated concentrations as predicted by the transport and diffusion models. The Kr-85 data and the meteorological data are being archived and will be made available to the modeling community

  16. Optimization of Iron Oxide Tracer Synthesis for Magnetic Particle Imaging

    Directory of Open Access Journals (Sweden)

    Sabina Ziemian

    2018-03-01

    Full Text Available The optimization of iron oxide nanoparticles as tracers for magnetic particle imaging (MPI alongside the development of data acquisition equipment and image reconstruction techniques is crucial for the required improvements in image resolution and sensitivity of MPI scanners. We present a large-scale water-based synthesis of multicore superparamagnetic iron oxide nanoparticles stabilized with dextran (MC-SPIONs. We also demonstrate the preparation of single core superparamagnetic iron oxide nanoparticles in organic media, subsequently coated with a poly(ethylene glycol gallic acid polymer and phase transferred to water (SC-SPIONs. Our aim was to obtain long-term stable particles in aqueous media with high MPI performance. We found that the amplitude of the third harmonic measured by magnetic particle spectroscopy (MPS at 10 mT is 2.3- and 5.8-fold higher than Resovist for the MC-SPIONs and SC-SPIONs, respectively, revealing excellent MPI potential as compared to other reported MPI tracer particle preparations. We show that the reconstructed MPI images of phantoms using optimized multicore and specifically single-core particles are superior to that of commercially available Resovist, which we utilize as a reference standard, as predicted by MPS.

  17. Evaluation of modelling of the TRUE-1 radially converging tests with sorbing tracers. The Aespoe task force on modelling of groundwater flow and transport of solutes. Tasks 4E and 4F

    Energy Technology Data Exchange (ETDEWEB)

    Elert, M.; Svensson, Haakan [Kemakta Konsult AB, Stockholm (Sweden)

    2001-05-01

    The Aespoe Task Force on Modelling of Groundwater Flow and Transport of Solutes is a forum for the international organisations supporting the Aespoe HRL Project. The purpose of the Task Force is to interact in the area of conceptual and numerical modelling of groundwater flow and solute transport in fractured rock. Task 4 of the Aespoe Modelling Task Force consists of modelling exercises in support of the TRUE-1 tracer tests. In this report, the modelling work performed within Tasks 4E and 4F is evaluated, which comprised predictive modelling of the tracer tests (STT-1, STT-1b and STT-2) performed within the TRUE-1 project using sorbing and non-sorbing tracers. The tests were made between packed off boreholes penetrating a water-conducting geological feature with a simple structure (Feature A). Nine modelling teams representing eight organisations have performed predictive modelling of the tracer tests using different modelling approaches and models. The modelling groups were initially given data from the site characterisation, data from preliminary tracer tests performed with non-sorbing tracers and data on the experimental set-up of the sorbing tracer tests. Based on this information, model predictions were made of drawdown, tracer mass recovery and tracer breakthrough. For the predictions of the STT-1b and STT-2 tests results from previous tracer tests with sorbing tracer were also available. The predictions of the sorbing tracer breakthrough in the initial tracer test (STT-1) generally underestimated the breakthrough time, suggesting the need to include additional processes and evaluate the application of the laboratory data. As a result of model calibration and modification the predictions were considerably improved for the latter tracer tests (STT-1b and STT-2). Task 4E and 4F have proved to be very valuable in increasing the understanding of non-sorbing tracer transport in fractured rock. There is a general consensus on the major processes responsible for

  18. New radioactive tracers can help find cause of jaundice

    International Nuclear Information System (INIS)

    Carrard, G.

    1987-01-01

    Radioactive tracers for the investigation of a condition known as persistent jaundice of the newborn, have been designed, prepared and tested at ANSTO. The tracers are chemical compounds of the radioactive elements gallium-67 and indium-111. They given lower radiation doses than the conventional radioactive tracer, iodine-131, used in these studies

  19. PET tracers for somatostatin receptor imaging of neuroendocrine tumors

    DEFF Research Database (Denmark)

    Johnbeck, Camilla Bardram; Knigge, Ulrich; Kjær, Andreas

    2014-01-01

    Neuroendocrine tumors have shown rising incidence mainly due to higher clinical awareness and better diagnostic tools over the last 30 years. Functional imaging of neuroendocrine tumors with PET tracers is an evolving field that is continuously refining the affinity of new tracers in the search...... these PET tracers further....

  20. Industrial tracer application in people's republic of china

    International Nuclear Information System (INIS)

    Sun Maoyi

    1987-01-01

    A number of important applications of radioisotopes and their compounds used as tracers in petroleum industry, metallurgical industry, mechanical industry, chemical industry, electronic industry, hydrology and water conservancy in China are introduced in this paper. And the tracer technique applied to entomology is also mentioned. The industrial tracer applications are successful and beneficial in People's Republic of China from the examples given. (author)

  1. Natural tracer profiles across argillaceous formations

    International Nuclear Information System (INIS)

    Mazurek, Martin; Alt-Epping, Peter; Bath, Adrian; Gimmi, Thomas; Niklaus Waber, H.; Buschaert, Stephane; Canniere, Pierre De; Craen, Mieke De; Gautschi, Andreas; Savoye, Sebastien; Vinsot, Agnes; Wemaere, Isabelle; Wouters, Laurent

    2011-01-01

    Highlights: → Solute transport processes in clay and shale formations at nine sites are examined. → Conservative pore-water tracers (e.g. Cl - , δ 18 O, δ 2 H, He) show regular profiles. → These indicate the dominance of diffusive transport over times of 10 5 -10 6 years. → The contribution of vertical advection to transport is limited or negligible. → Modelled evolution times are in line with independent palaeo-hydrogeological data. - Abstract: Argillaceous formations generally act as aquitards because of their low hydraulic conductivities. This property, together with the large retention capacity of clays for cationic contaminants, has brought argillaceous formations into focus as potential host rocks for the geological disposal of radioactive and other waste. In several countries, programmes are under way to characterise the detailed transport properties of such formations at depth. In this context, the interpretation of profiles of natural tracers in pore waters across the formations can give valuable information about the large-scale and long-term transport behaviour of these formations. Here, tracer-profile data, obtained by various methods of pore-water extraction for nine sites in central Europe, are compiled. Data at each site comprise some or all of the conservative tracers: anions (Cl - , Br - ), water isotopes (δ 18 O, δ 2 H) and noble gases (mainly He). Based on a careful evaluation of the palaeo-hydrogeological evolution at each site, model scenarios are derived for initial and boundary pore-water compositions and an attempt is made to numerically reproduce the observed tracer distributions in a consistent way for all tracers and sites, using transport parameters derived from laboratory or in situ tests. The comprehensive results from this project have been reported in . Here the results for three sites are presented in detail, but the conclusions are based on model interpretations of the entire data set. In essentially all cases, the

  2. Projected Applications of a ``Climate in a Box'' Computing System at the NASA Short-term Prediction Research and Transition (SPoRT) Center

    Science.gov (United States)

    Jedlovec, G.; Molthan, A.; Zavodsky, B.; Case, J.; Lafontaine, F.

    2010-12-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center focuses on the transition of unique observations and research capabilities to the operational weather community, with a goal of improving short-term forecasts on a regional scale. Advances in research computing have lead to “Climate in a Box” systems, with hardware configurations capable of producing high resolution, near real-time weather forecasts, but with footprints, power, and cooling requirements that are comparable to desktop systems. The SPoRT Center has developed several capabilities for incorporating unique NASA research capabilities and observations with real-time weather forecasts. Planned utilization includes the development of a fully-cycled data assimilation system used to drive 36-48 hour forecasts produced by the NASA Unified version of the Weather Research and Forecasting (WRF) model (NU-WRF). The horsepower provided by the “Climate in a Box” system is expected to facilitate the assimilation of vertical profiles of temperature and moisture provided by the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua satellite. In addition, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA’s Aqua and Terra satellites provide high-resolution sea surface temperatures and vegetation characteristics. The development of MODIS normalized difference vegetation index (NVDI) composites for use within the NASA Land Information System (LIS) will assist in the characterization of vegetation, and subsequently the surface albedo and processes related to soil moisture. Through application of satellite simulators, NASA satellite instruments can be used to examine forecast model errors in cloud cover and other characteristics. Through the aforementioned application of the “Climate in a Box” system and NU-WRF capabilities, an end goal is the establishment of a real-time forecast system that fully integrates modeling and analysis capabilities developed

  3. Projected Applications of a "Climate in a Box" Computing System at the NASA Short-Term Prediction Research and Transition (SPoRT) Center

    Science.gov (United States)

    Jedlovec, Gary J.; Molthan, Andrew L.; Zavodsky, Bradley; Case, Jonathan L.; LaFontaine, Frank J.

    2010-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center focuses on the transition of unique observations and research capabilities to the operational weather community, with a goal of improving short-term forecasts on a regional scale. Advances in research computing have lead to "Climate in a Box" systems, with hardware configurations capable of producing high resolution, near real-time weather forecasts, but with footprints, power, and cooling requirements that are comparable to desktop systems. The SPoRT Center has developed several capabilities for incorporating unique NASA research capabilities and observations with real-time weather forecasts. Planned utilization includes the development of a fully-cycled data assimilation system used to drive 36-48 hour forecasts produced by the NASA Unified version of the Weather Research and Forecasting (WRF) model (NU-WRF). The horsepower provided by the "Climate in a Box" system is expected to facilitate the assimilation of vertical profiles of temperature and moisture provided by the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua satellite. In addition, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA s Aqua and Terra satellites provide high-resolution sea surface temperatures and vegetation characteristics. The development of MODIS normalized difference vegetation index (NVDI) composites for use within the NASA Land Information System (LIS) will assist in the characterization of vegetation, and subsequently the surface albedo and processes related to soil moisture. Through application of satellite simulators, NASA satellite instruments can be used to examine forecast model errors in cloud cover and other characteristics. Through the aforementioned application of the "Climate in a Box" system and NU-WRF capabilities, an end goal is the establishment of a real-time forecast system that fully integrates modeling and analysis capabilities developed within the NASA SPo

  4. Two-well recirculation tracer tests at the H-2 hydropad, Waste Isolation Pilot Plant (WIPP), southeastern New Mexico

    International Nuclear Information System (INIS)

    1986-10-01

    Two recirculation tracer tests were performed on the Culebra Dolomite Member of the Rustler Formation at the H-2 hydropad at the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. The first test, which used pentafluorobenzoate (PFB), sodium benzoate, and a suite of halocarbons for tracers, was terminated before breakthrough at the pumping well because of equipment failure. The second test, which used sodium thiocyanate (SCN) and difluorochlorobromomethane (BCF) as tracers, proceeded normally and lasted 270 days. During the second test, the tracer injected during the first test was recovered. Tracer test analyses for the two tests were performed only for the PFB tracer injected during the first test and recovered during the second, and for SCN. Analysis of the PFB recovery was crudely modeled as a one-dimensional pulse-injection test. The SCN tracer used in the second test was analyzed with the homogeneous, isotropic Grove and Beetem one-dimensional porous-medium recirculating flow test model. In general, model predictions are in poor agreement with the field measurements. Discrepancies could be produced by the combined effects of local nonhomogeneities, matrix diffusion, and possible sorption or degradation of the tracer during the test. The best overall match between the SCN breakthrough curve predicted by the semianalytical model and that observed in measurements was achieved using a porosity that ranged from 17% to 19% and a dispersivity of 16 to 18 ft. A match based only on the early part of the breakthrough curve, however, yielded a porosity of 11.5% and a dispersivity of 8 ft. The latter porosity might more closely represent the effective porosity of the Culebra, if the SCN degraded during the test

  5. Prediction of non-brittle fracture in the welded joint of C-Mn steel in the brittle-ductile transition domain; Prediction de la non-rupture fragile dans un joint soude en acier C-Mn dans le domaine de la transition fragile/ductile

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thai Ha

    2009-11-15

    This work concerns the nuclear safety, specifically the secondary circuit integrity of pressurized water reactors (PWR). The problem is that of the fracture of a thin tubular structure in ferritic steel with many welded joints. The ferritic steel and weld present a brittle/ductile tenacity transition. Moreover, the welds present geometry propitious to the appearance of fatigue cracks, due to vibrations and expansions. These cracks may cause the complete fracture of the structure. The objectives of this work are to establish a criterion of non-fracture by cleavage of thin welded structures in ferritic steel, applicable to actual structures. Therefore, the present study focuses on the fracture behaviour of welded thin structures in brittle/ductile transition. It aims at developing the threshold stress model initially proposed by Chapuliot, to predict the non-brittle-fracture of this welded structure. The model is identified for the welded joint in C-Mn steel for nuclear construction, specifically in the upper part of the transition. A threshold stress, below which the cleavage cannot take place, is identified using tensile tests at low temperature on axis-symmetrical notched specimens taken in welded joint. This threshold stress is used to define the threshold volume where the maximum principal stress exceeds the threshold stress during the test. The analysis by SEM of specimen fracture surfaces shows that the gross solidification molten zone in the weld is the most likely to cleave. The relation between the brittle fracture probability and the threshold volume in the gross solidification molten zone is established via a sensitivity function, using multi-materials simulations. The model thus identified is tested for the prediction of non-brittle-fracture of SENT specimens taken in the welded joint and tested in tension. The results obtained are encouraging with regards to the transferability of the model to the actual structure. (author)

  6. Direct inversion of circulation and mixing from tracer measurements – Part 1: Method

    Directory of Open Access Journals (Sweden)

    T. von Clarmann

    2016-11-01

    Full Text Available From a series of zonal mean global stratospheric tracer measurements sampled in altitude vs. latitude, circulation and mixing patterns are inferred by the inverse solution of the continuity equation. As a first step, the continuity equation is written as a tendency equation, which is numerically integrated over time to predict a later atmospheric state, i.e., mixing ratio and air density. The integration is formally performed by the multiplication of the initially measured atmospheric state vector by a linear prediction operator. Further, the derivative of the predicted atmospheric state with respect to the wind vector components and mixing coefficients is used to find the most likely wind vector components and mixing coefficients which minimize the residual between the predicted atmospheric state and the later measurement of the atmospheric state. Unless multiple tracers are used, this inversion problem is under-determined, and dispersive behavior of the prediction further destabilizes the inversion. Both these problems are addressed by regularization. For this purpose, a first-order smoothness constraint has been chosen. The usefulness of this method is demonstrated by application to various tracer measurements recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. This method aims at a diagnosis of the Brewer–Dobson circulation without involving the concept of the mean age of stratospheric air, and related problems like the stratospheric tape recorder, or intrusions of mesospheric air into the stratosphere.

  7. Evaluation of TRUE-1 tests with sorbing tracers using CHAN3D

    International Nuclear Information System (INIS)

    Moreno, L.

    2001-01-01

    Three tracer tests (STT1a, STT1b and STT2) with sorbing species performed as a part of the TRUE-1 experiments are studied. The tests were carried out in a radially converging flow geometry with a travel distance of about 5 m The injected sorbing tracers were: Na + , Sr 2+ , Ca 2+ , Ba 2+ , Cs + , Co 2+ , Rb + . The sorption properties of the tracer cover a wide interval. The tracer tests were modelled using the Channel Network Model, which assumes that fluid flow and solute transport take place through a network of channels. It includes solute transport by advection, diffusion into the rock matrix, and sorption within the matrix and onto the channel surface. Sorption and diffusion data were obtained from laboratory measurements carried out over generic Aespoe material. Some measurements were made using material from the Feature A. Large differences are found between the experimental and the predicted breakthrough curves. The predicted times are much shorter than the experimental ones. An attempt is made to explain these differences using various possible retardation mechanisms. Finally, it is concluded that several mechanisms must act simultaneously in order to explain the large differences

  8. 15N tracer techniques in pediatric research

    International Nuclear Information System (INIS)

    Heine, W.; Richter, I.; Plath, C.; Wutzke, K.; Stolpe, H.J.; Tiess, M.; Toewe, J.

    1983-01-01

    The main topics of the review comprise mathematical fundamentals of the determination of N metabolism parameters using the 3-pool method, the value of different 15 N tracer substances for the determination of whole-body protein parameters, the utilization of parenterally applied D-amino acids, studies on the influence of different diets on the N metabolism of premature infants with the 15 N tracer technique, the application of the 15 N-glycine-STH-test for the evaluation of the therapeutic effect of STH in children suffering from hypothalamico-hypophyseal dwarfism, in vivo studies on urea utilization by the infant intestinal flora under various dietary regimens as well as in vitro investigations on the utilization of 15 N-labelled urea and NH 4 Cl, resp., by the intestinal flora

  9. Radioactive tracers and the cracking modelings

    International Nuclear Information System (INIS)

    Bettens, B.

    1982-01-01

    The use of tracers (3H and 14 C) labelled in specific positions is an intensive contribution to the understanding and the revealing of the very often complex cracking modeling. The pyrolytic decay of the phenol and the cresols, of the aniline, of the phenantrene and its hydrogenated derived products were investigated and are presented as examples. The decay mechanisms give a theoretical knowledge of the thermal cracking and allow to handle the results on an industrial scale. (AF)

  10. The medical applications of radioactive tracers

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, J.G.

    1947-12-31

    This report provides a broad yet in depth overview of the use of radioactive materials as tracers in medicine and biology for the period of 1935--1947. Particular attention is paid to is of radio-sodium, radio-iodine, radio-iron, radio-phosphorus, radio-strontium, and fission products. The main thrust of this paper is human rather than animal work and focuses in work that has been published.

  11. For patients with primary achalasia the clinical success of pneumatic balloon dilatation can be predicted from the residual fraction of radionuclide during esophageal transit scintigraphy.

    Science.gov (United States)

    Jeon, Han Ho; Youn, Young Hoon; Rhee, Kwangwon; Kim, Jie-Hyun; Park, Hyojin; Conklin, Jeffrey L

    2014-02-01

    Esophageal transit scintigraphy (ETS) and esophagography have long been used to evaluate patients with achalasia. The objectives of our study were to evaluate the efficacy of endoscopic pneumatic dilatation (EPD) as treatment for Koreans with achalasia and to determine which findings from ETS and esophagography predict successful treatment of achalasia. Patients with achalasia who were treated by EPD between April 2002 and January 2012 were recruited. We defined the success of EPD as 6 months or more of clinical remission without symptoms or a decrease in the Eckardt scores by at least two points and a total Eckardt score not exceeding 3. We reviewed the percentage of maximum scintigraphic activity retained in the esophagus at 30 s (R 30) and the post-PD rate of reduction of R 30 ((Pre R 30 - Post R 30)/Pre R 30 × 100) by ETS. Possible predictive factors determined by ETS and esophagography were analyzed. Our study included 53 eligible patients. The median symptom score (Eckardt score) was 5 (4-8). R 30 and T 1/2 were, respectively, 61.8 % and 38.5 min before EPD and 20 % and 4.19 min after EPD. Successful EPD was achieved for 40 of 53 (75.47 %) patients. Age (≥40, p = 0.027) and post-PD rate of reduction of R 30 (>20 %, p = 0.003) were best prognostic indicators of clinical success. There were no perforations related to EPD. Older age and a post-PD rate of reduction of R 30 were strongly associated with better outcomes. Examination with ETS before and after EPD can be used to objectively assess a patient's short-term response to EPD.

  12. Tracer technology modeling the flow of fluids

    CERN Document Server

    Levenspiel, Octave

    2012-01-01

    A vessel’s behavior as a heat exchanger, absorber, reactor, or other process unit is dependent upon how fluid flows through the vessel.  In early engineering, the designer would assume either plug flow or mixed flow of the fluid through the vessel.  However, these assumptions were oftentimes inaccurate, sometimes being off by a volume factor of 100 or more.  The result of this unreliable figure produced ineffective products in multiple reaction systems.   Written by a pioneering researcher in the field of chemical engineering, the tracer method was introduced to provide more accurate flow data.  First, the tracer method measured the actual flow of fluid through a vessel.  Second, it developed a suitable model to represent the flow in question.  Such models are used to follow the flow of fluid in chemical reactors and other process units, like in rivers and streams, or solid and porous structures.  In medicine, the tracer method is used to study the flow of chemicals—harmful  and harmless—in the...

  13. Radon diagnostics and tracer gas measurements

    International Nuclear Information System (INIS)

    Jilek, K.; Brabec, M.

    2004-01-01

    An outline is presented of the tracer gas technique, which is used for continuous measurements of air ventilation rate (generally time-varying) and for simultaneous estimation of air ventilation rate and radon entry rate, and some of its limitations are discussed. The performance of this technique in the calculation of the air ventilation rate is demonstrated on real data from routine measurements. The potential for air ventilation rate estimation based on radon measurements only is discussed. A practical application is described of the tracer gas technique to a simultaneous estimation of the air ventilation rate and radon entry rate in a real house where the effectiveness of radon remedy was tested. The following main advantages of the CO tracer gas techniques are stressed: (i) The averaging method continuous determination of the ventilation rate with good accuracy (≤ 20 %). (ii) The newly presented and verified method based on simultaneous measurements of radon concentration and CO gas concentration enables separate continuous measurements of the radon entry rate and ventilation rate. The results of comparative measurements performed with the aim to estimate the inaccuracy in determination of radon entry rate showed acceptable and good agreement up to approximately 10 %. The results of comparative measurements performed with the aim to estimate the mutual commensuration of the method to the determination of the ventilation rate confirmed the expected unreliability the two parametric non-linear regression method, which is the most frequently used method in radon diagnostic in the Czech Republic

  14. The ATLAS DDM Tracer monitoring framework

    International Nuclear Information System (INIS)

    Zang Dongsong; Garonne, Vincent; Barisits, Martin; Lassnig, Mario; Andrew Stewart, Graeme; Molfetas, Angelos; Beermann, Thomas

    2012-01-01

    The DDM Tracer monitoring framework is aimed to trace and monitor the ATLAS file operations on the Worldwide LHC Computing Grid. The volume of traces has increased significantly since the framework was put in production in 2009. Now there are about 5 million trace messages every day and peaks can be near 250Hz, with peak rates continuing to climb, which gives the current structure a big challenge. Analysis of large datasets based on on-demand queries to the relational database management system (RDBMS), i.e. Oracle, can be problematic, and have a significant effect on the database's performance. Consequently, We have investigated some new high availability technologies like messaging infrastructure, specifically ActiveMQ, and key-value stores. The advantages of key value store technology are that they are distributed and have high scalability; also their write performances are usually much better than RDBMS, all of which are very useful for the Tracer monitoring framework. Indexes and distributed counters have been also tested to improve query performance and provided almost real time results. In this paper, the design principles, architecture and main characteristics of Tracer monitoring framework will be described and examples of its usage will be presented.

  15. Novel tracer for radiation treatment planning

    International Nuclear Information System (INIS)

    Schwarzenboeck, S.; Krause, B.J.; Herrmann, K.; Gaertner, F.; Souvatzoglou, M.; Klaesner, B.

    2011-01-01

    PET and PET/CT with innovative tracers gain increasing importance in diagnosis and therapy management, and radiation treatment planning in radio-oncology besides the widely established FDG. The introduction of [ 18 F]Fluorothymidine ([ 18 F]FLT) as marker of proliferation, [ 18 F]Fluoromisonidazole ([ 18 F]FMISO) and [ 18 F]Fluoroazomycin-Arabinoside ([ 18 F]FAZA) as tracer of hypoxia, [ 18 F]Fluoroethyltyrosine ([ 18 F]FET) and [ 11 C]Methionine for brain tumour imaging, [ 68 Ga]DOTATOC for somatostatin receptor imaging, [ 18 F]FDOPA for dopamine synthesis and radioactively labeled choline derivatives for imaging phospholipid metabolism have opened novel approaches to tumour imaging. Some of these tracers have already been implemented into radio-oncology: Amino acid PET and PET/CT have the potential to optimise radiation treatment planning of brain tumours through accurate delineation of tumour tissue from normal tissue, necrosis and edema. Hypoxia represents a major therapeutic problem in radiation therapy. Hypoxia imaging is very attractive as it may allow to increase the dose in hypoxic tumours potentially allowing for a better tumour control. Advances in hybrid imaging, i.e. the introduction of MR/PET, may also have an impact in radio-oncology through synergies related to the combination of molecular signals of PET and a high soft tissue contrast of MRI as well as functional MRI capabilities. (orig.)

  16. Commercial applications of perfluorocarbon tracer (PFT) technology

    International Nuclear Information System (INIS)

    Dietz, R.N.

    1991-06-01

    Tracer technology can be successfully applied to many leak-checking and monitoring evaluations of operating systems (e.g., building HVACs), manufacturing processes and products (e.g., air conditioners), and subsurface components and systems (e.g., underground storage tanks). Perfluorocarbon tracer (PFT) technology is the most sensitive of all tracer technologies because the ambient background levels of the five (5) routinely-used PFTs are in the range of parts per 10 15 parts of air (i.e., parts per quadrillion-ppq) and this technology's instrumentation can measure down to those levels. The effectiveness of this technology is achieved both in terms of cost (very little PFT need to be used) and detectability; for example, very small leaks can be rapidly detected. The PFT compounds, which are environmentally and biologically safe to use, are commercially available as are the sampling and analysis instrumentation. This presentation concerns (1) the steps being taken to commercialize this technology, (2) new applications of processes currently under study, and (3) applications in areas of use that will be particularly beneficial to the environment. 21 refs., 2 figs., 2 tabs

  17. Automatic monitoring of radial injection tracer tests using a novel multi-electrode resistivity system

    International Nuclear Information System (INIS)

    Ward, R.S.; Sen, M.A.; Williams, G.M.; Jackson, P.D.

    1990-01-01

    A radial injection tracer test has been carried out in an unconfined fluvial sand and gravel aquifer underlain by low permeability clay. Sodium chloride has been used as an electrolyte tracer and breakthrough has been monitored using a newly developed automatic resistivity system (RESCAN) incorporating six fully penetrating resistivity probes each having 80 electrodes spaced at 5 cm intervals along their length. Each electrode is individually addressable under computer control to either carry current or measure potential. Any four electrodes can be selected in the traditional Wenner configuration to measure formation resistivity. Rapid measurement of changes in resistivity allows a very detailed picture of tracer migration to be obtained. The resistivity probes were placed at 1 and 2 m radii from the central fully-screened tracer injection well along three limbs at 120 degrees. Resistivity measurements were compared with adjacent multi-level samplers. An 8 x 8 m grid of 140 surface electrodes centred on the central well was also installed. The resistivity profiles measured prior to tracer injection were used to infer lithology, particularly layering. Detailed breakthrough curves were obtained at 77 positions along each of the six probes and compared with adjacent multi-level sampler breakthrough curves. The results showed that the aquifer was extremely heterogeneous even on this small scale. Because the system operates automatically without the need to extract and analyse large numbers of water samples, it opens up the possibility of carrying out lots of small scale injection tests within a larger domain likely to be invaded by a tracer or pollution plume. Such detailed information for determining aquifer properties can provide the data set necessary for characterisation of the aquifer to predict dispersion parameters appropriate to the large scale. (Author) (6 refs., 9 figs., 2 tabs.)

  18. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    Energy Technology Data Exchange (ETDEWEB)

    B.M. Freifeild

    2001-10-18

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  19. Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

    Energy Technology Data Exchange (ETDEWEB)

    Freifeld, Barry Mark [Univ. of California, Berkeley, CA (United States)

    2001-12-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  20. Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

    International Nuclear Information System (INIS)

    B.M. Freifeild

    2001-01-01

    Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

  1. Representation of tropical deep convection in atmospheric models – Part 2: Tracer transport

    Directory of Open Access Journals (Sweden)

    C. R. Hoyle

    2011-08-01

    Full Text Available The tropical transport processes of 14 different models or model versions were compared, within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere project. The tested models range from the regional to the global scale, and include numerical weather prediction (NWP, chemical transport, and chemistry-climate models. Idealised tracers were used in order to prevent the model's chemistry schemes from influencing the results substantially, so that the effects of modelled transport could be isolated. We find large differences in the vertical transport of very short-lived tracers (with a lifetime of 6 h within the tropical troposphere. Peak convective outflow altitudes range from around 300 hPa to almost 100 hPa among the different models, and the upper tropospheric tracer mixing ratios differ by up to an order of magnitude. The timing of convective events is found to be different between the models, even among those which source their forcing data from the same NWP model (ECMWF. The differences are less pronounced for longer lived tracers, however they could have implications for modelling the halogen burden of the lowermost stratosphere through transport of species such as bromoform, or short-lived hydrocarbons into the lowermost stratosphere. The modelled tracer profiles are strongly influenced by the convective transport parameterisations, and different boundary layer mixing parameterisations also have a large impact on the modelled tracer profiles. Preferential locations for rapid transport from the surface into the upper troposphere are similar in all models, and are mostly concentrated over the western Pacific, the Maritime Continent and the Indian Ocean. In contrast, models do not indicate that upward transport is highest over western Africa.

  2. Landscape change in the Holocene transition Development of a predictive model of vegetation cover in the Asón Valley (Cantabria

    Directory of Open Access Journals (Sweden)

    García Moreno, Alejandro

    2007-12-01

    Full Text Available The spatial distribution of prehistoric vegetation, and its evolution during the Pleistocene-Holocene transition, is essential for understanding the changes in the settlement patterns that took place at the end of the Upper Palaeolithic. To calculate this distribution, we have use a predictive model based on the weighted values method, according to the forest vegetation’s ecological requirements, analizing its evolution in the Asón river valley (Cantabria and its relationship with Palaeolithic sites.

    El conocimiento de la distribución espacial de la vegetación prehistórica, y su evolución a lo largo de la transición al Holoceno, es fundamental para entender los cambios en los patrones de explotación del territorio y de asentamiento que se producen en los grupos de cazadores-recolectores del final del Paleolítico Superior. Para calcular dicha distribución, se emplea un modelo predictivo basado en el método de weighted values (valores ponderados, a partir de los requerimientos ecológicos de la vegetación arbórea, analizando su evolución en el Valle del Asón (Cantabria y su relación con los yacimientos paleolíticos que allí existen.

  3. Emission quantification using the tracer gas dispersion method: The influence of instrument, tracer gas species and source simulation

    DEFF Research Database (Denmark)

    Delre, Antonio; Mønster, Jacob; Samuelsson, Jerker

    2018-01-01

    The tracer gas dispersion method (TDM) is a remote sensing method used for quantifying fugitive emissions by relying on the controlled release of a tracer gas at the source, combined with concentration measurements of the tracer and target gas plumes. The TDM was tested at a wastewater treatment...... plant for plant-integrated methane emission quantification, using four analytical instruments simultaneously and four different tracer gases. Measurements performed using a combination of an analytical instrument and a tracer gas, with a high ratio between the tracer gas release rate and instrument...... precision (a high release-precision ratio), resulted in well-defined plumes with a high signal-to-noise ratio and a high methane-to-tracer gas correlation factor. Measured methane emission rates differed by up to 18% from the mean value when measurements were performed using seven different instrument...

  4. Asian Tracer Experiment and Atmospheric Modeling (TEAM) Project: Draft Field Work Plan for the Asian Long-Range Tracer Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Allwine, K Jerry; Flaherty, Julia E.

    2007-08-01

    This report provides an experimental plan for a proposed Asian long-range tracer study as part of the international Tracer Experiment and Atmospheric Modeling (TEAM) Project. The TEAM partners are China, Japan, South Korea and the United States. Optimal times of year to conduct the study, meteorological measurements needed, proposed tracer release locations, proposed tracer sampling locations and the proposed durations of tracer releases and subsequent sampling are given. Also given are the activities necessary to prepare for the study and the schedule for completing the preparation activities leading to conducting the actual field operations. This report is intended to provide the TEAM members with the information necessary for planning and conducting the Asian long-range tracer study. The experimental plan is proposed, at this time, to describe the efforts necessary to conduct the Asian long-range tracer study, and the plan will undoubtedly be revised and refined as the planning goes forward over the next year.

  5. Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics.

    Science.gov (United States)

    Schleyer, P J; Thielemans, K; Marsden, P K

    2014-08-07

    Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions.

  6. Extracting a respiratory signal from raw dynamic PET data that contain tracer kinetics

    International Nuclear Information System (INIS)

    Schleyer, P J; Thielemans, K; Marsden, P K

    2014-01-01

    Data driven gating (DDG) methods provide an alternative to hardware based respiratory gating for PET imaging. Several existing DDG approaches obtain a respiratory signal by observing the change in PET-counts within specific regions of acquired PET data. Currently, these methods do not allow for tracer kinetics which can interfere with the respiratory signal and introduce error. In this work, we produced a DDG method for dynamic PET studies that exhibit tracer kinetics. Our method is based on an existing approach that uses frequency-domain analysis to locate regions within raw PET data that are subject to respiratory motion. In the new approach, an optimised non-stationary short-time Fourier transform was used to create a time-varying 4D map of motion affected regions. Additional processing was required to ensure that the relationship between the sign of the respiratory signal and the physical direction of movement remained consistent for each temporal segment of the 4D map. The change in PET-counts within the 4D map during the PET acquisition was then used to generate a respiratory curve. Using 26 min dynamic cardiac NH 3 PET acquisitions which included a hardware derived respiratory measurement, we show that tracer kinetics can severely degrade the respiratory signal generated by the original DDG method. In some cases, the transition of tracer from the liver to the lungs caused the respiratory signal to invert. The new approach successfully compensated for tracer kinetics and improved the correlation between the data-driven and hardware based signals. On average, good correlation was maintained throughout the PET acquisitions. (paper)

  7. [18F]Fluoroazabenzoxazoles as potential amyloid plaque PET tracers: synthesis and in vivo evaluation in rhesus monkey

    International Nuclear Information System (INIS)

    Hostetler, Eric D.; Sanabria-Bohórquez, Sandra; Fan Hong; Zeng, Zhizhen; Gammage, Linda; Miller, Patricia; O'Malley, Stacey; Connolly, Brett; Mulhearn, James; Harrison, Scott T.; Wolkenberg, Scott E.; Barrow, James C.; Williams, David L.; Hargreaves, Richard J.; Sur, Cyrille; Cook, Jacquelynn J.

    2011-01-01

    Introduction: An 18 F-labeled positron emission tomography (PET) tracer for amyloid plaque is desirable for early diagnosis of Alzheimer's disease, particularly to enable preventative treatment once effective therapeutics are available. Similarly, such a tracer would be useful as a biomarker for enrollment of patients in clinical trials for evaluation of antiamyloid therapeutics. Furthermore, changes in the level of plaque burden as quantified by an amyloid plaque PET tracer may provide valuable insights into the effectiveness of amyloid-targeted therapeutics. This work describes our approach to evaluate and select a candidate PET tracer for in vivo quantification of human amyloid plaque. Methods: Ligands were evaluated for their in vitro binding to human amyloid plaques, lipophilicity and predicted blood–brain barrier permeability. Candidates with favorable in vitro properties were radiolabeled with 18 F and evaluated in vivo. Baseline PET scans in rhesus monkey were conducted to evaluate the regional distribution and kinetics of each tracer using tracer kinetic modeling methods. High binding potential in cerebral white matter and cortical grey matter was considered an unfavorable feature of the candidate tracers. Results: [ 18 F]MK-3328 showed the most favorable combination of low in vivo binding potential in white matter and cortical grey matter in rhesus monkeys, low lipophilicity (Log D=2.91) and high affinity for human amyloid plaques (IC 50 =10.5±1.3 nM). Conclusions: [ 18 F]MK-3328 was identified as a promising PET tracer for in vivo quantification of amyloid plaques, and further evaluation in humans is warranted.

  8. Noaa chlorofluorocarbon tracer program air and seawater measurements: 1986-1989. Data file

    International Nuclear Information System (INIS)

    Wisegarver, D.P.; Bullister, J.L.; Gammon, R.H.; Menzia, F.A.; Kelly, K.C.

    1993-04-01

    The NOAA Chlorofluorocarbon (CFC) Tracer Program at PMEL has been measuring the growing burden of these anthropogenic gases in the thermocline waters of the Pacific Ocean since 1980. The central goals of the NOAA CFC Tracer Program are to document the transient invasion of the CFC tracers into the Pacific Ocean, by means of repeat occupations of key hydrographic sections at 5-year intervals, and to interpret these changing distributions in terms of coupled ocean-atmosphere models. Studies are underway to use the CFC observations in model-validation studies, and to help develop predictive capabilities on the decade-to-century timescale. The report includes measurements of trichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) dissolved in seawater samples collected in the Pacific Ocean by the NOAA CFC Tracer Program on six cruises during the period of 1986-1989. Measurements of depth, pressure, salinity, temperature, and dissolved oxygen are included with the CFC data. Measurements of CFC-11 and CFC-12 in air samples collected along the cruise tracks are also included in the report. Data from the report are also available from the authors in digital format

  9. Multimodel analysis of anisotropic diffusive tracer-gas transport in a deep arid unsaturated zone

    Science.gov (United States)

    Green, Christopher T.; Walvoord, Michelle Ann; Andraski, Brian J.; Striegl, Robert G.; Stonestrom, David A.

    2015-01-01

    Gas transport in the unsaturated zone affects contaminant flux and remediation, interpretation of groundwater travel times from atmospheric tracers, and mass budgets of environmentally important gases. Although unsaturated zone transport of gases is commonly treated as dominated by diffusion, the characteristics of transport in deep layered sediments remain uncertain. In this study, we use a multimodel approach to analyze results of a gas-tracer (SF6) test to clarify characteristics of gas transport in deep unsaturated alluvium. Thirty-five separate models with distinct diffusivity structures were calibrated to the tracer-test data and were compared on the basis of Akaike Information Criteria estimates of posterior model probability. Models included analytical and numerical solutions. Analytical models provided estimates of bulk-scale apparent diffusivities at the scale of tens of meters. Numerical models provided information on local-scale diffusivities and feasible lithological features producing the observed tracer breakthrough curves. The combined approaches indicate significant anisotropy of bulk-scale diffusivity, likely associated with high-diffusivity layers. Both approaches indicated that diffusivities in some intervals were greater than expected from standard models relating porosity to diffusivity. High apparent diffusivities and anisotropic diffusivity structures were consistent with previous observations at the study site of rapid lateral transport and limited vertical spreading of gas-phase contaminants. Additional processes such as advective oscillations may be involved. These results indicate that gases in deep, layered unsaturated zone sediments can spread laterally more quickly, and produce higher peak concentrations, than predicted by homogeneous, isotropic diffusion models.

  10. CityFlux perfluorocarbon tracer experiments

    Directory of Open Access Journals (Sweden)

    F. K. Petersson

    2010-07-01

    Full Text Available In June 2006, two perfluorocarbon tracer experiments were conducted in central Manchester UK as part of the CityFlux campaign. The main aim was to investigate vertical dispersion in an urban area during convective conditions, but dispersion mechanisms within the street network were also studied. Paired receptors were used in most cases where one receptor was located at ground level and one at roof level. One receptor was located on the roof of Portland Tower which is an 80 m high building in central Manchester. Source receptor distances in the two experiments varied between 120 and 600 m.

    The results reveal that maximum concentration was sometimes found at roof level rather than at ground level implying the effectiveness of convective forces on dispersion. The degree of vertical dispersion was found to be dependent on source receptor distance as well as on building height in proximity to the release site.

    Evidence of flow channelling in a street canyon was also found. Both a Gaussian profile and a street network model were applied and the results show that the urban topography may lead to highly effective flow channelling which therefore may be a very important dispersion mechanism should the right meteorological conditions prevail.

    The experimental results from this campaign have also been compared with a simple urban dispersion model that was developed during the DAPPLE framework and show good agreement with this.

    The results presented here are some of the first published regarding vertical dispersion. More tracer experiments are needed in order to further characterise vertical concentration profiles and their dependence on, for instance, atmospheric stability. The impact of urban topography on pollutant dispersion is important to focus on in future tracer experiments in order to improve performance of models as well as for our understanding of the relationship between air quality and public health.

  11. CityFlux perfluorocarbon tracer experiments

    Science.gov (United States)

    Petersson, F. K.; Martin, D.; White, I. R.; Henshaw, S. J.; Nickless, G.; Longley, I.; Percival, C. J.; Gallagher, M.; Shallcross, D. E.

    2010-07-01

    In June 2006, two perfluorocarbon tracer experiments were conducted in central Manchester UK as part of the CityFlux campaign. The main aim was to investigate vertical dispersion in an urban area during convective conditions, but dispersion mechanisms within the street network were also studied. Paired receptors were used in most cases where one receptor was located at ground level and one at roof level. One receptor was located on the roof of Portland Tower which is an 80 m high building in central Manchester. Source receptor distances in the two experiments varied between 120 and 600 m. The results reveal that maximum concentration was sometimes found at roof level rather than at ground level implying the effectiveness of convective forces on dispersion. The degree of vertical dispersion was found to be dependent on source receptor distance as well as on building height in proximity to the release site. Evidence of flow channelling in a street canyon was also found. Both a Gaussian profile and a street network model were applied and the results show that the urban topography may lead to highly effective flow channelling which therefore may be a very important dispersion mechanism should the right meteorological conditions prevail. The experimental results from this campaign have also been compared with a simple urban dispersion model that was developed during the DAPPLE framework and show good agreement with this. The results presented here are some of the first published regarding vertical dispersion. More tracer experiments are needed in order to further characterise vertical concentration profiles and their dependence on, for instance, atmospheric stability. The impact of urban topography on pollutant dispersion is important to focus on in future tracer experiments in order to improve performance of models as well as for our understanding of the relationship between air quality and public health.

  12. PIV tracer behavior on propagating shock fronts

    International Nuclear Information System (INIS)

    Glazyrin, Fyodor N; Mursenkova, Irina V; Znamenskaya, Irina A

    2016-01-01

    The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48  ×  24 mm) was used. The flat shock wave with Mach numbers M  =  1.4–2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M  =  1.2–1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03  ±  0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves. (paper)

  13. Macrophage migration inhibitory factor induces epithelial to mesenchymal transition, enhances tumor aggressiveness and predicts clinical outcome in resected pancreatic ductal adenocarcinoma.

    Science.gov (United States)

    Funamizu, Naotake; Hu, Chaoxin; Lacy, Curtis; Schetter, Aaron; Zhang, Geng; He, Peijun; Gaedcke, Jochen; Ghadimi, Michael B; Ried, Thomas; Yfantis, Harris G; Lee, Dong H; Subleski, Jeffrey; Chan, Tim; Weiss, Jonathan M; Back, Timothy C; Yanaga, Katsuhiko; Hanna, Nader; Alexander, H Richard; Maitra, Anirban; Hussain, S Perwez

    2013-02-15

    MIF is a proinflammatory cytokine and is implicated in cancer. A higher MIF level is found in many human cancer and cancer-prone inflammatory diseases, including chronic pancreatitis and pancreatic cancer. We tested the hypothesis that MIF contributes to pancreatic cancer aggressiveness and predicts disease outcome in resected cases. Consistent with our hypothesis we found that an elevated MIF mRNA expression in tumors was significantly associated with poor outcome in resected cases. Multivariate Cox-regression analysis further showed that MIF is independently associated with patients' survival (HR = 2.26, 95% CI = 1.17-4.37, p = 0.015). Mechanistic analyses revealed that MIF overexpression decreased E-cadherin and increased vimentin mRNA and protein levels in pancreatic cancer cell lines, consistent with the features of epithelial-to-mesenchymal transition (EMT). Furthermore, MIF-overexpression significantly increased ZEB1/2 and decreased miR-200b expression, while shRNA-mediated inhibition of MIF increased E-cadherin and miR-200b expression, and reduced the expression of ZEB1/2 in Panc1 cells. Re-expression of miR-200b in MIF overexpressing cells restored the epithelial characteristics, as indicated by an increase in E-cadherin and decrease in ZEB1/2 and vimentin expression. A reduced sensitivity to the chemotherapeutic drug, gemcitabine, occurred in MIF-overexpressing cells. Indicative of an increased malignant potential, MIF over-expressing cells showed significant increase in their invasion ability in vitro, and tumor growth and metastasis in an orthotopic xenograft mouse model. These results support a role of MIF in disease aggressiveness, indicating its potential usefulness as a candidate target for designing improved treatment in pancreatic cancer. Copyright © 2012 UICC.

  14. Survey on industrial applications of radioactive tracers

    International Nuclear Information System (INIS)

    Kim, Jae Rok; Yoo, Young Soo; Lee, Jong Doo; Awh, Ok Doo; Kim, Jun Hyung

    1986-12-01

    Current status and future feasibilities of industrial tracer applications in the Republic of Korea have been surveyed. Microleak detection using Krypton-85 in eight electronics industrial companies, and efficiency tests of steam generators in four nuclear power plants using Sodium-24 are the principal applications in Korea. Future applications are expected for mercury inventory in one soda industrial company, and alkali movement studies in two cement industrial companies. Korean industries expressed deep interest in leak detection in underground pipelines, abrasion/corrosion studies, mixing rate and residence time measurements. (Author)

  15. Pharmaceuticals as Groundwater Tracers - Applications and Limitations

    Science.gov (United States)

    Scheytt, T. J.; Mersmann, P.; Heberer, T.

    2003-12-01

    Pharmaceutically active substances and metabolites are found at concentrations up to the microgram/L-level in groundwater samples from the Berlin (Germany) area and from several other places world wide. Among the compounds detected in groundwater are clofibric acid, propyphenazone, diclofenac, ibuprofen, and carbamazepine. Clofibric acid, the active metabolite of clofibrate and etofibrate (blood lipid regulators) is detected in groundwater at maximum concentrations of 7300 ng/L. Among the most important input paths of drugs are excretion and disposal into the sewage system. Groundwater contamination is likely to be due to leaky sewage systems, influent streams, bank filtration, and irrigation with effluent water from sewage treatment plants. There are no known natural sources of the above mentioned pharmaceuticals. The use of pharmaceuticals as tracers may include: (a) Quantification of infiltration from underground septic tanks (b) Detection of leaky sewage systems / leaky sewage pipes (c) Estimation of the effectiveness of sewage treatment plants (d) Identification of transport pathways of other organic compounds (e) Quantification of surface water / groundwater interaction (f) Characterization of the biodegradation potential. The use of pharmaceuticals as tracers is limited by variations in input. These variations depend on the amount of drugs prescribed and used in the study area, the social structure of the community, the amount of hospital discharge, and temporal concentration variations. Furthermore, the analysis of trace amounts of pharmaceuticals is sophisticated and expensive and may therefore limit the applicability of pharmaceuticals as tracers. Finally, the transport and degradation behavior of pharmaceuticals is not fully understood. Preliminary experiments in the laboratory were conducted using sediment material and groundwater from the Berlin area to evaluate the transport and sorption behavior of selected drugs. Results of the column experiments

  16. Tracer preparate and method for its production

    International Nuclear Information System (INIS)

    Pratt, F.P.; Gagnon, D.

    1978-01-01

    The injectable tracer preparate for investigations to determine the blood flow in organs or the effect of drugs on the blood flow consists of a core of ion exchanger resin coated with polyfuran or a polymer which is the reaction product of a monomer catalysable by acid or base. The nuclei have a diameter of 10 to 200 micron, the coating thickness is between 1 and 3 micron. Ions of Ce 141, Cr 51, Sr 85, Sr 46 or Co 57 of strength 0.1-100 millicurie are adsorbed on the nucleus. (DG) [de

  17. Tracer techniques in estimating nuclear materials holdup

    International Nuclear Information System (INIS)

    Pillay, K.K.S.

    1987-01-01

    Residual inventory of nuclear materials remaining in processing facilities (holdup) is recognized as an insidious problem for safety of plant operations and safeguarding of special nuclear materials (SNM). This paper reports on an experimental study where a well-known method of radioanalytical chemistry, namely tracer technique, was successfully used to improve nondestructive measurements of holdup of nuclear materials in a variety of plant equipment. Such controlled measurements can improve the sensitivity of measurements of residual inventories of nuclear materials in process equipment by several orders of magnitude and the good quality data obtained lend themselves to developing mathematical models of holdup of SNM during stable plant operations

  18. Recover Act. Verification of Geothermal Tracer Methods in Highly Constrained Field Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Matthew W. [California State University, Long Beach, CA (United States)

    2014-05-16

    The prediction of the geothermal system efficiency is strong linked to the character of the flow system that connects injector and producer wells. If water flow develops channels or “short circuiting” between injection and extraction wells thermal sweep is poor and much of the reservoir is left untapped. The purpose of this project was to understand how channelized flow develops in fracture geothermal reservoirs and how it can be measured in the field. We explored two methods of assessing channelization: hydraulic connectivity tests and tracer tests. These methods were tested at a field site using two verification methods: ground penetrating radar (GPR) images of saline tracer and heat transfer measurements using distributed temperature sensing (DTS). The field site for these studies was the Altona Flat Fractured Rock Research Site located in northeastern New York State. Altona Flat Rock is an experimental site considered a geologic analog for some geothermal reservoirs given its low matrix porosity. Because soil overburden is thin, it provided unique access to saturated bedrock fractures and the ability image using GPR which does not effectively penetrate most soils. Five boreholes were drilled in a “five spot” pattern covering 100 m2 and hydraulically isolated in a single bedding plane fracture. This simple system allowed a complete characterization of the fracture. Nine small diameter boreholes were drilled from the surface to just above the fracture to allow the measurement of heat transfer between the fracture and the rock matrix. The focus of the hydraulic investigation was periodic hydraulic testing. In such tests, rather than pumping or injection in a well at a constant rate, flow is varied to produce an oscillating pressure signal. This pressure signal is sensed in other wells and the attenuation and phase lag between the source and receptor is an indication of hydraulic connection. We found that these tests were much more effective than constant

  19. Measurements of waste tank passive ventilation rates using tracer gases

    International Nuclear Information System (INIS)

    Huckaby, J.L.; Olsen, K.B.; Sklarew, D.S.; Evans, J.C.; Remund, K.M.

    1997-09-01

    This report presents the results of ventilation rate studies of eight passively ventilated high-level radioactive waste tanks using tracer gases. Head space ventilation rates were determined for Tanks A-101, AX-102, AX-103, BY-105, C-107, S-102, U-103, and U-105 using sulfur hexafluoride (SF 6 ) and/or helium (He) as tracer gases. Passive ventilation rates are needed for the resolution of several key safety issues. These safety issues are associated with the rates of flammable gas production and ventilation, the rates at which organic salt-nitrate salt mixtures dry out, and the estimation of organic solvent waste surface areas. This tracer gas study involves injecting a tracer gas into the tank headspace and measuring its concentration at different times to establish the rate at which the tracer is removed by ventilation. Tracer gas injection and sample collection were performed by SGN Eurisys Service Corporation and/or Lockheed Martin Hanford Corporation, Characterization Project Operations. Headspace samples were analyzed for He and SF 6 by Pacific Northwest National Laboratory (PNNL). The tracer gas method was first demonstrated on Tank S-102. Tests were conducted on Tank S-102 to verify that the tracer gas was uniformly distributed throughout the tank headspace before baseline samples were collected, and that mixing was sufficiently vigorous to maintain an approximately uniform distribution of tracer gas in the headspace during the course of the study. Headspace samples, collected from a location about 4 in away from the injection point and 15, 30, and 60 minutes after the injection of He and SF 6 , indicated that both tracer gases were rapidly mixed. The samples were found to have the same concentration of tracer gases after 1 hour as after 24 hours, suggesting that mixing of the tracer gas was essentially complete within 1 hour

  20. Chemotherapeutic agent and tracer composition and use thereof

    International Nuclear Information System (INIS)

    Babb, A. L.

    1985-01-01

    A therapeutic composition suitable for extracorporeal treatment of whole blood comprises a dialyzable chemotherapeutic agent and a dialyzable fluorescable tracer means. The removal rate of the fluorescable tracer compound from treated blood during hemodialysis is a function of the removal rate of unreacted chemotherapeutic agent present. The residual chemotherapeutic agent concentration after hemodialysis is ascertained by measuring the concentration of the fluorescable tracer compound in a dialysate using fluorometric techniques

  1. Atmospheric Gas Tracers in Groundwater: Theory, Sampling. Measurement and Interpretation

    International Nuclear Information System (INIS)

    Bayari, C.S.

    2002-01-01

    Some of the atmospheric gasses posses features that are sought in an environmental tracer of hydrogeologic interest. Among these, chlorofluorocarbons, sulfur hegzafluoride, carbon tetrachloride, methyl chloroform, krypton-85 etc. have found increasing use in groundwater age dating studies during the last ten years. This paper explains the theory of their use as tracer and discusses the major concerns as related to their sampling and analyses. Factors affecting their applicability and the approach to interpret tracer gas data is briefly outlined

  2. Tracer Testing for Estimating Heat Transfer Area in Fractured Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, Karsten; van Heel, Ton; Shan, Chao

    2004-05-12

    A key parameter governing the performance and life-time of a Hot Fractured Rock (HFR) reservoir is the effective heat transfer area between the fracture network and the matrix rock. We report on numerical modeling studies into the feasibility of using tracer tests for estimating heat transfer area. More specifically, we discuss simulation results of a new HFR characterization method which uses surface-sorbing tracers for which the adsorbed tracer mass is proportional to the fracture surface area per unit volume. Sorption in the rock matrix is treated with the conventional formulation in which tracer adsorption is volume-based. A slug of solute tracer migrating along a fracture is subject to diffusion across the fracture walls into the adjacent rock matrix. Such diffusion removes some of the tracer from the fluid in the fractures, reducing and retarding the peak in the breakthrough curve (BTC) of the tracer. After the slug has passed the concentration gradient reverses, causing back-diffusion from the rock matrix into the fracture, and giving rise to a long tail in the BTC of the solute. These effects become stronger for larger fracture-matrix interface area, potentially providing a means for estimating this area. Previous field tests and modeling studies have demonstrated characteristic tailing in BTCs for volatile tracers in vapor-dominated reservoirs. Simulated BTCs for solute tracers in single-phase liquid systems show much weaker tails, as would be expected because diffusivities are much smaller in the aqueous than in the gas phase, by a factor of order 1000. A much stronger signal of fracture-matrix interaction can be obtained when sorbing tracers are used. We have performed simulation studies of surface-sorbing tracers by implementing a model in which the adsorbed tracer mass is assumed proportional to the fracture-matrix surface area per unit volume. The results show that sorbing tracers generate stronger tails in BTCs, corresponding to an effective

  3. Performance Testing of Tracer Gas and Tracer Aerosol Detectors for use in Radionuclide NESHAP Compliance Testing

    Energy Technology Data Exchange (ETDEWEB)

    Fuehne, David Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lattin, Rebecca Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-28

    The Rad-NESHAP program, part of the Air Quality Compliance team of LANL’s Compliance Programs group (EPC-CP), and the Radiation Instrumentation & Calibration team, part of the Radiation Protection Services group (RP-SVS), frequently partner on issues relating to characterizing air flow streams. This memo documents the most recent example of this partnership, involving performance testing of sulfur hexafluoride detectors for use in stack gas mixing tests. Additionally, members of the Rad-NESHAP program performed a functional trending test on a pair of optical particle counters, comparing results from a non-calibrated instrument to a calibrated instrument. Prior to commissioning a new stack sampling system, the ANSI Standard for stack sampling requires that the stack sample location must meet several criteria, including uniformity of tracer gas and aerosol mixing in the air stream. For these mix tests, tracer media (sulfur hexafluoride gas or liquid oil aerosol particles) are injected into the stack air stream and the resulting air concentrations are measured across the plane of the stack at the proposed sampling location. The coefficient of variation of these media concentrations must be under 20% when evaluated over the central 2/3 area of the stack or duct. The instruments which measure these air concentrations must be tested prior to the stack tests in order to ensure their linear response to varying air concentrations of either tracer gas or tracer aerosol. The instruments used in tracer gas and aerosol mix testing cannot be calibrated by the LANL Standards and Calibration Laboratory, so they would normally be sent off-site for factory calibration by the vendor. Operational requirements can prevent formal factory calibration of some instruments after they have been used in hazardous settings, e.g., within a radiological facility with potential airborne contamination. The performance tests described in this document are intended to demonstrate the reliable

  4. The ATLAS DDM Tracer monitoring framework

    CERN Document Server

    ZANG, D; The ATLAS collaboration; BARISITS, M; LASSNIG, M; Andrew STEWART, G; MOLFETAS, A; BEERMANN, T

    2012-01-01

    The DDM Tracer Service is aimed to trace and monitor the atlas file operations on the Worldwide LHC Computing Grid. The volume of traces has increased significantly since the service started in 2009. Now there are about ~5 million trace messages every day and peaks of greater than 250Hz, with peak rates continuing to climb, which gives the current service structure a big challenge. Analysis of large datasets based on on-demand queries to the relational database management system (RDBMS), i.e. Oracle, can be problematic, and have a significant effect on the database's performance. Consequently, We have investigated some new high availability technologies like messaging infrastructure, specifically ActiveMQ, and key-value stores. The advantages of key value store technology are that they are distributed and have high scalability; also their write performances are usually much better than RDBMS, all of which are very useful for the Tracer service. Indexes and distributed counters have been also tested to improve...

  5. Climate proxy data as groundwater tracers in regional flow systems

    Science.gov (United States)

    Clark, J. F.; Morrissey, S. K.; Stute, M.

    2008-05-01

    The isotopic and chemical signatures of groundwater reflect local climate conditions. By systematically analyzing groundwater and determining their hydrologic setting, records of past climates can be constructed. Because of their chemistries and relatively uncomplicated source functions, dissolved noble gases have yielded reliable records of continental temperatures for the last 30,000 to 50,000 years. Variations in the stable isotope compositions of groundwater due to long term climate changes have also been documented over these time scales. Because glacial - interglacial climate changes are relatively well known, these climate proxies can be used as "stratigraphic" markers within flow systems and used to distinguish groundwaters that have recharged during the Holocene from those recharged during the last glacial period, important time scales for distinguishing regional and local flow systems in many aquifers. In southern Georgia, the climate proxy tracers were able to identify leakage from surface aquifers into the Upper Floridan aquifer in areas previously thought to be confined. In south Florida, the transition between Holocene and glacial signatures in the Upper Floridan aquifer occurs mid-way between the recharge area and Lake Okeechobee. Down gradient of the lake, the proxies are uniform, indicating recharge during the last glacial period. Furthermore, there is no evidence for leakage from the shallow aquifers into the Upper Floridan. In the Lower Floridan, the climate proxies indicate that the saline water entered the aquifer after sea level rose to its present level.

  6. Advancing Reactive Tracer Methods for Measurement of Thermal Evolution in Geothermal Reservoirs: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell A. Plummer; Carl D. Palmer; Earl D. Mattson; Laurence C. Hull; George D. Redden

    2011-07-01

    The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of novel

  7. Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification

    NARCIS (Netherlands)

    Zimmermann, M.B.; Zeder, C.; Muthayya, S.; Winichagoon, P.; Chaouki, N.; Aeberli, I.; Hurrell, R.F.

    2008-01-01

    Background: Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association

  8. Multiscale investigation of catchment functioning using environmental tracers: Insights from the mesoscale Attert basin in Luxembourg

    Science.gov (United States)

    Wrede, S.; Pfister, L.; Krein, A.; Bogaard, T. A.; Savenije, H. H. G.; Uhlenbrook, S.

    2009-04-01

    Experimental hydrology focuses traditionally on field investigations at smaller spatial and temporal scales and research is driven by small-scale, detailed and complex investigations of densely instrumented research sites. However, to improve operational water management and protection of water resources at the river basin scale, it is necessary to study the hydrological processes across a range of scales. Empirical studies investigating catchment structure and functioning across multiple scales are still rare and urgently needed. Besides geomorphologic and climatic catchment descriptors, environmental tracers have been recognized as a fundamental tool in experimental hydrology to assess the scaling gap, as they provide an independent and integrative perspective of catchment functioning and scaling. A three year tracer study is being carried out in the Attert river basin in Luxembourg to identify how major controls of runoff generation change across scales and to investigate the spatial and temporal functioning of larger basins. The mesoscale (300 km²) Attert catchment is located in the Midwestern part of Luxembourg and lies at the transition zone of contrasting bedrock lithology that is a major control for runoff generation: The Northern part is characterized by Devonian schist of the Ardennes massif, while sedimentary deposits of sandstone and marls dominate in the Southern part of the basin. Major hydrochemical tracers including stable water isotopes were grab sampled fortnightly and, where possible, also event-based at 13 nested stream locations ranging in size from 0.5 to 300 km² throughout the basin. Results using Deuterium and a range of hydrochemical tracers confirm the major role of bedrock lithology for runoff response of different geological parts of the basins: Hydrological response of schistose basins is characterized by seasonal variation and a delayed shallow groundwater component originating from a saprolitic zone, sandstone basins exhibit a

  9. TMI cable tracer operation and maintenance manual for assembly 417910

    International Nuclear Information System (INIS)

    Sumstine, R.L.

    1983-11-01

    This manual provides technical information and instructions to operate and maintain the cable tracer designed for the Three Mile Island (TMI) Unit 2 Reactor Building. The TMI cable tracer was developed to allow TMI personnel to trace cables in cable trays that may be tested or sectioned for destructive examination

  10. Methane emission quantification from landfills using a double tracer approach

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Samuelsson, J.; Fredenslund, Anders Michael

    2007-01-01

    A tracer method was successfully used for quantification of the whole methane (CH4) emission from Fakse landfill. By using two different tracers the emission from different sections of the landfill could be quantified. Furthermore, is was possible to determine the emissions from local on site...

  11. Toxicity of fluorescent tracers and their degradation byproducts

    Directory of Open Access Journals (Sweden)

    Philippe Gombert

    2017-01-01

    Full Text Available Tracer tests are frequently used to delineate catchment area of water supply springs in karstic zones. In the karstic chalk of Normandy, the main tracers used are fluorescent: uranine, sulforhodamine B, naphtionate, and Tinopal®. In this area, a statistical analysis shows that less than half of the injected tracers joins the monitored restitution points and enters the drinking water system where they undergo chlorination. Most of the injected tracers is absorbed in the rock matrix or is thrown out of the aquifer via karstic springs: then it can join superficial waters where it is degraded due to the sun and air action. The paper presents firstly the laboratory degradation of a first batch of fluorescent tracers in contact with chlorine, in order to simulate their passage through a water treatment system for human consumption. A second batch of the same tracers is subjected to agents of natural degradation: ultraviolet illumination, sunlight and air sparging. Most tracers is degraded, and toxicity and ecotoxicity tests (on rats, daphniae and algae are performed on degradation byproducts. These tests do not show any acute toxicity but a low to moderate ecotoxicity. In conclusion, the most used fluorescent tracers of the Normandy karstic chalk and their artificial and natural degradation byproducts do not exhibit significant toxicity to humans and the aquatic environment, at the concentrations generally noted at the restitution points.

  12. A survey of HC3N in extragalactic sources - is HC3N a tracer of activity in ULIRGs?

    DEFF Research Database (Denmark)

    Lindberg, Johan; Aalto, S.; Costagliola, F.

    2011-01-01

    , and to compare HC3N with other molecular tracers (HCN, HNC), as well as other properties (silicate absorption strength, IR flux density ratios, C II flux, and megamaser activity). Methods. We present mm IRAM 30 m, OSO 20 m, and SEST observations of HC3N rotational lines (mainly the J = 10-9 transition...

  13. National Biomedical Tracer Facility. Project definition study

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, R.

    1995-02-14

    We request a $25 million government-guaranteed, interest-free loan to be repaid over a 30-year period for construction and initial operations of a cyclotron-based National Biomedical Tracer Facility (NBTF) in North Central Texas. The NBTF will be co-located with a linear accelerator-based commercial radioisotope production facility, funded by the private sector at approximately $28 million. In addition, research radioisotope production by the NBTF will be coordinated through an association with an existing U.S. nuclear reactor center that will produce research and commercial radioisotopes through neutron reactions. The combined facilities will provide the full range of technology for radioisotope production and research: fast neutrons, thermal neutrons, and particle beams (H{sup -}, H{sup +}, and D{sup +}). The proposed NBTF facility includes an 80 MeV, 1 mA H{sup -} cyclotron that will produce proton-induced (neutron deficient) research isotopes.

  14. Use of radioactive tracers in chemical reactions

    International Nuclear Information System (INIS)

    Paci, B.; Saiki, M.

    1979-01-01

    A method for the determination of small quantities of nickel by using radioactive tracers is presented. An analytical application of the displacement reaction between and zinc-ethylenediaminetetraacetate, (Zn-EDTA), labelled with 65 Zn is investigated. This method is based on the extraction of radioactive zinc, displaced by nickel from the zinc chelate, into a dithizone-carbon tetrachloride solution and the subsequent measurement of the activity of an aliquot of the extract. It is shown that the method is very sentitive and nickel can be measured in concentrations as small as 0,1μg/ml or even less, depending on the specific activity of the radioreagent used. The precision and accuracy of the method are determined. An attempt to eliminate the problem of interference by using masking agents or by means of a previous separation of nickel and other interfereing metals, is also made. (Author) [pt

  15. New SPECT and PET dementia tracers

    International Nuclear Information System (INIS)

    Vergote, J.; Chalon, S.; Emond, P.; Vercouillie, J.; Guilloteau, D.; Vergote, J.; Guilloteau, D.; Pappata, J.S.

    2009-01-01

    Single photon emission tomography (SPECT) and positron emission tomography (PET) are techniques to study in vivo neurotransmitter systems, neuro inflammation and amyloid deposits in normal human brain and in dementia. These methods used to explore the integrity of dopaminergic, cholinergic and serotonergic systems in Alzheimer's disease and in other dementias allowed to understand how the neurotransmission was modified in these disorders. Progress in the understanding of pathophysiological and clinical signs of dementia requires an evolution of the radioligands used to carry out an increasingly early and differential diagnosis in addition to monitoring the progression of disease and the effects of therapies. New emerging radiotracers for neuro inflammation or amyloid deposits are essential. In this article, new SPECT and PET tracers are presented. (authors)

  16. Positron emission tomography tracers for imaging angiogenesis

    International Nuclear Information System (INIS)

    Haubner, Roland; Beer, Ambros J.; Wang, Hui; Chen, Xiaoyuan

    2010-01-01

    Position emission tomography imaging of angiogenesis may provide non-invasive insights into the corresponding molecular processes and may be applied for individualized treatment planning of antiangiogenic therapies. At the moment, most strategies are focusing on the development of radiolabelled proteins and antibody formats targeting VEGF and its receptor or the ED-B domain of a fibronectin isoform as well as radiolabelled matrix metalloproteinase inhibitors or α v β 3 integrin antagonists. Great efforts are being made to develop suitable tracers for different target structures. All of the major strategies focusing on the development of radiolabelled compounds for use with positron emission tomography are summarized in this review. However, because the most intensive work is concentrated on the development of radiolabelled RGD peptides for imaging α v β 3 expression, which has successfully made its way from bench to bedside, these developments are especially emphasized. (orig.)

  17. Atmospheric tracer experiments for regional dispersion studies

    International Nuclear Information System (INIS)

    Heffter, J.L.; Ferber, G.J.

    1980-01-01

    Tracer experiments are being conducted to verify atmospheric transport and dispersion calculations at distances from tens to hundreds of km from pollutant sources. In one study, a 2 1/2 year sampling program has been carried out at 13 sites located 30 to 140 km from a source of 85 Kr at the Savannah River Plant in South Carolina. Average weekly concentrations as well as twice-daily concentrations were obtained. Sampling data and meteorological data, including surface, tower, and rawinsonde observations are available on magnetic tape for model verification studies. Some verification results for the Air Resources Laboratories Atmospheric Transort and Dispersion Model (ARL-ATAD) are shown for averaging periods from one week to two years

  18. Use of radioactive tracers in chemical reactions

    International Nuclear Information System (INIS)

    Paci, B.

    1979-01-01

    A method for the determination of small quantities of nickel using radioactive tracers is presented. An analytical application of the displacement reaction between nickel and zinc ethylenediaminetetraacetate labeled with zinc-65 is pursued. This method is based on the extraction of radioactive zinc displaced by nickel from the zinc chelate into a dithizone-carbon tetracloride solution and the subsequent measurement of the activity of an aliquot of the extract. The method is very sensitive and nickel can be measured in concentrations as small as 0.1μg/ml or even less, depending on the specific activity of the radioreagent used. The precision and the accuracy of the method are determined. The problem of interferences, trying to eliminate them by using masking agents or by means of a previous separation between nickel and other interfering metals, is also investigated [pt

  19. National Biomedical Tracer Facility. Project definition study

    International Nuclear Information System (INIS)

    Schafer, R.

    1995-01-01

    We request a $25 million government-guaranteed, interest-free loan to be repaid over a 30-year period for construction and initial operations of a cyclotron-based National Biomedical Tracer Facility (NBTF) in North Central Texas. The NBTF will be co-located with a linear accelerator-based commercial radioisotope production facility, funded by the private sector at approximately $28 million. In addition, research radioisotope production by the NBTF will be coordinated through an association with an existing U.S. nuclear reactor center that will produce research and commercial radioisotopes through neutron reactions. The combined facilities will provide the full range of technology for radioisotope production and research: fast neutrons, thermal neutrons, and particle beams (H - , H + , and D + ). The proposed NBTF facility includes an 80 MeV, 1 mA H - cyclotron that will produce proton-induced (neutron deficient) research isotopes

  20. Unsaturated water flow and tracer transport modeling with Alliances

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, Alina, E-mail: alina.constantin@nuclear.ro [Institute for Nuclear Research, Campului Str, No. 1, PO Box 78, Postal Code 115400 Mioveni, Arges County (Romania); Genty, Alain, E-mail: alain.genty@cea.fr [CEA Saclay, DM2S/SFME/LSE, Gif-sur-Yvette 91191 cedex (France); Diaconu, Daniela; Bucur, Crina [Institute for Nuclear Research, Campului Str, No. 1, PO Box 78, Postal Code 115400 Mioveni, Arges County (Romania)

    2013-12-15

    Highlights: • Simulation of water flow and solute transport at Saligny site, Romania was done. • Computation was based on the available experimental data with Alliances platform. • Very good results were obtained for the saturation profile in steady state. • Close fit to experimental data for saturation profile at 3 m in transient state. • Large dispersivity coefficients were fitted to match tracer experiment. - Abstract: Understanding water flow and solute transport in porous media is of central importance in predicting the radionuclide fate in the geological environment, a topic of interest for the performance and safety assessment studies for nuclear waste disposal. However, it is not easy to predict transport properties in real systems because they are geologically heterogeneous from the pore scale upwards. This paper addresses the simulation of water flow and solute transport in the unsaturated zone of the Saligny site, the potential location for the Romanian low and intermediate level waste (LILW) disposal. Computation was based on the current available experimental data for this zone and was performed within Alliances, a software platform initially jointly developed by French organizations CEA, ANDRA and EDF. The output of the model developed was compared with the measured values in terms of saturation profile of the soil for water movement, in both steady and transient state. Very good results were obtained for the saturation profile in steady state and a close fit of the simulation over experimental data for the water saturation profile at a depth of 3 m in transient state. In order to obtain information regarding the solute migration in depth and the solute lateral dispersion, a tracer test was launched on site and dispersivity coefficients of the solute were fitted in order to match the experimental concentration determined on samples from different locations of the site. Results much close to the experiment were obtained for a longitudinal

  1. Transitional Justice

    DEFF Research Database (Denmark)

    Gissel, Line Engbo

    This presentation builds on an earlier published article, 'Contemporary Transitional Justice: Normalising a Politics of Exception'. It argues that the field of transitional justice has undergone a shift in conceptualisation and hence practice. Transitional justice is presently understood to be th...... to be the provision of ordinary criminal justice in contexts of exceptional political transition.......This presentation builds on an earlier published article, 'Contemporary Transitional Justice: Normalising a Politics of Exception'. It argues that the field of transitional justice has undergone a shift in conceptualisation and hence practice. Transitional justice is presently understood...

  2. USING PERFLUOROCARBON TRACERS FOR VERIFICATION OF CAP AND COVER SYSTEMS PERFORMANCE

    International Nuclear Information System (INIS)

    HEISER, J.; SULLIVAN, T.

    2001-01-01

    The Department of Energy (DOE) Environmental Management (EM) office has committed itself to an accelerated cleanup of its national facilities. The goal is to have much of the DOE legacy waste sites remediated by 2006. This includes closure of several sites (e.g., Rocky Flats and Fernald). With the increased focus on accelerated cleanup, there has been considerable concern about long-term stewardship issues in general, and verification and long-term monitoring (LTM) of caps and covers, in particular. Cap and cover systems (covers) are vital remedial options that will be extensively used in meeting these 2006 cleanup goals. Every buried waste site within the DOE complex will require some form of cover system. These covers are expected to last from 100 to 1000 years or more. The stakeholders can be expected to focus on system durability and sustained performance. DOE EM has set up a national committee of experts to develop a long-term capping (LTC) guidance document. Covers are subject to subsidence, erosion, desiccation, animal intrusion, plant root infiltration, etc., all of which will affect the overall performance of the cover. Very little is available in terms of long-term monitoring other than downstream groundwater or surface water monitoring. By its very nature, this can only indicate that failure of the cover system has already occurred and contaminants have been transported away from the site. This is unacceptable. Methods that indicate early cover failure (prior to contaminant release) or predict approaching cover failure are needed. The LTC committee has identified predictive monitoring technologies as a high priority need for DOE, both for new covers as well as existing covers. The same committee identified a Brookhaven National Laboratory (BNL) technology as one approach that may be capable of meeting the requirements for LTM. The Environmental Research and Technology Division (ERTD) at BNL developed a novel methodology for verifying and monitoring

  3. Suitable activated carbon-13 tracer techniques

    International Nuclear Information System (INIS)

    Zhang Weicheng; Peng Xiuru; Wang Yuhua

    1995-12-01

    Feasibility and applicability studies of the proton induced gamma ray emission (PIGE) have been performed. The graphite was firstly bombarded at various proton energies to determine gamma ray yield (and, thus, sensitivities) for the reaction of interest. The accuracy for the determination of 13 C abundance was checked, and the precision with which this value and ratios 13 C/ 12 C may be obtained was established by repetitive analysis samples. The performance of different standards in this determination was assessed. The mathematical treatment was developed for the determination of 13 C abundance in tracer studies, and to derive the equations that govern this method of analysis from first principles, to arrive finally at a simple expression by virtue of the observed regularities. The system was calibrated by measuring the gamma ray yield form the 12 C (p, γ) 13 N and 13 C(p,γ) 14 N reaction as a function of known 13 C enrichment. Using this experimentally determined calibration curve, unknown materials can be assayed. This technique is applicable to the analysis of samples with 13 C enrichments between 0.1% and 90%. The samples of human breath natural samples were analyzed against graphite and Cylinder CO 2 standards. Relative standard deviations were 13 C abundance, an increase in 13 C per cent isotopic abundance from the natural 1.11% (average) to only 1.39% may be ascertained. Finally, PIGE is compared with more classical techniques for analysis of 13 C tracer experiments. Ease and speed are important advantages of this technique over mass spectrometry, and its error is compatible with the natural variation of biological results. (9 refs., 11 figs., 9 tabs.)

  4. The European tracer experiment ETEX: a real-time long range atmospheric dispersion model exercise in different weather conditions

    International Nuclear Information System (INIS)

    Graziani, G.; )

    1998-01-01

    Two long-range tracer experiments were conducted. An inert, non-depositing tracer was being released at Rennes in France for 12 hours. The 168 sampling ground stations were run by the National Meteorological Services. Twenty-four institutions took part in the real-time forecasting of the cloud evolution using 28 long-range dispersion models. The horizontal projection of the cloud evolution over Europe was combined with real-time aerial chemical analysis. The results of the comparison indicate that a limited group of models (7-8) were capable of obtaining a good reproduction of the cloud movement throughout Europe for the first release. Large differences were, however, found in the predicted tracer concentration at a particular location. For the second release, there were large differences between the measured and calculated cloud, particularly after a front passage, which indicates that some efforts have still to be spent before consensus on the model reliability is achieved. (P.A.)

  5. Rate equations for tracer studies in recirculating reactors

    Energy Technology Data Exchange (ETDEWEB)

    Happel, J [Columbia Univ., New York (USA). Dept. of Chemical Engineering

    1974-10-01

    The employment of isotopic tracers is a useful technique for gaining insight into the rate controlling steps of a complex chemical reaction such as is frequently encountered in heterogeneous catalysis. An effective procedure has been to superpose tracer transfer on a reaction which is occurring under steady state conditions. If tracer transfer is employed in this fashion it is often possible to assess the individual step velocities in an assumed reaction mechanism. If transient transfer of tracer is now introduced it is possible in addition to estimate surface concentrations of chemisorbed species. The purpose of the present paper is to present the mathematical relationships involved when transfer of the tracer is not differential in the investigation. For this purpose a simple example is chosen to illustrate the various possibilities involved.

  6. Molecular dynamics investigation of tracer diffusion in a simple liquid

    International Nuclear Information System (INIS)

    Ould-Kaddour, F.; Barrat, J.L.

    1991-05-01

    Extensive Molecular-Dynamics (MD) simulations have been carried out for a model trace-solvent system made up of 100 solvent molecules and 8 tracer molecules interacting through truncated Lennard-Jones potentials. The influence of the size ratio between solute and solvent, of their mass ratio and of the solvent viscosity on the diffusivity of a small tracer were investigated. Positive deviations from a Stokes-Einstein behaviour are observed, in qualitative agreement with experimental observations. It was also observed that as tracer and solvent become increasingly dissimilar, their respective dynamics becomes decoupled. We suggest that such decouplings can be interpreted by writing their mobility of the tracer as the sum of two terms, the first one arising from a coupling between tracer dynamics and hydrodynamics modes of the solvent, and the second one describing jump motion in a locally nearly frozen environment. (author). 17 refs, 4 figs, 6 tabs

  7. Rate equations for tracer studies in recirculatinng reactors

    International Nuclear Information System (INIS)

    Happel, J.

    1974-01-01

    The employment of isotopic tracers is a useful technique for gaining insight into the rate controlling steps of a complex chemical reaction such as is frequently encountered in heterogeneous catalysis. An effective procedure has been to superpose tracer transfer on a reaction which is occurring under steady state conditions. If tracer transfer is employed in this fashion it is often possible to assess the individual step velocities in an assumed reaction mechanism. If transient transfer of tracer is now introduced it is possible in addition to estimate surface concentrations of chemisorbed species. The purpose of the present paper is to present the mathematical relationships involved when transfer of the tracer is not differential in the investigation. For this purpose a simple example is chosen to illustrate the various possibilities involved. (auth.)

  8. Benefits of important industrial tracer applications in the GDR

    International Nuclear Information System (INIS)

    Leonhardt, J.W.; Goeldner, R.; Koennecke, H.G.; Kupsch, H.; Luther, D.; Otto, R.; Reinhardt, R.; Ulrich, H.

    1990-01-01

    Tracers can be used to label substances or objects in order to discriminate between them, to follow their movement, to record changes of concentration and distribution between phases, etc. The main advantages of tracer investigations are the contactless recording of signals without influencing the observed process (also under rigorous operation conditions), the high detection sensitivity, the large number of available tracer nuclides (problems of all branches of industry can be solved) and the fact that tracer investigation can be carried out on operating production units, so that they provide valuable checks of the validity of design and process data. The cost-to-benefit ratio can be as low as 1:50. In the following some selected examples of tracer applications and their benefits will be presented. (orig./BBR) [de

  9. 3-D migration experiment - report 2: Instrumentation and tracers

    International Nuclear Information System (INIS)

    Abelin, H.; Birgersson, L.; Gidlund, J.

    1987-11-01

    This report is one of the four reports describing the Stripa 3D experiment where water and tracer flow has been monitored in a specially excavated drift in the Stripa mine. The experiment was performed in a specially excavated drift at the 360 m level in granite. The whole ceiling and upper part of the walls were covered with more than 350 individual plastic sheets where the water flow into the drift could be collected. 11 different tracers were injected at distances between 11 and 50 m from the ceiling of the drift. The flow rate and tracer monitoring was kept up for more than two years. The tracer breakthrough curves and flow rate distributions were used to study the flow paths, velocities, hydraulic conductivities, dispersivities and channeling effects in the rock. The report describes the instrumentation developed and used as well as the tracers that were tested and used in the experiment. (orig.)

  10. The hydraulic properties of fracture zones and tracer tests with non-reactive elements in Studsvik

    International Nuclear Information System (INIS)

    Klockars, C.-E.; Persson, O.; Landstroem, O.

    1982-04-01

    Tracer technique was applied in a rock formation within the Studsvik Energiteknik area in order to study hydrodynamic properties of discrete fracture zones between boreholes. The two hole method was applied in these studies; a nonreactive tracer is injected in one hole into a fracture zone which is in hydraulic contact with a central pump hole (observation hole). Hydraulic tests and TV inspection were carried out in the fracture zones. Chemical composition of the groundwater was determined. In summary, the following hydraulic properties were found for the fracture zones between the boreholes B1N-B6N and B5N-B6N respectively, under the prevailing conditions: 1) The fracture zones studied consists of a number of transport pathways with different mean transit times, varying from 100 to 1200 hours. 2) The fracture zone between boreholes B1N and B6N has a mean hydraulic conductivity of 6-7 x 10 -5 m/s and the fracture zone between boreholes B5N and B6N, 2 x 10 -4 m/s. 3) The kinematic porosity of the fracture zones studied, calculated as the ratio between the hydraulic conductivity of the rock mass and that of the fracture zone, is 2 x 10 -3 and 5 x 10 -3 , respectively. 4) The roughness factor β, which expresses the ratio between measured and theoretically calculated (plane-parallel) fracture conductivity for the fracture zones studied, is approximately 0.04 and 0.06, respectively. 5) Dispersivity for the flow channels within the fracture zones is of the order of 0.3-0.8 m. 6) The groundwater encountered is a nearly neutral, probably reducing, Na-Ca-HCO 3 water. The results of the tracer tests reveal the following: I-131 is a suitable nonreactive tracer for the test area. A test with simultaneous injection of I-131 and T (tritium) gave comparable breakthrough curves. (Author)

  11. Fracture geometries consistent with tiltmeter data and pressure and tracer communication in the GLISP I-1 stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, I.D.; Moschovidis, Z.A. (Amoco Production Co., Tulsa, OK (USA))

    The goal of this paper is to examine the consistency of three totally independent diagnostic observations of fracturing (tiltmeters, pressure, and tracer communication). The Gregoire Lake In-Situ Steam Pilot (GLISP) in the Athabasca tar sands, includes three producing wells surrounding an injection well. The authors modeled tiltmeter records of the fracturing treatment of the central injection well, and pressure and tracer communication from the central injection well to the producing wells, and investigated how these analyses support various fracture geometry scenarios. Several different fracture geometry scenarios have been examined. Theoretical surface tiltmeter vectors for these scenarios are compared with observed vectors. Also, theoretical time delays based on propagation of pressure transients and tracer material have been predicted for these scenarios, and compared with observed delays. The results of these comparisons are expressed in the form of a range of fracture geometries that are most consistent with measured tiltmeter data in the field, and pressure and tracer time delays in the three production wells. Interpretations within this range include complex fracture systems with one or two fracture components rising steeply from the base of the McMurray Formation into the overlying depleted zone. Dominant horizontal fracturing does not appear to occur. The three independent sets of observations (pressure transient delays, tracer delays, and tiltmeter vectors) support this hypothesis. 9 refs., 20 figs., 3 tabs.

  12. Tests of regional elemental tracers of pollution aerosols. 1. Distinctness of regional signatures, stability during transport, and empirical validation

    International Nuclear Information System (INIS)

    Lowenthal, D.H.; Wunschel, K.R.; Rahn, K.A.

    1988-01-01

    The two major requirements for a successful regional tracer system are distinctness of signatures and stability of signatures during transport. Dissimilarity of the five regional signatures from eastern North America is shown by collinearity diagnostics and by apportionment of synthetic samples generated randomly. Stability of regional signatures during transport is shown first by use of tracer elements in coarse and fine aerosol to predict the maximum possible change of ratios from particle-size effects alone and then by examination of actual changes in signatures during transport from the Midwest to Underhill, VT. Two recent empirical validations of the tracer system are presented: qualitative agreement of pulses of mid-western aerosol in Vermont with pulses of perfluorocarbon tracer gas released in Ohio during CAPTEX '83 and reproduction of our three major northeastern and mid-western signatures by other investigators. The tracer system currently uses the seven elements As, Se, Sb, Zn, In, noncrustal Mn, and noncrustal V as measured by instrumental neutron activation

  13. Tracer migration experiments in the Stripa mine 1980-1991

    International Nuclear Information System (INIS)

    Birgersson, L.; Widen, H.; Aagren, T.; Neretnieks, I.

    1992-05-01

    During more than 10 years, tracer experiments have been performed in the Stripa mine as part of the Stripa project to investigate the properties of both 'average' fractured rock and fracture zones. Experiments have been performed that have ranged from a few decimeters, to examine the diffusion into the rock matrix, up to tracer migration to a drift more than 50 meters from the injection point. This report compiles the results and experience that have been gained from all these tracer experiments. The experiments that are described in this report are: * The in-situ diffusion experiment where simultaneous flow and diffusion of tracers in undisturbed rock were studied over more than 3 years to validate diffusivities obtained under laboratory conditions. * Migration in a single fracture where water flow distribution and tracer transport were studied using both conservative and sorbing tracers over migration distances up to 10 meters. * The 3-D migration experiment where water inflow and tracer transport to a drift covered with 350 plastic sheet were investigated to get information on flow porosity, dispersion and channeling. The transport distances were between 10 and 56 meters from the injection points to the drift. * The channeling experiments in which the aim was to examine the channeling properties of single fractures in detail. Pressure pulse tests and tracer experiments were performed over a distances of 2 meters. * The tracer migration experiment in the validation drift where the tracer were injected mainly in a fracture zone and the collection was inside both a drift covered with plastic sheets similar to in the 3-D experiment as well as in a borehole. The distances between injection and sampling location were between 10 and 25 meters. (57 refs.) (au)

  14. Methods and systems using encapsulated tracers and chemicals for reservoir interrogation and manipulation

    Science.gov (United States)

    Roberts, Jeffery; Aines, Roger D; Duoss, Eric B; Spadaccini, Christopher M

    2014-11-04

    An apparatus, method, and system of reservoir interrogation. A tracer is encapsulating in a receptacle. The receptacle containing the tracer is injected into the reservoir. The tracer is analyzed for reservoir interrogation.

  15. A Study Plan for Determining Recharge Rates at the Hanford Site Using Environmental Tracers

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, E. M.; Szecsody, J. E.; Phillips, S. J.

    1991-02-01

    This report presents a study plan tor estimating recharge at the Hanford Site using environmental tracers. Past operations at the Hanford Site have led to both soil and groundwater contamination, and recharge is one of the primary mechanisms for transporting contaminants through the vadose zone and into the groundwater. The prediction of contaminant movement or transport is one aspect of performance assessment and an important step in the remedial investigation/feasibility study (RI/FS) process. In the past, recharge has been characterized by collecting lysimeter data. Although lysimeters can generate important and reliable data, their limitations include 1) fixed location, 2) fixed sediment contents, 3) edge effects, 4) low rates, and 5) relatively short duration of measurement. These limitations impact the ability to characterize the spatial distribution of recharge at the Hanford Site, and thus the ability to predict contaminant movement in the vadose zone. An alternative to using fixed lysimeters for determining recharge rates in the vadose zone is to use environmental tracers. Tracers that have been used to study water movement in the vadose zone include total chloride, {sup 36}CI, {sup 3}H, and {sup 2}H/{sup 18}O. Atmospheric levels of {sup 36}CI and {sup 3}H increased during nuclear bomb testing in the Pacific, and the resulting "bomb pulse" or peak concentration can be measured in the soil profile. Locally, past operations at the Hanford Site have resu~ed in the atmospheric release of numerous chemical and isotopic tracers, including nitrate, {sup 129}I, and {sup 99}Tc. The radionuclides, in particular, reached a well-defined atmospheric peak in 1945. Atmospheric releases of {sup 129}I and {sup 99}Tc were greatly reduced by mid-1946, but nitrogen oxides continued to be released from the uranium separations facilities. As a result, the nitrate concentrations probably peaked in the mid-1950s, when the greatest number of separations facilities were operating

  16. Novel tracer for radiation treatment planning; Welche neuen PET-Tracer braucht die Strahlentherapie?

    Energy Technology Data Exchange (ETDEWEB)

    Schwarzenboeck, S.; Krause, B.J. [Rostock Univ. (Germany). Klinik fuer Nuklearmedizin; Herrmann, K.; Gaertner, F.; Souvatzoglou, M. [Technische Univ. Muenchen (Germany). Klinik fuer Nuklearmedizin; Klaesner, B. [Klinikum Bogenhausen, Muenchen (Germany). Inst. fuer Radiologie und Nuklearmedizin

    2011-07-15

    PET and PET/CT with innovative tracers gain increasing importance in diagnosis and therapy management, and radiation treatment planning in radio-oncology besides the widely established FDG. The introduction of [{sup 18}F]Fluorothymidine ([{sup 18}F]FLT) as marker of proliferation, [{sup 18}F]Fluoromisonidazole ([{sup 18}F]FMISO) and [{sup 18}F]Fluoroazomycin-Arabinoside ([{sup 18}F]FAZA) as tracer of hypoxia, [{sup 18}F]Fluoroethyltyrosine ([{sup 18}F]FET) and [{sup 11}C]Methionine for brain tumour imaging, [{sup 68}Ga]DOTATOC for somatostatin receptor imaging, [{sup 18}F]FDOPA for dopamine synthesis and radioactively labeled choline derivatives for imaging phospholipid metabolism have opened novel approaches to tumour imaging. Some of these tracers have already been implemented into radio-oncology: Amino acid PET and PET/CT have the potential to optimise radiation treatment planning of brain tumours through accurate delineation of tumour tissue from normal tissue, necrosis and edema. Hypoxia represents a major therapeutic problem in radiation therapy. Hypoxia imaging is very attractive as it may allow to increase the dose in hypoxic tumours potentially allowing for a better tumour control. Advances in hybrid imaging, i.e. the introduction of MR/PET, may also have an impact in radio-oncology through synergies related to the combination of molecular signals of PET and a high soft tissue contrast of MRI as well as functional MRI capabilities. (orig.)

  17. Bromide as a tracer for studying water movement and nitrate displacement in soils: comparison with stable isotope tracers

    International Nuclear Information System (INIS)

    Russow, R.; Knappe, S.

    1999-01-01

    Tracers are an ideal means of studying water movement and associated nitrate displacement. Often bromide is preferred as a tracer because it is considered a representative tracer for water and because, being a conservative tracer (i.e. not involved in chemical and biological soil processes), it can be used for studying anion transport in soils. Moreover, it is less expensive and easier to measure than the stable isotopes deuterium and 15 N. Its great advantage over radioactive tracers (e.g. tritium), which outweighs their extreme sensitivity and ease of measurement and which it has in common with stable isotopes, is that it does not require radiation protection measures. However, there are also constraints on the use of bromide as a tracer in soil/water/plant systems. Our own studies on different soils using D 2 O, bromide and [ 15 N]-nitrate in lysimeters suggest that the above assumptions on bromide tracers need not always be valid under conditions as they prevail in biologically active soils. As the present paper shows, these studies permit a good assessment of the possibilities and limits to these tracers [de

  18. Crustal tracers in the atmosphere and ocean: Relating their concentrations, fluxes, and ages

    Science.gov (United States)

    Han, Qin

    Crustal tracers are important sources of key limiting nutrients (e.g., iron) in remote ocean regions where they have a large impact on global biogeochemical cycles. However, the atmospheric delivery of bio-available iron to oceans via mineral dust aerosol deposition is poorly constrained. This dissertation aims to improve understanding and model representation of oceanic dust deposition and to provide soluble iron flux maps by testing observations of crustal tracer concentrations and solubilities against predictions from two conceptual solubility models. First, we assemble a database of ocean surface dissolved Al and incorporate Al cycling into the global Biogeochemical Elemental Cycling (BEC) model. The observed Al concentrations show clear basin-scale differences that are useful for constraining dust deposition. The dynamic mixed layer depth and Al residence time in the BEC model significantly improve the simulated dissolved Al field. Some of the remaining model-data discrepancies appear related to the neglect of aerosol size, age, and air mass characteristics in estimating tracer solubility. Next, we develop the Mass-Age Tracking method (MAT) to efficiently and accurately estimate the mass-weighted age of tracers. We apply MAT to four sizes of desert dust aerosol and simulate, for the first time, global distributions of aerosol age in the atmosphere and at deposition. These dust size and age distributions at deposition, together with independent information on air mass acidity, allow us to test two simple yet plausible models for predicting the dissolution of mineral dust iron and aluminum during atmospheric transport. These models represent aerosol solubility as controlled (1) by a diffusive process leaching nutrients from the dust into equilibrium with the liquid water coating or (2) by a process that continually dissolves nutrients in proportion to the particle surface area. The surface-controlled model better captures the spatial pattern of observed

  19. Partitioning and interfacial tracers for differentiating NAPL entrapment configuration: column-scale investigation.

    Science.gov (United States)

    Dai, D; Barranco, F T; Illangasekare, T H

    2001-12-15

    Research on the use of partitioning and interfacial tracers has led to the development of techniques for estimating subsurface NAPL amount and NAPL-water interfacial area. Although these techniques have been utilized with some success at field sites, current application is limited largely to NAPL at residual saturation, such as for the case of post-remediation settings where mobile NAPL has been removed through product recovery. The goal of this study was to fundamentally evaluate partitioning and interfacial tracer behavior in controlled column-scale test cells for a range of entrapment configurations varying in NAPL saturation, with the results serving as a determinant of technique efficacy (and design protocol) for use with complexly distributed NAPLs, possibly at high saturation, in heterogeneous aquifers. Representative end members of the range of entrapment configurations observed under conditions of natural heterogeneity (an occurrence with residual NAPL saturation [discontinuous blobs] and an occurrence with high NAPL saturation [continuous free-phase LNAPL lens]) were evaluated. Study results indicated accurate prediction (using measured tracer retardation and equilibrium-based computational techniques) of NAPL amount and NAPL-water interfacial area for the case of residual NAPL saturation. For the high-saturation LNAPL lens, results indicated that NAPL-water interfacial area, but not NAPL amount (underpredicted by 35%), can be reasonably determined using conventional computation techniques. Underprediction of NAPL amount lead to an erroneous prediction of NAPL distribution, as indicated by the NAPL morphology index. In light of these results, careful consideration should be given to technique design and critical assumptions before applying equilibrium-based partitioning tracer methodology to settings where NAPLs are complexly entrapped, such as in naturally heterogeneous subsurface formations.

  20. Tracer diffusion in compacted, water-saturated bentonite

    International Nuclear Information System (INIS)

    Bourg, Ian C.; Sposito, Garrison; Bourg, Alain C.M.

    2005-01-01

    Compacted Na-bentonite clay barriers, widely used in the isolation of solid-waste landfills and other contaminated sites, have been proposed for a similar use in the disposal of high-level radioactive waste. Molecular diffusion through the pore space in these barriers plays a key role in their performance, thus motivating recent measurements of the apparent diffusion coefficient tensor of water tracers in compacted, water-saturated Na-bentonites. In the present study, we introduce a conceptual model in which the pore space of water-saturated bentonite is divided into 'macropore' and 'interlayer nanopore' compartments. With this model we determine quantitatively the relative contributions of pore-network geometry (expressed as a geometric factor) and of the diffusive behavior of water molecules near montmorillonite basal surfaces(expressed as a contrastivity factor) to the apparent diffusion coefficient tensor. Our model predicts, in agreement with experiment, that the mean principal value of the apparent diffusion coefficient tensor follows a single relationship when plotted against the partial montmorillonite dry density (mass of montmorillonite per combined volume of montmorillonite and pore space). Using a single fitted parameter, the mean principal geometric factor, our model successfully describes this relationship for a broad range of bentonite-water system, from dilute gel to highly-compacted bentonite with 80 percent of its pore water in interlayer nanopores

  1. The European Tracer Experiment - experimental results and database

    International Nuclear Information System (INIS)

    Nodop, K.; Connolly, R.; Girardi, F.

    1997-01-01

    As part of the European Tracer Experiment (ETEX) two successful atmospheric experiments were carried out in October and November, 1994. Perfluorocarbon (PFC) tracers were released into the atmosphere in Monterfil, Brittany, and air samples were taken at 168 stations in 17 European countries for 72 hours after the release. Upper air tracer measurements were made from three aircraft. During the first experiment a westerly air flow transported the tracer plume north-eastwards across Europe. During the second release the flow was eastwards. The results from the ground sampling network allowed the determination of the cloud evolution as far as Sweden, Poland and Bulgaria. Typical background concentrations of the tracer used are around 5 to 7 fl/l in ambient air. Concentrations in the plume ranged from 10 to above 200 fl/l. The tracer release characteristics, the tracer concentrations at the ground and in upper air, the routine and additional meteorological observations at the ground level and in upper air, trajectories derived from constant-level balloons and the meteorological input fields for long-range transport (LRT) models are assembled in the ETEX database. The ETEX database is accessible via the Internet

  2. Methods of 15N tracer research in biological systems

    International Nuclear Information System (INIS)

    Hirschberg, K.; Faust, H.

    1985-01-01

    The application of the stable isotope 15 N is of increasing importance in different scientific disciplines, especially in medicine, agriculture, and the biosciences. The close correlation between the growing interest and improvements of analytical procedures resulted in remarkable advances in the 15 N tracer technique. On the basis of the latest results of 15 N tracer research in life sciences and agriculture methods of 15 N tracer research in biological systems are compiled. The 15 N methodology is considered under three headings: Chemical analysis with a description of methods of sample preparation (including different separation and isolation methods for N-containing substances of biological and agricultural origin) and special procedures converting ammonia to molecular nitrogen. Isotopic analysis with a review on the most important methods of isotopic analysis of nitrogen: mass spectrometry (including the GC-MS technique), emission spectrometry, NMR spectroscopy, and other analytical procedures. 15 N-tracer techniques with a consideration of the role of the isotope dilution analysis as well as different labelling techniques and the mathematical interpretation of tracer data (modelling, N turnover experiments). In these chapters also sources of errors in chemical and isotopic analysis, the accuracy of the different methods and its importance on tracer experiments are discussed. Procedures for micro scale 15 N analysis and aspects of 15 N analysis on the level of natural abundance are considered. Furthermore some remarks on isotope effects in 15 N tracer experiments are made. (author)

  3. A Latent Transition Analysis of English Learners with Reading Disabilities: Do Measures of Cognition Add to Predictions of Late Emerging Risk Status?

    Science.gov (United States)

    Swanson, H. Lee

    2017-01-01

    The purpose of this cohort sequential study was to extend previously reported latent transition analyses conducted by Swanson, Kudo, and Guzman-Orth (2016) by determining the role of cognitive measures in identifying English learners (EL) at risk for late emerging reading disabilities (LERD). To this end, EL students (N = 450) in Grades 1, 2, and…

  4. Pressure Dependence of the Liquid-Liquid Phase Transition of Nanopore Water Doped Slightly with Hydroxylamine, and a Phase Behavior Predicted for Pure Water

    Science.gov (United States)

    Nagoe, Atsushi; Iwaki, Shinji; Oguni, Masaharu; Tôzaki, Ken-ichi

    2014-09-01

    Phase transition behaviors of confined pure water and confined water doped with a small amount of hydroxylamine (HA) with a mole fraction of xHA = 0.03 were examined by high-pressure differential thermal analyses at 0.1, 50, 100, and 150 MPa; the average diameters of silica pores used were 2.0 and 2.5 nm. A liquid-liquid phase transition (LLPT) of the confined HA-doped water was clearly observed and its pressurization effect could be evaluated, unlike in the experiments on undoped water. It was found that pressurization causes the transition temperature (Ttrs) to linearly decrease, indicating that the low-temperature phase has a lower density than the high-temperature one. Transition enthalpy (ΔtrsH) decreased steeply with increasing pressure. Considering the linear decrease in Ttrs with increasing pressure, the steep decrease in ΔtrsH indicates that the LLPT effect of the HA-doped water attenuates with pressure. We present a new scenario of the phase behavior concerning the LLPT of pure water based on the analogy from the behavior of slightly HA-doped water, where a liquid-liquid critical point (LLCP) and a coexistence line are located in a negative-pressure regime but not in a positive-pressure one. It is reasonably understood that doping a small amount of HA into water results in negative chemical pressurization and causes the LLPT to occur even at ambient pressure.

  5. The predicted 10.6 keV transition in Fr-221 from the alpha-decay of Ac-225 revealed

    Czech Academy of Sciences Publication Activity Database

    Yakushev, E. A.; Chumin, V. G.; Gorozhankin, VM.; Gromov, KY.; Kovalík, Alojz; Filosofov, D. V.; Norseev, YV.; Yurkova, LV.

    2002-01-01

    Roč. 28, č. 3 (2002), s. 463-467 ISSN 0954-3899 R&D Projects: GA ČR GA202/02/0157 Institutional research plan: CEZ:AV0Z1048901 Keywords : electromagnetic transition * electron conversion * alpha-decay Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.399, year: 2002

  6. Fluorinated tracers for imaging cancer with positron emission tomography

    International Nuclear Information System (INIS)

    Couturier, Olivier; Chatal, Jean-Francois; Luxen, Andre; Vuillez, Jean-Philippe; Rigo, Pierre; Hustinx, Roland

    2004-01-01

    2-[ 18 F]fluoro-2-deoxy-d-glucose (FDG) is currently the only fluorinated tracer used in routine clinical positron emission tomography (PET). Fluorine-18 is considered the ideal radioisotope for PET imaging owing to the low positron energy (0.64 MeV), which not only limits the dose rate to the patient but also results in a relatively short range of emission in tissue, thereby providing high-resolution images. Further, the 110-min physical half-life allows for high-yield radiosynthesis, transport from the production site to the imaging site and imaging protocols that may span hours, which permits dynamic studies and assessment of potentially fairly slow metabolic processes. The synthesis of fluorinated tracers as an alternative to FDG was initially tested using nucleophilic fluorination of the molecule, as performed when radiolabelling with iodine-124 or bromide-76. However, in addition to being long, with multiple steps, this procedure is not recommended for bioactive molecules containing reactive groups such as amine or thiol groups. Radiochemical yields are also often low. More recently, radiosynthesis from prosthetic group precursors, which allows easier radiolabelling of biomolecules, has led to the development of numerous fluorinated tracers. Given the wide availability of 18 F, such tracers may well develop into important routine tracers. This article is a review of the literature concerning fluorinated radiotracers recently developed and under investigation for possible PET imaging in cancer patients. Two groups can be distinguished. The first includes ''generalist'' tracers, i.e. tracers amenable to use in a wide variety of tumours and indications, very similar in this respect to FDG. These are tracers for non-specific cell metabolism, such as protein synthesis, amino acid transport, nucleic acid synthesis or membrane component synthesis. The second group consists of ''specific'' tracers for receptor expression (i.e. oestrogens or somatostatin), cell

  7. A tracer diffusion model derived from microstructure

    International Nuclear Information System (INIS)

    Lehikoinen, Jarmo; Muurinen, Arto; Olin, Markus

    2012-01-01

    Document available in extended abstract form only. Full text of publication follows: Numerous attempts have been made to explain the tracer diffusion of various solutes in compacted clays. These attempts have commonly suffered from an inability to describe the diffusion of uncharged and charged solutes with a single unified model. Here, an internally consistent approach to describing the diffusion of solutes in a heterogeneous porous medium, such as compacted bentonite, in terms of its microstructure is presented. The microstructure is taken to be represented by a succession of unit cells, which consist of two consecutive regions (Do, 1996). In the first region, the diffusion is viewed to occur in two parallel paths: one through microcrystalline units (micropores) and the other through meso-pores between the microcrystalline units. Solutes exiting these two paths are then joined together to continue diffusing through the second, disordered, region, connecting the two adjacent microcrystalline units. Adsorption (incl. co-ion exclusion) is thought to occur in the micropores, whereas meso-pores and the disordered region accommodate free species alone. Co-ions are also assumed to experience transfer resistance into and out of the micropores, which is characterized in the model by a transmission coefficient. Although the model is not new per se, its application to compacted clays has never been attempted before. It is shown that in the limit of strong adsorption, the effective diffusivity is limited from above only by the microstructural parameters of the model porous medium. As intuitive and logical as this result may appear, it has not been proven before. In the limit of vanishing disordered region, the effective diffusivity is no longer explicitly constrained by any of the model parameters. The tortuosity of the diffusion path, i.e. the quotient of the actual diffusion path length in the porous-medium coordinates and the characteristic length of the laboratory frame

  8. Microbial DNA; a possible tracer of groundwater

    Science.gov (United States)

    Sugiyama, Ayumi; Segawa, Takuya; Furuta, Tsuyumi; Nagaosa, Kazuyo; Tsujimura, Maki; Kato, Kenji

    2017-04-01

    chemical materials dissolved in groundwater. Though viral particle was employed as a tracer to chase the movement of groundwater, it doesn't tell the chemical and physical environmental condition where the particle was incorporated into groundwater. Thus, we propose microbial DNA as a new tracer to track the route of groundwater.

  9. Study of hydraulic parameters in leach mining using radioactive tracer

    International Nuclear Information System (INIS)

    Ahmad, M.; Tariq, J.A.; Iqbal, N.; Rafiq, M.

    2002-01-01

    Six radioactive tracer (/sup 131/I) experiments were carried out at in-situ leach mining site to study transit time of injected fluid from the injection wells to the production well along the dip, against the dip, along the diagonals and the strike. It was found that the dip of the host sandstone does not affect the movement of fluid as the same velocity was found along the dip (0.23 m/h) and against the dip (0.22 m/h). Along the diagonals, the breakthrough times for 13.75 m and 16.25 m were 54 hours and 155 hours respectively yielding velocities of 0.26 m/h and 0.1 m/h. The higher velocity is not only due to shorter distance but also due to higher porosity / injection rate. Along the strike, the breakthrough time was 29 hours (very short) for 9.25 m distance and 147 hours for 16.25 m distance. The unexpectedly high velocity along the strike for shorter distance was also due to higher injection rate in the well as the other well was accepting only small fraction of the total injection. At higher injection/production rate or higher hydraulic gradient, the breakthrough time is shorter and also the dispersion of fluid is less, consequently the leach area would be relatively small. Fluctuations of activity in some cases show the presence of fractures/cracks at certain places in the strata. The estimated porosity and hydraulic conductivity of the aquifer are 28% and 1.23 x 10-5 m/s respectively. (author)

  10. Contamination Tracer Testing With Seabed Rock Drills: IODP Expedition 357

    Science.gov (United States)

    Orcutt, B.; Bergenthal, M.; Freudenthal, T.; Smith, D. J.; Lilley, M. D.; Schneiders, L.; Fruh-Green, G. L.

    2016-12-01

    IODP Expedition 357 utilized seabed rock drills for the first time in the history of the ocean drilling program, with the aim of collecting intact core of shallow mantle sequences from the Atlantis Massif to examine serpentinization processes and the deep biosphere. This new drilling approach required the development of a new system for delivering synthetic tracers during drilling to assess for possible sample contamination. Here, we describe this new tracer delivery system, assess the performance of the system during the expedition, provide an overview of the quality of the core samples collected for deep biosphere investigations based on tracer concentrations, and make recommendations for future applications of the system.

  11. Contamination tracer testing with seabed drills: IODP Expedition 357

    Science.gov (United States)

    Orcutt, Beth N.; Bergenthal, Markus; Freudenthal, Tim; Smith, David; Lilley, Marvin D.; Schnieders, Luzie; Green, Sophie; Früh-Green, Gretchen L.

    2017-11-01

    IODP Expedition 357 utilized seabed drills for the first time in the history of the ocean drilling program, with the aim of collecting intact sequences of shallow mantle core from the Atlantis Massif to examine serpentinization processes and the deep biosphere. This novel drilling approach required the development of a new remote seafloor system for delivering synthetic tracers during drilling to assess for possible sample contamination. Here, we describe this new tracer delivery system, assess the performance of the system during the expedition, provide an overview of the quality of the core samples collected for deep biosphere investigations based on tracer concentrations, and make recommendations for future applications of the system.

  12. Supporting Transition

    Science.gov (United States)

    Qureshi, Asima; Petrucco, James

    2018-01-01

    Meadowbrook Primary School has explored the use of The Teacher Assessment in Primary Science (TAPS) to support transition, initially for transfer to secondary school and now for transition from Early Years Foundation Stage (EYFS) into Key Stage 1 (ages 5-7). This article will consider an example of a secondary transition project and discuss the…

  13. Positron emitting tracers for studies of cocaine

    International Nuclear Information System (INIS)

    Fowler, J.S.; Gatley, S.J.; MacGregor, R.R.; Wolf, A.P.; Yu, D.W.; Dewey, S.L.; Schlyer, D.J.; Volkow, N.D.; Bendriem, B.; Logan, J.

    1990-01-01

    The use of PET to study the behavior and mechanism of action of therapeutic drugs and substances of abuse can be approached from a number of perspectives. The most common approach is to measure the effect of a drug on some aspect of metabolism and requires well characterized radiotracers whose behavior in vivo can be related to a discrete biochemical transformation. A second approach is to study the labeled drug itself. This provides information on the drug's regional distribution and kinetics as well as its pharmacological profile and metabolism. Cocaine has been labeled in different positions with carbon-11 and with fluorine-18 and the stereoisomers of cocaine have also been labeled to characterize its binding and metabolism in human and baboon brain. Regional cocaine binding as measured by PET is consistent with reversible binding to striatal dopamine reuptake sites and its time course parallels the behavioral activation of cocaine. The behaviorally inactive enantiomer (+)-cocaine is rapidly metabolized in serum preventing its entry into the brain. These PET tracers are useful in understanding the neurochemical basis of cocaine's action

  14. National Biomedical Tracer Facility: Project definition study

    International Nuclear Information System (INIS)

    Heaton, R.; Peterson, E.; Smith, P.

    1995-01-01

    The Los Alamos National Laboratory is an ideal institution and New Mexico is an ideal location for siting the National Biomedical Tracer Facility (NBTF). The essence of the Los Alamos proposal is the development of two complementary irradiation facilities that combined with our existing radiochemical processing hot cell facilities and waste handling and disposal facilities provide a low cost alternative to other proposals that seek to satisfy the objectives of the NBTF. We propose the construction of a 30 MeV cyclotron facility at the site of the radiochemical facilities, and the construction of a 100 MeV target station at LAMPF to satisfy the requirements and objectives of the NBTF. We do not require any modifications to our existing radiochemical processing hot cell facilities or our waste treatment and disposal facilities to accomplish the objectives of the NBTF. The total capital cost for the facility defined by the project definition study is $15.2 M. This cost estimate includes $9.9 M for the cyclotron and associated facility, $2.0 M for the 100 MeV target station at LAMPF, and $3.3 M for design

  15. Isotope and chemical tracers in groundwater hydrology

    International Nuclear Information System (INIS)

    Kendall, C.; Stewart, M.K.; Morgenstern, U.; Trompetter, V.

    1999-01-01

    The course sessions cover: session 1, Fundamentals of stable and radioactive isotopes; session 2, Stable oxygen and hydrogen isotopes in hydrology: background, examples, sampling strategy; session 3, Catchment studies using oxygen and hydrogen isotopes: background - the hydrologic water balance, evapotranspiration - the lion's share, runoff generation - new water/old water fractions, groundwater recharge - the crumbs; session 4, Isotopes in catchment hydrology: survey of applications, future developments; session 5, Applications of tritium in hydrology: background and measurement, interpretation, examples; session 6, Case studies using mixing models: Hutt Valley groundwater system, an extended mixing model for simulating tracer transport in the unsaturated zone; session 7, Groundwater dating using CFC concentrations: background, sampling and measurement, use and applications; session 8, Groundwater dating with carbon-14: background, sampling and measurement, use and applications; session 9, NZ case studies: Tauranga warm springs, North Canterbury Plains groundwater; session 10, Stable carbon and nitrogen isotopes: background and examples, biological applications of C-N-S isotopes; session 11, New developments in isotope hydrology: gas isotopes, compound specific applications, age dating of sediments etc; session 12, NZ case studies: North Canterbury Plains groundwater (continued), Waimea Plains groundwater. (author). refs., figs

  16. National Biomedical Tracer Facility: Project definition study

    Energy Technology Data Exchange (ETDEWEB)

    Heaton, R.; Peterson, E. [Los Alamos National Lab., NM (United States); Smith, P. [Smith (P.A.) Concepts and Designs (United States)

    1995-05-31

    The Los Alamos National Laboratory is an ideal institution and New Mexico is an ideal location for siting the National Biomedical Tracer Facility (NBTF). The essence of the Los Alamos proposal is the development of two complementary irradiation facilities that combined with our existing radiochemical processing hot cell facilities and waste handling and disposal facilities provide a low cost alternative to other proposals that seek to satisfy the objectives of the NBTF. We propose the construction of a 30 MeV cyclotron facility at the site of the radiochemical facilities, and the construction of a 100 MeV target station at LAMPF to satisfy the requirements and objectives of the NBTF. We do not require any modifications to our existing radiochemical processing hot cell facilities or our waste treatment and disposal facilities to accomplish the objectives of the NBTF. The total capital cost for the facility defined by the project definition study is $15.2 M. This cost estimate includes $9.9 M for the cyclotron and associated facility, $2.0 M for the 100 MeV target station at LAMPF, and $3.3 M for design.

  17. Chemical and pharmacological aspects of cerebral tracers

    International Nuclear Information System (INIS)

    Rapin, J.R.; Duterte, D.; Le Poncin-Lafitte, M.; Coornaert, S.; Desplanches, G.; Bardy, A.; Askienazy, S.; Moretti, J.L.; Raynaud, C.

    1983-01-01

    Among the iodophenylalkylamines studied and labelled with iodine 125 or iodine 123, N-isopropyl-iodo-amphetamin (IAMP) was selected and proposed as tracer for blood flow, a ''chemical embolus'' having almost 100% extraction in the brain. A new way of obtaining N-isopropyl-p-iodo-amphetamin is proposed and the easily-applied exchange reaction with iodine 125 or 123 gives a product with a radiochemical purity of more than 96% and an unexchanged radioactive iodine content of less than 1%. The pharmacokinetic study of this product in the Wistar rat showed distribution in three compartments and the appearance of a steady state by the fourth minute. The target organes are the lungs, liver and brain. The latter receives 3% of the radioactivity and the autoradiographic study shows that the early distribution in the brain for IAMP closely equal the blood flow as found by a diffusible indicator. In the first hour, the redistribution is very low and at this time although IAMP is proposed for the study of regional blood flow, it does not exactly determine the flow but allows the cell activity [fr

  18. Chemical and pharmacological aspects of cerebral tracers

    International Nuclear Information System (INIS)

    Rapin, J.R.; Duterte, D.; Le Poncin-Lafitte, M.; Coornaert, S.; Desplanches, G.; Bardy, A.; Moretti, J.L.; Raynaud, C.

    1983-01-01

    Among the iodophenylalkylamines studied and labelled with iodine 125 or iodine 123, N-isopropyl-iodo-amphetamin (IAMP) was selected and proposed as tracer for blood flow, a ''chemical embolus'' having almost 100% extraction in the brain. A new way of obtaining N-isopropyl-p-iodo-amphetamin is proposed and the easily-applied exchange reaction with iodine 125 or 123 gives product with a radiochemical purity of more than 96% and an unexchanged radioactive iodine content of less than 1%. The pharmacokinetic study of this product in the Wistar rat showed distribution in three compartments and the appearance of a steady state by the fourth minute. The target organs are the lungs, liver and brain. The latter receives 3% of the radioactivity and the autoradiographic study shows that the early distribution in the brain for IAMP closely equals the blood flow as found by a diffusible indicator. In the first hour, the redistribution is very low and at this time although IAMP is proposed for the study of regional blood flow, it does not exactly determine the flow but rather mirrors cell activity [fr

  19. Studies of radioisotope tracer technique and its applications to pesticide sciences in China

    International Nuclear Information System (INIS)

    Jia Minghong; Chen Qing; Zheng Ran

    1996-05-01

    The improper use of chemical pesticides has resulted in serious environmental problems and food pollutions, affecting the ecosystem balance and human being health. There are more and more scientists and research institutions being engaged in the area of radioisotope tracer techniques for pesticide sciences in China. So far, more than 80 labeled compounds, including insecticides, fungicides, acaricides, herbicides, metabolic intermediates, fertilizer and biological agents, etc. have been synthesized at the laboratory for application of isotopes in Institute for Application of Atomic Energy, Chinese Academy of Agricultural Sciences. Over past several years, the great achievements have been made in the researches of radioisotope tracer techniques and their applications to pesticide sciences in China, especially in the researches for isotopic labeling, residues, degradation and metabolism of pesticides in plant and animal, behavior and fate of pesticides in environment, and techniques for safe application of pesticide, and so on. The researches of radioisotope tracer techniques and their applications to pesticide sciences in China in the past years are briefly introduced. Some problems are put forward and the development in future is predicted. (1 tab.)

  20. Choice of infusion-sampling mode for tracer studies of free fatty acid metabolism

    International Nuclear Information System (INIS)

    Jensen, M.D.; Rogers, P.J.; Ellman, M.G.; Miles, J.M.

    1988-01-01

    To determine the preferred infusion-sampling mode for isotopic studies of free fatty acid (FFA) metabolism, tracer [( 14 C]palmitate) was infused into the left ventricle of five anesthetized dogs, and tracee ([ 3 H]palmitate) was infused into three separate peripheral veins of each dog. The [ 14 C]palmitate specific activity (SA) was lower in mixed venous than arterial blood, and [ 3 H]palmitate SA was equal in both sites. The actual infusion rate of [ 3 H]palmitate [2.15 +/- 0.31 X 10(5) disintegrations/min (dpm).kg-1.min-1] could be accurately predicted (2.14 +/- 0.32 X 10(5) dpm.kg-1.min-1) using the known [ 14 C]palmitate infusion rate and the arterial plasma [ 14 C]-to-[ 3 H]palmitate ratio. In contrast, the mixed venous [ 14 C]-to-[ 3 H]palmitate ratio resulted in overestimates (P less than 0.05) of the actual [ 3 H]palmitate infusion rate. In summary, venous tracer infusion with arterial blood sampling for FFA tracer studies provides the most accurate estimates of tracee rate of appearance

  1. Diffusion coefficients of tracers in glassy polymer systems prepared by gamma radiolysis

    International Nuclear Information System (INIS)

    Tonge, M.P.; Gilbert, R.G.

    1996-01-01

    Diffusion-controlled reactions are common in free radical polymerisation reactions, especially in glassy polymer matrices. Such reactions commonly have an important influence on the polymerisation process and final polymer properties. For example, the dominant growth-stopping event (bimolecular termination) is generally diffusion-controlled. In glassy polymer systems, where molecular mobility is very low, the chain growth mechanism (propagation) may become diffusion-controlled. At present, the mechanism for propagation in glassy polymers is poorly understood, but it is expected by the Smoluchowski expression applied to propagation to depend strongly on the diffusion coefficient of monomer. The objective of this study is to measure reliable diffusion coefficients of small tracer molecules in glassy polymers, and compare these with propagation rate coefficients in similar systems, by the prediction above. Samples were initially prepared in a sealed sampled cell containing monomer, inert diluent, and tracer dye. After irradiation for several days, complete conversion of monomer to polymer can be obtained. The diffusion coefficients for two tracer dyes have been measured as a function of weight fraction polymer glassy poly(methyl methacrylate) samples

  2. A Systematic Method For Tracer Test Analysis: An Example Using Beowawe Tracer Data

    Energy Technology Data Exchange (ETDEWEB)

    G. Michael Shook

    2005-01-01

    Quantitative analysis of tracer data using moment analysis requires a strict adherence to a set of rules which include data normalization, correction for thermal decay, deconvolution, extrapolation, and integration. If done correctly, the method yields specific information on swept pore volume, flow geometry and fluid velocity, and an understanding of the nature of reservoir boundaries. All calculations required for the interpretation can be done in a spreadsheet. The steps required for moment analysis are reviewed in this paper. Data taken from the literature is used in an example calculation.

  3. Quantitative Analysis of Karst Conduit Structure Parameters and Hydraulic Parameters Based on Tracer Test

    Science.gov (United States)

    Qiang, Z.; Zhiqiang, Z.; Xu, M.; Jinyu, S.; Jihong, Q.

    2017-12-01

    The Old Town of Lijiang is famous as the world cultural heritage since 1997, while characterized by its ancient buildings and natural scenery, water is the soul of the town. Around Heilongtan Springs, there are a large quantity of springs at the Old Town of Lijiang , which is an important part of the World Cultural Heritage. Heilongtan Springs is 2420m above the sea level, the annual variation of the flow rate varies greatly (0 8042 x 104 m3 / year). Recharge area Jiuzihai depressions is 6km long, 3km wide and 2800m above sea level, as main karst water recharge area karst funnel and the sink hole are developing on this planation surface, in the research area medium to thick layers of limestone made up Beiya formation (T2b) of Triassic system distributed widely, karst is strongly developed and the fissure caves water occurrence. In order to exploring the application of tracer test in karst hydrogeology, a tracer test was conducted from Jiuzihai depressions to Ganze Spring. Based on the hydrogeological conditions in the study area, tracer test was used for analysis of groundwater connectivity and flow field characteristics, quantitative analysis of Tracer Breakthrough Curves (BTC) with code Qtracer2. The results demonstated that there are hydraulic connection between Jiuzihai depressions with Ganze Spring, and there are other karst conduits in this area. The longitudinal dispersivity coefficient is 0.24 m2/s, longitudinal dispersivity is 12.06m, flow-channel volume is 3.08×104 m3, flow-channel surface area is 3.27×107m2, mean diameter is 1.42m, Reynolds number is 25187, Froude number is 0.0061, respectively. The groundwater in this area is in a slow turbulent state. The results are of great significance to understand the law of groundwater migration, establish groundwater quality prediction model and exploit karst water resources effectively.

  4. Modelling the transport and decay processes of microbial tracers in a macro-tidal estuary.

    Science.gov (United States)

    Abu-Bakar, Amyrhul; Ahmadian, Reza; Falconer, Roger A

    2017-10-15

    The Loughor Estuary is a macro-tidal coastal basin, located along the Bristol Channel, in the South West of the U.K. The maximum spring tidal range in the estuary is up to 7.5 m, near Burry Port Harbour. This estuarine region can experience severe coastal flooding during high spring tides, including extreme flooding of the intertidal saltmarshes at Llanrhidian, as well as the lower industrial and residential areas at Llanelli and Gowerton. The water quality of this estuarine basin needs to comply with the designated standards for safe recreational bathing and shellfish harvesting industries. The waterbody however, potentially receives overloading of bacterial inputs that enter the estuarine system from both point and diffuse sources. Therefore, a microbial tracer study was carried out to get a better understanding of the faecal bacteria sources and to enable a hydro-environmental model to be refined and calibrated for both advection and dispersion transport. A two-dimensional hydro-environmental model has been refined and extended to predict the highest water level covering the intertidal floodplains of the Loughor Estuary. The validated hydrodynamic model for both water levels and currents, was included with the injected mass of microbial tracer, i.e. MS2 coliphage from upstream of the estuary, and modelled as a non-conservative tracer over several tidal cycles through the system. The calibration and validation of the transport and decay of microbial tracer was undertaken, by comparing the model results and the measured data at two different sampling locations. The refined model developed as a part of this study, was used to acquire a better understanding of the water quality processes and the potential sources of bacterial pollution in the estuary. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Hydraulic and tracer experiments in the TVO research tunnel 1993- 1994

    International Nuclear Information System (INIS)

    Hautojaervi, A.; Ilvonen, M.; Vieno, T.; Viitanen, P.

    1995-04-01

    Three full-size deposition holes (diameter 1.5 m, depth 7.5 m) for spent fuel canisters in a KBS-3 type repository have been bored with a new fullface boring method in the TVO Research Tunnel. The Research Tunnel lies in the crystalline bedrock at the depth of 60 metres in the VLJ Repository for low and medium level waste. The holes are 6 metres apart. The boring tests were accompanied by comprehensive pre- and post-characterization of the rock and the bored wells. The inflow rates of groundwater in two of the three full-size holes are 6 and 20 litres/hour. The well in the middle is almost dry as expected on the basis of the pre-characterization. In the tracer tests two different tracers, a dye and a radioactive tracer, were used at the same time. The comprehensive data analysis performed showed that novel techniques (e.g. Extreme Value Estimation, EVE) can be successfully applied to determine the impulse response from the experimental results even in cases where the measured signals are disturbed. Hydraulic and tracer tests as well as visual inspection of the inflow gave clear indications of flow and transport in sparse and narrow channels. Transport velocities could be predicted with a reasonable accuracy by using a simple concept of fracture cavities determining the transport time and 'bottlenecks' causing the hydraulic resistance. The observed non-Fickian dispersion is thought to be caused by velocity differences over the channel width or by diffusion into stagnant pools in the fracture filling. (orig.) (36 refs., 67 figs., 1 tab.)

  6. Chemical and Isotopic Tracers of Groundwater Sustainability: an Overview of New Science Directions

    Science.gov (United States)

    Bullen, T.

    2002-12-01

    Groundwater sustainability is an emerging concept that is rapidly gaining attention from both scientists and water resource managers, particularly with regard to contamination and degradation of water quality in strategic aquifers. The sustainability of a groundwater resource is a complex function of its susceptibility to factors such as intrusion of poor-quality water from diverse sources, lack of sufficient recharge and reorganization of groundwater flowpaths in response to excessive abstraction. In theory the critical limit occurs when degradation becomes irreversible, such that remediative efforts may be fruitless on a reasonable human time scale. Chemical and isotopic tracers are proving to be especially useful tools for assessment of groundwater sustainability issues such as characterization of recharge, identification of potential sources, pathways and impacts of contaminants and prediction of how hydrology will change in response to excessive abstraction. A variety of relatively cost-efficient tracers are now available with which to assess the susceptibility of groundwater reserves to contamination from both natural and anthropogenic sources, and may provide valuable monitoring and regulatory tools for water resource managers. In this overview, the results of several ongoing groundwater studies by the U.S. Geological Survey will be discussed from the perspective of implications for new science directions for groundwater sustainability research that can benefit water policy development. A fundamental concept is that chemical and isotopic tracers used individually often provide ambiguous information, and are most effective when used in a rigorous "multi-tracer" context that considers the complex linkages between the hydrology, geology and biology of groundwater systems.

  7. Our experience of blood flow measurements using radioactive tracers

    International Nuclear Information System (INIS)

    Danet, Bernard.

    1974-01-01

    A critical study of blood flow measuring methods is proposed. After a review of the various diffusible and non-diffusible radioactive tracers and the corresponding detector systems, the principles which allow to measure blood flow from the data so obtained, are studied. There is a different principle of flow measurement for each type of tracer. The theory of flow measurement using non-diffusible tracers (human serum albumin labelled with 131 I or sup(99m)Tc, 113 In-labelled siderophiline) and its application to cardiac flow measurement are described first. Then the theory of flow measurement using diffusible tracers ( 133 Xe, 85 Kr) and its application to measurement of blood flow through tissues (muscles and kidney particularly) are described. A personal experience of this various flow measurements is reported. The results obtained, the difficulties encountered and the improvments proposed are developed [fr

  8. Diffusing passive tracers in random incompressible flows: Statistical topography aspects

    International Nuclear Information System (INIS)

    Klyatskin, V.I.; Woyczynski, W.A.; Gurarie, D.

    1996-01-01

    The paper studies statistical characteristics of the passive tracer concentrations and of its spatial gradient, in random incompressible velocity fields from the viewpoint of statistical topography. The statistics of interest include mean values, probability distributions, as well as various functionals characterizing topographic features of tracers. The functional approach is used. We consider the influence of the mean flow (the linear shear flow) and the molecular diffusion coefficient on the statistics of the tracer. Most of our analysis is carried out in the framework of the delta-correlated (in time) approximation and conditions for its applicability are established. But we also consider the diffusion approximation scheme for finite correlation radius. The latter is applied to a diffusing passive tracer that undergoes sedimentation in a random velocity field

  9. Application of fluorescent-and radioactive tracers in Sedimentalogy

    International Nuclear Information System (INIS)

    Alencar, L.M.L. de.

    1981-01-01

    The development of techniques of sediment labelling, creating the possibility of using fluorescent and radioactive tracers not yet applied in Brazil, in the area of sedimentology, is studied. (A.R.H.) [pt

  10. Simulation of Tracer Transport in Porous Media: Application to Bentonites

    International Nuclear Information System (INIS)

    Bru, A.; Casero, D.

    2001-01-01

    We present a formal framework to describe tracer transport in heterogeneous media, such as porous media like bentonites. In these media, mean field approximation is not valid because there exist some geometrical constraints and the transport is anomalous. (Author)

  11. Chlorine isotopes potential as geo-chemical tracers

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Pradhan, U.K.; Banerjee, R.

    The potential of chlorine isotopes as tracers of geo-chemical processes of earth and the oceans is highlighted based on systematic studies carried out in understanding the chlorine isotope fractionation mechanism, its constancy in seawater and its...

  12. Hydraulic characterisation of karst systems with man-made tracers

    International Nuclear Information System (INIS)

    Werner, A.

    1998-01-01

    Tracer experiments using man-made tracers are common in hydrogeological exploration of groundwater aquifers in karst systems. In the present investigation, a convection-dispersion model (multidispersion model with consideration of several flow paths) and a single-cleft model (consideration of the diffusion between the cleft and the surrounding rock matrix) were used for evaluating tracer experiments in the main hydrological system of the saturated zone of karst systems. In addition to these extended analytical solutions, a numerical transport model was developed for investigating the influence of the transient flow rate on the flow and transport parameters. Comparative evaluations of the model approaches for the evaluation of tracer experiments were made in four different karst systems: Danube-Aach, Paderborn, Slowenia and Lurbach, of which the Danube-Aach system was considered as the most important. The investigation also comprised three supplementary experiments in order to enable a complete hydraulic characterisation of the system. (orig./SR) [de

  13. Results of repeat tracer tests at Ohaaki, NZ

    International Nuclear Information System (INIS)

    McCabe, W.J.; Morris, C.

    1995-01-01

    During 20 years of tracer testing at Ohaaki a number of wells have been used more than once as tracer injection sites. In studying the various responses obtained it has been necessary to consider variations in the experimental test conditions before making comparisons which relate to field conditions. Some very significant changes have occurred in the field hydrology in recent years and water flow speeds as high as those encountered at Wairakei have been demonstrated. (author). 4 refs., 2 tabs., 10 figs

  14. Evaporation rate in containers used for storing radioactive tracer solutions

    International Nuclear Information System (INIS)

    Gascon, J.L.

    2002-01-01

    In radiochemical analysis, the storage of a tracer solution is an important issue to bear in mind. The evaporation of the tracer solution depends on the type of container used for storing. Evaporation rate in four kinds of containers, i.e., flame-sealed glass ampoule, sealed glass flask, flame-sealed polyethylene ampoule and screw glass vial was studied. It is concluded that the evaporation rate depends on the system of closing. (author)

  15. Labeling of fruitflies and their identification by tracer activation

    International Nuclear Information System (INIS)

    Haisch, A.; Forster, S.; Staerk, H.

    1975-01-01

    A technique was worked out to label and identify cherry fruit flies (Rhagoletic cerasi L.) in large numbers. For that purpose, the tracers dysprosium and samarium were mingled with a carrier substance (silica gel) which, mixed with silica sand, formed the substrate for emergence. The flies, the pupae of which were in this substrate, took up with their ptilinum-labeled silica gel during their crawling through the sand up to the surface. The tracer was detected after its activation by neutron irradiation

  16. Use of tracers for locating and designing sea outfalls

    International Nuclear Information System (INIS)

    Gauthier, M.; Quetin, B.

    1976-01-01

    Various tracers are used for investigating the propagation of substances in solution or suspension (radioactive, biological, chemical substances and floats). Floats and dyes are the most employed. The main problems associated with the use of such tracers and data interpretation are discussed and it is shown how effective quantitative data can be obtained, especially as regards estimation of turbulent diffusion parameters and identification of suitable dispersion methods for purposes of determining pollutant concentration and areas affected thereby [fr

  17. Lanthanide-based fluorescent tracers in complex media

    International Nuclear Information System (INIS)

    Brichart, Thomas

    2014-01-01

    Tracers are objects allowing the determination of the position or the distribution of a product; tracers are currently used in a great variety of domains. Despite the fact that each field has it's own specifications, it is possible to find tracers in medicine (contrast agents), anti-counterfeiting or geological exploration. We have developed lanthanide complex tracers for oil field injection waters. Those tracers, derived from the DOTA, have been detected at concentration lower than 1 ppb, thanks to a simple and compact apparatus. This detection has been made possible by the use of time-resolved fluorescence spectroscopy, this technique allows us to get rid of the background noise created by the intrinsic fluorescence of oil residues that are present in production waters. We also demonstrated how we can, through a reverse microemulsion synthesis, encapsulate several different dyes inside a single nanoparticle composed of a gold core and a silica shell. We showed as well, how those particles can be used as smart tracers to gather data, such as temperature, pH, solvents, etc. inside the well. Finally the use of lanthanides and scale inhibitors properties allowed us to create a simple and fast dosing protocol of such scale inhibitors in injection waters. This dosage will then allow the quick adjustment of their concentration inside each well. (author) [fr

  18. Determination of the self purification of streams using tracers

    International Nuclear Information System (INIS)

    Salviano, J.S.

    1982-04-01

    A methodology for the 'in situ' evaluation of the self purification of streams is discussed. It consists of the simultaneous injection of two tracers into the stream. One of the tracers is oxidized by biochemical processes. It can be either artificially supplied to the stream or a naturally present component can be used. This tracer is used for the determination of the self purification parameters. The other tracer is conservative and allows for the hydrodynamic effects. Tests have been carried out in two streams with quite different hydrodynamic and physicochemical conditions. In the first stream, with a flow-rate of about 0.9 m 3 /s, urea was used as the nonconservative tracer. In the other stream, which had a flow-rate of about 5 m 3 /s, only a radioactive tracer has been used, and the rate of biochemical oxidation has been determined from BOD measurements. Calculations have been implemented on a digital computer. In both cases it was found that the reoxygenation rate is more conveniently determined by empirical formulas. Results from both tests have been deemed realistic by comparison with similar experiments. (Author) [pt

  19. Quantifying solute transport processes: are chemically "conservative" tracers electrically conservative?

    Science.gov (United States)

    Singha, Kamini; Li, Li; Day-Lewis, Frederick D.; Regberg, Aaron B.

    2012-01-01

    The concept of a nonreactive or conservative tracer, commonly invoked in investigations of solute transport, requires additional study in the context of electrical geophysical monitoring. Tracers that are commonly considered conservative may undergo reactive processes, such as ion exchange, thus changing the aqueous composition of the system. As a result, the measured electrical conductivity may reflect not only solute transport but also reactive processes. We have evaluated the impacts of ion exchange reactions, rate-limited mass transfer, and surface conduction on quantifying tracer mass, mean arrival time, and temporal variance in laboratory-scale column experiments. Numerical examples showed that (1) ion exchange can lead to resistivity-estimated tracer mass, velocity, and dispersivity that may be inaccurate; (2) mass transfer leads to an overestimate in the mobile tracer mass and an underestimate in velocity when using electrical methods; and (3) surface conductance does not notably affect estimated moments when high-concentration tracers are used, although this phenomenon may be important at low concentrations or in sediments with high and/or spatially variable cation-exchange capacity. In all cases, colocated groundwater concentration measurements are of high importance for interpreting geophysical data with respect to the controlling transport processes of interest.

  20. Tracer verification and monitoring of containment systems (II)

    International Nuclear Information System (INIS)

    Williams, C.V.; Dunn, S.D.; Lowry, W.E.

    1997-01-01

    A tracer verification and monitoring system, SEAtrace trademark, has been designed and field tested which uses gas tracers to evaluate, verify, and monitor the integrity of subsurface barriers. This is accomplished using an automatic, rugged, autonomous monitoring system combined with an inverse optimization code. A gaseous tracer is injected inside the barrier and an array of wells outside the barrier are monitored. When the tracer gas is detected, a global optimization code is used to calculate the leak parameters, including leak size, location, and when the leak began. The multipoint monitoring system operates in real-time, can be used to measure both the tracer gas and soil vapor contaminants, and is capable of unattended operation for long periods of time (months). The global optimization code searches multi-dimensional open-quotes spaceclose quotes to find the best fit for all of the input parameters. These parameters include tracer gas concentration histories from multiple monitoring points, medium properties, barrier location, and the source concentration. SEAtrace trademark does not attempt to model all of the nuances associated with multi-phase, multi-component flow, but rather, the inverse code uses a simplistic forward model which can provide results which are reasonably accurate. The system has calculated leak locations to within 0.5 meters and leak radii to within 0.12 meters

  1. Copper ion as a new leakage tracer.

    Science.gov (United States)

    Modaresi, J; Baharizade, M; Shareghi, A; Ahmadi, M; Daneshkazemi, A

    2013-12-01

    Most failures of root canal treatments are caused by bacteria. Studies showed that the most common cause of endodontic failures were the incomplete obturation of the root canal and the lack of adequate apical seal. Some in-vitro methods are used to estimate sealing quality, generally by measuring microleakage that allows the tracer agent to penetrate the filled canal. Conventional methods of evaluating the seal of endodontically treated teeth are complicated and have some drawbacks. We used copper ion diffusion method to assess the leakage and the results were compared to dye penetration method. The crowns of 21 extracted teeth were cut off at the CEJ level. After preparing the canals, the teeth were placed in tubes containing saline. They were divided randomly into 15 experimental cases; 3 positive and 3 negative controls. Positive controls were filled by single cone without sealer while the experimental and the negative control groups were filled by lateral technique. The coronal portion of gutta was removed and 9mm was left. The external surface of each tooth was coated with nail polish. Two millimeters of apical portion was immersed into 9ml of distilled water and 0.3ml of CuSO4 solution was injected into the coronal portion. After 2 days, copper sulfate was measured by an atomic absorption spectrophotometer. The teeth were then immersed in 2% methylene blue for 24 hours, sectioned and the extent of dye penetration was measured by a stereomicroscope. The maximum and minimum recorded copper ion concentrations for the experimental group were 18.37 and 2.87ppm respectively. The maximum and minimum recorded dye penetrations for the experimental group were 8.5 and 3.5mm respectively. The statistical analysis, adopting paired samples test, showed poor correlation between average recorded results of two methods. Based on our results, there was no significant correlation between the dye penetration and the copper ion diffusion methods.

  2. Tracer verification and monitoring of containment systems

    International Nuclear Information System (INIS)

    Lowry, W.; Dunn, S.D.; Williams, C.

    1996-01-01

    In-situ barrier emplacement techniques and materials for the containment of high-risk contaminants in soils are currently being developed by the Department of Energy (DOE). Because of their relatively high cost, the barriers are intended to be used in cases where the risk is too great to remove the contaminants, the contaminants are too difficult to remove with current technologies, or the potential for movement of the contaminants to the water table is so high that immediate action needs to be taken to reduce health risks. Consequently, barriers are primarily intended for use in high-risk sites where few viable alternatives exist to stop the movement of contaminants in the near term. Assessing the integrity of the barrier once it is emplaced, and during its anticipated life, is a very difficult but necessary requirement. Existing surface-based and borehole geophysical techniques do not provide the degree of resolution required to assure the formation of an integral in-situ barrier. Science and Engineering Associates, Inc., (SEA) and Sandia National Laboratories (SNL) are developing a quantitative subsurface barrier assessment system using gaseous tracers. Called SEAtrace trademark, this system integrates an autonomous, multipoint soil vapor sampling and analysis system with a global optimization modeling methodology to pinpoint leak sources and sizes in real time. SEAtrace trademark is applicable to impermeable barrier emplacements above the water table, providing a conservative assessment of barrier integrity after emplacement, as well as a long term integrity monitoring function. The SEAtrace trademark system is being developed under funding by the DOE-EM Subsurface Contaminant Focus Area

  3. Biogeochemical tracers of the marine cyanobacterium Trichodesmium

    Science.gov (United States)

    Carpenter, Edward J.; Harvey, H. Rodger; Fry, Brian; Capone, Douglas G.

    1997-01-01

    We examined the utility of several biogeochemical tracers for following the fate of the planktonic diazotrophic cyanobacterium Trichodesmium in the sea. The presence of a (CIO) fatty acid previously reported was observed in a culture of Trichodesmium but was not found in natural samples. This cyanobacterium had high concentrations of C 14 and C 16 acids, with lesser amounts of several saturated and unsaturated C 18 fatty acids. This composition was similar to that of other marine cyanobacteria. The major hydrocarbon identified was the C 17n-alkane, which was present in all samples from the five stations examined. Sterols common to algae and copepods were observed in many samples along with hopanoids representative of bacteria, suggesting a varied community structure in colonies collected from different stations. We found no unique taxonomic marker of Trichodesmium among the sterols. Measurements of the σ 15N and σ 13C in Trichodesmium samples from the SW Sargasso and NW Caribbean Seas averaged -0.4960 (range from -0.7 to -0.25960) and -12.9%0 (range from -15.2 to -11.9960), respectively, thus confirming previous observations that this cyanobacterial diazotroph has both the lowest σ 15N and highest σ 13C of any marine phytoplankter observed to date. A culture of Trichodesmium grown under diazotrophic conditions had a σ 15N between -1.3 and -3.6960. Our results support the supposition that the relatively low σ 15N and high σ 13C values observed in suspended and sediment-trapped material from some tropical and subtropical seas result from substantial input of C and N by Trichodesmium.

  4. Determination of diffusion parameters using radioactive tracers, aiming at a project of a submarine sewage outfall

    International Nuclear Information System (INIS)

    Santos, J.L. dos.

    1979-01-01

    Radioactive tracers technology is applied to pollutant dispersion studies in water bodies, for the project of submarine sewage outfall. The models proposed by Hansen/Harremoes and Okubo, respectively, for the prediction of physical dilution rates and determination of turbulent diffusion laws, are discussed. The methodology for field work as well as data processing is described. The results from field investigations carried out in Brazilian litoral waters for submarine release of sewage in Santos - Sao Vicente, Guaruja and Maceio, are presented and commented. (Author) [pt

  5. Improved reservoir characterization from waterflood tracer movement, Northwest Fault Block, Prudhoe Bay, Alaska

    International Nuclear Information System (INIS)

    Nitzberg, K.E.; Broman, W.H.

    1992-01-01

    This paper reports that simulation models of the Prudhoe Bay Northwest Fault Block (NWFB) waterflood project, with core-plug-derived permeabilities, predicted that injected water would slump because of gravity segregation. Detailed analysis of surveillance logs and production data for one pattern identified tritium tracer breakthrough in surrounding producers without significant slumping. To duplicate the nearly horizontal movement of injected water, a k V /k H ratio that is an order of magnitude lower than previously modeled is required. This improved reservoir characterization led to revision of the reservoir management strategy for the NWFB

  6. Transition radiation and transition scattering

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1982-01-01

    Transition radiation is a process of a rather general character. It occurs when some source, which does not have a proper frequency (for example, a charge) moves at a constant velocity in an inhomogeneous and (or) nonstationary medium or near such a medium. The simplest type of transition radiation takes place when a charge crosses a boundary between two media (the role of one of the media may be played by vacuum). In the case of periodic variation of the medium, transition radiation possesses some specific features (resonance transition radiation or transition scattering). Transition scattering occurs, in particular, when a permittivity wave falls onto an nonmoving (fixed) charge. Transition scattering is closely connected with transition bremsstrahlung radiation. All these transition processes are essential for plasma physics. Transition radiation and transition scattering have analogues outside the framework of electrodynamics (like in the case of Vavilov-Cherenkov radiation). In the present report the corresponding range of phenomena is elucidated, as far as possible, in a generally physical aspect. (Auth.)

  7. Determination of regional flow by use of intravascular PET tracers: microvascular theory and experimental validation for pig livers

    DEFF Research Database (Denmark)

    Munk, O L; Bass, L; Feng, H

    2003-01-01

    Today, the standard approach for the kinetic analysis of dynamic PET studies is compartment models, in which the tracer and its metabolites are confined to a few well-mixed compartments. We examine whether the standard model is suitable for modern PET data or whether theories including more...... physiologic realism can advance the interpretation of dynamic PET data. A more detailed microvascular theory is developed for intravascular tracers in single-capillary and multiple-capillary systems. The microvascular models, which account for concentration gradients in capillaries, are validated and compared...... with the standard model in a pig liver study. METHODS: Eight pigs underwent a 5-min dynamic PET study after (15)O-carbon monoxide inhalation. Throughout each experiment, hepatic arterial blood and portal venous blood were sampled, and flow was measured with transit-time flow meters. The hepatic dual...

  8. Development of a screening tool predicting the transition from acute to chronic low back pain for patients in a GP setting: Protocol of a multinational prospective cohort study

    Directory of Open Access Journals (Sweden)

    Bajracharya Suraj

    2008-12-01

    Full Text Available Abstract Background Low back pain (LBP is by far the most prevalent and costly musculoskeletal problem in our society today. Following the recommendations of the Multinational Musculoskeletal Inception Cohort Study (MMICS Statement, our study aims to define outcome assessment tools for patients with acute LBP and the time point at which chronic LBP becomes manifest and to identify patient characteristics which increase the risk of chronicity. Methods Patients with acute LBP will be recruited from clinics of general practitioners (GPs in New Zealand (NZ and Switzerland (CH. They will be assessed by postal survey at baseline and at 3, 6, 12 weeks and 6 months follow-up. Primary outcome will be disability as measured by the Oswestry Disability Index (ODI; key secondary endpoints will be general health as measured by the acute SF-12 and pain as measured on the Visual Analogue Scale (VAS. A subgroup analysis of different assessment instruments and baseline characteristics will be performed using multiple linear regression models. This study aims to examine 1. Which biomedical, psychological, social, and occupational outcome assessment tools are identifiers for the transition from acute to chronic LBP and at which time point this transition becomes manifest 2. Which psychosocial and occupational baseline characteristics like work status and period of work absenteeism influence the course from acute to chronic LBP 3. Differences in outcome assessment tools and baseline characteristics of patients in NZ compared with CH. Discussion This study will develop a screening tool for patients with acute LBP to be used in GP clinics to access the risk of developing chronic LBP. In addition, biomedical, psychological, social, and occupational patient characteristics which influence the course from acute to chronic LBP will be identified. Furthermore, an appropriate time point for follow-ups will be given to detect this transition. The generalizability of our

  9. Sistem Pre Kompilasi Data Tracer Studi Online Ditjen Belmawa Ristekdikti (Studi Kasus: Politeknik Harapan Bersama

    Directory of Open Access Journals (Sweden)

    Very Kurnia Bakti

    2017-01-01

    Full Text Available Tracer studi merupakan salah satu upaya yang diharapkan dapat menyediakan informasi untuk mengevaluasi hasil pendidikan di Politeknik Harapan Bersama dari kuisioner yang diberikan kepada alumni. Kegiatan tracer studi ini sudah dilaksanakan secara online, namun masih terdapat kendala pada bagian sistem yang digunakan saat ini, hal tersebut menyebabkan Politeknik Harapan Bersama tidak dapat melaporkan / mengunggah hasil tracer studi kepada Ditjen Belmawa Ristekdikti, dimana form kuisioner dan data export tracer studi yang dihasilkan berbeda dengan kebutuhan seperti yang tercantum pada surat edaran No. 313/B/SE/2016 tentang pelaksanaan tracer studi di tingkat perguruan tinggi. Mengingat pentingnya tracer studi sebagai umpan balik bagi Politeknik Harapan Bersama, maka perlu solusi untuk mengatasi kekurangan sistem ini. Dengan merubah sistem yang ada dengan sistem tracer studi yang baru merupakan solusi yang tepat dalam permasalahan ini. Sistem tracer studi yang baru mampu menghasilkan data tracer studi alumni dan pengisian form kuisioner sesuai dengan standar Ditjen Belmawa Ristekdikti yang dapat diunggah sistem tracer studi ristekdikti.

  10. I. Photon transition amplitudes predicted by the transformation between current and constituent quarks. II. Saturation of the Drell--Hearn--Gerasimov sum rule

    International Nuclear Information System (INIS)

    Karliner, I.

    1975-01-01

    The SU(6)-W group structure appears in both current algebra and in the spectroscopy of hadrons. Recently, a considerable progress has taken place in relating these two SU(6)-W structures. The consequences of the proposed correspondence, as it applies to real photon transitions, are investigated in this work. The general structure of such transitions is shown, and a set of resulting selection rules is presented for the multipole character of the photon amplitudes. Many specific amplitudes for both mesons and baryons are worked out and their signs and magnitudes are compared with available experimental data. The saturation of the Drell-Hearn-Gerasimov sum rule for the forward spin-flip amplitude of nucleon Compton scattering was investigated. The sum rule saturation was studied using recent analyses of single pion photoproduction in the region up to photon laboratory energies of 1.2 GeV. The original sum rule is decomposed into separate sum rules originating from different isospin compnents of the electromagnetic current. All three sum rules receive important nonresonant as well as resonant contributions. The isovector-isovector sum rule, whose contributions are known best, is found to be nearly saturated, lending support to the assumptions underlying the sum rules. The failure of the isovector-isoscalar sumrule to be saturated is then presumably to be blamed on inadequate data for inelastic contributions. (Diss. Abs,r. Int., B)

  11. Direct prediction of the solute softening-to-hardening transition in W–Re alloys using stochastic simulations of screw dislocation motion

    Science.gov (United States)

    Zhao, Yue; Marian, Jaime

    2018-06-01

    Interactions among dislocations and solute atoms are the basis of several important processes in metal plasticity. In body-centered cubic (bcc) metals and alloys, low-temperature plastic flow is controlled by screw dislocation glide, which is known to take place by the nucleation and sideward relaxation of kink pairs across two consecutive Peierls valleys. In alloys, dislocations and solutes affect each other’s kinetics via long-range stress field coupling and short-range inelastic interactions. It is known that in certain substitutional bcc alloys a transition from solute softening to solute hardening is observed at a critical concentration. In this paper, we develop a kinetic Monte Carlo model of screw dislocation glide and solute diffusion in substitutional W–Re alloys. We find that dislocation kinetics is governed by two competing mechanisms. At low solute concentrations, nucleation is enhanced by the softening of the Peierls stress, which dominates over the elastic repulsion of Re atoms on kinks. This trend is reversed at higher concentrations, resulting in a minimum in the flow stress that is concentration and temperature dependent. This minimum marks the transition from solute softening to hardening, which is found to be in reasonable agreement with experiments.

  12. Phase transitions and quantum entropy

    International Nuclear Information System (INIS)

    Arrachea, L.; Canosa, N.; Plastino, A.; Portesi, M.; Rossignoli, R.

    1990-01-01

    An examination is made of the possibility to predict phase transitions of the fundamental state of finite quantum system, knowing the quantum entropy of these states, defined on the basis of the information theory. (Author). 7 refs., 3 figs

  13. Characterization of a managed aquifer recharge system using multiple tracers.

    Science.gov (United States)

    Moeck, Christian; Radny, Dirk; Popp, Andrea; Brennwald, Matthias; Stoll, Sebastian; Auckenthaler, Adrian; Berg, Michael; Schirmer, Mario

    2017-12-31

    Knowledge about the residence times of artificially infiltrated water into an aquifer and the resulting flow paths is essential to developing groundwater-management schemes. To obtain this knowledge, a variety of tracers can be used to study residence times and gain information about subsurface processes. Although a variety of tracers exists, their interpretation can differ considerably due to subsurface heterogeneity, underlying assumptions, and sampling and analysis limitations. The current study systematically assesses information gained from seven different tracers during a pumping experiment at a site where drinking water is extracted from an aquifer close to contaminated areas and where groundwater is artificially recharged by infiltrating surface water. We demonstrate that the groundwater residence times estimated using dye and heat tracers are comparable when the thermal retardation for the heat tracer is considered. Furthermore, major ions, acesulfame, and stable isotopes (δ 2 H and δ 18 O) show that mixing of infiltrated water and groundwater coming from the regional flow path occurred and a vertical stratification of the flow system exist. Based on the concentration patterns of dissolved gases (He, Ar, Kr, N 2 , and O 2 ) and chlorinated solvents (e.g., tetrachloroethene), three temporal phases are observed in the ratio between infiltrated water and regional groundwater during the pumping experiment. Variability in this ratio is significantly related to changes in the pumping and infiltration rates. During constant pumping rates, more infiltrated water was extracted, which led to a higher dilution of the regional groundwater. An infiltration interruption caused however, the ratio to change and more regional groundwater is extracted, which led to an increase in all concentrations. The obtained results are discussed for each tracer considered and its strengths and limitations are illustrated. Overall, it is demonstrated that aquifer heterogeneity and

  14. Stable isotope tracers and exercise physiology: past, present and future.

    Science.gov (United States)

    Wilkinson, Daniel J; Brook, Matthew S; Smith, Kenneth; Atherton, Philip J

    2017-05-01

    Stable isotope tracers have been invaluable assets in physiological research for over 80 years. The application of substrate-specific stable isotope tracers has permitted exquisite insight into amino acid, fatty-acid and carbohydrate metabolic regulation (i.e. incorporation, flux, and oxidation, in a tissue-specific and whole-body fashion) in health, disease and response to acute and chronic exercise. Yet, despite many breakthroughs, there are limitations to 'substrate-specific' stable isotope tracers, which limit physiological insight, e.g. the need for intravenous infusions and restriction to short-term studies (hours) in controlled laboratory settings. In recent years significant interest has developed in alternative stable isotope tracer techniques that overcome these limitations, in particular deuterium oxide (D 2 O or heavy water). The unique properties of this tracer mean that through oral administration, the turnover and flux through a number of different substrates (muscle proteins, lipids, glucose, DNA (satellite cells)) can be monitored simultaneously and flexibly (hours/weeks/months) without the need for restrictive experimental control. This makes it uniquely suited for the study of 'real world' human exercise physiology (amongst many other applications). Moreover, using D 2 O permits evaluation of turnover of plasma and muscle proteins (e.g. dynamic proteomics) in addition to metabolomics (e.g. fluxomics) to seek molecular underpinnings, e.g. of exercise adaptation. Here, we provide insight into the role of stable isotope tracers, from substrate-specific to novel D 2 O approaches, in facilitating our understanding of metabolism. Further novel potential applications of stable isotope tracers are also discussed in the context of integration with the snowballing field of 'omic' technologies. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  15. Effects from influent boundary conditions on tracer migration and spatial variability features in intermediate-scale experiments

    International Nuclear Information System (INIS)

    Fuentes, H.R.; Polzer, W.L.; Springer, E.P.

    1987-04-01

    In previous unsaturated transport studies at Los Alamos dispersion coefficients were estimated to be higher close to the tracer source than at greater distances from the source. Injection of tracers through discrete influent outlets could have accounted for those higher dispersions. Also, a lack of conservation of mass of the tracers was observed and suspected to be due to spatial variability in transport. In the present study experiments were performed under uniform influent (ponded) conditions in which breakthrough of tracers was monitored at four locations at each of four depths. All other conditions were similar to those of the unsaturated transport experiments. A comparison of results from these two sets of experiments indicates differences in the parameter estimates. Estimates were made for the dispersion coefficient and the retardation factor by the one-dimensional steady flow computer code, CFITIM. Estimates were also made for mass and for velocity and the dispersion coefficient by the method of moments. The dispersion coefficient decreased with depth under discrete influent application and increased with depth under ponded influent application. Retardation was predicted better under the discrete influent application than under ponded influent application. Differences in breakthroughs and in estimated parameters among locations at the same depth were observed under ponded influent application. Those differences indicate that there is a lack of conservation of mass as well as significant spatial variability across the experimental domain. 14 refs., 9 figs., 8 tabs

  16. Green River air quality model development: meteorological and tracer data, July/August 1982 field study in Brush Valley, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Whiteman, C.D.; Lee, R.N.; Orgill, M.M.; Zak, B.D.

    1984-06-01

    Meteorological and atmospheric tracer studies were conducted during a 3-week period in July and August of 1982 in the Brush Creek Valley of northwestern Colorado. The objective of the field experiments was to obtain data to evaluate a model, called VALMET, developed at PNL to predict dispersion of air pollutants released from an elevated stack located within a deep mountain valley in the post-sunrise temperature inversion breakup period. Three tracer experiments were conducted in the valley during the 2-week period. In these experiments, sulfur hexafluoride (SF/sub 6/) was released from a height of approximately 100 m, beginning before sunrise and continuing until the nocturnal down-valley winds reversed several hours after sunrise. Dispersion of the sulfur hexafluoride after release was evaluated by measuring SF/sub 6/ concentrations in ambient air samples taken from sampling devices operated within the valley up to about 8 km down valley from the source. An instrumented research aircraft was also used to measure concentrations in and above the valley. Tracer samples were collected using a network of radio-controlled bag sampling stations, two manually operated gas chromatographs, a continuous SF/sub 6/ monitor, and a vertical SF/sub 6/ profiler. In addition, basic meteorological data were collected during the tracer experiments. Frequent profiles of vertical wind and temperature structure were obtained with tethered balloons operated at the release site and at a site 7.7 km down the valley from the release site. 10 references, 63 figures, 50 tables.

  17. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    DEFF Research Database (Denmark)

    Karup, Dan; Møldrup, Per; Paradelo Pérez, Marcos

    2016-01-01

    tracer mass could be well fitted to an analytical solution to the classical convection-dispersion equation. Both cumulative tracer mass and concentration as a function of time were hereby reasonable well predicted from the simple inputs of bulk density, clay and silt contents, and applied tracer mass......Solute transport through the soil matrix is heterogeneous and greatly affected by soil texture, soil structure, and macropore networks. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. Hundred...... of the soil structure rather than the actual formation of macropores causing preferential flow. The arrival times of 5 % and up to 50 % of the tracer mass were found to be strongly correlated with volumetric fines content. The hereby predicted tracer concentration breakthrough points up to 50% of applied...

  18. Busted Butte Phase 2: Introduction and Analytical Modeling of Nonreactive Tracer and Lithium Breakthrough

    International Nuclear Information System (INIS)

    Turin, H.J.; Soll, W.E.

    2002-01-01

    The Busted Butte Unsaturated-Zone Transport Test Facility is located approximately 8 km southeast of Yucca Mountain, and was designed to address uncertainties associated with flow and transport in the UZ site-process models for Yucca Mountain. Busted Butte Phase 2 consisted of a 10m x 10m x 7m test block. From July 1988 through October 2000, complex tracer mixtures were injected continuously at 77 discrete points located along eight parallel 10-m boreholes arranged in two horizontal planes. In August 1999, iodide was added to the tracer mixture to explore the effects of initial hydraulic transients. During the course of the experiment, porewater samples were collected at regular intervals using sorbing-paper collection pads, emplaced into fifteen horizontal and inclined 10-m collection boreholes, oriented perpendicular to the injection boreholes. Potential travel distances ranged from 20 cm to over 500 cm. Nonreactive tracer and weakly sorbing lithium breakthrough was observed at most of the collection points during the injection period. Following termination of injection, approximately 800 rock samples were collected using overcore and mineback techniques, and analyzed for tracer concentration. Rock analyses are discussed in a subsequent paper. To complement complex 3-dimensional finite-element modeling of the entire block, bromide, iodide, and lithium breakthrough onto the collection pads has been modeled with CXTFIT. This simple 1-dimensional analytical code uses a non-linear curve-fitting routine to estimate transport parameters including apparent velocity, dispersivity, and field retardation factors. Preliminary results show that: (1) Bromide and iodide behaved similarly, despite the fact that bromide was injected in a strongly transient flow field, while iodide injection began after flow had approached steady state conditions. (2) With the exception of the closest collection points, tracer velocities remained relatively constant, indicating that transport was

  19. TracerLPM (Version 1): An Excel® workbook for interpreting groundwater age distributions from environmental tracer data

    Science.gov (United States)

    Jurgens, Bryant C.; Böhlke, J.K.; Eberts, Sandra M.

    2012-01-01

    TracerLPM is an interactive Excel® (2007 or later) workbook program for evaluating groundwater age distributions from environmental tracer data by using lumped parameter models (LPMs). Lumped parameter models are mathematical models of transport based on simplified aquifer geometry and flow configurations that account for effects of hydrodynamic dispersion or mixing within the aquifer, well bore, or discharge area. Five primary LPMs are included in the workbook: piston-flow model (PFM), exponential mixing model (EMM), exponential piston-flow model (EPM), partial exponential model (PEM), and dispersion model (DM). Binary mixing models (BMM) can be created by combining primary LPMs in various combinations. Travel time through the unsaturated zone can be included as an additional parameter. TracerLPM also allows users to enter age distributions determined from other methods, such as particle tracking results from numerical groundwater-flow models or from other LPMs not included in this program. Tracers of both young groundwater (anthropogenic atmospheric gases and isotopic substances indicating post-1940s recharge) and much older groundwater (carbon-14 and helium-4) can be interpreted simultaneously so that estimates of the groundwater age distribution for samples with a wide range of ages can be constrained. TracerLPM is organized to permit a comprehensive interpretive approach consisting of hydrogeologic conceptualization, visual examination of data and models, and best-fit parameter estimation. Groundwater age distributions can be evaluated by comparing measured and modeled tracer concentrations in two ways: (1) multiple tracers analyzed simultaneously can be evaluated against each other for concordance with modeled concentrations (tracer-tracer application) or (2) tracer time-series data can be evaluated for concordance with modeled trends (tracer-time application). Groundwater-age estimates can also be obtained for samples with a single tracer measurement at one

  20. Do reciprocal relationships between academic workload and self-regulated learning predict medical freshmen's achievement? A longitudinal study on the educational transition from secondary school to medical school.

    Science.gov (United States)

    Barbosa, Joselina; Silva, Álvaro; Ferreira, Maria Amélia; Severo, Milton

    2018-04-16

    One of the most important factors that makes the transition from secondary school to medical school challenging is the inability to put in the study time that a medical school curriculum demands. The implementation of regulated learning is essential for students to cope with medical course environment and succeed. This study aimed to investigate the reciprocal relationships between self-regulated learning skills (SRLS) and academic workload (AW) across secondary school to medical school transition. Freshmen enrolled in medical school (N = 102) completed questionnaires at the beginning and at the end of their academic year, assessing AW (measured as study time hours and perceived workload), SRLS (planning and strategies for learning assessment, motivation and action to learning and self-directedness) and academic achievement. An exploratory factor analysis (EFA) and a longitudinal path analysis were performed. According to the EFA, study time and perceived workload revealed two factors of AW: students who had a high perceived workload also demonstrated increased study time (tandem AW); and those who had a low perceived workload also demonstrated increased study time (inverse AW). Only a longitudinal relationship between SRLS and AW was found in the path analysis: prior self-directedness was related to later tandem AW. Moreover, success during the first year of medical school is dependent on exposure to motivation, self-directedness and high study time without overload during secondary school and medical school, and prior academic achievement. By better understanding these relationships, teachers can create conditions that support academic success during the first year medical school.

  1. Improved diagnosis of the transition to JAK2 (V⁶¹⁷F homozygosity: the key feature for predicting the evolution of myeloproliferative neoplasms.

    Directory of Open Access Journals (Sweden)

    Mariana Selena Gonzalez

    Full Text Available Most cases of BCR-ABL1-negative myeloproliferative neoplasms (MPNs, essential thrombocythemia, polycythemia vera and primary myelofibrosis are associated with JAK2 (V617F mutations. The outcomes of these cases are critically influenced by the transition from JAK2 (V617F heterozygosity to homozygosity. Therefore, a technique providing an unbiased assessment of the critical allele burden, 50% JAK2 (V617F, is highly desirable. In this study, we present an approach to assess the JAK2 (V617F burden from genomic DNA (gDNA and complementary DNA (cDNA using one-plus-one template references for allele-specific quantitative-real-time-PCR (qPCR. Plasmidic gDNA and cDNA constructs encompassing one PCR template for JAK2 (V617F spaced from one template for JAK2(Wild Type were constructed by multiple fusion PCR amplifications. Repeated assessments of the 50% JAK2(V617F burden within the dynamic range of serial dilutions of gDNA and cDNA constructs resulted in 52.53 ± 4.2% and 51.46 ± 4.21%, respectively. The mutation-positive cutoff was estimated to be 3.65% (mean +2 standard deviation using 20 samples from a healthy population. This qPCR approach was compared with the qualitative ARMS-PCR technique and with two standard methods based on qPCR, and highly significant correlations were obtained in all cases. qPCR assays were performed on paired gDNA/cDNA samples from 20 MPN patients, and the JAK2 (V617F expression showed a significant correlation with the allele burden. Our data demonstrate that the qPCR method using one-plus-one template references provides an improved assessment of the clinically relevant transition of JAK2 (V617F from heterozygosity to homozygosity.

  2. Analysis of infiltration through mill tailings using a bromide tracer

    International Nuclear Information System (INIS)

    Lewis, G.J.; Stephens, D.B.

    1985-01-01

    Infiltration of precipitation into tailings impoundments as a means of recharge to underlying materials is often considered insignificant, particularly in arid and semi-arid environments. A series of experiments was performed to investigate the behavior of infiltrated precipitation into tailing soils, by the use of a bromide tracer. A bromide tracer was applied to the surface of columns driven into the tailings to monitor downward advancement of tracer-laden water. Controlled laboratory experiments on the behavior of the bromide tracer under varying precipitation events and initial soil moisture contents were also conducted. Results indicate that a definite downward migration of infiltrated precipitation occurs, particularly with large magnitude precipitation events, and that, eventually, some fraction of the infiltrated precipitation may continue downward below the zone affected by evaporation. The use of an artificially applied bromide tracer</