Science.gov

Sample records for accumulation rate measurements

  1. Using transplants to measure accumulation rates of epiphytic bryophytes in forests of western Oregon

    USGS Publications Warehouse

    Rosso, A.L.; Muir, Patricia S.; Rambo, T.

    2001-01-01

    We sought a simple and effective transplant method that could be used to measure biomass accumulation rates of epiphytic bryophytes. Trials were carried out in the Pseudotsuga menziesii-dominated forests of western Oregon. We tested multiple transplant methods over a 13-month period while comparing accumulation rates of Antitrichia curtipendula (Hedw.) Brid. and Isothecium myosuroides Brid. among an old-growth stand, a young stand, and a recent clearcut. In our study area, Antitrichia is considered to be an old-growth associate while Isothecium is a more ubiquitous species. Methods tested included containment in net bags, containment in hairnets, and directly tying mats to substrates. Three sizes of transplants were tested with both natural and inert artificial substrates. Transplants of approximately five g enclosed in plastic net bags and tied to either natural or artificial substrates worked well for our purposes. Only minor differences were found in mean accumulation rates between the old growth and young stand, though variation in accumulation rates was higher in the old growth. Neither species appeared capable of surviving in the clearcut. Antitrichia accumulated biomass 60% faster in the canopy than in the understory on average. Antitrichia also accumulated at a faster rate than Isothecium, with mean 13-month biomass increases of 11.8 and 3.7% respectively for 5 g transplants in the understory. Our results suggest that Antitrichia's association with old growth may be due more to dispersal or establishment limitations than to a decreased ability to grow in young stands.

  2. Laboratory Determination of Molybdenum Accumulation Rates as a Measure of Hypoxic Conditions

    EPA Science Inventory

    Redox sensitive metals, such as molybdenum (Mo), are enriched in reducing sediments due to authigenic fixation in anoxic interstitial waters of sediments. This study tested whether the process of fixation and accumulation of Mo in sediments could provide a geochemical indicator o...

  3. Measuring water accumulation rates using GRACE data in areas experiencing glacial isostatic adjustment: The Nelson River basin

    NASA Astrophysics Data System (ADS)

    Lambert, A.; Huang, J.; Kamp, G.; Henton, J.; Mazzotti, S.; James, T. S.; Courtier, N.; Barr, A. G.

    2013-12-01

    Recovery and Climate Experiment (GRACE) satellite-derived total water storage can be obscured by glacial isostatic adjustment. In order to solve this problem for the Nelson River drainage basin in Canada, a gravity rate map from 110 months (June 2002 to October 2011) of GRACE gravity data was corrected for glacial isostatic adjustment using an independent gravity rate map derived from updated GPS vertical velocities. The GPS-based map was converted to equivalent gravity rate using a transfer function developed from GPS and absolute-g data at colocated sites. The corrected GRACE gravity rate map revealed a major positive anomaly within the drainage basin, which was independently shown by hydrological data to be due to changes in water storage. The anomaly represents a cumulative increase at its center of about 340 mm of water, reflecting a progression from extreme drought to extremely wet conditions.

  4. Determining Greenland Ice Sheet Accumulation Rates from Radar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Jezek, Kenneth C.

    2002-01-01

    An important component of NASA's Program for Arctic Regional Climate Assessment (PARCA) is a mass balance investigation of the Greenland Ice Sheet. The mass balance is calculated by taking the difference between the areally Integrated snow accumulation and the net ice discharge of the ice sheet. Uncertainties in this calculation Include the snow accumulation rate, which has traditionally been determined by interpolating data from ice core samples taken from isolated spots across the ice sheet. The sparse data associated with ice cores juxtaposed against the high spatial and temporal resolution provided by remote sensing , has motivated scientists to investigate relationships between accumulation rate and microwave observations as an option for obtaining spatially contiguous estimates. The objective of this PARCA continuation proposal was to complete an estimate of surface accumulation rate on the Greenland Ice Sheet derived from C-band radar backscatter data compiled in the ERS-1 SAR mosaic of data acquired during, September-November, 1992. An empirical equation, based on elevation and latitude, is used to determine the mean annual temperature. We examine the influence of accumulation rate, and mean annual temperature on C-band radar backscatter using a forward model, which incorporates snow metamorphosis and radar backscatter components. Our model is run over a range of accumulation and temperature conditions. Based on the model results, we generate a look-up table, which uniquely maps the measured radar backscatter, and mean annual temperature to accumulation rate. Our results compare favorably with in situ accumulation rate measurements falling within our study area.

  5. Metabolic rate measurement system

    NASA Technical Reports Server (NTRS)

    Koester, K.; Crosier, W.

    1980-01-01

    The Metabolic Rate Measurement System (MRMS) is an uncomplicated and accurate apparatus for measuring oxygen consumption and carbon dioxide production of a test subject. From this one can determine the subject's metabolic rate for a variety of conditions, such as resting or light exercise. MRMS utilizes an LSI/11-03 microcomputer to monitor and control the experimental apparatus.

  6. Determining Greenland Ice Sheet Accumulation Rates from Radar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Jezek, Kenneth C.

    2001-01-01

    An important component of NASA's Program for Arctic Regional Climate Assessment (PARCA) is a mass balance investigation of the Greenland Ice Sheet. The mass balance is calculated by taking the difference between the snow accumulation and the ice discharge of the ice sheet. Uncertainties in this calculation include the snow accumulation rate, which has traditionally been determined by interpolating data from ice core samples taken throughout the ice sheet. The sparse data associated with ice cores, coupled with the high spatial and temporal resolution provided by remote sensing, have motivated scientists to investigate relationships between accumulation rate and microwave observations.

  7. Accumulation rates from central North Greenland during the past 700 year

    NASA Astrophysics Data System (ADS)

    Karlsson, Nanna B.; Eisen, Olaf; Nielsen, Lisbeth T.; Kipfstuhl, Sepp; Freitag, Johannes; Paden, John D.; Dahl-Jensen, Dorthe; Winter, Anna; Wilhelms, Frank

    2016-04-01

    A key variable when interpreting the evolution and mass loss from polar ice sheets is the input from the surface mass balance. While ice core records contain information on past accumulation rates, they always only provide information for a single location. Here, we present spatially distributed accumulation rates from central northern Greenland, specifically the area between the NEEM (North Greenland Eemian Drilling) and NGRIP (North Greenland Ice Core Project) ice core drill sites. The accumulation rates have been reconstructed using ice-penetrating radar, firn core measurements and inverse methods, and we are able to retrieve both spatial and temporal changes in the accumulation over an area spanning 300 km by 300 km. We investigate the stability of the accumulation pattern over the past several hundred years, and we address the question of how well the measured accumulation rates at the ice core sites capture the regional variations in accumulation. We find that while the accumulation rates at NEEM have been stable for the past 700 years, the NGRIP site has experienced fluctuations in accumulation rate. We interpret this as an indication of shifts in the dominating weather pattern over the ice divide in central North Greenland.

  8. Temperature-dependence of biomass accumulation rates during secondary succession.

    PubMed

    Anderson, Kristina J; Allen, Andrew P; Gillooly, James F; Brown, James H

    2006-06-01

    Rates of ecosystem recovery following disturbance affect many ecological processes, including carbon cycling in the biosphere. Here, we present a model that predicts the temperature dependence of the biomass accumulation rate following disturbances in forests. Model predictions are derived based on allometric and biochemical principles that govern plant energetics and are tested using a global database of 91 studies of secondary succession compiled from the literature. The rate of biomass accumulation during secondary succession increases with average growing season temperature as predicted based on the biochemical kinetics of photosynthesis in chloroplasts. In addition, the rate of biomass accumulation is greater in angiosperm-dominated communities than in gymnosperm-dominated ones and greater in plantations than in naturally regenerating stands. By linking the temperature-dependence of photosynthesis to the rate of whole-ecosystem biomass accumulation during secondary succession, our model and results provide one example of how emergent, ecosystem-level rate processes can be predicted based on the kinetics of individual metabolic rate.

  9. A 2000-year annual record of snow accumulation rates for Law Dome, East Antarctica

    NASA Astrophysics Data System (ADS)

    Roberts, J.; Plummer, C.; Vance, T.; van Ommen, T.; Moy, A.; Poynter, S.; Treverrow, A.; Curran, M.; George, S.

    2015-05-01

    Accurate high-resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to the mid-latitudes as well as regional Antarctic snowfall. Here, we extend the length of the Law Dome accumulation record from 750 years to 2035 years, using recent annual layer dating that extends to 22 BCE. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long-term mean accumulation rate. The modelled layer thicknesses were based on a power-law vertical strain rate profile fitted to observed annual layer thickness. The periods 380-442, 727-783 and 1970-2009 CE have above-average snow accumulation rates, while 663-704, 933-975 and 1429-1468 CE were below average, and decadal-scale snow accumulation anomalies were found to be relatively common (74 events in the 2035-year record). The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger-scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to El Niño-Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO) frequencies.

  10. Holocene and recent sediment accumulation rates in southern Lake Michigan

    USGS Publications Warehouse

    Colman, Steven M.; King, J.W.; Jones, Glenn A.; Reynolds, R.L.; Bothner, Michael H.

    2000-01-01

    Rates of sediment accumulation in Lake Michigan are a key component of its geologic history and provide important data related to societal concerns such as shoreline erosion and the fate of anthropogenic pollutants. Previous attempts to reconstruct Holocene rates of sediment accumulation in Lake Michigan, as well as in the other Laurentian Great Lakes, have been bedeviled by the effect of refractory terrestrial material on radiocarbon ages from total organic carbon samples of lake sediments. AMS radiocarbon ages on small samples of biogenic carbonate (ostracodes and mollusks) in Lake Michigan provide accurate Holocene ages. The present bicarbonate reservoir effect is estimated from shells of mollusks collected live before atmospheric nuclear testing to be 250 yr. From paired samples of biogenic carbonate and terrestrial macrofossils, the past reservoir effect is thought to be less than 500 yr. The radiocarbon ages indicate a distinct decrease in sediment accumulation rates throughout the southern basin of Lake Michigan at about 5 ka, about the time when lake level stabilized at the Nipissing level after rising rapidly for several thousand years. Average rates of sediment accumulation for the historic period (the last 150 yr) can be estimated from radioisotopes (210Pb and 137Cs), pollen stratigraphy, and changes in sediment properties associated with human activity. Multiple methods are necessary because at any given site, problems arise in the assumptions or applicability of one or more methods. In general, the mass accumulation calculations suggest that sediments were deposited 4 to 11 times faster in the historic period than before human settlement. The character of the sediment did not change in a dramatic way, but sediment magnetic properties suggest shifts in the sources of sediment. The data suggest that some of the changes in sources and (or) character of the sediment occurred just before human settlement and were probably related to climatic changes

  11. A two thousand year annual record of snow accumulation rates for Law Dome, East Antarctica

    NASA Astrophysics Data System (ADS)

    Roberts, J.; Plummer, C.; Vance, T.; van Ommen, T.; Moy, A.; Poynter, S.; Treverrow, A.; Curran, M.; George, S.

    2014-11-01

    Accurate high resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to mid-latitudes as well as regional Antarctic snowfall. Here, we extend the Law Dome accumulation record from 750 to 2035 years, using recent annual layer dating that extends to AD -22. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long term mean accumulation rate. The modelled layer thicknesses were based on a power law vertical strain rate profile fitted to observed annual layer thickness. The periods AD 380-442, AD 727-783 and AD 1970-2009 have above average snow accumulation rates, while AD 663-704, AD 933-975 and AD 1429-1468 were below average. The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to ENSO and Interdecadal Pacific Oscillation frequencies.

  12. Radon exhalation rates from building materials using electret ion chamber radon monitors in accumulators.

    PubMed

    Kotrappa, Payasada; Stieff, Frederick

    2009-08-01

    An electret ion chamber (EIC) radon monitor in a sealed accumulator measures the integrated average radon concentration at the end of the accumulation duration. Theoretical equations have been derived to relate such radon concentrations (Bq m(-3) ) to the radon emanation rate (Bq d(-1)) from building materials enclosed in the accumulator. As an illustration, a 4-L sealable glass jar has been used as an accumulator to calculate the radon emanation rate from different granite samples. The radon emanation rate was converted into radon flux (Bq mm(-2) d(-1)) by dividing the emanation rate by surface area of the sample. Fluxes measured on typical, commercially available granites ranged from 20-30 Bq m(-2) d(-1). These results are similar to the results reported in the literature. The lower limit of detection for a 2-d measurement works out to be 7 Bq m(-2) d(-1). Equations derived can also be used for other sealable accumulators and other integrating detectors, such as alpha track detectors.

  13. A flight experiment to determine GPS photochemical contamination accumulation rates

    NASA Technical Reports Server (NTRS)

    Tribble, A. C.; Haffner, J. W.

    1990-01-01

    It was recently suggested that photochemically deposited contamination, originating from volatiles outgassed by a spacecraft, may be responsible for the anomalous degradation in power seen on the GPS Block 1 vehicles. In an attempt to confirm, or deny, the photochemical deposition rates predicted, a study was undertaken to design a flight experiment to be incorporated on the GPS vehicles currently in production. The objective was to develop an inexpensive, light weight instrument package that would give information on the contamination levels within a few months of launch. Three types of apparatus were studied, Quartz Crystal Microbalances, (QCM's), modified solar cells, and calorimeters. A calorimeter was selected due primarily to its impact on the production schedule of the GPS vehicles. An analysis of the sensitivity of the final design is compared to the predicted contamination accumulation rates in order to determine how long after launch it will take the experiment to show the effects of photochemical contamination.

  14. Radiocarbon Dating, Chronologic Framework, and Changes in Accumulation Rates of Holocene Estuarine Sediments from Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Colman, Steven M.; Baucom, Pattie C.; Bratton, John F.; Cronin, Thomas M.; McGeehin, John P.; Willard, Debra; Zimmerman, Andrew R.; Vogt, Peter R.

    2002-01-01

    Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelerator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210Pb and 137Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

  15. Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay

    USGS Publications Warehouse

    Colman, Steven M.; Baucom, P.C.; Bratton, J.F.; Cronin, T. M.; McGeehin, J.P.; Willard, D.; Zimmerman, A.R.; Vogt, P.R.

    2002-01-01

    Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210 Pb and 137 Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

  16. Rating Scale Instruments and Measurement

    ERIC Educational Resources Information Center

    Cavanagh, Robert F.; Romanoski, Joseph T.

    2006-01-01

    The article examines theoretical issues associated with measurement in the human sciences and ensuring data from rating scale instruments are measures. An argument is made that using raw scores from rating scale instruments for subsequent arithmetic operations and applying linear statistics is less preferable than using measures. These theoretical…

  17. Effect of accumulation rate on water stable isotopes of near-surface snow in inland Antarctica

    NASA Astrophysics Data System (ADS)

    Hoshina, Yu; Fujita, Koji; Nakazawa, Fumio; Iizuka, Yoshinori; Miyake, Takayuki; Hirabayashi, Motohiro; Kuramoto, Takayuki; Fujita, Shuji; Motoyama, Hideaki

    2014-01-01

    changes in water stable isotopes in polar firn were investigated at three sites characterized by different accumulation rates along the East Antarctic ice divide near Dome Fuji. Water stable isotopes, major ion concentrations, and tritium contents of three 2-4 m deep pits were measured at high resolution (2 cm). Temporally, the snow pits cover the past 50 years with snow accumulation rates in the range of 29-41 kg m-2 a-1 around Dome Fuji. Oxygen isotopic profiles in the three pits do not show annual fluctuations, but instead exhibit multiyear cycles. These multiyear cycles are lower in frequency at Dome Fuji as compared with the other two sites. Peaks of water stable isotopes in the multiyear cycles correspond to some ion concentration minima in the pits, although such relationships are not observed in coastal regions. We propose that the extremely low accumulation environment keeps the snow layer at the near surface, which result in postdepositional modifications of isotopic signals by processes such as ventilation and vapor condensation-sublimation. We estimate that oxygen isotopic ratios could be modified by >10‰ and that the original seasonal cycle could be completely overprinted under the accumulation conditions at Dome Fuji. Moreover, stake measurements at Dome Fuji suggest that the large variability in snow accumulation rate is the cause of the multiyear cycles.

  18. Measuring Social Capital Accumulation in Rural Development

    ERIC Educational Resources Information Center

    Teilmann, Kasper

    2012-01-01

    Using a theoretical framework, the study proposes an index that can measure the social capital of local action group (LAG) projects. The index is founded on four indicators: number of ties, bridging social capital, recognition, and diversity, which are aggregated into one social capital index. The index has been tested in LAG-Djursland, Denmark,…

  19. Atmospheric Pb and Ti accumulation rates from Sphagnum moss: dependence upon plant productivity.

    PubMed

    Kempter, H; Krachler, M; Shotyk, W

    2010-07-15

    The accumulation rates of atmospheric Pb and Ti were obtained using the production rates of Sphagnum mosses collected in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and one year later the production of plant matter was harvested. Metal concentrations were determined in acid digests using sector field ICP-MS employing well established analytical procedures. Up to 12 samples (40 x 40 cm) were collected per site, and 6-10 sites were investigated per bog. Variations within a given sampling site were in the range 2.3-4x for Pb concentrations, 1.8-2.5x for Ti concentrations, 3-8.3x for Pb/Ti, 5.6-7.8x for Pb accumulation rates, and 2.3-6.4x for Ti accumulation rates. However, the median values of these parameters for the sites (6-10 per bog) were quite consistent. The mosses from the bogs in NBF exhibited significantly greater productivity (187-202 g m(-2) a(-1)) compared to the OB peat bogs (71-91 g m(-2) a(-1)), and these differences had a pronounced effect on the Pb and Ti accumulation rates. Highly productive mosses showed no indication of a "dilution effect" of Pb or Ti concentrations, suggesting that more productive plants were simply able to accumulate more particles from the air. The median rates of net Pb accumulation by the mosses are in excellent agreement with the fluxes obtained by direct atmospheric measurements at nearby monitoring stations in both regions (EMEP and MAPESI data).

  20. Field measurement of ventilation rates.

    PubMed

    Persily, A K

    2016-02-01

    Ventilation rates have significant impacts on building energy use and indoor contaminant concentrations, making them key parameters in building performance. Ventilation rates have been measured in buildings for many decades, and there are mature measurement approaches available to researchers and others who need to know actual ventilation rates in buildings. Despite the fact that ventilation rates are critical in interpreting indoor concentration measurements, it is disconcerting how few Indoor Air Quality field studies measure ventilation rates or otherwise characterize the ventilation design of the study building(s). This paper summarizes parameters of interest in characterizing building ventilation, available methods for quantifying these parameters, and challenges in applying these methods to different types of buildings and ventilation systems. These parameters include whole-building air change rates, system outdoor air intake rates, and building infiltration rates. Tracer gas methods are reviewed as well as system airflow rate measurements using, for example, duct traverses. Several field studies of ventilation rates conducted over the past 75 years are described to highlight the approaches employed and the findings obtained.

  1. Rate of tree carbon accumulation increases continuously with tree size

    USGS Publications Warehouse

    Stephenson, N.L.; Das, A.J.; Condit, R.; Russo, S.E.; Baker, P.J.; Beckman, N.G.; Coomes, D.A.; Lines, E.R.; Morris, W.K.; Rüger, N.; Álvarez, E.; Blundo, C.; Bunyavejchewin, S.; Chuyong, G.; Davies, S.J.; Duque, Á.; Ewango, C.N.; Flores, O.; Franklin, J.F.; Grau, H.R.; Hao, Z.; Harmon, M.E.; Hubbell, S.P.; Kenfack, D.; Lin, Y.; Makana, J.-R.; Malizia, A.; Malizia, L.R.; Pabst, R.J.; Pongpattananurak, N.; Su, S.-H.; Sun, I-F.; Tan, S.; Thomas, D.; van Mantgem, P.J.; Wang, X.; Wiser, S.K.; Zavala, M.A.

    2014-01-01

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage - increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to understand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  2. Rate of tree carbon accumulation increases continuously with tree size.

    PubMed

    Stephenson, N L; Das, A J; Condit, R; Russo, S E; Baker, P J; Beckman, N G; Coomes, D A; Lines, E R; Morris, W K; Rüger, N; Alvarez, E; Blundo, C; Bunyavejchewin, S; Chuyong, G; Davies, S J; Duque, A; Ewango, C N; Flores, O; Franklin, J F; Grau, H R; Hao, Z; Harmon, M E; Hubbell, S P; Kenfack, D; Lin, Y; Makana, J-R; Malizia, A; Malizia, L R; Pabst, R J; Pongpattananurak, N; Su, S-H; Sun, I-F; Tan, S; Thomas, D; van Mantgem, P J; Wang, X; Wiser, S K; Zavala, M A

    2014-03-06

    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

  3. Rates and environmental controls of aeolian dust accumulation, Athabasca River Valley, Canadian Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Hugenholtz, Chris H.; Wolfe, Stephen A.

    2010-09-01

    Despite an abundance of sedimentary archives of mineral dust (i.e. loess) accumulations from cold, humid environments, the absence of contemporary process investigations limits paleoenvironmental interpretations in these settings. Dust accumulations measured at Jasper Lake, a seasonally-filled reach of the glacially-fed Athabasca River in the Canadian Rocky Mountains, are some of the highest contemporary rates recorded to date. High deposition rates, including a maximum of 27,632 kg ha -1 month -1, occur during river low-flow periods, but even the lowest deposition rates, occurring during bankfull periods, exceed other contemporary rates of deposition. High rates of dust deposition may be attributed to geomorphic and climatic controls affecting sediment supply, availability and transport, and biologic factors affecting accumulation. Localized confinement of the Jasper River by tributary river alluvial fans has caused channel expansion upstream, and formation of the shallow depositional basin known as Jasper Lake. This localized sedimentary basin, coupled with large seasonal water level fluctuations and suitably high wind speeds, favors seasonal dust production. In addition, a dense source-proximal coniferous forest stand encourages high dust accumulation, via increased aerodynamic roughness and airflow deceleration. The forest stand also appears to act as an efficient dust filter, with the interception and storage of dust by the forest canopy playing a significant role with regards to secondary fallout and sediment accumulation. Overall, these results provide new insights on the environmental controls of dust entrainment and accumulation in cold, humid settings, and help clarify controls on the formation of Holocene river-sourced loess deposits.

  4. Accumulation rates during 1311-2011 CE in North Central Greenland derived from air-borne radar data

    NASA Astrophysics Data System (ADS)

    Karlsson, Nanna; Eisen, Olaf; Dahl-Jensen, Dorthe; Freitag, Johannes; Kipfstuhl, Sepp; Lewis, Cameron; Nielsen, Lisbeth; Paden, John; Winter, Anna; Wilhelms, Frank

    2016-11-01

    Radar-detected internal layering contains information on past accumulation rates and patterns. In this study, we assume that the radar layers are isochrones, and use the layer stratigraphy in combination with ice-core measurements and numerical methods to retrieve accumulation information for the northern part of central Greenland. Measurements of the dielectric properties of an ice core from the NEEM (North Greenland Eemian Ice Drilling) site, allow for correlation of the radar layers with volcanic horizons to obtain an accurate age of the layers. We obtain accumulation patterns averaged over 100 a for the period 1311-2011. Our results show a clear trend of high accumulation rates west of the ice divide and low accumulation rates east of the ice divide. At the NEEM site the accumulation pattern is persistent during our study period and only small temporal variations occur in the accumulation rate. However, from approximately 200 km south of the NEEM drill site, the accumulation rate shows temporal variations based on our centennial averages. We attribute this variation to shifts in the location of the high-low accumulation boundary that usually is aligned with the ice divide, but appears to have moved across the divide in the past.

  5. Holocene Carbon Accumulation Rates in the SPRUCE Bog Prior to Warming and Elevated CO2 Treatment

    NASA Astrophysics Data System (ADS)

    McFarlane, K. J.; Iversen, C. M.; Phillips, J. R.; Brice, D. J.; Hanson, P. J.

    2015-12-01

    In the Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) experiment warming and elevated CO2 treatments are being applied to an ombrotrophic spruce bog: the S1 Bog (S1) at Marcell Experimental Forest in northern Minnesota. To provide a historical context for recent and expected experimentally-induced changes in the bog's belowground carbon balance, we reconstructed historical carbon accumulation rates in peat using radiocarbon from 19 peat cores collected from randomly distributed SPRUCE plots. This unusually high number of cores allows us to assess spatial variability in age-depth profiles and accumulation rates across the SPRUCE study area within S1. This data, along with recent C flux measurements, show that the bog has been accumulating carbon for at least 12,0000 years and has continued to be a sink for atmospheric carbon of approximately 150 g C m-2 yr-1 in recent decades. Early Holocene accumulation rates are similar to those reported for other northern peatlands (approximately 25 g C m-2 yr-1), but apparent carbon accumulation decreased substantially around 3,000 years ago (to 5-15 g C m-2 yr-1) and stayed low until the last century. This decrease is considerably larger than that reported for other peatlands and is therefore unlikely to result only from cooling during the Holocene or bog succession. Although no charcoal has been found in peat at this site, evidence from a neighboring bog indicates a considerable amount of peat formed during this period was consumed by fire and it is possible that smoldering fires consumed peat, resulting in low apparent accumulation rates. Past droughts may have also contributed to observed trends by lowering the acrotelm/catotelm boundary, allowing for enhanced aerobic peat decomposition. This work provides important background information on spatial variability and carbon biogeochemistry that will aid in interpretation of climate change simulation experiments at S1.

  6. Metal accumulation rates in northwest Atlantic pelagic sediments

    NASA Astrophysics Data System (ADS)

    Thomson, J.; Carpenter, M. S. N.; Colley, S.; Wilson, T. R. S.; Elderfield, H.; Kennedy, H.

    1984-10-01

    Measurements of 230Th, 87Sr /86Sr and twenty-four metals were made on cores from the Nares Abyssal Plain. The sediment is characterized by slowly-accumulating (0.3-0.7 g/cm 2 10 3 yr) pelagic red clays and rapidly deposited grey clays transported by turbidity currents. Despite their colour differences and the enrichment of Mn, Fe, Cu, Co, Ni, Zn, V and, to a lesser degree, the rare earths in the red clays, Sr isotope evidence demonstrates that the clays have the same terrigenous origin. The excesses of metals in the red clays have been attributed to metal removal from the water column and a comparison with the grey clays has enabled the authigenic fluxes of metals to be estimated. The fluxes obtained are in the ranges 20-50 μmol/cm 2 10 3 yr for Mn and Fe, 0.1-0.4 μmol/cm 2 10 3 yr for Cu, Co, Ni, Zn, V, Sr and Ce, 10-20 nmol/cm 2 10 3 yr for La and Nd, and 0.5-3 nmol/cm 2 10 3 yr for Sm, Eu, Gd, Dy, Er and Yb. Authigenic fluxes of Y, Nb, Cr, Zr, Rb, U and Th were not resolvable. Fluxes appear to be near constant on the Plain but comparison with other areas shows that they are quite variable both between and within ocean basins. The chief factor controlling authigenic fluxes is the geochemical abundances of the elements but fractionation within both the transition element and rare earth series can be recognized from inter-element comparisons and from differences in fluxes between Atlantic and Pacific red clays corresponding to the oceanic reactivities of the elements.

  7. Sensor for Injection Rate Measurements

    PubMed Central

    Marcic, Milan

    2006-01-01

    A vast majority of the medium and high speed Diesel engines are equipped with multi-hole injection nozzles nowadays. Inaccuracies in workmanship and changing hydraulic conditions in the nozzles result in differences in injection rates between individual injection nozzle holes. The new deformational measuring method described in the paper allows injection rate measurement in each injection nozzle hole. The differences in injection rates lead to uneven thermal loads of Diesel engine combustion chambers. All today known measuring method, such as Bosch and Zeuch give accurate results of the injection rate in diesel single-hole nozzles. With multihole nozzles they tell us nothing about possible differences in injection rates between individual holes of the nozzle. At deformational measuring method, the criterion of the injected fuel is expressed by the deformation of membrane occurring due to the collision of the pressure wave against the membrane. The pressure wave is generated by the injection of the fuel into the measuring space. For each hole of the nozzle the measuring device must have a measuring space of its own into which fuel is injected as well as its measuring membrane and its own fuel outlet. During measurements procedure the measuring space must be filled with fuel to maintain an overpressure of 5 kPa. Fuel escaping from the measuring device is conducted into the graduated cylinders for measuring the volumetric flow through each hole of the nozzle.The membrane deformation is assessed by strain gauges. They are glued to the membrane and forming the full Wheatstone's bridge. We devoted special attention to the membrane shape and temperature compensation of the strain gauges.

  8. Rating scales and Rasch measurement.

    PubMed

    Andrich, David

    2011-10-01

    Assessments with ratings in ordered categories have become ubiquitous in health, biological and social sciences. Ratings are used when a measuring instrument of the kind found in the natural sciences is not available to assess some property in terms of degree - for example, greater or smaller, better or worse, or stronger or weaker. The handling of ratings has ranged from the very elementary to the highly sophisticated. In an elementary form, and assumed in classical test theory, the ratings are scored with successive integers and treated as measurements; in a sophisticated form, and used in modern test theory, the ratings are characterized by probabilistic response models with parameters for persons and the rating categories. Within modern test theory, two paradigms, similar in many details but incompatible on crucial points, have emerged. For the purposes of this article, these are termed the statistical modeling and experimental measurement paradigms. Rather than reviewing a compendium of available methods and models for analyzing ratings in detail, the article focuses on the incompatible differences between these two paradigms, with implications for choice of model and inferences. It shows that the differences have implications for different roles for substantive researchers and psychometricians in designing instruments with rating scales. To illustrate these differences, an example is provided.

  9. An integral method to estimate the moment accumulation rate on the Creeping Section of the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Tong, Xiaopeng; Sandwell, David T.; Smith-Konter, Bridget

    2015-10-01

    Moment accumulation rate (also referred to as moment deficit rate) is a fundamental quantity for evaluating seismic hazard. The conventional approach for evaluating moment accumulation rate of creeping faults is to invert for the slip distribution from geodetic measurements, although even with perfect data these slip-rate inversions are non-unique. In this study, we show that the slip-rate versus depth inversion is not needed because moment accumulation rate can be estimated directly from surface geodetic data. We propose an integral approach that uses dense geodetic observations from Interferometric Synthetic Aperture Radar (InSAR) and the Global Positioning System (GPS) to constrain the moment accumulation rate. The moment accumulation rate is related to the integral of the product of the along-strike velocity and the distance from the fault. We demonstrate our methods by studying the Creeping Section of the San Andreas fault observed by GPS and radar interferometry onboard the ERS and ALOS satellites. Along-strike variation of the moment accumulation rate is derived in order to investigate the degree of partial locking of the Creeping Section. The central Creeping Segment has a moment accumulation rate of 0.25-3.1 × 1015 Nm yr-1 km-1. The upper and lower bounds of the moment accumulation rates are derived based on the statistics of the noise. Our best-fitting model indicates that the central portion of the Creeping Section is accumulating seismic moment at rates that are about 5 per cent to 23 per cent of the fully locked Carrizo segment that will eventually be released seismically. A cumulative moment budget calculation with the historical earthquake catalogue (M > 5.5) since 1857 shows that the net moment deficit at present is equivalent to a Mw 6.3 earthquake.

  10. Comparison of carbon emission and accumulation rates in sub-arctic lakes

    NASA Astrophysics Data System (ADS)

    Lundin, Erik; Bastviken, David; Klaminder, Jonatan; Olid Garcia, Carolina; Karlsson, Jan

    2013-04-01

    Lakes play an important role for the carbon cycling in the sub-arctic landscape by both storing carbon in sediments and by releasing carbon to the atmosphere. Still, our knowledge regarding the importance of carbon accumulation rates vs. carbon emissions in lakes is poor, restricting large scale assessment of source sink potential of lakes in the landscape. In this study we compare annual carbon accumulation rates and CO2 and CH4 emissions to the atmosphere for six Swedish subarctic lakes. We measured the partial pressure of CO2 (every second hour) during the ice free season. CH4 emissions were measured using floating chambers. Furthermore, we sampled sediment cores from each lake (one to three cores per lake depending on lakes sizes) and calculated the recent accumulation rate of carbon into sediments by dating each core, using 210Pb. Total annual carbon emissions (CO2 + CH4) ranged between 5 to 54 g C m-2 yr-1; hence, all lakes were atmospheric net sources of carbon. Carbon emissions were overall dominated by CO2 which made up to over 90 % of the total annual carbon emission in all lakes except one, having low CO2 emission, where CH4 counted for 40% of the annual carbon emission. Sediment carbon accumulation rates were of comparable magnitudes as the emissions, counting for rates of 30 to 60% of the total carbon emission to the atmosphere. This results stress the dual role of subarctic lakes as they are acting both as atmospheric sources of CO2 and CH4 and as significant storages of carbon in sediments.

  11. Synthesis of passive microwave and radar altimeter data for estimating accumulation rates of polar snow

    NASA Technical Reports Server (NTRS)

    Davis, Curt H.

    1993-01-01

    In this paper, we compare dry-snow extinction coefficients derived from radar altimeter data with brightness temperature data from passive microwave measurements over a portion of the East Antarctic plateau. The comparison between the extinction coefficients and the brightness temperatures shows a strong negative correlation, where the correlation coefficients ranged from -0.87 to -0.95. The extinction coefficient of the dry polar snow decreases with increasing surface elevation, while the average brightness temperature increases with surface elevation. Our analysis shows that the observed trends are related to geographic variations in scattering coefficient of snow, which in turn are controlled by variations in surface temperature and snow accumulation rate. By combining information present in the extinction coefficient and brightness temperature data sets, we develop a model that can be used to obtain quantitative estimates of the accumulation rate of dry polar snow.

  12. Soil carbon stocks and their rates of accumulation and loss in a boreal forest landscape

    USGS Publications Warehouse

    Rapalee, G.; Trumbore, S.E.; Davidson, E.A.; Harden, J.W.; Veldhuis, H.

    1998-01-01

    Boreal forests and wetlands are thought to be significant carbon sinks, and they could become net C sources as the Earth warms. Most of the C of boreal forest ecosystems is stored in the moss layer and in the soil. The objective of this study was to estimate soil C stocks (including moss layers) and rates of accumulation and loss for a 733 km2 area of the BOReal Ecosystem-Atmosphere Study site in northern Manitoba, using data from smaller-scale intensive field studies. A simple process-based model developed from measurements of soil C inventories and radiocarbon was used to relate soil C storage and dynamics to soil drainage and forest stand age. Soil C stocks covary with soil drainage class, with the largest C stocks occurring in poorly drained sites. Estimated rates of soil C accumulation or loss are sensitive to the estimated decomposition constants for the large pool of deep soil C, and improved understanding of deep soil C decomposition is needed. While the upper moss layers regrow and accumulate C after fires, the deep C dynamics vary across the landscape, from a small net sink to a significant source. Estimated net soil C accumulation, averaged for the entire 733 km2 area, was 20 g C m-2 yr-1 (28 g C m-2 yr-1 accumulation in surface mosses offset by 8 g C m-2 yr-1 lost from deep C pools) in a year with no fire. Most of the C accumulated in poorly and very poorly drained soils (peatlands and wetlands). Burning of the moss layer in only 1% of uplands would offset the C stored in the remaining 99% of the area. Significant interannual variability in C storage is expected because of the irregular occurrence of fire in space and time. The effects of climate change and management on fire frequency and on decomposition of immense deep soil C stocks are key to understanding future C budgets in boreal forests.

  13. Rate of production, dissolution and accumulation of biogenic solids in the ocean

    NASA Technical Reports Server (NTRS)

    Arrhenius, G.

    1988-01-01

    The equatorial current system, by its response to global circulation changes, provides a unique recording mechanism for long range climatic oscillations. A permanent record of the changes in rate of upwelling and organic production is generated in the equatorial deep sea sediments, particularly by such biogenic components which are unaffected by secondary dissolution. In order to determine the rates of accumulation of various sedimentary components, a reliable differential measurement of age of the strata must be obtained. Various approaches to this problem are reviewed, and sources of error discussed. Secondary dissolution of calcium carbonate introduces a substantial and variable difference between the dissolution-modified, and hence a priori unknown, rate of deposition on one hand and the rate of accumulation, derivable from the observed concentration, on the other. The cause and magnitude of these variations are of importance, particularly since some current dating schemes are based on assumed constancy in the rate of accumulation of this and, in some cases, also all other sedimentary components. The concepts used in rate evaluation are discussed with emphasis on the difference between the state of dissolution, an observable property of the sediment, and the rate of dissolution, a parameter that requires deduction of the carbonate fraction dissolved, and of the time differential. As a most likely cause of the enhanced state of dissolution of the interglacial carbonate sediments is proposed the lowered rates of biogenic production and deposition, which cause longer exposure of the carbonate microfossils to corrosion in the bioturbated surface layer of the sediment. Historical perspective is included in the discussion in view of the dedication of the Symposium to Hans Pettersson, the leader of the Swedish Deep Sea Expedition 1947-1948, an undertaking that opened a new era in deep sea research and planetary dynamics.

  14. Rate of production, dissolution and accumulation of biogenic solids in the ocean.

    PubMed

    Arrhenius, G

    1988-01-01

    The equatorial current system, by its response to global circulation changes, provides a unique recording mechanism for long range climatic oscillations. A permanent record of the changes in rate of upwelling and organic production is generated in the equatorial deep sea sediments, particularly by such biogenic components which are unaffected by secondary dissolution. In order to determine the rates of accumulation of various sedimentary components, a reliable differential measurement of age of the strata must be obtained. Various approaches to this problem are reviewed, and sources of error discussed. Secondary dissolution of calcium carbonate introduces a substantial and variable difference between the dissolution-modified, and hence a priori unknown, rate of deposition on one hand and the rate of accumulation, derivable from the observed concentration, on the other. The cause and magnitude of these variations are of importance, particularly since some current dating schemes are based on assumed constancy in the rate of accumulation of this and, in some cases, also all other sedimentary components. The concepts used in rate evaluation are discussed with emphasis on the difference between the state of dissolution, an observable property of the sediment, and the rate of dissolution, a parameter that requires deduction of the carbonate fraction dissolved, and of the time differential. As a most likely cause of the enhanced state of dissolution of the interglacial carbonate sediments is proposed the lowered rates of biogenic production and deposition, which cause longer exposure of the carbonate microfossils to corrosion in the bioturbated surface layer of the sediment. Historical perspective is included in the discussion in view of the dedication of the Symposium to Hans Pettersson, the leader of the Swedish Deep Sea Expedition 1947-1948, an undertaking that opened a new era in deep sea research and planetary dynamics.

  15. Dual physiological rate measurement instrument

    NASA Technical Reports Server (NTRS)

    Cooper, Tommy G. (Inventor)

    1990-01-01

    The object of the invention is to provide an instrument for converting a physiological pulse rate into a corresponding linear output voltage. The instrument which accurately measures the rate of an unknown rectangular pulse wave over an extended range of values comprises a phase-locked loop including a phase comparator, a filtering network, and a voltage-controlled oscillator, arranged in cascade. The phase comparator has a first input responsive to the pulse wave and a second input responsive to the output signal of the voltage-controlled oscillator. The comparator provides a signal dependent on the difference in phase and frequency between the signals appearing on the first and second inputs. A high-input impedance amplifier accepts an output from the filtering network and provides an amplified output DC signal to a utilization device for providing a measurement of the rate of the pulse wave.

  16. Comparing Laboratory and Field Measured Biota-sediment Accumulation Factors

    EPA Science Inventory

    The report presents a review of studies where biota-sediment accumulation factors (BSAFs) were measured in the field, and the same sediment samples were tested in the laboratory using sediment bioaccumulation testing protocols. The focus of this review was to document the extent...

  17. Accumulation Rates of Trace Elements in the Cariaco Basin-A 20-kyr History of Seawater Chemistry and Global Climate

    NASA Astrophysics Data System (ADS)

    Piper, D. Z.; Dean, W. E.

    2002-12-01

    A sediment core from the Cariaco Basin on the Venezuelan continental shelf, which collected sediment as old as 20 kyr, was analyzed for its major-element-oxide and trace-element concen-trations. The elements can be partitioned between a siliciclastic, terrigenous-derived fraction and two seawater-derived fractions. The marine fractions are (1) a biogenic fraction represented by nutrient trace elements taken up mostly by phytoplankton in the photic zone, and (2) a hydroge-nous fraction derived from bottom water via adsorption and precipitation reactions. The present-day export of organic matter from the photic zone, redox conditions and advection of bottom water, and the flux of terrigenous debris into the basin are used to calculate current trace-element accu-mulation rates. The sums of calculated accumulation rates of Cd, Cu, Mo, Ni, V, and Zn show excellent agreement with their measured bulk rates of accumulation in the uppermost surface sediment. This agreement between current measured and calculated accumulation rates of trace elements supports a model of trace-element accumulation rates in the subsurface sediment that gives a 20-kyr history of upwelling into the photic zone, bottom-water advection, and sediment provenance. Extrema in the trace-element accumulation rates and interpreted hydrographic properties of the water column correspond to changes in eustatic sea level and global climate.

  18. Organic Carbon, Nitrogen and Phosphorus Accumulation Rates in the Soils of the Everglades Mangrove Ecotone

    NASA Astrophysics Data System (ADS)

    Smoak, J. M.; Breithaupt, J. L.; Sanders, C. J.

    2015-12-01

    One of the fundamental questions with regard to coastal ecotones relates to their role in the transformation, transport and storage of biogeochemically important constituents and how that role may be altered by climate change. Coastal wetlands provide a range of valuable ecosystem services including sequestering organic carbon (OC) and nutrients in their soils at rates greater than terrestrial ecosystems on a per area basis. As such the Everglades mangrove ecotone, the largest contiguous mangrove forest in North America, is a biogeochemical "hotspot" at the interface of freshwater marsh and the Gulf of Mexico. Over the last one hundred years this region has been impacted by a reduction in freshwater flow and a sea-level rise (SLR) of 2.3 mm/yr which combined to cause a landward shift in the ecotone. This creates an ideal setting to examine climate induced alterations in the mangrove-ecotone biogeochemical cycle. The ability of the Everglades mangrove forest to keep pace with SLR depends largely on the rate of organic matter accumulation as that accumulation is a key contributor to accretion. However, the basic threat from SLR can be exacerbated in some areas by accelerating organic matter mineralization due to increasing salinity. The increase in salinity supplies sulfate which functions as a terminal electron acceptor that soil microbes can utilize to enhance mineralization in the brackish ecotone regions of coastal wetlands. To investigate these processes, we measured mangrove forest soil accretion, OC, N and P accumulation rates over the most recent 10, 50 and 100 year periods (via 210Pb dating) from the Gulf of Mexico to the upper freshwater reaches of the mangrove forest within Everglades National Park. Lower organic carbon accumulation rates compared to the rest of the system were found in the ecotone region most susceptible to enhanced organic matter mineralization.

  19. Accumulation rates of Th-230, Pa-231, and some transition metals on the Bermuda Rise

    USGS Publications Warehouse

    Bacon, M.P.; Rosholt, J.N.

    1982-01-01

    Measurements of 238U, 234U, 230Th, 232Th, 231Pa, Mn, Fe, Co, Ni, Cu, and Zn were made on 23 samples from core GPC-5, a 29-m giant piston core from a water depth of 4583 m on the northeastern Bermuda Rise (33??41.2???N, 57??36.9???W). This area is characterized by rapid deposition of sediment transported by abyssal currents. Unsupported 230Th and 231Pa are present throughout the core but, because of large variations in the sedimentation rate, show marked departures from exponential decay with depth. The trend with depth of the 231Paex 230Thex ratio is consistent with the average accumulation rate of 36 cm/1000 y reported earlier on the basis of radiocarbon dating and CaCO3 stratigraphy. When expressed on a carbonate-free basis, concentrations of Mn, Co, Ni, Cu, Zn, 230Thex, and 231Paex all show cyclic variations positively correlated with those of CaCO3. The correlations can be explained by a model in which all of these constituents, including CaCO3, are supplied to the sediments from the water column at a constant rate. Concentration variations are controlled mainly by varying inputs of terrigenous detritus, with low inputs occurring during interglacials and high inputs during glacials. Relationships between the metal and 230Thex concentrations permit estimates of the rates at which the metals are removed to the sediment by scavenging from the water column. The results, in ??g/cm2-1000 y, are: 4300 ?? 1100 for Mn, 46 ?? 16 for Ni and 76 ?? 26 for Cu. These rates are somewhat larger than ocean-wide averages estimated by other methods, and the absolute rate of 230Th accumulation in GPC-5 averages about nine times higher than production in the overlying water column. This part of the Bermuda Rise and similar bottom-current deposits may act as important accumulators of elements scavenged from seawater. ?? 1982.

  20. Winter Insulation By Snow Accumulation in a Subarctic Treeline Ecosystem Increases Summer Carbon Cycling Rates

    NASA Astrophysics Data System (ADS)

    Parker, T.; Subke, J. A.; Wookey, P. A.

    2014-12-01

    The effect of snow accumulation on soil carbon and nutrient cycling is attracting substantial attention from researchers. We know that deeper snow accumulation caused by high stature vegetation increases winter microbial activity and therefore carbon and nitrogen flux rates. However, until now the effect of snow accumulation, by buffering winter soil temperature, on subsequent summer soil processes, has scarcely been considered. We carried out an experiment at an alpine treeline in subarctic Sweden in which soil monoliths, contained within PVC collars, were transplanted between forest (deep winter snow) and tundra heath (shallow winter snow). We measured soil CO2efflux over two growing seasons and quantified soil microbial biomass after the second winter. We showed that respiration rates of transplanted forest soil were significantly reduced compared with control collars (remaining in the forest) as a consequence of colder, but more variable, winter temperatures. We hypothesised that microbial biomass would be reduced in transplanted forests soils but found there was no difference compared to control. We therefore further hypothesised that the similarly sized microbial pool in the control is assembled differently to the transplant. We believe that the warmer winters in forests foster more active consortia of decomposer microbes as a result of different abiotic selection pressures. Using an ecosystem scale experimental approach, we have identified a mechanism that influences summer carbon cycling rates based solely on the amount of snow that accumulates the previous winter. We conclude that modification of snow depth as a consequence of changes in vegetation structure is an important mechanism influencing soil C stocks in ecosystems where snow persists for a major fraction of the year.

  1. Annual Greenland Accumulation Rates (2009-2012) from Airborne Snow Radar

    NASA Technical Reports Server (NTRS)

    Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joseph R.; Tedesco, Marco; Leuschen, Carl; Gogineni, Prasad

    2016-01-01

    Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in order to improve sea-level rise predictions. Snow accumulation is the largest component of the ice sheet's surface mass balance, but in situ observations thereof are inherently sparse and models are difficult to evaluate at large scales. Here, we quantify recent Greenland accumulation rates using ultra-wideband (2-6.5 gigahertz) airborne snow radar data collected as part of NASA's Operation IceBridge between 2009 and 2012. We use a semi-automated method to trace the observed radiostratigraphy and then derive annual net accumulation rates for 2009-2012. The uncertainty in these radar-derived accumulation rates is on average 14 percent. A comparison of the radarderived accumulation rates and contemporaneous ice cores shows that snow radar captures both the annual and longterm mean accumulation rate accurately. A comparison with outputs from a regional climate model (MAR - Modele Atmospherique Regional for Greenland and vicinity) shows that this model matches radar-derived accumulation rates in the ice sheet interior but produces higher values over southeastern Greenland. Our results demonstrate that snow radar can efficiently and accurately map patterns of snow accumulation across an ice sheet and that it is valuable for evaluating the accuracy of surface mass balance models.

  2. Annual Greenland accumulation rates (2009-2012) from airborne snow radar

    NASA Astrophysics Data System (ADS)

    Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joesph R.; Tedesco, Marco; Leuschen, Carl; Gogineni, Prasad

    2016-08-01

    Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in order to improve sea-level rise predictions. Snow accumulation is the largest component of the ice sheet's surface mass balance, but in situ observations thereof are inherently sparse and models are difficult to evaluate at large scales. Here, we quantify recent Greenland accumulation rates using ultra-wideband (2-6.5 GHz) airborne snow radar data collected as part of NASA's Operation IceBridge between 2009 and 2012. We use a semiautomated method to trace the observed radiostratigraphy and then derive annual net accumulation rates for 2009-2012. The uncertainty in these radar-derived accumulation rates is on average 14 %. A comparison of the radar-derived accumulation rates and contemporaneous ice cores shows that snow radar captures both the annual and long-term mean accumulation rate accurately. A comparison with outputs from a regional climate model (MAR) shows that this model matches radar-derived accumulation rates in the ice sheet interior but produces higher values over southeastern Greenland. Our results demonstrate that snow radar can efficiently and accurately map patterns of snow accumulation across an ice sheet and that it is valuable for evaluating the accuracy of surface mass balance models.

  3. Elevated rates of organic carbon, nitrogen, and phosphorus accumulation in a highly impacted mangrove wetland

    NASA Astrophysics Data System (ADS)

    Sanders, Christian J.; Eyre, Bradley D.; Santos, Isaac R.; Machado, Wilson; Luiz-Silva, Wanilson; Smoak, Joseph M.; Breithaupt, Joshua L.; Ketterer, Michael E.; Sanders, Luciana; Marotta, Humberto; Silva-Filho, Emmanoel

    2014-04-01

    The effect of nutrient enrichment on mangrove sediment accretion and carbon accumulation rates is poorly understood. Here we quantify sediment accretion through radionuclide tracers to determine organic carbon (OC), total nitrogen (TN), and total phosphorus (TP) accumulation rates during the previous 60 years in both a nutrient-enriched and a pristine mangrove forest within the same geomorphological region of southeastern Brazil. The forest receiving high nutrient loads has accumulated OC, TN, and TP at rates that are fourfold, twofold, and eightfold respectively, higher than those from the undisturbed mangrove. Organic carbon and TN stable isotopes (δ13C and δ15N) reflect an increased presence of organic matter (OM) originating with either phytoplankton, benthic algae, or another allochthonous source within the more rapidly accumulated sediments of the impacted mangrove. This suggests that the accumulation rate of OM in eutrophic mangrove systems may be enhanced through the addition of autochthonous and allochthonous nonmangrove material.

  4. Accumulator

    NASA Technical Reports Server (NTRS)

    Fenwick, J. R.; Karigan, G. H. (Inventor)

    1977-01-01

    An accumulator particularly adapted for use in controlling the pressure of a stream of fluid in its liquid phase utilizing the fluid in its gaseous phase was designed. The accumulator is characterized by a shell defining a pressure chamber having an entry throat for a liquid and adapted to be connected in contiguous relation with a selected conduit having a stream of fluid flowing through the conduit in its liquid phase. A pressure and volume stabilization tube, including an array of pressure relief perforations is projected into the chamber with the perforations disposed adjacent to the entry throat for accommodating a discharge of the fluid in either gaseous or liquid phases, while a gas inlet and liquid to gas conversion system is provided, the chamber is connected with a source of the fluid for continuously pressuring the chamber for controlling the pressure of the stream of liquid.

  5. Rates of biomass accumulation of North Carolina Piedmont forests

    SciTech Connect

    Peet, R.K.; Council, O.P.

    1980-01-01

    Recent work by Sharp et al. on the primary production of North Carolina vegetation has suggested that the average natural forest in North Carolina is unproductive relative to its potential as intensively managed forest, the difference being roughly 300%. This variation could be attributable to patterns of forest recovery after disturbance, to management practices, or even to species composition. These and other alternative hypotheses need to be tested in a careful and objective manner. The primary objectives of the present research project were twofold: (1) to use dimension analysis methods to develop a set of regression equations useful for evaluating the productivity (rate of solar energy fixation) and biomass (stored energy) of North Carolina piedmont forests; (2) to use the resulting equations to document patterns in and rates of change of forest production and biomass during forest recovery from disturbance. The first objective was divided into two component parts. First, the regression equations were developed. Second, the caloric content of trees was studied so as to allow conversion from biomass units (Kg/m/sup 2/) to energy units (Kcal/m/sup 2/). Section 2 of this report outlines the dimension analysis procedure, presents the resulting equations, and explains their use. The portion of the project assessing the caloric content of trees is presented in Section 3. The results of our second objective, the examination of changes in forest biomass and production, are presented in Section 4.

  6. Spatial variation in rates of carbon and nitrogen accumulation in a boreal bog

    SciTech Connect

    Ohlson, M.; Oekland, R.H.

    1998-12-01

    Although previous studies hint at the occurrence of substantial spatial variation in the accumulation rates of C and N in bogs, the extent to which rates may vary on high-resolution spatial and temporal scales is not known. A main reason for the lack of knowledge is that it is problematic to determine the precise age of peat at a given depth. The authors determined rates of carbon and nitrogen accumulation in the uppermost decimeters of a bog ecosystem using the pine method, which enables accurate dating of surface peat layers. They combined accumulation data with numerical and geostatistical analyses of the recent vegetation to establish the relationship between bog vegetation and rate of peat accumulation. Use of a laser technique for spatial positioning of 151 age-determined peat cores within a 20 x 20 m plot made it possible to give the first tine-scaled account of spatial and temporal variation in rates of mass, carbon, and nitrogen accumulation during the last century. Rates of C and N accumulation were highly variable at all spatial scales studied. For example, after {approximately}125 yr of peat growth, C and N accumulation varied by factors of five and four, respectively, from 25 to 125 g/dm{sup 2} for C, and from 0.7 to 2.6 g/dm{sup 2} for N. It takes 40 yr of peat accumulation before significant amounts of C are lost through decay. Hummocks built up by Sphagnum fuscum and S. rubellum were able to maintain average rates of C accumulation that exceed 2 g{center_dot}dm{sup {minus}2}{center_dot} yr{sup {minus}1} during 50 yr of growth. The authors argue that data on spatial variation in rates of C accumulation are necessary to understand the role of boreal peatlands in the greenhouse effect and global climate.

  7. Holocene sediment accumulation rates in fjords and bays of Chilean Patagonia and the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Wellner, J. S.; Anderson, J. B.; Milliken, K.; Fernandez, R.; Michalchuk, B.; Boyd, B.

    2007-12-01

    Beginning in 2005 and ending in May of 2007, we completed a series of four research cruises in the fjords and bays of Chilean Patagonia and the Antarctic Peninsula aimed, in part, at determining the style and rate of Holocene sediment accumulation in a range of glacial settings. Our original hypothesis stated that rates of glacial erosion are a function of sliding speed, and are therefore expected to diminish sharply as basal temperatures drop below the melting point. To test this hypothesis, we measured sediment accumulation in tidewater glacier fjords ranging from fast-moving temperate glaciers in Patagonia to slower moving polar glaciers on the Antarctic Peninsula. Four fjords were surveyed in Patagonia ranging from San Rafael fjord in the Northern Patagonia ice field to Marinelli fjord in Tierra del Fuego. The cruises to the Antarctic Peninsula included two SHALDRIL legs during which drill cores recovered 108 m and 80 m of Holocene sediment in Maxwell Bay, South Shetland Islands, and the Firth of Tay in the northwestern Weddell Sea, respectively. An additional nine fjords across the northern peninsula were surveyed with kasten and jumbo piston cores. To date, we have completed nearly 100 radiocarbon dates from fossil carbonate material, both shells and foraminifera, extracted from the sediment cores obtained in these fjords. Our initial results highlight the complexity of the controls on sediment yields and the extreme variability in sediment accumulation amongst fjords. While climate may be the first order control on glacier erosion rates and sediment transport to bays and fjords, several other factors must significantly influence these processes and may mask the broader signal. Our ongoing work with this newly acquired comprehensive dataset is examining additional controls including drainage basin size, precipitation gradient, altitude of the glaciers, and glacial substrate.

  8. Comparison of elemental accumulation rates between ferromanganese deposits and sediments in the South Pacific Ocean

    USGS Publications Warehouse

    Kraemer, T.; Schornick, J.C.

    1974-01-01

    Rates of accumulation of Fe and Mn, as well as Cu, Ni, Co, Pb, Zn, Hg, U and Th have been determined for five ferromanganese deposits from four localities in the South Pacific Ocean. Manganese is accumulating in nodules and crusts at a rate roughly equivalent to that found to be accumulating in sediments in the same area. Iron shows a deficiency in accumulation in nodules and crusts with respect to sediments, especially near the continents, but also in the central and south-central Pacific. Copper is accumulating in nodules and crusts at a rate one order of magnitude less than the surrounding sediments. This is interpreted as meaning that most of the Mn is supplied as an authigenic phase to both sediments and nodules while Fe is supplied mostly by ferromanganese micro-nodules and by detrital and adsorbed components of sediments; and Cu is enriched in sediments relative to nodules and crusts most probably through biological activity. ?? 1974.

  9. Moment accumulation rate on faults in California inferred from viscoelastic earthquake cycle models (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, K. M.

    2009-12-01

    model assumptions and are generally consistent with geologic estimates; therefore we focus on estimates of the distribution of interseismic locking of faults. We constrain the locking distribution using nearly a century of triangulation measurements of strain following the M7.8 1906 San Francisco earthquake, contemporary GPS velocities, geologic slip rate and earthquake timing data, and the viscoelastic earthquake cycle model with spatially variable distributions of locking and stress-driven creep. We find considerable lateral variations in locking depths in the San Francisco Bay area. Compared with our models of spatially variable locking distribution, models that assume a typical 15 km uniform locking depth overpredict the moment accumulation rate by a factor of 2-3 on the Peninsular San Andreas, Calaveras, Rodgers Creek, and Green Valley faults.

  10. Carbon and Nitrogen Accumulation Rates in Salt Marshes in Oregon, USA

    EPA Science Inventory

    Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...

  11. A True Eddy Accumulation - Eddy Covariance hybrid for measurements of turbulent trace gas fluxes

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas

    2016-04-01

    Eddy covariance (EC) is state-of-the-art in directly and continuously measuring turbulent fluxes of carbon dioxide and water vapor. However, low signal-to-noise ratios, high flow rates and missing or complex gas analyzers limit it's application to few scalars. True eddy accumulation, based on conditional sampling ideas by Desjardins in 1972, requires no fast response analyzers and is therefore potentially applicable to a wider range of scalars. Recently we showed possibly the first successful implementation of True Eddy Accumulation (TEA) measuring net ecosystem exchange of carbon dioxide of a grassland. However, most accumulation systems share the complexity of having to store discrete air samples in physical containers representing entire flux averaging intervals. The current study investigates merging principles of eddy accumulation and eddy covariance, which we here refer to as "true eddy accumulation in transient mode" (TEA-TM). This direct flux method TEA-TM combines true eddy accumulation with continuous sampling. The TEA-TM setup is simpler than discrete accumulation methods while avoiding the need for fast response gas analyzers and high flow rates required for EC. We implemented the proposed TEA-TM method and measured fluxes of carbon dioxide (CO2), methane (CH4) and water vapor (H2O) above a mixed beech forest at the Hainich Fluxnet and ICOS site, Germany, using a G2301 laser spectrometer (Picarro Inc., USA). We further simulated a TEA-TM sampling system using measured high frequency CO2 time series from an open-path gas analyzer. We operated TEA-TM side-by-side with open-, enclosed- and closed-path EC flux systems for CO2, H2O and CH4 (LI-7500, LI-7200, LI-6262, LI-7700, Licor, USA, and FGGA LGR, USA). First results show that TEA-TM CO2 fluxes were similar to EC fluxes. Remaining differences were similar to those between the three eddy covariance setups (open-, enclosed- and closed-path gas analyzers). Measured TEA-TM CO2 fluxes from our physical

  12. Carbon accumulation rates and the origin of the Holocene sapropel in the Black Sea

    NASA Astrophysics Data System (ADS)

    Calvert, S. E.; Vogel, J. S.; Southon, J. R.

    1987-10-01

    A detailed radiocarbon chronology obtained by accelerator mass spectrometry together with organic carbon and carbonate measurements on two Black Sea cores has been used to compare and contrast the burial fluxes of organic carbon in the Holocene sapropel and the modern sediment. At both deep-water and eastern-slope sites, the sapropel is separated from the modern facies by a variable thickness of compositionally homogeneous sediment with low levels of organic carbon and anomalously old radiocarbon ages. This homogeneous unit probably represents deposition by slumping or mudflow. The age limits of the sapropel are 1600 6600 B.P. at the deep-water site and 4000 6000 B.P. (radiocarbon years before 1950 A.D.) at the shallow-water site. The carbon accumulation rate in the deep-water sapropel is higher than that in the modern deep-water facies by a factor of 2 and is approximately the same as that in the modern sediment in shallow water. The revised chronology of sapropel formation and the differences in the carbon accumulation rates probably indicate that the sapropel was formed by increased production during the transition from the premodern lake to the modern marine phases of the Black Sea. This conclusion is consistent with the clear marine carbon-isotope signal in the organic matter in the sapropel in both cores (results to be reported elsewhere), in contrast to the mixed source of carbon in the other facies.

  13. Rating Scale Analysis. Rasch Measurement.

    ERIC Educational Resources Information Center

    Wright, Benjamin D.; Masters, Geofferey N.

    This book discusses constructing variables and making measures. It begins by outlining the qualities a number must meet before it qualifies as a measure of something. The basis is the measurement philosophy of G. Rasch. The first requirement for making good measures is good raw material. To achieve the possibility of comparisons, the data must…

  14. Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas

    USGS Publications Warehouse

    Shinn, E.A.; Hudson, J.H.; Halley, R.B.; Lidz, B.H.; Taylor, D.L.

    1977-01-01

    Core drilling and examination of underwater excavation on 6 reef sites in south Florida and Dry Tortugas revealed that underlying topography is the major factor controlling reef morphology. Carbon-14 dating on coral recovered from cores enables calculation of accumulation rates. Accumulation rates were found to range from 0.38 m/1000 years in thin Holocene reefs to as much as 4.85 m/1000 years in thicker buildups. Cementation and alteration of corals were found to be more pronounced in areas of low buildup rates than in areas of rapid accumulation rates. Acropora palmata, generally considered the major reef builder in Florida, was found to be absent in most reefs drilled. At Dry Tortugas, the more than 13-meter thick Holocene reef did not contain A. palmata. The principal reef builders in this outer reef are the same as those which built the Pleistocene Key Largo formation, long considered to be fossilized patch reef complex.

  15. Purification and partial kinetic and physical characterization of two NADP-specific glutamate dehydrogenase isoenzymes and their protein precursors, and measurement of the patterns of accumulation and rates of degradation of their nonidentical subunits in synchronized cells of Chlorella cultured in different concentrations of ammonia

    SciTech Connect

    Bascomb, N.F.

    1986-01-01

    Two ammonium-inducible, chloroplast-localized, NADP-specific glutamate dehydrogenases were purified from Chlorella sorokiniana. They were homopolymers of either alpha or beta subunits with molecular weights of 55,500 and 53,000, respectively. These isoenzymes were separated by their differential binding to the substrate affinity column. Peptide mapping of purified alpha and beta subunits showed them to have a high degree of sequence homology. By use of SDS slab-gel electrophoresis and a Western blot/immunodetection procedure, patterns of accumulation of alpha and beta subunits (in their holoenzyme) were measured in cells cultured in media, containing different concentrations of ammonia. Pulse-chase experiments with (/sup 35/S)sulfate were performed to measured the rates of degradation of the two isoenzymes. When the culture medium contained 2 mM ammonia or lower, cells accumulated only the alpha holoenzyme. Above 2 mM ammonia, cells contained both enzymes; however, their patterns of accumulation and rates of degradation were very different. The physiological role of alpha and beta holoenzymes appears to be ammonia assimilation at low and high external ammonia concentrations, respectively. From in vitro-translation studies with total cellular poly(A)/sup +/RNA, isolated from cells engaged in synthesis of alpha or beta holoenzymes or both, it was concluded that alpha and beta subunits have protein precursor(s) or identical molecular weight (M/sub r/ = 58,500). When the putative protein-precursor(s) were incubated in vitro, with cell-free extracts from Chlorella cells, they were processed to proteins the size of alpha and beta subunits.

  16. Impact Of Particle Agglomeration On Accumulation Rates In The Glass Discharge Riser Of HLW Melter

    SciTech Connect

    Kruger, A. A.; Rodriguez, C. A.; Matyas, J.; Owen, A. T.; Jansik, D. P.; Lang, J. B.

    2012-11-12

    The major factor limiting waste loading in continuous high-level radioactive waste (HLW) melters is an accumulation of particles in the glass discharge riser during a frequent and periodic idling of more than 20 days. An excessive accumulation can produce robust layers a few centimeters thick, which may clog the riser, preventing molten glass from being poured into canisters. Since the accumulation rate is driven by the size of particles we investigated with x-ray microtomography, scanning electron microscopy, and image analysis the impact of spinel forming components, noble metals, and alumina on the size, concentration, and spatial distribution of particles, and on the accumulation rate. Increased concentrations of Fe and Ni in the baseline glass resulted in the formation of large agglomerates that grew over the time to an average size of ~185+-155 {mu}m, and produced >3 mm thick layer after 120 h at 850 deg C. The noble metals decreased the particle size, and therefore significantly slowed down the accumulation rate. Addition of alumina resulted in the formation of a network of spinel dendrites which prevented accumulation of particles into compact layers.

  17. Verification of International Space Station Component Leak Rates by Helium Accumulation Method

    NASA Technical Reports Server (NTRS)

    Underwood, Steve D.; Smith, Sherry L.

    2003-01-01

    Discovery of leakage on several International Space Station U.S. Laboratory Module ammonia system quick disconnects (QDs) led to the need for a process to quantify total leakage without removing the QDs from the system. An innovative solution was proposed allowing quantitative leak rate measurement at ambient external pressure without QD removal. The method utilizes a helium mass spectrometer configured in the detector probe mode to determine helium leak rates inside a containment hood installed on the test component. The method was validated through extensive developmental testing. Test results showed the method was viable, accurate and repeatable for a wide range of leak rates. The accumulation method has been accepted by NASA and is currently being used by Boeing Huntsville, Boeing Kennedy Space Center and Boeing Johnson Space Center to test welds and valves and will be used by Alenia to test the Cupola. The method has been used in place of more expensive vacuum chamber testing which requires removing the test component from the system.

  18. Ice shelf snow accumulation rates from the Amundsen-Bellingshausen Sea sector of West Antarctica derived from airborne radar

    NASA Astrophysics Data System (ADS)

    Medley, B.; Kurtz, N. T.; Brunt, K. M.

    2015-12-01

    The large ice shelves surrounding the Antarctic continent buttress inland ice, limiting the grounded ice-sheet flow. Many, but not all, of the thick ice shelves located along the Amundsen-Bellingshausen Seas are experiencing rapid thinning due to enhanced basal melting driven by the intrusion of warm circumpolar deep water. Determination of their mass balance provides an indicator as to the future of the shelves buttressing capability; however, measurements of surface accumulation are few, limiting the precision of the mass balance estimates. Here, we present new radar-derived measurements of snow accumulation primarily over the Getz and Abbott Ice Shelves, as well as the Dotson and Crosson, which have been the focus of several of NASA's Operation IceBridge airborne surveys between 2009 and 2014. Specifically, we use the Center for Remote Sensing of Ice Sheets (CReSIS) snow radar to map the near-surface (< 30 m) internal stratigraphy to measure snow accumulation. Due to the complexities of the local topography (e.g., ice rises and rumples) and their relative proximity to the ocean, the spatial pattern of accumulation can be equally varied. Therefore, atmospheric models might not be able to reproduce these small-scale features because of their limited spatial resolution. To evaluate whether this is the case over these narrow shelves, we will compare the radar-derived accumulation rates with those from atmospheric models.

  19. Large scale spatial variation of accumulation rate across ice promontory in coastal Dronning Maud Land, Antarctica.

    NASA Astrophysics Data System (ADS)

    Callens, Denis; Matsuoka, Kenichi; Drews, Reinhard; Pattyn, Frank

    2013-04-01

    Ice rises are known to play a key role on ice shelf dynamics. By buttressing the flow, they constrain the flow of ice from the continent toward the ocean. However, since they are small hills surrounded by extremely flat area, they also play a role on atmospheric circulation. However, this impact is relatively unknown. Here, we show evidence that ice rises play a significant role on the wind redistribution of the snow. We report observations of persistent features observed all around the coast of Dronning Maud Land (DML). By analyzing radio-echo sounding data, we identified internal reflection horizons assumed to be isochronous. These layers show a remarkable variability in layer depth at both sides of the ridge, pointing to variability in surface accumulation rates. We show that a strong gradient of accumulation rate exist across, at least, 5 different ice rises in DML : Halvfarryggen Ice Rise nearby Ekstromisen (7°W), 2 ice rises into the Fimbulisen (2°E) and 2 ice rises within the Roi Baudoin Ice Shelf (25°E, Derwael & FranKenny Ice Rise). We used deepness of radar reflector as a proxy of the accumulation rate as long as we removed the influence of ice dynamics. All collected data (both low and high frequency) all show the similar persistent gradient in accumulation rate. Comparison of accumulation rate distribution and meteorological data shows that accumulation rate is twice as high on the wind side of the ridge compared to the lee side, which makes ice rise topography playing a significant role in snow redistribution. This feature is important in term of ice coring and paleoclimatic reconstruction of on time scales of 2 to 20k years.

  20. Incorporation of radiometric tracers in peat and implications for estimating accumulation rates.

    PubMed

    Hansson, Sophia V; Kaste, James M; Olid, Carolina; Bindler, Richard

    2014-09-15

    Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides (210)Pb, (137)Cs, (241)Am, and (7)Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of (7)Be down to 18-20 cm for some cores, and the broad vertical distribution of (241)Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age-depth model leads to unrealistic peat mass accumulation rates (400-600 g m(-2) yr(-1)), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of (210)Pb through the uppermost peat layers, recent peat accumulation rates (200-300 g m(-2) yr(-1)) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using (7)Be, and if this information is incorporated into age-depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.

  1. T1 Relaxation Rate (R1) Indicates Nonlinear Mn Accumulation in Brain Tissue of Welders With Low-Level Exposure

    PubMed Central

    Lee, Eun-Young; Flynn, Michael R.; Du, Guangwei; Lewis, Mechelle M.; Fry, Rebecca; Herring, Amy H.; Van Buren, Eric; Van Buren, Scott; Smeester, Lisa; Kong, Lan; Yang, Qing; Mailman, Richard B.; Huang, Xuemei

    2015-01-01

    Although the essential element manganese (Mn) is neurotoxic at high doses, the effects of lower exposure are unclear. MRI T1-weighted (TIW) imaging has been used to estimate brain Mn exposure via the pallidal index (PI), defined as the T1W intensity ratio in the globus pallidus (GP) versus frontal white matter (FWM). PI may not, however, be sensitive to Mn in GP because Mn also may accumulate in FWM. This study explored: (1) whether T1 relaxation rate (R1) could quantify brain Mn accumulation more sensitively; and (2) the dose-response relationship between estimated Mn exposure and T1 relaxation rate (R1). Thirty-five active welders and 30 controls were studied. Occupational questionnaires were used to estimate hours welding in the past 90 days (HrsW) and lifetime measures of Mn exposure. T1W imaging and T1-measurement were utilized to generate PI and R1 values in brain regions of interest (ROIs). PI did not show a significant association with any measure of Mn and/or welding-related exposure. Conversely, in several ROIs, R1 showed a nonlinear relationship to HrsW, with R1 signal increasing only after a critical exposure was reached. The GP had the greatest rate of Mn accumulation. Welders with higher exposure showed significantly higher R1 compared either with controls or with welders with lower exposure. Our data are additional evidence that Mn accumulation can be assessed more sensitively by R1 than by PI. Moreover, the nonlinear relationship between welding exposure and Mn brain accumulation should be considered in future studies and policies. PMID:25953701

  2. Greenland annual accumulation along the EGIG line, 1959-2004, from ASIRAS airborne radar and neutron-probe density measurements

    NASA Astrophysics Data System (ADS)

    Overly, Thomas B.; Hawley, Robert L.; Helm, Veit; Morris, Elizabeth M.; Chaudhary, Rohan N.

    2016-08-01

    We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and high resolution neutron-probe (NP) density profiles. ASIRAS-NP-derived accumulation rates are not statistically different (95 % confidence interval) from in situ EGIG accumulation measurements from 1985 to 2004. ASIRAS-NP-derived accumulation increases by 20 % below 3000 m elevation, and increases by 13 % above 3000 m elevation for the period 1995 to 2004 compared to 1985 to 1994. Three Regional Climate Models (PolarMM5, RACMO2.3, MAR) underestimate snow accumulation below 3000 m by 16-20 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modeled density profiles in place of NP densities. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates in the dry snow region. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the Operation IceBridge campaign.

  3. What to Look for in the Accumulator Core Cooling Signal Suppression Measurements

    SciTech Connect

    Sondgeroth, Al; Vander Meulen, Dave; /Fermilab

    2001-01-01

    This document explains what to look for in the signal suppression display produced by program P192 Pbar Accumulator Core Cooling Suppression Measurement. First we will give a quick overview of beam cooling and why we measure signal suppression. Beam cooling is a technique whereby the physical size and energy spread of a particle beam circulating in a storage ring is reduced without any accompanying beam loss. The goal is to compress the same number of particles into a beam of smaller size and energy spread. This is desirable for the Accumulator as it compensates for various mechanisms leading to growth of beamsize and/or loss of stored particles and makes space available so that more beam can be stored. It also allows us to provide a low emittance beam through the Main Injector into the Tevatron in order to maximize the collision rate. For further information on specific stochastic cooling systems see Chapter 5 of the Antiproton Source Rookie Book.

  4. Nutritive Value and Herbage Accumulation Rates of Pasture Sown to Grass, Legume, and Chicory

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Planting pastures to mixtures of forages may benefit herbage production; however, wide fluctuations in botanical composition could cause unstable nutritive value. A grazing study was conducted to examine how forage mixture complexity influenced nutritive value and accumulation rate during spring, su...

  5. Distinct mutation accumulation rates among tissues determine the variation in cancer risk

    PubMed Central

    Hao, Dapeng; Wang, Li; Di, Li-jun

    2016-01-01

    Cancer is believed to be a result of accumulated mutations. However, this concept has not been fully confirmed owing to the impossibility of tracking down the ancestral somatic cell. We sought to verify the concept by exploring the correlation between cancer risk and mutation accumulation among different tissues. We hypothesized that the detected mutations through bulk tumor sequencing are commonly shared in majority, if not all, of tumor cells and are therefore largely a reflection of the mutations accumulated in the ancestral cell that gives rise to tumor. We collected a comprehensive list of mutation frequencies revealed by bulk tumor sequencing, and investigated its correlation with cancer risk to mirror the correlation between mutation accumulation and cancer risk. This revealed an approximate 1:1 relationship between mutation frequency and cancer risk in 41 different cancer types based on the sequencing data of 5,542 patients. The correlation strongly suggests that variation in cancer risk among tissues is mainly attributable to distinct mutation accumulation rates. Moreover, the correlation establishes a baseline to evaluate the effect of non-mutagenic carcinogens on cancer risk. Finally, our mathematic modeling provides a reasonable explanation to reinforce that cancer risk is predominantly determined by the first rate-limiting mutation. PMID:26785814

  6. Tracing nitrogen accumulation in decaying wood and examining its impact on wood decomposition rate

    NASA Astrophysics Data System (ADS)

    Rinne, Katja T.; Rajala, Tiina; Peltoniemi, Krista; Chen, Janet; Smolander, Aino; Mäkipää, Raisa

    2016-04-01

    Decomposition of dead wood, which is controlled primarily by fungi is important for ecosystem carbon cycle and has potentially a significant role in nitrogen fixation via diazotrophs. Nitrogen content has been found to increase with advancing wood decay in several studies; however, the importance of this increase to decay rate and the sources of external nitrogen remain unclear. Improved knowledge of the temporal dynamics of wood decomposition rate and nitrogen accumulation in wood as well as the drivers of the two processes would be important for carbon and nitrogen models dealing with ecosystem responses to climate change. To tackle these questions we applied several analytical methods on Norway spruce logs from Lapinjärvi, Finland. We incubated wood samples (density classes from I to V, n=49) in different temperatures (from 8.5oC to 41oC, n=7). After a common seven day pre-incubation period at 14.5oC, the bottles were incubated six days in their designated temperature prior to CO2 flux measurements with GC to determine the decomposition rate. N2 fixation was measured with acetylene reduction assay after further 48 hour incubation. In addition, fungal DNA, (MiSeq Illumina) δ15N and N% composition of wood for samples incubated at 14.5oC were determined. Radiocarbon method was applied to obtain age distribution for the density classes. The asymbiotic N2 fixation rate was clearly dependent on the stage of wood decay and increased from stage I to stage IV but was substantially reduced in stage V. CO2 production was highest in the intermediate decay stage (classes II-IV). Both N2 fixation and CO2 production were highly temperature sensitive having optima in temperature 25oC and 31oC, respectively. We calculated the variation of annual levels of respiration and N2 fixation per hectare for the study site, and used the latter data together with the 14C results to determine the amount of N2 accumulated in wood in time. The proportion of total nitrogen in wood

  7. Hydroacoustic and spatial analysis of sediment fluxes and accumulation rates in two Virginia reservoirs, USA.

    PubMed

    Clark, E V; Odhiambo, B K; Yoon, S; Pilati, L

    2015-06-01

    Watershed sediment fluxes and reservoir sediment accumulation rates were analyzed in two contrasting reservoir systems in central and western Virginia. Lake Pelham, located in the Piedmont geologic province, is a human-impacted reservoir with a watershed dominated by agricultural, residential and industrial land uses. Conversely, Lake Moomaw has a largely undeveloped watershed characterized by very steep slopes and forested land use located in the Valley and Ridge province. The Revised Universal Soil Loss Equation (RUSLE) and sediment delivery ratios (SDRs) were used to estimate soil losses in the two watersheds. Bathymetric and sediment accumulation surveys of the two reservoirs were also conducted using a multi-frequency hydroacoustic surveying system. The RUSLE/SDR erosion model estimates 2150 kg ha(-1) year(-1) for Lake Pelham and 2720 kg ha(-1) year(-1) for Lake Moomaw, a 410 and 13 % increase from assumed pristine (100 % forested) land use for the respective basins. Mean sediment accumulation rates of 1.51 and 0.60 cm year(-1) were estimated from the hydroacoustic survey of Lake Pelham and Lake Moomaw, respectively. Overall, Lake Moomaw has relatively low sediment accumulation rates; however, the reservoir is vulnerable to increases in sediment fluxes with further human development due to the steep slopes and highly erodible colluvial soils that characterize the basin. Higher erosion and sediment accumulation rates in Lake Pelham are most likely reflecting the impact of human development on sedimentation processes, where the loss of vegetal buffers and increase in impervious surfaces exacerbates both the surficial soil losses as well as intrinsic stream sediment production leading to the current annual reservoir capacity loss of 0.4 %.

  8. Greenland snow accumulation rates estimated by the retracking of percolation facies from airborne radar

    NASA Astrophysics Data System (ADS)

    de la Pena, S.; Howat, I. M.

    2012-12-01

    The margins of the Greenland Ice Sheet are experiencing substantial thinning due to warming in the arctic regions, and there is a growing concern about the effects that mass imbalance of the ice sheet could have on climate and sea level rise. Although volume changes of the ice sheet may be inferred by remote sensing methods, mass gain and accumulation fluctuations are not easily distinguished and are poorly resolved. Recent advances in airborne radar techniques have resulted in systems capable of resolving snow accumulation by retracking internal layers formed by refreezing of surface meltwater that percolates through the snowpack, a phenomenon increasingly common in Greenland. We present accumulation rates for the catchment areas of the Jakobshavn, Helheim, and Rusell glaciers derived from snow depth resolved by snow and Ku-band airborne radar, flown as part of NASA's Operation IceBridge.

  9. Relationships between salinity and short-term soil carbon accumulation rates form marsh types across a landscape in the Mississippi River Delta

    USGS Publications Warehouse

    Baustian, Melissa M.; Stagg, Camille L.; Perry, Carey L; Moss, Leland C; Carruthers, Tim J.B.; Allison, Mead

    2017-01-01

    Salinity alterations will likely change the plant and environmental characteristics in coastal marshes thereby influencing soil carbon accumulation rates. Coastal Louisiana marshes have been historically classified as fresh, intermediate, brackish, or saline based on resident plant community and position along a salinity gradient. Short-term total carbon accumulation rates were assessed by collecting 10-cm deep soil cores at 24 sites located in marshes spanning the salinity gradient. Bulk density, total carbon content, and the short-term accretion rates obtained with feldspar horizon markers were measured to determine total carbon accumulation rates. Despite some significant differences in soil properties among marsh types, the mean total carbon accumulation rates among marsh types were not significantly different (mean ± std. err. of 190 ± 27 g TC m−2 year−1). However, regression analysis indicated that mean annual surface salinity had a significant negative relationship with total carbon accumulation rates. Based on both analyses, the coastal Louisiana total marsh area (1,433,700 ha) accumulates about 2.7 to 3.3 Tg C year−1. Changing salinities due to increasing relative sea level or resulting from restoration activities may alter carbon accumulation rates in the short term and significantly influence the global carbon cycle.

  10. The distribution of the heavy metal accumulation rate in the biomass of three Daphnia species

    SciTech Connect

    Gajula, V.K.; Hovorka, J.; Stuchlik, E.

    1995-12-31

    The difference in the accumulation rate of a mixture of heavy metals in aquatic organisms is of considerable interest because of its importance in the prediction of the effect of pollutants in aquatic systems. In this study the authors are making an effort to evaluate the accumulation patterns of pollutants in aquatic organisms by establishing a relation between the level of an accumulated mixture of heavy metals (Cd, Zn, Pb, As, Hg) in individuals of Daphnia magna, Daphnia pulicaria and Daphnia galeata and its dry weight with respect to the form of heavy metals in the aquatic environment. One age group of Daphnia species (10 day old) were exposed to 5 ppb, 10 ppb and 20 ppb of the mixture of heavy metals for 24 hours in three different experiments. In the first experiment the mixture of heavy metals was present exclusively in labelled algae (Scendesmus actus), in the second in an aquatic medium with non labelled algae, and in the third experiment the mixture of heavy metals was dissolved in the aquatic medium only without the addition of algae. The concentration of the heavy metal mixture in individuals of D.magna; D.pulicaria and D.galeata was determined using atomic absorption spectrometry. Results were statistically evaluated and the rate of accumulation and influence of various heavy metals in the biomass of three Daphnia species is discussed.

  11. A high-frequency response relaxed eddy accumulation flux measurement system for sampling short-lived biogenic volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Arnts, Robert R.; Mowry, Fred L.; Hampton, Gary A.

    2013-05-01

    second-generation relaxed eddy accumulation system was built and tested with the capability to measure vertical biogenic volatile organic compound (VOC) fluxes at levels as low as 10 µg C m-2 hr-1. The system features a continuous, integrated gas-phase ozone removal procedure to allow for the measurement of highly reactive species such as β-caryophyllene and polar terpenoids such as linalool. A two-component internal standard continuously added to the accumulators was used to correct for switching-induced volumetric errors and as a check on VOC losses exceeding accumulator tube adsorption limits. In addition, the internal standards were used to demonstrate that accumulators quickly return to target flow rates at segregation valve switching frequencies up to at least 0.8 Hz. The system was able to measure daytime hourly fluxes of individual biogenic VOC including oxygenated terpenoids, monoterpenes, and sesquiterpenes.

  12. Daily accumulation rates of marine debris on sub-Antarctic island beaches.

    PubMed

    Eriksson, Cecilia; Burton, Harry; Fitch, Stuart; Schulz, Martin; van den Hoff, John

    2013-01-15

    The worlds' oceans contain a large but unknown amount of plastic debris. We made daily collections of marine debris stranded at two sub-Antarctic islands to establish (a) physical causes of strandings, and (b) a sampling protocol to better estimate the oceans' plastic loading. Accumulation rates at some beaches were dependent on tide and onshore winds. Most of the 6389 items collected were plastic (Macquarie 95%, Heard 94%) and discarded or lost fishing gear comprised 22% of those plastic items. Stalked barnacles (Lepas spp.) were a regular attachment on Macquarie debris but not at Heard Island. The daily accumulation rate of plastic debris on Macquarie Island was an order of magnitude higher than that estimated from monthly surveys during the same 4 months in the previous 5 years. This finding suggests that estimates of the oceans' plastic loading are an order of magnitude too low.

  13. Sedimentology of Southwestern Roads region, U.S. Virgin Islands: origin and rate of sediment accumulation

    USGS Publications Warehouse

    Kindinger, Jack G.; Miller, Ronald J.; Holmes, Charles W.

    1983-01-01

    Sand deposits on southern insular shelf of St. Thomas, U.S. Virgin Islands, were investigated to determine their origin, environmental processes and accumulation rates. Sea-floor samples show that the sand has been derived (in situ) mainly from calcareous algae and molluscs. Zonation of the dominant sand producers is related to the present environmental setting; water depth has the greatest influence. Carbon-14 data (bulk sample) of cores indicate accumulation rates of slightly less than 1 mm/year for the last 5,000 years. Faunal studies show that the climate has remained constant over the past 5,000 years. The only changes in environmental conditions appear to have been an increase in water depth, changes in the patterns of water movement, and an increase in water temperature.

  14. Trawling-induced alterations of deep-sea sediment accumulation rates during the Anthropocene

    NASA Astrophysics Data System (ADS)

    Puig, P.; Paradis, S.; Masque, P.; Martin, J.; Juan, X.; Palanques, A.

    2015-12-01

    Commercial bottom trawling causes direct physical disturbance of the marine sedimentary environments by scraping and ploughing the seabed, generating periodic resuspension of surface sediments. However, the quantification of the sediment that is removed by trawling and exported across the continental margin remains largely unaddressed, and the preservation of the signal of such impacts in the geological record have been mostly overlooked. The analysis of sediment cores collected along the Catalan margin (NW Mediterranean) has allowed evaluating the contribution of this anthropogenic activity to the present-day sediment dynamics. Sediment cores at intensively trawled sites are characterized by over-consolidated sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sedimentary deposits. In turn, combined 210Pb and 137Cs chronologies indicate a significant increase of sediment accumulation rates within submarine canyon environments since the 1970s, coincidently with a strong impulse in the industrialization of the trawling fleets of this region. Two sampling sites that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied 1-2 decades after the first studies and revealed a second and even larger increase of sediment accumulation rates (>2 cm/y) occurring at the beginning of the XXI century. This recent change has been attributed to a preferential displacement of the trawling fleet towards fishing grounds surrounding submarine canyons and, also, to technical improvements in trawling vessels, presumably related to financial subsidies provided to the fishing sector. The alteration of sediment accumulation rates described in this continental margin may occur in many regions of the World's oceans given the wide geographical distribution of this human activity, and therefore, it could represent a potential marker of the Anthropocene in deep-sea environments.

  15. Balancing sample accumulation and DNA degradation rates to optimize noninvasive genetic sampling of sympatric carnivores.

    PubMed

    Lonsinger, Robert C; Gese, Eric M; Dempsey, Steven J; Kluever, Bryan M; Johnson, Timothy R; Waits, Lisette P

    2015-07-01

    Noninvasive genetic sampling, or noninvasive DNA sampling (NDS), can be an effective monitoring approach for elusive, wide-ranging species at low densities. However, few studies have attempted to maximize sampling efficiency. We present a model for combining sample accumulation and DNA degradation to identify the most efficient (i.e. minimal cost per successful sample) NDS temporal design for capture-recapture analyses. We use scat accumulation and faecal DNA degradation rates for two sympatric carnivores, kit fox (Vulpes macrotis) and coyote (Canis latrans) across two seasons (summer and winter) in Utah, USA, to demonstrate implementation of this approach. We estimated scat accumulation rates by clearing and surveying transects for scats. We evaluated mitochondrial (mtDNA) and nuclear (nDNA) DNA amplification success for faecal DNA samples under natural field conditions for 20 fresh scats/species/season from <1-112 days. Mean accumulation rates were nearly three times greater for coyotes (0.076 scats/km/day) than foxes (0.029 scats/km/day) across seasons. Across species and seasons, mtDNA amplification success was ≥95% through day 21. Fox nDNA amplification success was ≥70% through day 21 across seasons. Coyote nDNA success was ≥70% through day 21 in winter, but declined to <50% by day 7 in summer. We identified a common temporal sampling frame of approximately 14 days that allowed species to be monitored simultaneously, further reducing time, survey effort and costs. Our results suggest that when conducting repeated surveys for capture-recapture analyses, overall cost-efficiency for NDS may be improved with a temporal design that balances field and laboratory costs along with deposition and degradation rates.

  16. Rates of Species Accumulation and Taxonomic Diversification during Phototrophic Biofilm Development Are Controlled by both Nutrient Supply and Current Velocity

    PubMed Central

    2013-01-01

    The accumulation of new and taxonomically diverse species is a marked feature of community development, but the role of the environment in this process is not well understood. To address this problem, we subjected periphyton in laboratory streams to low (10-cm · s−1), high (30-cm · s−1), and variable (9- to 32-cm · s−1) current velocity and low- versus high-nutrient inputs. We examined how current velocity and resource supply constrained (i) the rates of species accumulation, a measure of temporal beta-diversity, and (ii) the rates of diversification of higher taxonomic categories, defined here as the rate of higher taxon richness increase with the increase of species richness. Temporal biofilm dynamics were controlled by a strong nutrient-current interaction. Nutrients accelerated the rates of accumulation of new species, when flow velocity was not too stressful. Species were more taxonomically diverse under variable than under low-flow conditions, indicating that flow heterogeneity increased the niche diversity in the high-nutrient treatments. Conversely, the lower diversification rates under high- than under low-nutrient conditions at low velocity are explained with finer resource partitioning among species, belonging to a limited number of related genera. The overall low rates of diversification in high-current treatments suggest that the ability to withstand current stress was conserved within closely related species. Temporal heterogeneity of disturbance has been shown to promote species richness, but here we further demonstrate that it also affects two other components of biodiversity, i.e., temporal beta-diversity and diversification rate. Therefore, management efforts for preserving the inherent temporal heterogeneity of natural ecosystems will have detectable positive effects on biodiversity. PMID:23335757

  17. The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast.

    PubMed

    Lee, Richard F; Sanders, Dorothea P

    2015-02-15

    The amount and accumulation rate of plastic debris at 20 sites along the Georgia coast were prepared using data reported by a number of volunteer organizations. The amount of plastic debris at highly visited barrier island beaches and estuarine marshes ranged from 300 to >1000 kg. Relatively large amount of plastics (180-500 kg) were found on less visited barrier island beaches, i.e. Blackbeard, Ossabaw and Cumberland Islands. A follow up monthly or quarterly collection study was carried out on two of the sites, a barrier beach and estuarine marsh, to determine accumulation rate in 8000 m(2) areas. Accumulation rates ranged from 0.18 to 1.28 kg/30 days-8000 m(2) on the barrier island beach and from 0.6 to 1.61 kg/30 days-8000 m(2) at the estuarine marsh site. The major type of plastics, e.g. bottles, food wrappers, plastic fragments, was highly variable at different seasons and sites. The authors recommend consideration of a standardization in reporting plastic debris, with respect to quantitation of debris and sample area.

  18. Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary

    USGS Publications Warehouse

    Lewis, R.C.; Coale, K.H.; Edwards, B.D.; Marot, M.; Douglas, J.N.; Burton, E.J.

    2002-01-01

    The distribution of excess 210Pb in 31 sediment cores was used to determine modern (last 100 yr) mass accumulation rates and the depth of sediment mixing on the continental shelf between Pacifica and Monterey, California, USA. Apparent mass accumulation rates average 0.27 g cm-2 yr-1 and range from 0.42 g cm-2 yr-1 to 0.12 g cm-2 yr-1. Accumulation rates were highest at mid-shelf water depths (60-100 m) adjacent to major rivers and near the head of the Ascension submarine canyon. Cores from water depths of less than 65 m had low, uniform 210Pb activity profiles and sandy textures. The uppermost 5-13 cm of 15 cores had uniform 210Pb activity profiles above a region of steadily decreasing 210Pb activity. This phenomenon was attributed to sediment mixing. The thickness of this upper layer of uniform 210Pb activity decreased southward from 13 cm, west of Pacifica, to less than 5 cm, near Monterey Canyon. This southward decrease may be attributed to shallower bioturbation in the southern study area. Integrated excess 210Pb activities were generally higher where sedimentation rates were high. They were also higher with increasing distance from major rivers. Thus, sedimentation rate alone does not explain the distribution of integrated excess 210Pb in this study area. Excess 210Pb in the seafloor is controlled by other factors such as sediment texture, the atmospheric deposition rate of 210Pb, and the residence time of sediment particles in the water column. ?? 2002 Elsevier Science B.V. All rights reserved.

  19. Impact of Megadunes and Glaze Areas on Estimates of East Antarctic Mass Balance and Accumulation Rate Change

    NASA Astrophysics Data System (ADS)

    Scambos, T. A.; Fahnestock, M. A.; Shuman, C.; Haran, T. M.

    2006-12-01

    for megadunes, glaze regions, and undulations in East Antarctica (and elsewhere) may also impact estimates of changes in accumulation rate (changes in surface elevation due to accumulation increase or decrease) when those changes are made by satellite radar altimeters (e.g. Davis et al, 2005). Previous studies have demonstrated that the broad footprint of satellite radar altimeters interacts preferentially with local highs in the topography; however, local highs show an amplified accumulation signal relative to the regional net surface flux. Therefore, changes in the net surface flux would also be amplified at the local crests, and could cause satellite radar change detection values to be overestimated. We present a simple model of this effect based on the megadune field measurements.

  20. River sediment flux and shelf sediment accumulation rates on the Pacific Northwest margin

    NASA Astrophysics Data System (ADS)

    Wheatcroft, R. A.; Sommerfield, C. K.

    2005-02-01

    To test the generality of insight obtained from recent STRATAFORM studies of northern California's Eel margin, river sediment sources and continental shelf sinks were examined on the Pacific Northwest margin from 38° to 44.5°N. River discharge and sediment concentration data acquired by the US Geological Survey were used to update long-term annual suspended-sediment loads for 17 rivers that range in basin area from 635 to ˜22,000 km 2. Resulting annual load estimates vary over 3 orders of magnitude (0.065-18×10 9 kg/yr), with major suspended-sediment fluxes supplied by, in decreasing order, the Eel, Klamath/Trinity, Mad, Rogue, Umpqua and Russian rivers. Down-core profiles of excess 210Pb and 137Cs were used to estimate sediment accumulation rates (SARs) at prescribed depths (70 and 110 m) and distances (0-40-km north and south along-shelf) from each of the major rivers. SARs were found to vary much less than the river flux estimates, and are mostly in the range of 1.5 to 6 mm/yr. Most significantly, shelf SARs on the other Pacific Northwest margins are only slightly less than those observed on the Eel shelf, implying that much higher proportions of riverine sediment are retained on those shelves. Likely reasons that the Eel dispersal system exhibits greater off-shelf transport are (1) the narrower and steeper shelf geometry, and (2) the existence of a newly documented cross-isobath sediment transport mechanism that involves wave-modulated fluid mud flows. Testing whether the fluid mud flows are a consequence of the Eel River basin's high sediment yield, and are thus unique to the Eel, or are caused by intense wave energy during discharge events, and hence are operative on many other margins, awaits future bottom-boundary layer measurements.

  1. Glass dissolution rate measurement and calculation revisited

    NASA Astrophysics Data System (ADS)

    Fournier, Maxime; Ull, Aurélien; Nicoleau, Elodie; Inagaki, Yaohiro; Odorico, Michaël; Frugier, Pierre; Gin, Stéphane

    2016-08-01

    Aqueous dissolution rate measurements of nuclear glasses are a key step in the long-term behavior study of such waste forms. These rates are routinely normalized to the glass surface area in contact with solution, and experiments are very often carried out using crushed materials. Various methods have been implemented to determine the surface area of such glass powders, leading to differing values, with the notion of the reactive surface area of crushed glass remaining vague. In this study, around forty initial dissolution rate measurements were conducted following static and flow rate (SPFT, MCFT) measurement protocols at 90 °C, pH 10. The international reference glass (ISG), in the forms of powders with different particle sizes and polished monoliths, and soda-lime glass beads were examined. Although crushed glass grains clearly cannot be assimilated with spheres, it is when using the samples geometric surface (Sgeo) that the rates measured on powders are closest to those found for monoliths. Overestimation of the reactive surface when using the BET model (SBET) may be due to small physical features at the atomic scale-contributing to BET surface area but not to AFM surface area. Such features are very small compared with the thickness of water ingress in glass (a few hundred nanometers) and should not be considered in rate calculations. With a SBET/Sgeo ratio of 2.5 ± 0.2 for ISG powders, it is shown here that rates measured on powders and normalized to Sgeo should be divided by 1.3 and rates normalized to SBET should be multiplied by 1.9 in order to be compared with rates measured on a monolith. The use of glass beads indicates that the geometric surface gives a good estimation of glass reactive surface if sample geometry can be precisely described. Although data clearly shows the repeatability of measurements, results must be given with a high uncertainty of approximately ±25%.

  2. Systems Level Regulation of Rhythmic Growth Rate and Biomass Accumulation in Grasses

    SciTech Connect

    Kay, Steve A.

    2013-05-02

    Several breakthroughs have been recently made in our understanding of plant growth and biomass accumulation. It was found that plant growth is rhythmically controlled throughout the day by the circadian clock through a complex interplay of light and phytohormone signaling pathways. While plants such as the C4 energy crop sorghum (Sorghum bicolor (L.) Moench) and possibly the C3 grass (Brachypodium distachyon) also exhibit daily rhythms in growth rate, the molecular details of its regulation remain to be explored. A better understanding of diurnally regulated growth behavior in grasses may lead to species-specific mechanisms highly relevant to future strategies to optimize energy crop biomass yield. Here we propose to devise a systems approach to identify, in parallel, regulatory hubs associated with rhythmic growth in C3 and C4 plants. We propose to use rhythmicity in daily growth patterns to drive the discovery of regulatory network modules controlling biomass accumulation.

  3. LATE CENOZOIC INCREASE IN ACCUMULATION RATES OF TERRESTRIAL SEDIMENT: How Might Climate Change Have Affected Erosion Rates?

    NASA Astrophysics Data System (ADS)

    Molnar, Peter

    2004-05-01

    Accumulation rates of terrestrial sediment have increased in the past few million years both on and adjacent to continents, although not everywhere. Apparently, erosion has increased in elevated terrain regardless of when last tectonically active or what the present-day climate. In many regions, sediment coarsened abruptly in late Pliocene time. Sparser data suggest increased sedimentation rates at 15 Ma, approximately when oxygen isotopes in benthic foraminifera imply high-latitude cooling. If climate change effected accelerated erosion, understanding how it did so remains the challenge. Some obvious candidates, such as lowered sea level leading to erosion of continental shelves or increased glaciation, account for increased sedimentation in some, but not all, areas. Perhaps stable climates that varied slowly allowed geomorphic processes to maintain a state of equilibrium with little erosion until 34 Ma, when large oscillations in climate with periods of 20,00040,000 years developed and denied the landscape the chance to reach equilibrium.

  4. Radionuclide activities, geochemistry, and accumulation rates of sediments in the Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Srisuksawad, Kanitha; Porntepkasemsan, Boonsom; Nouchpramool, Sunun; Yamkate, Pathom; Carpenter, Roy; Peterson, Michael L.; Hamilton, Terry

    1997-07-01

    Downcore concentration profiles of 210Pb, U, and Th isotopes, Al, Fe, Ti, Mn and Sc were measured in sediment box cores collected at 22 stations (16-70 m water depth) covering most of the Thai zone of the Gulf of Thailand. Distributions of excess 210Pb and the detrital elements were used to study spatial variations in sedimentary processes, mineralogy, and geochemistry between different regions of the gulf. Steady-state depositional concentrations and fluxes of excess 210Pb are 3-10 times lower in Gulf of Thailand sediments than in sediments from mid-latitudes in the northern hemisphere, reflecting lower 210Pb inputs from atmospheric fallout at 6-13°N latitude and from lower production of 210Pb from 226Ra in the shallower waters of the Gulf. U and Th concentrations are approximately 2-3 times higher than those in shelf sediments from mid-latitudes of North America, consistent with a higher proportion of granitic source rocks in the Thai environment. Downcore variations in 228Th/ 232Th activity ratios and in U activities reveal that exchange of interstitial and overlying waters and their dissolved chemicals occurs down to 20 cm in 8 of 10 cores. This benthic exchange may be important in budgets of fluxes of other soluble chemicals in this shallow shelf sea. A net flux of U isotopes from overlying water into Gulf of Thailand sediments occurs, in contrast to their release from sediments of the tropical Amazon shelf. Detectable levels of 137Cs were found only in sediments near the mouth of the largest river, the Chao Phraya. The detrital elements 232Th, 230Th, Al, Ti, and Sc all show relatively uniform downcore concentration profiles. This supports a key assumption in calculations of sediment accumulation rates from downcore profiles of 210Pb activity, that steady-state depositional conditions exist and that basic sediment mineralogy and grain size does not change. 210Pb model derived mass accumulation rates vary between 270 and 490 mg/cm 2 per year in the upper Gulf

  5. Regulation of Activation-associated MicroRNA Accumulation Rates during Monocyte-to-macrophage Differentiation*

    PubMed Central

    Eigsti, Renee L.; Sudan, Bayan; Wilson, Mary E.; Graff, Joel W.

    2014-01-01

    Circulating monocytes recruited to tissues can differentiate into macrophages and adopt unique gene expression programs in response to environmental cues. We recently described the regulated expression of several microRNAs (miRNAs) in polarized human monocyte-derived macrophages (MDMs). Basal expression of these activation-associated miRNAs was low in monocytes relative to MDMs. As development occurs in the context of specific cellular environments, we hypothesized that the rate of miRNA accumulation would be modified in the presence of microbial or cellular products during monocyte-to-macrophage differentiation. Indeed, LPS treatment augmented the accumulation of miR-146a and miR-155, whereas IL-4 treatment augmented the accumulation of miR-193b and miR-222 during development. In contrast, some stimuli repressed accumulation of specific miRNAs including interferons (IFNs) (miR-27a, miR-125a-5p, and miR-222), IL-4 (miR-125a-5p), and LPS (miR-27a). RT-PCR-based expression profiling of monocytes differentiated with distinct methods showed that activation-associated miRNAs and markers of macrophage polarization were substantially altered in MDMs differentiated in the presence of non-monocytic peripheral blood mononuclear cells due in part to NF-κB and STAT1 pathway activation. Expression of several of these miRNAs was regulated at a preprocessing step because the expression of the primary miRNAs, but not Dicer, correlated with mature miRNA expression. We conclude that a set of miRNAs is regulated during MDM differentiation, and the rate is uniquely modified for each miRNA by environmental factors. The low basal expression of activation-associated miRNAs in monocytes and their dynamic rates of accumulation during MDM differentiation permit monocytes to tailor miRNA profiles in peripheral tissues during differentiation to macrophages. PMID:25148686

  6. Multipartite entanglement accumulation in quantum states: Localizable generalized geometric measure

    NASA Astrophysics Data System (ADS)

    Sadhukhan, Debasis; Roy, Sudipto Singha; Pal, Amit Kumar; Rakshit, Debraj; SenDe, Aditi; Sen, Ujjwal

    2017-02-01

    Multiparty quantum states are useful for a variety of quantum information and computation protocols. We define a multiparty entanglement measure based on local measurements on a multiparty quantum state and an entanglement measure averaged on the postmeasurement ensemble. Using the generalized geometric measure as the measure of multipartite entanglement for the ensemble, we demonstrate, in the case of several well-known classes of multipartite pure states, that the localized multipartite entanglement can exceed the entanglement present in the original state. We also show that measurement over multiple parties may be beneficial in enhancing localizable multipartite entanglement. We point out that localizable generalized geometric measure faithfully signals quantum critical phenomena in well-known quantum spin models even when considerable finite-size effect is present in the system.

  7. Unprecedented last-glacial mass accumulation rates determined by luminescence dating of loess from western Nebraska

    USGS Publications Warehouse

    Roberts, H.M.; Muhs, D.R.; Wintle, A.G.; Duller, G.A.T.; Bettis, E. Arthur

    2003-01-01

    A high-resolution chronology for Peoria (last glacial period) Loess from three sites in Nebraska, midcontinental North America, is determined by applying optically stimulated luminescence (OSL) dating to 35-50 ??m quartz. At Bignell Hill, Nebraska, an OSL age of 25,000 yr near the contact of Peoria Loess with the underlying Gilman Canyon Formation shows that dust accumulation occurred early during the last glacial maximum (LGM), whereas at Devil's Den and Eustis, Nebraska, basal OSL ages are significantly younger (18,000 and 21,000 yr, respectively). At all three localities, dust accumulation ended at some time after 14,000 yr ago. Mass accumulation rates (MARs) for western Nebraska, calculated using the OSL ages, are extremely high from 18,000 to 14,000 yr-much higher than those calculated for any other pre-Holocene location worldwide. These unprecedented MARs coincide with the timing of a mismatch between paleoenvironmental evidence from central North America, and the paleoclimate simulations from atmospheric global circulation models (AGCMs). We infer that the high atmospheric dust loading implied by these MARs may have played an important role, through radiative forcing, in maintaining a colder-than-present climate over central North America for several thousand years after summer insolation exceeded present-day values. ?? 2003 Elsevier Science (USA). All rights reserved.

  8. Rapid Changes on Sediment Accumulation Rates within Submarine Canyons Caused By Bottom Trawling Activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Masque, P.; Martin, J.; Paradis, S.; Juan, X.; Toro, M.; Palanques, A.

    2014-12-01

    The physical disturbance of the marine sedimentary environments by commercial bottom trawling is a matter of concern. The direct physical effects of this fishing technique include scraping and ploughing of the seabed and increases of the near-bottom water turbidity by sediment resuspension. However, the quantification of the sediment that has been resuspended by this anthropogenic activity over years and has been ultimately exported across the margin remains largely unaddressed. The analysis of sediment accumulation rates from sediment cores collected along the axes of several submarine canyons in the Catalan margin (northwestern Mediterranean) has allowed to estimate the contribution of this anthropogenic activity to the present-day sediment dynamics. 210Pb chronologies, occasionally supported by 137Cs dating, indicate a rapid increase of sediment accumulation rates since the 1970s, in coincidence with a strong impulse in the industrialization of the trawling fleets of this region. Such increase has been associated to the enhanced delivery of sediment resuspended by trawlers from the shelves and upper slope regions towards the canyon's interior, and to the rapid technical development at that time, in terms of engine power and gear size. This change has been observed in La Fonera (or Palamós) Canyon at depths greater than 1700 m, while in other canyons it is restricted to shallower regions (~1000 m in depth) closer to fishing grounds. Two sampling sites from La Fonera and Foix submarine canyons that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied several years after the first chronological analyses. These two new cores reveal a second and more rapid increase of sediment accumulation rates in both canyons occurring circa 2002 and accounting for about 2 cm/y. This second change at the beginning of the XXI century has been attributed to a preferential displacement of the trawling fleet towards slope fishing grounds surrounding submarine

  9. Ages and Accumulation Rates of the Martian Polar Layered Deposits Estimated from Orbital Tuning

    NASA Astrophysics Data System (ADS)

    Sori, M.; Bailey, E. A.; Perron, J.; Huybers, P. J.; Aharonson, O.; Limaye, A.

    2013-12-01

    Layers of dusty water ice in the polar caps of Mars have been hypothesized to record climate changes driven by variation of the planet's orbit and spin axis, but the time interval over which the polar layered deposits (PLDs) formed is unknown, and an orbital influence has not been conclusively demonstrated. We performed orbital tuning of reconstructed PLD stratigraphic sequences in an attempt to constrain the accumulation interval and test for the presence of an orbital signal. Our procedure uses dynamic time warping (DTW) to search for a match between two time series - the polar insolation history and brightness or topographic information in the PLDs - and then assesses the significance of potential matches using a Monte Carlo procedure. We selected 30 images of the northern PLDs from the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor spacecraft and used Mars Orbiter Laser Altimeter profiles to transform each image into a record of image brightness as a function of vertical depth. To constrain the PLD age and accumulation rate, we tuned each image record to Martian insolation records for varying time intervals. If a particular insolation interval produced the strongest match to an image, and if the match became weaker as the image was tuned to progressively longer or shorter intervals, we chose the best-fitting interval as an estimated accumulation time for that PLD sequence, and used the depth range to estimate a corresponding PLD accumulation rate. We also tuned the insolation records to synthetic records containing no orbital influence to test whether the image matches were spurious. Of the 30 MOC images analyzed, 16 produce insolation intervals that we consider strong matches. These images yield an average deposition rate of 0.5 × 0.2 mm/yr for the northern PLDs. The images represent only a fraction of the entire stratigraphy; extrapolating that deposition rate farther back in time yields an age of ~4 Ma for the entire PLD sequence present in the

  10. Spatial and temporal variability of snow accumulation rate at East Antarctic ice sheet in 1993-2010

    NASA Astrophysics Data System (ADS)

    Motoyama, H.; Suzuki, K.; Yamanouchi, T.; Kawamura, K.

    2012-04-01

    Snow stakes along the traverse routes have been observed for long term monitoring program 'the variation of ice sheet surface mass balance' from the 1960's by the Japanese Antarctic Research Expedition in Shirase glacier drainage basin, East Antarctica. During the traverse route between coastal S16 point (69 02'S, 40 03'E, 580m a.s.l.) to inland Dome Fuji (77 22'S, 39 42'E, 3,810m a.s.l.), the snow stake observations every 2 km have been carried out from 1993. Latest stake heights were measured in January 2011 and February 2011. Yearly net snow accumulations from S16 to Dome Fuji were calculated. Heavy snow events were shown in 1998, 2004, 2005, 2008-2009 and 2010. Otherwise, in 1994, 1996, 1999, 2000, 2001, 2002 and 2006, light snow events were observed. They were different in way accumulating spatial pattern depending on places. The yearly accumulation rates were compared with seasonal change of AAO-index (SAM). As a result, yearly accumulation rate and AAO-index showed the positive correlation. We would indicate the spatial distributions of air parcel origins. So we calculate air transport by using the NITRAM trajectory model (Tomikawa and Sato, 2005) and ERA-Interim meteorological data set in 1990-2009. The time duration is 5 days and we suppose the origin of air parcel is the point of trajectory at 5 days ago. The starting points are distributed on 1 deg. x 1 deg. grids over Antarctica and its altitude is 1,300m above the surface. We indicate the spatial distributions of air parcel origins to Antarctica. If there were high ratios of sea origin atmosphere in the inland, there was much snow. It is indicated that the humid air from the sea is the main origin of snowfall. But such relations were not seen on the coast. We try to understand the cause of heavy snow and light snow event.

  11. Historical accumulation rates of mercury in four Scottish ombrotrophic peat bogs over the past 2000 years.

    PubMed

    Farmer, John G; Anderson, Peter; Cloy, Joanna M; Graham, Margaret C; MacKenzie, Angus B; Cook, Gordon T

    2009-10-15

    The historical accumulation rates of mercury resulting from atmospheric deposition to four Scottish ombrotrophic peat bogs, Turclossie Moss (northeast Scotland), Flanders Moss (west-central), Red Moss of Balerno (east-central) and Carsegowan Moss (southwest), were determined via analysis of (210)Pb- and (14)C-dated cores up to 2000 years old. Average pre-industrial rates of mercury accumulation of 4.5 and 3.7 microg m(-2) y(-1) were obtained for Flanders Moss (A.D. 1-1800) and Red Moss of Balerno (A.D. 800-1800), respectively. Thereafter, mercury accumulation rates increased to typical maximum values of 51, 61, 77 and 85 microg m(-2) y(-1), recorded at different times possibly reflecting local/regional influences during the first 70 years of the 20th century, at the four sites (TM, FM, RM, CM), before declining to a mean value of 27+/-15 microg m(-2) y(-1) during the late 1990s/early 2000s. Comparison of such trends for mercury with those for lead and arsenic in the cores and also with direct data for the declining UK emissions of these three elements since 1970 suggested that a substantial proportion of the mercury deposited at these sites over the past few decades originated from outwith the UK, with contributions to wet and dry deposition arising from long-range transport of mercury released by sources such as combustion of coal. Confidence in the chronological reliability of these core-derived trends in absolute and relative accumulation of mercury, at least since the 19th century, was provided by the excellent agreement between the corresponding detailed and characteristic temporal trends in the (206)Pb/(207)Pb isotopic ratio of lead in the (210)Pb-dated Turclossie Moss core and those in archival Scottish Sphagnum moss samples of known date of collection. The possibility of some longer-term loss of volatile mercury released from diagenetically altered older peat cannot, however, be excluded by the findings of this study.

  12. Measuring star formation rates in blue galaxies

    NASA Technical Reports Server (NTRS)

    Gallagher, John S., III; Hunter, Deidre A.

    1987-01-01

    The problems associated with measurements of star formation rates in galaxies are briefly reviewed, and specific models are presented for determinations of current star formation rates from H alpha and Far Infrared (FIR) luminosities. The models are applied to a sample of optically blue irregular galaxies, and the results are discussed in terms of star forming histories. It appears likely that typical irregular galaxies are forming stars at nearly constant rates, although a few examples of systems with enhanced star forming activity are found among HII regions and luminous irregular galaxies.

  13. Field studies using the oyster Crassostrea virginica to determine mercury accumulation and depuration rates

    SciTech Connect

    Palmer, S.J.; Presley, B.J.; Powell, E.N. ); Taylor, R.J. )

    1993-09-01

    Mercury as an environmental hazard, especially with regard to human health, has been of concern since the Minamata disaster. From 1966 to 1970 a chlor-alkali plant in Point Comfort, Texas released mercury-enriched wastewater (up to 29.9 kgHg/day) into Lavaca Bay (TWQB 1977). Since 1970 the Texas Department of Health (TDH) has periodically closed and then re-opened portions of Lavaca Bay to the harvesting of crabs and finfish based on their levels (<>0.5 ppm Hg wet weight) of mercury. A 1988 closure remains in effect as of this writing. Mercury contamination in Lavaca Bay organisms thus continues to be a problem 22 years after the chlor-alkali plant ceased releasing mercury into the bay. The goal of the following research was to better understand the behavior of mercury in Lavaca Bay. Oysters have been widely used as indicator species in metal pollution studies. Most such programs have focused on the concentrations of metals in oysters from different geographic areas. This study, however, investigated the rate and amount of mercury a [open quotes]clean[close quotes] oyster would accumulate when transplanted to a contaminated estuary and the rate of mercury depuration by contaminated oysters placed in a clean environment. The oysters were additionally analyzed for Ba, Cu, Fe, P, and Zn to test for the possible involvement of these metals in mercury accumulation and depuration. 17 refs., 3 figs., 2 tabs.

  14. Distributions and accumulation rates of polycyclic aromatic hydrocarbons in the northern Gulf of Mexico sediments.

    PubMed

    Adhikari, Puspa L; Maiti, Kanchan; Overton, Edward B; Rosenheim, Brad E; Marx, Brian D

    2016-05-01

    Sediment samples collected from shelf, slope and interior basin of the northern Gulf of Mexico during 2011-2013, 1-3 years after the Deepwater Horizon (DWH) oil spill, were utilized to characterize PAH pollution history, in this region. Results indicate that the concentrations of surface ΣPAH43 and their accumulation rates vary between 44 and 160 ng g(-1) and 6-55 ng cm(-2) y(-1), respectively. ΣPAH43 concentration profiles, accumulation rates and Δ(14)C values are significantly altered only for the sediments in the immediate vicinity of the DWH wellhead. This shows that the impact of DWH oil input on deep-sea sediments was generally limited to the area close to the spill site. Further, the PAHs source diagnostic analyses suggest a noticeable change in PAHs composition from higher to lower molecular weight dominance which reflects a change in source of PAHs in the past three years, back to the background composition. Results indicate low to moderate levels of PAH pollution in this region at present, which are unlikely to cause adverse effects on benthic communities.

  15. Accumulation of cAMP augments dynamic vagal control of heart rate.

    PubMed

    Nakahara, T; Kawada, T; Sugimachi, M; Miyano, H; Sato, T; Shishido, T; Yoshimura, R; Miyashita, H; Inagaki, M; Alexander, J; Sunagawa, K

    1998-08-01

    Recent investigations in our laboratory using a Gaussian white noise perturbation technique have shown that simultaneous sympathetic stimulation augmented the gain of the transfer function from vagal stimulation frequency to heart rate response. However, the mechanism of that augmentation remains to be elucidated. In this study, we examined in anesthetized rabbits how three pharmacological interventions known to cause intracellular accumulation of cAMP affected the transfer function. Isoproterenol (0.3 microg . kg-1 . min-1 iv) increased the dynamic gain of transfer function from 7.12 +/- 0.67 to 12.4 +/- 1.21 beats . min-1 . Hz-1 (P < 0.05) without changing the corner frequency or the lag time. Similar augmentations were observed when forskolin (5 microg . kg-1 . min-1 iv) or theophylline (20 mg/kg iv) was administered under conditions of beta-adrenergic blockade. These results suggest that the accumulation of cAMP at postjunctional effector sites contributes, at least in part, to the sympathetic augmentation of the dynamic vagal control of heart rate.

  16. High Resolution Measurement of the Glycolytic Rate

    PubMed Central

    Bittner, Carla X.; Loaiza, Anitsi; Ruminot, Iván; Larenas, Valeria; Sotelo-Hitschfeld, Tamara; Gutiérrez, Robin; Córdova, Alex; Valdebenito, Rocío; Frommer, Wolf B.; Barros, L. Felipe

    2010-01-01

    The glycolytic rate is sensitive to physiological activity, hormones, stress, aging, and malignant transformation. Standard techniques to measure the glycolytic rate are based on radioactive isotopes, are not able to resolve single cells and have poor temporal resolution, limitations that hamper the study of energy metabolism in the brain and other organs. A new method is described in this article, which makes use of a recently developed FRET glucose nanosensor to measure the rate of glycolysis in single cells with high temporal resolution. Used in cultured astrocytes, the method showed for the first time that glycolysis can be activated within seconds by a combination of glutamate and K+, supporting a role for astrocytes in neurometabolic and neurovascular coupling in the brain. It was also possible to make a direct comparison of metabolism in neurons and astrocytes lying in close proximity, paving the way to a high-resolution characterization of brain energy metabolism. Single-cell glycolytic rates were also measured in fibroblasts, adipocytes, myoblasts, and tumor cells, showing higher rates for undifferentiated cells and significant metabolic heterogeneity within cell types. This method should facilitate the investigation of tissue metabolism at the single-cell level and is readily adaptable for high-throughput analysis. PMID:20890447

  17. Vacuum test fixture improves leakage rate measurements

    NASA Technical Reports Server (NTRS)

    Maier, H.; Marx, H.

    1966-01-01

    Cylindrical chamber, consisting of two matching halves, forms a vacuum test fixture for measuring leakage rates of individual connections, brazed joints, and entrance ports used in closed fluid flow line systems. Once the chamber has been sufficiently evacuated, atmospheric pressure holds the two halves together.

  18. Complex Wind-Induced Variations of Surface Snow Accumulation Rates over East Antarctica

    NASA Astrophysics Data System (ADS)

    Das, I.; Scambos, T. A.; Koenig, L.; van den Broeke, M.; Lenaerts, J.

    2015-12-01

    Accurate quantification of surface snow-accumulation over Antarctica is important for mass balance estimates and climate studies based on ice core records. Using airborne radar, lidar and thresholds of surface slope, modeled surface mass balance (SMB) and wind fields, we have predicted continent-wide distribution of wind-scour zones over Antarctica. These zones are located over relatively steep ice surfaces formed by ice flow over bedrock topography. Near-surface winds accelerate over these steeper slopes and erode and sublimate the snow. This results in numerous localized regions (typically ≤ 200 km2) with reduced or negative surface accumulation. Although small zones of re-deposition occur at the base of the steeper slope areas, the redeposited mass is small relative to the ablation loss. Total losses from wind-scour and wind-glaze areas amounts to tens of gigatons annually. Near the coast, winds often blow significant amounts of surface snow from these zones into the ocean. Large uncertainties remain in SMB estimates over East Antarctica as climate models do not adequately represent the small-scale physical processes that lead to mass loss or redistribution over the wind-scour zones. In this study, we also use Operation IceBridge's snow radar data to provide evidence for a gradual ablation of ~16-18 m of firn (~200 years of accumulation) from wind-scour zones over the upper Recovery Ice Stream catchment. The maximum ablation rates observed in this region are ~ -54 kg m-2 a-1 (-54 mm water equivalent a-1). Our airborne radio echo-sounding analysis show snow redeposition downslope of the wind-scour zones is <10% of the cumulative mass loss. Our study shows that the local mass loss is dominated by sublimation to water vapor rather than wind-transport of snow.

  19. Bounding the rate of moment deficit accumulation along the Tohoku segment using GEONET GPS data

    NASA Astrophysics Data System (ADS)

    Segall, P.; Johnson, K. M.; Miyazaki, S.

    2011-12-01

    Geodetic estimates of strain accumulation compared to the rate of past moment release provide important input to earthquake hazard forecasts. Prior to the March 2011 Tohoku earthquake a number of studies investigated plate coupling along the Japan Trench in NE Japan using GEONET GPS data. Most of these assumed an elastic back-slip framework, and regularized the underdetermined inverse problem by minimizing some norm of the back-slip rate. All studies apparently smoothed to zero coupling at the trench and therefore infer the highest coupling just offshore. In contrast, we estimate rigorous bounds on the maximum and minimum permissible rates of moment deficit (MDR) accumulation, not a ``favored'' model according to some ad hoc regularization, using methods of Johnson et al [1994] and Murray and Segall [2002]. Given a domain of interest (the Tohoku rupture segment) and Green's functions G relating slip to data, we solve the following optimization problem for back-slip rate m: {minimize}\\ || G m - d ||22 \\ {subject to} \\ A m = M0 \\ \\ {and} \\ \\ 0 ≤ mi ≤ vplate, where A = [1,1, ... 1], such that A m yields the (normalized) moment-rate. on the model domain. Preliminary results find that || G m - d ||22 exhibits a broad minimum over a factor of 2 in MDR. For the minimum MDR the locked zone is just offshore, while the plate-boundary near the trench slips at the plate rate. At the maximum MDR the locked zone is much larger, including the entire fault near the trench. This clearly demonstrates that the shallow fault is completely in the null-space for onshore data, and that there is at least a factor of two uncertainty in MDR. We will present results employing a bootstrap procedure that is independent of an assumed error distribution in the GPS data. We also extend the method to include viscoelastic earthquake cycle effects, including time-dependence due both to past earthquakes and steady backslip. In these models, fault locking near the trench induces flow which

  20. GPS measurements of strain accumulation across the Imperial Valley, California: 1986-1989

    NASA Technical Reports Server (NTRS)

    Larsen, Shawn; Reilinger, Robert

    1989-01-01

    The Global Positioning System (GPS) data collected in southern California from 1986 to 1989 indicate considerable strain accumulation across the Imperial Valley. Displacements are computed at 29 stations in and near the valley from 1986 to 1988, and at 11 sites from 1988 to 1989. The earlier measurements indicate 5.9 +/- 1.0 cm/yr right-lateral differential velocity across the valley, although the data are heavily influenced by the 1987 Superstition Hills earthquake sequence. Some measurements, especially the east-trending displacements, are suspects for large errors. The 1988 to 1989 GPS displacements are best modeled by 5.2 +/- 0.9 cm/yr of valley crossing deformation, but rates calculated from conventional geodetic measurements (3.4 to 4.3 cm/yr) fit the data nearly as well. There is evidence from GPS and Very Long Base Interferometry (VLBI) observations that the present slip rate along the southern San Andreas fault is smaller than the long-term geologic estimate, suggesting a lower earthquake potential than is currently assumed. Correspondingly, a higher earthquake potential is indicated for the San Jacinto fault. The Imperial Valley GPS sites form part of a 183 station network in southern California and northern Baja California, which spans a cross-section of the North American-Pacific plate boundary.

  1. Global Positioning System measurements of strain accumulation across the Imperial Valley, California - 1986-1989

    NASA Technical Reports Server (NTRS)

    Larsen, Shawn; Reilinger, Robert

    1992-01-01

    The Global Positioning System (GPS) data collected in southern California from 1986 to 1989 indicate considerable strain accumulation across the Imperial Valley. Displacements are computed at 29 stations in and near the valley from 1986 to 1988, and at 11 sites from 1988 to 1989. The earlier measurements indicate 5.9 =/- 1.0 cm/yr right-lateral differential velocity across the valley, although the data are heavily influenced by the 1987 Superstition Hills earthquake sequence. Some measurements, especially the east-trending displacements, are suspects for large errors. The 1988 to 1989 GPS displacements are best modeled by 5.2 =/- 0.9 cm/yr of valley crossing deformation, but rates calculated from conventional geodetic measurements (3.4 to 4.3 cm/yr) fit the data nearly as well. There is evidence from GPS and Very Long Base Interferometry (VLBI) observations that the present slip rate along the southern San Andreas fault is smaller than the long-term geologic estimate, suggesting a lower earthquake potential than is currently assumed. Correspondingly, a higher earthquake potential is indicated for the San Jacinto fault. The Imperial Valley GPS sites form part of a 183 station network in southern California and northern Baja California, which spans a cross-section of the North American-Pacific plate boundary.

  2. Rates of post-fire vegetation recovery and fuel accumulation as a function of burn severity and time-since-burn in four western U.S. ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetation recovery and fuel accumulation rates following wildfire are useful measures of ecosystem resilience, yet few studies have quantified these variables over 10 years post-fire. Conventional wisdom is that recovery time to pre-fire condition will be slower as a function of burn severity, as i...

  3. Faster evolving Drosophila paralogs lose expression rate and ubiquity and accumulate more non-synonymous SNPs

    PubMed Central

    2014-01-01

    Background Duplicated genes can indefinately persist in genomes if either both copies retain the original function due to dosage benefit (gene conservation), or one of the copies assumes a novel function (neofunctionalization), or both copies become required to perform the function previously accomplished by a single copy (subfunctionalization), or through a combination of these mechanisms. Different models of duplication retention imply different predictions about substitution rates in the coding portion of paralogs and about asymmetry of these rates. Results We analyse sequence evolution asymmetry in paralogs present in 12 Drosophila genomes using the nearest non-duplicated orthologous outgroup as a reference. Those paralogs present in D. melanogaster are analysed in conjunction with the asymmetry of expression rate and ubiquity and of segregating non-synonymous polymorphisms in the same paralogs. Paralogs accumulate substitutions, on average, faster than their nearest singleton orthologs. The distribution of paralogs’ substitution rate asymmetry is overdispersed relative to that of orthologous clades, containing disproportionally more unusually symmetric and unusually asymmetric clades. We show that paralogs are more asymmetric in: a) clades orthologous to highly constrained singleton genes; b) genes with high expression level; c) genes with ubiquitous expression and d) non-tandem duplications. We further demonstrate that, in each asymmetrically evolving pair of paralogs, the faster evolving member of the pair tends to have lower average expression rate, lower expression uniformity and higher frequency of non-synonymous SNPs than its slower evolving counterpart. Conclusions Our findings are consistent with the hypothesis that many duplications in Drosophila are retained despite stabilising selection being more relaxed in one of the paralogs than in the other, suggesting a widespread unfinished pseudogenization. This phenomenon is likely to make detection of

  4. On the Effect of Ramp Rate in Damage Accumulation of the CPV Die-Attach: Preprint

    SciTech Connect

    Bosco, N. S.; Silverman, T. J.; Kurtz, S. R.

    2012-06-01

    It is commonly understood that thermal cycling at high temperature ramp rates may activate unrepresentative failure mechanisms. Increasing the temperature ramp rate of thermal cycling, however, could dramatically reduce the test time required to achieve an equivalent amount of thermal fatigue damage, thereby reducing overall test time. Therefore, the effect of temperature ramp rate on physical damage in the CPV die-attach is investigated. Finite Element Model (FEM) simulations of thermal fatigue and thermal cycling experiments are made to determine if the amount of damage calculated results in a corresponding amount of physical damage measured to the die-attach for a variety of fast temperature ramp rates. Preliminary experimental results are in good agreement with simulations and reinforce the potential of increasing temperature ramp rates. Characterization of the microstructure and resulting fatigue crack in the die-attach suggest a similar failure mechanism across all ramp rates tested.

  5. Recent peat accumulation rates in minerotrophic peatlands of the Bay James region, Eastern Canada, inferred by 210Pb and 137Cs radiometric techniques.

    PubMed

    Ali, Adam A; Ghaleb, Bassam; Garneau, Michelle; Asnong, Hans; Loisel, Julie

    2008-10-01

    (210)Pb and (137)Cs dating techniques are used to characterise recent peat accumulation rates of two minerotrophic peatlands located in the La Grande Rivière hydrological watershed, in the James Bay region (Canada). Several cores were collected during the summer 2005 in different parts of the two selected peatlands. These minerotrophic patterned peatlands are presently affected by erosion processes, expressed by progressive mechanical destruction of their pools borders. This erosion process is related to a water table rise induced by a regional increase of humidity since the last century. The main objective of the present paper is to (1) evaluate if (210)Pb and (137)Cs dating techniques can be applied to build accurate chronologies in these environments and (2) detect changes in the peat accumulation rates in regard to this amplification of humidity. In both sites, unsupported (210)Pb shows an exponential decreasing according to the depth. Chronologies inferred from (210)Pb allow to reconstruct peat accumulation rates since ca. 1855 AD. The (137)Cs data displayed evident mobility and diffusion, preventing the establishment of any sustained chronology based on these measurements. In the two sites, peat accumulation rates inferred from (210)Pb chronologies fluctuate between 0.005 and 0.038 g cm(-2) yr(-1). As a result, the rise of the water table during the last decade has not yet affected peat accumulation rates.

  6. Measurement of Transverse Beam Size in Accumulator as a Function of Momenta During Stacking

    SciTech Connect

    Halling, Mike

    1992-01-22

    The horizontal and vertical emittance as a function of momentum was measured in the accumulator while stacking with a small stack. The data suggests that the transverse emittance of the beam is blown up between the injection orbit and the stacking orbit. The technique shows promise, and should be repeated with a large stack to measure the emittance in the accumulator at a time when we have large losses.

  7. Wireless Measurement of Rotation and Displacement Rate

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    A magnetic field response sensor is designed to measure displacement or rotation rate without a physical connection to a power source, microprocessor, data acquisition equipment, or electrical circuitry. The sensor works with the magnetic field response recorder, which was described in Magnetic-Field-Response Measurement-Acquisition System, NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. These sensors are wirelessly powered and interrogated, and the measurement acquisition system and sensors are extremely lightweight.The response recorder uses oscillating magnetic fields to power the sensors. Once powered, the sensors respond with their own magnetic field. For displacement/ rotation measurements, the response recorder uses the sensor s response amplitude, which is dependent on the distance from the antenna. The recorder s antenna orientation and position are kept fixed, and the sampling period is constant.

  8. A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata).

    PubMed

    Weisrock, David W; Papenfuss, Theodore J; Macey, J Robert; Litvinchuk, Spartak N; Polymeni, Rosa; Ugurtas, Ismail H; Zhao, Ermi; Jowkar, Houman; Larson, Allan

    2006-11-01

    We examine phylogenetic relationships among salamanders of the family Salamandridae using approximately 2700 bases of new mtDNA sequence data (the tRNALeu, ND1, tRNAIle, tRNAGln, tRNAMet, ND2, tRNATrp, tRNAAla, tRNAAsn, tRNACys, tRNATyr, and COI genes and the origin for light-strand replication) collected from 96 individuals representing 61 of the 66 recognized salamandrid species and outgroups. Phylogenetic analyses using maximum parsimony and Bayesian analysis are performed on the new data alone and combined with previously reported sequences from other parts of the mitochondrial genome. The basal phylogenetic split is a polytomy of lineages ancestral to (1) the Italian newt Salamandrina terdigitata, (2) a strongly supported clade comprising the "true" salamanders (genera Chioglossa, Mertensiella, Lyciasalamandra, and Salamandra), and (3) a strongly supported clade comprising all newts except S. terdigitata. Strongly supported clades within the true salamanders include monophyly of each genus and grouping Chioglossa and Mertensiella as the sister taxon to a clade comprising Lyciasalamandra and Salamandra. Among newts, genera Echinotriton, Pleurodeles, and Tylototriton form a strongly supported clade whose sister taxon comprises the genera Calotriton, Cynops, Euproctus, Neurergus, Notophthalmus, Pachytriton, Paramesotriton, Taricha, and Triturus. Our results strongly support monophyly of all polytypic newt genera except Paramesotriton and Triturus, which appear paraphyletic, and Calotriton, for which only one of the two species is sampled. Other well-supported clades within newts include (1) Asian genera Cynops, Pachytriton, and Paramesotriton, (2) North American genera Notophthalmus and Taricha, (3) the Triturus vulgaris species group, and (4) the Triturus cristatus species group; some additional groupings appear strong in Bayesian but not parsimony analyses. Rates of lineage accumulation through time are evaluated using this nearly comprehensive sampling of

  9. Measuring radiative capture rates at DRAGON

    NASA Astrophysics Data System (ADS)

    Hager, U.; Davids, B.; Fallis, J.; Greife, U.; Hutcheon, D. A.; Rojas, A.; Ruiz, C.

    2013-04-01

    The DRAGON recoil separator facility is located at the ISAC facility at TRIUMF, Vancouver. It is designed to measure radiative alpha and proton capture reactions of astrophysical importance in inverse kinematics. The Supernanogan ion source at ISAC provides stable beams of high intensities. The DRAGON collaboration has taken advantage of this over the last years by measuring several reactions requiring high-intensity stable oxygen beams. In particular,the ^17O(p,γ) and ^16O(α,γ) reaction rates were recently measured. The former reaction is part of the hot CNO cycle, and strongly influences the abundance of ^18F in classical novae. Because of its relatively long lifetime, ^18F is a possible target for satellite-based gamma-ray spectroscopy. The ^16O(α,γ) reaction plays a role in steady-state helium burning in massive stars, where it follows the ^12C(α,γ) reaction. At astrophysically relevant energies, the reaction proceeds exclusively via direct capture, resulting in a low rate. In both cases, the unique capabilities of DRAGON enabled determination not only of the total reaction rates, but also of decay branching ratios. Results from both experiments will be presented.

  10. Ultrasonic rate measurement of multiphase flow

    SciTech Connect

    Dannert, D.A.; Horne, R.N.

    1993-01-01

    On of the most important tools in production logging and well testing is the downhole flowmeter. Unfortunately, existing tools are inaccurate outside of an idealized single phase flow, regime. Spinner tools are inaccurate at extremely high or low, flow rates and when the flow rate is variable. Radioactive tracer tools have similar inaccuracies and are extremely sensitive to the flow regime. Both tools completely fail in the presence of multiphase flow, whether gas/ oil, gas/water or fluid/solid. Downhole flowmetering is important for locating producing zones and thief zones and monitoring production and injection rates. The effects of stimulation can also be determined. This goal of this project is the investigation of accurate downhole flowmetering techniques for all single phase flow regimes and multiphase flows. The measurement method investigated in this report is the use of ultrasound. There are two ways to use ultrasound for fluid velocity measurement. The first method, examined in Chapter 2, is the contrapropagation, or transit-time, method which compares travel times with and against fluid flow. Chapter 3 details the second method which measures the Doppler frequency shift of a reflected sound wave in the moving fluid. Both of these technologies need to be incorporated in order to build a true multiphase flowmeter. Chapter 4 describes the proposed downhole multiphase flowmeter. It has many advantages besides the ones previously mentioned and is in full in that chapter.

  11. High dose rate brachytherapy source measurement intercomparison.

    PubMed

    Poder, Joel; Smith, Ryan L; Shelton, Nikki; Whitaker, May; Butler, Duncan; Haworth, Annette

    2017-03-24

    This work presents a comparison of air kerma rate (AKR) measurements performed by multiple radiotherapy centres for a single HDR (192)Ir source. Two separate groups (consisting of 15 centres) performed AKR measurements at one of two host centres in Australia. Each group travelled to one of the host centres and measured the AKR of a single (192)Ir source using their own equipment and local protocols. Results were compared to the (192)Ir source calibration certificate provided by the manufacturer by means of a ratio of measured to certified AKR. The comparisons showed remarkably consistent results with the maximum deviation in measurement from the decay-corrected source certificate value being 1.1%. The maximum percentage difference between any two measurements was less than 2%. The comparisons demonstrated the consistency of well-chambers used for (192)Ir AKR measurements in Australia, despite the lack of a local calibration service, and served as a valuable focal point for the exchange of ideas and dosimetry methods.

  12. Compact Instruments Measure Helium-Leak Rates

    NASA Technical Reports Server (NTRS)

    Stout, Stephen; Immer, Christopher

    2003-01-01

    Compact, lightweight instruments have been developed for measuring small flows of helium and/or detecting helium leaks in solenoid valves when the valves are nominally closed. These instruments do not impede the flows when the valves are nominally open. They can be integrated into newly fabricated valves or retrofitted to previously fabricated valves. Each instrument includes an upstream and a downstream thermistor separated by a heater, plus associated analog and digital heater-control, signal- conditioning, and data-processing circuits. The thermistors and heater are off-the-shelf surface mount components mounted on a circuit board in the flow path. The operation of the instrument is based on a well-established thermal mass-flow-measurement technique: Convection by the flow that one seeks to measure gives rise to transfer of heat from the heater to the downstream thermistor. The temperature difference measured by the thermistors is directly related to the rate of flow. The calibration curve from temperature gradient to helium flow is closely approximated via fifth-order polynomial. A microprocessor that is part of the electronic circuitry implements the calibration curve to compute the flow rate from the thermistor readings.

  13. Equatorial Pacific Reactive Phosphorus Accumulation Rates across the Eocene/Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Faul, K. L.; Stewart, K. L.

    2007-12-01

    Paired benthic foraminiferal stable isotope and trace metal records from ODP Site 1218 in the equatorial Pacific have shown that the Eocence/Oligocene (E/O) transition (~34 Ma) represents a major increase in Antarctic ice accumulation and a rapid deepening of the global calcite compensation depth (CCD) occurring in two steps [e.g., Lear et al., 2000; Lear et al., 2004; Coxall et al., 2005; Palike et al., 2006]. Simultaneous increases in biogenic mass accumulation rates (MARs) around Australia and in the Atlantic Ocean have been interpreted as representing increased productivity and/or organic carbon (C) burial possibly linked to cooling and ice sheet growth [Diester-Hass and Zahn, 2001; Anderson and Delaney, 2005]. Because the global CCD deepens across the transition, there is a need to distinguish organic C burial changes from CCD changes. We are determining reactive phosphorus (P, micromol P cm-2 kyr-1) MARs as an indicator of organic C burial for Site 1218 to help constrain the relative role of productivity during the E/O climatic transition. Reactive phosphorus (the sum of oxide associated, authigenic, and organic P; sequentially extracted from bulk sediment), delivered to the sediment water interface with organic C, is well preserved in oxygenated sediments. Preliminary results show an order of magnitude decrease in reactive P concentrations (from ~100 to ~10 micromol P g-1) across the E/O boundary. This may indicate that absolute organic C burial as well as the ratio of organic C burial to calcite burial may have decreased across the E/O transition in the equatorial Pacific upwelling zone.

  14. Constraints on the Recent Rate of Lunar Regolith Accumulation from Diviner Observations

    NASA Technical Reports Server (NTRS)

    Ghent, R. R.; Hayne, P. O.; Bandfield, J. L.; Campbell, B. A.; Carter, L. M.

    2012-01-01

    Many large craters on the lunar nearside show radar CPR signatures consistent with the presence of blocky ejecta blankets, to distances pre dicted to be covered by continuous ejecta. However, most of these sur faces show limited enhancements in both derived rock abundance and rock-free regolith temperatures calculated from Diviner nighttime infrar ed observations. This indicates that the surface rocks are covered by a layer of thermally insulating regolith material. By matching the results of one-dimensional thermal models to Diviner nighttime temperat ures, we have constrained the thermophysical properties of the upper regolith, and the thickness of regolith overlying proximal ejecta. We find that for all of the regions surveyed (all in the nearside highla nds), the nighttime cooling curves are best fit by a density profile that varies exponentially with depth, consistent with a linear mixture of rocks and regolith fines, with increasing rock content with depth . Our results show significant spatial variations in the density e-folding depth, H, among young crater ejecta regions, indicating differen ces in the thickness of accumulated regolith. However, away from youn g craters, the average regional "equilibrium" value of H (Heq) is remarkably consistent, and is on the order of 5 cm. As expected, near-rim ejecta associated with young craters show lower values of H, indicating a high rock content in the shallow subsurface; for older craters, the average value of H approaches the regional value of Heq. Calculat ed H values for young craters show a clear correlation with published ages, providing the first observational constraint on the recent rate of lunar regolith accumulation. In addition, this result may help to resolve the apparent discrepancy between ages calculated from small crater counts on melt ponds versus counts on continuous ejecta (e.g., King crater; Ashley et al., 2011, LPSC 42, abstract 2437). This method could, in principle, be extended to other

  15. Greenland annual accumulation along the EGIG line, 1959-2004, from ASIRAS airborne radar and detailed neutron-probe density measurements

    NASA Astrophysics Data System (ADS)

    Overly, T. B.; Hawley, R. L.; Helm, V.; Morris, E. M.; Chaudhary, R. N.

    2015-12-01

    We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and detailed neutron-probe (NP) density profiles. ASIRAS-NP accumulation rates are not statistically different (C.I. 95 %) from in situ EGIG accumulation measurements from 1985 to 2004. Below 3000 m elevation, ASIRAS-NP increases by 20 % for the period 1995 to 2004 compared to 1985 to 1994. Above 3000 m elevation, accumulation increases by 13 % for 1995-2004 compared to 1985-1994. Model snow accumulation results from the calibrated Fifth Generation Mesoscale Model modified for polar climates (Polar MM5) underestimate mean annual accumulation by 16 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modelled density profiles in place of detailed NP data. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the IceBridge campaign.

  16. Solids flow rate measurement in dense slurries

    SciTech Connect

    Porges, K.G.; Doss, E.D.

    1993-09-01

    Accurate and rapid flow rate measurement of solids in dense slurries remains an unsolved technical problem, with important industrial applications in chemical processing plants and long-distance solids conveyance. In a hostile two-phase medium, such a measurement calls for two independent parameter determinations, both by non-intrusive means. Typically, dense slurries tend to flow in laminar, non-Newtonian mode, eliminating most conventional means that usually rely on calibration (which becomes more difficult and costly for high pressure and temperature media). These issues are reviewed, and specific solutions are recommended in this report. Detailed calculations that lead to improved measuring device designs are presented for both bulk density and average velocity measurements. Cross-correlation, chosen here for the latter task, has long been too inaccurate for practical applications. The cause and the cure of this deficiency are discussed using theory-supported modeling. Fluid Mechanics are used to develop the velocity profiles of laminar non-Newtonian flow in a rectangular duct. This geometry uniquely allows the design of highly accurate `capacitive` devices and also lends itself to gamma transmission densitometry on an absolute basis. An absolute readout, though of less accuracy, is also available from a capacitive densitometer and a pair of capacitive sensors yields signals suitable for cross-correlation velocity measurement.

  17. Forest dynamics and tip-up pools drive pulses of high carbon accumulation rates in a tropical peat dome in Borneo (Southeast Asia)

    NASA Astrophysics Data System (ADS)

    Dommain, René; Cobb, Alexander R.; Joosten, Hans; Glaser, Paul H.; Chua, Amy F. L.; Gandois, Laure; Kai, Fuu-Ming; Noren, Anders; Salim, Kamariah A.; Su'ut, N. Salihah H.; Harvey, Charles F.

    2015-04-01

    Peatlands of Southeast Asia store large pools of carbon but the mechanisms of peat accumulation in tropical forests remain to be resolved. Patch dynamics and forest disturbance have seldom been considered as drivers that can amplify or dampen rates of peat accumulation. Here we used a modified piston corer, noninvasive geophysical measurements, and geochemical and paleobotanical techniques to establish the effect of tree fall on carbon accumulation rates in a peat swamp forest dominated by Shorea albida in Brunei (Borneo). Carbon initially accumulated in a mangrove forest at over 300 g C m-2 yr-1 but declined to less than 50 g C m-2 yr-1 with the establishment of a peat swamp forest. A rapid accumulation pulse of 720-960 g C m-2 yr-1 occurred around 1080 years ago as a tip-up pool infilled. Tip-up pools are common in the peatlands of northwest Borneo where windthrow and lightning strikes produce tree falls at a rate of 4 trees ha-1 every decade. A simulation model indicates that tip-up pools, which are formed across the entire forested peat dome, produce local discontinuities in the peat deposit, when peat is removed to create a pool that is rapidly filled with younger material. The resulting discontinuities in peat age at the base and sides of pool deposits obscure linkages between carbon accumulation rates and climate and require new approaches for paleoenvironmental reconstructions. Our results suggest that carbon accumulation in tropical peat swamps may be based on fundamentally different peat-forming processes than those of northern peatlands.

  18. Impacts of timber harvesting on historic sediment accumulation rates in the Coos Bay estuary, Oregon

    NASA Astrophysics Data System (ADS)

    Mathabane, N.; Roering, J. J.

    2014-12-01

    The expansion and development of human infrastructure along the coastline of the Pacific Northwest has profound consequences for the habitability and general ecological health of coastal ecosystems. Coos County, one of the most economically critical regions of the Oregon Coast, experienced vigorous timber harvest activity in the aftermath of WWII that declined in the last several decades. This period of extractive land use may have drastically altered the sediment supply in the major catchments of the Coos and Millicoma Rivers and lead to variations in sediment flux into the Coos Bay estuary. Accurate sediment flux histories are critical data for deciphering the relative importance of climate and land use factors such as logging and road construction on sediment production. Reduction of root reinforcement following timber harvest increases the likelihood of shallow landsliding and debris flows. In addition, forest roads increase sediment production due to overland flow and entrainment of fine sediments on hydrologically connected roads. Although these processes have been documented in small watersheds, their compounded effect on estuaries and coastal settings has not been well documented. We use Pb-210 activities derived from sediment cores taken at various locations in the Coos Bay estuary to establish temporal variations in sediment accumulation rates (SARs). Our cores will also be analyzed to assess dissolved oxygen and other proxies for ecosystem functioning. By correlating these SARs with quantitative metrics for timber extraction rate such as board feet per year and qualitative evaluations from historical photos, we propose to document the cumulative effect of historic forest practices. The temporal resolution provided by this technique should allow us to link changes in estuarine sedimentation to changes in land use as well as climatic triggers such as storms. The conclusions of this study will add valuable information regarding the ultimate impact of

  19. Limitations of oximetry to measure heart rate variability measures.

    PubMed

    Lu, Guohua; Yang, Fang

    2009-09-01

    Measuring heart rate variability (HRV) is widely used to assess autonomic nervous system function. It requires accurate measurement of the interval between successive heartbeats. This can be achieved from recording the electrocardiogram (ECG), which is non-invasive and widely available. However, methodological problems inherent in recording and analyzing ECG traces have motivated a search for alternative means of measuring the interval between successive heartbeats. Recording blood oxygenation pulsations (photoplethysmography-PPG) is also convenient, non-invasive and widely available, and has been suggested as an effective alternative to ECG to derive HRV. Moreover, it has been claimed that the pulse waveforms produced by oximetry may be more practicable than R-R intervals measured from the by ECG, especially for ambulatory recordings. We have therefore compared PPG with ECG recordings to measure HRV applying the same signal analysis techniques to PPG and ECG recordings made simultaneously. Comparison of 5 min recording epochs demonstrated a very high degree of correlation, in temporal, frequency domains and non-linear analysis, between HRV measures derived from the PPG and ECG. However, we found that the PPG signal is especially vulnerable to motion artifacts when compared to the ECG, preventing any HRV analysis at all in a significant minority of PPG recordings. Our results demonstrate that even though PPG provides accurate interpulse intervals to measure heart rate variability under ideal conditions, it is less reliable due to its vulnerability to motion artifacts. Therefore it is unlikely to prove a practical alternative to the ECG in ambulatory recordings or recordings made during other activities.

  20. Radionuclide measurement of differential glomerular filtration rate

    SciTech Connect

    Powers, T.A.; Stone, W.J.; Grove, R.B.; Plunkett, J.M.; Kadir, S.; Patton, J.A.; Bowen, R.D.

    1981-01-01

    The authors sought to determine whether radionuclides could provide a reasonable estimate of differential renal function in five normal dogs and six dogs with unilateral segmental renal infarction. Glomerular filtration rate (GFR) of each kidney was measured by the standard technique using constant infusions of 99mTc-DTPA, iothalamate, and creatinine following ureteral catheterization. These results were correlated with total GFR estimated by bolus injection of 99mTc-DTPA and analysis of the plasma 99mTc-DTPA disappearance curve obtained by blood sampling. Differential GFR was then calculated by multiplying the total GFR from double exponential analysis of this curve (DTPA2) by each of three measures of differential function. These include the percent differential uptake of 99mTc-DTPA and 99mTc-DMSA in the posterior projection as well as the geometric mean of 99mTc-DMSA uptake. There were good correlations between differential GFR calculated from iothalamate clearances obtained at ureteral catheterization and all noninvasive methods involving radionuclides and DTPA2 (r = 0.85 - 0.99). Single exponential analysis of the 99mTc-DTPA plasma disappearance curve was less satisfactory. The authors suggest that measurement of total and differential GFR calculated from plasma clearance of 99mTc-DTPA and external counting may be a useful method with potential clinical applications.

  1. Constraints on the recent rate of lunar regolith accumulation from Diviner observations

    NASA Astrophysics Data System (ADS)

    Ghent, R. R.; Hayne, P. O.; Bandfield, J. L.; Campbell, B. A.; Carter, L. M.; Allen, C.; Paige, D. A.

    2012-12-01

    Many large craters on the lunar nearside show radar CPR signatures consistent with the presence of blocky ejecta blankets, to distances predicted to be covered by continuous ejecta. However, most of these surfaces show limited enhancements in both derived rock abundance and rock-free regolith temperatures calculated from Diviner nighttime infrared observations. This indicates that the surface rocks are covered by a layer of thermally insulating regolith material. By matching the results of one-dimensional thermal models to Diviner nighttime temperatures, we have constrained the thermophysical properties of the upper regolith, and the thickness of regolith overlying proximal ejecta. We find that for all of the regions surveyed (all in the nearside highlands), the nighttime cooling curves are best fit by a density profile that varies exponentially with depth, consistent with a linear mixture of rocks and regolith fines, with increasing rock content with depth. Our results show significant spatial variations in the density e-folding depth, H, among young crater ejecta regions, indicating differences in the thickness of accumulated regolith. However, away from young craters, the average regional "equilibrium" value of H (Heq) is remarkably consistent, and is on the order of 5 cm. As expected, near-rim ejecta associated with young craters show lower values of H, indicating a high rock content in the shallow subsurface; for older craters, the average value of H approaches the regional value of Heq. Calculated H values for young craters (Giordano Bruno, Moore F, Byrgius A, Necho, Tycho, Jackson, King, and Copernicus) show a clear correlation with published ages, providing the first observational constraint on the recent rate of lunar regolith accumulation. In addition, this result may help to resolve the apparent discrepancy between ages calculated from small crater counts on melt ponds versus counts on continuous ejecta (e.g., King crater; Ashley et al., 2011, LPSC 42

  2. Marine debris accumulation in the Northwestern Hawaiian Islands: an examination of rates and processes.

    PubMed

    Dameron, Oliver J; Parke, Michael; Albins, Mark A; Brainard, Russell

    2007-04-01

    Large amounts of derelict fishing gear accumulate and cause damage to shallow coral reefs of the Northwestern Hawaiian Islands (NWHI). To facilitate maintenance of reefs cleaned during 1996-2005 removal efforts, we identify likely high-density debris areas by assessing reef characteristics (depth, benthic habitat type, and energy regime) that influence sub-regional debris accumulation. Previously cleaned backreef and lagoonal reefs at two NWHI locations were resurveyed for accumulated debris using two survey methods. Accumulated debris densities and weights were found to be greater in lagoonal reef areas. Sample weight-based debris densities are extrapolated to similar habitats throughout the NWHI using a spatial 'net habitat' dataset created by generalizing IKONOS satellite derivatives for depth and habitat classification. Prediction accuracy for this dataset is tested using historical debris point data. Annual NWHI debris accumulation is estimated to be 52.0 metric tonnes. For planning purposes, individual NWHI atolls/reefs are allotted a proportion of this total.

  3. Belowground carbon balance and carbon accumulation rate in the successional series of monsoon evergreen broad-leaved forest

    USGS Publications Warehouse

    Zhou, G.; Liu, S.; Tang, X.; Ouyang, X.; Zhang, Dongxiao; Liu, J.; Yan, J.; Zhou, C.; Luo, Y.; Guan, L.; Liu, Yajing

    2006-01-01

    The balance, accumulation rate and temporal dynamics of belowground carbon in the successional series of monsoon evergreen broadleaved forest are obtained in this paper, based on long-term observations to the soil organic matter, input and standing biomass of litter and coarse woody debris, and dissolved organic carbon carried in the hydrological process of subtropical climax forest ecosystem—monsoon evergreen broad-leaved forest, and its two successional forests of natural restoration—coniferous and broad-leaved mixed forest and Pinus massoniana forest, as well as data of root biomass obtained once every five years and respiration measurement of soil, litter and coarse woody debris respiration for 1 year. The major results include: the belowground carbon pools of monsoon evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, and Pinus massoniana forest are 23191 ± 2538 g · m−2, 16889 ± 1936 g · m−2 and 12680 ± 1854 g · m−2, respectively, in 2002. Mean annual carbon accumulation rates of the three forest types during the 24a from 1978 to 2002 are 383 ± 97 g · m−2 · a−1, 193 ± 85 g · m−2 · a−1 and 213 ± 86 g · m−2 · a−1, respectively. The belowground carbon pools in the three forest types keep increasing during the observation period, suggesting that belowground carbon pools are carbon sinks to the atmosphere. There are seasonal variations, namely, they are strong carbon sources from April to June, weak carbon sources from July to September; while they are strong carbon sinks from October to November, weak carbon sinks from December to March.

  4. Satellite Angular Rate Estimation From Vector Measurements

    NASA Technical Reports Server (NTRS)

    Azor, Ruth; Bar-Itzhack, Itzhack Y.; Harman, Richard R.

    1996-01-01

    This paper presents an algorithm for estimating the angular rate vector of a satellite which is based on the time derivatives of vector measurements expressed in a reference and body coordinate. The computed derivatives are fed into a spacial Kalman filter which yields an estimate of the spacecraft angular velocity. The filter, named Extended Interlaced Kalman Filter (EIKF), is an extension of the Kalman filter which, although being linear, estimates the state of a nonlinear dynamic system. It consists of two or three parallel Kalman filters whose individual estimates are fed to one another and are considered as known inputs by the other parallel filter(s). The nonlinear dynamics stem from the nonlinear differential equation that describes the rotation of a three dimensional body. Initial results, using simulated data, and real Rossi X ray Timing Explorer (RXTE) data indicate that the algorithm is efficient and robust.

  5. Measurements of the atmospheric neutron leakage rate

    NASA Technical Reports Server (NTRS)

    Lockwood, J. A.; Ifedili, S. O.; Jenkins, R. W.

    1973-01-01

    The atmospheric neutron leakage rate in the energy range from 0.01 to 10,000,000 eV has been measured as a function of latitude, altitude, and time with a neutron detector on board the Ogo 6 satellite. The latitude dependence of the neutron leakage is in reasonable agreement with that predicted by Lingenfelter (1963) and Light et al. (1973) if the neutron energy spectrum has the shape calculated by Newkirk (1963). The change in the neutron latitude dependence with the cosmic ray modulation agrees with the predictions of Lingenfelter and Light et al. For several solar proton events enhancements were observed in the neutron counting rates at lambda greater than or equal to 70 deg. Such events, however, provide an insignificant injection of protons at E less than or equal to 20 MeV into the radiation belts. An isotropic angular distribution of the neutron leakage in the energy range from 0.1 keV to 10 MeV best fits the observed altitude dependence of the neutron leakage flux.

  6. Accumulation rates and predominant atmospheric sources of natural and anthropogenic Hg and Pb on the Faroe Islands

    NASA Astrophysics Data System (ADS)

    Shotyk, W.; Goodsite, M. E.; Roos-Barraclough, F.; Givelet, N.; Le Roux, G.; Weiss, D.; Cheburkin, A. K.; Knudsen, K.; Heinemeier, J.; van Der Knaap, W. O.; Norton, S. A.; Lohse, C.

    2005-01-01

    A monolith representing 5420 14C yr of peat accumulation was collected from a blanket bog at Myrarnar, Faroe Islands. The maximum Hg concentration (498 ng/g at a depth of 4.5 cm) coincides with the maximum concentration of anthropogenic Pb (111 μg/g). Age dating of recent peat accumulation using 210Pb (CRS model) shows that the maxima in Hg and Pb concentrations occur at AD 1954 ± 2. These results, combined with the isotopic composition of Pb in that sample ( 206Pb/ 207Pb = 1.1720 ± 0.0017), suggest that coal burning was the dominant source of both elements. From the onset of peat accumulation (ca. 4286 BC) until AD 1385, the ratios Hg/Br and Hg/Se were constant (2.2 ± 0.5 × 10 -4 and 8.5 ± 1.8 × 10 -3, respectively). Since then, Hg/Br and Hg/Se values have increased, also reaching their maxima in AD 1954. The age date of the maximum concentrations of anthropogenic Hg and Pb in the Faroe Islands is consistent with a previous study of peat cores from Greenland and Denmark (dated using the atmospheric bomb pulse curve of 14C), which showed maximum concentrations in AD 1953. The average rate of atmospheric Hg accumulation from 1520 BC to AD 1385 was 1.27 ± 0.38 μg/m 2/yr. The Br and Se concentrations and the background Hg/Br and Hg/Se ratios were used to calculate the average rate of natural Hg accumulation for the same period, 1.32 ± 0.36 μg/m 2/yr and 1.34 ± 0.29 μg/m 2/yr, respectively. These fluxes are similar to the preanthropogenic rates obtained using peat cores from Switzerland, southern Greenland, southern Ontario, Canada, and the northeastern United States. Episodic volcanic emissions and the continual supply of marine aerosols to the Faroe Islands, therefore, have not contributed significantly to the Hg inventory or the Hg accumulation rates, relative to these other areas. The maximum rate of Hg accumulation was 34 μg/m 2/yr. The greatest fluxes of anthropogenic Hg accumulation calculated using Br and Se, respectively, were 26 and 31 μg/m 2

  7. 210Pb mass accumulation rates in the depositional area of the Magra River (Mediterranean Sea, Italy)

    NASA Astrophysics Data System (ADS)

    Delbono, I.; Barsanti, M.; Schirone, A.; Conte, F.; Delfanti, R.

    2016-08-01

    Nine sediment cores were collected between 2009 and 2012 in the inner continental shelf (Mediterranean Sea, Italy) mainly influenced by the Magra River, at water depths ranging from 11 to 64 m. Mass Accumulation Rates (MARs) were calculated through 210Pb analysed by Gamma spectrometry. Three different dating models (single and two-layer CF-CS, CRS) were applied to clay normalised 210Pbxs profiles and 137Cs was used to validate the 210Pb geochronology. The maximum MAR values (>2 g cm-2 yr-1) were found in the region adjacent to the Magra River mouth and outside the Gulf of La Spezia (0.9±0.1 g cm-2 yr-1 at St. 3-C6 and 4-C4). Results from 137Cs/210Pbxs ratios calculated in Surface Mixed Layers (SMLs) evidenced the coastal boundaries of the Magra River depositional area, which is very limited towards south. Differently, in the north-west sector, fine sediments are generally driven by the Ligurian Current and move towards north-west: at the deepest and most distant station from the River mouth, the MAR value is the lowest one in the study area. Few major Magra River floods occurred during the sediment core sampling period. By using the short-lived radioisotope 7Be as a tracer of river floods, a clear 7Be signature of 2009 flood is present at St. 1-SA1C. Finally, by analyzing the clay normalised 210Pbxs profiles, a decrease of its activity dating the years 1999 and 2000 is observed in four cores, corresponding to two major Magra River floods occurring in those years.

  8. Growth rate, protein accumulation, and catabolic enzyme activity of skeletal muscles of galliform birds.

    PubMed

    Shea, Russell E; Olson, John M; Ricklefs, Robert E

    2007-01-01

    We measured the mass and several potential indices of functional capacity of the leg and pectoral muscles through 21 d of age in chicks of three species of galliform birds and the domesticated turkey. The study was conducted to test the hypothesis that the growth rate of a tissue is inversely related to its capacity for mature function across species. We measured the proportion of protein and the activities of the catabolic enzymes citrate synthase (CS), pyruvate kinase (PK), and beta -hydroxy-acyl-CoA-dehydrogenase (HOAD) and estimated exponential growth rate (EGR) from growth increments. EGR was negatively related to proportion of protein, PK, and HOAD and positively related to CS activity. In a multiple regression, EGR was uniquely related only to proportion of protein; it was higher in pectoral muscles and increased in this order: wild turkeyrate. When the proportion of protein was normalized by its maximum value for each species and muscle type, the relationship between EGR and normalized protein did not differ significantly among species or muscle type. Thus, if we accept the proportion of protein relative to the mature level as an index of functional capacity--presumably representing the assembly of the contractile apparatus--then growth rate is consistently inversely related to a muscle's capacity for mature function, that is, force generation.

  9. Geographic variability in organic carbon stock and accumulation rate in sediments of East and Southeast Asian seagrass meadows

    NASA Astrophysics Data System (ADS)

    Miyajima, Toshihiro; Hori, Masakazu; Hamaguchi, Masami; Shimabukuro, Hiromori; Adachi, Hiroshi; Yamano, Hiroya; Nakaoka, Masahiro

    2015-04-01

    Organic carbon (OC) stored in the sediments of seagrass meadows has been considered a globally significant OC reservoir. However, the sparsity and regional bias of studies on long-term OC accumulation in coastal sediments have limited reliable estimation of the capacity of seagrass meadows as a global OC sink. We evaluated the amount and accumulation rate of OC in sediment of seagrass meadows and adjacent areas in East and Southeast Asia. In temperate sites, the average OC concentration in the top 30 cm of sediment was higher in seagrass meadows (780-1080 mmol g-1) than in sediments without seagrass cover (52-430 mmol g-1). The average OC in the top 30 cm of subtropical and tropical seagrass meadow sediments ranged from 140 to 440 mmol g-1. Carbon isotope mass balancing suggested that the contribution of seagrass-derived carbon to OC stored in sediments was often relatively minor (temperate: 10-40%; subtropical: 35-82%; tropical: 4-34%) and correlated to the habitat type, being particularly low in estuarine habitats. Stock of OC in the top meter of sediment of all the studied meadows ranged from 38 to 120 Mg ha-1. The sediment accumulation rates were estimated by radiocarbon dating of six selected cores (0.32-1.34 mm yr-1). The long-term OC accumulation rates calculated from the sediment accumulation rate and the top 30 cm average OC concentration for the seagrass meadows (24-101 kg ha-1 yr-1) were considerably lower than the OC accumulation rates previously reported for Mediterranean Posidonia oceanica meadows (580 kg ha-1 yr-1 on average). Current estimates for the global carbon sink capacity of seagrass meadows, which rely largely on Mediterranean studies, may be considerable overestimations.

  10. Accumulate repeat accumulate codes

    NASA Technical Reports Server (NTRS)

    Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung

    2004-01-01

    In this paper we propose an innovative channel coding scheme called 'Accumulate Repeat Accumulate codes' (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterative decoding of ARA codes on a graph. The structure of encoder for this class can be viewed as precoded Repeat Accumulate (RA) code or as precoded Irregular Repeat Accumulate (IRA) code, where simply an accumulator is chosen as a precoder. Thus ARA codes have simple, and very fast encoder structure when they representing LDPC codes. Based on density evolution for LDPC codes through some examples for ARA codes, we show that for maximum variable node degree 5 a minimum bit SNR as low as 0.08 dB from channel capacity for rate 1/2 can be achieved as the block size goes to infinity. Thus based on fixed low maximum variable node degree, its threshold outperforms not only the RA and IRA codes but also the best known LDPC codes with the dame maximum node degree. Furthermore by puncturing the accumulators any desired high rate codes close to code rate 1 can be obtained with thresholds that stay close to the channel capacity thresholds uniformly. Iterative decoding simulation results are provided. The ARA codes also have projected graph or protograph representation that allows for high speed decoder implementation.

  11. Carbon accumulation rates recorded in the last 150years in tropical high mountain peatlands of the Atlantic Rainforest, SE - Brazil.

    PubMed

    Lourençato, Lúcio F; Caldeira, Pedro P; Bernardes, Marcelo C; Buch, Andressa C; Teixeira, Daniel C; Silva-Filho, Emmanoel V

    2017-02-01

    Peatlands are environmental matrices that store large amounts of organic carbon (TOC) and work as records of environmental changes. Recent record of organic carbon accumulated were assessed in two Forest National Parks, Itatiaia and Serra dos Órgãos in the Southeastern of Brazil. Based on organic and inorganic characterization, the cores from peatlands presented a predominance of organic material in an advanced stage of decomposition and those soils were classified as typical Haplosaprists Histosols. The combination of favorable topographic and climatic conditions led to rapid C accumulation across coastal mountain in the tropical peatlands studied, presenting an average accumulation rate of C, in the last century, of 194gCm(-2)yr(-1) about 7 higher times than the rate found in boreal and subarctic peatlands, those higher values may be related to changes in the hydrological cycle occurred since 1950s.

  12. Inconsistencies between (14)C and short-lived radionuclides-based sediment accumulation rates: Effects of long-term remineralization.

    PubMed

    Baskaran, M; Bianchi, T S; Filley, T R

    2016-09-06

    (14)C is the most widely utilized geochronometer to investigate geological, geochemical and geophysical problems over the past 5 decades. Establishment of precise sedimentation rates is crucial for the reconstruction of paleo-climate, -ecological and - environmental studies when extrapolation of sedimentation rates is utilized for time scales beyond the dating range. However, agreement between short-term and long-term sedimentation rates in anthropogenically unperturbed sediment cores has not been shown. Here we show that the AMS (14)C-based long-term mass accumulation rate (MAR) of an organic-rich (>70%) sediment core from Mud Lake, Florida to be ∼5 times lower than the short-term MAR obtained using (239,240)Pu, (137)Cs and excess (210)Pb ((210)Pbxs). The measured sediment inventories of (210)Pbxs, (137)Cs and (239,240)Pu are comparable to the atmospheric fallout for the sampling site, indicating very little accelerated sediment erosion over the past several decades. Presence of sharp fallout peaks of (239,240)Pu indicates very little sediment mixing. The penetration depths of (137)Cs and (239,240)Pu were found to be much deeper than expected and this is attributed to their post-depositional mobility. MAR calculated using (14)C-ages in successive layers also indicated decreasing MARs with depth, and was reflective of progressive remineralization. Using first-order kinetics, the sediment remineralization rate was found to be 4.4 × 10(-4) y(-1) and propose that over the long-term, remineralization of organic-rich sediment affected the long-term MAR, but not the ratio of (14)C/(12)C. Thus, the MAR and linear sedimentation rate obtained using (14)C (and other isotope-based methods) could be erroneous, although (14)C ages may not be affected by such remineralization. Long-term remineralization rates of organic matter has a direct bearing on the biogeochemical cycling of elements in aqueous systems and mass balance of elements needs to be taken into consideration.

  13. Recent rates of carbon accumulation in montane fens ofYosemite National Park, California, U.S.A.

    USGS Publications Warehouse

    Drexler, Judith; Fuller, Christopher C.; Orlando, James L.; Moore, Peggy E.

    2016-01-01

    Little is known about recent rates of carbon storage in montane peatlands, particularly in the western United States. Here we report on recent rates of carbon accumulation (past 50 to 100 years) in montane groundwater-fed peatlands (fens) of Yosemite National Park in central California, U.S.A. Peat cores were collected at three sites ranging in elevation from 2070 to 2500 m. Core sections were analyzed for bulk density, % organic carbon, and 210Pb activities for dating purposes. Organic carbon densities ranged from 0.026 to 0.065 g C cm-3. Mean vertical accretion rates estimated using210Pb over the 50-year period from ∼1960 to 2011 and the 100-year period from ∼1910 to 2011 were 0.28 (standard deviation = ±0.09) and 0.18 (±-0.04) cm yr-1, respectively. Mean carbon accumulation rates over the 50- and 100-year periods were 95.4 (±25.4) and 74.7 (±17.2) g C m-2 yr-1, respectively. Such rates are similar to recent rates of carbon accumulation in rich fens in western Canada, but more studies are needed to definitively establish both the similarities and differences in peat formation between boreal and temperate montane fens.

  14. Measurements of /sup 10/B(n,He) reaction rates in a mockup control rod in ZPPR

    SciTech Connect

    Brumbach, S.B.; Collins, P.J.; Oliver, B.M.

    1986-01-01

    This paper reports the first direct measurement of /sup 10/B capture rate in a mockup control rod in a critical assembly. The experiment used the helium accumulation fluence monitor (HAFM) technique. 13 refs.

  15. Transverse beam stability measurement and analysis for the SNS accumulator ring

    NASA Astrophysics Data System (ADS)

    Xie, Zaipeng; Deibele, Craig; Schulte, Michael J.; Hu, Yu-Hen

    2015-07-01

    A field-programmable gate array (FPGA)-based transverse feedback damper system was implemented in the Spallation Neutron Source (SNS) accumulator ring with the intention to stabilize the electron-proton (e-p) instability in the frequency range of 1-300 MHz. The transverse feedback damper could also be used as a diagnostic tool by measuring the beam transfer function (BTF). An analysis of the BTF measurements provides the stability diagram for the production beam at SNS. This paper describes the feedback damper system and its setup as the BTF diagnostic tool. Experimental BTF results are presented and beam stability is analyzed by use of the BTF measurements for the SNS accumulator ring.

  16. Character, paleoenvironment, rate of accumulation, and evidence for seismic triggering of Holocene turbidites, Canada Abyssal Plain, Arctic Ocean

    USGS Publications Warehouse

    Grantz, A.; Phillips, R.L.; Mullen, M.W.; Starratt, S.W.; Jones, Glenn A.; Naidu, A.S.; Finney, B.P.

    1996-01-01

    Four box cores and one piston core show that Holocene sedimentation on the southern Canada Abyssal Plain for the last 8010??120 yr has consisted of a continuing rain of pelagic organic and ice-rafted elastic sediment with a net accumulation rate during the late Holocene of ???10 mm/1000 yr, and episodically emplaced turbidites 1-5 m thick deposited at intervals of 830 to 3450 yr (average 2000 yr). The average net accumulation rate of the mixed sequence of turbidites and thin pelagite interbeds in the cores is about 1.2 m/1000 yr. Physiography suggests that the turbidites originated on the Mackenzie Delta or its clinoform, and ??13C values of -27 to - 25??? in the turbidites are compatible with a provenance on a delta. Extant displaced neritic and lower slope to basin plain calcareous benthic foraminifers coexist in the turbidite units. Their joint occurence indicates that the turbidites originated on the modern continental shelf and entrained sediment from the slope and rise enroute to their final resting place on the Canada Abyssal Plain. The presence of Middle Pleistocene diatoms in the turbidites suggests, in addition, that the turbidites may have originated in shallow submarine slides beneath the upper slope or outer shelf. Small but consistent differences in organic carbon content and ??13C values between the turbidite units suggest that they did not share an identical provenance, which is at least compatible with an origin in slope failures. The primary provenance of the ice-rafted component of the pelagic beds was the glaciated terrane of northwestern Canada; and the provenance of the turbidite units was Pleistocene and Holocene sedimentary deposits on the outer continental shelf and upper slope of the Mackenzie Delta. Largely local derivation of the sediment of the Canada Abyssal Plain indicates that sediment accumulation rates in the Arctic Ocean are valid only for regions with similar depositional sources and processes, and that these rates cannot be

  17. ACCUMULATION RATE OF MICROBIAL BIOMASS AT TWO PERMEABLE REACTIVE BARRIER SITES

    EPA Science Inventory

    Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of in-situ Permeable Reactive Barriers for treating contaminated groundwater. Both processes can impact remedial performance by decreasing zero-valent iron reactivity...

  18. Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy.

    PubMed

    Zaccone, Claudio; Lobianco, Daniela; Shotyk, William; Ciavatta, Claudio; Appleby, Peter G; Brugiapaglia, Elisabetta; Casella, Laura; Miano, Teodoro M; D'Orazio, Valeria

    2017-02-23

    Floating islands mysteriously moving around on lakes were described by several Latin authors almost two millennia ago. These fascinating ecosystems, known as free-floating mires, have been extensively investigated from ecological, hydrological and management points of view, but there have been no detailed studies of their rates of accumulation of organic matter (OM), organic carbon (OC) and total nitrogen (TN). We have collected a peat core 4 m long from the free-floating island of Posta Fibreno, a relic mire in Central Italy. This is the thickest accumulation of peat ever found in a free-floating mire, yet it has formed during the past seven centuries and represents the greatest accumulation rates, at both decadal and centennial timescale, of OM (0.63 vs. 0.37 kg/m(2)/yr), OC (0.28 vs. 0.18 kg/m(2)/yr) and TN (3.7 vs. 6.1 g/m(2)/yr) ever reported for coeval peatlands. The anomalously high accretion rates, obtained using (14)C age dating, were confirmed using (210)Pb and (137)Cs: these show that the top 2 m of Sphagnum-peat has accumulated in only ~100 years. As an environmental archive, Posta Fibreno offers a temporal resolution which is 10x greater than any terrestrial peat bog, and promises to provide new insight into environmental changes occurring during the Anthropocene.

  19. Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy

    PubMed Central

    Zaccone, Claudio; Lobianco, Daniela; Shotyk, William; Ciavatta, Claudio; Appleby, Peter G.; Brugiapaglia, Elisabetta; Casella, Laura; Miano, Teodoro M.; D’Orazio, Valeria

    2017-01-01

    Floating islands mysteriously moving around on lakes were described by several Latin authors almost two millennia ago. These fascinating ecosystems, known as free-floating mires, have been extensively investigated from ecological, hydrological and management points of view, but there have been no detailed studies of their rates of accumulation of organic matter (OM), organic carbon (OC) and total nitrogen (TN). We have collected a peat core 4 m long from the free-floating island of Posta Fibreno, a relic mire in Central Italy. This is the thickest accumulation of peat ever found in a free-floating mire, yet it has formed during the past seven centuries and represents the greatest accumulation rates, at both decadal and centennial timescale, of OM (0.63 vs. 0.37 kg/m2/yr), OC (0.28 vs. 0.18 kg/m2/yr) and TN (3.7 vs. 6.1 g/m2/yr) ever reported for coeval peatlands. The anomalously high accretion rates, obtained using 14C age dating, were confirmed using 210Pb and 137Cs: these show that the top 2 m of Sphagnum-peat has accumulated in only ~100 years. As an environmental archive, Posta Fibreno offers a temporal resolution which is 10x greater than any terrestrial peat bog, and promises to provide new insight into environmental changes occurring during the Anthropocene. PMID:28230066

  20. [Estimating of decadal accumulation rates of heavy metals in surface rice soils in the Tai Lake region of China].

    PubMed

    Li, Lianqing; Pan, Genxing; Zhang, Pingjiu; Cheng, Jiemin; Zhu, Qiuhua; Qiu, Duosheng

    2002-05-01

    Estimation of decadal accumulation of some heavy metals in surface rice soils from the Tai Lake region, southern Jiangsu Province, China was made by means of calculating the monitoring data and/or analysis data of the archived soil samples. For the last decade, the estimated annual accumulation rate for Cu or Zn, Pb and Cd was 0.3-1 mg.(kg.a)-1, 0.2-1 mg.(kg.a)-1 and 0.3-3 micrograms.(kg.a)-1 respectively, the apparent pollution loading was, therefore, respectively 0.5-1 kg.(hm2.a)-1, 0.5-1.0 kg.(hm2.a)-1, 0.5-3.0 kg.(hm2.a)-1 [symbol: see text] 0.8-10 x 10(-3) kg.(hm2.a)-1. The accumulation rate for the content of available form was shown to be greater than that of total content. The non-point source pollution marked bigger contribution to the total annual loading for the Pb and Cd than the other source pollutions, while the Cd loading was prominently higher than those reported in Europe. These results may indicate that the food safety in this region may be constrained by the soil pollution of these heavy metals at high accumulation rates.

  1. Three hen strains fed photoisomerized trans,trans CLA-rich soy oil exhibit different yolk accumulation rates and source-specific isomer deposition.

    PubMed

    Shinn, Sara E; Gilley, Alex D; Proctor, Andrew; Anthony, Nicholas B

    2015-04-01

    Most CLA chicken feeding trials used cis,trans (c,t) and trans,cis (t,c) CLA isomers to produce CLA-rich eggs, while reports of trans,trans (t,t) CLA enrichment in egg yolks are limited. The CLA yolk fatty acid profile changes and the 10-12 days of feeding needed for maximum CLA are well documented, but there is no information describing CLA accumulation during initial feed administration. In addition, no information on CLA accumulation rates in different hen strains is available. The aim of this study was to determine a mathematical model that described yolk CLA accumulation and depletion in three hen strains by using t,t CLA-rich soybean oil produced by photoisomerization. Diets of 30-week Leghorns, broilers, and jungle fowl were supplemented with 15% CLA-rich soy oil for 16 days, and eggs were collected for 32 days. Yolk fatty acid profiles were measured by GC-FID. CLA accumulation and depletion was modeled by both quadratic and piecewise regression analysis. A strong quadratic model was proposed, but it was not as effective as piecewise regression in describing CLA accumulation and depletion. Broiler hen eggs contained the greatest concentration of CLA at 3.2 mol/100 g egg yolk, then jungle fowl at 2.9 mol CLA, and Leghorns at 2.3 mol CLA. The t,t CLA isomer levels remained at 55% of total yolk CLA during CLA feeding. However, t-10,c-12 (t,c) CLA concentration increased slightly during CLA accumulation and was significantly greater than c-9,t-11 CLA. Jungle fowl had the smallest increase in yolk saturated fat with CLA yolk accumulation.

  2. Carbon and sediment accumulation in the Everglades (USA) during the past 4000 years: rates, drivers, and sources of error

    USGS Publications Warehouse

    Glaser, Paul H.; Volin, John C.; Givnish, Thomas J.; Hansen, Barbara C. S.; Stricker, Craig A.

    2012-01-01

    Tropical and sub-tropical wetlands are considered to be globally important sources for greenhouse gases but their capacity to store carbon is presumably limited by warm soil temperatures and high rates of decomposition. Unfortunately, these assumptions can be difficult to test across long timescales because the chronology, cumulative mass, and completeness of a sedimentary profile are often difficult to establish. We therefore made a detailed analysis of a core from the principal drainage outlet of the Everglades of South Florida, to assess these problems and determine the factors that could govern carbon accumulation in this large sub-tropical wetland. Accelerator mass spectroscopy dating provided direct evidence for both hard-water and open-system sources of dating errors, whereas cumulative mass varied depending upon the type of method used. Radiocarbon dates of gastropod shells, nevertheless, seemed to provide a reliable chronology for this core once the hard-water error was quantified and subtracted. Long-term accumulation rates were then calculated to be 12.1 g m-2 yr-1 for carbon, which is less than half the average rate reported for northern and tropical peatlands. Moreover, accumulation rates remained slow and relatively steady for both organic and inorganic strata, and the slow rate of sediment accretion ( 0.2 mm yr-1) tracked the correspondingly slow rise in sea level (0.35 mm yr-1 ) reported for South Florida over the past 4000 years. These results suggest that sea level and the local geologic setting may impose long-term constraints on rates of sediment and carbon accumulation in the Everglades and other wetlands.

  3. Significant relationships among frost tolerance and net photosynthetic rate, water use efficiency and dehydrin accumulation in cold-treated winter oilseed rapes.

    PubMed

    Urban, Milan Oldřich; Klíma, Miroslav; Vítámvás, Pavel; Vašek, Jakub; Hilgert-Delgado, Alois Albert; Kučera, Vratislav

    2013-12-15

    Five winter oilseed rape cultivars (Benefit, Californium, Cortes, Ladoga, Navajo) were subjected to 30 days of cold treatment (4 °C) to examine the effect of cold on acquired frost tolerance (FT), dehydrin (DHN) content, and photosynthesis-related parameters. The main aim of this study was to determine whether there are relationships between FT (expressed as LT50 values) and the other parameters measured in the cultivars. While the cultivar Benefit accumulated two types of DHNs (D45 and D35), the other cultivars accumulated three additional DHNs (D97, D47, and D37). The similar-sized DHNs (D45 and D47) were the most abundant; the others exhibited significantly lower accumulations. The highest correlations were detected between LT50 and DHN accumulation (r=-0.815), intrinsic water use efficiency (WUEi; r=-0.643), net photosynthetic rate (r=-0.628), stomatal conductance (r=0.511), and intracellular/intercellular CO2 concentration (r=0.505). Those cultivars that exhibited higher Pn rate in cold (and further a significant increase in WUEi) had higher levels of DHNs and also higher FT. No significant correlation was observed between LT50 and E, PRI, or NDVI. Overall, we have shown the selected physiological parameters to be able to distinguish different FT cultivars of winter oilseed rape.

  4. Constraining mass accumulation rates across the Cretaceous-Paleogene boundary clay layer using extraterrestrial helium-3

    NASA Astrophysics Data System (ADS)

    Giron, M.; Sepulveda, J.; Mukhopadhyay, S.; Alegret, L.; Summons, R. E.

    2012-12-01

    The extended duration of the negative δ13C excursion observed in marine carbonates spanning the Cretaceous-Paleogene (K-Pg) mass extinction event has lead to two main hypothesized post-extinction models ("Strangelove" and "Living Ocean";[1, 2]) for the status of marine primary productivity and the global carbon cycle. However, these models are largely inconsistent with recent paleontological and geochemical evidence suggesting heterogeneous changes in marine productivity and carbon export [3, 4]. While the analysis of lipid biomarkers in the cosmopolitan boundary clay layer allows us to assess changes in primary production by non-calcifying organisms in the immediate aftermath of the mass extinction [4], our poor understanding of the deposition of the clay layer precludes a more detailed reconstruction of short-term variations in marine ecosystem resilience. Here, we present data on extraterrestrial 3He derived from interplanetary dust particles used as a constant flux proxy to constrain fluctuations in mass accumulation rates (MARs) [5] and the duration of the boundary clay deposition in three classic and expanded K-Pg boundary sections: El Kef (Tunisia), Caravaca (Spain), and Kulstirenden (Denmark). Our results from different depositional environments indicate average durations for the sedimentation of the clay layer that are comparable (~10 kyr) to other localities [5], thus confirming its globally brief deposition. Early Paleogene MARs vary among locations when compared to background Late Cretaceous values and do not strictly follow carbonate content as traditionally assumed, thus suggesting variable depositional conditions at different locations. Changes in sediment MARs across the K-Pg will be used to calculate MARs of algal- and bacterial-derived biomarkers, as well as benthic foraminifera, in order to assess the timing and global nature of the recovery of marine primary production and carbon export. 1. Hsu, K.J., He, Q., Mckenzie, J.A., Weissert, H

  5. Simultaneous measurements of ice sheet elevation change, accumulation, and firn compaction using Operation IceBridge data

    NASA Astrophysics Data System (ADS)

    Medley, Brooke; Ligtenberg, Stefan; van den Broeke, Michiel; Gogineni, Sivaprasad; Nowicki, Sophie

    2015-04-01

    Altimetric methods for determination of ice sheet mass balance are extremely valuable as they typically measure large regions of the ice sheet, from basin- to continental-scale. The measured volume change is converted to mass change if the density of the lost material is known. The complication lies in the fact that the observed elevation change consists of two components of differing densities: firn and ice. Annual fluctuations in snow accumulation and firn compaction cause the firn column to vary in thickness, which is often a large component of the total elevation change in the interior since the density of firn is less than that of ice. Further complication arises from the fact that fluctuations in the firn compaction rate do not result in mass change. Therefore, to properly determine mass change, the observed elevation change must be partitioned into accumulation, firn compaction, and ice components. Because altimetry studies are often large in scale, models are used to account for the firn processes, which are coarse in resolution (~10s kilometers) relative to the observed elevation changes (sub-kilometer). Here, we take advantage of a unique opportunity to simultaneously measure surface elevation change, snow accumulation, and firn compaction over the Thwaites catchment in West Antarctica using two Operation IceBridge (OIB) sensors. The firn processes are observed using the Center for Remote Sensing of Ice Sheets (CReSIS) snow radar, and elevation changes are measured using the Airborne Topographic Mapper. Coincident observations such as the aforementioned allow us to not only accurately evaluate mass change over short distances, but also determine the importance of accounting for small-scale variations in firn processes in large-scale (basin-wide to continental) assessments of mass balance. Our results indicate that accumulation rates vary by more than 10% and compaction rates vary by more than 10 cm/yr over distances as little as 5 km in this region. Thus

  6. Measurements of Protein Crystal Face Growth Rates

    NASA Technical Reports Server (NTRS)

    Gorti, S.

    2014-01-01

    Protein crystal growth rates will be determined for several hyperthermophile proteins.; The growth rates will be assessed using available theoretical models, including kinetic roughening.; If/when kinetic roughening supersaturations are established, determinations of protein crystal quality over a range of supersaturations will also be assessed.; The results of our ground based effort may well address the existence of a correlation between fundamental growth mechanisms and protein crystal quality.

  7. Constraint-Free Measurement of Metabolic Rate

    NASA Technical Reports Server (NTRS)

    Koester, K. L.

    1982-01-01

    By using hardware and software originally developed for manned spacecraft, metabolism is now measured while subject wears a loose-fitting mask. This more comfortable, less-restrictive measurement technique uses speed, accuracy and control capabilities of a microcomputer. Because mask imposes minimum interference to subject undergoing testing, it can be used to measure respiratory responses to such activities as treadmill exercise. Mask can be worn for long periods with little discomfort.

  8. Mutation accumulation in real branches: fitness assays for genomic deleterious mutation rate and effect in large-statured plants.

    PubMed

    Schultz, Stewart T; Scofield, Douglas G

    2009-08-01

    The genomic deleterious mutation rate and mean effect are central to the biology and evolution of all species. Large-statured plants, such as trees, are predicted to have high mutation rates due to mitotic mutation and the absence of a sheltered germ line, but their size and generation time has hindered genetic study. We develop and test approaches for estimating deleterious mutation rates and effects from viability comparisons within the canopy of large-statured plants. Our methods, inspired by E. J. Klekowski, are a modification of the classic Bateman-Mukai mutation-accumulation experiment. Within a canopy, cell lineages accumulate mitotic mutations independently. Gametes or zygotes produced at more distal points by these cell lineages contain more mitotic mutations than those at basal locations, and within-flower selfs contain more homozygous mutations than between-flower selfs. The resulting viability differences allow demonstration of lethal mutation with experiments similar in size to assays of genetic load and allow estimates of the rate and effect of new mutations with moderate precision and bias similar to that of classic mutation-accumulation experiments in small-statured organisms. These methods open up new possibilities with the potential to provide valuable new insights into the evolutionary genetics of plants.

  9. The accumulation rate of meteorite falls at the earth's surface - The view from Roosevelt County, New Mexico

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Wells, Gordon L.; Rendell, Helen M.

    1990-01-01

    The discovery of 154 meteorite fragments within an 11-sq km area of wind-excavated basins in Roosevelt County, New Mexico, permits a new calculation of the accumulation rate of meteorite falls at the earth's surface. Thermoluminescence dating of the coversand unit comprising the prime recovery surface suggests the maximum terrestrial age of the meteorites to be about 16.0 ka. The 68 meteorite fragments subjected to petrological analyses represent a minimum of 49 individual falls. Collection bias has largely excluded carbonaceous chondrites and achondrites, requiring the accumulation rate derived from the recovered samples to be increased by a factor of 1.25. Terrestrial weathering destroying ordinary chondrites can be modeled as a first-order decay process with an estimated half-life of 3.5 + or - 1.9 ka on the semiarid American High Plains. Having accounted for the age of the recovery surface, area of field searches, pairing of finds, collection bias and weathering half-life, an accumulation rate of 940 falls/a per 10 to the 6th sq km is calculated for falls greater than 10 g total mass. This figure exceeds the best-constrained previous estimate by more than an order of magnitude. One possible reason for this disparity may be the extraordinary length of the fall record preserved in the surficial geology of Roosevelt County. The high accumulation rate determined for the past 16 ka may point to the existence of periods when the meteorite fall rate was significantly greater than at present.

  10. Formation and distribution of coal measure-derived hydrocarbon accumulation in NW China

    SciTech Connect

    Wenxhi Zhao; Yan Zhang; Dafeng Xu; Changyi Zhao

    1996-12-31

    This study recognizes that the following conditions are necessary for the Jurassic coal measure-derived oil and gas fields in NW China: (1) The Jurassic original basins, which were dominated by lacustrine to low-positional swamp environments, should exist to accept coal-measure related sediments, (2) the original depositional settings were characterized by low and gentle depressions and humid climate where oil-prone organic materials accumulated, (3) the development of the subsequent basins and successive sedimentation should occur on the Jurassic original basins, which are necessary to keep the coal measure source rocks progressively maturing, and, (4) a certain degree of tectonic compression took place soon after the maturation of source rocks, which provided the driving force for the effective expulsion of oil and gas from coal measures. Most of the coal measure-derived oil & gas fields in NW China are horizontally distributed along the inner side of lake strandlines. They occur vertically above or below the threshold of maturation. Owing to the sharp variations of lithology and facies in coal measures, the lithologies and hydrocarbon compositions of oil and gas reservoirs play a significant role in the oil and gas accumulations of the coal measures sequences.

  11. Formation and distribution of coal measure-derived hydrocarbon accumulation in NW China

    SciTech Connect

    Wenxhi Zhao; Yan Zhang; Dafeng Xu; Changyi Zhao )

    1996-01-01

    This study recognizes that the following conditions are necessary for the Jurassic coal measure-derived oil and gas fields in NW China: (1) The Jurassic original basins, which were dominated by lacustrine to low-positional swamp environments, should exist to accept coal-measure related sediments, (2) the original depositional settings were characterized by low and gentle depressions and humid climate where oil-prone organic materials accumulated, (3) the development of the subsequent basins and successive sedimentation should occur on the Jurassic original basins, which are necessary to keep the coal measure source rocks progressively maturing, and, (4) a certain degree of tectonic compression took place soon after the maturation of source rocks, which provided the driving force for the effective expulsion of oil and gas from coal measures. Most of the coal measure-derived oil gas fields in NW China are horizontally distributed along the inner side of lake strandlines. They occur vertically above or below the threshold of maturation. Owing to the sharp variations of lithology and facies in coal measures, the lithologies and hydrocarbon compositions of oil and gas reservoirs play a significant role in the oil and gas accumulations of the coal measures sequences.

  12. Biogenic silica fluxes and accumulation rates in the Gulf of California

    SciTech Connect

    Thunell, R.C.; Pride, C.J.; Tappa, E. ); Muller-Karger, F.E. )

    1994-04-01

    The Gulf of California, though small in size, plays an important role in the global silica cycle. The seasonal pattern of biogenic silica flux in the gulf is closely related to that of phytoplankton biomass levels and is controlled by changes in weather and hydrographic conditions. The highest opal fluxes ([approximately] 0.35 g[center dot]m[sup [minus]2][center dot]d[sup [minus]1]) occur during winter and spring, and they are comparable to those measured in some of the most productive ecosystems of the world. Approximately 15%-25% of the biogenic silica produced in surface waters is preserved in gulf sediments, a figure significantly higher than the average global ocean preservation rate. However, the flux of opal at 500 m water depth is less than 25% of that being produced at the surface, suggesting that most of the recycling of biogenic silica in the Gulf of California occurs in the upper water column. 28 refs., 3 figs.

  13. Measuring Oxygen Consumption Rate in Caenorhabditis elegans

    PubMed Central

    Palikaras, Konstantinos; Tavernarakis, Nektarios

    2017-01-01

    The rate of oxygen consumption is a vital marker indicating cellular function during lifetime under normal or metabolically challenged conditions. It is used broadly to study mitochondrial function (Artal-Sanz and Tavernarakis, 2009; Palikaras et al., 2015; Ryu et al., 2016) or investigate factors mediating the switch from oxidative phosphorylation to aerobic glycolysis (Chen et al., 2015; Vander Heiden et al., 2009). In this protocol, we describe a method for the determination of oxygen consumption rates in the nematode Caenorhabditis elegans. PMID:28239622

  14. Thermal boundary conductance accumulation and interfacial phonon transmission: Measurements and theory

    NASA Astrophysics Data System (ADS)

    Cheaito, Ramez; Gaskins, John T.; Caplan, Matthew E.; Donovan, Brian F.; Foley, Brian M.; Giri, Ashutosh; Duda, John C.; Szwejkowski, Chester J.; Constantin, Costel; Brown-Shaklee, Harlan J.; Ihlefeld, Jon F.; Hopkins, Patrick E.

    2015-01-01

    The advances in phonon spectroscopy in homogeneous solids have unveiled extremely useful physics regarding the contribution of phonon energies and mean-free paths to the thermal transport in solids. However, as material systems decrease to length scales less than the phonon mean-free paths, thermal transport can become much more impacted by scattering and transmission across interfaces between two materials than the intrinsic relaxation in the homogeneous solid. To elucidate the fundamental interactions driving this thermally limiting interfacial phonon scattering process, we analytically derive and experimentally measure a thermal boundary conductance accumulation function. We develop a semiclassical theory to calculate the thermal boundary conductance accumulation function across interfaces using the diffuse mismatch model, and validate this derivation by measuring the interface conductance between eight different metals on native oxide/silicon substrates and four different metals on sapphire substrates. Measurements were performed at room temperature using time-domain thermoreflectance and represent the first-reported values for interface conductance across several metal/native oxide/silicon and metal/sapphire interfaces. The various metal films provide a variable bandwidth of phonons incident on the metal/substrate interface. This method of varying phonons' cutoff frequency in the film while keeping the same substrate allows us to mimic the accumulation of thermal boundary conductance and thus provides a direct method to experimentally validate our theory. We show that the accumulation function can be written as the product of a weighted average of the interfacial phonon transmission function and the accumulation of the temperature derivative of the phonon flux incident on the interface; this provides the framework to extract an average, spectrally dependent phonon transmissivity from a series of thermal boundary conductance measurements. Our approach provides

  15. Automated Speech Rate Measurement in Dysarthria

    ERIC Educational Resources Information Center

    Martens, Heidi; Dekens, Tomas; Van Nuffelen, Gwen; Latacz, Lukas; Verhelst, Werner; De Bodt, Marc

    2015-01-01

    Purpose: In this study, a new algorithm for automated determination of speech rate (SR) in dysarthric speech is evaluated. We investigated how reliably the algorithm calculates the SR of dysarthric speech samples when compared with calculation performed by speech-language pathologists. Method: The new algorithm was trained and tested using Dutch…

  16. Modern Measurements of Uranium Decay Rates

    NASA Astrophysics Data System (ADS)

    Parsons-Moss, T.; Faye, S. A.; Williams, R. W.; Wang, T. F.; Renne, P. R.; Mundil, R.; Harrison, M.; Bandong, B. B.; Moody, K.; Knight, K. B.

    2015-12-01

    It has been widely recognized that accurate and precise decay constants (λ) are critical to geochronology as highlighted by the EARTHTIME initiative, particularly the calibration benchmarks λ235U and λ238U. [1] Alpha counting experiments in 1971[2] measured λ235U and λ238U with ~0.1% precision, but have never been independently validated. We are embarking on new direct measurements of λ235U, λ238U, λ234Th, and λ234U using independent approaches for each nuclide. For the measurement of λ235U, highly enriched 235U samples will be chemically purified and analyzed for U concentration and isotopic composition by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Thin films will be electrodeposited from these solutions and the α activity will be measured in an α-γ coincidence counting apparatus, which allows reduced uncertainty in counting efficiency while achieving adequate counting statistics. For λ238U measurement we will measure ingrowth of 234Th in chemically purified, isotopically enriched 238U solutions, by quantitatively separating the Th and allowing complete decay to 234U. All of the measurements will be done using MC-ICP-MS aiming at 0.05% precision. This approach is expected to result in values of λ238U with less than 0.1% uncertainty, if combined with improved λ234Th measements. These will be achieved using direct decay measurements with an E-∆E charged particle telescope in coincidence with a gamma detector. This system allows measurement of 234Th β-decay and simultaneous detection and identification of α particles emitted by the 234U daughter, thus observing λ234U at the same time. The high-precision λ234U obtained by the direct activity measurements can independently verify the commonly used values obtained by indirect methods.[3] An overarching goal of the project is to ensure the quality of results including metrological traceability in order to facilitate implementation across diverse disciplines. [1] T

  17. Experimental measurement and modeling of snow accumulation and snowmelt in a mountain microcatchment

    NASA Astrophysics Data System (ADS)

    Danko, Michal; Krajčí, Pavel; Hlavčo, Jozef; Kostka, Zdeněk; Holko, Ladislav

    2016-04-01

    Fieldwork is a very useful source of data in all geosciences. This naturally applies also to the snow hydrology. Snow accumulation and snowmelt are spatially very heterogeneous especially in non-forested, mountain environments. Direct field measurements provide the most accurate information about it. Quantification and understanding of processes, that cause these spatial differences are crucial in prediction and modelling of runoff volumes in spring snowmelt period. This study presents possibilities of detailed measurement and modeling of snow cover characteristics in a mountain experimental microcatchment located in northern part of Slovakia in Western Tatra mountains. Catchment area is 0.059 km2 and mean altitude is 1500 m a.s.l. Measurement network consists of 27 snow poles, 3 small snow lysimeters, discharge measurement device and standard automatic weather station. Snow depth and snow water equivalent (SWE) were measured twice a month near the snow poles. These measurements were used to estimate spatial differences in accumulation of SWE. Snowmelt outflow was measured by small snow lysimeters. Measurements were performed in winter 2014/2015. Snow water equivalent variability was very high in such a small area. Differences between particular measuring points reached 600 mm in time of maximum SWE. The results indicated good performance of a snow lysimeter in case of snowmelt timing identification. Increase of snowmelt measured by the snow lysimeter had the same timing as increase in discharge at catchment's outlet and the same timing as the increase in air temperature above the freezing point. Measured data were afterwards used in distributed rainfall-runoff model MIKE-SHE. Several methods were used for spatial distribution of precipitation and snow water equivalent. The model was able to simulate snow water equivalent and snowmelt timing in daily step reasonably well. Simulated discharges were slightly overestimated in later spring.

  18. Complementary system for long term measurements of radon exhalation rate from soil

    SciTech Connect

    Mazur, J.; Kozak, K.

    2014-02-15

    A special set-up for continuous measurements of radon exhalation rate from soil is presented. It was constructed at Laboratory of Radiometric Expertise, Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN), Krakow, Poland. Radon exhalation rate was determined using the AlphaGUARD PQ2000 PRO (Genitron) radon monitor together with a special accumulation container which was put on the soil surface during the measurement. A special automatic device was built and used to raise and lower back onto the ground the accumulation container. The time of raising and putting down the container was controlled by an electronic timer. This set-up made it possible to perform 4–6 automatic measurements a day. Besides, some additional soil and meteorological parameters were continuously monitored. In this way, the diurnal and seasonal variability of radon exhalation rate from soil can be studied as well as its dependence on soil properties and meteorological conditions.

  19. Feed rate measuring method and system

    DOEpatents

    Novak, James L.; Wiczer, James J.

    1995-01-01

    A system and method are provided for establishing the feed rate of a workpiece along a feed path with respect to a machine device. First and second sensors each having first and second sensing electrodes which are electrically isolated from the workpiece are positioned above, and in proximity to the desired surfaces of the workpiece along a feed path. An electric field is developed between the first and second sensing electrodes of each sensor and capacitance signals are developed which are indicative of the contour of the workpiece. First and second image signals representative of the contour of the workpiece along the feed path are developed by an image processor. The time delay between corresponding portions of the first and second image signals are then used to determine the feed rate based upon the separation of the first and second sensors and the amount of time between corresponding portions of the first and second image signals.

  20. Feed rate measuring method and system

    DOEpatents

    Novak, J.L.; Wiczer, J.J.

    1995-12-05

    A system and method are provided for establishing the feed rate of a workpiece along a feed path with respect to a machine device. First and second sensors each having first and second sensing electrodes which are electrically isolated from the workpiece are positioned above, and in proximity to the desired surfaces of the workpiece along a feed path. An electric field is developed between the first and second sensing electrodes of each sensor and capacitance signals are developed which are indicative of the contour of the workpiece. First and second image signals representative of the contour of the workpiece along the feed path are developed by an image processor. The time delay between corresponding portions of the first and second image signals are then used to determine the feed rate based upon the separation of the first and second sensors and the amount of time between corresponding portions of the first and second image signals. 18 figs.

  1. Net ecosystem production: A comprehensive measure of net carbon accumulation by ecosystems

    USGS Publications Warehouse

    Randerson, J.T.; Chapin, F. S.; Harden, J.W.; Neff, J.C.; Harmon, M.E.

    2002-01-01

    The conceptual framework used by ecologists and biogeochemists must allow for accurate and clearly defined comparisons of carbon fluxes made with disparate techniques across a spectrum of temporal and spatial scales. Consistent with usage over the past four decades, we define "net ecosystem production" (NEP) as the net carbon accumulation by ecosystems. Past use of this term has been ambiguous, because it has been used conceptually as a measure of carbon accumulation by ecosystems, but it has often been calculated considering only the balance between gross primary production (GPP) and ecosystem respiration. This calculation ignores other carbon fluxes from ecosystems (e.g., leaching of dissolved carbon and losses associated with disturbance). To avoid conceptual ambiguities, we argue that NEP be defined, as in the past, as the net carbon accumulation by ecosystems and that it explicitly incorporate all the carbon fluxes from an ecosystem, including autotrophic respiration, heterotrophic respiration, losses associated with disturbance, dissolved and particulate carbon losses, volatile organic compound emissions, and lateral transfers among ecosystems. Net biome productivity (NBP), which has been proposed to account for carbon loss during episodic disturbance, is equivalent to NEP at regional or global scales. The multi-scale conceptual framework we describe provides continuity between flux measurements made at the scale of soil profiles and chambers, forest inventories, eddy covariance towers, aircraft, and inversions of remote atmospheric flask samples, allowing a direct comparison of NEP estimates made at all temporal and spatial scales.

  2. Accumulation of advanced glycation end products, measured as skin autofluorescence, in renal disease.

    PubMed

    Hartog, Jasper W L; de Vries, Aiko P J; Lutgers, Helen L; Meerwaldt, Robbert; Huisman, Roel M; van Son, Willem J; de Jong, Paul E; Smit, Andries J

    2005-06-01

    Advanced glycation end products (AGEs) accumulate during renal failure and dialysis. Kidney transplantation is thought to reverse this accumulation by restoring renal function. Using a noninvasive and validated autofluorescence reader, we evaluated AGE levels in 285 transplant recipients (mean age, 52 years; range, 41 to 60 years), 32 dialysis patients (mean age, 56 years; range, 43 to 65 years), and 231 normal control subjects (mean age, 51 years; range, 40 to 65 years). Measurements in transplant recipients were performed for a mean of 73 months (range, 32 to 143 months) after transplantation. Dialysis patients were on dialysis therapy for a mean of 42 months (range, 17 to 107 months). Fluorescence was significantly increased in dialysis patients compared with normal control subjects (2.8 vs. 2.0 arbitrary units [a.u.], P < .0001). Although fluorescence levels were significantly decreased in transplant recipients compared with dialysis patients (2.5 vs. 2.8 a.u., P < .0001), fluorescence in transplant recipients was higher than in controls (2.5 vs. 2.0 a.u., P < .0001). In transplant recipients, fluorescence correlated positively with the duration of dialysis prior to transplantation (R = 0.21, P < .0001), and negatively with creatinine clearance (R = -0.34, P < .0001). No correlation was found between time after transplantation and fluorescence in transplant recipients (R = -0.10, P = .10). Fluorescence in dialysis patients was positively correlated with duration of dialysis (R = 0.36, P = .042). Our results, like those of others, suggest that kidney transplantation does not fully correct increased AGE levels found in dialysis patients. The increased AGE levels in kidney transplant recipients cannot be explained by the differences in renal function alone. The availability of a simple, noninvasive method (AGE-Reader) to measure AGE accumulation may be used to monitor AGE accumulation in a clinical setting as well as in a study setting.

  3. Measurement of snow interception and canopy effects on snow accumulation and melt in a mountainous maritime climate, Oregon, United States

    NASA Astrophysics Data System (ADS)

    Storck, Pascal; Lettenmaier, Dennis P.; Bolton, Susan M.

    2002-11-01

    The results of a 3 year field study to observe the processes controlling snow interception by forest canopies and under canopy snow accumulation and ablation in mountain maritime climates are reported. The field study was further intended to provide data to develop and test models of forest canopy effects on beneath-canopy snowpack accumulation and melt and the plot and stand scales. Weighing lysimeters, cut-tree experiments, and manual snow surveys were deployed at a site in the Umpqua National Forest, Oregon (elevation 1200 m). A unique design for a weighing lysimeter was employed that allowed continuous measurements of snowpack evolution beneath a forest canopy to be taken at a scale unaffected by variability in canopy throughfall. Continuous observations of snowpack evolution in large clearings were made coincidentally with the canopy measurements. Large differences in snow accumulation and ablation were observed at sites beneath the forest canopy and in large clearings. These differences were not well described by simple relationships between the sites. Over the study period, approximately 60% of snowfall was intercepted by the canopy (up to a maximum of about 40 mm water equivalent). Instantaneous sublimation rates exceeded 0.5 mm per hour for short periods. However, apparent average sublimation from the intercepted snow was less than 1 mm per day and totaled approximately 100 mm per winter season. Approximately 72 and 28% of the remaining intercepted snow was removed as meltwater drip and large snow masses, respectively. Observed differences in snow interception rate and maximum snow interception capacity between Douglas fir (Pseudotsuga menziesii), white fir (Abies concolor), ponderosa pine (Pinus ponderosa), and lodgepole pine (Pinus contorta) were minimal.

  4. Measuring Transpiration to Regulate Winter Irrigation Rates

    SciTech Connect

    Samuelson, Lisa

    2006-11-08

    Periodic transpiration (monthly sums) in a young loblolly pine plantation between ages 3 and 6 was measured using thermal dissipation probes. Fertilization and fertilization with irrigation were better than irrigation alone in increasing transpiration of young loblolly pines during winter months, apparently because of increased leaf area in fertilized trees. Irrigation alone did not significantly increase transpiration compared with the non-fertilized and non-irrigated control plots.

  5. Measurement of radon/thoron exhalation rates and gamma-ray dose rate in granite areas in Japan.

    PubMed

    Prasad, G; Ishikawa, T; Hosoda, M; Sahoo, S K; Kavasi, N; Sorimachi, A; Tokonami, S; Uchida, S

    2012-11-01

    Radon and thoron exhalation rates and gamma-ray dose rate in different places in Hiroshima Prefecture were measured. Exhalation rates were measured using an accumulation chamber method. The radon exhalation rate was found to vary from 3 to 37 mBq m(-2) s(-1), while the thoron exhalation rate ranged from 40 to 3330 mBq m(-2) s(-1). The highest radon exhalation rate (37 mBq m(-2) s(-1)) and gamma-ray dose rate (92 nGy h(-1)) were found in the same city (Kure City). In Kure City, indoor radon and thoron concentrations were previously measured at nine selected houses using a radon-thoron discriminative detector (Raduet). The indoor radon concentrations varied from 16 to 78 Bq m(-3), which was higher than the average value in Japan (15.5 Bq m(-3)). The indoor thoron concentration ranged from ND (not detected: below a detection limit of approximately 10 Bq m(-3)) to 314 Bq m(-3). The results suggest that radon exhalation rate from the ground is an influential factor for indoor radon concentration.

  6. Vadose Zone Infiltration Rates from Sr isotope Measurements

    NASA Astrophysics Data System (ADS)

    Maher, K.; Maher, K.; DePaolo, D. J.; DePaolo, D. J.; Conrad, M.

    2001-12-01

    Predicting infiltration rates and recharge through the vadose zone in arid regions is difficult and hence developing methods for the measurement of infiltration rates is important. We have been investigating the use of Sr isotope measurements for determining infiltration at the 200 Area plateau on the Hanford reservation in central Washington. In this context, infiltration affects the transport of contaminants to the water table as well as recharge of the groundwater system. Using Sr isotopes for this purpose requires drill core and water samples from the vadose zone, although leaches of the cores can substitute for water samples. Complementary information, including some constraints on regional recharge, can also be obtained using water samples from groundwater monitoring wells. The VZ method is based on the fact that the Sr isotope ratio of soil water just below the surface is often set by dissolution of aeolian material including carbonate, and this ratio is different from the average value in the deeper underlying vadose zone rock matrix. As water infiltrates, the Sr isotopic composition of the water changes toward the rock values as a result of Sr released from the rocks by weathering reactions. The rate of change with depth of the Sr isotope ratio of the vadose zone water is a function ultimately of q/R; the ratio of the infiltration flux (q) to the bulk rock weathering rate (R). Where it is possible to evaluate R, q can be estimated. As data accumulate it may be possible to improve the calibration of the method. At Hanford the vadose zone rock material is mostly unconsolidated sand, silt, and gravel of broadly granitic composition, which constitute the Hanford and Ringold formations. Annual precipitation is about 160 mm/yr. Drilling and coring of a ca. 70m hole to the water table in 1999 as part of the Hanford groundwater monitoring program, in a relatively undisturbed area of the site, allowed us to generate a unique Sr isotope data set. The Sr isotope

  7. The impact of EDTA on the rate of accumulation and root/shoot partitioning of cadmium in mature dwarf sunflowers.

    PubMed

    Meighan, Michelle M; Fenus, Taressa; Karey, Emma; MacNeil, Joseph

    2011-06-01

    In addition to increasing the mobility of metal ions in the soil solution, chelating agents such as EDTA have been reported to alter both the total metal accumulated by plants and its distribution within the plant structures. Here, mature Mini-Sun Hybrid dwarf sunflowers exposed to 300 μM Cd(2+) in hydroponic solution had initial translocation rates of at least 0.12 mmol kg(-1)h(-1) and reached leaf saturation levels within a day when a 3-fold molar excess of EDTA was used. EDTA also promoted cadmium transfer from roots to the shoots. A threefold excess of EDTA increased the translocation factor (TF) 100-fold, resulting in cadmium levels in the leaves of 580 μg g(-1) and extracting 1400 μg plant(-1). When plants were exposed to dissolved cadmium without EDTA, the vast majority of the metal remained bound to the exterior of the root. The initial accumulation could be successfully modeled with a standard biosorption pseudo second-order kinetic equation. Initial accumulation rates ranged from 0.0359 to 0.262 mg g(-1)min(-1). The cadmium binding could be cycled, and did not show evidence of saturation under the experimental conditions employed, suggesting it might be a viable biosorbant for aqueous cadmium.

  8. Net accumulation rates derived from ice core stable isotope records of Pío XI glacier, Southern Patagonia Icefield

    NASA Astrophysics Data System (ADS)

    Schwikowski, M.; Schläppi, M.; Santibañez, P.; Rivera, A.; Casassa, G.

    2012-12-01

    Pío XI, the largest glacier of the Southern Patagonia Icefield, reached its neoglacial maximum extent in 1994 and is one of the few glaciers in that area which is not retreating. In view of the recent warming it is important to understand glacier responses to climate changes. Due to its remoteness and the harsh conditions in Patagonia, no systematic mass balance studies have been performed. In this study we derived net accumulation rates for the period 2000 to 2006 from a 50 m (33.2 4 m weq) ice core collected in the accumulation area of Pío XI (2600 m a.s.l., 49°16´40´´ S, 73°21´14´´ W). Borehole temperatures indicate near temperate ice, but the average melt percent is only 16% ± 14%. Records of stable isotopes are well preserved and were used for identification of annual layers. Net accumulation rates range from 3.4 to 7.1 water equivalent (m weq) with an average of 5.8 m weq, comparable to precipitation amounts at the Chilean coast, but not as high as expected for the Icefield. Ice core stable isotope data correlate well with upper air temperatures and may be used as temperature proxy.

  9. Accumulate-Repeat-Accumulate-Accumulate-Codes

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Dolinar, Sam; Thorpe, Jeremy

    2004-01-01

    Inspired by recently proposed Accumulate-Repeat-Accumulate (ARA) codes [15], in this paper we propose a channel coding scheme called Accumulate-Repeat-Accumulate-Accumulate (ARAA) codes. These codes can be seen as serial turbo-like codes or as a subclass of Low Density Parity Check (LDPC) codes, and they have a projected graph or protograph representation; this allows for a high-speed iterative decoder implementation using belief propagation. An ARAA code can be viewed as a precoded Repeat-and-Accumulate (RA) code with puncturing in concatenation with another accumulator, where simply an accumulator is chosen as the precoder; thus ARAA codes have a very fast encoder structure. Using density evolution on their associated protographs, we find examples of rate-lJ2 ARAA codes with maximum variable node degree 4 for which a minimum bit-SNR as low as 0.21 dB from the channel capacity limit can be achieved as the block size goes to infinity. Such a low threshold cannot be achieved by RA or Irregular RA (IRA) or unstructured irregular LDPC codes with the same constraint on the maximum variable node degree. Furthermore by puncturing the accumulators we can construct families of higher rate ARAA codes with thresholds that stay close to their respective channel capacity thresholds uniformly. Iterative decoding simulation results show comparable performance with the best-known LDPC codes but with very low error floor even at moderate block sizes.

  10. Early phase tumor accumulation of macromolecules: a great difference in clearance rate between tumor and normal tissues.

    PubMed

    Noguchi, Y; Wu, J; Duncan, R; Strohalm, J; Ulbrich, K; Akaike, T; Maeda, H

    1998-03-01

    The objective of this study was to investigate the molecular weight (MW) and time-dependence of the phenomenon termed "the enhanced permeability and retention" (EPR) effect in solid tumor, in particular to determine and define the early phase accumulation of macromolecules in tumor and normal tissues and the relationship between blood concentration and tissue clearance. As a model, radioiodinated N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers of MW ranging from 4.5 K to 800 K were administered i.v. to mice bearing sarcoma 180 tumor. Within 10 min all HPMA copolymers accumulated effectively in the tumor regardless of MW (1.0-1.5% of injected dose per g of tumor). However, higher MW copolymers (> 50 K) showed significantly increased tumor accumulation after 6 h, while the lower MW copolymers (< 40 K) were cleared rapidly from tumor tissue due to rapid diffusion back into the bloodstream. Blood clearance was also MW-dependent; the lower MW copolymers displayed rapid clearance, with kidney radioactivity of the copolymers of MW < 20 K representing 24% of injected dose per g kidney at 1 min after i.v. administration. Within 10 min these copolymers passed through the kidney and were excreted in the urine. Higher MW copolymers consistently showed kidney levels of 3-5% dose per g kidney in the early phase with no time-dependent accumulation in kidney. There was also no progressive accumulation in muscle or liver, regardless of polymer MW. These results suggest the "EPR effect" in solid tumor primarily arises from in the difference in clearance rate between the solid tumor and the normal tissues after initial penetration of the polymers into these tissues.

  11. Geologic ages and accumulation rates of basalt-flow groups and sedimentary interbeds in selected wells at the Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Anderson, S.R.; Liszewski, M.J.; Cecil, L.D.

    1997-01-01

    Geologic ages and accumulation rates, estimated from regressions, were used to evaluate measured ages and interpreted stratigraphic and structural relations of basalt and sediment in the unsaturated zone and the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL) in eastern Idaho. Geologic ages and accumulation rates were estimated from standard linear regressions of 21 mean potassium-argon (K-Ar) ages, selected mean paleomagnetic ages, and cumulative depths of a composite stratigraphic section composed of complete intervals of basalt and sediment that were deposited in areas of past maximum subsidence. Accumulation rates also were estimated from regressions of stratigraphic intervals in three wells in and adjacent to an area of interpreted uplift at and near the Idaho Chemical Processing Plant (ICPP) and the Test Reactor Area (TRA) to allow a comparison of rates in areas of past uplift and subsidence. Estimated geologic ages range from about 200 thousand to 1.8 million years before present and are reasonable approximations for the interval of basalt and sediment above the effective base of the aquifer, based on reported uncertainties of corresponding measured ages. Estimated ages between 200 and 800 thousand years are within the range of reported uncertainties for all 15 K-Ar ages used in regressions and two out of three -argon ({sup 40}Ar/{sup 39}Ar) ages of duplicate argon samples. Two sets of estimated ages between 800 thousand and 1.8 million years are within the range of reported uncertainties for all seven K-Ar ages used in regressions, which include one shared age of about 800 thousand years. Two sets of ages were estimated for this interval because K-Ar ages make up two populations that agree with previous and revised ages of three paleomagnetic subchrons. The youngest set of ages is consistent with a K-Ar age from the effective base of the aquifer that agrees with previous ages of the Olduvai Normal-Polarity Subchron.

  12. A method to reconstruct past accumulation rates in alpine firn regions: A study on Fiescherhorn, Swiss Alps

    NASA Astrophysics Data System (ADS)

    Schwerzmann, Aurel; Funk, Martin; Blatter, Heinz; Lüthi, Martin; Schwikowski, Margit; Palmer, Anne

    2006-03-01

    Annual snow layers in the accumulation zone of glaciers become thinner by viscous deformation while moving to greater depth. The reconstruction of the accumulation rate history requires the correction of the thickness of annual layers. We apply a novel method to determine the vertical velocity by repeated survey with a caliper probe of grooves scratched into the wall of a borehole. With this information and the assumptions of steady state velocity and density fields, the correction of layer thicknesses can be determined without knowledge of the ice density profile and thus can be applied to boreholes without ice cores. The method is applied to a borehole on Fiescherhorn, Swiss Alps, resulting in a substantially larger correction than with the simpler method of Nye (1963).

  13. Mercury accumulation in caged Corbicula: rate of uptake and seasonal variation.

    PubMed

    Neufeld, Douglas S G

    2010-09-01

    The uptake and seasonal fluctuations of total mercury were followed in caged and uncaged Asiatic clams, Corbicula fluminea, over a 1-year period in South River, Virginia. Mercury was rapidly accumulated in clams transplanted from a nominally uncontaminated site into cages on the contaminated South River, reaching 0.99 microg g(-1) dry mass within the first month. Resident clams moved to cages had higher mercury contents after the first month (2.04 microg g(-1) dry mass) and at all subsequent times in the study. Large monthly fluctuations in mercury were noted for both resident caged and transplant caged clams with a notable peak occurring in early spring (4.31 microg g(-1) dry mass in resident caged clams). Tissue mass of caged clams steadily increased through the winter and early spring. Adjustment of mercury concentrations for tissue mass changes indicated that the changes in mercury contents were primarily due to uptake/release rather than changes in tissue mass (concentration/dilution). The present study demonstrates the utility of using caged Corbicula as mercury biomonitors and illustrates the importance of accounting for large, short-term changes of mercury content in Corbicula when designing long-term biomonitoring studies.

  14. Flowmeter measures flow rates of high temperature fluids

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1966-01-01

    Flowmeter in which flow rate is determined by measuring the position and thus the displacement of an internal float acted upon by the flowing fluid determines the flow rates of various liquid metals at elevated temperatures. Viscous forces cause the float to move from its mounted position, affording several means for measuring this motion and the flow rate.

  15. Accumulation Rates in the Dry Snow Zone of the Greenland Ice Sheet Inferred from L-band InSAR Data

    NASA Astrophysics Data System (ADS)

    Chen, A. C.; Zebker, H. A.

    2012-12-01

    The Greenland ice sheet contains about 2.9 million km3 of ice and would raise global sea levels by about 7.1 m if it melted completely. Two unusually large iceberg calving events at Petermann Glacier in the past several years, along with the unusually large extent of ice sheet melt this summer point to the relevance of understanding the mass balance of the Greenland ice sheet. In this study, we use data from the PALSAR instrument aboard the ALOS satellite to form L-band (23-centimeter carrier wavelength) InSAR images of the dry snow zone of the Greenland ice sheet. We form geocoded differential interferograms, using the ice sheet elevation model produced by Howat et.al. [1]. By applying phase and radiometric calibration, we can examine interferograms formed between any pair of transmit and receive polarization channels. In co-polarized interferograms, the InSAR correlation ranges from about 0.35 at the summit (38.7 deg W, 73.0 deg N) where accumulation is about 20 cm w.e./yr to about 0.70 at the north-eastern part of the dry snow zone (35.1 deg W, 77.1 deg N), where accumulation is about 11.7 cm w.e./yr. Cross-polarized interferograms show similar geographic variation with overall lower correlation. We compare our InSAR data with in-situ measurements published by Bales et.al. [2]. We examine the applicability of dense-medium radiative transfer electromagnetic scattering models for estimating accumulation rates from L-band InSAR data. The large number and broad coverage of ALOS scenes acquired between 2007 and 2009 with good InSAR coherence at 46-day repeat times and 21.5 degree incidence angles gives us the opportunity to examine the empirical relationship between in-situ accumulation rate observations and the polarimetric InSAR correlation and radar brightness at this particular imaging geometry. This helps us quantify the accuracy of accumulation rates estimated from InSAR data. In some regions, 46-day interferograms acquired in the winters of several consecutive

  16. Measuring rates of outdoor airflow into HVAC systems

    SciTech Connect

    Fisk, William J.; Faulkner, David; Sullivan, Douglas P.; Delp, Woody

    2002-10-01

    During the last few years, new technologies have been introduced for measuring the flow rates of outside air into HVAC systems. This document describes one particular technology for measuring these airflows, a system and a related protocol developed to evaluate this and similar measurement technologies under conditions without wind, and the results of our evaluations. We conclude that the measurement technology evaluated can provide a reasonably accurate measurement of OA flow rate over a broad range of flow, without significantly increasing airflow resistance.

  17. Sediment accumulation rates in Conowingo Reservoir as determined by man-made and natural radionuclides

    SciTech Connect

    McLean, R.I.; Domotor, S.L. ); Summers, J.K.; Wilson, H. ); Olsen, C.R.; Larsen, I.L. )

    1991-05-01

    The Susquehanna River is the major contributor to sediment loadings in the Chesapeake Bay. Because many environmental contaminants are associated with suspended particulates, the degree of particle retention within the reservoirs of the lower Susquehanna River is an important consideration in evaluating contaminant loadings to the Chesapeake Bay. Profiles of weapons-test Cs-137, nuclear power plant-related Cs-134 and Cs-137, and naturally-derived Pb-210 were used to estimate rates of sediment accretion in the Conowingo Reservoir,an impoundmment of the Susquehanna River along the Maryland-Pennsylvania border. Net accretion rates ranged from about 2 cm yr{sup {minus}1} downstream of a nuclear power plant cooling discharge to a high of about 7 cm yr{sup {minus}1} at the mount of an incoming creek. Slight, but consistent, increases in the annual rate of accretion since the creation of the reservoir in 1928 are apparent. The current net average annual sediment load retained by the reservoir is estimated to be 0.4 {times} 10{sup 6} to 1.5 {times} 10{sup 6} metric tons yr{sup {minus}1}. The retained sediment load represents about 8-23% of the long-time average sediment input to the reservoir.

  18. The use of relaxed eddy accumulation to measure biosphere-atmosphere exchange of isoprene and other biological trace gases.

    PubMed

    Bowling, D R; Turnipseed, A A; Delany, A C; Baldocchi, D D; Greenberg, J P; Monson, R K

    1998-09-01

    The micrometeorological flux measurement technique known as relaxed eddy accumulation (REA) holds promise as a powerful new tool for ecologists. The more popular eddy covariance (eddy correlation) technique requires the use of sensors that can respond at fast rates (10 Hz), and these are unavailable for many ecologically relevant compounds. In contrast, the use of REA allows flux measurement with sensors that have much slower response time, such as gas chromatography and mass spectrometry. In this review, relevant micrometeorological details underlying REA are presented, and critical analytical and system design details are discussed, with the goal of introducing the technique and its potential applications to ecologists. The validity of REA for measuring fluxes of isoprene, a photochemically reactive hydrocarbon emitted by several plant species, was tested with measurements over an oak-hickory forest in the Walker Branch Watershed in eastern Tennessee. Concurrent eddy covariance measurements of isoprene flux were made using a newly available chemiluminesence instrument. Excellent agreement was obtained between the two techniques (r (2) = 0.974, n = 62), providing the first direct comparison between REA and eddy covariance for measuring the flux rate of a reactive compound. The influence of a bias in vertical wind velocity on the accuracy of REA was examined. This bias has been thought to be a source of significant error in the past. Measurements of normalized bias ([Formula: see text]) alone would lead us to think that a large potential error exists at this site. However, with our isoprene data and through simulations of REA with fast-response H2O and CO2 data, we conclude that accurate REA flux measurements can be made even in the presence of a bias in w.

  19. Determination of lake sediment accumulation rates in an agricultural watershed using lead-210 and cesium-137

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying the impact of erosion control practices in watersheds remains a difficult problem. It is rare for the application of management practices to be followed by measurements that can indicate the effectiveness of practices. The expense and time associated with erosion monitoring, along with...

  20. Comparison of annual accumulation rates derived from in situ and ground penetrating radar methods across Alaskan glaciers

    NASA Astrophysics Data System (ADS)

    McGrath, D.; Gusmeroli, A.; Oneel, S.; Sass, L. C.; Arendt, A. A.; Wolken, G. J.; Kienholz, C.; McNeil, C.

    2013-12-01

    Constraining annual snowfall accumulation in mountain glacier environments is essential for determining the annual mass balance of individual glaciers and predicting seasonal meltwater runoff to river and marine ecosystems. However, large spatial and elevation gradients, coupled with sparse point measurements preclude accurate quantification of this variable using traditional methods. Here, we report on an extensive field campaign conducted in March-May 2013 on key benchmark glaciers in Alaska, including Taku Glacier near Juneau, Scott Glacier near Cordova, both Eklutna and Wolverine Glacier near Anchorage and Gulkana Glacier in the interior Alaska Range. Over 50 km of 500 MHz common-offset ground penetrating radar (GPR) surveys were collected on each glacier, with an emphasis on capturing spatial variability in the accumulation zone. Frequent in situ observations were collected for comparison with the GPR, including probe depths, snow pits and shallow firn cores (~8 m). We report on spatial and elevation gradients across this suite of glaciers and across numerous climatic zones and discuss differences between GPR and in situ derived annual accumulation estimates. This comparison is an essential first step in order to effectively evaluate regional atmospheric re-analysis products.

  1. Measurement of seedling growth rate by machine vision

    NASA Astrophysics Data System (ADS)

    Howarth, M. Scott; Stanwood, Phillip C.

    1993-05-01

    Seed vigor and germination tests have traditionally been used to determine deterioration of seed samples. Vigor tests describe the seed potential to emerge and produce a mature crop under certain field conditions and one measure is seedling growth rate. A machine vision system was developed to measure root growth rate over the entire germination period. The machine vision measurement technique was compared to the manual growth rate technique. The vision system provided similar growth rate measurements as compared to the manual growth rate technique. The average error between the system and a manual measurement was -0.13 for the lettuce test and -0.07 for the sorghum test. This technique also provided an accurate representation of the growth rate as well as percent germination.

  2. Effect of self-alkalization on nitrite accumulation in a high-rate denitrification system: Performance, microflora and enzymatic activities.

    PubMed

    Li, Wei; Shan, Xiao-Yu; Wang, Zhi-Yao; Lin, Xiao-Yu; Li, Chen-Xu; Cai, Chao-Yang; Abbas, Ghulam; Zhang, Meng; Shen, Li-Dong; Hu, Zhi-Qiang; Zhao, He-Ping; Zheng, Ping

    2016-01-01

    The self-alkalization of denitrifying automatic circulation (DAC) reactor resulted in a large increase of pH up to 9.20 and caused a tremendous accumulation of nitrite up to 451.1 ± 49.0 mgN L(-1) at nitrate loading rate (NLR) from 35 kgN m(-3) d(-1) to 55 kgN m(-3) d(-1). The nitrite accumulation was greatly relieved even at the same NLR once the pH was maintained at 7.6 ± 0.2 in the system. Enzymatic assays indicated that the long-term bacterial exposure to high pH significantly inhibited the activity of copper type nitrite reductase (NirK) rather than the cytochrome cd1 type nitrite reductase (NirS). The terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the dominant denitrifying bacteria shifted from the NirS-containing Thauear sp. 27 to the NirK-containing Hyphomicrobium nitrativorans strain NL23 during the self-alkalization. The significant nitrite accumulation in the high-rate denitrification system could be therefore, due to the inhibition of Cu-containing NirK by high pH from the self-alkalization. The results suggest that the NirK-containing H. nitrativorans strain NL23 could be an ideal functional bacterium for the conversion of nitrate to nitrite, i.e. denitritation, which could be combined with anaerobic ammonium oxidation (Anammox) to develop a new process for nitrogen removal from wastewater.

  3. Rate of denitrification and the accumulation of intermediates in a denitrifying bioreactor

    NASA Astrophysics Data System (ADS)

    Parsignault, D. R.; Gursky, H.; Kellogg, E. M.; Matilsky, T.; Murray, S.; Schreier, E.; Tananbaum, H.; Giacconi, R.; Brinkman, A. C.

    2012-12-01

    Denitrifying bioreactors (DNBRs) are an emerging mechanism to mitigate the impact of excess reactive nitrogen by harnessing the activity of ubiquitous denitrifying soil microbes. DNBRs fundamentally consist of an organic carbon energy source sufficiently saturated to develop anaerobic conditions and support heterotrophic reduction of nitrate to dinitrogen. Although recent research has well established achievable nitrate removal in DNBRs upwards of 90%, few studies experimentally determine the fate of nitrogen in these systems. This study differentiates between denitrification to inert nitrogen gas, which permanently removes reactive nitrogen from an enriched ecosystem, and transformation of nitrate to another bioavailable form (such as N2O or NOX, powerful greenhouse gases). Previous research has failed to make this distinction and as both are perceived as a reduction in nitrate concentration at the outlet, the utility of DNBRs in reducing downstream reactive nitrogen has not been sufficiently established. In order to quantify the rate of nitrate removal and the products produced, dissolved gas samples are collected from the DNBR with passive diffusion gas samplers while the influent and effluent nitrate concentration and chemical oxygen demand are monitored in real time with spectrometer probes. Nitrate removal is compared with the denitrification rate and the ratio of dinitrogen to nitrous oxide is reported. Denitrification is quantified from the proportion of nitrogen gas products produced from the nitrate pool, indicated by the negative congruence of the regression of 15N enrichment in the nitrate pool and temporal depletion in the gaseous products. The proportion of nitrous oxide to dinitrogen is examined with respect to saturation and redox potential. This research informs the interpretation of previous studies as well as advises the focus of long-term system level monitoring that will provide further information on the design and application of DNBRs to

  4. Understanding the rates of nonpolar organic chemical accumulation into passive samplers deployed in the environment: Guidance for passive sampler deployments.

    PubMed

    Apell, Jennifer N; Tcaciuc, A Patricia; Gschwend, Philip M

    2016-07-01

    Polymeric passive samplers have become a common method for estimating freely dissolved concentrations in environmental media. However, this approach has not yet been adopted by investigators conducting remedial investigations of contaminated environmental sites. Successful adoption of this sampling methodology relies on an understanding of how passive samplers accumulate chemical mass as well as developing guidance for the design and deployment of passive samplers. Herein, we outline the development of a simple mathematical relationship of the environmental, polymer, and chemical properties that control the uptake rate. This relationship, called a timescale, is then used to illustrate how each property controls the rate of equilibration in samplers deployed in the water or in the sediment. Guidance is also given on how to use the timescales to select an appropriate polymer, deployment time, and suite of performance reference compounds. Integr Environ Assess Manag 2016;12:486-492. © 2015 SETAC.

  5. Variations in heavy metal accumulation, growth and yield of rice plants grown at different sewage sludge amendment rates.

    PubMed

    Singh, R P; Agrawal, M

    2010-05-01

    Use of sewage sludge in agriculture is an alternative disposal technique for this waste. The present field study was conducted to assess the suitability of sewage sludge amendment in soil for rice (Oryza sativa L. cv. Pusa sugandha 3) by evaluating the heavy metal accumulation, growth, biomass and yield responses of plants grown at 0, 3, 4.5, 6, 9, 12 kgm(-2) sewage sludge amendment (SSA) rate. Sewage sludge amendment modified the physico-chemical properties of soil, thus increasing the availability of heavy metals in soil and consequently with higher accumulation in plant parts. Root length decreased, whereas shoot length, number of leaves, leaf area and total biomass increased significantly when grown under various SSA rates. Yield of rice increased by 60%, 111%, 125%, 134% and 137% at 3, 4.5, 6, 9 and 12 kgm(-2) SSA, respectively, as compared to those grown in unamended soil. Sewage sludge amendment rates above 4.5 kgm(-2) though increased the yield of rice, but caused risk of food chain contamination as concentrations of Ni and Cd in rice grains were found to be above the Indian safe limits (1.5 mgkg(-1)) of human consumption above 4.5 kgm(-2) SSA and of Pb (2.5 mgkg(-1)) above 6 kgm(-2) SSA. Since aboveground parts of the rice also showed higher concentration than the permissible levels of Ni, Cd and Pb at 4.5 kgm(-2) SSA rate, it cannot be used as fodder. The rice husk may be used as bioresource for energy production. Efforts should be made to treat the effluents from small scale industries before discharge into the sewerage system.

  6. Improving the precipitation accumulation analysis using lightning measurements and different integration periods

    NASA Astrophysics Data System (ADS)

    Gregow, Erik; Pessi, Antti; Mäkelä, Antti; Saltikoff, Elena

    2017-01-01

    The focus of this article is to improve the precipitation accumulation analysis, with special focus on the intense precipitation events. Two main objectives are addressed: (i) the assimilation of lightning observations together with radar and gauge measurements, and (ii) the analysis of the impact of different integration periods in the radar-gauge correction method. The article is a continuation of previous work by Gregow et al. (2013) in the same research field. A new lightning data assimilation method has been implemented and validated within the Finnish Meteorological Institute - Local Analysis and Prediction System. Lightning data do improve the analysis when no radars are available, and even with radar data, lightning data have a positive impact on the results. The radar-gauge assimilation method is highly dependent on statistical relationships between radar and gauges, when performing the correction to the precipitation accumulation field. Here, we investigate the usage of different time integration intervals: 1, 6, 12, 24 h and 7 days. This will change the amount of data used and affect the statistical calculation of the radar-gauge relations. Verification shows that the real-time analysis using the 1 h integration time length gives the best results.

  7. Influences of sediment geochemistry on metal accumulation rates and toxicity in the aquatic oligochaete Tubifex tubifex.

    PubMed

    Méndez-Fernández, Leire; De Jonge, Maarten; Bervoets, Lieven

    2014-12-01

    Metal bioaccumulation and toxicity in the aquatic oligochaete Tubifex tubifex exposed to three metal-contaminated field-sediments was studied in order to assess whether sediment-geochemistry (AVS, TOC) plays a major role in influencing these parameters, and to assess if the biodynamic concept can be used to explain observed effects in T. tubifex tissue residues and/or toxicity. An active autotomy promotion was observed in three studied sediments at different time points and reproduction impairment could be inferred in T. tubifex exposed to two of the tested sites after 28 days. The present study showed that sediment metal concentration and tissue residues followed significant regression models for four essential metals (Cu, Co, Ni and Zn) and one non-essential metal (Pb). Organic content normalization for As also showed a significant relationship with As tissue residue. Porewater was also revealed to be an important source of metal uptake for essential metals (e.g. Cu, Ni and Zn) and for As, but AVS content was not relevant for metal uptake in T. tubifex in studied sediments. Under the biodynamic concept, it was shown that influx rate from food (IF, sediment ingestion) in T. tubifex, in a range of sediment geochemistry, was able to predict metal bioaccumulation, especially of the essential metals Cu, Ni and Zn, and for the non-essential metal Pb. Additionally, IF appeared to be a better predictor for metal bioaccumulation in T. tubifex compared to sediment geochemistry normalization.

  8. The Weathering of Antarctic Meteorites: Climatic Controls on Weathering Rates and Implications for Meteorite Accumulation

    NASA Technical Reports Server (NTRS)

    Benoit, P. H.; Akridge, J. M. C.; Sears, D. W. G.; Bland, P. A.

    1995-01-01

    Weathering of meteorites includes a variety of chemical and mineralogical changes, including conversion of metal to iron oxides, or rust. Other changes include the devitrification of glass, especially in fusion crust. On a longer time scale, major minerals such as olivine, pyroxene, and feldspar are partially or wholly converted to various phyllosilicates. The degree of weathering of meteorite finds is often noted using a qualitative system based on visual inspection of hand specimens. Several quantitative weathering classification systems have been proposed or are currently under development. Wlotzka has proposed a classification system based on mineralogical changes observed in polished sections and Mossbauer properties of meteorite powders have also been used. In the current paper, we discuss induced thermoluminescence (TL) as an indicator of degree of weathering of individual meteorites. The quantitative measures of weathering, including induced TL, suffer from one major flaw, namely that their results only apply to small portions of the meteorite.

  9. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  10. Resistive Wall Growth Rate Measurements in the Fermilab Recycler

    SciTech Connect

    Ainsworth, R.; Adamson, P.; Burov, A.; Kourbanis, I.

    2016-10-05

    Impedance could represent a limitation of running high intensity beams in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this,studies have been performed measuring the growth rate of presumably the resistive wall instability. The growth rates at varying intensities and chromaticities are shown. The measured growth rates are compared to ones calculated with the resistive wall impedance.

  11. Measured rates of sedimentation: What exactly are we estimating, and why?

    NASA Astrophysics Data System (ADS)

    Tipper, John C.

    2016-06-01

    Data on rates of sedimentation are essential in studies of sedimentation systems. These data are obtained in three main study contexts: (1) the study of sedimentation systems that are active today, (2) the source-to-sink study of sedimentation systems that no longer are active, and (3) the study of the relationship between accumulation rate and measurement timespan. The aim of this paper is to question the meaning of measured rates of sedimentation, and their interpretability, particularly in these three contexts. Individual measurements of rate of sedimentation must always be interpreted with care. Firstly, there are different definitions, for instance with different statistical support or measurement dimension; values that are defined differently cannot be compared directly. Secondly, appropriate sampling schemes must have been used for the measurement; this minimises sampling bias. Thirdly, the inherent limitations of the data sources must be taken into account. Rates of sedimentation can usually be measured successfully in active sedimentation systems. The same is not true for systems that are no longer active; these can only be studied using the stratigraphic successions left behind. Rates of erosion can never be measured successfully in stratigraphic successions. Rate of sedimentation is essentially a ratio - an amount of sedimentation per length of time - therefore the obvious strategy to use in determining it is first to measure the amount and the time independently, then to combine the values. The amount can be measured in terms of thickness or volume or mass per unit area. The duration of the time interval can be preset using quasi-continuous measurement techniques or site reoccupation, or it can be identified from interval-specific sedimentary structures, or it can be measured using dated horizons. An alternative strategy is to use a surrogate measurement variable. Rates of erosion in ancient systems are usually measured in this way, using cosmogenic

  12. Shallow Sediment Trace Metal Concentrations and Short-Term Accumulation Rates in the Neponset River Estuary, Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    Spencer, J. R.; Zhu, J.; Olsen, C. R.

    2010-12-01

    The Neponset River estuary is a small estuary that drains into the Boston Harbor on the east coast of the United States. It is also a highly urbanized estuary and has a long history of urban development over 450 years. In July 2006, six sediment cores were collected in the Neponset River estuary to examine particle dynamics and sediment accumulation via radionuclide (Beryllium-7) dating, and to determine sediment metal concentrations (As, Cu, Pb, and Zn) via ED-XRF measurements. Measured sediment Be-7 profiles indicate various sedimentation environments, where sediment accumulation, resuspension or redeposition is likely to occur. High metal concentrations were often corresponding to high Be-7 inventories in sediment cores. Possible sources of trace metal contaminants in the water column include: storm water run-off, Combined Sewer Overflows (CSOs), a well-documented industrial pollution event that occurred upstream in the early to mid twentieth century, and the resuspension of sediment. Existing and future data will provide baseline information for quantifying the effects of the proposed and pending environmental restoration project, which includes the removal of the Baker Dam. The combined pre- and post-Dam removal data may then be used in cost-benefit analyses for other similar estuarine restoration projects.

  13. Measurement of tracheal mucous transport rate in the horse

    SciTech Connect

    Nelson, R.; Hampe, D.W.

    1983-06-01

    Tracheal mucous transport rates were measured in 12 nonanesthetized horses after an intratracheal injection of 99mtechnetium-sulfur colloid. The transport rate of the subsequent bolus of radioactivity was determined, using a portable scaler rate meter fitted with a high-energy gamma-scintillation probe. A gamma-scintillation camera was used to verify bolus form and movement in 1 horse. The mean tracheal mucous transport rate was 1.66 +/- 0.24 cm/min.

  14. Biomass Accumulation Rates of Amazonian Secondary Forest and Biomass of Old-Growth Forests from Landsat Time Series and GLAS

    NASA Astrophysics Data System (ADS)

    Helmer, E.; Lefsky, M. A.; Roberts, D.

    2009-12-01

    We estimate the age of humid lowland tropical forests in Rondônia, Brazil, from a somewhat densely spaced time series of Landsat images (1975-2003) with an automated procedure, the Threshold Age Mapping Algorithm (TAMA), first described here. We then estimate a landscape-level rate of aboveground woody biomass accumulation of secondary forest by combining forest age mapping with biomass estimates from the Geoscience Laser Altimeter System (GLAS). Though highly variable, the estimated average biomass accumulation rate of 8.4 Mg ha-1 yr-1 agrees well with ground-based studies for young secondary forests in the region. In isolating the lowland forests, we map land cover and general types of old-growth forests with decision tree classification of Landsat imagery and elevation data. We then estimate aboveground live biomass for seven classes of old-growth forest. TAMA is simple, fast, and self-calibrating. By not using between-date band or index differences or trends, it requires neither image normalization nor atmospheric correction. In addition, it uses an approach to map forest cover for the self-calibrations that is novel to forest mapping with satellite imagery; it maps humid secondary forest that is difficult to distinguish from old-growth forest in single-date imagery; it does not assume that forest age equals time since disturbance; and it incorporates Landsat Multispectral Scanner (MSS) imagery. Variations on the work that we present here can be applied to other forested landscapes. Applications that use image time series will be helped by the free distribution of coregistered Landsat imagery, which began in December 2008, and of the Ice Cloud and land Elevation Satellite (ICESat) Vegetation Product, which simplifies the use of GLAS data. Finally, we demonstrate here for the first time how the optical imagery of fine spatial resolution that is viewable on Google Earth provides a new source of reference data for remote sensing applications related to land cover

  15. Dual Mode NOx Sensor: Measuring Both the Accumulated Amount and Instantaneous Level at Low Concentrations

    PubMed Central

    Groß, Andrea; Beulertz, Gregor; Marr, Isabella; Kubinski, David J.; Visser, Jaco H.; Moos, Ralf

    2012-01-01

    The accumulating-type (or integrating-type) NOx sensor principle offers two operation modes to measure low levels of NOx: The direct signal gives the total amount dosed over a time interval and its derivative the instantaneous concentration. With a linear sensor response, no baseline drift, and both response times and recovery times in the range of the gas exchange time of the test bench (5 to 7 s), the integrating sensor is well suited to reliably detect low levels of NOx. Experimental results are presented demonstrating the sensor’s integrating properties for the total amount detection and its sensitivity to both NO and to NO2. We also show the correlation between the derivative of the sensor signal and the known gas concentration. The long-term detection of NOx in the sub-ppm range (e.g., for air quality measurements) is discussed. Additionally, a self-adaption of the measurement range taking advantage of the temperature dependency of the sensitivity is addressed. PMID:22736980

  16. Measuring radon exhalation rate in two cycles avoiding the effects of back-diffusion and chamber leakage.

    PubMed

    Tan, Yanliang; Xiao, Detao

    2013-10-01

    This paper will present a simple method for measuring the radon exhalation rate from the medium surface in two cycles and also avoiding the effects of back-diffusion and chamber leakage. The method is based on a combination of the "accumulation chamber" technique and a radon monitor. The radon monitor performs the measurement of the radon concentration inside the accumulation chamber, and then the radon exhalation rate can be obtained by simple calculation. For reducing the systematic error and the statistical uncertainty, too short of total measurement time is not appropriate, and the first cycle time should be about 70 % of the total measurement. The radon exhalation rate from the medium surface obtained through this method is in good agreement with the reference value. This simple method can be applied to develop and improve the instruments for measuring radon exhalation rate.

  17. Predicting the visitation of carcasses by carrion-related insects under different rates of degree-day accumulation.

    PubMed

    Michaud, Jean-Philippe; Moreau, Gaétan

    2009-03-10

    Common assumptions in forensic entomology are that insects visit and colonize carcasses following a predictable sequence, and that this succession varies among seasons. However, currently available evidence for insect succession on decomposing bodies is essentially descriptive and, to our knowledge, the fine-scale predictability of insect succession with respect to seasons has never been confirmed statistically. In this study, we test these assumptions through the sampling of carrion-related insects attracted to pig carcasses. The study was carried out during the summer and fall of 2006 in rural fields of New Brunswick, Canada. Of the five species of carrion-related insects with high enough occurrence on carcasses to allow modelling, three showed predictable occurrence with respect to degree-day accumulation and seasonal effects. This demonstrates that the occurrence probability of some carrion-related insects on carcasses can be estimated from meteorological records even across seasons with different rates of degree-day accumulation. As opposed to the prevailing idea that adult insects are not reliable for post-mortem interval estimation, the adults of some species exhibited a specific pattern of visitation that could be determined and used in forensic investigations. It is stressed, however, that the statistical predictability of species occurrence must be assessed before any species is considered as a post-mortem interval indicator.

  18. Accumulation of Cd by the marine sponge Halichondria panicea pallas: Effects upon filtration rate and its relevance for biomonitoring

    SciTech Connect

    Olesen, T.M.E.; Weeks, J.M. )

    1994-05-01

    The marine demosponge Halichondria panicea Pallas, is a cosmopolitan species occurring in coastal waters with varied conditions of light, current, salinity and turbidity. H. panicea has a leuconoid structure and is composed of siliceous spicules and spongin fibers. Sponges are important members of many shallow water marine benthic communities, but comparatively little is known of their trace metal biology. Sponge architecture is constructed around a system of water canals and the physiology of the sponge is largely dependent on the currents of water flowing through their bodies. The volume of water pumped by a sponge is remarkable, ca. 100-1200 ml h[sup [minus]1] g[sup [minus]1]. This large volume of water passing through the body of a sponge means that most cells are in direct contact with the external medium. Many sponges are able to accumulate trace metals and are highly tolerant of such pollutants. This has led to the proposal that a [open quotes]sponge watch[close quotes] program be initiated supplementary to the existing [open quotes]mussel watch[close quotes] program. In view of the large volume of water passing through the bodies of sponges such as H. panicea, the suitability of this species as a biomonitoring organism was further investigated. This study describes the accumulation strategy of the demosponge H. panicea exposed to dissolved cadmium (Cd) and the effect of Cd upon sponge filtration rate.

  19. Escape rate scaling in infinite measure preserving systems

    NASA Astrophysics Data System (ADS)

    Munday, Sara; Knight, Georgie

    2016-02-01

    We investigate the scaling of the escape rate from piecewise linear dynamical systems displaying intermittency due to the presence of an indifferent fixed point. Strong intermittent behaviour in the dynamics can result in the system preserving an infinite measure. We define a neighbourhood of the indifferent fixed point to be a hole through which points escape and investigate the scaling of the rate of this escape as the length of the hole decreases, both in the finite measure preserving case and infinite measure preserving case. In the infinite measure preserving systems we observe logarithmic corrections to and polynomial scaling of the escape rate with hole length. Finally we conjecture a relationship between the wandering rate and the observed scaling of the escape rate.

  20. Gas flow meter and method for measuring gas flow rate

    DOEpatents

    Robertson, Eric P.

    2006-08-01

    A gas flow rate meter includes an upstream line and two chambers having substantially equal, fixed volumes. An adjustable valve may direct the gas flow through the upstream line to either of the two chambers. A pressure monitoring device may be configured to prompt valve adjustments, directing the gas flow to an alternate chamber each time a pre-set pressure in the upstream line is reached. A method of measuring the gas flow rate measures the time required for the pressure in the upstream line to reach the pre-set pressure. The volume of the chamber and upstream line are known and fixed, thus the time required for the increase in pressure may be used to determine the flow rate of the gas. Another method of measuring the gas flow rate uses two pressure measurements of a fixed volume, taken at different times, to determine the flow rate of the gas.

  1. 29 CFR 530.202 - Piece rates-work measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Piece rates-work measurement. 530.202 Section 530.202 Labor... Piece rates—work measurement. (a) No certificate will be issued pursuant to § 530.101 of subpart B to an... different types of items produced using stop watch time studies or other work measurement...

  2. 29 CFR 530.202 - Piece rates-work measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Piece rates-work measurement. 530.202 Section 530.202 Labor... Piece rates—work measurement. (a) No certificate will be issued pursuant to § 530.101 of subpart B to an... different types of items produced using stop watch time studies or other work measurement...

  3. Rating PV Power and Energy: Cell, Module, and System Measurements

    SciTech Connect

    Emery, Keith

    2016-06-02

    A summary of key points related to research-level measurements of current vs. voltage measurement theory including basic PV operation, equivalent circuit, and concept of spectral error; PV power performance including PV irradiance sensors, simulators and commercial and generic I-V systems; PV measurement artifacts, intercomparisons, and alternative rating methods.

  4. 29 CFR 530.202 - Piece rates-work measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Piece rates-work measurement. 530.202 Section 530.202 Labor... Piece rates—work measurement. (a) No certificate will be issued pursuant to § 530.101 of subpart B to an... different types of items produced using stop watch time studies or other work measurement...

  5. Soil weathering and accumulation rates of oxalate-extractable phases derived from alpine chronosequences of up to 1 Ma in age

    NASA Astrophysics Data System (ADS)

    Dahms, Dennis; Favilli, Filippo; Krebs, Rolf; Egli, Markus

    2012-05-01

    In this study we compare newly-developed chemical weathering data with previously published data from soils developed along two chronosequences of glacial deposits in the European Alps and the Rocky Mountains (Wind River Range, USA). By combining these chronosequences, we are able to present a comprehensive dataset that represents a time period of > 1 Ma. We describe weathering trends of important elements using a number of weathering indices (e.g., K + Ca/Ti ratio, the weathering 'index B' of Kronberg and Nesbitt (1981) and the open mass transport function). Further, we describe the accumulation of Al, Fe, Si and Mn oxyhydroxides (including partially organic phases) as a function of time, and derive the corresponding accumulation rates. We calculated pedogenetically formed oxyhydroxides using an approach based on immobile elements. Our study represents one of only a few studies that describe rates of soil chemical weathering over a period as long as ~ 1 Ma. Results show that rates of chemical weathering clearly decrease along the chronosequences with increasing age of the soils. We find weathering rates are nearly four orders of magnitude lower in the 1 Ma-old soils than in the young soils. Our results suggest that the older soils may be reaching a steady state for these chemical properties in their present environments. A power function best explains the measured time-trends of the 'index B' and (K + Ca)/Ti) ratios in the soils. The best time-trend model for pedogenic weakly- to poorly crystalline phases and the relative losses/gains (based on the open-system mass transport function) were obtained with an exponential decay model function. In terms of the soil system, the decreases in the accumulation rate of the oxyhydroxides appears to be influenced not only by the factor of time but by climate as well (increased precipitation at higher altitudes slows the decrease in weathering rate over time). Thus, our ~ 1 Ma chronosequences also become pedogenic gradients

  6. Regionally progressive accumulation of iron in Parkinson's disease as measured by quantitative susceptibility mapping.

    PubMed

    Guan, Xiaojun; Xuan, Min; Gu, Quanquan; Huang, Peiyu; Liu, Chunlei; Wang, Nian; Xu, Xiaojun; Luo, Wei; Zhang, Minming

    2017-04-01

    The progression of Parkinson's disease (PD) seems to vary according to the disease stage, which greatly influences the management of PD patients. However, the underlying mechanism of progression in PD remains unclear. This study was designed to explore the progressive pattern of iron accumulation at different stages in PD patients. Sixty right-handed PD patients and 40 normal controls were recruited. According to the disease stage, 45 patients with Hoehn-Yahr stage ≤ 2.5 and 15 patients with Hoehn-Yahr stage ≥ 3 were grouped into early-stage PD (EPD) and late-stage PD (LPD) groups, respectively. The iron content in the cardinal subcortical nuclei covering the cerebrum, cerebellum and midbrain was measured using quantitative susceptibility mapping (QSM). The substantia nigra pars compacta (SNc) showed significantly increased QSM values in the EPD patients compared with the controls. In the LPD patients, while the SNc continued to show increased QSM values compared with the controls and EPD patients, the regions showing increased QSM values spread to include the substantia nigra pars reticulata (SNr), red nucleus (RN) and globus pallidus (GP). Our data also indicated that iron deposition was more significant in the GP internal segment (GPi) than in the GP external segment. No other regions showed significant changes in QSM values among the groups. Therefore, we were able to confirm a regionally progressive pattern of iron accumulation in the different stages of PD, indicating that iron deposition in the SNc is affected exclusively in the early stages of the disease, while the SNr, RN and GP, and particularly the GPi segment, become involved in advanced stages of the disease. This is a preliminary study providing objective evidence of the iron-related progression in PD. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Drinking water boosts food intake rate, body mass increase and fat accumulation in migratory blackcaps (Sylvia atricapilla).

    PubMed

    Tsurim, Ido; Sapir, Nir; Belmaker, Jonathan; Shanni, Itai; Izhaki, Ido; Wojciechowski, Michał S; Karasov, William H; Pinshow, Berry

    2008-05-01

    Fat accumulation by blackcaps (Sylvia atricapilla) is a prerequisite for successful migratory flight in the autumn and has recently been determined to be constrained by availability of drinking water. Birds staging in a fruit-rich Pistacia atlantica plantation that had access to water increased their body mass and fat reserves both faster and to a greater extent than birds deprived of water. We conducted a series of laboratory experiments on birds captured during the autumn migration period in which we tested the hypotheses that drinking water increases food use by easing limitations on the birds' dietary choices and, consequently, feeding and food processing rates, and that the availability of drinking water leads to improved digestion and, therefore, to higher apparent metabolizable energy. Blackcaps were trapped in autumn in the Northern Negev Desert, Israel and transferred to individual cages in the laboratory. Birds were provided with P. atlantica fruit and mealworms, and had either free access to water (controls) or were water-deprived. In experiment 1, in which mealworm availability was restricted, water-deprived birds had a fourfold lower fruit and energy intake rates and, consequently, gained less fat and total mass than control birds. Water availability did not affect food metabolizability. In experiment 2, in which mealworms were provided ad libitum, water availability influenced the birds' diet: water-restricted birds ate more mealworms, while control birds consumed mainly P. atlantica fruit. Further, in experiment 2, fat and mass gain did not differ between the two treatment groups. We conclude that water availability may have important consequences for fat accumulation in migrating birds while they fatten at stopover sites, especially when water-rich food is scarce. Restricted water availability may also impede the blackcap's dietary shift from insectivory to frugivory, a shift probably necessary for successful pre-migratory fattening.

  8. Essentiality Is a Strong Determinant of Protein Rates of Evolution during Mutation Accumulation Experiments in Escherichia coli.

    PubMed

    Alvarez-Ponce, David; Sabater-Muñoz, Beatriz; Toft, Christina; Ruiz-González, Mario X; Fares, Mario A

    2016-09-26

    The Neutral Theory of Molecular Evolution is considered the most powerful theory to understand the evolutionary behavior of proteins. One of the main predictions of this theory is that essential proteins should evolve slower than dispensable ones owing to increased selective constraints. Comparison of genomes of different species, however, has revealed only small differences between the rates of evolution of essential and nonessential proteins. In some analyses, these differences vanish once confounding factors are controlled for, whereas in other cases essentiality seems to have an independent, albeit small, effect. It has been argued that comparing relatively distant genomes may entail a number of limitations. For instance, many of the genes that are dispensable in controlled lab conditions may be essential in some of the conditions faced in nature. Moreover, essentiality can change during evolution, and rates of protein evolution are simultaneously shaped by a variety of factors, whose individual effects are difficult to isolate. Here, we conducted two parallel mutation accumulation experiments in Escherichia coli, during 5,500-5,750 generations, and compared the genomes at different points of the experiments. Our approach (a short-term experiment, under highly controlled conditions) enabled us to overcome many of the limitations of previous studies. We observed that essential proteins evolved substantially slower than nonessential ones during our experiments. Strikingly, rates of protein evolution were only moderately affected by expression level and protein length.

  9. Long-term phenological trends, species accumulation rates, aphid traits and climate: five decades of change in migrating aphids.

    PubMed

    Bell, James R; Alderson, Lynda; Izera, Daniela; Kruger, Tracey; Parker, Sue; Pickup, Jon; Shortall, Chris R; Taylor, Mark S; Verrier, Paul; Harrington, Richard

    2015-01-01

    Aphids represent a significant challenge to food production. The Rothamsted Insect Survey (RIS) runs a network of 12·2-m suction-traps throughout the year to collect migrating aphids. In 2014, the RIS celebrated its 50th anniversary. This paper marks that achievement with an extensive spatiotemporal analysis and the provision of the first British annotated checklist of aphids since 1964. Our main aim was to elucidate mechanisms that advance aphid phenology under climate change and explain these using life-history traits. We then highlight emerging pests using accumulation patterns. Linear and nonlinear mixed-effect models estimated the average rate of change per annum and effects of climate on annual counts, first and last flights and length of flight season since 1965. Two climate drivers were used: the accumulated day degrees above 16 °C (ADD16) indicated the potential for migration during the aphid season; the North Atlantic Oscillation (NAO) signalled the severity of the winter before migration took place. All 55 species studied had earlier first flight trends at rate of β = -0·611 ± SE 0·015 days year(-1). Of these species, 49% had earlier last flights, but the average species effect appeared relatively stationary (β = -0·010 ± SE 0·022 days year(-1)). Most species (85%) showed increasing duration of their flight season (β = 0·336 ± SE 0·026 days year(-1)), even though only 54% increased their log annual count (β = 0·002 ± SE <0·001 year(-1)). The ADD16 and NAO were shown to drive patterns in aphid phenology in a spatiotemporal context. Early in the year when the first aphids were migrating, the effect of the winter NAO was highly significant. Further into the year, ADD16 was a strong predictor. Latitude had a near linear effect on first flights, whereas longitude produced a generally less-clear effect on all responses. Aphids that are anholocyclic (permanently parthenogenetic) or are monoecious (non

  10. Field Measurements of Isoprene and Monoterpene Emission Rates from Trees.

    NASA Astrophysics Data System (ADS)

    Dilts, Stephen Blair

    Monoterpene emission rates were measured by a branch enclosure technique from Pinus ponderosa in central Oregon in the early summer and fall along with photosynthesis and monoterpene needle concentrations. beta -pinene, Delta^3-carene, and alpha-pinene were the major constituents of the emissions with smaller amounts of myrcene, limonene, and beta-phellandrene. The emission rates of alpha-pinene and beta-pinene were highly correlated with their needle concentrations, while those of Delta ^3-carene were not. There was no discernible effect on emissions when photosynthesis was water stress limited in the fall, and monoterpene emissions appear to be distinct from short term photosynthetic carbon assimilation. Isoprene emission rates were measured from a Quercus robur on the Washington State University campus in the fall of 1989 and throughout the 1990 growing season, and from a Quercus rubra during most of the 1991 season and occasionally in 1992. The measured emission rates showed distinct seasonal patterns which could not be explained by temperature or light. Emission rates were initially low early in the season when the leaves were immature. Rates increased rapidly after leaf maturity to a maximum value and then declined over the rest of the season. Evidence suggests that the rate and magnitude of this decline depends on stresses on the tree. Isoprene emission rates were measured from several species near Oak Ridge, Tennessee. The mean normalized isoprene emission rate from the branch enclosure was compared to the rate measured from a Q. alba leaf in a light and temperature controlled cuvette. The branch enclosure result for Q. alba was about 65% lower than the mean leaf cuvette measurement. This difference appears be due to shading of leaves within the branch enclosure. A comparison was also made between the normalized branch enclosure results and normalized canopy isoprene flux measured by a micrometeorological gradient method with generally good agreement.

  11. Effects of greenhouse warming and N-fertilization on carbon accumulation rates in a nutrient-poor boreal mire: decadal effects assessed using 210Pb

    NASA Astrophysics Data System (ADS)

    Olid, Carolina; Nilsson, Mats B.; Eriksson, Tobias; Klaminder, Jonatan

    2013-04-01

    Boreal peatlands represent a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. How C accumulation in these peatlands responds to changing temperature and nutrient conditions is under debate. In this study, we assessed how peat and C accumulation rates have responded to increased annual nitrogen additions (30 kg ha-1 yr-1) and increased air temperatures (+3.6°C) in the longest ongoing boreal mire manipulation experiment. Accumulation rates for the uppermost 40 cm of peat in nitrogen and temperature treated plots (n=11) were assessed by 210Pb dating covering the last ~100yrs. A reference surface, installed in 1995 was used as independent validation of the dating model. An empirically based model of organic matter accumulation/degradation was applied to evaluate changes in both peat inputs and organic matter decay rates in response to the treatments. A significant increase in C-accumulation (15 g C m-2 yr-1) was observed in peat subjected to nitrogen additions, while greenhouse warming did not seem to significantly affect C-accumulation or decay rates. Based on our findings we argue that C-accumulation in nutrient poor boreal mires is mainly altered in near-surface peat layers (~15 cm) in response to nitrogen additions and that the uppermost peat layers (<40 cm) in nutrient poor boreal peatlands will continue to function as net C-sinks during the first decades of global warming.

  12. In situ growth rate measurement of selective LPCVD of tungsten

    SciTech Connect

    Holleman, J.; Hasper, A.; Middelhoek, J. )

    1991-04-01

    This paper reports on the reflectance measurement during the selective deposition of W on Si covered with an insulator rating proven to be a convenient method to monitor the W deposition. The reflectance change during deposition allows the in situ measurement of the deposition rate. The influence of surface roughening due to either the W growth or an etching pretreatment of the wafer is modeled, as well as the effect of selectivity loss and lateral overgrowth.

  13. Confidence bands for measured economically optimal nitrogen rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While numerous researchers have computed economically optimal N rate (EONR) values from measured yield – N rate data, nearly all have neglected to compute or estimate the statistical reliability of these EONR values. In this study, a simple method for computing EONR and its confidence bands is descr...

  14. Glacio-chemical study spanning the past 2 kyr on three ice cores from Dronning Maud Land, Antarctica 1. Annually resolved accumulation rates

    NASA Astrophysics Data System (ADS)

    Sommer, S.; Appenzeller, C.; Röthlisberger, R.; Hutterli, M. A.; Stauffer, B.; Wagenbach, D.; Oerter, H.; Wilhelms, F.; Miller, H.; Mulvaney, R.

    2000-12-01

    For the first time, annually resolved accumulation rates have been determined in central Antarctica by means of counting seasonal signals of ammonium, calcium, and sodium. All records, obtained from three intermediate depth ice cores from Dronning Maud Land, East Antarctica, show rather constant accumulation rates throughout the last 9 centuries with mean values of 63, 61, and 44 mm H2Oyr-1 and a typical year-to-year variation of about 30%. For the last few decades, no trend was detected accounting for the high natural variability of all records. A significant weak intersite correlation is apparent only between two cores when the high-frequency part with periods less than 30 years is removed. By analyzing the records in the frequency domain, no persistent periods were found. This suggests that the snow accumulation in this area is mainly influenced by local deposition patterns and may be additionally masked by redistribution of snow due to wind. By comparing accumulation rates over the last 2 millennia a distinct change in the layer thickness in one of the three cores was found, which might be attributed either to an area upstream of the drilling site with lower accumulation rates, or to deposition processes influenced by surface undulations. The missing of a clear correlation between the accumulation rate histories at the three locations is also important for the interpretation of small, short time variations of past precipitation records obtained from deep ice cores.

  15. 40 CFR 86.1726-99 - Mileage and service accumulation; emission measurements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... manufacturer may elect to conduct the respective emission tests at the higher weight. All mileage accumulation... lowest state-of-charge at the beginning of the test cycle. At no time throughout mileage accumulation... emission tests will include both the FTP and the SFTP tests. The Administrator will accept the...

  16. 40 CFR 86.1726-99 - Mileage and service accumulation; emission measurements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... manufacturer may elect to conduct the respective emission tests at the higher weight. All mileage accumulation... lowest state-of-charge at the beginning of the test cycle. At no time throughout mileage accumulation... emission tests will include both the FTP and the SFTP tests. The Administrator will accept the...

  17. 40 CFR 86.1726-99 - Mileage and service accumulation; emission measurements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... manufacturer may elect to conduct the respective emission tests at the higher weight. All mileage accumulation... lowest state-of-charge at the beginning of the test cycle. At no time throughout mileage accumulation... emission tests will include both the FTP and the SFTP tests. The Administrator will accept the...

  18. 40 CFR 86.1726-99 - Mileage and service accumulation; emission measurements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... lowest state-of-charge at the beginning of the test cycle. At no time throughout mileage accumulation... to this subpart: (1) For Otto-cycle and diesel vehicles and battery assisted combustion engine vehicles that use Otto-cycle or diesel engines: (i) Prior to initiation of mileage accumulation in...

  19. Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA

    USGS Publications Warehouse

    May, Christine L.; Gresswell, Robert E.

    2003-01-01

    Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low-order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand-replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low-order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain.

  20. Rating scales measuring the severity of psychotic depression

    PubMed Central

    Østergaard, Søren D.; Rothschild, Anthony J.; Flint, Alastair J.; Mulsant, Benoit H.; Whyte, Ellen M.; Leadholm, Anne Katrine; Bech, Per; Meyers, Barnett S.

    2015-01-01

    Objective Unipolar psychotic depression (PD) is a severe and debilitating syndrome, which requires intensive monitoring. The objective of this study was to provide an overview of the rating scales used to assess illness severity in PD. Method Selective review of publications reporting results on non-self-rated, symptom-based rating scales utilized to measure symptom severity in PD. The clinical and psychometric validity of the identified rating scales was reviewed. Results A total of 14 rating scales meeting the predefined criteria were included in the review. These scales grouped into the following categories: I. Rating scales predominantly covering depressive symptoms, II. Rating scales predominantly covering psychotic symptoms, III. Rating scales covering delusions, and IV. Rating scales covering psychotic depression. For the vast majority of the scales, the clinical and psychometric validity had not been tested empirically. The only exception from this general tendency was the 11-item Psychotic Depression Assessment Scale (PDAS), which was developed specifically to assess the severity of PD. Conclusion In PD, the Psychotic Depression Assessment Scale (PDAS) represents the only empirically derived rating scale for the measurement of overall severity of illness. The PDAS should be considered in future studies of PD and in clinical practice. PMID:26016647

  1. Versatile radar measurement of the electron loss rate in air

    NASA Astrophysics Data System (ADS)

    Dogariu, Arthur; Shneider, Mikhail N.; Miles, Richard B.

    2013-11-01

    We present an experimental method that makes possible in-situ measurements of the electron loss rate in arbitrary gas mixtures. A weakly ionized plasma is induced via resonant multiphoton ionization of trace amounts of nitric oxide seeded into the gas, and homodyne microwave scattering detection is used to study the dynamics of the electron loss mechanisms. Using this approach, the attachment rate for electrons to molecular oxygen in room temperature, atmospheric pressure air is determined. The measured 0.76 × 108 s-1 attachment rate is in very good agreement with predictions based on literature data.

  2. Versatile radar measurement of the electron loss rate in air

    SciTech Connect

    Dogariu, Arthur; Shneider, Mikhail N.; Miles, Richard B.

    2013-11-25

    We present an experimental method that makes possible in-situ measurements of the electron loss rate in arbitrary gas mixtures. A weakly ionized plasma is induced via resonant multiphoton ionization of trace amounts of nitric oxide seeded into the gas, and homodyne microwave scattering detection is used to study the dynamics of the electron loss mechanisms. Using this approach, the attachment rate for electrons to molecular oxygen in room temperature, atmospheric pressure air is determined. The measured 0.76 × 10{sup 8} s{sup −1} attachment rate is in very good agreement with predictions based on literature data.

  3. Aluminum X-ray mass-ablation rate measurements

    DOE PAGES

    Kline, John L.; Hager, Jonathan D.

    2016-10-15

    Measurements of the mass ablation rate of aluminum (Al) have been completed at the Omega Laser Facility. Measurements of the mass-ablation rate show Al is higher than plastic (CH), comparable to high density carbon (HDC), and lower than beryllium. The mass-ablation rate is consistent with predictions using a 1D Lagrangian code, Helios. Lastly, the results suggest Al capsules have a reasonable ablation pressure even with a higher albedo than beryllium or carbon ablators warranting further investigation into the viability of Al capsules for ignition should be pursued.

  4. Estimating Rain Rates from Tipping-Bucket Rain Gauge Measurements

    NASA Technical Reports Server (NTRS)

    Wang, Jianxin; Fisher, Brad L.; Wolff, David B.

    2007-01-01

    This paper describes the cubic spline based operational system for the generation of the TRMM one-minute rain rate product 2A-56 from Tipping Bucket (TB) gauge measurements. Methodological issues associated with applying the cubic spline to the TB gauge rain rate estimation are closely examined. A simulated TB gauge from a Joss-Waldvogel (JW) disdrometer is employed to evaluate effects of time scales and rain event definitions on errors of the rain rate estimation. The comparison between rain rates measured from the JW disdrometer and those estimated from the simulated TB gauge shows good overall agreement; however, the TB gauge suffers sampling problems, resulting in errors in the rain rate estimation. These errors are very sensitive to the time scale of rain rates. One-minute rain rates suffer substantial errors, especially at low rain rates. When one minute rain rates are averaged to 4-7 minute or longer time scales, the errors dramatically reduce. The rain event duration is very sensitive to the event definition but the event rain total is rather insensitive, provided that the events with less than 1 millimeter rain totals are excluded. Estimated lower rain rates are sensitive to the event definition whereas the higher rates are not. The median relative absolute errors are about 22% and 32% for 1-minute TB rain rates higher and lower than 3 mm per hour, respectively. These errors decrease to 5% and 14% when TB rain rates are used at 7-minute scale. The radar reflectivity-rainrate (Ze-R) distributions drawn from large amount of 7-minute TB rain rates and radar reflectivity data are mostly insensitive to the event definition.

  5. Interseismic strain accumulation in south central Chile from GPS measurements, 1996-1999

    NASA Astrophysics Data System (ADS)

    Ruegg, J. C.; Campos, J.; Madariaga, R.; Kausel, E.; de Chabalier, J. B.; Armijo, R.; Dimitrov, D.; Georgiev, I.; Barrientos, S.

    2002-06-01

    Two campaigns of Global Positioning System (GPS) measurements were carried out in the Concepción-Constitución area of Chile in 1996 and 1999. It is very likely that this area is a mature seismic gap, since no subduction earthquake has occurred there since 1835. In 1996, 32 sites were occupied in the range 35°S-37°S, between the Pacific coast of Chile and the Andes near the Chile-Argentina border. In 1999, the network was extended by the installation of 9 new points in the Arauco region whereas 13 points among the 1996 stations were reoccupied. The analysis of this campaign data set, together with the data recorded at eight continuous GPS sites (mostly IGS stations) in South America and surrounding regions, indicates a velocity of about 40 +/- 10 mm/yr in the direction N80-90°S for the coastal sites with respect to stable cratonic South America. This velocity decreases to about 20-25 mm/yr towards the Andes. We interpret this result as reflecting interseismic strain accumulation above the Nazca-South America subduction zone, due to a locked thrust zone extending down to about 60 km depth.

  6. Calibration of Observational Measurement of Rate of Responding

    ERIC Educational Resources Information Center

    Mudford, Oliver C.; Zeleny, Jason R.; Fisher, Wayne W.; Klum, Molly E.; Owen, Todd M.

    2011-01-01

    The quality of measurement systems used in almost all natural sciences other than behavior analysis is usually evaluated through calibration study rather than relying on interobserver agreement. We demonstrated some of the basic features of calibration using observer-measured rates of free-operant responding from 10 scripted 10-min calibration…

  7. Pictorial versus Verbal Rating Scales in Music Preference Measurement.

    ERIC Educational Resources Information Center

    LeBlanc, Albert; Jin, Young Chang; Simpson, Charles S.; Stamou, Lelouda; McCrary, Jan

    1998-01-01

    Compares pictorial and verbal rating scales as measures of music preference opinions. Examines internal consistency and test-retest reliability of each type of scale, the overall preference scores generated through the use of each to measure preference for the same music stimuli, and student preferences for each type after using them. (DSK)

  8. Ignition Rate Measurement of Laser-Ignited Coals

    SciTech Connect

    Chen, J.C.; Kabadi, V.

    1997-05-01

    We are proposing to establish a novel experiment to study the ignition of pulverized coals under conditions relevant to utility boiler. Specifically, our aims are to determine the ignition mechanism, which is either homogeneous or heterogeneous, of pulverized coal particles under various condition of particle size, coal type, freestream oxygen concentration, and heating rate. Furthermore, we will measure the ignition rate constants of various coals by direct measurement of the particle temperature at ignition, and incorporating this measurement into a mathematical model for the ignition process.

  9. Measuring Outdoor Air Intake Rates into Existing Building

    SciTech Connect

    Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

    2009-04-16

    Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10 percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15 percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100 percent, and were often greater than 25 percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

  10. Direct measurement of fluence rate in the human brain

    NASA Astrophysics Data System (ADS)

    Melnik, Ivan S.; Rusina, Tatyana V.; Denisov, Nikolay A.; Dets, Sergiy M.; Steiner, Rudolf W.; Rozumenko, Vladimir D.

    1996-01-01

    Fluence rate was measured in normal and cancerous (glioma) human brain samples using a multichannel detector. Detector consisted of 8 isotrope fiber probes positioned around the central irradiating probe. Detecting probes were displaced one from other at a step 0.5 mm along the central irradiating fiber. Bare ends of detecting fibers were coupled with photodiode array. He-Ne (633 nm) or Nd:YAG (1064 nm) lasers were coupled with irradiating probe. Fluence rate was measured in each of 8 points in the depth range 5 mm. Measured mean penetration depths of 633 nm light were 0.70 mm, 0.50 mm and 0.40 mm for white matter, grey matter and glioma, respectively. For Nd:YAG laser, penetration depth was about 2.3 mm for normal tissue and glioma. Multichannel computerized detector allows to provide a small invasive real-time measurements of fluence rate in different tissues.

  11. Modern rates of glacial sediment accumulation along a 15° S-N transect in fjords from the Antarctic Peninsula to southern Chile

    NASA Astrophysics Data System (ADS)

    Boldt, Katherine V.; Nittrouer, Charles A.; Hallet, Bernard; Koppes, Michele N.; Forrest, Brittany K.; Wellner, Julia S.; Anderson, John B.

    2013-12-01

    of glacial erosion in temperate climates rank among the highest worldwide, and the sedimentary products of such erosion record climatic and tectonic signals in many glaciated settings, as well as temporal changes in glacier behavior. Glacial sediment yields are expected to decrease with increasing latitude because decreased temperature and meltwater production reduce glacial sliding, erosion, and sediment transfer; however, this expectation lacks a solid supportive database. Herein we present modern 210Pb-derived sediment accumulation rates on decadal to century time scales for 12 fjords spanning 15° of latitude from the Antarctic Peninsula to southern Chile and interpret the results in light of glacimarine sediment accumulation worldwide. 210Pb records from the Antarctic Peninsula show surprisingly steady sediment accumulation throughout the past century at rates of 1-7 mm yr-1, despite rapid warming and glacial retreat. Cores from the South Shetland Islands reveal accelerated sediment accumulation over the past few decades, likely due to changes in the thermal state of the glaciers in this region, which straddles the boundary between subpolar and temperate conditions. In Patagonia and Tierra del Fuego, sediment accumulates faster (11-24 mm yr-1), and previously collected seismic profiles show that rates reach meters per year close to the glacier termini. This increase in sediment accumulation rates with decreasing latitude reflects the gradient from subpolar to temperate climates and is consistent with glacial erosion being much faster in the temperate climate of southern Chile than in the polar climate of the Antarctic Peninsula.

  12. Measuring task-related changes in heart rate variability.

    PubMed

    Moses, Ziev B; Luecken, Linda J; Eason, James C

    2007-01-01

    Small beat-to-beat differences in heart rate are the result of dynamic control of the cardiovascular system by the sympathetic and parasympathetic nervous systems. Heart rate variability (HRV) has been positively correlated with both mental and physical health. While many studies measure HRV under rest conditions, few have measured HRV during stressful situations. We describe an experimental protocol designed to measure baseline, task, and recovery values of HRV as a function of three different types of stressors. These stressors involve an attention task, a cold pressor test, and a videotaped speech presentation. We found a measurable change in heart rate in participants (n=10) during each task (all p's < 0.05). The relative increase or decrease from pre-task heart rate was predicted by task (one-way ANOVA, p= 0.0001). Spectral analysis of HRV during the attention task revealed consistently decreased measures of both high (68+/-7%, mean+/-S.E.) and low (62+/-13%) frequency HRV components as compared to baseline. HRV spectra for the cold pressor and speech tasks revealed no consistent patterns of increase or decrease from baseline measurements. We also found no correlation in reactivity measures between any of our tasks. These findings suggest that each of the tasks in our experimental design elicits a different type of stress response in an individual. Our experimental approach may prove useful to biobehavioral researchers searching for factors that determine individual differences in responses to stress in daily life.

  13. Lava effusion rate definition and measurement--A review

    USGS Publications Warehouse

    Calvari, Sonia; Dehn, Jonathan; Harris, A.

    2007-01-01

    Measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics, as well as for monitoring efforts during on-going eruptions. However, its exact definition remains a source of confusion, and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales, or measured using different approaches. Thus our aims are to: (1) define effusion rate terminology; and (2) assess the various measurement methods and their results. We first distinguish between instantaneous effusion rate, and time-averaged discharge rate. Eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began. The ultimate extension of this is mean output rate, this being the final volume of erupted lava divided by total eruption duration. Whether these values are total values, i.e. the flux feeding all flow units across the entire flow field, or local, i.e. the flux feeding a single active unit within a flow field across which many units are active, also needs to be specified. No approach is without its problems, and all can have large error (up to ∼50%). However, good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here. There are three important factors to consider and state when measuring, giving or using an effusion rate. First, the time-period over which the value was averaged; second, whether the measurement applies to the entire active flow field, or a single lava flow within that field; and third, the measurement technique and its accompanying assumptions.

  14. Classifying work rate from heart rate measurements using an adaptive neuro-fuzzy inference system.

    PubMed

    Kolus, Ahmet; Imbeau, Daniel; Dubé, Philippe-Antoine; Dubeau, Denise

    2016-05-01

    In a new approach based on adaptive neuro-fuzzy inference systems (ANFIS), field heart rate (HR) measurements were used to classify work rate into four categories: very light, light, moderate, and heavy. Inter-participant variability (physiological and physical differences) was considered. Twenty-eight participants performed Meyer and Flenghi's step-test and a maximal treadmill test, during which heart rate and oxygen consumption (VO2) were measured. Results indicated that heart rate monitoring (HR, HRmax, and HRrest) and body weight are significant variables for classifying work rate. The ANFIS classifier showed superior sensitivity, specificity, and accuracy compared to current practice using established work rate categories based on percent heart rate reserve (%HRR). The ANFIS classifier showed an overall 29.6% difference in classification accuracy and a good balance between sensitivity (90.7%) and specificity (95.2%) on average. With its ease of implementation and variable measurement, the ANFIS classifier shows potential for widespread use by practitioners for work rate assessment.

  15. Parametric study of injection rates with solenoid injectors in an injection quantity and rate measuring device

    DOE PAGES

    Busch, Stephen; Miles, Paul C.

    2015-03-31

    A Moehwald HDA (HDA is a German acronym: Hydraulischer Druckanstieg: hydraulic pressure increase) injection quantity and rate measuring unit is used to investigate injection rates obtained with a fast-acting, preproduction diesel solenoid injector. Experimental parametric variations are performed to determine their impact on measured injection rate traces. A pilot–main injection strategy is investigated for various dwell times; these preproduction injectors can operate with very short dwell times with distinct pilot and main injection events. Dwell influences the main injection rate shape. Furthermore, a comparison between a diesel-like fuel and a gasoline-like fuel shows that injection rates are comparable for amore » single injection but dramatically different for multiple injections with short dwells.« less

  16. Parametric study of injection rates with solenoid injectors in an injection quantity and rate measuring device

    SciTech Connect

    Busch, Stephen; Miles, Paul C.

    2015-03-31

    A Moehwald HDA (HDA is a German acronym: Hydraulischer Druckanstieg: hydraulic pressure increase) injection quantity and rate measuring unit is used to investigate injection rates obtained with a fast-acting, preproduction diesel solenoid injector. Experimental parametric variations are performed to determine their impact on measured injection rate traces. A pilot–main injection strategy is investigated for various dwell times; these preproduction injectors can operate with very short dwell times with distinct pilot and main injection events. Dwell influences the main injection rate shape. Furthermore, a comparison between a diesel-like fuel and a gasoline-like fuel shows that injection rates are comparable for a single injection but dramatically different for multiple injections with short dwells.

  17. A dual-inlet, single detector relaxed eddy accumulation system for long-term measurement of mercury flux

    NASA Astrophysics Data System (ADS)

    Osterwalder, S.; Fritsche, J.; Alewell, C.; Schmutz, M.; Nilsson, M. B.; Jocher, G.; Sommar, J.; Rinne, J.; Bishop, K.

    2016-02-01

    The fate of anthropogenic emissions of mercury (Hg) to the atmosphere is influenced by the exchange of elemental Hg with the earth surface. This exchange holds the key to a better understanding of Hg cycling from local to global scales, which has been difficult to quantify. To advance research about land-atmosphere Hg interactions, we developed a dual-inlet, single detector relaxed eddy accumulation (REA) system. REA is an established technique for measuring turbulent fluxes of trace gases and aerosol particles in the atmospheric surface layer. Accurate determination of gaseous elemental mercury (GEM) fluxes has proven difficult due to technical challenges presented by extremely small concentration differences (typically < 0.5 ng m-3) between updrafts and downdrafts. We present an advanced REA design that uses two inlets and two pairs of gold cartridges for continuous monitoring of GEM fluxes. This setup reduces the major uncertainty created by the sequential sampling in many previous designs. Additionally, the instrument is equipped with a GEM reference gas generator that monitors drift and recovery rates. These innovations facilitate continuous, autonomous measurement of GEM flux. To demonstrate the system performance, we present results from field campaigns in two contrasting environments: an urban setting with a heterogeneous fetch and a boreal peatland during snowmelt. The observed average emission rates were 15 and 3 ng m-2 h-1, respectively. We believe that this dual-inlet, single detector approach is a significant improvement of the REA system for ultra-trace gases and can help to advance our understanding of long-term land-atmosphere GEM exchange.

  18. High Pressure Burn Rate Measurements on an Ammonium Perchlorate Propellant

    SciTech Connect

    Glascoe, E A; Tan, N

    2010-04-21

    High pressure deflagration rate measurements of a unique ammonium perchlorate (AP) based propellant are required to design the base burn motor for a Raytheon weapon system. The results of these deflagration rate measurements will be key in assessing safety and performance of the system. In particular, the system may experience transient pressures on the order of 100's of MPa (10's kPSI). Previous studies on similar AP based materials demonstrate that low pressure (e.g. P < 10 MPa or 1500 PSI) burn rates can be quite different than the elevated pressure deflagration rate measurements (see References and HPP results discussed herein), hence elevated pressure measurements are necessary in order understand the deflagration behavior under relevant conditions. Previous work on explosives have shown that at 100's of MPa some explosives will transition from a laminar burn mechanism to a convective burn mechanism in a process termed deconsolidative burning. The resulting burn rates that are orders-of-magnitude faster than the laminar burn rates. Materials that transition to the deconsolidative-convective burn mechanism at elevated pressures have been shown to be considerably more violent in confined heating experiments (i.e. cook-off scenarios). The mechanisms of propellant and explosive deflagration are extremely complex and include both chemical, and mechanical processes, hence predicting the behavior and rate of a novel material or formulation is difficult if not impossible. In this work, the AP/HTPB based material, TAL-1503 (B-2049), was burned in a constant volume apparatus in argon up to 300 MPa (ca. 44 kPSI). The burn rate and pressure were measured in-situ and used to calculate a pressure dependent burn rate. In general, the material appears to burn in a laminar fashion at these elevated pressures. The experiment was reproduced multiple times and the burn rate law using the best data is B = (0.6 {+-} 0.1) x P{sup (1.05{+-}0.02)} where B is the burn rate in mm/s and

  19. Removal Rates of Aqueous Cr(VI) by Zero-Valent Iron Measured Under Flow Conditions

    SciTech Connect

    Kaplan, D.I.

    2002-05-10

    Studies were undertaken to measure the rate of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). The pseudo-first-order rate coefficients measured under flow conditions were comparable to those previously measured under batch conditions that had significantly greater ratios of solution volume to Fe(0) surface area. Between the range of 20 and 100 weight percent Fe(0), there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry had only marginal effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  20. Heart rate measurement as a tool to quantify sedentary behavior.

    PubMed

    Åkerberg, Anna; Koshmak, Gregory; Johansson, Anders; Lindén, Maria

    2015-01-01

    Sedentary work is very common today. The aim of this pilot study was to attempt to differentiate between typical work situations and to investigate the possibility to break sedentary behavior, based on physiological measurement among office workers. Ten test persons used one heart rate based activity monitor (Linkura), one pulse oximeter device (Wrist) and one movement based activity wristband (Fitbit Flex), in different working situations. The results showed that both heart rate devices, Linkura and Wrist, were able to detect differences in heart rate between the different working situations (resting, sitting, standing, slow walk and medium fast walk). The movement based device, Fitbit Flex, was only able to separate differences in steps between slow walk and medium fast walk. It can be concluded that heart rate measurement is a promising tool for quantifying and separating different working situations, such as sitting, standing and walking.

  1. Snow Accumulation and Spring Melt Rates of Bogs and Fens in the North Granny Creek Catchment Basin, Hudson Bay Lowlands, Ontario

    NASA Astrophysics Data System (ADS)

    Cook, C. F.; Price, J. S.

    2009-05-01

    differing hydrological properties of peatland types. Fens are expected to experience melt quicker than bogs and will receive and convey most of the runoff waters. Snow survey data from the springs of 2008 and 2009 coupled with stream discharge measurements will be used to determine the characteristics of different peatland types that control snow accumulation, melt rates and runoff production and their respective contributions. Since it is expected that the surface hydrology of this area will change over time because of groundwater depressurization it is important to develop a base line characterization of runoff generation and flowpaths within and between peatland types. An examination of snow accumulation and melt characteristics is necessary in northern peatland complexes to fully understand the response of these environments to changes in hydrology.

  2. Interseismic strain accumulation in seismic gap of south central Chile from GPS measurements

    NASA Astrophysics Data System (ADS)

    Rudloff, A.; Vigny, C.; Ruegg, J. C.; Campos, J.

    2003-04-01

    Three campaigns of Global Positioning System (GPS) measurements were carried out in the Concepcion-Constitucion seismic gap in South Central Chile in 1996, 1999, and 2002. We observed a network of about 40 sites, made of 2 east-west transects roughly perpendicular to the trench ranging from the coastal area to the Argentina border and 1 north-south profile along the coast. Data sets were processed with MIT's GAMIT/GLOBK package. Horizontal velocities have formal uncertainties around 1 to 2 mm/yr in average. Vertical velocities are also determined and have uncertainties around 2 to 5 mm/yr. We find that the convergence between Nazca and South-America plates better matches the pole previously estimated by (Larson et al, 1997) than the Nuvel-1A estimate. Our estimate predicts a convergence of 72 mm/yr at N70 to be compared with Nuvel-1A 80 mm/yr at N79. With respect to stable South America, horizontal velocities decrease from 35 mm/yr on the coast to 14 mm/yr in the Cordillera. Vertical velocities help constraint lithospheric flecture. Partionning of the slightly oblique convergence will be investigated. The gradient of convergent parallel velocities reflects aseismic elastic loading on a zone of about 400 km width. Interestingly enough, this gradient exhibit a linear pattern, marginally compatible with the expected arctangent shape. 70 mm/yr of motion accumulated since the last big event in this area (1835 Earthquake described by Darwin) represent more than 10 m of displacement. Therefore, this area is probably mature for a next large earthquake, the magnitude of which could reach 8.5.

  3. Measuring the Evolutionary Rate of Cooling of ZZ Ceti

    NASA Astrophysics Data System (ADS)

    Mukadam, Anjum S.; Bischoff-Kim, Agnes; Fraser, Oliver; Córsico, A. H.; Montgomery, M. H.; Kepler, S. O.; Romero, A. D.; Winget, D. E.; Hermes, J. J.; Riecken, T. S.; Kronberg, M. E.; Winget, K. I.; Falcon, Ross E.; Chandler, D. W.; Kuehne, J. W.; Sullivan, D. J.; Reaves, D.; von Hippel, T.; Mullally, F.; Shipman, H.; Thompson, S. E.; Silvestri, N. M.; Hynes, R. I.

    2013-07-01

    We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series photometry from 1970 November to 2012 January, we determine the rate of change of this period with time to be dP/dt = (5.2 ± 1.4) × 10-15 s s-1 employing the O - C method and (5.45 ± 0.79) × 10-15 s s-1 using a direct nonlinear least squares fit to the entire lightcurve. We adopt the dP/dt obtained from the nonlinear least squares program as our final determination, but augment the corresponding uncertainty to a more realistic value, ultimately arriving at the measurement of dP/dt = (5.5 ± 1.0) × 10-15 s s-1. After correcting for proper motion, the evolutionary rate of cooling of ZZ Ceti is computed to be (3.3 ± 1.1) × 10-15 s s-1. This value is consistent within uncertainties with the measurement of (4.19 ± 0.73) × 10-15 s s-1 for another similar pulsating DA white dwarf, G 117-B15A. Measuring the cooling rate of ZZ Ceti helps us refine our stellar structure and evolutionary models, as cooling depends mainly on the core composition and stellar mass. Calibrating white dwarf cooling curves with this measurement will reduce the theoretical uncertainties involved in white dwarf cosmochronometry. Should the 213.13 s period be trapped in the hydrogen envelope, then our determination of its drift rate compared to the expected evolutionary rate suggests an additional source of stellar cooling. Attributing the excess cooling to the emission of axions imposes a constraint on the mass of the hypothetical axion particle.

  4. Modern sediment characteristics and accumulation rates from the delta front to prodelta of the Yellow River (Huanghe)

    NASA Astrophysics Data System (ADS)

    Zhou, Liangyong; Liu, Jian; Saito, Yoshiki; Gao, Maosheng; Diao, Shaobo; Qiu, Jiandong; Pei, Shaofeng

    2016-08-01

    Since 1976, the main channel of the Yellow River (Huanghe) has been on the east side of the delta complex, and the river has prograded a broad new delta lobe in Laizhou Bay of the Bohai Sea. In 2012, extensive bathymetric and high-resolution seismic profiles were conducted and sediment cores were collected off the new delta lobe. This study examined delta sedimentation and morphology along a profile across the modern subaqueous Yellow River delta and into Laizhou Bay, by analyzing sediment radionuclides (137Cs, 210Pb and 7Be), sedimentary structure, grain-size composition, organic carbon content, and morphological changes between 1976 and 2012. The change in the bathymetric profile, longitudinal to the river's course, reveals subaqueous delta progradation during this period. The subbottom boundary between the new delta lobe sediment and the older seafloor sediment (before the 1976 course shift) was identified in terms of lithology and radionuclide distributions, and recognized as a downlap surface in the seismic record. The accumulation rate of the new delta lobe sediment is estimated to be 5-18.6 cm year-1 on the delta front slope, 2 cm year-1 at the toe of the slope, and 1-2 cm year-1 in the shelf areas of Laizhou Bay. Sediment facies also change offshore, from alternations of gray and brown sediment in the proximal area to gray bioturbated fine sediment in the distal area. Based on 7Be distribution, the shorter-term deposition rate was at least 20 cm year-1 in the delta front.

  5. Export production fluctuations in the eastern equatorial Pacific during the Pliocene-Pleistocene: Reconstruction using barite accumulation rates

    NASA Astrophysics Data System (ADS)

    Ma, Zhongwu; Ravelo, Ana Christina; Liu, Zhonghui; Zhou, Liping; Paytan, Adina

    2015-11-01

    Export production is an important component of the carbon cycle, modulating the climate system by transferring CO2 from the atmosphere to the deep ocean via the biological pump. Here we use barite accumulation rates to reconstruct export production in the eastern equatorial Pacific over the past 4.3 Ma. We find that export production fluctuated considerably on multiple time scales. Export production was on average higher (51 g C m-2 yr-1) during the Pliocene than the Pleistocene (40 g C m-2 yr-1), decreasing between 3 and 1 Ma (from more than 60 to 20 g C m-2 yr-1) followed by an increase over the last million years. These trends likely reflect basin-scale changes in nutrient inventory and ocean circulation. Our record reveals decoupling between export production and temperatures on these long (million years) time scale. On orbital time scales, export production was generally higher during cold periods (glacial maxima) between 4.3 and 1.1 Ma. This could be due to stronger wind stress and higher upwelling rates during glacial periods. A shift in the timing of maximum export production to deglaciations is seen in the last ~1.1 million years. Results from this study suggest that, in the eastern equatorial Pacific, mechanisms that affect nutrient supply and/or ecosystem structure and in turn carbon export on orbital time scales differ from those operating on longer time scales and that processes linking export production and climate-modulated oceanic conditions changed about 1.1 million years ago. These observations should be accounted for in climate models to ensure better predictions of future climate change.

  6. Non-contact Laser-based Human Respiration Rate Measurement

    NASA Astrophysics Data System (ADS)

    Scalise, L.; Marchionni, P.; Ercoli, I.

    2011-08-01

    At present the majority of the instrumentation, used in clinical environments, to measure human respiration rate are based on invasive and contact devices. The gold standard instrument is considered the spirometer which is largely used; it needs a direct contact and requires a collaboration by the patient. Laser Doppler Vibrometer (LDVi) is an optical, non-contact measurement system for the assessment of a surface velocity and displacement. LDVi has already been used for the measurement of the cardiac activity and for the measurement of the chest-wall displacements. The aims of this work are to select the best measurement point on the thoracic surface for LDVi monitoring of the respiration rate (RR) and to compare measured data with the RR valued provided by the spirometer. The measurement system is composed by a LDV system and a data acquisition board installed on a PC. Tests were made on 10 different point of the thorax for each patient. Patients population was composed by 33 subjects (17 male and 16 female). The optimal measurement point was chosen considering the maximum peak-to-peak value of the displacement measured by LDV. Before extracting RR we have used a special wavelet decomposition for better selection of the expiration peaks. A standard spirometer was used for the validation of the data. From tests it results that the optimal measurement point, namely is located on the inferior part of the thoracic region (left, front side). From our tests we have obtained a close correlation between the RR values measured by the spirometer and those measured by the proposed method: a difference of 14±211 ms on the RR value is reported for the entire population of 33 subjects. Our method allows a no-contact measurement of lungs activity (respiration period), reducing the electric and biological risks. Moreover it allows to measure in critical environment like in RMN or in burned skin where is difficult or impossible to apply electrodes.

  7. Low Velocity Difference Thermal Shear Layer Mixing Rate Measurements

    NASA Technical Reports Server (NTRS)

    Bush, Robert H.; Culver, Harry C. M.; Weissbein, Dave; Georgiadis, Nicholas J.

    2013-01-01

    Current CFD modeling techniques are known to do a poor job of predicting the mixing rate and persistence of slot film flow in co-annular flowing ducts with relatively small velocity differences but large thermal gradients. A co-annular test was devised to empirically determine the mixing rate of slot film flow in a constant area circular duct (D approx. 1ft, L approx. 10ft). The axial rate of wall heat-up is a sensitive measure of the mixing rate of the two flows. The inflow conditions were varied to simulate a variety of conditions characteristic of moderate by-pass ratio engines. A series of air temperature measurements near the duct wall provided a straightforward means to measure the axial temperature distribution and thus infer the mixing rate. This data provides a characterization of the slot film mixing rates encountered in typical jet engine environments. The experimental geometry and entrance conditions, along with the sensitivity of the results as the entrance conditions vary, make this a good test for turbulence models in a regime important to modern air-breathing propulsion research and development.

  8. Effects of frame rate and image resolution on pulse rate measured using multiple camera imaging photoplethysmography

    NASA Astrophysics Data System (ADS)

    Blackford, Ethan B.; Estepp, Justin R.

    2015-03-01

    Non-contact, imaging photoplethysmography uses cameras to facilitate measurements including pulse rate, pulse rate variability, respiration rate, and blood perfusion by measuring characteristic changes in light absorption at the skin's surface resulting from changes in blood volume in the superficial microvasculature. Several factors may affect the accuracy of the physiological measurement including imager frame rate, resolution, compression, lighting conditions, image background, participant skin tone, and participant motion. Before this method can gain wider use outside basic research settings, its constraints and capabilities must be well understood. Recently, we presented a novel approach utilizing a synchronized, nine-camera, semicircular array backed by measurement of an electrocardiogram and fingertip reflectance photoplethysmogram. Twenty-five individuals participated in six, five-minute, controlled head motion artifact trials in front of a black and dynamic color backdrop. Increasing the input channel space for blind source separation using the camera array was effective in mitigating error from head motion artifact. Herein we present the effects of lower frame rates at 60 and 30 (reduced from 120) frames per second and reduced image resolution at 329x246 pixels (one-quarter of the original 658x492 pixel resolution) using bilinear and zero-order downsampling. This is the first time these factors have been examined for a multiple imager array and align well with previous findings utilizing a single imager. Examining windowed pulse rates, there is little observable difference in mean absolute error or error distributions resulting from reduced frame rates or image resolution, thus lowering requirements for systems measuring pulse rate over sufficient length time windows.

  9. Rapid Measurement of Neutron Dose Rate for Transport Index

    SciTech Connect

    Morris, R.L.

    2000-02-27

    A newly available neutron dose equivalent remmeter with improved sensitivity and energy response has been put into service at Rocky Flats Environmental Technology Site (RFETS). This instrument is being used to expedite measurement of the Transport Index and as an ALARA tool to identify locations where slightly elevated neutron dose equivalent rates exist. The meter is capable of measuring dose rates as low as 0.2 {mu}Sv per hour (20 {mu}rem per hour). Tests of the angular response and energy response of the instrument are reported. Calculations of the theoretical instrument response made using MCNP{trademark} are reported for materials typical of those being shipped.

  10. Measurement of diffusion coefficients from solution rates of bubbles

    NASA Technical Reports Server (NTRS)

    Krieger, I. M.

    1979-01-01

    The rate of solution of a stationary bubble is limited by the diffusion of dissolved gas molecules away from the bubble surface. Diffusion coefficients computed from measured rates of solution give mean values higher than accepted literature values, with standard errors as high as 10% for a single observation. Better accuracy is achieved with sparingly soluble gases, small bubbles, and highly viscous liquids. Accuracy correlates with the Grashof number, indicating that free convection is the major source of error. Accuracy should, therefore, be greatly increased in a gravity-free environment. The fact that the bubble will need no support is an additional important advantage of Spacelab for this measurement.

  11. Simultaneous measurements of umbilical uptake, fetal utilization rate, and fetal turnover rate of glucose.

    PubMed

    Hay, W W; Sparks, J W; Quissell, B J; Battaglia, F C; Meschia, G

    1981-06-01

    Fetal umbilical glucose uptake was compared with simultaneous measurements of glucose turnover and utilization rates in 12 pregnant sheep, at a mean of 137 days gestational age (range, 118-146 days). Umbilical glucose uptake was calculated by application of the Fick principle. Fetal glucose turnover rate was measured by a primed-constant infusion of [14C]- and [3H]glucose (glucose turnover rate = tracer infusion rate divided by fetal glucose sp act). The calculation of fetal glucose utilization rate required substraction of the loss of tracer to the placenta from the tracer infusion rate, thus defining the net tracer entry into the fetus for direct comparison with the net umbilical glucose uptake. In fed, normoglycemic sheep, these measurements demonstrated statistical equivalence of umbilical glucose uptake rate (4.77 mg.min-1.kg-1 +/- 0.34 SE) and glucose utilization rate ([14C]glucose, 5.58 mg.min-1.kg-1 +/- 0.54 SE; and [3H]glucose, 7.19 mg.min-1.kg-1 +/- 1.24 SE) when tested by two-way analysis of variance (P greater than 0.1). In three fasted, hypoglycemic sheep, the umbilical glucose uptake rate fell to 1.43 mg.min-1.kg-1 +/- 0.56 SE, which was considerably lower than the simultaneous glucose utilization rate ([14C]glucose, 4.78 mg.min-1.kg-1 +/- 0.48 SE; and [3H]glucose, 6.81 mg.min-1.kg-1 +/- 2.19 SE). Thus, in the normoglycemic, late-gestation fetal lamb, there appears to be little glucogenesis, whereas glucogenesis may become significant during fasting-induced fetal hypoglycemia.

  12. Magnetic Implosion for Novel Strength Measurements at High Strain Rates

    SciTech Connect

    Lee, H.; Preston, D.L.; Bartsch, R.R.; Bowers, R.L.; Holtkamp, D.; Wright, B.L.

    1998-10-19

    Recently Lee and Preston have proposed to use magnetic implosions as a new method for measuring material strength in a regime of large strains and high strain rates inaccessible to previously established techniques. By its shockless nature, this method avoids the intrinsic difficulties associated with an earlier approach using high explosives. The authors illustrate how the stress-strain relation for an imploding liner can be obtained by measuring the velocity and temperature history of its inner surface. They discuss the physical requirements that lead us to a composite liner design applicable to different test materials, and also compare the code-simulated prediction with the measured data for the high strain-rate experiments conducted recently at LANL. Finally, they present a novel diagnostic scheme that will enable us to remove the background in the pyrometric measurement through data reduction.

  13. A High Frequency Response Relaxed Eddy Accumulation Flux Measurement System for Sampling Short-Lived Biogenic Volatile Organic Compounds

    EPA Science Inventory

    A second-generation relaxed eddy accumulation system was built and tested with the capability to measure vertical biogenic volatile organic compound (VOC) fluxes at levels as low as 10 µg C m−2 hr−1. The system features a continuous, integrated gas-phase ozo...

  14. Measurement of interseismic strain accumulation across the North Anatolian Fault by satellite radar interferometry

    NASA Astrophysics Data System (ADS)

    Wright, Tim; Parsons, Barry; Fielding, Eric

    In recent years, interseismic crustal velocities and strains have been determined for a number of tectonically active areas through repeated measurements using the Global Positioning System. The terrain in such areas is often remote and difficult, and the density of GPS measurements relatively sparse. In principle, satellite radar interferometry can be used to make millimetric-precision measurements of surface displacement over large surface areas. In practice, the small crustal deformation signal is dominated over short time intervals by errors due to atmospheric, topographic and orbital effects. Here we show that these effects can be over-come by stacking multiple interferograms, after screening for atmospheric anomalies, effectively creating a new interferogram that covers a longer time interval. In this way, we have isolated a 70 km wide region of crustal deformation across the eastern end of the North Anatolian Fault, Turkey. The distribution of deformation is consistent with slip of 17-32 mm/yr below 5-33 km on the extension of the surface fault at depth. If the GPS determined slip rate of 24±1 mm/yr is accepted, the locking depth is constrained to 18±6 km.

  15. Mauna Loa lava accumulation rates at the Hilo drill site: Formation of lava deltas during a period of declining overall volcanic growth

    USGS Publications Warehouse

    Lipman, P.W.; Moore, J.G.

    1996-01-01

    Accumulation rates for lava flows erupted from Mauna Loa, as sampled in the uppermost 280 m of the Hilo drill hole, vary widely for short time intervals (several thousand years), but overall are broadly similar to those documented elsewhere on this volcano since 100 ka. Thickness variations and accumulation rates for Mauna Loa lavas at the Hilo drill site have been strongly affected by local paleotopography, including funneling and ponding between Mauna Kea and Kilauea. In addition, gentle submerged slopes of Mauna Kea in Hilo Bay have permitted large shoreline displacements by Mauna Loa flows. Ages of eruptive intervals have been determined from published isotopic data and from eustatic sea level curves modified to include the isostatic subsidence of the island of Hawaii at 2.2-2.6 mm/yr. Prior to 10 ka, rates of Mauna Loa lava accumulation at the drill site varied from 0.6 to 4.3 mm/yr for dateable intervals, with an overall rate of 1.8 mm/yr. Major eruptive pulses at about 1.3 and 10 ka, each probably representing a single long-lived eruption based on lack of weathering between flow units, increase the overall accumulation rate to 2.4 mm/yr. The higher rate since 10 ka reflects construction of thick near-shoreline lava deltas as postglacial sea levels rose rapidly. Large lava deltas form only along coastal segments where initially subaerial slopes have been submerged by the combined effects of eustatic sea level rise, isostatic subsidence, or spreading of volcano flanks. Overall accumulation of 239 m of lava at the drill site since 100-120 ka closely balances submergence of the Hilo area, suggesting that processes of coastal lava deposition have been modulated by rise in sea level. The Hilo accumulation rate is slightly higher than average rates of 1-2 mm/yr determined elsewhere along the Mauna Loa coast, based on rates of shoreline coverage and dated sea cliff and fault scarp exposures. Low rates of coastal lava accumulation since 100 ka, near or below the rate

  16. Heart rate measurement based on face video sequence

    NASA Astrophysics Data System (ADS)

    Xu, Fang; Zhou, Qin-Wu; Wu, Peng; Chen, Xing; Yang, Xiaofeng; Yan, Hong-jian

    2015-03-01

    This paper proposes a new non-contact heart rate measurement method based on photoplethysmography (PPG) theory. With this method we can measure heart rate remotely with a camera and ambient light. We collected video sequences of subjects, and detected remote PPG signals through video sequences. Remote PPG signals were analyzed with two methods, Blind Source Separation Technology (BSST) and Cross Spectral Power Technology (CSPT). BSST is a commonly used method, and CSPT is used for the first time in the study of remote PPG signals in this paper. Both of the methods can acquire heart rate, but compared with BSST, CSPT has clearer physical meaning, and the computational complexity of CSPT is lower than that of BSST. Our work shows that heart rates detected by CSPT method have good consistency with the heart rates measured by a finger clip oximeter. With good accuracy and low computational complexity, the CSPT method has a good prospect for the application in the field of home medical devices and mobile health devices.

  17. NASA Measures Heavy Rainfall Rates in Tropical Cyclone Vardah

    NASA Video Gallery

    On Dec. 11 at 9:41 p.m. EST (Dec. 12 at 0241 UTC) GPM found very heavy rainfall present in storms in the southern side of the eye. Rain was measured by GPM's DPR falling at a rate of over 235 mm (9...

  18. An improved method of measuring heart rate using a webcam

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Ouyang, Jianfei; Yan, Yonggang

    2014-09-01

    Measuring heart rate traditionally requires special equipment and physical contact with the subject. Reliable non-contact and low-cost measurements are highly desirable for convenient and comfortable physiological self-assessment. Previous work has shown that consumer-grade cameras can provide useful signals for remote heart rate measurements. In this paper a simple and robust method of measuring the heart rate using low-cost webcam is proposed. Blood volume pulse is extracted by proper Region of Interest (ROI) and color channel selection from image sequences of human faces without complex computation. Heart rate is subsequently quantified by spectrum analysis. The method is successfully applied under natural lighting conditions. Results of experiments show that it takes less time, is much simpler, and has similar accuracy to the previously published and widely used method of Independent Component Analysis (ICA). Benefitting from non-contact, convenience, and low-costs, it provides great promise for popularization of home healthcare and can further be applied to biomedical research.

  19. A Simple Device to Measure Root Growth Rates

    ERIC Educational Resources Information Center

    Rauser, Wilfried E.; Horton, Roger F.

    1975-01-01

    Describes construction and use of a simple auxanometer which students can use to accurately measure root growth rates of intact seedlings. Typical time course data are presented for the effect of ethylene and indole acetic acid on pea root growth. (Author/BR)

  20. Variation of Accumulation Rates Over the Last Eight Centuries on the East Antarctic Plateau Derived from Volcanic Signals in Ice Cores

    NASA Technical Reports Server (NTRS)

    Anschuetz, H.; Sinisalo, A.; Isaksson, E.; McConnell, J. R.; Hamran, S.-E.; Bisiaux, M. M.; Pasteris, D.; Neumann, T. A.; Winther, J.-G.

    2011-01-01

    Volcanic signatures in ice-core records provide an excellent means to date the cores and obtain information about accumulation rates. From several ice cores it is thus possible to extract a spatio-temporal accumulation pattern. We show records of electrical conductivity and sulfur from firn cores from the Norwegian-USA scientific traverse during the International Polar Year 2007-2009 (IPY) through East Antarctica. Major volcanic eruptions are identified and used to assess century-scale accumulation changes. The largest changes seem to occur in the most recent decades with accumulation over the period 1963- 2007/08 being up to 25 % different from the long-term record. There is no clear overall trend, some sites show an increase in accumulation over the period 1963 to present while others show a decrease. Almost all of the sites above 3200 m above sea level (asl) suggest a decrease. These sites also show a significantly lower accumulation value than large-scale assessments both for the period 1963 to present and for the long-term mean at the respective drill sites. The spatial accumulation distribution is influenced mainly by elevation and distance to the ocean (continentality), as expected. Ground-penetrating radar data around the drill sites show a spatial variability within 10-20 % over several tens of kilometers, indicating that our drill sites are well representative for the area around them. Our results are important for large-scale assessments of Antarctic mass balance and model validation.

  1. Ignition Rate Measurement of Laser-Ignited Coals

    SciTech Connect

    John C. Chen; Vinayak Kabadi

    1997-10-31

    We established a novel experiment to study the ignition of pulverized coals under conditions relevant to utility boilers. Specifically, we determined the ignition mechanism of pulverized-coal particles under various conditions of particle size, coal type, and freestream oxygen concentration. We also measured the ignition rate constant of a Pittsburgh #8 high-volatile bituminous coal by direct measurement of the particle temperature at ignition, and incorporating this measurement into a mathematical model for the ignition process. The model, called Distributed Activation Energy Model of Ignition, was developed previously by our group to interpret conventional drop-tube ignition experiments, and was modified to accommodate the present study.

  2. MEASURING TINY MASS ACCRETION RATES ONTO YOUNG BROWN DWARFS

    SciTech Connect

    Herczeg, Gregory J.; Cruz, Kelle L.; Hillenbrand, Lynne A.

    2009-05-10

    We present low-resolution Keck I/LRIS spectra spanning from 3200 to 9000 A of nine young brown dwarfs and three low-mass stars in the TW Hya Association and in Upper Sco. The optical spectral types of the brown dwarfs range from M5.5 to M8.75, though two have near-IR spectral types of early L dwarfs. We report new accretion rates derived from excess Balmer continuum emission for the low-mass stars TW Hya and Hen 3-600A and the brown dwarfs 2MASS J12073347-3932540, UScoCTIO 128, SSSPM J1102-3431, USco J160606.29-233513.3, DENIS-P J160603.9-205644, and Oph J162225-240515B, and upper limits on accretion for the low-mass star Hen 3-600B and the brown dwarfs UScoCTIO 112, Oph J162225-240515A, and USco J160723.82-221102.0. For the six brown dwarfs in our sample that are faintest at short wavelengths, the accretion luminosity or upper limit is measurable only when the image is binned over large wavelength intervals. This method extends our sensitivity to accretion rate down to {approx}10{sup -13} M{sub sun}yr{sup -1} for brown dwarfs. Since the ability to measure an accretion rate from excess Balmer continuum emission depends on the contrast between excess continuum emission and the underlying photosphere, for objects with earlier spectral types the upper limit on accretion rate is much higher. Absolute uncertainties in our accretion rate measurements of {approx}3-5 include uncertainty in accretion models, brown dwarf masses, and distance. The accretion rate of 2 x 10{sup -12} M {sub sun} yr{sup -1} onto 2MASS J12073347-3932540 is within 15% of two previous measurements, despite large changes in the H{alpha} flux.

  3. Simultaneous measurement of breathing rate and heart rate using a microbend multimode fiber optic sensor

    NASA Astrophysics Data System (ADS)

    Chen, Zhihao; Lau, Doreen; Teo, Ju Teng; Ng, Soon Huat; Yang, Xiufeng; Kei, Pin Lin

    2014-05-01

    We propose and demonstrate the feasibility of using a highly sensitive microbend multimode fiber optic sensor for simultaneous measurement of breathing rate (BR) and heart rate (HR). The sensing system consists of a transceiver, microbend multimode fiber, and a computer. The transceiver is comprised of an optical transmitter, an optical receiver, and circuits for data communication with the computer via Bluetooth. Comparative experiments conducted between the sensor and predicate commercial physiologic devices showed an accuracy of ±2 bpm for both BR and HR measurement. Our preliminary study of simultaneous measurement of BR and HR in a clinical trial conducted on 11 healthy subjects during magnetic resonance imaging (MRI) also showed very good agreement with measurements obtained from conventional MR-compatible devices.

  4. Indirect rp-process Rate Measurements from Single Neutron Removal

    NASA Astrophysics Data System (ADS)

    Amthor, A. M.; Bazin, D.; Becerril, A.; Cole, A.; Cook, J.; Estrade, A.; Gade, A.; Howard, M.; Lorusso, G.; Matos, M.; Pereira, J.; Portillo, M.; Schatz, H.; Sherrill, B.; Smith, K.; Stolz, A.; Weisshaar, D.; Zegers, R. G. T.; Galaviz, D.; Chen, A.; Fulop, Zs.; Smith, E.; Wiescher, M.

    2007-10-01

    The structure of nuclei along the rp-process path in Type I X-ray bursts has been studied using neutron removal from radioactive beams produced at the National Superconducting Cyclotron Laboratory. Recently, ^37Ca and ^36K have been studied in this way to reduce the uncertainty in ^35Ar(p,γ)^36K and ^36K(p,γ)^37Ca reaction rates, which are important during burst rise. Under burst conditions these rates are dominated by resonant capture contributions from individual resonances because of the low level density just above the proton threshold, precluding the use of statistical methods based on level density to determine the reaction rates. Therefore, precise structure measurements are required to reduce the orders of magnitude rate uncertainty in these key reactions and thereby constrain X-ray burst models. Preliminary results will be presented along with the implications for X-ray burst models.

  5. A method to simultaneously and continuously measure the 222Rn and 220Rn exhalation rates of soil in an open loop.

    PubMed

    Tan, Yanliang; Xiao, Detao; Yuan, Hongzhi; Shan, Jian

    2014-01-01

    This paper presents a process in which a radon monitor based on the electrostatic collection method is used to measure the (222)Rn and (220)Rn exhalation rates simultaneously and continuously employing a ventilation-type accumulation chamber. Generally, the radon exhalation rate can be measured by accumulation technique, but cannot be measured continuously. The advantage of this method using a ventilation-type accumulation chamber is that the radon exhalation rates can be measured continuously. Even though the environmental air is drawn into the chamber, the low atmospheric values of radon and thoron do not influence the measurement accuracy. The (222)Rn and (220)Rn exhalation rates error from the environmental air is less than 5% in this experiment.

  6. Influence of the rate of ethanol production and accumulation on the viability of Saccharomyces cerevisiae in "rapid fermentation".

    PubMed

    Nagodawithana, T W; Steinkraus, K H

    1976-02-01

    Whereas "rapid fermentation" of diluted clover honey (25 degrees Brix) fortified with yeast nutrients using 8 X 10(8) brewers' yeast cells per ml resulted in an ethanol content of 9.5% (wt/vol; 12% vol/vol) in 3 h at 30 C, death rate of the yeast cells during this period was essentially logarithmic. Whereas 6 h was required to reach the same ethanol content at 15 C, the yeast cells retained their viability. Using a lower cell population (6 X 10(7) cells/ml), a level at which the fermentation was no longer "rapid," the yeast cells also retained their viability at 30 C. Ethanol added to the medium was much less lethal than the same or less quantities of ethanol produced by the cell in "rapid fermentation." It was considered possible that ethanol was produced so rapidly at 30 C that it could not diffuse out of the cell as rapidly as it was formed. The hypothesis was postulated that ethanol accumulating in the cell was contributing to the high death rate at 30 C. It was found that the intracellular ethanol concentration reached a level of approximately 2 X 10(11) ethanol molecules/cell in the first 30 min of fermentation at 30 C. At 15 C, with the same cell count, intracellular ethanol concentration reached a level of approximately 4 X 10(10) ethanol molecules/cell and viability remained high. Also, at 30 C with a lower cell population (6 X 10(7) cells/ml), under which conditions fermentation was no longer "rapid," intracellular ethanol concentration reached a similar level (4 X 10(10) molecules ethanol/cell) and the cells retained their viability. Alcohol dehydrogenase (ADH) lost its activity in brewers' yeast under conditions of "rapid fermentation" at 30 C but retained its activity in cells under similar conditions at 15 C. ADH activity was also retained in fermentations at 30 C with cell populations of 6 X 10(7)/ml. It would appear that an intracellular level of about 5 X 10(10) ethanol molecules/cell is normal and that this level does not damage either cell

  7. Water filtration rate and infiltration/accumulation of low density lipoproteins in 3 different modes of endothelial/smooth muscle cell co-cultures.

    PubMed

    Ding, ZuFeng; Fan, YuBo; Deng, XiaoYan

    2009-11-01

    Using different endothelial/smooth muscle cell co-culture modes to simulate the intimal structure of blood vessels, the water filtration rate and the infiltration/accumulation of LDL of the cultured cell layers were studied. The three cell culture modes of the study were: (i) The endothelial cell monolayer (EC/Phi); (ii) endothelial cells directly co-cultured on the smooth muscle cell monolayer (EC-SMC); (iii) endothelial cells and smooth muscle cells cultured on different sides of a Millicell-CM membrane (EC/SMC). It was found that under the same condition, the water filtration rate was the lowest for the EC/SMC mode and the highest for the EC/Phi mode, while the infiltration/accumulation of DiI-LDLs was the lowest in the EC/Phi mode and the highest in the EC-SMC mode. It was also found that DiI-LDL infiltration/accumulation in the cultured cell layers increased with the increasing water filtration rate. The results from the in vitro model study therefore suggest that the infiltration/accumulation of the lipids within the arterial wall is positively correlated with concentration polarization of atherogenic lipids, and the integrity of the endothelium plays an important role in the penetration and accumulation of atherogenic lipids in blood vessel walls.

  8. Scalar dissipation rate measurements in a starting jet

    NASA Astrophysics Data System (ADS)

    Soulopoulos, N.; Hardalupas, Y.; Taylor, A. M. K. P.

    2014-03-01

    Measurements of the scalar dissipation rate are taken in an impulsively started gas jet, using planar laser-induced fluorescence. The measurements are well-resolved spatially. The deteriorating effect of experimental noise on this experiment is treated with a Wiener filter, which is shown to be applicable to this large-scale inhomogeneous flow. The accuracy of the scalar dissipation rate is within 20 %, as determined from an explicit calculation of the filtering errors. The residual fields that remain after the filtering are analysed in detail, and their statistical properties show that these resemble white noise to a good approximation. The level of corrections is minimal for the scalar field but it is of the order of 40 % for the scalar dissipation rate. An examination of the filtering operation using modelled spectra and the measured spatial resolution shows that the Wiener filter produces errors in the estimate of the scalar dissipation rate ˜30 %, for Taylor-scale Reynolds number up to 1,000. The implications of this modelling are discussed with respect to common experimental situations and point out the relative merits of improving the spatial resolution as compared to improvements in the signal-to-noise ratio.

  9. Dissolution rate measurements of TiN in Ti-6242

    SciTech Connect

    Bewlay, B.P.; Gigliotti, M.F.X.

    1997-01-01

    This paper describes measurements of the dissolution rate of nitrided Ti sponge and monolithic TiN rod in molten Ti-6242. The dissolution rate is described in terms of an interface recession rate that was 2.2 {micro}m/s for a Ti-6242 temperature of 1,725 C and dissolution times between 1 and 100 min. Similar dissolution rates were measured for nitrided sponge and monolithic rod. This report also descries the microstructural and chemical interdiffusion phenomena that occur during dissolution of solid {delta}TiN in molten Ti-6242. There is a N-containing solid {alpha}Ti layer and a N-solidified {beta}Ti layer between the solid {delta}TiN and liquid Ti-6242 during dissolution. Microprobe measurements indicate that diffusion of Al, Zr, Sn and Mo into {delta}TiN did not occur. Steep N concentration profiles were observed in the {alpha}Ti layer. Al, Zr, Sn and Mo were observed in the N-solidified {beta}Ti layer contained <1% N. Similar microstructural and interdiffusional behaviors were observed during dissolution of nitrided sponge and monolithic {delta}TiN rod in molten Ti-6242.

  10. PRECEDENTS FOR AUTHORIZATION OF CONTENTS USING DOSE RATE MEASUREMENTS

    SciTech Connect

    Abramczyk, G.; Bellamy, S.; Nathan, S.; Loftin, B.

    2012-06-05

    For the transportation of Radioactive Material (RAM) packages, the requirements for the maximum allowed dose rate at the package surface and in its vicinity are given in Title 10 of the Code of Federal Regulations, Section 71.47. The regulations are based on the acceptable dose rates to which the public, workers, and the environment may be exposed. As such, the regulations specify dose rates, rather than quantity of radioactive isotopes and require monitoring to confirm the requirements are met. 10CFR71.47 requires that each package of radioactive materials offered for transportation must be designed and prepared for shipment so that under conditions normally incident to transportation the radiation level does not exceed 2 mSv/h (200 mrem/h) at any point on the external Surface of the package, and the transport index does not exceed 10. Before shipment, the dose rate of the package is determined by measurement, ensuring that it conforms to the regulatory limits, regardless of any analyses. This is the requirement for all certified packagings. This paper discusses the requirements for establishing the dose rates when shipping RAM packages and the precedents for meeting these requirements by measurement.

  11. Acoustic measurement of the Deepwater Horizon Macondo well flow rate

    PubMed Central

    Camilli, Richard; Di Iorio, Daniela; Bowen, Andrew; Reddy, Christopher M.; Techet, Alexandra H.; Yoerger, Dana R.; Whitcomb, Louis L.; Seewald, Jeffrey S.; Sylva, Sean P.; Fenwick, Judith

    2012-01-01

    On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and acoustic Doppler sonar operating onboard a remotely operated vehicle for noncontact measurement of flow cross-section and velocity from the well’s two leak sites. Over 2,500 sonar cross-sections and over 85,000 Doppler velocity measurements were recorded during the acquisition process. These data were then applied to turbulent jet and plume flow models to account for entrained water and calculate a combined hydrocarbon flow rate from the two leak sites at seafloor conditions. Based on the chemical composition of end-member samples collected from within the well, this bulk volumetric rate was then normalized to account for contributions from gases and condensates at initial leak source conditions. Results from this investigation indicate that on May 31, 2010, the well’s oil flow rate was approximately 0.10 ± 0.017 m3 s-1 at seafloor conditions, or approximately 85 ± 15 kg s-1 (7.4 ± 1.3 Gg d-1), equivalent to approximately 57,000 ± 9,800 barrels of oil per day at surface conditions. End-member chemical composition indicates that this oil release rate was accompanied by approximately an additional 24 ± 4.2 kg s-1 (2.1 ± 0.37 Gg d-1) of natural gas (methane through pentanes), yielding a total hydrocarbon release rate of 110 ± 19 kg s-1 (9.5 ± 1.6 Gg d-1). PMID:21903931

  12. Acoustic measurement of the Deepwater Horizon Macondo well flow rate.

    PubMed

    Camilli, Richard; Di Iorio, Daniela; Bowen, Andrew; Reddy, Christopher M; Techet, Alexandra H; Yoerger, Dana R; Whitcomb, Louis L; Seewald, Jeffrey S; Sylva, Sean P; Fenwick, Judith

    2012-12-11

    On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and acoustic Doppler sonar operating onboard a remotely operated vehicle for noncontact measurement of flow cross-section and velocity from the well's two leak sites. Over 2,500 sonar cross-sections and over 85,000 Doppler velocity measurements were recorded during the acquisition process. These data were then applied to turbulent jet and plume flow models to account for entrained water and calculate a combined hydrocarbon flow rate from the two leak sites at seafloor conditions. Based on the chemical composition of end-member samples collected from within the well, this bulk volumetric rate was then normalized to account for contributions from gases and condensates at initial leak source conditions. Results from this investigation indicate that on May 31, 2010, the well's oil flow rate was approximately 0.10 ± 0.017 m(3) s(-1) at seafloor conditions, or approximately 85 ± 15 kg s(-1) (7.4 ± 1.3 Gg d(-1)), equivalent to approximately 57,000 ± 9,800 barrels of oil per day at surface conditions. End-member chemical composition indicates that this oil release rate was accompanied by approximately an additional 24 ± 4.2 kg s(-1) (2.1 ± 0.37 Gg d(-1)) of natural gas (methane through pentanes), yielding a total hydrocarbon release rate of 110 ± 19 kg s(-1) (9.5 ± 1.6 Gg d(-1)).

  13. Directly Measured Heating Rates of a Tropical Subvisible Cirrus Cloud

    NASA Technical Reports Server (NTRS)

    Bucholtz, Anthongy; Hlavka, Dennis L.; McGill, Matthew J.; Schmidt, K. Sebastian; Pilewskie, Peter; Davis, Sean M.; Reid, Elizabeth A.; Walker, Annette L.

    2010-01-01

    We present the first direct measurements of the infrared and solar heating rates of a tropical subvisible cirrus (SVC) cloud sampled off the east coast of Nicaragua on 25 July 2007 by the NASA ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4). On this day a persistent thin cirrus layer, with mostly clear skies underneath, was detected in real time by the cloud lidar on the ER-2, and the aircraft was directed to profile down through the SVC. Measurements of the net broadband infrared irradiance and spectrally integrated solar irradiance above, below, and through the SVC are used to determine the infrared and solar heating rates of the cloud. The lidar measurements show that the variable SVC layer was located between approximately 13 and 15 km. Its midvisible optical depth varied from 0.01 to 0.10 with a mean of 0.034 +/- 0.033. Its depolarization ratio was approximately 0.4, indicative of ice clouds. From the divergence of the measured net irradiances the infrared heating rate of the SVC was determined to be approximately 2.50 - 3.24 K/d and the solar heating rate was found to be negligible. These values are consistent with previous indirect observations of other SVC and with model-generated heating rates of SVC with similar optical depths. This study illustrates the utility and potential of the profiling sampling strategy employed here. A more fully instrumented high-altitude aircraft that also included in situ cloud and aerosol probes would provide a comprehensive data set for characterizing both the radiative and microphysical properties of these ubiquitous tropical clouds

  14. Estimation of hydrocarbon biodegradation rates in gasoline-contaminated sediment from measured respiration rates

    USGS Publications Warehouse

    Baker, R.J.; Baehr, A.L.; Lahvis, M.A.

    2000-01-01

    An open microcosm method for quantifying microbial respiration and estimating biodegradation rates of hydrocarbons in gasoline-contaminated sediment samples has been developed and validated. Stainless-steel bioreactors are filled with soil or sediment samples, and the vapor-phase composition (concentrations of oxygen (O2), nitrogen (N2), carbon dioxide (CO2), and selected hydrocarbons) is monitored over time. Replacement gas is added as the vapor sample is taken, and selection of the replacement gas composition facilitates real-time decision-making regarding environmental conditions within the bioreactor. This capability allows for maintenance of field conditions over time, which is not possible in closed microcosms. Reaction rates of CO2 and O2 are calculated from the vapor-phase composition time series. Rates of hydrocarbon biodegradation are either measured directly from the hydrocarbon mass balance, or estimated from CO2 and O2 reaction rates and assumed reaction stoichiometries. Open microcosm experiments using sediments spiked with toluene and p-xylene were conducted to validate the stoichiometric assumptions. Respiration rates calculated from O2 consumption and from CO2 production provide estimates of toluene and p- xylene degradation rates within about ??50% of measured values when complete mineralization stoichiometry is assumed. Measured values ranged from 851.1 to 965.1 g m-3 year-1 for toluene, and 407.2-942.3 g m-3 year-1 for p- xylene. Contaminated sediment samples from a gasoline-spill site were used in a second set of microcosm experiments. Here, reaction rates of O2 and CO2 were measured and used to estimate hydrocarbon respiration rates. Total hydrocarbon reaction rates ranged from 49.0 g m-3 year-1 in uncontaminated (background) to 1040.4 g m-3 year-1 for highly contaminated sediment, based on CO2 production data. These rate estimates were similar to those obtained independently from in situ CO2 vertical gradient and flux determinations at the

  15. Hydraulic conductance as well as nitrogen accumulation plays a role in the higher rate of leaf photosynthesis of the most productive variety of rice in Japan

    PubMed Central

    Taylaran, Renante D.; Adachi, Shunsuke; Ookawa, Taiichiro; Usuda, Hideaki; Hirasawa, Tadashi

    2011-01-01

    An indica variety Takanari is known as one of the most productive rice varieties in Japan and consistently produces 20–30% heavier dry matter during ripening than Japanese commercial varieties in the field. The higher rate of photosynthesis of individual leaves during ripening has been recognized in Takanari. By using pot-grown plants under conditions of minimal mutual shading, it was confirmed that the higher rate of leaf photosynthesis is responsible for the higher dry matter production after heading in Takanari as compared with a japonica variety, Koshihikari. The rate of leaf photosynthesis and shoot dry weight became larger in Takanari after the panicle formation and heading stages, respectively, than in Koshihikari. Roots grew rapidly in the panicle formation stage until heading in Takanari compared with Koshihikari. The higher rate of leaf photosynthesis in Takanari resulted not only from the higher content of leaf nitrogen, which was caused by its elevated capacity for nitrogen accumulation, but also from higher stomatal conductance. When measured under light-saturated conditions, stomatal conductance was already decreased due to the reduction in leaf water potential in Koshihikari even under conditions of a relatively small difference in leaf–air vapour pressure difference. In contrast, the higher stomatal conductance was supported by the maintenance of higher leaf water potential through the higher hydraulic conductance in Takanari with the larger area of root surface. However, no increase in root hydraulic conductivity was expected in Takanari. The larger root surface area of Takanari might be a target trait in future rice breeding for increasing dry matter production. PMID:21527630

  16. Hydraulic conductance as well as nitrogen accumulation plays a role in the higher rate of leaf photosynthesis of the most productive variety of rice in Japan.

    PubMed

    Taylaran, Renante D; Adachi, Shunsuke; Ookawa, Taiichiro; Usuda, Hideaki; Hirasawa, Tadashi

    2011-07-01

    An indica variety Takanari is known as one of the most productive rice varieties in Japan and consistently produces 20-30% heavier dry matter during ripening than Japanese commercial varieties in the field. The higher rate of photosynthesis of individual leaves during ripening has been recognized in Takanari. By using pot-grown plants under conditions of minimal mutual shading, it was confirmed that the higher rate of leaf photosynthesis is responsible for the higher dry matter production after heading in Takanari as compared with a japonica variety, Koshihikari. The rate of leaf photosynthesis and shoot dry weight became larger in Takanari after the panicle formation and heading stages, respectively, than in Koshihikari. Roots grew rapidly in the panicle formation stage until heading in Takanari compared with Koshihikari. The higher rate of leaf photosynthesis in Takanari resulted not only from the higher content of leaf nitrogen, which was caused by its elevated capacity for nitrogen accumulation, but also from higher stomatal conductance. When measured under light-saturated conditions, stomatal conductance was already decreased due to the reduction in leaf water potential in Koshihikari even under conditions of a relatively small difference in leaf-air vapour pressure difference. In contrast, the higher stomatal conductance was supported by the maintenance of higher leaf water potential through the higher hydraulic conductance in Takanari with the larger area of root surface. However, no increase in root hydraulic conductivity was expected in Takanari. The larger root surface area of Takanari might be a target trait in future rice breeding for increasing dry matter production.

  17. Measurement of CPAS Main Parachute Rate of Descent

    NASA Technical Reports Server (NTRS)

    Ray, Eric S.

    2011-01-01

    The Crew Exploration Vehicle Parachute Assembly System (CPAS) is being designed to land the Orion Crew Module (CM) at a safe rate of descent at splashdown. Flight test performance must be measured to a high degree of accuracy to ensure this requirement is met with the most efficient design possible. Although the design includes three CPAS Main parachutes, the requirement is that the system must not exceed 33 ft/s under two Main parachutes, should one of the Main parachutes fail. Therefore, several tests were conducted with clusters of two Mains. All of the steady-state rate of descent data are normalized to standard sea level conditions and checked against the limit. As the Orion design gains weight, the system is approaching this limit to within measurement precision. Parachute "breathing," cluster interactions, and atmospheric anomalies can cause the rate of descent to vary widely and lead to challenges in characterizing parachute terminal performance. An early test had contradictory rate of descent results from optical trajectory and Differential Global Positioning Systems (DGPS). A thorough analysis of the data sources and error propagation was conducted to determine the uncertainty in the trajectory. It was discovered that the Time Space Position Information (TSPI) from the optical tracking provided accurate position data. However, the velocity from TPSI must be computed via numerical differentiation, which is prone to large error. DGPS obtains position through pseudo-range calculations from multiple satellites and velocity through Doppler shift of the carrier frequency. Because the velocity from DGPS is a direct measurement, it is more accurate than TSPI velocity. To remedy the situation, a commercial off-the-shelf product that combines GPS and an Inertial Measurement Unit (IMU) was purchased to significantly improve rate of descent measurements. This had the added benefit of solving GPS dropouts during aircraft extraction. Statistical probability

  18. MEASURING THE EVOLUTIONARY RATE OF COOLING OF ZZ Ceti

    SciTech Connect

    Mukadam, Anjum S.; Fraser, Oliver; Riecken, T. S.; Kronberg, M. E.; Bischoff-Kim, Agnes; Corsico, A. H.; Montgomery, M. H.; Winget, D. E.; Hermes, J. J.; Winget, K. I.; Falcon, Ross E.; Reaves, D.; Kepler, S. O.; Romero, A. D.; Chandler, D. W.; Kuehne, J. W.; Sullivan, D. J.; Von Hippel, T.; Mullally, F.; Shipman, H.; and others

    2013-07-01

    We have finally measured the evolutionary rate of cooling of the pulsating hydrogen atmosphere (DA) white dwarf ZZ Ceti (Ross 548), as reflected by the drift rate of the 213.13260694 s period. Using 41 yr of time-series photometry from 1970 November to 2012 January, we determine the rate of change of this period with time to be dP/dt = (5.2 {+-} 1.4) Multiplication-Sign 10{sup -15} s s{sup -1} employing the O - C method and (5.45 {+-} 0.79) Multiplication-Sign 10{sup -15} s s{sup -1} using a direct nonlinear least squares fit to the entire lightcurve. We adopt the dP/dt obtained from the nonlinear least squares program as our final determination, but augment the corresponding uncertainty to a more realistic value, ultimately arriving at the measurement of dP/dt = (5.5 {+-} 1.0) Multiplication-Sign 10{sup -15} s s{sup -1}. After correcting for proper motion, the evolutionary rate of cooling of ZZ Ceti is computed to be (3.3 {+-} 1.1) Multiplication-Sign 10{sup -15} s s{sup -1}. This value is consistent within uncertainties with the measurement of (4.19 {+-} 0.73) Multiplication-Sign 10{sup -15} s s{sup -1} for another similar pulsating DA white dwarf, G 117-B15A. Measuring the cooling rate of ZZ Ceti helps us refine our stellar structure and evolutionary models, as cooling depends mainly on the core composition and stellar mass. Calibrating white dwarf cooling curves with this measurement will reduce the theoretical uncertainties involved in white dwarf cosmochronometry. Should the 213.13 s period be trapped in the hydrogen envelope, then our determination of its drift rate compared to the expected evolutionary rate suggests an additional source of stellar cooling. Attributing the excess cooling to the emission of axions imposes a constraint on the mass of the hypothetical axion particle.

  19. In situ etch rate measurements of thin film combinatorial libraries

    SciTech Connect

    Perkins, J. D.; van Hest, M. F. A. M.; Teplin, C. W.; Dabney, M. S.; Ginley, D. S.

    2007-11-01

    We demonstrate the use of optical reflection mapping as an in situ characterization tool to evaluate the corrosion rate of compositionally graded thin film combinatorial libraries coated with a commercial glass etching paste. A multi-channel fiber-optically coupled CCD-array-based spectrometer was used to collect a series of reflectance maps from 300 to 1000 nm versus time. The thin film interference oscillations in the measured reflection spectra have been fitted to determine the film thickness as a function of time and thereby the etch rate. Application of this technique to an In–Mo–O composition spread library is presented as an example.

  20. Homogeneous nucleation rate measurements and the properties of critical clusters

    SciTech Connect

    Wyslouzil, Barbara E.; Strey, Reinhard; Wölk, Judith; Wilemski, Gerald; Kim, Yoojeong

    2009-10-06

    By combining a range of experimental techniques, quantitative nucleation rate measurements can now be made over {approx} 20 orders of magnitude. These rates can be used to directly test the predictions of nucleation theories or scaling laws. They can also provide direct information regarding the properties of the critical clusters - the first fragments of the new phase that are in unstable equilibrium with the supersaturated mother phase. This paper reviews recent progress in the field of vapor phase nucleation with a special focus on integrating the results from supersonic nozzle and nucleation pulse chamber studies.

  1. ZERO-VALENT IRON REMOVAL RATES OF AQUEOUS Cr(VI) MEASURED UNDER FLOW CONDITIONS

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-01

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). Dissolved Cr(VI) concentration, dissolved O2 concentration, and Eh data indicated that Cr(VI) removal from the aqueous phase was mass-transfer limited. All pseudo-first-order regression fits to the data were significant (P≤0.05), however, they did not capture many of the salient aspects of the data, including that the removal rate often decreased as contact time increased. As such, application of these rate coefficients to predict long-term Cr(VI) removal were compromised. The rate coefficients measured under flow conditions were comparable to those measured previously under batch conditions with significantly greater solution:solid ratios. Between the range of 20 and 100 wt-% Fe(0) in the column, there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry (0.2 M NaHCO3, distilled water, and a carbonate-dominated groundwater) had only marginal, if any, effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  2. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-06-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. These fuel consumption (FC) rates depend on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC rates are either modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC rates for various biomes and fuel categories to better understand FC rates and variability, and to provide a~database that can be used to constrain biogeochemical models with fire modules. We compiled in total 76 studies covering 10 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1), tropical forest (n = 19, FC = 126), temperate forest (n = 11, FC = 93), boreal forest (n = 16, FC = 39), pasture (n = 6, FC = 28), crop residue (n = 4, FC = 6.5), chaparral (n = 2, FC = 32), tropical peatland (n = 4, FC = 314), boreal peatland (n = 2, FC = 42), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only 3 measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences were found within the defined biomes: for example FC rates of temperate pine forests in the USA were 38% higher than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC rates, not only between biomes but also within biomes and fuel classes. This implies that care should be taken with using averaged values, and our comparison with FC rates from GFED3 indicates that also modeling studies have difficulty in representing the dynamics governing FC.

  3. Open charcoal chamber method for mass measurements of radon exhalation rate from soil surface.

    PubMed

    Tsapalov, Andrey; Kovler, Konstantin; Miklyaev, Peter

    2016-08-01

    Radon exhalation rate from the soil surface can serve as an important criterion in the evaluation of radon hazard of the land. Recently published international standard ISO 11665-7 (2012) is based on the accumulation of radon gas in a closed container. At the same time since 1998 in Russia, as a part of engineering and environmental studies for the construction, radon flux measurements are made using an open charcoal chamber for a sampling duration of 3-5 h. This method has a well-defined metrological justification and was tested in both favorable and unfavorable conditions. The article describes the characteristics of the method, as well as the means of sampling and measurement of the activity of radon absorbed. The results of the metrological study suggest that regardless of the sampling conditions (weather, the mechanism and rate of radon transport in the soil, soil properties and conditions), uncertainty of method does not exceed 20%, while the combined standard uncertainty of radon exhalation rate measured from the soil surface does not exceed 30%. The results of the daily measurements of radon exhalation rate from the soil surface at the experimental site during one year are reported.

  4. Probability Distributions of Measured Bedload Transport Rates with Application for Computing Sediment Rating Curves

    NASA Astrophysics Data System (ADS)

    Gaeuman, D. A.; Holt, C. R.

    2011-12-01

    Variability in fractional bedload transport rates derived from 948 bedload samples collected over a 7-year period at 4 locations along the same river were analyzed to assess the variability in measured transport rates under similar transport conditions. Sediment transport rating curves fit to the sample data show that transport characteristics can vary markedly between sampling locations. In addition, transport rates at the same locations usually exhibit clockwise bedload hysteresis between the rising and falling limbs of the annual flood hydrograph, even though long-term transport characteristics have remained comparatively stable over the period of record. Thus, the full set of sample data was separated into 8 groups, consisting of a rising and falling limb population at each of the 4 locations, for subsequent analysis. This separation was intended to reduce systematic variability caused by seasonal factors and position along the river while ensuring that each group contains a large population of measurements. Within each group, dimensionless fractional transport rates were computed and sorted into bins defined by the ratio of shear stress to reference shear stresses estimated from the sample data for each grain size fraction and sampling location. The mean and standard deviation transport rates computed for each shear stress bin were found to fit Chi-squared cumulative probability functions with means and degrees of freedom that increased with the shear stress ratio. Mean dimensionless transport rates ranged about 0.002 for bins with average shear stresses near the reference value to more than 0.12 for bins with average shear stresses exceeding twice the reference value. The standard deviations in dimensionless transport within bins ranged less than 0.6 times the mean value for large transport rates up to about twice the mean value for small transport rates. The relationship between the means and standard deviation transport rates and the shear stress ratio was

  5. Head rice rate measurement based on concave point matching

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Wu, Wei; Yang, Tianle; Liu, Tao; Chen, Wen; Chen, Chen; Li, Rui; Zhou, Tong; Sun, Chengming; Zhou, Yue; Li, Xinlu

    2017-01-01

    Head rice rate is an important factor affecting rice quality. In this study, an inflection point detection-based technology was applied to measure the head rice rate by combining a vibrator and a conveyor belt for bulk grain image acquisition. The edge center mode proportion method (ECMP) was applied for concave points matching in which concave matching and separation was performed with collaborative constraint conditions followed by rice length calculation with a minimum enclosing rectangle (MER) to identify the head rice. Finally, the head rice rate was calculated using the sum area of head rice to the overall coverage of rice. Results showed that bulk grain image acquisition can be realized with test equipment, and the accuracy rate of separation of both indica rice and japonica rice exceeded 95%. An increase in the number of rice did not significantly affect ECMP and MER. High accuracy can be ensured with MER to calculate head rice rate by narrowing down its relative error between real values less than 3%. The test results show that the method is reliable as a reference for head rice rate calculation studies.

  6. Head rice rate measurement based on concave point matching

    PubMed Central

    Yao, Yuan; Wu, Wei; Yang, Tianle; Liu, Tao; Chen, Wen; Chen, Chen; Li, Rui; Zhou, Tong; Sun, Chengming; Zhou, Yue; Li, Xinlu

    2017-01-01

    Head rice rate is an important factor affecting rice quality. In this study, an inflection point detection-based technology was applied to measure the head rice rate by combining a vibrator and a conveyor belt for bulk grain image acquisition. The edge center mode proportion method (ECMP) was applied for concave points matching in which concave matching and separation was performed with collaborative constraint conditions followed by rice length calculation with a minimum enclosing rectangle (MER) to identify the head rice. Finally, the head rice rate was calculated using the sum area of head rice to the overall coverage of rice. Results showed that bulk grain image acquisition can be realized with test equipment, and the accuracy rate of separation of both indica rice and japonica rice exceeded 95%. An increase in the number of rice did not significantly affect ECMP and MER. High accuracy can be ensured with MER to calculate head rice rate by narrowing down its relative error between real values less than 3%. The test results show that the method is reliable as a reference for head rice rate calculation studies. PMID:28128315

  7. Precision measurements of positronium decay rate and energy level

    SciTech Connect

    Asai, S.; Kataoka, Y.; Kobayashi, T.; Namba, T.; Suehara, T.; Akimoto, G.; Ishida, A.; Hashimoto, M. M.; Saito, H.; Idehara, T.; Yoshida, M.

    2008-08-08

    Positronium is an ideal system for the research of the bound state QED. New precise measurement of orthopositronium decay rate has been performed with an accuracy of 150 ppm, and the result combined with the last three is 7.0401{+-}0.0007 {mu}s{sup -1}. It is the first result to validate the 2nd order correction. The Hyper Fine Splitting of positronium is sensitive to the higher order corrections of the QED prediction and also to the new physics beyond Standard Model via the quantum oscillation into virtual photon. The discrepancy of 3.5{sigma} is found recently between the measured values and the QED prediction (O({alpha}{sup 3})). It might be due to the contribution of the new physics or the systematic problems in the previous measurements: (non-thermalized Ps and non-uniformity of the magnetic field). We propose new methods to measure HFS precisely without the these uncertainties.

  8. Seasonal variation of meteorological variables and recent surface ablation / accumulation rates on Davies Dome and Whisky Glacier, James Ross Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Láska, K.; Nývlt, D.; Engel, Z.; Budík, L.

    2012-04-01

    In this study, surface mass balance data of two glaciers on James Ross Island, Antarctica, and its spatial and temporal variations are evaluated using snow ablation stakes, ground-penetrating radar, and dGPS measurements. The investigated glaciers are located on the Ulu Peninsula, northern part of James Ross Island. Davies Dome is an ice dome, which originates on the surface of a flat volcanic mesa at elevations >400 m a.s.l. and terminates with a single 700 m wide outlet in the Whisky Bay. Davies Dome has an area of ~6.5 km2 and lies in the altitude range of 0-514 m a.s.l. Whisky Glacier is a cold-based land-terminating valley glacier surrounded by an extensive moraine ridges made of debris-covered ice. The glacier has an area of ~2.4 km2 and lies in the altitude range of 215-520 m a.s.l. Within several summer austral summers, extensive field programme were carried out on both glaciers including the operation of two automatic weather stations, field mapping and mass balance measurements. Each station was equipped with albedometer CM7B (Kipp-Zonen, Netherlands), air temperature and humidity sensor EMS33 (EMS, Czech Republic), propeller anemometer 05103 (Young, USA), and snow depth sensors (Judd, USA). In the period 2009-2011, high seasonal and interdiurnal variability of incoming solar radiation and near-surface air temperature was found as a result of changes in the circulation patterns and synoptic-scale weather systems moving in the Circumpolar Trough. High ablation and accumulation rates were recorded mainly in the spring and summer seasons (October-February), while negligible changes were found in winter (May-September). The effects of positive degree-day temperatures on the surface ablation rates were examined using a linear regression model. In this approach, near-surface air temperature maps on the glacier surfaces were derived from digital elevation model according to actual temperature lapse rates. Mass balance investigations started in 2006 on Davies

  9. Eating disorder symptom severity scale: a new clinician rated measure.

    PubMed

    Henderson, Katherine A; Buchholz, Annick; Perkins, Julie; Norwood, Sarah; Obeid, Nicole; Spettigue, Wendy; Feder, Stephen

    2010-01-01

    This study describes the development and validation of the clinician-rated Eating Disorder Symptom Severity Scale (EDS(3)), created to address a gap in measurement options for youth with eating disorders. The EDS(3) is modeled on the Childhood Severity and Acuity of Psychiatric Illness Scales (Lyons, J. S, 1998). Factor analysis revealed a 5-factor solution and accounted for 78% of the variance, and internal consistency within the subscales was good (Cronbach alphas: 0.69 to 0.93). The EDS(3) is a valid and reliable measure designed for clinicians to help assess the severity of a youth's eating disorder and to facilitate outcomes research.

  10. Disintegration rate measurement of a 192Ir solution.

    PubMed

    Fonseca, K A; Koskinas, M F; Dias, M S

    2001-01-01

    The disintegration rate of 192Ir has been measured using the 4pibeta-gamma coincidence technique. This radionuclide decays by electron capture (EC) and beta-emission. Since the EC contribution is low (4.5%), it has been corrected using decay scheme data taken from the literature. This measurement has been performed in collaboration with the Laboratório Nacional de Metrologia das Radiações Ionizantes (IRDDM), in Rio de Janeiro. The results, which were obtained independently and employed different techniques, are compared with the Systéme International Reference (SIR) maintained at the Bureau International des Poids et Mesures.

  11. Reaction Rate Measurements at the National Criticality Experiments Research Center

    NASA Astrophysics Data System (ADS)

    Bredeweg, T. A.; Bounds, J. A.; Brooks, G. H., Jr.; Favorite, J. A.; Goda, J. M.; Hayes, D. K.; Jackman, K. R.; Little, R. C.; Macinnes, M. R.; Myers, W. L.; Oldham, W. J.; Rundberg, R. S.; Sanchez, R. G.; Schake, A. R.; White, M. C.; Wilkerson, C. W., Jr.

    2014-09-01

    With the resumption of regular operations of the Los Alamos Critical Assemblies at the National Criticality Experiments Research Center (NCERC), located at the Nevada National Security Site, we have embarked upon a series of campaigns to restore the capability to perform integral reaction rate and fission product yield measurements using historical radiochemical methods. This talk will present an overview of the current and future experimental plans, including results from our experimental campaigns on the Comet/Zeus and Flattop assemblies.

  12. Measurement of Multiple Blade Rate Unsteady Propeller Forces

    DTIC Science & Technology

    1990-05-01

    Report I 0 Measurement of Multiple Blade Rate Unsteady Propeller Forces _ by Stuart D. Jessup DTIC SELECTE JUN07 1990 00 U,);i -,,I-ll lll ll mml~ CODE...blade rat and multiple axia wake inflow harmonics. The axial wake distributions weret meaured using a Piot tube. Unsteady propeller bearing thrust and...diameter EAR Propeller expanded area ratio f Maximum camber of section J Advance coefficient, Vvm/nD K Integer multiple of blade number KT Thrust

  13. Serum nitric oxide metabolite as a biomarker of visceral fat accumulation: Clinical significance of measurement for nitrate/nitrite

    PubMed Central

    Fujita, Koji; Wada, Koichiro; Nozaki, Yuichi; Yoneda, Masato; Endo, Hiroki; Takahashi, Hirokazu; Kirikoshi, Hiroyuki; Inamori, Masahiko; Kobayashi, Noritoshi; Kubota, Kensuke; Saito, Satoru; Nakajima, Atsushi

    2011-01-01

    Summary Background A visceral fat area of more than 100 cm2 as measured by computed tomography (CT) at the umbilical level has been included as a criterion for obesity in all the proposed criteria for metabolic syndrome. However, CT cannot be used frequently because of radiation exposure. We evaluated the usefulness of measurement of the serum levels of nitric oxide (NO), instead of CT and the waist circumference, as a marker of abdominal visceral fat accumulation. Material/Methods The study was carried out in 80 subjects. The serum levels of NO metabolites (nitrate/nitrite) were measured using the Griess reagent. Results Simple and multiple regression analysis revealed that the serum levels of NO metabolites showed the greatest degree of correlation with the visceral fat area (r=0.743, p<0.0001), and corresponded to a visceral fat area of 100 cm2, as determined using the ROC curve, was 21.0 μmol/ml (sensitivity 88%, specificity 82%); this method was more sensitive than the waist circumference for evaluation of the visceral fat accumulation. Conclusions Measurement of the serum levels of NO metabolites may be a simple, safe, convenient and reliable method for the evaluation of visceral fat accumulation in clinical diagnostic screening. PMID:21358598

  14. Development of a portable photosynthesis rate measurement device

    NASA Astrophysics Data System (ADS)

    Wang, Junsheng; Xing, Da; Xu, Wenhai

    2006-09-01

    Photosynthesis is a very important chemical reaction in the plant, and its measurement plays critical role in the agriculture production and science research of plant. Delayed fluorescence (DF) in plants is an intrinsic label of efficiency of charge separation at P680 in photosystem II (PS II). In this paper, a portable photosynthesis rate measurement device by means of DF is proposed. It can achieve DF of plant with high sensitivity and signal-to-noise ratio basing on ultra-weak luminescence detection technique, and get photosynthesis rate by the corresponding relation between DF and photosynthesis rate. The device has its illumination power and can obtain all-weather measurement with less interference of the environment. Locale live survey can be realized by hermetic darkroom design and battery power supply. The system carries out data acquisition and processing by single-chip microcomputer control. The results show that this instrument has a lot of values such as low cost, high accuracy and good reliability and convenience.

  15. Patient-rated versus proxy-rated cognitive and functional measures in older adults

    PubMed Central

    Howland, Molly; Allan, Kevin C; Carlton, Caitlin E; Tatsuoka, Curtis; Smyth, Kathleen A; Sajatovic, Martha

    2017-01-01

    Objectives Patients with cognitive impairment may have difficulty reporting their functional and cognitive abilities, which are important clinical outcomes. Health care proxies may be able to corroborate patient self-reports. Several studies reported discrepancy between patient and proxy ratings, though the literature is sparse on changes over time of these ratings. Our goals in this 12-month study were to compare patient and proxy reports on functioning, cognition, and everyday executive function, and to further elucidate correlates of patient–proxy discrepancy. Methods This was a prospective cohort study of individuals older than 70 years who ranged from having no cognitive impairment to having moderate dementia who had a proxy available to complete instruments at baseline (N=76). Measurements included Alzheimer’s Disease Cooperative Study–Activities of Daily Living Inventory (ADCS-ADLI), Neuro-QOL Executive Function, PROMIS Applied Cognition (PROMIS-Cog), Mini-Mental State Examination (MMSE), and Geriatric Depression Scale. Results Patient- and proxy-rated ADCS-ADLI were correlated at baseline and at 1-year follow-up. Patient and proxy ratings were discrepant on Neuro-QOL Executive Function and PROMIS-Cog. Greater patient–proxy discrepancy on PROMIS-Cog was associated with younger age and less depression, and greater patient–proxy discrepancy on Neuro-QOL Executive Function was associated with less depression and worse cognitive impairment. Patient–proxy discrepancy increased over time for everyday executive function. Changes in proxy-rated but not patient-rated ADCS-ADLI correlated with MMSE changes. Conclusion Patients and proxies generally agree in reporting on activities of daily living. Patient and proxy reports differ in their respective evaluation of cognitive functioning and everyday executive function. Ratings from both sources may be preferred for these two domains, though studies using gold standard measures are necessary. It is important

  16. Cosmogenic {sup 36}Cl accumulation in unstable landforms 2. Simulations and measurements on eroding moraines

    SciTech Connect

    Zreda, M.G.; Phillips, F.M.; Elmore, D.

    1994-11-01

    Cosmogenic {sup 36}Cl ages of boulders from late Pleistocene moraines in Bishop Creek, Sierra Nevada, California, provided valuable details about {sup 36}Cl surface exposure dating and the nature of post depositional processes that modify glacial landforms. The natural variability of the apparent {sup 36}Cl ages among morainal boulders is due to soil erosion and gradual exposure of boulders at the surface. Two mechanisms are responsible for the resulting distributions of the apparent {sup 36}Cl ages. Variability of the initial burial depth among boulders and variability in the chemical composition of boulders from the same depth both result in different {sup 36}Cl ages due to the dependence of the depth production profile on the boulder chemistry. The authors measured cosmogenic {sup 36}Cl in boulders from a late Pleistocene moraine. The distribution of the calculated apparent ages allowed them to calculate the true age of 85 kyr and the erosion rate of 570 g cm{sup -2}. These results are in excellent agreement with independently estimated values of 87 kyr and 600 g cm{sup -2} for the age and erosion depth, respectively. These results indicate that the model satisfactorily simulates effects of erosion processes and can thus aid in surface exposure dating of eroding landforms.

  17. Simultaneous measurement of bacterial flagellar rotation rate and swimming speed.

    PubMed Central

    Magariyama, Y; Sugiyama, S; Muramoto, K; Kawagishi, I; Imae, Y; Kudo, S

    1995-01-01

    Swimming speeds and flagellar rotation rates of individual free-swimming Vibrio alginolyticus cells were measured simultaneously by laser dark-field microscopy at 25, 30, and 35 degrees C. A roughly linear relation between swimming speed and flagellar rotation rate was observed. The ratio of swimming speed to flagellar rotation rate was 0.113 microns, which indicated that a cell progressed by 7% of pitch of flagellar helix during one flagellar rotation. At each temperature, however, swimming speed had a tendency to saturate at high flagellar rotation rate. That is, the cell with a faster-rotating flagellum did not always swim faster. To analyze the bacterial motion, we proposed a model in which the torque characteristics of the flagellar motor were considered. The model could be analytically solved, and it qualitatively explained the experimental results. The discrepancy between the experimental and the calculated ratios of swimming speed to flagellar rotation rate was about 20%. The apparent saturation in swimming speed was considered to be caused by shorter flagella that rotated faster but produced less propelling force. Images FIGURE 1 FIGURE 4 PMID:8580359

  18. Measurements of Aperture Averaging on Bit-Error-Rate

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.; Andrews, Larry C.; Phillips, Ronald L.; Nelson, Richard A.; Ferrell, Bobby A.; Borbath, Michael R.; Galus, Darren J.; Chin, Peter G.; Harris, William G.; Marin, Jose A.; Burdge, Geoffrey L.; Wayne, David; Pescatore, Robert

    2005-01-01

    We report on measurements made at the Shuttle Landing Facility (SLF) runway at Kennedy Space Center of receiver aperture averaging effects on a propagating optical Gaussian beam wave over a propagation path of 1,000 in. A commercially available instrument with both transmit and receive apertures was used to transmit a modulated laser beam operating at 1550 nm through a transmit aperture of 2.54 cm. An identical model of the same instrument was used as a receiver with a single aperture that was varied in size up to 20 cm to measure the effect of receiver aperture averaging on Bit Error Rate. Simultaneous measurements were also made with a scintillometer instrument and local weather station instruments to characterize atmospheric conditions along the propagation path during the experiments.

  19. A 9000 year perspective on carbon accumulation rates under changing hydro-climate and vegetation conditions in a mountain peatland, northern Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Feurdean, Angelica; Panait, Andrei; Gałka, Mariusz; Diaconu, Andrei; Hutchinson, Simon; Mulch, Andreas; Tantau, Ioan; Hickler, Thomas

    2016-04-01

    Peatlands, in particular ombrogenous bogs, which entirely depend on water from precipitation, are sensitive to changes in the balance between precipitation and evapotranspiration; and therefore highly suitable for hydro-climatological reconstruction. Peatlands also represent a large carbon pool in the terrestrial biosphere. However, little is known about the C sequestration processes in mountain peatlands under various competing drivers of change (climate, vegetation, fire). We applied a multi-proxy approach (bulk density, loss on ignition, total organic carbon, testate amoebae, δ13C in Sphagnum, plant macrofossils, pollen and charcoal) to a peat sequence from a mountain ombrogenous bog (Tǎul Muced) to explore how changes in hydro-climate conditions, peat plant composition and fire have affected long-term physical peat properties and the rate of carbon accumulation over the last 9000 years. Carbon accumulation at this site ranged from 7 to 105 g C cm2 yr1 (mean 23 ± 14 g C cm2 yr_1). We found that high moisture availability (P-E) as inferred from testate amoebae and δ13C values in Sphagnum increased the carbon sink capacity of peatland. The strength of the relationship between the rate of carbon accumulation and climate appears particularly evident over the last millennium when high C accumulation rates correlated with the warm and wet conditions of the Medieval Climate Anomaly and lower C accumulation rates with the dry conditions of the Little Ice Age. We also found a significant positive correlation between the rate of C accumulation and changes in vegetation; rates were lowest (17 g C cm2 yr_1), during periods of mixed Sphagnum (primarily S. magellanicum and S. angustifolium) and vascular plant (Cyperaceae, Eriophorum vaginatum) growth and increased (31 g C cm2 yr_1) during the accumulation of Sphagnum peat, regardless the dominant Sphagnum species. We did not find indication of peatland fire during the investigated interval. Our study represents one of the

  20. Measurements of in situ chemical ozone (oxidant) production rates

    NASA Astrophysics Data System (ADS)

    Huang, Hao; Faloon, Kate; Najera, Juan; Bloss, William

    2013-04-01

    Tropospheric ozone is a major air pollutant, harmful to human health, agricultural crops and vegetation, the main precursor to the atmospheric oxidants which initiate the degradation of most reactive gases emitted to the atmosphere, and an important greenhouse gas in its own right. The capacity to understand and predict tropospheric ozone levels is a key goal for atmospheric science - but one which is challenging, as ozone is formed in the atmosphere from the complex oxidation of VOCs in the presence of NOx and sunlight, on a timescale such that in situ chemical processes, deposition and transport all affect ozone levels. Known uncertainties in emissions, chemistry, dynamics and deposition affect the accuracy of predictions of current and future ozone levels, and hinder development of optimal air quality policies to mitigate against ozone exposure. Recently new approaches to directly measure the local chemical ozone production rate, bypassing the many uncertainties in emissions and chemical schemes, have been developed (Cazorla & Brune, AMT 2010). Here, we describe the development of an analogous Ozone Production Rate (OPR) approach: Air is sampled into parallel reactors, within which ozone formation either occurs as in the ambient atmosphere, or is suppressed. Comparisons of ozone levels exiting a pair of such reactors determines the net chemical oxidant production rate, after correction for perturbation of the NOx-O3 photochemical steady state, and when operated under conditions such that wall effects are minimised. We report preliminary measurements of local chemical ozone production made during the UK NERC ClearfLo (Clean Air for London) campaign at an urban background location in London in January and July 2012. The OPR system was used to measure the local chemical oxidant formation rate, which is compared with observed trends in O3 and NOx and the prevailing meteorology, and with the predictions of a detailed zero-dimensional atmospheric chemistry model

  1. Temperature-fluctuation-sensitive accumulative effect of the phase measurement errors in low-coherence interferometry in characterizing arrayed waveguide gratings.

    PubMed

    Zhao, Changyun; Wei, Bing; Yang, Longzhi; Wang, Gencheng; Wang, Yuehai; Jiang, Xiaoqing; Li, Yubo; Yang, Jianyi

    2015-09-20

    We investigate the accumulative effect of the phase measurement errors in characterizing optical multipath components by low-coherence interferometry. The accumulative effect is caused by the fluctuation of the environment temperature, which leads to the variation of the refractive index of the device under test. The resulting phase measurement errors accumulate with the increasing of the phase difference between the two interferometer arms. Our experiments were carried out to demonstrate that the accumulative effect is still obvious even though the thermo-optical coefficient of the device under test is quite small. Shortening the measurement time to reduce the fluctuation of the environment temperature can effectively restrain the accumulative effect. The experiments show that when the scanning speed increases to 4.8 mm/s, the slope of the phase measurement errors decreases to 5.52×10(-8), which means the accumulative effect can be ignored.

  2. Combining Disparate Measures of Metabolic Rate During Simulated Spacewalks

    NASA Technical Reports Server (NTRS)

    Feiveson, Alan H.; Kuznetz, Larry; Nguyen, Dan

    2009-01-01

    Scientists from NASA's Extravehicular Activities (EVA) Physiology Systems and Performance Project help design space suits for future missions, during which astronauts are expected to perform EVA activities on the Lunar or Martian surface. During an EVA, an astronaut s integrated metabolic rate is used to predict how much longer the activity can continue and still provide a safe margin of remaining consumables. For EVAs in the Apollo era, NASA physicians monitored live data feeds of heart rate, O2 consumption, and liquid cooled garment (LCG) temperatures, which were subjectively combined or compared to produce an estimate of metabolic rate. But these multiple data feeds sometimes provided conflicting estimates of metabolic rate, making real-time calculations of remaining time difficult for physician/monitors. Currently, designs planned for the Constellation Program EVAs utilize an automated, but largely heuristic methodology for incorporating the above three measurements, plus an additional one - CO2 production, ignoring data that appears in conflict; however a more rigorous model-based approach is desirable. In this study, we show how principal axis factor analysis, in combination with OLS regression and LOWESS smoothing can be used to estimate metabolic rate as a data-driven weighted average of heart rate, O2 consumption, LCG temperature data, and CO2 production. Preliminary results suggest less sensitivity to occasional spikes in observed data feeds, and reasonable within-subject reproducibility when applied to subsequent tasks. These methods do not require physician monitoring and as such can be automated in the electronic components of future space suits. With additional validation, our models show promise for increasing astronaut safety, while reducing the need for and potential errors associated with human monitoring of multiple systems.

  3. Elucidating effects of atmospheric deposition and peat decomposition processes on mercury accumulation rates in a northern Minnesota peatland over last 10,000 cal years

    NASA Astrophysics Data System (ADS)

    Nater, E. A.; Furman, O.; Toner, B. M.; Sebestyen, S. D.; Tfaily, M. M.; Chanton, J.; Fissore, C.; McFarlane, K. J.; Hanson, P. J.; Iversen, C. M.; Kolka, R. K.

    2014-12-01

    Climate change has the potential to affect mercury (Hg), sulfur (S) and carbon (C) stores and cycling in northern peatland ecosystems (NPEs). SPRUCE (Spruce and Peatland Responses Under Climate and Environmental change) is an interdisciplinary study of the effects of elevated temperature and CO2 enrichment on NPEs. Peat cores (0-3.0 m) were collected from 16 large plots located on the S1 peatland (an ombrotrophic bog treed with Picea mariana and Larix laricina) in August, 2012 for baseline characterization before the experiment begins. Peat samples were analyzed at depth increments for total Hg, bulk density, humification indices, and elemental composition. Net Hg accumulation rates over the last 10,000 years were derived from Hg concentrations and peat accumulation rates based on peat depth chronology established using 14C and 13C dating of peat cores. Historic Hg deposition rates are being modeled from pre-industrial deposition rates in S1 scaled by regional lake sediment records. Effects of peatland processes and factors (hydrology, decomposition, redox chemistry, vegetative changes, microtopography) on the biogeochemistry of Hg, S, and other elements are being assessed by comparing observed elemental depth profiles with accumulation profiles predicted solely from atmospheric deposition. We are using principal component analyses and cluster analyses to elucidate relationships between humification indices, peat physical properties, and inorganic and organic geochemistry data to interpret the main processes controlling net Hg accumulation and elemental concentrations in surface and subsurface peat layers. These findings are critical to predicting how climate change will affect future accumulation of Hg as well as existing Hg stores in NPE, and for providing reference baselines for SPRUCE future investigations.

  4. Predominant anthropogenic sources and rates of atmospheric mercury accumulation in southern Ontario recorded by peat cores from three bogs: comparison with natural "background" values (past 8000 years).

    PubMed

    Givelet, Nicolas; Roos-Barraclough, Fiona; Shotyk, William

    2003-12-01

    Peat cores from three bogs in southern Ontario provide a complete, quantitative record of net rates of atmospheric Hg accumulation since pre-industrial times. For comparison with modern values, a peat core extending back 8000 years was used to quantify the natural variations in Hg fluxes for this region, and their dependence on climatic change and land use history. The net mercury accumulation rates were separated into "natural" and "excess" components by comparing the Hg/Br ratios of modern samples with the long-term, pre-anthropogenic average Hg/Br. The average background mercury accumulation rate during the pre-anthropogenic period (from 5700 years BC to 1470 AD) was 1.4 +/- 1.0 microg m(-2) per year (n = 197). The beginning of Hg contamination from anthropogenic sources dates from AD 1475 at the Luther Bog, corresponding to biomass burning for agricultural activities by Native North Americans. During the late 17th and 18th centuries, deposition of anthropogenic Hg was at least equal to that of Hg from natural sources. Anthropogenic inputs of Hg to the bogs have dominated continuously since the beginning of the 19th century. The maximum Hg accumulation rates decrease in the order Sifton Bog, in the City of London, Ontario (141 microg Hg m(-2) per year), Luther Bog in an agricultural region (89 microg Hg m(-2) per year), and Spruce Bog which is in a comparatively remote, forested region (54 microg Hg m(-2) per year). Accurate age dating of recent peat samples using the bomb pulse curve of 14C shows that the maximum rate of atmospheric Hg accumulation occurred during AD 1956 and 1959 at all sites. In these (modern) samples, the Hg concentration profiles resemble those of Pb, an element which is known to be immobile in peat bogs. The correlation between these two metals, together with sulfur, suggests that the predominant anthropogenic source of Hg (and Pb) was coal burning. While Hg accumulation rates have gone into strong decline since the late 1950's, Hg

  5. Direct measurement of densifcation rates in polar snow and the implications for altimetry

    NASA Astrophysics Data System (ADS)

    Morris, E.; Wingham, D. J.

    2012-04-01

    As part of the cal/val experiments for the CryoSat radar altimeter, density profiles in the upper 10-14 m of snow have been measured along a 500 km traverse across the Greenland Ice Sheet, using a neutron scattering technique. Repeat measurements, over periods ranging from a few days to 5 years allow strainrates and densification rates to be determined as a function of depth. We show that, as expected, the strainrate decreases as the ratio of pore space to ice content decreases. Very large strain rates are observed in the surface layer of snow over summer periods. However, for multi-year snow, once the effect of porosity has been removed, the remaining mean response is constant with depth, that is the effect of increasing overburden pressure is counteracted by increasing strength of the material. The mean strainrate for multi-year snow at a given site is related to the mean annual accumulation rate and mean annual temperature by an expression consistent with the Herron and Langway equation(Herron and Langway, 1980) for first-stage densification. However, there are fluctuations in strainrate associated with the annual layering which indicate that fine and coarse-grained snow have differing strengths. We show that the temperature-dependent process equations proposed by Alley (1987) and Arthern et al. (2010) do not hold, and suggest an alternative relation based on the temperature-history of the snow. Finally we calculate the effect of our observed short-term fluctuations in compaction and accumulation on the elevation ofthe snow surface and discuss the contribution of densification to uncertainty in satellite measurements of elevation trends.

  6. Variations in the accumulation, localization and rate of metabolization of selenium in mature Zea mays plants supplied with selenite or selenate.

    PubMed

    Longchamp, Mélanie; Castrec-Rouelle, Maryse; Biron, Philippe; Bariac, Thierry

    2015-09-01

    Quantification of selenium bioavailability from foods is a key challenge following the discovery of the antioxidant role of this micronutrient in human health. This study presents the uptake, accumulation and rate of metabolization in mature Zea mays plants grown in hydroponic solution supplemented with selenate or selenite. Selenium content was lower in plants supplemented with selenate and accumulated mainly in the leaves compared with selenite-treated plants where the selenium was retained in the roots. Selenite-treated grains accumulated more selenium. Selenate was metabolized less than selenite in whole plants, but in grains selenium was present exclusively as organic selenium compounds. For humans, the bioavailability of organic selenium was evaluated at 90% compared with only 50% for inorganic forms. Our results show that the potential for selenium bioavailability is increased with selenite treatment.

  7. Remote Measurements of Heart and Respiration Rates for Telemedicine

    PubMed Central

    Qian, Yi; Tsien, Joe Z.

    2013-01-01

    Non-contact and low-cost measurements of heart and respiration rates are highly desirable for telemedicine. Here, we describe a novel technique to extract blood volume pulse and respiratory wave from a single channel images captured by a video camera for both day and night conditions. The principle of our technique is to uncover the temporal dynamics of heart beat and breathing rate through delay-coordinate transformation and independent component analysis-based deconstruction of the single channel images. Our method further achieves robust elimination of false positives via applying ratio-variation probability distributions filtering approaches. Moreover, it enables a much needed low-cost means for preventing sudden infant death syndrome in new born infants and detecting stroke and heart attack in elderly population in home environments. This noncontact-based method can also be applied to a variety of animal model organisms for biomedical research. PMID:24115996

  8. The stratigraphic filter and bias in measurement of geologic rates

    USGS Publications Warehouse

    Schumer, Rina; Jerolmack, Douglas; McElroy, Brandon

    2011-01-01

    Erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power-law dependence on measurement interval. This dependence can result from a power-law distribution of stratigraphic hiatuses. By representing the stratigraphic filter as a stochastic process called a reverse ascending ladder, we describe a likely origin of power-law hiatuses, and thus, rate scaling. While power-law hiatuses in certain environments can be a direct result of power-law periods of stasis (no deposition or erosion), they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift. Autocorrelation in fluctuations can make hiatuses more or less heavy-tailed, but still exhibit power-law characteristics. In addition we show that by passing stratigraphic data backward through the filter, certain statistics of surface kinematics from their formative environments can be inferred.

  9. The stratigraphic filter and bias in measurement of geologic rates

    USGS Publications Warehouse

    Schumer, R.; Jerolmack, D.; McElroy, B.

    2011-01-01

    Erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power-law dependence on measurement interval. This dependence can result from a power-law distribution of stratigraphic hiatuses. By representing the stratigraphic filter as a stochastic process called a reverse ascending ladder, we describe a likely origin of power-law hiatuses, and thus, rate scaling. While power-law hiatuses in certain environments can be a direct result of power-law periods of stasis (no deposition or erosion), they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift. Autocorrelation in fluctuations can make hiatuses more or less heavy-tailed, but still exhibit power-law characteristics. In addition we show that by passing stratigraphic data backward through the filter, certain statistics of surface kinematics from their formative environments can be inferred. Copyright ?? 2011 by the American Geophysical Union.

  10. Seabed measurements of modern corrosion rates on the Florida escarpment

    USGS Publications Warehouse

    Paull, C.K.; Commeau, R.F.; Curray, Joseph R.; Neumann, A.C.

    1991-01-01

    A mooring containing diverse carbonate and anhydrite substrates was exposed to bottom waters for 9 months at the base of the Florida Escarpment to determine the influence of dissolution on the development of this continental margin. Weight loss was measured on all samples. Etching, pitting, and loss of the original framework components were observed on substrates with known characteristics. Extrapolations of modern dissolution rates predict only about 1.6 meters of corrosion per million years. However, more rapid anhydrite dissolution, up to 1 km per million years, would cause exposed anhydrite beds to undercut and destabilize intercalated limestones. ?? 1991 Springer-Verlag New York Inc.

  11. Viscometer for low frequency, low shear rate measurements

    NASA Technical Reports Server (NTRS)

    Berg, R. F.; Moldover, M. R.

    1986-01-01

    A computer-controlled torsion-oscillator viscometer with low 0.5 Hz frequency and very low 0.05/s shear rate is designed to precisely study shear-sensitive fluids such as microemulsions, gels, polymer solutions and melts, colloidal solutions undergoing coagulation, and liquid mixtures near critical points. The viscosities are obtained from measurements of the logarithmic decrement of an underdriven oscillator. The viscometer is found to have a resolution of 0.2 percent when used with liquid samples and a resolution of 0.4 percent when used with a dense gaseous sample. The design is compatible with submillikelvin temperature control.

  12. Prospects for DNA methods to measure human heritable mutation rates

    SciTech Connect

    Mendelsohn, M.L.

    1985-06-14

    A workshop cosponsored by ICPEMC and the US Department of Energy was held in Alta, Utah, December 9-13, 1984 to examine the extent to which DNA-oriented methods might provide new approaches to the important but intractable problem of measuring mutation rates in control and exposed human populations. The workshop identified and analyzed six DNA methods for detection of human heritable mutation, including several created at the meeting, and concluded that none of the methods combine sufficient feasibility and efficiency to be recommended for general application. 8 refs.

  13. Dynamic flux chamber measurements of hydrogen sulfide emission rate from a quiescent surface--A computational evaluation.

    PubMed

    Prata, Ademir A; Santos, Jane M; Beghi, Sandra P; Fernandes, Isabella F; Vom Marttens, Lya L C; Pereira Neto, Leovegildo I; Martins, Ramon S; Reis, Neyval C; Stuetz, Richard M

    2016-03-01

    Enclosure devices have been studied and used for research purposes and practical applications in order to measure the emission rate of odorous pollutants from quiescent liquid surfaces to atmosphere. However, important questions remain about the interference of these measuring devices on the actual emission rate. The main concern regarding the use of a flux chamber is the fact that odorous compounds can accumulate into the chamber and yield gas-phase concentration increase inside the equipment, which causes a reduction of the emission rate during the measurement and thus gives an inaccurate local emission rate. Furthermore, the fluid flow inside the chamber does not reproduce the atmospheric boundary layer flow. This study applied the Computational Fluid Dynamics (CFD) technique in order to investigate the influence of the fluid flow features inside a flux chamber on the measured hydrogen sulfide emission rate at quiescent liquid surfaces. The flux chamber design and operational conditions are those supported by the United States Environmental Protection Agency (US EPA). The results show that the US EPA flux chamber presents a fairly well mixed air phase. However, a trend to stagnation and hydrogen sulfide accumulation near chamber walls was detected in the computational simulation, which also indicated that the positioning of the sampling tube in relation to the inlet orifices may lead to deviations in the measurement results. CFD results showed that the wall shear and concentration gradients spatially vary at the gas-liquid interface, and friction velocity inside the chamber does not match typical values of atmospheric flow.

  14. Human amyloid-beta synthesis and clearance rates as measured in cerebrospinal fluid in vivo.

    PubMed

    Bateman, Randall J; Munsell, Ling Y; Morris, John C; Swarm, Robert; Yarasheski, Kevin E; Holtzman, David M

    2006-07-01

    Certain disease states are characterized by disturbances in production, accumulation or clearance of protein. In Alzheimer disease, accumulation of amyloid-beta (Abeta) in the brain and disease-causing mutations in amyloid precursor protein or in enzymes that produce Abeta indicate dysregulation of production or clearance of Abeta. Whether dysregulation of Abeta synthesis or clearance causes the most common form of Alzheimer disease (sporadic, >99% of cases), however, is not known. Here, we describe a method to determine the production and clearance rates of proteins within the human central nervous system (CNS). We report the first measurements of the fractional production and clearance rates of Abeta in vivo in the human CNS to be 7.6% per hour and 8.3% per hour, respectively. This method may be used to search for novel biomarkers of disease, to assess underlying differences in protein metabolism that contribute to disease and to evaluate treatments in terms of their pharmacodynamic effects on proposed disease-causing pathways.

  15. Germline mutation rates and the long-term phenotypic effects of mutation accumulation in wild-type laboratory mice and mutator mice

    PubMed Central

    Uchimura, Arikuni; Higuchi, Mayumi; Minakuchi, Yohei; Ohno, Mizuki; Toyoda, Atsushi; Fujiyama, Asao; Miura, Ikuo; Wakana, Shigeharu; Nishino, Jo; Yagi, Takeshi

    2015-01-01

    The germline mutation rate is an important parameter that affects the amount of genetic variation and the rate of evolution. However, neither the rate of germline mutations in laboratory mice nor the biological significance of the mutation rate in mammalian populations is clear. Here we studied genome-wide mutation rates and the long-term effects of mutation accumulation on phenotype in more than 20 generations of wild-type C57BL/6 mice and mutator mice, which have high DNA replication error rates. We estimated the base-substitution mutation rate to be 5.4 × 10−9 (95% confidence interval = 4.6 × 10−9–6.5 × 10−9) per nucleotide per generation in C57BL/6 laboratory mice, about half the rate reported in humans. The mutation rate in mutator mice was 17 times that in wild-type mice. Abnormal phenotypes were 4.1-fold more frequent in the mutator lines than in the wild-type lines. After several generations, the mutator mice reproduced at substantially lower rates than the controls, exhibiting low pregnancy rates, lower survival rates, and smaller litter sizes, and many of the breeding lines died out. These results provide fundamental information about mouse genetics and reveal the impact of germline mutation rates on phenotypes in a mammalian population. PMID:26129709

  16. Germline mutation rates and the long-term phenotypic effects of mutation accumulation in wild-type laboratory mice and mutator mice.

    PubMed

    Uchimura, Arikuni; Higuchi, Mayumi; Minakuchi, Yohei; Ohno, Mizuki; Toyoda, Atsushi; Fujiyama, Asao; Miura, Ikuo; Wakana, Shigeharu; Nishino, Jo; Yagi, Takeshi

    2015-08-01

    The germline mutation rate is an important parameter that affects the amount of genetic variation and the rate of evolution. However, neither the rate of germline mutations in laboratory mice nor the biological significance of the mutation rate in mammalian populations is clear. Here we studied genome-wide mutation rates and the long-term effects of mutation accumulation on phenotype in more than 20 generations of wild-type C57BL/6 mice and mutator mice, which have high DNA replication error rates. We estimated the base-substitution mutation rate to be 5.4 × 10(-9) (95% confidence interval = 4.6 × 10(-9)-6.5 × 10(-9)) per nucleotide per generation in C57BL/6 laboratory mice, about half the rate reported in humans. The mutation rate in mutator mice was 17 times that in wild-type mice. Abnormal phenotypes were 4.1-fold more frequent in the mutator lines than in the wild-type lines. After several generations, the mutator mice reproduced at substantially lower rates than the controls, exhibiting low pregnancy rates, lower survival rates, and smaller litter sizes, and many of the breeding lines died out. These results provide fundamental information about mouse genetics and reveal the impact of germline mutation rates on phenotypes in a mammalian population.

  17. Measurement of the Rate of Stellar Tidal Disruption Flares

    NASA Astrophysics Data System (ADS)

    van Velzen, Sjoert; Farrar, Glennys R.

    2014-09-01

    We report an observational estimate of the rate of stellar tidal disruption flares (TDFs) in inactive galaxies based on a successful search for these events among transients in galaxies using archival Sloan Digital Sky Survey (SDSS) multi-epoch imaging data (Stripe 82). This search yielded 186 nuclear flares in galaxies, 2 of which are excellent TDF candidates. Because of the systematic nature of the search, the very large number of galaxies, the long time of observation, and the fact that non-TDFs were excluded without resorting to assumptions about TDF characteristics, this study provides an unparalleled opportunity to measure the TDF rate. To compute the rate of optical stellar tidal disruption events, we simulate our entire pipeline to obtain the efficiency of detection. The rate depends on the light curves of TDFs, which are presently still poorly constrained. Using only the observed part of the SDSS light curves gives a model-independent upper limit to the optical TDF rate, \\dot{N}<2\\times 10^{-4}\\,yr^{-1}\\,galaxy^{-1} (90% CL), under the assumption that the SDSS TDFs are representative examples. We develop three empirical models of the light curves based on the two SDSS light curves and two more recent and better-sampled Pan-STARRS TDF light curves, leading to our best estimate of the rate: \\dot{N}_TDF = (1.5{--}2.0)_{-1.3}^{+2.7} \\times 10^{-5} \\,yr^{-1}\\, galaxy^{-1}. We explore the modeling uncertainties by considering two theoretically motivated light curve models, as well as two different relationships between black hole mass and galaxy luminosity, and two different treatments of the cutoff in the visibility of TDFs at large M BH. From this we conclude that these sources of uncertainty are not significantly larger than the statistical ones. Our results are applicable for galaxies hosting black holes with mass in the range of a few 106-108 M ⊙, and translates to a volumetric TDF rate of (4-8) × 10-8 ± 0.4 yr-1 Mpc-3, with the statistical

  18. Measurement and relevance of maximum metabolic rate in fishes.

    PubMed

    Norin, T; Clark, T D

    2016-01-01

    Maximum (aerobic) metabolic rate (MMR) is defined here as the maximum rate of oxygen consumption (M˙O2max ) that a fish can achieve at a given temperature under any ecologically relevant circumstance. Different techniques exist for eliciting MMR of fishes, of which swim-flume respirometry (critical swimming speed tests and burst-swimming protocols) and exhaustive chases are the most common. Available data suggest that the most suitable method for eliciting MMR varies with species and ecotype, and depends on the propensity of the fish to sustain swimming for extended durations as well as its capacity to simultaneously exercise and digest food. MMR varies substantially (>10 fold) between species with different lifestyles (i.e. interspecific variation), and to a lesser extent (measuring this trait has spread across disciplines in attempts to predict effects of climate change on fish populations. Here, various techniques used to elicit and measure MMR in different fish species with contrasting lifestyles are outlined and the relevance of MMR to the ecology, fitness and climate change resilience of fishes is discussed.

  19. Response times from ensembles of accumulators

    PubMed Central

    Zandbelt, Bram; Purcell, Braden A.; Palmeri, Thomas J.; Logan, Gordon D.; Schall, Jeffrey D.

    2014-01-01

    Decision-making is explained by psychologists through stochastic accumulator models and by neurophysiologists through the activity of neurons believed to instantiate these models. We investigated an overlooked scaling problem: How does a response time (RT) that can be explained by a single model accumulator arise from numerous, redundant accumulator neurons, each of which individually appears to explain the variability of RT? We explored this scaling problem by developing a unique ensemble model of RT, called e pluribus unum, which embodies the well-known dictum “out of many, one.” We used the e pluribus unum model to analyze the RTs produced by ensembles of redundant, idiosyncratic stochastic accumulators under various termination mechanisms and accumulation rate correlations in computer simulations of ensembles of varying size. We found that predicted RT distributions are largely invariant to ensemble size if the accumulators share at least modestly correlated accumulation rates and RT is not governed by the most extreme accumulators. Under these regimes the termination times of individual accumulators was predictive of ensemble RT. We also found that the threshold measured on individual accumulators, corresponding to the firing rate of neurons measured at RT, can be invariant with RT but is equivalent to the specified model threshold only when the rate correlation is very high. PMID:24550315

  20. Snowfall Rate Retrieval using NPP ATMS Passive Microwave Measurements

    NASA Technical Reports Server (NTRS)

    Meng, Huan; Ferraro, Ralph; Kongoli, Cezar; Wang, Nai-Yu; Dong, Jun; Zavodsky, Bradley; Yan, Banghua; Zhao, Limin

    2014-01-01

    Passive microwave measurements at certain high frequencies are sensitive to the scattering effect of snow particles and can be utilized to retrieve snowfall properties. Some of the microwave sensors with snowfall sensitive channels are Advanced Microwave Sounding Unit (AMSU), Microwave Humidity Sounder (MHS) and Advance Technology Microwave Sounder (ATMS). ATMS is the follow-on sensor to AMSU and MHS. Currently, an AMSU and MHS based land snowfall rate (SFR) product is running operationally at NOAA/NESDIS. Based on the AMSU/MHS SFR, an ATMS SFR algorithm has been developed recently. The algorithm performs retrieval in three steps: snowfall detection, retrieval of cloud properties, and estimation of snow particle terminal velocity and snowfall rate. The snowfall detection component utilizes principal component analysis and a logistic regression model. The model employs a combination of temperature and water vapor sounding channels to detect the scattering signal from falling snow and derive the probability of snowfall (Kongoli et al., 2014). In addition, a set of NWP model based filters is also employed to improve the accuracy of snowfall detection. Cloud properties are retrieved using an inversion method with an iteration algorithm and a two-stream radiative transfer model (Yan et al., 2008). A method developed by Heymsfield and Westbrook (2010) is adopted to calculate snow particle terminal velocity. Finally, snowfall rate is computed by numerically solving a complex integral. The ATMS SFR product is validated against radar and gauge snowfall data and shows that the ATMS algorithm outperforms the AMSU/MHS SFR.

  1. Measurement of Carbon Dioxide Accumulation and Physiological Function in the Launch and Entry and Advanced Crew Escape Suits

    NASA Technical Reports Server (NTRS)

    Bishop, Phillip; Greenisen, M. C.

    1997-01-01

    The Launch and Entry Suit (LES) and Advanced Crew Escape Suit (ACES) are worn by astronauts for launch and entry. Previous work by Waligora, et al., 1992, Waligora and Gilbert, 1992, and Dalrymple 1996, have found that carbon dioxide (CO2) accumulation in the LES/ACES helmet may be problematic. CO2 accumulation is important because high inspired levels of CO2 reduce physical function and pose a safety hazard (e.g. levels of CO2 accumulation of 3.6% in the Extravehicular Mobility Unit are sufficient to terminate Extra Vehicular Activities). My task was to design a suitable test protocol for determining the important physiological aspects of LES/ACES use. Three basic issues arose. First was the determination of the astronaut's CO2 inspiration during visor-down use at rest and during walking at 3.5 mph. A sub-issue was the impact of a pneumotach on CO2 since it has been previously observed that when the Aerosport pneumotach was used, performance seemed improved, which might be attributable to a lowered respiration rate when using the pneumotach. The second issue was the energy costs of waLking in the LES/ACES with various G-suit inflation levels, since G-suit inflation increases metabolic costs and metabolic costs influence the C02 production in the LES/ACES helmet. Since G-suit inflation improves orthostatic tolerance after space flight, but likely increases the energy costs of walking, the balance between G-suit inflation and C02 accumulation is an important safety consideration. The third issue which arose from pilot work was the substantial reduction in physical function after a 10 min visor-down period prior to walk.

  2. Instrument for precision long-term β-decay rate measurements

    NASA Astrophysics Data System (ADS)

    Ware, M. J.; Bergeson, S. D.; Ellsworth, J. E.; Groesbeck, M.; Hansen, J. E.; Pace, D.; Peatross, J.

    2015-07-01

    We describe an experimental setup for making precision measurements of relative β-decay rates of 22Na, 36Cl, 54Mn, 60Co, 90Sr, 133Ba, 137Cs, 152Eu, and 154Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate.

  3. Instrument for precision long-term β-decay rate measurements

    SciTech Connect

    Ware, M. J. Bergeson, S. D.; Ellsworth, J. E.; Groesbeck, M.; Hansen, J. E.; Pace, D.; Peatross, J.

    2015-07-15

    We describe an experimental setup for making precision measurements of relative β-decay rates of {sup 22}Na, {sup 36}Cl, {sup 54}Mn, {sup 60}Co, {sup 90}Sr, {sup 133}Ba, {sup 137}Cs, {sup 152}Eu, and {sup 154}Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate.

  4. Attitude/attitude-rate estimation from GPS differential phase measurements using integrated-rate parameters

    NASA Technical Reports Server (NTRS)

    Oshman, Yaakov; Markley, Landis

    1998-01-01

    A sequential filtering algorithm is presented for attitude and attitude-rate estimation from Global Positioning System (GPS) differential carrier phase measurements. A third-order, minimal-parameter method for solving the attitude matrix kinematic equation is used to parameterize the filter's state, which renders the resulting estimator computationally efficient. Borrowing from tracking theory concepts, the angular acceleration is modeled as an exponentially autocorrelated stochastic process, thus avoiding the use of the uncertain spacecraft dynamic model. The new formulation facilitates the use of aiding vector observations in a unified filtering algorithm, which can enhance the method's robustness and accuracy. Numerical examples are used to demonstrate the performance of the method.

  5. Bit error rate measurement above and below bit rate tracking threshold

    NASA Technical Reports Server (NTRS)

    Kobayaski, H. S.; Fowler, J.; Kurple, W. (Inventor)

    1978-01-01

    Bit error rate is measured by sending a pseudo-random noise (PRN) code test signal simulating digital data through digital equipment to be tested. An incoming signal representing the response of the equipment being tested, together with any added noise, is received and tracked by being compared with a locally generated PRN code. Once the locally generated PRN code matches the incoming signal a tracking lock is obtained. The incoming signal is then integrated and compared bit-by-bit against the locally generated PRN code and differences between bits being compared are counted as bit errors.

  6. Sediment accumulation rates and high-resolution stratigraphy of recent fluvial suspension deposits in various fluvial settings, Morava River catchment area, Czech Republic

    NASA Astrophysics Data System (ADS)

    Sedláček, Jan; Bábek, Ondřej; Kielar, Ondřej

    2016-02-01

    We present a comprehensive study concerning sedimentary processes in fluvial sediment traps within the Morava River catchment area (Czech Republic) involving three dammed reservoirs, four meanders and oxbow lakes, and several natural floodplain sites. The objective of the study was to determine sediment accumulation rates (SAR), estimate erosion rates, calculating these using a combination of the 137Cs method and historical data. Another purpose of this study was to provide insight into changing erosion and accumulation rates over the last century. Extensive water course modifications were carried out in the Morava River catchment area during the twentieth century, which likely affected sedimentation rates along the river course. Other multiproxy stratigraphic methods (X-ray densitometry, magnetic susceptibility, and visible-light reflectance spectrometry) were applied to obtain additional information about sediment infill. Sediment stratigraphy revealed distinct distal-to-proximal patterns, especially in reservoirs. Granulometrically, silts and sandy silts prevailed in sediments. Oxbow lakes and meanders contained larger amounts of clay and organic matter, which is the main difference between them and reservoirs. Pronounced 137Cs peaks were recorded in all studied cores (maximum 377 Bq·kg- 1), thus indicating Chernobyl fallout from 1986 or older events. Calculated sediment accumulation rates were lowest in distal parts of reservoirs (0.13-0.58 cm/y) and floodplains (0.45-0.88 cm/y), moderately high rates were found in proximal parts of reservoirs and oxbow lakes (2.27-4.4 cm/y), and the highest rates in some oxbow lakes located near the river (6-8 cm/y). The frequency of the inundation still can be high in some natural areas as in the Litovelské Pomoraví protected area, whereas the decreasing frequency of the inundation in other modified parts can contribute to a lower sedimentation rate. The local effects such as difference between SARs in oxbow lakes and

  7. Increasing sediment accumulation rates in La Fonera (Palamós) submarine canyon axis and their relationship with bottom trawling activities

    NASA Astrophysics Data System (ADS)

    Puig, P.; Martín, J.; Masqué, P.; Palanques, A.

    2015-10-01

    Previous studies conducted in La Fonera (Palamós) submarine canyon (NW Mediterranean) found that trawling activities along the canyon flanks cause resuspension and transport of sediments toward the canyon axis. 210Pb chronology supported by 137Cs dating applied to a sediment core collected at 1750 m in 2002 suggested a doubling of the sediment accumulation rate since the 1970s, coincident with the rapid industrialization of the local trawling fleet. The same canyon area has been revisited a decade later, and new data are consistent with a sedimentary regime shift during the 1970s and also suggest that the accumulation rate during the last decade could be greater than expected, approaching ~2.4 cm yr-1 (compared to ~0.25 cm yr-1 pre-1970s). These results support the hypothesis that commercial bottom trawling can substantially affect sediment dynamics and budgets on continental margins, eventually initiating the formation of anthropogenic depocenters in submarine canyon environments.

  8. Comprehensive modeling and investigation of the effect of iron on the growth rate and lipid accumulation of Chlorella vulgaris cultured in batch photobioreactors.

    PubMed

    Concas, Alessandro; Steriti, Alberto; Pisu, Massimo; Cao, Giacomo

    2014-02-01

    Recent works have shown that specific strains of microalgae are capable to simultaneously increase their growth rate and lipid content when cultured under suitable concentrations of iron. While these results are promising in view of the exploitation of microalgae for producing biofuels, to the best of our knowledge, no mathematical model capable to describe the effect of iron on lipid accumulation in microalgae, has been so far proposed. A comprehensive mathematical model describing the effect of iron on chlorophyll synthesis, nitrogen assimilation, growth rate and lipid accumulation in a freshwater strain of Chlorella vulgaris is then proposed in this work. Model results are successfully compared with experimental data which confirm the positive effect of growing iron concentrations on lipid productivity of C. vulgaris. Thus, the proposed model might represent a useful tool to optimize iron-based strategies to improve the lipid productivity of microalgal cultures.

  9. Preferential accumulation of sex and Bs chromosomes in biarmed karyotypes by meiotic drive and rates of chromosomal changes in fishes.

    PubMed

    Molina, Wagner F; Martinez, Pablo A; Bertollo, Luiz A C; Bidau, Claudio J

    2014-12-01

    Mechanisms of accumulation based on typical centromeric drive or of chromosomes carrying pericentric inversions are adjusted to the general karyotype differentiation in the principal Actinopterygii orders. Here, we show that meiotic drive in fish is also supported by preferential establishment of sex chromosome systems and B chromosomes in orders with predominantly bi-brachial chromosomes. The mosaic of trends acting at an infra-familiar level in fish could be explained as the interaction of the directional process of meiotic drive as background, modulated on a smaller scale by adaptive factors or specific karyotypic properties of each group, as proposed for the orthoselection model.

  10. Measurement of outgassing rate for GTAW welded SS304 materials

    NASA Astrophysics Data System (ADS)

    Bukhari, Mohsin; Mukherjee, Samiran; Panchal, Paresh; Gangradey, Ranjana; Shukla, Ajit Kumar

    2016-09-01

    Outgassing plays an important role to achieve Ultra High Vacuum (UHV) and to maintaining the required vacuum level of the vessel. For a large size machines like Tokamak, accelerators, space simulation chambers, outgassing from the structural materials and their welding sections need to be checked during the design. Hence studies were carried out for the measurement of outgassing rate for the Gas Tungsten Arc Welding (GTAW) welded SS304 materials at OutGassing Measurement System (OGMS) at IPR Extension Lab. The system consists of two chambers, pumping chamber and sample chamber, made up of 304 grades Stainless Steel pre-air baked at 400 °C. The pumping chamber connected to a turbo molecular pump having pumping speed 240 l/s, backed by a rotary vacuum pump having pumping speed 5m3/hour. Pumping chamber and sample chamber connected through a 100 CF flange having a circular aperture of 5.2 mm diameter. The conductance of aperture is 2.47 l/s. Bare SS304 sample & GTAW welded SS304 samples are prepared with 100mmX50mmX5mm and 95mmX55mmX5mm dimensions respectively. The base outgassing rate of the blank system is 2.34×10-11 mbar l/s-cm2. The calculated outgassing rate is 3.66×10-10 & 4.37×10-10 mbar l/s-cm2 for bare sample & welded sample. From the partial pressure analysis it has been found that hydrogen and nitrogen are in the partial level of 3.35×10-9 & 2.36×10-9 for bare sample and 3.14×10-9 mbar & 2.33×10-9 mbar for welded sample. It has been observed that, the GTAW doesn't have major effect on outgassing rate and one can use welded joint for designing a large vessel welding sections.

  11. Excitation rate and background measurements during LIF studies on krypton

    NASA Astrophysics Data System (ADS)

    Whitehead, C. A.; Cannon, B. D.; Wacker, J. F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure Kr-85 concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce Kr-85 to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p(sub 6) state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the Kr-85 isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p(sub 8) energy level. Non-isotopically selective de-excitation rates as high as 5 x 10(exp 5)/sec have been measured, yielding a signal-to-background ratio of g reater than 10(exp 6). The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by Kr-85. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2-3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  12. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure [sup 85]Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce [sup 85]Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p[sub 6] state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the [sup 85]Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p[sub 8] energy level. Non-isotopically selective de-excitation rates as high as 5 [times] 10[sup 5] sec[sup [minus]1] have been measured, yielding a signal-to-background ratio of >10[sup 6]. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by [sup 85]Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  13. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure {sup 85}Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce {sup 85}Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p{sub 6} state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the {sup 85}Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p{sub 8} energy level. Non-isotopically selective de-excitation rates as high as 5 {times} 10{sup 5} sec{sup {minus}1} have been measured, yielding a signal-to-background ratio of >10{sup 6}. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by {sup 85}Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  14. How Integrated Management Strategies Promote Protein Quality of Cotton Embryos: High Levels of Soil Available N, N Assimilation and Protein Accumulation Rate

    PubMed Central

    Yang, HongKun; Meng, YaLi; Chen, BingLin; Zhang, XingYue; Wang, YouHua; Zhao, WenQing; Zhou, ZhiGuo

    2016-01-01

    Cottonseed is widely used as a source of ruminant feed and for industrial purposes. Therefore, there is a tremendous need to improve the nutritional value of cotton embryos. In this study, a conventional management (CM) and two integrated cotton management strategies (IMS1, IMS2) were performed at two soil fertility levels to study the relationships among soil N, N assimilation, embryonic protein accumulation and protein quality. The levels of proteins, essential amino acids, and semi-essential amino acids, especially those of glutamate, lysine, and methionine, were higher in IMS1 and IMS2 embryos than in CM embryos. These changes were significantly positively correlated with the soil-available N content, glutamine synthetase activity and peak value of protein accumulation rate and were negatively correlated with the free amino acid level. These results illustrated that integrated management strategies, especially the rates and timing of N application, raise the level of soil available N, which is beneficial for N assimilation in developing cotton embryos. The protein content was limited by the rate of protein accumulation rather than by the free amino acid content. The combination of target yield fertilization, a growth-driven N application schedule, a high plant density and the seedling raising with bio-organic fertilizer can substantially improve protein quality in cotton embryos, especially at a soil with low soil organic matter and total nitrogen. PMID:27532007

  15. How Integrated Management Strategies Promote Protein Quality of Cotton Embryos: High Levels of Soil Available N, N Assimilation and Protein Accumulation Rate.

    PubMed

    Yang, HongKun; Meng, YaLi; Chen, BingLin; Zhang, XingYue; Wang, YouHua; Zhao, WenQing; Zhou, ZhiGuo

    2016-01-01

    Cottonseed is widely used as a source of ruminant feed and for industrial purposes. Therefore, there is a tremendous need to improve the nutritional value of cotton embryos. In this study, a conventional management (CM) and two integrated cotton management strategies (IMS1, IMS2) were performed at two soil fertility levels to study the relationships among soil N, N assimilation, embryonic protein accumulation and protein quality. The levels of proteins, essential amino acids, and semi-essential amino acids, especially those of glutamate, lysine, and methionine, were higher in IMS1 and IMS2 embryos than in CM embryos. These changes were significantly positively correlated with the soil-available N content, glutamine synthetase activity and peak value of protein accumulation rate and were negatively correlated with the free amino acid level. These results illustrated that integrated management strategies, especially the rates and timing of N application, raise the level of soil available N, which is beneficial for N assimilation in developing cotton embryos. The protein content was limited by the rate of protein accumulation rather than by the free amino acid content. The combination of target yield fertilization, a growth-driven N application schedule, a high plant density and the seedling raising with bio-organic fertilizer can substantially improve protein quality in cotton embryos, especially at a soil with low soil organic matter and total nitrogen.

  16. Combined effects of water flow and copper concentration on the feeding behavior, growth rate, and accumulation of copper in tissue of the infaunal polychaete Polydora cornuta.

    PubMed

    Colvin, Marienne A; Hentschel, Brian T; Deheyn, Dimitri D

    2016-12-01

    We performed an experiment in a laboratory flume to test the effects of water flow speed and the concentration of aqueaous copper on the feeding behavior, growth rate, and accumulation of copper in the tissues of juvenile polychaetes Polydora cornuta. The experiment included two flow speeds (6 or 15 cm/s) and two concentrations of added copper (0 or 85 μg/L). Worms grew significantly faster in the faster flow and in the lower copper concentration. In the slower flow, the total time worms spent feeding decreased significantly as copper concentration increased, but copper did not significantly affect the time worms spent feeding in the faster flow. Across all treatments, there was a significant, positive relationship between the time individuals spent feeding and their relative growth rate. Worms were observed suspension feeding significantly more often in the faster flow and deposit feeding significantly more often in the slower flow, but copper concentration did not affect the proportion of time spent in either feeding mode. The addition of 85 μg/L copper significantly increased copper accumulation in P. cornuta tissue, but the accumulation did not differ significantly due to flow speed. There was a significant interaction between copper and flow; the magnitude of the difference in copper accumulation between the 0 and 85 μg/L treatments was greater in the faster flow than in the slower flow. In slow flows that favor deposit feeding, worms grow slowly and accumulate less copper in their tissue than in faster flows that favor suspension feeding and faster growth.

  17. Effect of different tannery sludge compost amendment rates on growth, biomass accumulation and yield responses of Capsicum plants.

    PubMed

    Silva, Jayara D C; Leal, Tamara T B; Araújo, Ademir S F; Araujo, Raul M; Gomes, Regina L F; Melo, Wanderley J; Singh, Rajeev P

    2010-10-01

    Composting has been recognized as one of the most cost effective and environmentally sound alternatives for organic wastes recycling from long and composted wastes have a potential to substitute inorganic fertilizers. We investigated the potential of composted tannery sludge for ornamental purposes and to examine the effects of two different composts and concentrations on ornamental Capsicum growth. The two composts were produced with tannery sludge and the composition of each compost was: compost(1) of tannery sludge (C(1)TS) - tannery sludge+sugarcane straw and cattle manure mixed in the ratio 1:3:1 (v:v:v); compost(2) of tannery sludge (C(2)TS) - tannery sludge+"carnauba" straw and cattle manure in the ratio 1:3:1 (v:v:v). Each compost was amended with soil at rates (% v:v) of 0%, 25%, 50%, 75% and 100% (designation hereafter as T(1)-T(5), respectively). The number of leaves and fruits were counted, and the stem length was also measured. Chlorophyll content was recorded on three leaves of each harvested plant prior to harvest. Number of leaves and fruits, stem length, dry weight of shoot and roots did not vary significantly between the plants grown in two tannery composts. All the treatments with composted tannery sludge application (T(2)-T(5)) significantly increased the number of leaves and fruits, stem length and chlorophyll content compared with the control (T(1)). The chlorophyll content was higher in plants growing in the C(1)TS compared to C(2)TS. The results of the present study further suggest that Capsicum may be a good option to be grown on composted tannery amended soil.

  18. Direct Measurements of Reconnection Rate Attenuation by Plasmasphere Plumes

    NASA Astrophysics Data System (ADS)

    Sanchez, E. R.; Takahashi, K.

    2013-12-01

    It is widely hypothesized that mass loading of the magnetosphere (the process whereby the average mass density of the magnetosphere increases from its nominal value) significantly impacts solar wind-magnetosphere coupling and circulation within the magnetosphere. One important way in which mass loading can affect the magnetosphere occurs when enhanced convection after a lull in geomagnetic activity brings super-dense plasma from the plasmasphere (the so-called plasmsphere plume) into the dayside reconnection site. We measured the magnetic flux across the dayside polar cap boundary (a proxy of the dayside magnetic field reconnection rate) and tracked the sunward migration of the plasma plume for three storms that occurred after long intervals of quiet conditions. Significant intermittent reduction in the dayside reconnection potential (approximately 66% in the most pronounced case) was observed in the hours following the onset of negative IMF Bz condition, in agreement with the hypothesis that super-dense magnetospheric plasma convected into the dayside magnetopause inhibits reconnection.

  19. Disintegration rate measurement of a 152Eu solution.

    PubMed

    Koskinas, Marina F; Fonseca, Kátia A; Dias, Mauro S

    2002-01-01

    The procedure followed by the Laboratório de Metrologia Nuclear at the IPEN-CNEN/SP, in São Paulo, for the standardization of 152Eu is described. The disintegration rate of 152Eu has been measured using the 4pi beta-gamma coincidence technique, using a 4pi proportional counter, filled with P-10 gas and operated at 0.1 MPa, coupled to one HPGe detector for the gamma-ray emission. Two discrimination windows were set in the gamma-channel, one related to the beta branch (344 keV) and the other related to the electron capture events (1408.03 keV), in order to determine the counting efficiencies for beta, X-ray and Auger electron events in the proportional counter. The activity of solution was determined by a biparametric extrapolation curve obtained for the two selected gamma-windows.

  20. Estimation of Measurement Characteristics of Ultrasound Fetal Heart Rate Monitor

    NASA Astrophysics Data System (ADS)

    Noguchi, Yasuaki; Mamune, Hideyuki; Sugimoto, Suguru; Yoshida, Atsushi; Sasa, Hidenori; Kobayashi, Hisaaki; Kobayashi, Mitsunao

    1995-05-01

    Ultrasound fetal heart rate monitoring is very useful to determine the status of the fetus because it is noninvasive. In order to ensure the accuracy of the fetal heart rate (FHR) obtained from the ultrasound Doppler data, we measure the fetal electrocardiogram (ECG) directly and obtain the Doppler data simultaneously. The FHR differences of the Doppler data from the direct ECG data are concentrated at 0 bpm (beats per minute), and are practically symmetrical. The distribution is found to be very close to the Student's t distribution by the test of goodness of fit with the chi-square test. The spectral density of the FHR differences shows the white noise spectrum without any dominant peaks. Furthermore, the f-n (n>1) fluctuation is observed both with the ultrasound Doppler FHR and with the direct ECG FHR. Thus, it is confirmed that the FHR observation and observation of the f-n (n>1) fluctuation using the ultrasound Doppler FHR are as useful as the direct ECG.

  1. Direct measurement of densification rate using a neutron scattering technique

    NASA Astrophysics Data System (ADS)

    Morris, E. M.; Wingham, D.

    2012-12-01

    A non-destructive method for measuring density, based on neutron-scattering, has been used in the dry snow area of the Greenland Ice Sheet to derive profiles of densification rate over periods ranging from a few days to 5 years. From these observations we have derived a constitutive law for the compaction of dry snow relating strainrate to stress, temperature and the "type" of snow, that is, whether the snow is part of a "winter" wind-compacted layer with rounded grains or a "summer" lower-density hoar layer. We suggest that the processes which allow compaction of the snow also promote sintering, by bringing the snow grains into closer proximity. Higher temperatures increase the initial densification rate for a snow element but also, over time, harden it more rapidly. The net result is a much-reduced apparent activation energy for snow densification, similar to that used by Herron and Langway in their empirical equation derived from ice core density profiles.

  2. Interseismic accumulation across the Khoy fault from InSAR measurement

    NASA Astrophysics Data System (ADS)

    Mohseni Aref, Mohammad; Çakir, Ziyadin; Karimzadeh, Sadra

    2016-04-01

    The Khoy fault is part of a long right lateral strike slip fault that runs in NW-SE direction between Çaldıran in eastern Turkey and Tabriz in northwest of Iran within the Turkish-Iranian plateau that accommodates the plate convergence between Eurasia and Arabia. It connects the North Tabriz Fault (NTF) with the Gailatu-Siah Chesmeh and Çaldiran faults, and thus is named here the Çaldiran-Tabriz fault (CTF). The CTF, unlike the North and East Anatolian faults to the west, does not have a clear morphological expression in the topography along much of it length. Active fault maps show a distributed deformation zone. Nevertheless, it has produced several devastating large earthquakes both recently (e.g., Ms 7.3, 1976 Çaldiran earthquake), and historical times (e.g., Ms > 7, 1721 and 1780 Tabriz earthquakes).The recent double earthquakes (Mw 6.5 and 6.2) of August 11th, 2012 in Ahar-Varzaghan area 40-45 km north of the NTF manifest the seismic activity of the region. Recent geodetic studies using GPS InSAR suggest 9±2 mm/yr of slip rate for the NTF, which is significantly higher than geologically determined slip rates (e.g., 2-4 mm/yr). In this study, we use InSAR data acquired from 2003 and 2010 on a descending orbit track of ENVISAT satellite, across the Khoy fault zone, which is the north-western continuation of the NTF north of the Urmia Lake. We use the Stanford method of persistent scatter interferometry (StaMPS) technique to overcome the decorelation problem with time and over large areas. The line of sight velocity field we obtained clearly delineates the shear zone that trends NW-SW aligning with the NTF. We project the mean line of sigh velocity field derived by InSAR time series onto fault parallel horizontal velocity field, assumed that vertical offset rate of the Khoy fault is negligible. Single screw dislocation models in elastic half-space model were applied along the fault zone to estimate slip rate, locking depth and fault location within 95

  3. Cortisol production rates measured by liquid chromatography/mass spectrometry

    SciTech Connect

    Esteban, N.V.; Yergey, A.L. )

    1990-04-01

    Cortisol production rates (FPRs) in physiologic and pathologic states in humans have been investigated over the past 30 years. However, there has been conflicting evidence concerning the validity of the currently accepted value of FPRs in humans (12 to 15 mg/m2/d) as determined by radiotracer methodology. The present study reviews previous methods proposed for the measurement of FPRs in humans and discusses the applications of the first method for the direct determination of 24-hour plasma FPRs during continuous administration of a stable isotope, using a thermospray high-pressure liquid chromatography-mass spectrometry technique. The technique is fast, sensitive, and, unlike gas chromatography-mass spectrometry methods, does not require derivatization, allowing on-line detection and quantification of plasma cortisol after a simple extraction procedure. The results of determination of plasma FPRs by stable tracer/mass spectrometry are directly in units of mass/time and, unlike radiotracer methods, are independent of any determination of volume of distribution or cortisol concentration. Our methodology offers distinct advantages over radiotracer techniques in simplicity and reliability since only single measurements of isotope ratios are required. The technique was validated in adrenalectomized patients. Circadian variations in daily FRPs were observed in normal volunteers, and, to date, results suggest a lower FRP in normal children and adults than previously believed. 88 references.

  4. Under-canopy snow accumulation and ablation measured with airborne scanning LiDAR altimetry and in-situ instrumental measurements, southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Kirchner, P. B.; Bales, R. C.; Musselman, K. N.; Molotch, N. P.

    2012-12-01

    We investigated the influence of canopy on snow accumulation and melt in a mountain forest using paired snow on and snow off scanning LiDAR altimetry, synoptic measurement campaigns and in-situ time series data of snow depth, SWE, and radiation collected from the Kaweah River watershed, Sierra Nevada, California. Our analysis of forest cover classified by dominant species and 1 m2 grided mean under canopy snow accumulation calculated from airborne scanning LiDAR, demonstrate distinct relationships between forest class and under-canopy snow depth. The five forest types were selected from carefully prepared 1 m vegetation classifications and named for their dominant tree species, Giant Sequoia, Jeffrey Pine, White Fir, Red Fir, Sierra Lodgepole, Western White Pine, and Foxtail Pine. Sufficient LiDAR returns for calculating mean snow depth per m2 were available for 31 - 44% of the canopy covered area and demonstrate a reduction in snow depth of 12 - 24% from adjacent open areas. The coefficient of variation in snow depth under canopies ranged from 0.2 - 0.42 and generally decreased as elevation increased. Our analysis of snow density snows no statistical significance between snow under canopies and in the open at higher elevations with a weak significance for snow under canopies at lower elevations. Incident radiation measurements made at 15 minute intervals under forest canopies show an input of up to 150 w/m2 of thermal radiation from vegetation to the snow surface on forest plots. Snow accumulated on the mid to high elevation forested slopes of the Sierra Nevada represents the majority of winter snow storage. However snow estimates in forested environments demonstrate a high level of uncertainty due to the limited number of in-situ observations and the inability of most remote sensing platforms to retrieve reflectance under dense vegetation. Snow under forest canopies is strongly mediated by forest cover and decoupled from the processes that dictate accumulation

  5. Gamma radiation measurements and dose rates in commercially-used natural tiling rocks (granites).

    PubMed

    Tzortzis, Michalis; Tsertos, Haralabos; Christofides, Stelios; Christodoulides, George

    2003-01-01

    The gamma radiation in samples of a variety of natural tiling rocks (granites) imported in Cyprus for use in the building industry was measured, employing high-resolution gamma-ray spectroscopy. The rock samples were pulverised, sealed in 1-l plastic Marinelli beakers, and measured in the laboratory with an accumulating time between 10 and 14 h each. From the measured gamma-ray spectra, activity concentrations were determined for (232)Th (range from 1 to 906 Bq kg(-1)), (238)U (from 1 to 588 Bq kg(-1)) and (40)K (from 50 to 1606 Bq kg(-1)). The total absorbed dose rates in air calculated from the concentrations of the three radionuclides ranged from 7 to 1209 nGy h(-1) for full utilization of the materials, from 4 to 605 nGy h(-1) for half utilization and from 2 to 302 nGy h(-1) for one quarter utilization. The total effective dose rates per person indoors were determined to be between 0.02 and 2.97 mSv y(-1) for half utilization of the materials. Applying dose criteria recently recommended by the EU for superficial materials, 25 of the samples meet the exemption dose limit of 0.3 mSv y(-1), two of them meet the upper dose limit of 1 mSv y(-1) and only one clearly exceeds this limit.

  6. Inferential consequences of modeling rather than measuring snow accumulation in studies of animal ecology

    USGS Publications Warehouse

    Cross, Faul C.; Klaver, Robert W.; Brennan, Angela; Creel, Scott; Beckmann, Jon P.; Higgs, Megan D.; Scurlock, Brandon M.

    2013-01-01

    Abstract. It is increasingly common for studies of animal ecology to use model-based predictions of environmental variables as explanatory or predictor variables, even though model prediction uncertainty is typically unknown. To demonstrate the potential for misleading inferences when model predictions with error are used in place of direct measurements, we compared snow water equivalent (SWE) and snow depth as predicted by the Snow Data Assimilation System (SNODAS) to field measurements of SWE and snow depth. We examined locations on elk (Cervus canadensis) winter ranges in western Wyoming, because modeled data such as SNODAS output are often used for inferences on elk ecology. Overall, SNODAS predictions tended to overestimate field measurements, prediction uncertainty was high, and the difference between SNODAS predictions and field measurements was greater in snow shadows for both snow variables compared to non-snow shadow areas. We used a simple simulation of snow effects on the probability of an elk being killed by a predator to show that, if SNODAS prediction uncertainty was ignored, we might have mistakenly concluded that SWE was not an important factor in where elk were killed in predatory attacks during the winter. In this simulation, we were interested in the effects of snow at finer scales (2) than the resolution of SNODAS. If bias were to decrease when SNODAS predictions are averaged over coarser scales, SNODAS would be applicable to population-level ecology studies. In our study, however, averaging predictions over moderate to broad spatial scales (9–2200 km2) did not reduce the differences between SNODAS predictions and field measurements. This study highlights the need to carefully evaluate two issues when using model output as an explanatory variable in subsequent analysis: (1) the model’s resolution relative to the scale of the ecological question of interest and (2) the implications of prediction uncertainty on inferences when using model

  7. Inferential consequences of modeling rather than measuring snow accumulation in studies of animal ecology.

    PubMed

    Brennan, Angela; Cross, Paul C; Higgs, Megan; Beckmann, Jon P; Klaver, Robert W; Scurlock, Brandon M; Creel, Scott

    2013-04-01

    It is increasingly common for studies of animal ecology to use model-based predictions of environmental variables as explanatory or predictor variables, even though model prediction uncertainty is typically unknown. To demonstrate the potential for misleading inferences when model predictions with error are used in place of direct measurements, we compared snow water equivalent (SWE) and snow depth as predicted by the Snow Data Assimilation System (SNODAS) to field measurements of SWE and snow depth. We examined locations on elk (Cervus canadensis) winter ranges in western Wyoming, because modeled data such as SNODAS output are often used for inferences on elk ecology. Overall, SNODAS predictions tended to overestimate field measurements, prediction uncertainty was high, and the difference between SNODAS predictions and field measurements was greater in snow shadows for both snow variables compared to non-snow shadow areas. We used a simple simulation of snow effects on the probability of an elk being killed by a predator to show that, if SNODAS prediction uncertainty was ignored, we might have mistakenly concluded that SWE was not an important factor in where elk were killed in predatory attacks during the winter. In this simulation, we were interested in the effects of snow at finer scales (< 1 km2) than the resolution of SNODAS. If bias were to decrease when SNODAS predictions are averaged over coarser scales, SNODAS would be applicable to population-level ecology studies. In our study, however, averaging predictions over moderate to broad spatial scales (9-2200 km2) did not reduce the differences between SNODAS predictions and field measurements. This study highlights the need to carefully evaluate two issues when using model output as an explanatory variable in subsequent analysis: (1) the model's resolution relative to the scale of the ecological question of interest and (2) the implications of prediction uncertainty on inferences when using model predictions

  8. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Hartle, R.; Simpson, D.; Johnson, R.; Thomsen, M.; Arridge, C.

    2011-01-01

    We present the present status of an investigation of the rotation rate of Saturn's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. for SOI and similar to that used by Thomsen et al.. This technique allows one to nearly cover the full energy range of the Cassini Plasma Spectrometer (CAPS) IMS from 1 V . E/Q < 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll maneuvers. We make comparisons with the bi-Maxwellian fitting technique developed by Wilson et al. and the similar velocity moment technique by Thomsen et al. . We concentrate our analysis when ion composition data is available, which is used to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The chosen periods have high enough telemetry rates (4 kbps or higher) so that coincidence ion data, similar to that used by Sittler et al. for SOI is available. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. In the future we will then make comparisons with magnetic field observations, Saturn ionosphere conductivities as presently known and the field aligned currents necessary for the planet to enforce corotation of the rotating plasma.

  9. Effect of altering the root-zone temperature on growth, translocation, carbon exchange rate, and leaf starch accumulation in the tomato.

    PubMed

    Hurewitz, J; Janes, H W

    1983-09-01

    Tomato seedlings (Lycopersicon esculentum Mill. cv Vendor) were grown hydroponically with their root systems maintained at a constant temperature for a 2-week period commencing with the appearance of the first true leaf. Based on fresh and dry weight and leaf area, the optimal root-zone temperature for seedling growth was 30 degrees C. The carbon exchange rate of the leaves was also found to increase with rising root-zone temperature up to 30 degrees C. However, a more complex relationship seems to exist between root-zone temperature and the accumulation of (14)C-labeled assimilates in the roots; inasmuch as there is no enhancement in this accumulation at the most growth promoting root-zone temperatures (22-30 degrees C).

  10. Are We Correctly Measuring Star-Formation Rates?

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B.; Skillman, Evan D.; Dolphin, Andrew E.; Mitchell, Noah P.

    2017-01-01

    Integrating our knowledge of star formation (SF) traced by observations at different wavelengths is essential for correctly interpreting and comparing SF activity in a variety of systems and environments. This study compares extinction-corrected, integrated ultraviolet (UV) emission from resolved galaxies with color-magnitude diagram (CMD) based star-formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The data sets are from the panchromatic Starburst Irregular Dwarf Survey (STARBIRDS) and include deep legacy GALEX UV imaging, Hubble Space Telescope optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near-UV fluxes predicted from the CMD-based SFRs—using four different models—agree with the measured, extinction corrected, integrated near-UV fluxes from GALEX images, but the far-UV (FUV) predicted fluxes do not. Furthermore, we find a systematic deviation between the SFRs based on integrated FUV luminosities and existing scaling relations, and the SFRs based on the resolved stellar populations. This offset is not driven by different SF timescales, variations in SFRs, UV attenuation, nor stochastic effects. This first comparison between CMD-based SFRs and an integrated FUV emission SFR indicator suggests that the most likely cause of the discrepancy is the theoretical FUV-SFR calibration from stellar evolutionary libraries and/or stellar atmospheric models. We present an empirical calibration of the FUV-based SFR relation for dwarf galaxies, with uncertainties, which is ˜53% larger than previous relations. These results have signficant implications for measuring FUV-based SFRs of high-redshift galaxies.

  11. Leaf senescence in rice due to magnesium deficiency mediated defect in transpiration rate before sugar accumulation and chlorosis.

    PubMed

    Kobayashi, Natsuko I; Saito, Takayuki; Iwata, Naoko; Ohmae, Yoshimi; Iwata, Ren; Tanoi, Keitaro; Nakanishi, Tomoko M

    2013-08-01

    Magnesium (Mg) is an essential macronutrient supporting various functions, including photosynthesis. However, the specific physiological responses to Mg deficiency remain elusive. In this study, 2-week-old rice seedlings (Oryza sativa. cv. Nipponbare) with three expanded leaves (L2-L4) were transferred to Mg-free nutrient solution for 8 days. In the absence of Mg, on day 8, L5 and L6 were completely developed, while L7 just emerged. We also studied several mineral deficiencies to identify specific responses to Mg deficiency. Each leaf was analyzed in terms of chlorophyll, starch, anthocyanin and carbohydrate metabolites, and only absence of Mg was found to cause irreversible senescence of L5. Resupply of Mg at various time points confirmed that the borderline of L5 death was between days 6 and 7 of Mg deficiency treatment. Decrease in chlorophyll concentration and starch accumulation occurred simultaneously in L5 and L6 blades on day 8. However, nutrient transport drastically decreased in L5 as early as day 6. These data suggest that the predominant response to Mg deficiency is a defect in transpiration flow. Furthermore, changes in myo-inositol and citrate concentrations were detected only in L5 when transpiration decreased, suggesting that they may constitute new biological markers of Mg deficiency.

  12. Proton Transfer Rate Coefficient Measurements of Selected Volatile Organic Molecules

    NASA Astrophysics Data System (ADS)

    Brooke, G.; Popović, S.; Vušković, L.

    2002-05-01

    We have developed an apparatus based on the selected ion flow tube (SIFT)footnote D. Smith and N.G. Adams, Ads. At. Mol. Phys. 24, 1 (1987). that allows the study of proton transfer between various positive ions and volatile organic molecules. Reactions in the flow tube occur at pressures of approximately 300 mTorr, eliminating the requirement of thermal beam production. The proton donor molecule H_3O^+ has been produced using several types of electrical discharges in water vapor, such as a capacitively coupled RF discharge and a DC hollow cathode discharge. Presently we are developing an Asmussen-type microwave cavity discharge using the components of a standard microwave oven that has the advantages of simple design and operation, as well as low cost. We will be presenting the results of the microwave cavity ion source to produce H_3O^+, and compare it to the other studied sources. In addition, we will be presenting a preliminary measurement of the proton transfer rate coefficient in the reaction of H_3O^+ with acetone and methanol.

  13. Estimating sediment accumulation rates in Manila Bay, a marine pollution hot spot in the Seas of East Asia.

    PubMed

    Sta Maria, E J; Siringan, F P; Bulos, A dM; Sombrito, E Z

    2009-01-01

    The GEF/UNDP/IMO/PEMSEA project identifies Manila Bay as among the marine pollution hot spots in the Seas of East Asia. (210)Pb dating of its sediment can provide a historical perspective of its pollution loading. However, the validity of (210)Pb dating in a complex dynamic coastal system of Manila Bay may come into question. Land-based sediment input can be high and physical and biological processes can possibly disturb the sediment layers. In this report, the (210)Pb profiles of sediment cores from different parts of the bay are presented. The linear sedimentation rates are shown to be higher in the recent past and are also variable across the bay. The largest change in sedimentation rate, coincided with the occurrence of a volcanic eruption in 1991 and is shown by applying a variant of the CIC model in sedimentation rate calculations. The data suggest that (210)Pb dating can be useful in estimating relative magnitudes of sedimentation rates, even in a complex dynamic coastal system like Manila Bay.

  14. Effects of feeding and organism loading rate on PCB accumulation by Lumbriculus variegatus in sediment bioaccumulation testing

    EPA Science Inventory

    Sediment bioaccumulation test methods published by USEPA and ASTM in 2000 specify that the Lumbriculus variegatus, a freshwater oligochaete, should not be fed during the 28-day exposure and recommends an organism loading rate of total organic carbon in sediment to organism dry we...

  15. Sedimentation rates in eastern North America reveal strong links between regional climate, depositional environments, and sediment accumulation

    NASA Astrophysics Data System (ADS)

    Goring, S. J.; McLachlan, J. S.; Jackson, S. T.; Blaauw, M.; Christen, J.; Marlon, J.; Blois, J.; Williams, J. W.

    2011-12-01

    PalEON is a multidisciplinary project that combines paleo and modern ecological data with state-of-the-art statistical and modelling tools to examine the interactions between climate, fire and vegetation during the past two millennia in the northeastern United States. A fundamental challenge for PalEON (and paleo research more broadly) is to improve age modelling to yield more accurate sediment-core chronologies. To address this challenge, we assessed sedimentation rates and their controls for 218 lakes and mires in the northeastern U.S. Sedimentation rates (yr/cm) were calculated from age-depth models, which were obtained from the Neotoma database (www.neotomadb.org) and other contributed pollen records. The age models were recalibrated to IntCal09 and augmented in some cases using biostratigraphic markers (Picea decline, 16 kcal BP - 10.5 kcal BP; Quercus rise, 12 - 9.1 kcal BP; and Alnus decline, 11.5 - 10.6 kcal BP) as described in Blois et al. (2011). Relationships between sedimentation rates and sediment age, site longitude, and depositional environment (lacustrine or mire) are significant but weak. There are clear and significant links between variations in the NGRIP record of δ18O and sedimentation in mires across the PalEON region, but no links to lacustrine sedimentation rates. This result indicates that super-regional climatic control of primary productivity, and thus autochthonic sediment deposition, dominates in mires while deposition in lacustrine basins may be driven primarily by local and regional factors including watershed size, surficial materials,and regional vegetation. The shape of the gamma probability functions that best describe sedimentation rate distributions are calculated and presented here for use as priors in Bayesian age modelling applications such as BACON (Blaauw and Christen, in press). Future applications of this research are also discussed.

  16. A Method for the Measurement of Nitrous Acid Flux Using Relaxed Eddy Accumulation

    NASA Astrophysics Data System (ADS)

    Bertman, S.; Marchewka, M.; King, J.

    2003-12-01

    HONO has recently received renewed attention as a byproduct of condensed nitrogen photolysis and as a potential atmospheric radical source. In particular, several recent accounts suggesting a photochemical source in forests have lead us to develop a method for assessing nitrous acid flux above a hardwood forest in northern Michigan. The technique was based on nitrous acid in ambient air being scrubbed into a 1mM phosphate buffer that was then derivatized into a light absorbing complex. A separate scrubbing system was used for updrafts and downdrafts after the air had been separated through Teflon valves according to input from a sonic anemometer. The detection of the complex was performed via UV absorption through a capillary flowthrough cell. Detection limit for this analytical method is around 10 pptv. Derivatized solution from each flow system was injected into the capillary cell via an 8-port valve with two sample loops. Each sample loop was injected as soon as it filled, which allowed measurement of all of the scrubbed material in each flow system. Laboratory tests were performed to assess the accuracy and suitability of this method. The field worthiness of the instrument was determined during the summer of 2003 at the University of Michigan Biological Station in northern Michigan where it was placed on top of a 35m tower above a forest canopy.

  17. Micro/meso scale fatigue damage accumulation monitoring using nonlinear acoustic vibro-modulation measurements

    NASA Astrophysics Data System (ADS)

    Zagrai, Andrei; Donskoy, Dimitri; Chudnovsky, Alexander; Golovin, Edward; Agarwala, Vinod S.

    2006-03-01

    Monitoring the incipient damage at the earliest possible stage is essential for predicting structural performance and remaining life of structural components. Existing prognostic methodologies incorporate conventional SHM and NDE techniques responsive to cracks and delaminations resulted from the irreversible material fracture and disintegration at the macro-scale. There is an increasing need for technologies that could allow for monitoring material degradation at the micro/meso scale before the onset of the macro-scale fracture. In this contribution, we report results of the real-time monitoring of the material micro/meso scale degradation using the nonlinear acoustic vibro-modulation technique. The technique explores nonlinear acoustic interaction of high frequency ultrasound and low frequency structural vibration at the site of the incipient damage. The indicator of the damage severity, nonlinear acoustic damage index (DI), was measured in real time during the strain-controlled three-point bending fatigue test of aluminum and steel specimens. Nondestructively, degradation of the specimen was revealed through the increase in the DI, which correlated well with the respective decrease in the specimen's stiffness. Destructive SEM examination confirmed sensitivity of the DI to the incipient micro/meso scale damage and advocated for utilizing the vibro-modulation approach for assessment of material degradation before fracture.

  18. X ray attenuation measurements for high-temperature materials characterization and in situ monitoring of damage accumulation

    NASA Astrophysics Data System (ADS)

    Baaklini, George Youssef

    1991-10-01

    The development and application is examined of x ray attenuation measurement systems that are capable of (1) characterizing density variations in high temperature materials, e.g., monolithic ceramics, ceramic and intermetallic matrix composites and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic matrix composites under room temperature tensile testing. Results are presented in the development of (1) a point scan digital radiography system and (2) an in-situ x ray material testing system. The former is used to characterize silicon carbide and silicon nitride specimens and the latter is used to image the failure behavior of silicon carbide fiber reinforced reaction bonded silicon nitride matrix composites. Further, state of the art x ray computed tomography is studied to determine its capabilities and limitations in characterizing density variations of subscale engine components, e.g., a silicon carbide rotor, a silicon nitride blade, and a silicon carbide fiber reinforced beta titanium matrix rod, rotor, and ring. Microfocus radiography, conventional radiography, scanning acoustic microscopy, and metallography are used to substantiate the x ray computed tomography findings. Point scan digital radiography is a viable technique for characterization density variations in monolithic ceramic specimens. But it is very limited and time consuming in characterizing ceramic matrix composities. Precise x ray attenuation measurements, reflecting minute density variations, are achieved by photon counting and by using micro collimators at the source and the detector. X ray computed tomography is found to be a unique x ray attenuation measurement technique capable of providing cross sectional spatial density information in monolithic ceramics and metal matrix composites. X ray computed tomography is proven to accelerate generic composite component development. Radiographic evaluation before, during and after loading show the effect of preexisting

  19. Simulation of continental basin margin sedimentation in response to crustal movements, eustatic sea level change, and sediment accumulation rates

    SciTech Connect

    Helland-Hansen, W.; Kendall, C.G.St.C.; Lerche, I.; Nakayama, K.

    1988-10-01

    As eustasy, subsidence, and sediment accumulation vary, a 2D computer-based graphical simulation generates on-lapping and off-lapping geometries of both marine and near coastal alluvial deposits, reproducing timelines within sediment-bodies at basin margins. In the simulation, deposition is expressed by creation of new surfaces above previous ones. Thicknesses of layers are reduced by both erosion and compaction while their surfaces move vertically in response to tectonic change and loading. Simulation is divided into a series of equal time steps in which sediment is deposited as an array of en-echelon columns that mark the top of the previous depositional surface. The volume of sediment deposited in each time step is expressed as a 2D cross section and is derived from two right-angle triangles (sand and shale), whose areas are a 2D expression of the quantity of sediment deposited at that time step and whose length matches the width of the offshore sediment wedge seaward of the shoreline. Each column in the array is filled by both marine sediments up to sea level, and alluvial sediments to a surface determined by an alluvial angle that is projected landward from the shore to its intersection with the previous surface. Each time the area representing the sediment column is subtracted from the triangles, the triangle heights are reduced correspondingly. This process is repeated until the triangle heights match the position of sea level above the sediment surface, at which time the remaining area of the sediment triangle is deposited seaward as a single wedge of offshore sediments. This simulation is designed to aid interpretation of stratigraphic sequences. It can be used as a complement to seismic stratigraphy or can be used alone as an inexpensive test of stratigraphic models.

  20. Imaging System For Measuring Macromolecule Crystal Growth Rates in Microgravity

    NASA Technical Reports Server (NTRS)

    Corder, Eric L.; Briscoe, Jeri

    2004-01-01

    In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, a team of scientists and engineers at NASA's Marshal Space Flight Center (MSFC) developed flight hardware capable of measuring the crystal growth rates of a population of crystals growing under the same conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of crystal over time, the hardware was named Delta-L. Delta-L consists of three sub assemblies: a fluid unit including a temperature-controlled growth cell, an imaging unit, and a control unit (consisting of a Data Acquisition and Control Unit (DACU), and a thermal control unit). Delta-L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station. This paper will describe the Delta-L imaging system. The Delta-L imaging system was designed to locate, resolve, and capture images of up to 10 individual crystals ranging in size from 10 to 500 microns with a point-to-point accuracy of +/- 2.0 microns within a quartz growth cell observation area of 20 mm x 10 mm x 1 mm. The optical imaging system is comprised of a video microscope camera mounted on computer controlled translation stages. The 3-axis translation stages and control units provide crewmembers the ability to search throughout the growth cell observation area for crystals forming in size of approximately 10 microns. Once the crewmember has selected ten crystals of interest, the growth of these crystals is tracked until the size reaches approximately 500 microns. In order to resolve these crystals an optical system with a magnification of 10X was designed. A black and white NTSC camera was utilized with a 20X microscope objective and a 0.5X custom designed relay lens with an inline light to meet the magnification requirement. The design allows a 500 pm

  1. Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

    PubMed

    Mauad, Cristiane R; Wagener, Angela de L R; Massone, Carlos G; Aniceto, Mayara da S; Lazzari, Letícia; Carreira, Renato S; Farias, Cássia de O

    2015-02-15

    Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement.

  2. Improvement of the operation rate of medical temperature measuring devices

    NASA Astrophysics Data System (ADS)

    Hotra, O.; Boyko, O.; Zyska, T.

    2014-08-01

    A method of reducing measuring time of temperature measurements of biological objects based on preheating the resistance temperature detector (RTD) up to the temperature close to the temperature to be measured, is proposed. It has been found that at the same measuring time, the preheating allows to decrease the measurement error by a factor of 5 to 45 over the temperature range of 35-41°С. The measurement time is reduced by 1.6-4 times over this range, keeping the same value of the measurement error.

  3. Measuring Cognitive Load with Subjective Rating Scales during Problem Solving: Differences between Immediate and Delayed Ratings

    ERIC Educational Resources Information Center

    Schmeck, Annett; Opfermann, Maria; van Gog, Tamara; Paas, Fred; Leutner, Detlev

    2015-01-01

    Subjective cognitive load (CL) rating scales are widely used in educational research. However, there are still some open questions regarding the point of time at which such scales should be applied. Whereas some studies apply rating scales directly after each step or task and use an average of these ratings, others assess CL only once after the…

  4. Adaptation of a speciation sampling cartridge for measuring ammonia flux from cattle feedlots using relaxed eddy accumulation

    NASA Astrophysics Data System (ADS)

    Baum, K. A.; Ham, J. M.

    Improved measurements of ammonia losses from cattle feedlots are needed to quantify the national NH 3 emissions inventory and evaluate management techniques for reducing emissions. Speciation cartridges composed of glass honeycomb denuders and filter packs were adapted to measure gaseous NH 3 and aerosol NH 4+ fluxes using relaxed eddy accumulation (REA). Laboratory testing showed that a cartridge equipped with four honeycomb denuders had a total capture capacity of 1800 μg of NH 3. In the field, a pair of cartridges was deployed adjacent to a sonic anemometer and an open-path gas analyzer on a mobile tower. High-speed valves were attached to the inlets of the cartridges and controlled by a datalogger so that up- and down-moving eddies were independently sampled based on direction of the vertical wind speed and a user-defined deadband. Air flowed continuously through the cartridges even when not sampling by means of a recirculating air handling system. Eddy covariance measurement of CO 2 and H 2O, as measured by the sonic and open-path gas analyzer, were used to determine the relaxation factor needed to compute REA-based fluxes. The REA system was field tested at the Beef Research Unit at Kansas State University in the summer and fall of 2007. Daytime NH 3 emissions ranged between 68 and 127 μg m -2 s -1; fluxes tended to follow a diurnal pattern correlated with latent heat flux. Daily fluxes of NH 3 were between 2.5 and 4.7 g m -2 d -1 and on average represented 38% of fed nitrogen. Aerosol NH 4+ fluxes were negligible compared with NH 3 emissions. An REA system designed around the high-capacity speciation cartridges can be used to measure NH 3 fluxes from cattle feedlots and other strong sources. The system could be adapted to measure fluxes of other gases and aerosols.

  5. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

    2012-01-01

    We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

  6. Denudation rates determined from the accumulation of in situ-produced 10Be in the luquillo experimental forest, Puerto Rico

    USGS Publications Warehouse

    Brown, Erik Thorson; Stallard, Robert F.; Larsen, Matthew C.; Raisbeck, Grant M.; Yiou, Francoise

    1995-01-01

    We present a simple method for estimation of long-term mean denudation rates using in situ-produced cosmogenic 10Be in fluvial sediments. Procedures are discussed to account for the effects of soil bioturbation, mass wasting and attenuation of cosmic rays by biomass and by local topography. Our analyses of 10Be in quartz from bedrock outcrops, soils, mass-wasting sites and riverine sediment from the Icacos River basin in the Luquillo Experimental Forest, Puerto Rico, are used to characterize denudation for major landform elements in that basin. The 10Be concentration of a discharge-weighted average of size classes of river sediment corresponds to a long-term average denudation of ≈ 43 m Ma −1, consistent with mass balance results. 

  7. A comparison of winter mercury accumulation at forested and no-canopy sites measured with different snow sampling techniques

    USGS Publications Warehouse

    Nelson, S.J.; Johnson, K.B.; Weathers, K.C.; Loftin, C.S.; Fernandez, I.J.; Kahl, J.S.; Krabbenhoft, D.P.

    2008-01-01

    Atmospheric mercury (Hg) is delivered to ecosystems via rain, snow, cloud/fog, and dry deposition. The importance of snow, especially snow that has passed through the forest canopy (throughfall), in delivering Hg to terrestrial ecosystems has received little attention in the literature. The snowpack is a dynamic system that links atmospheric deposition and ecosystem cycling through deposition and emission of deposited Hg. To examine the magnitude of Hg delivery via snowfall, and to illuminate processes affecting Hg flux to catchments during winter (cold season), Hg in snow in no-canopy areas and under forest canopies measured with four collection methods were compared: (1) Hg in wet precipitation as measured by the Mercury Deposition Network (MDN) for the site in Acadia National Park, Maine, USA, (2) event throughfall (collected after snowfall cessation for accumulations of >8 cm), (3) season-long throughfall collected using the same apparatus for event sampling but deployed for the entire cold season, and (4) snowpack sampling. Estimates (mean ?? SE) of Hg deposition using these methods during the 91-day cold season in 2004-2005 at conifer sites showed that season-long throughfall Hg flux (1.80 ??g/m2) < snowpack Hg (2.38 ?? 0.68 ??g/m2) < event throughfall flux (5.63 ?? 0.38 ??g/m2). Mercury deposition at the MDN site (0.91 ??g/m2) was similar to that measured at other no-canopy sites in the area using the other methods, but was 3.4 times less than was measured under conifer canopies using the event sampling regime. This indicates that snow accumulated under the forest canopy received Hg from the overstory or exhibited less re-emission of Hg deposited in snow relative to open areas. The soil surface of field-scale plots were sprayed with a natural rain water sample that contained an Hg tracer (202Hg) just prior to the first snowfall to explore whether some snowpack Hg might be explained from soil emissions. The appearance of the 202Hg tracer in the snowpack (0

  8. The Measurement of Self-Rated Depression: A Multidimensional Approach.

    ERIC Educational Resources Information Center

    Bolon, Kevin; Barling, Julian

    1980-01-01

    Investigates the capacity of the Zung Self-Rating Depression Scale for providing specific multidimensional descriptors of depressive behavior. Ideational, physiological and behavioral depression factors were evident in data from 96 normal, white university student volunteers. (Author/RH)

  9. A more direct measure of supernova rates in starburst galaxies

    NASA Technical Reports Server (NTRS)

    Van Buren, Dave; Greenhouse, Matthew A.

    1994-01-01

    We determine ages for young supernova remnants in the starburst galaxies M82 and NGC 253 by applying Chevalier's model for radio emission from supernova blast waves expanding into the ejecta of their precursor stars. Absolute ages are determined by calibrating the model with radio observations of Cas A. We derive supernova rates of 0.10 and 0.08/yr for M82 and NGC 253, respectively. Assuming L (sub FIR) to be proportional to the supernova rate, we find r(sub SN) approximately equal 2 x 10(exp -12) x L(sub FIR), solar yr(exp -1) for these archetypal starburst galaxies. This approach is unique in that the supernova rate is derived from direct observation of supernova remnants rather than from star formation rates and an assumed initial mass function (IMF). We suggest that the approach presented here can be used to derive star-formation rates that are more directly related to observable quantities than those derived by other methods. We find that the supernova rate, far infrared (FIR) luminosity, and dynamical mass of the M82 starburst place few constraints on the initial mass function (IMF) slope and mass limits.

  10. Locomotor response to exercise in relation to plasma lactate accumulation and heart rate in Andalusian and Anglo-Arabian horses.

    PubMed

    Muñoz, A; Santisteban, R; Rubio, M D; Riber, C; Agüera, E I; Castejón, F M

    1999-10-01

    To establish the effect of the locomotor pattern on heart rate (HR) and plasma lactate (LA), 28 horses, 18 Andalusian (AN) and 10 Anglo-Arabian (AA), aged 3-4 years, were studied. After a warm-up period, the horses performed a four-step test at 5, 6, 7 and 8 m/s, covering 1000 m at each velocity. HR was monitored, LA was analysed at rest and after each workload, and images were filmed. The locomotor parameters determined were stride duration (SD), frequency (SF) and length (SL), step and bipedal support durations, stance (restraint and propulsion) and swing phase durations, and stride vertical component. The HR and LA were significantly higher in the AN horses from velocities of 5 m/s. Similarly, the stride vertical component was higher in the AN horses at the trot and in the leading forelimbs at the gallop. Conversely, at all the galloping velocities, swing phase duration and stride length were longer in the AA horses. Significant correlations between HR, LA and locomotor pattern were only found in the AN horses. It was concluded that the greater stride vertical component in the AN horses limits SL and the cranial advancement of the hoof, with the result that reaching a longer SL triggers an increase in HR and LA. AA horses reach a balance between SL and SF, improving the efficiency of the gait.

  11. Partitioning and accumulation rates of polycyclic aromatic hydrocarbons into polydimethylsiloxane thin films and black worms from aqueous samples.

    PubMed

    Qin, Zhipei; Mok, Sandra; Ouyang, Gangfeng; Dixon, D George; Pawliszyn, Janusz

    2010-05-14

    Partition equilibriums and extraction rates of polycyclic aromatic hydrocarbons (PAHs) were examined for live biomonitoring with oligochaetes (black worms, Lumbriculus variegatus) and for high surface area chemical passive samplers constructed from polydimethylsiloxane thin film. The goals were to better understand the principles of bioconcentration by aquatic organisms and to aid in the design of a convenient and simple chemical monitoring tool to replace the use of live animals. The worms and films were exposed simultaneously to the contaminated water stream. In the initial extraction stage, similar extracted amount per surface area indicated that thin-film samplers could mimic the behavior of worms for passive sampling. Equilibrium was reached faster by the thin films than by the worms. A good linear relationship between the bioconcentration factors and the film-water partition coefficients of PAHs was found, which demonstrated the feasibility of thin-film sampler for determining the bioavailability of PAHs in water. Compared to the lengthy and inconvenient process of liquid-liquid extraction in worm treatment, thin-film technique simplifies the sample pretreatment procedure by integrating sampling and sample preparation.

  12. A Comparison of GHG Flux Measurements by Relaxed Eddy Accumulation and Eddy Covariance Methods Using FTIR and QCL Analyzers

    NASA Astrophysics Data System (ADS)

    Vermeulen, A. T.; Laborde, M.; Hensen, A.; van den Bulk, P.; Famulari, D.; Griffith, D. W.; Nemitz, E.

    2013-12-01

    In this presentation results obtained with a novel system for Relaxed Eddy Accumulation (REA) measurements using an Ecotech Spectronus FTIR analyzer (Griffth et al, 2012) will be compared to eddy covariance fluxes using an Aerodyne QCL and a Licor 6262 NDIR analyzer. The REA FTIR system can be easily combined with other standard (e.g. NDIR) analyzers suited for eddy covariance measurements to allow for scaling of the obtained up/down concentration differences with the directly measured fluxes. Furthermore the FTIR system allows for on-line simultaneous high precision concentration measurement of a large number of different gases and even isotope composition, next to the measurement of CO2, CH4 and N2O mixing ratios. The final design goal for the REA FTIR system is an attractive fully automated, low maintenance system for long-term monitoring of Greenhouse Gas fluxes at the hourly time scale and a spatial scale of about 1 km2. During a campaign of four weeks in June 2013 (in the framework of the InGOS EU project) at a grazed grassland site at Easter Bush, Scotland (UK), simultaneous surface flux measurements of N2O and additionally CO2 and CH4 have been performed using our systems and a number of setups from other groups.. Weather conditions during the campaign were excellent and after the application of fertilizer at the field and some rainfall the increased emission of N2O was detected clearly by all systems. Both the eddy covariance and REA methods performed well during the campaign and the measured fluxes compare satisfactorily. In general the resulting fluxes from the FTIR system are lower then the QCL based results. Reasons for these deviations will be discussed together with implications of the results for the design of future REA measurements using the FTIR system. Griffith, D.W.T., N.M. Deutscher, C.G.R. Caldow, G. Kettlewell, M. Riggenbach and S. Hammer, A Fourier transform infrared trace gas analyser for atmospheric applications. Atmospheric Measurement

  13. Field comparison of an eddy accumulation and an aerodynamic-gradient system for measuring pesticide volatilization fluxes

    USGS Publications Warehouse

    Majewski, M.; Desjardina, R.; Rochette, P.; Pattey, E.; Selber, J.; Glotfelty, D.

    1993-01-01

    The field experiment reported here applied the relaxed eddy accumulation (REA) technique to the measurement of triallate (TA) and trifluralin (TF) volatilization from fallow soil. A critical analysis of the REA system used in this experiment is done, and the fluxes are compared to those obtained by the aerodynamic-gradient (AG) technique. The measured cumulative volatilization losses, corrected for the effective upwind source area (footprint), for the AG system were higher than with the REA system. The differences between the methods over the first 5 days of the experiment were 27 and 13% for TA and TF, respectively. A mass balance based on the amount of parent compounds volatilized from soil during the first 5 days of the experiment showed a 110 and 70% and a 79 and 61% accountability for triallate and trifluralin by the AG and REA methods, respectively. These results also show that the non-footprint-corrected AG flux values underestimated the volatilization flux by approximately 16%. The footprint correction model used in this experiment does not presently have the capability of accounting for changes in atmospheric stability. However, these values still provide an indication of the most likely upwind area affecting the evaporative flux estimations. The soil half-lives for triallate and trifluralin were 9.8 and 7.0 days, respectively. ?? 1992 American Chemical Society.

  14. The Lima-Peru seismic gap: a study of inter-seismic strain accumulation from a decade of GPS measurements

    NASA Astrophysics Data System (ADS)

    Norabuena, E. O.; Pollitz, F. F.; Dixon, T. H.

    2013-05-01

    The Peruvian subduction zone between the Mendaña Fracture zone and Arica, northern Chile, has been source of large megathrust earthquakes since historical to present times, The two last major events affecting the southern segment corresponds to Arequipa 2001 (Mw 8.3) and Pisco 2007 (Mw 8.1). A noteworthy event is the Lima 1746 earthquake with an assigned magnitude of Mw 8.5 and which is assumed to have broken several km of the seismogenic zone off Lima. The great shock was followed by a devastating tsunami that destroyed the main port of Callao, killing about 99 percent of its population. This extreme event was followed by quiescence of a few hundred years until the XX century when the Lima subduction zone was broken again by the earthquakes of May 1940 (Mw 8.0), October 1966 (Mw 8.0) and Lima 1974 (Mw 8.0). The broken areas overlap partially with the estimated area of the 1746 earthquake and put the region in a state of seismic gap representing a major hazard for Lima city - Peru's capital and its about 9 million of inhabitants. Our study reports the interseismic strain accumulation derived from a decade of GPS measurement at 11 geodetic monuments including one measurement in an island 80 km offshore and models variations of coupling along the plate interface.

  15. Simultaneous measurement at multiple depths of in situ rates of denitrification in the bed of a groundwater-fed river

    NASA Astrophysics Data System (ADS)

    Lansdown, Katrina; Trimmer, Mark; Heppell, Kate

    2010-05-01

    Typically characterised by steep chemical gradients and variable redox conditions, the hyporheic zone is considered a 'hotpot' or site of enhanced biogeochemical activity in the aquatic environment. As such the importance of the hyporheic zone for the attenuation of nutrients such as nitrate in a fluvial network has long been recognised. Controls on nitrogen transformations, however, especially at depths greater than 10cm below the sediment-water interface, remain comparatively less understood. Most work aimed at quantifying denitrification in the hyporheic zone has involved laboratory incubation of recovered sediments which is likely to affect the estimate of the true in situ rate. Results of such studies are usually cited as 'potential' rates of denitrification and have undoubtedly improved the understanding of nitrogen cycling in the aquatic environment. There is, however, a need for in situ measurement to improve our knowledge of nitrogen cycling in the river bed. Here, rates of denitrification in the hyporheic zone have been measured at multiple depths, simultaneously using 'push-pull' methodology (e.g. Snodgrass and Kitanidis 1998). The 'push-pull' technique involves injection of a solution containing reactant(s) (e.g. nitrate) and a conservative tracer (e.g. chloride) into the sediment and extraction of pore water samples over time. Recovered samples are screened for the removal of reactant(s) and/or the accumulation of products(s). Temporal changes in the conservative tracer are used to correct the concentration of the reactant(s) and product(s) for dispersion and advection. The disadvantage of the 'traditional' 'push-pull' methodology is that rates of nitrate removal are measured rather than rates of denitrification. In this research, comparison of measured and 'corrected' nitrate concentrations allowed the rate of nitrate removal (or production) to be quantified. In order to determine in situ rates of denitrification we used 15N-enriched nitrate as the

  16. Accumulation of bone strontium measured by in vivo XRF in rats supplemented with strontium citrate and strontium ranelate.

    PubMed

    Wohl, Gregory R; Chettle, David R; Pejović-Milić, Ana; Druchok, Cheryl; Webber, Colin E; Adachi, Jonathan D; Beattie, Karen A

    2013-01-01

    Strontium ranelate is an approved pharmacotherapy for osteoporosis in Europe and Australia, but not in Canada or the United States. Strontium citrate, an alternative strontium salt, however, is available for purchase over-the-counter as a nutritional supplement. The effects of strontium citrate on bone are largely unknown. The study's objectives were 1) to quantify bone strontium accumulation in female Sprague Dawley rats administered strontium citrate (N=7) and compare these levels to rats administered strontium ranelate (N=6) and vehicle (N=6) over 8 weeks, and 2) to verify an in vivo X-ray fluorescence spectroscopy (XRF) system for measurement of bone strontium in the rat. Daily doses of strontium citrate and strontium ranelate were determined with the intention to achieve equivalent amounts of elemental strontium. However, post-hoc analyses of each strontium compound conducted using energy dispersive spectrometry microanalysis revealed a higher elemental strontium concentration in strontium citrate than strontium ranelate. Bone strontium levels were measured at baseline and 8 weeks follow-up using a unique in vivo XRF technique previously used in humans. XRF measurements were validated against ex vivo measurements of bone strontium using inductively coupled plasma mass spectrometry. Weight gain in rats in all three groups was equivalent over the study duration. A two-way ANOVA was conducted to compare bone strontium levels amongst the three groups. Bone strontium levels in rats administered strontium citrate were significantly greater (p<0.05) than rats administered strontium ranelate and vehicle. ANCOVA analyses were performed with Sr dose as a covariate to account for differences in strontium dosing. The ANCOVA revealed differences in bone strontium levels between the strontium groups were not significant, but that bone strontium levels were still very significantly greater than vehicle.

  17. Heat generation rate measurement in a Li-ion cell at large C-rates through temperature and heat flux measurements

    NASA Astrophysics Data System (ADS)

    Drake, S. J.; Martin, M.; Wetz, D. A.; Ostanek, J. K.; Miller, S. P.; Heinzel, J. M.; Jain, A.

    2015-07-01

    Understanding the rate of heat generation in a Li-ion cell is critical for safety and performance of Li-ion cells and systems. Cell performance, cycle life, and system safety all depend on temperature distribution in the cell, which, in turn, depends on heat generation rate within the cell and on heat removal rate at the cell surface. Despite the existence of a number of theoretical models to predict heat generation rate, there is not much literature on experimental measurement at high C-rates. This paper reports measurement of heat generation rate from a Li-ion cell at high discharge rates, up to 9.6C, using measurements of cell temperature and surface heat flux. As opposed to calorimetry-based approaches, this method can be applied in situ to yield measurements of heat generation rate in laboratory or field use provided that at least one a priori test is performed to measure the temperature gradient within a cell in the same ambient condition. This method is based on simultaneous determination of heat stored and heat lost from the cell through heat flux and temperature measurements. A novel method is established for measurement of the internal temperature of the cell. Heat generation measurements are shown to agree with well-established theoretical models. The effect of actively cooling the cell is briefly discussed.

  18. Estimating accumulation rates and physical properties of sediment behind a dam: Englebright Lake, Yuba River, northern California

    NASA Astrophysics Data System (ADS)

    Snyder, Noah P.; Rubin, David M.; Alpers, Charles N.; Childs, Jonathan R.; Curtis, Jennifer A.; Flint, Lorraine E.; Wright, Scott A.

    2004-11-01

    Studies of reservoir sedimentation are vital to understanding scientific and management issues related to watershed sediment budgets, depositional processes, reservoir operations, and dam decommissioning. Here we quantify the mass, organic content, and grain-size distribution of a reservoir deposit in northern California by two methods of extrapolating measurements of sediment physical properties from cores to the entire volume of impounded material. Englebright Dam, completed in 1940, is located on the Yuba River in the Sierra Nevada foothills. A research program is underway to assess the feasibility of introducing wild anadromous fish species to the river upstream of the dam. Possible management scenarios include removing or lowering the dam, which could cause downstream transport of stored sediment. In 2001 the volume of sediments deposited behind Englebright Dam occupied 25.5% of the original reservoir capacity. The physical properties of this deposit were calculated using data from a coring campaign that sampled the entire reservoir sediment thickness (6-32 m) at six locations in the downstream ˜3/4 of the reservoir. As a result, the sediment in the downstream part of the reservoir is well characterized, but in the coarse, upstream part of the reservoir, only surficial sediments were sampled, so calculations there are more uncertain. Extrapolation from one-dimensional vertical sections of sediment sampled in cores to entire three-dimensional volumes of the reservoir deposit is accomplished via two methods, using assumptions of variable and constant layer thickness. Overall, the two extrapolation methods yield nearly identical estimates of the mass of the reservoir deposit of ˜26 × 106 metric tons (t) of material, of which 64.7-68.5% is sand and gravel. Over the 61 year reservoir history this corresponds to a maximum basin-wide sediment yield of ˜340 t/km2/yr, assuming no contribution from upstream parts of the watershed impounded by other dams. The

  19. Estimating accumulation rates and physical properties of sediment behind a dam: Englebright Lake, Yuba River, northern California

    USGS Publications Warehouse

    Snyder, N.P.; Rubin, D.M.; Alpers, C.N.; Childs, J. R.; Curtis, J.A.; Flint, L.E.; Wright, S.A.

    2004-01-01

    Studies of reservoir sedimentation are vital to understanding scientific and management issues related to watershed sediment budgets, depositional processes, reservoir operations, and dam decommissioning. Here we quantify the mass, organic content, and grain-size distribution of a reservoir deposit in northern California by two methods of extrapolating measurements of sediment physical properties from cores to the entire volume of impounded material. Englebright Dam, completed in 1940, is located on the Yuba River in the Sierra Nevada foothills. A research program is underway to assess the feasibility of introducing wild anadromous fish species to the river upstream of the dam. Possible management scenarios include removing or lowering the dam, which could cause downstream transport of stored sediment. In 2001 the volume of sediments deposited behind Englebright Dam occupied 25.5% of the original reservoir capacity. The physical properties of this deposit were calculated using data from a coring campaign that sampled the entire reservoir sediment thickness (6–32 m) at six locations in the downstream ∼3/4 of the reservoir. As a result, the sediment in the downstream part of the reservoir is well characterized, but in the coarse, upstream part of the reservoir, only surficial sediments were sampled, so calculations there are more uncertain. Extrapolation from one-dimensional vertical sections of sediment sampled in cores to entire three-dimensional volumes of the reservoir deposit is accomplished via two methods, using assumptions of variable and constant layer thickness. Overall, the two extrapolation methods yield nearly identical estimates of the mass of the reservoir deposit of ∼26 × 106 metric tons (t) of material, of which 64.7–68.5% is sand and gravel. Over the 61 year reservoir history this corresponds to a maximum basin-wide sediment yield of ∼340 t/km2/yr, assuming no contribution from upstream parts of the watershed impounded by other dams. The

  20. MEASUREMENTS OF INFILTRATION RATES IN COMPACTED URBAN SOILS

    EPA Science Inventory

    Previous research hs identified significant reductions in infiltration rates in disturbed urban soils, More than 150 prior tests were conducted in predominately sandy and clayey urban soils in the Birmingham and Mobile, AL areas. Infiltration in Clayey soils ws found to be affect...

  1. Measuring the growth rate of structure around cosmic voids

    NASA Astrophysics Data System (ADS)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  2. Monoterpene emission rate measurements from a Monterey pine

    SciTech Connect

    Juuti, S. ); Arey, J.; Atkinson, R. )

    1990-05-20

    The monoterpenes emitted from a Monterey pine (pinus radiata) were investigated using a dynamic flow-through enclosure technique. The monoterpenes identified and quantified were {alpha}- and {beta}-pinene, d-limonene + {beta} phellandrene, myrcene, camphene and {Delta}{sup 3}-carene, with {alpha}- and {beta}-pinene accounting for over 80% of the total monoterpene emissions. The monoterpene emission rate increased with temperature, in good agreement with previous data for other coniferous species. The absence of added CO{sub 2} to the synthetic air flow stream, exposure to elevated levels (300-500 ppb mixing ratio) of O{sub 3} for 3-4 hours, and increased air movement within the enclosure, had no observable effect on the monoterpene emission rate at a given temperature. In contrast, rough handling of the pine during the sampling protocol resulted in increases in the monoterpene emission rate by factors of 10-50. These results will be useful to those designing enclosure sampling protocols for the determination of the emission rates of biogenic organic compounds from vegetation.

  3. Theoretical and Applied Implications of Precisely Measuring Learning Rates

    ERIC Educational Resources Information Center

    Skinner, Christopher H.

    2008-01-01

    Nist and Joseph (2008) have confirmed earlier research showing that adding and interspersing a large number of time-consuming learning trials targeting known items (e.g., incremental rehearsal (IR) or interspersal) retards student learning rates. In addition, their current study has confirmed earlier research that adding and interspersing known…

  4. Accumulate-Repeat-Accumulate-Accumulate Codes

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Dolinar, Samuel; Thorpe, Jeremy

    2007-01-01

    Accumulate-repeat-accumulate-accumulate (ARAA) codes have been proposed, inspired by the recently proposed accumulate-repeat-accumulate (ARA) codes. These are error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels. ARAA codes can be regarded as serial turbolike codes or as a subclass of low-density parity-check (LDPC) codes, and, like ARA codes they have projected graph or protograph representations; these characteristics make it possible to design high-speed iterative decoders that utilize belief-propagation algorithms. The objective in proposing ARAA codes as a subclass of ARA codes was to enhance the error-floor performance of ARA codes while maintaining simple encoding structures and low maximum variable node degree.

  5. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, J. D.; Temi, P.; Rank, D.

    2000-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short enough times that many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extinction is especially severe. Thus, determining the supernova rate in active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micrometer emission line was the strongest line in the infrared spectrum for a period of a year and half after th explosion. Since dust extinction is much less at 6.63 micrometers than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the [NiII] line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micrometers using ISOCAM to search for the [NiII] emission line characteristic of recent supernovae. We did not detect any [NiII] line emission brighter than a 5-sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled ot the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a [NiII] line with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a [NiII] line luminosity greater than the line in SN1987A.

  6. Direct Measurement of the Supernova Rate in Starburst Galaxies

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Temi, Pasquale; Rank, David; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.

  7. Ozone Production and Loss Rate Measurements in the Middle Stratosphere

    NASA Technical Reports Server (NTRS)

    Jucks, Kenneth W.; Johnson, David G.; Chance, K. V.; Traub, Wesley A.; Salawitch, R. J.; Stachnik, R. A.

    1996-01-01

    The first simultaneous measurements of HO(x), NO(x), and Cl(x) radicals in the middle stratosphere show that NO(x) catalytic cycles dominate loss of ozone (O3) for altitudes between 24 and 38 km; Cl(x) catalytic cycles are measured to be less effective than previously expected; and there is no 'ozone deficit' in the photochemically dominated altitude range from 31 and 38 km, contrary to some previous theoretical studies.

  8. Increased zinc accumulation in mineralized osteosarcoma tissue measured by confocal synchrotron radiation micro X‐ray fluorescence analysis

    PubMed Central

    Pemmer, Bernhard; Roschger, Andreas; Turyanskaya, Anna; Smolek, Stephan; Maderitsch, Angelika; Hischenhuber, Peter; Foelser, Martin; Simon, Rolf; Lang, Susanna; Puchner, Stephan E.; Windhager, Reinhard; Klaushofer, Klaus; Wobrauschek, Peter; Hofstaetter, Jochen G.; Roschger, Paul; Streli, Christina

    2016-01-01

    Abnormal tissue levels of certain trace elements such as zinc (Zn) were reported in various types of cancer. Little is known about the role of Zn in osteosarcoma. Using confocal synchrotron radiation micro X‐ray fluorescence analysis, we characterized the spatial distribution of Zn in high‐grade sclerosing osteosarcoma of nine patients (four women/five men; seven knee/one humerus/one femur) following chemotherapy and wide surgical resection. Levels were compared with adjacent normal tissue. Quantitative backscattered electron imaging as well as histological examinations was also performed. On average, the ratio of medians of Zn count rates (normalized to calcium) in mineralized tumor tissue was about six times higher than in normal tissue. There was no difference in Zn levels between tumor fraction areas with a low fraction and a high fraction of mineralized tissue, which were clearly depicted using quantitative backscattered electron imaging. Moreover, we found no correlation between the Zn values and the type of tumor regression according to the Salzer‐Kuntschik grading. The underlying mechanism of Zn accumulation remains unclear. Given the emerging data on the role of trace elements in other types of cancer, our novel results warrant further studies on the role of trace elements in bone cancer. Copyright © 2016 The Authors. X‐Ray Spectrometry published by John Wiley & Sons Ltd. PMID:28239202

  9. Glaciation in the Late Noachian Icy Highlands: Ice accumulation, distribution, flow rates, basal melting, and top-down melting rates and patterns

    NASA Astrophysics Data System (ADS)

    Fastook, James L.; Head, James W.

    2015-02-01

    Geological evidence for extensive non-polar ice deposits of Amazonian age indicates that the current cold and dry climate of Mars has persisted for several billion years. The geological record and climate history of the Noachian, the earliest period of Mars history, is less certain, but abundant evidence for fluvial channels (valley networks) and lacustrine environments (open-basin lakes) has been interpreted to represent warm and wet conditions, including rainfall and runoff. Alternatively, recent atmospheric modeling results predict a "cold and icy" Late Noachian Mars in which moderate atmospheric pressure accompanied by a full water cycle produce an atmosphere where temperature declines with elevation following an adiabatic lapse rate, in contrast to the current situation on Mars, where temperature is almost completely determined by latitude. These results are formulated in the Late Noachian Icy Highlands (LNIH) model, in which these cold and icy conditions lead to the preferential deposition of snow and ice at high elevations, such as the southern uplands. What is the fate of this snow and ice and the nature of glaciation in such an environment? What are the prospects of melting of these deposits contributing to the observed fluvial and lacustrine deposits? To address these questions, we report on a glacial flow-modeling analysis using a Mars-adapted ice sheet model with LNIH climate conditions. The total surface/near-surface water inventory is poorly known for the Late Noachian, so we explore the LNIH model in a "supply-limited" scenario for a range of available water abundances and a range of Late Noachian geothermal fluxes. Our results predict that the Late Noachian icy highlands (above an equilibrium line altitude of approximately +1 km) were characterized by extensive ice sheets of the order of hundreds of meters thick. Due to extremely cold conditions, the ice-flow velocities in general were very low, less than a few mm/yr, and the regional ice

  10. Measurement of generation-dependent proliferation rates and death rates during mouse erythroid progenitor cell differentiation.

    PubMed

    Akbarian, Vahe; Wang, Weijia; Audet, Julie

    2012-05-01

    Herein, we describe an experimental and computational approach to perform quantitative carboxyfluorescein diacetate succinimidyl ester (CFSE) cell-division tracking in cultures of primary colony-forming unit-erythroid (CFU-E) cells, a hematopoietic progenitor cell type, which is an important target for the treatment of blood disorders and for the manufacture of red blood cells. CFSE labeling of CFU-Es isolated from mouse fetal livers was performed to examine the effects of stem cell factor (SCF) and erythropoietin (EPO) in culture. We used a dynamic model of proliferation based on the Smith-Martin representation of the cell cycle to extract proliferation rates and death rates from CFSE time-series. However, we found that to accurately represent the cell population dynamics in differentiation cultures of CFU-Es, it was necessary to develop a model with generation-specific rate parameters. The generation-specific rates of proliferation and death were extracted for six generations (G(0) -G(5) ) and they revealed that, although SCF alone or EPO alone supported similar total cell outputs in culture, stimulation with EPO resulted in significantly higher proliferation rates from G(2) to G(5) and higher death rates in G(2) , G(3) , and G(5) compared with SCF. In addition, proliferation rates tended to increase from G(1) to G(5) in cultures supplemented with EPO and EPO + SCF, while they remained lower and more constant across generations with SCF. The results are consistent with the notion that SCF promotes CFU-E self-renewal while EPO promotes CFU-E differentiation in culture.

  11. Four-year measurement of methane flux over a temperate forest with a relaxed eddy accumulation method

    NASA Astrophysics Data System (ADS)

    Sakabe, A.; Kosugi, Y.; Ueyama, M.; Hamotani, K.; Takahashi, K.; Iwata, H.; Itoh, M.

    2013-12-01

    Forests are generally assumed to be an atmospheric methane (CH4) sink (Le Mer and Roger, 2001). However, under Asian monsoon climate, forests are subject to wide spatiotemporal range in soil water status, where forest soils often became water-saturated condition heterogeneously. In such warm and humid conditions, forests may act as a CH4 source and/or sink with considerable spatiotemporal variations. Micrometeorological methods such as eddy covariance (EC) method continuously measure spatially-representative flux at a canopy scale without artificial disturbance. In this study, we measured CH4 fluxes over a temperate forest during four-year period using a CH4 analyzer based on tunable diode laser spectroscopy detection with a relaxed eddy accumulation (REA) method (Hamotani et al., 1996, 2001). We revealed the amplitude and seasonal variations of canopy-scale CH4 fluxes. The REA method is the attractive alternative to the EC method to measure trace-gas flux because it allows the use of analyzers with an optimal integration time. We also conducted continuous chamber measurements on forest floor to reveal spatial variations in soil CH4 fluxes and its controlling processes. The observations were made in an evergreen coniferous forest in central Japan. The site has a warm temperate monsoon climate with wet summer. Some wetlands were located in riparian zones along streams within the flux footprint area. For the REA method, the sonic anemometer (SAT-550, Kaijo) was mounted on top of the 29-m-tall tower and air was sampled from just below the sonic anemometer to reservoirs according to the direction of vertical wind velocity (w). After accumulating air for 30 minutes, the air in the reservoirs was pulled into a CO2/H2O gas analyzer (LI-840, Li-Cor) and a CH4 analyzer (FMA-200, Los Gatos Research). Before entering the analyzers, the sampled air was dried using a gas dryer (PD-50 T-48; Perma Pure Inc.). The REA flux is obtained from the difference in the mean concentrations

  12. Carbonic anhydrase activity and photosynthetic rate in the tree species Paulownia tomentosa Steud. Effect of dimethylsulfoxide treatment and zinc accumulation in leaves.

    PubMed

    Lazova, Galia N; Naidenova, Tsveta; Velinova, Katya

    2004-03-01

    The enzyme carbonic anhydrase (CA) (EC 4.2.1.1) catalyzes the reversible conversion of CO2 to HCO3- and has been shown to be involved in photosynthesis. The enzyme has been shown in animals, plants, eubacteria and viruses, but similar reports on the evidence for CA activity in tree plants does not be appear to be available. In the preliminary analyses of the work, the CA activity in leaf extracts from the tree species Paulownia tomentosa Steud. (introduced in Bulgaria) is described. A connection between CA activity and the rate of photosynthetic CO2 fixation is shown. In the second portion of the work, the effect of 10(-4) mol/L and 10(-2) mol/L dimethylsulfoxide (DMSO) on the zinc accumulation in leaves is demonstrated. It is suggested that CA activity is an indicator of the level of physiologically active zinc in leaves of P. tomentosa Steud. A connection between the process of zinc accumulation in leaves and the activity of the enzymes CA and glycolate oxidase (GO) (EC 1.1.3.1) is established.

  13. Outcome Rating Scale and Session Rating Scale in Psychological Practice: Clinical Utility of Ultra-Brief Measures

    ERIC Educational Resources Information Center

    Campbell, Alistair; Hemsley, Samantha

    2009-01-01

    The validity and reliability of the Outcome Rating Scale (ORS) and the Session Rating Scale (SRS) were evaluated against existing longer measures, including the Outcome Questionnaire-45, Working Alliance Inventory, Depression Anxiety Stress Scale-21, Quality of Life Scale, Rosenberg Self-Esteem Scale and General Self-efficacy Scale. The measures…

  14. A single-injection method for measuring glomerular filtration rate.

    PubMed

    Hall, J E; Guyton, A C; Farr, B M

    1977-01-01

    A method for estimating glomerular filtration rate (GFR) has been developed that is based on an analysis of the total area under the plasma radioactivity-time curve after a single intravenous injection of [125I]iothalamate. Glomerular filtration rates obtained by this method (method A) and those obtained with two widely used single-injection techniques, the slope-intercept method (method B), and the two-compartment method (method C), were compared with GFRs obtained by standard inulin clearance techniques in 14 dogs. Method B consistently over. estimated inulin clearances more than 30%. Method C also overestimated inulin clearance considerably in dogs with an increased extracellular fluid volume, but was fairly reliable in normal dogs. Glomerular filtration rates obtained by the new method (method A) were in excellent agreement with inulin clearances in all dogs, regardless of the state of body hydration. The mean inulin clearance for all 14 experiments was 72.7+/-6.0 SE ml/min, while GFRs obtained by method A averaged 75.1+/-6.0 ml/min. The data from this study suggest that method A is a reliable means for estimating GFR that is especially useful in chronic experiments.

  15. Measurement of glomerular filtration rate using inulin prepared from Vernonia herbacea, a Brazilian native species.

    PubMed

    Dias-Tagliacozzo, G M; Dietrich, S M; Mello-Aires, M

    1996-10-01

    Vernonia herbacea (Vell.) Rusby (Asteraceae) is a perennial herb native to the cerrado vegetation of tropical areas in Brazil, which accumulates inulin in the underground reserve organs. The aim of this paper was to determine whether the inulin extracted from V. herbacea could replace commercial inulin for the measurement of glomerular filtration rate (GFR). Underground organs of vegetative plants were collected from a preserved area of the Brazilian cerrado. The inulin fraction utilized was obtained by ethanol precipitation after discarding the high molecular mass fructans in the freeze-thawing precipitate. GFR was determined in male Wistar rats anesthetized with inactin (100 mg/kg), which received intravenously commercial inulin obtained from Dahlia sp (Sigma) or Vernonia herbacea inulin (30 mg/100 g) as a priming dose and 0.05 mg min-1 100 g-1 as a sustaining dose in isotonic saline at the rate of 0/055 ml/min. Clearance was determined during 3 periods, with urine collected from the bladder and blood from the carotid artery. There was no significant difference in the GFR measured by clearance in inulin from both sources even when the plasma concentration of inulin from V. herbacea was doubled. The mean arterial pressure did not vary after the application of both inulins, indicating that they do not produce systemic side effects. The filtered load and the excreted amount of inulin from V. herbacea were equal, showing that the substance is not influenced by tubular function. These results demonstrate that the inulin from V. herbacea can substitute for imported inulin for the determination of GFR and in experiments of kidney microperfusion as a marker of tubular water reabsorption.

  16. Variance in Broad Reading Accounted for by Measures of Reading Speed Embedded within Maze and Comprehension Rate Measures

    ERIC Educational Resources Information Center

    Hale, Andrea D.; Skinner, Christopher H.; Wilhoit, Brian; Ciancio, Dennis; Morrow, Jennifer A.

    2012-01-01

    Maze and reading comprehension rate measures are calculated by using measures of reading speed and measures of accuracy (i.e., correctly selected words or answers). In sixth- and seventh-grade samples, we found that the measures of reading speed embedded within our Maze measures accounted for 50% and 39% of broad reading score (BRS) variance,…

  17. The influence of structural features of marine humic substances on the accumulation rates of cadmium by a blue mussel Mytilus edulis

    SciTech Connect

    Pempkowiak, J.; Kozuch, J. ); Southon, T. )

    1994-01-01

    Laboratory experiments revealed that both concentration and origin of humic substances (HS) influence the accumulation rates of cadmium by the blue mussel Mytilus edulis. In the concentration of humic substances typical of seawater, the increase is about 60% and 100%, respectively, for aquatic and sedimentary humic substances. The phenomenon was attributed to the stimulation of cadmium uptake due to complexing properties of the substances toward cadmium. Complexing capacity of sedimentary humic substances was found to be 0.57 [mu]g/mg HS, that of aquatic substances 0.41 [mu]g/mg HS. Cross Polarization Magic Angle Spinning (CP/MAS) [sup 13]C NMR of the investigated humic substances revealed differences in the spectra at about 175, 100, 55 and 32 ppm. This was attributed to the varying content of oxygen containing functional groups involved in formation of complexes with metal ions. 8 refs., 4 figs., 3 tabs.

  18. Performance assessment of a commonly used "accumulation and wash-off" model from long-term continuous road runoff turbidity measurements.

    PubMed

    Sage, Jérémie; Bonhomme, Céline; Al Ali, Saja; Gromaire, Marie-Christine

    2015-07-01

    The suitability of a commonly used accumulation and wash-off model for continuous modelling of urban runoff contamination was evaluated based on 11-month turbidity and flow-rate records from an urban street. Calibration and uncertainty analysis were performed using a Markov Chain Monte-Carlo sampling method for both suspended solids loads (discharge rates) and concentration modelling. Selected models failed at replicating suspended solids concentration over the complete monitoring period. The studied dataset indeed suggests that the accumulation process is rather unpredictable and cannot be satisfactorily represented with usual accumulation models unless short periods are considered. Regarding suspended solid loads modelling, noticeably better performance was achieved, but similar results could as well be obtained with much simpler constant concentration models. Unless providing very accurate estimates of concentrations in runoff, accounting for their temporal variability during rain events may therefore not always be necessary for pollutant loads modelling, as loads are in fact mostly explained by runoff volumes.

  19. The “accumulation effect” of positrons in the stack of foils, detected by measurements of the positron implantation profile

    SciTech Connect

    Dryzek, Jerzy; Siemek, Krzysztof

    2013-12-14

    The profiles of positrons implanted from the radioactive source {sup 22}Na into a stack of foils and plates are the subject of our experimental and theoretical studies. The measurements were performed using the depth scanning of positron implantation profile method, and the theoretical calculations using the phenomenological multi-scattering model (MSM). Several stacks consisting of silver, gold and aluminum foils, and titanium and germanium plates were investigated. We notice that the MSM describes well the experimental profiles; however when the stack consisting of silver and gold foils, the backscattering and linear absorption coefficients differ significantly from those reported in the literature. We suggest the energy dependency of the backscattering coefficient for silver and gold. In the stacks which comprise titanium and germanium plates, there were observed the features, which indicate the presence of the “accumulation effect” in the experimental implantation profile. This effect was previously detected in implantation profiles in Monte Carlo simulations using the GEANT4 tool kit, and it consists in higher localization of positrons close the interface. We suppose that this effect can be essential for positron annihilation in any heterogeneous materials.

  20. Long-term measurement of terpenoid flux above a Larix kaempferi forest using a relaxed eddy accumulation method

    NASA Astrophysics Data System (ADS)

    Mochizuki, Tomoki; Tani, Akira; Takahashi, Yoshiyuki; Saigusa, Nobuko; Ueyama, Masahito

    2014-02-01

    Terpenoids emitted from forests contribute to the formation of secondary organic aerosols and affect the carbon budgets of forest ecosystems. To investigate seasonal variation in terpenoid flux involved in the aerosol formation and carbon budget, we measured the terpenoid flux of a Larix kaempferi forest between May 2011 and May 2012 by using a relaxed eddy accumulation method. Isoprene was emitted from a fern plant species Dryopteris crassirhizoma on the forest floor and monoterpenes from the L. kaempferi. α-Pinene was the dominant compound, but seasonal variation of the monoterpene composition was observed. High isoprene and monoterpene fluxes were observed in July and August. The total monoterpene flux was dependent on temperature, but several unusual high positive fluxes were observed after rain fall events. We found a good correlation between total monoterpene flux and volumetric soil water content (r = 0.88), and used this correlation to estimate monoterpene flux after rain events and calculate annual terpenoid emissions. Annual carbon emission in the form of total monoterpenes plus isoprene was determined to be 0.93% of the net ecosystem exchange. If we do not consider the effect of rain fall, carbon emissions may be underestimated by about 50%. Our results suggest that moisture conditions in the forest soil is a key factor controlling the monoterpene emissions from the forest ecosystem.

  1. Measurement of fracture properties of concrete at high strain rates.

    PubMed

    Rey-De-Pedraza, V; Cendón, D A; Sánchez-Gálvez, V; Gálvez, F

    2017-01-28

    An analysis of the spalling technique of concrete bars using the modified Hopkinson bar was carried out. A new experimental configuration is proposed adding some variations to previous works. An increased length for concrete specimens was chosen and finite-element analysis was used for designing a conic projectile to obtain a suitable triangular impulse wave. The aim of this initial work is to establish an experimental framework which allows a simple and direct analysis of concrete subjected to high strain rates. The efforts and configuration of these primary tests, as well as the selected geometry and dimensions for the different elements, have been focused to achieve a simple way of identifying the fracture position and so the tensile strength of tested specimens. This dynamic tensile strength can be easily compared with previous values published in literature giving an idea of the accuracy of the method and technique proposed and the possibility to extend it in a near future to obtain other mechanical properties such as the fracture energy. The tests were instrumented with strain gauges, accelerometers and high-speed camera in order to validate the results by different ways. Results of the dynamic tensile strength of the tested concrete are presented.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  2. Measurement of fracture properties of concrete at high strain rates

    NASA Astrophysics Data System (ADS)

    Rey-De-Pedraza, V.; Cendón, D. A.; Sánchez-Gálvez, V.; Gálvez, F.

    2017-01-01

    An analysis of the spalling technique of concrete bars using the modified Hopkinson bar was carried out. A new experimental configuration is proposed adding some variations to previous works. An increased length for concrete specimens was chosen and finite-element analysis was used for designing a conic projectile to obtain a suitable triangular impulse wave. The aim of this initial work is to establish an experimental framework which allows a simple and direct analysis of concrete subjected to high strain rates. The efforts and configuration of these primary tests, as well as the selected geometry and dimensions for the different elements, have been focused to achieve a simple way of identifying the fracture position and so the tensile strength of tested specimens. This dynamic tensile strength can be easily compared with previous values published in literature giving an idea of the accuracy of the method and technique proposed and the possibility to extend it in a near future to obtain other mechanical properties such as the fracture energy. The tests were instrumented with strain gauges, accelerometers and high-speed camera in order to validate the results by different ways. Results of the dynamic tensile strength of the tested concrete are presented. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  3. Biogeochemical cycling in an organic-rich coastal marine basin: 9. Sources and accumulation rates of vascular plant-derived organic material

    NASA Astrophysics Data System (ADS)

    Haddad, Robert I.; Martens, Christopher S.

    1987-11-01

    The sources, degradation and burial of vascular plant debris deposited over the past several decades in the lagoonal sediments of Cape Lookout Bight, North Carolina, are quantified using alkaline cupric oxide lignin oxidation product (LOP) analysis. Non-woody angiosperms, accounting for 92 ± 32% of the recognizable sedimentary vascular plant debris, are calculated to contribute 23 ± 17% of the total organic carbon buried over the past decade (upper meter of sediment column). When combined with a previously established sedimentary organic carbon budget for this site (Martens and Klump, 1984; Martens et al., 1987, in preparation) a vascular plant derived carbon burial rate of 26 ± 20 mole C m -2 yr -1 is calculated for this same time interval. The refractory nature and invariant depth distributions of the lignin oxidation products (LOP), when coupled with evidence for constant degradation rates of metabolizable materials, indicate that sediment accumulation at this site has been a steady state process with respect to source and burial of organic carbon since its conversion from an inner-continental shelf to a lagoonal environment during the late 1960's. Thus systematic down-core decreases in labile organic matter result from early diagenetic processes rather than input rate variations.

  4. Development of a scale to measure individuals’ ratings of peace

    PubMed Central

    2014-01-01

    Background The evolving concept of peace-building and the interplay between peace and health is examined in many venues, including at the World Health Assembly. However, without a metric to determine effectiveness of intervention programs all efforts are prone to subjective assessment. This paper develops a psychometric index that lays the foundation for measuring community peace stemming from intervention programs. Methods After developing a working definition of ‘peace’ and delineating a Peace Evaluation Across Cultures and Environments (PEACE) scale with seven constructs comprised of 71 items, a beta version of the index was pilot-tested. Two hundred and fifty subjects in three sites in the U.S. were studied using a five-point Likert scale to evaluate the psychometric functioning of the PEACE scale. Known groups validation was performed using the SOS-10. In addition, test-retest reliability was performed on 20 subjects. Results The preliminary data demonstrated that the scale has acceptable psychometric properties for measuring an individual’s level of peacefulness. The study also provides reliability and validity data for the scale. The data demonstrated internal consistency, correlation between data and psychological well-being, and test-retest reliability. Conclusions The PEACE scale may serve as a novel assessment tool in the health sector and be valuable in monitoring and evaluating the peace-building impact of health initiatives in conflict-affected regions. PMID:25298781

  5. A New Method for Flow Rate Measurement in Millimeter-Scale Pipes

    PubMed Central

    Ji, Haifeng; Gao, Xuemin; Wang, Baoliang; Huang, Zhiyao; Li, Haiqing

    2013-01-01

    Combining the Capacitively Coupled Contactless Conductivity Detection (C4D) technique and the principle of cross correlation flow measurement, a new method for flow rate measurement in millimeter-scale pipes was proposed. The research work included two parts. First, a new five-electrode C4D sensor was developed. Second, with two conductivity signals obtained by the developed sensor, the flow rate measurement was implemented by using the principle of cross correlation flow measurement. The experimental results showed that the proposed flow rate measurement method was effective, the developed five-electrode C4D sensor was successful, and the measurement accuracy was satisfactory. In five millimeter-scale pipes with different inner diameters of 0.5, 0.8, 1.8, 3.0 and 3.9 mm respectively, the maximum relative difference of the flow rate measurement between the reference flow rate and the measured flow rate was less than 5%. PMID:23353139

  6. Neutron detector for fusion reaction-rate measurements

    SciTech Connect

    Lerche, R.A.; Phillion, D.W.; Tietbohl, G.L.

    1993-09-03

    We have developed a fast, sensitive neutron detector for recording the fusion reaction-rate history of inertial-confinement fusion (ICF) experiments. The detector is based on the fast rise-time of a commercial plastic scintillator (BC-422) and has a response < 25-ps FWHM. A thin piece of scintillator material acts as a neutron-to- light converter. A zoom lens images light from the scintillator surface to a high-speed (15 ps) optical streak camera for recording. The zoom lens allows the scintillator to be positioned between 1 and 50 cm from a target. The camera simulaneously records an optical fiducial pulse which allows the camera time base to be calibrated relative to the incident laser power. Bursts of x rays formed by focusing 20-ps, 2.5-TW laser pulses onto gold disk targets demonstrate the detector resolution to be < 25 ps. We have recorded burn histories for deuterium/tritium-filled targets producing as few as 3 {times} 10{sup 7} neutrons.

  7. Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

    PubMed

    Zhou, Xiaowei; Xia, Chunming; Stephen, Gandy; Khan, Faisel; Corner, George A; Hoskins, Peter R; Huang, Zhihong

    2017-02-21

    Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors.

  8. Measuring evaporation rates of metal compounds from solid samples.

    PubMed

    Ludwig, Christian; Wochele, Jörg; Jörimann, Urs

    2007-04-01

    A thermogravimeter (TGA, Mettler-Toledo TGA/SDTA851e) was connected to an inductively coupled plasma optical emission spectrometer (ICP-OES, Varian Liberty 110) using a condensation interface (CI), which transforms gaseous high-boiling-temperature substances into solid (or liquid) aerosols. Argon was used as the carrier gas to transfer the aerosols into the ICP-OES for on-line elemental analysis. This new analytical TGA-CI-ICP-OES device, called TGA-ICP, is the first of its kind and allows one to study the thermochemically induced evaporation behavior of high-boiling-temperature substances, such as heavy metal compounds, under different thermochemical conditions. It allows the investigation of the behavior of large solid or liquid samples (100-500 mg), which is important for applying the results to industrial processes. So far, the CI principle has allowed only semiquantitative elemental analyses of hot gases when connected to an ICP-OES. In this work, we show that a direct calibration of the CI-ICP-OES device is possible in combination with a TGA. The intensities determined by ICP-OES could be directly related to gravimetrically determined evaporation rates of volatile model compounds. The results show model evaporation experiments with native CdCl2 and CdCl2 resulting from the reaction of CaCl2 with CdO. Cadmium was studied because it is a volatile toxic heavy metal and its thermal behavior is relevant in various waste-treatment and recycling processes.

  9. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-12-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1 with a standard deviation of 2.2), tropical forest (n = 19, FC = 126 ± 77), temperate forest (n = 12, FC = 58 ± 72), boreal forest (n = 16, FC = 35 ± 24), pasture (n = 4, FC = 28 ± 9.3), shifting cultivation (n = 2, FC = 23, with a range of 4.0-43), crop residue (n = 4, FC = 6.5 ± 9.0), chaparral (n = 3, FC = 27 ± 19), tropical peatland (n = 4, FC = 314 ± 196), boreal peatland (n = 2, FC = 42 [42-43]), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole

  10. Measurements of Heart Rate and Accelerometry to Determine the Physical Activity Level in Boys Playing Paintball

    PubMed Central

    JARVI, MICHELLE; BROWN, GREGORY A; SHAW, BRANDON S.; SHAW, INA

    2013-01-01

    Paintball is a popular recreational sport played by 3.655 million Americans and may be sufficient physical activity to promote health. Paintball has been played as an organized sport since the 1980’s and is essentially a game of tag, except instead of touching an opponent by hand opponents are tagged by shooting them with a paintball that leaves a mark indicating who has been eliminated. A previous evaluation of paintball as physical activity had 13 subjects undergo a VO2max test to develop a heart rate (HR) /oxygen consumption relationship, and it was observed that heart rates during paintball were 68–73% of the measured maximal HR. The present study used accelerometry and HR monitors to evaluate the quantity and intensity of physical activity in boys playing paintball. Eleven boys (12.7 ± 1.0 y, 51.5 ± 11.3 kg, 161.8 ± 10.1 cm) engaged in a VO2max test to develop a HR/oxygen consumption correlation. On a separate day the boys played 7 games of outdoor paintball while wearing a HR monitor and accelerometer. The boys played paintball for 11.5 ± 6.2 minutes/game for a total of 80.6 ± 10.0 minutes of game play. Average HR during paintball play was 129.6 ± 6.6 beats/min, representing 39.9 ± 12.9% VO2max. Based on accelerometry, the boys accumulated 63.2 ± 15.6 minutes of moderate intensity activity and 2.6 ± 2.8 minutes of vigorous activity during paintball. These data suggest that playing paintball may be considered as physical activity that is > 3 METs, and thus health promoting. PMID:27182396

  11. Accretion rate of cosmic spherules measured at the South Pole

    NASA Astrophysics Data System (ADS)

    Taylor, Susan; Lever, James H.; Harvey, Ralph P.

    1998-04-01

    Micrometeorites are terrestrially collected, extraterrestrial particles smaller than about 1mm, which account for most of the mass being accreted to the Earth,. Compared with meteorites, micrometeorites more completely represent the Earth-crossing meteoroid complex, and should include fragments of asteroids, comets, Mars and our Moon, as well as pre-solar and interstellar grains,. Previous measurements of the flux of micrometeoroids that survive to the Earth's surface have large uncertainties owing to the destruction of particles by weathering, inefficiencies in magnetic collection or separation techniques, low particle counts,, poor age constraint,, or highly variable concentrating processes,. Here we describe an attempt to circumvent these problems through the collection of thousands of well preserved and dated micrometeorites from the bottom of the South Pole water well, which supplies drinking water for the Scott-Amundsen station. Using this collection, we have determined precise estimates of the flux and mass distribution for 50-700-µm cosmic spherules (melted micrometeorites). Allowing for the expected abundance of unmelted micrometeorites in the samples, our results indicate that about 90% of the incoming mass of submillimetre particles evaporates during atmospheric entry. Our data indicate the loss of glass-rich and small stony spherules from deep-sea deposits,, and they provide constraints for models describing the survival probability of micrometeoroids,.

  12. Late Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation

    USGS Publications Warehouse

    Normark, W.R.; McGann, M.; Sliter, R.W.

    2009-01-01

    An evaluation of the geologic hazards of the inner California Borderland requires determination of the timing for faulting and mass-movement episodes during the Holocene. Our effort focused on basin slopes and turbidite systems on the basin floors for the area between Santa Barbara and San Diego, California. Dating condensed sections on slopes adjacent to fault zones provides better control on fault history where high-resolution, seismic-reflection data can be used to correlate sediment between the core site and the fault zones. This study reports and interprets 147 radiocarbon dates from 43 U.S. Geological Survey piston cores as well as 11 dates from Ocean Drilling Program Site 1015 on the floor of Santa Monica Basin. One hundred nineteen dates from 39 of the piston cores have not previously been published. Core locations were selected for hazard evaluation, but despite the nonuniform distribution of sample locations, the dates obtained for the late Quaternary deposits are useful for documenting changes in sediment-accumulation rates during the past 30 ka. Cores from basins receiving substantial sediment from rivers, i.e., Santa Monica Basin and the Gulf of Santa Catalina, show a decrease in sediment supply during the middle Holocene, but during the late Holocene after sea level had reached the current highstand condition, rates then increased partly in response to an increase in El Ni??o-Southern Oscillation events during the past 3.5 ka. ?? 2009 The Geological Society of America.

  13. Prediction of Heart Rates on a Ropes Course from Simple Physical Measures. Research Update.

    ERIC Educational Resources Information Center

    Priest, Simon; Montelpare, William

    1995-01-01

    This study identified the highest heart rates attained on a ropes course for a corporate population; examined relationships between highest heart rate and other physical measures (basal heart rate, blood pressure, height, weight, body girths, cholesterol, maximum number of pushups, and heart rate after brisk walk); and developed an equation for…

  14. Oxygen consumption rate v. rate of energy utilization of fishes: a comparison and brief history of the two measurements.

    PubMed

    Nelson, J A

    2016-01-01

    Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2 ] in water is more challenging than measuring [O2 ], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption (M˙O2 ) has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included.

  15. HUBBLE SPACE TELESCOPE ON TRACK FOR MEASURING THE EXPANSION RATE OF THE UNIVERSE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    rate with an estimate of how much matter is in space. The younger age values from each team assume the Universe is at a critical density where it contains just enough matter to expand indefinitely. The higher age estimates are calculated based on a low density of matter in space. (See 'Science Background' for more information on the expanding Universe.) 'A point of great interest is whether the age of the Universe arrived at this way is really older than the independently derived ages of the oldest stars,' said Saha, an investigator on both Hubble teams. 'The numbers lean on the side that the stellar ages are a little lower, or that the hypothesis that we live in a critical density universe needs to be questioned,' said Saha. 'As further results accumulate over the next few years, we hope to tighten the constraints on these issues.' THE OBSERVATIONS The Key Project team is midway along in their three-year program to derive the expansion rate of the Universe based on precise distance measurements to galaxies. They have now measured Cepheid distances to a dozen galaxies, and are about halfway through their overall program. The Key Project team also presented a preliminary estimate of the distance to the Fornax cluster of galaxies. The estimate was obtained through the detection and measurement with the Hubble Space Telescope of pulsating stars known as Cepheid variables found in the Fornax cluster. The Fornax cluster is measured to be approximately as far away as the Virgo cluster of galaxies -- about 60 million light-years. The Key Project team member who led this effort, Caltech astronomer Barry Madore said, 'This cluster allows us to make independent estimates of the expansion rate of the Universe using a number of different techniques. All of these methods are now in excellent agreement. With Fornax we are now at turning point in this field.' The team is measuring Cepheid distances to the Virgo and Fornax clusters of galaxies as a complementary test. Their strategy

  16. Carbon accumulation in a permafrost polygon peatland: steady long-term rates in spite of shifts between dry and wet conditions.

    PubMed

    Gao, Yang; Couwenberg, John

    2015-02-01

    Ice-wedge polygon peatlands contain a substantial part of the carbon stored in permafrost soils. However, little is known about their long-term carbon accumulation rates (CAR) in relation to shifts in vegetation and climate. We collected four peat profiles from one single polygon in NE Yakutia and cut them into contiguous 0.5 cm slices. Pollen density interpolation between AMS (14)C dated levels provided the time span contained in each of the sample slices, which--in combination with the volumetric carbon content--allowed for the reconstruction of CAR over decadal and centennial timescales. Vegetation representing dry palaeo-ridges and wet depressions was reconstructed with detailed micro- and macrofossil analysis. We found repeated shifts between wet and dry conditions during the past millennium. Dry ridges with associated permafrost growth originated during phases of (relatively) warm summer temperature and collapsed during relatively cold phases, illustrating the important role of vegetation and peat as intermediaries between ambient air temperature and the permafrost. The average long-term CAR across the four profiles was 10.6 ± 5.5 g C m(-2) yr(-1). Time-weighted mean CAR did not differ significantly between wet depression and dry ridge/hummock phases (10.6 ± 5.2 g C m(-2) yr(-1) and 10.3 ± 5.7 g C m(-2) yr(-1), respectively). Although we observed increased CAR in relation to warm shifts, we also found changes in the opposite direction and the highest CAR actually occurred during the Little Ice Age. In fact, CAR rather seems to be governed by strong internal feedback mechanisms and has roughly remained stable on centennial time scales. The absence of significant differences in CAR between dry ridge and wet depression phases suggests that recent warming and associated expansion of shrubs will not affect long-term rates of carbon burial in ice-wedge polygon peatlands.

  17. Landscape scale measures of steelhead (Oncorhynchus mykiss) bioenergetic growth rate potential in Lake Michigan and comparison with angler catch rates

    USGS Publications Warehouse

    Hook, T.O.; Rutherford, E.S.; Brines, Shannon J.; Geddes, C.A.; Mason, D.M.; Schwab, D.J.; Fleischer, G.W.

    2004-01-01

    The relative quality of a habitat can influence fish consumption, growth, mortality, and production. In order to quantify habitat quality, several authors have combined bioenergetic and foraging models to generate spatially explicit estimates of fish growth rate potential (GRP). However, the capacity of GRP to reflect the spatial distributions of fishes over large areas has not been fully evaluated. We generated landscape scale estimates of steelhead (Oncorhynchus mykiss) GRP throughout Lake Michigan for 1994-1996, and used these estimates to test the hypotheses that GRP is a good predictor of spatial patterns of steelhead catch rates. We used surface temperatures (measured with AVHRR satellite imagery) and acoustically measured steelhead prey densities (alewife, Alosa pseudoharengus) as inputs for the GRP model. Our analyses demonstrate that potential steelhead growth rates in Lake Michigan are highly variable in both space and time. Steelhead GRP tended to increase with latitude, and mean GRP was much higher during September 1995, compared to 1994 and 1996. In addition, our study suggests that landscape scale measures of GRP are not good predictors of steelhead catch rates throughout Lake Michigan, but may provide an index of interannual variation in system-wide habitat quality.

  18. Recent increases in sediment and nutrient accumulation in Bear Lake, Utah/Idaho, USA

    USGS Publications Warehouse

    Smoak, J.M.; Swarzenski, P.W.

    2004-01-01

    This study examines historical changes in sediment and nutrient accumulation rates in Bear Lake along the northeastern Utah/Idaho border, USA. Two sediment cores were dated by measuring excess 210Pb activities and applying the constant rate of supply (CRS) dating model. Historical rates of bulk sediment accumulation were calculated based on the ages within the sediment cores. Bulk sediment accumulation rates increased throughout the last 100 years. According to the CRS model, bulk sediment accumulation rates were <25mg cm-2 year-1 prior to 1935. Between 1935 and 1980, bulk sediment accumulation rates increased to approximately 40mg cm -2 year-1. This increase in sediment accumulation probably resulted from the re-connection of Bear River to Bear Lake. Bulk sediment accumulation rates accelerated again after 1980. Accumulation rates of total phosphorus (TP), total nitrogen (TN), total inorganic carbon (TIC), and total organic carbon (TOC) were calculated by multiplying bulk sediment accumulation rates times the concentrations of these nutrients in the sediment. Accumulation rates of TP, TN, TIC, and TOC increased as a consequence of increased bulk sediment accumulation rates after the re-connection of Bear River with Bear Lake.

  19. Measurement of phloem transport rates by an indicator-dilution technique. [Triticum aestivum L

    SciTech Connect

    Fisher, D.B. )

    1990-10-01

    An indicator-dilution technique for the measurement of flow rates, commonly used by animal physiologists for circulation measurements, was adapted to the measurement of phloem translocation rates in the wheat (Triticum aestivum L.) peduncle. The approach is based on the observation that, during the transport of a given amount of solute, its mean concentration will be inversely proportional to flow rate. For phloem transport in the wheat peduncle, the necessary measurements are (a) the time course of tracer kinetics in the peduncle phloem, (b)the volume of sieve tubes and companion cells in the monitored segment of the peduncle, and (c) the amount of tracer transported past that point. The method was evaluated by in situ monitoring of {sup 32}PO{sub 4} transport in pulse-labeling experiments. Specific activities (i.e. {sup 32}P concentrations) of phloem exudate were in good agreement with those calculated from in situ count rates and measured phloem areas. Mass transport rates, calculated from volume flow rates and phloem exudate dry matter content, also agreed well with expected mass transport rates based on measurements of grain growth rate and net CO{sub 2} exchange by the ear. The indicator-dilution technique appears to offer good precision and accuracy for short-term measurements of phloem transport rates in the wheat peduncle and should be useful for other systems as well.

  20. Calorimeter measures high nuclear heating rates and their gradients across a reactor test hole

    NASA Technical Reports Server (NTRS)

    Burwell, D.; Coombe, J. R.; Mc Bride, J.

    1970-01-01

    Pedestal-type calorimeter measures gamma-ray heating rates from 0.5 to 7.0 watts per gram of aluminum. Nuclear heating rate is a function of cylinder temperature change, measured by four chromel-alumel thermocouples attached to the calorimeter, and known thermoconductivity of the tested material.

  1. Patient-Rated Alliance as a Measure of Therapist Performance in Two Clinical Settings

    ERIC Educational Resources Information Center

    Imel, Zac E.; Hubbard, Rebecca A.; Rutter, Carolyn M.; Simon, Gregory

    2013-01-01

    Objective: The ability to form a strong therapeutic alliance is considered a foundational skill across psychotherapies. Patient-rated measures of the alliance are now being used to make judgments about a therapist's tendency to build alliances with their patients. However, whether a patient-rated alliance measure provides a useful index of a…

  2. Predicting Ratings of Counselor Trainee Empathy with Self-Report Anxiety Measures and Skin Conductance.

    ERIC Educational Resources Information Center

    Bowman, James T.; Giesen, J. Martin

    1982-01-01

    Investigated the degree of relationship between clients' and judges' ratings of counselor trainee (N=29) empathy and self-report anxiety and skin conductance measures. Results indicated the usefulness of anxiety measures to predict counselor empathy is predicated on the criterion for rating counselor empathy. (RC)

  3. Rating Quality Studies Using Rasch Measurement Theory. Research Report 2013-3

    ERIC Educational Resources Information Center

    Engelhard, George, Jr.; Wind, Stefanie A.

    2013-01-01

    The major purpose of this study is to examine the quality of ratings assigned to CR (constructed-response) questions in large-scale assessments from the perspective of Rasch Measurement Theory. Rasch Measurement Theory provides a framework for the examination of rating scale category structure that can yield useful information for interpreting the…

  4. Stretch-rate relationships for turbulent premixed combustion LES subgrid models measured using temporally resolved diagnostics

    SciTech Connect

    Steinberg, Adam M.; Driscoll, James F.

    2010-07-15

    Temporally resolved measurements of turbulence-flame interaction were used to experimentally determine relationships for the strain-rate and curvature stretch-rate exerted on a premixed flame surface. These relationships include a series of transfer functions that are analogous to, but not equal to, stretch-efficiency functions. The measurements were obtained by applying high-repetition-rate particle image velocimetry in a turbulent slot Bunsen flame and were able to resolve the range of turbulent scales that cause flame surface straining and wrinkling. Fluid control masses were tracked in a Lagrangian manner as they interacted with the flame surface. From each interaction, the spatially and temporally filtered subgrid strain-rate and curvature stretch-rate were measured. By analyzing the statistics of thousands of turbulence-flame interactions, relationships for the strain-rate and curvature stretch-rate were determined that are appropriate for Large Eddy Simulation. It was found that the strain-rate exerted on the flame during these interactions was better correlated with the strength of the subgrid fluid-dynamic strain-rate field than with previously used characteristic strain-rates. Furthermore, stretch-efficiency functions developed from simplified vortex-flame interactions significantly over-predict the measurements. Hence, the proposed relationship relates the strain-rate on the flame to the filtered subgrid fluid-dynamic strain-rate field during real turbulence-flame interactions using an empirically determined Strain-Rate Transfer function. It was found that the curvature stretch-rate did not locally balance the strain-rate as has been proposed in previous models. A geometric relationship was found to exist between the subgrid flame surface wrinkling factor and subgrid curvature stretch-rate, which could be expressed using an empirically determined wrinkling factor transfer function. Curve fits to the measured relationships are provided that could be

  5. Collector design for measuring high intensity time variant sprinkler application rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peak water application rate in relation to soil water infiltration rate and soil surface storage capacity is important in the design of center pivot sprinkler irrigation systems for efficient irrigation and soil erosion control. Measurement of application rates of center pivot irrigation systems ha...

  6. Measurement Quality of the Chinese Early Childhood Program Rating Scale: An Investigation Using Multivariate Generalizability Theory

    ERIC Educational Resources Information Center

    Chen, Dezhi; Hu, Bi Ying; Fan, Xitao; Li, Kejian

    2014-01-01

    Adapted from the Early Childhood Environment Rating Scale-Revised, the Chinese Early Childhood Program Rating Scale (CECPRS) is a culturally comparable measure for assessing the quality of early childhood education and care programs in the Chinese cultural/social contexts. In this study, 176 kindergarten classrooms were rated with CECPRS on eight…

  7. The importance of rating scales in measuring patient-reported outcomes

    PubMed Central

    2012-01-01

    Background A critical component that influences the measurement properties of a patient-reported outcome (PRO) instrument is the rating scale. Yet, there is a lack of general consensus regarding optimal rating scale format, including aspects of question structure, the number and the labels of response categories. This study aims to explore the characteristics of rating scales that function well and those that do not, and thereby develop guidelines for formulating rating scales. Methods Seventeen existing PROs designed to measure vision-related quality of life dimensions were mailed for self-administration, in sets of 10, to patients who were on a waiting list for cataract extraction. These PROs included questions with ratings of difficulty, frequency, severity, and global ratings. Using Rasch analysis, performance of rating scales were assessed by examining hierarchical ordering (indicating categories are distinct from each other and follow a logical transition from lower to higher value), evenness (indicating relative utilization of categories), and range (indicating coverage of the attribute by the rating scale). Results The rating scales with complicated question format, a large number of response categories, or unlabelled categories, tended to be dysfunctional. Rating scales with five or fewer response categories tended to be functional. Most of the rating scales measuring difficulty performed well. The rating scales measuring frequency and severity demonstrated hierarchical ordering but the categories lacked even utilization. Conclusion Developers of PRO instruments should use a simple question format, fewer (four to five) and labelled response categories. PMID:22794788

  8. HUBBLE SPACE TELESCOPE ON TRACK FOR MEASURING THE EXPANSION RATE OF THE UNIVERSE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    rate with an estimate of how much matter is in space. The younger age values from each team assume the Universe is at a critical density where it contains just enough matter to expand indefinitely. The higher age estimates are calculated based on a low density of matter in space. (See 'Science Background' for more information on the expanding Universe.) 'A point of great interest is whether the age of the Universe arrived at this way is really older than the independently derived ages of the oldest stars,' said Saha, an investigator on both Hubble teams. 'The numbers lean on the side that the stellar ages are a little lower, or that the hypothesis that we live in a critical density universe needs to be questioned,' said Saha. 'As further results accumulate over the next few years, we hope to tighten the constraints on these issues.' THE OBSERVATIONS The Key Project team is midway along in their three-year program to derive the expansion rate of the Universe based on precise distance measurements to galaxies. They have now measured Cepheid distances to a dozen galaxies, and are about halfway through their overall program. The Key Project team also presented a preliminary estimate of the distance to the Fornax cluster of galaxies. The estimate was obtained through the detection and measurement with the Hubble Space Telescope of pulsating stars known as Cepheid variables found in the Fornax cluster. The Fornax cluster is measured to be approximately as far away as the Virgo cluster of galaxies -- about 60 million light-years. The Key Project team member who led this effort, Caltech astronomer Barry Madore said, 'This cluster allows us to make independent estimates of the expansion rate of the Universe using a number of different techniques. All of these methods are now in excellent agreement. With Fornax we are now at turning point in this field.' The team is measuring Cepheid distances to the Virgo and Fornax clusters of galaxies as a complementary test. Their strategy

  9. Fast repetition rate (FRR) fluorometer and method for measuring fluorescence and photosynthetic parameters

    DOEpatents

    Kolber, Zbigniew; Falkowski, Paul

    1995-06-20

    A fast repetition rate fluorometer device and method for measuring in vivo fluorescence of phytoplankton or higher plants chlorophyll and photosynthetic parameters of phytoplankton or higher plants by illuminating the phytoplankton or higher plants with a series of fast repetition rate excitation flashes effective to bring about and measure resultant changes in fluorescence yield of their Photosystem II. The series of fast repetition rate excitation flashes has a predetermined energy per flash and a rate greater than 10,000 Hz. Also, disclosed is a flasher circuit for producing the series of fast repetition rate flashes.

  10. Fast repetition rate (FRR) fluorometer and method for measuring fluorescence and photosynthetic parameters

    DOEpatents

    Kolber, Z.; Falkowski, P.

    1995-06-20

    A fast repetition rate fluorometer device and method for measuring in vivo fluorescence of phytoplankton or higher plants chlorophyll and photosynthetic parameters of phytoplankton or higher plants is revealed. The phytoplankton or higher plants are illuminated with a series of fast repetition rate excitation flashes effective to bring about and measure resultant changes in fluorescence yield of their Photosystem II. The series of fast repetition rate excitation flashes has a predetermined energy per flash and a rate greater than 10,000 Hz. Also, disclosed is a flasher circuit for producing the series of fast repetition rate flashes. 14 figs.

  11. A Protocol for Improved Measurement of Arterial Flow Rate in Preclinical Ultrasound

    PubMed Central

    Kenwright, D. A.; Thomson, A. J. W.; Hadoke, P. W. F.; Anderson, T.; Moran, C. M.; Gray, G. A.; Hoskins, P. R.

    2015-01-01

    Purpose: To describe a protocol for the measurement of blood flow rate in small animals and to compare flow rate measurements against measurements made using a transit time flowmeter. Materials and Methods: Measurements were made in rat and mice using a Visualsonics Vevo 770 scanner. The flow rate in carotid and femoral arteries was calculated from the time-average maximum velocity and vessel diameter. A correction factor was applied to correct for the overestimation of velocity arising from geometric spectral broadening. Invasive flow rate measurements were made using a Transonics system. Results: Measurements were achieved in rat carotid and femoral arteries and in mouse carotid arteries. Image quality in the mouse femoral artery was too poor to obtain diameter measurements. The applied correction factor in practice was 0.71–0.77. The diameter varied by 6–18% during the cardiac cycle. There was no overall difference in the flow rate measured using ultrasound and using transit-time flowmeters. The flow rates were comparable with those previously reported in the literature. There was wide variation in flow rates in the same artery in individual animals. Transit-time measurements were associated with changes of a factor of 10 during the typical 40 min measurement period, associated with probe movement, vessel spasm, vessel kinking and other effects. Conclusion: A protocol for the measurement of flow rate in arteries in small animals has been described and successfully used in rat carotid and femoral arteries and in mouse carotid arteries. The availability of a noninvasive procedure for flow rate measurement avoids the problems with changes in flow associated with an invasive procedure. PMID:27689153

  12. Measurements of Transverse Beam Diffusion Rates in the Fermilab Tevatron Collider

    SciTech Connect

    Stancari, G.; Annala, G.; Johnson, T.R.; Still, D.A.; Valishev, A.; /Fermilab

    2011-08-01

    The transverse beam diffusion rate vs. particle oscillation amplitude was measured in the Tevatron using collimator scans. All collimator jaws except one were retracted. As the jaw of interest was moved in small steps, the local shower rates were recorded as a function of time. By using a diffusion model, the time evolution of losses could be related to the diffusion rate at the collimator position. Preliminary results of these measurements are presented.

  13. Measurement of tectonic surface uplift rate in a young collisional mountain belt

    USGS Publications Warehouse

    Abbott, L.D.; Silver, E.A.; Anderson, R. Scott; Smith, R.; Ingle, J.C.; Kling, S.A.; Haig, D.; Small, E.; Galewsky, J.; Sliter, W.

    1997-01-01

    Measurement of the rate of tectonically driven surface uplift is crucial to a complete understanding of mountain building dynamics. The lack of a suitable rock record typically prevents determination of this quantity, but the unusual geology of Papua New Guinea's Finisterre mountains makes measurement of this rate possible. The tectonic surface uplift rate at the Finisterre range is 0.8-2.1 mm yr-1, approximately that expected to arise from crustal thickening.

  14. Alternate measures of replacement rates for social security benefits and retirement income.

    PubMed

    Biggs, Andrew G; Springstead, Glenn R

    2008-01-01

    Discussions of retirement planning and Social Security policy often focus on replacement rates, which represent retirement income or Social Security benefits relative to preretirement earnings. Replacement rates are a rule of thumb designed to simplify the process of smoothing consumption over individuals' lifetimes. Despite their widespread use, however, there is no common means of measuring replacement rates. Various measures of preretirement earnings mean that the denominators used in replacement rate calculations are often inconsistent and can lead to confusion. Whether a given replacement rate represents an adequate retirement income depends on whether the denominator in the replacement rate calculation is an appropriate measure of preretirement earnings. This article illustrates replacement rates using four measures of preretirement earnings: final earnings; the constant income payable from the present value (PV) of lifetime earnings (PV payment); the wage-indexed average of all earnings prior to claiming Social Security benefits; and the inflation-adjusted average of all earnings prior to claiming Social Security benefits (consumer price index (CPI) average). The article then measures replacement rates against a sample of the Social Security beneficiary population using the Social Security Administration's Modeling Income in the Near Term (MINT) microsimulation model. Replacement rates are shown based on Social Security benefits alone, to indicate the adequacy of the current benefit structure, as well as on total retirement income including defined benefit pensions and financial assets, to indicate total preparedness for retirement. The results show that replacement rates can vary considerably based on the definition of preretirement earnings used and whether replacement rates are measured on an individual or a shared basis. For current new retirees, replacement rates based on all sources of retirement income seem strong by most measures and are projected to

  15. Complex sediment deposition history on a wide continental shelf: Implications for the calculation of accumulation rates on the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Lewis, Stephen E.; Olley, Jon; Furuichi, Takahisa; Sharma, Ashneel; Burton, Joanne

    2014-05-01

    Understanding the key processes controlling the delivery, deposition and fate of sediments on continental shelves is critical to appreciate the evolution of coasts and estuaries and to interpret geological sequences. This study presents radiocarbon and Optically Stimulated Luminescence (OSL) ages of sediment cores collected from key locations offshore from the Burdekin River, Australia, the largest single source of sediment delivered to the Great Barrier Reef (GBR) lagoon. The ages show variable sediment accumulation rates at the different locations that coincide with the Holocene avulsion history of the Burdekin River. Our data show that most fine sediment (<63 μm) delivered from the Burdekin River is retained within 50 km of the mouth, a finding that contrasts previous studies which postulated that fine sediments are advected northwards via longshore drift processes. The pairing of radiocarbon and OSL ages provides insights on resuspension regimes operating on the inner shelf of the GBR. It was thought that turbidity on inshore GBR coral reefs and seagrass meadows has increased as a result of increased erosion in the adjacent catchment from agricultural development. Our data show that the age of the sediments in Cleveland Bay (derived from the radiocarbon ages from shell and organic material) can be several thousand years older than when the sediment was last deposited (OSL ages). However, the increased turbidity could conceivably be caused from ‘new biologically-produced sediment’ (i.e. particulate organic matter) as a result of increased nutrient export to the GBR. We suggest that the composition of sediment in resuspension events before and after the wet season be analysed to examine whether newly delivered organic-rich sediment can affect coral reefs and seagrass meadows.

  16. A record of barite accumulation rate for marine export productivity changes in the tropical Indian Ocean during the Mid-Pliocene--Early-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Zhou, Liping; Ma, Zhongwu; Ding, Xuan

    2016-04-01

    One of the most interesting features in the marine oxygen isotope records is the gradual shift towards heavier 18O from the Mid-Pliocene, which ends with the initiation of Northern Hemisphere glaciation (NHG) around 2.7 Ma. The lack of significant change in sea surface temperature in the tropical Indian Ocean as revealed in the previous studies does not rule out their possible contributions to this dramatic climate change during the Mid-Pliocene transition. Changing circulation systems in the region will control the supply of nutrients for the water masses which in turn determine the marine productivity. In the areas of high productivity, ocean export productivity may potentially provide a mechanism of CO2 draw-down into the deep ocean, through which contributing to the lowering of the global temperature. In this study, we present a record of barite accumulation rate (BAR) for DSDP Site 214 drilled on the Ninetyeast Ridge. Here we use the marine barite, which is formed during the decay of organism in the twilight zone, as a proxy for ocean export productivity. Our results show that the BAR of Site 214 varies between 0.25 and 1.25 mg/cm2/kyr during the period between 4 Ma and 2 Ma. Five intervals of increased BAR from 3.6 Ma to 2.4 Ma are identified with the most distinct peak centred around 3 Ma. The overall pattern does not follow either the oxygen isotope record for the Site or the sea surface temperature and subsurface temperature reconstructed with the Mg/Ca of foraminifera. This suggests that regional changes in ocean circulation and water masses may have played more important role than temperature in controlling the productivity change in the tropical Indian Ocean. The relative higher productivity around 3 Ma may imply a biogenetic process towards the intensification of NHGs.

  17. Application of Fresnel diffraction from phase steps to measurement of etching rate of transparent materials.

    PubMed

    Mahmoudi, Ali

    2015-09-10

    Based on Fresnel diffraction from phase steps, we present an optical method for real-time monitoring and measurement of thickness during the wet etching of transparent materials. It is shown experimentally that during the etching process, the visibility of diffraction fringes varies periodically with time (thickness) and the rate the etching is measured. Using dilute etching solutions, we measured an average etching rate of 5.3  nm/s for glass.

  18. Spectral composition of a measuring signal during measurements of vibration rates of a moving body

    NASA Technical Reports Server (NTRS)

    Daynauskas, I. A. I.; Slepov, N. N.

    1973-01-01

    Cybernetics diagnostics of machines and mechanisms using the spectral approach is discussed. The problem of establishing the accuracy of determination of the spectral composition is investigated. In systems with rectilinear or rotary movement, the vibrations appear in the form of movement rate vibrations, which are equivalent to frequency modulation of the signal, in proportion to the mean movement rate of the body. The case of a harmonic signal which reproduces and analyzes the characteristics of the frequency modulated signal is discussed. Mathematical models are developed to show the relationships of the parameters.

  19. Measuring Flow Rate in Crystalline Bedrock Wells Using the Dissolved Oxygen Alteration Method.

    PubMed

    Vitale, Sarah A; Robbins, Gary A

    2017-03-22

    Determination of vertical flow rates in a fractured bedrock well can aid in planning and implementing hydraulic tests, water quality sampling, and improving interpretations of water quality data. Although flowmeters are highly accurate in flow rate measurement, the high cost and logistics may be limiting. In this study the dissolved oxygen alteration method (DOAM) is expanded upon as a low-cost alternative to determine vertical flow rates in crystalline bedrock wells. The method entails altering the dissolved oxygen content in the wellbore through bubbler aeration, and monitoring the vertical advective movement of the dissolved oxygen over time. Measurements were taken for upward and downward flows, and under ambient and pumping conditions. Vertical flow rates from 0.06 to 2.30 Lpm were measured. To validate the method, flow rates determined with the DOAM were compared to pump discharge rates and found to be in agreement within 2.5%.

  20. Development of a technique for the measurement of the radon exhalation rate using an activated charcoal collector.

    PubMed

    Iimoto, Takeshi; Akasaka, Yoshinori; Koike, Yuya; Kosako, Toshiso

    2008-04-01

    A simple system to evaluate the 222Rn (radon) exhalation rate from soil has been improved. A sampling cuvette of 2.1 L is placed so that it covers the targeted ground soil, and radon emanating from the soil accumulates within the cuvette for 24 h. Its internal radon concentration is measured by the combination of an activated charcoal (PICO-RAD) and a liquid scintillation counting system. This study shows variations of the conversion factor (CF: unit Bq m(-3)/cpm) of PICO-RAD. The range of CF due to temperature (10-30 degrees C) was between -21% and +69%, and this due to humidity (30-90%) was between 0% and -15%. Humidity and radon concentration in the cuvette covering soil tended to saturate in a few hours. The above information was used to correct the CF for the evaluation. The improved system shows high reliability and can be easily applied to natural environments.

  1. Measured Thermal and Fast Neutron Fluence Rates for ATF-1 Holders During ATR Cycle 157D

    SciTech Connect

    Smith, Larry Don; Miller, David Torbet

    2016-03-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 157D which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. The fluence rates reported are for the average power levels given in the table of power history and distribution.

  2. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    NASA Technical Reports Server (NTRS)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  3. Thick target measurement of the 40Ca(alpha,gamma)44Ti reaction rate

    SciTech Connect

    Sheets, S A; Burke, J T; Scielzo, N D; Phair, L; Bleuel, D; Norman, E B; Grant, P G; Hurst, A M; Tumey, S; Brown, T A; Stoyer, M

    2009-02-06

    The thick-target yield for the {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction has been measured for E{sub beam} = 4.13, 4.54, and 5.36 MeV using both an activation measurement and online {gamma}-ray spectroscopy. The results of the two measurements agree. From the measured yield a reaction rate is deduced that is smaller than statistical model calculations. This implies a smaller {sup 44}Ti production in supernova compared to recently measured {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction rates.

  4. Comparison of measured and calculated dose rates for the Castor HAW 20/28 CG.

    PubMed

    Ringleb, O; Kühl, H; Scheib, H; Rimpler, A

    2005-01-01

    In January 2003 neutron and gamma dose rate measurements at a CASTOR HAW 20/28 CG were performed by the Bundesamt für Strahlenschutz at Gorleben. First, commercial dose rate measurement devices were used, then spectral measurements with a Bonner sphere system were made to verify the results. Axial and circumferential dose rate profiles were measured near the cask surface and spectral measurements were performed for some locations. A shielding analysis of the cask was performed with the MCNP Monte Carlo Code with ENDF/B-VI cross section libraries. The cask was modelled 'as built', i.e. with its real inventory, dimensions and material densities and with the same configuration and position as in the storage facility. The average C/E-ratios are 1.3 for neutron dose rates and 1.4 for gamma dose rates. Both the measured and calculated dose rates show the same qualitative trends in the axial and circumferential direction. The spectral measurements show a variation in the spectra across the cask surface. This correlates with the variation found in the C/E-ratios. At cask midheight good agreement between the Bonner sphere system and the commercial device (LB 6411) is found with a 7% lower derived H*(10) dose rate from the Bonner sphere system.

  5. Measuring pulse rate variability using long-range, non-contact imaging photoplethysmography.

    PubMed

    Blackford, Ethan B; Piasecki, Alyssa M; Estepp, Justin R

    2016-08-01

    Camera-based measurement of the blood volume pulse via non-contact, imaging photoplethysmography is a very popular approach for measuring pulse rate using a remote imaging sensor. Comparatively less attention has been paid to the usefulness of the method for measuring features of pulse rate variability, and even less focus has been put on the accuracy of any cardiac activity feature that can be achieved at long imager-to-subject distances. In this study, video was recorded from 19 participants, while at rest, at a distance of 25 meters from the imaging sensor. A digital camera was used to record video while cardiovascular measures of both electrical and optical physiological ground truth were recorded. Pulse rate data obtained from the imager using a common blind source separation and periodogram approach were compared to physiological ground truth signals. The quality of the recovered blood volume pulse morphology was sufficient to calculate time-domain measures of pulse rate using inter-pulse interval (IPI) time series. Following this, several features of pulse rate variability were calculated from the IPI time series and compared to those calculated from the corresponding physiological ground truth signals. Use of the time-domain data as compared to the periodogram approach to measure pulse rate reduced the error in the estimate from 1.6 to 0.2 beats per minute. Correlation analysis (r2) between the camera-based measures of pulse rate variability and ECG-derived heart rate variability ranged from 0.779 to 0.973; these results are of comparable outcome to those obtained at imager-to-subject distances of no more than 3 meters. This study demonstrates that pulse rates of less than one beat-per-minute error can be obtained when the recovered blood volume pulse morphology is of adequate quality to resolve systolic onsets for individual cardiac cycles. Further, this approach can yield data of very promising quality for estimating measures of pulse rate variability.

  6. Met-myoglobin formation, accumulation, degradation, and myoglobin oxygenation monitoring based on multiwavelength attenuance measurement in porcine meat

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien; Phan, Kien Nguyen; Lee, Jee-Bum; Kim, Jae Gwan

    2016-05-01

    We propose a simple, rapid, and nondestructive method to investigate formation, accumulation, and degradation of met-myoglobin (met-Mb) and myoglobin oxygenation from the interior of porcine meat. For the experiment, color photos and attenuance spectra of porcine meat (well-bled muscle, fat, and mixed) were collected daily to perform colorimetric analysis and to obtain the differences of attenuance between 578 and 567 nm (A578-A567) and between 615 and 630 nm (A630-A615), respectively. Oxy-, deoxy-, and met-myoglobin concentration changes over storage time were also calculated using Beer-Lamberts' law with reflectance intensities at 557, 582, and 630 nm. The change of A578-A567 was well matched with the change of myoglobin oxygenation, and the change of A630-A615 corresponded well with the formation and degradation of met-Mb. In addition, attenuation differences, A578-A567 and A630-A615, were able to show the formation of met-Mb earlier than colorimetric analysis. Therefore, the attenuance differences between wavelengths can be indicators for estimating myoglobin oxygenation and met-Mb formation, accumulation, and degradation, which enable us to design a simple device to monitor myoglobin activities in porcine meat.

  7. A novel approach to measure photodesorption rates of interstellar ice analogues. The photodesorption rate of CO ice reinvestigated

    NASA Astrophysics Data System (ADS)

    Paardekooper, D. M.; Fedoseev, G.; Riedo, A.; Linnartz, H.

    2016-12-01

    Context. In recent years photodesorption rates have been determined in dedicated laboratory experiments for a number of different interstellar ice analogues. These rates are important in order to model non-thermal desorption processes that, for example, affect gas-phase abundances of species and determine the position of photo-induced snow lines in protoplanetary disks. However, different groups using similar experiments have found significant deviating photodesorption values. Aims: Here a new measurement concept is introduced that allows photodesorption rates to be determined following a different experimental approach. The potential of this method is demonstrated using the example of pure CO ice, the solid that gives the most striking discrepancies in the published results. Methods: The new experimental approach uses laser desorption post-ionisation time-of-flight mass spectrometry. It is based on the concept that the physical and geometrical properties of the plume obtained by laser induced desorption of the ice directly depend on the original ice thickness. This allows the ice loss to be determined as function of vacuum ultraviolet (VUV) fluence, which results in a photodesorption rate. The method has the additional advantage that it records all ice species, including photoproducts generated by the VUV irradiation. As a consequence, the method introduced here is also suited to determine the overall photodesorption rate of mixed ices. Results: The photodesorption rate for CO ice at 20 K has been determined as (1.4 ± 0.7) × 10-3 molecules per incident VUV photon. This result is compared to existing experimental and theoretical values and the astronomical relevance is discussed.

  8. Can student self-ratings be compared with peer ratings? A study of measurement invariance of multisource feedback.

    PubMed

    Lee, Keng-Lin; Tsai, Shih-Li; Chiu, Yu-Ting; Ho, Ming-Jung

    2016-05-01

    Measurement invariance is a prerequisite for comparing measurement scores from different groups. In medical education, multi-source feedback (MSF) is utilized to assess core competencies, including the professionalism. However, little attention has been paid to the measurement invariance of assessment instruments; that is, whether an instrument holds the same meaning across different rater groups. To examine the measurement invariance of the National Taiwan University professionalism MSF (NTU P-MSF) in order to determine whether medical students' self-rating can be compared to their peers' rating. An eight-factor model was specified for confirmatory factor analysis to examine the construct validity of the NTU P-MSF. Cronbach's alpha was computed for the items of each domain to evaluate internal consistent reliability. The same eight-factor model was used for multi-group confirmatory factor analyses. Four hierarchical models were specified to test configural (i.e., identical factor-item relationship), metric (i.e., identical factor loadings), scalar (i.e., identical intercepts), and error variance across self-rating and peer rating groups. One hundred and twenty second-year medical students from weekly discussion groups conducted as part of a medical professionalism course agreed to use the NTU P-MSF to assess themselves or their discussion group peers. NTU P-MSF assessment scores were a good fit for the eight-factor model among self group and peer group. The Cronbach's alpha coefficients of students' NTU P-MSF scores and peers' scores ranged from 0.76 to 0.89 and 0.84 to 0.91, respectively indicating that the NTU P-MSF scores also have good internal consistent reliability between both groups. In addition, same factor structure and similar factor loadings and intercepts of NTU P-MSF scores between both groups indicate that NTU P-MSF scores had configural, metric, and scalar invariance. Thus, students' self-assessments and peer assessments can be compared in terms of

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

    PubMed

    Kandasamy, Palani; Moitra, Ranabir; Mukherjee, Souti

    2015-01-01

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

  10. Application of psychometric theory to the measurement of voice quality using rating scales.

    PubMed

    Shrivastav, Rahul; Sapienza, Christine M; Nandur, Vuday

    2005-04-01

    Rating scales are commonly used to study voice quality. However, recent research has demonstrated that perceptual measures of voice quality obtained using rating scales suffer from poor interjudge agreement and reliability, especially in the mid-range of the scale. These findings, along with those obtained using multidimensional scaling (MDS), have been interpreted to show that listeners perceive voice quality in an idiosyncratic manner. Based on psychometric theory, the present research explored an alternative explanation for the poor interlistener agreement observed in previous research. This approach suggests that poor agreement between listeners may result, in part, from measurement errors related to a variety of factors rather than true differences in the perception of voice quality. In this study, 10 listeners rated breathiness for 27 vowel stimuli using a 5-point rating scale. Each stimulus was presented to the listeners 10 times in random order. Interlistener agreement and reliability were calculated from these ratings. Agreement and reliability were observed to improve when multiple ratings of each stimulus from each listener were averaged and when standardized scores were used instead of absolute ratings. The probability of exact agreement was found to be approximately .9 when using averaged ratings and standardized scores. In contrast, the probability of exact agreement was only .4 when a single rating from each listener was used to measure agreement. These findings support the hypothesis that poor agreement reported in past research partly arises from errors in measurement rather than individual differences in the perception of voice quality.

  11. Effects of Upstream Turbulence on Measurement Uncertainty of Flow Rate by Venturi

    NASA Astrophysics Data System (ADS)

    Lee, Jungho; Yoon, Seok Ho; Yu, Cheong-Hwan; Park, Sang-Jin; Chung, Chang-Hwan

    2010-06-01

    Venturi has been widely used for measuring flow rate in a variety of engineering applications since pressure loss is relatively small compared with other measuring method. The current study focuses on making detailed estimation of measured uncertainties as the upstream turbulence affects uncertainty levels of the water flows in the closed-loop testing. Upstream turbulences can be controlled by selecting 9 different swirl generators. Measurement uncertainty of flow rate has been estimated by a quantitative uncertainty analysis which is based on the ANSI/ASME PTC 19.1-2005 standard. The best way to reduce error in measuring flow rate was investigated for evaluating its measurement uncertainty. The results of flow rate uncertainty analysis show that the case with systematic error has higher than that without systematic error. Especially the result with systematic error exhibits that the uncertainty of flow rate was gradually increased by upstream turbulence. Uncertainty of flow rate measurement can be mainly affected by differential pressure and discharge coefficient. Flow disturbance can be also reduced by increasing of the upstream straight length of Venturi.

  12. The MapCHECK Measurement Uncertainty function and its effect on planar dose pass rates.

    PubMed

    Bailey, Daniel W; Spaans, Jason D; Kumaraswamy, Lalith K; Podgorsak, Matthew B

    2016-03-01

    Our study aimed to quantify the effect of the Measurement Uncertainty function on planar dosimetry pass rates, as measured and analyzed with the Sun Nuclear Corporation MapCHECK 2 array and its associated software. This optional function is toggled in the program preferences of the software (though turned on by default upon installation), and automatically increases the dose difference tolerance defined by the user for each planar dose comparison. Dose planes from 109 static-gantry IMRT fields and 40 VMAT arcs, of varying modulation complexity, were measured at 5 cm water-equivalent depth in the MapCHECK 2 diode array, and respective calculated dose planes were exported from a commercial treatment planning system. Planar dose comparison pass rates were calculated within the Sun Nuclear Corporation analytic software using a number of calculation parameters, including Measurement Uncertainty on and off. By varying the percent difference (%Diff) criterion for similar analyses performed with Measurement Uncertainty turned off, an effective %Diff criterion was defined for each field/arc corresponding to the pass rate achieved with Measurement Uncertainty turned on. On average, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.8%-1.1% for 3%/3 mm analysis, depending on plan type and calculation technique (corresponding to an average change in pass rate of 1.0%-3.5%, and a maximum change of 8.7%). At the 2%/2 mm level, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.7%-1.2% on average, again depending on plan type and calculation technique (corresponding to an average change in pass rate of 3.5%-8.1%, and a maximum change of 14.2%). The largest increases in pass rate due to the Measurement Uncertainty function are generally seen with poorly matched planar dose comparisons, while the function has a notably smaller effect as pass rates approach 100%. The Measurement Uncertainty function, then, may

  13. The MapCHECK Measurement Uncertainty function and its effect on planar dose pass rates.

    PubMed

    Bailey, Daniel W; Spaans, Jason D; Kumaraswamy, Lalith K; Podgorsak, Matthew B

    2016-03-08

    Our study aimed to quantify the effect of the Measurement Uncertainty function on planar dosimetry pass rates, as measured and analyzed with the Sun Nuclear Corporation MapCHECK 2 array and its associated software. This optional function is toggled in the program preferences of the software (though turned on by default upon installation), and automatically increases the dose difference tolerance defined by the user for each planar dose comparison. Dose planes from 109 static-gantry IMRT fields and 40 VMAT arcs, of varying modulation complexity, were measured at 5 cm water-equivalent depth in the MapCHECK 2 diode array, and respective calculated dose planes were exported from a commercial treatment planning system. Planar dose comparison pass rates were calculated within the Sun Nuclear Corporation analytic software using a number of calculation parameters, including Measurement Uncertainty on and off. By varying the percent difference (%Diff) criterion for similar analyses performed with Measurement Uncertainty turned off, an effective %Diff criterion was defined for each field/arc corresponding to the pass rate achieved with Measurement Uncertainty turned on. On average, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.8%-1.1% for 3%/3 mm analysis, depending on plan type and calculation technique (corresponding to an average change in pass rate of 1.0%-3.5%, and a maximum change of 8.7%). At the 2%/2 mm level, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.7%-1.2% on average, again depending on plan type and calculation technique (corresponding to an average change in pass rate of 3.5%-8.1%, and a maximum change of 14.2%). The largest increases in pass rate due to the Measurement Uncertainty function are generally seen with poorly matched planar dose comparisons, while the function has a notably smaller effect as pass rates approach 100%. The Measurement Uncertainty function, then, may

  14. Different subjective awareness measures demonstrate the influence of visual identification on perceptual awareness ratings.

    PubMed

    Wierzchoń, Michał; Paulewicz, Borysław; Asanowicz, Dariusz; Timmermans, Bert; Cleeremans, Axel

    2014-07-01

    We compare four subjective awareness measures in the context of a visual identification task and investigate quantitative differences in terms of scale use and correlation with task performance. We also analyse the effect of identification task decisions on subsequent subjective reports. Results show that awareness ratings strongly predict accuracy for all scale types, although the type of awareness measure may influence the reported level of perceptual awareness. Surprisingly, the overall relationship between awareness ratings and performance was weaker when participants rated their awareness before providing identification responses. Furthermore, the Perceptual Awareness Scale was most exhaustive only when used after the identification task, whereas confidence ratings were most exhaustive when used before the identification task. We conclude that the type of subjective measure applied may influence the reports on visual awareness. We also propose that identification task decisions may affect subsequent awareness ratings.

  15. Glycolysis-induced discordance between glucose metabolic rates measured with radiolabeled fluorodeoxyglucose and glucose

    SciTech Connect

    Ackermann, R.F.; Lear, J.L. )

    1989-12-01

    We have developed an autoradiographic method for estimating the oxidative and glycolytic components of local CMRglc (LCMRglc), using sequentially administered ({sup 18}F)fluorodeoxyglucose (FDG) and ({sup 14}C)-6-glucose (GLC). FDG-6-phosphate accumulation is proportional to the rate of glucose phosphorylation, which occurs before the divergence of glycolytic (GMg) and oxidative (GMo) glucose metabolism and is therefore related to total cerebral glucose metabolism GMt: GMg + GMo = GMt. With oxidative metabolism, the {sup 14}C label of GLC is temporarily retained in Krebs cycle-related substrate pools. We hypothesize that with glycolytic metabolism, however, a significant fraction of the {sup 14}C label is lost from the brain via lactate production and efflux from the brain. Thus, cerebral GLC metabolite concentration may be more closely related to GMo than to GMt. If true, the glycolytic metabolic rate will be related to the difference between FDG- and GLC-derived LCMRglc. Thus far, we have studied normal awake rats, rats with limbic activation induced by kainic acid (KA), and rats visually stimulated with 16-Hz flashes. In KA-treated rats, significant discordance between FDG and GLC accumulation, which we attribute to glycolysis, occurred only in activated limbic structures. In visually stimulated rats, significant discordance occurred only in the optic tectum.

  16. Measurement and control of the frequency chirp rate of high-order harmonic pulses

    SciTech Connect

    Mauritsson, J.; Johnsson, P.; Lopez-Martens, R.; Varju, K.; L'Huillier, A.; Kornelis, W.; Biegert, J.; Keller, U.; Gaarde, M.B.; Schafer, K.J.

    2004-08-01

    We measure the chirp rate of harmonics 13 to 23 in argon by cross correlation with a 12 femtosecond probe pulse. Under low ionization conditions, we directly measure the negative chirp due to the atomic dipole phase, and show that an additional chirp on the pump pulse is transferred to the qth harmonic as q times the fundamental chirp. Our results are in accord with simulations using the experimentally measured 815 nm pump and probe pulses. The ability to measure and manipulate the harmonic chirp rate is essential for the characterization and optimization of attosecond pulse trains.

  17. Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 2: Why to measure glomerular filtration rate with iohexol?

    PubMed Central

    Delanaye, Pierre; Melsom, Toralf; Ebert, Natalie; Bäck, Sten-Erik; Mariat, Christophe; Cavalier, Etienne; Björk, Jonas; Christensson, Anders; Nyman, Ulf; Porrini, Esteban; Remuzzi, Giuseppe; Ruggenenti, Piero; Schaeffner, Elke; Soveri, Inga; Sterner, Gunnar; Eriksen, Bjørn Odvar; Gaspari, Flavio

    2016-01-01

    A reliable assessment of glomerular filtration rate (GFR) is of paramount importance in clinical practice as well as epidemiological and clinical research settings. It is recommended by Kidney Disease: Improving Global Outcomes guidelines in specific populations (anorectic, cirrhotic, obese, renal and non-renal transplant patients) where estimation equations are unreliable. Measured GFR is the only valuable test to confirm or confute the status of chronic kidney disease (CKD), to evaluate the slope of renal function decay over time, to assess the suitability of living kidney donors and for dosing of potentially toxic medication with a narrow therapeutic index. Abnormally elevated GFR or hyperfiltration in patients with diabetes or obesity can be correctly diagnosed only by measuring GFR. GFR measurement contributes to assessing the true CKD prevalence rate, avoiding discrepancies due to GFR estimation with different equations. Using measured GFR, successfully accomplished in large epidemiological studies, is the only way to study the potential link between decreased renal function and cardiovascular or total mortality, being sure that this association is not due to confounders, i.e. non-GFR determinants of biomarkers. In clinical research, it has been shown that measured GFR (or measured GFR slope) as a secondary endpoint as compared with estimated GFR detected subtle treatment effects and obtained these results with a comparatively smaller sample size than trials choosing estimated GFR. Measuring GFR by iohexol has several advantages: simplicity, low cost, stability and low interlaboratory variation. Iohexol plasma clearance represents the best chance for implementing a standardized GFR measurement protocol applicable worldwide both in clinical practice and in research. PMID:27679716

  18. Measuring the sedimentation rate in a magnetorheological fluid column via thermal conductivity monitoring

    NASA Astrophysics Data System (ADS)

    Cheng, Haibin; Zhang, Xiaopeng; Liu, Guizhen; Ma, Wentao; Wereley, Norman M.

    2016-05-01

    Measuring sedimentation rate of magnetorheological fluids (MRFs) is of great importance when designing and synthesizing MRFs for engineering applications. A method of characterizing sedimentation rate in an MRF column is proposed utilizing thermal conductivity correlated with particle concentration. A series of MRF samples composed of carbonyl iron particles suspended in silicone oil were prepared, and their concentrations (measured as volume fraction, ∅) and thermal conductivities, k, were tested. A calibration curve was developed to relate particle concentration, ∅, to thermal conductivity, k, using this set of MRF samples with known concentration. The particle concentration, ∅, in the MRF column was then monitored by measuring thermal conductivities (k) at a fixed location and using this calibration relationship. Finally, sedimentation rate in the MRF column was determined by examining how particle concentration varied with time. The sedimentation rate measured in the MRF column was validated using visual observation of mudline (boundary between the topmost clarified fluid zone and MRF below).

  19. The Power of String: Building a Conceptual Foundation for Measuring Rate

    ERIC Educational Resources Information Center

    Lucey, Linda Polhemus; Jennings, Sybillyn; Olson, Peter; Rubenfeld, Lester; Holmes, Aliya E.

    2007-01-01

    This article describes how Lego robotics, interactive multimedia, and a simple manipulative--string--can be offered to students through coordinated activities to help them build a conceptual foundation for measuring rate. (Contains 5 figures and 3 tables.)

  20. Comparing measurement error correction methods for rate-of-change exposure variables in survival analysis.

    PubMed

    Veronesi, Giovanni; Ferrario, Marco M; Chambless, Lloyd E

    2013-12-01

    In this article we focus on comparing measurement error correction methods for rate-of-change exposure variables in survival analysis, when longitudinal data are observed prior to the foll